JPH1027745A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the surface of a wafer in adhesion to a photoresist film by a method wherein the wafer is subjected to a hydrofluoric acid treatment to remove a contaminant layer from its surface before it is subjected to a hexamethyldisilazane treatment. SOLUTION: A semiconductor wafer coated with a natural oxide film or a NH4 OH film is subjected to a hydrofluoric acid cleaning treatment. In this cleaning process, the semiconductor wafers are arranged in a carrier with spaces between them and subjected to hydrofluoric acid cleaning through a spin-coating method or a vapor method. In succession, the semiconductor wafer is subjected to a hexamethyldisilazane(HMDS) treatment, photoresist is applied through a spin coating method onto the semiconductor wafer where an HMDS layer is formed, and the wafer is baked to form a photoresist film. By this setup, the HMDS film is enhanced in adhesion to the photoresist film, whereby a pattern can be ensured of its good shape and a line width as prescribed.

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 photoresist coating method for forming a photoresist film by a spin coating method after performing a hexamethyldisilazane treatment on a semiconductor wafer surface.

[0002]

2. Description of the Related Art The progress of semiconductor devices is remarkable, and high integration and miniaturization are progressing. Accordingly, there is a demand for a technique capable of forming a pattern with high precision in a photomechanical process in a semiconductor device manufacturing process. As one of the techniques for forming such a pattern with high precision, there is a technique in which a substrate surface is subjected to a hydrophobic treatment as a pretreatment of a photoresist coating step on a semiconductor wafer. In this method, hexamethyldisilazane (hereinafter referred to as HMDS) is adhered to react with hydroxyl (OH) groups on the wafer to make the surface hydrophobic, thereby improving the adhesion of the photoresist to the wafer. It is to improve.

[0003] A vapor method is generally employed as a method for attaching the HMDS. Hereinafter, the conventional HMD
The S processing step will be described. In FIG. 2, reference numeral 1 denotes a semiconductor wafer made of, for example, a silicon substrate, which is mounted by suction on a suction table 4 having a built-in heater 3 in a processing chamber 2. A nitrogen (N2) gas whose flow rate has been adjusted by a valve 5 is supplied from a supply source (not shown) into the processing chamber 2 to the container 6 and flows into the HMDS 7 stored in the container 6 to generate bubbles, and this publishing is performed. Is generated, the vapor of HMDS 7 mixed with the nitrogen gas from the container 6 is introduced from the nozzle 9 through the pipe 8.

The HM introduced from the nozzle 9
DS7 vapor is sprayed on the substrate 1 and H
An MDS layer is formed. H formed on the wafer surface
The MDS layer improves the adhesion to the photoresist applied in a later step. The semiconductor wafer 1 after the above-described HMDS processing step is carried out of the processing chamber 2 and sent to the next resist coating processing step, where a photoresist film is coated on the substrate by a spin coating method and baked. A step of applying a photoresist to the semiconductor wafer 1 has been performed.

[0005]

However, in response to recent demands for miniaturization, a problem has arisen that the above-described technology alone cannot cope with the problem. That is, if the adhesion with the further photoresist film is not achieved, the pattern shape is poor,
In particular, there is a problem that occurrence of a line width defect cannot be prevented.

In particular, in the case where a SiN film (silicon nitride film) is formed on a semiconductor wafer, NH3 which is a reaction gas remains on the wafer surface to form an NH4 OH layer. Also in other steps, the surface may become a contaminated layer (for example, an NH4 OH layer or H
A contaminated layer comprising a hydroxyl group such as 2 O) is formed. At the time of exposure processing, for example, NH3
Forms a thin film on the wafer surface that has reacted with the photoresist film. Further, on the surface where the hydroxyl (OH) group remains, the adhesion to the photoresist film, which is an organic substance, is reduced, and particularly, in the case of a long and thin pattern, it tends to be peeled off, thus causing a defect such as a pattern shift.

Accordingly, it is an object of the present invention to improve the adhesion of a semiconductor wafer surface to a photoresist film by performing a hydrofluoric acid treatment on the surface of the semiconductor wafer before the HMDS processing step.

[0008]

SUMMARY OF THE INVENTION Accordingly, the present invention relates to a method of manufacturing a semiconductor device in which a photoresist film is formed by spin coating after subjecting a semiconductor wafer surface to hexamethyldisilazane treatment. Before performing the above, the surface of the wafer is treated with hydrofluoric acid to remove a contaminant layer mainly composed of at least hydroxyl groups on the surface of the wafer.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a method for manufacturing a semiconductor device according to the present invention will be described below. One embodiment of the present invention will be described based on a flowchart of a manufacturing process of a semiconductor device shown in FIG. First, a hydrofluoric acid (HF) cleaning process is performed in step 1 on a semiconductor wafer whose surface is coated with, for example, natural oxidation or an NH4 OH film on Si.

In this cleaning step, cleaning with hydrofluoric acid is performed in a state where a plurality of semiconductor wafers are arranged in a carrier (not shown) with a gap therebetween (the cleaning with hydrofluoric acid may be performed, for example, by a spin coating method using hydrofluoric acid solution or vapor). Is performed in the same manner). The composition of the hydrofluoric acid cleaning liquid is, for example, 0.1 to 10% by weight, and the cleaning is performed at a liquid temperature of 25 ° C. for 5 seconds to 1 minute. By performing the cleaning with hydrofluoric acid, the oxide film and the NH4 OH film generated in the previous process can be removed. .

Subsequently, in step 2, HMDS processing is performed. This step is the same as that of the prior art. To be brief, the valve 5 is held in a state where the semiconductor wafer 1 is mounted on the suction table 4 in the processing chamber 2 by suction as shown in FIG.
Is opened, nitrogen (N2) gas is supplied to the container 6 through the pipe 8, and flows into the HMDS 7 accommodated in the container 6, and bubbles are generated. The HMDS 7 vapor mixed with the HMDS 7 is introduced from the nozzle 9 through the pipe 8.

The HM introduced from the nozzle 9
The vapor of DS7 is sprayed on the substrate 1 and HM
A DS layer is formed. HMD formed on this substrate surface
The S layer plays a role of improving the adhesion to a photoresist applied in a later step. Further, in step 3, a photoresist coating process is performed.

That is, a photoresist is applied to the semiconductor wafer on which the HMDS layer is formed as described above by a spin coating method and baked to form a photoresist film on the semiconductor wafer. As described above, in the present invention, the surface of the semiconductor wafer is treated with hydrofluoric acid before the HMDS treatment step to remove the contaminant layer on the wafer surface, thereby further improving the adhesion between the HMDS film and the photoresist film as compared with the related art. And the occurrence of pattern shape defects, particularly line width defects, can be prevented.

In this embodiment, an oxide film is formed on a semiconductor wafer. However, the present invention is not limited to this. For example, a SiN film (silicon nitride film), a polysilicon film, a WSix film (tungsten silicide) may be used. Membrane), B
The same applies to those in which HMDS processing is performed before the formation of a photoresist film after the formation of a PSG film or the like. Particularly, in the case of forming a SiN film, NH3 which is a reactive gas is deposited on the wafer surface. Remaining, NH4 OH
During the exposure process, a thin film is formed on the wafer surface where, for example, NH3, which is a component of the contaminated layer, has reacted with the photoresist film during the exposure process, and an organic substance is present on the surface where hydroxyl (OH) groups remain. In this case, the adhesion to the photoresist film is reduced, and particularly in the case of a long and thin pattern, it is easy to peel off.

[0015]

As described above, according to the present invention, the surface of the semiconductor substrate is treated with hydrofluoric acid before the HMDS treatment step to remove the contaminant layer on the substrate surface, thereby improving the adhesion to the photoresist film.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a manufacturing process of a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a view showing a schematic cross-sectional structure of a conventional photoresist coating apparatus.

Claims (2)

[Claims] In a method of manufacturing a semiconductor device in which a photoresist film is formed by a spin coating method after performing a hexamethyldisilazane treatment on a semiconductor wafer surface, the wafer surface is fluorinated before the hexamethyldisilazane treatment is performed. A method of manufacturing a semiconductor device, comprising removing a contaminant layer on a wafer surface by performing an acid treatment. 2. The method according to claim 1, wherein the contaminant layer is made of a substance having at least a hydroxyl group as a main component.