KR20050010667A - Inspection method for non patterned wafer defect - Google Patents

Abstract

PURPOSE: A method of inspecting defects of a ratio pattern formed wafer is provided to improve the exactness of an inspecting process by using multi-critical values set up per each region based on the difference of thickness in a layer. CONSTITUTION: A ratio pattern formed wafer is manufactured by forming a layer on a wafer within a predetermined process deviation. The thickness of the layer is measured by using a laser beam source and a detector. Multi-critical values(900a,900b,900c) are set up according to the thickness of each region of the layer.

Description

Non-patterned wafer defect inspection method {INSPECTION METHOD FOR NON PATTERNED WAFER DEFECT}

The present invention relates to a non-patterned wafer defect inspection method. More specifically, the present invention relates to a method for inspecting defects by setting multiple thresholds for each non-patterned wafer region according to the thickness of a film formed within a predetermined process spread.

In general, a semiconductor device is formed by repeatedly forming and patterning a plurality of films on a wafer. At this time, if a defect that may occur in each film forming process exceeds a predetermined allowable limit, the completed semiconductor device may not work or may malfunction.

In addition, the test wafer used to check process abnormalities between semiconductor processes is a non-pattern forming wafer, and if a defect occurs, a test signal indicates that a process abnormality occurs, and equipment for inspecting defects is required for process improvement.

In general, equipment for inspecting defects of non-patterned wafers is KLA Tencor or AIT.

Currently, there are two types of non-patterned wafer inspection methods using the inspection equipment, one of which is an inspection method using laser scattering and the other of which is an inspection method using a CCD (Charge Coupled Devie) imaging device. to be.

The inspection equipment is also used to set process parameters. The type of the process parameter is a reflectance, a refractive index, a light amount, a threshold value of an intensity of light, which can be determined as a defect, according to the type of the film to be inspected.

1 is a cross-sectional view schematically illustrating a process of inspecting a defect of a conventional non-patterned wafer. 2 is a graph showing a single threshold value for determining an abnormality determination for a defect of a conventional non-patterned wafer.

Referring to FIG. 1, reference numeral 40 is a laser light source, 50 is a laser light, and 60 is provided with a detector for detecting the laser light 50 reflected from the film 20 formed on the wafer 10.

The process of inspecting the degree of defects in the film formed on the wafer using the non-patterned wafer inspection equipment using the laser scattering structure as described above is as follows.

The non-patterned wafer 30 having the film 20 to be inspected on the wafer 10 is prepared, and mounted and aligned on the inspection equipment.

Then, the non-pattern wafer 30 or the light source 40 and the detector 60 are moved by the same speed while being reflected by the film 20 and the defect 70 formed by irradiating the laser light 50. The laser beam 50 is detected through the detector 60.

Referring to FIG. 2, FIG. 2 shows the results detected by the detector, where the x-axis represents the position of the wafer and the y-axis represents the value of the light intensity.

A straight line represents a single threshold value 90 as a reference for determining the extent of the defect occurring in the non-patterned wafer.

The curve continuously represents the intensity 80 of the laser light 50 reflected by the film 20 and the defect 70 or the like.

The peaks A, B, and C in the curve represent the peaks of the laser light reflected by the defect 70 and the like, and have the intensity of the laser light exceeding the threshold 90. It is determined that the degree of defects is high.

However, the film formed on the wafer has a thicker center portion than the edge portion or thicker edge portion than the center portion for each non-pattern wafer region depending on the state of the equipment. It is common when

In addition, the difference in the thickness of the film formed on the wafer acts as a factor of raising or lowering the peak of the laser light reflected by the defect, thereby misinterpreting the degree of the defect, thereby making an error of abnormality determination, thereby lowering the process reliability. .

It is therefore an object of the present invention to provide a new process parameter setting method for inspecting non-patterned wafers in order to solve the above problems.

1 is a cross-sectional view schematically illustrating a process of inspecting a defect of a conventional non-patterned wafer.

2 is a graph showing a single threshold value for determining an abnormality determination for a defect of a conventional non-patterned wafer.

3 is a top view of a non-patterned wafer in contour lines showing the difference in thickness of the film formed on the wafer within a given process dispersion of the present invention.

4 is a cross-sectional view schematically illustrating a process of inspecting a defect of a non-patterned wafer of the present invention.

5 is a graph showing multiple threshold values for respective regions for determining an abnormality determination for defects in a non-patterned wafer of the present invention.

<Explanation of symbols for the main parts of the drawings>

10, 100: wafer 20, 200: film

30, 300: non-pattern forming wafer 40, 400: laser light source

50, 500: laser light 60, 600: detector

70, 700 defect 80, 800 intensity of reflected laser light

90, 900a, 900b, 900c: Threshold 1000: Contour

In order to achieve the above object, to form a non-patterned wafer by forming a film in a predetermined process dispersion on the wafer, measuring the thickness of the film formed on the non-patterned wafer and the measured non-patterned wafer To provide a non-patterned wafer defect inspection method comprising the step of setting multiple thresholds according to the thickness.

Therefore, by setting the multiple threshold value for each region according to the difference in the thickness of the film formed on the wafer to ensure the process reliability by accurately analyzing the degree of the defect during non-patterned wafer defect inspection.

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

3 is a top view of a non-patterned wafer in contour lines showing the difference in thickness of the film formed on the wafer within a given process dispersion of the present invention.

Referring to FIG. 3, the difference in the thickness after the thickness measurement of the film formed on the wafer within a predetermined process spread is shown by the contour line 1000. The contour line 1000 classifies the measured thickness of the film by region.

The thickness measurement method may be classified by region using the measured thickness after measurement using the thickness measurement equipment. The classification according to the thickness according to the thickness of the film should be classified into at least two or more regions. In FIG. 3, the non-pattern forming wafers classified by the contour lines are classified into three regions (A region, B region, and C region). It is shown.

The thickness of the film may be thicker from the A region to the C region of the non-patterned wafer, or may be thicker from the C region to the A region.

The area A may be referred to as a central portion of the non-patterned wafer, and the area C may be referred to as an edge portion of the non-patterned wafer.

4 is a cross-sectional view schematically illustrating a process of inspecting a defect of a non-patterned wafer of the present invention. FIG. 5 is a graph showing multiple threshold values for respective regions for determining an abnormality determination for defects in the non-patterned wafer of the present invention.

Referring to FIG. 4, reference numeral 400 is a laser light source, 500 is a laser light, and 600 is provided with a detector for detecting the laser light 500 reflected from the film 200 formed on the wafer 100.

The process of inspecting the non-patterned wafer shown in FIG. 3, that is, the non-patterned wafer divided into three regions due to the difference in thickness of the film, using the non-patterned wafer inspection equipment using the laser scattering structure as described above is as follows. Same as

The non-pattern forming wafer 300 having the film 200 to be inspected on the wafer 100 is prepared, and mounted and aligned on the inspection equipment.

The formed film is a non-patterned wafer divided into three regions due to the thickness difference.

In addition, the laser beam 500 is irradiated while moving the non-pattern forming wafer 300 or the light source 400 and the detector 600 at the same speed, and the film 200 and the defects formed for each of the three regions ( The laser beam 500 reflected by the 700 is detected through the detector 600.

Referring to FIG. 5, FIG. 5 shows the results detected by the detector, where the x-axis represents the position of the wafer and the y-axis represents the value of the light intensity.

The curve shows the film 200 formed for each of the three regions and the intensity 800 of the laser light reflected by the defect 700.

Peaks A ', B', and C 'in the curve represent the reflection peaks of the laser light reflected by the defect 700.

Here, multiple threshold values 900a, 900b, which serve as a reference for determining the degree of defects for each region of the non-patterned wafer in consideration of the intensity of laser light reflected on the thickness of the film 200 formed for each of the three regions. 900c).

The reflection peak of the laser beam reflected by the defect 700 is confirmed using the set multiple threshold values 900a, 900b, and 900c for each region, and the degree of the defect 700 is determined by the thickness of the film for each non-patterned wafer region. It was judged accurately regardless.

Therefore, by setting the multiple threshold value for each region according to the difference in the thickness of the film formed on the wafer to ensure the process reliability by accurately analyzing the degree of the defect during non-patterned wafer defect inspection.

By setting multiple threshold values for each region according to the difference in the thickness of the film formed on the wafer, the process reliability is secured by accurately analyzing the degree of the defect during non-pattern forming wafer defect inspection.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below. I can understand that you can.

Claims (5)

Forming a non-patterned wafer by forming a film on the wafer within a predetermined process spread; Measuring a thickness of a film formed on the non-patterned wafer; And And setting multiple threshold values according to thicknesses on the measured non-patterned wafers. The method of claim 1, wherein the non-patterned wafer defect inspection method further comprises classifying the measured thickness of the film by wafer region. The non-pattern wafer defect inspection method according to claim 2, wherein the classification by area is classified into at least two areas. 2. The method of claim 1, wherein the thickness of the film is thickened from the center portion of the non-pattern forming wafer to the edge portion. The method of claim 1, wherein the thickness of the film is thickened from the edge portion of the non-patterned wafer to the center portion.