JPH1064841A - Method for manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device of high reliability by eliminating occurring of residue when a resist is removed. SOLUTION: A base-material oxide film 21 is formed on a substrate 20, and as a resist acting as a mask for ion implantation, 2-layer structure of a negative resist 22 and a positive resist 23 is formed over it, then, high-dose ion implantation 24 is performed. Then the positive resist 23 is removed by ashing. Then, the negative resist 22 is removed by such wet method as sulfuric acid hydrolysis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device in which high dose ion implantation is performed using a positive resist as a mask.

[0002]

2. Description of the Related Art Conventionally, techniques in such a field include:
There were the following. FIG. 2 is a sectional view showing a manufacturing process of such a conventional semiconductor device. (1) First, as shown in FIG. 2A, a well 2 is formed on a substrate 1, and a field oxide film 3 for element isolation is formed. Thereafter, a gate insulating film 4 is formed, a gate electrode 5 is formed, and a first low concentration impurity 6 is implanted. Next, a sidewall 8 is formed using a CVD oxide film. 7 is a second low concentration impurity.

(2) Next, as shown in FIG. 2 (b), an oxide film 9 serving as a surface protection film for ion implantation is generated, a resist pattern 10 is formed by photolithography, and impurities are increased using the resist pattern 10 as a mask. Dose ion implantation is performed to form a first high-concentration impurity layer. (3) Next, as shown in FIG. 2C, similarly, ions of the opposite conductivity type are ion-implanted to form a second high-concentration impurity layer.

[0004]

However, in the above-mentioned conventional method for manufacturing a semiconductor device, FIG.
As shown in FIG. 1, for example, a high dose ion implantation 18 is performed using a resist 17 formed on an oxide film 16 on a substrate 15 as a mask.
Is performed, as shown in FIG.
The ion-implanted region on the surface is altered. Resist 17
In the case of removing by the usual ashing, there is a problem that the residue (main component is an oxide) 19 remains without being completely removed as shown in FIG. 3C.

[0005] In particular, when the pattern becomes fine and a positive resist is used, there is a problem that a very large amount of residue is generated. This residue causes a pattern defect or the like in a subsequent manufacturing process, and has a problem of causing a defect of the semiconductor device. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for manufacturing a highly reliable semiconductor device, which eliminates the above problems and eliminates the generation of residues when removing a resist.

[0006]

According to the present invention, there is provided a method for manufacturing a semiconductor device in which high dose ion implantation is performed using a positive resist as a mask. Forming a two-layer resist having a positive resist formed on the negative resist;
A step of performing high dose ion implantation using the two-layer resist as a mask, a step of removing the positive resist, and a step of removing the negative resist are performed.

As described above, by forming a negative resist with less residue under the positive resist where the residue remains, the residue at the time of removing the positive resist can be removed by the lift-off effect at the time of removing the negative resist. No residue remains on the surface of the underlying oxide film. Therefore, a factor of a defect in a later manufacturing process can be removed, so that the yield of the semiconductor device can be improved.

(2) In a method of manufacturing a semiconductor device in which high dose ion implantation is performed using a positive resist as a mask, a step of forming an insulating film having an etching selectivity with respect to the underlying oxide film on the underlying oxide film; A step of forming a resist, a step of performing high dose ion implantation using the positive resist as a mask, a step of removing the positive resist, and a step of removing the insulating film are performed.

Therefore, after removing the positive resist,
Since the generated residue can be removed at the same time by removing the film on the surface, no residue remains. Thus, the yield of the semiconductor device can be improved. In addition, since the surface film covers the entire surface of the base, contaminants attached to or implanted on the surface of the ion-implanted region can be removed.

(3) In a method of manufacturing a semiconductor device in which high dose ion implantation is performed using a positive resist as a mask, a step of forming a base oxide film thicker than a predetermined thickness, and forming a positive resist on the thick base oxide film Forming,
A step of performing high dose ion implantation using the positive resist as a mask, a step of removing the positive resist, and a step of etching the surface of the thick base oxide film are performed.

Therefore, after removing the positive resist,
Since the generated residue is simultaneously removed by etching the surface of the base oxide film, no residue remains. In addition, since the residue itself is an oxide, the removal effect can be improved by removing the residue with an oxide film etchant.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a manufacturing process of a semiconductor device according to a first embodiment of the present invention. (1) First, as shown in FIG. 1A, a base oxide film 21 is formed on a substrate 20, and a two-layer structure of a negative resist 22 and a positive resist 23 is formed thereon as a resist serving as a mask for ion implantation. Formed.

(2) Thereafter, as shown in FIG.
High dose ion implantation 24 is performed. (3) Next, as shown in FIG.
3 is removed by ashing. (4) Next, as shown in FIG.
2 is removed by a wet method such as sulfuric acid-hydrogen peroxide.

With this configuration, the negative resist 22 with less residue is formed under the positive resist 23 where the residue remains, so that the residue when removing the positive resist is removed by a lift-off effect when removing the negative resist. Therefore, no residue can be left on the surface of the underlying oxide film. Next, a second embodiment of the present invention will be described.

FIG. 4 is a sectional view showing a semiconductor device manufacturing process according to a second embodiment of the present invention. (1) First, as shown in FIG. 4A, a film 32 having an etching selectivity with respect to an oxide film, for example, a nitride film or the like is formed on the underlying oxide film 31 on the substrate 30 by about several tens of kilometers. ,
A positive resist 33 is formed. (2) Thereafter, as shown in FIG. 4B, high dose ion implantation 34 is performed.

(3) Next, as shown in FIG. 4C, the positive resist 33 is removed by ashing. (4) Next, as shown in FIG. 4D, the film 32 is removed by a wet method such as phosphoric acid. With this configuration, after removing the positive resist 33, the generated residue can be removed at the same time by removing the film 32 on the surface, so that no residue can be left.

Further, since the surface film 32 covers the entire surface of the base, contaminants adhered to or implanted on the surface of the ion-implanted region can be removed. Here, the contaminant refers to particles at the time of ion implantation or metal contamination (Al, Fe, etc.) introduced by ion beam sputtering. Next, a third embodiment of the present invention will be described.

FIG. 5 is a sectional view showing a manufacturing process of a semiconductor device according to a third embodiment of the present invention. (1) First, as shown in FIG. 5A, when forming an oxide film on the surface of the substrate 40, a base oxide film 41 having a thickness of about several tens of mm is generated in advance, and then a positive resist 42 is formed. To form (2) Next, as shown in FIG. 5B, high dose ion implantation 43 is performed.

(3) Next, as shown in FIG. 5C, the positive resist 42 is removed by ashing. (4) Next, using an etching solution that etches an oxide film such as diluted hydrofluoric acid for several tens of millimeters, a thick base oxide film 4 is formed.
One surface is etched to form a base oxide film 44 having a predetermined thickness as shown in FIG.

With this configuration, the positive resist 4
After removing 2, the generated residue is simultaneously removed by etching the surface of the underlying oxide film 41,
No residue remains. In addition, since the residue itself is an oxide, the removal effect can be improved by removing the residue with an oxide film etchant. It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made based on the gist of the present invention, and these are not excluded from the scope of the present invention.

[0021]

As described above, according to the present invention, the following effects can be obtained. (1) According to the first aspect of the invention, by forming a negative resist in which a residue is less likely to remain under a positive resist in which a residue remains, the residue at the time of removing the positive resist is lifted off when the negative resist is removed. Therefore, there is an effect that no residue remains on the surface of the underlying oxide film.

As a result, the factor of the defect in the later manufacturing process can be removed, and the yield of the semiconductor device can be improved. (2) According to the second aspect of the invention, after removing the positive resist, the generated residue can be removed at the same time by removing the film on the surface, so that there is an effect that no residue remains.

Thus, the yield of the semiconductor device can be improved. Also, since the surface film covers the entire surface of the base, it adheres to the surface of the ion-implanted region or
The effect of removing the injected contaminants can also be expected. Here, the contaminant refers to particles at the time of ion implantation or metal contamination (Al, Fe, etc.) introduced by ion beam sputtering.

(3) According to the third aspect of the invention, after the positive resist is removed, the generated residue is simultaneously removed by etching the surface of the underlying oxide film, so that no residue remains. Is obtained. In addition, since the residue itself is an oxide, the removal effect can be improved by removing the residue with an oxide film etchant.
Thus, improvement in the yield of the semiconductor device can be expected.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a manufacturing process of a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a manufacturing process of a conventional semiconductor device.

FIG. 3 is a cross-sectional view of a manufacturing process of a semiconductor device showing a problem of the related art.

FIG. 4 is a cross-sectional view illustrating a manufacturing process of a semiconductor device according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a manufacturing process of a semiconductor device according to a third embodiment of the present invention.

[Explanation of symbols]

 20, 30, 40 Substrate 21, 31 Underlying oxide film 22 Negative resist 23, 33, 42 Positive resist 24, 34, 43 High dose ion implantation 32 Film having an etching selectivity with oxide film 41 Thick underlying oxide film 44 Predetermined Thick underlying oxide film

Claims (3)

[Claims] 1. A method of manufacturing a semiconductor device in which high dose ion implantation is performed using a positive resist as a mask, comprising:
A step of forming a negative resist on the underlying oxide film and forming a positive resist on the negative resist to form a two-layer resist; and (b) performing high dose ion implantation using the two-layer resist as a mask. A method of manufacturing a semiconductor device, comprising: a step of (c) removing the positive resist; and (d) a step of removing the negative resist. 2. A method of manufacturing a semiconductor device in which high dose ion implantation is performed using a positive resist as a mask, comprising:
Forming an insulating film having an etching selectivity with the base oxide film on the base oxide film; (b) forming a positive resist; and (c) performing high dose ion implantation using the positive resist as a mask. A method of manufacturing a semiconductor device, comprising: (d) removing the positive resist; and (e) removing the insulating film. 3. A method of manufacturing a semiconductor device in which high dose ion implantation is performed using a positive resist as a mask, wherein (a)
Forming a base oxide film thicker than a predetermined thickness;
(B) a step of forming a positive resist on the thick underlying oxide film, (c) a step of performing high dose ion implantation using the positive resist as a mask, and (d) a step of removing the positive resist. e) etching the surface of the thick underlying oxide film.