JP2006041200A - Film formation method and film formation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film formation method by which particles can be prevented from scattering when the pressure is restored to normal pressure in a processing vessel. <P>SOLUTION: An object W to be processed supported by a plurality of steps is housed in a vertical processing vessel 22 for evacuation, and while the object is heated, a gas for film formation is fed into the processing vessel and a thin film is deposited on the object in pressure-reduced atmosphere. In such the film formation method, when the pressure in the processing vessel is restored to normal pressure, a gas for normal pressure restoration is fed in the processing vessel so that it may flow in the reverse direction to the flow direction of the gas for film formation. Thus, particles can be prevented from scattering when the pressure in the processing vessel is restored to normal pressure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a film forming method and film forming apparatus for depositing a thin film on the surface of an object to be processed such as a semiconductor wafer, and more particularly to a film forming method for preventing scattering of particles when returning to normal pressure in a processing container. And a film forming apparatus.

In general, in order to manufacture a semiconductor integrated circuit, various processes such as a film formation process, an etching process, an oxidation process, a diffusion process, and a modification process are performed on a semiconductor wafer made of a silicon substrate or the like. Of the various types of processing described above, for example, film forming processing is used as an example, and this type of film forming processing is performed in, for example, a batch type film forming apparatus as disclosed in Patent Document 1 and Patent Document 2, for example. Done. Specifically, as shown in FIG. 4, semiconductor wafers W that are objects to be processed are accommodated in a plurality of stages in a wafer boat 4 in a vertical processing container 2, and the processing container 2 The wafer W is heated to a predetermined temperature, for example, about 600 to 800 ° C. by the heating means 6 provided so as to surround the wafer. Then, a film forming gas such as dichlorosilane (hereinafter also referred to as “DCS”) or NH ₃ gas is supplied from the lower part to the ceiling of the processing container 2 while being supplied into the processing container 2 from the film forming gas supply means 8. The inside of the processing container 2 is evacuated by the vacuum exhaust system 12 from the provided exhaust port 10, and the film forming process is performed while maintaining the internal atmosphere at a predetermined pressure.

When the film formation process described above is completed, the supply of the film formation gas such as NH ₃ gas or DCS gas is stopped, and then the atmospheric pressure is placed in the vacuum processing container 2 in order to unload the processed wafer. inert gas as the return gas, evacuating the example N ₂ gas supply unit 14 residual gas while supplying from N ₂ gas, and at the same time to cool the wafer temperature unloading temperature, for example up to about 600 ° C.. When the pressure in the processing container 2 returns to the normal pressure and the wafer temperature also falls to a temperature at which handling can be performed, the wafer boat 4 is lowered and unloaded, and the processed wafer W is processed into the processing container. 2 will be taken out from inside.

Japanese Patent Laid-Open No. 9-246257 Japanese Patent Laid-Open No. 2002-9209

By the way, when the film forming process is completed, N ₂ gas is supplied into the processing container 2 as a normal pressure restoring gas. At this time, the N ₂ gas needs to be quickly restored to normal pressure in order to improve throughput. Large flow rate is supplied in a fairly short time. In this case, since the temperature in the bottom of the processing container 2 is relatively lower than that in the central part of the container, an unnecessary film or reaction auxiliary is not formed on the surface of the heat insulating cylinder 16 that supports the wafer boat 4 or the inner wall surface of the processing container 2. The product is adhered, and the unnecessary film and reaction by-product are wound up following the momentum of the introduced gas when the normal pressure restoring gas is introduced, and are scattered as particles in the processing container 2. There remains a problem that it remains and adheres to the wafer W. In particular, this kind of unnecessary film or reaction by-product is subjected to repeated heating and deposition, and is subjected to repeated heating and cooling, resulting in large thermal stress and relatively easy film peeling. An early solution is desired.
The present invention has been devised to pay attention to the above problems and to effectively solve them. The objective of this invention is providing the film-forming method and film-forming apparatus which can prevent scattering of the particle at the time of a normal pressure return in a processing container.

According to the first aspect of the present invention, an object to be processed supported in a plurality of stages is accommodated in a vertical processing container that can be evacuated, and a film is formed in the processing container while heating the object to be processed. In a film forming method in which a thin film is deposited on the object to be processed in a reduced pressure atmosphere by flowing a working gas, the flow of the film forming gas into the processing container when the inside of the processing container is returned to normal pressure. The film forming method is characterized in that the normal pressure return gas is allowed to flow in a direction opposite to the direction.
As described above, when the inside of the processing container is returned to the normal pressure, the normal pressure returning gas is caused to flow in the processing container in the direction opposite to the flow direction of the film forming gas. The normal pressure recovery gas is not blown to the portion where the reaction by-product or the like tends to adhere, and therefore, scattering of particles at the time of normal pressure recovery in the processing container can be prevented.

In this case, for example, as defined in claim 2, the film-forming gas flows in the processing container from below to above during film-forming processing, and the pressure-returning gas from above to return to normal pressure. Make it flow downward.
For example, as defined in claim 3, the normal pressure recovery gas is made of an inert gas.
According to a fourth aspect of the present invention, there is provided a vertical processing container capable of accommodating an object to be processed, holding means for supporting the object to be processed in a plurality of stages, and heating means for heating the object to be processed. A film forming gas supply means for supplying a film forming gas into the processing container, a film forming vacuum exhaust means for evacuating the processing container during film formation, and a control means for controlling the operation of the entire apparatus. In the film forming apparatus, the normal pressure return gas is caused to flow in the processing container in a direction opposite to the flow direction of the film forming gas when the inside of the processing container is returned to normal pressure. The film forming apparatus is characterized in that a pressure return gas supply means and a normal pressure return gas exhaust means are provided.

In this case, for example, as defined in claim 5, the processing vessel has a single tube structure, and an exhaust gas to which a gas nozzle of the gas nozzle of the film forming gas supply unit and the gas exhaust unit for returning to normal pressure are connected. The mouth is located at the lower part of the processing container, and the gas outlet of the gas nozzle of the gas supply means for returning to the normal pressure and the gas outlet of the gas supply means for returning to the normal pressure are located at the upper part of the processing container.
Alternatively, for example, as defined in claim 6, the processing vessel has a single tube structure, and a gas injection port of a gas nozzle of the film forming gas supply unit and an exhaust port to which the normal pressure return gas exhaust unit is connected are An exhaust port connected to the vacuum evacuation unit at the time of film formation and a gas injection port of a gas nozzle of the normal pressure return gas supply unit are positioned below the process vessel.

Further, for example, as defined in claim 7, the processing container has a double-pipe structure including an inner cylinder and an outer cylinder arranged concentrically at a predetermined interval, and the film-forming gas supply means An exhaust port to which the gas injection port of the gas nozzle and the gas supply means for returning to normal pressure are connected is provided at the lower part of the processing container so as to face the inner cylinder and the outer cylinder, and the vacuum exhaust means at the time of film formation is connected The exhaust port and the gas injection port of the gas nozzle of the normal pressure return gas supply means are provided at the lower part of the processing container so as to face the gap between the inner cylinder and the outer cylinder.
For example, as defined in claim 8, the normal pressure recovery gas is made of an inert gas.

According to the film forming method and the film forming apparatus of the present invention, the following excellent effects can be exhibited.
When returning to normal pressure in the processing vessel, the normal pressure return gas is made to flow in the direction opposite to the flow direction of the film forming gas in the processing vessel. The gas for returning to normal pressure is no longer sprayed on the portion where the etc. tend to adhere, and therefore, scattering of particles when returning to normal pressure in the processing container can be prevented.

Hereinafter, an embodiment of a film forming method and a film forming apparatus according to the present invention will be described in detail with reference to the accompanying drawings.
<First embodiment>
FIG. 1 is a block diagram showing a first embodiment of a film forming apparatus for carrying out the method of the present invention. First, this film forming apparatus will be described. As shown in the figure, the film forming apparatus 20 has a vertical processing container 22 having a cylindrical shape with a lower end opened and a predetermined length in the vertical direction. For example, quartz having high heat resistance can be used for the processing container 22.
A wafer boat 24 as a holding means on which a plurality of semiconductor wafers W as processing objects are placed at a predetermined pitch over a plurality of stages from below the processing container 22 is detachably inserted and removed. The wafer boat 24 is made of, for example, quartz. For example, about 50 to 100 wafers W having a diameter of 300 mm can be supported in multiple stages at substantially equal pitches.

  When the wafer boat 24 is inserted, the opening at the lower end of the processing vessel 22 is closed and sealed with a lid 26 made of, for example, quartz or stainless steel. At this time, a seal member 28 such as an O-ring is interposed between the lower end portion of the processing container 22 and the lid portion 26 in order to maintain airtightness. The wafer boat 24 is placed on a table 32 via a quartz heat insulating cylinder 30, and the table 32 has a rotating shaft 34 that passes through a lid portion 26 that opens and closes a lower end opening of the processing container 22. Supported by the upper end. For example, a magnetic fluid seal 36 is interposed in the penetrating portion of the rotating shaft 34 and supports the rotating shaft 34 so as to be rotatable while hermetically sealing. The above-described rotating shaft 34 is attached to the tip of an arm 40 supported by an elevating mechanism 38 such as a boat elevator, for example, so that the wafer boat 24 and the lid 26 can be integrally raised and lowered. The table 32 may be fixed to the lid portion 26 side, and the wafer W may be processed without rotating the wafer boat 24.

  A heating means 42 made of, for example, a carbon wire heater is provided on the side of the processing container 22 so as to surround the processing container 22, and the processing container 22 positioned inside the processing container 22 and the semiconductor wafer W therein. Can be heated. Further, a heat insulating material 44 is provided on the outer periphery of the heating means 42 so as to ensure this thermal stability. Further, first, second, and third gas nozzles 46, 48, and 50 made of, for example, quartz are provided in the lower portion of the processing container 22 so as to penetrate the side wall in an airtight manner. The gas injection ports 46A and 48A of the first and second gas nozzles 46 and 48 are provided facing the lower part in the processing container 22, respectively. The third gas nozzle 50 is bent upward and extends upward along the side wall of the container, and the gas injection port 50 </ b> A is provided facing the ceiling portion in the processing container 22. In addition, a first exhaust port 52 bent in an L shape in the lateral direction is provided in the ceiling portion of the processing container 22, and a second exhaust port 54 is formed in the lower side wall of the processing container 22. Is provided.

In this first embodiment, a film forming gas supply means 60 is connected to the first and second gas nozzles 46, 48, and a normal pressure return gas supply means 62 is connected to the third gas nozzle 50. Is done. Specifically, the film forming gas supply means 60 includes a DCS gas supply system 64 and an NH ₃ gas supply system 66, and the gas passage 64 A of the DCS gas supply system 64 and the gas of the NH ₃ gas supply system 66. The passage 66A is connected to the first and second gas nozzles 46 and 48, respectively, and the gas passages 64A and 66A are respectively provided with flow controllers 64B and 66B such as a mass flow controller and on-off valves 64C and 66C. The DCS gas and the NH ₃ gas can be supplied while controlling the flow rate as necessary.
In contrast, the atmospheric pressure returning gas supply means 62 is made of a N ₂ gas supply system 68 for supplying for example N ₂ gas as the inert gas, the gas passage 68A of the N ₂ gas supply system 68 is the first The gas passage 68A is provided with a flow rate controller 68B such as a mass flow controller and an open / close valve 68C in order, and supplies N ₂ gas while controlling the flow rate as necessary. It can be done. As the inert gas, Ar gas, He gas or the like may be used in addition to N ₂ gas.

  The first exhaust port 52 is connected to a vacuum exhaust means 70 during film formation for evacuation during film formation. In contrast, the second exhaust port 54 is connected to normal pressure for exhausting when normal pressure is restored. A return gas exhaust means 72 is connected. Specifically, a pressure control valve 70C such as an on-off valve 70B, 72B, a butterfly valve, or the like is provided in the gas passage 70A of the vacuum exhaust means 70 during film formation and the gas passage 72A of the gas exhaust means 72 for returning to normal pressure. 72C and vacuum pumps 70D and 72D are sequentially provided. The gas passages 70A and 72A on the downstream side of the on-off valves 70B and 72B may be merged so that the pressure control valve and the vacuum pump are shared. The operation of the entire apparatus is controlled by a control means 80 composed of, for example, a microcomputer.

Next, a film forming method performed using the film forming apparatus 20 configured as described above will be described.
First, when the semiconductor wafer W made of, for example, a silicon wafer is in an unloaded state and the film forming apparatus 20 is in a standby state, the processing container 22 is maintained at a temperature lower than the process temperature, and a large number of normal temperature sheets, for example, 50 wafers. The wafer boat 24 in a state where W is placed is loaded into the processing container 22 in a hot wall state by being lifted from below, and the lower end opening of the processing container 22 is closed by the lid portion 26 to thereby close the processing container 22. Seal the inside.
Then, the inside of the processing container 22 is evacuated and maintained at a predetermined process pressure, and the power supplied to the heating means 42 is increased to raise the wafer temperature to the film processing temperature. The DCS gas and the NH _{3 are} supplied from a predetermined processing gas required for performing the film forming process step, that is, the DCS gas supply system 64 and the NH ₃ gas supply system 66 of the film forming gas supply means 60 here. _Three gases are supplied into the processing vessel 22 from the first and second gas nozzles 46 and 48 while controlling the flow rate. During this film formation process, the on-off valve 68C of the normal pressure return gas supply means 62 is closed so that N ₂ gas is not supplied, and the drive of the normal pressure return gas exhaust means 72 is stopped, and the vacuum during film formation is stopped. Only the exhaust means 70 is driven.

Both the DCS and NH ₃ gases rise in the processing vessel 22 as indicated by an arrow 82 and react in a vacuum atmosphere to come into contact with the wafer W accommodated in the rotating wafer boat 24. Thus, a silicon nitride film (SiN) is deposited on the wafer surface. The processing gas or the gas generated by the reaction is exhausted from the first exhaust port 52 in the ceiling of the processing container 22 to the outside by the vacuum exhaust means 70 during film formation. As described above, during the film formation, the film forming gas is caused to flow into the processing container 22 upward from below. When the film forming process for a predetermined time is completed, the on-off valves 64C and 66C of the film forming gas control means 60 are closed to stop the supply of both the DCS gas and the NH ₃ gas, and the film forming vacuum is performed. The on-off valve 70B of the exhaust means 70 is closed to stop this drive.

At the same time, in order to eliminate the residual gas in the processing container 22 and lower the wafer temperature to the unload temperature, the on-off valve 68C of the normal pressure return gas supply means 62 is opened, and the processing container is supplied from the third gas nozzle 50. N ₂ gas is supplied to the ceiling part 22 while controlling the flow rate. At the same time, the normal pressure return gas exhaust means 72 connected to the lower portion of the processing container 22 is driven, and the on-off valve 72B is opened to exhaust the atmosphere in the processing container 22 from the second exhaust port 54. As a result, the atmosphere gas flows from the upper side to the lower side in the processing container 22 as indicated by the white arrow 84, the normal pressure is restored in the processing container 22, and the wafer temperature is also lowered to the unloading temperature. It will be.
In this manner, when the inside of the processing chamber 22 returns to normal pressure and the wafer temperature also decreases, the supply of the normal pressure return gas is stopped and the driving of the normal pressure return gas exhaust means 72 is also stopped. When the wafer boat 24 is lowered and unloaded, the processed wafer W is taken out of the processing container 22.

As described above, in the first embodiment, since the film forming gas is supplied from the lower part in the processing container 22 and flows upward, the vicinity of the lower part in the processing container 22 that is relatively low in temperature. An unnecessary film or reaction by-product adheres to the substrate, but the normal pressure return gas (N ₂ ) supplied relatively vigorously is introduced from the upper part in the processing vessel 22 and flows downward. Therefore, the unnecessary film and reaction by-products are less likely to be peeled off, and accordingly, the particles are not wound up, and the generation of particles can be suppressed.

<Second embodiment>
Next, a second embodiment of the device of the present invention will be described.
FIG. 2 is a block diagram showing a second embodiment of the apparatus of the present invention. In addition, the same code | symbol is attached | subjected about the same component as 1st Example shown in FIG. 1, and the description is abbreviate | omitted.
In the second embodiment, the flow direction of the film forming gas and the flow direction of the normal pressure restoring gas are set opposite to each other in the case of the first embodiment. That is, here, similarly to the third gas nozzle 50, the second gas nozzle 48 is bent upward and raised upward along the inner wall of the processing vessel 22, and the gas injection port 48 </ b> A is formed in the ceiling portion in the processing vessel 22. To be located.
The NH ₃ gas supply system 66 and the DCS gas supply system 64 of the film forming gas supply means 60 are connected to the second and third gas nozzles 48 and 50, respectively, and the NH ₃ gas and the DCS gas are supplied into the processing vessel 22. It is designed to be supplied to the ceiling.

The N ₂ gas supply system 68 of the normal pressure return gas supply means 62 is connected to the first gas nozzle 46 so that N ₂ gas is supplied to the lower part in the processing vessel 22. Further, a vacuum exhaust means 70 is connected to the second exhaust port 54 at the lower part of the processing container 22, while the first exhaust port 52 on the ceiling of the processing container 22 is connected to the first exhaust port 54. The normal pressure return gas exhaust means 72 is connected.
As a result, the film forming gas flows into the processing vessel 22 from the upper side as shown by the arrow 82, whereas the normal pressure return gas flows from the lower side and up as shown by the white arrow 84. It begins to flow toward. In this case as well, as in the case of the first embodiment, unnecessary films and reaction by-products are less likely to be peeled off, so that the particles are not rolled up and the generation of particles is suppressed. Can do.

<Third embodiment>
Next, a third embodiment of the device of the present invention will be described.
FIG. 3 is a block diagram showing a third embodiment of the apparatus of the present invention. In addition, the same code | symbol is attached | subjected about the same component as 1st Example shown in FIG. 1, and the description is abbreviate | omitted.
In this third embodiment, the processing vessel has a double tube structure consisting of an inner cylinder and an outer cylinder, and the flow direction of the film forming gas flowing in the inner cylinder and the flow direction of the normal pressure restoring gas are as follows. Are set to be the same as those in the first embodiment. That is, in the third embodiment, the processing container 22 includes an inner cylinder 22A and an outer cylinder 22B arranged concentrically at a predetermined interval. The lower end of the processing vessel 22 is connected to a manifold 86 made of, for example, stainless steel formed in a cylindrical shape via a seal member 90 such as an O-ring. The lower end portion of the inner cylinder 22A is supported by a support convex portion 88 protruding from the manifold 86.

The first and second nozzles 46 and 48 are provided so as to penetrate the manifold 86, and the gas injection ports 46A and 48A are installed so as to face the inner side of the inner cylinder 22A. Yes. A DCS gas supply system 64 and an NH ₃ gas supply system 66 are connected to the first and second nozzles 46 and 48, respectively. The second exhaust port 54 is also provided in the manifold 86 so as to face the inner cylinder 22A. Then, the normal pressure return gas exhaust means 72 is connected to the second exhaust port 54.

On the other hand, the first exhaust port 52 is provided at the lower part of the processing container 22 so as to face the gap 92 between the inner tube 22A and the outer tube 22B. The vacuum evacuation means 70 is connected to the film 52 at the time of film formation. Similarly, the third gas nozzle 50 is provided at the lower part of the processing container 22 so as to face the gap 92 between the inner cylinder 22A and the outer cylinder 22B. An N ₂ gas supply system 68 of the return gas supply means 62 is connected.
In the case of the third embodiment, the film forming gas flows from the lower side to the upper side in the inner cylinder 22A in which the wafer W is accommodated as shown by an arrow 82, and is folded at the ceiling portion of the processing vessel 22. It flows downward through the gap 92 between the inner cylinder 22A and the outer cylinder 22B, and is evacuated from the first exhaust port 52 to the outside of the container.

On the other hand, N ₂ gas, which is a normal pressure recovery gas, flows from below to above in the gap 92 between the inner cylinder 22A and the outer cylinder 22B, as indicated by the white arrow 84, and is processed. It is folded at the ceiling of the container 22, flows in the inner cylinder 22 </ b> A downward from above, and is discharged out of the container through the second exhaust port 54. In this case as well, as in the case of the first embodiment, unnecessary films and reaction by-products are less likely to be peeled off, so that the particles are not rolled up and the generation of particles is suppressed. Can do.
In each of the above embodiments, the case where the silicon nitride film is formed using DCS gas and NH ₃ gas as the film forming gas has been described as an example. Of course, the present invention can be applied to any kind of film forming gas and film type.
The object to be processed is not limited to a semiconductor wafer, and the present invention can be applied to an LCD substrate, a glass substrate, and the like.

It is a block diagram which shows 1st Example of the film-forming apparatus for enforcing the method of this invention. It is a block diagram which shows 2nd Example of this invention apparatus. It is a block diagram which shows 3rd Example of this invention apparatus. It is a schematic block diagram which shows the conventional batch type film-forming apparatus.

Explanation of symbols

20 Film deposition apparatus 22 Processing container 24 Wafer boat (holding means)
42 heating means 46 first gas nozzle 46A gas injection port 48 second gas nozzle 48A gas injection port 50 third gas nozzle 50A gas injection port 52 first exhaust port 54 second exhaust port 60 film forming gas supply unit 62 Gas supply means for returning to normal pressure 64 DCS gas supply system 66 NH ₃ gas supply system 68 N ₂ gas supply system 70 Vacuum exhaust means during film formation 72 Gas exhaust means for returning to normal pressure 80 Control means W Semiconductor wafer (object to be processed)

Claims (8)

A processing object supported in a plurality of stages is accommodated in a vertical processing container that can be evacuated, and a film forming gas is allowed to flow in the processing container while heating the processing object in a reduced-pressure atmosphere. In the film forming method in which a thin film is deposited on the object to be processed,
The film forming method is characterized in that when the inside of the processing container is returned to normal pressure, the normal pressure returning gas is caused to flow in the processing container so as to be in a direction opposite to the flow direction of the film forming gas. Method.   In the processing container, the film forming gas flows upward from below during film forming processing, and the normal pressure returning gas flows downward from above when returning to normal pressure. The film forming method according to claim 1.   The film forming method according to claim 1, wherein the normal pressure recovery gas is made of an inert gas. A vertical processing container capable of accommodating an object to be processed;
Holding means for supporting the object to be processed in a plurality of stages;
Heating means for heating the object to be processed;
A film forming gas supply means for supplying a film forming gas into the processing container;
A vacuum evacuation means during film formation for evacuating the inside of the processing container during film formation;
Control means for controlling the operation of the entire apparatus;
In a film forming apparatus having
When the inside of the processing container is returned to normal pressure, a normal pressure returning gas supply means for flowing the normal pressure returning gas into the processing container in a direction opposite to the flow direction of the film forming gas, A film forming apparatus comprising a pressure return gas exhaust unit.   The processing vessel has a single tube structure, and a gas injection port of a gas nozzle of the film forming gas supply unit and an exhaust port to which the normal pressure return gas exhaust unit is connected are located in a lower part of the processing vessel, and 5. The film forming apparatus according to claim 4, wherein an exhaust port to which a film vacuum exhaust unit is connected and a gas injection port of a gas nozzle of the normal pressure return gas supply unit are located above the processing vessel.   The processing vessel has a single tube structure, and a gas injection port of a gas nozzle of the film forming gas supply unit and an exhaust port to which the normal pressure return gas exhaust unit is connected are located above the processing vessel, and 5. The film forming apparatus according to claim 4, wherein an exhaust port to which a film vacuum exhaust unit is connected and a gas injection port of a gas nozzle of the normal pressure return gas supply unit are positioned below the processing vessel.   The processing container has a double-pipe structure composed of an inner cylinder and an outer cylinder arranged concentrically at a predetermined interval, and includes a gas injection port of a gas nozzle of the film forming gas supply means and a normal pressure return gas. An exhaust port to which the supply means is connected is provided at the lower part of the processing container so as to face the inner cylinder and the outer cylinder. The film forming apparatus according to claim 4, wherein a gas injection port of a gas nozzle of the supply unit is provided at a lower portion of the processing container so as to face a gap between the inner cylinder and the outer cylinder. The film forming apparatus according to claim 4, wherein the normal pressure return gas is made of an inert gas.

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