JPS6327850B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a semiconductor device in which adhesion between a photoresist and a substrate is arbitrarily controlled in a photoetching process.

In manufacturing semiconductor devices, the degree of adhesion between the photoresist and the surface of the semiconductor substrate is one of the important factors in the photoetching process. It is known that the degree of adhesion between the two is influenced by the hydrophilicity of the substrate surface. Conventional methods for chemically controlling the degree of hydrophilicity of a substrate surface generally utilize a dehydration condensation reaction using a silanol-based or alcohol-based organic compound. In methods that utilize this dehydration condensation reaction, it is possible to change the degree of hydrophilicity by selecting the type of organic compound, but it has not yet been possible to control the degree arbitrarily and easily with good reproducibility. is the actual situation. For this reason, the conventional method has had the disadvantage that the taper angle of the opening in the substrate after photoetching cannot be arbitrarily and uniformly controlled.

This invention was made in consideration of the above circumstances, and its purpose is to enable the degree of hydrophilicity on the surface of a semiconductor substrate to be controlled arbitrarily, easily, and with good reproducibility, so that the degree of hydrophilicity can be controlled easily and reproducibly after photoetching. An object of the present invention is to provide a method for manufacturing a semiconductor device that can control the taper angle of an opening in a substrate arbitrarily and uniformly.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1a, the method for manufacturing a semiconductor device of the present invention involves first forming a SiO ₂ film 2 on the surface of a semiconductor substrate 1 by a method such as thermal oxidation, and then forming the SiO 2 film 2 on the surface of the semiconductor substrate 1 on which the SiO ₂ film 2 has been formed. The substrate 1 is boiled in, for example, a mixture of H ₂ SO ₄ and H ₂ O ₂ or an alkaline solution. As a result, the substrate 1
Impurities such as heavy metal molecules or Na molecules adhering to the surface of the SiO ₂ film 2 are removed, and the hydrophilicity of the surface of the SiO ₂ film 2 becomes extremely large.

Next, a treatment solution is prepared by dissolving a certain amount of hexamethylene disilazane as an organic silane compound, for example, in one of xylene, butyl acetate, trichlene, or methanol as an organic solvent, and the substrate 1 is placed in a predetermined manner in this treatment solution. Soak for an hour.

Figure 2 shows that a treatment solution is prepared by dissolving a predetermined amount of the above hexamethylene disilazane as an organic silane compound in 1 c.c. each of xylene, butyl acetate, trichlene, and methanol as organic solvents.
It shows the change characteristics of the surface contact angle θ when a semiconductor substrate is immersed in this treatment solution, and the four curves A, B, C, and D are for methanol, trichlene, butyl acetate, and xylene as organic solvents, respectively. This is when it is used. Note that the surface contact angle θ here refers to the angle formed by the circumferential surface of the water droplet with respect to the substrate surface when a water droplet is dropped onto the substrate surface and becomes round due to surface tension. represents the degree of hydrophilicity in Therefore, if the surface contact angle θ is a small value, the degree of hydrophilicity is high, and conversely, if the surface contact angle θ is a large value, the degree of water blocking property is high. As is clear from FIG. 2, by arbitrarily selecting or setting the type of organic solvent and the amounts of the organic solvent and organic silane compound, the surface contact angle θ on the surface of the SiO ₂ film 2 of the substrate 1 can be kept constant. can be the value of That is, by immersing the substrate 1 in the above treatment solution, an adsorption reaction of hexamethylene disilazane occurs on the surface of the SiO ₂ film 2, which has been made more hydrophilic in the above step, and the hydrophilicity of the surface of this SiO ₂ film is increased. The degree of this decreases gradually. The degree of hydrophilicity is determined only by the type of organic solvent and the amounts of the organic solvent and organic silane compound.
That is, the surface contact angle θ saturates at a certain value after a predetermined processing time has elapsed.

After the above steps are completed, a photoresist is applied on the SiO ₂ film 2 to form a photoresist film 3, as shown in FIG. 1b. Next, the substrate 1 is subjected to a series of photoetching processes including exposure and wet etching through a photomask to form openings 4 in the SiO ₂ film 2 as shown in FIG. 1c. At this time, there is a difference between the taper angle γ of the opening 4 formed in the SiO ₂ film 2 and the surface contact angle θ when hexamethylene disilazane is used as the organic silane compound and butyl acetate is used as the organic solvent. A correlation as shown in FIG. 3 holds true. Therefore, this figure 3 and 2
From the figure, when using hexamethylene disilazane as the organic silane compound and butyl acetate as the organic solvent, for example, in order to make the taper angle γ of the openings 4 formed in the SiO ₂ film 2 uniform by 40 degrees, It is sufficient to set the surface contact angle θ to about 37 degrees, and to further increase θ to 37 degrees, add hexamethylene disilazane to 1 c.c. of butyl acetate in the amount at point A in Figure 2, that is, 2 × 10 ^-2 The adsorption reaction treatment may be performed using a treatment solution containing cc dissolved therein. Similarly, when using other organic solvents,
It becomes possible to form a constant taper angle γ in the opening 4.

Note that this invention is not limited to the above embodiments, and the types of the organic silane compound and the organic solvent are not limited. In short, a treatment solution in which an organic silane compound is dissolved in a predetermined organic solvent at a certain ratio is used. Just do it.

As described above, according to the present invention, it is possible to provide a method of manufacturing a semiconductor device in which the taper angle of the opening in the substrate after photo-etching can be arbitrarily and uniformly controlled.

[Brief explanation of the drawing]

FIGS. 1A to 1C are cross-sectional views showing each step of a method according to an embodiment of the present invention, and FIGS. 2 and 3 are characteristic curve diagrams for explaining the method of this invention, respectively. DESCRIPTION OF SYMBOLS 1...Semiconductor substrate, 2... _SiO2 film, 3...Photoresist film, 4...Opening part.

Claims (1)

[Claims] 1. A step of treating the surface of a semiconductor substrate to increase its hydrophilicity; and immersing the substrate in a treatment solution prepared by dissolving an organic silane compound in a predetermined proportion in a predetermined organic solvent. A step of optionally reducing the degree of hydrophilicity of the substrate surface by adsorbing an organic silane compound onto the substrate surface, and selectively forming a resist layer for etching on the substrate, and then using this resist layer as a mask. 1. A method for manufacturing a semiconductor device, comprising the step of: etching a substrate using an etching method.