CN109727887B - Wafer edge defect monitoring method - Google Patents
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- CN109727887B CN109727887B CN201811632588.7A CN201811632588A CN109727887B CN 109727887 B CN109727887 B CN 109727887B CN 201811632588 A CN201811632588 A CN 201811632588A CN 109727887 B CN109727887 B CN 109727887B
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Abstract
The invention discloses a wafer edge defect monitoring method, which comprises the following steps: collecting characteristic parameters formed by digitalizing scanning photos of the edge defects of the known wafer and adding the characteristic parameters of the edge defects of various wafers into a defect database; secondly, scanning the edge of the monitored wafer, taking a picture and forming a scanning picture; picking out various crystal edge defects from the scanned photos of the monitored wafer, digitizing and obtaining corresponding characteristic parameters; and step four, subtracting the characteristic parameters of the various crystal edge defects corresponding to the monitored wafer from the characteristic parameters in the defect database, and determining the types of the various crystal edge defects corresponding to the monitored wafer according to the subtraction value. The invention can realize comprehensive real-time monitoring on various known and newly-appeared unknown defects, eliminate the monitoring blind spots on the unknown defects, eliminate the influence on the product caused by the monitoring blind spots and improve the quality of the product.
Description
Technical Field
The present invention relates to a method for manufacturing a semiconductor integrated circuit, and more particularly, to a method for monitoring edge defects of a wafer.
Background
Semiconductor integrated circuits are generally formed on wafers, which are generally silicon substrate wafers, and as technology develops, the size of the wafer, i.e., the diameter, is from 4 inches, 6 inches, 8 inches to 12 inches, in the production process of the wafer, e.g., 12 inch wafer, as the process is continuously reduced and the process is continuously optimized, more new kinds of edge defects are generated in the process, the edge defects are defects at the edge of the wafer, once the edge defects such as film peeling and the like fall into effective devices in the process, yield loss is caused, the effective devices are devices in the chip forming area inside the edge of the wafer, and the devices at the edge of the wafer are finally removed. Therefore, an on-line effective edge defect monitoring method must be established. However, due to the difference of the lithography edge-cleaning distances and the increase of the growth levels of the thin films in different processes and the different degrees of contact between the wafer edge and the machine parts in different processes, the wafer edge has a large noise in the defect measurement process.
In the prior art, the monitoring mode of the wafer edge defect is as follows: the method comprises the steps of scanning the edge of a wafer, namely, scanning the edge of the wafer to obtain a wafer edge photo, scanning the edge of the wafer through a defect detection machine, selecting required special defects from the obtained photo, establishing a wafer edge scanning program aiming at the characteristic defects through parameter selection and continuous adjustment, and continuously monitoring the special defects, namely the known defects on line after the wafer edge scanning program is established.
In the existing method, a corresponding wafer edge scanning program is required to be established for each type of defect, the defects without the corresponding wafer edge scanning program cannot be monitored on line, the existing wafer edge monitoring method has directionality, namely, the existing defects can be monitored only aiming at the known defects, however, for the unknown new type of wafer edge defects, the existing monitoring method cannot be found at the first time, and certain delay exists in the aspect of timeliness.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a method for monitoring the crystal edge defects of the wafer, which can realize comprehensive real-time monitoring on various known and newly-appeared unknown defects, eliminate the monitoring blind spots on the unknown defects, eliminate the influence on the product caused by the monitoring blind spots and improve the quality of the product.
In order to solve the above technical problem, the method for monitoring the edge defects of the wafer provided by the invention comprises the following steps:
step one, collecting characteristic parameters of the crystal edge defects of the known type of wafers, wherein the characteristic parameters are formed by scanning and photographing the corresponding crystal edge defects of the edges of the wafers and digitizing pictures of the crystal edge defects in the scanned pictures, and adding the known characteristic parameters of all the types of the crystal edge defects into a defect database.
And step two, scanning the edge of the monitored wafer, taking a picture and forming a scanning picture.
And thirdly, picking out various crystal edge defects from the scanned photos of the monitored wafer, digitizing the photos of the various crystal edge defects and obtaining corresponding characteristic parameters.
And fourthly, carrying out subtraction on the characteristic parameters of the various crystal edge defects corresponding to the monitored wafer and the characteristic parameters of the various crystal edge defects in the defect database, and determining the types of the various crystal edge defects corresponding to the monitored wafer according to subtraction values.
A further improvement is that, in the fourth step, if a subtraction value between the characteristic parameter of one of the edge defects corresponding to the monitored wafer and the characteristic parameter of one of the edge defects in the defect database is less than or equal to a comparison threshold, it is determined that the type of the edge defect corresponding to the monitored wafer is a known type.
A further improvement is that, in the fourth step, if the difference between the characteristic parameter of one of the edge defects corresponding to the monitored wafer and the characteristic parameters of all types of edge defects in the defect database is greater than the comparison threshold, it is determined that the type of the edge defect corresponding to the monitored wafer is the new type.
In a further improvement, the characteristic parameters of the new type of edge defects corresponding to the monitored wafer are added to the defect database.
In a further refinement, the wafers are 6 inches, 8 inches, and 12 inches or more in diameter.
In a further improvement, the edge defects include defects formed by peeling of the film.
In a further improvement, the types of the peeled films corresponding to the edge defects include: dielectric film, metal film, photoresist.
In a further refinement, step two includes scanning a top surface, a side surface, and a bottom surface of the edge of the monitored wafer, respectively.
In a further improvement, the characteristic parameters of the edge defects include shape, area and bright spots.
In a further improvement, after the photograph of the edge defect is digitized, local left-right difference reduction is needed to realize background weakening.
In a further improvement, the inside of the edge of the wafer is a chip forming area.
A further improvement is that, when the edge defects are detected in the fourth step and the number of the edge defects is greater than or equal to the required value, the monitored wafer is cleaned to remove the edge defects.
And when the edge defects are detected in the fourth step and the number of the edge defects is smaller than the required value, carrying out the next process on the monitored wafer.
A further improvement is that when the edge defects are detected in the fourth step and the number of the edge defects is greater than or equal to the required value, the machine corresponding to the last process of the monitored wafer needs to be inspected.
In a further refinement, the monitored wafers are production wafers.
The further improvement is that in the step one, the defect detection machine is adopted to scan and photograph the corresponding edge defects of the wafer.
And in the second step, the edge of the monitored wafer is scanned and photographed by adopting the defect detection machine.
Firstly, collecting characteristic parameters of various known types of wafer edge defects and forming a defect database, wherein the characteristic parameters are formed by digitalizing photos of the various known types of wafer edge defects, so that the monitored wafer is not required to be scanned by adopting a wafer edge scanning program corresponding to one or more known wafer edge defects in the subsequent monitoring, but a universal or known wafer edge scanning program is adopted to carry out edge scanning on the monitored wafer, then, the scanned photos are digitally converted to obtain corresponding characteristic parameters, and the types of the wafer edge defects of the monitored wafer can be determined by carrying out subtraction calculation and comparison on the scanned photos and the characteristic parameters in the defect database, wherein the types of the wafer edge defects of the monitored wafer can be determined no matter the wafer edge defects are known or unknown; for new unknown crystal edge defects, the obtained characteristic parameters can be added into a defect database in time; therefore, the method can realize comprehensive real-time monitoring on various known and newly-appeared unknown defects, eliminate the monitoring blind spots on the unknown defects, eliminate the influence on the product caused by the monitoring blind spots and improve the quality of the product.
In addition, in the prior art, one type of edge scanning program can only detect corresponding known types of edge defects, and different edge defects need different edge scanning programs.
Drawings
The invention is described in further detail below with reference to the following figures and detailed description:
FIG. 1 is a flowchart illustrating a method for monitoring edge defects of a wafer according to an embodiment of the present invention;
FIG. 2 is a schematic diagram illustrating a wafer being scanned according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of the digital processing of the edge defects in the method according to the embodiment of the invention.
Detailed Description
As shown in fig. 1, which is a flowchart of a method for monitoring a crystal edge defect 1 of a wafer 101 according to an embodiment of the present invention, the method for monitoring a crystal edge defect 1 of a wafer 101 according to an embodiment of the present invention includes the following steps:
firstly, collecting characteristic parameters of the edge defect 1 of the wafer 101 of a known type, wherein the characteristic parameters are formed by scanning and photographing the edge defect 1 of the edge of the wafer 101 correspondingly and digitizing the picture of the edge defect 1 in the scanned picture, and adding the known characteristic parameters of the edge defect 1 of all types into a defect database.
Preferably, scanning and photographing corresponding edge defects 1 of the edge of the wafer 101 are performed by using a defect detection machine. When collecting the characteristic parameters of the edge defects 1 of various known types, scanning photos formed in the previous testing process can be adopted, and scanning photographing can be independently carried out for collection, so that convenience is brought to the user.
As shown in fig. 2, which is a schematic diagram of scanning a wafer 101 in the method according to the embodiment of the present invention, a circle indicated by a mark 102 in the wafer 101 is an inner circle of an edge of the wafer 101, and an outer circle of the edge is an outermost periphery of the wafer 101. The inner part of the edge of the wafer 101, that is, the inner part of the circle 102, is a chip forming area, and all devices in the chip forming area are useful devices and are required to be not damaged by the crystal edge defect 1.
The wafer 101 is 6 inches, 8 inches, and 12 inches or more in diameter.
The edge defects 1 include defects formed by peeling of a thin film.
The types of the peeled films corresponding to the edge defects 1 comprise: dielectric film, metal film, photoresist.
The characteristic parameters of the crystal edge defect 1 comprise shape, area and bright spot.
After the photo of the edge defect 1 is digitized, local left-right difference reduction is needed to realize background weakening.
As shown in fig. 3, which is a schematic diagram of performing digital processing on the edge defect 1 in the method according to the embodiment of the present invention, a diagram corresponding to the mark 301 is a scanned photograph corresponding to the edge defect 1; the graph corresponding to the mark 302 is digital information on each position formed after digitization, the number is related to the characteristics of the corresponding position, such as brightness, and the 5 numbers corresponding to the mark 201 in the graph 302 correspond to the edge defect 1; the reference numeral 303 is digital information obtained by performing background processing on the graph in the reference numeral 302, the background processing is obtained by locally subtracting the left and right differences from the digital information in the graph 302, and 32 is subtracted from the graph 302 in the graph 303.
And step two, scanning the edge of the monitored wafer 101, taking a picture and forming a scanning photo.
Preferably, the defect inspection machine is used to scan the edge of the monitored wafer 101 and take a picture of the edge.
Step two includes scanning the top surface, the side surface, and the bottom surface of the edge of the monitored wafer 101, respectively.
The monitored wafer 101 is typically a production wafer 101.
And thirdly, picking out various edge defects 1 from the scanned photos of the monitored wafer 101, digitizing the photos of the various edge defects 1 and obtaining corresponding characteristic parameters.
And fourthly, subtracting the characteristic parameters of the various edge defects 1 corresponding to the monitored wafer 101 from the characteristic parameters of the various edge defects 1 in the defect database, and determining the types of the various edge defects 1 corresponding to the monitored wafer 101 according to a subtraction value.
In the embodiment of the present invention, if a subtraction value between a characteristic parameter of one edge defect 1 of the edge defects 1 corresponding to the monitored wafer 101 and a characteristic parameter of one edge defect 1 of the defect database is less than or equal to a comparison threshold, it is determined that the type of the edge defect 1 corresponding to the monitored wafer 101 is a known type.
In the fourth step, if the difference between the characteristic parameter of one edge defect 1 of the edge defects 1 corresponding to the monitored wafer 101 and the characteristic parameters of all types of edge defects 1 in the defect database is greater than the comparison threshold, it is determined that the type of the edge defect 1 corresponding to the monitored wafer 101 is the new type. At this time, the characteristic parameters of the new type of edge defects 1 corresponding to the monitored wafer 101 need to be added to the defect database.
And when the edge defects 1 are detected in the fourth step and the number of the edge defects 1 is greater than or equal to the required value, cleaning the monitored wafer 101 to remove the edge defects 1. Usually, the reason for exceeding is possibly caused by the previous process when the number of the edge defects 1 exceeds the standard, so that when the edge defects 1 are detected in the fourth step and the number of the edge defects 1 is greater than or equal to the required value, the machine corresponding to the previous process of the monitored wafer 101 needs to be inspected.
And when the edge defects 1 are detected in the fourth step and the number of the edge defects 1 is smaller than the required value, performing the next process on the monitored wafer 101.
In the embodiment of the invention, firstly, characteristic parameters of various known types of wafer edge defects 1 are collected and a defect database is formed, the characteristic parameters are formed by digitalizing photos of the various known types of wafer edge defects 1, so that the monitored wafer 101 is not required to be scanned by adopting a wafer edge scanning program corresponding to one or more known wafer edge defects 1 in the subsequent monitoring, but a universal or known wafer edge scanning program is adopted to carry out edge scanning on the monitored wafer 101, then, the scanned photos are digitally converted to obtain corresponding characteristic parameters, and the types of the wafer edge defects 1 of the monitored wafer 101 can be determined by carrying out subtraction calculation and comparison with the characteristic parameters in the defect database, wherein the types of the wafer edge defects 1 can be determined no matter whether the wafer edge defects 1 are known or the wafer edge defects 1 are unknown; for the new unknown crystal edge defect 1, the obtained characteristic parameters can be added into a defect database in time; therefore, the method can realize comprehensive real-time monitoring on various known and newly-appeared unknown defects, eliminate the monitoring blind spots on the unknown defects, eliminate the influence on the product caused by the monitoring blind spots and improve the quality of the product.
In addition, in the prior art, one type of edge scanning program can only detect corresponding known types of edge defects 1, and different edge defects 1 need different edge scanning programs, compared with the directional detection in the prior art, the embodiment of the invention can detect various types of edge defects 1 by one-time scanning, and does not need to adjust the parameters of the edge scanning program for the new type of edge defects 1, so that the embodiment of the invention can also improve the testing efficiency and reduce the testing cost.
The present invention has been described in detail with reference to the specific embodiments, but these should not be construed as limitations of the present invention. Many variations and modifications may be made by one of ordinary skill in the art without departing from the principles of the present invention, which should also be considered as within the scope of the present invention.
Claims (15)
1. A method for monitoring the edge defects of a wafer is characterized by comprising the following steps:
step one, collecting characteristic parameters of the crystal edge defects of the known type of wafers, wherein the characteristic parameters are formed by scanning and photographing the crystal edge defects of the edges of the corresponding wafers and digitizing the pictures of the crystal edge defects in the scanned pictures, and adding the known characteristic parameters of all the types of the crystal edge defects into a defect database; the graph is formed after the photos of the crystal edge defects are digitized, and digital information formed by digitizing the characteristics of the positions corresponding to the photos of the crystal edge defects is formed on each position of the graph;
secondly, scanning the edge of the monitored wafer, taking a picture and forming a scanning picture;
picking out various crystal edge defects from the scanned photos of the monitored wafer, digitizing the photos of the various crystal edge defects and obtaining corresponding characteristic parameters;
and fourthly, carrying out subtraction on the characteristic parameters of the various crystal edge defects corresponding to the monitored wafer and the characteristic parameters of the various crystal edge defects in the defect database, and determining the types of the various crystal edge defects corresponding to the monitored wafer according to subtraction values.
2. The method for monitoring the edge defects of the wafer according to claim 1, wherein:
in the fourth step, if the subtraction value of the characteristic parameter of one of the edge defects corresponding to the monitored wafer and the characteristic parameter of one of the edge defects in the defect database is less than or equal to the comparison threshold, it is determined that the type of the edge defect corresponding to the monitored wafer is the known type.
3. The method for monitoring the edge defects of the wafer according to claim 1, wherein:
in the fourth step, if the subtraction value of the characteristic parameter of one of the edge defects corresponding to the monitored wafer and the characteristic parameters of all types of edge defects in the defect database is greater than the comparison threshold, it is determined that the type of the edge defect corresponding to the monitored wafer is a new type.
4. The method for monitoring the edge defects of the wafer according to claim 3, wherein: and adding the characteristic parameters of the new types of crystal edge defects corresponding to the monitored wafer into the defect database.
5. The method for monitoring the edge defects of the wafer according to claim 1, wherein: the wafers are 6 inches, 8 inches, and 12 inches or more in diameter.
6. The method for monitoring the edge defects of the wafer according to claim 1, wherein: the edge defects include defects formed by peeling of the film.
7. The method for monitoring the edge defects of the wafer according to claim 6, wherein: the types of the peeled films corresponding to the edge defects comprise: dielectric film, metal film, photoresist.
8. The method for monitoring the edge defects of the wafer according to claim 1, wherein: and the second step comprises respectively scanning the top surface, the side surface and the bottom surface of the edge of the monitored wafer.
9. The method for monitoring the edge defects of the wafer according to claim 1, wherein: the characteristic parameters of the crystal edge defect comprise shape, area and bright spot.
10. The method for monitoring the edge defects of the wafer according to claim 1, wherein: after the photos of the crystal edge defects are digitized, local left-right difference reduction is needed to realize background weakening.
11. The method for monitoring the edge defects of the wafer according to claim 1, wherein: and a chip forming area is arranged inside the edge of the wafer.
12. The method for monitoring the edge defects of the wafer according to claim 11, wherein: when the wafer edge defects are detected in the fourth step and the number of the wafer edge defects is larger than or equal to the required value, cleaning the monitored wafer to remove the wafer edge defects;
and when the edge defects are detected in the fourth step and the number of the edge defects is smaller than the required value, carrying out the next process on the monitored wafer.
13. The method for monitoring the edge defects of the wafer according to claim 12, wherein: and when the edge defects are detected in the fourth step and the number of the edge defects is greater than or equal to the required value, checking a machine corresponding to the last step of the monitored wafer.
14. The method for monitoring the edge defects of the wafer according to claim 12, wherein: the monitored wafer is a product wafer.
15. The method for monitoring the edge defects of the wafer according to claim 1, wherein:
scanning and photographing corresponding edge defects of the wafer edge by adopting a defect detection machine;
and in the second step, the edge of the monitored wafer is scanned and photographed by adopting the defect detection machine.
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| JP2004257826A (en) * | 2003-02-25 | 2004-09-16 | Matsushita Electric Works Ltd | Visual examination method using color image and visual examination device |
| CN104282587A (en) * | 2013-07-03 | 2015-01-14 | 中芯国际集成电路制造(上海)有限公司 | Method for detecting edge defect of wafer |
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| CN107590511A (en) * | 2017-08-30 | 2018-01-16 | 武汉华星光电技术有限公司 | A kind of defect identification method and identifying system the defects of for automatic check machine |
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| CN102982155A (en) * | 2012-11-29 | 2013-03-20 | 上海华力微电子有限公司 | System and method for searching defects based on pattern identification |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004257826A (en) * | 2003-02-25 | 2004-09-16 | Matsushita Electric Works Ltd | Visual examination method using color image and visual examination device |
| CN104282587A (en) * | 2013-07-03 | 2015-01-14 | 中芯国际集成电路制造(上海)有限公司 | Method for detecting edge defect of wafer |
| CN107275245A (en) * | 2017-05-22 | 2017-10-20 | 茆胜 | A kind of OLED minitype displayer Rapid checking device and its method for quickly detecting |
| CN107590511A (en) * | 2017-08-30 | 2018-01-16 | 武汉华星光电技术有限公司 | A kind of defect identification method and identifying system the defects of for automatic check machine |
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