JPH0353523A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To avoid any etching residue thereby enabling the patterns in excellent shape to be formed by a method wherein an impurity hardly etched away existing on a polysilicon film or a polycide film is previously removed and then the said film is patterned by dryetching process. CONSTITUTION:Firstly, an impurity such as a spontaneous oxide film 5, etc., formed on a polysilicon film 2 deposited on the surface of this semiconductor substrate 1 is removed. That is, the impurity is removed using an etching such as 15:1 buffered fluoric acid, etc., for around 30sec. Next, resist patterns 3 are formed on the surface of the polysilicon film 2 by normal photolithographic process. The polysilicon layer 2 is patterned to form polisilicon patterns 4 in specific shape by anisotropic dryetching process using the resist patterns 3 as masks. Later, the residual resist patterns 3 on the surface of the polysilicon film 2 whereon the polysilicon patterns 4 are formed are removed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, and more specifically, a method for forming a pattern by dry etching a polysilicon film or a polycide film covering the surface of a semiconductor substrate. Regarding preprocessing when [Prior Art] Conventionally, when patterning a polysilicon film or a polycide film covering the surface of a semiconductor substrate by dry etching, the steps are shown in the cross-sectional structural diagrams of FIGS. 2(a) to 2(d). A method has been adopted. That is, the surface of the semiconductor substrate 1 is covered with a polysilicon layer (or polycide film) 2 deposited to a predetermined thickness, as shown in FIG. 2(a). Therefore, first, a normal photolithography process is performed to form a resist pattern 3 on the surface of the polysilicon III 2 as shown in FIG. 2(b).
After forming, the polysilicon film 2 is patterned by an anisotropic dry etching process, and a polysilicon pattern 4 having a shape as shown in FIG. 2(C) is formed on this polysilicon film 2. Thereafter, as shown in FIG. 2(d), the resist pattern 3 remaining on the surface of the polysilicon 11!2 on which the polysilicon pattern 4 was formed is removed. By the way, if it is necessary to implant and diffuse impurities into this polysilicon film 2, the required impurities are implanted and diffused before forming the resist pattern 3 by photolithography.

[Problem to be solved by the invention]

However, the above-described semiconductor device manufacturing method has the following disadvantages. That is, on the surface of the polysilicon film (or polycide film) 2 covering the semiconductor substrate Fi1, there is a natural oxide film (indicated by reference numeral 5 in FIG. 2(a)), which is a substance that is difficult to etch, and foreign substances such as dust. If it exists, etching residue (indicated by reference numeral 6 in FIG. 2(d)) consisting of foreign matter is likely to be generated inside the polysilicon pattern 4 shaped by the dry etching process, which is a problem. Therefore, it becomes impossible to obtain a pattern having a specific shape. Furthermore, when impurities are implanted and diffused into the polysilicon film 2, substances that are difficult to be etched are likely to be generated on the surface of the polysilicon film 2, resulting in a large amount of etching residue 6 being generated. The present invention was devised in view of such disadvantages, and an object of the present invention is to provide a method for manufacturing a semiconductor device that can prevent the generation of etching residue and obtain a pattern with a good shape. It is said that [Means for Solving the Problems] In order to achieve the above object, the method for manufacturing a semiconductor device according to the present invention includes patterning a polysilicon film or a polycide film covering the surface of a semiconductor substrate by dry etching treatment. In this process, foreign matter including a native oxide film formed on the polysilicon film or polycide film is removed immediately before the dry etching process or the photolithography process that precedes the dry etching process.

[Effect]

According to the above method, patterning is performed by dry etching after removing foreign substances including the native oxide film, which is a material that is difficult to etch, existing on the polysilicon film or polycide film. Etching residue consisting of foreign matter will no longer be generated inside the pattern of the etched polysilicon film or polycide film. [Example] An example of the method of this invention will be described below based on the drawings. FIGS. 1(a) to 1(e) are cross-sectional structural views showing the steps of a method for manufacturing a semiconductor device according to the present invention. In addition, in these FIGS. 1(a) to (e), parts that are the same as or correspond to those in FIGS. 2(a) to (d) showing the conventional method described above are given the same reference numerals. As shown in FIG. 1(a), the surface of a semiconductor substrate l used in this method is covered with a polysilicon film (or polycide film) 2 deposited to a predetermined thickness of 3000 Å. On the surface of this polysilicon film 2, a thin natural oxide film 5, which is a substance that is difficult to etch, is formed, and foreign matter such as dust is present. First, as shown in FIG. 1(b), foreign matter such as the native oxide film 5 existing on the polysilicon film 2 deposited on the surface of the semiconductor substrate 1 is removed. In addition, this foreign matter removal is performed using l5:1 bath fed #1 (BHF).
The etching process is performed for about 30 seconds using an etching solution such as .

Next, a resist pattern 3 as shown in FIG. 1(c) is formed on the surface of the polysilicon film 2 by performing a normal photolithography process. Thereafter, by performing an anisotropic dry etching process using this resist vacuum 3 as a mask, polysilicon II! A polysilicon pattern 4 having a predetermined shape as shown in FIG. 1(d) is formed on this polysilicon film 2. Thereafter, as shown in FIG. 1(e), the resist pattern 3 remaining on the surface of the polysilicon M2 on which the polysilicon pattern 4 is formed is removed.

Note that when it is necessary to implant and diffuse impurities into the polysilicon film 2 covering the surface of the semiconductor substrate 1, it is necessary to first check the presence of foreign substances such as the native oxide film 5 and m-debris on the surface of the polysilicon film 2. After necessary impurities are implanted and diffused in the state shown in FIG. 1(a), these foreign substances are removed.

By the way, in the above explanation, it is assumed that foreign substances including the natural oxide film 5 are removed immediately before performing photolithography processing, that is, immediately before forming the resist pattern 3.
Needless to say, the removal of this foreign material may be performed immediately before the dry ethoching process, and the same result will be obtained.

〔Effect of the invention〕

As explained above, according to the method for manufacturing a semiconductor device according to the present invention, foreign matter including a natural oxide film, which is a substance that is difficult to be etched, existing on a polysilicon film or a polycide film is removed in advance, and then the polysilicon film is removed. Alternatively, since patterning is performed by dry etching of a polycide film, etching residues made of foreign matter are not generated inside the formed pattern, and a pattern with a good shape can be obtained. As a result, semiconductor devices with high yield and excellent reliability can be manufactured.

[Brief explanation of drawings]

1(a) to 1(e) are cross-sectional structural views showing a method of manufacturing a semiconductor device according to the present invention, and FIGS. 2(a) to 2(d) show a method of manufacturing a semiconductor device according to a conventional example. FIG. In the figure, numeral 1 is a semiconductor substrate, 2 is a polysilicon Il
l (polycide film), 4 is polysilicon pattern, 5
is a natural oxide film (foreign substance). Note that the same reference numerals in the figures indicate parts or parts that are the same or correspond to each other.

Claims (1)

[Claims] (1) When patterning a polysilicon film or a polycide film covering the surface of a semiconductor substrate by dry etching processing, immediately before the dry etching processing or the preceding photolithography processing, a pattern formed on the polysilicon film or polycide film is A method for manufacturing a semiconductor device, characterized in that foreign matter including a native oxide film is removed.