JP2008028409A - Heat treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat treatment apparatus capable of increasing a heat treatment rate such as a film forming rate without deteriorating heat treatment quality. <P>SOLUTION: The heat treatment apparatus for directing a process gas toward a work to be processed W and performing a predetermined heat treatment of the work to be processed comprises: a work supporter 26 for arranging a plurality of the works to be processed with a predetermined pitch and supporting them; a process vessel 4 capable of being vacuumed to house the works to be processed; a gas guiding inlet 38 with a small conductance, which is formed along the arrangement direction of the works to be processed so as to face one sides of the plurality of the works to be processed; a gas suction inlet 40 with a large conductance, which is formed along the arrangement direction of the works to be processed so as to face the other sides of the plurality of the works to be processed; and a load/unload mechanism 28 which loads/unloads the work supporter into/from the process vessel. This increases the heat treatment rate such as a film forming rate without deteriorating the heat treatment quality. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heat treatment method and a heat treatment apparatus for performing a heat treatment such as film deposition on an object to be processed such as a semiconductor wafer.

In general, when performing various heat treatments on a semiconductor wafer or the like, for example, film deposition, a batch-type heat treatment apparatus is mainly used because a large number of semiconductor wafers can be formed at once. .
In this heat treatment apparatus, a large number of semiconductor wafers of about 70 to 150 are supported in multiple stages on a quartz wafer boat at a predetermined pitch, and are accommodated in a cylindrical vertical processing container. Then, a predetermined heat treatment such as film formation is performed by flowing a processing gas upward or downward in the container. Here, a general batch-type heat treatment apparatus will be described. FIG. 21 is a schematic configuration diagram showing a general batch-type heat treatment apparatus. This batch-type heat treatment apparatus 102 includes a processing vessel 108 having a double-pipe structure composed of an inner cylinder 104 and an outer cylinder 106. The processing space S in the cylinder 104 accommodates a wafer boat 110 which can be inserted and removed from below, and a large number of, for example, about 150 product wafers W are loaded in a full state at a predetermined pitch. Then, a predetermined heat treatment, for example, CVD (Chemical Vapor Deposition) film formation is performed.
Various gases such as a film forming gas are introduced from the lower part of the processing vessel 108 and rise while reacting in the processing space S, which is a high temperature region in the inner cylinder 104, and then folded downward to be connected to the inner cylinder 104 and the outer cylinder 104. The gap with the cylinder 106 is lowered and discharged from the exhaust port 112 to the outside. A heater (not shown) divided into zones is provided on the outer periphery of the processing container. During this heat treatment, the semiconductor wafer is maintained at a predetermined process temperature, and the processing chamber is also maintained at a predetermined process pressure. A part of the processing gas introduced into the processing container rises along the peripheral direction of the wafer along the arrangement direction of the wafers, and partly flows between the wafers to cause a thermal decomposition reaction, thereby depositing a film on the wafer surface.

By the way, taking film formation processing as an example, from the viewpoint of improving productivity, it is possible to form a film having a good quality at a high film formation rate while maintaining high uniformity between wafer surfaces and in-plane. is necessary.
In order to increase the film formation rate of various films, it is only necessary to increase the parameters such as the supply amount of process gas, process pressure, process temperature, etc. to promote the gas reaction. However, there is a limit to the value of each parameter described above. For example, when a polysilicon film or the like is formed using silane gas (SiH ₄ ) as a processing gas, it is generally impossible to form a film with good quality at a process pressure exceeding 1.5 Torr. For example, when the pressure exceeds 1.5 Torr, the passage time of the silane gas in the high temperature region which is the processing space S becomes long, and the decomposition reaction in the gas phase is excessively promoted.

When the gas phase reaction is excessively promoted in this way, silicon is powdered and deposited and adheres to the wafer surface, which not only deteriorates the quality of the film but also causes generation of particles. Therefore, in order to prevent such a gas phase reaction from occurring excessively and to perform a film forming reaction mainly including an interface reaction in which a decomposition reaction proceeds on the wafer surface, the process pressure is set to 1.5 Torr or less as described above. For this reason, the film forming rate was about 15 Å / min at the maximum.
The present invention has been devised to pay attention to the above problems and to effectively solve them. An object of the present invention is to provide a heat treatment method and a heat treatment apparatus capable of increasing a heat treatment speed such as a film forming rate without deteriorating the quality of the heat treatment.

The inventors of the present invention forcibly pass the processing gas between the semiconductor wafers arranged in a large number of sheets, thereby reducing the residence time of the processing gas in this portion, thereby suppressing the gas phase reaction and increasing the process. The present invention has been achieved by obtaining the knowledge that the film formation rate can be improved while suppressing the film caused by the gas phase reaction even under pressure.
In the invention defined in claim 1, when a predetermined heat treatment is performed by flowing a processing gas to a plurality of objects to be processed arranged at a predetermined pitch, one end side of the plurality of objects to be processed arranged is faced. Of the conductance formed along the arrangement direction of the objects to be processed so as to face the other end side of the plurality of objects to be processed from a gas inlet having a small conductance formed along the arrangement direction of the objects to be processed. The processing gas is caused to flow toward the large gas suction port so that the processing gas passes between the objects to be processed.

According to this, since the processing gas flows from the gas introduction port having a small conductance toward the gas suction port having a large conductance, the processing gas is forced to pass between the objects to be processed. For this reason, the residence time of the processing gas passing between the objects to be processed is shortened by that amount. Therefore, for example, in the film forming process, the gas phase reaction is suppressed even when the process pressure is increased, and the film is formed by the interfacial reaction. It becomes possible to perform film deposition at a high film formation rate.
The invention defined in claim 2 is an apparatus invention for carrying out the above-described method invention, wherein a plurality of objects to be processed are arranged at a predetermined pitch in a heat treatment apparatus that performs a predetermined heat treatment by flowing a processing gas to the object to be processed. Processing object support tools arranged and supported, a processing container configured to be evacuated to accommodate the processing objects, and an array of the processing objects so as to face one end side of the plurality of processing objects A gas introduction port with a small conductance formed along the direction, a gas suction port with a large conductance formed along the arrangement direction of the objects to be processed so as to face the other end of the plurality of objects to be processed, The processing object support is configured to include an insertion / removal mechanism for loading and unloading into the processing container.

In this case, for example, the processing container has a double pipe structure of an inner cylinder and an outer cylinder provided so as to surround the inner cylinder, and the gas inlet is formed along one side of the inner cylinder. In addition, the gas suction port may be formed along the other side of the inner cylinder.
The gas inlet may be provided along the side wall of the processing container, and the gas suction port may be provided by forming the side wall of the processing container to protrude outward. Furthermore, the gas inlet may be divided and arranged for each of a plurality of zones along the arrangement direction of the objects to be processed.
According to this, it becomes possible to introduce process gas substantially equally from each gas inlet port dividedly arranged in the arrangement direction of the objects to be processed.
The gas inlet may be divided into a plurality of portions along the circumferential direction of the object to be processed. According to this, it becomes possible to supply process gas uniformly to each to-be-processed object in plane.

  Further, the object support tool may include two plate members each having an arcuate cross section having a predetermined thickness and having a support portion that contacts and supports the object to be processed. Good. According to this, the plate member can act as a baffle plate to prevent the processing gas from flowing around the outer periphery of the object to be processed and guide it to flow between the objects to be processed. For example, the film forming rate can be improved.

According to the heat treatment method and heat treatment apparatus of the present invention, the following excellent operational effects can be exhibited.
According to the invention defined in claims 1 to 4, since the processing gas is caused to flow from the gas introduction port having a small conductance toward the gas suction port having a large conductance, the processing gas can be efficiently processed between the objects to be processed. Can flow. Accordingly, the heat treatment with the processing gas is promoted to increase the heat treatment speed. For example, in the case of film formation, a film having good quality can be formed at a high film formation rate.
According to the invention defined in claim 5, since the gas inlets are dispersed in the arrangement direction of the objects to be processed and arranged for each zone so that they can be independently controlled, the processing gas is supplied uniformly in the arrangement direction. The uniformity between the surfaces of the heat treatment can be improved.
According to the invention defined in claim 6, since the gas inlets are arranged in a distributed manner along the circumferential direction of the object to be processed, the processing gas can be supplied uniformly within the surface of the object to be processed, and heat treatment The in-plane uniformity can be improved.
According to the invention defined in claim 7, the plate member acts as a baffle plate to prevent the processing gas from flowing into the outer periphery of the object to be processed so that more processing gas flows between the objects to be processed. Therefore, the film formation rate such as heat treatment can be further improved accordingly.

Hereinafter, an embodiment of a heat treatment method and a heat treatment apparatus according to the present invention will be described in detail with reference to the accompanying drawings.
1 is a block diagram showing a heat treatment apparatus according to the first invention, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 3 is a perspective view showing an inner cylinder in FIG. Here, a film forming process for depositing a silicon film as the heat treatment will be described as an example.
As shown in the figure, this heat treatment apparatus 2 has a cylindrical processing container 4 made of, for example, quartz, and this processing container 4 covers the inner cylinder 6 which is a feature of the first invention and the periphery thereof. The outer cylinder 8 is mainly configured. A heater (not shown) is provided on the outer periphery of the processing container 4. The lower end of the outer cylinder 8 is airtightly joined to, for example, a stainless steel manifold 10 through a seal member 12 such as an O-ring, and thereby a ring-shaped support portion provided so as to protrude inward. 14, the lower end of the inner cylinder 6 is placed and supported.

The manifold 10 is provided with a gas introduction nozzle 16 bent in an L shape so as to pass therethrough. For example, silane, Si ₂ H ₆ , B ₂ H ₆ , AsH ₃ or the like is formed as a processing gas. Gas or other necessary gas can be introduced.
Further, a cap 20 is attached to the lower end opening of the manifold 10 through a sealing member 18 such as an O-ring so as to be airtightly detachable. In the center of the cap 20, a rotating shaft 24 supporting a quartz heat insulating cylinder 22 is inserted at the upper end thereof. In the heat insulating cylinder 22, for example, a quartz wafer boat 26 is used as an object supporting tool. It is placed. Then, the wafers 26 are supported by, for example, support grooves (not shown) of the four support posts 26A, and the semiconductor wafers W as the objects to be processed are supported in multiple stages at a predetermined pitch.
The lower end of the rotary shaft 24 is attached to an arm 28A of a boat elevator 28 that can be raised and lowered, for example, as an insertion / removal mechanism. By driving the boat elevator 28 up and down, the wafer boat 26 is processed. The container 4 can be loaded and unloaded. In addition, an exhaust port 30 is formed at the upper end of the outer cylinder 8, and a vacuum exhaust system having a vacuum pump or a detoxification unit (not shown) connected to the exhaust port 30 in the middle. The inside of the processing container 4 can be vacuumed.

On the other hand, as shown in FIGS. 2 and 3, the cylindrical inner cylinder 6 which is a feature of the first invention has a thick side wall 32 in which approximately half of the cross section of the side wall is made thick in the height direction. The remaining half is a thin-walled side wall 34. Then, by forming a concave groove 36 along the height direction at substantially the center of the thick side wall 32, a vertically long gas conductance port 38 having a small conductance opened to the inside is formed. It is composed. That is, the gas introduction port 38 faces one end side of the wafer W. The tip 16A of the L-shaped gas introduction nozzle 16 is positioned at the lower end opening of the groove 36, and the processing gas or the like is guided into the gas introduction port 38.
Here, for example, an 8-inch wafer is used as the wafer W, the distance between the wafers W adjacent to each other in the vertical direction is set to about 6 mm, and the vertical L1 of the groove 36 is about 5 mm to 30 mm, and the horizontal L2 is set. Is set to about 5 mm to 30 mm. The distance L3 between the inner surface of the thick wall 32 and the peripheral edge of the wafer W is about 3 mm to 20 mm, and the exhaust conductance of the gas inlet 38 is set small as described above.

  On the other hand, the thin-wall side wall 34 side, which is the other end side of the wafer W, is configured as a gas suction port 40 having a large conductance as a whole. Suction is made through the mouth 40. At this time, the distance L4 between the inner surface of the thin side wall 34 and the peripheral portion of the wafer W is set to about 20 mm to 50 mm, and the exhaust conductance of the gas suction port 40 is set large as described above. A ceiling plate 44 having a gas outlet 42 having the same cross-sectional shape as the gas suction port 40 is provided at the ceiling portion of the inner cylinder 6.

Next, the operation of the first invention apparatus configured as described above will be described.
First, in a state where unprocessed semiconductor wafers W are placed in multiple stages on the wafer boat 26, they are lifted from below the processing container 4 by the boat elevator 28 and loaded into the preheated inner cylinder 6. The inside of the processing container 4 is sealed by closing the opening with the cap 20. Here, 40 wafers W are mounted.
Next, when the power supplied to a heater (not shown) is increased and the wafer W is heated to a process temperature, for example, about 530 ° C., silane, N ₂ gas, and the like whose flow rate is controlled from the gas introduction nozzle 16 are processed into the processing container. At the same time, the inside of the processing container 4 is evacuated from the exhaust port 30 to maintain the inside at a predetermined process pressure, and a film forming process is performed. Specifically, the processing gas released from the tip 16A of the gas introduction nozzle 16 flows out in the horizontal direction, that is, in the horizontal direction while rising in the gas introduction port 38 formed in the inner cylinder 6, and between each wafer W. It decomposes while passing through and flows into the gas suction port 40 located on the opposite side. Then, the reacted processing gas that has flowed into the gas suction port 40 rises and is discharged from the processing container 4 through the gas outlet 42 and the exhaust port 30.

When the processing gas passes between the wafers, silane is decomposed and a film is formed on the wafer surface. Here, the gas introduction port 38 has a gap L3 between the inner surface of the thick side wall 32 and the peripheral edge of the wafer. The exhaust conductance of the gas suction port 40 is set to be small by bringing the both into close proximity with each other, while the gas suction port 40 increases the distance L4 between the inner surface of the thin side wall 34 and the peripheral edge of the wafer. Since the exhaust conductance is set to be large by being separated, a large differential pressure is generated between the gas introduction port 38 and the gas suction port 40, so that the processing gas does not bypass the outer periphery of the wafer W. It will actively flow in between and quickly pass over the wafer surface.
As a result, the processing gas efficiently flows between the wafers, and the residence time here is reduced. Accordingly, the time during which the processing gas is exposed to high temperature is reduced, and the gas phase reaction is suppressed. Film formation is promoted. Therefore, even when the flow rate of the processing gas is increased and the process pressure is higher than that in the conventional method (up to about 1.5 Torr), a film having a good quality is deposited mainly by the film by the interface reaction. In addition, the film formation rate can be greatly improved, and productivity can be improved.

Here, when the above effect is considered with reference to the decomposition reaction of silane, silane (SiH ₄ ) is converted into Si crystal through an intermediate product mainly composed of silylene (SiH ₂ ) due to thermal decomposition. The silane and silylene concentrations in between are as shown in FIG. That is, thermal decomposition starts simultaneously with the introduction of silane, and the silane concentration gradually decreases, while the silylene concentration gradually increases, and both reach saturation after a certain period of time.
Here, in the conventional method or apparatus, since the flow of the processing gas between the wafers is very slow, the processing gas between the wafers is in the state indicated by the region A, the concentration of silylene is considerably high, and the silylene is crystallized. The step coverage that determines the quality of the Si crystal film is not good. Therefore, in order to suppress the vapor phase reaction and suppress the silylene from being crystallized to Si, the process pressure had to be kept low, but the processing gas flowing between the wafers as in the method or apparatus of the present invention. By increasing this speed and shortening this transit time, the processing gas between the wafers is in the state indicated by region B, and the concentration of silylene is considerably reduced. Therefore, even if the process pressure is increased by increasing the supply amount of the processing gas, the concentration of silylene does not increase so much, that is, the gas phase reaction is not promoted, and the quality with mainly the interface reaction as described above is good. The film can be deposited at a high film formation rate.

Moreover, since the simulation of the processing gas velocity on the wafer surface in the case of the conventional apparatus and the case of the apparatus of the present invention was performed, the results are compared.
FIG. 5 is a diagram showing a simulation of the flow velocity distribution of the processing gas on the semiconductor wafer in the case of the conventional apparatus, FIG. 6 is a diagram showing a simulation result of the first invention apparatus, and FIG. 6 (A) is the first invention. A simulation model of the apparatus is shown, and FIG. 6B shows a simulation of the flow velocity distribution of the processing gas on the semiconductor wafer, both of which are described for a half region. The process conditions are the same, the process temperature is 530 ° C., the process pressure is 1.0 Torr, and the flow rate of the processing gas is 500 sccm. In addition, the length of the arrow in a figure represents the speed | velocity | rate of process gas.
As is clear from this figure, in the case of the conventional apparatus shown in FIG. 5, the arrows are almost like dots, and the processing gas velocity is very slow, whereas the first invention apparatus shown in FIG. In this case, the arrow is considerably long, and it is found that the speed of the processing gas is much faster, for example, 0.04 m / sec.

Moreover, since the quality of the film quality of the conventional apparatus and the first invention apparatus and the pressure dependency of the film forming rate were actually obtained, the results will be described with reference to FIG. Here, the film quality when the process pressure was set to 1.0 Torr and 3.0 Torr was examined for the conventional apparatus and the first invention apparatus, respectively. Other process conditions are the same, the process temperature is 530 ° C., and the silane flow rate is 500 sccm. In FIG. 7, the hatched portion indicates a SiH ₄ layer (Si crystal layer crystallized from silane) having a good quality, and the white portion indicates a SiH ₂ layer (Si crystal layer crystallized from silylene) having a poor quality. The numerical values on each graph represent the deposition contribution rate of the SiH ₂ layer with respect to the overall deposition rate.
As is apparent from this figure, when the process pressure is low at 1.0 Torr, both the conventional apparatus and the first invention apparatus have a low film formation rate of about 15 Å / min, and there is almost no difference. On the other hand, when the process pressure is 3.0 Torr, the film formation rates of the conventional apparatus and the first invention apparatus are 36 Å / min and 28 Å / min, respectively, which are significantly increased. In this case, the SiH ₂ layer having a higher film formation rate but inferior quality contributes 36.5% in the case of the conventional apparatus, whereas it is 24.3% in the case of the first invention apparatus. As a result, it was found that the film quality of the first invention apparatus was better.

Next, the dependence of the film quality on the processing gas flow rate was examined using the first invention apparatus, and the result will be described with reference to FIG.
Here, using the apparatus of the first invention, the process pressure was fixed at 530 ° C. and the process pressure at 3 Torr, and the silane flow rate was changed to 500 sccm, 1000 sccm, and 1500 sccm.
As is apparent from this graph, as the silane flow rate is increased, the film formation rate gradually changes, but at the same time, the contribution ratio of the poor quality SiH ₂ layer to the overall film formation rate is 24. There is a significant decrease in the order of 3%, 14.9% and 10.1%. Therefore, it can be seen that increasing the flow rate of silane is preferable because a high quality film can be obtained by that amount although the overall film formation rate is slightly reduced.

Next, since the process pressure dependence of the silylene concentration with respect to the silane flow rate was examined, the examination result will be described with reference to FIG.
Here, the apparatus of the first invention was used, the process temperature was fixed at 530 ° C., and the flow rate of silane was changed. Further, three types of process pressures of 3 Torr, 4.5 Torr, and 7 Torr were examined. In the graph, the film formation rate is also shown, which is considerably higher than the conventional ratio.
As is clear from this graph, the higher the silane flow rate, the lower the concentration of silylene, which is preferable, and the higher the process pressure, the higher the film formation rate. Therefore, in order to suppress the silylene concentration below an allowable value, for example, 10.5% (this value will be described later), the silane flow rate is about 1700 sccm or more when the process pressure is 3 Torr, and when the process pressure is 4.5 Torr. It can be seen that it may be set to about 2700 sccm or more and 4100 sccm or more when the process pressure is 7 Torr.

The reason why the allowable value of the silylene concentration is 10.5% or less is that the step coverage is 97% based on the relationship between the silylene concentration and the step coverage (hole diameter: 0.4 μm, depth: 1 μm) shown in FIG. This is because the silylene concentration needs to be 10.5% or less in order to set the above.
The dimensions of the members of the first invention apparatus described above, the shape of the gas inlet port 38, the shape of the gas suction port 40, etc. are merely examples, and are not limited thereto. For example, a plurality of gas inlets 38 may be formed in the thick side wall 32, and the length of the thick side wall 32 in the circumferential direction is further increased to increase the length of the gas suction port 40 in the circumferential direction. May be shortened.

In the first invention apparatus described above, the wafer boat 26 is a conventional one, and the processing vessel 4 is a double-pipe structure, and the shape of the inner cylinder 6 is devised to provide a gas introduction port 38. However, the present invention is not limited to this, and a processing vessel is formed as a single tube structure as in the second invention apparatus shown below, and a gas introduction port and a gas suction port are formed therein, and a wafer is further formed. By changing the shape of the boat, the processing gas that escapes to the outer periphery of the wafer may be suppressed, and the processing gas may be efficiently passed between the wafers.
FIG. 11 is a block diagram showing such a heat treatment apparatus of the second invention, FIG. 12 is a cross-sectional view taken along the line BB in FIG. 11, and FIG. 13 is a schematic configuration showing a wafer boat which is a workpiece support tool. 14 is a partial cross-sectional perspective view of the wafer boat shown in FIG. 13, FIG. 15 is a partial cross-sectional perspective view showing a processing container, and FIG. 16 is a view showing a processing gas supply system. The same parts as those of the first invention apparatus described above are denoted by the same reference numerals and description thereof is omitted.

As shown in the figure, in this heat treatment apparatus 50, the processing vessel 52 has a single tube structure as described above, and an exhaust port 54 for evacuation is provided at the bottom of the side wall of the vessel. Then, an L-shaped gas introduction nozzle 16 is provided through the manifold 10 in the same manner as in the first invention apparatus, and a gas pipe 56 is connected to this to supply various required gases such as processing gas. It comes to supply. Although one nozzle 16 is shown in the illustrated example, a plurality of nozzles 16 are actually provided.
The processing vessel 52 is provided with a gas conductance port 58 with a small conductance on one side wall (inner wall), and a gas with a large conductance is formed on the opposite side by projecting the side wall partially in a convex shape. A suction port 60 is provided. Specifically, as shown in FIG. 15, a total of nine ejection slits 62A to 62C, 64A, in which three gas inlets 58 are arranged on the side wall of the processing vessel 52 in the height direction and in the circumferential direction, respectively, are provided. -64C, 66A-66C, and the arrangement position in the height direction is slightly shifted in the circumferential direction. Therefore, the ejection slit is divided into three zones in the height direction of the container.

Each of the ejection slits 62A to 62C, 64A to 64C, 66A to 66C passes through the side wall, and a quartz passage forming member is formed along the height direction on the outer peripheral surface of the side wall corresponding to the slit. 68 is joined by welding or the like. Each passage forming member 68 has three passage grooves 70A, 70B, and 70C having different lengths corresponding to the height levels of the ejection slits 62A to 62C, 64A to 64C, and 66A to 66C that are different in the height direction. The passage forming member 68 is joined to the outer peripheral surface of the processing vessel 68 so that the passage slits 70A, 70B, 70C and the corresponding ejection slits at the height level communicate with each other. The gas introduction nozzles 16 are provided in a number corresponding to the number of slits. Here, if the length of the effective portion of the processing container 52 is 900 mm, the length of each slit is set to about 300 mm and the width is set to about 10 mm, and the vertical and horizontal cross-sectional shapes of the passage grooves 70A to 70C are both 10 mm. Degree.
The gas supply system to each of the ejection slits 62A to 62C, 64A to 64C, 66A to 66C is shown in FIG. 16, and the ejection slits arranged in the circumferential direction are connected in common. In the middle of the gas pipe 56 connected for each zone, a flow controller 72 such as a mass flow controller that can be individually controlled and an on-off valve 74 are interposed, and then connected to the processing gas source 76 in common. Yes.

On the other hand, as shown in FIGS. 13 and 14, the wafer boat 80 as a workpiece support tool is configured by joining two plate members 86 having a circular arc cross section between a top plate 82 and a bottom plate 84. Has been. Two support protrusions 88 are formed on the inner surface of the plate member 86 as support portions for supporting the peripheral edge of the lower surface of the wafer W. For example, 90 to 100 wafers W can be formed at a predetermined pitch. It can be supported in multiple stages. Note that a support groove may be formed instead of the support protrusion 28. As shown in FIG. 12, the two plate members 86 are separated by a distance corresponding to the opening width L <b> 8 of the gas suction port 60 and cover a substantially semicircle of the cross section of the wafer boat 80. Then, by setting the thickness L6 of the plate member 86 to be considerably thick, for example, about 5 to 7 mm, the distance L7 between the plate member 86 and the inner wall of the container is very narrow, for example, within a range of about 2 to 5 mm. It is made to become. Thereby, the amount of the processing gas that bypasses the outer periphery of the wafer W is suppressed as much as possible. Further, the front end 86A of the plate member 86 is a tapered surface inclined toward the wafer center along the gas flow direction, so that the processing gas to be detoured to the outer periphery of the wafer can be efficiently taken into the wafer surface. It has become.
When processing an 8-inch wafer, the cross-sectional width L8 of the gas suction port 60 is about 50 to 100 mm, and the depth L9 is about 25 to 30 mm. However, the present invention is not limited to this value.

Next, a film forming method using the second invention apparatus configured as described above will be described with reference to FIGS. 17 to 19 are diagrams schematically showing the flow of the processing gas in the longitudinal section and the transverse section of the lower, middle, and upper sections of the heat treatment apparatus, respectively.
As shown in FIG. 11, the processing gas supplied from the processing gas source 76 (see FIG. 16) during film formation is appropriately flow-controlled for each zone, and the corresponding passage grooves 70 </ b> A to 70 </ b> C via the nozzles 16. (Refer to FIG. 15), rises in the groove, and is discharged into the processing container 52 from the ejection slits 62 </ b> A to 62 </ b> C, 64 </ b> A to 64 </ b> C, and 66 </ b> A to 66 </ b> C constituting the gas introduction port 58. The discharged processing gas passes between the wafers W and flows into the gas suction port 60, flows down, and is discharged from the exhaust port 54 to the outside of the container.

Here, as in the first invention device, the gas inlet 58 has a small exhaust conductance, while the gas suction port 60 has a large exhaust conductance. A film is formed by thermal decomposition of silane while the gas efficiently flows between the wafers.
In particular, in the second invention apparatus, the two plate members 86 forming the wafer boat 80 are accommodated in a state of being very close to the inner wall of the container, so that this acts like a baffle plate against the processing gas. Then, the flow of the processing gas that tries to flow around the outer periphery of the wafer is blocked and guided to the inside of the wafer surface. Further, since the tip 86A of the plate member 86 also has a tapered surface, it acts to guide the processing gas that is about to flow to the outer periphery of the wafer further to the inside of the wafer surface. Therefore, as compared with the case of the first invention apparatus, more processing gas can be flowed between the wafer surfaces, so that the processing gas can be used effectively, and the flow rate of the supplied processing gas can be reduced accordingly.

  Further, as shown in FIGS. 17 to 19, here, the processing gas is divided into three zones in the height direction of the processing vessel 52 and further divided into three in the circumferential direction to supply the processing gas. Therefore, since the processing gas can be supplied substantially uniformly on the wafer surface, for example, the in-plane and inter-surface uniformity of the film can be kept high. Since the evaluation at this time was performed by simulation, the result is shown in FIG. FIG. 20A shows a simulation model in the case of the second invention apparatus as described above, and FIG. 20B shows a simulation of the flow velocity distribution of the processing gas therein. In this case, similarly to the case shown in FIG. 6, the length of the arrow in the drawing represents the speed of the processing gas. In the case of the first invention apparatus shown in FIG. 6, a considerable amount of processing gas flows densely between the wafer outer periphery and the container inner surface. In the case of the second invention apparatus shown in FIG. The amount of processing gas that bypasses the wafer outer peripheral side by the plate member 86 is very small, so that a large amount of gas flows on the wafer surface and the flow velocity is high, and it is found that the processing gas can be used more effectively. . For example, here, the flow velocity is about 0.15 m / sec, which is considerably faster than 0.04 m / sec of the first invention apparatus shown in FIG. 6, and the required gas flow rate is reduced to about 1/4. Is possible.

In the second invention apparatus, three slits are provided in each of the height direction and the circumferential direction, but the number of slits is not limited to this.
Further, the heat treatment is not limited to the film forming process of a polysilicon film, an amorphous film, or other film types, and it is needless to say that the heat treatment can be applied to other heat treatments such as an oxidation diffusion process and an annealing process.
Furthermore, the object to be processed is not limited to a semiconductor wafer, but can also be applied to an LCD substrate, a glass substrate, or the like.

It is a block diagram which shows the heat processing apparatus of 1st invention. It is an AA arrow directional cross-sectional view in FIG. It is a perspective view which shows the inner cylinder in FIG. It is a figure which shows the density | concentration of the silane and silylene between semiconductor wafers. It is a figure which shows the simulation of the flow velocity distribution of the process gas on the semiconductor wafer in the case of the conventional apparatus. It is a figure which shows the simulation in the case of the 1st invention apparatus, and the flow velocity distribution of the process gas on a semiconductor wafer. It is a figure which shows the pressure dependence of the film quality of the conventional apparatus and 1st invention apparatus, and the film-forming rate. It is a figure which shows the dependence of the film quality with respect to process gas flow volume using a 1st invention apparatus. It is a figure which shows the process pressure dependence of the silylene concentration with respect to a silane flow rate. It is a figure which shows the relationship between a silylene density | concentration and step coverage. It is a block diagram which shows the heat processing apparatus of 2nd invention. It is a BB arrow directional cross-sectional view in FIG. It is a schematic block diagram which shows the wafer boat which is a to-be-processed object support tool. FIG. 14 is a partial cross-sectional perspective view of the wafer boat shown in FIG. 13. It is a fragmentary sectional perspective view which shows a processing container. It is a figure which shows the supply system of a process gas. It is a figure which shows typically the flow of the process gas in the heat processing apparatus of 2nd invention. It is a figure which shows typically the flow of the process gas in the heat processing apparatus of 2nd invention. It is a figure which shows typically the flow of the process gas in the heat processing apparatus of 2nd invention. It is a figure which shows the simulation of the flow of the process gas of a 2nd invention apparatus. It is a schematic block diagram which shows a general batch type heat processing apparatus.

Explanation of symbols

2 Heat treatment apparatus 4 Processing container 6 Inner cylinder 8 Outer cylinder 16 Gas introduction nozzle 26 Wafer boat (object to be processed support)
28 Boat elevator (insertion / removal mechanism)
32 Thick-wall side wall 34 Thin-wall side wall 38 Gas introduction port 40 Gas suction port 50 Heat treatment apparatus 52 Processing vessel 58 Gas introduction port 60 Gas suction ports 62A to 62C, 64A to 64C, 66A to 66C Ejection slit 68 Passage forming members 70A to 70C Groove 80 Wafer boat (processing object support)
82 Top plate 84 Bottom plate 86 Plate member 88 Support protrusion (support part)
W Semiconductor wafer (object to be processed)

Claims (7)

When a predetermined heat treatment is performed by flowing a processing gas to a plurality of objects to be processed arranged at a predetermined pitch, the plurality of objects to be processed are arranged in the arrangement direction so as to face one end side of the plurality of objects to be processed. The treatment is performed from a gas introduction port having a small conductance formed along a direction toward a gas suction port having a large conductance so as to face the other end side of the plurality of treatment objects. A film forming method, wherein a gas is allowed to flow to pass the processing gas between the objects to be processed. In a heat treatment apparatus for performing a predetermined heat treatment by flowing a processing gas to a target object, a target object supporting tool that supports a plurality of target objects arranged at a predetermined pitch and supports the target object A processing vessel made evacuable, a gas inlet having a small conductance formed along the arrangement direction of the objects to be processed so as to face one end side of the objects to be processed, and the plurality of objects to be processed A gas suction port having a large conductance formed along the arrangement direction of the objects to be processed so as to face the other end of the body, and an insertion / removal for loading and unloading the object support tool into the processing container. And a mechanism for heat treatment. The processing container has a double pipe structure of an inner cylinder and an outer cylinder provided so as to surround the inner cylinder, and the gas inlet is formed along one side of the inner cylinder, The heat treatment apparatus according to claim 2, wherein the gas suction port is formed along the other side of the inner cylinder. 3. The gas inlet is provided along a side wall of the processing container, and the gas suction port is provided by forming the side wall of the processing container so as to protrude outward. The heat treatment apparatus as described. The heat treatment apparatus according to claim 4, wherein the gas introduction port is divided and arranged for each of a plurality of zones along the arrangement direction of the objects to be processed. 6. The heat treatment apparatus according to claim 4, wherein the gas inlet is divided into a plurality of portions along a circumferential direction of the object to be processed. The object to be processed support includes two plate members having an arcuate cross section having a support portion which is in contact with and supports the object to be processed on the inner side and has a predetermined thickness. Item 7. The heat treatment apparatus according to any one of Items 4 to 6.

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