JPS6237779B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mask repair method, and particularly to a hard
Concerning how to correct pinholes in masks.

Many hard masks are used when manufacturing semiconductor integrated circuits, especially LSIs. These pinholes existing in the hard mask adversely affect the performance, reliability, or manufacturing yield of semiconductor integrated circuits. Therefore, the pinhole correction process is an extremely important process in the hard mask manufacturing process.

Next, a method conventionally used for pinhole correction will be explained using a chrome mask as an example.

That is, in the conventional method of repairing a hard mask such as chrome, as shown in FIG.
First, a positive resist layer 4 is applied and formed on the surface of the chrome mask having the chromium film 2, in which the pinhole 3 exists in the chromium film 2 deposited thereon. Next, the positive resist layer covering the predetermined area 5 including the pinhole 3 is exposed to light using a correction device or the like, and developed to form a pinhole correction window in the positive resist layer 4 as shown in FIG. 1b. form 6. Next, as shown in FIG. 1c, a chromium layer 7 for correction is coated on the mask surface by a method such as vapor deposition or sputtering, and then the chrome mask is coated with a resist made of sodium hydroxide (NaOH) or the like. The positive resist layer 4 is dissolved and removed by immersion in a stripping solution, and at the same time the correction chromium layer 7 on the positive resist layer 4 is peeled off (lift-off method), and the chrome is removed as shown in FIG. 1d. The pinholes have been repaired by forming a remaining repair chromium layer 7 on a predetermined region of the film 2 including the pinholes 3.

However, in the conventional method described above, when lifting off the chromium layer for repair, the resist stripper enters only from the end surface of the resist layer because the top surface of the positive resist layer is covered with the chrome layer for repair. The process requires a long time to dissolve the resist layer. In addition, the peeled off correction chromium layer is torn off to form a chromium layer in the form of small pieces, and especially for masks with fine patterns or high-density patterns, the chromium layer adhering to the exposure window of the mask may be removed during the cleaning process. This poses a problem in that the remaining chromium particles cannot be completely removed, leading to a decrease in the manufacturing yield of the mask, and additional man-hours are required for correction processing to remove the chromium fragment residues.

In view of the above-mentioned problems, the present invention provides a hard mask pin that allows corrections to be made with simple operations and in a short time, and that does not produce any residue of the correction light-shielding film that would deform the exposure window of the mask. Provide a hole correction method.

That is, the present invention provides a method for correcting pinholes in a hard mask, in which a photoresist layer is coated on a mask surface having a light-shielding film, and then the pinhole portions of the light-shielding film are exposed on the photoresist layer. A pinhole correction window is formed, then a dye film is coated on the entire surface of the mask, the dye film is oxidized and solidified, the photo resist layer is dissolved and removed, and at the same time the dye film on the photo resist layer is lifted. - It is characterized by having a step of turning off the light shielding film and forming a light shielding layer made of a dye film covering the pinhole in the pinhole portion of the light shielding film.

Hereinafter, one embodiment of the present invention for repairing pinholes in a chrome mask will be described in detail with reference to process cross-sectional views shown in FIGS. 2a to 2e.

That is, when using the method of the present invention to correct pinholes in a chrome mask in which pinholes 3 are present in the chromium film 2 deposited on the glass substrate 1 as shown in FIG. As shown in FIG. 3B, first, a positive resist layer 4 having a thickness of, for example, about 5000 to 6000 Å is formed on the surface of the chromium mask having the chromium film 2. Next, using a correction device or the like, the positive resist layer 4 is exposed to light at a position covering the pinhole 3 in a desired area including the pinhole 3, and developed to form a positive resist layer 4 as shown in FIG. 2c. - A pinhole correction window 6 is formed in the resist layer 4 to expose a predetermined region 5 including the pinhole 3 of the chromium film 2.

Next, as shown in FIG. 2d, a dye such as thio-indigo (C ₁₆ H ₈ O ₂ S ₂ )-based indigoid dye, which has a black or red color blocking effect against ultraviolet light, is applied to the mask surface. [%] of an organic solution such as alcohol is applied by a method such as dipping or spin coating to form a dye film 8 made of the above dye over the entire mask surface. And in this case pinhole 3
Inside is a chromium film 2 with a thickness of about 800 [Å].
The pigment with almost the same thickness as that of the other surfaces accumulates, and the pigment film 8 on the other surfaces becomes extremely thin, on the order of several tens of angstroms.

Next, the mask is dried in the air at a temperature of about 40 to 50 [°C] for about 3 to 5 [minutes] to evaporate the solvent in the pigment film 8, and then the mask is dried in the air for about 90 to 100 minutes.
It is heated at a temperature of about [°C] for about 5 to 10 [minutes] to oxidize the dye film 8 and develop a color peculiar to the dye, such as black or red. And in this case, the pigment film 8
The thickness of the pigment film 8 within the pinhole 3 is approximately 400 [Å] thick, and the thickness of the other areas is approximately 1/2 of the coating thickness. It becomes Satoshi. Note that in order to form a thicker dye film inside the pinhole, the concentration of the dye liquid to be applied may be further increased.

Next, the mask is immersed in a resist stripping solution made of sodium hydroxide or the like to dissolve and remove the positive resist layer 4, and at the same time lift off the dye film 8 on the positive resist layer 4, as shown in FIG. 2e. As shown, a light-shielding film made of a dye film 8 is formed on a desired region of the chromium film 2 including the pinhole 3 to cover the pinhole 3 to a thickness of about 400 Å.

The dye film 8 formed on the positive resist layer 4 in the lift-off process of the dye film 8
However, as mentioned above, since the film thickness is extremely thin, on the order of several tens of Å, the stripping solution penetrates through the dye film and dissolves the positive resist layer 4, resulting in a short time of about 5 to 10 minutes. Lift off is completed. Furthermore, since the dye film 8 on the positive resist layer 4 is extremely thin as described above, the peeled dye film 8 does not become a thin film but becomes extremely fine particles, and the residue of the dye particles forms the exposure window of the mask. There's nothing to force you to do.

In the above example, an indigoid dye was used as the pigment film for correcting pinholes, but the pigment film used in the method of the present invention is not limited to the above, and dyes that develop color in a light tone that blocks ultraviolet light may be used. Applicable.

As explained above, according to the present invention, the hardware
When repairing pinholes in a mask, the repair time can be shortened, and the residue of the repair film will not adhere to the exposure window of the mask and deform the exposure window, improving the manufacturing yield of hard masks and reducing the number of manufacturing steps. reduction can be achieved.

[Brief explanation of the drawing]

1A to 1D are cross-sectional views of a conventional mask repair method, and FIGS. 2A to 2E are cross-sectional views of a mask repair method according to the present invention. In the figure, 1 is a glass substrate, 2 is a chromium film, and 3 is a glass substrate.
is a pinhole, 4 is a positive resist layer, 5 is a predetermined area including the pinhole, 6 is a pinhole correction window,
7 represents a chromium layer for correction, and 8 represents a pigment film.

Claims (1)

[Claims] 1 In a method for correcting pinholes in a hard mask, a photoresist layer is coated on a mask surface having a light-shielding film, and then a pinhole is formed on the photoresist layer to expose the pinhole portion of the light-shielding film. A correction window is formed, then a dye film is coated on the entire surface of the mask, the dye film is oxidized and solidified, the photo resist layer is dissolved and removed, and at the same time the dye film on the photo resist layer is lifted.
1. A mask repair method comprising the steps of: turning off the light shielding film, and forming a light shielding layer made of a dye film covering the pinholes in the pinhole portions of the light shielding film.