JP2677086B2 - Defect repair method for phase shift mask - Google Patents

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 an exposure phase shift mask.

[0002]

2. Description of the Related Art FIG. 2 and FIG.
This paper shows the defect correction method for phase shift masks, which was published in the 1st JSAP Conference Lecture (27p-ZG-10) and in the monthly Semiconductor World 1991.5 p103-106.
2A to 2C are diagrams showing a state before defect correction, FIG. 2A is a sectional view showing a defective portion of the phase shift mask, and FIGS. Shows the transmitted light amplitude distribution and the transmitted light intensity distribution before defect correction. 3A is a sectional view of the phase shift mask after the defect is repaired, and FIGS. 3B and 3C show transmitted light amplitude distribution and transmitted light intensity distribution after the defect repair. In FIGS. 2 and 3, 1 is a quartz glass substrate, 2 is a conductive film, 3 is light-shielding chrome, 4 is a shifter, 5 is a concave defect present in the shifter 4, and 8 is the shifter 4 and an optical path of transmitted light. It is a sub-shifter composed of a transparent film having a refractive index (n) and a thickness (d) such that the length (nd) is the same.

Next, the operation will be described. When the concave defect 5 is present, the phase of the light transmitted through that portion is different from the surrounding normal portion, and the transmitted light amplitude distribution and transmitted light intensity distribution at that time are shown in FIGS. 2 (b) and 2 (c). As a result, a predetermined optical image cannot be obtained. In this conventional method, a sub-shifter 8 having the same optical length (nd) as that of the shifter 4 is provided, and the concave defect 5 is etched and removed to the surface of the conductive film 2 by using the FIB apparatus, so that the light transmitted through the shifter 4 is removed. The phase difference of the transmitted light in the portion where the concave defect 5 is removed is set to 360 °, and as a result, the phase is made to be the same phase. With such correction, the transmitted light amplitude distribution and the transmitted light intensity distribution are as shown in FIGS. 3B and 3C, and a predetermined optical image can be obtained.

[0004]

However, in the conventional defect correcting method of the phase shift mask as described above, it is necessary to further provide the sub shifter 8 under the shifter 4, and the FIB device is required for the defect correction. However, there is a problem in that it becomes expensive.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for inexpensively correcting defects in a phase shift mask.

[0006]

A method of repairing a defect of a phase shift mask according to the present invention is a method in which a repairing material is dropped and embedded in a concave defect and baked to match an optical constant with a shifter. The defect of the phase shift mask is corrected by etching back the correction material so that it is flush with the shifter.

[0007]

In the present invention, since the correction material is embedded in the concave defect and baked to have the same refractive index as that of the shifter, the correction material is etched back so as to be flush with the plane of the shifter. , The defective portion is easily repaired, and a predetermined optical image is obtained.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. 1A to 1D are process cross-sectional views showing a method of repairing defects in a phase shift mask according to the present invention, and FIG. 1A shows a state before repairing defects in the phase shift mask.
1B shows a step of burying a resist in a defective portion, FIG. 1C shows a baked state, and FIG. 1D shows an etched back state. In FIG. 1, 1 is a quartz glass substrate, 2 is a conductive film, 3 is blocking chrome, and 4 is S.
The shifters 5 made of OG or CVD SiO ₂ are concave defects of the shifter 4.

Next, the defect correction flow will be described.
First, a correction material, for example, a resist 7 is dropped from a nozzle 6 to the concave defect 5 shown in FIG.
(FIG. 1B). After that, the mask is baked so that the refractive index of the resist 7 changes depending on the temperature, so that the refractive index of the resist 7 becomes the same as that of the shifter 4 (FIG. 1).
(C)). Then, the phase shift mask is repaired by performing anisotropic etching until the resist plane filled with O ₂ plasma becomes flush with the shifter 4 (FIG. 1D).

In the above embodiment, the shifter 4 is S
Although OG or CVDSiO ₂ was used and the resist 7 was used as the repairing material, CVDSiO ₂ was used as the shifter 4, and the etching rates by the CVDSiO ₂ and O ₂ plasma were different as the repairing material, and the selection ratios were different.
You may use G.

[0011]

As described above, according to the present invention,
A correction material is dropped and embedded in the concave defect of the shifter of the phase shift mask, and the refractive index is matched with that of the shifter by baking it. Etching is performed by ordinary O ₂ anisotropic plasma etching until it is flush with the shifter. Therefore, the defect can be easily repaired, the conventionally used repairing sub-shifter is not required, and the FIB device is not required, so that the defect can be repaired at low cost.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a flow of a method of correcting a defect of a phase shift mask according to an embodiment of the present invention.

FIG. 2 is a diagram showing a conventional phase shift mask before defect correction.

FIG. 3 is a diagram showing a conventional phase shift mask after defect correction.

[Explanation of symbols]

 1 Quartz glass substrate 2 Conductive film 3 Light-shielding chrome 4 Shifter 5 Recessed defect 7 Resist

Claims (1)

(57) [Claims] 1. A method of correcting a defect of a concave defect of a phase shift mask for exposure, wherein a shifter for causing a phase difference of light is arranged on a quartz glass substrate, and the shifter is present in the shifter. After the correction material is dropped onto the concave defect portion and embedded therein, the baked correction material is baked so that the refractive index thereof is the same as the refractive index of the shifter. A method of repairing defects in a phase shift mask, characterized by etching back until it becomes the same plane as the plane.