Sheet sticking apparatus and sticking method

A sheet sticking apparatus 10 comprises a sheet feed-out unit 12 for feeding out an adhesive sheet S to a position facing a surface of a semiconductor wafer W, and a press roller 14 for imparting a press force to the adhesive sheet S to stick the adhesive sheet S to the wafer W. The sheet feed-out unit 12 includes a tension measuring means 35 for measuring the tension of the adhesive sheet S between a feed-out head 49 and the press roller 14. The tension measuring means 35 maintains the tension to a constant level to prevent catching of air bubbles between the adhesive sheet S and the wafer W as well as to prevent warp deformation of the wafer stuck with the sheet.

FIELD OF THE INVENTION

The present invention relates to a sheet sticking apparatus and a sticking method, particularly to a sheet sticking apparatus and a sticking method capable of sticking a sheet, when sticking a sheet to a plate-like object such as a semiconductor wafer, precisely to a predetermined position of the object.

BACKGROUND OF THE ART

Conventionally, semiconductor wafers (hereinafter, simply referred to as “wafer”) are stuck with a protective sheet for protecting circuit surface thereof, and stuck with an adhesive sheet for die bonding on the rear surface thereof.

As the sheet sticking method described above, the following sticking method is known. That is, using a raw strip sheet in which a strip of adhesive sheet is temporarily stuck on a strip of release liner, the adhesive sheet is peeled off from the release liner, stuck onto a wafer, and then cut off along the periphery of the wafer (refer to, for example, patent document 1).

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

However, in a sheet sticking apparatus disclosed in the patent document 1, there has not been positively employed such an arrangement so as to maintain constant tension during the operation of sticking an adhesive sheet onto a wafer.

Therefore, when the adhesive sheet is stuck with shortage of tension, such disadvantages may be resulted in that creases are generated on the adhesive sheet and/or air bubbles are caught between the adhesive sheet and the wafer. On the other hand, when an excessive tension is given to the adhesive sheet, such a disadvantage may be brought in that warp deformation is caused on the wafer after sticking the adhesive sheet.

Also, in the sheet sticking apparatus disclosed in the patent document 1, a set of guide rollers28for feeding out the adhesive sheet to a position facing the surface of the wafer is disposed. Since the guide rollers28nip constantly the adhesive sheet throughout sticking operation, cutting operation and peeling operation of the adhesive sheet, a line-like dent portion is formed on the adhesive layer of the adhesive sheet. Therefore, in the case of plate-like object such as the wafer, which is subjected to a grinding process to obtain an extremely thin thickness of several dozens micron, a sheet with a trace of line-like dent portion may cause an unevenness in thickness, or breakage of wafer in the grinding process. Thus, the area with the hollow portion cannot be used for the area to be stuck to the wafer. Although the sheet can be fed so that the area with the hollow portion is excluded, that case causes such a disadvantage that the sheet is consumed wastefully.

Object of the Invention

The present invention has been proposed in view of the above disadvantages. It is an object of the present invention to provide a sheet sticking apparatus and a sticking method capable of sticking a sheet by continuously measuring the tension of the sheet to maintain the tension constantly at a preset value during performing the sticking operation while giving a press force to the sheet with a press roller.

Also, another object of the present invention is to provide a sheet sticking apparatus and a sticking method capable of significantly suppressing wasteful consumption of the sheet by feeding the sheet of a length corresponding to the size of the plate-like object.

Means for Solving Problems

In order to achieve the above object, the present invention adopts such an arrangement that a sheet sticking apparatus, comprising: a sheet feed-out unit for feeding out a sheet to a position facing a surface of a plate-like object; and a press roller for imparting a press force to the sheet to stick the sheet from one end toward the other end of the plate-like object, wherein

the sheet feed-out unit includes a tension measuring means for measuring the tension of the sheet between the sheet feed-out unit and the press roller, and the tension measuring means measures the tension constantly to maintain a constant tension while sticking the sheet to the plate-like object with the press roller.

In the present invention, the tension measuring means preferably includes a load cell and a tension measuring roller and is arranged such that when the load cell detects a change of the tension, the position of the tension measuring roller is shifted to maintain the constant tension.

Also, the present invention adopts such an arrangement that a sheet sticking apparatus, comprising: a sheet feed-out unit for feeding out a sheet to a position facing a surface of a plate-like object; and a press roller for imparting a press force to the sheet to stick the sheet from one end toward the other end of the plate-like object, wherein

the sheet feed-out unit includes a sticking-angle maintaining means, and the sticking-angle maintaining means maintains the sticking angle of the sheet at a constant angle with respect to the plate-like object.

Further, the present invention adopts such an arrangement that the sheet feed-out unit includes a peel plate, the length of the sheet fed out between the front end of the peel plate and the press roller being set to be a little longer than the length from the one end to the other end of the plate-like object.

Furthermore, the present invention adopts such an arrangement that, when the sheet is stuck onto the plate-like object, the front end of the peel plate is positioned at the outside in the vicinity of the other end of the plate-like object.

Further, the present invention adopts such a sheet sticking method, in which a sheet is fed out from a sheet feed-out unit and pressed by a press roller to stick the same onto a plate-like object, and comprises the steps of: measuring the tension constantly while the press roller presses the sheet for sticking; and sticking the sheet onto the plate-like object while maintaining the tension at a constant level via a tension measuring means.

Moreover, the present invention adopts a sheet sticking method, in which a sheet is fed out from a sheet feed-out unit and the sheet is pressed by a press roller to stick the same onto a plate-like object, and comprising the step of sticking the sheet in a state that a sticking angle with respect to the plate-like object is maintained to a constant angle.

Furthermore, the above methods adopt such method that the sheet is stuck in a state that the length of the sheet fed out from the sheet feed-out unit to the press roller is kept a little longer than the length from the one end to the other end of the plate-like object.

Effect of the Invention

According to the present invention, the tension measuring means operates to maintain the constant tension of the sheet, and in this state, the press roller sticks the sheet while imparting the press force to the sheet. Consequently, no slack of the sheet is generated and no excessive tension is imparted thereto. Accordingly, crease generation, air bubble catching and warp deformation of the plate-like object can be avoided.

Also, such arrangement is adopted that the tension measuring roller shifts the position so as to maintain a constant tension in the load cell. Therefore, variation of the tension, which tends to occur accompanied by movement of the press roller, can be easily coped with.

Further, since the sticking angle of the sheet is constantly maintained by the sticking-angle maintaining means, even when the unstuck area of the fed out sheet becomes short as the press roller moves and the sticking of the sheet to the plate-like object progresses, the tension of the sheet can be easily maintained at a constant level.

Furthermore, the sticking is carried out in a state that the length of the sheet fed out between the front end of the peel plate and the press roller is set to be a little longer than the length from the one end to the other end of the plate-like object. Therefore, the area of the sheet continuing to the vicinity of the other end of the plate-like object can be used as the area to be stuck onto the next plate-like object. Accordingly, unused area or margin between the sheet areas stuck on the plate-like objects can be minimized, and thus wasteful consumption of the sheet can be eliminated.

EXPLANATION OF REFERENCE NUMERALS

35tension measuring means

37sticking-angle maintaining means

L raw strip sheet

PS release liner

S adhesive sheet

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1is a front view schematically showing a sheet sticking apparatus according to the embodiment; andFIG. 2is a schematic perspective view thereof. In these figures, a sheet sticking apparatus10comprises: a sheet feed-out unit12disposed in the upper portion of a base11; a table13for supporting a wafer W as a plate-like object; a press roller14for imparting a press force to an adhesive sheet S fed out to the upper surface side of the wafer W to stick the adhesive sheet S to the wafer W; a cutter15for cutting the adhesive sheet S along the outer periphery of the wafer W after sticking the adhesive sheet S to the wafer W; a peeling apparatus16for peeling off unnecessary adhesive sheet S1outside the wafer W from the upper surface of the table13; and a winding apparatus17for winding the unnecessary adhesive sheet S1.

The sheet feed-out unit12comprises: a support roller20for supporting a rolled raw strip sheet L in which the strip of adhesive sheet S is temporarily stuck on one surface of a strip of a release liner PS; a peel plate22with which the raw strip sheet L fed out from the support roller20is sharply folded back to peel off the adhesive sheet S from the release liner PS; a collection roller23for collecting the release liner PS by winding the same; a plurality of guide rollers25to31disposed between the support roller20and the collection roller23; a buffer roller33disposed between the guide rollers25and26; a tension measuring means35disposed between the guide rollers27and28; and a sticking-angle maintaining means37for integrally supporting the peel plate22, guide rollers27,28,29and the tension measuring means35. Note that the guide rollers27and29are concomitantly provided with brake shoes32and42respectively. These brake shoes32and42are arranged so as, when sticking the adhesive sheet S to the wafer W, to be moved toward/away from the corresponding guide roller27,29by means of cylinders38and48respectively, to nip the adhesive sheet S to restrain the feeding thereof.

The tension measuring means35comprises a load cell39and a tension measuring roller40supported by the load cell39and located at the base side of the peel plate22. The tension measuring roller40is pulled by a tension of the adhesive sheet S, which is nipped by the guide roller27and the brake shoe32and is fed out to the press roller14, and the tension is transmitted to the load cell39. And there is such an arrangement that while the load cell39measures the tension of the adhesive sheet S fed out, a feed-out head49, which will be described later, moves downward at an angle inFIG. 1via the sticking-angle maintaining means37so that the tension of the adhesive sheet S is maintained at a constant level.

The sticking-angle maintaining means37is arranged to interact with the press roller14so as to maintain the sticking angle θ of the adhesive sheet S with respect to the wafer W to a constant angle. The sticking-angle maintaining means37comprises: a feed-out head49, including guide rollers27,28and29, the load cell39, the tension measuring roller40, brake shoes32and42, cylinders38and48, the peel plate22and a pair of slide plates43and43for supporting above items; a pair of guide rails45,45for vertically guiding the feed-out head49; and a pair of uniaxial robots46and46for imparting a force to the feed-out head49to move in the vertical direction. The guide rails45and the uniaxial robots46are disposed in an inclined posture enabling to move the feed-out head49vertically along the inclined angle. Note that the peel plate22is supported by a cylinder50disposed at the inner side of the slide plates43enabling to move forward and backward in the X-direction inFIG. 1. Owing to this, the front edge position of the peel plate22can be adjusted in accordance with the diameter of the wafer W.

As shown inFIG. 3, the table13comprises: an outer table51having a substantially square shape in plane view; and an inner table52having a substantially circular shape in plane view. The outer table51is configured in a concave-shape so as to receive the inner table52, and is arranged so as to move in the vertical direction with respect to the base11via a uniaxial robot54. On the other hand, the inner table52is arranged so as to move in the vertical direction with respect to the outer table51via a uniaxial robot56. Accordingly, the outer table51and the inner table52are arranged so as to move integrally in the vertical direction as well as to move in the vertical direction independently each other. Owing to this, the outer table51and the inner table52are arranged to be adjustable to a predetermined level position corresponding to the thickness of the adhesive sheet S and the wafer W.

The press roller14is supported via a portal frame57. On the upper face side of the portal frame57, cylinders59,59are provided. The press roller14is arranged so as to move in the vertical direction owing to the operation of these cylinders59. Incidentally, as shown inFIG. 2, the portal frame57is arranged to be movable in the X-direction inFIG. 1via the uniaxial robot60and the guide rail61.

The cutter15is provided movably in the vertical direction via a lifter (not shown) above the table13. The cutter15comprises: a rotation arm66fixed to a rotation center shaft65, and a cutter blade67supported by the rotation arm66. When the cutter blade67is rotated around the rotation center shaft65, the adhesive sheet S can be cut along the outer periphery of the wafer W.

As shown inFIGS. 1,4and5, the peeling apparatus16comprises a small diameter roller70and a large diameter roller71. A moving frame F supports the small diameter roller70and the large diameter roller71. The moving frame F comprises a front frame F1and a rear frame F2, which are opposing to each other in the Y-direction inFIG. 2, the rear frame F2being connected to the front frame F1via a connecting member73. The rear frame F2is supported by a uniaxial robot75, while the front frame F1is supported by the guide rail61. Owing to this, the moving frame F is movable in the X-direction inFIG. 2. An arm member74supports the large diameter roller71as shown inFIG. 1. The arm member74is arranged so that a cylinder78can move the large diameter roller71in the direction closer to/away from the small diameter roller70.

The winding apparatus17comprises: a drive roller80supported by the moving frame F; and a winding roller81, which is supported at the free-end of the rotation arm84being abutted on the circumferential surface of the drive roller80via a spring85to nip the unnecessary adhesive sheet S1. A drive motor M is disposed at the shaft end of the drive roller80, and it is arranged so that, when the drive roller80is driven to rotate by the motor M, the winding roller81follows the drive roller80to rotate; thereby the unnecessary adhesive sheet S1is wound thereon. Note that as the wound amount increases, the winding roller81shifts rightward inFIG. 1against the force of the spring85.

Next, the sticking method of the adhesive sheet S in accordance with the embodiment will be described with reference toFIGS. 4 and 5as well.

In the initial setting, in the raw strip sheet L, which is fed out from the support roller20, the adhesive sheet S is peeled off from the release liner PS at the front edge position of the peel plate22, and the lead end of the release liner PS is fixed to the collection roller23through the guide rollers28,29. On the other hand, the lead end of the adhesive sheet S is fixed to the winding roller81of the winding apparatus17through the press roller14and the peeling apparatus16. Here, the peel plate22constituting the front end of the feed-out head49is positioned at its upper limit position (refer toFIG. 1andFIG. 4(A)). And the adhesive sheet S between the peel plate22and the press roller14is set so as to have a predetermined sticking angle θ with respect to the surface of the wafer W disposed on the table13as shown inFIG. 1. Also, the position of the front end of the peel plate22is adjusted by the cylinder50so that the length of the adhesive sheet S between the peel plate22and the press roller14is a little longer than the length from the one end to the other end, i.e., from the right end to the left end of the wafer W inFIG. 4.

In a state that the wafer W is set on the table13by means of a transfer arm (not shown), the sticking operation starts. Before sticking operation starts, the brake shoes32,42are brought into contact with the guide rollers27,29to restrain the adhesive sheet S from being fed out. In a state that the table13is at a standstill, the press roller14rotates and moves on the wafer W leftward inFIG. 4. When the press roller moves, a tension is applied to the adhesive sheet S, and the tension measuring roller40is pulled in the X-direction. Then, the load cell39measures the tension, and thereby the feed-out head49is lowered at an angle by using the sticking-angle maintaining means37to maintain a predetermined tension. That is, the load cell39measures the tension, and is controlled to output an instruction to the pair of uniaxial robots46to maintain the predetermined tension based on the data.

Therefore, as a result, the feed-out head49gradually descends along the inclined angle of the guides45and uniaxial robots46(refer toFIG. 1). Owing to this, even when the length of the adhesive sheet S between the front end of the peel plate22and the press roller14becomes shorter, the sticking angle θ is maintained constantly to a constant angle.

In this embodiment, as described above, during the sticking operation of the press roller14, the feed-out head49is lowered while the tension of the adhesive sheet S being measured with the load cell39. As a result, the sticking angle θ is maintained. However, control of descent of the feed-out head49may eliminate the load cell39. That is, as shown inFIG. 4(A), assuming that the lowermost position of the press roller14and the front edge position of the peel plate22at the start point of the sticking operation be P1and P2respectively; the front edge position of the peel plate22at the point when the sticking operation of the adhesive sheet S has been completed be P3; and the sticking angle formed by P2, P1and P3be θ, the following arrangement may also be adopted. That is, the uniaxial robots46and60are controlled synchronously to lower the feed-out head49constituting the sticking-angle maintaining means37along the guide bars45so that, as the press roller14moves and the distance between the points P1and P3is made smaller by the uniaxial robot60, the level of the peel plate22, that is the distance between the points P2and P3also becomes shorter, and thus the sticking angle θ is constantly maintained. Note that the movement amount of the feed-out head49is readily calculated by using the trigonometric function. Thus, by constantly maintaining the sticking angle θ based on the detection of the movement distance of the press roller14, the same operation and effect as those of the tension control using the load cell39can be obtained. In the present invention, these control methods can be employed selectively.

As shown inFIGS. 4(D) and 4(E), when the sticking operation of the adhesive sheet S has been completed, the cutter15descends to cut the adhesive sheet S along the peripheral edge of the wafer W, and then the cutter15goes up to return to the initial position (refer toFIG. 1). At this time, the front end of the peel plate22is positioned in the vicinity of the left end of the wafer W. Owing to this, the area of the adhesive sheet existing at the left side from the front edge position of the peel plate22can be used as the area to be stuck to the next wafer W, thus the adhesive sheet S is prevented from being consumed wastefully.

Then, after the wafer W is removed from the table13by means of the transfer apparatus, as shown inFIGS. 5(A) to 5(D), the press roller14goes up, and the small diameter roller70and the large diameter roller71constituting the peeling apparatus16move leftward. And the drive roller80of the winding apparatus17is driven to wind the unnecessary adhesive sheet S1; thus the unnecessary adhesive sheet S1around the wafer W can be peeled off from the upper surface of the table13.

Then, the brake shoes32,42move away from the guide rollers27,29so that the raw strip sheet L can be fed out, and in a state that the drive roller80is locked, the peeling apparatus16and the winding apparatus17return to the initial position. As a result, new adhesive sheet S is pulled out and new wafer W is transferred onto the table13again.

Therefore, according to the embodiment as described above, since such arrangement is employed that the tension of the adhesive sheet S is maintained to a constant level while sticking the adhesive sheet S to the wafer W, such advantage can be obtained that air bubbles catching due to insufficient tension or warp deformation of the wafer due to excessive tension can be effectively prevented.

The best arrangement, method and the like for carrying out the present invention have been disclosed so far. However, the present invention is not limited to the above.

That is, the present invention has been illustrated and described mainly about a specific embodiment. However, it is possible for those skilled in the art to add various modifications, if necessary, to the above-described embodiment with respect to the shape, position and/or disposition without departing from the technical spirit and the range of the object of the present invention.

For example, in the above-described embodiment, the case where the press roller14is moved to stick the adhesive sheet S in a state that the table13is at a standstill has been illustrated and described. However, such arrangement that the table13is caused to move may be employed. Also, the sticking angle θ is not particularly limited.

Further, in the above-described embodiment, an example in which the plate-like object is the wafer has been described. However, the present invention is applicable to such arrangement that a sheet or film is stuck on a plate-like object other than wafer.