JP2803259B2 - Repair method of mask pattern defect - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for correcting a pattern defect on a photomask or an X-ray mask which is an original of a circuit pattern of a semiconductor integrated circuit.

[Conventional technology]

In the process of manufacturing a semiconductor integrated circuit, if there is a pattern defect on the photomask which is the original of the circuit pattern, the common pattern defect is transferred to all the transferred wafers, so the pattern defect of the photomask must be completely corrected. Must.

A conventional method for correcting a chipped defect such as a pinhole or a chipped edge will be described with reference to FIGS. 2 and 4. FIG. FIG. 2 is a schematic view of a mask having a pattern defect, and FIG. 4 is a schematic view of a mask corrected by a conventional method. FIG. 2A is a plan view of the mask, and FIG. Shows cross-sectional views taken along the line AB in FIG.

In FIG. 2, the structure of the mask is generally 0.
A mask pattern 2 made of a metal film such as chromium or molybdenum silicide having a thickness of about 1000 ° is formed on the surface of a transparent mask substrate 1 made of 09-inch quartz glass or the like. However, reference numeral 3 is an example of a pattern defect defect of the mask pattern 2.

Meanwhile, when correcting the pattern chipping defect shown in FIG. 2, while supplying an organic metal gas such as hexacarbonyl chromium (Cr (CO) ₆ ) near the pattern defect 3 on the mask surface, a laser beam such as a YAG laser is used. Is irradiated on the pattern defect 3, the organometallic gas is decomposed, and the metal film is deposited on the laser beam irradiation location. The principle is that laser light is absorbed by a substrate to become thermal energy, and the organic metal gas adsorbed on the substrate surface is decomposed, and is called laser CVD. In this way, the deposition film 4 is formed on the pattern defect 3 as shown in FIG. 4, and the defect is corrected. At this time, when the deposition film 4 is a metal,
It can be put to practical use in about 1000Å.

[Problems to be solved by the invention]

However, such a conventional defect repair method has the following problems. This will be described with reference to FIG.
When the repaired mask is washed with high-pressure pure water, a scrubber, or the like, as shown in FIG. 5, peeling 5 may occur as a defect in the deposition film 4 of the repaired portion. This is because, when the deposition film 4 is formed, if the substrate 1 is made of a transparent substance such as glass, the absorption of laser light is small, so that the metal film is not easily deposited directly on the glass substrate, and the metal film is defective. 3 is grown from the mask pattern 2 in the vicinity. That is, the portion of the deposition film 4 for defect correction on the mask pattern 2 is adhered to the substrate, but the portion of the defect 3 has a weak adhesive force with the substrate (glass), and thus is easily peeled off during cleaning. This is particularly remarkable for a large pinhole having a defect size of 10 μm ² or more, or a pattern defect at a pattern edge portion.

As described above, according to the conventional method, there is a problem that the repaired portion of the pattern defect is easily peeled off by cleaning.

[Means for solving the problem]

In order to solve the problems of the prior art as described above, the present invention forms an intermediate layer that absorbs laser light over the entire exposed surface of the mask pattern when correcting a pattern defect present in the mask pattern. Then, after correcting the pattern chipping defect by deposition by laser CVD, the intermediate layer other than the repaired portion is removed using the deposition film as a mask, and the repaired portion is bonded to the intermediate layer and the intermediate layer. The above-mentioned deposition film is left.

[Action]

In the present invention, by providing an intermediate layer that absorbs laser light on the entire surface of the mask, the energy of laser light is absorbed even on a glass substrate, and a deposition film having high adhesion can be formed. The film of the correction part does not peel off.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a process sectional view showing an embodiment of a mask defect repairing method according to the present invention, FIG. 2 is an example of a pattern chipping defect, and FIG. 3 is a defect repairing method according to this embodiment. Are shown after the masking. In these figures, the same or corresponding parts are denoted by the same reference numerals, and 6 is an intermediate layer such as a metal film formed before performing pattern correction, and this intermediate layer 6 is for absorbing laser light. .

Next, for convenience of explanation, the method of the above-described embodiment will be described by taking, as an example, the correction of the pattern defect defect shown in FIG. 2 as in the conventional example.

In FIG. 1, first, an Al film having a thickness of 200.degree. Is formed as an intermediate layer 6 on the entire surface of the mask having the defect 3 shown in FIG. 2 by a sputter method (FIGS. 1A and 1B).

Next, while supplying hexacarbonylchromium (Cr (CO) ₆ ) gas, a YAG laser beam is applied to the defect 3 to decompose the adsorbed gas, thereby forming a deposition film 4 on the laser beam irradiated portion as a deposition film 4. A film is formed to a thickness of 800 ° (FIG. 3 (c)).

Then, the mask is immersed in phosphoric acid (H ₃ PO ₄ ) to selectively remove the Al film 6 as an intermediate layer, thereby completing defect repair as shown in FIG. 3 (FIG. 3). (D)). At this time, since the phosphoric acid does not etch the chromium film, the portion of the Al film 6 covered with the chromium film 4 remains without being etched.

As described above, according to the method of this embodiment, since the Al film 6 is formed on the entire surface of the substrate when the correction deposition film 4 is formed as an intermediate layer, the laser light is absorbed even on the glass substrate. Therefore, a deposition film having good adhesiveness is formed. Therefore, if the defect of the pattern is corrected by the method of the present invention, the corrected portion will not be peeled off by the cleaning.

In the above embodiment, Al is used as the intermediate layer 6 and wet etching with phosphoric acid is used for the etching, but the laser light is absorbed.

 Etching can be performed using the mask pattern 4 as a mask.

If the condition is satisfied, another metal or another etchant may be used, or a substance other than the metal such as an organic film may be used as the intermediate layer. Also, dry etching may be used instead of wet etching.

Further, in the above embodiment, the YAG laser is used for the correction, but a laser beam of another type and another wavelength may be used.

In the above embodiment, a photomask having a glass substrate has been described. However, as long as the mask substrate is transparent, the same effect can be obtained with an X-ray mask.

〔The invention's effect〕

As described above, according to the present invention, when correcting a pattern defect present in a mask pattern, an intermediate layer that absorbs laser light is formed on the entire surface of the mask before performing deposition by laser light, and the defect is corrected after the defect is corrected. By selectively removing the layer, the intermediate layer absorbs the energy of the laser beam even on a transparent substrate such as glass, and can form a highly adhesive deposition film. The film of the repaired portion is not peeled off, and there is an effect that a good mask without defects can be obtained.

[Brief description of the drawings]

1 (a) to 1 (d) are process sectional views showing an embodiment of the method of the present invention, and FIGS. 2 (a) and 2 (b) show an example of a pattern chipping defect used for explaining the embodiment. FIGS. 3A and 3B are a schematic plan view and a cross-sectional view taken along the line AB of the mark, and FIGS. 3A and 3B are a plan view of the mark after being corrected by the method of the above embodiment and a cross-sectional view taken along the line AB. Figures, FIGS. 4 (a) and (b)
5A and 5B are a plan view of a mask and an A-B cross-sectional view thereof showing an example of a mask corrected by a conventional method, and FIGS. 5A and 5B are plan views of a mask used to explain problems of the conventional example. It is a figure and the sectional view on the AB line. DESCRIPTION OF SYMBOLS 1 ... Mask substrate, 2 ... Mask pattern, 3 ... Pattern missing defect, 4 ... Deposition film for defect correction, 6
...... Intermediate layer.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03F 1/08-1/16

Claims (1)

(57) [Claims] In a mask for a semiconductor integrated circuit having a transparent substrate, an intermediate layer for absorbing a laser beam is formed over the entire exposed surface of the mask pattern when correcting a chipped defect existing in the mask pattern. And then the laser CV
After correcting the pattern chipping defect by the deposition according to D, the intermediate layer other than the repaired portion is removed using the deposition film as a mask, and the repaired portion has the intermediate layer and the deposition adhered thereon. A method for correcting a pattern defect in a mask, characterized by leaving a film.