Method of manufacturing a semiconductor device

Abstract

In a patterning process of a semiconductor device having inverted stagger type TFTs, a normal photolithography step using diazo naphthoquinone (DNQ)-Novolac resin based positive photo resist is applied, and a problem of the area dependency of the photo resist pattern side wall taper angle may occur. The problem is critical for the reason of influence on variation of an etching shape in a dry-etching step. The present invention has an object to solve the above problem. In a photolithography step, which is patterning step of a semiconductor device having inverted stagger type TFTs, by adjusting a pre-bake temperature or a PEB (post-exposure-bake) temperature, and positively performing evacuation of solvent in a state of a photo resist film, the volume contraction by evacuation of solvent at the post-bake is reduced, and the problem of the area dependency of the photo resist pattern side wall taper angle is solved, which is deformation due to the volume contraction.

Description

TECHNICAL FIELD TO WHICH THE INVENTION BELONGS[0001] The present invention relates to a semiconductor device having a circuit formed of thin film transistors (thereafter, referred to as TFTs) and a method of manufacturing the same. The semiconductor device includes, for example, an electro-optical device such as a liquid crystal display formed of TFTs.[0002] More specifically, the present invention relates to a method of manufacturing a semiconductor device having inverted staggered type TFTs with a bottom gate structure, and more particularly to a photolithography for patterning the semiconductor device.PRIOR ART[0003] In recent years, an active matrix liquid crystal display technology using TFTs is of great interest. Since an active matrix display is provided with a TFT switch on each pixel, a liquid crystal orientation state of TN (i.e., twisted nematic) mode is available, and it is advantageous in terms of response speed, viewing angle and contrast, compared with a passive matri...

AI Technical Summary

Benefits of technology

[0012] It is an object of the present invention to provide an semiconductor device formed of inverted stagger type TFTs and a method of manufacturing the same, which can solve the above described problems.

[0020] In the normal photolithography step consisting of a combination of the diazo naphthoquinone (DNQ)-Novolac resin based positive photo resist and a reduction projection exposure apparatus (also referred to as a stepper) which is a single wavelength (g-ray and i-ray of high-pressure mercury-vapor Lamp) exposure apparatus, it is considered that volume contraction phenomenon in the resist pattern due to evacuation of residual solvent at the post-bake causes a pattern deformation on the side wall of large area photo resist pattern (about 10 .mu.m or more). Accordingly, it is expected that if PEB temperature for baking the entire resist film after exposure is equal to or greater than the post-bake temperature, evacuation of solvent component at the PEB process is promoted, and evacuation of the solvent from the resist pattern at post-bake is relatively reduced.

[0024] Accordingly, it is demonstrated that the pattern deformation with variation in the resist taper angle in the large area photo resist pattern is effectively controlled by rising PEB temperature equal to or higher than the post-bake temperature (see FIGS. 2A and 2B).

[0032] Accordingly, in accordance with the present invention, a solution is provided which can solve a problem of the area dependence of the photo resist pattern side wall taper angle inducing the deformation phenomenon due to volume contraction occurred by evacuation of solvent from the photo resist pattern at the post-bake.

Problems solved by technology

Since various dimensions of circuit patterns exist in a liquid crystal display, deformation in the resist pattern with variation in taper angle depending on variation in the area of the resist pattern influences the etched shape, and thus is a critical problem.

In this case, since a plurality of thin film layers are patterned simultaneously using the resist pattern as a mask, variation of the resist pattern side wall taper angle is a critical problem because it is observed that it also greatly influences the etched shape.

Images