Vacuum processing apparatus

There is a vacuum processing apparatus which can reduce the amount of foreign particle occurrence by enhancing the ease of maintenance of a gas diffuser installing portion in the vacuum processing apparatus. A gas diffuser chamber for accommodating a gas diffuser is installed in the vacuum processing apparatus.

CLAIM OF PRIORITY

The present invention claims priority from Japanese patent application JP 2008-149021 filed on Jun. 6, 2008, the content of which is hereby incorporated by reference into this application.

FIELD OF THE INVENTION

The present invention relates to a vacuum processing apparatus, and more particularly, to an installation configuration and an installation method of a gas diffuser in a semiconductor manufacturing apparatus.

BACKGROUND OF THE INVENTION

In manufacturing processes of semiconductor devices such as DRAMs or microprocessors, plasma etching and plasma CVD are widely used. One of the issues in the manufacturing processes of semiconductor devices is to reduce the number of foreign particles attaching to a sample to be processed. For example, in a semiconductor manufacturing apparatus for etching, if foreign particles fall on a fine pattern of a sample before etching, the region is locally hindered from being etched. This causes a failure such as breaking of wire and reduces the yield. On this account, there have been contrived a number of methods for preventing foreign particles from attaching to the sample in the semiconductor manufacturing apparatus and a semiconductor inspection apparatus for inspecting the sample in the course of the manufacturing process. For example, Japanese Patent Application Laid-Open No. 8(1996)-64582 describes a method for installing a gas diffuser to prevent the fly-off of foreign particles during venting in a lock chamber for switching between a vacuum and the atmosphere. In this context, the term “venting” refers to switching from a vacuum to the atmosphere by purging nitrogen gas or the like. The gas diffuser prevents a rapid gas flow in a specific direction, and is disclosed, for example, in Japanese Patent Application Laid-Open No. 8(1996)-64582.

SUMMARY OF THE INVENTION

In the lock chamber, the gas diffuser has to be so installed that a transfer arm or the sample does not touch the gas diffuser during the transfer of the sample. However, there is a tendency to minimize the volume of the lock chamber in order to reduce vent time and vacuuming time, which disadvantageously makes it difficult to secure enough space for accommodating the gas diffuser in the lock chamber. If the gas diffuser is installed in a minimal space where the distance between the gas diffuser and a wall surface is too small, there is a high risk that foreign particles attaching to the wall surface around the gas diffuser peel and fly off in the lock chamber due to the flow of supplied vent gas so that foreign particles attach to the sample.

Further, it is desirable to remove and thoroughly clean an area around the gas diffuser at the time of periodic wet cleaning (overhaul cleaning of swap parts). However, in most cases, the lock chamber itself is not designed to be cleaned by removal at the time of wet cleaning. Accordingly, in the case where the gas diffuser is installed directly in the lock chamber, it is not easy to clean the area around the gas diffuser in the lock chamber by ultrasonic pure water cleaning or the like at the time of periodic wet cleaning.

Further, from the viewpoint of preventing the fly-off of foreign particles during venting in a processing chamber, a gas diffuser may be installed also in the processing chamber. However, since ion and deposition radical or corrosive radical exist in the processing chamber, if the gas diffuser is installed in an exposed state in the processing chamber, the gas diffuser may be contaminated by these substances.

The whole of the gas diffuser disclosed in Japanese Patent Application Laid-Open No. 8(1996)-64582 is installed directly in the lock chamber through the use of a gas introduction pipe, which does not solve the above problems.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a vacuum processing apparatus which can reduce the amount of foreign particle occurrence by enhancing the ease of maintenance of a gas diffuser installing portion in the vacuum processing apparatus.

A representative example of the invention is a vacuum processing apparatus comprising a lock chamber capable of switching between an atmosphere and a vacuum; a vacuum transfer chamber; and a vacuum processing chamber, wherein the vacuum processing apparatus further comprises a gas diffuser for venting the lock chamber, and a dedicated chamber for accommodating the gas diffuser only, wherein the dedicated chamber is removably connected to the lock chamber.

According to the invention, it is possible to facilitate the maintenance of a gas diffuser installing portion and reduce the occurrence number of foreign particles.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to a representative embodiment of the present invention, in a semiconductor manufacturing apparatus including a processing chamber, a vacuum transfer chamber, a lock chamber, and an atmospheric transfer chamber, a gas diffuser chamber for accommodating a gas diffuser is connected to the lock chamber. According to another embodiment, two gate valves are installed at a connection port for connecting the processing chamber with the vacuum transfer chamber, and a gas diffuser is installed in an area sandwiched between the two gate valves. Hereinafter, referring to the accompanying drawings, embodiments of the invention will be described taking a plasma processing apparatus as an example.

First Embodiment

FIG. 1is a top view showing the general configuration of a plasma processing apparatus. In the plasma processing apparatus, four plasma processing chambers60(60-1to60-4) are connected to a vacuum transfer chamber61. The vacuum transfer chamber61and an atmospheric transfer chamber63are connected to each other through two lock chambers65(65-1,65-2) capable of switching between the atmosphere and a vacuum. For example, the lock chambers65-1is a load lock chamber, and the lock chambers65-2is used as an unload lock chamber. The load lock chamber is used in transferring a sample from the atmospheric transfer chamber to the vacuum transfer chamber, whereas the unload lock chamber is used in transferring a sample from the vacuum transfer chamber to the atmospheric transfer chamber. As a matter of course, each lock chamber may be used as both the load lock chamber and the unload lock chamber. In the atmospheric transfer chamber63, a wafer aligner66for detecting the center and the notch position of a sample2is installed. Further, a wafer station67for accommodating front opening unified pods (FOUP)68for storing wafers is connected to the atmospheric transfer chamber. Further, a computer39for controlling the whole of the plasma processing unit is installed. Further, gas diffuser chambers85(85-1and85-2) for accommodating gas diffusers are connected to the lock chambers65-1and65-2, respectively. Furthermore, gas diffuser chambers85(85-3and85-6) for accommodating gas diffusers are installed near the respective connection ports between processing chambers60(60-1to60-4) and the vacuum transfer chamber61. Furthermore, a gas diffuser chamber85-7for accommodating a gas diffuser is installed above the vacuum transfer chamber61.

Next, the configuration of a pumping system and a vent gas supply system of a lock chamber will be described with reference toFIG. 2.FIG. 2is a schematic longitudinal sectional view of the lock chamber65-1. Gate valves70-1and70-2are provided at respective connection ports for connecting the lock chamber65-1with the atmospheric transfer chamber63and the vacuum transfer chamber61. Although not shown, a gas diffuser chamber for installing a gas diffuser84at an outer surface of the lock chamber65-1is removably fixed to a wall surface perpendicular to side faces where the gate valves70-1and70-2are installed. In the lock chamber65-1, a vacuum pumping system45for depressurizing the lock chamber and a vent gas supply system46for supplying vent gas during venting are installed. In this context, the term “venting” refers to switching from a vacuum to the atmosphere by supplying gas such as nitrogen. The vent gas refers to gas that is supplied during venting. The vacuum pumping system45is composed of a slow open valve52-1and a dry pump42. The slow open valve is a valve that can adjust the open speed of a valve element, and has the effect of easing rapid depressurization of the lock chamber by slowly opening the valve at the start of vacuuming. The vent gas supply system46is composed of a regulator53for reducing the pressure of vent gas such as nitrogen gas supplied from the source (not shown) of the vent gas, a valve52-2, and the gas diffuser84. Further, a pressure gauge54for measuring pressure is provided in the lock chamber. The vacuum pumping system45and the vent gas supply system46are controlled by the computer39.

Next, the gas diffuser chambers85which are dedicated chambers for accommodating gas diffusers will be described with reference toFIGS. 3 to 6. The following description will be made by taking as an example the gas diffuser chamber85-1connected to the lock chamber65-1.FIG. 3is a schematic view sterically showing the gas diffuser chamber connected to the lock chamber.FIG. 4is a schematic sectional view of the gas diffuser chamber.FIG. 5is a schematic sectional view in which the gas diffuser is removed from the gas diffuser chamber and the gas diffuser chamber is removed from the lock chamber.FIG. 6is a perspective view showing the configuration of a flange and the gas diffuser removed from the gas diffuser chamber.

As shown inFIG. 3, the gas diffuser chamber85-1is fixed to a lateral surface of the lock chamber65-1. The slender cylindrical gas diffuser84is installed in the gas diffuser chamber85-1along the lateral surface of the lock chamber65-1. A space within the gas diffuser chamber85-1is connected to a space within the lock chamber65-1through a connection port47-1provided on the lock chamber65-1. The height and width of the gas diffuser chamber85-1are smaller than the height and width of the lock chamber65-1. Further, the top face of the lock chamber65-1can be opened and closed for maintenance. On the top face of the lock chamber65-1, there is provided a transparent window (not shown) for observing the state of a wafer.

InFIGS. 4 and 5, the gas diffuser chamber85-1has approximately the same height as the transfer path of the sample (e.g., wafer)2including the gate valves70-1and70-2, and is provided thereoutside. The gas diffuser chamber85-1is fixed to the lock chamber by a screw96-1with an O-ring91-1in between. That is, the gas diffuser chamber can be removed from the lock chamber by removing the screw96-1. Further, the gas diffuser84can be removed from the gas diffuser chamber by removing a screw96-2.

As shown inFIG. 6, the gas diffuser84is connected to a stainless steel (SUS) pipe87passing through a flange86. The opposite end of the SUS pipe87passing through the flange from the gas diffuser can be connected to a pipe59of the vent gas supply system by a gas pipe connection unit94such as VCR connection. The flange86is screwed into the gas diffuser chamber85-1, thereby installing the gas diffuser84in the gas diffuser chamber. There is an O-ring groove on the flange86, and an O-ring91-2is mounted therein. InFIG. 6, the surface of a portion of the gas diffuser84indicated by reference numeral84X is a porous body. Gas is so supplied as to ooze through the porous body84X, which can prevent a rapid gas flow in a specific direction.

Next, referring toFIG. 7, description will be made as to the merits of the configuration in which the gas diffuser chamber85for accommodating the gas diffuser84is connected to the lock chamber and the gas diffuser chamber and the gas diffuser are removable.FIG. 7is an operation explanatory view simplifying the lock chamber65-1and the gas diffuser chamber85shown inFIG. 4. It is almost impossible for existing cleaning techniques to bring about a state where foreign particles completely do not attach to the inner surfaces of the lock chamber and the gas diffuser chamber. Further, at actual mass production sites, the sample sometimes brings foreign particles into the lock chamber65-1when transferred into the lock chamber. For this reason, in most cases, foreign particles gradually accumulate in the lock chamber with operations, and the contamination level deteriorates.

FIG. 7shows a contaminated state where such foreign particles80attach to the inner walls by operations. Further, solid arrows indicate blowout directions of vent gas supplied from the gas diffuser. In this case, for example, foreign particles80attaching to the right side (R-B area) of the lock chamber inFIG. 7are far from the gas diffuser84; accordingly, the risk that these foreign particles peel off the inner wall and fly off during venting is small. On the other hand, for example, foreign particles80attaching to the left side (R-A area) of the lock chamber inFIG. 7are close to the gas diffuser84; accordingly, vent gas supplied from the gas diffuser strikes these foreign particles. Although the gas diffuser relieves a rapid gas flow, there is a risk that foreign particles attaching to a wall very close to the gas diffuser peel and fly off due to a vent gas flow. For example, as shown by dotted arrows inFIG. 7, foreign particles80attaching to inner walls around the gas diffuser84may peel off and attach to the wafer2. Accordingly, it is desirable to periodically clean the inner walls around the gas diffuser84. If the gas diffuser is installed directly in the lock chamber, there arises a need to clean the lock chamber itself. However, in general, the lock chamber itself is not constructed to easily removed for cleaning at the time of periodic maintenance; therefore, it is difficult to clean the inner walls around the gas diffuser.

On the other hand, as in the invention, if the gas diffuser chamber85is installed to the lock chamber65-1and can be easily removed from the lock chamber, there is a merit that the gas diffuser chamber can be periodically cleaned by ultrasonic pure water cleaning or the like. Further, the gas diffuser84can be easily cleaned.

Next, inFIGS. 8A and 8B, a comparison will be made between the case (FIG. 8A) where the gas diffuser84in the gas diffuser chamber85is installed to the lock chamber65as in the invention and the case (FIG. 8B) where the gas diffuser84is installed directly in the lock chamber65as in conventional techniques such as Japanese Patent Application Laid-Open No. 8(1996)-64582. To simplify the description, in the example ofFIG. 8A, the gas diffuser chamber85is installed over the lock chamber. As seen in the example ofFIG. 8B, to install the gas diffuser84over the sample2, the height of the lock chamber65has to be increased. In this case, the volume Vb of the lock chamber65ofFIG. 8Bis larger than the volume Va of the lock chamber65ofFIG. 8A, which requires longer time for venting or vacuuming and disadvantageously reduces the throughput of the lock chamber. Thus, with the use of the gas diffuser chamber85, there is the merit of minimizing an increase in the time required to vacuum or vent the lock chamber. According to the invention, in an apparatus for processing a 12-inch wafer as an example, the inner width of the lock chamber65is about 350 mm, whereas the inner height of the lock chamber65is as small as about 30 mm, which leads to a reduction in the volume of the lock chamber and can reduce the time required to vacuum or vent the lock chamber.

Next, the size of the connection port47-1for connecting the gas diffuser chamber85with the lock chamber65will be described with reference toFIG. 4. As described above, the space within the gas diffuser chamber85-1is connected to the space within the lock chamber65-1through the connection port47-1. It is desirable that the size of the connection port be as large as possible in order to slow the flow velocity of vent gas around the connection port. The size of the connection port47-1is substantially expressed by the following equations (1) and (2).
WA>0.5×La(1)
HB>0.5×Db(2)

where, WA inFIG. 3denotes the width of the connection port, HB inFIG. 3denotes the height of the connection port, La inFIG. 4denotes the length of the gas diffuser, and Db inFIG. 4denotes the diameter of the gas diffuser. Further, LC inFIG. 4denotes the distance between the gas diffuser and a wall surface close to the gas diffuser. If LC is too small, foreign particles attaching to the wall close to the gas diffuser peel and fly off due to the force of gas blowing from the gas diffuser. For this reason, in general, it is desirable that LC be 5 mm or larger. The LC of 5 mm or larger is based on the condition that the diameter Db of the gas diffuser is about 10 to 20 mm, the length La is about 100 to 300 mm, and the gas supply quantity is about 40 to 200 L/min. In the case where, for example, the gas blow-out area of the gas diffuser is smaller or the gas supply quantity is larger, LC has to be larger, e.g., 10 mm or larger.

In the example ofFIGS. 1 to 4, the gas diffuser84is installed parallel to the wafer surface, that is, installed laterally as viewed from the wafer surface, and the connection port47-1between the gas diffuser chamber and the lock chamber is oblong. With this, the velocity of gas flowing from the gas diffuser chamber to the lock chamber is made as slow as possible.

Further, by connecting the dedicated chamber for accommodating the gas diffuser to the side face of the lock chamber65, the top face of the lock chamber can be opened and closed. Thereby, since the dedicated chamber does not block the opening and closing of the top face of the lock chamber, there is the merit of facilitating the maintenance of the lock chamber itself.

As described above, according to this embodiment, the dedicated chamber for accommodating the gas diffuser can be easily removed and cleaned, and the ease of maintenance around the gas diffuser is enhanced, which facilitates cleaning for reducing foreign particles.

Second Embodiment

A second embodiment of the invention will be described with reference toFIGS. 9A and 9B.FIG. 9Ais a longitudinal sectional view, andFIG. 9Bis a plan view. If it is not possible to secure the connection port47-1of large size as in the first embodiment, it is possible to secure a connection port as shown inFIGS. 9A and 9B. That is, a connection port47-1for connecting the gas diffuser chamber85is opened on the bottom face of the lock chamber65and in the corner outside the periphery of the wafer2.

According to this embodiment as well, the dedicated chamber for accommodating the gas diffuser can be easily removed and cleaned, and the ease of maintenance around the gas diffuser is enhanced, which facilitates cleaning for reducing foreign particles. However, in this embodiment, the size of the connection port47-1has to be smaller than that ofFIG. 4. Accordingly, the flow velocity of vent gas at the connection port becomes higher, so that there is the demerit of increasing the risk of the fly-off of foreign particles.

Third Embodiment

A third embodiment of the invention will be described with reference toFIGS. 10 and 11. In this embodiment, the gas diffuser84is installed over the lock chamber65. In the example ofFIG. 10, a transparent window74inside which a connection port47is provided is installed over the lock chamber65, and the gas diffuser chamber85is installed over the transparent window74. It is possible to check an inner state of the lock chamber65through the transparent window74. The specific configurations of the gas diffuser84and the gas diffuser chamber85are basically the same as those of the first embodiment.

According to this embodiment, the ease of maintenance around the gas diffuser is enhanced, which facilitates cleaning for reducing foreign particles.

This embodiment has the same effect in preventing the fly-off of foreign particles as the first embodiment (FIG. 4), but there is the demerit of reducing the effective area of the window. It is desirable that the window74can be opened during maintenance etc. as shown inFIG. 11. In the example ofFIG. 11, the illustration of the gas diffuser etc. is omitted. Further, even in the case of no transparent window, it is desirable that the top face of the lock chamber can be opened. Accordingly, in the case where the gas diffuser chamber is installed over a top lid or a top window, there is a possibility of occurrence of a need to remove a gas line59for supplying vent gas to the gas diffuser every time the top lid or window is opened.

Fourth Embodiment

A fourth embodiment of the invention will be described with reference toFIGS. 12 and 13. In the case where the gas diffuser is installed over the top window74, it is also possible to employ a flat-type gas diffuser84having a flat surface through which gas blows.FIGS. 12 and 13show this example.FIG. 12is a perspective view sterically showing the lock chamber ofFIG. 13. The window74is fixed over the lock chamber65through the use of a frame75. In the center of the window, there is a hole of diameter Dj as a connection port. A flat-type (plate-type) gas diffuser84is fixed over the window74with screws96-4. InFIG. 13, reference numeral84X denotes a porous body, and reference symbol Dk denotes the diameter of the exposed portion of the porous body. Further, arrows denote the flow of vent gas. As a matter of course, it is desirable to satisfy the following equation (3).
Dj≧Dk(3)

According to this embodiment, the ease of maintenance around the gas diffuser is enhanced, which facilitates cleaning for reducing foreign particles. However, since the gas diffuser is also installed over the window, there are the demerit of reducing the effective area of the window and the demerit that there is a possibility of occurrence of a need to remove a vent gas line59from the gas diffuser at the time of opening the window.

Fifth Embodiment

Next, description will be made as to a method of installing a gas diffuser on a plasma processing chamber60side as a fifth embodiment of the invention. Since plasma is generated in the processing chamber, it is undesirable that the gas diffuser be installed in a directly exposed state in the processing chamber. This is because there is a risk of contaminating the gas diffuser due to ion irradiation and deposition or corrosive radical irradiation.

For this reason, except in the case of venting the plasma processing chamber for wet cleaning (overhaul cleaning of swap parts) or the like, it is desirable that the gas diffuser be installed in an enclosed space other than the space within the processing chamber to avoid plasma irradiation. In this invention, two gate valves are installed at a connection port between a vacuum processing chamber and the vacuum transfer chamber, and a gas diffuser chamber is installed in a space enclosed by the two gate valves.FIGS. 14 and 15show this configuration.

FIG. 14is a schematic sectional view showing a configuration around the gate valves installed at the connection port between the processing chamber60-1and the vacuum transfer chamber61.FIG. 15is a longitudinal sectional view taken along line A-A ofFIG. 14.

In the vacuum processing apparatus, two gate valves70-3and70-4are installed at a connection port (connection space)47-3for connecting the vacuum processing chamber60-1with the vacuum transfer chamber61. That is, there are provided a first gate valve70-4which forms a part of a side wall of the vacuum processing chamber60-1, a second gate valve70-3which forms a part of a side wall of the vacuum transfer chamber61, and a cylindrical gas diffuser84for venting the vacuum processing chamber, and the gas diffuser84is installed in the connection space (connection port) sandwiched between the two gate valves. Further, a mounting electrode4for mounting the sample2is moved up and down by an up-and-down drive mechanism73. A shower plate5is installed under an antenna3through a gas dispersion plate, and processing gas is supplied into the processing chamber through gas holes (not shown) provided in the shower plate5. Reference numeral41denotes a turbo-molecular pump;43, a butterfly valve unit; and83, an inner case. The connection port47-3for accommodating the gas diffuser84is located at approximately the same height as the mounting electrode4, and the gas diffuser84is located at a position slightly higher than the transfer surface of the sample2. The gas diffuser84is installed in a direction perpendicular to the transfer direction of the sample2.

The gate valve70-3adjacent to the vacuum transfer chamber is a valve for pressure-wise isolating the vacuum transfer chamber from the processing chamber, and has the function of keeping the vacuum transfer chamber under vacuum even if the processing chamber is opened to the atmosphere. On the other hand, the gate valve70-4is also called a process valve. The gate valve70-4allows the processing chamber to be axisymmetric in terms of high-frequency power for generating plasma, and the gate valve element is shaped like an arc as viewed from above. With this configuration, the inner surface of the inner case83and the surface of the process valve70-4adjacent to the processing chamber exist on the circumference of a circle.

This process valve70-4also has the effect of preventing contamination by deposition radical or corrosive radical around the port for connecting the vacuum transfer chamber with the processing chamber. By closing the process valve, the space of the connection port47-3is protected against contamination by deposition radical or corrosive radical. Accordingly, it is desirable that the gas diffuser be installed in this area. That is, when the processing chamber is vented, vent gas is supplied from the gas diffuser with the process valve70-4opened and the gate valve70-3closed, thereby returning the processing chamber to the atmosphere.

This embodiment can provide the vacuum processing apparatus having less frequency of maintenance.

In the case where the cross section of the connection port47-3is small, that is, the height is small so that the gas diffuser cannot be installed, as shown inFIG. 16a gas diffuser chamber85-3communicated with the connection port is installed over the connection port47-3(the transfer path of the sample2), thus securing a space for accommodating the gas diffuser84.

In the plasma processing apparatus shown inFIG. 1, all of the gas diffuser chambers85(85-1to85-7) and the gas diffusers84incorporated therein do not need to have the same structure, and each of the embodiments can be applied thereto as appropriate.

The invention is applicable not only to the etching processing apparatus described in each embodiment, but also to general vacuum processing apparatuses which transfer samples while supplying vent gas, e.g., a plasma CVD apparatus and a semiconductor inspection apparatus using a CD-SEM (critical dimension scanning electron microscope) or the like.