JP3907546B2 - Vertical heat treatment apparatus and method for manufacturing semiconductor integrated circuit device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vertical heat treatment apparatus. For example, in a method for manufacturing a semiconductor integrated circuit device (hereinafter referred to as an IC), various types of semiconductor wafers (hereinafter referred to as wafers) on which an integrated circuit including semiconductor elements is fabricated. The present invention relates to a vertical heat treatment apparatus (furnace) for performing thermal treatment.
[0002]
[Prior art]
In an IC manufacturing method, a batch type vertical hot wall is an example of a vertical heat treatment apparatus for depositing silicon nitride (Si ₃ N ₄ ), silicon oxide (SiOx), polysilicon, or the like on a wafer. Mold vacuum CVD equipment is widely used. A batch type vertical hot wall type reduced pressure CVD apparatus (hereinafter referred to as a CVD apparatus) includes an inner tube forming a processing chamber and an outer tube surrounding the inner tube. A manifold connected to an exhaust pipe for exhausting gas and a gas introduction pipe for supplying gas to the processing chamber, a heater unit laid outside the process tube to heat the processing chamber, and a plurality of wafers are aligned vertically And a boat that holds the plurality of wafers into the processing chamber, is loaded into the processing chamber from the bottom furnace port (boat loading), and the film forming gas is introduced into the processing chamber through the gas introduction pipe. The process chamber is heated by the heater unit and the CVD film is deposited on the wafer. It has been.
[0003]
In this type of conventional CVD apparatus, it is known that by-products (intermediate products) are generated inside the process tube under certain specific conditions (temperature, pressure, gas type, etc.). For example, when silicon nitride (Si ₃ N ₄ ) is formed on a wafer, it is known that by-products such as ammonia chloride (NH ₄ Cl) adhere to the place where the reaction gas is 150 ° C. or lower. Yes.
[0004]
[Problems to be solved by the invention]
In the CVD apparatus described above, the seal ring laid on the outer tube and the manifold is forcibly cooled to prevent deterioration, so that by-products adhere to and accumulate on the lower ends of the inner tube and the outer tube and the manifold. End up. Since the accumulated by-product becomes a source of foreign matter, a maintenance operation for removing the accumulated by-product is periodically performed.
[0005]
An object of the present invention is to provide a vertical heat treatment apparatus that can prevent by-products from adhering to the vicinity of a furnace port.
[0006]
[Means for Solving the Problems]
A vertical heat treatment apparatus according to the present invention includes an inner tube that forms a processing chamber, an outer tube that surrounds the inner tube, a process tube installed in a vertical shape, a heater unit that heats the processing chamber, An exhaust pipe for exhausting the processing chamber and a manifold connected with a gas introduction pipe for supplying gas to the processing chamber, and a seal flange is interposed between the outer tube and the manifold, A cooling medium passage is laid on the seal flange.
[0007]
According to the above-mentioned means, since the seal flange is interposed between the outer tube and the manifold, it is possible to suppress a decrease in the temperature of the manifold due to forced cooling for preventing deterioration of the seal ring, and as a result. Byproduct can be prevented from adhering to and depositing on the inner wall surface of the manifold.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0009]
As shown in FIG. 1, a CVD apparatus 10 according to the present embodiment includes a vertical process tube 11 that is vertically arranged and fixedly supported so that the center line is vertical. . The process tube 11 includes an outer tube 12 and an inner tube 13 that are arranged concentrically with each other. The outer tube 12 is made of quartz glass or silicon carbide (SiC) and has a cylindrical shape with the upper end closed and the lower end opened. The inner tube 13 is formed integrally and is formed in a cylindrical shape using quartz glass or silicon carbide and having both upper and lower ends opened. A cylindrical hollow portion of the inner tube 13 forms a processing chamber 14 into which a plurality of wafers held concentrically aligned by a boat are loaded, and a lower portion of the inner tube 13 serves as a substrate to be processed. A furnace port 15 having a diameter larger than the maximum outer diameter of the wafer is formed.
[0010]
As shown in FIG. 1 and FIG. 2, a manifold 16 formed in a short cylindrical shape using a metal such as stainless steel at the lower end of the process tube 11 and opened at both upper and lower ends has a seal flange described later. 21 is disposed concentrically with the process tube 11, and the process tube 11 is supported vertically by the manifold 16 being supported by the housing 2. A partition wall 17 protrudes horizontally at an intermediate portion of the inner periphery of the manifold 16, and the partition wall 17 partitions the inner space of the manifold 16 vertically. A large-diameter exhaust pipe 18 having the other end connected to a vacuum exhaust device (not shown) on the side wall of the manifold 16 communicates fully with the upper space in the inner space of the manifold 16 partitioned by the partition wall 17. The exhaust pipe 18 is connected, and exhausts the exhaust path 19 formed by the clearance between the outer tube 12 and the inner tube 13. A gas introduction pipe 20 is connected to the lower end portion of the side wall of the manifold 16 so as to communicate with the lower space on the furnace port 15 side in the inner space of the manifold 16 partitioned by the partition wall 17. The other end is connected to a gas supply device (not shown) for supplying a gas such as a source gas or nitrogen gas.
[0011]
As shown in FIGS. 2 and 3, the seal flange 21 is formed in a circular ring shape using the same heat-resistant material as the manifold 16, and the inner diameter of the seal flange 21 is larger than the inner diameter of the manifold 16. The outer diameter of the seal flange 21 is set larger than the outer diameter of the flange portion 12 a of the outer tube 12. A positioning recess 22 is concentrically recessed on the upper surface of the seal flange 21, and the inner diameter of the positioning recess 22 is set slightly larger than the outer diameter of the flange portion 12 a of the outer tube 12. A seal ring storage groove 23 is concentrically recessed on the bottom surface of the positioning recess 22 of the seal flange 21, and a seal ring 24 is stored in the seal ring storage groove 23. A cooling water passage 25 as a cooling medium passage is laid concentrically at a portion of the seal flange 21 immediately below the seal ring housing groove 23, and cooling water for circulating the cooling water 26 as a cooling medium through the cooling water passage 25. A supply path (not shown) is connected.
[0012]
On the other hand, a flange portion 27 protrudes radially outward from the upper end portion of the manifold 16, and a seal ring storage groove 28 is concentrically recessed on the upper surface of the flange portion 27. The seal ring 29 is accommodated in. A positioning convex portion 30 is formed concentrically on the upper side of the flange portion 27 of the manifold 16, and a heat insulating layer forming groove 31 is formed in an L-shaped groove shape at a corner portion of the flange portion 27 and the positioning convex portion 30. ing. As shown in FIG. 3A, in the state where the seal flange 21 is placed on the flange portion 27 of the manifold 16, the inner peripheral surface of the seal flange 21 and the outer peripheral surface of the positioning convex portion 30 of the manifold 16 A heat conducting ring 32 is interposed between the two. The heat conducting ring 32 is made of a heat-resistant material such as fluorine resin, and is formed in a circular ring shape having an outer diameter smaller than the inner diameter of the seal flange 21 and an inner diameter larger than the outer diameter of the positioning protrusion 30 of the manifold 16. Has been. Therefore, heat insulating layer portions 33 and 33 are formed on both sides of the heat conducting ring 32 between the inner peripheral surface of the seal flange 21 and the outer peripheral surface of the positioning convex portion 30 of the manifold 16.
[0013]
As shown in FIGS. 2 and 3, the outer tube 12 is placed on the bottom surface of the positioning recess 22 of the seal flange 21 with the seal flange 21 and the heat conducting ring 32 assembled to the manifold 16. As a result, the outer tube 12 is positioned in the manifold 16 and the inner tube 13 by the positioning recess 22 and the flange portion 12a. Thereafter, the pressing ring 34 placed on the seal flange 21 is suppressed by the outer tube 12, so that the seal flange 21, the heat conducting ring 32, and the outer tube 12 are fixed. The heater unit 35 is provided concentrically so as to surround the process tube 11 outside the process tube 11, and is installed vertically by being supported by the housing 2. The heater unit 35 is configured to heat the inside of the process tube 11 uniformly or with a predetermined temperature distribution throughout.
[0014]
As shown in FIGS. 1 and 2, the CVD apparatus 10 includes a furnace port opening / closing device 36 as an isolation valve that opens and closes the furnace port 15 of the manifold 16. It arrange | positions concentrically with the extended line of a center line, and is comprised so that it may be raised / lowered by a boat elevator (not shown). The furnace opening / closing device 36 has a base 37 that is vertically moved by a boat elevator, and a seal cap 38 that is formed in a disk shape substantially equal to the outer diameter of the manifold 16 and is in close contact with the lower end surface of the manifold 16 to seal the furnace opening 15. The seal cap 38 is arranged in parallel with a slight gap directly above the base 37 and is supported horizontally. A rotation shaft 39 rotated by a rotation drive device (not shown) is vertically inserted on the center line of the base 37 and is rotatably supported by a bearing device. Stands vertically and is fixed.
[0015]
As shown in FIG. 1, the boat 40 includes a pair of upper and lower end plates 41 and 42 and a plurality of holding members 43 disposed vertically between the both end plates 41 and 42. A plurality of holding grooves 44 are arranged in the holding member 43 at equal intervals in the longitudinal direction so as to be opened in the same plane. The wafer 1 is held in the boat 40 by being aligned in a state where the centers are aligned with each other horizontally by inserting the outer peripheral portion between the plurality of holding grooves 44.
[0016]
Next, a case where silicon nitride (Si ₃ N ₄ ) is formed on a wafer using the CVD apparatus according to the above configuration will be described.
[0017]
In the boat loading / unloading chamber directly below the process tube 11, the plurality of wafers 1 are loaded into the boat 40 by the wafer transfer device in a state in which the center lines are aligned with each other. As shown in FIG. 1, the boat 40 loaded with a plurality of wafers 1 is placed on the seal cap 38 in a state where the direction in which the group of wafers 1 is arranged is vertical, and is lifted by the boat elevator. Then, it is carried into the processing chamber 14 from the furnace port 15 of the manifold 16 (boat loading), and remains in the processing chamber 14 while being supported by the seal cap 38. In this state, the seal cap 38 hermetically seals the furnace port 15.
[0018]
The inside of the process tube 11 is exhausted by the exhaust pipe 18 to a predetermined degree of vacuum (several tens to tens of thousands Pa). In the present embodiment, since the exhaust pipe 18 is set to have a large diameter, the exhaust speed of the exhaust pipe 18 with respect to the exhaust path 19 can be set larger than in the conventional example. By-products can be prevented from adhering and accumulating on the surfaces of the passage 19, the manifold 16 and the exhaust pipe 18. Further, the inside of the process tube 11 is uniformly heated to a predetermined temperature (about 700 ° C.) by the heater unit 35.
[0019]
When the temperature and pressure inside the process tube 11 are stabilized, the film forming gas 51 is supplied to the processing chamber 14 of the inner tube 13 by the gas introduction pipe 20. In the present embodiment, SiH ₂ Cl ₂ gas and ammonia (NH ₃ ) gas are used as the film forming gas. Incidentally, the NH ₃ gas is supplied before the SiH ₂ Cl ₂ gas is supplied. During the processing, the boat 40 is rotated by the rotation shaft 39.
[0020]
The supplied film forming gas 51 rises in the processing chamber 14 of the inner tube 13, flows out from the upper end opening to the exhaust path 19 formed by the gap between the inner tube 13 and the outer tube 12, and is exhausted from the exhaust pipe 18. . The deposition gas 51 comes into contact with the surface of the wafer 1 when passing through the processing chamber 14. A Si ₃ N ₄ film is deposited (deposited) on the surface of the wafer 1 by the thermal CVD reaction by the film forming gas 51 accompanying the contact with the wafer 1.
[0021]
When a predetermined processing time for depositing a desired thickness of the Si ₃ N ₄ film elapses, the seal cap 38 is lowered, the furnace port 15 is opened, and the wafer group 1 is held in the boat 40. Is unloaded from the furnace port 15 to the boat loading / unloading chamber directly below the process tube 11.
[0022]
By the way, in the above film forming process, the film forming gas 51 supplied from the gas introduction pipe 20 to the furnace port 15 contacts the surface of the furnace port 15 of the manifold 16 or the inner tube 13. At this time, when the temperature of the manifold 16 and the inner tube 13 is lower than the temperature of the processing chamber 14, a by-product (intermediate product) such as NH ₄ Cl is formed on the inner wall surface of the manifold 16 and the inner tube 13. It adheres to the surface of the furnace port 15. By-products attached to these surfaces accumulate each time the film formation process is repeated, and the accumulated thickness of the deposited film increases as the number of batch processes for film formation increases. . When the accumulated deposited film reaches a certain value, it becomes easy to peel off, and the generation of particles increases rapidly.
[0023]
On the other hand, in the above film forming process, in order to prevent deterioration of the seal ring 24 of the seal flange 21 and the seal ring 29 of the manifold 16 due to heat, the cooling water 26 is circulated through the cooling water passage 25, whereby the seal flange 21. The seal ring 24 and the seal ring 29 of the manifold 16 are forcibly cooled. However, in the CVD apparatus 10 according to the present embodiment, the seal flange 21 is interposed between the outer tube 12 and the manifold 16, so that the temperature of the manifold 16 by the cooling water passage 25 of the seal rings 24 and 29 is increased. Therefore, it is possible to prevent the by-product from adhering to and depositing on the inner wall surface of the manifold. In addition, since the heat insulating layer 33 is interposed between the seal flange 21 and the manifold 16, a decrease in the temperature of the manifold 16 due to the cooling water passage 25 of the seal flange 21 can be suppressed. By-products can be prevented from adhering and depositing on the inner wall surface. Moreover, in the present embodiment, the heat transfer path 52 indicated by the broken line arrow in FIG. 3 is formed by the heat conduction ring 32 in which the heat of the outer tube 12 is interposed between the outer tube 12 and the manifold 16 in the manifold 16. As a result, the temperature drop of the manifold 16 due to the cooling water passage 25 of the seal flange 21 can be further suppressed, so that it is ensured that by-products adhere to and accumulate on the inner wall surface of the manifold 16. Further, heat transfer from the outer tube 12 to the seal ring 24 can be reduced. Therefore, it is possible to prevent by-products from accumulating on these surfaces, to prevent generation of particles, and to eliminate or reduce maintenance work for removing this deposited film. can do.
[0024]
According to the embodiment described above, the following effects can be obtained.
[0025]
1) By interposing a seal flange between the outer tube and the manifold, it is possible to suppress a decrease in the temperature of the inner tube due to forced cooling to prevent deterioration of the seal ring. By-products can be prevented from adhering and depositing in the vicinity.
[0026]
2) By providing a heat insulation layer between the seal flange and the manifold, it is possible to suppress a decrease in the temperature of the manifold due to forced cooling to prevent deterioration of the seal ring. An object can be prevented from adhering and accumulating.
[0027]
3) By installing a heat conduction ring between the outer tube and the manifold, the heat of the outer tube can be transferred to the manifold, so the temperature of the manifold is reduced by forced cooling to prevent deterioration of the seal ring. And by-products can be prevented from adhering to and depositing near the furnace port of the manifold.
[0028]
4) By preventing the by-product of the processing gas from adhering to the inner wall surface of the manifold, it is possible to prevent the by-product from accumulating on these surfaces. Can be prevented, and as a result, the manufacturing yield and throughput of the CVD apparatus, and hence the IC manufacturing method, can be increased.
[0029]
5) By preventing the deposition of by-products, the maintenance work for removing the deposited film can be abolished or reduced, so that the operating efficiency of the CVD apparatus and thus the productivity of the IC manufacturing method can be increased. it can.
[0030]
6) By forcibly cooling the seal ring, the life of the seal ring can be extended, so that the operating efficiency of the CVD apparatus and thus the productivity of the IC manufacturing method can be increased.
[0031]
7) By installing a seal flange between the outer tube and the manifold, a large-diameter exhaust pipe can be connected to the manifold, so the exhaust pipe exhaust speed can be set large. By-products can be prevented from adhering to the inner surface of the exhaust pipe, the outer peripheral surface of the manifold, the inner peripheral surface of the outer tube, and the like.
[0032]
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.
[0033]
For example, the cooling medium for forcibly cooling the seal ring is not limited to using cooling water, and a cooling gas such as nitrogen gas may be used.
[0034]
The film type to be formed is not limited to a silicon nitride film, but may be a polysilicon film, a silicon oxide film, or the like.
[0035]
The vertical heat treatment apparatus is not limited to a CVD apparatus, but is also used for oxidation treatment, diffusion treatment, reflow treatment and annealing treatment for carrier activation and planarization after ion implantation as well as oxidation and diffusion treatment. It can be applied to all devices.
[0036]
In the above embodiment, the case where the wafer is processed has been described. However, the processing target may be a photomask, a printed wiring board, a liquid crystal panel, a compact disk, a magnetic disk, or the like.
[0037]
【The invention's effect】
As described above, according to the present invention, it is possible to prevent the by-product from adhering to the vicinity of the furnace port.
[Brief description of the drawings]
FIG. 1 is a front sectional view showing a CVD apparatus according to an embodiment of the present invention.
FIG. 2 is a front sectional view of the main part.
3 (a) is an enlarged cross-sectional view of part a of FIG. 2, and FIG. 3 (b) is an enlarged cross-sectional view showing an exploded main part thereof.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Wafer (substrate to be processed), 2 ... Housing, 3 ... Boat loading / unloading chamber, 10 ... CVD apparatus (vertical heat treatment apparatus), 11 ... Process tube, 12 ... Outer tube, 12a ... Flange part, 13 ... Inner Tubes 14, processing chambers 15, furnace ports 16, manifolds 17, partition walls 18, exhaust pipes 19, exhaust passages 20, gas introduction pipes 21, seal flanges 22, positioning recesses 23, seal rings Storage groove, 24 ... Seal ring, 25 ... Cooling water passage (cooling medium passage) 26 ... Cooling water (cooling medium), 27 ... Flange, 28 ... Seal ring storage groove, 29 ... Seal ring, 30 ... Positioning convex part, 31 ... heat insulation layer forming groove, 32 ... heat conduction ring, 33 ... heat insulation layer part, 34 ... pressing ring, 35 ... heater unit, 36 ... furnace opening / closing device, 37 ... base, 38 ... seal cap 39 ... rotary shaft, 40 ... boat, 41, 42 ... end plate, 43 ... holding member, 44 ... holding groove 51 ... film forming gas, 52 ... heat transfer path.

Claims (3)

A process tube that is installed in a vertical form a processing chamber, a heater unit for heating the processing chamber, a gas inlet tube for supplying a gas to the exhaust pipe and the process chamber for exhausting the processing chamber Ru connected cylindrical a manifold formed in a shape provided with a,
In the manifold, a flange portion protrudes radially outward, and a positioning convex portion is formed concentrically on the upper side of the flange portion,
Between the process tube and the flange portion , a seal flange having a larger diameter than the positioning convex portion is interposed, and a cooling medium passage is laid in the seal flange,
A vertical heat treatment apparatus , wherein a heat insulating layer is formed between the seal flange and the outer peripheral surface of the positioning convex portion . 2. The vertical heat treatment according to claim 1, wherein a heat conduction ring is provided between the seal flange and the positioning convex portion to transfer heat of the process tube to the seal flange. apparatus. A method for manufacturing a semiconductor integrated circuit device, wherein the vertical heat treatment device according to claim 1 or 2 is used for processing.
  Supplying gas from the gas introduction pipe to the processing chamber;
  The heater unit heating the processing chamber;
  The gas contacting the substrate to be processed in the processing chamber;
  Exhausting the processing chamber from the exhaust pipe;
  The cooling medium flowing through the cooling medium passage;
  A method for manufacturing a semiconductor integrated circuit device, comprising:

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