JPH07122489A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To restrain auto doping by simple and few processes. CONSTITUTION:The title method consists of the following; a first process wherein a high density N-type (or P-type) buried layer 4 is formed on a semiconductor substrate 1 by epitaxial growth, a second process wherein an intrinsic layer 6 is formed on the surface of the buried layer 4 by epitaxial growth, and a third process wherein a P-type (or N-type) low concentration layer 2 is formed on the whole surface of the semiconductor substrate 1 containing the intrinsic layer 6 by epitaxial growth.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device.

[0002]

2. Description of the Related Art As a conventional method of manufacturing a semiconductor device,
For example, there are those shown in FIGS. 9 and 10 (Lateral
Autodoping Suppression by Selective Epitaxy Cappin
g andIts Application in High Speed BiCMOS, Extended
Abstracts of the 20th (1988 International) Conffere
nce on Solid State Devices and Materials, Tokyo, 198
8, pp.45-48). First, the oxide film 13 is formed on the P-type silicon substrate 11. The oxide film 13 in the region where the N-type buried layer is formed is removed by mask etching. P-type silicon substrate 1
1 is doped with boron as an impurity at a low concentration of about 10 ¹⁵ cm ⁻³ (FIG. 9A). Ion implantation 16 is performed to form an N-type buried layer. The injection condition is As 15
The energy is 0 keV and the dose is 3E15 cm ^-2 . Ions are implanted near the surface of the P-type silicon substrate 11 (FIG. 9B). Since the impurities implanted by the ion implantation 16 are incorporated into the crystal as carriers,
And a heat treatment is performed to recover the defects caused by the ion implantation 16. By this heat treatment, the high-concentration N-type buried layer 14 is formed. The concentration of the N-type buried layer 14 is 10
It is about ¹⁹ to 10 ²⁰ cm ^-3 (Fig. 9 (c)). After forming the N-type buried layer 14, the coating layer 15 is formed. This coating layer 1
5 is formed by selective epitaxial growth. Growth temperature is 950 ° C., pressure is 100 Torr, film thickness is 0.8-
It is 1.0 μm. The coating layer 15 is an intrinsic layer without introducing a doping gas during growth (FIG. 9 (d)). After removing the entire surface of the oxide film 13, a P-type epitaxial layer 12 having an impurity concentration of about 10 ¹⁵ cm ⁻³ is formed on the entire surface. The film thickness is 1.0 to 2.0 μm (FIG. 10A). After the P-type epitaxial layer 12 is formed, N-type impurities are diffused from the surface of the P-type epitaxial layer 12 to form the N-type well 1 in the P-type epitaxial layer 12.
Form 7. The P-type epitaxial layer 12 is separated so that no leak current flows between the N-type wells 17 (FIG. 10B). A P-type diffusion layer 18 having a concentration of 10 ¹⁷ cm ⁻³ and a P-type diffusion layer 19 having a concentration of 10 ¹⁶ cm ⁻³ are provided in the N-type well 17.
After formation of source contact 20 and drain contact 2
1. Form the gate electrode 22. In this way, a lateral power MOS is formed in the N-type well 17 (FIG. 10).
(C)).

As an epitaxial growth method in the above process, the P-type silicon substrate 11 is heated to a high temperature (900 to 120).
A chemical vapor deposition method (CVD method) is used in which silicon chloride or a hydrogen compound (hereinafter referred to as a source gas) is heated to 0 ° C.) and reacted on the surface of the substrate 11. Selective epitaxial growth is also a growth method using the CVD method. The cover layer 15 is formed by selective epitaxial growth in order to prevent lateral autodoping in the growth process of the P-type epitaxial layer 12. Regarding autodoping, "Silicon crystals and doping" (Maruzen),
As described in P82 to P83, the N-type impurities in the high-concentration N-type buried layer 14 are not contained in the P-type epitaxial layer 12.
It is a phenomenon that is taken in. FIG. 12 shows "ON BURIED LA with N type buried layer before epitaxial growth".
Although the impurity concentration profile in the depth direction of “YER” is shown, the N-type buried layer 14 has a very high surface concentration as compared with the P-type silicon substrate 11, so that the impurities can be easily removed in the epitaxial growth process in which high temperature treatment is performed. The impurities that have jumped out from the N-type buried layer 14 are taken into the interface between the P-type silicon substrate 11 and the P-type epitaxial layer 12, and there is no N-type buried layer, as shown in FIG. The N-type inversion layer 23 is formed in the OFF BURIED LAYER. FIG. 13 shows the "OFF BURIE in which the N-type inversion layer 23 is formed after the epitaxial growth.
3 shows an impurity concentration profile of D LAYER ″ in the depth direction. Before the growth of the P-type epitaxial layer 12, N is shown.
By selectively forming the coating layer 15 on the surface of the mold burying layer 14, it is possible to prevent impurities from being separated from the surface and suppress the formation of the N-type inversion layer 23 by autodoping.

[0004]

However, in such a conventional method of manufacturing a semiconductor device, P having a low concentration is used.
Before the formation of the N-type epitaxial layer on the entire surface, an ion implantation step for forming an N-type buried layer, a heat treatment step, and a selective epitaxial growth step for forming a coating layer, and three separate steps are required. was there.

The present invention has been made in view of such a conventional problem, and an object thereof is to provide a method of manufacturing a semiconductor device capable of suppressing autodoping with a simple and small number of steps.

[0006]

In order to solve the above problems, the present invention firstly has a high-concentration N type (or P type) buried layer on a semiconductor substrate and a P type ( Or a method for manufacturing a semiconductor device in which an N type) low concentration layer is formed by epitaxial growth, a first step of forming the high concentration N type (or P type) buried layer on a semiconductor substrate by epitaxial growth, and the high concentration A second step of forming an intrinsic layer on the surface of the N-type (or P-type) buried layer by epitaxial growth, and the P-type (or N-type) low concentration layer on the entire surface of the semiconductor substrate including the intrinsic layer And a third step of forming by epitaxial growth.

Secondly, the gist of the first structure is that the first step and the second step are continuously performed in the same apparatus.

Thirdly, in a method of manufacturing a semiconductor device having a high concentration N type (or P type) buried layer on a semiconductor substrate and forming a P type (or N type) low concentration layer thereon by epitaxial growth. A first step of forming the high-concentration N-type (or P-type) buried layer on the semiconductor substrate, and a high concentration on the entire surface of the semiconductor substrate including the high-concentration N-type (or P-type) buried layer Second step of forming a P-type (or N-type) intermediate layer by epitaxial growth, and forming the P-type (or N-type) low-concentration layer by epitaxial growth on the high-concentration P-type (or N-type) intermediate layer The gist is to have a third step.

Fourthly, in a method of manufacturing a semiconductor device having a high concentration N type (or P type) buried layer on a silicon substrate and forming a P type (or N type) low concentration layer thereon by epitaxial growth. A first step of forming the high-concentration N-type (or P-type) buried layer on a silicon substrate, and a second step of implanting silicon ions on the high-concentration N-type (or P-type) buried layer And the P-type (or N-type) on the entire surface of the silicon substrate including the high-concentration N-type (or P-type) buried layer.
The third step is to form a low concentration layer by epitaxial growth.

[0010]

In the above structure, firstly, P type (or N type)
An epitaxial growth step for forming an N-type (or P-type) buried layer before the low-concentration layer epitaxial growth step;
It becomes possible to suppress autodoping in two small steps of the epitaxial growth step for forming the intrinsic layer which is the covering layer. Moreover, since the ion implantation method is not used, it is possible to eliminate the occurrence of defects.

Secondly, the epitaxial growth step for forming the N-type (or P-type) buried layer and the epitaxial growth step for forming the intrinsic layer are continuously performed in the same apparatus, so that both steps are performed. Can be performed in one step, and the steps can be further simplified.

Third, before the epitaxial growth step of the P-type (or N-type) low-concentration layer, the N-type (or P-type) buried layer forming step and the high-concentration P-type (or N-type) intermediate layer are formed. It is possible to prevent the N-type inversion layer from being formed even if auto-doping occurs in two fewer epitaxial growth steps. Further, if the epitaxial growth step for the high-concentration P-type (or N-type) intermediate layer and the epitaxial growth step for the P-type (or N-type) low-concentration layer are successively performed in the same apparatus, the process is further simplified. It becomes possible to do.

Fourth, ion implantation of silicon is performed on the high-concentration N-type (or P-type) buried layer to obtain a high-concentration N-type (or P-type).
Autodoping can be suppressed by a simple process of lowering the surface concentration of the (type) buried layer.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a manufacturing process of a first embodiment of the present invention. First, the silicon oxide film 3 is formed on the P-type silicon substrate 1. The silicon oxide film 3 in the region where the buried layer is formed is removed by mask etching. The P-type silicon substrate 1 is doped with boron as an impurity at a low concentration of about 10 ¹⁵ cm ⁻³ (a). The high-concentration N-type buried layer 4 is formed by selective epitaxial growth. Growth temperature 950 ℃
In, PH3 is introduced as a doping gas. After the high-concentration N-type buried layer 4 is formed, the coating layer 6 is formed by selective epitaxial growth while keeping the temperature constant in the same device.
The coating layer 6 is an intrinsic layer without introducing a doping gas during epitaxial growth (b). After forming the coating layer 6, the silicon oxide film 3 is entirely removed (c), and a low concentration P-type epitaxial layer 2 having an impurity concentration of about 10 ¹⁵ cm ^-3 is formed on the entire surface (d).

In the epitaxial growth method, the doping gas (N
In the case of the mold, the impurity concentration can be controlled by changing the flow rate of PH3) and the source gas, and the impurity concentration of the growth layer can be set to 10 ¹⁴ to 10 ²⁰ cm ⁻³ by changing each flow rate. Further, a high-concentration layer and a low-concentration layer, and further an intrinsic layer without a doping gas can be continuously formed with the same apparatus. Therefore, as in this embodiment, the high-concentration N-type buried layer 4 and the coating layer 6 which is an intrinsic layer can be formed in one step. Further, the epitaxial growth method does not require heat treatment unlike the methods such as the ion implantation method because the impurities are taken in while the crystal is grown. According to such a method of manufacturing a semiconductor device, suppression of autodoping can be realized in a small number of steps.

2 and 3 show a second embodiment of the present invention. The present embodiment is a case of having N-type and P-type buried layers. A silicon oxide film 3a is formed on the P type silicon substrate 1, and the silicon oxide film 3a in the region where the N type buried layer is to be formed is removed by mask etching (FIG. 2A). The high-concentration N-type buried layer 4a is formed by selective epitaxial growth. Further, a coating layer 6a which is an intrinsic layer is formed by selective epitaxial growth using the same apparatus (FIG. 2).
(B)). After forming the coating layer 6a, the silicon oxide film 3a is entirely removed (FIG. 2C). A silicon oxide film 3b is again formed on the entire surface to form a P-type buried layer, and only the region where the P-type buried layer is formed is removed by mask etching (FIG. 2D). The high-concentration P-type buried layer 4b is formed by selective epitaxial growth. Further, a coating layer 6b which is an intrinsic layer is formed by selective epitaxial growth using the same apparatus (FIG. 3 (a)). The entire surface of the silicon oxide film 3b is removed (FIG. 3B). A low concentration P-type epitaxial layer 2 is formed on the entire surface (FIG. 3C). According to this embodiment, even if the N-type and P-type buried layers are provided, the suppression of autodoping can be realized with a small number of steps.

FIG. 4 shows a third embodiment of the present invention. In this example, by forming a high concentration P-type intermediate layer,
Even if autodoping occurs, an N-type inversion layer cannot be formed. A silicon oxide film 3 is formed on the P-type silicon substrate 1, and the silicon oxide film 3 in the region where the buried layer is to be formed is removed by mask etching. A high-concentration N type buried layer 5 is formed by a solid diffusion method or an ion implantation method (a). The silicon oxide film 3 is entirely removed. High concentration of P
The mold intermediate layer 7 is formed on the entire surface by epitaxial growth using the CVD method (b). After the P-type intermediate layer 7 is formed, the low-concentration P-type epitaxial layer 2 is formed on the entire surface in the same chamber (c). As described above, in the epitaxial growth method, even when the same source gas and doping gas are used, it is possible to continuously form epitaxial layers having different impurity concentrations by changing the respective flow rates. For example, the source gas and the doping gas are set to the conditions shown in Table 1, that is,
An impurity concentration profile is as shown in FIG. 5 when the P-type intermediate layer 7 of the first layer is formed under the condition that the impurity concentration of the second layer is high and that of the P-type epitaxial layer 2 of the second layer is low. By thus performing the epitaxial growth in two stages and forming the P-type intermediate layer 7 having a high impurity concentration, even if lateral auto-doping occurs in the epitaxial growth process, the P-type intermediate layer 7 is offset and the N-type No inversion layer. Furthermore, the P-type intermediate layer 7 on the surface of the N-type buried layer 5 suppresses vertical auto-doping and outward diffusion, and a steep impurity concentration profile can be realized at the interface between the N-type buried layer 5 and the P-type epitaxial layer 2. .

[0019]

[Table 1] FIG. 6 shows a fourth embodiment of the present invention. In this embodiment, the surface concentration of the buried layer is lowered by silicon ion implantation to suppress autodoping. A silicon oxide film 3 is formed on the P-type silicon substrate 1, and the silicon oxide film 3 in the region where the buried layer is to be formed is removed by mask etching. High concentration N using the silicon oxide film 3 as a mask
The mold embedding layer 5 is formed (a). After the N type buried layer 5 is formed, silicon ion implantation 8 is performed. At this time, since the silicon oxide film 3 is present on the surface of the P-type silicon substrate 1, silicon ions are selectively implanted only on the surface of the N-type buried layer 5 (b). After the silicon ion implantation, the silicon oxide film 3 is entirely removed and low temperature (550 ° C.) annealing is performed. Then, a low concentration P-type epitaxial layer 2 is formed on the entire surface (c).
Here, the effect of the silicon ion implantation 8 is shown in FIGS.
I will explain based on. FIG. 7 shows "O" just before the epitaxial growth of the semiconductor device manufactured by the manufacturing method of this embodiment.
N BURIED LAYER ″ is an impurity concentration profile in the depth direction. The impurity of the N-type buried layer 5 is phosphorus. In this experimental example, the surface concentration of the N-type buried layer 5 before silicon ion implantation 8 is 10 ^19. cm ⁻³ , the dose amount of the silicon ion implantation 8 is 1E16 cm ⁻² , and the surface concentration of the N-type buried layer 5 is 4 × 10 ¹⁸ c by the silicon ion implantation 8.
It has fallen to m ^-3 . Further, FIG. 8 shows an impurity concentration profile of "OFF BURIED LAYER" after the P-type epitaxial layer 2 is formed. Compared with FIG. 13 of the conventional example, the concentration of the N-type inversion layer, which is an influence of autodoping, is lowered. In this way, by reducing the surface concentration of the N-type buried layer 5 by the silicon ion implantation 8 before performing the epitaxial growth, it becomes possible to suppress the lateral autodoping in the epitaxial growth process.

[0020]

As described above, according to the present invention,
First, a first step of forming a high-concentration N-type (or P-type) buried layer on a semiconductor substrate by epitaxial growth, and an epitaxial growth on the surface of the high-concentration N-type (or P-type) buried layer. Since the method includes the second step of forming the intrinsic layer and the third step of forming the P-type (or N-type) low concentration layer on the entire surface of the semiconductor substrate including the intrinsic layer by epitaxial growth, the P-type Before the epitaxial growth process of the (or N type) low concentration layer,
Autodoping can be suppressed by the first and second fewer steps. Further, since the ion implantation method is not used, the generation of defects can be eliminated.

Second, since the first step and the second step are continuously performed in the same apparatus, both steps can be performed in one step, and the steps can be further simplified. .

Third, the first step of forming a high concentration N type (or P type) buried layer on the semiconductor substrate, and the semiconductor substrate including the high concentration N type (or P type) buried layer. Second step of forming a high-concentration P-type (or N-type) intermediate layer on the entire surface by epitaxial growth, and a P-type (or N-type) low-concentration layer on the high-concentration P-type (or N-type) intermediate layer. Since the third step of forming by epitaxial growth is provided, before the epitaxial growth step of the P-type (or N-type) low concentration layer, even if auto-doping occurs in the first and second few steps, the P-type It is possible to prevent the N-type (or P-type) inversion layer from being formed on the surface of the (or N-type) low concentration layer. Further, if the second step and the third step are continuously performed by the same apparatus, the steps can be further simplified.

Fourth, the first step of forming a high-concentration N-type (or P-type) buried layer on a silicon substrate, and the high-concentration N
A second step of implanting silicon ions on the p-type (or p-type) buried layer, and p-type (or n-type) on the entire surface of the silicon substrate including the high-concentration n-type (or p-type) buried layer Since the third step of forming the low concentration layer by epitaxial growth is provided, autodoping can be suppressed by a simple step of lowering the surface concentration of the high concentration N-type (or P-type) buried layer.

[Brief description of drawings]

FIG. 1 is a diagram showing a manufacturing process of a first embodiment of a method for manufacturing a semiconductor device according to the present invention.

FIG. 2 is a diagram showing a manufacturing process of a second embodiment of the present invention.

FIG. 3 is a diagram showing a manufacturing process of the second embodiment of the present invention.

FIG. 4 is a diagram showing a manufacturing process of the third embodiment of the present invention.

FIG. 5: "OFF BURIE" in the third embodiment.
It is a figure which shows the impurity concentration profile of D LAYER ".

FIG. 6 is a diagram showing a manufacturing process of the fourth embodiment of the present invention.

FIG. 7 is a diagram showing an impurity concentration profile of a buried layer before epitaxial growth in the fourth embodiment.

FIG. 8 is a diagram showing an impurity concentration profile of “OFF BURIED LAYER” after epitaxial growth in the fourth example.

FIG. 9 is a process drawing of the conventional method for manufacturing a semiconductor device.

FIG. 10 is a process drawing of the conventional method for manufacturing a semiconductor device.

FIG. 11 is a diagram showing a state of autodoping in the conventional example.

FIG. 12 is a diagram showing an impurity concentration profile of a buried layer before epitaxial growth in the conventional example.

FIG. 13 is a diagram showing an impurity concentration profile of “OFF BURIED LAYER” after epitaxial growth in the conventional example.

[Explanation of symbols]

 1 P-type silicon substrate 2 Low-concentration P-type epitaxial layer 3 Silicon oxide film 4,5 N-type buried layer 6 Covering layer (intrinsic layer) 7 High-concentration P-type intermediate layer

Claims (4)

[Claims] 1. A high concentration N type (or P type) on a semiconductor substrate.
In a method of manufacturing a semiconductor device having a buried layer and forming a P-type (or N-type) low-concentration layer thereon by epitaxial growth, the high-concentration N-type (or P-type) is formed on a semiconductor substrate.
A first step of forming a buried layer by epitaxial growth, and a second step of forming an intrinsic layer by epitaxial growth on the surface of the high-concentration N-type (or P-type) buried layer
And a third step of forming the P-type (or N-type) low concentration layer on the entire surface of the semiconductor substrate including the intrinsic layer by epitaxial growth. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the first step and the second step are continuously performed in the same device. 3. A high concentration N type (or P type) on a semiconductor substrate.
In a method of manufacturing a semiconductor device having a buried layer and forming a P-type (or N-type) low-concentration layer thereon by epitaxial growth, the high-concentration N-type (or P-type) is formed on a semiconductor substrate.
A first step of forming a buried layer; and a step of forming a high-concentration P-type (or N-type) intermediate layer by epitaxial growth on the entire surface of the semiconductor substrate including the high-concentration N-type (or P-type) buried layer. A second step and a third step of forming the P-type (or N-type) low-concentration layer on the high-concentration P-type (or N-type) intermediate layer by epitaxial growth. Production method. 4. A high concentration N-type (or P-type) on a silicon substrate.
A high-concentration N-type (or P-type) buried layer on a silicon substrate in a method of manufacturing a semiconductor device having a P-type (or N-type) low-concentration layer formed thereon by epitaxial growth. Forming a high concentration N-type (or P-type) buried layer and a second step of implanting silicon ions on the high-concentration N-type (or P-type) buried layer; And a third step of forming the P-type (or N-type) low-concentration layer on the entire surface of the silicon substrate including by epitaxial growth.