Plasma pre-cleaning system for cluster tools

Abstract

A plasma processing system for cleaning a substrate is provided. A plasma processing system includes a processing chamber including: a chamber body enclosing an interior space; and a substrate support disposed in the internal space. The plasma processing system includes: a vacuum pump; a first exhaust line fluidly coupled between the interior space of the processing chamber and the vacuum pump; and a second exhaust line fluidly coupled between the interior space of the processing chamber and the vacuum pump. The first exhaust line and the second exhaust line are arranged to provide an alternative path for exhaust between the interior space and the vacuum pump, and an inner diameter of the first exhaust line is at least 50% smaller than an inner diameter of the second exhaust line.

Description

Technical Field

[0001] Embodiments of the present disclosure relate generally to the field of semiconductor manufacturing processes, and more particularly to a plasma pre-cleaning system and a cluster tool including the same. Background Art

[0002] Cluster tools are often used to perform processes (e.g., deposition) on substrates (e.g., semiconductor substrates). For some depositions, such as epitaxial deposition, a plasma pre-clean process may be performed on the substrate prior to deposition. The plasma pre-clean process may be performed in one chamber of the cluster tool, while deposition may be performed in another chamber of the cluster tool. Cluster tools including a deposition chamber and a plasma pre-clean chamber are typically configured to operate at a vacuum pressure, such as a pressure of less than 10 Torr.

[0003] Recently, some epitaxial deposition processes have been developed that operate at or near atmospheric pressure, but the plasma pre-cleaning process is still performed at vacuum pressure. Operating different parts of a cluster tool at substantially different pressures (e.g., a pressure of 10 Torr and a pressure of 760 Torr) may lead to problems, such as damage to the substrate, when the substrate is transferred between environments with substantially different pressures.

[0004] Therefore, a method and corresponding device for solving the above problems are needed. Summary of the invention

[0005] In one embodiment, a plasma processing system for cleaning a substrate is provided. The plasma processing system includes a processing chamber, including: a chamber body enclosing an internal space; and a substrate support disposed in the internal space. The plasma processing system includes: a vacuum pump; a first exhaust line fluidly coupled between the internal space of the processing chamber and the vacuum pump; and a second exhaust line fluidly coupled between the internal space of the processing chamber and the vacuum pump, wherein the first exhaust line and the second exhaust line are arranged to provide an alternative path for exhaust between the internal space and the vacuum pump, and the inner diameter of the first exhaust line is at least 50% smaller than the inner diameter of the second exhaust line.

[0006] In another embodiment, a plasma processing system for cleaning a substrate is provided. The plasma processing system includes a processing chamber, including: a chamber body enclosing an interior space; and a substrate support disposed in the interior space. The plasma processing system may further include: a gas source fluidically coupled to the interior space; a first supply line fluidly coupled between the interior space and the gas source; and a second supply line fluidly coupled between the interior space and the gas source, wherein the first supply line and the second supply line are arranged to provide an alternative path between the interior space and the gas source, and the inner diameter of the first supply line is at least 50% smaller than the inner diameter of the second supply line.

[0007] In another embodiment, a cluster tool for processing a semiconductor substrate is provided. The cluster tool includes: a transfer chamber; a deposition chamber coupled to the transfer chamber; and a plasma processing system coupled to the transfer chamber, the plasma processing system including: a processing chamber, including: a chamber body enclosing an interior space; and a substrate support disposed in the interior space; a vacuum pump; a first exhaust line fluidly coupled between the interior space of the processing chamber and the vacuum pump; and a second exhaust line fluidly coupled between the interior space of the processing chamber and the vacuum pump, wherein the first exhaust line and the second exhaust line are arranged to provide an alternative path for exhaust between the interior space and the vacuum pump, and the inner diameter of the first exhaust line is at least 50% smaller than the inner diameter of the second exhaust line. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The embodiments of the present disclosure, briefly summarized above and discussed in more detail below, can be understood by reference to the illustrative embodiments of the present disclosure depicted in the accompanying drawings. It should be noted, however, that the accompanying drawings depict only typical embodiments of this disclosure and are therefore not to be considered as limiting the scope of this disclosure, as the disclosure may admit to other equally effective embodiments.

[0009] Figure 1 is a schematic top view of a cluster tool that may be used to perform the processes described herein, according to one embodiment.

[0010] Figure 2 According to one embodiment, Figure 1 Cross-sectional view of the pre-cleaning system of a cluster tool.

[0011] Figure 3 FIG. 1 is a process flow diagram of a method for performing a pre-cleaning process on a substrate according to one embodiment.

[0012] To facilitate understanding, the same reference numerals are used, where possible, to refer to the same elements common to the drawings. The drawings are not drawn to scale and may be simplified for clarity. It is contemplated that elements and features of one embodiment may be beneficially incorporated into other embodiments without further recitation. DETAILED DESCRIPTION

[0013] Figure 1 1 is a schematic top view of a cluster tool 100 that can be used to perform the processes described herein according to one embodiment. The cluster tool 100 includes a transfer chamber 102, a pair of load lock chambers 106A, 106B, a pre-cleaning system 200 (also referred to as a processing system), and a pair of processing chambers 108, 110. The transfer chamber 102 includes a transfer robot 104 that can transfer substrates 50 to and from various parts of the cluster tool 100.

[0014] As described in more detail below, the pre-clean system 200 includes several features that enable the pre-clean system 200 to perform a vacuum pressure (eg, 3 Torr) plasma pre-clean process on a substrate and then transfer the substrate to the transfer chamber 102 at or near atmospheric pressure.

[0015] A summary of exemplary processes performed on a substrate 50 in a cluster tool is provided herein. The substrate 50 may be received by the cluster tool 100 in one of the load lock chambers 106A, 106B. The substrate 50 may then be transferred by the transfer robot 104 through the transfer chamber 102 and into a chamber of the pre-cleaning system 200 for a pre-cleaning process, such as removing oxides on the substrate 50. The substrate 50 may then be transferred by the robot 104 through the transfer chamber 102 into one of the processing chambers 108, 110 so that a process (e.g., epitaxial deposition) may be performed on the substrate 50. In some embodiments, a second process may be performed on the substrate 50 in another processing chamber 108, 110. After processing in one or both of the processing chambers 108, 110, the substrate 50 may then be transferred by the transfer robot 104 back through the transfer chamber 102 to one of the load lock chambers 106A, 106B for additional processing in other equipment (not shown).

[0016] The pre-cleaning system 200 may include a pre-cleaning chamber 201 ( Figure 2), the pre-cleaning chamber 201 is configured to clean the substrate 50 before a process (e.g., epitaxial deposition) performed on the substrate 50 in one of the processing chambers 108, 110. In some embodiments, a device for providing plasma to the interior space of the pre-cleaning chamber 201 may be included so that a pre-cleaning process can be performed on the substrate 50. Depending on the embodiment, the pre-cleaning system may include one or more of a remote plasma source, a capacitively coupled plasma source, or an inductively coupled plasma source. The pre-cleaning system 200 can be used to perform the cleaning processes described below.

[0017] In one embodiment, the processing chambers 108, 110 may be epitaxial deposition chambers. The processing chambers 108, 110 may be configured to perform epitaxial deposition at atmospheric pressure or near atmospheric pressure (eg, 700-800 Torr).

[0018] Figure 2 2 is a cross-sectional view of a pre-cleaning system 200 according to one embodiment. The pre-cleaning system 200 includes a pre-cleaning chamber 201 (also referred to as a processing chamber). The pre-cleaning chamber 201 includes a chamber body 210. The chamber body 210 includes a bottom 211, a lid assembly 214, and one or more chamber walls 212 connecting the bottom 211 and the lid assembly 214. The chamber body 210 can enclose an interior space 205 of the pre-cleaning chamber 201.

[0019] The pre-cleaning chamber 201 further includes a substrate support assembly 216. The substrate support assembly 216 may include a substrate support 232, an actuator 234, and a shaft 236 connecting the actuator 234 to the substrate support 232. The substrate support 232 may be located in the interior space 205 to support the substrate 50 during processing.

[0020] The chamber body 210 may further include a slit valve 215 to allow the substrate 50 to be inserted into and removed from the interior space 205 of the pre-cleaning chamber 201. The pre-cleaning system 200 and the cluster tool 100 may be configured so that when the slit valve 215 is opened, the pressure in the interior space 205 is maintained lower than the pressure in the transfer chamber 102 to prevent gas and / or particles from flowing from the pre-cleaning chamber 201 to the transfer chamber 102, as described in further detail below.

[0021] The lid assembly 214 is disposed at the upper end of the chamber body 210. The lid assembly 214 may include a remote plasma source 220 for generating plasma from a cleaning gas provided to the remote plasma source 220. The cleaning gas may be provided from a cleaning gas source 227 via a gas inlet 226 of the pre-cleaning chamber 201. The cleaning gas source 227 may include a separate tank for each cleaning gas. In one embodiment, the cleaning gas from the cleaning gas source 227 may include one or more of hydrogen (H2), nitrogen trifluoride (NF3), and ammonia (NH3). The remote plasma source 220 may include a first electrode 221 and a second electrode 222. The first electrode 221 may be spaced apart from the second electrode 222. The remote plasma source 220 may include a plasma generation space 229 located between the first electrode 221 and the second electrode 222.

[0022] The processing system 200 may include a radio frequency (RF) power source 224. The RF power source 224 may be connected to the first electrode 221. The second electrode 222 may be connected to electrical ground to serve as a return path for the RF power when plasma is generated in the space 229. The RF power source 224 may be used to generate plasma of a cleaning gas in the plasma generation space 229 when the cleaning gas is provided to the remote plasma source 220.

[0023] The lid assembly 214 may further include a baffle plate 228 and a showerhead 230 for distributing gas and / or plasma to the interior space 205 of the pre-cleaning chamber 201. The baffle plate 228 may be located between the remote plasma source 220 and the showerhead 230. The baffle plate 228 may receive plasma and / or gas discharged from the remote plasma source 220. In some embodiments, one or more gases may be provided directly to the baffle plate 228 or the showerhead 230, thereby allowing the remote plasma source 220 to be bypassed.

[0024] The processing system 200 may further include an inert gas source 240 connected to the pre-cleaning chamber 201. In one embodiment, the inert gas source 240 includes nitrogen, but in other embodiments, an inert gas (e.g., argon) may also be used. After performing a pre-cleaning process on the substrate 50 and / or before transferring a new substrate 50 into the pre-cleaning chamber 201, the inert gas may be used to pressurize the interior space 205 of the pre-cleaning chamber 201. The processing system 200 may include a pressure sensor 260 configured to measure the pressure of the interior space 205 of the processing chamber 201.

[0025] The inert gas source 240 may be connected to the gas inlet 226 of the processing chamber via a first supply line 245 or a second supply line 246 of the processing system 200. The first supply line 245 and the second supply line 246 may be connected to the gas inlet 226 via a common supply line 247. The first supply line 245 and the second supply line 246 may be arranged to form a parallel (i.e., alternative) path relative to each other, so that a gas may be supplied to the pre-cleaning chamber 201 via one of the supply lines but not via the other supply line.

[0026] The first supply line 245 may include a first supply valve 241 that may be opened to connect the first supply line 245 with the common supply line 247. The second supply line 246 may include a second supply valve 242 that may be opened to connect the second supply line 246 with the common supply line 247.

[0027] The first supply line 245 may have a smaller inner diameter relative to the inner diameter of the second supply line 246. In some embodiments, the inner diameter of the first supply line 245 may be from about 5% to about 90%, such as from about 10% to about 50%, of the inner diameter of the second supply line 246. The smaller diameter of the first supply line 245 may be used to slowly increase the pressure in the inner space 205 from the vacuum pressure used for the pre-cleaning process (e.g., 2 to 20 Torr, such as between about 3 to 5 Torr) after performing a pre-cleaning process on the substrate 50. On the other hand, the second supply line 246 may be used to quickly increase the pressure in the inner space 205 back to atmospheric pressure or a pressure close to atmospheric pressure after the pressure of the gas provided by the smaller first supply line 245 reaches a higher pressure (e.g., 300 Torr). Slowly increasing the pressure after the pre-cleaning process can prevent the possibility of damaging the substrate 50 due to sudden pressure changes, such as mechanical damage caused by swinging or otherwise unintentionally moving the substrate 50.

[0028] Using different supply lines with different inner diameters is one method of varying the rate at which gas is provided to the interior space 205. In other embodiments, for example, a slower pressure change can be achieved by an analog control valve on a single supply line. In some of these other embodiments, a sensor (e.g., a flow meter or a pressure sensor) can be used to control an analog control valve or other actuator (e.g., a variable speed pump) to control the rate at which the pressure in the interior space 205 increases when an inert gas is supplied to the interior space 205, so that a slower pressure change in the interior space 205 can be achieved.

[0029] The processing system 200 may further include a vacuum pump 218 configured to exhaust gas from the pre-cleaning chamber 201 through an exhaust port 223 of the pre-cleaning chamber 201. The vacuum pump 218 may be connected to the exhaust port 223 through a first exhaust line 261 or a second exhaust line 262 of the processing system 200. The first exhaust line 261 and the second exhaust line 262 may be arranged to form a parallel (i.e., alternative) path relative to each other, so that gas may be exhausted from the pre-cleaning chamber 201 through one of the exhaust lines but not through the other exhaust line. The first exhaust line 261 and the second exhaust line 262 may be connected to the exhaust port 223 through a common exhaust line 263. The first exhaust line 261 may include a first exhaust valve 219, which may be opened to fluidly couple the first exhaust line 261 and the common exhaust line 263. The second exhaust line 262 may include a second exhaust valve 239 that may be opened to fluidly couple the second exhaust line 262 with the common exhaust line 263 .

[0030] The first exhaust line 261 may have a smaller inner diameter relative to the inner diameter of the second exhaust line 262. All references to inner diameter provided in this disclosure also apply to the inner cross-sectional area, for example, if a component (e.g., a fluid conduit) has a non-circular cross-section. In some embodiments, the inner diameter of the first exhaust line 261 may be from about 5% to about 75%, such as from about 10% to about 50%, of the inner diameter of the second exhaust line 262. The smaller diameter of the first exhaust line 261 can be used to smoothly and slowly reduce the pressure in the interior space 205 from atmospheric pressure or a pressure close to atmospheric pressure (e.g., 700-800 Torr) to a lower pressure, such as from about 400-650 Torr, such as about 600 Torr. For example, the decompression can be performed after the substrate 50 is transferred from the transfer chamber 102 maintained at atmospheric pressure or a pressure close to atmospheric pressure to the pre-cleaning chamber 201. On the other hand, the second exhaust line 262 can be used to quickly reduce the pressure in the interior space 205 to a pressure close to the pressure used for the pre-cleaning plasma process, such as a pressure less than 50 Torr, such as about 100 mTorr to about 20 Torr, such as a pressure between about 300 mTorr and about 5 Torr. Slowly reducing the pressure after the substrate 50 is transferred into the pre-cleaning chamber 201 can prevent the possibility of damaging the substrate 50 due to sudden pressure changes, such as mechanical damage caused by swinging or otherwise unintentionally moving the substrate 50.

[0031] Using different exhaust lines with different inner diameters is one method of varying the rate at which gas and / or plasma is exhausted from the interior space 205, so that slower pressure changes in the interior space 205 can be achieved. In other embodiments, for example, slower pressure changes can be achieved by an analog control valve on a single exhaust line. In some of these other embodiments, a sensor (e.g., a flow meter or a pressure sensor) can be used to control an analog control valve or other actuator (e.g., a variable speed vacuum pump) to control the rate at which the pressure in the interior space 205 is reduced when the interior space 205 is reduced to the vacuum pressure for performing the plasma pre-cleaning process.

[0032] As described above, the substrate support assembly 216 includes a substrate support 232, an actuator 234, and a shaft 236 connecting the actuator 234 to the substrate support 232. The shaft 236 may extend through a centrally located opening formed in the bottom 211 of the chamber body 210. The actuator 234 may be resiliently sealed to the bottom 211 of the chamber body 210 by a bellows (not shown), which prevents vacuum leakage from around the shaft 236. The actuator 234 allows the substrate support 232 to move vertically within the chamber body 210 between a process position and a lower transfer position. The transfer position may be slightly below an opening of a slit valve 215 formed through one of the one or more walls 212 of the chamber body 210.

[0033] Although not shown, in some embodiments, an RF and / or DC bias may be coupled to the substrate support 232 to assist in directing the cleaning plasma toward the substrate 50 .

[0034] The processing system 200 may further include an auxiliary exhaust assembly 270. The auxiliary exhaust assembly 270 may include a first auxiliary exhaust line 275, a second auxiliary exhaust line 276, and a common auxiliary exhaust line 278. The auxiliary exhaust assembly 270 may further include a vacuum pump or other device for generating a negative pressure in the auxiliary exhaust assembly 270 line relative to the internal space 205 of the pre-cleaning chamber 201, so that when the valve of the auxiliary exhaust assembly 270 is opened, the gas is exhausted from the internal space 205 through the auxiliary exhaust assembly 270.

[0035] The common auxiliary exhaust line 278 may be connected to the inner space 205 of the pre-cleaning chamber 201. The first auxiliary exhaust line 275 and the second auxiliary exhaust line 276 may be connected to the inner space 205 of the pre-cleaning chamber 201 via the common auxiliary exhaust line 278. The first auxiliary exhaust line 275 may include a first auxiliary exhaust valve 272, which may be opened to connect the first auxiliary exhaust line 275 with the common auxiliary exhaust line 278. The second auxiliary exhaust line 276 may include a second auxiliary exhaust valve 274, which may be opened to connect the second auxiliary exhaust line 276 with the common auxiliary exhaust line 278.

[0036] The first auxiliary exhaust valve 272 may be opened when a high pressure condition occurs. The first auxiliary exhaust line 275 may include a pressure sensor 271 to measure the pressure within the first auxiliary exhaust line 275. When a pressure above a given threshold (e.g., 800 Torr) is measured, the first auxiliary exhaust valve 272 may be opened to release the pressure within the interior space 205. Because the pre-cleaning chamber 201 operates at a higher pressure than other pre-cleaning chambers that typically operate at a vacuum pressure (e.g., less than 100 Torr) for pre-cleaning processes and substrate transfer, more components of the pre-cleaning chamber are fastened or otherwise secured to each other. For example, components of the lid assembly 214 may be secured to other components in the lid assembly 214 and / or to the chamber wall 212. For pre-cleaning chambers that operate at a vacuum pressure for pre-cleaning processes and substrate transfer in and out of the pre-cleaning chamber, some of these components in the lid assembly are typically not fastened. Additional securing of components in the pre-cleaning chamber 201 can help prevent any components from moving during the pressure changes that occur for each substrate pre-cleaning and transfer, as described in further detail below. However, securing these components may create safety issues because previously unsecured components may move to relieve high pressure conditions. In the pre-cleaning chamber 201, the first auxiliary exhaust valve 272 can be opened to relieve the high pressure condition when measured by the pressure sensor 271, preventing an unsafe high pressure condition from occurring.

[0037] When the slit valve 215 is opened, the second auxiliary exhaust valve 274 may be opened, which allows gas to flow from the interior space 205 out of the auxiliary exhaust assembly 270. The interior space 205 of the pre-cleaning chamber 201 is generally considered to be less clean than the interior space of the transfer chamber 102. Therefore, gas should not flow from the interior space 205 of the pre-cleaning chamber 201 to the interior space of the transfer chamber 102. When the second auxiliary exhaust valve 274 is opened while the slit valve 215 is open, the pressure in the interior space 205 is reduced relative to the pressure in the interior space of the transfer chamber 102, and gas flows from the interior space of the transfer chamber 102 through the interior space 205 of the pre-cleaning chamber 201 and out of the auxiliary exhaust assembly 270.

[0038] The processing system 200 may further include a controller 290 for controlling the processing system 200 ( Figure 2 ) and cluster tool 100( Figure 1 ) within other parts of the process. Controller 290 can be any type of controller used in an industrial setting, such as a programmable logic controller (PLC). Controller 290 includes a processor 292, a memory 294, and input / output (I / O) circuits 296. Controller 290 may further include one or more of the following components (not shown), such as one or more power supplies, clocks, communication components (e.g., a network interface card), and user interfaces that are commonly found in controllers for semiconductor equipment.

[0039] The memory 294 may include non-transitory memory. The non-transitory memory may be used to store programs and settings described below. The memory 294 may include one or more readily available types of memory, such as read-only memory (ROM) (e.g., electronically erasable programmable read-only memory (EEPROM)), flash memory, floppy disk, hard disk, or random access memory (RAM) (e.g., non-volatile random access memory (NVRAM)).

[0040] The processor 292 is configured to execute various programs stored in the memory 294, for example, it is configured to execute the following reference Figure 3 The procedures of the method 1000 are described. During the execution of these procedures, the controller 290 can communicate with I / O devices (e.g., sensors and actuators) via the I / O circuits 296. For example, during the execution of these procedures and the communication via the I / O circuits, the controller 290 can control outputs (e.g., opening and closing valves) and receive information from feedback devices (e.g., feedback on the open / closed state of valves), sensors, and other instruments in the processing system 200 and other parts of the cluster tool 100.

[0041] The memory 294 may further include various operating settings for controlling the processing system 200 and other portions of the cluster tool 100. For example, the settings may include settings for the following references: Figure 3 The method 1000 is described with respect to pressure settings when transitioning between slowly changing and more rapidly changing the pressure in the interior space 205, as well as various other settings.

[0042] Figure 3 FIG. 1 is a process flow diagram of a method 1000 for performing a pre-cleaning process on a substrate 50 according to one embodiment. Figure 1 to Figure 3 The method 1000 is described. The controller 290 may execute a program stored in a memory to perform the method 1000. The method begins at block 1002.

[0043] At block 1002, a new substrate 50 is transferred from the transfer chamber 102 of the cluster tool 100 into the pre-cleaning chamber 201. At block 1002, the interior space of the transfer chamber 102 and the interior space 205 of the pre-cleaning chamber 201 are both at or near atmospheric pressure. The slit valve 215 of the pre-cleaning chamber 201 may be opened, and the transfer robot 104 may position the substrate 50 on the substrate support 232 in the interior space 205 of the pre-cleaning chamber 201. The second auxiliary exhaust valve 274 may be opened at the following time: when the slit valve 215 is opened or slightly before the slit valve 215 is opened, which allows gas to flow from the interior of the transfer chamber 102 to the interior space 205 of the pre-cleaning chamber 201 and out through the auxiliary exhaust assembly 270, which is connected to a low pressure outlet (not shown). Flowing gas from the transfer chamber 102 to the pre-clean chamber 201 helps maintain a clean environment in the transfer chamber 102 and the rest of the cluster tool outside of the pre-clean chamber 201 .

[0044] At block 1004, the slit valve 215 is closed and a slow evacuation of the pre-cleaning chamber 201 is performed. When the slow evacuation begins, the interior space 205 of the pre-cleaning chamber 201 is at atmospheric pressure or a pressure close to atmospheric pressure. The slow evacuation of the interior space 205 is performed by energizing the vacuum pump 218 and opening the first exhaust valve 219. The slow evacuation continues until a first target exhaust pressure in the interior space 205 as measured by the pressure sensor 260 is reached. In some embodiments, the first target exhaust pressure may be from about 400 torr to about 700 torr, for example, about 600 torr. The first exhaust valve 219 is located on the first exhaust line 261, which has a smaller inner diameter than the second exhaust line 262. The smaller diameter of the first exhaust line 261 can be used to smoothly and slowly reduce the pressure in the interior space 205 until the first target exhaust pressure is reached. In some embodiments, the slow evacuation may take from about 5 seconds to about 100 seconds, for example, about 20 seconds. Slow pumpdown helps prevent damage to the substrate 50 that could result from movement (e.g., wobbling or other unintentional movement) of the substrate 50 when the substrate 50 is exposed to sudden pressure changes, for example, if a faster pumpdown of the interior space 205 is performed without first performing the slow pumpdown at block 1004.

[0045] At block 1006, a rapid evacuation of the interior space 205 of the pre-clean chamber 201 is performed from the first target exhaust pressure (e.g., 600 Torr) achieved at block 1004 to a lower target exhaust pressure measured by the pressure sensor 260 for the pre-clean plasma process. The lower target exhaust pressure may be from about 100 mTorr to about 20 Torr, such as between about 300 mTorr to about 5 Torr. The rapid evacuation of the interior space 205 is performed by opening the second exhaust valve 239 to connect the interior space 205 to the vacuum pump 218 via the second exhaust line 262. The first exhaust valve 219 may be closed at block 1006. The second exhaust line 262 has a larger inner diameter (e.g., 100% larger) relative to the first exhaust line 261, so that the pressure of the interior space 205 can be reduced more quickly relative to the pressure change during the slow evacuation of block 1004. In some embodiments, the rapid evacuation may take from about 3 seconds to about 50 seconds, such as about 10 seconds.

[0046] At block 1008, a plasma pre-cleaning process is performed on the substrate 50 in the interior volume 205 of the pre-cleaning chamber 201. The pre-cleaning process may include providing one or more cleaning gases (e.g., NF3, NH, and H2) to the remote plasma source 220, generating a plasma of the one or more cleaning gases in the remote plasma source 220, and providing the plasma of the one or more cleaning gases into the interior volume 205 of the pre-cleaning chamber 201 through the showerhead 230 until the cleaning process at block 1008 is completed (e.g., after a specified period of time). In one embodiment, the plasma of the one or more cleaning gases may be used to remove oxides from the substrate 50.

[0047] At block 1010, after the cleaning process of block 1008 is completed, a slow filling of the interior space 205 of the pre-cleaning chamber 201 with an inert gas (e.g., N2) is performed. The plasma pre-cleaning process performed at block 1008 is performed under a vacuum pressure (e.g., 3 Torr). Therefore, the slow filling process at block 1010 starts at the vacuum pressure at the end of block 1008. The slow filling of the interior space 205 of the pre-cleaning chamber 201 is performed by opening the first supply valve 241 on the first supply line 245, which connects the inert gas source 240 to the gas inlet 226 of the pre-cleaning chamber 201 via the first supply line 245.

[0048] The slow filling at block 1010 continues until a first target supply pressure in the interior space 205 as measured by the pressure sensor 260 is reached. In some embodiments, the first target supply pressure may be from about 100 Torr to about 500 Torr, such as about 300 Torr. The first supply valve 241 is located on a first supply line 245, which has a smaller inner diameter than the second supply line 246. The smaller diameter of the first supply line 245 can be used to smoothly and slowly increase the pressure in the interior space 205 until the first target supply pressure is reached. In some embodiments, the slow filling may take from about 5 seconds to about 100 seconds, such as about 20 seconds. The slow filling helps prevent damage to the substrate 50 that may be caused by movement (e.g., wiggling or other unintentional movement) of the substrate 50 when the substrate 50 is exposed to sudden pressure changes, for example, if a faster filling of the interior space 205 is performed without first performing the slow filling at block 1010.

[0049] At block 1012, a rapid fill of the interior space 205 of the pre-cleaning chamber 201 is performed from the first target supply pressure (e.g., 200 Torr) achieved at block 1010 to a higher second target supply pressure measured by the pressure sensor 260. The higher second target supply pressure can be atmospheric pressure or a pressure close to atmospheric pressure. The rapid fill of the interior space 205 is performed by opening the second supply valve 242, which connects the inert gas source 240 to the gas inlet 226 of the pre-cleaning chamber 201 via the second supply line 246.

[0050] The first supply valve 241 may be closed at block 1012. The second supply line 246 has a larger inner diameter (e.g., 100% larger) relative to the first supply line 245 so that the pressure of the interior space 205 can be increased more quickly relative to the pressure change during the slow fill of block 1010. In some embodiments, the fast fill may take from about 3 seconds to about 50 seconds, such as about 10 seconds.

[0051] At block 1014, the substrate 50 may be removed from the pre-cleaning chamber 201 while the interior space 205 is at or near atmospheric pressure. The slit valve 215 of the pre-cleaning chamber 201 may be opened, and the transfer robot 104 may remove the substrate 50 from the substrate support 232. The second auxiliary exhaust valve 274 may be opened at the same time as or slightly before the slit valve 215 is opened, which allows gas to flow from the interior of the transfer chamber 102 to the interior space 205 of the pre-cleaning chamber 201 and out through the auxiliary exhaust assembly 270, which is connected to a low pressure outlet (not shown). Allowing gas to flow from the transfer chamber 102 to the pre-cleaning chamber 201 helps maintain a clean environment in the transfer chamber 102 and the rest of the cluster tool 100 outside the pre-cleaning chamber 201.

[0052] After removal from the pre-clean chamber 201 , the pre-cleaned substrate 50 may be transferred to one of the processing chambers 108 , 110 so that additional processes may be performed on the substrate 50 , such as epitaxial deposition performed at atmospheric or near atmospheric pressure.

[0053] At block 1016, a determination is made as to whether a pre-cleaning process should be performed on another substrate 50. If another substrate 50 is to be pre-cleaned, blocks 1002 to 1014 may be repeated for the next substrate 50. This repetition may continue until a target number of substrates 50 have been pre-cleaned using method 1000.

[0054] The apparatus and process described in this disclosure enable a vacuum pressure (e.g., 3 Torr), plasma pre-clean process to be performed on a substrate in a pre-clean chamber when the pre-clean chamber is connected to an apparatus that operates at a substantially higher pressure (e.g., atmospheric pressure). For example, other portions of the cluster tool 100, such as the transfer chamber 102, the processing chambers 108, 110, and the load lock chambers 106A, 106B, may all operate at substantially higher pressures (e.g., atmospheric pressure). By starting the pressure change of the interior space 205 of the pre-clean chamber 201 in a slow manner by slow evacuation at block 1004 and slow filling at block 1010, and then increasing the rate of pressure change of the interior space 205 by fast evacuation at block 1006 and fast filling at block 1012, a large number of substrates 50 may be pre-cleaned in a rapid and efficient manner while the risk of damaging the substrates 50 due to sudden pressure changes (e.g., mechanical damage caused by wobbling or otherwise unintentionally moving the substrates) is maintained low.

[0055] 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.

Claims

1. A plasma processing system for cleaning a substrate, comprising: A processing chamber comprising: a chamber body enclosing the interior space; and a substrate support member disposed in the internal space; Vacuum pump; a first exhaust line fluidly coupled between the interior space of the processing chamber and the vacuum pump; and A second exhaust line is fluidly coupled between the interior space of the processing chamber and the vacuum pump, wherein The first exhaust line and the second exhaust line are arranged to provide alternative paths for exhaust between the interior space and the vacuum pump, and The inner diameter of the first exhaust line is at least 50% smaller than the inner diameter of the second exhaust line.

2. The plasma processing system of claim 1 , further comprising a controller configured to: opening a first exhaust valve on the first exhaust line to exhaust the interior space of the processing chamber through the first exhaust line until a first exhaust pressure in the interior space is reached; and The second exhaust valve on the second exhaust line is opened to exhaust the interior space of the processing chamber through the second exhaust line until a second exhaust pressure in the interior space is reached.

3. The plasma processing system of claim 2, wherein the first exhaust pressure is greater than 400 Torr.

4. The plasma processing system of claim 3, wherein the second exhaust pressure is less than 50 Torr.

5. The plasma processing system of claim 1 , further comprising: a gas source fluidly coupled to the interior space; a first supply line fluidly coupled between the interior space and the gas source; and a second supply line fluidly coupled between the interior space and the gas source, wherein The first supply line and the second supply line are arranged to provide an alternative path between the interior space and the gas source, and The inner diameter of the first supply line is at least 50% smaller than the inner diameter of the second supply line.

6. The plasma processing system of claim 5, further comprising a remote plasma source fluidly coupled between the first supply line and the interior space.

7. The plasma processing system of claim 5, further comprising a controller configured to: opening a first supply valve on the first supply line to supply gas from the gas source to the interior space of the processing chamber via the first supply line until a first supply pressure in the interior space is reached; and A second supply valve on the second supply line is opened to supply the gas from the gas source to the interior space of the processing chamber via the second supply line until a second supply pressure in the interior space is reached.

8. The plasma processing system of claim 7, wherein the first supply pressure is less than 300 Torr.

9. The plasma processing system of claim 8, wherein the second supply pressure is greater than 600 Torr.

10. A plasma processing system for cleaning a substrate, comprising: A processing chamber comprising: a chamber body enclosing the interior space; and a substrate support member disposed in the internal space; a gas source fluidly coupled to the interior space; a first supply line fluidly coupled between the interior space and the gas source; and a second supply line fluidly coupled between the interior space and the gas source, wherein The first supply line and the second supply line are arranged to provide an alternative path between the interior space and the gas source, and The inner diameter of the first supply line is at least 50% smaller than the inner diameter of the second supply line.

11. The plasma processing system of claim 10, further comprising a controller configured to: opening a first supply valve on the first supply line to supply gas from the gas source to the interior space of the processing chamber via the first supply line until a first supply pressure in the interior space is reached; and A second supply valve on the second supply line is opened to supply the gas from the gas source to the interior space of the processing chamber via the second supply line until a second supply pressure in the interior space is reached.

12. The plasma processing system of claim 11 wherein said first supply pressure is less than 300 Torr.

13. The plasma processing system of claim 12, wherein the second supply pressure is greater than 600 Torr.

14. The plasma processing system of claim 10, further comprising a remote plasma source fluidly coupled between the first supply line and the interior space.

15. A cluster tool for processing a semiconductor substrate, comprising: transfer chamber; a deposition chamber coupled to the transfer chamber; and A plasma processing system coupled to the transfer chamber, the plasma processing system comprising: A processing chamber comprising: a chamber body enclosing the interior space; and a substrate support member disposed in the internal space; Vacuum pump; a first exhaust line fluidly coupled between the interior space of the processing chamber and the vacuum pump; and A second exhaust line is fluidly coupled between the interior space of the processing chamber and the vacuum pump, wherein The first exhaust line and the second exhaust line are arranged to provide alternative paths for exhaust between the interior space and the vacuum pump.

16. The cluster tool of claim 15, further comprising a controller configured to: opening a first exhaust valve on the first exhaust line to exhaust the interior space of the processing chamber through the first exhaust line until a first exhaust pressure in the interior space is reached; and The second exhaust valve on the second exhaust line is opened to exhaust the interior space of the processing chamber through the second exhaust line until a second exhaust pressure in the interior space is reached.

17. The cluster tool of claim 16, wherein the first exhaust pressure is greater than 400 Torr.

18. The cluster tool of claim 17, wherein the second exhaust pressure is less than 50 Torr.

19. The cluster tool of claim 16, wherein the controller is configured to operate the transfer chamber at atmospheric pressure.

20. The cluster tool of claim 16, wherein the controller is configured to perform a cleaning process on a substrate in the processing chamber at a pressure from about 300 mTorr to about 20 Torr.

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