JPS6228463B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a chrome mask repair method for repairing defects in a chrome mask in which a metal chromium film is deposited in a desired shape on the surface of a glass substrate. Semiconductors and integrated circuits are becoming smaller and more dense every year, and the quality required for photomasks has also become stricter. As a result, hard masks whose pattern material is chromium metal are becoming mainstream. In terms of photomask quality, defects greatly affect the manufacturing yield of devices, and of course a defect-free mask is desirable. However, the probability of obtaining a defect-free mask through normal mask manufacturing processes is extremely low, and masks often contain several defects. Therefore, in order to obtain a defect-free mask, it is necessary to correct these defects in some way. There are two types of defects in a chromium hard mask: "residual defects" in which black spots of chromium remain, and "missing defects" in which pinholes appear in the chromium film. Residual defects can be easily corrected by irradiating the defective area with laser light to evaporate residual chromium. The defect can be corrected by the following process called the chromium lift-off method. That is, (1) applying a positive photoresist to the entire surface of the mask, (2) irradiating the defective area with spot light, (3) developing treatment, (4) depositing metallic chromium by vapor deposition or sputtering, (5) ) Resist removal (chromium lift-off): In this method, defects are repaired using metallic chromium deposited on the glass in the defective area, but the defects may be removed due to poor adhesion between the glass surface after development and the deposited metallic chromium. There was a risk that the chromium deposited on the mask would peel off during mask cleaning and other operations.

The present invention has been made in view of these problems, and provides a method for enhancing the adhesion between the glass surface and the deposited metal chromium after development in the chromium lift-off method. . According to the present invention, a technique for repairing missing defects in a chrome mask using a lift-off method has been established, and a defect-free mask can be easily obtained.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an enlarged view of the main part of the chrome mask, in which a desired pattern is drawn on the surface of a glass substrate 1 by a metal chromium film 2. As shown in FIG. Note that 3 is a defect in which a part of the chromium film 2 is missing.

A positive resist 4 is applied to the entire surface of such a chrome mask.
Then, after irradiating ultraviolet rays only at the locations of the defects 3 of the chromium film 2 using a spot exposure device, a development process is performed to expose only the locations of the defects 3 from the resist 4 (FIG. 2).

Next, this mask is placed in an etching atmosphere 5 for a short time to lightly etch the exposed areas not covered by the resist 4 (FIG. 3).

Subsequently, metal chromium 6 is deposited on the entire surface of the mask by vapor deposition or sputtering (FIG. 4). At this time, chromium 6 is naturally deposited on the surface of the resist 4, but also on exposed areas.

Finally, by peeling off the resist 4, the chromium 6 on the resist 4 is lifted off, and the chromium 6 in other parts, that is, the exposed parts, remains, and this residual chromium 6 is used to remove the chromium 6 from the metal chromium 2. This means that the missing defect in the mask pattern has been repaired (Fig. 5).

A specific embodiment of the invention described above will now be described. As a positive resist 4 to be applied on a photomask having a metal chromium pattern,
AZ-1350 is used, and its thickness is 6000 Å and 90
Baking treatment is performed at ℃ for 25 minutes. The three defective areas were spot exposed, developed for 60 seconds, and then a photoetchant was sprayed in a shower for 5 seconds. After depositing metal chromium 6 to a thickness of 1000 Å by sputtering, the resist 4 was removed with acetone, and only the chromium 6 in the defect 3 remained. This chromium 6 did not peel off even when the mask was cleaned with acid.

As is clear from the above description, in the present invention, after the defects in the chromium film are exposed from the resist film,
Since the exposed area is lightly etched and then a chromium film is deposited, the adhesion of the deposited chromium film to the glass substrate is increased, and chromium loss defects can be reliably repaired.

[Brief explanation of the drawing]

1 to 5 are cross-sectional views showing the method of the present invention in the order of steps, where 1 shows a glass substrate, 2 shows a metal chromium film, 3 shows a defect, 4 shows a resist, and 6 shows a deposited resist, respectively. ing.

Claims (1)

[Claims] 1 A method for repairing defects in a chromium mask in which a chromium film is deposited in a desired shape on the surface of a glass substrate, in which only the defective parts of the chromium film are exposed from the photoresist film, and then the exposed parts are lightly etched. , followed by depositing chromium on the entire surface of the substrate, removing the photoresist film, and repairing defective parts of the chromium film with deposited chromium.