JP2003121989A - Method for modifying halftone phase shifting mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for modifying a halftone phase shifting mask capable of saving labor for newly fabricating a mask for modification and capable of avoiding waste of material for the mask. SOLUTION: In a halftone phase shifting mask having a translucent film pattern and a light shielding film pattern on a transparent substrate, light shielding film residue which remains as a defect on the translucent film pattern is removed by applying a resist, patterning the resist with patterning data used in the formation of the light shielding film pattern without using a mask, forming a resist pattern by developing the resist to protect at least the light shielding film pattern and carrying out etching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect correction method for a halftone type phase shift mask used when a fine pattern such as an LSI is transferred by a projection exposure apparatus.

[0002]

2. Description of the Related Art Conventionally, as a halftone type phase shift mask, a semitransparent film made of MoSiN, MoSiON or the like is provided on a transparent substrate, and the semitransparent film forms a predetermined pattern in a transfer region. The non-transfer area is covered with a light shielding film made of chromium or the like. The following method is available as a method of manufacturing this type of halftone phase shift mask. After forming the semi-translucent film 2 on the transparent substrate 1, the light-shielding film 3 is formed, and then the positive electron beam resist 4 is formed (FIG. 4A). Next, a desired pattern is drawn with an electron beam and developed to form a resist pattern 4a (FIG. 2B). Next, the light-shielding film 3 is dry-etched using the resist pattern 4a as a mask to form the light-shielding film pattern 3a (FIG. 7C). next,
The semi-transmissive film 2 is dry-etched using the resist pattern 4a and the light-shielding film pattern 3a as a mask to form the semi-transmissive film pattern 2a (FIG. 3D). Next, the resist pattern 4a is peeled off ((e) in the figure). After that, the photoresist 5 is applied and baked (FIG. 7F). next,
A desired pattern is exposed to form a resist pattern 5a that covers the light-shielding film in the non-transfer area (FIG. 9 (g)). next,
The exposed light-shielding film is removed by, for example, wet etching using the resist pattern 5a as a mask (FIG. 6H). Finally, the resist pattern 5a is peeled off and washed to obtain a halftone type phase shift mask ((i) in the same figure). As a method of repairing the chromium residue on the halftone film in this type of halftone type phase shift mask, there is, for example, the technique described in JP-A-10-274839. According to this technique, as shown in FIG. 5, on the semi-transmissive film pattern 12 made of MoSiON in the semi-transmissive region (semi-transmissive film pattern region) 11 of the halftone type phase shift mask 10, the light-shielding region 13 is provided with Cr. If there is a Cr film residue 15 generated in the step of forming the light shielding film pattern 14, a resist 16 is applied to the entire surface of the mask 10. Then, exposure is performed using the correction mask 20 in which the Cr light shielding film pattern 21 is formed at the position corresponding to the light shielding region 13, the resist 16 is developed, and the Cr light shielding film pattern 14 is protected by the resist pattern 16. After that, the Cr film residue 15 is removed by etching.

[0003]

However, the above-mentioned prior art has the following drawbacks. (1) A mask must be newly prepared for correction. Therefore, labor and material costs are required. (2) Since the semi-translucent region 11 (size of the main chip) varies depending on the product type, the manufactured mask cannot always be used. (3) It is difficult to accurately overlay the correction mask on the semi-transmissive region 11 for exposure, and an unexposed portion or an excess exposed portion may occur. (4) Although wet etching is adopted in the embodiment, it has been found from the experience of the present inventor that the Cr residue that has remained once is not often etched by wet etching. The cause of this is unknown, but it is considered that this is because the physical properties of the Cr residue have changed with respect to the physical properties of the Cr light-shielding film. (5) The MoSiON semi-transparent film has weaker resistance to dry etching with a chlorine-based gas than the MoSiN semi-transparent film.

[0004]

In the above-mentioned conventional technique, the rate of occurrence of pattern defects is increased by the improvement of the degree of integration in recent semiconductor devices, or the increase of the pattern density accompanying the miniaturization and the adoption of the dry etching process. Therefore, since the number of times of correction increases by spot exposure, which is a problem in terms of labor, the present invention was invented as a correction method capable of correcting defects at a plurality of locations in one correction operation. is there. The present invention has the following configuration in order to solve the problems described above.

(Structure 1) In a halftone phase shift mask having a semi-transmissive film pattern and a light-shielding film pattern on a transparent substrate, the light-shielding film residue left as a defect on the semi-transmissive film pattern is masked after resist application. A method of repairing a halftone phase shift mask, which comprises exposing and developing a resist pattern to protect at least the light-shielding film pattern and then removing by etching without using.

(Structure 2) The half-tone phase shift mask according to Structure 1, wherein the light-shielding film pattern is formed in a non-transfer area other than a transfer area of the half-tone phase shift mask. How to fix.

(Structure 3) The light-shielding film residue left as a defect on the semi-transmissive film pattern is a residue generated by wet etching, and the method of removing the light-shielding film residue by etching is dry etching. 3. A method of repairing a halftone type phase shift mask according to Structure 1 or 2.

[0008]

According to the above structure 1, the light-shielding film residue left as a defect on the semi-light-transmitting film pattern is drawn based on the drawing data used for forming the light-shielding film pattern without using a mask after applying the resist, or based on the drawing data. Drawing using the drawing data, developing to form a resist pattern to protect at least the light-shielding film pattern, and then removing it by etching to create a new mask for correction and mask material (mask blank ) Can be omitted, and since the existing drawing data is used, accurate drawing can be easily performed. The drawing of the present invention includes laser drawing and electron beam drawing,
Laser drawing is preferred for ease of drawing.
As the drawing data, it is the simplest to use the drawing data used for forming the light-shielding pattern. However, when the number of defects is small or the defects are partially generated, it is used for forming the light-shielding pattern. The drawing time can be shortened by extracting the region covering the missing portion and performing the drawing based on the drawn data.

According to the invention of Structure 2, the entire semi-transparent film region where the semi-transparent film pattern is formed is exposed and developed to form a resist pattern in the region other than the semi-transparent film region. By protecting the light-shielding film pattern and then performing an etching process, the light-shielding film residue that remains as a defect on the semi-light-transmitting film pattern can be removed by etching, and on the semi-light-transmitting film pattern that cannot be detected by the defect inspection device. It is possible to simultaneously remove even minute Cr residue defects. In Configuration 2, the semi-transparent film region refers to a region including a region where the semi-transparent film pattern is formed or a region in the vicinity thereof.
In the normal case shown in FIG. 5, that is, when only the semi-transparent film pattern is formed in the semi-transparent film region 11 and the light-shielding region 13 is formed in the peripheral region of the mask excluding the semi-transparent film region. The semi-transparent film region referred to in the invention according to Configuration 2 is the semi-transparent film region 11 which is a pattern transfer region (device region).
Refers to the whole. As described above, the region where the light shielding film is formed is usually the region (non-transfer region) excluding the pattern transfer region, that is, the peripheral region of the mask. However, when the light shielding film pattern is also formed in the pattern transfer region, this light shielding film is formed. A region including the pattern portion or a region in the vicinity thereof is also included in the region where the light-shielding film is formed. In this case, the semi-light-transmitting film region referred to in the invention according to Configuration 2 is the region except the region where the light-shielding film pattern is formed or the region thereof. Refers to the area excluding the area including the neighborhood area. In configuration 2, the entire semi-transparent film region can be exposed by using the drawing data for leaving the light-shielding film used in the mask manufacturing process as it is and performing the exposure again for leaving the resist in the portion where the light-shielding film is left. Therefore, the correction can be performed easily and at low cost.

By using MoSiN for the semi-translucent film, damage to the semi-transmissive film due to dry etching (that is, phase difference, change in transmittance) can be minimized, and the mask step can be improved. It can be expected to improve the stay.

According to the above-mentioned structure 3, by adopting dry etching as a method of removing the light-shielding film residue by etching, it is possible to reliably remove the Cr residue which cannot be removed by wet etching.

[0012]

Embodiment 1 FIG. 1 is an explanatory view of a manufacturing process of a halftone type phase shift mask according to a first embodiment of the present invention, and FIG. 2 is an explanatory view of a correction process. This embodiment will be described below with reference to these drawings. The transparent substrate 1 is a quartz glass substrate (size 6 inch square, thickness 0.25 inch) whose surface is mirror-polished and subjected to predetermined cleaning. First transparent substrate 1
A semi-transparent film 2 made of molyfden, silicon, oxygen, and nitrogen was formed thereon by sputtering to have a film thickness of 100 nm, and then a light shielding film 3 made of chromium was formed at a film thickness of 100 nm. Then, a positive electron beam resist (ZEP70
00: manufactured by Zeon Corporation) was applied by a spin coating method to a film thickness of 500 nm (FIG. 1 (a)). Next, an electron beam drawing device (MEBES: manufactured by ETEC) is used to form a desired pattern.
Then, electron beam writing was carried out, and development was carried out to form a resist pattern 4a ((b) of the same figure). Next, using the resist pattern 4a as a mask, the light-shielding film 3 was etched by dry etching containing chlorine and oxygen to form a first light-shielding film pattern 3a (FIG. 7C). Next, the resist pattern 4a
Using the first light-shielding film pattern 3a as a mask, the semi-transmissive film 2 is mixed with CF ₄ / O ₂ mixed gas at a pressure of 0.4 Torr.
Dry etching was performed under the conditions of r and RF power of 100 W to form a semi-transmissive film pattern 2a (FIG. 3D). Finally, the resist pattern 4a was peeled off to complete a mask patterned up to the first step ((e) of the same figure). afterwards,
Photoresist (AZ1350: Clariant) 5
Was applied to a film thickness of 500 nm by a spin coating method and baked ((f) in the same figure). Next, a desired pattern was exposed (drawn) by a laser drawing device (ALTA3000: manufactured by ETEC) and developed to form a resist pattern 5a (FIG. 9 (g)). Next, using the resist pattern 5a as a mask, the first light-shielding film pattern 3a was etched using an etching solution containing cerium ammonium nitrate and perchloric acid to form a second light-shielding film pattern 3b (see FIG. h)). Finally, the resist pattern 5a was peeled off and a predetermined cleaning was performed to obtain a halftone type phase shift mask ((i) in the figure).

Next, after a predetermined cleaning, a defect inspection was conducted. As a result, an essentially unnecessary Cr residue defect 3c was found on the semi-transparent film pattern 2a, and it was clear that it cannot be used as it is as a halftone type mask (FIG. 2A). By the way, the phase difference at this point was 181.5 ° and the transmittance was 6.1%. Therefore, a positive photoresist (for example, AZ1350: manufactured by Clariant Co., Ltd.) 4 was applied (the same figure (b)). Next, the region where the semi-translucent film is exposed is exposed again and developed to form a resist pattern 4a (FIG. 7C). Then, the Cr residue 3c was removed by etching using a dry etching method consisting of chlorine and oxygen (FIG. 3 (d)). Finally, the resist pattern 4a was peeled off to obtain a normal halftone mask ((1e) in the same figure). After that, the phase difference and the transmittance were measured. As a result, the phase difference was 181.3 ° and the transmittance was 6.2%. There was almost no change from before the correction, and the semi-transparent film was almost damaged by the dry etching correction. Turned out not.

Embodiment 2 FIG. 3 is an explanatory view of a correction process of a halftone type phase shift mask according to a second embodiment of the present invention. This embodiment will be described below with reference to this drawing. Since the steps up to mask fabrication are the same as in Example 1, description thereof is omitted. After the mask was manufactured, a predetermined cleaning was performed and then a defect inspection was performed. As a result, an essentially unnecessary Cr residue defect 3c was found on the semi-transparent film pattern 2a, and it was clear that it could not be used as it is as a halftone mask (FIG. 3A). Therefore, a positive photoresist (for example, AZ1350: manufactured by Clariant Co., Ltd.) 4 was applied (the same figure (b)). Next, in the same manner, the area where the Cr residual defect is exposed is exposed by ALTA 3000 and developed to form a resist pattern 4a (FIG. 3C). In this exposure, since the exposure deposit area was extracted from the drawing data for exposing the area where the semi-transparent film is exposed so as to cover the defect from the coordinates of the defect portion, the time required for drawing is 20 minutes longer than the regular time. It was completed in a short time of about 1. Then, the Cr residue 3c was removed by etching using a dry etching method consisting of chlorine and oxygen (FIG. 3 (d)). Finally, the resist pattern 4a is peeled off,
A normal halftone mask was obtained ((e) in the same figure).

Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to the above embodiments.

[0016]

As described in detail above, according to the repairing method of the present invention, it is possible to save the trouble of newly preparing a repairing mask and the waste of the masking material. Further, as compared with the case of using a correction mask, it is possible to correct a defect only by adding a relatively simple process, and yet to obtain a high quality halftone type phase shift mask efficiently in a short time in a high yield. You can

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a manufacturing process of a halftone phase shift mask according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a correction process of the halftone type phase shift mask according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a correction process of the halftone type phase shift mask according to the second embodiment of the present invention.

FIG. 4 is an explanatory diagram of a manufacturing process of a halftone type phase shift mask.

FIG. 5 is an explanatory diagram of a conventional correction method of a halftone type phase shift mask.

[Explanation of symbols]

1 transparent substrate 2 Semi-transparent film 2a Semi-transparent film pattern 3 Light-shielding film 3a First light-shielding film pattern 3b Second light-shielding film pattern 3c Shield film residue 4 resist 4a Resist pattern 5 resist 5a resist pattern

Claims (3)

[Claims] 1. A halftone phase shift mask having a semi-transparent film pattern on a transparent substrate and a light-shielding film pattern at a desired position on the semi-transparent film, which remains as a defect on the semi-transparent film pattern. At least the light-shielding film pattern is formed by drawing the residue of the light-shielding film using the drawing data used for forming the light-shielding film pattern after applying the resist on the entire surface of the mask or the drawing data based on the data and developing the resist pattern to form a resist pattern. A method of repairing a halftone type phase shift mask, which comprises removing the protective film after etching. 2. The halftone phase shift mask according to claim 1, wherein the light shielding film pattern is formed in a non-transfer area of the halftone phase shift mask excluding a transfer area. How to fix. 3. The light-shielding film residue, which remains as a defect on the semi-translucent film pattern, is a residue generated by wet etching, and the method of removing the light-shielding film residue by etching is dry etching. A method of repairing a halftone phase shift mask according to claim 1 or 2.