and about 30 [Image Omitted]

. However, any suitable thickness may be utilized.

The first metal material may be formed adjacent to the first dielectric material as a barrier layer and may be formed from a metallic material such as TaN, Ti, TiAlN, TaC, TaCN, TaSiN, Mn, Zr, TiN, Ru, Mo, WN, other metal oxides, metal nitrides, metal silicates, transition metal-oxides, transition metal-nitrides, transition metal-silicates, oxynitrides of metals, metal aluminates, zirconium silicate, zirconium aluminate, combinations of these, or the like. The first metal material may be deposited using a deposition process such as atomic layer deposition, chemical vapor deposition, sputtering, or the like, to a thickness of between about 5 [Image Omitted] and about 200 , although any suitable deposition process or thickness may be used.

The work function layer is formed over the first metal material, and the material for the work function layer may be chosen based upon the type of device desired. Exemplary p-type work function metals that may be included include Al, TiAlC, TiN, TaN, Ru, Mo, WN, ZrSi₂, MoSi₂, TaSi₂, NiSi₂, WN, other suitable p-type work function materials, or combinations thereof. Exemplary n-type work function metals that may be included include Ti, Ag, TaAl, TaAlC, TiAlN, TaC, TaCN, TaSiN, Mn, Zr, other suitable n-type work function materials, or combinations thereof. A work function value is associated with the material composition of the work function layer, and thus, the material of the work function layer is chosen to tune its work function value so that a desired threshold voltage Vt is achieved in the device that is to be formed in the respective region. The work function layer(s) may be deposited by CVD, PVD, and/or other suitable process to a thickness of between about 5 [Image Omitted] and about 50 .

The first barrier layer may be formed adjacent to the work function layer and, in a particular embodiment, may be similar to the first metal material. For example, the first barrier layer may be formed from a metallic material such as TiN, Ti, TiAlN, TaC, TaCN, TaSiN, Mn, Zr, TaN, Ru, Mo, WN, other metal oxides, metal nitrides, metal silicates, transition metal-oxides, transition metal-nitrides, transition metal-silicates, oxynitrides of metals, metal aluminates, zirconium silicate, zirconium aluminate, combinations of these, or the like. Additionally, the first barrier layer may be deposited using a deposition process such as atomic layer deposition, chemical vapor deposition, sputtering, or the like, to a thickness of between about 5 [Image Omitted] and about 200 , although any suitable deposition process or thickness may be used.

The metal layer may be a material that is both suitable for use as a seed layer to help a subsequent filling process as well as a material that can be used to help block or reduce the transport of fluorine atoms into the work function layer. In a particular embodiment, the metal layer may be crystalline tungsten (W) that is formed free from the presence of fluorine atoms using, e.g., an atomic layer deposition process, although any suitable deposition process may be utilized. The metal layer may be formed to a thickness of between about 20 Å and about 50 Å, such as between about 30 [Image Omitted] and about 40 .

Once the metal layer has been formed, a fill material is deposited to fill a remainder of the opening. In an embodiment the fill material may be a material such as Al, Cu, AlCu, W, Ti, TiAlN, TaC, TaCN, TaSiN, Mn, Zr, TiN, Ta, TaN, Co, Ni, combinations of these, or the like, to a thickness of between about woo A and about 2000 Å, such as about 1500 Å. However, any suitable material may be utilized.

FIG. 1 additionally illustrates that, after the fill material has been deposited to fill and overfill the opening, the materials of the first dielectric material, first conductive layer, first metal material, work function layer, first barrier layer, metal layer, and fill material may be planarized to form a gate stack 113. In an embodiment the materials may be planarized with the first ILD 111 using, e.g., a chemical mechanical polishing process, although any suitable process, such as grinding or etching, may be utilized. Additionally, after the planarization the gate stack 113 may have a bottom width WB of between about to nm and about 13 nm, such as about 11 nm, although any suitable dimensions may be utilized.

After the materials of the gate stack 113 have been formed and planarized, the materials of the gate stack 113 may optionally be recessed and capped with a capping layer 115. In an embodiment the materials of the gate stack 113 may be recessed using, e.g., a wet or dry etching process that utilizes etchants selective to the materials of the gate stack 113. In an embodiment the materials of the gate stack 113 may be recessed a distance of between about 5 nm and about 150 nm, such as about 120 nm. However, any suitable process and distance may be utilized.

Once the materials of the gate stack 113 have been recessed, the capping layer 115 is deposited in order to act as an etch stop layer for subsequent processing (described further below). In an embodiment the capping layer 115 is a material such as tungsten (W) or ruthenium formed using, e.g., an atomic layer deposition process which will selectively grow on the material of the gate stack 113 without forming on other exposed surfaces. The capping layer 115 may be formed to a thickness of between about 4 nm and about 8 nm, such as about 6 nm. However, any suitable material, process of formation, and thickness may be utilized.

FIG. 2 illustrates a deposition of a first sacrificial material 201 over the capping layer 115. In an embodiment the first sacrificial material 201 is a material that may be used as a hard mask material with a high etch selectivity to a second sacrificial material 801 (not illustrated in FIG. 2 but illustrated and described below with respect to FIG. 8), the materials of the gate stack 113, the capping layer 115, a first contact material 601, the first spacers 105 (e.g., oxides such as silicon oxide) and the second spacer 107 (e.g., nitrides such as silicon nitride) without requiring another etch stop layer and with little residual material. For example, the first sacrificial material 201 may have an etch selectivity to either the first spacers 105 or the second spacers 107 of between about 9 and about 35, such as greater than about 9, such as greater than about 12, greater than about 27, or greater than about 35. Additionally, the first sacrificial material 201 may also have an etch selectivity to the second sacrificial material 801 of between about 12 and about 40, such as greater than about 12, such as greater than about 20 or greater than about 40.

Additionally, in some embodiments the first sacrificial material 201 may also be a dielectric material with good chemical mechanical polishing properties that helps to increase the integration flexibility in advanced technology nodes. In a particular embodiment the first sacrificial material 201 may be a material such as zirconium oxide (ZrO), although other suitable materials, such as silicon oxide (SiO₂), silicon nitride (SiN), aluminum oxide (AlO), silicon oxycarbide (SiOC), silicon carbon (SiC), zirconium nitride (ZrN), combinations of these, or the like, may also be utilized. The first sacrificial material 201 may be deposited using a deposition process such as plasma enhanced atomic layer deposition (PEALD), thermal atomic layer deposition (thermal ALD), plasma enhanced chemical vapor deposition (PECVD), wherein the process temperature can be held to be between about 250° C. and about 400° C. However, any suitable deposition process and process conditions may be utilized.

Bu using such materials, the height of the gate may be protected while still helping to reduce or prevent etch loss or damage from occurring during subsequent etching processes (discussed further below). Additionally, by utilizing these materials, a high oxide etch selectivity on small CD and high aspect ratio oxide etches may be achieved. Also, in embodiments which utilize a second sacrificial material 801, these materials provide high etch selectivity during subsequent etching of the second sacrificial material 801, while still providing a wide etch process window.

Once the first sacrificial material 201 has been deposited, the first sacrificial material 201 may be planarized to remove excess material. In an embodiment the first sacrificial material 201 may be planarized using, e.g., a chemical mechanical polishing process, whereby etchants and abrasives are utilized along with a rotating platen in order to react and remove the excess material of the first sacrificial material 201. However, any suitable planarization process may be utilized to planarize the first sacrificial material 201 and the first ILD layer 111.

By planarizing the first sacrificial material 201 with the first ILD layer 111, the first sacrificial material 201 is formed to have two portions: a first portion located within the first spacers 105 and a second portion located outside of the first spacers 105 within the first ILD layer 111. Additionally, while the first portion and the second portion are illustrated in FIG. 2 as being separated from each other by a dashed line, this is done for clarity, as there may or may not be a discernible interface between the first portion and the second portion of the first sacrificial material 201. In an embodiment the first portion has a first width W₁of between about 12 nm and about 15 nm, such as about 12 nm, and has a first thickness T₁of between about 20 nm and about 30 nm, such as about 22 nm. Additionally, the second portion has a second width W₂of between about 20 nm and about 28 nm, such as about 22 nm, and a second thickness T₂of between about 14 nm and about 26 nm, such as about 16 nm. However, any suitable dimensions may be utilized.

FIG. 2 also illustrates a formation of a second ILD layer 203 over the gate stacks 113 and the source/drain regions 109. The second ILD layer 203 may comprise a material such as boron phosphorous silicate glass (BPSG), although any suitable dielectrics may be used. The second ILD layer 203 may be formed using a process such as PECVD, although other processes, such as LPCVD, may alternatively be used. The second ILD layer 203 may be formed to a thickness of between about 100 Å and about 3,000 Å. Once formed, the second ILD layer 203 may be planarized using, e.g., a planarization process such as chemical mechanical polishing process, although any suitable process may be utilized.

FIG. 3A illustrates a formation of layers for a contact end cut (CMD). In a particular embodiment, a first CMD layer 301, a second CMD layer 303, and a third CMD layer 305 are formed over the second ILD layer 203. In accordance with some embodiments the first CMD layer 301 is a metal hard mask layer, which may be formed of titanium nitride, for example. The first CMD layer 301 may have a thickness in the range between about 200 Å and about 400 Å. The second CMD layer 303 may be a Low-Temperature (LT) oxide layer, which is deposited at a low temperature, for example, lower than about 100° C. The second CMD layer 303 may include silicon oxide, for example. The second CMD layer 303 may have a thickness in the range between about 300 Å and about 600 Å. The third CMD layer 305 is deposited over the second CMD layer 303, and may have a thickness between about 100 Å and about 300 Å. The third CMD layer 305 may be an amorphous silicon layer. The third CMD layer 305, however, may be formed of other materials. Each of the first CMD layer 301, the second CMD layer 303, and the third CMD layer 305 may be formed using Chemical Vapor Deposition (CVD), Atomic Layer Deposition (ALD), or the like.

Once the first CMD layer 301, the second CMD layer 303, and the third CMD layer 305 have been formed, the first CMD layer 301, the second CMD layer 303, and the third CMD layer 305 are patterned. In an embodiment the first CMD layer 301, the second CMD layer 303, and the third CMD layer 305 are pattered using, e.g., a photolithographic masking and etching process, whereby a single or tri-layer photoresist is applied and exposed to a patterned energy source (e.g., light) in order to induce a chemical reaction. After exposure, a developer is applied in order to remove either the exposed or unexposed portions to form a patterned photoresist. The pattern of the photoresist may then be transferred to the underlying third CMD layer 305 using, e.g., one or more etching processes such as reactive ion etching processes. However, any suitable etching processes may be utilized.

FIG. 3B illustrates a separate cross-sectional view of the view illustrated in FIG. 3A, in which the third CMD layer 305 is positioned to protect the first ILD layer 111 within one region between two gate stacks 113. Such protection is intended to keep the material of the first ILD layer 111 within this region as the material of the first ILD layer 111 is removed and replaced in other regions, as described further below with respect to FIGS. 4-8. FIG. 3B additionally illustrates that some of the dummy gate electrodes 117 are not fully removed (as described above with respect to FIG. 1), and may be retained in subsequent process steps.

FIG. 4 illustrates a patterning of the first CMD layer 301 and the second CMD layer 303 after the patterning of the third CMD layer 305 with the third CMD layer 305 removed from this view for clarity. In an embodiment the first CMD layer 301 and the second CMD layer 303 are patterned using, e.g., a second photolithographic masking and etching process. For example, a single or tri-layer photoresist is applied, exposed, and developed, and then one or more etching processes may be used to transfer the pattern of the photoresist to the underlying first CMD layer 301 and the second CMD layer 303. However, any suitable process may be utilized to pattern the first CMD layer 301 and the second CMD layer 303.

FIG. 5 illustrates a transference of the pattern of the first CMD layer 301 and the second CMD layer 303 to the second ILD layer 203 and the first ILD layer 111. In an embodiment the pattern of the first CMD layer 301 and the second CMD layer 303 may be transferred using a first etching process (represented in FIG. 5 by the arrows labeled 501). The first etching process 501 may be, e.g., one or more reactive ion etches using the first CMD layer 301 and the second CMD layer 303 as masks. However, any suitable method of transferring the pattern may be utilized.

However, with the inclusion of the first sacrificial material 201, the first sacrificial material 201 will act as a self aligned contact material that also acts as a masking material once the first etching process 501 has exposed the first sacrificial material 201 through the second ILD layer 203. Additionally, a portion of the first sacrificial material 201 may be etched by the first etching process 501 while the first etching process 501 removes the first ILD layer 111 and exposes the source/drain regions 109. As a result, one or more of the first sacrificial material 201 may have an indentation from the first etching process 501, but will still protect the underlying structure from the first etching process 501 while the source/drain regions 109 is exposed. The indentation may have an indentation distance D₁of between about 4 nm and about 10 nm, such as about 6 nm, although any suitable distance may be utilized.

Once the source/drain regions 109 have been exposed, an optional silicide contact (not separately illustrated) may be formed on the source/drain regions 109. The silicide contact may comprise titanium, nickel, cobalt, or erbium in order to reduce the Schottky barrier height of the contact. However, other metals, such as platinum, palladium, and the like, may also be used. The silicidation may be performed by blanket deposition of an appropriate metal layer, followed by an annealing step which causes the metal to react with the underlying exposed silicon. Un-reacted metal is then removed, such as with a selective etch process. The thickness of the silicide contact may be between about 5 nm and about 50 nm.

FIG. 6 illustrates a formation of a first contact material 601 in physical connection with the silicide contact (when present) or the source/drain regions 109. In an embodiment the first contact material 601 may be a conductive material such as cobalt, W, Al, Cu, AlCu, W, TaC, TaCN, TaSiN, Mn, Zr, TiN, Ta, TaN, Ni, Ti, TiAlN, Ru, Mo, or WN, although any suitable material, such as aluminum, copper, alloys of these, combinations of these, or the like, and may be deposited using a deposition process such as sputtering, chemical vapor deposition, electroplating, electroless plating, or the like, to fill and/or overfill the opening within the second ILD 203.

FIG. 7 illustrates that, once the first contact material 601 has been deposited, the first contact material 601 may be planarized to remove excess material. In an embodiment the first contact material 601 may be planarized using, e.g., a chemical mechanical polishing process, whereby etchants and abrasives are utilized along with a rotating platen in order to react and remove the excess material of the first contact material 601 and the first sacrificial material 201. However, any suitable planarization process may be utilized to planarize the first contact material 601 and the first sacrificial material 201.

FIG. 8 illustrates that, once the first contact material 601 has been planarized with the first sacrificial material 201, the first contact material 601 is recessed to a level below a top surface of the first sacrificial material 201. In an embodiment the first contact material 601 is recessed using a wet or dry etching process that uses one or more etchants that are selective to the material of the first contact material 601 (e.g., cobalt) without significantly removing the material of the first sacrificial material 201. The first sacrificial material 201 may be recessed a first distance D₁of between about 18 nm and about 25 nm. However, any suitable distance may be utilized.

FIG. 8 also illustrates a deposition of a second sacrificial material 801 once the first contact material 601 has been recessed. In an embodiment the second sacrificial material 801 may be a material with a high etch selectivity to the materials of the first sacrificial material 201, the first spacers 105 and the second spacers 107. For example, the second sacrificial material 801 may have an etch selectivity to the material of the first sacrificial material 201, the first spacers 105 or the second spacers 107 of greater than about 12, such as between about 12 and about 40.

In an embodiment the second sacrificial material 801 may be a dielectric such as silicon nitride, silicon oxide (SiO₂), silicon nitride (SiN), silicon carbide (SiC), aluminum oxide (AlO), aluminum nitride (AlN), zirconium oxide (ZrO), zirconium nitride (ZrN), combinations of these, or the like. However, any suitable material may be utilized. By utilizing such materials, damage to the underlying first contact material 601 can be reduced or eliminated during the etching of the second sacrificial material 801 to form a source/drain contact opening 1003 (described further below). The second sacrificial material 801 may be deposited using a deposition process such as plasma enhanced atomic layer deposition (PEALD), thermal atomic layer deposition (thermal ALD), plasma enhanced chemical vapor deposition (PECVD), wherein the process temperature can be held to be between about 250° C. and about 400° C. However, any suitable deposition and process conditions may be utilized.

The second sacrificial material 801 may be formed to fill and overfill the openings left by the recessing of the first contact material 601. Once the second sacrificial material 801 has been deposited, the second sacrificial material 801 may be planarized with the first sacrificial material 201 using, e.g., a planarization process such as a chemical mechanical polishing process, although any suitable process may be utilized. As such, the sacrificial material 801 may be formed to have a third width W₃of between about 12 nm and about 15 nm, such as about 14 nm.

Additionally, by controlling the recessing of the first contact material 601, the K value of the combination of the sacrificial materials (e.g., the first sacrificial material 201 and the second sacrificial material 801) may be controlled. In particular, by controlling a height gap H_gbetween a bottom surface of the second sacrificial material 801 and the first sacrificial material 201, the K value could be controlled, with a wider height gap H_gresulting in a lower overall K value, which affects the parasitic capacitance. In a particular embodiment the height gap H_gmay be between about 0 nm and about 15 nm, such as about 6 nm. However, any suitable height gap H_G, including no height gap, may be utilized.

After the second sacrificial material 801 has been deposited and planarized, a first etch stop layer 803 is deposited over the second sacrificial material 801. In an embodiment the first etch stop layer 803 may be a material such as silicon nitride or silicon oxycarbide, combinations of these, or the like, and may be deposited using a low temperature deposition process such as chemical vapor deposition, physical vapor deposition, or atomic layer deposition.

FIG. 9 illustrates that, once the first etch stop layer 803 has been formed, a metal gate contact opening 901 may be formed through the first etch stop layer 803 and the second sacrificial material 801 to expose the capping layer 115 (when present) or the gate stack 113 (when the capping layer 115 is not present). In an embodiment the metal gate contact opening 901 may be formed by initially placing a first photoresist 903 over the second sacrificial material 801. The first photoresist 903 may be a tri-layer photoresist with a bottom anti-reflective coating (BARC) layer 905, an intermediate mask layer 907, and a first top photosensitive layer 909. The BARC layer 905 is applied in preparation for an application of the first top photosensitive layer 909. The BARC layer 905, as its name suggests, works to prevent the uncontrolled and undesired reflection of energy (e.g., light) back into the overlying first top photosensitive layer 909 during an exposure of the first top photosensitive layer 909, thereby preventing the reflecting light from causing reactions in an undesired region of the first top photosensitive layer 909. Additionally, the BARC layer 905 may be used to provide a planar surface, helping to reduce the negative effects of the energy impinging at an angle.

The intermediate mask layer 907 may be placed over the BARC layer 905. In an embodiment the intermediate mask layer 907 is a hard mask material such as silicon nitride, oxides, oxynitrides, silicon carbide, combinations of these, or the like. The hard mask material for the intermediate mask layer 907 may be formed through a process such as chemical vapor deposition (CVD), although other processes, such as plasma enhanced chemical vapor deposition (PECVD), low pressure chemical vapor deposition (LPCVD), spin-on coating, or even silicon oxide formation followed by nitridation, may alternatively be utilized. Any suitable method or combination of methods to form or otherwise place the hardmask material may be utilized, and all such methods or combination are fully intended to be included within the scope of the embodiments. The intermediate mask layer 907 may be formed to a thickness of between about 100 Å and about 800 Å, such as about 300 Å.

In an embodiment the first top photosensitive layer 909 is applied over the intermediate mask layer 907 using, e.g., a spin-on process, and includes a photoresist polymer resin along with one or more photoactive compounds (PACs) in a photoresist solvent. The PACs will absorb the patterned light source and generate a reactant in those portions of the first top photosensitive layer 909 that are exposed, thereby causing a subsequent reaction with the photoresist polymer resin that can be developed in order to replicate the patterned energy source within the first top photosensitive layer 909.

Once each of the BARC layer 905, the intermediate mask layer 907, and the first top photosensitive layer 909 have been applied, the first top photosensitive layer 909 is exposed to a patterned energy source (e.g., light) and developed in order to create the metal gate contact opening 901 within the first top photosensitive layer 909. Once the metal gate contact opening 901 has been formed within the first top photosensitive layer 909, the first top photosensitive layer 909 may then be used as a mask to extend the pattern into the intermediate mask layer 907 and the BARC layer 905 using one or more etching processes. Similarly, once the intermediate mask layer 907 and the BARC layer 905 have been patterned, the intermediate mask layer 907 and the BARC layer 905 may be utilized as masks to extend the metal gate contact opening 901 through the first etch stop layer 803 and through the first sacrificial material 201 to expose the capping layer 115.

For example, in a particular embodiment in which the first sacrificial material 201 is zirconium oxide, the etching process to form the metal gate contact opening 901 may utilize a first etchant such as BCl₃in combination with a second etchant such as Cl₂, although any suitable etchants may be utilized. In a particular embodiment the first etchant may have a flow rate of between about 200 sccm and about 800 sccm, such as about 300 sccm, while the second etchant may be introduced at a flow rate of between about 0 sccm and about 100 sccm, such as about 40 sccm. Additionally, the second etching process 1201 may be performed at a temperature of between about 20° C. and about 80° C., such as about 50° C., and at a pressure of between about to mTorr and about 80 mTorr, such as about 30 mTorr. However, any suitable process conditions may be utilized.

However, thanks to the high etch selectivity of the first sacrificial material 201 with respect to the first spacer 105, the extension through the first sacrificial material 201 can be performed without significant damage, if any, to the first spacer 105. Additionally, with the inclusion of the capping layer 115, the extension of the metal gate contact opening 901 through the first sacrificial material 201 can be stopped without damaging the materials of the underlying gate stack 113.

FIG. 10 illustrates a removal of the first top photosensitive layer 909 and a placement of a second top photosensitive layer 1001 in order to form a source/drain contact opening 1003. In an embodiment the first top photosensitive layer 909 may be removed using, e.g., an ashing process, whereby the temperature of the first top photosensitive layer 909 is increased until the first top photosensitive layer 909 undergoes a thermal decomposition, after which the first top photosensitive layer 909 may be easily removed. However, any suitable process, such as a wet strip, may be utilized.

Once the first top photosensitive layer 909 has been removed, the second top photosensitive layer 1001 may be placed over the intermediate mask layer 907. In an embodiment the second top photosensitive layer 1001 may be similar to the first top photosensitive layer 909 such as by comprising a photoresist polymer resin along with one or more photoactive compounds (PACs). Additionally, the second top photosensitive layer 1001 may be placed in a similar fashion, such as by applying the second top photosensitive layer 1001 using a spin-coating process. However, by using a method such as spin coating, the second top photosensitive layer 1001 will additionally fill in the metal gate contact opening 901 and protect the metal gate contact opening 901 during subsequent processing.

Once in place, the second top photosensitive layer 1001 may be patterned. In an embodiment the second top photosensitive layer 1001 is patterned to be a mask for the formation of the source/drain contact opening 1003 by exposing the second top photosensitive layer 1001 with a patterned energy source (e.g., light). Once exposed, the second top photosensitive layer 1001 may be developed to pattern the source/drain contact opening 1003 into the second top photosensitive layer 1001. Once the source/drain contact opening 1003 has been formed within the second top photosensitive layer 1001, the second top photosensitive layer 1001 may then be used as a mask to extend the pattern into the intermediate mask layer 907 and the BARC layer 905 using one or more etching processes. Similarly, once the intermediate mask layer 907 and the BARC layer 905 have been patterned, the intermediate mask layer 907 and the BARC layer 905 may be utilized as masks to extend the source/drain contact opening 1003 through the first etch stop layer 803.

Additionally, once the source/drain contact opening 1003 has been extended through the first etch stop layer 803, the source/drain contact opening 1003 is then extended into the second sacrificial material 803. However, because of the selectivity of the second sacrificial material 803, the source/drain contact opening 1003 at this point extends partially through the second sacrificial material 803 and does not extend all of the way through the second sacrificial material 803.

FIG. 11 illustrates a removal of the second top photosensitive layer 1001 and a placement of a third top photosensitive layer 1101 in order to form a rail opening 1103. In an embodiment the second top photosensitive layer 1001 may be removed using, e.g., an ashing process, whereby the temperature of the second top photosensitive layer 1001 is increased until the second top photosensitive layer 1001 undergoes a thermal decomposition, after which the second top photosensitive layer 1001 may be easily removed. However, any suitable process, such as a wet strip, may be utilized.

Once the second top photosensitive layer 1001 has been removed, the third top photosensitive layer 1101 may be placed over the intermediate mask layer 907. In an embodiment the third top photosensitive layer 1101 may be similar to the first top photosensitive layer 909 such as by comprising a photoresist polymer resin along with one or more photoactive compounds (PACs). Additionally, the third top photosensitive layer not may be placed in a similar fashion, such as by applying the third top photosensitive layer not using a spin-coating process. However, by using a method such as spin coating, the third top photosensitive layer not will additionally fill in the metal gate contact opening 901 and the source/drain contact opening 1003 and protect both the metal gate contact opening 901 and the source/drain contact opening 1003 during subsequent processing.

Once in place, the third top photosensitive layer not may be patterned. In an embodiment the third top photosensitive layer not is patterned to be a mask for the formation of a rail opening 1103 by exposing the third top photosensitive layer not with a patterned energy source (e.g., light). Once exposed, the third top photosensitive layer not may be developed to pattern the rail opening 1103 into the third top photosensitive layer not. Once the rail opening 1103 has been formed within the third top photosensitive layer not, the third top photosensitive layer not may then be used as a mask to extend the pattern into the intermediate mask layer 907 and the BARC layer 905 using one or more etching processes. Similarly, once the intermediate mask layer 907 and the BARC layer 905 have been patterned, the intermediate mask layer 907 and the BARC layer 905 may be utilized as masks to extend the rail opening 1103 through the first etch stop layer 803 and through the first sacrificial material 201 to expose the capping layer 115.

Additionally, once the rail opening 1103 has been extended through the first etch stop layer 803, the rail opening 1103 is then extended into the second sacrificial material 803. However, because of the selectivity of the second sacrificial material 803, the rail opening 1103 at this point extends partially through the second sacrificial material 803 and does not extend all of the way through the second sacrificial material 803.

FIG. 12 illustrates that, once the metal gate contact opening 901, the source/drain contact opening 1003, and the rail opening 1103 have been formed, the third top photosensitive layer 1101 is removed. In an embodiment the third top photosensitive layer 1101 may be removed using, e.g., an ashing process, whereby the temperature of the third top photosensitive layer 1101 is increased until the third top photosensitive layer 1101 undergoes a thermal decomposition, after which the third top photosensitive layer 1101 may be easily removed. However, any suitable process, such as a wet strip, may be utilized.

Once the third top photosensitive layer 1101 has been removed, a second etching process (represented in FIG. 12 by the arrows labeled 1201) may be utilized to extend the source/drain contact opening 1003 and the rail opening 1103 through the second sacrificial material 803. In an embodiment the second etching process 1201 may be, e.g., a dry etch such as a reactive ion etch using etchants that are selective to the material of the second sacrificial material 803 (e.g., SiN). However, any suitable process may be utilized.

After the source/drain contact opening 1003 and the rail opening 1103 have been fully extended, a pre-clean may be performed. In an embodiment the pre-clean process may be either a plasma or non-plasma process that is utilized to clean and remove any remaining residues left over after the third top photosensitive layer 1101 has been removed.

FIG. 13A illustrates a filling of the metal gate contact opening 901, the source/drain contact opening 1003, and the rail opening 1103. In an embodiment the metal gate contact opening 901, the source/drain contact opening 1003, and the rail opening 1103 may be filled with a conductive material 1301 such as cobalt, Al, Cu, AlCu, W, Ti, TiAlN, TaC, TaCN, TaSiN, Mn, Zr, TiN, Ta, TaN, Ni, combinations of these, or the like, in order to form vias and rails. The conductive material 1301 may be deposited using a deposition or plating process. However, any suitable process or material may be utilized.

FIG. 13A additionally illustrates that, after the conductive material 1301 has been deposited to fill and overfill the openings, the conductive material 1301 and the first etch stop layer 803 may be planarized. In an embodiment the materials may be planarized with the first ILD 111 using, e.g., a chemical mechanical polishing process, although any suitable process, such as grinding or etching, may be utilized. The planarizing forms a gate contact 1303, a source/drain contact 1305, and a rail contact 1307.

FIG. 13B illustrates the cross-sectional view of FIG. 3B (described above). As can be seen, in FIG. 13B a portion of the conductive material 1301 extends over the remaining dummy gate electrode 117 and the remaining portion of the first ILD layer 111. However, any suitable design may be utilized.

By enhancing the etch selectivity between the various materials as described above, the final height of the first sacrificial material 201 may be reduced to a first height H₁over the first spacers 105 of between about 3 nm and about 10 nm, such as about 5 nm and an overall second height H₂of between about 18 nm and about 30 nm, such as about 22 nm. As such, by reducing the height of the first sacrificial material 201, the overall height of the gate (including the gate stack 113, the capping layer 115, and the first sacrificial material 201) may be reduced to a third height H₃of between about 50 nm and about 80 nm, such as about 60 nm. Additionally, the aspect ratio of the gate (including the gate stack 113, the capping layer 115, and the first sacrificial material 201) may be reduced to be between about 4 and about 7, such as about 5.

By lowering the gate height requirement, the front end of line etching and clean process window will be enhanced. For example, with less etching needed, etch residues will be reduced while poly line collapsing (with reduced or no lateral damage) and bending issues (e.g., bowing) will be reduced and the process will also provide a more robust etch process window in the middle end of line etching process. Such improvements can be achieved with a wider etch process condition control while also leading to an improved yield.

FIG. 14 illustrates another embodiment in which a helmet material 1401 is utilized to further enhance the selectivity of the first sacrificial material 201 during the etching process. In this embodiment, once the first sacrificial material 201 has been deposited (as described above with respect to FIG. 2), instead of planarizing the first sacrificial material 201 to be planar with the first ILD layer 111, the first sacrificial material 201 is planarized to be planar with each of the first ILD layer 111, the first spacers 105, and the second spacers 107. As such, the first sacrificial material 201 is formed to have the first portion with the first width W₁and the first thickness T₁.

Once the first sacrificial material 201 has been planarized, the helmet material 1401 is deposited. In an embodiment the helmet material 1401 helps to enhance the etch selectivity of the surrounding materials and may have an etch selectivity to each of the first sacrificial material 201, the first spacer 105, the second spacer 107, and the second sacrificial material 801 of greater than about 12. In particular embodiments the helmet material 1401 comprises a material such as silicon, silicon nitride, silicon oxide, silicon carbide, aluminum oxide, aluminum nitride, zirconium oxide, yttrium silicon oxide (YSiO), yttrium oxide (Y₂O₃), combinations of these, or the like. However, any suitable material may be utilized.

In another embodiment the added protection afforded by the use of the helmet material 1401 may be achieved by using the same material as the material utilized for the first sacrificial material 201 (described above with respect to FIG. 2). In this embodiment, the helmet material 1401 is utilized to increase the thickness of the first sacrificial material 201 by the thickness of the helmet material 1401. Such an embodiment would be a separate and different method of obtaining the structure illustrated in FIG. 2. By utilizing the same material, the first spacer 105 and the second spacer 107 may be protected during subsequent etching process from bad photo overlays and bad critical dimension uniformity (CDU).

The helmet material 1401 may be deposited using a deposition process such as plasma enhanced atomic layer deposition (PEALD), thermal atomic layer deposition (thermal ALD), plasma enhanced chemical vapor deposition (PECVD). Additionally, during the deposition process the process temperature can be held to be between about 250° C. and about 400° C. However, any suitable deposition and process conditions may be utilized.

Once the helmet material 1401 has been deposited, the helmet material 1401 can be patterned such that the helmet material 1401 is located over the gate stack 113, the first spacers 105, and the second spacers 107, while exposing the first ILD layer 111 between the gate stacks 113 for further processing. In an embodiment the helmet material 1401 is patterned using a photolithographic masking and etching process. However, any suitable method of patterning the helmet material 1401 may be utilized.

FIG. 15 illustrates that, once the helmet material 1401 has been deposited and patterned, the remainder of the process described above with respect to FIGS. 2-13 may be continued. However, with the added presence of the helmet material 1401, a larger etch selectivity may be achieved during the etching processes. Such added etch selectivity helps to prevent damage during the etching processes.

FIG. 16 illustrates yet another embodiment similar to the embodiment described above with respect to FIGS. 14-15. However, in this embodiment, while the first sacrificial material 201 is planarized with each of the first ILD layer 111, the first spacers 105, and the second spacers 107 (as described above with respect to FIG. 14), the helmet material 1401 is not deposited. As such, the first sacrificial material 201 may be formed with planar sidewalls. Further, by removing the process steps related to the helmet material 1401, a simpler process may be obtained.

Additionally, while many embodiments have been discussed in order to enhance the selectivity of the various materials to achieve a smaller gate height, a wide variety of combinations may be achieved between the materials of the first sacrificial material 201, the first spacers 105 (or the second spacers 107), the second sacrificial material 801, and the helmet material 1401. Table 1 below, without limiting the embodiments described herein, illustrate some of the various embodiments that may be utilized for each of the materials.