JPH01310534A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of electrostatic breakdown as well as to contrive improvement in reliability by a method wherein a multilayer film, consisting of at least two or more kinds of layers consisting of different materials including at least a conductive film, is used as a mask in a impurity implanting process. CONSTITUTION:An insulating film 2 for isolation, thin insulating films 3a and 3b, and a polysilicon gate 4 are formed on the desired place on an Si substrate 1, and an oxide film 6, which is a first layer mask, is formed on the whole surface. Then, a conductivity film 7 is coated on the whole upper surface as a second layer mask, a photoresist 5 is coated on the whole upper surface of the conductivity film 7, a desired pattern is formed, and an aperture is provided. Then, using the photoresist 5 as a mask, the conductivity film 7, the oxide film 6 and the thin oxide film 3b are removed successively, the photoresist 5 is removed, and impurity ions 8 are implanted in the state wherein the conductivity film 7 is exposed to the top surface. At this time, the positive electric charge implanted in the conductivity film 7 is discharged along the film 7, after the implanting work has been finished, the conductivity film 7 and the oxide film 6 are removed. As a result, the occurrence of electrostatic reliability and the yield of production can be achieved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, and in particular, during an ion implantation process in which impurity ions are implanted into a predetermined region, the semiconductor device is charged up and an insulating thin film within the semiconductor device is damaged. The present invention relates to a method of manufacturing a semiconductor device that is free from electrostatic damage.

[Conventional technology]

FIG. 2 is a cross-sectional process diagram showing a conventional method for manufacturing a semiconductor device. In the figure, 1 is a Si substrate, 2 is an insulating film for element isolation (generally 5io2), and 3a and 3b are thin insulating films. , 4 is a polysilicon gate. Further, 5 is a photomask for implanting impurity ions into a desired Si substrate.

Next, the manufacturing process will be explained. First, as shown in FIG. 2(a), the thin insulating film 3b is removed using the photomask 5 as an etching mask, and then impurity ions 8 are implanted into the semiconductor device using an ion implanter as shown in FIG. Inject all over. At this time, the photomask 5 is positively charged, the amount of charge increases, and the moment the Si substrate 1 is grounded, the weakest thin oxide film 3a is shown in FIG. 2 (C1).
Destroy and short circuit. As a result, the semiconductor device loses its normal function.

[Problem to be solved by the invention]

Since the conventional method for manufacturing a semiconductor device is configured as described above, there is a problem in that electrostatic discharge damage occurs in the ion implantation process and the semiconductor device loses its function.

Currently, there is a method for preventing this electrostatic damage by drastically reducing the injection current value, but this reduces productivity. or,
There are means to provide antistatic measures to ion implanters, but they are expensive and incomplete.

This invention was made to solve the above-mentioned problems, and its purpose is to provide a highly reliable and high-yield method for manufacturing semiconductor devices that does not cause electrostatic damage during the ion implantation process. .

[Means to solve the problem]

A method for manufacturing a semiconductor device according to the present invention includes implanting impurities using a film having a multilayer structure of two or more layers made of two or more different materials including at least one type of conductive film as a mask in the impurity implantation step. This is what I did.

[Effect]

In this invention, since impurity implantation is performed using a conductive mask, electrostatic damage during the ion implantation process can be prevented.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a cross-sectional process diagram showing a method of manufacturing a semiconductor device according to an embodiment of the present invention. In the figure, 1 is a Si substrate 1.2
is an insulating film for element isolation (generally 5tou), 3a, 3
b is a thin insulating film, 4 is a polysilicon gate, 5 is a photoresist, 6 is an oxide film as a first Nth mask, 7 is a conductive film (for example, AN) as a second layer mask, 8
is the impurity ion to be implanted.

Next, the manufacturing process will be explained.

First, as shown in FIG. 1 (al), an isolation insulating film 2 and a thin insulating film 3a are deposited on desired locations on a Si substrate l.

3b, after forming the polysilicon gate 4, an oxide film 6 serving as a first layer mask is formed over the entire surface of the semiconductor device.

Examples of this forming method include low-temperature CVD and coating methods.

Next, as shown in FIG. 1(b), a conductive film 7 is coated over the entire surface of the oxide film 6 as a second layer mask. Furthermore, as shown in FIG. 1(C), a photoresist 5
is applied over the entire surface of the conductive film 7 to form a desired pattern and provide openings. Subsequently, as shown in FIG. 1(d), using the photoresist 5 as a mask, conductive film 7° oxide film 6 and thin oxide If! 3b are removed in order.

Then, as shown in FIG. 1(e), the photoresist 5
With the conductive film 7 exposed at the outermost surface by removing the conductive film 7, impurity ions 8 are implanted using an ion implanter. At this time,
The positive charges injected onto the conductive film 7 are discharged through the conductive film 7, and the semiconductor device is not charged as shown in FIG. 1 if). After the implantation is completed, as shown in FIG. 1(g), the conductive film 7 and the oxide film 6 are removed to complete the implantation process.

As described above, in this example, the mask used in the ion implantation process has a two-layer structure consisting of an oxide film, GL, and a conductive film, so that the positive charges injected during ion implantation are discharged through the conductive film. Therefore, electrostatic damage to the semiconductor device due to charging of the mask can be prevented.

(Effects of the Invention) As described above, according to the present invention, since impurity ion implantation is performed using a mask with a multilayer structure including a conductive film, the semiconductor device is highly reliable without electrostatic damage due to charging. , and has the effect of realizing a high-yield semiconductor device manufacturing method.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional process diagram showing a method for manufacturing a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional process diagram showing a conventional method for manufacturing a semiconductor device. 1 is a Si substrate, 2 is an isolation insulating film, 3 is a thin gray border film,
4 is a polysilicon gate, 5 is a photoresist, 6 is a first layer mask (oxide film), 7 is a second layer mask (conductive film), and 8 is an impurity ion. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) In a method for manufacturing a semiconductor device, in an ion implantation step in which impurity ions are implanted into a predetermined region, a film having a multilayer structure of two or more layers made of two or more different materials including at least one type of conductive film is masked. 1. A method for manufacturing a semiconductor device, characterized in that the method is used as a semiconductor device.