JPH05323568A - Phase shift mask and its manufacture - Google Patents

Abstract

PURPOSE:To make the mask applicable to a great exposure pattern width as well by providing a taper angle for a boundary face to define a phase- inverted area, so that phase invertion can be gently performed from a sequencial phase portion to an opposite phase portion. CONSTITUTION:After a resist layer is formed on the whole upper face of a substrate 1, patterning using a chrome pattern 2 as a mask is given from the lower part of the substrate 1 by back exposure to form a resist mask 3. Dry etching using the resist pattern 3 as a mask is given from the upper part of the substrate 1 to form a recessed portion 4 as an opposite phase portion. Then, a boundary face 5 with a specified taper angle is formed. Next, the resist pattern 3 and the chrome pattern 2 are removed in sequence. In this way, a phase shift mask 7 without having a chrome pattern (a chromeless phase shift mask) can be obtained, for which a sequencial phase portion 6, an opposite portion 4 and a phase judgment portion 5 (a boundary face) laid therebetween are provided on a silicon substrate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase shift mask, which is useful as a reticle for photolithography in the manufacture of semiconductor devices, and which is made of metal such as chromium and has no light-shielding pattern, and a method for manufacturing the same.

[0002]

2. Description of the Related Art A phase shift mask that does not use a light-shielding pattern such as chromium (for example, "chromeless phase shift mask").
Is formed on the surface of a quartz plate or the like according to the required mask pattern, and causes phase inversion of the transmitted light at the boundary area between the concave and flat portions due to the optical path difference between the two. is there. A sharp decrease in light intensity due to phase reversal in the boundary area between the order phase part composed of the flat part and the anti-phase part (shifter part) composed of the concave part causes the same effect as that of the light shielding part. It is generated and functions as a mask.

In the conventional chromeless phase shift mask, a phase shift mask having a chrome pattern (for example, an edge enhancement type phase shift mask) is formed with an inverted phase portion (recess), and then a relatively phased phase portion is formed. It was made by removing the chromium pattern on the surface. At that time, the boundary surface forming the phase inversion region between the order phase part and the antiphase part is
It was formed almost perpendicular to the surfaces of the rank phase portion and the antiphase portion parallel to each other.

Since the chromeless phase shift mask has no light-shielding portion such as a chrome pattern, there is no need to change the width of the exposure pattern by changing the width of the chrome pattern. Then, since the width of the transition region in which the phase inversion occurs at the substantially vertical boundary surface has a substantially constant value according to the specific characteristics of the target light, the range of applicable exposure pattern width is extremely limited. There was a flaw.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a phase shift mask having no light-shielding pattern and a method of manufacturing the same, which is applicable to an exposure pattern width larger than the conventional one.

[0006]

According to the present invention, the above-mentioned object is such that the boundary surface defining the phase inversion region between the order phase part and the anti-phase part is changed from the order phase part to the anti-phase part. And a phase shift mask having no light-shielding pattern, which has a tapered surface so that the phase inversion can be performed gently.

According to the method of manufacturing a phase shift mask without a light-shielding pattern of the present invention, the boundary surface defining the phase inversion region between the order phase portion and the anti-phase portion is moved from the order phase portion to the anti-phase portion. It is characterized in that it is formed with a taper so that the phase inversion can be performed gently.

[0008]

In the present invention, since the boundary surface forming the phase inversion part between the order phase part and the antiphase part has a taper,
Since the phase inversion is gradually performed as compared with the conventional vertical boundary surface, the range in which the light intensity decreases decreases and the pattern width to be exposed also increases accordingly.

[0009]

EXAMPLE A phase shift mask without a chrome pattern was prepared according to the present invention. The procedure will be described with reference to FIG. The steps (1) to (4) in FIG.
3 shows a cross section of a state in which the process in 1 is completed.

[Procedure 1] A chrome film (thickness 900Å) was formed on a quartz substrate (thickness) 1 by sputtering, and this was patterned by an electron beam drawing method to form a chrome pattern 2.

[Procedure 2] After forming a resist layer on the entire upper surface of the substrate 1, the substrate 1 using the chromium pattern 2 as a mask
The resist mask 3 was formed by patterning by backside exposure from below.

[Procedure 3] Substrate 1 using resist pattern 3 as a mask by a balanced plate type plasma etching apparatus
Dry etching was performed from above to form a recess 4 having a depth of 2750Å as an antiphase portion (shifter portion). For dry etching, the gas composition is CF ₄ 30% + CH ₃ 70
% And 1.8 Torr, and 2 W / cm ² .
As a result, the boundary surface 5 having the taper angle θ≈75 ° was formed.

[Procedure 4] Next, the resist pattern 3 was removed with an etchant having the following composition 1, and the chromium pattern 2 was removed with an etchant having the following composition 2. As a result, a phase shift mask (chromeless phase shift mask) 7 having no chromium pattern, which is formed by providing the order phase portion 6, the antiphase portion 4, and the phase inversion portion (boundary surface) 5 between them on the quartz substrate 1, is provided. was gotten. Etchant composition Composition 1: H ₂ O ₂ (50 cc) + H ₂ SO ₄ (4000
cc) Composition 2: ceric ammonium nitrate (16.8 wt.
%) + Ammonium nitrate (6.5 wt%) + surfactant

For comparison with the mask of the present invention, a conventional mask having the same structure as the mask 7 except that it has a vertical boundary surface 5 was prepared. Using the present invention and the conventional chromeless phase shift mask, pattern formation was performed under the following conditions. Pattern formation conditions Exposure method: reduction projection exposure Exposure light: wavelength 248 nm (KrF excimer laser) Exposure target: Si substrate + chemically amplified resist (thickness: 0.
7 μm)

As a result of the above pattern formation, the conventional mask has a pattern width of 0.18 to 0.20 μm, while the mask according to the present invention has a pattern width of 0.20 to 0.23 μm wider than the conventional pattern width. was gotten. This pattern width obtained by the present invention is between the pattern width 0.25-0.28 obtained by the excimer laser using the chrome pattern mask and the pattern width obtained by the conventional chromeless phase shift mask. Yes, it enables pattern widths that were outside the applicable range in the past.

As described above, according to the present invention, it is possible to widen the exposure pattern width obtained by the chromeless phase shift pattern and easily realize the pattern width which has been difficult in the past.

[Brief description of drawings]

FIG. 1 is a sectional view showing a procedure for producing a chromeless phase shift mask according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Quartz substrate 2 ... Chrome pattern 3 ... Resist pattern 4 ... Recessed part as antiphase part (shifter part) 5 ... Phase inversion part (boundary surface) 6 ... Flat part as order phase part 7 ... Chromeless phase shift of this invention mask

Claims (2)

[Claims] 1. A boundary surface that defines a phase inversion region between the order phase portion and the antiphase portion has a taper so that the phase inversion is performed gently from the order phase portion to the antiphase portion. A phase shift mask without a light-shielding pattern. 2. A boundary surface that defines a phase inversion region between the order phase part and the antiphase part is tapered so that the phase inversion is performed gently from the order phase part to the antiphase part. A method for manufacturing a phase shift mask having no light-shielding pattern, which is characterized by being formed.