JP5690535B2 - Die bonder and semiconductor manufacturing method - Google Patents

Description

  The present invention relates to a die bonder and a semiconductor manufacturing method, and more particularly to a highly reliable die bonder and a semiconductor manufacturing method.

Part of the process of assembling a package by mounting a die (semiconductor chip) on a substrate such as a wiring board or a lead frame is a die bonding process in which the die is adsorbed from the wafer and bonded to the substrate.
In the die bonding process, it is necessary to bond the die accurately to the bonding surface of the substrate. However, the substrate surface is heated to a high temperature of about 80 ° C. to 250 ° C. to facilitate bonding. Due to the high temperature or radiant heat, the component members are displaced, and the die cannot be bonded to an accurate position.

  There is Patent Document 1 as a conventional technique for solving this type of problem. The problem of Patent Document 1 is that the difference (offset amount) between the position of the camera that detects the bonding position and the bonding tool changes by radiant heat from the high-temperature bonding stage. In order to solve this problem, in Patent Document 1, the offset amount is detected using a reference member provided near the bonding stage as a reference point, and the bonding position is corrected.

JP 2001-203224 A

  However, with the recent miniaturization of dies or the development of chip-on-chip technology, die bonding is required to have higher precision (a few tens to several μm). Therefore, in addition to the problem of Patent Document 1, a bonding position shift on the substrate side has become a problem due to thermal expansion of the substrate and the bonding stage that supports the substrate.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a highly reliable die bonder and a semiconductor manufacturing method capable of accurately bonding a die.

In order to achieve the above object, the present invention has at least the following features.
The present invention provides a first imaging unit that images a substrate or a reference mark provided in the vicinity of the substrate, a recognition pattern provided at a bonding position of the reference mark and the substrate, the reference mark, and the bonding Second imaging means for imaging the die close to the position, and correction means for correcting the position of the die close to the bonding position based on imaging data obtained by the first and second imaging means The first feature is that the bonding position correction apparatus comprises:

  The present invention also provides a first imaging step for imaging a reference mark provided in the vicinity of the substrate or in the vicinity of the substrate and a recognition pattern provided at the bonding position of the substrate, and a proximity step in which a die is brought close to the bonding position. And a second imaging step for imaging the reference mark and the die close to the bonding position, and the proximity of the bonding position based on the imaging data obtained by the first and second imaging steps. According to a second aspect of the present invention, the method includes a correction step of correcting the position of the die and a step of bonding the die to the substrate based on the correction amount.

Furthermore, the present invention is characterized in that a third reference mark is formed by irradiating light on the substrate. Further, the present invention provides the reference mark provided at a position other than the bonding position. A fourth feature is that the pattern is on the substrate.
Furthermore, the present invention is characterized in that the second imaging is performed obliquely from above with a predetermined angle with respect to the side of the bonding position.
Further, the present invention is characterized in that the correction is performed based on the imaging data of the die or collet.

  ADVANTAGE OF THE INVENTION According to this invention, the reliable die bonder and semiconductor manufacturing method which can bond die | dye correctly can be provided.

It is the conceptual diagram which looked at the die bonder which is one Embodiment of this invention from the top. It is a schematic block diagram of Example 1 of the bonding head part which has the bonding position correction apparatus which has the characteristics of this invention. 2 is a diagram illustrating an arrangement of two position correction cameras in Embodiment 1. FIG. The processing flow from when the bonding head sucks the die and comes to the upper side of the bonding position is shown. It is a figure which shows the imaging screen in the flow in FIG. It is a schematic block diagram of Example 2 of the bonding head part which has the bonding position correction apparatus which has the characteristics of this invention. It is a figure which shows the imaging screen in the process of Example 2.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a conceptual view of a die bonder 10 according to an embodiment of the present invention as viewed from above. The die bonder 10 is roughly divided into a wafer supply unit 1, a substrate supply / conveyance unit 5, a die bonding unit 3, and a control unit 4 that controls them.

The wafer supply unit 1 includes a wafer cassette lifter 11 and a pickup device 12. The wafer cassette lifter 11 has a wafer cassette (not shown) filled with wafer rings, and sequentially supplies the wafer rings to the pickup device 12. The pick-up device 12 moves the wafer ring so that the desired die can be picked up from the wafer ring.
The substrate supply / conveyance unit 5 includes a stack loader 51, a frame feeder 52, and an unloader 53. The stack loader 51 supplies a substrate (for example, a lead frame) to which the die is bonded to the frame feeder 52. The frame feeder 52 conveys the substrate to the unloader 53 via two processing positions on the frame feeder 52. The unloader 53 stores the transported substrate.

  The die bonding unit 3 includes a preform unit 31 and a bonding head unit 32. The preform unit 31 applies a die adhesive to the substrate conveyed by the frame feeder 52. The bonding head unit 32 picks up the die from the pickup device 12 and moves up, and moves the die to the bonding point on the frame feeder 52. Then, the bonding head unit 32 lowers the die at the bonding point, and bonds the die onto the substrate coated with the die adhesive.

  FIG. 2 is a schematic configuration diagram of the first embodiment of the bonding head unit 32 having the bonding position correcting apparatus 20 having the features of the present invention.

The bonding head unit 32 is a substrate that detects the position of the lead frame in order to align the bonding head 41 that adsorbs and bonds the die D and the lead frame 45 that is the substrate, in addition to the bonding position correction device 20 described later. A position detection imaging camera 42 (hereinafter simply referred to as a position detection camera), a fixed base 43 that supports or fixes the bonding head 41 and the position detection camera 42, a moving mechanism 47 that moves the fixed base 43 in the XY directions, and a lead And a bonding stage (hereinafter simply referred to as a stage) 44 that holds the frame 45. Reference numeral 52 denotes a frame feeder that forms the substrate supply / conveyance unit 5 that conveys the lead frame 45.
The bonding head 41 includes a collet 41c that holds the die D at the tip thereof, and a two-dimensional moving mechanism 41m that moves the collet 41c up and down (moves in the Z direction) to move the collet 41c in the Y direction with respect to the fixed base 43. And have.

  The bonding position correction apparatus 20 includes a reference mark forming light source (hereinafter simply referred to as a light source) 21 that forms a reference mark KM indicating a reference position on the lead frame 45 and a reference mark KM and a bonding position before the collet 41c is lowered. A processing position camera 22 that captures 45b (hereinafter referred to as a processing position), and two positions that capture the tip of the bonding head 41 and the reference mark KM that are directly above the processing position 45b when the collet 41c is lowered. Correction image pickup cameras (hereinafter simply referred to as position correction cameras) 23 and 24. In this embodiment, the processing position camera 22 is also used as the substrate position detection camera 42. Moreover, the light source 21 should just be what can irradiate in spot shape like a laser light source. Further, the processing position camera 22 and the like constituting the bonding position correcting device 20 are fixed to the structural member 27 of the die bonder 10 via their support portions 28. In FIG. 2, the support portion 28 of the position correction camera 23 is omitted for easy understanding of the drawing. Note that 45s indicated by a broken line indicates a processing position peripheral area including the processing position 45b and the reference mark KM. Two L-shaped recognition patterns 45p1 and 45p2 are formed on the diagonal line of the die D at the processing position 45b.

  FIG. 3 is a diagram showing the arrangement of the two position correction cameras 23 and 24. FIG. 3A is a view of the two position correction cameras 23 and 24 as viewed from above. FIG. 3B is a view of the position correction camera 23 or 24 as viewed from the side. As shown in FIG. 3A, the two position correction cameras 23 and 24 are disposed at a position of 90 degrees with respect to each other. Further, as shown in FIG. 3B, the two position correction cameras 23 and 24 are oblique to the lead frame 45 at an angle θ from the processing position peripheral region 45s including at least the reference mark KM and the processing position 45b. Image.

  With the above configuration, a bonding processing flow, which is a feature of the present invention in the embodiment of FIG. 2, will be described with reference to FIGS. FIG. 4 shows a processing flow from when the bonding head 41 sucks the die and comes to the upper side of the processing position. FIG. 5 is a diagram showing an imaging screen in the flow in FIG.

  First, before the bonding head 41 lowers the die D to the processing position 45b, the processing position camera 22 images the processing position peripheral region 45s including the reference mark KM and the processing position 45b (step 1). FIG. 5A is an imaging screen showing this state. In the state of FIG. 5A, the lead frame is thermally expanded by heating. Therefore, the position coordinates of the processing position 45b obtained from FIG. 5A are position coordinates including the influence of thermal expansion.

Two L-shaped recognition patterns 45p1 and 45p2 are formed on the diagonal line of the die D at the processing position 45b. Using the center point of the reference mark KM as the origin, the position coordinates of the two recognition patterns 45p1 and 45p2 are obtained by image processing (step 2). Next, the position coordinates of the center position 45c of the processing position 45b are obtained from the position coordinates of the two recognition patterns 45p1 and 45p2 (step 3). The coordinate position of the center position 45c is set as the first center coordinate. Assuming that the position coordinates of the first central coordinates 45c1 and the two recognition patterns 45p1 and 45p2 are (X1, Y1), (Xp11, Yp11), and (Xp21, Yp21), respectively, the first central coordinates are expressed by Equation (1), It can be obtained from equation (2).
X1 = (Xp11 + Xp21) / 2 (1)
Y1 = (Yp11 + Yp21) / 2 (2)
Next, the movement amount of the bonding head 41 is obtained (step 4). The position coordinates of Expression (1) and Expression (2) are position coordinates viewed from the processing position camera 22. Since there is an offset between the bonding head 41 and the processing position camera 22, it is necessary to change to a position coordinate viewed from the bonding head 41. Therefore, when the offset amount is (Xh, Yh), the position coordinates ((Xhi, Yhi) of the center position 45c viewed from the bonding head 41 are expressed by Equations (3) and (4).
Xhi = X1 + Xh (3)
Yhi = Y1 + Yh (4)
Next, the boarding head 41 is moved to the positions indicated by the equations (3) and (4), and the collet 41c holding the die D is lowered toward the processing position 45b (step 5). The moving time of the boarding head 41 and the descent time of the die D are very short. Therefore, there is almost no change in shape due to thermal expansion of the lead frame 45 or change in the offset amount during that time. Accordingly, if there is no fluctuation or time series fluctuation of the offset amount from the initial value, the die D can be bonded to the processing position 45b as the target value by the lowering of the die D.

  However, in practice, the offset amount changes due to radiant heat generated by the heating mechanism of the lead frame 45. Therefore, the change in the offset amount is corrected. For this purpose, it stops just before bonding, and detects the amount of deviation between the lowering position of the die and the processing position 45b. First, in the stopped state, the processing position peripheral region 45s including the reference mark KM and the processing position 45b is imaged by the two position correction cameras 23 and 24 (step 6).

  FIG. 5B and FIG. 5C show the states captured by the position correction cameras 23 and 24, respectively. The reason why the image is not picked up directly by the processing position camera 22 is that the collet 41c covers the processing position 45b and the recognition patterns 45p1 and 45p2 cannot be recognized. Second, although the collet 41c is likely to be imaged in FIG. 2, the collet 41c is actually obstructed by the mechanism of the bonding head 41 and cannot be seen from directly above. Therefore, imaging is performed with an angle θ shown in FIG. 3B so that the die D or the collet 41c can be imaged. Since the die D is actually bonded, an angle at which the die D itself can be imaged is desirable. When the die itself is imaged, the angle tends to decrease. However, if the remainder angle θ is decreased, the deformation of the image increases and the position detection accuracy decreases, and the angle is adjusted between them.

  Next, in the stopped state, the position coordinates of the corners of the die D corresponding to the two recognition marks are obtained by image processing (step 7). In the first embodiment, two position correction cameras 23 and 24 are used to obtain the position coordinates of the corner of the die D. The reason is as follows. When the image is taken obliquely, the hit length per pixel differs depending on the position in the X-axis direction and the Y-axis direction viewed from the position correction cameras 23 and 24, respectively, but the Y-axis direction and the X-axis direction are not changed. Therefore, as shown in FIG. 5 (b), the position coordinates in the X direction of the die D in the coordinate system based on the center of the reference mark KM based on the data captured by the position correction camera 23 are shown in FIG. 5 (c). As shown in FIG. 5, based on the data captured by the position correction camera 24, the position coordinate in the Y direction of the die D is detected in a coordinate system based on the center of the reference mark KM. Therefore, in the embodiment in FIG. 2, the die D corresponding to the recognition patterns 45p1 and 45p2 can be detected by using the corner on the imaging side.

The center position of the die D, that is, the center position 45c of the processing position 45b is obtained from the position coordinates of the corner of the die D (step 8). This center coordinate is defined as a second center coordinate 45c2. (X2, Y2) of the second central coordinate 45c2 is expressed by equations (5) and (6) from FIG. 5 (b) and FIG. 5 (c).
X2 = (Xd1 + Xd2) / 2 (5)
Y2 = (Yd1 + Yd2) / 2 (6)
Next, bonding represented by Equation (7) and Equation (8) from the first center coordinate obtained by Equation (1) and Equation (2) and the second center coordinate obtained by Equation (5) and Equation (6). A positional shift amount (correction amount) (ΔX, ΔY) is obtained (step 9).
ΔX = X2-X1 (7)
ΔY = Y2−Y1 (8)
The amount of deviation is the amount of deviation when viewed from the bonding head 41, and the following two points can be cited as causes. The first is the amount of offset deviation between the bonding head 41 and the processing position camera 22 due to radiant heat as described above. The second is the amount of offset deviation due to radiant heat between the bonding head 41 and the position correction cameras 23 and 24. However, in the second cause, since the position coordinates are obtained with the reference mark as the origin in the same image, even if a deviation of the offset amount occurs, it is naturally corrected. Therefore, the cause is the first point.

  Next, the die position is corrected based on the correction amount and bonded to the lead frame (substrate) 45 (step 10). Finally, the collet 41c is raised and the process proceeds to the next die bonding process (step 11).

  In the above description, the two L-shaped recognition patterns 45p1 and 45p2 provided on the diagonal line of the processing position 45b are used as the recognition patterns. In the above description, since the correction amount is finally obtained at the processing position, that is, the center position 45c of the bonding position, the L-shaped recognition patterns 45p1 and 45p2 are considered virtually, and × of the center position 45c of the processing position. A single recognition mark such as a (cross) mark may be used.

According to the first embodiment described above, it is possible to correct both the thermal expansion of the lead frame 45 itself due to the high temperature of the lead frame 45 and the offset amount between the processing position camera 22 and the position correction cameras 23 and 24 and the bonding head 41. It is possible to provide a highly reliable die bonder capable of accurately bonding the die.
Further, by using this die bonder, a highly reliable semiconductor manufacturing method can be provided.

  FIG. 6 is a schematic configuration diagram of a second embodiment of the bonding head unit 32 having the bonding position correction apparatus 20 having the features of the present invention.

  The second embodiment differs from the first embodiment in the following points, and the other points are the same. The first difference is as follows. In Example 1, the two position correction cameras 23 and 24 arranged at an angle of 90 degrees with each other were used to image the die D stopped immediately before bonding together with the reference mark KM, and the correction amount was obtained. In the second embodiment, as shown in FIG. 7A, the processing position 45b, that is, one position correction camera 25 arranged at an angle of 45 degrees with respect to the side of the die to be bonded is stopped immediately before bonding. The captured collet 41c and the reference mark KM are imaged together to determine the correction amount. FIG. 7C shows an image obtained by one position correction camera 25. FIG. 7A shows an image captured by the processing position camera 22, which is the same as FIG. 5A.

  Further, since the position correction camera 25 has an angle of 45 degrees in relation to the first point, the second point is also an image rotated by 45 degrees, and the position coordinate system is 45. Rotate degrees. Therefore, it is necessary to rotate one of the position coordinate systems 45 times to match the position coordinate systems of both images. In this embodiment, the position coordinate system of the imaging screen of the processing position camera 22 shown in FIG. 7B is rotated. The position coordinates shown in FIG. 7A indicate the position coordinates after rotation. Further, since the image is taken from an oblique direction, the correction is also performed.

Further, the third point shows an example in which the die itself is also covered with a collet and cannot be imaged as described above and as shown in FIG. Therefore, in this embodiment, a collet is used instead of a die.
As shown in FIG. 7, the position coordinates of the corner positions 41c1 and 41c2 of the collet 41c corresponding to the recognition patterns 45p1 and 45p2 shown in FIG. 7A are (Xc21, Yc21) and (Xc22, Yc22) by image processing, respectively. ) The second central coordinates (X2 ′, Y2 ′) are expressed by equations (9) and (10) from FIG. 5 (b) and FIG. 5 (c).
X2 ′ = (Xc21 + Xc22) / 2 (9)
Y2 '= (Yc21 + Yc22) / 2 (10)
As a result, the correction amounts (ΔX, ΔY ′) are obtained in the same manner as in the equations (7) and (8), the die position is corrected in the same manner as in the first embodiment, and bonding to the lead frame (substrate) 45 is performed. Can do.
In the above description, the position correction camera is arranged at 45 degrees with respect to the processing position 45b, but other angles may be used.

  Therefore, according to the second embodiment, it is possible to correct both the thermal expansion of the lead frame 45 itself due to the high temperature of the lead frame 45 and the variation in the offset amount of the processing position camera 22 and the bonding head 41, and the reliability with which the die can be accurately bonded. Can provide a high die bonder.

Further, according to the second embodiment, a semiconductor manufacturing method with high reliability can be provided by using this die bonder.
Furthermore, according to the second embodiment, only one position correction camera is required, and the system can be simplified.

  In both Example 1 and Example 2 described above, the reference mark was created using a light source, but a pattern on a substrate (lead frame) that is not hidden by the collet when bonding may be used, or a known example As described above, a specific member may be provided in the vicinity of the substrate.

  Although the embodiment of the present invention has been described above, the present invention includes various alternatives, modifications, and variations without departing from the spirit of the present invention.

1: Wafer supply unit 3: Die bonding unit 4: Control unit 5: Substrate supply / transfer unit 10: Die bonder 20: Bonding position correction device 21: Reference mark forming light source (light source) 22: Processing position cameras 23, 24, 25: Position correction imaging camera (position correction camera)
31: Preform part 32: Bonding head part 41: Bonding head 41c: Collet 42: Position detection camera 43: Fixing base 44: Bonding stage (stage) 45: Lead frame 45b: Bonding position (processing position) 45c: Processing position Center position 45p1, 45p2: Recognition pattern 45s: Processing position peripheral area including processing position and reference mark 47: Moving mechanism D: Die KM: Reference mark θ: Angle formed from the lead frame surface of the position correction imaging camera.

Claims (12)

A reference mark provided in the vicinity of the substrate or the substrate;
A first image pickup means for picking up an image of the reference mark and a recognition pattern provided at a bonding position of the substrate; a second image pickup means for picking up an image of the reference mark and a die close to the bonding position; A bonding position correction apparatus comprising: correction means for correcting the position of the die adjacent to the bonding position based on imaging data obtained by the first and second imaging means;
A die bonder characterized by comprising:   The die bonder according to claim 1, wherein the bonding position correction device includes a light source that forms the reference mark in a spot shape.   The die bonder according to claim 1, wherein the reference mark is a pattern on the substrate provided at a position other than the bonding position.   2. The die bonder according to claim 1, wherein the second image pickup unit picks up the image from obliquely above with a predetermined angle with respect to a side of the bonding position.   The die bonder according to claim 4, wherein the predetermined angle is 45 degrees.   2. The die bonder according to claim 1, wherein the second imaging unit is perpendicular to two sides adjacent to the bonding position, and performs the imaging from obliquely above. The die bonder according to claim 1, wherein the recognition pattern is a pattern provided at a corner or a center position of the bonding position. A first imaging step of imaging a reference mark provided in the vicinity of the substrate or the substrate and a recognition pattern provided at a bonding position of the substrate;
A proximity step to bring the die close to the bonding position;
A second imaging step of imaging the die adjacent to the reference mark and the bonding position;
A correction step of correcting the position of the die adjacent to the bonding position based on the imaging data obtained by the first and second imaging steps;
Bonding the die to the substrate based on the amount to be corrected;
A method of manufacturing a semiconductor, comprising:   9. The semiconductor manufacturing method according to claim 8, further comprising the step of irradiating light on the substrate to form the spot-like reference mark.   The semiconductor manufacturing method according to claim 8, wherein the reference mark is a pattern on the substrate provided at a position other than the bonding position.   The semiconductor manufacturing method according to claim 8, wherein in the second imaging step, the imaging is performed obliquely from above with a predetermined angle with respect to a side of the bonding position.   9. The semiconductor manufacturing method according to claim 8, wherein the correcting step is performed based on the imaging data of the die or collet.

Images