JPS639934A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the generation of the decrease of disconnections, etc. positively in a wiring in an opening section in a film on a substrate even when evaporation for the wiring is conducted to the opening section by forming the peripheral wall of the opening section to a tapered shape without being formed to a vertically steeply risen shape. CONSTITUTION:A photo-resist film 3 formed to the surface of a substrate 1 is exposed so that an exposure value in the periphery of an opening-section forming region is changed toward the outside of the periphery of the opening- section forming region from the periphery of the opening-section forming region and developed. The side wall of the opening section 10 shaped to the photo-resist film 3 is formed to a tapered shape that it is widened toward an upper section by the development. The substrate 1 is etched and treated, using the photo-resist film 3 as a mask. Accordingly, the opening is formed to the tapered shape especially when shaping the opening section in step coverage, thus preventing the generation of disconnections on wirings.

Description

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

(Prior Art) As is well known, when manufacturing semiconductor devices, photolithography processes various films formed on a substrate into a predetermined pattern by selectively etching them using a mask. As semiconductor devices become increasingly smaller and finer, anisotropic etching techniques with less side etching are increasingly used.

and 1 for exposing the photoresist prior to etching.
Usually, ultraviolet rays are irradiated, but this ultraviolet ray is usually irradiated perpendicularly to the substrate.

Through holes having vertical walls are formed in the developed photoresist film. Therefore, the side walls of the windows opened in various films that are anisotropically etched using this resist film as a mask generally become steep vertical walls.

For this reason, for example, if this window is used as an opening (contact hole) for attaching an electrode, and wiring is performed by vapor-depositing aluminum, etc., a large amount of vapor is deposited on the edge of the opening. However, the amount of evaporation in other parts is reduced, and as a result, contact with the wiring may result in disconnection.

(Problems to be Solved by the Invention) The present invention relates to etching processing in the manufacturing process of semiconductor devices, and in particular, when forming an opening in step coverage, the sidewalls of the opening formed in the photoresist film are not vertical. The purpose of this is to prevent the occurrence of disconnection in the wiring by forming the opening in a tapered shape that widens upward.

(Means for Solving the Problems) The present invention controls the exposure amount around the opening formation region of the photoresist film so that it changes from the periphery of the opening toward the outside thereof, and thereby It is characterized in that the side wall is developed so as to spread out as it goes upward.

(Function) When a photoresist is irradiated with ultraviolet rays for exposure, the amount of development varies depending on the amount of exposure.

Therefore, for example, if the exposure amount is gradually decreased as it goes outward from the periphery of the opening forming area,
During subsequent development, even if the opening forming area is completely developed, the periphery thereof expands outward toward the top. That is, the opening has a tapered sidewall that expands outward.

Therefore, when the underlying film is etched using the photoresist film as a mask, the sidewalls of the portions of the photoresist film corresponding to the openings are etched into a tapered shape that widens upward. Therefore, if the lower film is opened in this way, even if aluminum is deposited in the opening, it will be deposited with a substantially uniform thickness not only on the surface but also on the side walls.

(Example) In 6 diagrams illustrating an example of this invention, 1
is a semiconductor substrate, and here we will explain the case where an oxide film 2 formed on the surface thereof is photoetched.

First, a positive photoresist film 3 is coated on the surface of the oxide film 2 to form it. The surface is then exposed to light using a mask 4. Here, as shown in FIG. and non-transparent part 6
is formed, and the non-formed portion is defined as a transparent portion 7.

According to the present invention, the amount of transmission of the exposure wavelength is made to decrease as the periphery of the light-transmitting portion 7 goes outward.

Specifically, as shown in FIG. 1, the non-transparent part around the transparent part 7 is formed to become thicker stepwise from the periphery of the transparent part 7 to the outside. This is a tapered part of the fabric formed in this way.

In order to form such a tapered portion 8, the light-shielding material may be applied in multiple layers so that the peripheral edge of the light-transmitting portion 7 becomes tapered one after another.

The photoresist film 3 is coated through the mask 4 having such a structure.
When exposed to ultraviolet rays, the portion facing the transparent portion 7 is sufficiently exposed, but the portion facing the tapered portion 8 is exposed depending on the thickness of the tapered portion 8. I'm going to go. In other words, the portion facing the thicker portion of the tapered portion 8.

This reduces the amount of exposure.

When the photoresist film 3 exposed in this way is developed, the portion facing the light-transmitting portion 7 is removed to form the opening 9, as shown in FIG. It is developed accordingly and becomes tapered.

Then, using this photoresist gI3 as a mask, the oxide film 2 is anisotropically etched. As this etching process progresses, the portion facing the opening 9 is gradually removed, and an opening 1° is formed there.

However, since the peripheral wall of the opening 9 of the photoresist film 3 is tapered, the opening 1o formed in the oxide film 2
Its peripheral wall is tapered (see Figure 3).

After this, the photoresist film 3 is removed.

Wiring is formed by vapor-depositing aluminum on the surface of the oxide film 2. Since the peripheral wall of the opening 10 is tapered, the electrode film 11 formed by vapor-depositing aluminum is also formed as shown in FIG. In this way, it adheres to the peripheral wall of the opening 10 almost evenly and with approximately the same thickness as the flat part. Therefore, there is no disconnection caused by non-uniform film thickness as in the conventional case.

(Effects of the Invention) As described in detail above, according to the present invention, when photoetching a film on a substrate, the peripheral wall of the opening of the film is not shaped vertically as in the conventional case. Since the opening is tapered instead, vapor deposition for wiring can be performed on the opening.

This has the effect of reliably preventing the occurrence of wire breakage or other problems in the wiring.

[Brief explanation of the drawing]

1 to 4 are cross-sectional views showing steps of an embodiment of the present invention.

Claims (1)

[Claims] The photoresist film formed on the surface of the substrate is exposed to light such that the amount of exposure around the opening formation area changes from the periphery of the opening formation area toward the outside, and then developed. A method for manufacturing a semiconductor device, wherein the side wall of the opening formed in the photoresist film has a tapered shape that widens upward, and then the substrate is etched using the photoresist film as a mask. .