The illustrative leak check employs the illustrative pressure sensor P located in the process chamber 12. However, it will be appreciated that the pressure sensor could be located anywhere in the gas path that is downstream of the downstream valve VD. If there are multiple process gas lines feeding into a mixing manifold located upstream of the final valve VF (e.g. the embodiment of FIGS. 3 and 4), then the pressure sensor may be suitably in the mixing manifold or downstream of the final valve VF, for example. Typically, the process chamber 12 will include the illustrative pressure sensor P to monitor (and possibly provide feedback control of) the pressure in the process chamber 12 during the processing of wafers, and hence this pressure sensor P is conveniently available for use in the automated leak check. It will also be appreciated that the described leak check method is merely an illustrative example, and that other automated or semiautomated leak check methods can additionally or alternatively be employed. For example, if the process chamber 12 includes a gas analyzer or gas sniffer sensor that is sensitive to a particular gas species, then this sensor could be used in a leak check in conjunction with a dose of that gas species manually applied external to the process gas piping to detect a leak.

As seen in part (B), with both the upstream valve VU and the downstream valve VD closed, the leak check is only performed up to the downstream pneumatic valve VD, and will not detect a leak in the upstream valve VU or the portion of piping between the upstream valve VU and the downstream valve VD. For example, the leak check will not detect a leak in the mass flow controller MFC. As previously noted, the mass flow controller MFC is a complex precision instrument which typically includes an electrically adjustable valve and a mass flow sensor which may include components such as a capillary tube and a built-in heater. Hence, the mass flow controller MFC can be a relatively common location of a leak. The leak check performed on the embodiment of FIG. 1 parts (A) and (B) in the configuration shown in part (B) will also not detect a leak in the upstream valve VU.

The valve control of the embodiment of FIG. 1 parts (A) and (B) is advantageous for use during processing of semiconductor wafers using the semiconductor wafer processing tool, and during some other types of maintenance. Preprogrammed wafer processing and/or tool maintenance recipes may be written for this design in which a single control signal delivered by the single electrically actuated valve EV opens both the upstream and downstream valves VU and VD together. Hence, replacing this single electrically actuated valve EV with two electrically actuated valves for controlling the upstream valve VU and the downstream valve VD respectively would entail modifying these preprogrammed recipes. Additionally, such a modification would involve duplication of the pneumatic control line to provide two separate pneumatic control lines for the upstream valve VU and the downstream valve VD, respectively.

A second embodiment of a semiconductor wafer processing tool, which is diagrammatically shown in FIG. 1 parts (C) and (D), provides a further benefit with respect to leak checking, while advantageously retaining the single electrically actuated valve EV for closing both the upstream and downstream valves VU and VD together for use during wafer processing and other maintenance tasks. Accordingly, the preprogrammed recipes for wafer processing and maintenance (other than the leak checking program) can be used without modification, with such programs still controlling only the single electrically actuated valve EV. The second embodiment shown in parts (C) and (D) includes many of the same components as the first embodiment of parts (A) and (B), including the gas source 10, the normally closed pneumatic upstream valve VU, the normally closed pneumatic downstream valve VD, the process chamber 12 with pressure sensor P, and the pneumatic control line 20 having trunk 22 controlled by electrically actuated valve EV, upstream branch 24 connected to deliver the pneumatic pressure 28 to the upstream valve VU, and a downstream branch 26 connected to deliver the pneumatic pressure to the downstream valve VD.

However, the second embodiment of the semiconductor wafer processing tool shown in FIG. 1 parts (C) and (D) additionally includes a relay 30 controlled by an electrical actuator EA. The relay 30 controls the pneumatic pressure 28 through the upstream branch 24 that is connected with the upstream valve VU. The relay 30 is switchable by action of the electrical actuator EA between a closed position which blocks the pneumatic pressure 28, and an open position which passes the pneumatic pressure 28. In each of FIG. 1 parts (C) and (D), the relay 30 is closed, thereby passing the pneumatic pressure 28 through the upstream branch 24 if the pneumatic pressure 28 is being passed through the trunk 22 by action of the electrically actuated valve EV. As such, with the relay 30 closed the second embodiment of a semiconductor wafer processing tool shown in FIG. 1 part (C) operates identically with the operation of the first embodiment of a semiconductor wafer processing tool shown in FIG. 1 part (A); and likewise the second embodiment shown in FIG. 1 part (D) operates identically with the operation of the first embodiment shown in FIG. 1 part (B).

The relay 30 and actuator EA may, for example, be embodied as an electrically actuated valve. Note that the relay 30 in its open position corresponds to a valve implementing the relay 30 being closed, thereby blocking the pneumatic pressure from passing through the upstream branch 24 to open the upstream valve VU; whereas, the relay 30 in its closed position corresponds to the valve implementing the relay 30 being open, thereby passing the pneumatic pressure (if present in the trunk 22) through the upstream branch 24 to open the upstream valve VU.

FIG. 1 part (C) thus shows the operating configuration of the process gas line of the second embodiment, in which the electrically actuated valve EV is open to apply the pneumatic pressure 28 to both the upstream and downstream pneumatic valves VU and VD via the pneumatic control line 20. Since the relay 30 is closed in the operating configuration of part (C), the pneumatic pressure 28 in the trunk 22 of the pneumatic control line 20 is transferred through the upstream branch 24 to actuate closure of the upstream valve VU, as previously described for the operating configuration of the first embodiment shown in part (A).

FIG. 1 part (D) shows the same leak check configuration for the second embodiment as that shown in part (B) for the first embodiment. In this configuration the electrically actuated valve EV is closed, so that the pneumatic pressure is not applied through the trunk 22 of the pneumatic control line 20 and hence is also not applied to either the upstream branch 24 or the downstream branch 26. Both the upstream valve VU and the downstream valve VD are therefore in their normally closed positions. As already described for this configuration of the first embodiment shown in part (B), this leak checking configuration of part (D) enables leak checking up to the downstream valve VD, but does not allow leak checking up to the upstream valve VU. This is because the closed downstream valve VD will prevent the leak check from detecting any leak in the mass flow controller MFC or any leak in the upstream valve VU.

It is also noted that while FIG. 1 part (D) shows the leak check configuration with the relay 30 in its closed position, the setting of the relay 30 does not actually matter in the leak checking configuration of part (D), since the pneumatic pressure is not present in the trunk 22 of the pneumatic control line 20. Hence, if the configuration shown in part (D) is modified by opening the relay 30 this has no effect on the leak check.

More generally, review of FIG. 1 parts (C) and (D) demonstrates that with the relay 30 closed, the pneumatic control of the upstream and downstream valves VU and VD of the second embodiment is exactly the same as the pneumatic control of the upstream and downstream valves VU and VD of the first embodiment. That is, the single electrically actuated valve EV controls both upstream and downstream valves VU and VD together. When the electrically actuated valve EV is open as shown in FIG. 1 part (C), the pneumatic pressure 28 is applied to both pneumatic valves VU and VD so as to open both the upstream and downstream valves VU and VD together. Conversely, when the electrically actuated valve EV is closed as shown in FIG. 1 part (D), the pneumatic pressure is removed from both pneumatic valves VU and VD so as to cause both upstream and downstream valves VU and VD to revert to their normally closed position together. Consequently, preprogrammed recipes written for the first embodiment of parts (A) and (B) for performing wafer processing or various maintenance operations, which are written in expectation that the single electrically actuated valve EV controls both upstream and downstream valves VU and VD together, can be used without modification with the second embodiment of parts (C) and (D) whenever the relay 30 is closed.

With reference now to FIG. 2, the purpose of the relay 30 is described. FIG. 2 illustrates the second embodiment (that is, the same embodiment as that of FIG. 1 parts (C) and (D)) in a second leak checking configuration. In this second leak checking configuration, the electrically actuated valve EV is open to pass the pneumatic pressure 28, and the relay 30 is open to block the pneumatic pressure 28 from reaching the upstream valve VU. Consequently, the pneumatic pressure 28 passes through the downstream branch 26 and opens the downstream valve VD, but is blocked by the open relay 30 from opening the upstream valve VU. The result is that a leak check performed with the semiconductor wafer processing tool in the configuration of FIG. 2 can detect a leak up to and including the upstream valve VU.

Moreover, by performing a first leak check using the configuration of FIG. 1 part (D) and a second leak check using the configuration of FIG. 2, a leak can be identified as being either: (i) downstream of (and possibly including) the downstream valve VD, or (ii) between (and possibly including) the upstream valve VU and the downstream valve VD. To do so, the following pattern can be used. If the leak is detected using both the configuration of FIG. 1 part (D) and the configuration of FIG. 2, then the leak is identified as being downstream of (or possibly at) the downstream valve VD. This is because a leak further upstream would not be detected by a leak check using the configuration of FIG. 1 part (D). On the other hand, if the leak is detected only using the configuration of FIG. 2 but not using the configuration of FIG. 1 part (D), then the leak is identified as being at the upstream valve VU or between the upstream valve VU and the downstream valve VD (for example, possibly at the mass flow controller MFC). This is because if the leak was further downstream then it would also have been detected using the configuration of FIG. 1 part (D).

With reference to FIG. 1 parts (C) and (D) and FIG. 2, in some embodiments the electrically actuated valve EV and the relay 30 and its electrical actuator EA, along with a portion of the pneumatic control line 20, are constructed on a circuit board, support board, or the like to form a unitary integrated circuit (IC) controller 32. In this way, an existing semiconductor wafer processing tool can be upgraded to provide the functionality of the second leak check performed with the configuration of FIG. 2 merely by replacing the electronic valve EV with the IC controller 32.

The first embodiment of FIG. 1 parts (A) and (B) and the second embodiment of FIG. 1 parts (C) and (D) and FIG. 2 include a single process line comprising the mass flow controller MFC and normally closed pneumatic valves VU and VD that delivers a process gas from the gas source 10 to the process chamber 12.

With reference to FIGS. 3 and 4, a semiconductor wafer processing tool according to a third embodiment is shown, which includes multiple process gas lines, namely a hydrogen (H₂) gas line, a nitrogen (N₂) gas line, and a helium (He) gas line. Note that FIGS. 3 and 4 diagrammatically show gas sources 10 which will correspond to a hydrogen gas source (e.g. H₂cylinder) connected to the H₂process gas line, a nitrogen gas source (e.g. N₂cylinder) connected to the N₂process gas line, and a helium gas source (e.g. He cylinder) connected to the He process gas line. In a large semiconductor foundry, one or more of these process gases might also be supplied as a “house” gas source from gas distribution tubing routed through the fab. Each of these process gas lines includes a mass flow controller MFC and upstream and downstream normally closed pneumatic valves VU and VD. The illustrative H₂line further includes a further-upstream valve VUU, although this may be omitted.

The illustrative semiconductor wafer processing tool of FIGS. 3 and 4 is a chemical vapor deposition (CVD) tool, in which the process chamber 12 is a CVD chamber 12. The illustrative CVD tool of FIGS. 3 and 4 is configured to deposit titanium nitride (TiN). As seen in FIGS. 3 and 4, the TiN-CVD tool further includes a titanium source in the form of a tetrakis-(dimethylamido)titanium (TDMAT) bubbler cylinder 40 that operates with a helium (He) carrier gas delivered to the TDMAT bubbler 40 by a second helium (He) process gas line denoted as He #2 in FIGS. 3 and 4. The gas source for the He #2 process gas line may be the same He cylinder or the like supplying the He process gas line, or different cylinders may be used. While the illustrative TiN-CVD chamber of FIGS. 3 and 4 uses TDMAT as the titanium source, in other embodiments another titanium-containing metalorganic compound could be used as the titanium precursor in the TiN deposition. Because the TDMAT bubbler cylinder 40 is relatively frequently replaced as the liquid TDMAT is depleted, inlet and outlet manual valves M are provided which can be closed off when replacing the TMAT bubbler cylinder 40. A pneumatic bypass valve V_bypassis provided between the inlet and outlet of the TMAT bubbler cylinder 40 to enable bypassing the bubbler for various maintenance or other operations. In operation to perform the processing on the semiconductor wafer using the semiconductor wafer processing tool (specifically in this case comprising TiN deposition on the semiconductor wafer using the TiN-CVD tool of FIGS. 3 and 4), the mass flow controller MFC of the He #2 carrier gas line along with other operational parameters such as a temperature of the TDMAT bubbler 40 is adjusted to provide a flow of helium with a desired mass flow of the TDMAT reagent. The flows of the various other process gases are also set using the mass flow controllers MFC of the respective process gas lines in accordance with a recipe determined to produce a calibrated deposition rate of TiN.

The TiN-CVD tool of FIGS. 3 and 4 further includes a gas mixing manifold 42 that receives and mixes the process gases supplied by the H₂, N₂, and He process gas lines, and the mixed gas then flows through the final valve VF to the process chamber. The illustrative TiN-CVD tool still further includes a vacuum pump 44 connected via a pump valve V_pumpto a point downstream of the final valve VF and upstream of the CVD chamber 12. A process chamber valve V_chis provided just upstream of the process chamber 12 to enable isolating the process chamber 12 during maintenance or otherwise. FIGS. 3 and 4 are simplified flow diagrams, and the TiN-CVD tool may include other components and/or features not shown, such as an exhaust line exiting the process chamber 12, a load lock for loading a batch or lot of wafers into the process chamber 12, and so forth.

As there are multiple process gas lines in the TiN-CVD tool of FIGS. 3 and 4 (namely four such gas lines: H₂, N₂, He, and H₂#2 carrier gas lines), there will be a corresponding number of instances of the pneumatic control line 20 with electrically actuated valve EV and relay 30 and electrical actuator EA. FIGS. 3 and 4 show only the instance of the pneumatic control line 20 with electrically actuated valve EV and relay 30 and electrical actuator EA operatively connected with the He gas line, but it will be understood that there are additional instances connected to each of the other process gas lines (H₂, N₂, and He #2).

With brief reference to FIG. 5, in some embodiments the pneumatic control lines 20 for multiple process gas lines may be integrated into a single IC controller 32. FIG. 5 illustrates such an arrangement with a clean dry air (CDA) bus line 50 into which CDA is fed via a CDA inlet fitting 52. The CDA bus line 50 connects with the trunks 22 of an illustrative two instances of a pneumatic control line 20, each with its own electrically actuated valve EV and relay 30 (with the electrical actuators EA not shown in FIG. 5). As indicated by the ellipses ( . . . ) of FIG. 5, the illustrative two pneumatic control lines 20 can be extended to additional instances of the pneumatic control line 20 each with its own electrically actuated valve EV and relay 30, e.g. four such instances to handle the four process gas lines of the TiN-CVD chamber of FIGS. 3 and 4. The branches 24 and 26 of the illustrative two (or more) pneumatic control lines 20 include outlet fittings 54 for connecting to the upstream and downstream valves VU and VD, respectively. The IC controller 32 of FIG. 5 further includes an onboard microprocessor 56 that is programmed to control the electrically actuated valves EV and relays 30; alternatively, this processing hardware could be disposed elsewhere, e.g. at a computer operatively connected with the electrically actuated valves EV and relays 30.

Thus, a gas delivery system is disclosed herein for a semiconductor wafer processing tool. The gas delivery system includes a plurality of process gas lines each comprising a mass flow controller MFC and normally closed pneumatic valves including an upstream valve VU that is upstream of the mass flow controller MFC and a downstream valve VD that is downstream of the mass flow controller MFC. A pneumatic valve controller 32 includes a pneumatic pressure inlet 54 and, for each process gas line of the plurality of process gas lines: a pneumatic control line 20 having a trunk 22 receiving pneumatic pressure from the pneumatic pressure inlet 54 and that branches into an upstream branch 24 connected to deliver the pneumatic pressure to the upstream valve VU of the process gas line, and a downstream branch 26 connected to deliver the pneumatic pressure to the downstream valve VD of the process gas line; an electrically actuated valve EV controlling pneumatic pressure through the trunk 22 that has closed and open positions; and an electrically actuated relay 30 controlling pneumatic pressure through the upstream branch 24.

With returning reference to FIG. 3, comparison with FIG. 1 part (D) of the second embodiment demonstrates that the configuration of the valves shown in FIG. 3 is configured to perform the first leak check up to the downstream valves VD of the four process gas lines. This is done by setting the electrically actuated valves EV to be closed, thereby closing the normally closed upstream and downstream valves VU and VD of all four process gas lines. This is explicitly shown only for the He gas line in FIG. 3. To perform the leak check, the valve pump V_pumpis opened for a first time interval (e.g. 1 minute in a nonlimiting illustrative embodiment) in order to draw vacuum in the portion of the semiconductor wafer processing tool including the mixing manifold 42 up to the downstream valves VD (via the open final valve VF) and in the vacuum chamber 12 (via the open chamber valve V_ch). After the first time interval is complete, the drawing of vacuum is stopped by closing off the pump valve V_pump. Thereafter, a delay of a second time interval is taken, e.g. 1 minute in a nonlimiting illustrative embodiment. After the second time interval is finished, the pressure sensor P monitoring pressure in the process chamber 12 is read. If the tool is leak tight up to the downstream valves VD, then the measured pressure should be low. On the other hand, if there is a leak somewhere in the tool up to the downstream valves VD, then such a leak will cause the pressure to rise after the pump valve V_pumpis closed off—hence, a leak can be detected as the measured pressure exceeding a threshold pressure (where the threshold pressure is determined empirically or based on calculated/modeled leak rates to identify a leak of sufficient flow rate to constitute a leak check failure). As previously discussed, the leak check performed with the configuration of FIG. 3 only checks for leaks up to (and including) the downstream valves VD.

With reference to FIG. 4, comparison with FIG. 2 of the second embodiment demonstrates that the configuration of the valves shown in FIG. 4 is configured to perform the second leak check up to the upstream valve VU of the helium (He) gas line. This is done by setting the electrically actuated valve EV of the He gas line to be open and also setting the relay 30 to be open, thereby keeping the upstream valve VU of the He line closed (by action of the open relay 30) while opening the downstream valve VD of the He line. In the example of FIG. 4, the remaining process gas lines (i.e. the H₂, N₂, and He #2 lines) are kept in the same configuration as that used in the first leak check of FIG. 3, namely with the electrically actuated valve EV closed to cause the upstream and downstream valves VU and VD of these other three lines to remain closed. To perform the leak check, the process already described is repeated: the valve pump V_pumpis opened for a first time interval to draw vacuum in the portion of the semiconductor wafer processing tool including the process chamber 12 and the mixing manifold 42 up to the downstream valves VD, and also in the setup of FIG. 4 extending up to the upstream valve VU of the He line, then stopping the drawing of vacuum by closing off the pump valve V_pump, waiting the second time interval, and measuring the pressure using the pressure sensor P. If the tool is leak tight up to the downstream valves VD of the other lines and also up to the upstream valve VU of the He line, then the measured pressure should be low. On the other hand, a leak is detected if the measured pressure exceeds the threshold pressure. If this is the case, then if the tool had previously passed the leak check performed using the configuration of FIG. 3 then it can be inferred that the leak is located between the upstream valve VU of the He line and the downstream valve VD of the He line, or possibly at the upstream valve VU of the He line.

This process described for the He gas line with reference to FIG. 4 can be repeated for each other process gas line, by: (i) closing the electrically actuated valve EV of all lines other than the one being tested up to its upstream valve so as to close the upstream and downstream lines VU and VD of these other gas lines; (ii) opening the electrically actuated valve EV of the gas line being tested while also opening the relay 30 of that gas line so that the upstream valve VU is closed by action of the open relay and the downstream valve VD is open by action of the pneumatic pressure; and (iii) performing the leak check. Advantageously, if the first leak check of FIG. 3 is passed but a pass of the second leak check of FIG. 4 is failed, then it can be inferred that the leak is between the upstream and downstream valves VU and VD (or at the upstream valve VU) of the line currently being tested at the time of the failure.

In a variant approach to performing the second leak check, all gas lines can have their valves configured as shown in FIG. 4 for the He line, i.e. with the electrically actuated valves EV all open to open all downstream valves VD and with all relays 30 open to close all upstream valves VU. In this variant, the second leak check can be performed only once, but if it fails then it is not known which gas line has the leak between its upstream and downstream valves. If a leak is detected, the previously described sequence of checking each line individually can then be performed to isolate which line contains the leak.

In the case of the He #2 carrier gas line, based on the flow diagram of FIGS. 3 and 4 if this line is to be included in the leak checking then inlet and outlet pneumatic valves V_inletand V_outletcan be closed and the bypass valve V_bypassopened, so that the leak check to the He #2 gas line is via the bypass valve V_bypass.

With reference now to FIG. 6, a flow chart of a semiconductor processing method including leak detection as disclosed herein is presented. Normal operation of the tool to perform TiN deposition is described with reference to operations 60, 62, and 64. At an operation 60, the relay 30 (or relays 30 in the case of multiple process gas lines, e.g. FIGS. 3 and 4) is/are closed. At an operation 62 a TiN deposition run is performed to deposit TiN on a wafer or on the wafers of a batch or lot of wafers loaded into the process chamber 12. In this processing, the upstream and downstream valves VU and VD of each process gas line can be controlled together using the corresponding electrically actuated valve EV, since the closed relays 30 ensure the electrically actuated valve EV controls the upstream and downstream valves VU and VD together. After each wafer (or batch or lot of wafers) is processed, the wafer(s) are removed from the process chamber 12, and at a decision operation 64 it is determined whether it is time to perform a leak check. A leak check may be done, by way of nonlimiting illustrative example, after every 16 lots. In other embodiments, the operation 64 can use another criterion to decide if a leak check should be done, such as the absolute amount of time that has elapsed since the last leak check. If it is not time for a leak check as determined at the operation 64, then flow passes back to operation 62 to process the next wafer (or batch or lot of wafers).

On the other hand, if at the decision 64 it is determined that a leak check should be performed, then flow passes to operations 70, 72, 74 which flowchart the first leak check previously described with reference to FIG. 3. At an operation 70 the electrically actuated valves EV are closed for all process gas lines, thereby reverting the normally closed upstream and downstream valves VU and VD to their closed state. As previously noted, for the first leak check the relay(s) 30 can either remain closed (e.g., as shown in FIG. 1 part (D)) or can be opened (as shown in FIG. 3). In an operation 72 the first leak check of FIG. 3 is performed, e.g., by pulling vacuum, closing the pump valve, waiting and checking for a pressure rise due to a leak as previously described. If the measured pressure exceeds the threshold pressure then this is detected at an operation 74. Not only does this tell the operator that a leak is present, but that the leak is in one of the downstream valves VD or further downstream.

On the other hand, if the leak check 72 passes (e.g., the measured pressure does not exceed the threshold pressure), then flow passes to operations 80, 82, 84, 86 which flowchart the second leak check previously described with reference to FIG. 4. The operations 80, 82, 84, 86 correspond to performing the second leak check on one process gas line. In an operation 80, the relay