KR20030089342A - Method for measuring eccentricity of exposure apparatus - Google Patents

Abstract

PURPOSE: A method for measuring eccentricity of semiconductor exposure equipment is provided to measure eccentricity of a light source by measuring asymmetry of critical dimension(CD) between photoresist layer patterns formed by an exposure process and a development process using a phase shift mask(PSM) with a phase difference of 0 degree and 90 degrees. CONSTITUTION: A photoresist layer is formed on a wafer. A photoresist layer pattern is formed through an exposure and development process using the PSM with a phase difference of 0 degree and 90 degrees. The asymmetry of CD between the photoresist layer patterns is measured and a proportional constant between the CD asymmetry and the eccentricity of the light source is obtained to abstract the eccentricity of the light source.

Description

Depth measurement method of semiconductor exposure equipment {Method for measuring eccentricity of exposure apparatus}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the depth of a semiconductor exposure apparatus. In particular, the method for measuring the depth of a semiconductor exposure apparatus improves the yield and reliability of a device by measuring the depth of a light source in a pattern formed on a wafer. It is about.

The depth of the light source is the degree to which the center of the light source deviates from the optical axis of the projection lens and can be measured by the equipment manufacturer at the assembly stage of the exposure equipment, but after the exposure equipment is assembled, that is, in the pattern formed on the wafer There was no method to measure.

Depth of the light source has a problem that the patterning process is difficult to cause the uniformity of the light source and the occurrence of exposure aberration in the semiconductor exposure equipment.

The present invention has been made to solve the above problems, by measuring the CD (Critical Dimension) asymmetry between the photosensitive film pattern formed by the exposure process and the development process using a PSM (Phase Shift Mask) having a phase difference of 0 degrees and 90 degrees It is an object of the present invention to provide a method for measuring the depth of a semiconductor exposure apparatus for measuring the depth of depth.

1A to 1D are cross-sectional views illustrating a method of forming a PSM having a phase difference of 0 degrees and 90 degrees.

2 is a cross-sectional view showing the diffraction direction of light in a PSM having a phase difference of 0 degrees and 90 degrees.

3 is a graph showing the depth of field of the light source.

4 is a schematic diagram showing a simulation result of an image change according to the depth of a light source and an expected photoresist pattern in a PSM having a phase difference of 0 degrees and 90 degrees according to an exemplary embodiment of the present invention.

5 is a graph showing the results of simulating the CD difference between the left and right lines according to the depth of the light source.

<Description of Symbols for Major Parts of Drawings>

DESCRIPTION OF SYMBOLS 1 Translucent board | substrate 3: 1st light transmission area

5: Light shielding layer pattern 7: Photosensitive film

9: second projection region 11: incident pupil

21 wafer 23 photosensitive film pattern

The present invention for achieving the above object,

Applying a photoresist film on the wafer,

The photosensitive film pattern is formed by an exposure and development process using a PSM having a phase difference of 0 degrees and 90 degrees, the CD asymmetry amount is measured between the photosensitive film patterns, and the proportionality constant between the CD asymmetry amount and the depth of the light source is obtained to determine the depth of light source. And providing a method for measuring the depth of field of the semiconductor exposure equipment comprising the step of extracting,

CD asymmetry between the photoresist pattern is characterized in that it is measured by using a scanning electron microscopy (SEM),

The light source is characterized by using all light sources with a wavelength of 10 ~ 436nm.

The principle of the present invention is to measure the CD asymmetry between the photosensitive film pattern formed by the exposure process and the development process using a PSM having a phase difference of 0 degrees and 90 degrees. It is an invention for improving and preventing the occurrence of exposure aberration.

At this time, since the CD asymmetry is changed linearly according to the depth of the light source, the proportion of the CD asymmetry and the depth of the light source can be obtained to measure the depth of the light source in the pattern formed on the wafer.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1A to 1D are cross-sectional views illustrating a method of forming a PSM having a phase difference of 0 degrees and 90 degrees.

Referring to FIG. 1A, a light shielding layer pattern 5 defining a first light transmissive region 3 having a phase of 0 degrees is formed on the light transmissive substrate 1. In this case, the light transmissive substrate 1 is formed of glass or quartz, and the light blocking layer pattern 5 is formed of chromium.

Then, the photosensitive film 7 is formed on the light transmissive substrate 1 including the light blocking layer pattern 5.

Referring to FIG. 1B, the photosensitive film 7 is patterned by a process of exposing and developing using a mask that exposes a light-transmitting region having a phase of 90 degrees.

Referring to FIG. 1C, the light-transmissive substrate 1 exposed using the patterned photoresist 7 as a mask is etched to form a second light-transmitting region 9 having a phase of 90 degrees.

Referring to FIG. 1D, the photosensitive film 3 is removed to expose the first light-transmitting region 3 whose phase is 0 degrees.

FIG. 2 is a cross-sectional view showing the diffraction direction of light in a PSM having a phase difference of 0 degrees and 90 degrees, and FIG. 3 is a graph showing an eccentricity of a light source.

Referring to FIG. 2, in the PSM having a phase difference of 0 degrees and 90 degrees, the zero-order diffracted light travels in a direction slightly inclined with respect to the optical axis because the phases of the light-transmitting region are alternately located at 0 degrees and 90 degrees. Since the first-order diffracted light is distributed to make an overall image, information on the tilt of the light source can be extracted.

Referring to FIG. 3, σ, which is an illumination coherence, is determined as a value obtained by dividing the size of a light source formed in the entrance pupil 11 of the projection lens by the size of the entrance pupil 11, and the eccentricity of the light source. (ε) is determined as the amount of the shift amount of the light source formed in the incident pupil 11 compared with the size of the incident pupil 11.

FIG. 4 is a schematic diagram illustrating a simulation result of an image change according to an eccentricity of a light source and an expected photoresist pattern in a PSM having a phase difference of 0 degrees and 90 degrees according to an embodiment of the present invention, and FIG. It is a graph which shows the result of simulating the CD difference between left and right lines.

4 and 5, a photosensitive film is coated on the wafer 21.

The size of the line / space on the mask is 0.15 μm based on the size of the pattern formed on the wafer, the wavelength is 248 nm, and the numerical aperture is 0.70 and? An exposure process using a PSM having a depth and a depth of light of the light source is performed, and a photoresist pattern 23 is formed by a subsequent development process.

At this time, as a result of simulating the process, as the light source is moved from the optical axis, the image is rapidly changed, and thus the photoresist pattern 23 formed on the wafer 21 is asymmetrically changed.

At this time, the depth of the light source is measured by an asymmetric change of the photoresist pattern 23.

That is, since the CD asymmetry between the photoresist pattern 23 is linearly changed according to the depth of light source, if the proportional constant between the depth of light source and the CD asymmetry between the photoresist pattern 23 is known, the photoresist pattern 23 By measuring the amount of CD asymmetry of the liver, it is possible to accurately extract the depth of light source.

At this time, as the light source, all light sources having a wavelength of 10 to 436 nm, such as I-line, g-line, KrF, ArF, and F of Hg lamps, and light sources of all shapes such as circles, are used, and SEM is used to form the photoresist pattern ( 23) CD asymmetry can be measured.

Depth measurement method of the semiconductor exposure equipment of the present invention by measuring the CD asymmetry of the photosensitive film pattern formed by the exposure and development process using a PSM having a phase difference of 0 degrees and 90 degrees to measure the depth of the light source and using the uniformity of the light source By improving the efficiency and preventing the occurrence of exposure aberration, there is an effect of improving the yield and reliability of the device and reducing the production cost of the device.

Claims (3)

Applying a photoresist film on the wafer, The photosensitive film pattern is formed by an exposure and development process using a PSM having a phase difference of 0 degrees and 90 degrees, the CD asymmetry amount is measured between the photosensitive film patterns, and the proportionality constant between the CD asymmetry amount and the depth of the light source is obtained to determine the depth of light source. Depth measurement method of a semiconductor exposure equipment comprising the step of extracting. The method of claim 1, CD asymmetry amount between the photosensitive film pattern is a method for measuring the depth of depth of the semiconductor exposure equipment, characterized in that by using a SEM. The method of claim 1, The light source is a depth measurement method of a semiconductor exposure equipment, characterized in that using all the light source of the wavelength of 10 ~ 436nm.