JPS6134966A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain sheet resistors with less scattering in performance characteristics by a method wherein an oxide film on an N type semiconductor substrate is subjected to etching, impurity is introduced for the formation of a P type semiconductor region, the oxide film is again etched before th growth of an nitride film, and a part of the nitride film is removed for the formation of a contact region to be developed into a resistor. CONSTITUTION:After oxidation of an N type semiconductor substrate 1 in an oxygen atmosphere for the formation of an oxide film 2, photo-etching is performed for the selective etching of the oxide film 2, and then a P type impurity is introduced into the semiconductor substrate 1 by the ion implantation method for the formation of a P type semiconductor region 4 to be a resistor. A process follows wherein photo-etching is effected for the selective etching of the oxide film 2 for the formation of a contact hole for another diffusion layer, the entire surface is covered by a nitride film 7 formed by the vacuum CVD method, photo-etching is effected for the selective etching of the nitride film 7 including the inside of the contact hole 6b for the completion of the contact hole 6b, and then metallizing is effected. By this method, in the absence of oxidation-induced scattering of concentration in the surface of the P type semiconductor layer 4, a high-precision ion-implanted resistor may be realized with ease.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a semiconductor device manufacturing method, particularly a semiconductor device in which a semiconductor region formed by introducing a thin material into a semiconductor substrate by an ion implantation method is used as a resistor. The present invention relates to a method for manufacturing a device.

(Prior Art) Conventionally, so-called ion implantation resistors, in which impurities are introduced into a semiconductor substrate by ion implantation and used as a resistor, have been widely used in semiconductor integrated circuits and the like because high resistance can be easily achieved.

However, in the conventional ion implantation resistor, after the thin material is introduced into the semiconductor substrate by the ion implantation method, an oxidation process is performed to use it as a mask for the next diffusion process or to prepare for the metallization process. An oxide film is formed on a semiconductor region into which p-type impurities have been introduced, but during this oxidation process, impurities on the narrow surface of the semiconductor substrate enter the oxide film, resulting in variations in the degree of impurity and a decrease in ion implantation resistance. This had the fatal drawback of causing variations in sheet resistance. In particular, the rate at which impurities enter the oxide film is greatly affected by changes in aging conditions.

(Problems to be Solved by the Invention) An object of the present invention is to eliminate the drawbacks of the conventional method for manufacturing an ion-implanted resistor, and to obtain a resistor with less variation in sheet resistance.

(Means for Solving the Problems) According to the present invention, - a step of growing an oxide film on a conductive type semiconductor substrate, a step of selectively etching the oxide film by photolithography, and a step of selectively etching the oxide film by photolithography; A step of introducing impurities of other conductivity type into the semiconductor substrate by ion implantation using the oxide film as a mask to form a semiconductor region of another conductivity type, and then further selectively etching the oxide film by photolithography. a step of exposing other regions of the semiconductor substrate, and then a step of growing a nitride film over the entire surface, and selectively removing a part of the nitride film on the other region where the oxide film has been removed to form a contact portion. A semiconductor device 1 characterized in that the other conductive type semiconductor region is used as a resistor.
Obtain the manufacturing method of d.

(Example) Hereinafter, the present invention will be explained in more detail using the drawings.

FIG. 2 is a cross-sectional view at each step showing an example of a conventional method for manufacturing an ion-implanted resistor. First, an N-type semiconductor substrate 1 is prepared (FIG. 2(a)), and this N-type semiconductor substrate 1 is oxidized in an oxidizing atmosphere to form an oxide film 2 (FIG. 2(b)).
Next, the oxide film 2 was selectively etched by photolithography to form an opening region 3 (FIG. 2(c)), and then the fiP type impurity region 4 was formed by ion implantation (FIG. 2(c)). After forming the oxide film 5 through a post-oxidation process (Fig. 2(d)), the oxide film 2 is selectively removed by photolithography.
A recess or contact hole 6a for forming an impurity diffusion region in the next step is formed by etching (FIG. 2(f)).
).

In this conventional manufacturing method for ion-implanted resistors, the oxidation process is performed after introducing fine particles by ion implantation, so variations in oxidation do not directly result in variations in the sheet resistance of the ion-implanted resistors, making them inherently highly accurate. The drawback was that the advantages of the ion implantation method were not fully utilized.

The present invention eliminates the fatal drawbacks of the above-mentioned method of manufacturing ion implanted resistors.

FIG. 1 shows a cross-sectional view of a valley manufacturing process according to an embodiment of the present invention. First, prepare the N-type semiconductor substrate 1 (see Figure 1 (Ta)).
After this N-type semiconductor substrate 1 was oxidized in an oxidizing atmosphere to form an oxide film 2 (FIG. 1(b)), the oxide film 2 was selectively etched by photolithography as shown in FIG. 1(c). ), a 9P type impurity is introduced into the semiconductor substrate 1 by ion implantation to form a P type semiconductor region 4 to form a resistor as shown in FIG.
d) ) S Next, after selectively etching the oxide film 2 using a photolithography process to form a contact hole 6b for another diffusion layer (FIG. 1(e)), a nitride film is formed on the entire surface using a low pressure CVD method. 7 (Fig. 1(f)) s Next, the nitride film 7 is selectively etched including the inside of the contact hole 6b using a photographic technique to complete the contact hole (Fig. 1(g)), and then This is a metallization process.

According to the present invention, since there is no oxidation step after introducing the P-type impurity using the ion implantation method, there is no variation in the surface concentration of the P-type semiconductor layer 4 due to oxidation, so a highly accurate ion implantation resistor can be easily realized. There is a big advantage that it can be done.

It goes without saying that the above description holds true even if the conductivity types are interchanged.

(Effects of the Invention) According to the present invention, a resistor having a sheet resistance that is not affected by heat treatment conditions after ion implantation can be obtained.

[Brief explanation of drawings]

FIGS. 1(a) to (g) are cross-sectional views of each manufacturing process according to an embodiment of the present invention, and FIGS. 2(a) to (f) are cross-sectional views of conventional manufacturing processes. 1... N-type semiconductor substrate, 2... Oxide film, 3... Old oxide film opening, 4... P-type semiconductor region, 5... ...Oxide film, 6a...Opening part,
6b...Opening portion, 7...Nitride film, 8.
...opening area. Kana l @ Figure 2

Claims (1)

[Claims] A step of growing an oxide film on a semiconductor substrate of one conductivity type, a step of selectively etching the oxide film by photolithography, and an ion implantation method using the oxide film as a mask to implant impurities of another conductivity type into the semiconductor substrate. A step of introducing the oxide film into the substrate to form another conductive type semiconductor region, a step of selectively etching the oxide film by photolithography to expose another region of the semiconductor substrate, and then nitriding the entire surface. a step of growing a film and selectively removing a nitride film on the other region to form a contact portion, and using the semiconductor region of the other conductivity type as a resistor. Method of manufacturing the device.