JP4916140B2 - Vacuum processing system - Google Patents

Description

  The present invention relates to a vacuum processing system that performs a desired process on an object to be processed in a reduced pressure state, and more particularly to a vacuum processing system including a load lock chamber.

  A cluster tool vacuum processing system is a multi-chamber device in which a plurality of processing chambers are arranged around a transfer chamber in order to achieve process coherence, connection or combination, and is typically employed in semiconductor manufacturing equipment. (For example, refer to Patent Document 1). In each processing chamber, various processes such as a film forming process, a cleaning process, and a dry etching process are performed on the target object under reduced pressure. Since the object to be processed is carried into and out of each processing chamber by the transfer mechanism of the transfer chamber under reduced pressure, the inside of the transfer chamber is also always kept in a reduced pressure state. In order to carry an untreated object to be processed from the atmospheric space into the main transfer chamber in such a reduced pressure state, the processed object that has been subjected to a series of vacuum processing in the system is carried out from the reduced pressure transfer chamber to the atmospheric space. For this purpose, a load lock chamber is connected to the main transfer chamber as an interface.

  An unprocessed object such as a semiconductor wafer is carried into the load lock chamber under atmospheric pressure. In the load lock chamber, when an unprocessed semiconductor wafer is loaded, the gate valve on the atmosphere side is closed and a vacuum is drawn to switch the chamber from the atmospheric state to the vacuum state. After a certain period of time, the gate valve on the vacuum side of the load lock chamber is opened, and the transfer mechanism in the transfer chamber takes out the semiconductor wafer from the load lock chamber. Thereafter, the semiconductor wafer is transferred in a predetermined order to a plurality of processing chambers in the system by the transfer mechanism of the transfer chamber and is subjected to a required process in each processing chamber. When a series of processing is completed in the system, the processed semiconductor wafer is returned from the transfer chamber to the vacuum load lock chamber. Thereafter, the load lock chamber is switched from the vacuum state to the atmospheric pressure state, the gate valve on the atmosphere side is opened, and the processed semiconductor wafer is carried out to the atmosphere space.

The cluster tool system as described above is increasingly used for in-line of various vacuum processes accompanying the miniaturization and high performance of semiconductor devices. And the process processing of high vacuum degree (10 <^-4> Pa or less) is oriented according to the high precision of a process, and the pressure in each processing chamber in a system is becoming increasingly low. Further, the interior of the transfer chamber, which is always evacuated during the operation of the system, is also maintained at a pressure of 10 mTorr (about 1.33 Pa) or less. As described above, the load lock chamber has a structure that can be selectively switched between the atmospheric pressure state and the vacuum state, and is evacuated when changing from the atmospheric pressure state to the vacuum state.
Japanese Patent Laid-Open No. 2000-127069

  However, in the vacuum processing system, a problem of organic matter contamination in which organic matter generated from a movable part or a rubbing part in the system adheres to the object to be treated has become apparent. In particular, in a cluster tool vacuum processing system, the total number of processes in the system is large, so the total processing time, that is, the stay time of the workpiece, is long, and the space in each chamber is relatively small, so it occurs somewhere in the system. The probability that the floating organic substance adheres to the object to be processed is much higher than the probability that the organic substance floating in the clean room under the atmosphere adheres to the object to be processed. Such adhesion or contamination of the organic matter greatly reduces the reliability of the process such as the film formation process and the etching process in the processing chamber and the manufacturing yield. In particular, organic substances generated or scattered from grease applied to O-rings or bearings used for vacuum sealing, organic substances generated from a transport mechanism (for example, a transport belt), or adhered to the surface of each part in the processing chamber due to poor cleaning, etc. When the organic matter adheres to the surface of the object to be processed, it is difficult to remove the organic substance and the defective area of the surface to be processed becomes wide, so that the manufacturing yield is significantly reduced.

  As a result of repeated experiments and examinations, the present inventor has found that the object to be processed is easily contaminated with organic matter particularly in the load lock chamber in the vacuum processing system of the cluster tool.

The present invention has been made in view of the problems and circumstances of the prior art as described above, and is a vacuum processing system in which an object to be processed is not contaminated with organic matter in the system (particularly in a load lock chamber). The purpose is to provide.

In order to achieve the above object, a first vacuum processing system of the present invention is a transport in which a chamber is kept in a reduced pressure state and a transport mechanism is provided for transporting an object to be processed between the chamber and an adjacent chamber. A chamber, a vacuum processing chamber provided adjacent to the transfer chamber, in which predetermined processing is performed on an object to be processed in a room under reduced pressure, and a chamber provided adjacent to the transfer chamber, wherein the chamber is selectively in an atmospheric state. Alternatively, a load lock chamber that is switched to a depressurized state and temporarily holds an object to be transferred between the atmospheric space and the transfer chamber, a first exhaust unit that evacuates the load lock chamber, and A first purge gas supply section for supplying purge gas into the load lock chamber; and an exhaust operation of the first exhaust section and a purge gas supply operation of the first purge gas supply section for controlling the pressure in the load lock chamber. At least one Possess a Gosuru control unit, the load lock chamber, wherein the mounting table having a plurality of through-holes for mounting the object to be processed by a single unit, a cylindrical base supporting the mounting table A lift pin mechanism having a plurality of lift pins configured to be movable up and down through the plurality of through holes of the mounting base inside the cylindrical base, and the lift pin mechanism and the load inside the cylindrical base An elevating drive shaft for connecting an elevating drive unit provided in an atmospheric space below the lock chamber, and a seal member provided at the bottom of the load lock chamber in order to keep a vacuum airtight in the room with respect to the elevating drive shaft A gas introduction hole provided at a position higher than the mounting table for introducing the purge gas from the first purge gas supply unit into the room, and the mounting table for sending the indoor gas to the first exhaust unit. And an exhaust port provided at a position close to the seal member, the exhaust port being provided on the outside of the cylindrical base, with a predetermined interval in the circumferential direction on the side wall of the cylindrical base A plurality of openings are formed.

The second vacuum processing system of the present invention is provided with a transfer chamber provided with a transfer mechanism for transferring an object to be processed between a room and an adjacent chamber, and adjacent to the transfer chamber, and is under reduced pressure. A vacuum processing chamber in which predetermined processing is performed on the object to be processed in the chamber, and adjacent to the transfer chamber, the chamber is selectively switched to an atmospheric state or a reduced pressure state, and the atmosphere space and the transfer chamber A load lock chamber that temporarily holds the object to be transferred between the first and second exhaust units, a first exhaust unit that evacuates the load lock chamber, and a first purge gas supply unit that supplies purge gas into the load lock chamber. A first control unit that controls at least one of an exhaust operation of the first exhaust unit and a purge gas supply operation of the first purge gas supply unit in order to control the pressure in the load lock chamber; and the transfer chamber Evacuate A second exhaust unit, a second purge gas supply unit that supplies purge gas into the transfer chamber, and an exhaust operation of the second exhaust unit and the second purge gas to control the pressure in the transfer chamber And a second control unit that controls at least one of purge gas supply operations of the supply unit, and a mounting table that has a plurality of through holes in the load lock chamber for mounting the objects to be processed one by one. And a cylindrical base for supporting the mounting table, and a lift pin mechanism having a plurality of lift pins configured to be movable up and down through the plurality of through holes of the mounting table inside the cylindrical base, A lift drive shaft that connects the lift pin mechanism inside the cylindrical base and a lift drive unit provided in an atmospheric space below the load lock chamber, and maintains a vacuum airtight in the chamber with respect to the lift drive shaft For this purpose, a seal member provided at the bottom of the load lock chamber, a gas introduction hole provided at a position higher than the mounting table for introducing the purge gas from the first purge gas supply unit into the room, and gas in the room An exhaust port provided at a position lower than the mounting table and close to the seal member for sending to the first exhaust unit, the exhaust port being provided outside the cylindrical base, and the cylindrical shape A plurality of openings are formed in the side wall of the base at predetermined intervals in the circumferential direction.

Oite to the above configuration, in a vacuum processing system, in particular away organics from organic member leaving a load lock chamber, it is also scattered or floating, the mean free path of the organic material is suppressed by the purge gas, or Since the organic substance is effectively discharged out of the load lock chamber together with the purge gas, adhesion of the organic substance to the surface of the object to be processed is effectively suppressed. In particular, even if organic matter is generated or scattered from the seal member provided at the bottom of the load lock chamber in order to maintain a vacuum tightness in the room with respect to the lift drive shaft for lifting the lift pin, it passes through the through hole of the mounting table through which the lift pin passes. Instead of going to the object to be processed, it is quickly sent to the exhaust port together with the purge gas through the opening of the cylindrical base, and is discharged by the first exhaust part. Thereby, the adhesion of organic substances to the surface of the object to be processed is further effectively suppressed.

  According to a preferred aspect of the present invention, the pressure in the load lock chamber is made higher than the pressure in the transfer chamber. Here, the pressure in the load lock chamber is controlled to several tens to several hundreds Pa. Further, the pressure in the transfer chamber is controlled to several tens to several hundreds Pa. Under such pressure conditions, in both the load lock chamber and the transfer chamber, it is possible to prevent or reduce organic substances from adhering to the surface of the object to the maximum, and when the opening / closing part between the two chambers is opened, the load lock chamber Since purge gas flows into the transfer chamber from the inside, it is possible to reliably prevent the organic matter in the transfer chamber from entering the load lock chamber.

  According to a preferred aspect of the present invention, the load lock chamber has a plurality of through holes for mounting the objects to be processed in units of one sheet, and each of the plurality of through holes of the mounting table is penetrated. A lift pin mechanism having a plurality of lift pins configured to be movable up and down, a lift drive shaft that connects the lift pin mechanism and a lift drive unit provided in an atmospheric space under the load lock chamber, and the lift drive A seal member provided at the bottom of the load lock chamber to maintain a vacuum tightness in the room with respect to the shaft, and a gas introduction provided at a position higher than the mounting table for introducing the purge gas from the first purge gas supply unit into the room A hole and an exhaust port provided at a position lower than the mounting table and close to the seal member are provided in order to send indoor gas to the first exhaust unit.

  In this case, the mounting table may be composed of a cooling plate having a high thermal conductivity. Further, it is preferable that a part of the purge gas introduced from the gas introduction hole in the load lock chamber flows through the vicinity of the seal member to the exhaust port.

  According to the vacuum processing system of the present invention, the organic matter contamination of the object to be processed can be remarkably reduced by the configuration and operation as described above even if organic members or organic substances are present in the vacuum processing system.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings.
FIG. 1 shows a configuration of a vacuum processing system for a cluster tool according to an embodiment of the present invention. This vacuum processing system is installed in a clean room and has, for example, four process modules PM ₁ , PM ₂ , PM ₃ , PM ₄ and two load locks around a hexagonal transfer module TM having a transfer chamber 10. Modules LLM ₁ and LLM ₂ are arranged in a cluster.

The process modules PM ₁ , PM ₂ , PM ₃ , and PM ₄ have vacuum processing chambers (process chambers) 12, 14, 16, and 18 in which chamber pressures are individually set or controlled. The load lock modules LLM ₁ and LLM ₂ respectively have load lock chambers 20 and 22 that can be selectively switched to an atmospheric pressure state or a vacuum state as will be described later. The vacuum processing chamber 12, 14, 16, 18 are respectively connected to the gate valve _{GV 1, GV 2, GV 3} , the transfer chamber 10 via the GV _4. The load lock chambers 20 and 22 are connected to the transfer chamber 10 via gate valves GV _T and GV _T , respectively. The interior of the transfer chamber 10 of the transfer module TM is maintained in a reduced pressure state at a predetermined pressure. In addition, a vacuum transfer robot 28 having a pair of transfer arms 24 and 26 that can turn and extend is provided in the room.

The process modules PM ₁ , PM ₂ , PM ₃ , and PM ₄ use a predetermined utility (processing gas, high frequency, etc.) in each processing chamber 12, 14, 16, 18 to perform required single wafer processing, for example, CVD. (Chemical Vapor Deposition), ALD (Atomic Layer Deposition), PVD (Physical Vapor Deposition), and other film forming processes, heat treatment, semiconductor wafer surface cleaning process, dry etching process, and the like are performed.

Also in the load lock chambers 20 and 22 of the load lock modules LLM ₁ and LLM ₂ , pressure and atmosphere control as described later is performed. These load lock chambers 20 and 22, the transfer module TM side viewed from the gate to the wafer transfer chamber 30 of the loader module LM is under atmospheric pressure on the opposite side valve GV _R, are connected via the GV _R.

  A load port LP and an orientation flat aligning mechanism ORT are provided adjacent to the loader module LM. The load port LP is used for loading and unloading a wafer cassette CR that can store, for example, 25 batches of semiconductor wafers W with an external transfer vehicle. The orientation flat alignment mechanism ORT is used to align the orientation or notch of the semiconductor wafer W with a predetermined position or orientation.

The atmospheric transfer robot 32 provided in the loader module LM has an extendable transfer arm, can move horizontally on a linear guide (linear slider) 34, and can move up and down and turn. The semiconductor wafer W is transferred between the load port LP, the orientation flat alignment mechanism ORT, and the load lock modules LLM ₁ and LLM ₂ and transferred in units of _single wafers (or batch units). Here, the atmospheric transfer robot 32 carries the wafer W into the loader module LM when the LP door (not shown) provided on the front surface of each wafer cassette CR is open. The linear guide 34 includes, for example, a permanent magnet, a driving magnetic coil, a scale head, and the like, and performs linear motion control of the atmospheric transfer robot 32 according to a command from the host controller.

FIG. 2 shows a configuration of a pressure control mechanism for controlling the pressure in the load lock chambers 20 and 22 of the load lock modules LLM ₁ and LLM ₂ and the pressure in the transfer chamber 10 of the transfer module TM.

  An exhaust mechanism 38 is connected to the load lock chamber 20 (22) via an exhaust valve 36. The exhaust mechanism 38 includes an exhaust pump such as a dry pump or a turbo molecular pump, and can evacuate the interior of the load lock chamber 20 (22).

A predetermined purge gas, for example, N ₂ gas is supplied from the purge gas supply unit 44 to the load lock chamber 20 (22) via the flow rate adjusting valve 40 or the open / close valve 42 connected in parallel. The flow rate adjustment valve 40 is controlled by the controller 48 in terms of valve opening. This flow rate adjustment is performed by feedback control based on the output signal of the vacuum gauge 46 that measures the pressure in the load lock chamber 20 (22). The on-off valve 42 is opened when the inside of the load lock chamber 20 (22) is moved from the reduced pressure state to the atmospheric pressure state by supplying purge gas. The on-off valve 42 and the exhaust valve 36 are controlled by another controller (not shown).

  While the semiconductor wafer W stays in the load lock chamber 20 (22), the exhaust mechanism 38 exhausts the chamber with a constant exhaust amount, and the controller 48, the vacuum gauge 46, and the flow rate adjustment valve 40 include the purge gas supply unit 44. The flow rate of the purge gas supplied from is controlled, and the pressure in the load lock chamber 20 (22) is maintained at the set value. Here, the set pressure in the load lock chamber 20 (22) is selected within a pressure range of several tens to several hundreds of Pa effective for preventing or reducing organic contamination, and a transfer chamber of the transfer module TM described later. The pressure may be higher than the pressure within 10, preferably within the range of 1 to 2 times.

An exhaust mechanism 52 is also connected to the transfer chamber TM of the transfer module TM via an exhaust valve 50. The exhaust mechanism 52 includes an exhaust pump such as a dry pump or a turbo molecular pump, and can evacuate the interior of the transfer chamber 10. A predetermined purge gas, for example, N ₂ gas is also supplied from the purge gas supply unit 58 to the transfer chamber 10 via the flow rate adjustment valve 54 and the opening / closing valve 56 connected in parallel. The flow rate adjusting valve 54 is controlled by the controller 62 using the output signal of the vacuum gauge 60 for measuring the pressure in the transfer chamber 10 as a feedback signal. The on-off valve 56 is normally fixed in a closed state and is opened when the inside of the transfer chamber 10 is brought into an atmospheric pressure state during maintenance work. The exhaust valve 50 and the opening / closing valve 56 are controlled by another controller (not shown).

  While the vacuum processing system is in operation, the exhaust mechanism 52 exhausts the room with a constant exhaust amount, and the flow rate of the purge gas supplied from the purge gas supply unit 58 by the controller 62, the vacuum gauge 60, and the flow rate adjustment valve 54 is reduced. Controlled, the pressure in the transfer chamber 10 is maintained at a set value. The set pressure in the transfer chamber 10 is preferably lower than the pressure in the load lock chamber 20 as described above, and is within a pressure range of several tens to several hundreds Pa that is effective for preventing or reducing organic contamination. You may be chosen.

3 and 4 show the configuration of the load lock module LLM ₁ in this embodiment. The other load lock module LLM ₂ has the same configuration. Hereinafter, the load lock module LLM ₁ will be described, and the description of the load lock module LLM ₂ will be omitted.

The load lock chamber 20 of the load lock module LLM ₁ is made of, for example, aluminum or stainless steel, and a wafer mounting table S for mounting the semiconductor wafer W is installed in the chamber. The wafer mounting table S is configured as a cooling plate made of a material having a high thermal conductivity, such as an aluminum plate, and has holes 64 for passing lift pins 66 at a plurality of positions, for example, three positions of the plate. Each lift pin 66 is fixed vertically to a horizontal support plate 68 disposed under the wafer mounting table S. The horizontal support plate 68 is connected to a lift drive unit 72 installed in the atmosphere below the load lock chamber 20 via a lift drive shaft 70. The elevating drive shaft 70 is airtightly introduced into the chamber by a seal portion 74 attached to the bottom of the load lock chamber 20. The elevating drive unit 72 includes, for example, an air cylinder, and moves the lift pins 66 up and down on the wafer mounting table S through the elevating drive unit 72 and the horizontal support plate 68 so as to appear and retract.

  The wafer mounting table S is fixed to the upper surface of a cylindrical base 78 fixed to the bottom surface of the load lock chamber 20. The cylindrical base 78 is made of a material having a high thermal conductivity, for example, a metal such as aluminum or a ceramic such as aluminum nitride. An opening 80 through which the elevating drive shaft 70 is passed is formed at the center of the bottom surface of the cylindrical base 78. Opening 82 for circulating the purge gas is formed at a plurality of locations at predetermined intervals in the circumferential direction.

  An exhaust port 84 is provided at one location adjacent to the side wall of the bottom 20 a of the load lock chamber 20. An exhaust mechanism 38 is connected to the exhaust port 84 via an exhaust pipe 85.

  Further, a purge gas supply pipe 86 is drawn into the chamber from a location that is substantially diagonal to the exhaust port 84 at the bottom 20 a of the load lock chamber 20. The purge gas supply pipe 86 extends vertically upward to a height position near the ceiling of the load lock chamber 20 and is bent horizontally near the top, and has a plurality of gas discharge holes 88a on the peripheral surface thereof. A purge gas nozzle 88 is attached. The purge gas supply pipe 86 is connected to the purge gas supply unit 44.

  Here, main operations in the vacuum processing system in this embodiment will be described.

In FIG. 1, first, the atmospheric transfer robot 32 of the loader module LM takes out one unprocessed semiconductor wafer W from the wafer cassette CR loaded in one of the load ports LP, and passes through the orientation flat alignment mechanism ORT. the gate valve GV _R load is better to open the lock chamber, for example, the load lock chamber 20 to carry the semiconductor wafer W of untreated. At this time, the interior of the load lock chamber 20 is in an atmospheric pressure state, and the lift pins 66 protrude above the mounting table S to receive the semiconductor wafer W from the atmospheric transfer robot 32, and the semiconductor wafer W is horizontally leveled at the received position. To support.

The load lock chamber 20, the semiconductor wafer W to untreated as described above is carried, the gate valve GV _R of the loader module LM side is closed immediately, is switched chamber from atmospheric pressure to reduced pressure .

FIG. 5A shows an embodiment of a pressure control sequence related to the load lock chamber 20 (22). Immediately prior to time t _1, the loader module gate valve GV _R of LM side is open, the flow rate adjusting valve 40 is fully closed, the opening and closing valve 42 is opened, the exhaust valve 36 has been closed. The gate valve GV _R of the loader module LM side is closed at time t _1. Then, immediately after time t ₂ , the exhaust valve 36 is switched to the open state, and vacuuming by the exhaust mechanism 38 starts. Further, at time t ₃ after several seconds, the opening / closing valve 42 is closed, and the controller 48 starts the valve opening control of the flow rate adjusting valve 40. In this manner, the interior of the load lock chamber 20 is evacuated by the exhaust mechanism 38 while the purge gas is supplied from the purge gas supply mechanism 44 so as to reach a set pressure in the range of several tens of Pa to several hundred Pa. become.

Here, the purge gas is, for example, high purity N ₂ gas, and the partial pressure of moisture and oxygen in the purge gas is preferably 10 ⁻⁴ Pa or less. As shown in FIG. 5A, the opening / closing valve 42 is opened before and after time t ₁ , and the load lock chamber 20 is in an N ₂ gas atmosphere. Thereby, it is possible to effectively prevent moisture or oxygen in the atmosphere in the wafer transfer chamber 30 of the loader module LM from entering the load lock chamber 20.

  In order to make the pressure in the load lock chamber 20 reach the set pressure of the vacuum, as shown by the solid line in FIG. 6, the pressure is gradually decreased from the atmospheric pressure toward the set pressure value. In this exhaust control, the controller 48 feeds back the pressure measurement value from the vacuum gauge 46 and gradually lowers the valve opening degree of the flow rate adjustment valve 40 from the fully open state.

As another evacuation control method, as shown by a dotted line in FIG. 6, there is a technique in which rapid evacuation is once reduced to a pressure considerably lower than the set pressure value and then gradually increased to the set pressure value. In this case, the value at which the pressure in the load lock chamber 20 becomes the lowest, that is, the minimum pressure value is, for example, 10 ⁰ Pa to 10 ⁻⁴ Pa.

  In any of the above two exhaust control methods, when the wafer W is loaded from the wafer transfer chamber 30 of the loader module LM into the load lock chamber 20, moisture or oxygen in the atmosphere of the wafer transfer chamber 30 is loaded. Even if it enters the lock chamber 20, these components can be effectively discharged out of the load lock chamber 20.

  As described above, when the inside of the load lock chamber 20 is changed from the atmospheric pressure state to the reduced pressure state of the set pressure, moisture or oxygen that enters or remains in the load lock chamber 20 is greatly reduced by the vacuum exhaust control method in this embodiment. Can be reduced. As a result, as will be described later, it is possible to effectively prevent or reduce the formation of a natural oxide film while staying on the surface of the semiconductor wafer W to be kept in the load lock chamber 20 under reduced pressure for a while. it can.

After reaching the chamber set pressure of the load lock chamber 20 from the time t ₃ of Figure 5A over several seconds (tens Pa~ several hundred Pa) is the exhaust system 38 to continue the evacuation of constant flow rate, the controller 48 is vacuum By automatically adjusting the supply flow rate of the purge gas from the purge gas supply mechanism 44 through the total 46 and the flow rate adjusting valve 40, the pressure in the load lock chamber 20 is maintained at the set pressure value. Thus, the unprocessed wafer W is kept in the load lock chamber 20 having a set pressure (several tens to hundreds of Pa) effective for preventing or reducing organic contamination for a certain period of time before undergoing a series of process processes. .

When unprocessed semiconductor wafer W as described above has passed a predetermined time from when carried into the load lock chamber 20, is opened the gate valve GV _T of the transfer chamber 10 side of the load lock chamber 20, transfer chamber 10 The vacuum transfer robot 28 takes out the semiconductor wafer W from the load lock chamber 20.

In this embodiment, since the pressure in the vacuum in the load lock chamber 20 is higher than the pressure in the transfer chamber 10, when the gate valve GV _T is opened, gas from the load lock chamber 20 into the transfer chamber 10 (mostly purge gas) Has come to flow.

Usually, since the vacuum transfer robot 28 is operating in the transfer chamber 10, the rate at which organic matter is generated or scattered is higher than in the load lock chamber 20 (22). However, the transport chamber 10 because of much greater space than the load lock chamber 20 (22), the probability of organic matter adhering to the semiconductor wafer W is lower transfer chamber 10. From another point of view, it is preferable to avoid the organic matter from moving from the former 10 to the latter 20 (22) as much as possible between the transfer chamber 10 and the load lock chamber 20 (22). In this embodiment, as described above, the pressure at the time of depressurization of the load lock chamber 20 is set higher than the pressure of the transfer chamber 10 (preferably within a range of 1 to 2 times). In the load lock chamber 20, organic contamination on the wafer surface is effectively prevented.

Also, by not unnecessarily large pressure differential between the transfer chamber 10 and load lock chamber 20 (22), preventing the generation of gas collision or shock wave between the two chambers when opening the gate valve GV _T In the transfer chamber 10, detachment or scattering of organic substances due to such a shock wave can be suppressed. As a result, even in the transfer chamber 10, the adhesion of organic substances to the surface of the wafer W can be further reduced.

Vacuum transfer robot 28 of the transfer chamber 10 has retrieved the unprocessed semiconductor wafer W from the load lock chamber 20 as described above, immediately carried to a predetermined process module PM _i. At that time, extracting one previous semiconductor wafer W from the process module PM _i just after completion process of the first step, therewith to carry the semiconductor wafer W of the unprocessed to turnover. Thus, each semiconductor wafer W is transferred in a predetermined order to the plurality of process modules PM _i , PM _{i + 1} ... In the system by the vacuum transfer robot 28 in the transfer chamber 10. A predetermined vacuum process is performed in the PM processing chamber. After the required series of processing is completed, the processed semiconductor wafer W is carried into the load lock chamber, for example, the load lock chamber 22, which is in an empty state by the vacuum transfer robot 28.

At this time, the load lock chamber 22 has become a vacuum of set pressure, the vacuum transfer robot 28 gate valve GV _T is opened to carry the processed semiconductor wafer W, the lift pins 66 receives this wafer W . Then, after the gate valve GV _T is closed vacuum transfer robot 28 is exited, the elevation drive unit 72 down the lift pins 66, the semiconductor wafer W is placed on the wafer table S. The wafer mounting table S is composed of a cooling plate having a high thermal conductivity as described above, and is temperature-controlled at a reference temperature near room temperature. By staying on the cooling plate S for a while, the temperature of the semiconductor wafer W is lowered to near room temperature.

Also in this case, since the pressure in the vacuum when the load lock chamber 22 is set higher than the pressure in the transfer chamber 10, when the gate valve GV _T is opened, the transfer chamber from the load lock chamber 22 10 Even if the organic matter moves in, the organic matter does not move in the opposite form, that is, from the inside of the transfer chamber 10 into the load lock chamber 22.

  While the semiconductor wafer W processed as described above stays in the load lock chamber 22, the pressure in the load lock chamber 22 is switched from the reduced pressure state to the atmospheric pressure state, for example, at the end of the stay time.

In the exhaust control of the load lock chamber 22 in this case, referring to the timing chart of FIG. 5A, at the time t ₄ , the flow rate adjustment valve 40 is switched from the open state to the fully closed state, and at the same time the open / close valve 42 The previous closed state is switched to the open state. Next, the exhaust valve 36 is closed, for example, at time t ₅ after several seconds. At this time, the gate valve GV _R of the loader module LM side is closed. In this way, the pressure in the load lock chamber 22 is returned to the atmospheric pressure from the set pressure value as shown in FIG. Then, the gate valve GV _R is opened at time t ₆ after became atmospheric pressure. In the load lock chamber 22, the lift pins 66 rise to lift the semiconductor wafer W onto the wafer mounting table S for carrying out the wafer.

In a state where the gate valve GV _R is opened, the atmospheric transfer robot 32 of the loader module LM takes out the processed semiconductor wafer W from the load lock chamber 22 to the wafer transfer chamber 30, then either the wafer cassette CR of the load port LP Store in.

FIG. 5B shows another embodiment of the pressure control sequence related to the load lock chamber 20 (22). According to this embodiment, the processed semiconductor wafer W during removal from the load lock chamber 22 to the wafer transfer chamber 30 side, the period just before opening the gate valve GV _R of the loader module LM side (time t ₅ ~ At t ₆ ), the opening / closing valve 42 is opened and the purge gas is supplied into the room. At this time, the exhaust valve 36 is switched from the open state to the closed state immediately before (time t ₄ ). Thus, the pressure in the chamber by the purge gas supply without evacuation After returning to atmospheric pressure or more positive pressure, opening the gate valve GV _R (time t _6).

  In this vacuum processing system, the bottom portion 20a (22a) of the load lock chamber 20 (22) is provided with a seal portion 74. The seal portion 74 is used from a seal member such as an O-ring or the like, or used for the seal portion 74. There is a possibility that organic substances generated from the grease etc. diffuse or float in the room. Further, in the transfer chamber 10, there is a vacuum transfer robot 28 that is a drive mechanism, and organic matter generated from grease or the like may also diffuse or float from here. If no special measures are taken, there is a possibility of organic contamination in the load lock chamber 20 (22) and the transfer chamber 10 where organic substances adhere to the semiconductor wafer W. As described above, the load lock chamber 20 (22) Since there is a smaller space, the probability of organic contamination is high. This is very prominent because when the process time in the cluster tool is increased, the time during which the semiconductor wafer W is retained in the load lock chamber is also increased.

  In this embodiment, as described above, in both the load lock chamber 20 (22) and the transfer chamber 10, the pressure in the chamber is within a pressure range of several tens to several hundreds Pa that is effective for preventing or reducing organic contamination. The pressure in the load lock chamber 20 (22) is set higher than the pressure in the transfer chamber 10 (preferably in the range of 1 to 2 times). Here, it has been confirmed that several tens to several hundreds Pa is a pressure that moderately reduces the mean free path of organic molecules.

According to this embodiment, a series of process processes for forming a barrier metal such as titanium (Ti) or titanium nitride (TiN), tungsten (W) or tungsten silicide (WSi) in a multilayer structure on a 300 mmφ semiconductor wafer. In this case, the adhesion of organic matter on the wafer can be significantly reduced as compared with the conventional case. In addition, even in a film forming process in which a high dielectric constant insulating film (High-k film) such as a tantalum oxide (Ta ₂ O ₅ ) film is formed in multiple layers, the effect of reducing such organic contamination is also confirmed. Has been.

  Further, in the load lock chamber 20 (22) of this embodiment, a plurality of openings 82 are formed on the side wall of the cylindrical base 78 that supports the wafer mounting table S at predetermined intervals in the circumferential direction. The organic matter generated from the portion 74 does not go out onto the wafer mounting table S through the gap between the pin holes 64, but flows out from the opening 82 to the side of the cylindrical base 78 together with the purge gas and quickly flows to the exhaust port 84. It is like that. As a result, it is possible to more effectively prevent or reduce organic substances from adhering to the semiconductor wafer W in the load lock chamber 20 (22).

  FIG. 7 shows a modification of the mechanism for controlling the pressure in the load lock chamber 20 (22). In this configuration example, an automatic pressure control device (APC) 90 is provided on the exhaust system side in order to control the pressure in the load lock chamber 20 (22) to a set pressure. This automatic pressure control device (APC) 90 is provided with a variable exhaust valve 92 in the middle of the exhaust pipe 85 so that the pressure in the load lock chamber 20 (22) measured by the vacuum gauge 46 matches the set value. In addition, the controller 94 controls the variable valve 92. The purge gas supply unit 44 side may be configured to supply the purge gas at a constant flow rate.

  FIG. 8 shows a more preferable apparatus configuration for removing organic substances generated in the load lock chamber 20 (22). As shown in the figure, an exhaust port 84 is provided inside a cylindrical base 78 that supports the wafer mounting table S. Furthermore, in addition to the holes 64 through which the lift pins 66 pass, the wafer mounting table S is also provided with a plurality of holes 96 for barge gas distribution discretely. According to this configuration, the organic matter generated from the bearing 74 can be quickly sent to the exhaust port 84 and discharged to the outside without being taken out of the cylindrical base 78 on the barge gas flow 98.

The load lock modules LLM ₁ and LLM ₂ in the above-described embodiment are of the single wafer type in which the semiconductor wafer W is temporarily held in units of one. As shown in FIG. 9, these load lock modules LLM ₁ and LLM ₂ can be configured as a batch type in which semiconductor wafers W are temporarily held in units of a plurality of sheets. In FIG. 9, for convenience of explanation, the same reference numerals are given to parts having the same configuration or function as those of the single-wafer type.

  In FIG. 9, in the load lock chamber 20 (22), a cassette support base 102 for placing and supporting a cassette 100 capable of accommodating up to a predetermined number of wafers W, for example, 25, is disposed so as to be movable up and down. . The cassette support 102 is connected to an elevating drive unit 72 installed in the atmosphere below the load lock chamber 20 (22) via an elevating drive shaft 70. The elevating drive shaft 70 is airtightly introduced into the chamber by a seal portion 74 attached to the bottom portion 20a (22a) of the load lock chamber 20 (22). The raising / lowering drive part 72 is equipped with the motor, for example, and moves the cassette support stand 102 and the cassette 100 on the stand up / down within a fixed raising / lowering movement range via the raising / lowering drive shaft 70.

  A partition horizontal plate 110 is provided between the lower limit position of the lifting movement range and the bottom 20a (22a) of the load lock chamber 20 (22). Yes. In addition to the opening 108, the partition plate 110 may be formed with a plurality of openings (not shown) having a small diameter for flowing the purge gas.

  An exhaust port 84 is provided near the seal portion 74 at the bottom 20a (22a) of the load lock chamber 20 (22). The exhaust port 84 communicates with the exhaust mechanism 38 via an exhaust pipe 85, and the exhaust valve 36 is provided in the middle of the exhaust pipe 85. A purge gas supply pipe 86 is drawn from the upper surface of the load lock chamber 20 (22), and a purge gas nozzle 88 is disposed at a height position near the ceiling. The purge gas supply system has the same configuration as in FIG. The structure and operation of the mechanism for controlling the pressure or atmosphere in the load lock chamber 20 (22) are the same as those in FIG. That is, while the cassette 100 stays in the load lock chamber 20 (22), the exhaust mechanism 38 exhausts the chamber with a constant exhaust amount, and the controller 48, the vacuum gauge 46, and the flow rate adjustment valve 40 include the purge gas supply unit. The flow rate of the purge gas supplied from 44 is controlled, and the pressure in the load lock chamber 20 (22) is maintained at a set value. Here, the set pressure in the load lock chamber 20 (22) is selected within a pressure range of several tens of Pa to several hundred Pa effective for preventing or reducing organic contamination, and the transfer chamber of the adjacent transfer module TM is also used. 10 (FIG. 2) higher than the pressure, preferably within a range of 1 to 2 times the pressure.

  Further, in the batch type load lock chamber 20 (22), the organic matter generated from the seal portion 74 is quickly discharged together with the purge gas from the exhaust port 84 to the outside without entering the space above the partition plate 110. It is like that.

  The configuration shown in FIG. 10 uses an automatic pressure control device (APC) 90 similar to that in FIG. 7 as a mechanism for controlling the pressure or atmosphere in the batch type load lock chamber 20 (22). is there.

  The batch-type load lock module takes in and out one lot of semiconductor wafers W in units of 100 cassettes. Therefore, it takes a long time to hold each semiconductor wafer W in the load lock chamber 20 (22), for example, 1 to 2 hours. In addition, the effects of the organic matter prevention according to the present invention can be enjoyed more remarkably.

The vacuum processing system of the cluster tool in the above embodiment is not limited to that shown in FIG. 1, and various modifications can be made in the layout, the configuration of each part, and the like. For example, as shown in FIG. 11, a configuration in which two transfer modules TM ₁ and TM ₂ are connected in series via a path unit 112 in one cluster tool is also possible. In the illustrated layout, up to six process modules PM can be installed. On both sides of the pass unit 112, submodules SM ₁ and SM ₂ for preprocessing the process are also arranged.

Even in a vacuum processing system with a large number of transfer modules TM and process modules PM as shown in FIG. 11, the processing time applied to one semiconductor wafer increases as in the vacuum processing system as shown in FIG. In this case, the waiting time of the semiconductor wafer W reaches several minutes to several tens of minutes in the load lock chambers 20 and 22 of the load lock modules LLM ₁ and LLM _2. Contamination can be greatly suppressed. As a result, it is possible to improve the manufacturing yield of semiconductor devices that are miniaturized and have higher performance.

  Although the preferred embodiments of the present invention have been described above, the above-described embodiments do not limit the present invention. Those skilled in the art can make various modifications and changes in specific embodiments without departing from the technical idea and technical scope of the present invention.

  For example, the present invention can be applied not only to the vacuum processing system of the cluster tool described above but also to a vacuum processing system in which organic contamination is a concern and a relatively high pressure vacuum state is acceptable. It is also possible to adopt a configuration in which an exhaust pump for low vacuum is attached to the transfer chamber and no purge gas supply means is provided. The object to be processed is not limited to a semiconductor wafer, and may be another object to be processed such as an LCD substrate that is likely to be contaminated with organic matter.

1 is a schematic plan view showing a configuration of a vacuum processing system for a cluster tool in one embodiment. It is a schematic longitudinal cross-sectional view which shows roughly the principal part of the said vacuum processing system. It is a cross-sectional view showing a main configuration of a single-wafer type load lock module in the embodiment. It is a longitudinal cross-sectional view which shows the main structures of the said load lock module. It is a timing chart which shows one Example of the operation | movement of the vacuum exhaustion in the said load lock module. It is a timing chart which shows another Example of the operation | movement of the evacuation in the said load lock module. It is a graph which shows the time change of the pressure in the load lock room of the above-mentioned load lock module. It is a longitudinal cross-sectional view which shows the modification of the single wafer type load lock module in embodiment. It is a partial expanded longitudinal cross-sectional view which shows another modification of the single-wafer | sheet-fed loadlock module in embodiment. It is a longitudinal cross-sectional view which shows the main structures of the batch type load lock module in embodiment. It is a longitudinal cross-sectional view which shows the modification of the batch type load lock module in embodiment. It is a schematic plan view showing a modification of the cluster tool in the embodiment.

Explanation of symbols

10 Transfer chamber 12, 14, 16, 18 Processing chamber (process chamber)
20, 22 Load lock chamber 24, 26 Transfer arm 28 Vacuum transfer robot 30 Wafer transfer chamber 32 Atmospheric transfer robot 36, 50 Exhaust valve 38, 52 Exhaust mechanism 40, 54 Flow rate adjustment valve 42, 56 Open / close valve 44, 58 Purge gas supply unit 46, 60 Vacuum gauge 48, 62 Controller 64 Pin hole 66 Lift pin 68 Horizontal support plate 70 Lifting drive shaft 72 Lifting drive part 74 Sealing part 84 Exhaust port 86 Purge gas supply pipe 88 Purge gas nozzle 90 Automatic pressure control device 110 Partition member TM, TM _1, TM ₂ transfer module LLM _1, LLM ₂ load-lock modules _{PM 1, PM 2, PM 3} , PM 4, PM 5, PM 6 process module GV _T gate valve GV _R gate valves LM loader module LP low DOPORT ORT Orientation flat alignment mechanism

Claims (7)

A transfer chamber provided with a transfer mechanism in which the interior of the chamber is maintained in a reduced pressure state and the object to be processed is transferred between the chamber and the adjacent chamber;
A vacuum processing chamber provided adjacent to the transfer chamber, in which a predetermined process is performed on a target object in a chamber under reduced pressure;
A load lock chamber provided adjacent to the transfer chamber, wherein the chamber is selectively switched to an atmospheric state or a reduced pressure state, and temporarily holds an object to be processed transferred between the atmospheric space and the transfer chamber; ,
A first exhaust part for evacuating the load lock chamber;
A first purge gas supply unit for supplying purge gas into the load lock chamber;
A control unit for controlling at least one of an exhaust operation of the first exhaust unit and a purge gas supply operation of the first purge gas supply unit to control the pressure in the load lock chamber;
In the load lock chamber,
A mounting table having a plurality of through holes for mounting the object to be processed in units of one sheet;
A cylindrical base for supporting the mounting table;
A lift pin mechanism having a plurality of lift pins configured to be movable up and down through the plurality of through holes of the mounting table inside the cylindrical base;
An elevating drive shaft that connects the lift pin mechanism inside the cylindrical base and an elevating drive unit provided in an atmospheric space under the load lock chamber;
A seal member provided at the bottom of the load lock chamber in order to maintain a vacuum tightness in the room with respect to the lift drive shaft;
A gas introduction hole provided at a position higher than the mounting table for introducing the purge gas from the first purge gas supply unit into the room, and a lower than the mounting table for sending the room gas to the first exhaust unit. And an exhaust port provided at a position close to the seal member,
The exhaust port is provided outside the cylindrical base, and a plurality of openings are formed at predetermined intervals in a circumferential direction on a side wall of the cylindrical base.
Vacuum processing system. A transfer chamber provided with a transfer mechanism for transferring the object to be processed between the room and the adjacent chamber;
A vacuum processing chamber provided adjacent to the transfer chamber, in which a predetermined process is performed on a target object in a chamber under reduced pressure;
A load lock chamber provided adjacent to the transfer chamber, wherein the chamber is selectively switched to an atmospheric state or a reduced pressure state, and temporarily holds an object to be processed transferred between the atmospheric space and the transfer chamber; ,
A first exhaust part for evacuating the load lock chamber;
A first purge gas supply unit for supplying purge gas into the load lock chamber;
A first controller that controls at least one of an exhaust operation of the first exhaust unit and a purge gas supply operation of the first purge gas supply unit to control the pressure in the load lock chamber;
A second exhaust part for evacuating the transfer chamber under reduced pressure;
A second purge gas supply unit for supplying purge gas into the transfer chamber;
A second control unit for controlling at least one of an exhaust operation of the second exhaust unit and a purge gas supply operation of the second purge gas supply unit in order to control the pressure in the transfer chamber;
In the load lock chamber,
A mounting table having a plurality of through holes for mounting the object to be processed in units of one sheet;
A cylindrical base for supporting the mounting table;
A lift pin mechanism having a plurality of lift pins configured to be movable up and down through the plurality of through holes of the mounting table inside the cylindrical base;
An elevating drive shaft that connects the lift pin mechanism inside the cylindrical base and an elevating drive unit provided in an atmospheric space under the load lock chamber;
A seal member provided at the bottom of the load lock chamber in order to maintain a vacuum tightness in the room with respect to the lift drive shaft;
A gas introduction hole provided at a position higher than the mounting table for introducing the purge gas from the first purge gas supply unit into the room, and a lower than the mounting table for sending the room gas to the first exhaust unit. And an exhaust port provided at a position close to the seal member,
The exhaust port is provided outside the cylindrical base, and a plurality of openings are formed at predetermined intervals in a circumferential direction on a side wall of the cylindrical base.
Vacuum processing system.   The vacuum processing system according to claim 1, wherein the pressure in the load lock chamber is higher than the pressure in the transfer chamber.   The vacuum processing system according to claim 1, wherein the pressure in the load lock chamber is controlled to several tens to several hundreds Pa.   The vacuum processing system according to claim 1, wherein the pressure in the transfer chamber is controlled to several tens to several hundreds Pa.   The vacuum processing system according to claim 1, wherein the mounting table includes a cooling plate having high thermal conductivity.   The vacuum processing system according to claim 1, wherein a part of the purge gas introduced from the gas introduction hole in the load lock chamber flows through the vicinity of the seal member to the exhaust port.

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