JP3595508B2 - Semiconductor manufacturing equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a semiconductor manufacturing apparatus, and more particularly to a semiconductor manufacturing apparatus that performs in-situ (in-situ) cleaning after forming a film on a wafer in an insulating film forming step.
[0002]
[Prior art]
In an insulating film forming apparatus using a high-density plasma source, a process of forming an insulating film and an in-situ cleaning process of removing an insulating film attached to an inner wall of a chamber or the like are repeatedly and periodically performed. In this type of apparatus, an insulating film formation step using a high-density plasma source is performed in a high vacuum region (a region in which the atmospheric pressure is reduced to several tens Pa). On the other hand, in-situ cleaning performed subsequent to the film forming process is performed in a medium vacuum region (a region in which the atmospheric pressure is reduced to several hundred Pa).
[0003]
As described above, the pressure in the region where the processing is performed is greatly different between the film forming step and the in-situ cleaning step. For this reason, a turbo molecular pump is used for the pressure reduction in the film forming process, while a dry pump is usually used instead of the turbo molecular pump for the pressure reduction in the in-situ cleaning.
[0004]
In order to enable the above-mentioned switching of the pump, the insulating film deposition apparatus using the high-density plasma source has a region which cannot be structurally cleaned by in-situ cleaning. The film attached to such a region becomes particles by peeling off from the inner wall of the chamber, which causes a reduction in the yield of the semiconductor device.
[0005]
Hereinafter, a structural problem of the conventional insulating film forming apparatus regarding in-situ cleaning will be described in more detail with reference to FIG.
FIG. 1 is a conceptual diagram of an insulating film forming apparatus using a high-density plasma source. A susceptor 103 for holding a wafer 102 is provided in the process chamber 101. The susceptor 103 is connected to an RF power supply 108 and can apply RF. A coil 105 is provided on the outer wall of the chamber 101. The coil 105 is connected to the RF power supply 104 and can perform RF application. The susceptor 103 is provided with a wafer cooling mechanism and a wafer chuck mechanism. However, since it is not related to the present invention, a detailed description thereof will be omitted. Although this apparatus is provided with a piping line for introducing an in-situ cleaning gas, its illustration is omitted because the configuration does not affect the present invention.
[0006]
The vacuum system of this apparatus includes a turbo-molecular pump 111 for keeping the chamber 101 at a high vacuum, and a dry pump 113 for reducing the back pressure of the turbo-molecular pump 111 or roughing the gas in the chamber 101. Have. The vacuum line is provided with a throttle valve 109 for pressure control, a main valve 110 of the chamber 101, a valve 107 used for roughing the gas in the chamber 101, and a valve 112 located downstream of the turbo molecular pump 111. ing. Here, the pressure in the chamber 101 is controlled using the throttle valve 110, but the pressure may be controlled by the rotation speed of the turbo-molecular pump 111.
[0007]
The formation of the insulating film is performed in a high vacuum region. Therefore, in the step of forming the insulating film, the turbo-molecular pump 111 evacuates the vacuum in a state where the valve 107 is closed and both the main valve 110 and the valve 112 are open. The back pressure is drawn by the dry pump 113. On the other hand, in-situ cleaning is performed in a medium vacuum region, and in that process, vacuum is drawn by the dry pump 113. At this time, in the vacuum system of the apparatus, the main valve 110 and the valve 112 are closed, and the valve 107 is opened.
[0008]
[Problems to be solved by the invention]
Compared with the state of the vacuum system in the insulating film formation process, the vacuum system during the in-situ cleaning has a closed region from the downstream of the main valve 110 to the upstream of the valve 112 located downstream of the turbo-molecular pump 111. It will be in a state where it was lost. Since the in-situ cleaning gas does not flow in this closed area, the products adhering to the valve element of the main valve 110 and the rotor and the stator of the turbo molecular pump 111 (to the amount adhering to the inner wall of the chamber 101). Although very small in comparison), it cannot be removed by in-situ cleaning.
[0009]
In the conventional insulating film forming apparatus, in order to remove a product adhering to this portion, it is necessary to perform cleaning by removing a vacuum pipe, a valve, a pump, and the like. For this reason, in the conventional apparatus, the above-described cleaning causes a long downtime, which is a factor of reducing the operation rate of the apparatus. Further, the product adhered to the valve body of the main valve 110 has become a particle source with the operation of the valve body. As described above, the conventional insulating film forming apparatus using the high-density plasma source has a structural problem that the film forming step and the in-situ cleaning step are performed in different pressure regions, and as a result, There is a problem that the yield of the semiconductor device is reduced by the generated particles.
[0010]
These problems are difficult to solve if the configuration of the conventional device is maintained as it is. That is, as a method of in-situ cleaning, a method of performing RF discharge by introducing an in-situ cleaning gas into the chamber 101 and performing in-situ cleaning by an activated species generated as a result, or a method of cleaning the chamber 101 Various methods are known, such as a method of generating an in-situ cleaning active species such as a fluorine radical outside and introducing the active species into the chamber 101 for in-situ cleaning. However, none of these in-situ cleanings can be performed in a pressure region used for film formation using a high-density plasma source. On the other hand, if the pressure for the film formation is set to the pressure used for in-situ cleaning, high-density plasma cannot be discharged. For this reason, in the conventional apparatus, it has been difficult to solve the problem caused by the fact that the pressure region for in-situ cleaning and the film formation pressure using high-density plasma are performed in different pressure regions.
[0011]
As described above, in the conventional apparatus, it is a serious problem that the film forming process and the in-situ cleaning process cannot be performed unless the state of the vacuum system is switched due to the difference in the pressure region. One method for solving the above-mentioned problem is to enable a film forming process and an in-situ cleaning process to be performed in the same pressure region. For example, if the film forming process can be performed in the in-situ cleaning pressure region, the above-mentioned problem is solved. However, in this case, high-density plasma cannot be discharged, and the film forming process cannot be performed. Further, when the film formation process is performed with the degree of vacuum reduced within a range in which in-situ cleaning can be performed, the average free distance of ions in the film formation plasma is not sufficient, so that wiring or STI (Shallow Trench Isolation) is not used. Vacancies are likely to be formed in the buried insulating film for forming the holes. These holes cannot be ignored because they affect the characteristics of the semiconductor device.
[0012]
The present invention has been made to solve the above-described problems, and a vacuum system used for normal film formation without closing a main valve even during in-situ cleaning, that is, a vacuum system including a turbo molecular pump. An object of the present invention is to provide a semiconductor manufacturing apparatus in which parts for lowering the vacuum conductance are inserted between a process chamber and a turbo molecular pump so that a vacuum can be evacuated in a system.
[0013]
[Means for Solving the Problems]
The invention according to claim 1 is a semiconductor manufacturing apparatus for forming an insulating film on a semiconductor wafer to achieve the above object,
A process chamber for performing an insulating film formation process;
A vacuum pump for exhausting gas in the process chamber,
A pressure control valve disposed between the process chamber and the vacuum pump,
A main valve that shuts off the process chamber and the vacuum pump;
Providing a valve body having a predetermined opening, an opening and closing valve disposed between the process chamber and the vacuum pump,
It is characterized by having.
[0014]
According to a second aspect of the present invention, in the semiconductor manufacturing apparatus according to the first aspect, the open / close valve is disposed between the main valve and the vacuum pump.
[0015]
The invention according to claim 3 is the semiconductor manufacturing apparatus according to claim 1 or 2, wherein the open / close valve is opened during a process of forming an insulating film, and the open / close valve is opened during in-situ cleaning. It is characterized by further comprising a control device for closing the state.
[0016]
According to a fourth aspect of the present invention, in the semiconductor manufacturing apparatus according to the third aspect, the control device causes the pressure in the process chamber to be in a predetermined high vacuum state when the insulating film is formed. wherein controlling the pressure control valve, and, during the in-situ cleaning, the pressure of the process chamber is characterized by controlling the pressure control valve so that the vacuum state in the predetermined manner.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
Hereinafter, the first embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a diagram illustrating a configuration of the semiconductor manufacturing apparatus according to the first embodiment of the present invention. As shown in FIG. 2, the semiconductor manufacturing apparatus of the present embodiment includes a process chamber 201. A susceptor 203 for holding a wafer 202 is disposed inside the chamber 201.
[0018]
The susceptor 203 is connected to an RF power supply 208 and can perform RF application. A coil 205 is provided on the outer wall of the chamber 201. The coil 205 is connected to the RF power supply 204 and can perform RF application. The susceptor 203 is provided with a wafer cooling mechanism and a wafer chuck mechanism. However, since the susceptor is not related to the present invention, a detailed description thereof will be omitted. Although this apparatus is provided with a piping line for introducing an in-situ cleaning gas, its illustration is omitted because the configuration does not affect the present invention.
[0019]
The vacuum system of this apparatus includes a turbo-molecular pump 211 for keeping the chamber 201 at a high vacuum and a dry pump 213 for reducing the back pressure of the turbo-molecular pump 211 or roughing the gas in the chamber 201. Have. The vacuum line is provided with a throttle valve 209 for pressure control, a main valve 210 of the chamber 201, a valve 207 used for roughing gas in the chamber 201, and a valve 212 located downstream of the turbo-molecular pump 211. ing. Here, the pressure in the chamber 201 is controlled using the throttle valve 210, but the pressure may be controlled by the rotation speed of the turbo-molecular pump 11.
[0020]
The structure described above is the same as the structure of the conventional insulating film forming apparatus shown in FIG. The semiconductor manufacturing apparatus according to the present embodiment includes a valve 214 between the throttle valve 209 and the turbo molecular pump 211, and a valve 301 having a hole 301 as shown in FIG. Is characterized by
[0021]
In the step of forming an insulating film on the wafer 202, a semiconductor material gas such as SiH ₄ , SiF ₄ , PH ₃ or the like is introduced into the process chamber 201, and the susceptor 203 and the coil 205 are supplied with RF power sources 204 and 208. A high frequency is applied. As a result, high-density plasma is generated inside the chamber 201, and the semiconductor material gas is decomposed in the high-density plasma, whereby an insulating film is formed on the wafer 202. At this time, a vacuum exhaust path is formed inside the apparatus so that the gas in the chamber 201 is exhausted by the turbo molecular pump 211 and the dry pump 213 through the throttle valve 209 for pressure control.
[0022]
The in-situ cleaning is performed by introducing a material gas for generating radical molecules for cleaning, for example, a semiconductor material gas such as NF ₃ , C ₂ F ₆ , C ₃ F _{8 into} the chamber 201. More specifically, in the in-situ cleaning step, the above-described material gas is introduced into the chamber 201, and plasma is generated in the chamber 201 by the RF power supplies 204 and 208. This process needs to be performed in a medium vacuum region of about 500 Pa unlike the case of the insulating film formation process.
[0023]
When the turbo molecular pump 211 is used in a normal manner, the internal pressure of the chamber 201 is reduced to a high vacuum region. Therefore, in order to use the turbo molecular pump 211 at the time of in-situ cleaning, it is necessary to reduce the degree of vacuum in the chamber 201 to a medium vacuum level by some method. As a method of reducing the degree of vacuum in the chamber 201, for example, it is conceivable to control a throttle valve 209 mounted upstream of the turbo molecular pump 211. However, in this case, since the pressure difference generated between the upstream side and the downstream side of the throttle valve 209 is high, highly accurate control cannot be realized.
[0024]
In the apparatus of the present embodiment, when the valve 214 having the characteristic valve element as shown in FIG. 3 is closed during in-situ cleaning, a pressure difference is generated between the upstream and downstream of the valve 214. Thus, the pressure difference between upstream and downstream of the throttle valve 209 can be reduced. It should be noted that the pressure difference between the upstream and downstream of the valve 214 can be controlled by the size and number of holes in the valve body shown in FIG. In the present embodiment, the size is 1 mm ^2, and the number is about 100 pieces.
[0025]
The device of the present embodiment includes a control device (not shown) for controlling the states of the throttle valve 209 and the valve 214. This control device controls the throttle valve 209 so that a desired degree of vacuum is obtained while the valve 214 is in an open state at the time of forming an insulating film, and at the time of in-situ cleaning, After the valve 214 is closed, the throttle valve 209 is controlled to obtain a desired degree of vacuum. In this case, since the pressure difference generated between the upstream and the downstream of the throttle valve 209 during the in-situ cleaning is suppressed, while the turbo molecular pump 211 is operated, the medium vacuum necessary for performing the in-situ cleaning is reduced. The state can be created with high accuracy.
[0026]
In the apparatus of this embodiment, the vacuum exhaust path formed during in-situ cleaning is exactly the same as the vacuum exhaust path formed during the formation of the insulating film except that the valve 214 is closed. . That is, in the present embodiment, during the in-situ cleaning, the path through which the gas inside the chamber 201 is exhausted follows the same path as the gas inside the chamber 201 follows during the formation of the insulating film. Is done. Therefore, according to the apparatus of the present embodiment, the insulating film adhered to the chamber 201 and the evacuation path can be completely removed by in-situ cleaning.
[0027]
By the way, in Embodiment 1 described above, a material gas for in-situ cleaning is introduced into the chamber 201 and radical molecules are generated inside the chamber 201 to perform cleaning. However, the present invention is not limited to this. It is not limited. That is, even if radical molecules generated outside the chamber 201 are directly introduced into the chamber 201 to perform in-situ cleaning, the same effect as that of the first embodiment can be obtained.
[0028]
【The invention's effect】
As described above in detail, according to the present invention, a particle source generated in a process chamber during a film forming process using high-density plasma can be completely removed by in-situ cleaning. Therefore, according to the present invention, it is possible to prevent a source of particles from remaining in the process chamber or the evacuation path, and to increase the yield of the semiconductor device.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an outline of an insulating film forming apparatus using a conventional high-density plasma source.
FIG. 2 is a diagram illustrating an outline of a semiconductor manufacturing apparatus according to the first embodiment of the present invention;
FIG. 3 is a plan view of a valve body of a valve provided in the semiconductor manufacturing apparatus according to the first embodiment of the present invention.
[Explanation of symbols]
201 process chamber 202 wafer 203 susceptor 204, 208 RF power supply 205 RF introduction coil 206 bypass pipe 207, 212 valve 209 throttle valve 210 main valve 211 turbo molecular pump 213 dry pump 214 differential pressure generating valve 301 differential pressure generating hole

Claims (4)

A semiconductor manufacturing apparatus for forming an insulating film on a semiconductor wafer,
A process chamber for performing an insulating film formation process;
A vacuum pump for exhausting gas in the process chamber,
A pressure control valve disposed between the process chamber and the vacuum pump,
A main valve that shuts off the process chamber and the vacuum pump;
Providing a valve body having a predetermined opening, an opening and closing valve disposed between the process chamber and the vacuum pump,
A semiconductor manufacturing apparatus comprising: 2. The semiconductor manufacturing apparatus according to claim 1, wherein the on-off valve is arranged between the main valve and the vacuum pump. The semiconductor device according to claim 1, further comprising a control device that opens the open / close valve during a process of forming an insulating film and closes the open / close valve during in-situ cleaning. manufacturing device. The control device controls the pressure control valve so that the pressure in the process chamber is in a predetermined high vacuum state during the deposition process of the insulating film, and, at the time of in-situ cleaning, 4. The semiconductor manufacturing apparatus according to claim 3, wherein the pressure control valve is controlled so that the pressure in the process chamber is in a predetermined medium vacuum state.

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