JPH03139647A - Correcting method for mask - Google Patents

Abstract

PURPOSE:To make corrections with high accuracy without damaging a glass substrate by correcting a black defect by a laser correcting device which has low correction accuracy and forming a white defect on a light shield pattern, and then correcting the white defect by a converged ion beam correcting device which has high correction accuracy. CONSTITUTION:When the black defect 2 (excessive part of light shield film) of the mask for exposure where the light shield pattern 1 is formed of a light shield film on a transparent substrate is removed, the black defect part is irradiated with a converged laser beam to remove the light shield film of the black defect part, and at the same time the light shield film is removed even from a normal light shield pattern adjoining to the black defect part to form the white defect 5 (absence part of light shield film). Then organic gas is blown to the white defect part, which is irradiated with a converged ion beam to polymerize the organic gas, thereby depositing a carbon film on the white defect part. Consequently, the etching process of the glass substrate is omitted and the black defect can be corrected with high accuracy without damaging the glass substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] This invention relates to a method for repairing a mask used in a manufacturing process of semiconductor devices and the like.

The object of the present invention is to provide a highly accurate method for correcting black defects without damaging the glass substrate by omitting the etching process of the glass substrate.

When removing a black defect (excess portion of the light shielding film) of an exposure mask in which a light shielding pattern made of a light shielding film is formed on a transparent substrate, the black defect portion is irradiated with a focused laser beam,
At the same time as removing the light shielding film in the black defect part, the light shielding film is also removed from the normal light shielding pattern adjacent to the black defect part to form a white defect (the part where the light shielding film is missing). The organic gas is polymerized by blowing gas and irradiating with a focused ion beam, and a carbon film is deposited on the white defect portion.

[Industrial application field]

The present invention relates to a method for repairing a mask used in the manufacturing process of semiconductor devices and the like.

In recent years, the accuracy of defect correction for masks and reticles has been ±0.
1 μm, focused ion beam (FIB) correction is becoming mainstream in place of traditional laser correction methods.

The present invention can be applied as a highly accurate method for correcting black defects without damaging glass substrates.

[Conventional technology]

Defects in the mask include white defects such as pinholes in the light-shielding film, and black defects such as protrusion of the light-shielding film.

A conventional method for repairing black defects uses a laser repair device to irradiate a focused laser beam onto the defective area to blow away the light-shielding film material.

However, as mentioned above, laser repair methods are no longer able to satisfy the required repair accuracy. For this reason, FIB correction devices have been developed and have become widely used.

The correction accuracy of the FIB correction device is ±0.0 for both black and white defects.
1 μm (3σ), and conventional laser correction equipment has a correction accuracy of ±0.
The limit was 2 μm (3σ).

However, the correction of black defects by FIB correction equipment is difficult.

After modification, impurities (Ga stain) are implanted into the glass substrate. This implanted impurity layer reduces the light transmittance (down to 86% when measured at the g-line), so it is necessary to remove the impurity layer in order to restore the transmittance. To achieve this, the glass substrate is etched using a metal light-shielding film as a mask. On this occasion,
Since the impurity layer has a thickness of approximately 300 nm, etching is required to be 2' thicker.

FIGS. 2(1) to 2(3) are partial plan views of mask patterns illustrating a conventional FIR correction method for black defects.

In FIG. 2(1), a black defect 2 is formed in a normal light-shielding pattern 1 made of a metal light-shielding film.

3 is a light transmitting part where the glass substrate is exposed.

In FIG. 2(2), after the FIB correction of the black defect is performed, an impurity layer 4 is formed which is implanted into the surface of the glass substrate after the defect has been removed.

In FIG. 2(3), the glass substrate is etched by dry etching using CF4 using a metal light-shielding mask to remove the impurity layer 4.

(Problems to be Solved by the Invention) When a black defect is repaired by FIB, impurities are implanted into the glass substrate in the defect-removed portion that should become transparent, so etching of the glass substrate is necessary.

When a glass substrate is etched, the following secondary problems occur.

In the above example, the glass substrate was etched by dry etching using CF, but etching is carried out using a metal shielding film (Cr film) as an etching mask, whether dry or wet. The etching selection ratio at this time is approximately 2.
It is 0. Therefore, the Cr film that acts as a mask is also damaged by approximately 1/20 of the amount of etching on the glass (approximately 30
Since zero etching is performed, the Cr film will be etched by about 15 μm). This is a problem because it damages the Cr film, which requires durability.

SUMMARY OF THE INVENTION An object of the present invention is to provide a highly accurate method for correcting black defects without damaging the glass substrate by omitting the etching process of the glass substrate.

[Means to solve the problem]

The solution to the above problem is to irradiate a focused laser beam to the black defect portion when removing a black defect (excess portion of the light shielding film) of an exposure mask in which a light shielding pattern made of a light shielding film is formed on a transparent substrate. , At the same time as removing the light shielding film in the black defect part, the light shielding film is also removed from the normal light shielding pattern adjacent to the black defect part to form a white defect (a part where the light shielding film is missing). This is achieved by a mask repair method in which an organic gas is sprayed and a focused ion beam is irradiated to polymerize the organic gas and deposit a carbon film on the white defect area.

[Effect]

The present invention corrects black defects using a laser correction device with low correction accuracy to create white defects in light-shielding patterns (the size of which is equal to or larger than that which inevitably occurs when trying to completely remove black defects due to low accuracy). white defects) are formed, and then,
By correcting white defects using an FIB correction device with high correction accuracy, it is possible to perform high-precision correction without causing damage to a glass substrate that occurs when a black defect is directly corrected with an FIB correction device.

The reason why FIB correction is more accurate than laser correction is as follows.
This is because while the minimum spot diameter of a laser is 2 μm, the ion beam diameter can be narrowed down to 0.1 μm. Furthermore, the FIB repair device can perform fully automatic alignment of defective locations, improving repair accuracy.

〔Example〕

FIGS. 1(1) to 1(3) are partial plan views of a mask pattern illustrating a method for correcting black defects according to an embodiment of the present invention.

In FIG. 1(1), a black defect 2 is formed in a normal light-shielding pattern 1 made of a metal light-shielding film.

3 is a light transmitting part where the glass substrate is exposed.

In FIG. 1(2), after the 5 black defects are laser-corrected, a white defect 5 is formed in the light-shielding pattern I after defect removal.

An example of the laser repair conditions for black defects in this case is shown below.

Laser salt used: WAG Laser power: 50 mJ Focused spot diameter: 2 μm (MIN) Others: All alignment of the repaired area is done manually In this case, the size of the white defect 5 is inevitable if you try to completely remove the black defect. equal to or greater than that occurring in

In FIG. 1(3), FIB correction of white defect 5 is performed.

6 is a light-shielding portion where the white defect 5 has been corrected.

Next, an example of FIB correction conditions for white defects will be shown.

Ion source used: Ga liquid metal ion source Acceleration energy: 20 KeV Focused spot diameter = 0.1 μm Others: The procedure for fully automatic FIB correction for alignment of the correction location is as follows.

■ Spray organic gas around the defect.

■Irradiate the focused ion beam only to the defective area.

■ A uniform carbon (component of organic gas) film is deposited on the defective area.

White defects are corrected by the above procedure.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to omit the etching step of the glass substrate, and therefore, a highly accurate method for repairing black defects without damaging the glass substrate has been obtained.

In the figure A normal light-shielding pattern made of a Group 1 light-shielding film divided by 2 is a black defect.

3 is the light transmitting part where the glass substrate is exposed.

4 is an impurity layer implanted by FIB correction.

5 is a white defect created by laser correction of a black defect.

6 is the light-shielding film in the white defect correction area

[Brief explanation of the drawing]

FIGS. 1(1) to 1(3) are partial plan views of mask patterns illustrating a method for correcting black defects according to an embodiment of the present invention. FIGS. 2(1) to 2(3) are partial plan views of mask patterns illustrating a conventional FIB correction method for black defects. 6 Plan view of the embodiment Fig. 1 Plan view of the conventional example Fig. 2

Claims (1)

[Claims] When removing black defects (excess portions of the light shielding film) of an exposure mask in which a light shielding pattern made of a light shielding film is formed on a transparent substrate, the black defect portion is irradiated with a focused laser beam. , At the same time as removing the light shielding film from the black defect part, the light shielding film is also removed from the normal light shielding pattern adjacent to the black defect part to remove the white defect (
A carbon film is deposited on the white defect by spraying an organic gas onto the white defect and irradiating the white defect with a focused ion beam to polymerize the organic gas. How to modify a mask.