JPH08236458A - Manufacture of semiconductor substrate - Google Patents

Abstract

PURPOSE: To increase the crystal growing speed by the epitaxial growth method by using trichlorosilane as a qaseous starting material and flowing down a carrier gas in a treating furnace at a flow velocity faster than a specific value or in a high-speed laminar flow having a number of inert gas replacing times larger than a specific value so that the reaction temperature can be maintained at a specific value, CONSTITUTION: A crystal layer is grown by epitaxial growth on a single-crystal silicon substrate having a fine pattern in which an impurity is buried and diffused and a crystal axis of <100>0±1 deg.. SiCl4 is used as a gaseous starting material and a carrier gas is made to flow down in a treating furnace at a flow velocity of 2m/min or in a high-speed laminar flow having a number of inert gas replacing times of 3 times/min. The reaction temperature is maintained at 1,150±10 deg.C. The reason why the flow velocity of the carrier gas in the treating furnace is specified is to prevent the stagnation of the gaseous starting material by the high-speed laminar flow so that the occurrence of local etching and deposition can be eliminated and the reaction can be stabilized and accelerated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, particularly B
The present invention relates to a method for manufacturing a single crystal silicon substrate for semiconductor integrated circuits such as for ip-IC and BiCMOS, when epitaxially growing on a silicon single crystal substrate having a specific crystal axis,
In the case of SiHCl ₃ (trichlorosilane), the growth rate is 2.0 μm by keeping the specific growth temperature by using SiHCl ₃ or SiCl ₄ as a raw material gas and letting the carrier gas flow at a much higher speed and laminar flow. / M
5.0 μm / m when flowing down at a speed higher than in
The present invention relates to a method for manufacturing a semiconductor substrate that enables high-speed film formation of in or more.

[0002]

2. Description of the Related Art When manufacturing a semiconductor integrated circuit for Bip-IC, BiCMOS, etc., <100 is used as a starting semiconductor substrate.
A silicon single crystal substrate having a crystal axis of> 0 ± 1 ° is often used. This semiconductor substrate is a wafer in which at least one surface is mirror-finished, and a dopant (P type:
B, N type: Sb, As, P) is diffused in an arbitrary portion, and then epitaxially grown by a vapor phase growth method.

Conventionally, <100> in which a buried layer is formed
When epitaxially growing a silicon single crystal wafer having a crystal axis of 0 ± 1 °, a cylinder furnace or a pancake furnace is used as a vapor phase growth furnace. At this time, it is necessary to pay attention to the pattern distortion after the epitaxial growth. Generally, pattern distortion is said to be affected by growth pressure, growth temperature, growth rate, and Si raw material gas.

[0004]

Generally, when SiCl ₄ (silicon tetrachloride) is used as a raw material gas, the reaction is carried out under normal pressure at a growth temperature of 1180 to 1200 ° C. and a growth rate of 1 ° C.
It is manufactured under the condition of μm / min or less.

When trichlorosilane is used as a raw material gas, it also has a growth rate of 1180 ° C. or higher under normal pressure.
Although it can be produced under the condition of μm / min or less, silicon and oxides of silicon are deposited inside the wall of the quartz reaction vessel (wall Depo), which causes a problem such as devitrification of quartz and uncontrollable temperature control. Not practical.

Further, when dichlorosilane or monosilane is used as a raw material gas, it is used under normal pressure or reduced pressure at 10
At a reaction temperature of 50 ° C to 1150 ° C, the growth rate is 1 μm /
It is manufactured under the condition of min or less.

However, since the growth rate is 1 μm / min or less under any of these conditions, there is a problem that productivity is poor. Furthermore, in the case of hydrogen reduction reaction such as SiCl ₄ or trichlorosilane, the reaction temperature becomes extremely high, crystal defects called Slip and autodoping of impurities from the buried layer become large, and the resistivity control (reversal) of the epitaxial film is increased. It is difficult to form (including formation of layers).

In view of the above problems in the manufacturing method of epitaxially growing a silicon single crystal substrate having a crystal axis of <100> 0 ± 1 °, the present invention reduces autodoping during hydrogen reduction reaction and causes pattern distortion. It is an object of the present invention to provide a method for manufacturing a semiconductor substrate, which can achieve a growth rate of 1 μm / min or more without any trouble.

[0009]

The inventors have found that the crystal axis <1
For the purpose of accelerating the epitaxial growth rate on a silicon single crystal substrate of 00> 0 ± 1 °, various studies were conducted on the gas flow in the reaction furnace and in the vicinity of the substrate. (Inch) The flow rate of H ₂ gas per sheet is several l to 15 l / min,
Moreover, as a result of further studying that the gas flow is a turbulent flow and a gas concentration difference is generated, as a result, the H ₂ gas flow rate per silicon single crystal substrate (5 inches) is 30 to 12
It was found that the pattern distortion can be greatly improved by setting the flow rate as high as 0 l / min and by using the gas flow in one direction, that is, a laminar flow that flows in one direction along the substrate surface.

The inventors further conducted various studies on the gas flow in the vicinity of the substrate. As a result of the laminar flow of the carrier gas being a high-speed flow, a stagnation layer of the source gas was hardly generated, and local etching, Since there is no deposit and fresh gas is always supplied, the reaction is stable and faster, that is, the hydrogen gas flow rate and gas flow per wafer are among the factors that affect the degree of influence on pattern distortion. Was found to be a very significant factor.

Therefore, the present inventors also examined the relationship between the laminar flow and the high-speed carrier gas flow and the reaction temperature based on the above findings. When trichlorosilane was used as the Si source, the reaction temperature was 1150 ° C. ± 10. When a high-speed and laminar carrier gas having a gas flow rate of 2 m / min or more in the processing furnace or a gas replacement frequency of 3 times / min or more is flowed down at ℃, the temperature is lower than the conventional one and the growth rate is also higher. The inventors have completed the present invention by discovering that a reaction that exceeds the conventional wisdom of 2 to 10 times is possible.

That is, according to the present invention, the crystal axis <100> 0 having a fine pattern in which impurities are embedded and diffused.
During epitaxial growth on a silicon single crystal substrate of ± 1 °, SiHCl ₃ (trichlorosilane) was used as a raw material gas and the gas flow rate in the processing furnace was 2 m / min or more, or the gas replacement frequency was 3 times / min or more. Laminar carrier gas is flown down, and the reaction temperature is 1150 ° C ±
It is a method of manufacturing a semiconductor substrate, which is characterized by holding at 10 ° C.

Further, according to the present invention, the crystal axis <100> 0 ± 1 having a fine pattern in which impurities are embedded and diffused.
At the time of epitaxial growth on a silicon single crystal substrate of ° C, SiCl ₄ (silicon tetrachloride) was used as a source gas.
A high-speed and laminar carrier gas having a gas flow rate of 2 m / min or more in the processing furnace or a gas replacement frequency of 3 times / min or more is flowed down, and the reaction temperature is 1150 ° C to 1190 ° C.
The method for manufacturing a semiconductor substrate is characterized in that

In the present invention, the pretreatment before the epitaxial growth is performed by baking in a high temperature H ₂ atmosphere and high temperature H ₂
And an etching treatment under a small amount of HCl gas atmosphere may be adopted. Further, the vapor phase growth apparatus has any known structure such as a vertical type, a dome type, or a tube type as long as the carrier gas flow rate can be a predetermined high-speed flow with a laminar flow flowing in one direction along the substrate surface. A device can also be employed.

In the present invention, the carrier gas flow rate in the reaction furnace is limited by the laminar flow at a high speed, so that a stagnation layer of the source gas is not generated, local etching and deposition are eliminated, and the reaction To stabilize and increase the speed, but to obtain such an effect, at least 2 m / m
A flow rate of more than in is required, and the higher the flow rate, the higher the effect. However, increasing the flow rate increases the back pressure in the reaction vessel and eventually destroys it. It is recommended to select the upper limit according to the capacity of the mass flow controller for flow rate control, which is practically 2 to 16 m / m.
in.

Further, in the present invention, the carrier gas flow rate in the reaction furnace may be replaced by the gas replacement frequency, and in order to obtain the same effect, the gas replacement frequency is at least 3 times / min or more. A flow rate is required and it is preferable that the number of replacements is large, but for the same reason as above,
Practically, it is 3 to 26 times / min.

In the present invention, when trichlorosilane is used as the Si source, the reaction temperature is 1150 ° C. ± 1.
The temperature of 0 ° C. is 2.0 to 5.0 μm / m when the carrier gas flow is a laminar high-speed flow and is outside the reaction temperature range.
This is because a growth rate of in or 5.0 μm / min or more cannot be obtained. Moreover, SiCl _{4 is used} as the Si source.
Also when using a reaction temperature of 1150 ℃ ~ for the same reason.
If the temperature is out of the 1190 ° C. range, a growth rate of 1.0 to 3.0 μm / min or 3.0 μm / min or more cannot be obtained.

[0018]

According to the present invention, in the case of epitaxial growth on a silicon single crystal substrate having a crystal axis <100> 0 ± 1 ° having a fine pattern in which impurities are embedded and diffused, in the case of a raw material gas SiHCl ₃ , the growth temperature is 1150 ° C. ±. 10
℃, keep the growth temperature 1150 ℃ for SiCl ₄
By maintaining the carrier gas at ˜1190 ° C. and flowing the carrier gas at a much higher speed and laminar flow than the conventional method, SiHCl
_In the case of ₃ , the growth rate is 2.0 μm / min or more, and if the film is flowed down at a higher speed, high-speed film formation of 5.0 μm / min or more is possible, and it is possible to react at a growth rate twice or more of the conventional rate. Therefore, it is possible to provide a high-quality silicon single crystal substrate for a semiconductor integrated circuit with improved productivity and less slip and auto-doping.

[0019]

【Example】

Example 1 5 inch diameter, P type (Boron), specific resistance 5 to 10 Ωc
After the patterning as shown in FIG. 1A is formed on the substrate having the crystal axis <100> 0 ± 1 ° of m, Sb (N
After forming a diffusion layer having a surface concentration of 1 × 10 ¹⁸ atoms / cc and a diffusion depth of 5 μm, epitaxial growth was performed. As the vapor phase growth apparatus, one having a gas flow in which main H ₂ becomes a laminar flow at a large flow rate is used, trichlorosilane is used as a raw material Si gas, and a reaction temperature is 1100 to 1150.
C, the hydrogen gas flow rate per wafer is 30 to 120
1 / min, that is, a flow velocity of 2.36 m / min
9.45 m / min, gas replacement frequency 3.9 times / min
When epitaxial growth was performed under the condition of ˜15.6 times / min, the growth rate was 2.0 to 5.0 μm / min.

1B and FIGS. 2A and 2B show a hydrogen gas flow rate per wafer of 60 l / min (gas flow rate 4.72).
m / min, gas replacement frequency 7.8 times / min) and epitaxially grown to a thickness of 20 μm.
The reaction temperature is 1100 when the growth rate of m / min is obtained.
It is an expansion (107.5 time) figure which shows the obtained pattern in 1 degreeC, 1130 degreeC, and 1300 degreeC. As shown in FIG. 2A, under all the conditions where the reaction temperature was grown in the range of 1100 to 1130 ° C., the pattern distortion was bad and not practical, but as shown in FIG. 2B, the pattern distortion was the same as that of the conventional furnace (0 It was as good as or better than that produced at a growth rate of 0.5 μm / min). Also, slip and auto-dope were at a level without any problems.

Example 2 Under the vapor phase growth conditions of Example 1, the reaction temperature was set to 1150.
℃ and obtained 2.0μm / min, 4.0μm / m
An enlarged (107.5 times) diagram showing patterns at growth rates of in, 4.5 μm / min, and 5.0 μm / min is shown in FIGS. 3A and 3B and FIGS. 4A and 4B, respectively. As a result, 11
The pattern distortion under all conditions reacted at 50 ° C. was as good as or better than that produced under the conventional furnace conditions. Also, slip and auto-dope were at a level without any problems.

Example 3 On the silicon single crystal substrate on which the impurity diffusion shown in FIG. 1A of Example 1 was carried out, the vapor phase growth apparatus of Example 1 in which the main H ₂ becomes a laminar flow at a large flow rate was used as the Si source. SiC
L ₄ , the reaction temperature is 1100 to 1190 ° C., the hydrogen gas flow rate per wafer is 30 to 120 l / min, that is, the flow rate is 2.36 m / min to 9.45 m / mi.
n, the gas replacement frequency is 3.9 times / min to 15.6 times / m
When epitaxial growth was performed under the condition of in,
A growth rate of 1.0 to 3.0 μm / min was obtained. As a result, the pattern distortion was poor under all conditions where the reaction temperature was grown in the range of 1100 to 1130 ° C.
It wasn't practical. However, the pattern distortion was observed in Comparative Example 1 under all conditions where the reaction was performed at 1150 ° C. or higher.
It was as good as or better than the one manufactured under the conventional furnace conditions.

That is, the reaction temperature is set to 1190 ° C., the growth rate is set to 2.0 μm / min, and the hydrogen gas flow rate per wafer is 30 l / min and 60 l / min.
min, 120 l / min, flow velocity 2.36 m / mi
n, 4.72 m / min, 9.45 m / min, gas replacement frequency 3.9 times / min, 7.8 times / min, 15.
Enlargement showing the pattern of the substrate at 6 times / min (10
(7.5 times) As shown in FIGS. 5A, 5B and 5C, the pattern distortion was good, and there was no problem with slip and autodoping.

Comparative Example 1 5 inch diameter, P type (Boron), specific resistance 5 to 10 Ωc
After patterning and forming Sb (N type) as a surface concentration on a substrate having a crystal axis <100> 0 ± 1 ° of m of 1 × 10
After forming a diffusion layer of ¹⁸ atoms / cc and a diffusion depth of 5 μm, the flow rate of hydrogen gas per wafer is 15 l / min and the flow rate is 1.18 m / mi in a normal cylinder furnace.
n, the gas replacement frequency is 1.9 times / min, and the reaction temperature is 12
When epitaxial growth was performed under the condition of 00 ° C,
A 18 μm thickness was obtained at a growth rate of 0.26 μm / min. As is apparent from the enlarged (107.5 times) diagrams showing the patterns of the substrates of FIGS. 6A, B, and 7A, B, the pattern distortion is good, and there is no problem with slip and autodoping. there were.

[0025]

According to the present invention, when epitaxially growing on a silicon single crystal substrate having a crystal axis <100> 0 ± 1 ° having a fine pattern in which impurities are embedded and diffused,
When the raw material gas is SiHCl ₃ , the growth temperature is 1150 ° C.
Keeping the temperature at ± 10 ° C., the growth temperature is 11 in the case of SiCl _4.
By holding the carrier gas at 50 ° C to 1190 ° C and flowing the carrier gas in a laminar flow at a much higher speed than in the conventional case, Si
In the case of HCl ₃ , if the growth rate is 2.0 μm / min or more, and if it is made to flow at a higher rate, high-speed film formation of 5.0 μm / min or more is possible, and the reaction rate is twice as fast as that of the conventional method. Because it is possible, productivity can be improved,
Moreover, it is possible to provide a high-quality silicon single crystal substrate for semiconductor integrated circuits with less slip and auto-doping.

[Brief description of drawings]

FIG. 1A is an enlarged view (107.5 times) of a substrate formed with patterning before epitaxial growth in Example, and B is an enlarged view (107.5 times) of the substrate in Example 1 at a reaction temperature of 1100 ° C. It is a figure.

2A is an enlarged view (107.5 times) of the substrate when the reaction temperature of Example 1 is 1130 ° C., and FIG. 2B is a photographed view of the substrate when the reaction temperature of Example 1 is 1150 ° C. (107.5 times). Is.

FIG. 3A shows a growth rate of Example 2 of 2.0 μm / min.
FIG. 9B is an enlarged view (107.5 times) of the substrate in FIG.
It is a figure.

FIG. 4A shows a growth rate of Example 2 of 4.5 μm / min.
(107.5 times) enlarged view of the substrate at B, and B shows the enlarged substrate (107.5 at a growth rate of 5.0 μm / min).
It is a figure.

5A, 5B, and 5C are hydrogen gas flow rates of 30 l / min, 60 l / min, and 12 per wafer of Example 3.
Enlargement showing the pattern of the substrate at 0 l / min (10
(7.5 times) FIG.

FIG. 6A is an enlarged (107.5 times) photograph of a substrate on which patterning is performed before epitaxial growth in Comparative Example 1, and B is an enlarged (107.5 times) photograph of a substrate on which conventional epitaxial growth is performed. Is.

FIG. 7A is an enlarged (107.5 times) view of the substrate on which patterning before epitaxial growth is formed in Comparative Example 1 at a different angle from FIG. 6, and B is a conventional epitaxially grown substrate. FIG. 6 is an enlarged view (107.5 times) viewed from a different angle.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01L 21/20 H01L 21/20

Claims (2)

[Claims] 1. SiHCl ₃ is used for epitaxial growth on a silicon single crystal substrate having a crystal axis <100> 0 ± 1 ° having a fine pattern in which impurities are embedded and diffused.
Using (trichlorosilane) as a raw material gas, a high-speed and laminar carrier gas with a gas flow rate of 2 m / min or more in the processing furnace or a gas replacement frequency of 3 times / min or more is allowed to flow down, and the reaction temperature is 1150 ° C ± A method of manufacturing a semiconductor substrate, characterized by holding at 10 ° C. 2. SiCl is epitaxially grown on a silicon single crystal substrate having a crystal axis <100> 0 ± 1 ° having a fine pattern in which impurities are embedded and diffused.
_{Using 4} (silicon tetrachloride) as the raw material gas, the gas flow rate in the processing furnace is 2 m / min or more, or the gas replacement frequency is 3
A method for manufacturing a semiconductor substrate, characterized in that a high-speed and laminar carrier gas at a flow rate of at least 1 turn / min is flowed down, and the reaction temperature is maintained at 1150 ° C to 1190 ° C.