JPS62274729A - Manufacturing method of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain the contact hole having an ideal cross-sectional form by a method wherein an insulating films consisting of two layers of a silicon dioxide film and a silicon nitride film is formed using the silicon nitride film on the upper layer, and after isotropic etching has been performed thereon, anisotropic etching having excellent dimensional controllability with the lower layer of silicon nitride film is conducted. CONSTITUTION:An SiO2 film 105 and an Si3N4 film 106 are formed on the semiconductor substrate 101 whereon an MOS transistor is formed, and an insulating film of double-layer structure is completed. Then, a pattern is formed using a photoresist 107, and the Si3N4 film 106 is etched. In this case, isotropic etching is performed in order to obtain an inclined form, the SiN film is removed, and the etching operation is suspended when the SiO2 film 5 is exposed. At this point, the SiO2 film is changed into the state in which an etching operation can be performed, and the SiO2 film 105 is etched continuously. At this time, as the etching is performed on the SiO2 film in a complete anisotropic manner, the SiO2 film 105 is formed into almost vertical shape, and lastly, the photoresist 107 is removed.

Description

[Detailed description of the invention] 3. Detailed description of the invention [Industrial application field] The present invention relates to a method for manufacturing a semiconductor device.

[Conventional technology]

A conventional method for manufacturing a semiconductor device using a MOS transistor as an example is as follows. That is, 2-(
A) Source, drain 202 and gate 2 as shown
After forming a silicon dioxide film (hereinafter abbreviated as Si0g film) 205 as an insulating film on the semiconductor substrate 201 on which a MOS transistor consisting of 04 was formed, as shown in Figure 2-(B),
2-(C) An opening pattern is formed using photoresist 207 as shown in FIG. Next, as shown in Fig. 2-(D), the 5i02 film is etched using the photoresist 207 as a mask, and then the photoresist 207 is removed as shown in Fig. 2-(E). , a contact hole was formed in the drain 202 portion for establishing electrical conduction.

[Problem that the invention seeks to solve]

However, in the conventional technology, as shown in Figure 2-(D), when the SiO film 205 is etched by dry etching, the etching progresses only in the depth direction and hardly in the lateral direction. The shape of the contact hole is vertical as shown in Figure 2-(E), and the source or drain 10 is connected through the contact hole.
2 and other elements using metal wiring, the metal wiring sometimes breaks at the contact hole portion.

The present invention solves these problems in the conventional semiconductor device manufacturing method, and its purpose is to easily form a contact hole having an ideal inclined shape to prevent disconnection of metal wiring. An object of the present invention is to provide a method for manufacturing a semiconductor device that is more stable and reliable.

[Means for solving problems]

The method for manufacturing a semiconductor device of the present invention includes the step of forming a silicon dioxide film as a first insulating film on a semiconductor substrate on which elements such as transistors, diodes, and resistors are formed, and forming a second silicon dioxide film on the silicon dioxide film. a step of forming a silicon nitride film as an insulating film, a step of forming an opening pattern using a photoresist on the silicon nitride film, a step of isotropically etching the silicon nitride film using the photoresist as a mask, and The method is characterized in that it subsequently includes a step of anisotropically etching the silicon dioxide film using the photoresist as a mask.

[Effect]

According to the above structure of the present invention, by forming the two-layer structure of the insulating film, that is, the silicon dioxide film as the first insulating film and the silicon nitride film as the second insulating film, the silicon nitride film can be easily formed isotropically. Since the etching can be carried out in a uniform manner, a contact hole having an inclination can be easily formed, and disconnection of the metal wiring at the contact hole portion can be greatly reduced.

〔Example〕

1-(A) to 1-(G) are cross-sectional views according to the manufacturing process of a semiconductor device in an embodiment of the present invention, and are MO3I
- Formation of an insulating film and contact hole on a transistor was shown as an example.

In the embodiment of the present invention, a MOS transistor is first formed on a semiconductor substrate 101 as shown in FIG. 1-(A).
102 is a source, a drain, 103 is a gate film, 1
04 is a gate electrode.

The method for forming the insulating film and the contact hole will be described in detail below.

As shown in Figure 1-(B), after forming the S + Oz film 105 as a first insulating film on the semiconductor substrate 10 on which a MOS transistor has already been formed, as shown in Figure 1-(C), A silicon nitride film (hereinafter abbreviated as s i3 N4 W!J) is directly formed as a second insulating film on the 5iOz film 105 to complete a two-layer insulating film.

Next, as shown in Figure 1-(D), a photoresist 10
Pattern formation is performed in step 7.

Next, as shown in Figure 1-(E), a photoresist 10
Using 7 as a mask, the Si N film +06 is etched. If this etching is performed using a dry etching method, it is possible to achieve completely anisotropic etching, that is, the shape of the contact hole is vertical, depending on the etching conditions.
In this case, in order to obtain a sloped shape, isotropic etching is performed to remove the SiN film and remove the SiO□ film 10.
Etching is interrupted when 5 is exposed. Now, if the conditions are changed to etching the 5102 film and then the 5ift film 105 is etched, the result will be as shown in Figure 1-(F). At this time, since the SiO□ film is etched completely anisotropically, the shape of the Si film 105 is almost vertical. Finally, photoresist 10
By removing 7, the cross-sectional structure shown in FIG. 1-(G) is obtained.

[Effects of the Invention] As described above, according to the present invention, an insulating film consisting of two layers, a silicon dioxide film and a silicon nitride film, is formed, and a silicon nitride film that can be easily isotropically etched is used as the upper layer. By isotropically etching this and then etching it with the underlying silicon dioxide film using anisotropic etching with good dimensional control, a contact hole with good dimensional control and an ideal cross-sectional shape can be obtained. This makes it possible to extremely reduce the probability of metal wiring breaking when attempting to provide metal wiring in an upper layer.

Furthermore, compared to the conventional insulating film of a single layer of silicon dioxide film, since a silicon nitride film is also used,
Since the ability to block impurity ions that adversely affect devices is improved, the reliability of semiconductor devices is also greatly improved.

[Brief explanation of drawings]

FIGS. 1A to 1G are cross-sectional views of the manufacturing process of a semiconductor device according to an embodiment of the present invention. FIGS. 2(A) to 2(E) are cross-sectional views showing the manufacturing process of a conventional semiconductor device π. 101.201...Semiconductor substrate 102.202
...Source, drain 103.203...
...Gate film 104.204...Gate electrode 105.205
...Silicon dioxide film 106...
......Silicon nitride film 107.207...
・・・Photoresist and above Applicant Seiko Epson Co., Ltd. Agent Patent Attorney Mogami Tsutomu N and 1 other person,・′・″

Claims (1)

[Claims] A step of forming a silicon dioxide film as a first insulating film on a semiconductor substrate on which elements such as transistors, diodes, and resistors are formed, and a step of forming a silicon nitride film as a second insulating film on the silicon dioxide film. , forming an opening pattern with a photoresist on the silicon nitride film, isotropically etching the silicon nitride film using the photoresist as a mask, and subsequently etching a silicon dioxide film using the photoresist as a mask. 1. A method for manufacturing a semiconductor device, comprising the step of etching anisotropically.