JP2004296659A - Substrate processing apparatus and method of manufacturing semiconductor device - Google Patents

Abstract

An object of the present invention is to prevent circulating flow, improve film thickness uniformity, and reduce particles.
The CVD apparatus includes an inner tube (2) into which a boat (11) holding a wafer (10) is loaded, an outer tube (3) surrounding the inner tube (2), and an exhaust hole (24) which is opened perpendicular to the outer tube (3) and exhausts the inner tube (2). 25, a preliminary chamber 21 formed to bulge radially outward at a position facing the exhaust hole 25 of the inner tube 2, and a pair of gas inlets laid vertically close to each other in the preliminary chamber 21. The nozzles 22 are provided with a plurality of sets of three orifices 24 each of which is opened in the same plane of the gas introduction nozzles 22.
[Effect] Since the gas is dispersed from the three ejection ports to attenuate the momentum of the ejection, generation of vortices can be prevented, so that the contact time of the gas with the wafer can be prevented from being prolonged, and the polysilicon film can be prevented. It is possible to prevent quality deterioration and generation of particles.
[Selection] Fig. 2

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a substrate processing technique, and more particularly to a technique for improving uniformity of film thickness in a substrate surface. For example, in a method of manufacturing a semiconductor integrated circuit device (hereinafter, referred to as an IC), a semiconductor wafer (IC) is manufactured. Hereafter, the present invention relates to a wafer which is effective for depositing (depositing) a polysilicon or a silicon nitride film on a wafer.
[0002]
2. Description of the Related Art In a method of manufacturing an IC, a batch-type vertical hot-wall type reduced-pressure CVD apparatus (hereinafter, referred to as a CVD apparatus) is widely used for depositing a CVD film such as a polysilicon or a silicon nitride film on a wafer. A conventional CVD apparatus of this type includes a vertically installed process tube composed of an inner tube and an outer tube surrounding the inner tube, a boat for holding a plurality of wafers and carrying the wafer into the inner tube, and an inner tube. A gas introduction nozzle for introducing the raw material gas into the tube, an exhaust port for exhausting the inside of the process tube to reduce the pressure, and a heater unit laid outside the process tube to heat the inside of the process tube; In some of these, a plurality of ejection ports are opened corresponding to each wafer held by the boat, and an exhaust hole is opened in a side wall of the inner tube (for example, see Patent Document 1).
[0003]
In this CVD apparatus, a plurality of wafers are loaded (boat loading) from the furnace port at the lower end into the inner tube in a state where the wafers are long and aligned and held by the boat, and a raw material gas is introduced into the inner tube by a gas introduction nozzle. At the same time, the inside of the process tube is heated by the heater unit, so that the CVD film is deposited on the wafer. At this time, the raw material gas horizontally ejected from the plurality of ejection ports of the gas introduction nozzle flows between the upper and lower wafers held horizontally by the boat, comes into contact with the surface of the wafer, and is opened in the inner tube. The air is exhausted from the exhaust hole to the outside of the inner tube by the exhaust force of the exhaust port.
[0004]
[Patent Document 1]
JP 2000-311862 A [0005]
[Problems to be solved by the invention]
In the above-described CVD apparatus, the gas ejected at a high speed from the ejection into the processing chamber of several Pa to several hundred Pa from the ejection port of the gas introduction nozzle is greatly attenuated, so that a large vortex (circulation flow) due to a difference in pressure is generated. The vortex is generated and the gas flow path is lengthened, so that there is a problem that the contact time of the gas with the wafer is prolonged. For example, in the case of forming a polysilicon film, if the passage time of monosilane (SiH ₄ ) in the high temperature region becomes long, the decomposition reaction in the gas phase excessively proceeds, so that the polysilicon becomes powdery. As a result, they are deposited and adhere to the surface of the wafer, which not only deteriorates the quality of the polysilicon film but also causes the generation of particles.
[0006]
An object of the present invention is to prevent a gas ejected from an ejection port from generating a large vortex, thereby improving the uniformity of film thickness and film quality of a wafer and reducing particles, and a method of manufacturing a semiconductor device. Is to provide.
[0007]
[Means for Solving the Problems]
The substrate processing apparatus according to the present invention includes: a process tube including an inner tube into which a substrate is loaded and an outer tube surrounding the inner tube; a gas introduction nozzle configured to introduce a gas into the inner tube; A substrate processing apparatus having an exhaust port for exhausting air.
The gas introduction nozzle is characterized in that at least a plurality of ejection ports are opened in a plane parallel to a main surface of the substrate.
[0008]
According to the above-described means, the gas is dispersed and ejected from the plurality of ejection ports of the gas introduction nozzle into the inner tube to attenuate the momentum, so that a large vortex is generated near the gas introduction nozzle. The phenomenon is prevented. As a result, it is possible to prevent the contact time of the gas with the substrate from being lengthened, so that the processing state becomes uniform in the entire substrate and the entire substrate group.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0010]
In the present embodiment, the substrate processing apparatus according to the present invention is configured as a CVD apparatus (batch type vertical hot wall type reduced pressure CVD apparatus) as shown in FIG. The CVD apparatus shown in FIG. 1 includes a vertical process tube 1 which is vertically arranged so that a center line thereof becomes vertical and is fixedly supported. The process tube 1 includes an inner tube 2 and an outer tube 3. It is composed of Each of the inner tube 2 and the outer tube 3 is made of a material having high heat resistance such as quartz glass or silicon carbide (SiC) and is integrally formed into a cylindrical shape.
[0011]
The inner tube 2 is formed in a cylindrical shape whose upper end is closed and whose lower end is opened. The cylindrical hollow portion of the inner tube 2 defines a processing chamber 4 into which a plurality of wafers held long and aligned by a boat are loaded. Has formed. The lower end opening of the inner tube 2 constitutes a furnace port 5 for taking in and out the wafer 10 as a substrate to be processed. Therefore, the inner diameter of the inner tube 2 is set to be larger than the maximum outer diameter of the wafer 10 to be handled. The outer tube 3 is formed in a cylindrical shape having a shape similar to the inner tube 2 and having a closed upper end and an open lower end. The outer tube 3 is concentrically covered so as to surround the outer side of the inner tube 2. The lower end between the inner tube 2 and the outer tube 3 is hermetically sealed by a manifold 6 formed in a circular ring shape. The manifold 6 is used for maintenance and inspection work and cleaning work on the inner tube 2 and the outer tube 3. Therefore, it is detachably attached to the inner tube 2 and the outer tube 3. By supporting the manifold 6 on a casing (not shown) of the CVD apparatus, the process tube 1 is in a vertically installed state.
[0012]
An exhaust port 7 is formed in a part of the side wall of the manifold 6, and the exhaust port 7 is connected to an exhaust device (not shown) so that the inside of the process tube 1 can be depressurized to a predetermined vacuum degree. Have been. The exhaust port 7 is in communication with an exhaust path 8 formed by a gap formed between the inner tube 2 and the outer tube 3. The exhaust path 8 is formed by a gap between the inner tube 2 and the outer tube 3. Has a circular ring shape with a constant width. Since the exhaust port 7 is opened in the manifold 6, the exhaust port 7 is in a state in which a cylindrical hollow body is formed and is disposed at a lower end portion of a vertically extending exhaust path 8.
[0013]
A seal cap 9 for closing the lower end opening is brought into contact with the manifold 6 from below in the vertical direction. The seal cap 9 is formed in a disk shape substantially equal to the outer diameter of the outer tube 3, and is configured to be vertically moved up and down by a boat elevator (not shown) installed vertically outside the process tube 1. ing. On the center line of the seal cap 9, a boat 11 for holding a wafer 10 as an object to be processed is vertically supported and supported. The boat 11 is provided with a pair of upper and lower end plates 12 and 13 and a plurality of holding members 14 vertically arranged between the both end plates 12 and 13. The holding grooves 15 are arranged at regular intervals in the longitudinal direction and are submerged so as to open opposite to each other. By inserting the circumferential edge of the wafer 10 between the holding grooves 15 of the same step of the plurality of holding members 14, the plurality of wafers 10 are held in a state of being aligned horizontally and centered with each other. A pair of upper and lower auxiliary end plates 16 and 17 are disposed between the boat 11 and the seal cap 9 and supported by a plurality of auxiliary holding members 18. A groove 19 is submerged.
[0014]
Outside the outer tube 3, a heater unit 20 for heating the inside of the process tube 1 uniformly or at a predetermined temperature distribution is provided concentrically so as to surround the outer tube 3, and the heater unit 20 is provided in the CVD apparatus. It is in a vertically installed state by being supported by the housing.
[0015]
At a position on the side wall of the inner tube 2 opposite to the exhaust port 7 by 180 degrees, a channel-shaped spare chamber 21 is formed so as to bulge outward in the radial direction and extend long in the vertical direction. An exhaust hole 25 is vertically elongated at a position on the side wall of the tube 2 opposite to the preliminary chamber 21 by 180 degrees, that is, at a position on the exhaust port 7 side. As shown in FIG. 2, a pair of gas introduction nozzles 22, 22 are arranged in the preliminary chamber 21 so as to extend in the vertical direction close to each other. As shown in FIG. 1, the gas inlet 23 of each gas inlet nozzle 22 penetrates the side wall of the manifold 6 radially outward and protrudes to the outside of the process tube 1. A source gas supply device, a nitrogen gas supply device, and the like (not shown) are connected to 23. In the pair of gas introduction nozzles 22, a plurality of sets of three sets of ejection ports 24 are opened in a vertical direction. The number of sets of the spouts 24 is equal to the number of wafers 10 held on the boat 11, and the height position of each set is the space between the upper and lower adjacent wafers 10 held on the boat 11. Are set to face each other. That is, the three ejection ports 24 a, 24 b, and 24 c of the gas introduction nozzle 22 are opened in a plane parallel to the main surface of the wafer 10. In the pair of gas introduction nozzles 22, the gas ejection direction of the center ejection port 24 a of the three ejection ports 24 is parallel to the line connecting the center of the wafer 10 and the exhaust hole 25. The ejection direction of the gas from the ejection ports 24b and 24c on both sides is set such that the elevation angle Θ with respect to the ejection direction of the center ejection port 24a as a reference line from the center of the gas introduction nozzle 22 is 30 degrees. It is set to be line symmetric.
[0016]
Next, a film forming method according to an embodiment of the present invention using the CVD apparatus having the above configuration will be described.
[0017]
In the wafer charging step, the wafers 10 are inserted into the boat 11 so as to engage with the holding grooves 15 of the holding member 14 at a plurality of locations where the circumferential edges of the wafers 10 face each other. It is loaded (charged) and held so as to be engaged with each holding groove 15 and to support its own weight. The plurality of wafers 10 are aligned in parallel and horizontally with their centers aligned in the charging state of the boat 11.
[0018]
In the boat loading step, the boat 11 in which a plurality of wafers 10 are aligned and held is loaded into the processing chamber 4 from the furnace port 5 of the inner tube 2 (boat loading) by the boat elevator so that the boat 11 is loaded. 4 as shown in FIG. In this state, the seal cap 9 seals the furnace port 5.
[0019]
Subsequently, in the depressurizing step, the inside of the process tube 1 is depressurized to a predetermined degree of vacuum (for example, 200 Pa) by the exhaust force acting on the exhaust port 7, and in the temperature increasing step, the inside of the process tube 1 is heated by the heater unit. 20, the temperature is raised to a predetermined temperature (for example, 400 ° C.).
[0020]
Next, in a film forming step, a predetermined source gas 30 is supplied to the gas introduction port 23 of the gas introduction nozzle 22 at normal pressure (atmospheric pressure), and flows through a pair of gas introduction nozzles 22 to form a plurality of sets of three gas supply nozzles. The jets 24 a, 24 b, and 24 c are introduced into the processing chamber 4 of the inner tube 2 in a controlled manner such that they are jetted at a high speed close to the speed of sound. For example, when doped polysilicon is diffused, monosilane (SiH ₄ ) and phosphine (PH ₃ ) are introduced into the processing chamber 4 as the source gas 30. The raw material gas 30 introduced into the processing chamber 4 flows out from an exhaust hole 25 formed in the side wall of the inner tube 2 in a vertically elongated shape into an exhaust passage 8 formed by a gap between the inner tube 2 and the outer tube 3. Air is exhausted from an exhaust port 7 opened in a manifold 6 located at the lower end of the tube 3.
[0021]
At this time, since the pair of gas introduction nozzles 22 and 22 and the exhaust hole 25 and the exhaust port 7 are arranged so as to face each other at an interval of 180 degrees, each pair of the pair of gas introduction nozzles 22 and 22 is arranged. The source gas 30 ejected from each of the three ejection ports 24 a, 24 b, and 24 c flows horizontally in the processing chamber 4 toward the exhaust hole 25 on the opposite side, and thus flows in parallel with each wafer 10. In addition, since the three spouts 24a, 24b, and 24c of each set are arranged so as to face each other between the vertically adjacent wafers 10, the source gas spouted from the spouts 24, respectively. Numerals 30 flow into each of the spaces between the vertically adjacent wafers 10, and flow reliably in parallel. A CVD film is deposited on the surface of the wafer 10 by the CVD reaction of the source gas 30 flowing in parallel in the space between the vertically adjacent wafers 10 while being in contact with the surface of the wafer 10. For example, when monosilane and phosphine are introduced, a doped polysilicon film is deposited on the wafer 10. At this time, since the source gas 30 is uniformly contacted over the entire surface of each wafer 10, the deposited state of the CVD film is uniform in both the film thickness and the film quality throughout the entire wafer 10.
[0022]
Further, in the present embodiment, the source gas 30 is ejected from each set of the ejection ports 24 of the gas introduction nozzle 22 at a high speed close to the sonic speed, so that the downstream pressure and the upstream pressure in the gas introduction nozzle 22 are increased. Is equal to or less than the critical pressure ratio, and a constant flow rate can always be generated regardless of fluctuations in the flow field on the downstream side. Therefore, it is necessary to uniformly control the gas flow rate above and below the gas introduction nozzle 22. Can be. As a result, the film thickness and the film quality formed on each wafer 10 of the group of wafers 10 held by the boat 11 become uniform over the entire length of the boat 11 in the group of wafers 10.
[0023]
After a desired CVD film (for example, a doped polysilicon film) is deposited, in a boat unloading step, the furnace port 5 is opened by lowering the seal cap 9 and the boat is held by the boat 11. Is carried out from the furnace port 5 to the outside of the process tube 1 (boat unloading).
[0024]
By the way, when the gas flow at the time of reaching a steady state when the gas is ejected from the ejection port of the gas introduction nozzle at a high speed close to the speed of sound was simulated, the streamlines shown in FIGS. 3 and 4 were obtained. Was done.
[0025]
Fig. 3 shows a conventional example in which the gas introduction nozzle is arranged so as to be in contact with the inner peripheral surface of the side wall of the inner tube, and has a single ejection port. It is observed that a strong large vortex is formed immediately after the ejection port. Is done. Most of the injected gas is returned to the vicinity of the ejection port again by the large vortex, and the flow on the wafer surface is not uniform. Although not shown, when observing a flow velocity contour diagram near the ejection port corresponding to the streamline in FIG. 3, the gas ejected at a high speed close to the sonic speed from the ejection port reached about 30 mm after reaching the wafer surface. , Where it was observed that it was already on the order of a few meters / second. Since the injected gas diffuses widely immediately after the injection port due to the decompression field, it is considered that the penetration force of the injection gas is significantly attenuated and the flow velocity becomes extremely slow. Since it is presumed that the influence of the large velocity gradient and the vortex is strongly received at the time of film formation, it is necessary to improve them.
[0026]
FIG. 4 shows the case of this embodiment in which strong turbulence can be prevented from occurring due to the large vortex near the ejection port in the result of FIG. Looking at the streamlines in FIG. 4, it is possible to observe that the gas flows to the exhaust holes without generating large turbulence on the wafer surface. This is considered for the following reasons. Since the flow rates of the pair of gas introduction nozzles 22 and 22 and the nozzle area of the gas introduction nozzles 22 are the same as those in FIG. 3, the flow rate from one gas introduction nozzle 22 is reduced by half. The momentum of gas per nozzle is halved. In addition, since the gas is dispersed and jetted from the set of jet ports 24a, 24b, and 24c into the inner tube 2 by the three gas inlet nozzles 22, 22, the gas is attenuated. The generation of a large vortex near the nozzle 22 is prevented. Further, the gas is discharged from a set of three jet ports 24a, 24b, 24c at a wide angle onto a plane parallel to the main surface of the wafer, so that the penetration force of gas to the exhaust port is reduced by the main surface of the wafer. Is widened on a plane parallel to the above, so that generation of a large vortex near the gas introduction nozzle 22 is prevented.
[0027]
The gas ejection directions of the gas outlets 24b and 24c on both sides are symmetrical with respect to the center of the gas introduction nozzle 22 as a starting point, and the elevation angle と し た with respect to the center of the gas outlet 24a as a reference line and an elevation angle Θ of 30 degrees. It is desirable that the optimum value be set according to conditions such as the interval between the pair of gas introduction nozzles 22 and the size of the preliminary chamber 21 in the circumferential and radial directions.
[0028]
According to the embodiment, the following effects can be obtained.
[0029]
1) A gas introduction nozzle is provided in a spare chamber formed on the side wall of the inner tube, and the source gas is ejected from the ejection port of the gas introduction nozzle into the processing chamber so that the penetration force of the injected source gas reaches the wafer. This can prevent the generation of a large velocity gradient or a vortex on the wafer surface, so that the contact time of the source gas with the wafer can be prevented from being prolonged.
[0030]
2) By preventing the contact time of the raw material gas with the wafer from being prolonged, for example, when a polysilicon film is formed, the passage time of monosilane in a high temperature region is prolonged, and the decomposition reaction in the gas phase is performed. Excessively progresses, and polysilicon is deposited in a powdery form and adheres to the surface of the wafer, thereby preventing the quality of the polysilicon film from being deteriorated or causing particles to be generated. Therefore, a high-quality polysilicon film can be formed, and a decrease in the yield of the film forming process can be prevented.
[0031]
3) A pair of gas introduction nozzles is provided in the spare chamber, and a pair of gas introduction nozzles is provided with a pair of gas ejection nozzles, so that the gas is parallel from the three gas ejection nozzles to the main surface of the wafer. In this state, a large-volume vortex causes a strong turbulence to be more reliably prevented, and a higher-quality polysilicon film can be formed. A decrease in the yield of the film process can be reliably prevented.
[0032]
4) Since the source gas is ejected from the ejection port of the gas introduction nozzle at a high speed close to the speed of sound, the flow rate of the source gas can be controlled uniformly above and below the gas introduction nozzle. The thickness and quality of the CVD film formed on each wafer can be made uniform over the entire length of the wafer group.
[0033]
5) By disposing the gas introduction nozzle and the exhaust hole so as to face each other at an angle of 180 degrees, and by arranging the plurality of ejection ports so as to face between vertically adjacent wafers, respectively, Since the raw material gas ejected from the outlet can flow in parallel in the space between the vertically adjacent wafers so as to be uniformly contacted over the entire surface of each wafer, the film thickness of the CVD film over the entire surface of each wafer And the film quality can be formed uniformly.
[0034]
6) By making the thickness and quality of the CVD film in the wafer surface and in the wafer group as a whole uniform, the thickness and quality of the CVD film in one process can be made uniform. The quality and reliability of the apparatus and the film forming process can be improved.
[0035]
Note that the present invention is not limited to the above-described embodiment, and it goes without saying that various changes can be made without departing from the gist of the present invention.
[0036]
For example, as shown in FIG. 5A, not only the corner (edge) 26 is left at the opening edge of the ejection port of the gas introduction nozzle, but also as shown in FIG. 5B. The R-chamfered portion 27 may be formed as described above, or the approximated curved surface portion 28 may be formed as shown in FIG. As a result, the turbulence of the gas flow is further reduced. Furthermore, the adhered film is easily peeled off at the corners 26, which causes particles. However, by forming the R chamfered portion 27 or the approximate curved surface portion 28, the occurrence of this peeling phenomenon can be prevented. That is, since the cause of the generation of particles can be further prevented, a high-quality polysilicon film can be formed, and a decrease in the yield of the film forming process can be prevented.
[0037]
For example, the number of one set of ejection ports in the same plane of the gas introduction nozzle is not limited to three, and may be two or four or more. The number of gas introduction nozzles is not limited to one pair, and may be one or three or more.
[0038]
The number of sets of ejection ports opened in the gas introduction nozzle is not limited to be equal to the number of wafers to be processed, but can be increased or decreased according to the number of wafers to be processed. For example, the plurality of ejection ports in each set are not limited to being arranged opposite each other between vertically adjacent wafers, but may be arranged every two or three wafers.
[0039]
The exhaust hole formed in the side wall of the inner tube is not limited to a series of long holes, and may be formed in a plurality of long holes, a circular hole, a polygonal hole, or the like. May be.
[0040]
In the above-described embodiment, the case where the processing is performed on the wafer 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.
[0041]
In the above embodiment, the deposition of the doped polysilicon film has been described. However, the deposition method according to the present invention can be applied to the entire deposition method of a CVD film such as a doped polysilicon oxide film or a silicon nitride film. it can. Further, the method for manufacturing a semiconductor device according to the present invention can be applied to all methods for manufacturing a semiconductor device, such as an oxide film forming method and a diffusion method.
[0042]
In the above embodiment, the case where the present invention is applied to a batch type vertical hot wall type reduced pressure CVD apparatus is described. However, the present invention is not limited to this, and a horizontal hot wall type reduced pressure CVD apparatus, an oxide film forming apparatus, a diffusion apparatus and other heat treatments are used. The present invention can be applied to all substrate processing apparatuses such as apparatuses.
[0043]
【The invention's effect】
As described above, according to the present invention, it is possible to prevent the gas ejected from the ejection port from generating a large vortex, thereby improving the uniformity of the film thickness and film quality of the wafer and reducing particles, Processing quality and reliability can be increased.
[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 plan sectional view in which a heater unit is omitted.
FIG. 3 is a streamline diagram showing a case in which the gas introduction nozzle has one ejection port.
FIG. 4 is a streamline diagram showing a case where there are three jet ports according to the present embodiment.
FIGS. 5A and 5B are cross-sectional views showing the shape of an opening edge portion of an ejection port, where FIG. 5A is an ejection port having a corner, FIG. 5B is an ejection port having an R chamfer, and FIG. Are shown, respectively.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Process tube, 2 ... Inner tube, 3 ... Outer tube, 4 ... Processing chamber, 5 ... Furnace port, 6 ... Manifold, 7 ... Exhaust port, 8 ... Exhaust path, 9 ... Seal cap, 10 ... Wafer (substrate) , 11 boat, 12, 13 end plate, 14 holding member, 15 holding groove, 16, 17 auxiliary end plate, 18 auxiliary holding member, 19 holding groove, 20 heater unit, 21 spare chamber , 22 ... gas introduction nozzle, 23 ... gas introduction port, 24, 24a, 24b, 24c ... injection port, 25 ... exhaust hole, 26 ... corner, 27 ... R chamfer, 28 ... approximate curved surface, 30 ... material gas.

Claims (2)

A process tube including an inner tube into which a substrate is loaded and an outer tube surrounding the inner tube, a gas introduction nozzle for introducing a gas into the inner tube, and an exhaust port for exhausting the inside of the process tube. Substrate processing equipment,
The substrate processing apparatus according to claim 1, wherein the gas introduction nozzle has at least a plurality of ejection ports formed in a plane parallel to a main surface of the substrate. Loading a boat holding a plurality of substrates into the processing chamber, introducing a gas into an introduction nozzle, and introducing the plurality of substrates into a plane parallel to a main surface of the substrate. The step of passing the gas through an ejection port, the step of treating the substrate with the gas, the step of passing the gas through an exhaust port for exhausting the processing chamber, the step of stopping the supply of the gas, Carrying out the boat from a processing chamber.

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