CN115798558A - Wafer evaluation method, apparatus and readable storage medium - Google Patents
Wafer evaluation method, apparatus and readable storage medium Download PDFInfo
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- CN115798558A CN115798558A CN202211657812.4A CN202211657812A CN115798558A CN 115798558 A CN115798558 A CN 115798558A CN 202211657812 A CN202211657812 A CN 202211657812A CN 115798558 A CN115798558 A CN 115798558A
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Abstract
The embodiment of the invention provides a wafer evaluation method, a wafer evaluation device and a readable storage medium, wherein the method comprises the following steps: acquiring a wafer image; dividing a plurality of areas in the wafer image; determining a plurality of area groups in the plurality of areas according to the fact that two adjacent areas form a group; calculating a particle density ratio of two regions in the set of regions; and determining that the wafer corresponding to the wafer image is an abnormal product under the condition that the calculated particle density ratio is greater than a preset threshold.
Description
Technical Field
The embodiment of the invention relates to the technical field of wafer processing, in particular to a wafer evaluation method, a wafer evaluation device and a readable storage medium.
Background
Crystal Originated defects (COPs) are particularly important for monitoring COPs because, during Crystal growth, due to the formation of octahedral voids by vacancy aggregation, the production of COPs will directly affect whether the produced wafers are acceptable. The current monitoring method mainly includes periodically monitoring the detection data of a Particle Counter (Particle Counter) by a manual method. Specifically, wafers are spot-inspected according to different carriers and different blocks (blocks), after the wafers are extracted to the carriers, overlay images (Overlay) are performed on all the wafers in the carriers, and the detection map is observed in such a way, so as to artificially determine whether COP exists. However, the problem of missing inspection caused by the fact that all products cannot be inspected completely exists in manual detection, and subjective influence exists in manual judgment, so that the wafer evaluation result is not accurate enough.
Disclosure of Invention
The embodiment of the invention provides a wafer evaluation method, a wafer evaluation device and a readable storage medium, which solve the problems that all products cannot be completely inspected by manually detecting COP (coefficient of performance), the inspection omission occurs, subjective influence exists in manual judgment, and the evaluation result of a wafer is not accurate enough.
According to a first aspect of the embodiments of the present invention, there is provided a wafer evaluation method, including:
acquiring a wafer image;
dividing a plurality of areas in the wafer image;
determining a plurality of area groups in the plurality of areas according to the condition that two adjacent areas form a group;
calculating a particle density ratio of two regions in the set of regions;
and determining that the wafer corresponding to the wafer image is an abnormal product under the condition that the calculated particle density ratio is greater than a preset threshold.
Optionally, the dividing the wafer image into a plurality of regions includes:
dividing a plurality of regions in the wafer image from inside to outside;
in the two adjacent areas, the inner area is a first area, and the outer area is a second area.
Optionally, the dividing the wafer into a plurality of regions from inside to outside includes:
and dividing a plurality of annular regions with the same circle center from inside to outside at equal intervals in the wafer image.
Optionally, the calculating a particle density ratio of two regions in the set of regions comprises:
and sequentially calculating the particle density ratio of the second region to the first region in each region group according to the sequence from outside to inside.
Optionally, the number of the plurality of regions is 5 to 15.
Optionally, the preset threshold is 3.5 to 4.5.
According to a first aspect of the embodiments of the present invention, there is provided a wafer evaluation apparatus, comprising:
the acquisition module is used for acquiring a wafer image;
the dividing module is used for dividing a plurality of areas in the wafer image;
the first determining module is used for determining a plurality of area groups in the plurality of areas according to the fact that two adjacent areas form a group;
a calculation module for calculating a particle density ratio of two regions in the set of regions;
and the second determining module is used for determining that the wafer corresponding to the wafer image is an abnormal product under the condition that the calculated particle density ratio is greater than a preset threshold.
Optionally, the dividing module is specifically configured to:
dividing a plurality of regions in the wafer image from inside to outside;
among the two adjacent areas, the inner area is a first area, and the outer area is a second area.
Optionally, the dividing module is specifically configured to:
and dividing a plurality of annular regions with the same circle center from inside to outside at equal intervals in the wafer image.
Optionally, the calculation module is specifically configured to:
and sequentially calculating the particle density ratio of the second region to the first region in each region group according to the sequence from outside to inside.
Optionally, the number of the plurality of regions is 5 to 15.
Optionally, the preset threshold is 3.5 to 4.5.
According to a first aspect of embodiments of the present invention, there is provided a readable storage medium on which a program or instructions are stored, which program or instructions, when executed by a processor, implement the steps of the wafer evaluation method according to the first aspect.
In the embodiment of the invention, the wafer image is divided into a plurality of areas, the two adjacent areas are taken as a group, the particle density ratio of the two areas in the area group is calculated, and the wafer corresponding to the wafer image is judged to be an abnormal product under the condition that the calculated particle density ratio is greater than a preset threshold. Therefore, on one hand, compared with the existing method for overlaying and observing the wafer, the detection method for calculating the particle density ratio of the two areas is easier to execute, can be applied to detection of all wafers, realizes full detection of all products and avoids the problem of missed detection, and on the other hand, the unified rule can be applied to automatic detection, so that manual detection is abandoned, subjective influence on detection is avoided, and the accuracy of wafer evaluation results is improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.
FIG. 1 is a schematic flow chart illustrating a wafer evaluation method according to an embodiment of the present invention;
fig. 2 is a schematic view of an application scenario provided in an embodiment of the present invention;
FIG. 3 is a schematic illustration of a crystal pulling crystal boundary;
FIG. 4 is a diagram of a process of forming a ring COP;
FIG. 5 is a ratio chart of the ring radius of the ring-shaped COP;
FIG. 6 is a graph of the average number of particles in different regions;
FIG. 7 is a graph of the ratio of COP area to inner ring area;
fig. 8 is a graph of the ratio of COP region to outer ring region.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, an embodiment of the present application provides a wafer evaluation method, including the following steps:
step 101: acquiring a wafer image; the wafer image can be obtained by the existing method, and the microscopic image is required to be used for detecting COP, so that the wafer image can be shot by a microscope camera.
Step 102: dividing a plurality of areas in the wafer image;
step 103: determining a plurality of area groups in the plurality of areas according to the fact that two adjacent areas form a group;
step 104: calculating a particle density ratio of two regions in the set of regions;
step 105: and determining that the wafer corresponding to the wafer image is an abnormal product under the condition that the calculated particle density ratio is greater than a preset threshold. Since the region with COP on the wafer has a significant variation in particle density, in the embodiment of the present application, it can be determined whether COP exists based on the particle density ratio between two adjacent regions.
In the embodiment of the invention, the wafer image is divided into a plurality of areas, the two adjacent areas are taken as a group, the particle density ratio of the two areas in the area group is calculated, and the wafer corresponding to the wafer image is judged to be an abnormal product under the condition that the calculated particle density ratio is greater than a preset threshold. Therefore, on one hand, compared with the existing method for overlaying and observing the wafer, the detection method for calculating the particle density ratio of the two areas is easier to execute, can be applied to detection of all wafers, realizes full detection of all products and avoids the problem of missed detection, and on the other hand, the unified rule can be applied to automatic detection, so that manual detection is abandoned, subjective influence on detection is avoided, and the accuracy of wafer evaluation results is improved.
In one possible embodiment, dividing a plurality of regions in a wafer image includes:
dividing a plurality of areas in the wafer image from inside to outside;
among the two adjacent areas, the inner area is a first area, and the outer area is a second area.
In the embodiment of the present application, the area division in the wafer image is specifically divided from inside to outside, where for two adjacent areas, an inner area is a first area, and an outer area is a second area. It should be noted that the inside and outside concepts described in the embodiments of the present application are defined by the inside and outside of the wafer image itself, that is, the inside and outside refers to the direction from the center of the wafer image to the edge of the wafer image.
Further, dividing a plurality of regions from inside to outside on the wafer includes:
a plurality of annular regions with the same circle center are divided in the wafer image at equal intervals from inside to outside.
In the embodiment of the application, the area division in the wafer image is specifically to divide a plurality of annular areas with the same circle center at equal intervals from inside to outside, and accordingly, the first area and the second area are the inner circle area and the outer circle area in two adjacent areas.
The annular region division is adopted, the shape of the wafer and the production process are considered, the region is divided into the annular shape, the particle density in the region is more uniform, and the calculated particle density ratio is more accurate. Meanwhile, annular area division is adopted, so that annular COP can be checked out more conveniently.
For example, as shown in fig. 2, a ring-shaped area division from inside to outside is adopted for a wafer image; in the wafer image shown in fig. 2, a ring of obviously dense dots can be seen, which shows the case of the ring-shaped COP, and accordingly, the wafer image is divided into ring-shaped regions, which is more beneficial to find out the ring-shaped COP.
In one possible embodiment, calculating the particle density ratio of two regions of the set of regions comprises:
and calculating the particle density ratio of the second region to the first region in each region group in sequence from outside to inside.
In the embodiment of the present application, the particle density ratio calculation is sequentially performed on a plurality of region groups, specifically, the particle density ratio between the outer ring region (i.e., the second region) and the inner ring region (i.e., the first region) in each region group is calculated.
In one possible embodiment, the number of the plurality of regions is 5 to 15. An alternative number of zones is 10, as shown in figure 2.
The setting for the number of the above-described regions is considered based on the COP formation process, and in the prior art, as shown in fig. 3, single-crystal silicon prepared by the Magnetic Field Applied Czochralski Method (MCZ), that is, the MCZ Czochralski Method, has crystal defects such as crystal originated defects (COP), flow Pattern Defects (FPD), oxidation Induced Stacking Faults (OiSF), direct Surface Oxidation Defects (DSOD), and the like. The accumulation of these defects causes not only a breakdown voltage failure of the oxide film of the silicon substrate but also a PN junction leakage, a short circuit of the trench capacitor, or an insulation failure, and reduces the yield of the integrated circuit. Therefore, it is required to control the crystal quality in the point defect region by the temperature in the crystal pulling furnace and the crystal growth rate. Depending on the type of defects and the way of aggregation, the following crystal domains will be distinguished: vacancy defect accumulation region (v-rich), boundary (P-Band), vacancy point defect region (Pv), interstitial point defect region (Pi) and interstitial defect accumulation region (i-rich). Since there are many different crystal defects, at least five or more divisions are set when the region needs to be set.
As shown in fig. 4, while the formation of cyclic COP results from the boundary between liquid and solid during crystal production, the distribution of the radius of the ring is statistically not more than 10mm wide, as shown in fig. 5, which is a total of 5000 pieces of cyclic COP samples. Therefore, in order to cover all cases, the maximum number of the ring partitions can be set to be 15 for a 300 mm-sized wafer, and the minimum partition ring radius is guaranteed to be 10mm.
In one possible embodiment, the preset threshold is 3.5 to 4.5. An alternative preset threshold is 4.0.
Aiming at the setting of the preset threshold, the same sample as the previous circular ring radius in the statistical timing is selected, and the area with the partition quantity of 10 is selected for the partition and marked as the area 1-10 from inside to outside. The number of particles in the ring COP region and the regions before and after the ring COP region was counted, and it was found that the number of particles was not significantly characterized, as shown in fig. 6. Secondly, ratio analysis is carried out on the ring-shaped COP, and the ratio of the ring-shaped COP to the adjacent area is mostly distributed to be more than 4.0, so that the preset threshold recommended value is 3.5-4.5 as shown in the following figures 7 and 8. In order to more accurately distinguish the annular COP, the ratio of the COP area to the inner ring and the ratio of the COP area to the outer ring are counted, the COP area is found to be more accurate about 4.0, the ratio of the COP area to the inner ring which is more than 4.0 can reach more than 95%, and the COP area is found to be more accurate when the preset threshold is 4.0.
The embodiment of the present application further provides a wafer evaluation apparatus, which may be an apparatus that is independently arranged, or a functional apparatus that is additionally arranged in an existing system, and this is not specifically limited in the embodiment of the present application.
The device comprises:
the acquisition module is used for acquiring a wafer image;
the dividing module is used for dividing a plurality of areas in the wafer image;
the first determining module is used for determining a plurality of area groups in a plurality of areas according to the fact that two adjacent areas form a group;
a calculation module for calculating a particle density ratio of two regions in the set of regions;
and the second determining module is used for determining that the wafer corresponding to the wafer image is an abnormal product under the condition that the calculated particle density ratio is greater than a preset threshold.
Optionally, the dividing module is specifically configured to:
dividing a plurality of areas in the wafer image from inside to outside;
in the two adjacent areas, the inner area is a first area, and the outer area is a second area.
Optionally, the dividing module is specifically configured to:
and dividing a plurality of annular regions with the same circle center at equal intervals from inside to outside in the wafer image.
Optionally, the calculation module is specifically configured to:
and calculating the particle density ratio of the second region to the first region in each region group in sequence from outside to inside.
Optionally, the number of the plurality of regions is 5 to 15.
Optionally, the preset threshold is 3.5 to 4.5.
It should be noted that the above-mentioned module division may be a specific independently-arranged hardware module, or may also be a virtual module integrated together, which is not specifically limited in this embodiment of the present application.
The embodiment of the present application further provides a readable storage medium, where a program or an instruction is stored on the readable storage medium, and when the program or the instruction is executed by a processor, the program or the instruction implements each process of the wafer evaluation method embodiment, and can achieve the same technical effect, and in order to avoid repetition, details are not repeated here.
Wherein, the processor is the processor in the terminal described in the above embodiment. The readable storage medium includes a computer readable storage medium, such as a computer read only memory ROM, a random access memory RAM, a magnetic or optical disk, and the like.
While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (9)
1. A method of evaluating a wafer, comprising:
acquiring a wafer image;
dividing a plurality of areas in the wafer image;
determining a plurality of area groups in the plurality of areas according to the fact that two adjacent areas form a group;
calculating a particle density ratio of two regions in the set of regions;
and determining that the wafer corresponding to the wafer image is an abnormal product under the condition that the calculated particle density ratio is greater than a preset threshold.
2. The method of claim 1, wherein the dividing the plurality of regions in the wafer image comprises:
and dividing a plurality of annular areas with the same circle center in the wafer image at equal intervals from inside to outside.
3. The method of claim 1, wherein the plurality of regions is 5 to 15 in number.
4. The method of claim 1, wherein the predetermined threshold is 3.5 to 4.5.
5. A wafer evaluation apparatus, comprising:
the acquisition module is used for acquiring a wafer image;
the dividing module is used for dividing a plurality of areas in the wafer image;
the first determining module is used for determining a plurality of area groups in the plurality of areas according to the condition that two adjacent areas form a group;
a calculation module for calculating a particle density ratio of two regions in the set of regions;
and the second determining module is used for determining that the wafer corresponding to the wafer image is an abnormal product under the condition that the calculated particle density ratio is greater than a preset threshold.
6. The apparatus according to claim 5, wherein the partitioning module is specifically configured to:
and dividing a plurality of annular areas with the same circle center in the wafer image at equal intervals from inside to outside.
7. The apparatus of claim 5, wherein the plurality of regions is 5 to 15 in number.
8. The apparatus of claim 5, wherein the preset threshold is 3.5 to 4.5.
9. A readable storage medium, on which a program or instructions are stored which, when executed by a processor, carry out the steps of the wafer evaluation method of any one of claims 1 to 4.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211657812.4A CN115798558A (en) | 2022-12-22 | 2022-12-22 | Wafer evaluation method, apparatus and readable storage medium |
| TW112105000A TWI823774B (en) | 2022-12-22 | 2023-02-13 | Wafer evaluation method, device and readable storage medium |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211657812.4A CN115798558A (en) | 2022-12-22 | 2022-12-22 | Wafer evaluation method, apparatus and readable storage medium |
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| CN115798558A true CN115798558A (en) | 2023-03-14 |
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| US8173449B2 (en) * | 2006-06-09 | 2012-05-08 | Sumco Corporation | Method for making COP evaluation on single-crystal silicon wafer |
| JP5029514B2 (en) * | 2008-07-02 | 2012-09-19 | 株式会社Ｓｕｍｃｏ | Method for determining COP generation factor of single crystal silicon wafer |
| JP5782782B2 (en) * | 2011-03-30 | 2015-09-24 | 株式会社Sumco | Specific defect detection method, specific defect detection system and program |
| JP6000839B2 (en) * | 2012-12-21 | 2016-10-05 | メルクパフォーマンスマテリアルズマニュファクチャリング合同会社 | Composite of silicon oxide nanoparticles and silsesquioxane polymer, method for producing the same, and composite material produced using the composite |
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Address after: 710000 room 1-3-029, No. 1888, Xifeng South Road, high tech Zone, Xi'an, Shaanxi Province Applicant after: Xi'an Yisiwei Material Technology Co.,Ltd. Applicant after: XI'AN ESWIN SILICON WAFER TECHNOLOGY Co.,Ltd. Address before: 710000 room 1-3-029, No. 1888, Xifeng South Road, high tech Zone, Xi'an, Shaanxi Province Applicant before: Xi'an yisiwei Material Technology Co.,Ltd. Applicant before: XI'AN ESWIN SILICON WAFER TECHNOLOGY Co.,Ltd. |