Calibration method for high-precision bonding of chip

Abstract

The invention discloses a calibration method for high-precision bonding of a chip. The calibration method comprises the following steps: S1, identifying the outline of the chip; s2, moving the pickup head to a position above the chip; s3, picking up the chip and turning over the chip; s4, sucking the chip by the welding head; s5, the welding head moves to the position above the calibration piece; s6, giving way to the calibration sheet; s7, the distance B1M1 is calculated; s8, enabling the mark point B1 to coincide with the mark point M1; s9, calculating a distance B2M2; s10, calculating the angle offset between the chip and the standard sheet; s11, the welding head performs theta motion; s12, calculating a distance A1M3 between the mark point A1 and the mark point M3; s13, enabling the mark point A1 to coincide with the mark point M3; s14, calculating the angle offset between the substrate and the standard sheet; s15, performing angle compensation on the substrate; and S16, bonding the chip and the substrate. Compared with the prior art, high-precision bonding is realized.

Description

Technical Field

[0001] The invention belongs to the field of chip bonding, and in particular relates to a calibration method for high-precision chip bonding. Background Art

[0002] Flip-chip welding equipment is mainly used for the flip-chip welding process in the manufacture of large-scale integrated circuit devices. It completes the direct interconnection and bonding of the chip and the substrate, making the package have more superior high-frequency, low-latency, and low-crosstalk circuit characteristics, and can effectively improve the reliability of assembly interconnection of circuits, components or systems.

[0003] When the chip is bonded, the bonded chip is pressed and bonded to the substrate, thereby completing the flip-chip bonding process of the chip. In the prior art, only the position of the chip mark point on the bonding head is usually identified by the upward vision, so as to adjust the chip position so that the chip is aligned with the substrate. Summary of the invention

[0004] The purpose of the present invention is to provide a calibration method for high-precision chip bonding, which fully calculates the distance between the chip and the substrate through upward and downward vision in conjunction with a calibration sheet, thereby achieving position compensation and ensuring high-precision bonding between the chip and the substrate.

[0005] In order to achieve the above object, the present invention adopts the following technical solution: a calibration method for high-precision chip bonding, comprising the following steps:

[0006] S1, the first visual inspection component identifies the outline of the chip;

[0007] S2, the pickup head moves above the chip;

[0008] S3, the pickup head picks up the chip and turns it 180 degrees;

[0009] S4, the welding head picks up the chip from the pickup head, with the marking points M1 and M2 on the chip facing downwards;

[0010] S5. The welding head is moved to the top of the calibration sheet, and a first downward-looking visual device and a second downward-looking visual device are respectively arranged on both sides of the welding head. The visual center of the first downward-looking visual device is aligned with the mark point A1 on the calibration sheet, and the visual center of the second downward-looking visual device is aligned with the mark point A2 on the calibration sheet. A first upward-looking visual device and a second upward-looking visual device are arranged below the calibration sheet, and the visual center of the first upward-looking visual device is aligned with the mark point B1 on the calibration sheet, and the visual center of the second upward-looking visual device is aligned with the mark point B2 on the calibration sheet;

[0011] S6, the calibration piece is moved horizontally to make way, so that the first upward vision device below the calibration piece recognizes the mark point M1 on the chip, and the second upward vision device recognizes the mark point M2 on the chip;

[0012] S7, the first upward vision device calculates and obtains the distance B1M1 between the marking point B1 and the marking point M1;

[0013] S8, the welding head moves in XY direction so that the marking point B1 coincides with the marking point M1;

[0014] S9, the second upward vision device calculates the distance B2M2 between the marking point B2 and the marking point M2;

[0015] S10, calculating a first angle offset between the chip and the standard sheet;

[0016] S11, the welding head performs θ movement according to the calculated first angle offset between the chip and the calibration sheet;

[0017] S12, the welding head, the first downward vision device and the second downward vision device move to the top of the substrate, and calculate the distance A1M3 between the marking point A1 and the marking point M3;

[0018] S13, moving the substrate by a high-precision XY displacement platform so that the marking point A1 coincides with the marking point M3;

[0019] S14, calculating a second angle offset between the substrate and the standard piece;

[0020] S15, according to the calculated second angle offset between the substrate and the standard sheet, the substrate performs θ movement to perform angle compensation;

[0021] S16, the welding head descends along the Z axis to bond the chip and the substrate.

[0022] As a further description of the above technical solution:

[0023] In step S7 and step S9, the welding head, the first downward-looking vision device and the second downward-looking vision device are lowered along the Z-axis so that the chip under the welding head is at the same height as the calibration sheet, the visual center of the first downward-looking vision device is aligned with the marking point A1 on the calibration sheet, and the visual center of the second downward-looking vision device is aligned with the marking point A2 on the calibration sheet.

[0024] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0025] 1. In the present invention, during the chip bonding process, the upward vision and the downward vision are used to calculate the distance between the chip marking point M1 and the marking point M2 on the welding head and the visual center of the downward vision through the calibration sheet. After that, when the chip is bonded to the substrate, the distance between the visual center of the downward vision and the marking point on the substrate is used to calculate the offset between the marking point on the chip and the marking point on the calibration sheet, and between the marking point on the substrate and the marking point on the calibration sheet, thereby controlling the chip and the substrate to perform XYθ movement, realizing position compensation, and ensuring high-precision bonding between the chip and the substrate.

[0026] 2. In the present invention, during step S12-step S16, two position compensation methods can be used when performing position compensation between the chip and the substrate. One is that the welding head does not move as described in step S12-step S16, the substrate performs XYθ movement, aligns the chip, and a high-precision motion stage is set on the back of the substrate to fully ensure the bonding accuracy; the other is that the welding head moves and the substrate does not move. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 Schematic diagram of step S5 in a calibration method for high-precision chip bonding.

[0029] Figure 2 Schematic diagram of step S6 in a calibration method for high-precision chip bonding.

[0030] Figure 3 Schematic diagram of step S8 in a calibration method for high-precision chip bonding.

[0031] Figure 4 It is a schematic diagram of step S11 in a calibration method for high-precision chip bonding.

[0032] Figure 5 It is a schematic diagram of step S12 in a calibration method for high-precision chip bonding.

[0033] Figure 6 It is a schematic diagram of step S13 in a calibration method for high-precision chip bonding.

[0034] Figure 7 It is a schematic diagram of step S15 in a calibration method for high-precision chip bonding.

[0035] Figure 8It is a schematic diagram of step S16 in a calibration method for high-precision chip bonding.

[0036] Legend:

[0037] 1. Chip; 2. Welding head; 3. Calibration sheet; 4. Substrate. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] The marking points A1, A2, B1, and B2 on the calibration sheet 3 are photoetching points with nanometer precision. The distance between them is known, and the position relationship is consistent with the corresponding marking points on the chip and substrate. Consistent.

[0041] Therefore, the following calculation conditions can be obtained:

[0042] L(A1, A2)=(C 1X , C 1Y )constant

[0043] L(B1, B2)=(C 2X , C 2Y )constant

[0044] L(A1, B1)=(C 3X , C 3Y )constant

[0045] L(B2, A2)=(C 4X , C 4Y )constant

[0046] Assume that the pixel calibration value of the four groups of lenses is K.

[0047] Marking point M1 and marking point M2 are located at diagonals of chip 1 , and marking point M3 and marking point M4 are located at diagonals of substrate 4 .

[0048] See also Figure 1-8The present invention provides a technical solution: a calibration method for high-precision chip bonding, comprising the following steps:

[0049] S1, the first visual detection component recognizes the outline of chip 1;

[0050] S2, the pickup head moves to above chip 1;

[0051] S3, the pickup head picks up chip 1 and turns it 180 degrees;

[0052] S4, welding head 2 picks up chip 1 from the pick-up head, with the marking points M1 and M2 on chip 1 facing downward;

[0053] S5, the welding head 2 is moved to the top of the calibration sheet 3, and a first downward-looking visual device and a second downward-looking visual device are respectively provided on both sides of the welding head 2, and the visual center of the first downward-looking visual device is aligned with the marking point on the calibration sheet 3 The visual center of the second downward vision device is aligned with the marking point on the calibration sheet 3 A first upward visual device and a second upward visual device are arranged below the calibration sheet 3, and the visual center of the first upward visual device is aligned with the marking point on the calibration sheet 3. The visual center of the second upward vision device is aligned with the mark point on the calibration sheet 3

[0054] S6, the calibration sheet 3 is moved horizontally to make way, so that the first upward visual device below the calibration sheet 3 recognizes the mark point M1 (a1, b1) on the chip 1, and the second upward visual device recognizes the mark point M2 (a2, b2) on the chip 1, and the mark point M1 and the mark point M2 are located at the diagonal positions of the chip 1;

[0055] S7, the first upward vision device combines and calculates the recognized marking point M1 and the marking point B1 to obtain the distance between B1 and M1.

[0056] S8, move the high-precision XY displacement platform of the welding head 2 so that the marking point M1 and the marking point B1 coincide with each other, that is, B1M1=(0,0);

[0057] S9, the second upward vision device combines and calculates the recognized mark point M2 and the mark point B2 to obtain the distance between B2 and M2.

[0058] S10, calculating the first angle offset α between the chip 1 and the standard chip 3 Dev , the calculation formula is as follows

[0059]

[0060] S11, the welding head 2 performs θ movement according to the calculated first angle offset between the chip 1 and the calibration sheet 3 to perform angle compensation;

[0061] S12, the welding head 2, the first downward visual device and the second downward visual device move to the top of the substrate 4, the first downward visual device recognizes the mark point M3 on the substrate 4, the second downward visual device recognizes the mark point M4 on the substrate 4, the mark point M3 and the mark point M4 are located at the diagonal positions of the substrate 4, and the distance A1M3 between the mark point A1 and the mark point M3 is calculated.

[0062] S13, the high-precision XY displacement platform of the moving substrate 4 makes the marking point A1 and the marking point M3 coincide, that is, A1M3 = (0, 0);

[0063] S13, the second upward vision device combines and calculates the recognized marking point A2 and the marking point M4 to obtain the distance between A2 and M4.

[0064] S14, calculating the second angle offset β between the substrate 4 and the standard piece 3 Dev , the calculation formula is as follows

[0065]

[0066] S15, the substrate 4 performs θ movement according to the calculated second angle offset between the substrate 4 and the standard sheet 3 to perform angle compensation;

[0067] S16, the bonding head 2 descends along the Z axis to bond the chip 1 and the substrate 4.

[0068] In step S7 and step S9, the welding head 2, the first downward-looking vision device and the second downward-looking vision device are lowered along the Z axis so that the chip 1 below the welding head 2 and the calibration plate 3 are at the same height, the visual center of the first downward-looking vision device is aligned with the marking point A1 on the calibration plate 3, and the visual center of the second downward-looking vision device is aligned with the marking point A2 on the calibration plate 3.

[0069] Working principle: During the chip bonding process, the upward vision and downward vision calculate the offset between the chip marking points M1 and M2 on the welding head and the marking points B1 and B2 on the calibration sheet through the calibration sheet. After that, when the chip is bonded to the substrate, the offset between the marking points on the substrate and the marking points on the calibration sheet is calculated through the distance between the visual center of the downward vision and the marking points on the substrate, and then the chip and the substrate are controlled to perform XYθ movement to achieve position compensation and ensure high-precision bonding between the chip and the substrate. When performing position compensation on the chip, the welding head performs XYθ movement and the substrate does not move; when performing position compensation on the substrate, the welding head does not move and the substrate performs XYθ movement. High-precision motion stages are set on the back of the substrate and the chip at the same time to fully ensure bonding accuracy.

[0070] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A calibration method for high-precision chip bonding, characterized in that: The following steps are involved: S1, a first visual detection component identifies the outline of the chip (1); S2, the pickup head moves to above the chip (1); S3, the pickup head picks up the chip (1) and turns it 180 degrees; S4, the welding head (2) picks up the chip (1) from the pickup head, with the marking point M1 and the marking point M2 on the chip (1) facing downwards; S5, the welding head (2) is moved to the top of the calibration sheet (3), a first downward-looking visual device and a second downward-looking visual device are respectively arranged on both sides of the welding head (2), the visual center of the first downward-looking visual device is aligned with the mark point A1 on the calibration sheet (3), and the visual center of the second downward-looking visual device is aligned with the mark point A2 on the calibration sheet (3), and a first upward-looking visual device and a second upward-looking visual device are arranged below the calibration sheet (3), the visual center of the first upward-looking visual device is aligned with the mark point B1 on the calibration sheet (3), and the visual center of the second upward-looking visual device is aligned with the mark point B2 on the calibration sheet (3); S6, the calibration sheet (3) moves horizontally to make way, so that the first upward-looking visual device below the calibration sheet (3) recognizes the marking point M1 on the chip (1), and the second upward-looking visual device recognizes the marking point M2 on the chip (1); S7, the first upward vision device calculates and obtains a distance B1M1 between the marking point B1 and the marking point M1; S8, the welding head (2) moves in XY direction so that the marking point B1 coincides with the marking point M1; S9, the second upward vision device calculates and obtains a distance B2M2 between the marking point B2 and the marking point M2; S10, calculating a first angle offset between the chip (1) and the standard chip (3); S11, the welding head (2) performs θ movement according to the calculated first angular offset between the chip (1) and the calibration sheet (3); S12, the welding head (2), the first downward-looking visual device and the second downward-looking visual device move to above the substrate (4), and calculate the distance A1M3 between the marking point A1 and the marking point M3; S13, moving the substrate (4) by means of a high-precision XY displacement platform so that the marking point A1 coincides with the marking point M3; S14, calculating a second angular offset between the substrate (4) and the standard sheet (3); S15, according to the calculated second angular offset between the substrate (4) and the standard sheet (3), the substrate (4) performs θ movement to perform angle compensation; S16, the bonding head (2) descends along the Z axis to bond the chip (1) and the substrate (4).

2. A calibration method for high-precision chip bonding according to claim 1, characterized in that: In step S7 and step S9, the welding head (2), the first downward-looking visual device and the second downward-looking visual device are lowered along the Z-axis so that the chip (1) below the welding head (2) and the calibration sheet (3) are at the same height, the visual center of the first downward-looking visual device is aligned with the marking point A1 on the calibration sheet (3), and the visual center of the second downward-looking visual device is aligned with the marking point A2 on the calibration sheet (3).

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