JPH0745533A - Vertical type cvd equipment - Google Patents

Abstract

PURPOSE:To provide a vertical type CVD equipment wherein uniformity of intersurface distribution of film quality is improved and compact structure is realized. CONSTITUTION:A wafer boat 36 in which wafers A are mounted on multistage in the vertical direction is loaded in a furnace core pipe 16, into which reaction gas is introduced. Vapor growth reaction is performed at a high temperature and a thin film is formed on the wafer surface. The wafer boat 36 which is loaded in the equipment is constituted by stacking units 38 which can be divided for each wafer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical CVD apparatus used in a thin film forming process for manufacturing semiconductor chips, and more particularly to a film thickness of a thin film formed on a wafer in a thin film forming process by a vapor phase growth reaction. And a vertical CVD apparatus improved so that the inter-plane distribution of film quality becomes uniform. In the present specification, the film quality of the thin film and the inter-plane distribution of the film thickness are
The difference in film quality and the film thickness between the wafers for each batch is referred to, and the uniform inter-plane distribution means that the difference between the wafers is small.

[0002]

2. Description of the Related Art In a semiconductor manufacturing process, a batch type vertical CVD apparatus is widely used as a CVD apparatus for forming Si, SiN, and SiO 2 type thin films, and especially Poly-Si.
It is preferably used for CVD and SiN-CVD film formation.
A conventional batch type vertical CVD apparatus (hereinafter, simply referred to as vertical CVD apparatus for simplification) B includes a cylindrical outer tube 12 and an inner tube 14 formed of quartz or the like as shown in FIG. The double furnace core tube 16 and the annular heater 18 arranged so as to surround the periphery thereof. The inner hollow portion of the inner tube 12 of the furnace core tube 16 constitutes a furnace chamber 20 for the vapor phase growth reaction, and a wafer boat 22 in which a large number of wafers A are vertically separated from each other is mounted therein. Placed. The wafer boat 22 is
The wafer boat side wall surface is provided with a shelf means made of a highly heat-resistant material such as quartz and capable of accommodating a large number of wafers at predetermined intervals in a vertical direction.

The reaction gas is the lower hatch 24 of the furnace core tube 16.
The inner tube 1 through the gas introduction port 26 provided in the
4 and the wafer boat 22 are introduced into the annular space. A part of the flow of the reaction gas flowing in the annular space is branched and flows as a diffusion flow along the surface of the wafer A across the wafer boat 22, and a desired element or compound is reacted by a gas phase reaction on the surface of the wafer A. To grow up. The remaining reaction gas penetrates the upper portion of the inner tube 14 and flows from the upper portion to the lower portion of the annular portion of the inner tube 14 and the outer tube 12 from the upper portion to the lower portion. No.) is sucked and discharged to the outside.

Below the furnace core tube 16, a load lock chamber 3 is provided.
0 is provided. The load lock chamber 30 is a vacuum chamber which is designed to carry out these operations without being communicated with the outside when loading and unloading the wafer in the furnace chamber, and the vacuum is sucked by another vacuum pump (not shown). ing.

[0005]

By the way, the recent vertical CVD apparatus is capable of handling a large wafer diameter and processing a large number of wafers (up to 100 s) at one time.
The furnace chamber 20 inside the furnace core tube 16 functioning as a process furnace chamber is larger than the conventional one, and the temperature, pressure, and reaction gas concentration must be uniform in a larger region than in the single-wafer type. However, apart from the temperature, it is technically extremely difficult to make the pressure and the reaction gas concentration uniform over the entire loading area of the wafer. Therefore, a method of dividing the furnace chamber into small regions and controlling the temperature, which is a thin film forming factor that is relatively easy to control in each region, has been attempted. According to this method, the uniformity of the film thickness can be achieved to a considerable extent, but the film quality changes in each region.

Further, in the conventionally used apparatus, since a large number of wafers are loaded on one wafer boat, the wafer boat becomes large. Therefore, in an apparatus equipped with a load lock mechanism to prevent atmospheric components from entering the furnace chamber, there is a problem that the apparatus expands as the size of the wafer boat increases. In particular, this tendency is becoming stronger with the recent increase in the diameter of wafers. Therefore, it is desired to downsize the device while maintaining the processing capacity. Furthermore, due to the recent demand for miniaturization of semiconductor chips, the LPCVD film is required to be further thinned. In order to reduce the film thickness, CVD conditions that are not affected by the surface condition of the substrate are required. For that purpose, it is necessary to increase the partial pressure of the source gas so as to increase the density of nuclei formed on the substrate surface. On the other hand, if the partial pressure is increased, the inter-plane distribution becomes worse.

In view of the above problems, it is an object of the present invention to provide a vertical CVD apparatus which improves the uniformity of the inter-plane distribution of film quality and makes the apparatus compact.

[0008]

In order to solve the above-mentioned problems, a vertical CVD apparatus according to the present invention is configured such that a wafer boat on which wafers are vertically stacked is loaded in a furnace core tube, In a vertical CVD apparatus configured to form a thin film on a wafer surface by introducing a reaction gas into a wafer and performing a vapor phase growth reaction at a high temperature, the wafer boat is formed by stacking divisible units for each wafer. Is characterized by.

A preferred embodiment of the present invention is characterized by comprising a load lock chamber capable of accommodating the unit. A further preferred embodiment of the present invention is characterized in that the loading / unloading of the wafer in the load lock chamber is performed for each unit, and further, the load lock chamber is provided at the upper part and the lower part of the furnace core tube, respectively, and the wafer is introduced. It is characterized in that the discharge and the discharge are performed through different load lock chambers, respectively, and that a plurality of furnace core tubes are provided. Further, according to another preferred embodiment of the present invention, a plurality of furnace core tubes are provided, and load lock chambers are provided at the upper part and the lower part of each furnace core tube, and the load lock chambers are connected to each other. The wafer is introduced from the load lock chamber of the furnace core tube, and the wafer is discharged from the load lock chamber of another furnace core tube.

[0010]

According to the invention of claim 1, since the wafer boat is constructed by stacking units that can be divided for each wafer, the size of each unit is small. When a wafer is transferred, it is carried out separately for each unit on which one wafer is placed, and each unit is stacked to form a wafer boat, so that the wafer is housed in the furnace chamber as in the conventional apparatus. Therefore, the space required for moving the wafer boat is reduced, and the dimensions of the load lock chamber and the like can be reduced. Also, the withstand load of the transfer arm can be reduced.

According to the second aspect of the present invention, since the volume of the load lock chamber can be set to accommodate only one unit, it can be made much smaller than the conventional one. According to the third aspect of the present invention, when the wafer is put in and taken out of the furnace, the unit of the wafer boat is individually used to reduce the pace of the apparatus.

In the invention of claim 4, the load lock chambers are provided in the upper part and the lower part of the furnace core tube, respectively, and the loading and unloading of the wafers are performed through the different load lock chambers. It can be moved sequentially from the entrance to the exit. Therefore, in the process of moving in the furnace chamber, each wafer experiences the same reaction environment in the furnace by passing through the whole inside of the furnace, and the vapor phase growth reaction is performed under the same condition. As a result, in-plane variation in film quality is eliminated in principle, and it is possible to secure the in-plane uniformity of film quality. Further, by using this method, the present apparatus can be applied to a process having a trade-off relationship with the inter-plane uniformity, for example, a process such as ultra-thin film formation in which the inter-plane uniformity cannot be obtained by the conventional method. According to the invention of claim 6, a plurality of furnace core tubes are provided, load lock chambers are provided at the upper and lower portions of each furnace core tube, and the load lock chambers are connected to each other, and the load lock chamber of one furnace core tube is connected. By introducing the wafer from the chamber and discharging the wafer from the load lock chamber of another furnace core tube, the unit containing the wafer is not exposed to the atmosphere, and processing can be performed without preparing a space for placing the unit at all. .

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in more detail based on embodiments with reference to the accompanying drawings. In addition, the following FIG. 1 to FIG.
5, the parts having the same functions as those of FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted. Example 1 FIG. 1 is a schematic diagram of a vertical CVD apparatus according to the present invention, and FIG. 2 is a schematic diagram of a wafer boat unit. The vertical CVD apparatus 10 of the first embodiment has the same furnace core tube 16, heater 18, lower hatch 24, and lower hatch 24 as the conventional vertical CVD apparatus B described above.
Furnace chamber 20 with gas inlet 26 and gas outlet 28
And a buffer station 32 provided under the lower hatch 24 and a load lock chamber 34 adjacent to the buffer station 32. In the furnace chamber 20 in the furnace core tube 16, a wafer boat 36 in which a large number of wafers A are vertically stacked is housed.

The wafer boat 36 is composed of a large number of wafer boat units 38, and these wafer boat units 38 are vertically stacked to be formed as one combined wafer boat. 2A is a view I of FIG.
2 is a plan view of the wafer boat unit 38 of FIG.
FIG. 2B is a side view taken along the line II-II of FIG. Each wafer boat unit (hereinafter abbreviated as a unit for simplicity) 38 has a plurality of short quartz columns 40 that are slightly smaller than the diameter of the wafer A (shown by phantom lines), as shown in FIG. Strut connecting rods 4 made of quartz are arranged at equal intervals on a semicircle of a circle having a small diameter, and the struts 40 are mutually made.
It is formed by connecting two. The height of the pillar 40 is equal to the required distance between the wafers, and the lower portion 43 of the pillar 40 has a structure in which the head of the pillar 40 of another unit 38 is fitted. ing. The pillar connecting rod 42 also has a function of connecting the pillar 40 and a function of a support for supporting one wafer A. That is, one wafer A is held by one unit 38.

A transfer unit 44 is provided in the load lock chamber 34.
The transfer unit 44 carries one of the above-mentioned units 38 and transfers it from the load lock chamber 34 to the buffer station 32. In addition, a known transfer system 46 is provided in the buffer station 32 to raise and lower the unit 38 from the buffer station 32 to the furnace chamber 20 in the core tube 16 across the lower hatch 26.

One wafer A has one unit 38
Housed in. That is, in the load lock chamber 34, the wafers A are transferred one by one on the transfer unit 44.
Each unit 38 is loaded by a commonly used transfer device (not shown), and is transported from the load lock chamber 34 to the buffer station 32. The unit 38 then
It is stacked in the furnace chamber 20 in the furnace core tube 16 from the buffer station 32 by the transfer system 46. FIG. 1 shows the wafer boat 3 after stacking a predetermined number of units 38.
6 shows the state of No. 6. In order to discharge the wafer from the furnace, one unit 38 is lowered from the furnace chamber 20 to the buffer station 32 by the transfer system 46 in the reverse operation to the above. The remaining units 38 in the furnace chamber 20 will move down one stage at the same time. Then
One lowered unit 38 is moved from the buffer station 32 to the load lock chamber 34, and the wafer A is transferred to a desired place by a transfer device (not shown).

The wafer boat is composed of a combination of a number of units, one wafer is placed on each unit in the load lock chamber, and the unit is transferred into the furnace core tube via the buffer station. The size of can be greatly reduced compared to the conventional one. Since not only the space of the load lock chamber but also the volume of the load lock chamber to be exhausted is reduced, the cost of the exhaust device can be reduced and a high vacuum can be achieved.

Embodiment 2 FIG. 3 is a schematic side sectional view showing the structure of Embodiment 2 of the vertical CVD apparatus according to the present invention. Vertical CVD of Example 2
The device 50 is configured such that the unit 38 is introduced into the furnace chamber 20 of the furnace core tube 12 from the lower part and discharged from the upper part, and the inner tube 14 is omitted and the gas introduction port 26 is provided in the upper part of the outer tube 12. Except for the vertical C of Example 1.
It has the same configuration as the VD device 30. In the upper part, another upper buffer station 52, an upper load lock chamber 54 adjacent to the upper buffer station 52, and an upper transfer unit 56 for transferring the unit 38 therebetween are provided, and further, across the upper hatch 58, the outer tube 12 is provided. An upper transfer system (not shown) for raising the unit 38 from the furnace chamber 20 to the upper buffer station 52 is provided.

One wafer is loaded in one unit 38 and passed through the buffer station 32 to the unit 38.
At the same time, the unit 38 is loaded from the bottom into the furnace chamber 20, and the previously introduced unit 38 moves upward together with the wafer. The thin film formation by the vapor phase growth reaction is performed while the wafer is sequentially moved from the bottom to the top. As a result, all the wafers pass through the inside of the furnace, so that the thin film formed on the wafer has no in-plane distribution in terms of film thickness and film quality. In this embodiment, the reaction gas is set to always flow in the furnace chamber 20, but for safety, the reaction gas may be stopped when the isolation door is opened. In this embodiment, the inlet of the unit is at the bottom,
Although the discharge port of the unit is provided at the upper part, of course, the reverse may be applied.

Embodiment 3 FIG. 4 is a schematic side sectional view showing the structure of Embodiment 3 of the vertical CVD apparatus according to the present invention. The vertical CVD apparatus 60 of the third embodiment has a configuration in which two sets of the vertical CVD apparatus 50 of the second embodiment are adjacent in parallel. An upper connection buffer station 62 and a lower connection buffer station 64 through which the unit 38 passes are provided between the upper two buffer stations 52, 52 and between the lower two buffer stations 32, 32. In addition, in this embodiment, two sets of vertical CVD devices 50 are arranged adjacent to each other in parallel.
Of course, three or more sets of vertical CVD devices 50 may be adjacently arranged in parallel. Unit 38 has two outer tubes 1
The wafer is circulated in the inside of the outer tube 12, and the wafer is discharged and introduced at the upper part or the lower part of the outer tube 12. For example, the unit 38 is introduced from the lower portion into the outer tube 12A and moved upward, and is taken out from the upper portion to form the upper buffer station 52 and the upper connection buffer station 6
It is introduced from the upper part to the outer tube 12B via 2 and moves downward, and finally taken out from the lower part. The advantage of this device is that the unit 38 is not exposed to the atmosphere. Furthermore, processing can be performed without preparing any space for placing the unit. Further, as in the case of Example 2, there is theoretically no wafer-to-wafer distribution regarding film thickness and film quality.

[0021]

According to the present invention, the wafer boat is constructed by stacking the dividable units for each wafer, so that the space for the load lock chamber and the transfer system can be saved and the apparatus can be downsized. Further, since the wafer boat can be divided into units, the maintenance is easy and the load capacity of the transfer system can be reduced. Claim 2
The inventions of 3 and 3 further enhance the effect of the invention of claim 1. According to the invention of claim 4, the load lock chambers are provided in the upper part and the lower part of the furnace core tube, respectively, and the wafer is introduced and discharged through the different load lock chambers. In principle, the processing can be performed so that it does not exist. Therefore, the vertical CVD apparatus of the present invention can also be applied to a process having a trade-off relationship with the interplane distribution, for example, a process of forming an extremely thin film by a vapor phase growth reaction. According to the invention of claim 6, since the unit accommodating the wafer is always in the furnace core tube or the load lock chamber, it is not exposed to the atmosphere, and the processing is performed without preparing a space for placing the unit at all. be able to.

[Brief description of drawings]

FIG. 1 is a schematic side cross-sectional view showing the configuration of Example 1 of a vertical CVD apparatus according to the present invention.

2A and 2B are a plan view and a side view of a unit, respectively.

FIG. 3 is a schematic side cross-sectional view showing the configuration of Example 2 of the vertical CVD apparatus according to the present invention.

FIG. 4 is a schematic side sectional view showing the configuration of Example 3 of the vertical CVD apparatus according to the present invention.

FIG. 5 is a schematic side sectional view showing a configuration of a conventional vertical CVD apparatus.

[Explanation of symbols]

 10 Example 1 of Vertical CVD Apparatus According to the Present Invention 12 Outer Tube 14 Inner Tube 16 Double Furnace Core Tube 18 Annular Heater 20 Furnace Chamber 22 Wafer Boat 24 Lower Hatch 26 Gas Inlet 28 Gas Outlet 30 Load Lock Chamber 32 Buffer station 34 Load lock chamber 38 Unit 40 Strut 42 Strut connecting rod 44 Transfer unit 46 Transfer system 50 Vertical CVD apparatus 52 Upper buffer station 54 Upper load lock chamber 56 Upper transfer unit 58 Upper hatch 60 In Example 3 according to the present invention Vertical CVD device 62 Upper connection buffer station 64 Lower connection buffer station

Claims (6)

[Claims] 1. A wafer boat in which wafers are placed in a multi-tiered manner is loaded in a furnace core tube, and a reaction gas is introduced into the furnace core tube to cause a vapor phase growth reaction at a high temperature to form a thin film on the wafer surface. A vertical CVD apparatus configured to form the wafer boat, wherein the wafer boat is formed by stacking units that can be divided for each wafer. 2. The vertical CVD apparatus according to claim 1, further comprising a load lock chamber capable of accommodating the unit. 3. The vertical CVD apparatus according to claim 1, wherein wafers are taken in and out of the load lock chamber for each unit. 4. The vertical structure according to claim 3, wherein load lock chambers are provided at an upper portion and a lower portion of the furnace core tube, respectively, and wafers are introduced and discharged through different load lock chambers. Type CVD equipment. 5. The vertical CVD apparatus according to claim 3, further comprising a plurality of furnace core tubes. 6. A plurality of furnace core tubes are provided, and load lock chambers are provided at an upper portion and a lower portion of each furnace core tube. 4. The vertical CVD apparatus according to claim 3, wherein a wafer is introduced and the wafer is discharged from a load lock chamber of another furnace core tube.