Method and system for acquiring source of dead pixel on back of crystal

Abstract

The invention provides a method and a system for acquiring a source of a dead pixel on a wafer back, and belongs to the field of semiconductors. The method for obtaining the source of the wafer back dead pixel comprises the following steps: obtaining wafer back information of a wafer obtained by each operation machine and a target dead pixel feature map of each photoetching layer; and comparing the target dead pixel feature map with the wafer back information collected in each step of the previous layer, and screening out image information conforming to the dead pixel feature map. And based on the screened image information conforming to the defective pixel feature map and the wafer back information of each operation machine, locking the machine generating the defective pixel. The method comprises the following steps: firstly, obtaining wafer back information of a wafer and a target dead pixel feature pattern of each photoetching layer; and then, screening out image information conforming to the defective pixel feature map. And finally, locking the machine with the dead pixels. According to the method, the front-layer source of the dead pixel can be efficiently traced, the existing source checking time is shortened, the existing tracing workload is reduced, and the existing comparison difficulty is also reduced.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a method and system for obtaining a source of a wafer backside bad point. Background Art

[0002] As semiconductor development enters more advanced process research and development, the degree of back-end defects has an increasingly greater impact on the final molding requirements of the device, and back-end defects come from a certain link in the complex process flow. For photolithography, the presence of back-end particles will affect exposure molding, and severe cases will cause defocusing of the pattern, resulting in defects, which are called bad pixels. Currently, the effective method for detecting back-end particles is visual inspection or optical inspection. The inspection requires special human processing and scanning with a back-end inspection program to obtain a back-end defect image. Because the inspection site is single, it is difficult to trace the source of the bad pixel, and it is difficult to find the source based on the inspection results of a single step.

[0003] It should be noted that the information disclosed in the background technology section of the invention is only intended to deepen the understanding of the general background technology of the invention, and should not be regarded as an admission or suggestion in any form that the information constitutes prior art already known to those skilled in the art. Summary of the invention

[0004] The object of the present invention is to provide a method and system for obtaining the source of wafer backside bad pixels, so as to solve the problem that the machine generating the bad pixels cannot be traced back to the source.

[0005] In order to solve the above technical problems, the present invention provides a method for obtaining the source of the wafer back bad point, comprising:

[0006] Obtain the backside information of each wafer passed by the operating machine, as well as the target bad pixel feature map of each lithography layer;

[0007] Compare the target bad pixel feature map with the backside information collected in each step of the previous layer, and filter out image information that meets the bad pixel feature map;

[0008] Based on the image information that matches the bad pixel feature map and the backside information of each operating machine, the machine that produces the bad pixel is locked.

[0009] Preferably, obtaining the backside information of each wafer passed by the machine includes:

[0010] Obtain image information of the backside of each wafer after each process step;

[0011] Stacking the wafer back image information of all wafers in each batch to serve as the wafer back information of the wafer in the batch;

[0012] The backside information of all batches of wafers is counted by machine, and the backside information of the wafers obtained by each operating machine is obtained.

[0013] Preferably, the wafer backside information includes the coordinates and size of the bad spot, wherein the size of the bad spot is the height of the bad spot protruding upwards with the plane where the wafer is located as the horizontal plane.

[0014] Preferably, the wafer back information is used to characterize the frequency of occurrence of bad pixels.

[0015] Preferably, the area where bad pixels appear is called an abnormal area, and the frequency of occurrence of bad pixels is represented by the depth of color. The more bad pixels appear in the abnormal area, the darker the color of the abnormal area.

[0016] Preferably, obtaining a target bad pixel characteristic map of each photolithography layer includes:

[0017] Each batch of wafers is lithographically processed by an etching machine, and the bad pixel information of the etched wafers is counted to obtain a bad pixel feature map corresponding to each batch of wafers;

[0018] All batches of bad pixel feature maps obtained from each etching layer are stacked to obtain a target bad pixel feature map for the photolithography layer.

[0019] Preferably, collecting statistics on bad pixel information of the batch of etched wafers includes:

[0020] Statistics are collected on the coordinates, size, and percentage distribution of bad pixels in the bad pixel feature map.

[0021] Preferably, collecting statistics on bad pixel information of the batch of etched wafers further includes:

[0022] Obtain the distribution characteristics of bad pixels on the wafer to obtain the feature map radius, the distribution of bad pixels in the wafer radius, and the proportion of each distribution interval.

[0023] Preferably, comparing the target bad pixel feature map with the backside information collected in each step of the previous layer includes:

[0024] Compare the position of the bad pixel in the target bad pixel feature map with the position of the bad pixel in the wafer back information.

[0025] Based on the same inventive concept, the present invention also provides a system for obtaining the source of the backside bad point of the wafer, comprising:

[0026] The acquisition module is used to obtain the backside information of each wafer passed by the operating machine, as well as the target bad pixel feature map of each photolithography layer;

[0027] A comparison module is used to compare the target bad pixel feature map with the backside information collected in each step of the previous layer, and filter out image information that meets the bad pixel feature map;

[0028] The locking module is used to lock the machine that produces the bad pixel based on the image information that is screened out and conforms to the bad pixel feature map and the wafer back information of each operating machine.

[0029] Compared with the prior art, the method for obtaining the source of wafer backside bad spots of the present invention has the following advantages:

[0030] The method for obtaining the source of the backside bad spots provided by the present invention first obtains the backside information of the wafer and the target bad spot feature map of each photolithography layer. Then, the target bad spot feature map is compared with the backside information collected in each step of the previous layer, and the image information that meets the bad spot feature map is screened out. Finally, the machine that produces the bad spot can be locked by the screened image information that meets the bad spot feature map and the backside information of each operating machine. Not only can the front-layer source of the bad spot be traced back efficiently, the existing time for troubleshooting the source can be shortened, the existing tracing workload can be reduced, and the difficulty of the existing comparison can be reduced.

[0031] The system for obtaining the source of the backside bad point provided by the present invention and the method for obtaining the source of the backside bad point provided by the present invention belong to the same inventive concept. Therefore, the system for obtaining the source of the backside bad point provided by the present invention at least has all the advantages of the method for obtaining the source of the backside bad point provided by the present invention, and can lock the machine that produces the bad point. Not only can the front-layer source of the bad point be efficiently traced, the time for existing source investigation can be shortened, the workload of existing tracing can be reduced, and the difficulty of existing comparison can also be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a flow chart of a method for obtaining a source of a wafer backside bad point provided in one embodiment of the present invention;

[0033] Figure 2 It is a schematic diagram of a method for obtaining a source of a bad spot on the back of a wafer provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, advantages and features of the present invention clearer, the method and system for obtaining the source of the backside bad point proposed by the present invention are further described in detail in combination with the drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. It should be understood that the drawings in the specification do not necessarily show the specific structure of the present invention in proportion, and the illustrative features used to illustrate certain principles of the present invention in the drawings in the specification will also adopt a slightly simplified drawing method. The specific design features of the present invention disclosed herein include, for example, specific dimensions, directions, positions and shapes, which will be determined in part by the specific application and use environment. And, in the embodiments described below, sometimes the same figure mark is used in common between different drawings to represent the same part or a part with the same function, and its repeated description is omitted. In this specification, similar numbers and letters are used to represent similar items, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0035] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0036] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0037] The core idea of ​​the present invention is to provide a method and system for obtaining the source of the bad pixel on the back of the wafer, which can solve the problem that the machine that produces the bad pixel cannot be traced back to the source.

[0038] In order to realize the above idea, the present invention provides a method for obtaining the source of the backside bad point of the wafer. Figure 1 and Figure 2 A specific implementation of the disclosed method for obtaining the source of the wafer backside bad pixel includes the following steps S1 to S4.

[0039] Step S1: Obtain backside information of each wafer passed through a processing machine.

[0040] Specifically, refer to Figure 1 and Figure 2 As shown, obtaining the backside information of each wafer passed by the machine includes:

[0041] First, obtain the image information of the back of each wafer after each process step. Use a scanner to collect the electronic signal of the back of each wafer after each process step, convert the electronic signal into a digital signal through a simulator, and use the digital signal to represent the image information of the back of each wafer. Figure 2 As shown, step 1 (the first step), after the first step process is completed, a scanner is used to collect electronic signals from the back of each wafer after the first step process is completed, the electronic signals are converted into digital signals through a simulator, and the digital signals are used to represent the back image information of each wafer. Similarly, for step 2, step 3...step N (where N is an integer greater than or equal to 1), a scanner is used to collect electronic signals from the back of each wafer after each step process is completed, the electronic signals are converted into digital signals through a simulator, and the digital signals are used to represent the back image information of each wafer.

[0042] The image information of the back of the wafer includes the coordinates and size of the bad pixel. The size of the bad pixel refers to the height of the bad pixel protruding upward with the plane where the wafer is located as the horizontal plane. The image information of the back of the wafer can also characterize the frequency of bad pixel occurrence. For example, the area where the bad pixel appears can be called the abnormal area, and the frequency of bad pixel occurrence can be characterized by the depth of color. The more bad pixels appear in the abnormal area, the darker the color of the abnormal area. For example, engineers can define red as dark color and green or white as light color. Engineers can change the depth of color through the system. When engineers find that a certain area on the back of the wafer is red, they can preliminarily judge that the frequency of bad pixels in this area is high.

[0043] Next, the back image information of all wafers in each batch is stacked to serve as the back information of the wafers in the batch. Each batch of wafers is taken as a lot. A lot is 25 wafers. That is, every 25 wafers are regarded as a batch. The back image information of all wafers in each lot is stacked to serve as the back information of a working lot.

[0044] Finally, the backside information of all batches is counted by machine, and the backside information of the wafers obtained by each operating machine is obtained. The backside information of all lots is counted by machine, and the backside information of each operating machine is obtained.

[0045] Step S2: Obtain a target bad pixel feature map of each photolithography layer.

[0046] Specifically, refer to Figure 1 and Figure 2 As shown, obtaining a bad pixel feature map of each lithography layer includes:

[0047] First, each batch of wafers is lithographically processed by an etching machine, and the bad pixel information of the etched wafers is counted to obtain the bad pixel feature map corresponding to each batch of wafers. Each lot of wafers is lithographically processed by a photolithography machine. After the lithography is completed, the bad pixel information of each batch after the photolithography machine is completed is counted to obtain the bad pixel feature map of each lot. Figure 2 As shown, for example, after a lot of wafers are lithographically processed by photolithography machine 1, the bad pixel information of the wafers after etching of the batch is counted, and the bad pixel feature map corresponding to each batch of wafers is obtained. Similarly, for photolithography machine 2, photolithography machine 3 to photolithography machine M (where M is an integer greater than or equal to 1), after a lot of wafers are lithographically processed by the corresponding photolithography machine, the bad pixel information of the wafers after etching of the batch is counted, and the bad pixel feature map corresponding to each lot of wafers is obtained.

[0048] The statistics of bad pixel information of the batch of etched wafers include statistics of the coordinates, sizes and proportion of the bad pixel sizes in the bad pixel feature map.

[0049] As for the size of the bad pixel, the height of the bad pixel protruding upward is the size of the bad pixel, with the plane where the wafer is located as the horizontal plane.

[0050] The statistical analysis of the bad pixel information of the batch of etched wafers also includes obtaining the distribution characteristics of the bad pixels on the wafer to obtain the characteristic map radius. That is, obtaining the wafer radius on which the characteristic map radius is located. Thus, it is possible to obtain the value of the radius of the wafer backside when the number of bad pixels is large, thereby providing data for obtaining the source of the bad pixels on the wafer backside.

[0051] The bad pixel information statistics of the wafer include the distribution of bad pixels within the wafer radius and the percentage of bad pixels in each distribution interval.

[0052] Next, all batches of bad pixel feature maps obtained for each etched layer are stacked to obtain a target bad pixel feature map for the photolithography layer.

[0053] Step S3: Compare the target bad pixel feature map with the backside information collected in each step of the previous layer, and filter out image information that meets the bad pixel feature map.

[0054] Specifically, refer to Figure 1 and Figure 2As shown, the target bad pixel feature map obtained in step S2 is compared with the backside information collected in each step of the previous layer to filter out image information that meets the bad pixel feature map. When the target bad pixel feature map is compared with the backside information collected in each step of the previous layer, the position of the bad pixel in the target bad pixel feature map is compared with the position of the bad pixel in the backside information.

[0055] Step S4: Based on the image information that is screened out and conforms to the bad pixel feature map and the wafer back information of each operating machine, the machine that generates the bad pixel is locked.

[0056] Specifically, refer to Figure 1 and Figure 2 As shown, based on the image information that matches the bad pixel feature map and the backside information of each operating machine, the machine that produces the bad pixel can be locked. It should be noted that based on the image information that matches the bad pixel feature map and the backside information of each operating machine, the machine that produces the bad pixel can be locked. Not only can the machine that produces the bad pixel be locked, but also the specific chamber in the machine that performs lithography can be locked.

[0057] The method for obtaining the source of bad spots on the back of the wafer provided in this embodiment first obtains the back information of the wafer and the target bad spot feature map of each photolithography layer. Then, the target bad spot feature map is compared with the back information collected at each step of the previous layer, and the image information that meets the bad spot feature map is screened out. Finally, the machine that produces the bad spot can be locked by screening out the image information that meets the bad spot feature map and the back information of each operating machine. Not only can the previous layer source of the bad spot be traced back efficiently, shortening the existing time for troubleshooting the source, reducing the existing tracing workload, but also reducing the difficulty of the existing comparison.

[0058] To realize the above idea, this embodiment also discloses a system for obtaining the source of bad spots on the back of the wafer, including: an acquisition module, used to obtain the back of the wafer information of each operating machine, and the target bad spot feature map of each lithography layer. A comparison module, used to compare the target bad spot feature map with the back of the wafer information collected at each step of the previous layer, and filter out the image information that meets the bad spot feature map. A locking module, used to lock the machine that produces bad spots based on the filtered image information that meets the bad spot feature map and the back of the wafer information of each operating machine.

[0059] The system for obtaining the source of the backside bad point provided by this embodiment and the method for obtaining the source of the backside bad point provided by this embodiment belong to the same inventive concept. Therefore, the system for obtaining the source of the backside bad point provided by this embodiment at least has all the advantages of the method for obtaining the source of the backside bad point provided by this embodiment, and can lock the machine that produces the bad point. Not only can the front-layer source of the bad point be efficiently traced, the time for existing source investigation can be shortened, the workload of existing tracing can be reduced, and the difficulty of existing comparison can also be reduced.

[0060] In summary, the above embodiments have described in detail the different configurations of the method and system for obtaining the source of bad spots on the back of the wafer. Of course, the above description is only a description of the preferred embodiments of the present invention, and is not any limitation to the scope of the present invention. The present invention includes but is not limited to the configurations listed in the above implementations. Those skilled in the art can draw inferences based on the contents of the above embodiments. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure are within the scope of protection of the claims.

Claims

1. A method for obtaining the source of wafer backside bad points, characterized in that: include: Obtain the backside information of each wafer passed by the operating machine, as well as the target bad pixel feature map of each lithography layer; Compare the target bad pixel feature map with the backside information collected in each step of the previous layer, and filter out image information that meets the bad pixel feature map; Based on the image information that matches the bad pixel feature map and the backside information of each operating machine, the machine that produces the bad pixel is locked.

2. The method for obtaining the source of wafer backside bad spots according to claim 1, characterized in that: Obtaining the backside information of each wafer passing through the machine includes: Obtain image information of the backside of each wafer after each process step; Stacking the wafer back image information of all wafers in each batch to serve as the wafer back information of the wafer in the batch; The backside information of all batches of wafers is counted by machine, and the backside information of the wafers obtained by each operating machine is obtained.

3. The method for obtaining the source of wafer backside bad spots according to claim 1, characterized in that: The wafer back information includes the coordinates and size of the bad spot, wherein the size of the bad spot is the height of the bad spot protruding upward with the plane where the wafer is located as the horizontal plane.

4. The method for obtaining the source of wafer backside bad spots according to claim 1, characterized in that: The wafer back information is used to characterize the frequency of occurrence of bad pixels.

5. The method for obtaining the source of wafer backside bad spots according to claim 4, characterized in that: The area where bad pixels appear is called an abnormal area, and the frequency of bad pixels is represented by the depth of color. The more bad pixels appear in the abnormal area, the darker the color of the abnormal area.

6. The method for obtaining the source of wafer backside bad spots according to claim 1, characterized in that: Obtaining the target bad pixel feature map of each lithography layer includes: Each batch of wafers is lithographically processed by an etching machine, and the bad pixel information of the etched wafers is counted to obtain a bad pixel feature map corresponding to each batch of wafers; All batches of bad pixel feature maps obtained from each etching layer are stacked to obtain a target bad pixel feature map for the photolithography layer.

7. The method for obtaining the source of wafer backside bad spots according to claim 6, characterized in that: The bad pixel information of the batch of etched wafers is statistically analyzed as follows: Statistics are collected on the coordinates, size, and percentage distribution of bad pixels in the bad pixel feature map.

8. The method for obtaining the source of wafer backside bad spots according to claim 6, characterized in that: The statistics of bad pixel information of the wafers after etching in this batch also include: Obtain the distribution characteristics of bad pixels on the wafer to obtain the feature map radius, the distribution of bad pixels in the wafer radius, and the proportion of each distribution interval.

9. The method for obtaining the source of wafer backside bad spots according to claim 1, characterized in that: Comparing the target bad pixel feature map with the backside information collected in each step of the previous layer includes: Compare the position of the bad pixel in the target bad pixel feature map with the position of the bad pixel in the wafer back information.

10. A system for obtaining the source of wafer backside bad points, characterized in that: include: The acquisition module is used to obtain the backside information of each wafer passed by the operating machine, as well as the target bad pixel feature map of each photolithography layer; A comparison module is used to compare the target bad pixel feature map with the backside information collected in each step of the previous layer, and filter out image information that meets the bad pixel feature map; The locking module is used to lock the machine that produces the bad pixel based on the image information that is screened out and conforms to the bad pixel feature map and the wafer back information of each operating machine.

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