JP4441344B2 - Sheet pasting device - Google Patents

Description

  The present invention relates to a sheet affixing device, and more specifically, when an adhesive sheet is affixed to the surface of a semiconductor wafer having a plurality of solder bumps (hereinafter simply referred to as “bumps”), air is interposed between the bumps. The present invention relates to a sheet sticking device that can prevent mixing.

  2. Description of the Related Art Conventionally known semiconductor wafers (hereinafter simply referred to as “wafers”) are those that form a plurality of chips that ensure electrical connection by a flip chip method. As shown in FIG. 8, such a wafer W is half-cut into a plurality of bumps B having a protrusion shape and a square shape in plan view by tip dicing, and at a position corresponding to the outer peripheral edge of each vertically long chip C. In the process of forming the chip C from the wafer W after the groove-shaped (see FIG. 10) dicing line DL provided is formed on the surface W1, first, in order to protect the surface W1 and the bumps B of the wafer W, Each chip is obtained by pasting the adhesive sheet H on the surface of the wafer W via a pasting device (see Patent Document 1), then grinding the back side of the wafer W with a predetermined grinding device and making the wafer W extremely thin. C is formed.

  Here, the sticking apparatus includes a holding table that holds the wafer W and a pressing roll R (see FIG. 8) that rolls on the adhesive sheet H disposed on the surface W1 of the wafer W. A pressing force is applied to the adhesive sheet H by the roll R.

Japanese Patent Laid-Open No. 7-14807

  However, in the apparatus, once the reference position (orientation flat or V notch) of the wafer is determined and positioned, the adhesive sheet H can be bonded only in a certain direction regardless of the circuit pattern. As shown in FIG. 10, air is mixed between the wafer W surface W <b> 1 and the adhesive sheet H, and an area SA where bubbles A are generated is easily formed. Therefore, as shown in FIG. 11, when a wafer W that has been half-cut on the wafer surface side by front dicing is ground from the back surface side (upper surface side in the figure), the cooling water used for the grinding is It will enter the bubble A through the dicing line DL. As a result, the surfaces of the bumps B and the wafer W (the lower surface in the figure) are wetted or fouled by the cooling water, resulting in a defective product of the chip C and the like, resulting in a decrease in yield. In addition, due to the ultra-thinning of the wafer W by grinding, the wafer W expands in the region A where the bubbles A are generated (see FIG. 12). In this state, if the grinding is continued, the thickness of the chip C is kept constant. This also causes product defects.

  Here, in order to avoid the inconvenience, the present inventor has studied from various viewpoints, and there is a causal relationship between the generation of bubbles A and the conditions of the wafer W and the sticking apparatus in the following points. I thought.

(1) Bubble A generation area SA
As shown in FIGS. 8 and 9, the bubble A is positioned so as to straddle the adjacent bumps B in the generation region SA. The generation area SA extends substantially parallel to the extending direction of the central axis CT of the pressing roll R when the wafer W is viewed in plan. In addition, a plurality of bumps B are located in the generation area SA. For example, an area per unit length L (predetermined length) obtained by triple the short width of one chip C is given as an example. A position where the number m of bumps B to be simultaneously pressed with respect to the central axis CT is maximum (in FIG. 8, m = 9) is the generation area SA.
(2) Deformation of the pressure roll R when the adhesive sheet H is applied When the central axis of the pressure roll R passes directly above the bump B, the lower surface side of the pressure roll R is elastically deformed so as to be recessed at the protruding position of the bump B. . At this time, when the number of bumps B simultaneously pressed by the pressing roll R is relatively small, the lower surface side of the pressing roll R is recessed and deformed so as to follow the protruding shape of the bump B as shown in FIG. That is, the concave deformation amount r1 on the lower surface of the pressing roll R is substantially the same as the protrusion height b1 of the bump B, and the drag force against the pressing force of the pressing roll R is generated by each bump B and the wafer W surface W1. However, when the number of bumps B simultaneously pressed by the pressing roll R increases, the drag per bump B decreases, and the deformation amount of the dent deformation decreases. Then, as shown in FIG. 13B, the depression deformation amount r2 of the pressing roll R becomes smaller than the protrusion height b1 of the bump B, and the pressing force against the adhesive sheet H on the wafer W surface W1 other than the bump B is reduced. Will be reduced.
(3) Summary of (1) and (2) Accordingly, considering (1) and (2) comprehensively, the number of bumps B arranged substantially parallel to the extending direction of the central axis CT of the pressing roll R In the generation area SA where there is a large amount, the dent deformation amount of the pressing roll R becomes small. As a result, the pressing roll R presses only the bumps B so that almost no pressing force is applied to the wafer W surface W1, and as a result, the adhesive sheet H is incompletely applied to the wafer W surface W1 in the generation area SA. It is considered that bubbles A are generated.
Here, it seems that if the pressing force of the entire pressing roll R is increased, the dent deformation amount can be increased to avoid the generation of bubbles A. In this case, however, the wafer W is cracked or bent. It causes another inconvenience that it becomes easy.
Therefore, the present inventor has focused on the number of bumps B pressed by the pressing roll R at the same time, and has devised the configuration and conditions of a sticking device that can reduce the number.

[Object of invention]
The present invention has been devised by paying attention to such inconveniences, and an object of the present invention is to provide a sheet sticking device capable of preventing the generation of bubbles between the surface of a wafer and an adhesive sheet. It is in.

In order to achieve the above object, the present invention is a sheet sticking device for sticking an adhesive sheet to a front surface side of a semiconductor wafer having a plurality of bumps on the front surface side,
Including a pressing roll for applying a pressing force by rolling on an adhesive sheet disposed on the surface of the semiconductor wafer;
The central axis of the pressing roll is in a direction to reduce the maximum value of the number of bumps to which a pressing force is applied simultaneously with respect to the central axis of a predetermined length when the semiconductor wafer is viewed in plan during the bonding of the adhesive sheet. It is configured to be directed in a direction shifted by a predetermined angle in the plane.

In the present invention, it is preferable to further include a holding device that holds the semiconductor wafer, and a control unit that stores the angle in advance and controls driving of the holding device.
Further, the image forming apparatus further includes an identification unit that automatically determines the angle by detecting the bump, the identification unit simultaneously detecting a bump position and a formation region based on detection data of the sensor. It is preferable to include a detection unit that detects the direction of the central axis that maximizes the number of bumps to which the pressing force is applied, and a direction determination unit that determines the direction of the central axis that is shifted with respect to the direction.

  According to the present invention, the adhesive sheet can be stuck by setting the direction of the central axis of the pressing roll so that the number of bumps to which the pressing force is simultaneously applied by the pressing roll is reduced. Thereby, it can suppress that the resistance with respect to the pressing force of the press roll in each bump falls, and it becomes possible to dent and deform | transform so that a press roll may follow the protrusion shape of a bump. As a result, the pressing force from the pressing roll is always applied not only to each bump but also to the wafer surface, and it is possible to prevent the generation of bubbles between the bumps due to insufficient pressing force as in the prior art.

  In addition, when the wafer surface is diced first, the wafer surface and bumps can be sealed by the adhesive sheet even in the grinding process on the back surface of the wafer, and contamination due to the intrusion of cooling water, etc. It can be avoided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic plan view according to the present embodiment. In this figure, a sheet sticking device 10 is configured as a device for sticking an adhesive sheet H to a surface W1 of a wafer W. The sheet sticking device 10 includes a cassette 11 for storing wafers W, an alignment device 13 for aligning wafers W taken out from the cassette 11 via a robot 12, and a transfer device 15 from the alignment device 13 via a transfer device 15. A holding device 16 that holds the wafer W moved in the X direction (left direction in FIG. 1), a pressing roll R that rolls on the adhesive sheet H to apply a pressing force, and an adhesive that is attached to the wafer W. A cutting device 20 that cuts a predetermined position of the sheet H, and the cutting device 20 cuts off the sheet sticking portion 17 (see FIG. 4) that attaches the adhesive sheet H onto the wafer W held by the holding device 16. And a recovery device 55 for recovering the adhesive sheet H.

The wafer W is housed in the cassette 11 with the surface W1 formed as a circuit surface and the surface W1 on the upper surface side. As shown in an enlarged manner in FIG. 2, the configuration of the wafer W is the same as that described in the conventional example (FIG. 8). Therefore, here, the same reference numerals are given to the respective components of the wafer W, and redundant description is omitted.
The bump B will be described in detail. Although not particularly limited, in the present embodiment, the number of bumps B and the position of formation of the bumps B in each chip C are the same. One bump B is formed at the center in the left-right direction in the upper part of each chip C in FIG. 2, and three bumps B are formed at substantially equal intervals along the left and right at the upper and lower intermediate parts in FIG. Two are provided along the left and right in the lower part of FIG. When viewed as the entire wafer W, the upper, upper and lower intermediate portions and the lower bumps B are arranged at substantially equal intervals along the left-right direction in FIG.

  The adhesive sheet H is formed in a strip shape having a width dimension larger than the diameter dimension of the wafer W before being attached to the wafer W, and the sheet sticking portion with the release sheet P temporarily attached to the adhesive surface. 17 is wound around a supply reel described later.

  The robot 12 includes a substantially cylindrical base 22, a vertical movement mechanism 23 erected on the base 22, and an articulated arm 24 provided at the upper end of the vertical movement mechanism 23 and rotatable in a substantially horizontal plane. And a distal end portion 25 having a substantially C-shaped or substantially U-shaped planar shape attached to the distal end of the arm 24. The robot 12 sucks and holds the lower surface side of the wafer W accommodated in the cassette 11 by the front end portion 25 and transfers the wafer W to the alignment device 13 in this state.

  As shown in FIG. 3, the alignment device 13 is connected to a pump or the like (not shown) to hold the wafer W on the upper surface, and supports and holds the holding table 27 from below. A rotation mechanism 28 that rotates the table 27 in a plane, an XY movement mechanism 29 provided on the lower side of the rotation mechanism 28, and a substantially central portion of the holding table 27. The lifter 30 includes a cylindrical member 30 </ b> A that can protrude from the upper surface, and a sensor 31 that is provided on the upper surface side of the holding table 27 and includes a camera that detects a V notch or the like of the wafer W. The cylindrical member 30 </ b> A has an upper surface capable of sucking and holding the wafer W in the same manner as the holding table 27, and is provided so as to be able to be raised and lowered from a position that is substantially flush with the holding table 27. Therefore, when the cylindrical member 30 </ b> A is protruded from the upper surface of the holding table 27, the wafer W is raised from the holding table 27, and a space is secured between the upper surface of the holding table 27 and the wafer W.

  The wafer W that has been aligned by the alignment device 13 is transferred to the transfer device 15 and transferred to the holding device 16. The transfer device 15 sucks and holds the wafer W from the lower surface side, supports an arm member 33 having a substantially C-shaped or substantially U-shaped planar shape on the distal end side, and supports a proximal end side of the arm member 33. The Y-axis robot 34 that moves the arm member 33 along the Y-axis, and the X-axis robot 35 that supports the Y-axis robot 34 and moves the Y-axis robot 34 and the arm member 33 along the X direction. It is comprised by.

  The holding device 16 has substantially the same structure as the alignment device 13 except that the movement range in the Y direction is increased and the sensor 31 is omitted. Therefore, the description is omitted here assuming that the same reference numerals are used.

  As shown in FIG. 4, the sheet pasting portion 17 extends from the supply reel 37 that holds the original roll wound with the adhesive sheet H temporarily attached to the release sheet P, and the supply reel 37. A guide roller 38 and a tension roller 39 for guiding the adhesive sheet H to the pressing roll R, a take-up reel 40 for taking up the release sheet P peeled from the adhesive sheet H, and a space between the take-up reel 40 and the tension roller 39 And a drive roller 42 that applies a feeding force to the release sheet P. The tension roller 39, the take-up reel 40, and the drive roller 42 are applied with a driving force for feeding the sheets H and P through driving means such as a motor (not shown). Further, the tension roller 39 and the drive roller 42 are provided with pinch rollers 43 and 44 in contact therewith, and a guide roller 45 is provided between the pinch roller 44 and the take-up reel 40.

  The pressing roll R is configured by using a resin material such as silicon, and the surface side thereof is provided so as to be elastically deformable. The pressing roll R is rotatably supported by holders 47 at both ends. The holder 47 is connected to a cylinder 48, and the pressing roll R is moved up and down by driving the cylinder 48.

  Here, a pair of chucks 49, 49 capable of holding the adhesive sheet H is provided between the pressing roll R and the cutting device 20, and these chucks 49, 49 are arranged on both sides in the width direction of the adhesive sheet H, respectively. ing. The chucks 49 and 49 are connected to the vertical movement cylinders 50 and 50, respectively, so as to be movable up and down. The cylinders 50 and 50 for vertical movement are respectively supported by sliders 51 oriented in the X direction (the direction orthogonal to the paper surface in FIG. 4), so that the chucks 49 and 49 are separated from and approach each other along the X direction. When the adhesive sheet H is attached to a wafer, tension is applied in the width direction of the adhesive sheet H so that wrinkles do not occur.

  The cutting device 20 includes an ultrasonic cutter 53 capable of cutting the adhesive sheet H, and a moving mechanism 54 that supports the ultrasonic cutter 53 and moves the ultrasonic cutter 53 in the X direction and the vertical direction. Has been. The cutting device 20 first cuts the adhesive sheet H attached to the wafer W in the width direction (X direction) of the adhesive sheet H by driving the moving mechanism 54, and then the ultrasonic cutter 53 at the outer peripheral position of the wafer W. And the holding table 27 of the holding device 16 is rotated to cut the adhesive sheet H along the outer periphery of the wafer W. Then, the adhesive sheet H cut off by the cutting is recovered by the recovery device 55.

  Next, the sticking process of the adhesive sheet H by the sheet sticking apparatus 10 will be described.

  The wafer W accommodated in the cassette 11 is sucked and held from the lower surface side by the tip portion 25 of the robot 12 and moved onto the alignment device 13. At this time, the lifter 30 of the alignment apparatus 13 is in a state in which the cylindrical member 30A protrudes from the holding table 27, and holds the wafer W on the upper portion of the cylindrical member 30A. Thereafter, the tip 25 of the robot 12 is retracted from between the wafer W and the holding table 27, and then the cylindrical member 30 </ b> A is lowered to hold the wafer W on the holding table 27 by suction. Then, the camera 31 detects a V notch or the like while moving the wafer W via the rotation mechanism 28 and the XY movement mechanism 29, and performs alignment so that the dicing line DL of the wafer W is along the X direction and the Y direction. .

  After the alignment, the wafer W is lifted through the lifter 30 of the alignment device 13, and the lower surface side thereof is sucked and held by the arm member 33 of the transfer device 15 and transferred to the holding device 16. At this time, the holding device 16 is in a state in which the holding table 27 is rotated counterclockwise by an angle θ, and, like the alignment device 13, is in a state where the cylindrical member 30A of the lifter 30 protrudes. Then, after the wafer W is sucked and held on the holding table 27 from the arm member 33 of the transfer device 15 via the lifter 30 of the holding device 16, the holding table 27 is rotated clockwise by an angle θ. Thereafter, the holding device 16 moves to the left side in FIG. 4 along the Y direction.

  When the left end side in FIG. 4 of the holding table 27 in the holding device 16 reaches the position below the chucks 49, 49, the movement of the holding device 16 along the Y direction is stopped. At this time, while the chucks 49 and 49 hold both sides in the width direction of the adhesive sheet H, a force to separate the chucks 49 and 49 from each other in the X direction is applied via the slider 51, so that the adhesive sheet H is moved in the width direction. Has been expanded. In this state, as shown in FIG. 5A, the pressing roll R and the chucks 49 and 49 are lowered and bonded to the outer peripheral portion of the wafer W (the left end portion in FIG. 5B) via the pressing roll R. Press the sheet H. At this time, the chucks 49 and 49 release the holding of the adhesive sheet H, and the tension roller 39 rotates in the feeding direction to relieve the tension of the adhesive sheet H disposed on the surface W1 side of the wafer W. Thereafter, as shown in FIG. 5C, by moving the holding device 16 in the left direction in the figure, the pressing roll R rolls on the adhesive sheet H to apply a pressing force, and the wafer W It sticks so that the sticking area with the adhesive sheet H may gradually expand. Then, as shown in FIG. 5D, when the adhesive sheet H is pasted on the entire surface W1 of the wafer W, the movement of the holding table 27 is stopped and the adhesive sheet H is held by the chucks 49 and 49. Thereafter, the adhesive sheet H is cut in the width direction by the ultrasonic cutter 53 of the cutting device 20.

  Thereafter, while moving the wafer W by the holding device 16, the ultrasonic cutter 53 is moved to the outer peripheral position of the wafer W via the moving mechanism 54 of the cutting device 20, the holding table 27 of the holding device 16 is rotated, and the ultrasonic wave is moved. The adhesive sheet H attached to the wafer W by the cutter 53 is cut along the outer periphery of the wafer W. By this cutting, the unnecessary adhesive sheet H that protrudes outside the wafer W is cut off and recovered by the recovery device 55. Then, after the wafer W is lifted by the lifter 30 of the holding device 16, the wafer 11 is accommodated in the cassette 11 via the robot 12.

  Here, the above-described angle θ, the state of the pressing roll R during application of the adhesive sheet H, and the like will be further examined while comparing with the conventional example shown in FIG.

Here, with respect to the wafer W of the present embodiment, the direction of the central axis CT of the pressure roll R of the conventional example is set to a unit length L that is three times the short width of one chip C as shown in FIG. With respect to the central axis CT, the number m of bumps B that overlap at the same time becomes the maximum (m = 9).
Assuming that the central axis at this time is the maximum central axis CTmax (see FIG. 2), in this embodiment, the central axis CT is set such that the central axis CT is shifted by an angle θ (about 30 °) with respect to the maximum central axis CTmax. ing. Thus, by rotating the holding table 27 of the holding device 16 and setting the orientation of the wafer W, when the wafer W is viewed in plan during the bonding of the adhesive sheet H, the pressure roll R is compared with the conventional example. The central axis CT is oriented in a direction shifted about 30 ° counterclockwise in the plane. According to the direction of the central axis CT, as shown in FIG. 2, the number m of bumps B that overlap simultaneously with the central axis CT having a unit length L that is three times the short width of one chip C. At most, m = 4, and the number m is reduced to about half or less compared to the conventional example (m = 9, see FIG. 5B). That is, during the application of the adhesive sheet H, the maximum value of the number m of the bumps B to which the pressing force is simultaneously applied to the central axis CT having the length L can be reduced.
By the way, as shown in FIGS. 6A and 6B, when the pressing force of the entire pressing roll R is F, and the resistance force per bump B against the pressing force F is an equation for obtaining the resistance f. Is as follows.
Drag f = pressing force F / number m
In this equation, if the pressing force F is constant, the drag force f can be increased by decreasing the number m. Therefore, in the present embodiment, the number m is about half that of the conventional example, so that the drag force f can be increased about twice. Thus, during the application of the adhesive sheet H, the pressing roll R is deformed in a dent so that it always follows the protruding shape of the bump B, that is, the dent deforms in the same manner as in FIG. It becomes possible to stably apply the pressing force of the pressing roll R to the surface W1 of the wafer W.

  The angle θ for rotating the wafer W via the holding device 16 can be stored in advance in a control unit (not shown) that controls the driving of the holding device 16, and depends on the position and number of bumps B on the wafer W. Settings can be changed as appropriate.

Therefore, according to such an embodiment, as shown in FIG. 7, it is possible to avoid the generation of bubbles between the adhesive sheet and the surface W1 of the wafer W, and it is easy to bring them into close contact with each other. Can be maintained. As a result, inconveniences such as the bump B and the surface of the wafer W being wetted by the cooling water, fouling, a product defect of the chip C and the like and lowering the yield in the subsequent process do not occur. In addition, the extremely thin wafer W by grinding prevents the thickness of the chip C from becoming unstable due to the swelling of the wafer W (see FIG. 12) in the generation area SA of the bubbles A, and is stable. Product supply can be performed.
Further, by rotating the holding table 27 of the holding device 16, the direction of the central axis CT of the pressing roll R can be easily shifted with respect to the aligned position of the wafer W.

The best configuration, method and the like for carrying out the present invention have been disclosed in the above description, but the present invention is not limited to this.
That is, the invention has been illustrated and described with particular reference to particular embodiments, but it should be understood that the above-described embodiments are not deviated from the technical idea and scope of the invention. On the other hand, those skilled in the art can make various modifications in shape, quantity, material, and other detailed configurations.
Therefore, the description limited to the shape disclosed above is an example for easy understanding of the present invention, and does not limit the present invention. The description by the name of the member which removed the limitation of part or all of the limitation is included in the present invention.

  For example, when measuring the number m, the length of the central axis CT serving as a reference is not limited to the unit length L described above and can be variously changed. For example, the short width or length of one chip C It is good also as the length etc. which made the dimension width n times (n> = 2). In short, the length of the central axis CT is the same in the direction in which the number m is maximum and the direction shifted with respect to the direction, and it is sufficient that the number m in these directions is comparable.

  For example, the setting of the angle θ to be shifted can be arbitrarily changed, such as 45 ° or 60 °, as long as the number m is not maximized.

  Further, although the wafer W is rotated by the angle θ through the holding device 16, the wafer W may be rotated by the alignment device 13. In this case, after the alignment is completed, the wafer W is rotated by the angle θ through the alignment device 13, and then transferred to the holding device 16 by the transfer device 15. According to this, the rotation operation of the wafer W can be concentrated on the alignment device 13, and the rotation mechanism 28 of the holding device 16 can be omitted.

  Moreover, in the said embodiment, before sticking the adhesive sheet H, it is good also as a structure which added the identification means which determines the said angle (theta) automatically by detecting the bump B. FIG. As this identification means, a sensor such as a camera that can detect the position and formation area of the bump B, and a detection means that detects the direction of the central axis that maximizes the number m based on detection data of the sensor, A configuration provided with direction determining means for obtaining the direction of the central axis CT shifted with respect to the direction can be exemplified.

  Further, when the pressing roll R applies a pressing force to the adhesive sheet H, the wafer W and the pressing roll R may be moved relative to each other so that the pressing roll R reciprocates on the wafer W.

  The present invention is mainly used for a sheet sticking apparatus for sticking an adhesive sheet to a semiconductor wafer having bumps.

The schematic plan view of the sheet sticking apparatus of this embodiment. The partial enlarged plan view of the semiconductor wafer which stuck the adhesive sheet. The right view of the alignment apparatus of FIG. The schematic front view of a sheet sticking part. (A)-(D) are explanatory drawings of the process of sticking an adhesive sheet on a semiconductor wafer. The schematic diagram for demonstrating the pressing force of a press roll, and the drag of a bump. The expanded sectional view which follows the AA line of FIG. The top view similar to FIG. 2 which concerns on a prior art example. The elements on larger scale of FIG. Sectional drawing which follows the BB line of FIG. Sectional view after grinding the semiconductor wafer of FIG. Sectional drawing which follows the CC line | wire of FIG. (A) And (B) is an expanded sectional view of the state to which the pressing roll gave pressing force.

Explanation of symbols

10 Sheet pasting device B Bump CT Center axis H Adhesive sheet W Semiconductor wafer W1 Surface

Claims (3)

A sheet sticking device for sticking an adhesive sheet to the surface side of a semiconductor wafer provided with a plurality of bumps on the surface side,
Including a pressing roll for applying a pressing force by rolling on an adhesive sheet disposed on the surface of the semiconductor wafer;
The central axis of the pressing roll is in a direction to reduce the maximum value of the number of bumps to which a pressing force is applied simultaneously with respect to the central axis of a predetermined length when the semiconductor wafer is viewed in plan during the bonding of the adhesive sheet. A sheet sticking device, wherein the sheet sticking device is directed in a direction shifted by a predetermined angle in a plane. The sheet sticking apparatus according to claim 1, further comprising: a holding device that holds the semiconductor wafer; and a control unit that stores the angle in advance and controls driving of the holding device. It further includes an identification unit that automatically determines the angle by detecting the bump, and the identification unit simultaneously detects a position and a formation area of the bump and a pressing force based on detection data of the sensor. And a direction determining means for determining the direction of the central axis shifted with respect to the direction. The sheet sticking apparatus according to claim 1 or 2.

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