JPH03203229A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable damage due to ion impregnation to be recovered completely and a highly dense n-type buried layer to be formed easily by forming an insulation layer SiO2 as a protection film on a silicon substrate and implanting ions and then performing high-temperature treatment within gas environment of a specific mixture ration of a pure nitrogen N2 and a small amount of O2. CONSTITUTION:An SiO2 film 2 is formed as an ion-impregnation protection film within an oxygen environment containing steam over the entire surface of a silicon substrate 1. After that, an As ion 3 is impregnated and high- temperature heat treatment is performed at 1200 deg.C within gas environment where the mixture ratio between the pure nitrogen N2 and a small amount of oxygen O2 is O2/(N2+O2)=0.02. Then, after that, silicon epitaxial growth is performed, thus enabling damage due to ion implantation to be recovered completely and a high-density n-type buried layer 4 to be formed easily.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for forming a buried layer by implanting As ions.

[Conventional technology]

Conventionally, when forming an n-type buried layer, a solid phase-
A coating solution mainly composed of silicon oxide containing As or SB as a solid-phase diffusion source is applied onto a silicon substrate, and then heat treatment is performed at a relatively high temperature for a long time to obtain a desired profile, followed by silicon epitaxial growth. An n-type buried layer is formed.

Alternatively, when forming a buried layer using ion implantation method,
A thin insulating film is formed on the silicon substrate or As ions are implanted directly into the silicon substrate, followed by heat treatment at a relatively high temperature (~1150°C), followed by silicon epitaxial growth to form an n-type buried layer. is forming.

[Problem to be solved by the invention]

When forming the embedded layer using the conventional coating liquid mentioned above,
For example, there are disadvantages in that it requires a large number of steps such as pre-coating treatment and baking of the coating solution, and a large amount of process time. In addition, it is difficult to control the impurity concentration profile compared to ion implantation, and the in-plane uniformity is poor.

In addition, in the conventional ion implantation method, in the heat treatment after As ion implantation, the heat treatment temperature is approximately 1150°C, so crystal defects caused by ion implantation (mainly dislocations at the interface between the amorphous layer and the silicon crystal) are not fully recovered and remain. As a defect, it has the disadvantage of having an adverse effect on the device (deterioration of electrical characteristics). Also, the heat treatment atmosphere is 02/(N2+O2)>0
．． In the case of 02, the oxidizing atmosphere becomes strong, increasing crystal defects (mainly dislocations), causing p-n junction leakage, and deteriorating the electrical characteristics of the device.

[Means to solve the problem]

The method of forming a buried layer by implanting As ions of the present invention uses a (111) P-type silicon substrate in particular. After ion implantation, b), the mixing ratio of pure nitrogen N2 and trace amount of oxygen 02 is 02/(N2
+O2) -0.02 or less gas atmosphere and heat treatment at a high temperature of 1200°C or more.

In other words, in contrast to the conventional method of forming two buried layers, the present invention specifically forms a thin insulating film 810. Forming 1-1 impure SAs
After implanting ions at a high dose, pure nitrogen N was used to obtain the desired profile.

and a trace amount of oxygen O3 at a mixing ratio of 02/(N 2 102
) Heat treatment is performed at a temperature of 1200° C. or higher in a gas atmosphere of 0.02 or lower.

In the present invention, in order to alleviate implantation damage, a thin insulating film Si○2 is formed on a silicon substrate, and an impurity As
After ion implantation at a high dose, the mixing ratio of pure nitrogen N2 and a trace amount of oxygen 02 is 02/(N 2 + O2) = 0
．． A desired profile is formed by heat treatment at 1200° C. or higher in a gas atmosphere of 0.02° C. or lower.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIGS. 1(a) to 1(b) are process cross-sectional views of an embodiment of the present invention.

Silicon substrate 1 with low concentration P type surface orientation (111)
SiO was applied to the entire upper surface in an oxidizing atmosphere containing water vapor at 950°C.
2 Film 2 was used as an ion-implanted protective film for 200 people. Thereafter, As ions 3 were implanted at an acceleration energy of 70 KeV and a dose of I x 10'' atoms/cml, and the mixing ratio of pure nitrogen N2 and a trace amount of oxygen 02 was 02/(N2
+ 02) = 1200℃ in a gas atmosphere of 0.02
A high temperature heat treatment was performed for 40 minutes. For comparison with conventional technology, As ion implantation was performed at 5×1015 and I×10
``It is directly applied to the entire surface of a silicon substrate with a low concentration P type plane orientation (111) at two levels of doses of atoms/cffl, and then pure nitrogen N is applied.

The mixing ratio of 0□ and a trace amount of oxygen is 02/(N 2 + 0
2) High temperature heat treatment at 1140° C. was performed for 3.5 hours in a gas atmosphere of =0.02. However, the heat treatment time is
Heat treatment was performed at 1140° C. for 3.5 hours to make the surface concentration and profile equivalent to the profile obtained at 1200° C. for 40 minutes.

After further performing the above heat treatment, the silicon epitaxial layer 5 is coated with dichlorosilane (S) and H in the well according to the present invention and the well according to the conventional technique.

Cj22), hydrochloric acid (HCL), hydrogen (H2) gas and phosphine (PH8) as a doping gas at a humidity of 108
A chemical reaction was carried out in a lamp heating furnace at 0° C. and a vacuum degree of 80 Torr to form an n-type buried layer 4 to a thickness of 2.2 μm.

After that, the well on which the silicon epitaxial layer was formed was immersed in the Wright etch solution for 1 minute to perform selective etching, and then the etch pits were observed using an optical microscope 4.
It was performed at 00x. The results are shown in FIG.

In the conventional method, an etch pit density of ~10'/cnt was observed, whereas in the buried layer forming method according to the present invention, no etch pit I was observed, demonstrating the superiority of the present invention.

Next, another embodiment of the present invention will be described using FIGS. 1(a) to 1(d) again.

A 5iOz film was formed on the entire surface of a silicon substrate with a low concentration P-type plane orientation (111) in the same manner as in Example 1, and As ions were accelerated at an energy of 70 K e V and a dose of 5.times.
Mixing ratio of pure nitrogen N2 and trace amount of oxygen 02 at 10"atoms/cn! 02/(N2+O2)=0.
A high-temperature heat treatment at 1200° C. was performed for 40 minutes in a gas atmosphere of 0.02. In order to compare with the conventional technology, a SiO2 film was formed on the silicon substrate, and As ions were implanted at an acceleration energy of 70 KeV and a dose of 5 x 1015 and 1 x 1016 at.
The heat treatment was carried out at two levels: oms/c clear, and the heat treatment atmosphere was 02/
(N 2 + 02) = 0.02, 1140°C
High temperature heat treatment was performed for 3.5 hours.

Further, in the same manner as in the first embodiment, a silicon epitaxial layer was grown to a length of 2.2 μm to form an n-type buried layer in each well.

Thereafter, crystal defect evaluation was performed in the same manner as in one example. The results are shown in FIG. In the conventional method, an etch pit density of about 103 holes/cnt was observed, whereas in the buried layer forming method according to the present invention, no etch pits were observed, demonstrating the superiority of the present invention.

〔Effect of the invention〕

As explained above, in the present invention, an insulating film 5iCh is formed as an ion implantation protection film on a silicon substrate with a P-type plane orientation (111), and As ions are implanted, and after the implantation, pure nitrogen N2 and a trace amount of Mixing ratio 02/ (N 2 +
By performing high-temperature heat treatment at 1200° C. in a gas atmosphere of 0.02) = 0.02 or less, damage caused by ion implantation can be completely recovered and a highly concentrated n-type buried layer can be easily formed.

[Brief explanation of drawings]

FIGS. 1(a) to 1(d) are one embodiment of forming a buried layer by As ion implantation according to the present invention, process sectional views of another embodiment, and a second embodiment of the present invention.
3 are diagrams showing crystal defect evaluation results according to the present invention and the conventional method. 1... Silicon substrate, 2... SiO2
Film, 3... As ion, 4... N-type buried layer, 5... Epitaxial layer.

Claims (2)

[Claims] (1) After forming a thin oxide film on the surface of a silicon substrate and implanting impurity ions into the surface of the silicon substrate through the oxide film, the mixing ratio of nitrogen N_2 and oxygen O_2 is O_2.
A method for manufacturing a semiconductor device, comprising the steps of performing heat treatment at a temperature of 1200° C. or more in a gas atmosphere of /(N_2+O_2)=0.02 or less, and then performing silicon epitaxial growth. (2) In a semiconductor device manufacturing method that forms a highly concentrated buried layer region by ion-implanting impurities ^7^5As^+, a thin insulating film SiO_2 is formed on a P-type silicon substrate with a plane orientation of (111). After forming and implanting impurity As ions at a high dose, in order to obtain the desired profile, the mixture ratio of pure nitrogen N_2 and a trace amount of oxygen O_2 is O_2/(N_2+O_2) = 1200 mL or less in a gas atmosphere of 0.02 or less. A method for manufacturing a semiconductor device characterized by a step of performing heat treatment at a temperature of ℃ or higher and then performing silicon epitaxial growth.