JP4516318B2 - Substrate processing apparatus and semiconductor device manufacturing method - Google Patents

Description

  The present invention relates to a substrate processing apparatus, and is used, for example, in a heat treatment apparatus (furnace) such as a CVD apparatus, a diffusion apparatus, an oxidation apparatus, and an annealing apparatus used in a method for manufacturing a semiconductor integrated circuit device (hereinafter referred to as an IC). Related to effective.

In an IC manufacturing method, a CVD film such as silicon nitride (Si ₃ N ₄ ), silicon oxide, or polysilicon is formed on a semiconductor wafer (hereinafter referred to as a wafer) in which an integrated circuit including a semiconductor element is formed. A batch type vertical hot wall type low pressure CVD apparatus is widely used. A batch type vertical hot wall type low pressure CVD apparatus (hereinafter referred to as a CVD apparatus) is composed of an inner tube into which a wafer is loaded and an outer tube surrounding the inner tube, and a process tube installed in a vertical shape and a process tube. A gas supply pipe for supplying a film forming gas as a processing gas to the processed chamber, an exhaust pipe for evacuating the processing chamber, a heater unit installed outside the process tube to heat the processing chamber, and a boat elevator A seal cap that opens and closes the furnace port of the processing chamber, and a boat that is vertically installed on the seal cap and holds a plurality of wafers. The plurality of wafers are vertically aligned by the boat. In this state, the processing chamber is loaded from the bottom furnace port (boat loading) and sealed. With the furnace port closed by the cap, the film forming gas is supplied to the processing chamber from the gas supply pipe, and the processing chamber is heated by the heater unit so that the CVD film is deposited on the wafer. (For example, refer patent document 1).
JP 2002-110556 A

  In general, in a CVD apparatus, a process chamber is purged with nitrogen gas after film formation and the temperature is lowered to a predetermined temperature, and then the boat is unloaded from the process chamber (boat unloading). This is to prevent the boat from being unloaded while the processing temperature is maintained, so that the temperature deviation between the wafers and the temperature deviation within the wafer surface become large and adversely affect the IC characteristics. Nitrogen gas is supplied to the processing chamber through a gas supply pipe fixed to the manifold.

  However, since nitrogen gas is supplied to the processing chamber by a gas supply pipe fixed to the manifold, there is a problem that the temperature drop of the wafer group becomes non-uniform. That is, since the gas supply pipe is disposed at one position below the boat in the processing chamber, it cannot contact the wafer group with a uniform flow. That is, since the flow of nitrogen gas becomes non-uniform, the wafer group is cooled non-uniformly in the region of the wafer group and the wafer surface, and only the wafer and wafer surface in the region where the flow rate of nitrogen gas is high are cooled.

  An object of the present invention is to provide a substrate processing apparatus capable of improving a temperature drop rate and preventing temperature deviation between substrates and in a substrate surface.

A substrate processing apparatus according to the present invention includes a processing chamber for holding a substrate on a substrate holder for processing, a heater unit installed around the processing chamber for heating the substrate, and a gas for supplying a processing gas to the processing chamber. A supply pipe, an exhaust pipe for exhausting the processing chamber, an elevator for raising and lowering a seal cap holding the substrate holder, a cooling gas nozzle for raising and lowering together with the seal cap and injecting a cooling gas to the substrate, and the cooling gas nozzle And a gas flow rate control unit that controls injection when the gas descends.
Among the other inventions disclosed in the present application, representative ones are as follows.
(1) A temperature sensor that detects the temperature of the substrate that is raised and lowered by the elevator is installed in the vicinity of the substrate holder, and the gas flow rate control unit controls the gas flow rate based on the temperature detected by the temperature sensor. A substrate processing apparatus configured to be controlled.
(2) A plurality of the cooling gas nozzles having different lengths in a direction perpendicular to the main surface of the substrate are provided, and these cooling gas nozzles include the gas flow rate control unit. The substrate processing apparatus according to (1).
(3) A processing chamber for processing a substrate held on a substrate holder, a heater unit installed around the processing chamber for heating the substrate, a gas supply pipe for supplying a processing gas to the processing chamber, and the processing An exhaust pipe for exhausting the chamber, an elevator for raising and lowering a seal cap holding the substrate holder, a cooling gas nozzle for raising and lowering together with the seal cap and injecting a cooling gas to the substrate, and an injection when the cooling gas nozzle descends In a manufacturing method of a semiconductor device for processing a substrate using a substrate processing apparatus provided with a gas flow rate control unit for controlling
The processed substrate holder is lowered by the elevator, the gas flow rate controller jets cooling gas from the cooling gas nozzle, the cooling gas nozzle reaches the substrate, and the cooling gas And a step of cooling the substrate.

  According to the above-described means, the temperature of the processed substrate can be rapidly and uniformly lowered by injecting the cooling gas from the cooling gas nozzle.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  In this embodiment, as shown in FIG. 1, FIG. 2 and FIG. 3, the substrate processing apparatus according to the present invention is a CVD apparatus (batch type vertical hot wall type) for performing a film forming process in an IC manufacturing method. (Low pressure CVD apparatus) 10. In this CVD apparatus, a FOUP (front opening unified pod, hereinafter referred to as a pod) 2 is used as a wafer carrier for transporting the wafer 1.

  As shown in FIG. 1 to FIG. 3, the CVD apparatus 10 includes a housing 11 constructed in a rectangular parallelepiped box shape by using a steel plate or a steel plate. A pod loading / unloading port 12 is opened on the front wall of the housing 11 so as to communicate with the inside and outside of the housing 11, and the pod loading / unloading port 12 is opened and closed by a front shutter 13. A pod stage 14 is installed in front of the pod loading / unloading port 12, and the pod stage 14 is configured to place the pod 2 and perform alignment. The pod 2 is loaded onto the pod stage 14 by an in-process transfer device (not shown) and is also unloaded from the pod stage 14.

  A rotary pod shelf 15 is installed in an upper portion of the housing 11 at a substantially central portion in the front-rear direction, and the rotary pod shelf 15 is configured to store a plurality of pods 2. That is, the rotary pod shelf 15 includes a support column 16 that is vertically set up and intermittently rotated in a horizontal plane, and a plurality of shelf plates 17 that are radially supported by the support column 16 at each of the upper, middle, and lower levels. The plurality of shelf boards 17 are configured to hold the pod 2 in a state where a plurality of the pods 2 are respectively placed. A pod transfer device 18 is installed between the pod stage 14 and the rotary pod shelf 15 in the housing 11, and the pod transfer device 18 is provided between the pod stage 14 and the rotary pod shelf 15 and the rotary pod. The pod 2 is transported between the shelf 15 and the pod opener 21.

  A sub-housing 19 is constructed across the rear end of the lower portion of the housing 11 at a substantially central portion in the front-rear direction. A pair of wafer loading / unloading ports 20 for loading / unloading the wafer 1 into / from the sub-casing 19 are arranged on the front wall of the sub-casing 19 in two vertical rows. A pair of pod openers 21 and 21 are respectively installed at the wafer loading / unloading ports 20 and 20. The pod opener 21 includes a mounting table 22 for mounting the pod 2, and a cap attaching / detaching mechanism 23 for mounting and removing the cap of the pod 2 mounted on the mounting table 22, and the pod 2 mounted on the mounting table 22. This cap is configured to be opened / closed by the cap attaching / detaching mechanism 23 to open / close the wafer inlet / outlet of the pod 2. The pod 2 is carried into and out of the mounting table 22 of the pod opener 21 by the pod transfer device 18.

  A transfer chamber 24 in which a wafer transfer device 25 is installed is formed in the front region within the sub-housing 19. The wafer transfer device 25 is configured to load (charge) and unload (discharge) the wafer 1 with respect to the boat 30. A standby chamber 26 is formed at the rear end of the sub-housing 19 to accommodate and wait for the boat. A boat elevator 27 for raising and lowering the boat is installed in the waiting room 26. The boat elevator 27 is configured by a motor-driven feed screw shaft device, a bellows, or the like. A seal cap 29 is horizontally installed on the arm 28 connected to the elevator platform of the boat elevator 27, and the seal cap 29 is configured to support the boat 30 vertically. The boat 30 includes a plurality of holding members, and is configured to hold a plurality of (for example, about fifty to fifty to fifty) wafers 1 with their centers aligned and horizontally supported. Has been.

As shown in FIG. 3, the CVD apparatus 10 includes a vertical process tube 31 that is vertically arranged and supported so that the center line is vertical, and the process tubes 31 are arranged concentrically with each other. The outer tube 32 and the inner tube 33 are comprised. The outer tube 32 is made of quartz (SiO ₂ ), which is an example of a material that transmits heat rays (infrared rays, far-infrared rays, etc.) of a heating lamp, which will be described later, and is integrally formed into a cylindrical shape with the upper end closed and the lower end opened. Yes. The inner tube 33 is formed in a cylindrical shape whose upper and lower ends are open, and the cylindrical hollow portion of the inner tube 33 substantially includes a processing chamber 34 into which a plurality of wafers held in a long alignment state by the boat 30 are loaded. Is formed. The lower end opening of the inner tube 33 substantially constitutes a furnace port 35 for taking in and out the wafer, and the inner diameter of the inner tube 33 is set to be larger than the maximum outer diameter (for example, diameter of 300 mm) of the wafer to be handled. Has been.

  A lower end portion between the outer tube 32 and the inner tube 33 is hermetically sealed by a manifold 36 constructed in a substantially cylindrical shape. The manifold 36 is used for the replacement of the outer tube 32 and the inner tube 33 and the like. Removably attached to the tube 32 and the inner tube 33, respectively. Since the manifold 36 is supported by the sub casing 19, the process tube 31 is installed vertically.

  The exhaust passage 37 is formed by a gap between the outer tube 32 and the inner tube 33 in a circular ring shape having a constant cross-sectional shape. One end of an exhaust pipe 38 is connected to the upper portion of the side wall of the manifold 36, and the exhaust pipe 38 communicates with the lowermost end portion of the exhaust path 37. An exhaust device 39 controlled by a pressure controller 41 is connected to the other end of the exhaust pipe 38, and a pressure sensor 40 is connected to the exhaust pipe 38. The pressure controller 41 is configured to feedback control the exhaust device 39 based on the measurement result from the pressure sensor 40.

  A gas supply pipe 42 is connected to the lower portion of the manifold 36 so as to communicate with the furnace port 35 of the inner tube 33. The gas supply pipe 42 is connected to a raw material gas supply device controlled by a gas flow rate controller 44 and an inert gas. A supply device (hereinafter referred to as a gas supply device) 43 is connected. The gas introduced into the furnace port 35 by the gas supply pipe 42 flows through the processing chamber 34 of the inner tube 33, passes through the exhaust passage 37, and is exhausted by the exhaust pipe 38.

  A seal cap 29 constructed in a disc shape substantially equal to the outer diameter of the manifold 36 is in contact with the lower end of the manifold 36 from the lower side in the vertical direction and is closed. A rotation shaft 45 is inserted on the center line of the seal cap 29 and is rotatably supported. The rotation shaft 45 is configured to be rotationally driven by a motor 47 controlled by a drive controller 46. Incidentally, the drive controller 46 is also configured to control the motor 27 a of the boat elevator 27. The boat 30 is vertically supported and supported at the upper end of the rotating shaft 45. A heat insulating cap portion 48 is disposed between the seal cap 29 and the boat 30. That is, the boat 30 is supported by the rotating shaft 45 in a state where the lower end of the boat 30 is lifted from the upper surface of the seal cap 29 so as to be separated from the position of the furnace port 35 by an appropriate distance. The cap part which fills the space | interval between the lower end of this and the seal cap 29 is comprised.

A heater unit 50 is installed outside the process tube 31. The heater unit 50 includes a heat insulating tank 51 having a small heat capacity that covers the entire process tube 31, and the heat insulating tank 51 is vertically supported by the sub-housing 19. Inside the heat insulating tank 51, a plurality of L-tube halogen lamps (hereinafter referred to as heating lamps) 52 as heating means are arranged concentrically and arranged at equal intervals in the circumferential direction. The heating lamps 52 are arranged in a combination of a plurality of standards having different lengths, and are configured to increase the amount of heat generated at the upper and lower portions of the process tube 31 where heat can easily escape. The terminals 52a of the heating lamps 52 are respectively disposed at the upper and lower portions of the process tube 31, and a decrease in the amount of heat generated due to the interposition of the terminals 52a is avoided. The heating lamp 52 is formed by covering a filament such as carbon or tungsten with an L tube made of quartz (SiO ₂ ) and sealing it in an inert gas or vacuum atmosphere. The heating lamp 52 is configured to irradiate heat rays having a peak wavelength of thermal energy of about 1.0 μm to 2.0 μm so that the wafer 1 can be heated by radiation without almost heating the outer tube 32. Is set.

As shown in FIGS. 3 and 4, a plurality of L-tube halogen lamps (hereinafter referred to as ceiling heating lamps) 53 are parallel to each other at the center of the heat insulating tank 51 below the ceiling surface. The ceiling heating lamps 53 are configured to heat the group of wafers held on the boat 30 from above the process tube 31. The ceiling heating lamp 53 is configured by covering a filament such as carbon or tungsten with an L tube made of quartz (SiO ₂ ) and sealing it in an inert gas or vacuum atmosphere. The ceiling heating lamp 53 is configured to irradiate heat rays having a peak wavelength of thermal energy of about 1.0 μm to 2.0 μm, and can heat the wafer 1 by radiation without almost heating the outer tube 32. It is set to be possible. Similarly, a cap heating lamp 53 </ b> A group is configured between the boat 30 and the heat insulating cap part 48 so as to heat from the lower side of the wafer group 1 and the process tube 31.

  As shown in FIG. 3, the heating lamp 52 group, the ceiling heating lamp 53 group, and the cap heating lamp 53A group are connected to a heating lamp driving device 54, and the heating lamp driving device 54 is controlled by a temperature controller 55. It is comprised so that. A cascade thermocouple 56 is laid in the vertical direction inside the inner tube 33, and the cascade thermocouple 56 transmits a measurement result to the temperature controller 55. The temperature controller 55 performs feedback control of the heating lamp driving device 54 based on the measured temperature from the cascade thermocouple 56. That is, the temperature controller 55 obtains an error between the target temperature of the heating lamp driving device 54 and the measured temperature of the cascade thermocouple 56, and executes feedback control for eliminating the error if there is an error. The temperature controller 55 is configured to perform zone control on the heating lamps 52 group.

As shown in FIGS. 3 and 4, a reflector (reflector) 57 formed in a cylindrical shape is installed outside the group of heating lamps 52 in a concentric circle with the process tube 31, and the reflector 57 is a heating lamp. The heat rays from the 52 group are all reflected in the direction of the process tube 31. The reflector 57 is made of a material excellent in oxidation resistance, heat resistance and thermal shock resistance, such as a material formed by coating a stainless steel plate with quartz (SiO ₂ ). A cooling water pipe 58 is spirally laid on the outer peripheral surface of the reflector 57 so that the cooling water pipe 58 cools the reflector 57 to 300 ° C. or less, which is the heat resistant temperature of the quartz (SiO ₂ ) coating on the reflector surface. Is set. When the reflector 57 exceeds 300 ° C., it easily deteriorates due to oxidation or the like. However, by cooling the reflector 57 to 300 ° C. or less, the durability of the reflector 57 can be improved and the particles accompanying the deterioration of the reflector 57 can be improved. Can be suppressed. Further, when the temperature inside the heat insulating tank 51 is lowered, the cooling effect can be improved by cooling the reflector 57. Further, the cooling water pipe 58 is configured to be able to control the cooling area of the reflector 57 by dividing it into upper, middle and lower zones. By controlling the zone of the cooling water pipe 58, when the temperature of the process tube 31 is lowered, cooling can be performed corresponding to the zone of the process tube 31. For example, the zone in which the wafer group is placed has a heat capacity that is increased by the amount of the wafer group, so that it is difficult to cool compared to the zone in which the wafer group is not placed. It is possible to control the zone so as to cool it preferentially.

  As shown in FIGS. 3 and 4, a ceiling reflector 59 formed in a disk shape is installed on the ceiling surface of the heat insulating tank 51 concentrically with the process tube 31, and the ceiling reflector 59 is a ceiling heating lamp. The heat rays from the 53 group are all reflected in the direction of the process tube 31. The ceiling reflector 59 is also made of a material excellent in oxidation resistance, heat resistance and thermal shock resistance. A cooling water pipe 60 is laid in a serpentine shape on the upper surface of the ceiling reflector 59, and the cooling water pipe 60 is set to cool the ceiling reflector 59 to 300 ° C. or lower. When the ceiling reflector 59 exceeds 300 ° C., it tends to deteriorate due to oxidation or the like. However, by cooling the ceiling reflector 59 to 300 ° C. or less, the durability of the ceiling reflector 59 can be improved, and the ceiling reflector 59 Generation of particles due to deterioration can be suppressed. Further, when the temperature inside the heat insulating tank 51 is lowered, the cooling effect can be improved by cooling the ceiling reflector 59.

  As shown in FIGS. 3 and 4, a cooling air passage 61 through which cooling air as a cooling gas flows between the heat insulating tank 51 and the process tube 31 surrounds the process tube 31 as a whole. Is formed. An air supply pipe 62 for supplying cooling air to the cooling air passage 61 is connected to the lower end portion of the heat insulating tank 51, and the cooling air supplied to the air supply pipe 62 diffuses over the entire circumference of the cooling air passage 61. ing. An exhaust port 63 for discharging cooling air from the cooling air passage 61 is opened at the center of the ceiling wall of the heat insulating tank 51, and an exhaust path (not shown) connected to the exhaust device is connected to the exhaust port 63. Has been. A buffer portion 64 that communicates with the exhaust port 63 is formed below the exhaust port 63 on the ceiling wall of the heat insulating tank 51, and a plurality of sub exhaust ports 65 are provided at the periphery of the bottom surface of the buffer unit 64. 64 and the cooling air passage 61 are opened. These sub exhaust ports 65 allow the cooling air passage 61 to be efficiently exhausted. Further, by arranging the sub exhaust port 65 in the peripheral part of the ceiling wall of the heat insulating tank 51, the ceiling heating lamp 53 can be laid at the center of the ceiling surface of the heat insulating tank 51, and the ceiling heating lamp 53 is exhausted. The ceiling heating lamp 53 can be prevented from deteriorating by retreating from the flow path to prevent stress and chemical reaction due to the exhaust flow.

  As shown in FIG. 5, a long nozzle 66 and a short nozzle 67 are vertically erected on the periphery of the seal cap 29 on the same radius and spaced in the circumferential direction. The short nozzle 67 is configured as a cooling gas nozzle that injects nitrogen gas as a cooling gas. The long nozzle 66 and the short nozzle 67 are provided with a plurality of injection ports 66 a and 67 a so as to inject nitrogen gas toward the center of the boat 30 in the radial direction. The opening shape of each of the injection ports 66a and 67a (a perfect circle or a long length) is set so that the flow rate of nitrogen gas injected from each of the injection ports 66a and 67a is as uniform as possible over the entire length of the long nozzle 66 and the short nozzle 67. Round, etc.), aperture, opening area, etc. are set. In order to set the jet flow from the jet nozzles aligned in the longitudinal direction to an equal flow rate over the entire length of the nozzle, it is common to gradually increase the size of each jet nozzle as it goes downstream. However, in order to uniformly cool the group of wafers aligned on the boat 30 over the entire length, it is necessary to increase the flow velocity from each injection port and to control it uniformly. For this purpose, it is desirable to adjust the internal conductance by setting the sizes of the injection ports 66a and 67a to be the same, and gradually setting the inner diameters (flow channel cross-sectional areas) of the long nozzle 66 and the short nozzle 67. . In addition, it is desirable to prevent pressure loss due to channel resistance by setting the inner diameters (channel cross-sectional areas) of the long nozzle 66 and the short nozzle 67 sufficiently large over the entire length.

  As shown in FIG. 5, a nitrogen gas supply device 68 is connected to the long nozzle 66 and the short nozzle 67, and the nitrogen gas supply device 68 is configured to be controlled by a flow rate controller 69. . The cooling capacity by the long nozzle 66 and the short nozzle 67 can be adjusted by controlling the injection amount of the nitrogen gas by the nitrogen gas supply device 68. In addition, by independently controlling the flow rate of the long nozzle 66 and the flow rate of the short nozzle 67, the cooling capacity of the long nozzle 66 and the short nozzle 67 can be zone-controlled. Between the long nozzle 66 and the short nozzle 67, a thermocouple 70 that moves together with the boat 30 is erected in the vertical direction, and the thermocouple 70 transmits a measurement result to the flow rate adjustment controller 69. The flow rate adjustment controller 69 performs feedback control of the nitrogen gas supply device 68 by PID control or the like based on the measured temperature from the thermocouple 70. That is, the flow rate adjustment controller 69 obtains an error between a preset target temperature and the measured temperature of the thermocouple 70, and if there is an error, the long nozzle 66 and Feedback control for increasing or decreasing the supply flow rate of nitrogen gas to the short nozzle 67 is executed. For example, if the gas flow rate does not reach the maximum flow rate, a method of simply lowering the set temperature can provide a sufficient effect, but if a control pattern is set so that the temperature in the lowest region is set to the set temperature, it becomes even more uniform. Can be cooled quickly.

  A film forming process in the IC manufacturing method by the CVD apparatus having the above-described configuration will be described.

  As shown in FIGS. 1 and 2, when the pod 2 is supplied to the pod stage 14, the pod loading / unloading port 12 is opened by the front shutter 13, and the pod 2 above the pod stage 14 is connected to the pod transfer device. 18 is carried into the housing 11 from the pod loading / unloading port 12. The loaded pod 2 is automatically transferred to the designated shelf plate 17 of the rotary pod shelf 15 by the pod transfer device 18 and delivered, and temporarily stored on the shelf plate 17. The stored pod 2 is transferred to one pod opener 21 by the pod transfer device 18 and transferred to the mounting table 22. At this time, the wafer loading / unloading port 20 of the pod opener 21 is closed by the cap attaching / detaching mechanism 23, and the transfer chamber 24 is filled with nitrogen gas. That is, the oxygen concentration in the transfer chamber 24 is set to 20 ppm or less, which is much lower than the oxygen concentration inside the housing 11 (atmosphere).

  The pod 2 mounted on the mounting table 42 has its opening-side end face pressed against the opening edge of the wafer loading / unloading port 20 on the front surface of the sub-casing 19 and the cap is removed by the cap attaching / detaching mechanism 23 to remove the wafer. Mouth open. The plurality of wafers 1 stored in the pod 2 are picked up by the wafer transfer device 25, loaded into the standby chamber 26 through the transfer chamber 24 from the wafer loading / unloading port 20, and loaded into the boat 30 (charging). . The wafer transfer device 25 that has transferred the wafer 1 to the boat 30 returns to the pod 2 and loads the next wafer 1 into the boat 30. Thereafter, by repeating the operation of the wafer transfer device 25, all the wafers 1 of the pod 2 on the mounting table 22 of one pod opener 21 are sequentially loaded into the boat 30.

  During the loading operation of the wafer into the boat 30 by the wafer transfer device 25 in the one (upper or lower) pod opener 21, the other (lower or upper) pod opener 21 receives another pod from the rotary pod shelf 15. 2 is transferred and transferred by the pod transfer device 18, and the opening operation of the pod 2 by the pod opener 21 is simultaneously performed. As described above, when the opening operation is simultaneously performed in the other pod opener 21, the pod 2 set in the other pod opener 21 is completed simultaneously with the completion of the operation of loading the wafer 1 into the boat 30 in the one pod opener 21. The loading operation of the wafer into the boat 30 by the wafer transfer device 25 can be started. That is, since the wafer transfer device 25 can continuously carry out the loading operation of the wafers into the boat 30 without wasting a waiting time for the replacement operation of the pod 2, the throughput of the CVD apparatus 10 can be increased. it can.

  As shown in FIG. 3, when a predetermined number of wafers 1 are loaded into the boat 30, the boat 30 holding the group of wafers is lifted by the boat elevator 27 by the seal cap 29 being lifted. The inner tube 33 is loaded into the processing chamber 34 (boat loading) and remains in the processing chamber 34 while being supported by the seal cap 29. As shown in FIG. 4, the seal cap 29 reaching the upper limit is pressed against the manifold 36 to seal the inside of the process tube 31.

  Subsequently, the inside of the process tube 31 is exhausted by the exhaust pipe 38 and heated to the target temperature for sequence control of the temperature controller 55 by the heating lamp 52 group and the ceiling heating lamp 53 group. The actual temperature rise inside the process tube 31 due to heating of the heating lamp 52 group, ceiling heating lamp 53 group and cap heating lamp 53A group, and sequence control of the heating lamp 52 group, ceiling heating lamp 53 group and cap heating lamp 53A group Is corrected by feedback control based on the measurement result of the cascade thermocouple 56. Further, the boat 30 is rotated by the motor 47.

When the internal pressure and temperature of the process tube 31 and the rotation of the boat 30 become constant and stable as a whole, the raw material gas is introduced into the processing chamber 34 of the process tube 31 from the gas supply pipe 42 by the gas supply device 43. The source gas introduced by the gas supply pipe 42 flows through the processing chamber 34 of the inner tube 33, passes through the exhaust path 37, and is exhausted by the exhaust pipe 38. When flowing through the processing chamber 34, a CVD film is formed on the wafer 1 by a thermal CVD reaction caused by the source gas contacting the wafer 1 heated to a predetermined processing temperature. Incidentally, an example of processing conditions when silicon nitride (Si ₃ N ₄ ) is formed is as follows. The processing temperature is 700 to 800 ° C., the flow rate of SiH ₂ Cl ₂ as a raw material gas is 0.1 to 0.5 SLM (standard liter per minute), the flow rate of NH ₃ is 0.3 to 5 SLM, and the processing pressure is 20 to 100 Pa.

By the way, the temperature of the outer tube 32 and the heater unit 50 need not be maintained above the processing temperature, but is preferably reduced to a temperature lower than the processing temperature. Therefore, the film forming step is shown in FIG. As described above, the cooling air is supplied from the air supply pipe 62 and is exhausted from the sub exhaust port 65, the buffer unit 64, and the exhaust port 63, thereby being circulated through the cooling air passage 61. At this time, since the heat capacity of the heat insulating tank 51 is set smaller than usual, it can be rapidly cooled. In addition, since the cooling air passage 61 is isolated from the processing chamber 34, cooling air can be used as a refrigerant. However, in order to further improve the cooling effect and to prevent corrosion under high temperature due to impurities in the air. For this purpose, an inert gas such as nitrogen gas may be used as the refrigerant gas. Thus, by forcibly cooling the outer tube 32 and the heater unit 50 by the flow of the cooling air in the cooling air passage 61, for example, a silicon nitride film can prevent adhesion of NH ₄ Cl at 150 ° C. The temperature of the outer tube 32 can be maintained to an extent.

  When a predetermined processing time has elapsed, after the introduction of the processing gas is stopped, nitrogen gas is introduced into the process tube 31 from the gas supply pipe 42, and the injection port 66a of the long nozzle 66 and the injection of the short nozzle 67 are performed. The wafer 67 is sprayed from the mouth 67a. Since the wafer 1 group is directly cooled by the flow of nitrogen gas in the processing chamber 34 and the blowing to the wafer 1 group, the temperature of the wafer 1 group rapidly decreases at a large rate (speed), and the wafer 1 It descends uniformly over the entire length of the group and in the plane of the wafer 1.

  Subsequently, the boat 30 supported by the seal cap 29 is lowered by the boat elevator 27 and unloaded from the processing chamber 34 (boat unloading). In this boat unloading, the temperature of the wafer group 1 is rapidly lowered at a large rate (speed) by spraying the wafer group 1 from the ejection port 66a of the long nozzle 66 and the ejection port 67a of the short nozzle 67. The wafer 1 is lowered uniformly over the entire length of the group of wafers 1 and within the plane of the wafer 1. At this time, the temperature over the entire length of the group of wafers is measured by a thermocouple 70 standing between a long nozzle 66 and a short nozzle 67, and a nitrogen gas supply device 68 by a flow rate controller 69 based on the measured temperature. By controlling the supply flow rate of nitrogen gas to the long nozzle 66 and the short nozzle 67, the entire length of the wafer group 1 and the temperature in the plane of the wafer 1 are maintained uniformly. The thermocouple 70 is preferably maintained at a more uniform temperature by providing a plurality of measurement points.

  The processed wafer 1 of the boat 30 carried out to the standby chamber 26 is detached (discharged) from the boat 30 by the wafer transfer device 25 and inserted into the pod 2 opened in the pod opener 21 for storage. . Even when the processed wafers 1 are detached from the boat 30, the number of wafers 1 batch processed by the boat 30 is many times larger than the number of wafers 1 stored in one empty pod 2. The base pod 2 is repeatedly supplied to the upper and lower pod openers 21 and 21 alternately by the pod transfer device 18. Also in this case, during the wafer transfer operation to one (upper or lower) pod opener 21, transfer to the empty pod 2 and preparation operations to the other (lower or upper) pod opener 21 are simultaneously performed. As a result, the wafer transfer device 25 can continuously perform the detaching operation without wasting the waiting time for the replacement operation of the pod 2, so that the throughput of the CVD apparatus 10 can be increased.

  When a predetermined number of processed wafers 1 are stored, the pod 2 is closed with a cap attached thereto by a pod opener 21. Subsequently, the pod 2 storing the processed wafer 1 is transferred from the mounting table 22 of the pod opener 21 to the specified shelf plate 17 of the rotary pod shelf 15 by the pod transfer device 18 and temporarily stored. . Thereafter, the pod 2 storing the processed wafer 1 is transferred from the rotary pod shelf 15 to the pod loading / unloading port 12 by the pod transfer device 18, and unloaded from the pod loading / unloading port 12 to the outside of the casing 11 to be a pod stage. 14. The pod 2 placed on the pod stage 14 is transferred to the next process by the in-process transfer apparatus. The loading / unloading operation of the old and new pod 2 to / from the pod stage 14 and the replacement operation between the pod stage 14 and the rotary pod shelf 15 are performed during the loading / unloading operation of the boat 30 in the processing chamber 34 and the film forming process. Therefore, it is possible to prevent the working time of the entire CVD apparatus 10 from being extended.

  Thereafter, the film forming process is performed on the wafer 1 by the CVD apparatus 10 by repeating the above operation.

By the way, in general, while the wafer is left in the processing chamber, the temperature drop characteristic of the wafer is determined by the temperature of the processing chamber and the flow rate of nitrogen gas that is a cooling gas. However, in the process of unloading wafers from the processing chamber (boat unloading), the temperature drops sequentially from the wafers away from the processing chamber (heating source), causing a temperature difference between the wafers in the wafer group. To do. If there is a temperature difference between the wafers in the wafer group, for example, there is a difference between the characteristics of the IC acquired from the wafer positioned at the upper stage of the boat and the characteristics of the IC acquired from the wafer positioned at the lower stage of the boat. Will occur. Further, if there is a temperature difference in the wafer surface, for example, a difference occurs between the characteristics of the IC acquired from the high temperature region of the wafer and the characteristics of the IC acquired from the low temperature region of the wafer. Further, if the temperature difference between the wafers and the temperature difference within the wafer surface are significant, the IC characteristics are adversely affected by the thermal history of the wafer. In addition, when a heated wafer is exposed to an atmosphere containing a large amount of oxygen (O ₂ ), a natural oxide film is likely to be formed on the wafer.

  In this embodiment, during boat unloading, nitrogen gas is blown to the group of wafers from the ejection port 66a of the long nozzle 66 and the ejection port 67a of the short nozzle 67, so that the temperature of the wafer group 1 is increased at a high rate (speed). ) And is also lowered uniformly within the entire length of the wafer group 1 and within the plane of the wafer 1, the temperature difference between the wafers in the wafer group and the temperature difference within the wafer plane affect the IC characteristics. Adverse effects can be avoided. Further, since the temperature of the group of wafers 1 can be sufficiently lowered at the time of boat unloading, generation of a natural oxide film due to exposure of the heated wafer 1 to an atmosphere rich in oxygen can be prevented. .

Actual measured values are shown below.
FIG. 6 to FIG. 9 are graphs showing the relationship between the position in the height direction of the boat under each condition, the temperature and temperature deviation of the wafer peripheral portion and the central portion at each height, and time. As the temperature measuring means, a plurality of temperature measuring devices in which a thermocouple is embedded in the periphery and center of the dummy wafer are used, and these are arranged on the 62nd, 36th and 10th stages from the bottom of the boat, respectively. did. In each graph, the horizontal axis represents time, the left vertical axis represents the wafer peripheral and center temperatures (curves A to F) measured by the temperature measuring instrument at each stage, and the right vertical axis represents each stage. The temperature difference (curves G to I) between the wafer peripheral part and the central part measured by the temperature measuring device is shown. The temperature of the processing chamber 34 was set to 600 ° C., the temperature of the heating lamp and the ceiling heating lamp was controlled, and the cap heating lamp was turned off. Moreover, the descending speed of the boat was set to 600 mm / min.

  FIG. 6 shows a conventional example, and is a graph showing a temperature lowering characteristic in a case where nitrogen gas is continuously supplied at a rate of 200 l (liter) / min when the boat descends. As can be seen from this graph, for example, it takes 4 minutes for the 62nd stage to cool down to 150 ° C. Further, the temperature deviation at the 62nd stage is -160 ° C.

  FIG. 7 is a graph showing the temperature lowering characteristics when nitrogen gas is kept flowing at 200 l / min using only a long nozzle when the boat descends. As can be seen from this graph, for example, in the 62nd stage, the temperature decreases to 150 ° C., but decreases to 3 minutes. Further, the temperature deviation at the 62nd stage is reduced to −80 ° C.

  FIG. 8 is a graph showing a temperature drop characteristic when nitrogen gas is kept flowing at 200 l / min using a long nozzle and a short nozzle when the boat descends. As can be seen from this graph, for example, in the 62nd stage, the temperature decreases to 150 ° C. but decreases to 2.5 minutes. Further, the temperature deviation at the 62nd stage is reduced to −60 ° C.

  FIG. 9 is a graph showing the temperature lowering characteristics when a long nozzle is used when the boat descends and nitrogen gas is continuously supplied at 300 l / min. As can be seen from this graph, for example, in the 62nd stage, the temperature decreases to 150 ° C. but decreases to 2 minutes. The temperature deviation at the 62nd stage is reduced to -70 ° C.

  As can be seen from these graphs, at the time of boat unloading, nitrogen gas is blown onto the group of wafers by the nozzles 66 and 67 that are erected on the seal cap 29, thereby increasing the temperature drop rate of the group of wafers. The uniformity of the in-plane temperature of the wafer 1 can be improved.

  Further, when the boat 30 is rotated by the motor 47 when the nitrogen gas is blown onto the wafer 1, the temperature difference in the plane of the wafer 1 can be further reduced. That is, by rotating the wafer 1 together with the boat 30 while bathing the nitrogen gas on the wafer 1, the nitrogen gas can be sprayed evenly over the entire circumference of the wafer 1, thereby reducing the temperature difference in the plane of the wafer 1. be able to.

  According to the embodiment, the following effects can be obtained.

1) At the time of boat unloading, nitrogen gas is blown onto the wafer group by a nozzle erected on the seal cap, thereby increasing the temperature drop rate of the wafer group and improving the uniformity of the in-plane temperature of the wafer 1. it can.

2) During boat unloading, adverse effects on IC characteristics can be avoided by preventing the temperature difference between wafers in the wafer group and the temperature difference within the wafer surface, and the temperature of the wafer group can be avoided. Therefore, it is possible to prevent generation of a natural oxide film due to exposure of a heated wafer to an atmosphere containing a large amount of oxygen.

3) By sufficiently lowering the temperature of the wafer group at the time of boat unloading, the temperature lowering waiting time after boat unloading can be omitted or shortened, so that the throughput of the CVD apparatus can be improved.

4) A plurality of nozzles are arranged on the seal cap at intervals in the circumferential direction and are vertically erected. Each nozzle has a plurality of injection ports that inject nitrogen gas radially toward the center of the boat. By opening each of them, the temperature of the wafer group can be lowered more rapidly at a large rate (speed), so that the throughput of the CVD apparatus can be further improved and the thermal history of the wafer can be reduced. By doing so, the yield of the IC can be improved.

5) By configuring the nitrogen gas supply device that supplies nitrogen gas to the nozzle with the flow rate adjustment controller, the amount of nitrogen gas injected from the nozzle can be controlled by the nitrogen gas supply device. The cooling capacity can be adjusted.

6) By providing nozzles with different lengths in the seal cap, the nitrogen gas injection flow rate can be zoned, so that the cooling capacity of the nozzles can be zoned and the wafer group can be cooled uniformly throughout. Or by adjusting the cooling distribution.

7) When nitrogen gas is blown onto the wafer, the boat is rotated by a motor so that nitrogen gas can be blown evenly over the entire circumference of the wafer, thus further reducing the temperature difference in the wafer surface. be able to.

8) By providing a thermocouple together with the nozzle on the seal cap, the injection flow rate of nitrogen gas from the nozzle can be feedback controlled, thus reliably preventing temperature differences between wafers and in the wafer surface. be able to. In addition, since the actual temperature of the wafer can be monitored by a thermocouple, the wafer can be removed from the boat at an appropriate temperature and time, and as a result, the throughput of the CVD apparatus is further improved. Can be made.

9) By supplying cooling air to the space between the heat insulation tank and the process tube after the film formation step, the temperature of the heat insulation tank and the process tube can be rapidly lowered at a large rate (speed). This can be further improved.

10) By circulating cooling air through the space between the heat insulation tank and the outer tube, it is possible to prevent film formation and by-products from adhering to the inner surface of the outer tube. This can be prevented and the cleaning time can be shortened.

  Needless to say, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.

  For example, the blowing of nitrogen gas to the wafer by the nozzle provided in the seal cap may be executed from the start of boat loading. When the temperature of the wafer rises, the temperature at the peripheral edge in the wafer surface tends to be higher than the temperature at the center, which adversely affects film quality, film thickness uniformity, and temperature deviation. If the spraying is executed from the start of boat loading, the temperature rise distribution in the wafer surface can be made uniform, and this adverse effect can be prevented. Although two cooling gas nozzles have been exemplified, three or more cooling gas nozzles may be used.

The heating means is not limited to using a halogen lamp with a peak wavelength of heat energy of 1.0 μm, but other heat rays (infrared rays, far-infrared rays, etc.) wavelength (for example, 0.5 to 3.5 μm) are irradiated A heating lamp (for example, a carbon lamp) may be used, or an induction heater, a metal heating element such as molybdenum silicide or Fe—Cr—Al alloy may be used.
The heating means (heater unit) is the heating lamp 52 group, the ceiling heating lamp 53 group, and the cap heating lamp 53A group, but may be only the heating lamp 52 group, or only the heating lamp 52 group and the ceiling heating lamp 53 group or The configuration of the heating lamp 52 group and the cap heating lamp 53A group may be adopted.

  The outer tube is not limited to being formed of quartz, but may be formed of a material that can transmit the wavelength of the heat rays and that can prevent contamination of the wafer.

  Although the CVD apparatus has been described in the above embodiment, the present invention can be applied to all substrate processing apparatuses such as an oxidation / diffusion apparatus and an annealing apparatus.

  The substrate to be processed is not limited to a wafer, but may be a photomask, a printed wiring board, a liquid crystal panel, a compact disk, a magnetic disk, or the like.

It is a partially-omission perspective view which shows the CVD apparatus which is one embodiment of this invention. FIG. FIG. It is a partially omitted rear cross-sectional view showing the main part. It is a perspective view which shows the principal part. It is a graph which shows the temperature fall characteristic of a comparative example. It is a graph which shows the temperature fall characteristic at the time of using one nozzle. It is a graph which shows the temperature fall characteristic at the time of using a plurality of nozzles. It is a graph which shows the temperature fall characteristic at the time of increasing the flow volume of nitrogen gas.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Wafer (substrate), 2 ... Pod, 10 ... CVD apparatus (substrate processing apparatus), 11 ... Housing | casing, 12 ... Pod loading / unloading exit, 13 ... Front shutter, 14 ... Pod stage, 15 ... Rotary pod shelf, DESCRIPTION OF SYMBOLS 16 ... Support | pillar, 17 ... Shelf board, 18 ... Pod conveyance apparatus, 19 ... Sub housing | casing, 20 ... Wafer loading / unloading exit, 21 ... Pod opener, 22 ... Mounting stand, 23 ... Cap attaching / detaching mechanism, 24 ... Transfer chamber, 25 ... Wafer transfer device, 26 ... Standby chamber, 27 ... Boat elevator, 28 ... Arm, 29 ... Seal cap, 30 ... Boat (substrate holder), 31 ... Process tube, 32 ... Outer tube, 33 ... Inner tube, 34 ... Processing chamber, 35 ... Furnace port, 36 ... Manifold, 37 ... Exhaust passage, 38 ... Exhaust pipe, 39 ... Exhaust device, 40 ... Pressure sensor, 41 ... Pressure controller, 42 ... Gas supply Pipe, 43 ... Gas supply device, 44 ... Gas flow controller, 45 ... Rotating shaft, 46 ... Drive controller, 47 ... Motor, 48 ... Heat insulation cap part, 50 ... Heater unit, 51 ... Heat insulation tank, 52 ... Heating lamp (heating) Means), 53 ... Ceiling heating lamp, 53A ... Cap heating lamp, 54 ... Heating lamp driving device, 55 ... Temperature controller, 56 ... Cascade thermocouple, 57 ... Reflector, 58 ... Cooling water piping, 59 ... Ceiling reflector, 60 ... Cooling water piping, 61 ... cooling air passage, 62 ... air supply pipe, 63 ... exhaust port, 64 ... buffer portion, 65 ... sub exhaust port, 66 ... long nozzle (cooling gas nozzle), 66a ... injection port, 67 ... short nozzle ( Cooling gas nozzle), 67a ... injection port, 68 ... nitrogen gas supply device, 69 ... flow rate adjustment controller, 70 ... thermocouple (temperature measuring device).

Claims (3)

A substrate holder for holding a plurality of substrates in a vertical direction;
A processing chamber for processing a plurality of substrates held by the substrate holder,
A heater unit installed around the processing chamber for heating the substrate;
A gas supply pipe for supplying a processing gas to the processing chamber;
An exhaust pipe for exhausting the processing chamber;
An elevator that raises and lowers a seal cap that holds the substrate holder;
A cooling gas nozzle that is provided to be connected to the seal cap so as to be moved up and down by the elevator, and has a plurality of jet nozzles for jetting a cooling gas for cooling the substrate along the vertical direction of the processing chamber ;
A temperature sensor provided to be connected to the seal cap so as to be moved up and down by the elevator, and for detecting a temperature of the substrate held by the substrate holder;
Gas flow control for controlling the supply gas flow rate of the cooling gas to the cooling gas nozzle based on the temperature detected by the temperature sensor when unloading at least the processed substrate held by the substrate holder from the processing chamber And
A substrate processing apparatus comprising:   The substrate processing apparatus according to claim 1, wherein the cooling gas nozzle includes a plurality of nozzles having different lengths in a direction perpendicular to a main surface of the substrate. A seal cap holding a substrate holding body in which a plurality of substrates are held in a vertical direction , and a cooling gas nozzle and a temperature sensor provided to connect to the seal cap are raised by an elevator to raise the substrate holding body and the cooling Carrying a gas nozzle and the temperature sensor into a processing chamber;
Heating the substrate in the processing chamber with a heater unit and processing the substrate;
A seal cap that holds the substrate holding body in which a plurality of the substrates are held in the vertical direction , and the cooling gas nozzle and the temperature sensor that are provided so as to be connected to the seal cap are lowered by the elevator to form the substrate. Carrying out the holding body , the cooling gas nozzle and the temperature sensor from the processing chamber,
At least in the carry-out step, the gas flow rate control unit controls the supply gas flow rate of the cooling gas to the cooling gas nozzle based on the temperature detected by the temperature sensor, and is provided along the vertical direction of the processing chamber of the cooling gas nozzle. method for producing a plurality of the ejection ports to the plurality of substrates held by the substrate holding member is provided with a spouted step a cooling gas, and wherein a, which is.

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