Plasma pre - cleaning system for cluster tools

Abstract

A plasma processing system for cleaning a substrate is provided. The plasma processing system includes a process chamber including a chamber body surrounding an internal space and a substrate support disposed within the internal space. The plasma processing system includes a vacuum pump, a first exhaust line fluidly coupled between the internal space of the process chamber and the vacuum pump, and a second exhaust line fluidly coupled between the internal space of the process chamber and the vacuum pump. The first exhaust line and the second exhaust line are arranged to provide alternative paths for exhausting between the internal space and the vacuum pump, and the first exhaust line has an inner diameter that is at least 50% smaller than the inner diameter of the second exhaust line.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to the field of semiconductor manufacturing processes, and more particularly, to a plasma preclean system and a cluster tool including the plasma preclean system.

Background Art

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

[0003] In recent years, several epitaxial deposition processes operating at or near atmospheric pressure have been developed, but the plasma preclean process is still performed at a vacuum pressure. Operating different parts of a cluster tool at substantially different pressures, such as a pressure of 10 Torr and a pressure of 760 Torr, can cause problems, such as damage to the substrate when the substrate is transferred between environments having substantially different pressures.

[0004] Therefore, there is a need for methods and corresponding devices to address the problems described above.

Summary of the Invention

[0005] In one embodiment, a plasma processing system for cleaning a substrate is provided. The plasma processing system includes a process chamber having a chamber body surrounding an interior volume and a substrate support disposed within the interior volume. The plasma processing system includes a vacuum pump, a first exhaust line fluidly coupled between the interior volume of the process chamber and the vacuum pump, and a second exhaust line fluidly coupled between the interior volume of the process chamber and the vacuum pump. The first exhaust line and the second exhaust line are arranged to provide alternative paths for exhausting between the interior volume and the vacuum pump, and the first exhaust line has an inner diameter that 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 process chamber having a chamber body surrounding an interior volume and a substrate support disposed within the interior volume. The plasma processing system can further include a gas source fluidly coupled to the interior volume, a first supply line fluidly coupled between the interior volume and the gas source, and a second supply line fluidly coupled between the interior volume and the gas source. The first supply line and the second supply line are arranged to provide alternative paths for supplying between the interior volume and the gas source, and the first supply line has an inner diameter that 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 includes a process chamber surrounding an internal space and having a substrate support disposed therein, a vacuum pump, a first exhaust line fluidly coupled between the internal space of the process chamber and the vacuum pump, and a second exhaust line fluidly coupled between the internal space of the process chamber and the vacuum pump. The first exhaust line and the second exhaust line are arranged to provide alternative paths for exhausting between the internal space and the vacuum pump, and the first exhaust line has an inner diameter that is at least 50% smaller than the inner diameter of the second exhaust line.

[0008] Implementations of the present disclosure, briefly summarized above and described in more detail below, can be understood by reference to the exemplary implementations of the present disclosure shown in the accompanying drawings. However, it should be noted that since the present disclosure may admit other equally effective implementations, the accompanying drawings show only the general implementations of the present disclosure and should not be considered as limiting its scope.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0010] To facilitate understanding, wherever possible, like reference numerals are used to designate like elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. It is contemplated that elements and features of one implementation may be advantageously incorporated into other implementations without further recitation.

[0011] FIG. 1 is a schematic top view of a cluster tool 100 that can be used to execute 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 process chambers 108, 110. The transfer chamber 102 includes a transfer robot 104 that can transfer a substrate 50 between the various components of the cluster tool 100.

[0012] As will be described in more detail below, the pre-cleaning system 200 includes several features that enable the pre-cleaning system 200 to perform a plasma pre-cleaning process at a vacuum pressure (e.g., 3 torr) on a substrate and then transfer the substrate to the transfer chamber 102 at atmospheric pressure or a pressure close to atmospheric pressure.

[0013] Here, an overview of an exemplary process executed on the substrate 50 in the cluster tool is provided. The substrate 50 can be received by the cluster tool 100 in one of the load lock chambers 106A, 106B. Then, the substrate 50 can be transferred by the transfer robot 104 through the transfer chamber 102 into a chamber of the pre-cleaning system 200 for a pre-cleaning process, such as the removal of oxides on the substrate 50. Next, the substrate 50 can be transferred by the robot 104 through the transfer chamber 102 into one of the process chambers 108, 110 so that a process (e.g., epitaxial deposition) can be executed on the substrate 50. In some embodiments, a second process can be executed on the substrate 50 in the other process chambers 108, 110. After processing in one or both of the process chambers 108, 110, the substrate 50 can be transferred back by the transfer robot 104 through the transfer chamber 102 into one of the load lock chambers 106A, 106B for additional processing in other equipment (not shown).

[0014] The pre-cleaning system 200 can include a pre-cleaning chamber 201 (FIG. 2) configured to clean the substrate 50 before a process (e.g., epitaxial deposition) to be executed on the substrate 50 in one of the process chambers 108, 110. In some embodiments, the pre-cleaning system 200 can include equipment for providing plasma to the internal space of the pre-cleaning chamber 201 so that a pre-cleaning process can be executed on the substrate 50. Depending on the embodiment, the pre-cleaning system can 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 execute the cleaning process described below.

[0015] In one embodiment, the process chambers 108, 110 can be epitaxial deposition chambers. The process chambers 108, 110 can be configured to perform epitaxial deposition at atmospheric pressure or a pressure close to atmospheric pressure (e.g., 700 - 800 Torr).

[0016] Figure 2 is a cross-sectional view of a pre-cleaning system 200 according to an embodiment. The pre-cleaning system 200 includes a pre-cleaning chamber 201 (also referred to as a process 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 to the lid assembly 214. The chamber body 210 can surround the internal space 205 of the pre-cleaning chamber 201.

[0017] The pre-cleaning chamber 201 further includes a substrate support assembly 216. The substrate support assembly 216 can 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 can be positioned in the internal space 205 to support the substrate 50 during processing.

[0018] The chamber body 210 can further include a slit valve 215 to enable insertion of the substrate 50 into the internal space 205 of the pre-cleaning chamber 201 and removal of the substrate 50 from the internal space 205 of the pre-cleaning chamber 201. The pre-cleaning system 200 and the cluster tool 100 can be configured to keep the pressure in the internal space 205 lower than the pressure in the transfer chamber 102 to prevent the flow of gas and / or particles from the pre-cleaning chamber 201 to the transfer chamber 102 when the slit valve 215 is open, as will be described in more detail below.

[0019] The lid assembly 214 is disposed at the upper end of the chamber body 210. The lid assembly 214 can include a remote plasma source 220 for generating plasma from a cleaning gas supplied to the remote plasma source 220. The cleaning gas can be supplied from a cleaning gas source 227 through a gas inlet 226 of the pre-cleaning chamber 201. The cleaning gas source 227 can include separate tanks for each cleaning gas. In one embodiment, the cleaning gas from the cleaning gas source 227 can include one or more of hydrogen (H2), nitrogen trifluoride (NF3), and ammonia (NH3). The remote plasma source 220 can include a first electrode 221 and a second electrode 222. The first electrode 221 can be spaced apart from the second electrode 222. The remote plasma source 220 can include a plasma generation volume 229 disposed between the first electrode 221 and the second electrode 222.

[0020] The processing system 200 can include a radio frequency (RF) power source 224. The RF power source 224 can be connected to the first electrode 221. The second electrode 222 can be connected to electrical ground so as to serve as a return path for RF power when plasma is generated in the volume 229. The RF power source 224 can be used to generate plasma of the cleaning gas within the plasma generation volume 229 when the cleaning gas is supplied to the remote plasma source 220.

[0021] The lid assembly 214 can further include a blocker plate 228 and a shower head 230 for distributing gas and / or plasma into the internal space 205 of the pre-cleaning chamber 201. The blocker plate 228 can be disposed between the remote plasma source 220 and the shower head 230. The blocker plate 228 can receive plasma and / or gas emitted from the remote plasma source 220. In some embodiments, one or more gases can be supplied directly to the blocker plate 228 or the shower head 230, making it possible to bypass the remote plasma source 220.

[0022] The processing system 200 can further include an inert gas source 240 connected to the pre - cleaning chamber 201. In certain embodiments, the inert gas source 240 includes nitrogen, although an inert gas (e.g., argon) can also be used. The inert gas can be used to pressurize the internal space 205 of the pre - cleaning chamber 201 after a pre - cleaning process is performed on the substrate 50 and / or before a new substrate 50 is transferred into the pre - cleaning chamber 201. The processing system 200 can include a pressure sensor 260 configured to measure the pressure of the internal space 205 of the process chamber 201.

[0023] The inert gas source 240 can be connected to the gas inlet 226 of the process chamber through the first supply line 245 or the second supply line 246 of the processing system 200. The first supply line 245 and the second supply line 246 can be connected to the gas inlet 226 through a common supply line 247. The first supply line 245 and the second supply line 246 can be arranged to form parallel (i.e., alternative) paths with respect to each other so that gas can be supplied to the pre - cleaning chamber 201 through one of the supply lines without passing through other supply lines.

[0024] The first supply line 245 can include a first supply valve 241 that can be opened to connect the first supply line 245 to the common supply line 247. The second supply line 246 can include a second supply valve 242 that can be opened to connect the second supply line 246 to the common supply line 247.

[0025] The first supply line 245 can have an inner diameter smaller than that of the second supply line 246. In some embodiments, the inner diameter of the first supply line 245 can be about 5% to about 90%, such as about 10% to about 50% of the inner diameter of the second supply line 246. The smaller diameter of the first supply line 245 can be used to slowly increase the pressure in the internal space 205 from the vacuum pressure (e.g., between about 2 to 20 Torr, such as between about 3 to 5 Torr) used for the pre-cleaning process after the pre-cleaning process is performed on the substrate 50. On the other hand, the second supply line 246 can be used to quickly return the pressure to atmospheric pressure or a pressure close to atmospheric pressure after the pressure in the internal space 205 reaches a higher pressure (e.g., 300 Torr) from the gas supplied from the smaller first supply line 245. By slowly increasing the pressure after the pre-cleaning process, it is possible to prevent the substrate 50 from being damaged by sudden pressure changes, such as mechanical damage caused by wobbling or unintentionally moving the substrate 50.

[0026] Using different supply lines with different inner diameters is one way to vary the speed at which gas is supplied to the internal space 205. In other embodiments, for example, an analog control valve on a single supply line can be used to achieve slower pressure changes. In some of these other embodiments, a sensor, such as 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 internal space 205 increases when an inert gas is supplied to the internal space 205, thereby achieving a slower pressure change in the internal space 205.

[0027] The processing system 200 can further include a vacuum pump 218 configured to exhaust gas from the pre-cleaning chamber 201 through the exhaust port 223 of the pre-cleaning chamber 201. The vacuum pump 218 can be connected to the exhaust port 223 through the first exhaust line 261 or the second exhaust line 262 of the processing system 200. The first exhaust line 261 and the second exhaust line 262 can be arranged to form parallel (i.e., alternative) paths with respect to each other so that gas can be exhausted from the pre-cleaning chamber 201 through one of the exhaust lines without passing through other exhaust lines. The first exhaust line 261 and the second exhaust line 262 can be connected to the exhaust port 223 through a common exhaust line 263. The first exhaust line 261 can include a first exhaust valve 219 that can be opened to fluidly couple the first exhaust line 261 to the common exhaust line 263. The second exhaust line 262 can include a second exhaust valve 239 that can be opened to fluidly couple the second exhaust line 262 to the common exhaust line 263.

[0028] The first exhaust line 261 can have an inner diameter smaller than that of the second exhaust line 262. All references to inner diameter made in the present disclosure also apply to the internal cross-sectional area, for example, when a component (such as a fluid conduit) has a non-circular cross-section. In some embodiments, the inner diameter of the first exhaust line 261 can be, for example, about 5% to about 75%, such as 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 lower the pressure in the internal space 205 from atmospheric pressure or a pressure close to atmospheric pressure (for example, 700 to 800 Torr) to a lower pressure, such as about 400 to 650 Torr, such as about 600 Torr. The pressure reduction can be performed, for example, after the substrate 50 is transferred from the transfer chamber 102 maintained at atmospheric pressure or a pressure close to atmospheric pressure into the pre-cleaning chamber 201. On the other hand, the second exhaust line 262 can be used to rapidly lower the pressure in the internal space 205 to a pressure close to the pressure used for the pre-cleaning plasma process, such as a pressure between about 300 mTorr and about 5 Torr, such as about 100 mTorr to about 20 Torr, such as a pressure less than 50 Torr. After the substrate 50 is transferred into the pre-cleaning chamber 201, by slowly reducing the pressure, it is possible to prevent the substrate 50 from being damaged by sudden pressure changes, such as mechanical damage caused by wobbling or unintentionally moving the substrate 50 otherwise.

[0029] Using different exhaust lines with different inner diameters is one way to vary the speed at which gas and / or plasma is exhausted from the internal space 205 so that a slower pressure change in the internal space 205 can be achieved. In other embodiments, for example, an analog control valve on a single exhaust line can be used to achieve a slower pressure change. In some of these other embodiments, when the internal space 205 is brought to a vacuum pressure for performing a plasma pre-cleaning process, a sensor such as 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 internal space 205 drops.

[0030] As introduced above, the substrate support assembly 216 includes a substrate support 232, an actuator 234, and a shaft 236 that connects the actuator 234 to the substrate support 232. The shaft 236 can extend through a centrally located opening formed in the bottom 211 of the chamber body 210. The actuator 234 can be flexibly sealed to the bottom 211 of the chamber body 210 by a bellows (not shown) that prevents vacuum leakage around the shaft 236. The actuator 234 enables the substrate support 232 to be vertically moved within the chamber body 210 between a process position and a lower transfer position. The transfer position can be slightly below the opening of the slit valve 215 formed through one of the one or more walls 212 of the chamber body 210.

[0031] Although not shown, in some embodiments, an RF and / or DC bias can be coupled to the substrate support 232 to assist in guiding the cleaning plasma toward the substrate 50.

[0032] The processing system 200 can further include an auxiliary exhaust assembly 270. The auxiliary exhaust assembly 270 can 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 can further include a vacuum pump or other device for generating a negative pressure in the auxiliary exhaust assembly 270 lines with respect to the internal space 205 of the pre-cleaning chamber 201 such that when the valve of the auxiliary exhaust assembly 270 is opened, gas is exhausted from the internal space 205 through the auxiliary exhaust assembly 270.

[0033] The common auxiliary exhaust line 278 can be connected to the internal space 205 of the pre-cleaning chamber 201. The first auxiliary exhaust line 275 and the second auxiliary exhaust line 276 can be connected to the internal space 205 of the pre-cleaning chamber 201 through the common auxiliary exhaust line 278. The first auxiliary exhaust line 275 can include a first auxiliary exhaust valve 272 that can be opened to connect the first auxiliary exhaust line 275 to the common auxiliary exhaust line 278. The second auxiliary exhaust line 276 can include a second auxiliary exhaust valve 274 that can be opened to connect the second auxiliary exhaust line 276 to the common auxiliary exhaust line 278.

[0034] The first auxiliary exhaust valve 272 can be opened when a high-pressure state occurs. The first auxiliary exhaust line 275 can include a pressure sensor 271 for measuring the pressure within the first auxiliary exhaust line 275. When a pressure exceeding a given threshold (e.g., 800 torr) is measured, the first auxiliary exhaust valve 272 can be opened to release the pressure within the internal space 205. The pre-cleaning chamber 201 is operated at a higher pressure than other pre-cleaning chambers that generally operate at a vacuum pressure (e.g., less than 100 torr) for pre-cleaning processes and substrate transfer. As a result, more components of the pre-cleaning chamber are fastened to each other or otherwise fixed. For example, the components of the lid assembly 214 can be fixed to other components within the lid assembly 214 and / or to the chamber wall 212. Some of these components within the lid assembly are generally not fixed for pre-cleaning chambers that operate at a vacuum pressure for pre-cleaning processes and substrate transfer to and from the pre-cleaning chamber. The additional fastening of the components within the pre-cleaning chamber 201 can help prevent the movement of any of the components during the pressure changes that occur for each substrate pre-cleaning and transfer, as will be explained in more detail below. However, fixing these components can pose safety issues as components that were not previously fixed may be able to move to release a high-pressure situation. Within the pre-cleaning chamber 201, the first auxiliary exhaust valve 272 can open to release the high-pressure state when measured by the pressure sensor 271 and prevent a dangerous high-pressure state from occurring.

[0035] When the slit valve 215 is open, the second auxiliary exhaust valve 274 can be opened, thereby allowing gas to flow from the internal space 205 to the outside of the auxiliary exhaust assembly 270. The internal space 205 of the pre-cleaning chamber 201 is generally considered to be less clean than the internal space of the transfer chamber 102. Therefore, gas should not flow from the internal space 205 of the pre-cleaning chamber 201 to the internal 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 internal space 205 drops relative to the pressure in the internal space of the transfer chamber 102, and gas flows from the internal space of the transfer chamber 102 through the internal space 205 of the pre-cleaning chamber 201 and out through the auxiliary exhaust assembly 270.

[0036] The processing system 200 can also include a controller 290 for controlling processes within the processing system 200 (FIG. 2) and other parts of the cluster tool 100 (FIG. 1). The controller 290 can be any type of controller used in an industrial environment, such as a programmable logic controller (PLC). The controller 290 includes a processor 292, a memory 294, and an input / output (I / O) circuit 296. The controller 290 can further include one or more of components (not shown), such as one or more power supplies, a clock, a communication component (e.g., a network interface card), and a user interface commonly found in controllers for semiconductor devices.

[0037] Memory 294 can include non-transitory memory. The non-transitory memory can be used to store the programs and settings described below. Memory 294 can include one or more readily available types of memory, such as read-only memory (ROM) (e.g., electrically 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)).

[0038] Processor 292 is configured to execute various programs stored in memory 294, such as a program configured to execute method 1000 described below with reference to FIG. 3. During the execution of these programs, controller 290 can communicate with I / O devices (e.g., sensors and actuators) through I / O circuit 296. For example, during the execution of these programs and communication via the I / O circuit, controller 290 can control the output (e.g., open and close a valve) and receive information from a feedback device (e.g., feedback regarding the open / closed state of the valve), a sensor, and other instruments in other parts of processing system 200 and cluster tool 100.

[0039] Memory 294 can further include various operation settings used to control processing system 200 and other parts of cluster tool 100. For example, the settings can include pressure settings regarding when, among various settings, the transition between slowly changing the pressure in internal space 205 and changing it more rapidly occurs in method 1000, as described below with reference to FIG. 3.

[0040] FIG. 3 is a process flow diagram of a method 1000 for performing a pre-cleaning process on a substrate 50 according to one embodiment. The method 1000 will be described with reference to FIGS. 1-3. The controller 290 can execute a program stored in the memory to perform the method 1000. The method starts at block 1002.

[0041] 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, both the internal space of the transfer chamber 102 and the internal space 205 of the pre-cleaning chamber 201 are at or near atmospheric pressure. The slit valve 215 of the pre-cleaning chamber 201 can be opened, and the transfer robot 104 can place the substrate 50 on the substrate support 232 in the internal space 205 of the pre-cleaning chamber 201. The second auxiliary exhaust valve 274 can open when or slightly before the slit valve 215 is opened, allowing gas to flow from the inside of the transfer chamber 102 into the internal space 205 of the pre-cleaning chamber 201 and out through the auxiliary exhaust assembly 270 connected to a low-pressure outlet (not shown). Flowing gas from the transfer chamber 102 into the pre-cleaning chamber 201 helps maintain a clean environment inside the transfer chamber 102 and other parts of the cluster tool outside the pre-cleaning chamber.

[0042] In block 1004, the slit valve 215 is closed and a slow pump-down of the pre-cleaning chamber 201 is performed. When the slow pump-down starts, the internal space 205 of the pre-cleaning chamber 201 is at atmospheric pressure or a pressure close to atmospheric pressure. The slow pump-down of the internal space 205 is performed by activating the vacuum pump 218 and opening the first exhaust valve 219. The slow pump-down continues until a first target exhaust pressure in the internal space 205, measured by the pressure sensor 260, is reached. In some embodiments, the first target exhaust pressure can be, for example, about 400 Torr to about 700 Torr, such as about 600 Torr. The first exhaust valve 219 is located on a first exhaust line 261 having an inner diameter smaller than that of the second exhaust line 262. The smaller diameter of the first exhaust line 261 can be used to smoothly and slowly lower the pressure in the internal space 205 until the first target exhaust pressure is reached. In some embodiments, the slow pump-down can take, for example, about 5 seconds to about 100 seconds, such as about 20 seconds. The slow pump-down helps prevent damage to the substrate 50, which can occur due to movement (e.g., wobbling or otherwise unintended movement) of the substrate 50 when the substrate 50 is exposed to a rapid pressure change, for example, when a faster pump-down of the internal space 205 is performed in block 1004 without first performing the slow pump-down.

[0043] In block 1006, a faster pump-down of the internal space 205 of the pre-cleaning chamber 201 is performed from the first target exhaust pressure (e.g., 600 Torr) reached in block 1004 to a lower target exhaust pressure measured by the pressure sensor 260 for the pre-cleaning plasma process. The lower target exhaust pressure can be, for example, between about 100 mTorr and about 20 Torr, such as between about 300 mTorr and about 5 Torr. The faster pump-down of the internal space 205 is performed by opening the second exhaust valve 239 to connect the internal space 205 of the vacuum pump 218 through the second exhaust line 262. In block 1006, the first exhaust valve 219 can be closed. The second exhaust line 262 has a larger (e.g., greater than 100%) inner diameter than the first exhaust line 261, thereby enabling the pressure in the internal space 205 to be reduced more rapidly in response to pressure changes during the slow pump-down in block 1004. In some embodiments, the fast pump-down can take, for example, about 3 seconds to about 50 seconds, such as about 10 seconds.

[0044] In block 1008, a plasma pre-cleaning process is performed on the substrate 50 in the internal space 205 of the pre-cleaning chamber 201. The pre-cleaning process can include supplying one or more cleaning gases (e.g., NF3, NH, and H2) to the remote plasma source 220, generating a plasma of one or more cleaning gases in the remote plasma source 220, and supplying the plasma of one or more cleaning gases to the internal space 205 of the pre-cleaning chamber 201 through the showerhead 230 until the cleaning process in block 1008 is completed (e.g., after a specified period). In one embodiment, a plasma of one or more cleaning gases can be used to remove oxides from the substrate 50.

[0045] In block 1010, after the cleaning process in block 1008 is completed, a slow filling of the internal space 205 of the pre-cleaning chamber 201 with an inert gas (e.g., N2) is performed. The plasma pre-cleaning process performed in block 1008 is carried out at a vacuum pressure (e.g., 3 Torr). Therefore, the slow filling process in block 1010 starts at the vacuum pressure when block 1008 ends. The slow filling of the internal space 205 of the pre-cleaning chamber 201 is performed by opening the first supply valve 241 on the first supply line 245 that connects the inert gas source 240 to the gas inlet 226 of the pre-cleaning chamber 201 through the first supply line 245.

[0046] The slow filling in block 1010 continues until the first target supply pressure in the internal space 205, measured by the pressure sensor 260, is reached. In some embodiments, the first target supply pressure can be from about 100 Torr to about 500 Torr, such as about 300 Torr. The first supply valve 241 is located on the first supply line 245 having an inner diameter smaller than that of 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 internal space 205 until the first target supply pressure is reached. In some embodiments, the slow filling can take from about 5 seconds to about 100 seconds, such as about 20 seconds. The slow filling helps to prevent damage to the substrate 50, which can occur due to movement of the substrate 50 (e.g., wobbling or otherwise unintended movement) when the substrate 50 is exposed to a rapid pressure change, for example, when a faster filling of the internal space 205 is performed without first performing the slow filling in block 1010.

[0047] In block 1012, a rapid filling of the internal space 205 of the pre-cleaning chamber 201 is performed from the first target supply pressure (e.g., 200 torr) reached in 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 filling of the internal space 205 is performed by opening a second supply valve 242 that connects an inert gas source 240 to the gas inlet 226 of the pre-cleaning chamber 201 through a second supply line 246.

[0048] In block 1012, the first supply valve 241 can be closed. The second supply line 246 has a larger (e.g., larger than 100%) inner diameter than the first supply line 245, thereby enabling the pressure in the internal space 205 to be increased more rapidly with respect to the pressure change during slow filling in block 1010. In some embodiments, the rapid filling can take from about 3 seconds to about 50 seconds, such as about 10 seconds.

[0049] In block 1014, with the internal space 205 at atmospheric pressure or a pressure close to atmospheric pressure, the substrate 50 can be removed from the pre-cleaning chamber 201. The slit valve 215 of the pre-cleaning chamber 201 can be opened, and the transfer robot 104 can remove the substrate 50 from the substrate support 232. The second auxiliary exhaust valve 274 can be opened when the slit valve 215 is opened or slightly before the slit valve 215 is opened, thereby enabling gas to flow from the inside of the transfer chamber 102 into the internal space 205 of the pre-cleaning chamber 201 and out through an auxiliary exhaust assembly 270 connected to a low-pressure outlet (not shown). Allowing gas to flow from the transfer chamber 102 into the pre-cleaning chamber 201 helps maintain a clean environment in the transfer chamber 102 and other parts of the cluster tool 100 outside the pre-cleaning chamber 201.

[0050] After being removed from the pre-cleaning chamber 201, the pre-cleaned substrate 50 can be transferred into one of the process chambers 108, 110 so that additional processes, such as epitaxial deposition performed at atmospheric pressure or a pressure close to atmospheric pressure, can be performed on the substrate 50.

[0051] In block 1016, a determination is made as to whether the pre-cleaning process should be performed on another substrate 50. If another substrate 50 should be pre-cleaned, blocks 1002-1014 can be repeated for the next substrate 50. This repetition can continue until the target number of substrates 50 have been pre-cleaned using method 1000.

[0052] The equipment and processes described in this disclosure enable a plasma pre-cleaning process at a vacuum pressure (e.g., 3 Torr) to be performed on a substrate in the pre-cleaning chamber when the pre-cleaning chamber is connected to equipment that operates at a substantially higher pressure, such as atmospheric pressure. For example, all other parts of the cluster tool 100, such as the transfer chamber 102, the process chambers 108, 110, and the load lock chambers 106A, 106B, can operate at a substantially higher pressure, such as atmospheric pressure. By starting the pressure change for the internal space 205 of the pre-cleaning chamber 201 in a slower manner with the slow pump-down in block 1004 and the slow fill in block 1010, and then increasing the rate of the pressure change for the internal space 205 with the faster pump-down in block 1006 and the fast fill in block 1012, the risk of damaging the substrate 50 due to a rapid pressure change (e.g., mechanical damage caused by wobbling or unintentionally moving the substrate) remains low, and a large number of substrates 50 can be pre-cleaned quickly and efficiently.

[0053] The above is directed to embodiments of the present disclosure, but other further embodiments of the present disclosure may be devised without departing from the basic scope of the present disclosure.

Claims

1. A plasma processing system for cleaning a substrate, said plasma processing system comprising: a process chamber comprising a chamber body surrounding an internal space, and a substrate support disposed within said internal space ; a vacuum pump; a first exhaust line fluidly coupled between said internal space of said process chamber and said vacuum pump; a second exhaust line fluidly coupled between said internal space of said process chamber and said vacuum pump; and wherein said first exhaust line and said second exhaust line are arranged to provide alternative paths for exhausting between said internal space and said vacuum pump, and wherein said first exhaust line has an inner diameter that is at least 50% smaller than the inner diameter of said second exhaust line.

2. receiving a substrate on said substrate support at the start of a first period; reducing the pressure within said internal space until a first exhaust pressure within said internal space is reached during said first period, and opening a first exhaust valve on said first exhaust line to exhaust said internal space of said process chamber through said first exhaust line; further reducing the pressure to exhaust said internal space of said process chamber through said second exhaust line until a second exhaust pressure within said internal space is reached during said first period, and opening a second exhaust valve on said second exhaust line; performing an initial process on said substrate within said internal space of said process chamber during said first period after said second exhaust pressure is reached; and further comprising a controller configured to perform the above.

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

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

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

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

7. Opening a first supply valve on the first supply line to supply gas from the gas source to the internal space of the process chamber through the first supply line until a first supply pressure in the internal space is reached; Opening a second supply valve on the second supply line to supply gas from the gas source to the internal space of the process chamber through the second supply line until a second supply pressure in the internal space is reached; The plasma processing system according to claim 5, further comprising a controller configured to perform the above operations.

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

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

10. A plasma processing system for cleaning a substrate, wherein the plasma processing system includes a process chamber having a chamber body surrounding an internal space, and a substrate support disposed within the internal space ; a process chamber; a gas source fluidly coupled to the internal space; a first supply line fluidly coupled between the internal space and the gas source; and a second supply line fluidly coupled between the internal space and the gas source ; wherein the first supply line and the second supply line are arranged to provide alternative paths between the internal space and the gas source, and the first supply line has an inner diameter that is at least 50% smaller than the inner diameter of the second supply line. A plasma processing system.

11. Executing a process on a substrate disposed on the substrate support within the internal space of the process chamber during a first period; Increasing the pressure within the internal space until a first supply pressure within the internal space is reached during the first period, and opening a first supply valve on the first supply line to supply gas from the gas source to the internal space of the process chamber through the first supply line; Further increasing the pressure within the internal space until a second supply pressure within the internal space is reached during the first period, and opening a second supply valve on the second supply line to supply gas from the gas source to the internal space of the process chamber through the second supply line; Removing the substrate from the process chamber during the first period after reaching the second supply pressure The plasma processing system according to claim 10, further comprising a controller configured to perform the above operations.

12. The plasma processing system according to claim 11, wherein the first supply pressure is less than 300 Torr.

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

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

15. A cluster tool for processing a semiconductor substrate, wherein the cluster tool comprises a transfer chamber, a deposition chamber coupled to the transfer chamber, and a plasma processing system coupled to the transfer chamber and includes, the plasma processing system is a process chamber, a chamber body surrounding an internal space, and a substrate support disposed within the internal space a process chamber, a vacuum pump, a first exhaust line fluidly coupled between the internal space of the process chamber and the vacuum pump, and a second exhaust line fluidly coupled between the internal space of the process chamber and the vacuum pump and includes, the cluster tool, wherein the first exhaust line and the second exhaust line are arranged to provide an alternative path for exhausting between the internal space and the vacuum pump.

16. Receiving a substrate on the substrate support at the start of a first period, Reduce the pressure in the internal space until the first exhaust pressure in the internal space is reached during the first period, and open the first exhaust valve on the first exhaust line to exhaust the internal space of the process chamber through the first exhaust line. Open the second exhaust valve on the second exhaust line to further reduce the pressure so as to exhaust the internal space of the process chamber through the second exhaust line until the second exhaust pressure in the internal space is reached during the first period. Execute an initial process on the substrate in the internal space of the process chamber during the first period after the second exhaust pressure is reached. The cluster tool according to claim 15, further comprising a controller configured to perform the above.

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

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

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

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

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