KR950012906B1 - Semiconductor manufacturing apparatus - Google Patents

Abstract

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Description

Semiconductor manufacturing device

1 is a cross-sectional view of a conventional vertical reactor,

2 is a cross-sectional view of a conventional suitable plasma CVD apparatus disclosed in the above-mentioned Japanese Patent Publication No. 59-145531,

3 is a front view of a conventional plasma CVD apparatus,

4 is a front view of another embodiment of a conventional plasma CVD apparatus,

5 is a cross-sectional view of an embodiment of a vertical thermal reactor with a ring reactor body according to the invention,

6 is a front view of a vertical thermal reactor mainly illustrating the reaction tube and wafer of FIG. 5;

7 is a front view of a vertical thermal reactor showing self-cleaning by applying an R.F voltage between adjacent electrodes in accordance with one embodiment of the present invention,

8 is a front view of a vertical thermal reactor illustrating wafer cleaning by applying an R.F voltage between an outer electrode and an inner electrode,

9 is a cross-sectional view of a vertical reactor according to another embodiment of the present invention,

10 is a front view of the ninth reactor,

11 is a perspective view of a vertical reactor of another embodiment,

12 is a perspective view of a vertical reactor of yet another embodiment,

13 is a front view of a wafer holder of another embodiment,

FIG. 14 is a cross-sectional view of the FIG. 13 wafer holder,

15 is another embodiment of the wafer holder,

16 is a wafer holder portion of yet another embodiment.

The present invention relates to an apparatus for manufacturing a semiconductor device. In particular, the present invention relates to an apparatus for heat treatment of semiconductor wafers in a vertical furnace.

In the manufacture of a semiconductor device, a plurality of heat treatments are performed. Examples include thermal oxidation, diffusion, vapor phase growth, and chemical vapor etching. These treatments were conventionally performed using a transverse quartz tube. For horizontal quartz tubes, it provides high production rates. In other words, many semiconductor wafers are processed immediately. However, there is a tendency to use large wafers. Therefore, the quartz tube must have a larger diameter. This raises a problem of maintaining an even temperature distribution in the vertical direction with respect to the transverse tube.

Typically the top of the tube has a slightly higher temperature. Moreover, the large wafer means increases the overall weight of the boat on which these large wafers are placed.

This also causes other problems with the entry and exit of the boat. Conventionally, a modified bar has been attached to the boat and this bar has been processed for operation. This bar tends to bow because the weight of the boat increases.

Recently, vertical reactors are also used to save indoor space. In order to install a plurality of wafers, the height of the vertical reactor is increased. However, there are limitations to the ceiling of clean rooms, which limits the number of wafers that can be set in a vertical reactor.

One example of a vertical reactor is disclosed in US Pat. No. 4,062,318, where each wafer is placed on each surface of a carbon susceptor. This vertical reactor is currently manufactured by US and foreign manufacturers.

United States Application No. 017,693, assigned to the applicant, discloses another example of a vertical reactor with a plurality of plasma cleaning electrodes.

Other examples of the reactor are shown in Japanese Patent Laid-Open Nos. 59-145531 and 54-56366. These publications disclose primarily plasma CVD apparatus in which the wafer lies vertically on a wafer holder in a cylindrical reactor body.

The front view of the wafer has a spoke shape. The reaction gas is supplied at the center of the cylindrical reactor. Heating is provided by a lamp provided outside the reactor,

It is an object of the present invention to provide a longitudinal thermal reactor having a ring reactor body having a uniform temperature distribution over a plurality of semiconductor wafers.

Another object of the present invention is to provide a vertical thermal reactor with a self-cleaning plasma electrode.

Still another object of the present invention is to provide a ring reactor having a gas outlet at its upper end.

According to the present invention, a ring reactor is used to vertically arrange a plurality of semiconductor wafers. The front view of the wafer in the ring reactor is spoke-shaped. The wafer ring is placed on a wafer holder.

Other wafer holders can be used to load onto wafer holders for setting more wafers in a ring reactor. The wafer stack is rotatable in a ring reactor using a motor provided outside the reactor.

Heating means are provided to surround the reactor body and other heating means are provided in the center of the ring reactor. These heating means provide a uniform temperature distribution in the horizontal direction in the ring reactor.

The reaction gas is supplied from the bottom of the ring reactor and output to the top of the ring reactor. These gases are fed from bottom to top and the gas flows parallel to the surface of each wafer. Such wafer placement and gas flow provide a smooth flow of gas and a uniform distribution of reactants of the reactant gas. It also provides higher wafer production rates in one process.

According to the present invention, a plurality of plasma generating electrodes are disposed on the outer circumferential surface of the reactor and the hollow portion of the ring reactor. High frequency is applied to the electrode to generate plasma during the introduction of the etching gas.

This plasma etches away materials attached to the inner surface of the ring reactor during the reaction. When high frequency is applied between electrodes located on the outer circumferential surface, the plasma is mainly etched away to remove only the material attached to the inner surface of the reactor.

When a high frequency is applied between the main portion and the center portion, the plasma is removed by etching the material attached to the wafer surface. This allows self-cleaning of large reactors in order to be suitable for large wafers.

The above objects and the present invention are described in detail below with reference to the drawings and preferred embodiments.

First, the prior art will be described with reference to FIGS. 1 to 4.

1 is a cross-sectional view of a conventional vertical reactor.

In this figure, the heating means 1 consists of an electric heater 1b, and the lid 1a of the furnace is attached so as to surround the outer surface of the vertical crystal tube 8. The tube 8 has an inlet 10 at the top of the tube and the reaction gas “g” is introduced from the inlet 10. This tube has a lower end connected to a metal susceptor with a gas outlet 9b.

A plurality of semiconductor wafers 3 are placed on the wafer holder 2 and the wafer holders 2 are set on the support means 4 rotatable by the motor 6. The vacuum flange 7 is connected to the lower end of the metal susceptor. The support means 4 and the vacuum flange 7 are movable in the vertical direction as shown by the arrow.

Appropriate gas is introduced from the inlet port 10 during the heat treatment. In a typical example of vapor phase growth, some reaction product is also deposited on the inner surface portion of the tube near the outlet 9b.

This reaction product is unstable and can easily be stripped off by the airflow that may occur during wafer loading into or out of the tube. Reaction products called by airflow adhere to the surface of the wafer causing contamination of the wafer.

Furthermore, it is necessary to clean the tubes after several treatment cycles. Since this tube is large in vertical length, it is difficult to separate the large tube and wash the large tube.

2 shows a suitable conventional plasma CVD apparatus disclosed in Japanese Patent Publication.

In FIG. 2 the bell-shaped terminal 11 has a gas discharge pipe 13 which is connected to a vacuum pump 12. The rotating shaft 14 is provided in the load core part.

The rotating shaft 14 is driven by a motor not shown in this figure. The disk susceptor 15 is attached to the upper end of the rotating shaft 14. The inlet 16 is connected to a conduit 17 in the tube of the rotating shaft 14.

Conduit 17 is connected to a gas controller 18 that controls the reaction gas. A donor shaped ring 19 is located on the top surface of the susceptor 15 which has a number of trenches 20 as indicated in the front view of FIG.

Each wafer 21 is set in the trench 20 at its outer periphery. Bell-shaped jar cover 24 is composed of a top cover 23 and a cylindrical body 22 covering the entire bell-shaped jar body (11).

The pair of electrodes 25 and 26 are firmly fixed to the upper cover 23 and are connected to the high frequency generator 27. The cylindrical body 22 is made of transparent crystal and the heating lamp 28 is installed outside the cylindrical body 22 to heat the wafer 21.

4 shows another example of the apparatus for generating plasma electrodes 30 and 31 inside the wafer ring.

5 is a cross-sectional view of an embodiment of a vertical thermal reactor with a ring reactor body according to the present invention.

The same numbers as used in FIG. 5 in FIG. 5 represent the same objects as in FIG.

5 indicates a rotating shaft.

OR stands for full vacuum ring.

8a is the top ring of the ring reactor body 8, 8b is the open end of the body 8 and 8c is the recessed portion in the center of the body 8.

1c is a supplemental heat source.

The electric heater 1b and the supplemental heat source 1c set a uniform temperature distribution in the longitudinal direction of the body as set in the conventional vertical reaction tube shown in FIG.

According to one aspect of the invention the longitudinal heat reactor 8 consists of a ring reactor body which means a cylindrical body with a cavity along its center such that a supplemental heat source is provided therein.

A centered crystal reactor is used as shown in this embodiment of FIG. 5.

The wafer 3 stands on a ring wafer holder 2 and is excreted in a spoke shape as shown in FIG. The wafer holder 2 is mounted on the support means 4 connected to the support shaft 5.

The wafer holder 2 has the shape of a so-called flower basket and is see-through so that the reaction gas passes easily. The wafer holder 2 may have one or more stacks. Two stacks are shown in the embodiment of FIG.

As shown in FIG. 5, the wafer holder 2 is set in the ring-shaped reaction body 8 and rotated to improve reaction uniformity when any process is performed. At least one reaction gas is introduced at inlet 10.

In this example the inlet 10 is placed on the bottom plate of the vacuum flange 7 and faces the stage 9a of the outlet 9b. In use, the outlet 9b is connected to a vacuum system such as a rotary pump and the reactant gas introduced at the inlet 10 provides the reactant and the reactants are distributed to all wafers and finally from the outlet 9b through the stage 9a. Discharged.

Here the conduit 9 between the stage 9a and the outlet 9b is located in an isothermal space provided by a pair of heaters 1b and 1c such that no reacted material is deposited.

As described above, thermal processes in a vertical reactor include chemical vapor deposition, chemical vapor etching, gas diffusion and thermal oxidation.

As is known, SiO ₂ , SI ₃ N ₄ and other glass films are formed using silane or other suitable gas source. To this end, the inlet 10 is provided with one or more. Multiple gas sources are used in gas diffusion. Some types of gas require preheating of the gas.

When using this kind of gas the inlet 10 can be located at the bottom of the recessed part 8c and the conduit extending from the outside to the inlet 10 located at the bottom is also located in the preheating space. do.

In the embodiment of Fig. 5, a supplemental heat source 1c is provided. The supplemental heat source 1c may be an electric heater or an indirect heater such as a heat absorber to emit heat.

The indirect heater may be composed of a heat reflector. One of these heat sources is chosen taking into account the thermal balance design.

A second feature of the invention is that multiple plasma generating electrodes 51 can be arranged on the surface of the ring reactor 8. The plasma generating electrode 51 is arranged to cover the outer cylinder surface and the inner pressing surface. The electrode 51 is included in the insulating tube 52 and a suitable inert gas may be filled in the space between the electrode and the tube 52 if necessary. Tube 52 may be constructed of quartz.

The high frequency power source 53 generates a radio frequency that generates plasma inside the reactor 8 when a suitable cleaning gas is introduced into the reactor 8 after several deposition cycles. The cleaning gas is selected from known gases such as chloride and fluoride in the plasma etching field.

The electrodes 51 are connected in either manner as shown in FIGS. 7 and 8.

In FIG. 7 the R.F voltage is applied between adjacent electrodes, in which case plasma 54 mainly occurs along the inner wall of the reactor to clean the inner wall without separating the reactor. Therefore, adjustment is very easy.

In FIG. 8, the R.F voltage is applied between the inner electrode and the outer electrode, in which case plasma 54 occurs across the inner space of the reactor to clean the wafer 3 and / or the wafer holder 2. The connection of the electrodes can be changed on the cone or on the operating panel and an appropriate connection is selected on the panel for cleanliness.

The electrodes shown in Figs. 7 and 8 are made in a rod shape. The plate or mesh may be used as the electrode 51.

When operating the vertical thermal reactor of the present invention, the same process as the conventional vertical reactor is used except for the above gas flow.

According to the last feature of the invention, a conduit 9 is introduced in the isothermal space in which the reaction gas is introduced from the bottom of the reactor to the top of the reactor and connects the top 9a and the actual outlet 9b. Therefore, unstable deposition does not occur at the top 9a and the conduit 9. The actual outlet 9b is very far from the top 9a.

As a result, unnecessary particles do not adhere to the wafer during degassing or during vacuuming. The airflow during these operations is strong enough to strip off any reactants adhering on the inner wall of conventional vertical reaction tubes. However, this problem does not arise in the present invention.

The top 9a is also one or more openings. In other cases, the upper end 9a may have a circular shape.

9 is a cross-sectional view of a vertical reactor according to another embodiment of the present invention. The vertical reactor of FIG. 9 has basically the same structure as the conventional vertical reactor of FIG.

The first difference is the shape of the exhaust system, which consists of an inlet 10, an upper end 9a and an actual outlet 9b. The purpose and effects of conduit arrangements in isothermal space have already been mentioned.

The upper portion 8a of the reactor comprising the top 9a as described above is in an isothermal space of the vertical reaction tube and the reacted material has the same uniformity as that attached to the wafer and on the inner surface around the upper portion 8a. The attached material has the same adhesive force.

Therefore, peeling off the attachment is not easy. However, the actual outlet 9b is far from the top 9a and the temperature around the outlet 9b is reduced, so that the film properties are not uniform and the attachment is not easily peeled off.

According to the structure of the present invention the top 9a is very far from the actual outlet 9b and spatially separated. Therefore, unstable deposits do not flow on the wafer. The conduit 9 can be fixed to the outer surface of the reactor by dissolving the crystal.

The configuration applies equally to horizontal reactors.

10 is a top view of the reactor of FIG.

According to the present invention, a plasma generating electrode 51 is provided. The electrode 51 is almost the same as for the electrode of FIGS. 5-8.

9 and 10, the R.F power source is connected between adjacent electrodes to clean the inner wall of the reactor. A constant vacuum level in the reactor is required for plasma generation. When the R.F power source is connected between the counter electrodes, plasma is generated in the reactor and in this case the wafer and / or wafer holder can be cleaned.

The top 9a can also have a variety of shapes to establish the original flow of reaction gas. For this purpose the top 9a has 3 or 4 openings as shown in FIGS. 11 and 12. Arrows in these figures indicate the flow of reaction gas.

13 and 14 show a wafer holder 2 of another embodiment.

FIG. 13 is a partial perspective top view of the wafer holder 2 and FIG. 14 is a sectional view of the wafer holder 2 of FIG.

The wafer holder 2 is composed of quartz, and a plurality of wafers 3 are located between a pair of quartz ring portions as shown in FIGS. 13 and 14. The wafer holder 2 is provided with a top circular correction flange 55.

When adjusting the wafer holder, adjustment means are inserted from the central opening of the flange 55. The wafer holder is then pulled up by hanging up the flange 55.

15 is a top view of a portion of a wafer holder of yet another embodiment.

16 illustrates another embodiment of a wafer holder. In both figures a plurality of insert plates 56 are provided.

The wafer holder of FIG. 15 is suitable for the deposition of polycrystalline silicon and silicon nitride. In these reactions, the chemical reaction depends on the reaction rate and is not controlled by the distance between adjacent wafers. However, in silicon dioxide deposition, for example, the chemical reaction is determined by the feed rate and mainly controlled by the amount of gas supplied.

Wafer spacing is important for uniform deposition or etching in these reactions, so inserter 56 of FIG. 16 is provided to keep wafer spacing uniform.

In the above, the present invention has been described with reference to specific examples. However, the present invention is not limited to the above specific examples, and many variations and modifications may be made in accordance with the spirit and concept of the present invention.

Claims (6)

A longitudinal thermal reactor for processing a plurality of semiconductor wafers therein, the vertical thermal reactor having a vertically extending cylindrical outer surface, having a depression at the center of the body along the longitudinal center axis of the body, thereby reducing the longitudinal direction of the body. The body and the cross section form a ring-shaped inner space, a ring-shaped reactor body having an open bottom end and a closed top, a gas inlet for introducing a reaction gas into the inner space of the body, the for drawing the reaction gas An opening installed in the closed upper part, an outlet for discharging the reaction gas from the reactor body, a conduit connecting the opening to the outlet located along the outer surface of the reactor body, setting an isothermal space in the inner space of the body And a heating means surrounding the outer surface of the reactor body and the depression in the body Additional heating means, a plurality of plasma generating electrodes located on the outer surface and the depression to generate plasma in the inner space to perform cleaning of the inner wall of the reactor body, the reaction body and the inner when heat treatment is performed A wafer holder for mounting a plurality of semiconductor wafers, a support means for mounting the wafer holder thereon, fixed to the support means to rotate the wafer holder in the ring-shaped inner space of the reactor body And a drive means for rotating the rotatable shaft. The longitudinal thermal reactor of claim 1, wherein the wafer holders are at least one and stacked on each other. The vertical thermal reactor according to claim 2, wherein the heat treatment is one of gas phase growth, diffusion, thermal oxidation, and chemical vaporization. A vertical thermal reactor for processing a plurality of semiconductor wafers therein, the vertical thermal reactor having a vertically extending outer surface and having a central portion at the center of the body along a central axis in the longitudinal direction of the body thereby The body and the cross section form a ring-shaped inner space, a cylindrical reactor body having an open bottom end and a closed upper portion, a gas inlet for introducing a reaction gas into the inner space of the body, the for drawing the reaction gas An opening installed in a closed upper portion, an outlet for discharging the reaction gas from the reactor body, a conduit for connecting the opening along the outer surface portion of the reactor body and connecting the outlet to an isothermal space within the inner space of the body To the heating means and the body surrounding the outer surface of the cylindrical reactor body. Additional heating means inserted into the hollow portion, a plurality of plasma generating electrodes located on the outer surface portion and the hollow portion to generate a plasma in the inner space to perform cleaning of the inner wall of the reactor body, when heat treatment is performed A wafer holder for mounting a plurality of semiconductor wafers located in the isothermal space of the inner space of the reactor body, support means for mounting the wafer holder thereon, fixed to the support means in the ring-shaped inner space of the reactor body And a rotatable shaft for rotating the wafer holder, and drive means for rotating the rotatable shaft. 5. The longitudinal thermal reactor of claim 4, wherein the wafer holders are at least one and stacked on each other. The vertical thermal reactor according to claim 4, wherein the heat treatment is selected from one of gas phase growth, diffusion, thermal oxidation, and chemical vaporization.

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