WO2024076665A1

WO2024076665A1 - Methods for clean rate improvement in multi-rpsc pecvd systems

Info

Publication number: WO2024076665A1
Application number: PCT/US2023/034527
Authority: WO
Inventors: Yan Chi PAN; Jrjyan Jerry Chen; Lynn YANG; Max Chang; Gaku Furuta; Vanness CHEN; Allen K. Lau
Original assignee: Applied Materials, Inc.
Priority date: 2022-10-07
Filing date: 2023-10-05
Publication date: 2024-04-11

Abstract

Embodiments of the present disclosure generally relate to a method of cleaning a chemical vapor deposition chamber. The method includes commencing flow of a cleaning gas to a center remote plasma source (RPS) reactor in a processing chamber. The method includes commencing flow of the cleaning gas to four corner RPS reactors in the processing chamber. The method also includes flowing cleaning gas to the center RPS reactor and the four corner RPS reactors. The method further includes stopping flow of the cleaning gas to the center RPS reactor and stopping flow of the cleaning gas to the four corner RPS reactors.

Description

METHODS FOR CLEAN RATE IMPROVEMENT IN MULTI-RPSC PECVD

SYSTEMS

BACKGROUND

Field

[0001] Embodiments of the present disclosure generally relate to chemical vapor deposition chambers and methods of cleaning the same. More specifically, embodiments described herein relate to a method of chemical vapor deposition, a method of cleaning a chemical vapor deposition chamber by controlling individual remote plasma sources, a non-transitory storage medium with storing instructions to perform operations of chemical vapor deposition, a non-transitory storage medium with storing instructions to perform operations of cleaning a chemical vapor deposition chamber, and a chemical vapor deposition chamber.

Description of the Related Art

[0002] Plasma enhanced chemical vapor deposition (PECVD) is generally employed to deposit thin films on substrates, such as semiconductor substrates, solar panel substrates, organic light emitting diode (OLED) substrates and liquid crystal display (LCD) substrates. These substrates can be fairly large and are substantially rectangular. PECVD is generally accomplished by introducing precursor gases into a vacuum chamber having the substrate disposed on a substrate support. The precursor gases are delivered to the substrate through a gas distribution assembly in the chamber.

[0003] During chemical vapor deposition, deposited material may be formed on components of the chamber, such as the gas distribution assembly and the internal sidewalls of the chamber. This deposited material can flake off during subsequent processing and create contaminating particles that can damage the substrate in the chamber. Thus, periodic chamber cleaning is utilized.

[0004] Current methods of cleaning PECVD chambers are inefficient. This inefficiency can result in increased downtime of the process and waste of cleaning gases. Accordingly, what is needed in the art is improved cleaning apparatus and methods. SUMMARY

[0005] Embodiments of the present disclosure generally relate to chemical vapor deposition chambers and methods of cleaning the same. More specifically, embodiments described herein relate to a method of chemical vapor deposition, a method of cleaning a chemical vapor deposition chamber by controlling individual remote plasma sources, a non-transitory storage medium with storing instructions to perform operations of chemical vapor deposition, a non-transitory storage medium with storing instructions to perform operations of cleaning a chemical vapor deposition chamber, and a chemical vapor deposition chamber.

[0006] In one or more embodiments, a method of cleaning a chemical vapor deposition chamber. The method includes commencing flow of a cleaning gas to a center remote plasma source (RPS) reactor in a processing chamber. The method also includes commencing flow of the cleaning gas to four corner RPS reactors in the processing chamber. The method includes flowing cleaning gas to the center RPS reactor and the four corner RPS reactors. The method further includes stopping flow of the cleaning gas to the center RPS reactor and stopping flow of the cleaning gas to the four corner RPS reactors.

[0007] In one or more embodiments, a non-transitory storage medium with storing instructions that, when executed by a processor, will cause the processor to perform operations of cleaning a chemical vapor deposition chamber. The instructions include commencing flow of a cleaning gas to a center remote plasma source (RPS) reactor in a processing chamber. The instructions include commencing flow of the cleaning gas to four corner RPS reactors in the processing chamber. The instructions also include flowing cleaning gas to the center RPS reactor and the four corner RPS reactors. The instructions further include stopping flow of the cleaning gas to the center RPS reactor and stopping flow of the cleaning gas to the four corner RPS reactors.

[0008] In one or more embodiments, a chemical vapor deposition chamber. The chemical vapor deposition chamber includes a chamber body and a chamber lid and a center remote plasma source (RPS) reactor fluidly coupled to a center of the chamber lid. The chamber also includes four corner RPS reactors, each corner RPS reactor fluidly coupled to a respective corner of the chamber lid. The chamber includes a common valve fluidly connected to the four corner RPS reactors. The chamber further includes a center valve fluidly connected to the center RPS reactor and a cleaning gas supply fluidly connected to the common valve.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of scope, for the disclosure may admit to other equally effective embodiments.

[0010] Figure 1 is a cross-sectional view of a chemical vapor deposition chamber according to one or more embodiments.

[0011] Figures 2A-2B are schematic layouts of the piping for remote plasma source cleaning (RPSC) of a chemical vapor deposition chamber according to one or more embodiments.

[0012] Figure 3A is a schematic block diagram view of a method of cleaning a chemical vapor deposition chamber according to one or more embodiments.

[0013] Figure 3B is a schematic block diagram view of a method of cleaning a chemical vapor deposition chamber according to one or more embodiments.

[0014] Figure 4 is a graph illustrating the effect of cleaning gas flow rate on the cleaning rate of a chemical vapor deposition chamber.

[0015] Figure 5 is a graph illustrating the effect of the length of a first cleaning process on the cleaning rate of a chemical vapor deposition chamber. DETAILED DESCRIPTION

[0016] Embodiments of the present disclosure generally relate to chemical vapor deposition chambers and methods of cleaning the same. More specifically, embodiments described herein relate to a method of chemical vapor deposition, a method of cleaning a chemical vapor deposition chamber by controlling individual remote plasma sources, a non-transitory storage medium with storing instructions to perform operations of chemical vapor deposition, a non-transitory storage medium with storing instructions to perform operations of cleaning a chemical vapor deposition chamber, and a chemical vapor deposition chamber.

[0017] Figure 1 is a schematic cross sectional view of a processing chamber 100, such as a plasma enhanced chemical vapor deposition (PECVD) chamber according to one embodiment. The processing chamber 100 may be used to deposit one or more films may be onto a substrate 140. The processing chamber 100 may be used to process one or more substrates 140, for example, semiconductor substrates, flat panel display substrates, and solar panel substrates, among others.

[0018] The processing chamber 100 generally includes sidewalls 102, a bottom 104 and a showerhead 110 that define a processing volume 106. A substrate support (or susceptor) 130 is disposed in the processing volume 106. The substrate support 130 includes a substrate receiving surface 132 for supporting the substrate 140. The process volume 106 is accessed through an opening 108 formed through the sidewalls 102 such that the substrate 140 may be transferred in and out of the processing chamber 100 when the substrate support 130 is in the lowered position. One or more stems 134 may be coupled to a lift system 136 to raise and lower the substrate support 130. As shown in Figure 1 , the substrate 140 is in a lowered position where the substrate 140 can be transferring into and out of the processing chamber 100. The substrate 140 can be elevated to a processing position, not shown, for processing. The spacing between the top surface of the substrate 140 disposed on the substrate receiving surface 132 and the showerhead 110 may be between about 400 mil and about 1 ,200 mil when the substrate support 130 is raised to the processing position. In one embodiment, the spacing may be between about 400 mil and about 800 mil.

[0019] Lift pins 138 are moveably disposed through the substrate support 130 to space the substrate 140 from the substrate receiving surface 132 to facilitate robotic transfer of the substrate. The substrate support 130 may also include heating and/or cooling elements 139 to maintain the substrate support 130 at a predetermined temperature. The substrate support 130 may also include RF return straps 131 to provide a RF return path at the periphery of the substrate support 130.

[0020] The showerhead 110 may be coupled to a backing plate 112 at a periphery thereof by a suspension 114. The showerhead 110 may also be coupled to the backing plate 112 by one or more coupling supports 160 to help mitigate sag and/or control the straightness/curvature of the showerhead 110.

[0021] A gas source 120 may be fluidly coupled to the backing plate 112 to provide processing gas through a gas outlet 142 in the backing plate 112 and through gas passages 111 in the showerhead 110 to the substrate 140 disposed on the substrate receiving surface 132. A vacuum pump 109 may be coupled to the processing chamber 100 to control the pressure within the process volume 106. An RF power source 122 is coupled to the backing plate 112 and/or to the showerhead 110 to provide RF power to the showerhead 110. The RF power creates an electric field between the showerhead 110 and the substrate support 130 so that a plasma may be generated from the gases between the showerhead 110 and the substrate support 130. Various frequencies may be used, such as a frequency between about 0.3 MHz and about 200 MHz. In one embodiment, the RF power source is provided at a frequency of 13.56 MHz.

[0022] A frame 133 may be placed adjacent to the periphery region of the substrate 140, either in contact with or spaced from the substrate 140. In some embodiments, the frame 133 may be configured to be disposed under the substrate 140. In other embodiments, the frame 133 may be configured to be disposed over the substrate 140. The frame 133 may be a shadow frame, a non-contact frame (e.g., the frame is not in contact with a substrate when positioned on the substrate support 130), a floating frame, a removable frame, a confinement ring, a flow control structure, or other suitable structure positionable adjacent the periphery of the substrate 140.

[0023] During the cleaning process, the frame 133 may rest on the frame support 162. The substrate receiving surface 132 may also be raised to a level that touches the frame 133 without lifting the frame 133 off from the frame support 162 during cleaning.

[0024] The processing chamber 100 includes a plurality of remote plasma sources, such as five (three are shown, 124A-124C). A first remote plasma source 124A, such as an inductively coupled remote plasma source, may also be coupled between the gas source 120 and the backing plate 112 at a central location of the backing plate. A second remote plasma source 124B may be located near one corner of the backing plate. For example, if the backing plate is divided into quadrants in a plan view, the second remote plasma source 124B may be coupled to the backing plate in one quadrant thereof. Similarly, a third remote plasma source 124C may be located in another quadrant, while two other remote plasma sources may each respectively be disposed in remaining quadrants. (Note that the fourth and fifth remote plasma sources are shown in Figures 2A and 2B.) Between processing substrates, a cleaning gas may be provided to the remote plasma sources 124 so that a remote plasma is generated and provided into the processing volume 106 to clean chamber components. The cleaning gas may be further excited while in the processing volume 106 by power applied to the showerhead 110 from the RF power source 122. Suitable cleaning gases include but are not limited to NF₃, F2, and SFe. The cleaning gasses may be utilized separately, or as shown on Page 2 of the appendix, may be combined with inert gases. Inert gasses that may be utilized include, but are not limited to, argon and nitrogen.

[0025] Figure 2A is an embodiment of a remote plasma source cleaning (RPSC) system. The cleaning gas is supplied to a common valve 201. The common valve 201 may be a singular piece of equipment to distribute to the five RPS reactors 240, 250, or the common valve 201 may be a series of valves and piping to distribute the cleaning gas. As shown in Figure 2A, a single pipe may lead to multiple of the corner RPS reactors 240. In another embodiment, the corner RPS reactors 240 may have dedicated cleaning gas supply piping. In one embodiment, the common valve 201 evenly distributes the cleaning gas to the five RPS reactors 240, 250. In one embodiment, the four comers of the processing chamber 100 have corner RPS reactors 240. The center of the processing chamber 100 also has a center RPS reactor 250. In one embodiment, there is no difference between the RPS reactors 240, 250 other than location within the PECVD system. For example, in one embodiment, each of RPS reactors 240, 250 receives an equal flow rate of cleaning gas. Each of RPS reactors 240, 250 may operate for the same of differing amounts of time during a cleaning operation. Each of the RPS reactors 240, 250 may have open valves 210, 220 on the piping leading to the inlets. A closed valve 230 may be located after a split in the piping that leads to the center RPS reactor 250.

[0026] Figure 2B is an embodiment of an RPSC system according to another embodiment. This configuration of the RPSC system includes piping to the center RPS reactor 250 that is not connected to the common valve 201 . The center RPS reactor 250 is connected to a gas supply via valve 220. The center RPS reactor may be connected to the same cleaning gas supply as the common valve 201 or a second cleaning gas supply that is not connected to the common valve 201 .

[0027] The cleaning gas flow to the center RPS reactor is controlled individually relatively to the corner RPS reactors 240, which are each controlled together (separate from the center RPS reactor 250). The cleaning gas supply to the four corner RPS reactors 240 may be supplied via the common valve 201 , and in one example, the common valve 201 may provide equal flow rates to each corner RPS reactor 240. The piping connecting the common valve 201 to the corner RPS reactors 240 may have open valves to allow flow of the cleaning gas to the corner RPS reactors 240. A closed valve 230 may be located on piping from the common valve 201 that leads to a location near the center RPS reactor. The piping after the closed valve 230 may also be fitted with a blind flange to prevent cleaning gas from leaking. [0028] Figure 3A is a schematic block diagram view of a method 300a of cleaning a processing chamber 100 according to one or more embodiments. The method 300a may be utilized with the RPSC system of Figure 2A.

[0029] In operation 310a, the flow of cleaning gas to all five RPS reactors 240, 250 is commenced simultaneously. During operation 320a, cleaning gas is directed towards the five RPS reactors 240, 250. To increase or decrease flow of cleaning gas, flow of cleaning gas is increased or decreased to all five RPS reactors 240, 250. In one or more embodiments, the flow of cleaning gas during operation 320a is constant. In one or more embodiments, the flow of cleaning gas during operation 320a is ramped up, ramped down, or operated in any other non-constant manner. In one or more embodiments, operation 310a is operated by opening valves 210, 220. In one or more embodiments, operation 310a is operated by opening common valve 201 .

[0030] In operation 330a, the flow to all of the RPS reactors 240, 250 is stopped simultaneously. Operation 330a may occur when the RPS reactors 240, 250 are fully clean, when the RPS reactors 240, 250 are determined to be sufficiently clean, after a set period of time, at the request of operations personnel, or any other time. In one or more embodiments, operation 310a is operated by closing valves 210, 220. In one or more embodiments, operation 310a is operated by closing common valve 201 .

[0031] Figure 3B is a schematic block diagram view of a method 300b of cleaning a processing chamber 100 according to one or more embodiments.

[0032] In operation 310b, the flow of cleaning gas to the center RPS reactor 250 is started. In one or more embodiments, operation 310b may be operated by opening valve 220. In operation 312b, the flow of cleaning gas to the corner RPS reactors 240 is started. In one or more embodiments operation 312b may be operated by opening valves 210 or common valve 201. In one or more embodiments, operation 310b and operation 312b commence simultaneously. In one or more embodiments, operation 310b starts before operation 312b. In one or more embodiments, operation 312b starts before operation 310b. [0033] In operation 320b, cleaning gas is flowed to the center RPS reactor 250. In one or more embodiments, the flow of cleaning gas during operation 320b is constant. In one or more embodiments, the flow of cleaning gas during operation 320b is ramped up, ramped down, or operated in any other non-constant manner.

[0034] In operation 322b, cleaning gas is flowed to the corner RPS reactors 240. In one or more embodiments, the flow of cleaning gas during operation 322b is constant. In one or more embodiments, the flow of cleaning gas during operation 322b is ramped up, ramped down, or operated in any other non-constant manner.

[0035] In operation 330b, the flow to the center RPS reactor 250 is stopped. Operation 330b may occur when the center RPS reactor 250 is fully clean, when the center RPS reactor 250 is determined to be sufficiently clean, after a set period of time, at the request of operations personnel, or any other time. For example, operation 330b may be commenced after 0 s to 40 s of operation 320b, for example, after 10 s to 20 s of operation 320b.

[0036] In one or more embodiments, after operation 330b, the flow of cleaning gas towards the corner RPS reactors 240 is maintained, increased, or decreased.

[0037] In one or more embodiments, operation 320b, operation 322b, and operation 330b are run as a two-process cleaning operation. In a first process, operation 320b and 322b are run at a first rate. In the second process, the flow of the cleaning gas to the center RPS reactor 250 is stopped in operation 322b, and the flow of the cleaning gas to the corner RPS reactors 240 is maintained or increased.

[0038] In operation 332b, the flow to the corner RPS reactors 240 is stopped. Operation 330b may occur when the corner RPS reactors 240 are fully clean, when the corner RPS reactors 250 are determined to be sufficiently clean, after a set period of time, at the request of operations personnel, or any other time.

[0039] In one or more embodiments, Operation 330b and operation 332b commence simultaneously. In one or more embodiments, operation 330b starts before operation 332b. In one or more embodiments, operation 332b starts before 330b. In one or more embodiments, operation 310b, operation 320b, and operation 330b are completed prior to commencing operation 312b, operation 322b, and operation 332b. In one or more embodiments, operation 312b, operation 322b, and operation 332b are completed prior to commencing operation 310b, operation 320b, and operation 330b.

[0040] Figure 4 is a schematic graphical view of a graph illustrating the effect of cleaning gas flow rate on the cleaning rate of a chemical vapor deposition chamber. As the cleaning gas flow rate is increased to the corner RPS reactors 240, the cleaning rate (in A/min) holds steady. However, when the cleaning gas flow rate is increased to the center RPS reactor 250, there is an approximately logarithmic increase in the cleaning rate. Similarly, the overall cleaning rate increases with the increase of cleaning gas, but flattens out.

[0041] Figure 5 is a schematic graphical view of a graph illustrating the effect of the length of a first cleaning process on the cleaning rate of a chemical vapor deposition chamber. In one or more embodiments, the first clean process may be operation 320b and operation 322b in Figure 3B, and the second clean process is operation 322b after operation 330b.

[0042] As shown in Figure 5, the cleaning rate of the center RPS reactor 250 increases greatly in the beginning, but levels off. Likewise, the overall cleaning rate of the processing chamber 100 increases greatly in the beginning, but levels off. There is little effect of the time in the first cleaning process on the cleaning rate of the corner RPS reactors 240.

Table 1

[0043] Table 1 details experimental results from a two-process cleaning process as shown in Figure 3B. In Process 1 , 32 slm of NF3 is flowed to the center RPS reactor 250 and 12 slm of NF3 is flowed to the four corner RPS reactors 240, for a total flow rate of 80 slm. In Process 2, 0 slm of NF3 is flowed to the center RPS reactor 250 and 20 slm of NF3 is flowed to the four corner RPS reactors 240, for a total flow rate of 80 slm.

[0044] In tests 1 -7, Process 1 was run for a period of time listed in the second column. In Tests 1 -7, Process 2 was run until the processing chamber was cleaned. Test 8 was utilized as a reference, where Process 1 was run until the processing chamber was clean. In Test 8, Process 2 was not run. The overall cleaning rate of Test 8 was utilized as a baseline to compare Tests 1-7 against. Tests 1 and 2 had lower cleaning ratios than Test 8, so Tests 1 and 2 had negative ratios. Tests 3-7 had higher cleaning ratios than Test 8, so Tests 3-7 had positive ratios.

Table 2

[0045] Table 2 illustrates the difference in cleaning rate between single and two- process cleaning processes.

[0046] In Test A, 16 slm of NF3 is flowed to each of the corner RPS reactors 240 and 16 slm of NF3 is flowed to the center RPS reactor 250, for a total flow rate of 80 slm. In the first example, the cleaning rate is 16,748 A/min. Utilizing Test A as a base cleaning rate, the first example has a normalized cleaning rate of 100%.

[0047] In Test B, 20 slm of NF3 is flowed to each of the corner RPS reactors 240 and 20 slm of NF3 is flowed to the center RPS reactor 250, for a total flow rate of 100 slm. In the second example, the cleaning rate is 18,124 A/min. Utilizing Test A as a base cleaning rate, the Test B has a normalized cleaning rate of 108%.

[0048] In Test C, a two-process cleaning process is utilized. In the first process, 12 slm of NF3 is flowed to each of the corner RPS reactors 240 and 32 slm of NF3 is flowed to the center RPS reactor 250, for a total flow rate of 80 slm. In the second process, 20 slm of NF3 is flowed to each of the corner RPS reactors 240 and 0 slm of NF3 is flowed to the center RPS reactor 250, for a total flow rate of 80 slm. In Test C, the cleaning rate is 18,227 A/min. Utilizing Test A as a base cleaning rate, Test C has a normalized cleaning rate of 109%.

[0049] Benefits of the present disclosure include optimizing the amount of cleaning gas utilized to clean a processing chamber. By utilizing less cleaning gas, this reduces the costs of cleaning gas and the amount of waste gas produced during cleaning operations. The present disclosure may also have the benefit of reducing the time required to clean a processing chamber.

[0050] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

Claims:

1. A method of cleaning a chemical vapor deposition chamber, the method comprising: commencing flow of a cleaning gas to a center remote plasma source (RPS) reactor in a processing chamber; commencing flow of the cleaning gas to four corner RPS reactors in the processing chamber; flowing cleaning gas to the center RPS reactor and the four corner RPS reactors; stopping flow of the cleaning gas to the center RPS reactor; and stopping flow of the cleaning gas to the four corner RPS reactors.

2. The method of claim 1 , wherein the commencing of the flow of the cleaning gas to the RPS reactor and the four corner RPS reactors occurs simultaneously.

3. The method of claim 2, wherein the stopping of the flow of the cleaning gas to the center RPS reactor and the four corner RPS reactors occurs simultaneously.

4. The method of claim 1 , wherein the flow of the cleaning gas to the center RPS reactor is stopped prior to stopping the flow of the cleaning gas to the four corner RPS reactors.

5. The method of claim 4, further comprising increasing a flow rate of the cleaning gas to the four corner RPS reactors after stopping the flow of the cleaning gas to the center RPS reactor.

6. The method of claim 1 , wherein stopping the flow of the cleaning gas to the center RPS reactor occurs after 10 seconds to 30 seconds of flowing cleaning gas to the center RPS reactor.

7. The method of claim 1 , wherein stopping the flow of the cleaning gas to the corner RPS reactors occurs after the chemical vapor deposition chamber is clean.

8. The method of claim 1 , wherein the cleaning gas comprises NF3, F2, or SFe.

9. The method of claim 1 , wherein the cleaning gas comprises an inert gas.

10. A non-transitory storage medium with storing instructions that, when executed by a processor, will cause the processor to perform operations of cleaning a chemical vapor deposition chamber, the instructions comprising: commencing flow of a cleaning gas to a center remote plasma source (RPS) reactor in a processing chamber; commencing flow of the cleaning gas to four corner RPS reactors in the processing chamber; flowing cleaning gas to the center RPS reactor and the four corner RPS reactors; stopping flow of the cleaning gas to the center RPS reactor; and stopping flow of the cleaning gas to the four corner RPS reactors.

11 . The non-transitory storage medium of claim 10, wherein the commencing of the flow of the cleaning gas to the RPS reactor and the four corner RPS reactors is instructed to occur simultaneously.

12. The non-transitory storage medium of claim 11 , wherein the stopping of the flow of the cleaning gas to the center RPS reactor and the four corner RPS reactors is instructed to occur simultaneously.

13. The non-transitory storage medium of claim 10, wherein the flow of the cleaning gas to the center RPS reactor is instructed to stop prior to stopping the flow of the cleaning gas to the four corner RPS reactors.

14. The non-transitory storage medium of claim 13, further comprising instructions to increase a flow rate of the cleaning gas to the four corner RPS reactors after stopping the flow of the cleaning gas to the center RPS reactor.

15. The non-transitory storage medium of claim 10, wherein the instructions for flowing cleaning gas to the center RPS reactor includes a flow rate of cleaning gas to the center RPS reactor between 0 slm and 32 slm.

16. The non-transitory storage medium of claim 10, wherein the instructions for flowing cleaning gas to the corner RPS reactors includes a flow rate of cleaning gas to the corner RPS reactors between 12 slm and 20 slm.

17. A chemical vapor deposition chamber, comprising: a chamber body and a chamber lid; a center remote plasma source (RPS) reactor fluidly coupled to a center of the chamber lid; four corner RPS reactors, each corner RPS reactor fluidly coupled to a respective corner of the chamber lid; a common valve fluidly connected to the four corner RPS reactors; a center valve fluidly connected to the center RPS reactor; and a cleaning gas supply fluidly connected to the common valve.

18. The chemical vapor deposition chamber of claim 17, wherein the center valve is fluidly connected to the cleaning gas supply.

19. The chemical vapor deposition chamber of claim 17, wherein the cleaning gas supply is a first cleaning gas supply and the center valve is fluidly connected to a second cleaning gas supply.

20. The chemical vapor deposition chamber of claim 17, wherein the cleaning gas supply is configured to supply a cleaning gas and an inert gas.