JPH07168368A - Formation of resist pattern and thin-film metallic pattern - Google Patents

Abstract

PURPOSE:To provide a method for forming resist patterns of stencil shapes having heat resistance and a method for forming good thin-film metallic patterns which do not generate burrs by a lift-off method with the resist patterns as a mask. CONSTITUTION:This method for forming the thin-film metallic patterns includes a stage for forming a resist 2 on a semiconductor substrate 1, then subjecting the resist to desired pattern exposing and org. solvent treatment to form a hardly soluble layer on the front layer part of the resist 2, a stage for developing the sectional shapes of the resist patterns to the stencil shapes having eaves formed wider in the apertures of the substrate surface than the apertures of the front layer part of the resist, a stage for irradiating the resist patterns having the stencil shapes with far UV rays 6 to impart heat resistance thereto and a stage for depositing a thin metallic film by evaporation with these resist patterns as a mask, then removing the resist patterns, thereby forming the thin-film metallic patterns on the semiconductor substrate 1. As a result, the deformation of the resist patterns having the stencil shapes does not arise even if there is a temp. rise by the vapor deposition of the thin-film metal and, therefore, the good thin-film metallic patterns free from the burrs are obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a thin film metal pattern on a semiconductor substrate by a lift-off method,
In particular, the present invention relates to a method for forming a good thin film metal pattern without burrs by applying heat resistance to a resist pattern after processing a resist pattern into a stencil shape having an overhang shape and using the resist pattern as a mask.

[0002]

2. Description of the Related Art A lift-off method is known as a method for forming a thin film metal or metal wiring on a semiconductor substrate. In this method, it is necessary to form a stencil for processing the resist cross-section into an overhang shape in order to facilitate lift-off of thin film metal or the like to be vapor-deposited. If the length of the stencil-shaped eaves is insufficient, the cutting of the thin-film metal after lift-off is likely to be incomplete, and there is a problem in that burrs are formed at the ends of the thin-film metal. Thus, in the lift-off method, the cross-sectional shape of the stencil greatly affects the quality of the thin film metal pattern after lift-off. Organic solvent treatment has been reported as a method of forming a stencil for lift-off [M. Hatzakis: Single-Step Optical Lift-Off Pro
cess, IBM J.Res.Develop.vol.24, No.4, (1980), p.45
2]. Here, a predetermined resist is formed on a semiconductor substrate, and an organic solvent dipping method of a resist using an organic solvent such as chlorobenzene or brombenzene is the best method before pattern exposure or after pattern exposure. It is said that there is. Overhang due to the difference in development speed between the exposed and unexposed areas of the modified layer (poorly soluble layer) formed on the surface layer of the resist and the non-modified layer (soluble layer) below It is believed that parts are formed. FIG. 3 shows an example of a case where a resist 2 is formed on a semiconductor substrate 1, a desired pattern exposure and brombenzene immersion treatment are performed, and then a development treatment is performed to form a stencil-shaped resist pattern. As is clear from the figure, the stencil of the overhang 3 is formed. With this stencil shape, the eaves with a large overhang can be obtained by lowering the resist pre-bake temperature and prolonging the immersion time of the organic solvent such as brombenzene.
FIG. 4 is a resist pattern in which a thin film metal (for example, a gold (Au) film having a thickness of 1 to 2 microns) 4 is vapor-deposited on a resist pattern on which a stencil having a good shape is formed. The cross-sectional shape of is shown. In order to form the thick thin film metal 4, it is necessary to evaporate in a vacuum for a long time. At this time, the temperature of the semiconductor substrate rises due to the heat source for melting the evaporating metal and the latent heat of the evaporated metal. Occurs, the resist pattern on which the stencil having a good shape is formed is deformed, and even if lift-off treatment is performed with an organic solvent (generally, acetone or the like), the thin metal film 4 is not cut as shown in the figure. There is a problem that the thin film metal 4 is completely formed with burrs 5 or the like at the end of the thin film metal 4, or the lift-off process cannot be performed.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the prior art and to improve the cross-sectional shape of a resist pattern in a method of forming a thin film metal pattern on a semiconductor substrate by a lift-off method. A method of forming a heat-resistant resist pattern that is processed into an overhang stencil shape, and a thin-film metal is formed by using the above heat-resistant resist pattern as a mask. It is an object of the present invention to provide a method for forming a thin film metal pattern that can obtain a good thin film metal pattern that does not occur.

[0004]

In order to achieve the above object of the present invention, in a method of forming a thin film metal pattern on a semiconductor substrate by a lift-off method, the shape of the resist pattern is changed by the effect of heat of vapor deposition of the thin film metal. A step of imparting heat resistance to the resist pattern is added by irradiating the surface of the resist pattern with deep ultraviolet rays so as not to change. By imparting heat resistance to the resist pattern in this way, even if a thin film metal is vapor-deposited using this as a mask, the resist pattern will not be deformed by the heat during vapor deposition, so even if the resist pattern is removed by the lift-off method. An extremely good thin film metal pattern can be obtained without generation of burrs or the like. The specific constitution of the present invention is, after forming a predetermined resist on a semiconductor substrate, performing a desired pattern exposure and an organic solvent treatment to form a hardly soluble layer on the surface layer of the resist, and a resist pattern. At least a step of developing a cross-sectional shape into a stencil shape in which the opening of the substrate surface is wider than the opening of the resist surface layer, and a step of irradiating the stencil-shaped resist pattern with deep ultraviolet rays to provide heat resistance. It is a method of forming a resist pattern including. Furthermore, the present invention uses Au, Pt, Ni, Zn as a mask with the stencil-shaped resist pattern produced by the above method.
Is a method for forming a thin film metal pattern, which includes at least a step of depositing a thin film metal such as the above and then removing the resist pattern to form a thin film metal pattern on a semiconductor substrate.

[0005]

[Function] Since the surface layer of the stencil-shaped resist pattern is hardened and has heat resistance, the stencil-shaped resist pattern is not deformed even when the temperature rises when the thin film metal is vapor-deposited. Even if the resist pattern is removed by the lift-off method, a good thin film metal pattern without burrs can be formed on the semiconductor substrate.

[0006]

EXAMPLES Examples of the case where an organic solvent treatment is carried out after pattern exposure in the present invention will be described below in more detail with reference to the drawings. FIG. 1 is an explanatory diagram showing a method for forming a resist pattern in this embodiment. In the figure, a positive resist (for example, S1400 series manufactured by Shipley) 2 is formed on a semiconductor substrate 1 at a pre-baking temperature of 70 ° C., and pattern exposure is performed by using a reduction projection exposure apparatus (for example, NSR series manufactured by Nikon), and a bromine exposure It shows the shape of the resist pattern when irradiated with deep ultraviolet rays 6 having a wavelength of about 200 nm or less (1 to 5 minutes) after organic solvent treatment with benzene (10 minutes) and development treatment (3 minutes). Good overhangs 3 eaves are formed. It should be noted that almost no deformation of the resist pattern shape due to irradiation with the deep ultraviolet rays 6 was observed. Figure 2
The shape of the resist pattern when a gold (Au) film having a film thickness of 1.5 μm is deposited as the thin film metal 4 is shown. There is no phenomenon that the resist pattern is deformed by vapor deposition of a thin film metal as in the prior art, and even if the lift-off process is performed, the thin film metal 4 having an extremely good shape without the burr 5 is obtained as the semiconductor substrate 1.
Could be formed on.

[0007]

As described above in detail, according to the method for forming a resist pattern and a thin film metal pattern of the present invention, a hardly soluble layer of an organic solvent such as brombenzene is formed on the surface layer of the resist. With this, after obtaining a good stencil-shaped resist pattern, it is possible to improve the heat resistance of the resist pattern by irradiating deep ultraviolet rays, and even if the temperature rises due to the deposition of thin-film metal, the stencil-shaped resist pattern Since no deformation occurs, it is possible to obtain a good thin film metal pattern without burrs.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a method of forming a stencil-shaped resist pattern exemplified in an embodiment of the present invention.

FIG. 2 is an explanatory view showing a method for forming a thin film metal pattern using the stencil-shaped resist pattern exemplified in the embodiment of the present invention as a mask.

FIG. 3 is a schematic diagram showing a conventional stencil-shaped resist pattern.

FIG. 4 is a schematic view showing the deformation of a resist pattern when a thin film metal pattern is formed using a conventional stencil-shaped resist pattern as a mask.

[Explanation of symbols]

 1 Semiconductor Substrate 2 Resist 3 Overhang 4 Thin Film Metal 5 Burr 6 Far UV

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/027 21/3065

Claims (2)

[Claims] 1. A step of forming a hardly soluble layer on the surface layer of the resist by performing desired pattern exposure and organic solvent treatment after forming a resist on a semiconductor substrate, and a cross-sectional shape of the resist pattern, A step of developing into a stencil-shaped resist pattern in which the opening of the substrate surface is wider than the opening of the resist surface layer, and a step of irradiating the stencil-shaped resist pattern with deep ultraviolet rays to impart heat resistance, A method for forming a characteristic resist pattern. 2. A step of depositing a thin film metal using the stencil-shaped resist pattern produced by the method according to claim 1 as a mask, and then removing the resist pattern to form a thin film metal pattern on a semiconductor substrate. A method of forming a thin film metal pattern, comprising: