In some embodiments, a pH adjusting agent may be included to obtain a preselected pH of an acid. For example, a pH adjusting agent can be added to an acid of the present disclosure. In some embodiments, pH adjusting agents may be provided in any amount necessary to obtain a desired pH value in the final composition of the acid. Acidic pH adjusting agents can be organic acids, including amino acids, and inorganic mineral acids. Non-limiting examples of acidic pH adjusting agents include acetic acid, citric acid, fumaric acid, glutamic acid, glycolic acid, hydrochloric acid, lactic acid, nitric acid, phosphoric acid, sodium bisulfate, sulfuric acid, and the like, and combinations thereof. In some embodiments, all organic acids are contemplated for use as pH adjusting agents. Non-limiting examples of alkaline pH adjusting agents include alkali metal hydroxides, such as sodium hydroxide, and potassium hydroxide; ammonium hydroxide; organic bases; and alkali metal salts of inorganic acids, such as sodium borate (borax), sodium phosphate, sodium pyrophosphate, and the like, and mixtures thereof.

FIG. 4 is a schematic illustration of a tool for carrying out processes for forming features described herein, in accordance with the present technology. Referring now to FIG. 4, and integrated tool 720 can be provided to carry out a number of process steps involved in the formation of microfeatures on wafers. Below is described one possible combination of processing stations that could be embodied in a processing tool platform sold under the trademark RAIDER® by Applied Materials, Inc. of Santa Clara, Calif. Other processing tool platforms could be configured in similar or different manners to carry out metallization steps such as those described below. Referring to FIG. 4, an exemplary integrated processing tool such as tool 720 includes stations to carry out a pre-wet process 722, optional metal deposition such as copper deposition process 724, under bump metallization process 726, rinse process 728, alloy deposition process 730, and a spin-rinse-dry process 732. The chambers for carrying out such process sequences can be arranged in various configurations. Microelectronic workpieces are transferred between the chambers through the use of robotics (not shown). The robotics for the tool 720 are designed to move along a linear track. Alternatively, the robotics can be centrally mounted and designed to rotate to access the input section 736 and the output section 738 of tool 720. Processing tool such as tool 720 is capable of being programmed to implement user entered processing recipes and conditions.

The rinse chamber or station for rinse process 728 and spin-rinse-dry chamber or station for spin-rinse-dry process 732 may include the acid as described herein and can be of the type available from numerous manufacturers for carrying out such process steps. Examples of such chambers include spray processing modules and immersion processing modules available in conjunction with the RAIDER® ECD system. The optional metal such as copper deposition chamber for optional copper deposition process 724, under bump metallization chamber for under bump metallization process 726 and metal alloy deposition chamber alloy for alloy deposition process 730 can be provided by numerous electroplating and electroless deposition chambers such as those available as immersion processing modules and electroplating processing reactors for the RAIDER® ECD system.

FIGS. 5A-5D are process flow diagrams of a method of reducing cross-contamination from a wafer 100, in accordance with the present technology. As shown in FIGS. 5A-5D, the wafer 100 may be removed from the electroplating processor. In some embodiments, the same method may be performed on a seal (such as seal 46 of FIG. 3). In FIG. 5A, the wafer 100 has residual electroplating solution RS on its surface. One skilled in the art will understand that FIGS. 5A-5D are simplified diagrams, and any amount of residual electroplating solution RS may be present on the wafer 100 (or seal) upon its removal from the electroplating solution.

In FIG. 5B, the wafer 100 is rinsed with an acid (or rinse agent) A. In some embodiments, the acid A is delivered through a rinsate line (or tube) 505. In some embodiments, the acid A is an MSA mixture. In some embodiments, the acid A is carbonic acid. In some embodiments, the acid A has a pH ranging from about 0 to about 5.5. In some embodiments, the acid A has a pH of 4 or lower. In some embodiments, the acid A has a pH of 2 or lower. In FIG. 5C, the residual electroplating solution RS and the acid A mix together to form a rinsate R. In FIG. 5D, the rinsate R is removed from the wafer 100, such as with a tool as shown in FIG. 4.

FIG. 6A is an example system for mixing an acid A, in accordance with the present technology. In some embodiments, the acid A may be mixed before it is used to rinse the wafer 100 (or the seal, as described herein). In some embodiments, the mixing system includes at least two reservoirs 510A, 510B. In some embodiments, a first reservoir 510A of the at least two reservoirs 510A, 510B is configured to hold concentrated acid (or acid precursor) CA. In some embodiments, a second reservoir 510B of the at least two reservoirs 510A, 510B is configured to water W. In some embodiments, water W is deionized (DI) water.

In some embodiments, the mixing system mixes the acid precursor CA with water W by directing both acid precursor CA and water W into a rinsate tube 505 having a sufficient length L. In some embodiments, the sufficient length is any length that allows for the acid precursor CA and the water W to mix into a homogeneous acid mixture. In some embodiments, the length L is between about 10 cm and 3 meters.

FIG. 6B is another example system for mixing an acid, in accordance with the present technology. In some embodiments, the acid A may be mixed before it is used to rinse the wafer 100 (or the seal, as described herein). In some embodiments, the mixing system includes at least two reservoirs 510A, 510B. In some embodiments, a first reservoir 510A of the at least two reservoirs 510A, 510B is configured to hold concentrated acid (or acid precursor) CA. In some embodiments, a second reservoir 510B of the at least two reservoirs 510A, 510B is configured to water W. In some embodiments, water W is deionized (DI) water. In some embodiments, the mixing system further includes a rinsate tube 505, a mixing chamber 520, and a static mixer 515.

In operation, acid precursor CA and water W may be mixed in the mixing chamber 520 with a static mixer, before flowing or being directed into the rinsate tube 505. In such embodiments, the acid precursor CA and the water W are mixed by the static mixer 520 to form the homogenous acid A.

FIG. 6C is yet another example system for mixing an acid, in accordance with the present technology. In some embodiments, the acid A may be mixed before it is used to rinse the wafer 100 (or the seal, as described herein). In some embodiments, the mixing system includes at least two reservoirs 510A, 510B. In some embodiments, a first reservoir 510A of the at least two reservoirs 510A, 510B is configured to hold concentrated acid (or acid precursor) CA. In some embodiments, a second reservoir 510B of the at least two reservoirs 510A, 510B is configured to water W. In some embodiments, water W is deionized (DI) water.

In some embodiments, the mixing system further includes one or more injection valves 530A, 530B, each configured to injection mix the acid precursor and/or the water in an injection mixing chamber 525, and a rinsate tube 505. In some embodiments, the injection valves may be configured to injection mix the acid precursor CA and the water W to form a homogenous acid A in the injection mixing chamber 525. The acid A may then flow through the rinsate tube 505 onto the wafer (or seal).

FIG. 7 is a method of reducing cross-contamination of a wafer, in accordance with the present technology. It should be understood that method 700 may be carried out with any of the systems disclosed herein. Furthermore, any of the methods illustrated in FIGS. 7-10 may be carried without all the illustrated steps or with additional steps. In some embodiments, method 700 may include an electroplating processor (such as electroplating processor 50), electroplating solution (such as electroplating solution ES), a wafer (such as wafer 100), a seal (such as seal 46), residual electroplating solution (such as residual electroplating solution RS), an acid (such as acid A), and/or a rinsate (such as rinsate R).

In block 705, the wafer (or seal) is removed from the electroplating solution. In some embodiments, when the wafer is removed from the electroplating solution, residual electroplating solution (such as shown in FIG. 5A) is present on the wafer.

In block 710, the wafer (or seal) is rinsed with acid. In some embodiments, the acid mixes with the residual electroplating solution to form a rinsate. In some embodiments, the pH of the residual electroplating solution and pH of the acid may be a value between 2 and 4.5. In some embodiments, the pH of the residual electroplating solution and pH of the acid may be similar such as, for example, within a pH value of plus or minus 2, 1, 0.5, or 0.2 to 2.0. In some embodiments, the pH of the residual electroplating solution may be about 3, and the pH of the acid may be about 5. In some embodiments, the pH of the residual electroplating solution may be about 3.5, and the pH of the acid may be about 3.5 to 4.5. In some embodiments, the pH of the residual electroplating solution may be about 4, and the pH of the acid may be about 4. In some embodiments, the pH of the electroplating solution may be below 1, and the pH of the acid may be about 2 for the purpose of reducing cross-contamination. In some embodiments, the pH of the acid may be equal or similar to the pH of the electroplating solution. In some embodiments, the acid may be selected from hydrogen bromide (BrH), hydrogen iodide (HI), hydrochloric acid (HCl), nitric acid (HNO₃), nitrous acid (HNO₂), phosphoric acid (H₃PO₄), sulfuric acid (H₂SO₄), boric acid (H₃BO₃), hydrofluoric acid (HF), hydrobromic acid (HBr), perchloric acid (HClO₄), hydroiodic acid (HI), and combinations thereof. In some embodiments, the acid is an acid solution comprising carbonic acid (H₂CO₃). In some embodiments, carbonic acid is applied as an acid, wherein the pH of the acid is similar or somewhat higher than the pH of the electroplating solution or electrolyte. In some embodiments, a carbonic acid rinse agent is formed by dissolving carbon dioxide in water and under pressure to achieve a pH between about 3 and 4. In some embodiments, carbon dioxide may also be injected directly in water to form carbonic acid or may be pressurized on one side of a permeable membrane with water on the other side of the membrane.

In block 715, the rinsate is removed from the wafer, with any of the methods described herein.

FIG. 8 is another method of reducing cross-contamination of a wafer, in accordance with the present technology. It should be understood that method 800 may be carried out with any of the systems disclosed herein. In some embodiments, method 800 may include an electroplating processor (such as electroplating processor 50), electroplating solution (such as electroplating solution ES), a wafer (such as wafer 100), a seal (such as seal 46), residual electroplating solution (such as residual electroplating solution RS), an acid (such as acid A), and/or a rinsate (such as rinsate R). In some embodiments, the method 800 may further be carried out by any of the mixing systems disclosed and illustrated in FIGS. 6A-6C.

In block 805, the wafer (or seal) is removed from the electroplating solution. In some embodiments, when the wafer is removed from the electroplating solution, residual electroplating solution (such as shown in FIG. 5A) is present on the wafer.

In block 810, the acid is mixed. As described herein, in some embodiments, the acid is mixed by directing acid precursor and water down a rinse line of a sufficient length to form a homogenous acid. In some embodiments, the acid is mixed with a static mixer. In yet other embodiments, the acid may be mixed by injection mixing.

In block 815, the wafer (or seal) is rinsed with acid. In some embodiments, the acid mixes with the residual electroplating solution to form a rinsate. The acid may be any of the acids described herein. In some embodiments, as disclosed herein, the residual electroplating solution and the acid may have similar pH to one another.

In block 815, the rinsate is removed from the wafer, with any of the methods described herein.

FIG. 9 is another method of reducing cross-contamination of a wafer, in accordance with the present technology. It should be understood that method 700 may be carried out with any of the systems disclosed herein. In some embodiments, method 700 may include an electroplating processor (such as electroplating processor 50), electroplating solution (such as electroplating solution ES), a wafer (such as wafer 100), a seal (such as seal 46), residual electroplating solution (such as residual electroplating solution RS), an acid (such as acid A), and/or a rinsate (such as rinsate R).

In block 905, the wafer (or seal) is rinsed with MSA. In some embodiments, the wafer or seal may be removed from the electroplating solution. In some embodiments, methane sulfonic acid (MSA) is a suitable acid in accordance with the present disclosure. In some embodiments, the acid comprises or consists of methane sulfonic acid. For example, methane sulfonic acid (pH of about 2 and a concentration of approximately 20 g/L methane sulfonic acid (MSA) in water) may be provided in an amount sufficient to prevent the formation of a precursor layer and/or subsequent plate-up. In one embodiment, methane sulfonic acid is a suitable acid for use in accordance with the present disclosure, wherein the methane sulfonic acid has a concentration of at least 3.6 g/L and solution thereof has a pH of about 3. In some embodiments, the acid such as methane sulfonic acid (MSA) is contacted with a surface in need thereof for 10 seconds or more, or a duration sufficient to displace the bulk of the plating chemistry from the surface being cleaned.