JP2006019500A - Method and apparatus of bonding protective tape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for bonding protective tape via a bonding roller with its periphery elastically deformable to the surface of a semiconductor wafer adsorbed and held by a chuck table, wherein stress on the bonded protective tape in the direction of shrinkage is decreased to the utmost so that the wafer after thickness reduction suffers from less warpage or distortion. <P>SOLUTION: In this method for bonding protective tape T via a bonding roller 25 with its periphery elastically deformable to the surface of a semiconductor wafer W adsorbed and held by a chuck table 10, the protective tape T is bonded to the periphery of the wafer W before it is bonded to the central part of the wafer W. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and apparatus for attaching a protective tape to a surface of a semiconductor wafer before back grinding.

As a means for thinning a semiconductor wafer (hereinafter simply referred to as a wafer), the back surface of the wafer is processed by using a mechanical method such as grinding or polishing, or a chemical method using etching, and the thickness is reduced. When the wafer is thinned and the wafer is processed using these methods, a protective tape is attached to the surface of the wafer in order to protect the wafer surface on which the wiring pattern is formed. And as a means to affix the protective tape on the wafer, while supplying the roll-shaped band-like protective tape to the wafer surface, the protective roller is rolled on the wafer surface to move the protective tape to the wafer surface. A means of applying the tape sequentially from one end and then cutting the protective tape along the periphery of the wafer is widely used (see, for example, Patent Document 1).
JP 2002-57208 A

  If the protective tape is applied to the surface of the wafer by rolling and moving the application roller as described above, the protective tape will be applied to the wafer surface while being slightly stretched by the pressing force of the application roller. The shrinking stress is accumulated. In this case, the thick wafer before the back grinding process has rigidity capable of resisting stress in the shrinking direction of the protective tape. However, when the thickness is reduced by the back grinding process, the rigidity of the wafer is reduced. As a result, it becomes impossible to resist the stress in the shrinking direction of the protective tape, causing warping and distortion.

  The present invention has been made paying attention to such a situation, and it is possible to reduce the stress in the shrinking direction of the attached protective tape as much as possible to reduce the warpage and distortion of the wafer after thinning. It aims at providing the protective tape sticking method and protective tape sticking apparatus which can be performed.

  A first invention is a protective tape attaching method for attaching a protective tape to a surface of a semiconductor wafer attracted and held on a chuck table via an attaching roller whose outer peripheral surface is elastically deformable. Is also characterized in that a protective tape is applied in advance.

  According to this, compared to the case where the protective tape is applied from the central part to the outer peripheral part, the deformation of the protective tape in the wafer outer peripheral direction is less, and the protective tape is applied in a state where the shrinkage stress in the wafer central direction is small. Will be.

  Therefore, according to the first invention method, since the protective tape is applied in a state where the shrinkage stress toward the wafer center is small, the protective tape is obtained in a state where the thickness of the wafer is reduced by back grinding and its rigidity is reduced. It is possible to reduce warpage and distortion caused by the shrinkage stress.

  According to a second aspect of the present invention, there is provided a protective tape attaching apparatus for attaching a protective tape to a semiconductor wafer adsorbed and held on a chuck table via an adhesive roller whose outer peripheral surface is elastically deformable, wherein the central portion of the adhesive roller has a smaller diameter than both ends. It is characterized by being.

  According to this structure, the sticking roller pressed in parallel to the wafer is compressed and deformed at both end portions having a large diameter ahead of the central portion having a small diameter, and the protective tape is advanced from the outer peripheral portion of the wafer. Then it will be pasted.

  As described above, the protective tape applied in advance from the outer peripheral portion of the wafer has less stretching deformation in the wafer outer peripheral direction than the case where the protective tape is applied from the central portion to the outer peripheral portion, for example. It will be affixed with a small amount of shrinkage stress in the direction.

  Therefore, according to the second invention, the first invention can be suitably implemented.

  According to a third aspect of the present invention, there is provided a protective tape attaching apparatus for attaching a protective tape to a semiconductor wafer adsorbed and held on a chuck table via an adhesive roller whose outer peripheral surface can be elastically deformed. And the hardness of the elastic layer on both ends of the sticking roller is lower than the hardness of the elastic layer in the center.

  According to this configuration, since the hardness of both ends of the elastic layer of the sticking roller pressed against the wafer is lower than the hardness of the central portion, when the roller is pressed downward, the both ends having low hardness are advanced by the roller. By being spread forward and backward in the direction, both ends of the roller have a larger ground contact area with the wafer than the center, and the both ends of the roller can stick the tape ahead of the center. As a result, the protective tape is applied in advance from the outer peripheral portion of the wafer.

  Therefore, according to the third invention, the first invention can be suitably implemented.

  According to a fourth aspect of the present invention, there is provided a protective tape attaching apparatus for attaching a protective tape to a semiconductor wafer adsorbed and held on a chuck table via an adhesive roller whose outer peripheral surface is elastically deformable. In addition, the wafer mounting surface of the chuck table is concavely curved so as to be lower than the outer peripheral portion.

  According to this configuration, the wafer is pressed by the affixing roller while being concavely curved along the wafer placement surface, and the protective tape is affixed in advance from the outer peripheral portion of the wafer.

  Therefore, according to the second invention, the first invention can be suitably implemented.

  According to a fifth aspect of the present invention, there is provided a protective tape attaching apparatus for attaching a protective tape to a semiconductor wafer adsorbed and held on a chuck table via an adhesive roller whose outer peripheral surface is elastically deformable. The elastic layer is covered and configured to have the same diameter over the entire length, and the thickness of the elastic layer on both ends of the sticking roller is larger than the thickness of the elastic layer in the central portion. .

  According to this configuration, since the thickness of both ends of the elastic layer of the sticking roller pressed in parallel with the wafer is larger than the thickness of the center portion, when the roller is pressed downward, both end portions having a large thickness When the roller is pushed forward and backward in the moving direction of the roller, both ends of the roller have a larger ground contact area with the wafer than the center, and the tape is attached to both ends of the roller ahead of the center. Can do. As a result, the protective tape is applied in advance from the outer peripheral portion of the wafer.

  Therefore, according to the second invention, the first invention can be suitably implemented.

  According to the present invention, since the protective tape is attached to the outer peripheral portion of the semiconductor wafer prior to the central portion, the protective tape is less likely to be stretched and deformed in the wafer outer peripheral direction. As a result, the protective tape can be affixed in a state where the shrinkage stress toward the wafer center is small, and the warpage and distortion of the wafer after the thinning can be reduced.

  An embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1 is a perspective view showing the overall configuration of the protective tape attaching device. This protective tape affixing device 1 includes a wafer supply unit 3 in which a cassette C1 containing a semiconductor wafer (hereinafter simply referred to as “wafer”) W is loaded, and a protective tape T on the surface. And a wafer recovery unit 4 that recovers the processed wafer W ′ that has been pasted and cut out. A wafer transfer mechanism 6 having a robot arm 5 is disposed between the wafer supply unit 2 and the wafer recovery unit 3, and an alignment stage 7 is disposed on the right side of the base 2. Is provided with a tape supply unit 8 for supplying the protective tape T toward the wafer W. In addition, a separator collection unit 9 that collects only the separator s from the protective tape T with a separator supplied from the tape supply unit 8 is disposed diagonally to the right of the tape supply unit 8. Then, on the left side of the alignment stage 7, a chuck table 10 on which the wafer W is placed and sucked and held, a tape sticking unit 11 for sticking the protective tape T to the wafer W held on the chuck table 10, and the wafer W And a tape peeling unit 12 for peeling off the unnecessary tape T ′ after being cut and pasted to the wafer W, and above that, the protective tape T stuck to the wafer W is cut and cut along the outer shape of the wafer W A tape cutting mechanism 13 is provided. In addition, a tape collection unit 14 that winds and collects the unnecessary tape T ′ that has been peeled off by the tape peeling unit 12 is disposed on the upper left side of the base 2. Further, a protective tape T before being attached to the wafer W and a static electricity removing device 15 for removing static electricity from the unnecessary tape T ′ before recovery are provided on both sides of the chuck table 10.

  Hereinafter, each mechanism will be specifically described.

  The wafer supply unit 3 includes a cassette base 17 that can be moved up and down, and a cassette C1 in which wafers W with a pattern surface facing upward are inserted and stored in multiple stages in a horizontal posture is placed on the cassette base 17.

  The robot arm 5 provided in the wafer transfer mechanism 6 is configured to be able to move forward and backward horizontally and to be driven and swung as a whole. At the tip of the robot arm 5, a horseshoe-shaped vacuum suction type wafer holder 5a is provided, and the wafer holder 5a is inserted into the gap between the wafers W stored in multiple stages in the cassette C1. Is sucked and held from the back surface, and the wafer W sucked and held is pulled out from the cassette C1 and conveyed in the order of an alignment stage 7, a chuck table 10, and a wafer recovery unit 4 to be described later.

  The alignment stage 7 is configured to align the wafer W loaded and placed by the wafer transport mechanism 6 based on an orientation flat or notch formed on the outer periphery thereof.

  The chuck table 10 vacuum-sucks the wafer W transferred from the wafer transfer mechanism 6 and placed in a predetermined alignment posture. Further, a cutter running groove 19 is formed on the upper surface of the chuck table 10 for cutting a protective tape T by turning a cutter 18 of a tape cutting mechanism 13 (to be described later) along the outer shape of the wafer W.

  The tape supply unit 8 winds and guides the protective tape T with a separator fed from a supply bobbin 22 pivotally supported on the vertical wall 21 of the apparatus main body around the group of guide rollers 23, and the protective tape T from which the separator s has been peeled off. It is configured to be guided to the tape adhering unit 11, and is configured so as to give an appropriate rotational resistance to the supply bobbin 22 so that excessive tape feeding is not performed.

  The separator collection unit 9 is rotatably driven in the winding direction by a drive mechanism (not shown) on the back of the vertical wall, with a recovery bobbin 24 that winds up the separator s peeled off from the protective tape T supported on the vertical wall 21 of the apparatus main body. It has become so.

  The tape affixing unit 11 is provided with an affixing roller 25 facing forward and horizontally, and is reciprocated horizontally horizontally by a slide guide mechanism and a screw feed type driving mechanism (not shown) provided on the back of the vertical wall 21. ing.

  The tape peeling unit 12 is provided with a peeling roller 26 that faces forward and horizontally, and is reciprocated horizontally by a slide guide mechanism and a screw feed type driving mechanism (not shown) provided on the back of the vertical wall 21. ing.

  The tape collection unit 14 is configured such that a collection bobbin 27 for winding up the unnecessary tape T ′ is pivotally supported on the vertical wall 21 of the apparatus main body and is rotated in the winding direction by a drive mechanism (not shown) on the back of the vertical wall. Yes.

  The wafer collecting unit 4 includes a cassette base 28 that can be moved up and down, and a cassette C2 in which the processed wafers W on which the protective tape T is pasted and the unnecessary tape is cut and removed are inserted and stored in multiple stages in a horizontal posture are stored in the cassette base 28. It is supposed to be placed.

  Next, a series of operations for attaching the protective tape T to the surface of the wafer W using the above-described embodiment apparatus will be described.

  When the cassette C1 storing the wafers W in multiple stages is placed on the cassette table 17 of the wafer supply unit, the cassette table 17 is moved up and down and stopped at a height where the robot arm 5 can take out the wafer W to be taken out. .

  Next, the wafer transfer mechanism 6 turns to insert the wafer holder 5a of the robot arm 5 into the gap between the wafers in the cassette C1, and the robot arm 5 moves the wafer W from the back surface (lower surface) with the wafer holder 5a. The wafer W is taken out by suction, and the wafer W is transferred to the alignment stage 7.

  The wafer W placed on the alignment stage 7 is aligned using an orientation flat or notch, and the aligned wafer W is again sucked and held by the robot arm 5 and transferred to the chuck table 10. Is done.

  The wafer W placed on the chuck table 10 is positioned and attracted and held so that the center thereof is on the center of the chuck table 10. At this time, as shown in FIG. 2, the tape applying unit 11 and the tape peeling unit 12 are waiting at the left initial position, and the cutter 18 of the tape cutting mechanism 13 is waiting at the upper initial position.

  When the alignment of the wafer W is completed, as shown in FIG. 3, the application roller 25 of the tape application unit 11 is lowered, and the tape travels on the wafer W while pressing the protective tape T downward with the application roller 25. It rolls in the direction opposite to the direction (from left to right in the figure), whereby the protective tape T is applied to the entire surface of the wafer W.

  Next, the tape cutting mechanism 13 is lowered, and as shown in FIG. 4, the cutter 18 that has been waiting upward is lowered to the cutting action position and pierced by the protective tape T, and is set at a predetermined height. Stops when lowered to position.

  The cutter 18 lowered to a predetermined height position is driven to rotate around the vertical axis X, and the protective tape T is cut along the wafer outer shape. At this time, a predetermined tension is applied to the protective tape T by the tape applying unit 11 and the tape peeling unit 12.

  When the tape cutting along the outer periphery of the wafer W is completed, the cutter 18 is raised to the original standby position as shown in FIG. Next, the tape peeling unit 12 rolls up and peels off the unnecessary tape T 'remaining cut and cut on the wafer W while moving the wafer W in the direction opposite to the tape running direction.

  When the tape peeling unit 12 reaches the end position of the peeling operation, the tape peeling unit 12 and the tape attaching unit 11 move in the tape running direction and return to the initial position. At this time, the unnecessary tape T ′ is wound around the recovery bobbin 27 and a certain amount of the protective tape T is fed out from the tape supply unit 8.

  This completes a series of operations for attaching the protective tape T to the surface of the wafer W, and this is repeated thereafter.

  In the pasting apparatus for pasting the protective tape as described above, in the present invention, the pasting form is devised so that the protective tape T can be pasted on the wafer W with less shrinkage stress. It is shown below.

[First example]
As shown in FIG. 6, in this example, the sticking roller 25 configured by covering the core shaft 25a with a rubber layer 25b such as urethane rubber has a diameter D1 at the center portion slightly larger than the diameter D2 at both ends. It is set to have a small diameter (for example, about 0.5%), and the outer peripheral surface is smoothly recessed and recessed along its entire length.

  When the sticking process of the protective tape T is performed using the sticking roller 25 as described above, the sticking roller 25 pressed in parallel with the wafer W has both end portions having large diameters ahead of the central portion having a small diameter. The protective tape T is affixed in advance from the outer peripheral portion of the wafer. FIG. 7 shows a plan view of the case where the sticking roller 25 is run in the A direction and the protective tape is attached, and the hatched area in the drawing is an area to be attached in advance.

  As described above, the protective tape T applied in advance from the outer peripheral portion of the wafer has less stretching deformation in the wafer outer peripheral direction than the case where the protective tape T is applied from the central portion to the outer peripheral portion, for example. It is pasted in a state where there is little shrinkage stress in the center direction.

[Second example]
As shown in FIG. 8, in this example, the affixing roller 25 configured by covering the core shaft 25a with a rubber layer 25b such as urethane rubber is formed to have the same diameter over the entire length, and the rubber on both end sides thereof. The hardness of the layer 25b (s) is set lower (softer) than the hardness of the rubber layer 25b (c) in the central portion.

  When the sticking process of the protective tape T is performed using the sticking roller 25 as described above, the sticking roller 25 pressed against the wafer W has a lower hardness than that of the central portion of the elastic layer 25b. When the sticking roller 25 is pressed downward, both end portions of the elastic layer 25b having low hardness are spread forward and backward in the traveling direction of the roller 25, so that both end portions of the roller 25 and the wafer W are compared with the central portion. , And the protective tape T can be applied with the both ends of the roller 25 preceding the center. As a result, the protective tape T is applied in advance from the outer peripheral portion of the wafer W.

[Third example]
As shown in FIG. 9, the pasting roller of this example is formed so that the core layer 25a on the straight axis is covered with an elastic layer 25b of a predetermined hardness to have a uniform thickness, and is formed to have the same diameter over the entire length. The wafer mounting surface S is smoothly recessed and curved so that the central portion thereof is slightly lower than the outer peripheral portion.

  When the protective tape T is applied in this manner as described above, the wafer W is pressed by the adhesive roller 25 in a state of being recessed and curved along the wafer mounting surface S, and the protective tape is the wafer. It is affixed in advance from the outer peripheral part of.

[Fourth example]
As shown in FIG. 10, the sticking roller of this example covers the core shaft 25a with an elastic layer 25b having a uniform hardness over the entire length, is formed to have the same diameter over the entire length, and the central portion of the core shaft 25a is The elastic layer 25b is configured to have a medium-bulge shape with a larger diameter than both end portions, and thus the thickness t2 of the elastic layer 25b on both end portions side of the elastic layer 25b is set larger than the thickness t1 of the elastic layer 25b on the central portion. ing.

  When the sticking process of the protective tape T is performed using the sticking roller 25 as described above, the sticking roller 25 traveling in parallel with the wafer has a thickness at both ends of the elastic layer 25b that is greater than the thickness of the central portion. Since it is large, both ends of the elastic layer 25b having a large thickness are pushed forward and backward in the direction of travel of the roller 25 when the sticking roller 25 is pressed downward, so that both ends of the roller 25 are compared with the center. The ground contact area with the wafer W is increased, and the protective tape T can be attached so that both end portions of the roller 25 precede the center portion. As a result, the protective tape T is applied in advance from the outer peripheral portion of the wafer W.

  FIG. 11 shows actual measurement results obtained by performing the pasting test in the form of each of the above examples. Here, as shown in FIG. 12, the amount of warpage δ is the placement surface of the wafer edge when a wafer W having a diameter of 8 inches is mounted on a flat surface with a protective tape T applied and ground to a thickness of 125 μm. The maximum lift from

  Here, in the first example, a sticking roller 25 having a diameter of 50 mm at both ends, a diameter of 49.75 mm at the center, and a Shore hardness of 70 degrees of the elastic layer 25b is used, and the moving speed of the roller outer periphery is 40 mm / sec. Affixed.

  In the second example, an affixing roller 25 having a diameter of 50 mm, a shore hardness of 85 degrees at both ends of the elastic layer 25b, and a shore hardness of 70 degrees at the center is used, and the moving speed of the outer circumference of the roller is 40 mm. Pasted at / sec.

  In the third example, the wafer mounting surface S is smoothly recessed and curved so that the central portion thereof is slightly lower than the outer peripheral portion, and the wafer W is mounted on the chuck table 5 so as to be in close contact with the wafer mounting surface S. The adhering roller 25 having a diameter of 50 mm and an elastic layer 25b having a Shore hardness of 70 degrees was affixed by rolling and moving at a moving speed of 40 mm / sec on the outer periphery of the roller.

  In the comparative example, the pasting roller 25 having a diameter of 50 mm and an elastic layer having a Shore hardness of 70 degrees was pasted by rolling and moving at a moving speed of 40 mm / sec on the outer periphery of the roller.

  As is clear from the above test results, in the application form of the present invention shown in the first to third examples, the stress in the shrinking direction of the attached protective tape T is reduced, and the amount of warpage of the wafer W is reduced. confirmed.

  In addition, this invention can also be implemented with the following forms.

  (1) As shown in FIG. 13, immediately after the protective tape T is pasted by the pasting roller 25 of the first example, when the auxiliary pasting roller 25 ′ having the same diameter is rolled over the entire length, the wafer center The central part is also securely attached in a state where the shrinkage stress in the direction is small.

  (2) In addition to feeding and attaching the continuous belt-shaped protective tape T wound in rolls as described above, a single wafer protective tape T is supplied to the wafer W one by one and applied. You can also

  (3) The affixing roller 25 has a diameter at the central portion smaller than the diameter at both ends as in the first example, and the hardness of the elastic layer at both ends as in the second example. If the elastic layer is made lower than the hardness of the elastic layer, the protective tape can be more reliably attached to the outer peripheral portion of the semiconductor wafer prior to the central portion.

It is a perspective view which shows the whole protective tape sticking apparatus. It is a schematic front view which shows a tape sticking action | operation. It is a schematic front view which shows a tape sticking action | operation. It is a schematic front view which shows a tape sticking action | operation. It is a schematic front view which shows a tape sticking action | operation. It is a side view of the sticking roller used for the 1st example. It is a top view of a semiconductor wafer showing a pasting result. It is a side view of the sticking roller used for the 2nd example. It is a side view which shows the chuck table and sticking roller which are used for a 3rd example. It is a side view of the sticking roller used for the 4th example. It is a chart which shows a test result. It is a front view which shows the curvature measurement form. It is a perspective view of the principal part which shows another Example.

Explanation of symbols

10 chuck table 25 sticking roller 25a core shaft 25b elastic layer W semiconductor wafer T protective tape

Claims (5)

In the protective tape attaching method of attaching a protective tape to the surface of the semiconductor wafer sucked and held on the chuck table via an attaching roller whose outer peripheral surface is elastically deformable,
A protective tape attaching method, wherein a protective tape is attached to an outer peripheral portion of the semiconductor wafer prior to a central portion. In the protective tape attaching device for attaching the protective tape to the semiconductor wafer sucked and held on the chuck table via an attaching roller whose outer peripheral surface is elastically deformable,
A protective tape sticking apparatus, wherein a central portion of the sticking roller has a smaller diameter than both end portions. In the protective tape attaching device for attaching the protective tape to the semiconductor wafer sucked and held on the chuck table via an attaching roller whose outer peripheral surface is elastically deformable,
The core roller is covered with an elastic layer to constitute the sticking roller, and the hardness of the elastic layer on both ends of the sticking roller is lower than the hardness of the elastic layer at the center. Protective tape pasting device. In the protective tape attaching device for attaching the protective tape to the semiconductor wafer sucked and held on the chuck table via an attaching roller whose outer peripheral surface is elastically deformable,
A protective tape attaching device, wherein the attaching roller has the same diameter over the entire length, and is concavely curved so that the wafer mounting surface of the chuck table is lower than the outer peripheral portion. In the protective tape attaching device for attaching the protective tape to the semiconductor wafer sucked and held on the chuck table via an attaching roller whose outer peripheral surface is elastically deformable,
The sticking roller is configured so that the core shaft is covered with an elastic layer having a uniform hardness so as to have the same diameter over the entire length, and the thickness of the elastic layer on both ends of the sticking roller is set to be equal to that of the elastic layer in the center portion. A protective tape affixing device characterized by being larger than the thickness.

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