Method for defining effective bare crystal position on inspection wafer graph

Abstract

A method of defining an effective die position on an inspection wafer graph includes the following steps. The method comprises the following steps of: obtaining a position of a reference die in a test wafer graph, wherein the position of the reference die is adjacent to a central point of the test wafer graph; obtaining map data center data, and calculating the coordinate of the position of the reference point bare crystal in the map data center data; and calculating the relative offset between the coordinate system of the inspection wafer graph and the coordinate system of the map data center data according to the coordinate of the position of the reference point bare crystal in the map data center data. And returning the effective bare crystal position in the image information center data and modifying the inspection wafer image so as to generate a correct effective bare crystal image.

Description

Technical Field

[0001] The present invention relates to a valid die map, and more particularly to a method for defining valid die positions on an inspection wafer map. Background Art

[0002] Usually, it takes a complex process to manufacture multiple chips on a wafer. Wafer design is the first step in the semiconductor manufacturing process. Simply put, it is to transfer the designed circuit diagram to the semiconductor wafer. After a series of procedures, an integrated circuit (IC) is formed on the surface of the wafer, and then cut into pieces of bare crystals / die. Finally, these bare crystals / die are packaged and protected to form the final chip.

[0003] However, currently, a single wafer can accommodate tens of thousands of effective die, while invalid die and test die are scattered around the edge of the wafer and at specific locations within the circle. For inspection machines (including defect inspection, electrical inspection, thickness measurement, etc.), the location of the effective die must be defined before measurement can be performed. If the location of tens of thousands of effective die is manually selected and invalid die and test die are manually removed, it will take a long time, and the total number of effective chips on the wafer map will often have errors when manually selecting and inspecting, and it is impossible to achieve 100% accuracy. Summary of the invention

[0004] The invention relates to a method for defining effective bare die positions on an inspection wafer map, so as to solve problems caused by manual processing.

[0005] According to one aspect of the present invention, a method for defining a valid die position on an inspection wafer map is provided, comprising the following steps. Obtain the position of a reference die in an inspection wafer map, wherein the position of the reference die is adjacent to the center point of the inspection wafer map. Obtain map center data, and calculate the coordinates of the position of the reference die in the map center data. Calculate the relative offset between the coordinate system of the inspection wafer map and the coordinate system of the map center data based on the coordinates of the position of the reference die in the map center data. Return the valid die position in the map center data and modify the inspection wafer map to generate a correct valid die map.

[0006] In order to better understand the above and other aspects of the present invention, embodiments are given below and described in detail with reference to the accompanying drawings: BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 A flow chart of a method for defining valid die locations on a wafer map according to an embodiment of the present invention is shown.

[0008] FIG. 2A to FIG. 2D Draw the corresponding Figure 1 Schematic diagram of the various steps of the method.

[0009] Figure 3 A flow chart of a method for combining the position of a reference die on a wafer map with map center data according to an embodiment of the present invention is shown.

[0010] Figure 4 Schematic diagram showing the coordinates of the center die and the location of the center point of the inspection wafer map.

[0011] Figure 5A and Figure 5B Schematic diagrams showing the die sizes before and after merging are shown respectively.

[0012]

Explanation of symbols

[0013] 100: Check wafer image

[0014] 100c: Center point

[0015] 102: Bare crystal

[0016] 102c: Center Bare Crystal

[0017] 103a: First Bare Crystal

[0018] 103b: Second bare crystal

[0019] 103c: The third bare crystal

[0020] 106c: Central exposure area

[0021] 108:Effective wafer diameter

[0022] 110: Data from the Map Center

[0023] 112: Valid bare die image DETAILED DESCRIPTION

[0024] Generally speaking, wafers will inevitably have some defects during the manufacturing process, and there are many reasons for the defects on the wafers. Therefore, engineers observe the electron microscope photos of these defects and the distribution of erroneous bare crystals through the wafer map generated by the wafer inspection results, and then analyze the causes of errors in the manufacturing process. During the inspection process, engineers used to manually find the correct valid bare crystal position by observing the wafer map with the naked eye, and remove invalid bare crystals and test bare crystals to avoid noise interference. Although the manual selection method can ensure its accuracy, it is very inefficient. In view of this, the present invention automatically generates an inspection wafer map through a computer program to quickly define the position of the valid bare crystal on the inspection wafer map, and remove invalid bare crystals and test bare crystals, thereby reducing labor costs and the error rate of wafer analysis.

[0025] Please refer to Figure 1 and FIG. 2A to FIG. 2D ,in Figure 1 A flow chart of a method for defining valid die locations on a wafer map according to an embodiment of the present invention is shown. FIG. 2A to FIG. 2D Draw the corresponding Figure 1 A schematic diagram of each step of the method. The method for defining a valid die position on an inspection wafer map includes the following steps S110 to S140. First, in step S110, obtain the position of a reference die in an inspection wafer map, where the position of the reference die is adjacent to the center point of the inspection wafer map. In step S120, obtain a map center data, and calculate the coordinates of the position of the reference die in the map center data. Next, in step S130, calculate the relative offset between the coordinate system of the inspection wafer map and the coordinate system of the map center data based on the coordinates of the position of the reference die in the map center data. In step S140, transmit the valid die position in the map center data back and modify the inspection wafer map to generate a correct valid die map.

[0026] First, please refer to Figure 2A, according to the specifications of the produced die, multiple die 102 of the same size are generated, so that they are spread all over the inspection wafer map 100 (wafer map), so as to standardize the size of the die 102, and number each die 102. Next, the position of the reference point die is found from the inspection wafer map 100. Generally speaking, the position of the reference point die is, for example, the position of the center die (center die) 102c, but it can also be other reference point positions. The center die 102c is, for example, located at the lower left corner of the center exposure area (center shot) 106c. The center exposure area 106c represents the size of a mask pattern, and the position of the reference point 101 of the mask pattern (reticle map) is just located at the lower left corner of the center die 102c, and the reference point 101 is adjacent to the center point 100c of the inspection wafer map 100. Therefore, defining the center die 102c as the position of the reference point die can facilitate the calculation of the actual position / distance of each die 102 relative to the center die 102c. However, the present invention is not limited to using the central bare die 102c at the lower left corner of the central exposure area 106c as the position of the reference point bare die, and it may also be other corners or areas, and the present invention is not limited to this.

[0027] Then, in Figure 2B In the embodiment, the effective size of the inspection wafer image 100 is defined, wherein the effective size of the wafer image 100 refers to the effective wafer diameter 108 (eg, the original wafer diameter minus the reserved edge size (eg, 3.5 mm)). Figure 2B The wafers 102 located within the effective size are valid wafers and test wafers (located at specific locations) that are scheduled for product inspection, and the wafers 102 located outside the effective size are invalid wafers that are not scheduled for product inspection. Generally speaking, it takes a long time to manually remove invalid wafers and test wafers, and the total number of valid chips on the wafer map 100 that is manually selected for inspection often has errors, so Figure 2C In this embodiment, the coordinates (X, Y) of the reference point die in the inspection wafer map 100 can be read by a computer program, and the coordinates (X', Y') of the reference point die in the map center data 110 can be calculated, and the effective die position (such as Figure 2C As shown in FIG. 1 , the inspection wafer map 100 is transmitted back and modified to generate a correct valid die map 112. Figure 2C As shown, the valid die position in the data center data 110 is represented by bit 1, and the invalid die position is represented by bit 0, but it is not limited thereto. Through this embodiment, the number of more than tens of thousands of valid die that have been detected can be calculated without manually selecting them, and the accuracy is higher than that of manual selection.

[0028] For detailed steps of executing the computer program in step S140 to generate an effective die map 112, such as steps S142 to S148, please refer to Figure 3 ,in Figure 3 FIG. 1 is a flow chart of a method for combining the inspection wafer map 100 with the map center data 110 according to an embodiment of the present invention.

[0029] Please refer to Figure 3 In step S142, a map center data 110 is read by a computer program, wherein the map center data 110 is, for example, pre-collected or stored bare die production data of the same model, which includes the position information of each bare die 102 on the inspection wafer map 100 of the same model produced in the previous batch, valid bare die / invalid bare die information, and the relative coordinate information of each bare die 102 relative to the origin of the coordinate system of the map center data 110. For example, in Figure 2B In the inspection wafer map 100, the coordinates of the center die 102c relative to the origin of the coordinate system of the inspection wafer map 100 (for example, the upper left corner of the central exposure area 106c is the origin) are, for example, (X, Y), but the coordinates of the center die 102c relative to the origin of the coordinate system of the image data center data 110 (for example, the upper left corner of the image data is the origin) may be (X', Y'), there is a difference between the two, and the coordinate system conversion must be performed first. Therefore, in step S144, the computer program must first use the coordinates (X, Y) of the center die 102c as an anchor point to overlap the coordinate system of the inspection wafer map 100 with the coordinate system of the image data center data 110 to calculate the coordinates (X', Y') of each die 102 in the coordinate system of the image data center data 110. Next, in step S146, based on the position information of the center data 110, the computer program calculates the number of valid die and the number of invalid die generated by extending the center die 102c in four directions: left, right, up, and down. Figure 2C In step S148, the computer program calculates the number and position of 19 valid die generated by the expansion of the central die 102c to the left, the number and position of 20 valid die generated by the expansion to the right, and so on. The number and position of valid die in the upper and lower directions are shown above. Figure 2C The valid die position in the data center data 110 is returned Figure 2B The inspection wafer map 100 in FIG. 1 is used to generate a correct valid die map 112 (eg, Figure 2D As shown in FIG. 1 , the above-mentioned method for defining and inspecting effective die positions on the wafer map 100 is substantially completed.

[0030] In step S150, the method may further include calculating the total number of valid dies on the valid die map 112 by a computer program, and automatically removing the number of invalid dies and test dies originally in the inspection wafer map 100. In one embodiment, the computer program may be executed by a processor and / or computer software, and the computer program may be stored in a memory, wherein the processor may include: a central processing unit (CPU), a digital signal processor (DSP), a microprocessor (MPU), a microcontroller (MCU), and other standard logic integrated circuits (Standard logic ICs) for processing digital signals, application-specific integrated circuits (ASICs), etc.; the memory may include: a static random access memory (SRAM), a dynamic random access memory (DRAM), and a flash memory, etc.;

[0031] Please refer to Figure 4 , which depicts a schematic diagram of the coordinates (X, Y) of the center die 102c and the position of the center point 100c of an inspection wafer map. In one embodiment, the coordinates (X, Y) of the center die 102c may be located at a different position due to the offset caused by the alignment of the exposure machine. Therefore, the relative relationship between the coordinates (X, Y) of the center die 102c and the position of the center point 100c of the inspection wafer map 100 must be calculated based on the offset. For example, Figure 4 In the coordinate system of the central exposure area 106c, the coordinates (X, Y) of the central bare die 102c are (1, 3), and the position of the central point 100c of the inspection wafer map 100 falls on the coordinate point (1, 2). According to the offset calculation formula (-m+1, -b+n), it can be known that the coordinates (X, Y) of the central bare die 102c are offset (0, -1) relative to the position of the central point 100c of the inspection wafer map 100. That is, the X coordinate of the coordinate point where the central point 100c is located is set to m, the Y coordinate of the coordinate point where the central point 100c is located is set to n, and the Y coordinate of the coordinate point where the central bare die 102c is located is set to b. Substituting into the offset calculation formula (-m+1, -b+n), the position offset (-1+1, -3+2) = (0, -1) can be obtained. The above position offset (0, -1) information can be pre-stored in the map center data 110 for table lookup. Since the position offsets of the center die 102 c of the same model manufactured under the same process parameters are substantially the same, there is no need to recalculate the position of the center die 102 c .

[0032] Therefore, based on the image center data 110, the computer program can quickly find the position offset of the coordinates (X, Y) of the center die 112c relative to the center point 100c of the inspection wafer image 100. If it is (0, -1), it means that the center die 112c is located at a coordinate point below the center point 100c. Therefore, the computer program can correctly calculate the position of the center die 112c in the image center data 110 according to the offset calculation formula.

[0033] In step S150, the invalid bare die includes unqualified dies, dies outside the effective size of the wafer map 100, and test bare die for testing the performance of the dies. Figure 5A and Figure 5B , calculating the number of valid bare die may include calculating the number of merged first bare die 103a and second bare die 103b, wherein the size of the first bare die 103a and the second bare die 103b is, for example, smaller than a preset bare die size that cannot be selected by the human eye (for example, smaller than 1150 microns), and the bare die size is enlarged by merging the first bare die 103a and the second bare die 103b.

[0034] Please refer to Figure 5A and Figure 5B , which depicts a schematic diagram of the die size before and after merging, wherein the number of die in a single exposure area before merging is, for example, 22x1, and the number of die in a single exposure area after merging is, for example, 11x1. Calculating the number of the first die 103a and the second die 103b, for example, merging the first die 103a and the second die 103b of smaller size into a third die 103c of larger size, in addition to calculating the number of the third die 103c of larger size after merging, the computer program further calculates the original number of the first die 103a and the original number of the second die 103b before merging according to the merged data (e.g., two-in-one or three-in-one), so as to obtain the correct number of effective die.

[0035] The method for defining and inspecting valid die positions on a wafer map according to the above embodiment of the present invention does not require manual selection of tens of thousands of valid die that have been inspected, and does not require manual removal of invalid die and test die. The above operations can be completed through a computer program, thereby saving a great deal of time. Furthermore, the method for defining and inspecting valid die positions on a wafer map according to this embodiment can avoid errors that often occur when manually selecting and inspecting the total number of valid die on a wafer map, thereby improving the accuracy rate, for example, achieving 100% accuracy.

[0036] In summary, although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Those skilled in the art to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the scope defined in the attached claims.

Claims

1. A method for defining valid die locations on an inspection wafer map, comprising: Obtaining a position of a reference die in an inspection wafer map, wherein the position of the reference die is adjacent to a center point of the inspection wafer map; Obtain the center data of the image data, and calculate the coordinates of the position of the reference point bare die in the center data of the image data; Calculating the relative offset between the coordinate system of the inspection wafer map and the coordinate system of the map center data according to the coordinate of the position of the reference point die in the map center data; and The valid die positions in the map center data are transmitted back and the inspection wafer map is modified to generate a correct valid die map. 2 . The method of claim 1 , wherein the reference point die is a center die, the position of the center die is defined as a lower left corner of a center exposure area, and the center exposure area represents a size of a mask pattern.

3. The method as claimed in claim 1 further includes defining the effective size of the inspection wafer image as the effective wafer diameter obtained by deducting the reserved edge size from the original wafer diameter, wherein the bare crystals located within the effective size are valid bare crystals and test bare crystals (located at a specific position), and the bare crystals located outside the effective size are invalid bare crystals.

4. The method of claim 1 , wherein generating the correct effective die map comprises: Read the data from the map center using a computer program; The computer program uses the coordinates (X, Y) of the center die as an anchor point to overlap the coordinate system of the inspection wafer map with the coordinate system of the center data of the map, so as to calculate the coordinates (X', Y') of each die on the inspection wafer map in the coordinate system of the center data of the map; According to the position information of the center data of the image data, the computer program calculates the number of valid bare die and the number of invalid bare die generated by extending the center bare die in four directions: left, right, up and down; as well as The valid die position is transmitted back to the inspection wafer map, and the position of the valid die is marked in the inspection wafer map to generate the correct valid die map.

5. The method of claim 4, wherein generating the correct effective die map further comprises: The computer program is used to calculate the total number of valid dies on the valid die map, and automatically remove the number of invalid dies and test dies originally in the inspection wafer map.

6. The method as claimed in claim 4, wherein the central data of the image data collects or stores the production data of the same model of bare crystals in advance, which includes the position information of each bare crystal on the inspection wafer map of the same model produced in the previous batch, valid bare crystal / invalid bare crystal information, and the relative coordinate information of each bare crystal relative to the origin of the coordinate system of the central data of the image data. 7 . The method of claim 4 , wherein the coordinates (X, Y) of the center die are obtained by coordinate system transformation to obtain the coordinates (X′, Y′) of the center die in the coordinate system of the center data of the image.

8. The method of claim 4, wherein the computer program calculates the position offset of the coordinates (X, Y) of the central bare crystal relative to the center point of the inspection wafer map according to an offset calculation formula, and stores it in the map center data for table lookup.

9. The method of claim 8, wherein the computer program calculates the coordinates (X', Y') of the center die in the coordinate system of the image center data according to the offset.

10. The method of claim 5, wherein calculating the total number of valid bare dies comprises calculating the number of the first bare die and the second bare die after merging, and then calculating the original number of the first bare die and the original number of the second bare die before merging according to the merged data. 11 . The method of claim 10 , wherein the sizes of the first die and the second die are smaller than a preset die size that cannot be selected by human eyes.

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