JPS594012A - Method and apparatus for manufacturing semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a growth layer, in which there exists no slip line and thickness thereof is uniform, by keeping a space of adjacent wafers to approximately specific value during the time when a heating temperature is kept constant during growth and keeping the space to predetermined value or less during the time when a temperature change advances when a single crystalline Si thin-film is grown on a semiconductor wafer in an epitaxial manner. CONSTITUTION:A coil 24 connected to a RF power supply is wound on the outer circumference of a quartz pipe 21, a gas introducing pipe 23 is inserted into the quartz pipe 21, and a gas after used is discharged from a discharge port. A fixed holder 32 and a movable holder 32a to which the semiconductor wafers 22 are each pasted under vertical states are set up under the introducing pipe 23, and the holder 32a is moved during treatment to change the spaces of the surfaces 31a of adjacent wafers 22. That is, the spaces are kept to approximately 15mm. during the time when the heating temperature during the growth of the thin- films is kept constant, and narrowed to approximately 6mm. or less when the temperature change advances.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a method of manufacturing a semiconductor device and an apparatus thereof, and more particularly to a method of low pressure epitaxial growth and an apparatus thereof.

(2) Background of the Technology A low-pressure epitaxial growth (vapor phase growth) method for growing a silicon single crystal thin film on a semiconductor wafer and an apparatus used therefor are known. Figure 1+al schematically shows the arrangement of the device, in which ■ is a quartz tube, 2 is a wafer, 3 is a gas tube, and 4 is a radio frequency (RF) power source for heating the quartz tube 1. 5 is the heating coil connected to it, 6 is the box hook that stores the gas phone, 7 is the gas control box that stores the flow meter, etc., 8 is the rotary pump, 9 is the mechanical booster pump, 1° is Each gas outlet is shown. Monosilane gas (S i II), dichlorosilane gas (Sj
HzC4z), dopant bosphin/hydrogen gas (PII3/)It), hydrogen chloride/hydrogen gas (H(J/lh), purge gas (N2), etc., from Bonge Box 6 to Gas Conn Day Call Box 7. The gas is then discharged from the outlet 1o of the gas pipe 3 toward the wafer 2, and is ejected one nozzle in the direction shown by the arrow by the low-pressure pump 8.
・The pressure is maintained at (the pressure range where the decompression shrimp effect occurs).

FIG. 1 (bl is a diagram showing the arrangement of wafers in detail, wafer 2 is a SiC-coated carbon disk (susceptor) 11
gas is sent through the gas pipe 3 as shown by the arrow in the figure. The susceptor 11 is placed in a quartz holder (not shown). The figure fcl is a view of the arrangement of the wafer 2 seen from the side of the figure (bl).

Using such a device, the inside of the quartz tube 1 was heated to 1150°C ± 50°C and heated (preheated) for about 15 minutes.During this time, the surface of the wafer 2 was cleaned using IIC! about 1 gas
Lasts for a minute. Next, the temperature is lowered to 1000° C., and epitaxial growth is performed over a period of 5 to 20 minutes. Next, the temperature is lowered over a period of about 5 minutes, and the epitaxial growth process is completed. This progress is shown in the diagram of FIG. 2, in which the vertical axis represents temperature ('C) and the horizontal axis represents time (minutes).

(3) Prior Art and Problems In the vapor phase growth of silicon single crystals as described in Section 2, heat conduction between the wafer 2 and the susceptor 11 is poor (particularly noticeable under reduced pressure), and the susceptor 11 is completely uniform. Because the wafer is not heated by the temperature distribution, a temperature gradient occurs within the wafer, resulting in slip lines.

The slip line is placed on the wafer as shown in FIG.
2, which is caused by the step difference in the silicon single crystal layer. The same figure (bl is a schematic cross-sectional view of the silicon single crystal layer on the wafer surface; silicon single crystal 1*13
When there is a step between a and 13b, a slip line 12 appears in the depth direction of the silicon single crystal layer. This is because the temperature on the wafer surface is non-uniform due to the salinity gradient mentioned above.
This temperature non-uniformity causes non-uniform growth of single crystal silicon.
This is because a step difference as shown in i3a and 13b is produced on the surface of the silicon single crystal layer.

Semiconductor devices formed on such slip lines 12 not only become defective products, but also the silicon single crystal may crack along the slip lines.

(4) Purpose of the Invention In view of the above-mentioned conventional problems, the present invention provides a method for growing monocrystalline silicon on a semiconductor wafer in a vapor phase, without generating slip lines seen in the prior art. An object of the present invention is to provide a method and apparatus for growing a silicon single crystal layer.

(5) Structure and object of the invention According to the present invention, in a method for low-pressure vapor phase growth (epitaxial growth of single crystal silicon) of single crystal silicon on the surface of a semiconductor wafer, in a quartz tube during growth of single crystal silicon. While the temperature is constant, the distance between adjacent wafers is kept at about 15 mm to allow silicon source gas to easily flow between these wafers, and the temperature changes during heating or cooling. In the method, the distance between adjacent wafers is brought closer to 6 mm or less, and in an epitaxial growth apparatus, one group of every other wafer is placed on a fixed means, and the other group of wafers is placed on a movable means. During silicon single crystal growth, the movable means is arranged so as to maintain a distance of about 15 mm between the wafers in one group and the wafers in the other group, and the movable means is arranged so as to increase or decrease the temperature of the heat applied to the wafers. This is achieved by providing an apparatus configured to move the movable means to reduce the distance between the wafers of one group and the wafers of the other group to 6 mm or less during a temperature change. Ru. Therefore, the movable means in the above device comprises a holder arranged in the length direction of the quartz tube in which the wafer is arranged and movable in that direction,
A means on which a susceptor for supporting wafers is fixed, or a holder for a susceptor on which one group of wafers is placed and a holder on which a susceptor on which wafers from the other group are placed can be opened and closed. When these holders are closed, the distance between adjacent wafers is maintained at 6 mm or less, and when the holders are open, the distance between adjacent wafers is approximately 15 mm. composition.

(6) Examples of the invention Embodiments of the present invention will be described in detail below with reference to the drawings.

In an experiment to find the cause of the slip line described above, the inventor of the present application confirmed the following fact. Slip lines are caused by non-uniform temperature gradients, and non-uniform temperature gradients are particularly likely to occur when the temperature inside the quartz tube in which the wafer is placed is decreasing. Takashi)
do. However, when two wafers are arranged with a distance of 6 mm mm, the above-mentioned cooling of the wafers does not occur due to mutual radiant heat. Furthermore, when the wafers are placed at a close distance of 6 mm or less, even if an apparatus having the configuration shown in FIG. do not have.

On the other hand, if the two wafers are separated by about 15 mm, single crystal silicon will grow in a satisfactory state at the growth temperature (1000° C.). However, if the two wafers are separated to this extent, cooling occurs from the periphery of the wafer during cooling, and slip lines are likely to occur.

Therefore, in the method of the present invention, adjacent wafers are spread apart by about 15 mm during silicon growth, that is, while the temperature inside the quartz tube in which the wafers are placed is 1000°C. If the two wafers are separated by about 15 mm, there will be cooling from the periphery of the wafers as described above during cooling, but this separation only occurs during silicon growth, and during that time the temperature inside the quartz tube will remain at 1000°C. There is no need to worry about cooling the wafer. If the distance between the two wafers is set to 6 mm or less during temperature cooling, rapid cooling from the periphery of the wafers is prevented by radiant heat between the wafers, as described above. Since the single-crystal silicon film having a predetermined thickness has already grown, the fact that silicon growth does not proceed in a state where the thickness is less than 6 mm does not have any effect.

FIG. 4 shows a schematic W1 side view of an apparatus for carrying out the method of the present invention, in which 21 is an Iconic tube;
2 is a wafer, 23 is a gas pipe, and 24 is a coil connected to an IiF source (not shown), and silicon source gas sent to this gas pipe is ejected in the direction of the arrow from an outlet 3o. The wafer 22 is placed on the susceptor 31'' in Figure 1 (b).
1 and (C1).

The configuration of other parts not shown, such as a silicon source gas supply system and an exhaust system, is the same as that shown in FIG.

Every other susceptor 3 from the second one from the left in the figure
I is fixed on a fixed boulder 32, and the fixed holder 32 is immovable. By force, every other susceptor 31a from the leftmost one in the figure is fixed on a movable boulder 32a, and the movable boulder 32a is configured to be able to slide, for example, on a rail (not shown), and is driven by an appropriate driving means (not shown). As shown in the figure, it can move left and right.

During single crystal silicon growth, that is, while the temperature inside the quartz tube 21 is maintained at 1000°C, the susceptors 31 and 31a
The wafers 22 are separated from each other so that the distance between adjacent wafers 22 is maintained at about 15 mm (FIG. 4(a)).

Before the epitaxial growth is completed and the temperature inside the quartz tube 21 begins to decrease, the movable boulder 32a moves to the right as seen in the figure and does not move until the distance between the adjacent wafers 22 becomes 6 mm or less. Figure 4(b)). When two wafers come close to each other, the radiant heat from each other causes the wafers to
Since the wafer is kept warm, rapid cooling from the wafer periphery as experienced in the prior art is prevented.

Although preferred embodiments of the present invention have been described above,
The holders 32 and 32a may be two concentrically arranged shafts, the outer shaft being the movable holder 32a, the inner shaft being the fixed holder 32, and the outer shaft sliding on the inner shaft.

Or instead of the above, the movable holder 32a is formed to be rotatable, and when the movable holder 32 is rotated to the open state, the wafers 22 are in the separated state shown in FIG. When the wafer 22 is in the state shown in FIG.
It is also possible to use an opening/closing means as shown in FIG. Although such a device requires the use of a quartz tube with a large diameter, it has the advantage that the wafer 22 can be placed on both sides of the susceptor 31.degree. 31a.

As understood from FIG. 4 fa+, in the above-described apparatus, the wafer can only be placed on one side of the susceptor, but an apparatus using opening/closing means improves this point.

In the above example, the case of temperature decrease is taken, but the same applies to the case of temperature increase, and the scope of the present invention is applicable to temperature increase,
This applies to both cases of temperature drop, that is, cases where there is a temperature change. - (7) Effects of the Invention As explained in detail above, the method and apparatus of the present invention prevents the occurrence of slip lines experienced in the prior art, and not only improves the manufacturing yield of semiconductor devices. , which is highly effective in improving product reliability.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a diagram showing a conventional low-pressure epitaxial growth apparatus, in which Tal is a diagram not showing the arrangement of the apparatus, fbl is a cross-sectional view showing the arrangement of a susceptor on which a wafer is placed, and its ( 0)
For example, the susceptor shown in Tbl is viewed from the side, Figure 2 is a diagram showing the relationship between time and temperature during single crystal silicon thin film growth, and Figure 3 is a diagram for explaining slip lines. (Al is a plan view of a wafer where a slip line has occurred, fbl is a cross-sectional view of a single crystal silicon layer at a slip line, and FIG. 4 is a schematic cross-sectional view of an embodiment of the present invention.・Quartz tube, 2.22・-Wafer, 3.23
-Gas pipe, 4.24- Coil, 5-11F source, 6
-Cylinder box, 7-Gas control box, 8-Rotary phone '7', 9-Mechanical booster box, 10.30-Gas outlet, 11.31
・-Susceptor, 12- Slip line, 13a, 1
3b-single crystal silicon layer surface, 32...-fixed holder,
32a-nJ dynamic holder patent Applicant: Fujitsu Ltd. = 62 Figure 3 (Q) (b)

Claims (1)

[Claims] In a method for epitaxially growing an o1fi crystal silicon thin film on a semiconductor wafer, while the heating temperature is constant during growth of a single crystal silicon thin film, the interval between adjacent wafers is maintained at approximately 15rr1m, and the While the temperature change is progressing, the distance between adjacent wafers is 6 m.
A method for manufacturing a semiconductor device, characterized in that the temperature is kept below m. (2) A semiconductor urchin consisting of a quartz tube, a heating coil connected to a high-frequency power supply surrounding the quartz tube, and a system for supplying and discharging silicon source gas to the quartz tube, on which a single crystal silicon thin film is grown. , wafers are mounted on a susceptor, and the susceptor is fixed to a holder. placed on a movable means, one group of wafers and (
Spacing between each wafer in the fll group −'i: 15
The movable means is arranged so as to keep the wafers in one group and the wafers in the other group by moving the movable means while the temperature of the quartz tube is increasing and decreasing. An apparatus for manufacturing a semiconductor device, characterized in that the interval is narrowed to 6 mm or less.