JPS6247166A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enhance a yield and to reduce a leakage current by coating an insulating film on a semiconductor substrate, opening a window, deeply diffusing one conductivity type region, then expanding the area of the window, coating the entire surface with a reverse conductivity type diffusion source film, and heat treating it to form a region having a wide area and a shallow reflection conductivity type on one conductivity type region. CONSTITUTION:An insulating film 11 is coated on a semiconductor substrate 10, a window is opened, and an N<+> type region 12 is formed at a deep position by thermal diffusing or ion implanting. Then, the window of the opened film 11 is expanded with the mask, and the entire surface which includes the expanded hole 13 is coated with a reverse conductivity type diffusion source film 14. Thereafter, a P<+> type region 15 having a wider area than the region 12 is disposed on the region 12 by heat treating to form a semiconductor device such as a varicap diode. Thus, the manufacturing yield is improved, and a leakage current level is improved.

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a semiconductor device.

[Technical background of the invention and its problems]

Conventionally, a semiconductor device comprising a so-called vari-gap diode has been manufactured as follows.

First, as shown in FIG. 4, an insulating film 2 having a thickness of about 1 μm is formed on the main surface of a semiconductor substrate 1 by thermal oxidation. Then,
The insulator film 2 is selectively etched to form an opening exposing a predetermined region of the semiconductor substrate I. Next, using this insulating film 2 as a mask, a high concentration impurity region 3 of a predetermined conductivity type is formed in the semiconductor substrate 1 by thermal diffusion or ion implantation. Next, after enlarging the bottom part of the opening by selective etching, the diffusion source film 4 of the opposite conductivity type to the high concentration impurity region 3 is coated with CvD so as to cover the high concentration impurity region 5 and the exposed surface of the conductive substrate 1. (Chamlcal Vapor De
It is formed on the insulating film 2 by the position method or the like. Next, the diffusion source film 4 is subjected to heat treatment to form an impurity region 5 of the opposite conductivity type, which is wider than the high concentration impurity region 3 and has a shallow diffusion depth, and covers about 60% of the region. Next, impurity region 5
A contact hole 6 for forming an electrode connected to is opened in the diffusion source film 4 to expose the main surface of the impurity region 5.

Thereafter, heat treatment is performed with the contact hole 6 open to form a predetermined impurity region 5. Next, after forming an electrode (not shown) connected to impurity region 5 through contact hole 7, back electrode 7 is formed on the back side of semiconductor substrate 1 to obtain a semiconductor device.

In this Hiko semiconductor device manufacturing method, since the contact hole 6 is opened in the diffusion source film 4 when forming the impurity region 5, there is a problem that the surface concentration of the impurity region 5 decreases and leakage current increases. there were. Furthermore, since the formation of the impurity region 5 is not completed in one heat treatment process, there is a problem that the yield υ cannot be sufficiently improved.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a semiconductor device that can easily produce a semiconductor device with improved yield and leakage current level.

[Summary of the invention]

The present invention provides a semiconductor device with improved yield and leakage current level by providing a step of completely forming an impurity region of the opposite conductivity type with the diffusion source film remaining. This is a method of manufacturing a semiconductor device that can be easily performed.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings. First, as shown in FIG. 1, an insulating film II having a thickness of about 1/zm is formed on the main surface side of a semiconductor substrate IO by thermal oxidation. Next, the semiconductor substrate 1 is etched by selective etching.
An opening (not shown) that exposes a predetermined area of
Form II.

Next, a high concentration impurity region 12 is formed at a predetermined diffusion depth in the semiconductor substrate 10 using the insulating film 1 as a mask by thermal diffusion or ion implantation.

The opening is then enlarged (by selective etching). Next, a diffusion source film 14 having a conductivity type opposite to that of the high concentration impurity region 12 is formed on the insulating film 11 so as to close the region exposed through the enlarged opening 13 . After that, the diffusion source membrane 14
A heat treatment is performed to completely form an impurity region 15 of the opposite conductivity type, which is wider and shallower than the high concentration impurity region 12. Next, a contact hole communicating with a predetermined region of impurity region 15 is opened in diffusion source Mz4, and an electrode (not shown) connected to impurity region 15 through this contact hole is formed.

Next, a predetermined back electrode 16 is formed on the back side of the semiconductor substrate lO.
A semiconductor device is obtained by forming.

In this way, in this method of creating a semiconductor device, the impurity region 15 is completely formed with the surface covered with the diffusion source film 14 before the contact hole is opened, so that the surface concentration of the impurity region 150 is prevented from decreasing. It is possible to prevent this and suppress an increase in leakage current. Incidentally, it was experimentally confirmed that the leakage current level of the semiconductor device obtained in the example was in the range of 0.1 to 1 nA, as shown in FIG. On the other hand, it has been experimentally confirmed that in semiconductor devices obtained by conventional methods, the leakage current level IR is in the range of 1 to 10 nA as shown in FIG.

Furthermore, in the semiconductor device manufacturing method of the embodiment, since impurity region 15 is completely formed by one heat treatment, the yield can be significantly improved. Incidentally, it has been experimentally confirmed that the yield can be improved by 20 to 30% compared to conventional methods.

〔Effect of the invention〕

As described above, according to the method for creating a semiconductor device according to the present invention, a semiconductor device with improved yield and leakage current level can be easily obtained.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an embodiment of the present invention, Figs. 2 and 3 are characteristic diagrams showing the relationship between leakage current level and number of pieces, and Fig. 4 is an explanatory diagram showing a conventional method. be. 10... Semiconductor substrate, 11... Insulating film, 12...
High concentration impurity region, 13... Opening, 14... Diffusion source film, 15... Impurity region, 16... Back electrode. Applicant's attorney Takehiko Takehiko 61 Figure 1 Figure 4 (nA) (nA) Figure 3
Figure 2

Claims (1)

[Claims] forming an insulating film on the main surface of a semiconductor substrate of one conductivity type; forming an opening in the insulating film to expose a predetermined region of the main surface; forming a high concentration impurity region, enlarging the opening, and forming a diffusion source film of a conductivity type opposite to that of the high concentration impurity region on the insulating film so as to close the enlarged opening. and a step of performing heat treatment on the diffusion source film to form an impurity region of the opposite conductivity type that is wider and shallower in the surface region of the high concentration impurity region. Production method.