A LDI exposure compensation method

Abstract

The invention discloses an LDI exposure compensation method, which belongs to the field of laser direct imaging technology. An LDI exposure compensation method comprises the following steps: collecting transverse texture features and longitudinal texture features of a copper strip; defining a plurality of calibration areas on the surface of the copper strip; covering the surface of the copper strip with a dry film, exposing a calibration pattern on the dry film of the calibration area and developing it, wherein the calibration pattern comprises transverse lines, longitudinal lines and oblique lines; amplifying the transverse error value according to the transverse texture features of the copper strip to obtain a transverse correction value; amplifying the longitudinal error value according to the longitudinal texture features to obtain a longitudinal correction value; calculating an oblique correction value according to the transverse texture features, the longitudinal texture features and the oblique error value; performing compensation of the exposure engine in the X-direction exposure position according to the transverse correction value, performing compensation of the exposure engine in the Y-direction exposure position according to the longitudinal correction value, and performing compensation of the optical path angle of the exposure engine according to the oblique correction value.

Description

Technical Field

[0001] The present invention relates to the technical field of laser direct imaging, and more specifically to an LDI exposure compensation method. Background Art

[0002] The existing LDI exposure equipment is used in the lead frame industry. The laser beam moves in the Y direction for irradiation and moves in the X direction for splicing steps. After multiple movements in the X / Y directions, the lead frame pattern is exposed on the dry film. The exposure results of the existing LDI equipment are different from the design values. The design values ​​are achieved by adjusting the equipment compensation in the X and Y directions. After the actual adjustment, the XY adjustment is inconsistent, resulting in fluctuations in the oblique dimensions. The size difference after the actual operation of the lead frame is obvious.

[0003] After searching the patent document with the existing publication number CN117724307A, a method, device and LDI exposure equipment for calibrating and compensating the position of LDI exposure pattern are provided. The method exposes a MARK point grid with a fixed row and column spacing on a substrate, and for any position to be calibrated within the compensation range, determines its target grid and obtains the errors of the four vertices of the target grid, calculates the position error between the actual exposure pattern and the ideal pattern at the position according to the errors of the four vertices of the target grid, and then calibrates and compensates the position according to the calculated error. Thus, the accuracy compensation of any position can be achieved by compensating the grid size.

[0004] In order to increase the surface roughness of the copper strip used in the current lead frame, a roller is used to form a texture on the surface of the copper strip. Due to the processing characteristics of the copper strip, the texture direction is uniform, resulting in differences in the analytical effects of the dry film in various directions affected by the texture in the actual processing of the lead frame. It is difficult to control the error within a reasonable range by directly compensating based on the error. In view of this, we propose an LDI exposure compensation method. Summary of the invention

[0005] 1. Technical issues to be solved

[0006] The object of the present invention is to provide an LDI exposure compensation method to solve the problems raised in the above background technology.

[0007] 2. Technical solution

[0008] The present invention is achieved through the following technical solutions:

[0009] An LDI exposure compensation method comprises the following steps:

[0010] S1. Collect the transverse texture characteristics and longitudinal texture characteristics of the copper strip;

[0011] S2, defining multiple calibration areas on the surface of the copper tape;

[0012] S3, covering the surface of the copper strip with a dry film, exposing a calibration pattern on the dry film in the calibration area and developing the calibration pattern, wherein the calibration pattern includes horizontal lines, vertical lines and oblique lines;

[0013] S4. Measure the actual widths of the horizontal lines, vertical lines, and diagonal lines in each calibration area;

[0014] S5, calculating the error between the designed width and the actual width of the transverse line, the longitudinal line, and the oblique line of each calibration pattern in each calibration area;

[0015] S6, respectively calculating the mean of the lateral line errors, the mean of the longitudinal line errors, and the mean of the oblique line errors of all calibration patterns in the multiple calibration areas as the lateral error value, the longitudinal error value, and the oblique error value;

[0016] S7, amplifying the transverse error value according to the transverse texture characteristics of the copper strip to obtain a transverse correction value; amplifying the longitudinal error value according to the longitudinal texture characteristics to obtain a longitudinal correction value; calculating the oblique correction value according to the transverse texture characteristics, the longitudinal texture characteristics, and the oblique error value;

[0017] S8. Compensate the exposure position of the exposure engine in the X direction according to the lateral correction value, compensate the exposure position of the exposure engine in the Y direction according to the longitudinal correction value, and compensate the optical path angle of the exposure engine according to the oblique correction value.

[0018] As an optional solution of the technical solution of the present application document, in S1, the transverse texture feature is the roughness of the copper strip in the transverse direction, and the longitudinal texture feature is the roughness of the copper strip in the longitudinal direction.

[0019] As an optional solution of the technical solution of this application document, in S2, the number of calibration areas is not less than three.

[0020] As an optional solution of the technical solution of the present application document, in S3, a plurality of calibration patterns are provided in each calibration area, and the design widths of the horizontal lines, vertical lines and oblique lines of different calibration patterns in the same calibration area are all different.

[0021] As an optional solution of the technical solution of this application document, the width of the horizontal lines, the vertical lines and the oblique lines is 11-45 microns.

[0022] As an optional solution of the technical solution of this application document, in S7, the calculation formula of the lateral correction value is as follows:

[0023]

[0024] in, is the lateral correction value, is the lateral correction factor, is the roughness of the copper strip in the transverse direction, is the lateral error value.

[0025] As an optional solution of the technical solution of this application document, in S7, the calculation formula of the longitudinal correction value is as follows:

[0026]

[0027] in, is the longitudinal correction value, is the longitudinal correction factor, is the roughness of the copper strip in the longitudinal direction, is the longitudinal error value.

[0028] As an optional solution of the technical solution of this application document, in S7, the calculation formula of the oblique correction value is as follows:

[0029]

[0030] in, is the oblique correction value, is the oblique error value, is the angle adjustment value, is the oblique correction factor, is the roughness of the copper strip in the transverse direction, It is the roughness of the copper strip in the longitudinal direction.

[0031] 3. Beneficial effects

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present application optimizes the size of the light spot by collecting the horizontal and vertical roughness of the copper tape, and according to the exposure pattern error of the exposure engine, compensates for the exposure position and the optical path angle of the exposure engine, thereby reducing the influence of the surface texture of the copper tape on the light spot size and increasing the exposure accuracy of the exposure engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a flow chart of an LDI exposure compensation method;

[0035] Figure 2 It is a copper tape texture map of the LDI exposure compensation method;

[0036] Figure 3 It is a diagram of the arrangement structure of the calibration area of ​​the LDI exposure compensation method;

[0037] Figure 4 A schematic diagram of a calibration pattern for an LDI exposure compensation method. DETAILED DESCRIPTION

[0038] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings.

[0039] See also Figure 1 , the present invention provides a technical solution:

[0040] An LDI exposure compensation method comprises the following steps:

[0041] S1. Collect the transverse texture characteristics and longitudinal texture characteristics of the copper strip;

[0042] S2, defining multiple calibration areas on the surface of the copper tape;

[0043] S3, covering the surface of the copper strip with a dry film, exposing a calibration pattern on the dry film in the calibration area and developing the calibration pattern, wherein the calibration pattern includes horizontal lines, vertical lines and oblique lines;

[0044] S4. Measure the actual widths of the horizontal lines, vertical lines, and diagonal lines in each calibration area;

[0045] S5, calculating the error between the designed width and the actual width of the transverse line, the longitudinal line, and the oblique line of each calibration pattern in each calibration area;

[0046] S6, respectively calculating the mean of the lateral line errors, the mean of the longitudinal line errors, and the mean of the oblique line errors of all calibration patterns in the multiple calibration areas as the lateral error value, the longitudinal error value, and the oblique error value;

[0047] S7, amplifying the transverse error value according to the transverse texture characteristics of the copper strip to obtain a transverse correction value; amplifying the longitudinal error value according to the longitudinal texture characteristics to obtain a longitudinal correction value; calculating the oblique correction value according to the transverse texture characteristics, the longitudinal texture characteristics, and the oblique error value;

[0048] S8. Compensate the exposure position of the exposure engine in the X direction according to the lateral correction value, compensate the exposure position of the exposure engine in the Y direction according to the longitudinal correction value, and compensate the optical path angle of the exposure engine according to the oblique correction value.

[0049] In S1, the texture on the copper tape used for the lead frame is as follows Figure 2 As shown, in order to quantify the influence of the copper tape texture on the LDI exposure accuracy, the roughness of the copper tape in the transverse direction can be used as the transverse texture feature, and the roughness of the copper tape in the longitudinal direction can be used as the longitudinal texture feature.

[0050] In S2, the number of the calibration areas is not less than three, and the multiple calibration areas are arranged longitudinally on the copper tape.

[0051] In S3, a plurality of calibration patterns are provided in each calibration area, and the design widths of the transverse lines, longitudinal lines and oblique lines of different calibration patterns in the same calibration area are all different, and the design widths of the transverse lines, longitudinal lines and oblique lines of the calibration pattern are 11-45 microns; the transverse lines of the calibration pattern are parallel to the transverse texture direction of the copper strip, and the longitudinal lines of the calibration pattern are perpendicular to the transverse texture direction of the copper strip, and the angle between the oblique lines of the calibration pattern and the transverse lines of the calibration pattern is preferably 45 degrees.

[0052] In S4 to S6, by setting a plurality of calibration areas and setting a plurality of calibration patterns in each calibration area, the influence of random errors can be reduced and the reliability of the calculation results can be increased when calculating the lateral error value, the longitudinal error value and the oblique error value.

[0053] In S7, the calculation formula of the lateral correction value is as follows:

[0054]

[0055] in, is the lateral correction value, is the lateral correction factor, is the roughness of the copper strip in the transverse direction, is the lateral error value.

[0056] The calculation formula of the longitudinal correction value is as follows:

[0057]

[0058] in, is the longitudinal correction value, is the longitudinal correction factor, is the roughness of the copper strip in the longitudinal direction, is the longitudinal error value.

[0059] The calculation formula of the oblique correction value is as follows:

[0060]

[0061] in, is the oblique correction value, is the oblique error value, is the angle adjustment value, is the oblique correction factor, is the roughness of the copper strip in the transverse direction, It is the roughness of the copper strip in the longitudinal direction.

[0062] In S8, the original size of the light spot is a square. Due to the influence of the surface roughness of the copper tape, it becomes a rectangle after exposure. The actual size of the calibration pattern after development is narrower than expected. The diagonal line has size deviation during the light spot splicing process. By compensating the exposure position of the exposure engine and the optical path angle, the size of the light spot can be optimized to reduce the influence of the surface roughness of the copper tape on the exposure accuracy.

[0063] The following will introduce the above methods in combination with actual implementation cases:

[0064] In this case, the equipment used has 12 groups of exposure engines, 6 groups at the top and 6 groups at the bottom. In each exposure engine, the single light path from top to bottom is divided into 3 areas, and calibration patterns of different sizes are arranged in each area, such as Figure 3 As shown in Figure 2. The calibration pattern is as follows: Figure 4 As shown, multiple transverse lines, longitudinal lines, and diagonal lines are spliced ​​into multiple mutually nested annular figures, and width markings are provided in the middle of the multiple mutually nested annular figures. Preferably, the width markings are the designed widths of the transverse lines, longitudinal lines, and diagonal lines of the calibration pattern.

[0065] The calculation process of compensating one set of exposure engines using the above method is as follows:

[0066] Table 1: Engine 1 compensation calculation table

[0067]

[0068] After performing compensation on the exposure position in the X direction, the exposure position in the Y direction, and the angle of the optical path on engine 1, and re-exposing the calibration pattern, the measurement results are as follows:

[0069] Table 2: Engine 1 retest data

[0070]

Claims

1. An LDI exposure compensation method, characterized in that: The following steps are involved: S1. Collect the transverse texture characteristics and longitudinal texture characteristics of the copper strip; S2, defining multiple calibration areas on the surface of the copper tape; S3, covering the surface of the copper strip with a dry film, exposing a calibration pattern on the dry film in the calibration area and developing the calibration pattern, wherein the calibration pattern includes horizontal lines, vertical lines and oblique lines; S4. Measure the actual widths of the horizontal lines, vertical lines, and diagonal lines in each calibration area; S5, calculating the error between the designed width and the actual width of the transverse line, the longitudinal line, and the oblique line of each calibration pattern in each calibration area; S6, respectively calculating the mean of the lateral line errors, the mean of the longitudinal line errors, and the mean of the oblique line errors of all calibration patterns in the multiple calibration areas as the lateral error value, the longitudinal error value, and the oblique error value; S7, amplifying the transverse error value according to the transverse texture characteristics of the copper strip to obtain a transverse correction value; amplifying the longitudinal error value according to the longitudinal texture characteristics to obtain a longitudinal correction value; calculating the oblique correction value according to the transverse texture characteristics, the longitudinal texture characteristics, and the oblique error value; S8, performing compensation for the exposure position of the exposure engine in the X direction according to the lateral correction value, performing compensation for the exposure position of the exposure engine in the Y direction according to the longitudinal correction value, and performing compensation for the optical path angle of the exposure engine according to the oblique correction value; In S1, the transverse texture feature is the roughness of the copper strip in the transverse direction, and the longitudinal texture feature is the roughness of the copper strip in the longitudinal direction; In S7, the calculation formula of the lateral correction value is as follows: in, is the lateral correction value, is the lateral correction factor, is the roughness of the copper strip in the transverse direction, is the lateral error value; In S7, the calculation formula of the longitudinal correction value is as follows: in, is the longitudinal correction value, is the longitudinal correction factor, is the roughness of the copper strip in the longitudinal direction, is the longitudinal error value; In S7, the calculation formula of the oblique correction value is as follows: in, is the oblique correction value, is the oblique error value, is the angle adjustment value, is the oblique correction factor, is the roughness of the copper strip in the transverse direction, It is the roughness of the copper strip in the longitudinal direction.

2. The LDI exposure compensation method according to claim 1, characterized in that: In S2, the number of calibration areas is not less than three.

3. The LDI exposure compensation method according to claim 1, characterized in that: In S3, a plurality of calibration patterns are provided in each calibration area, and the design widths of the transverse lines, longitudinal lines and oblique lines of different calibration patterns in the same calibration area are all different.

4. The LDI exposure compensation method according to claim 1, characterized in that: The widths of the transverse lines, longitudinal lines and oblique lines are 11-45 microns.

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