JPH11162884A - Peel method of protective sheet from semiconductor substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove in a batch and easily the protective sheets on a semiconductor substrate which is cut and divided by dicing, without damaging small structures and moving sections formed on the semiconductor substrate and having small mechanical strength (hereinafter called 'structure and the like'). SOLUTION: Cut pieces of a protective sheet 1 cut and divided by dicing are jointed into a single body, and then the periphery of the protective sheets 1 and an adhesive sheet 1 are so attached to each other as to surround the structure 3 and the like. Then, the protective sheets 1 now integrated into one body by the adhesive force of the adhesive sheet 1 are peeled off from a semiconductor substrate 2. The protective sheets 1 are peeled off by rolling a cylindrical drum 10 provided with the adhesive sheet 1 over the semiconductor substrate 2. If a recessed section 10c to house caps 1a formed on the protective sheets 1 is formed on the outer surface of a drum 2, the protective sheets 1 can be peeled off in batch from the semiconductor substrate 2, without damaging the structure 3 and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for peeling a protective sheet that has been divided together with a semiconductor substrate by dicing.

[0002]

2. Description of the Related Art A protective sheet mounted on the surface of a semiconductor substrate is divided together with the semiconductor substrate by dicing.
A conventional method of separating the divided protective sheet from the semiconductor substrate is described in Japanese Patent Application Laid-Open No. 64-61208. In the method described in this publication, a protective film or a protective sheet (hereinafter, referred to as a protective sheet) made of a heat-shrinkable plastic film with a radiation-crosslinkable adhesive is used, and a semiconductor substrate (wafer) to which the protective sheet is adhered is used. After irradiating the semiconductor substrate with the semiconductor substrate,
The protective sheet is turned up in a roll by being put into a heating furnace of 00 ° C. for 30 seconds or more, and the protective sheet is peeled off from the semiconductor substrate by inverting the semiconductor substrate. Then, even when the protective sheet is not completely peeled off, the protective sheet is lifted up with tweezers or the like to be peeled off from the semiconductor substrate.

[0003]

However, according to the above-mentioned conventional method, it is difficult to surely peel off all the divided protective sheets on the semiconductor substrate every time, and some protective sheets have a reduced adhesive strength. Since it is insufficient, it remains on the semiconductor substrate and must be peeled off with tweezers or the like, which causes a problem that the operation becomes complicated. When the protective sheet is peeled off with tweezers or the like, there is a high possibility that the elements on the semiconductor substrate are damaged.

Further, when a circuit formed on a semiconductor substrate has a structure or a movable portion having low mechanical strength, the circuit is destroyed by contacting the structure or the movable portion when the pressure-sensitive adhesive sheet contracts. In particular, a problem arises in that a vibration is applied when the semiconductor substrate is inverted and the structure or the movable portion is destroyed. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a first object of the present invention is to provide a method for peeling a protective sheet of a semiconductor substrate, in which the protective sheet on the semiconductor substrate cut and divided in dicing can be easily and collectively removed. Aim.

Further, even when a structure or a movable portion having low mechanical strength is formed on the semiconductor substrate, the protective sheet can be peeled off from the semiconductor substrate without destroying the structure or the movable portion. A second object is to provide a method for peeling a protective sheet.

[0006]

In order to achieve the above object, the following technical means are employed. According to the first aspect of the present invention, the protection sheet (1) cut and divided by the dicing cut of the semiconductor substrate (2) is joined at the cut portion (X) to be integrated, and the protection sheet and the pressure-sensitive adhesive sheet are integrated. (11, 21) are adhered to each other, and the integrated protective sheet is peeled off from the semiconductor substrate at a time by the adhesive force of the adhesive sheet.

As described above, when the protective sheet is integrated, the outer peripheral portion of the protective sheet is brought into close contact with the adhesive sheet, and the protective sheet is peeled off from the semiconductor substrate by the adhesive force of the adhesive sheet. It can be peeled off from the substrate at once. The invention according to claim 2 is characterized in that, in the step of peeling the protective sheet, a portion to be an outer periphery of the protective sheet and the adhesive sheet are brought into close contact with each other so as to surround the plurality of elements.

As described above, by adhering the outer peripheral portion of the protective sheet and the adhesive sheet so as to surround the plurality of elements, the protective sheet can be collectively removed from the semiconductor substrate without damaging the plurality of elements. Can be peeled. In this case, as described in claim 4, even when the plurality of elements are a structure or a movable portion having a small mechanical strength,
These damages can be effectively prevented. In addition, as described in claim 5, even when the protection sheet has unevenness for protecting a structure or a movable portion having a small mechanical strength, the protection sheet is formed without crushing the unevenness. It can be separated from the semiconductor substrate.

In the invention according to claim 6, the step of peeling off the protective sheet includes the step of peeling the cylindrical member (1) around which the adhesive sheet is wound so that the adhesive surface of the adhesive sheet is on the upper surface.
0) and a step of rotating the cylindrical member on the semiconductor substrate so that the protective sheet is brought into close contact with the adhesive sheet and wound.

As described above, by attaching the pressure-sensitive adhesive sheet to the cylindrical member and rotating the cylindrical member, the protective sheet can be peeled off with the rotation. In the invention according to claim 7, in the step of peeling the protective sheet, the pressure-sensitive adhesive sheet is wound so that the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet is on the upper surface, and a structure or a movable portion having low mechanical strength can be accommodated. The cylindrical member (1) in which the concave portion (10c) is formed
0), a step of accommodating a portion of the adhesive sheet arranged on the concave portion in the concave portion, and a step of rotating the cylindrical member on the semiconductor substrate to bring the protective sheet into close contact with the adhesive sheet. And winding step.

As described above, when the cylindrical member having the concave portion is prepared and the portion of the adhesive sheet arranged on the concave portion is accommodated in the concave portion, the concave and convex portions formed on the protective sheet are removed from the cylindrical member. In the recess. This can prevent the structure or the movable portion having a small mechanical strength from being damaged without the cylindrical member crushing the unevenness formed on the protective sheet.

According to the present invention, a suction hole (10d) communicating with the outside of the cylindrical member is formed in the bottom surface of the concave portion.
Is formed, and by suctioning the adhesive sheet on the concave portion through the communication hole, a portion of the adhesive sheet arranged on the concave portion is housed in the concave portion. In this manner, by providing the suction hole communicating with the outside of the cylindrical member on the bottom surface of the concave portion, the portion of the adhesive sheet that is arranged in the concave shape can be suctioned. Can be accommodated.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 1A shows a protective sheet 1 on the surface.
1 shows a semiconductor substrate 2 on which is mounted. As shown in FIG. 1A, a plurality of structures or movable parts (hereinafter, abbreviated as structures, etc.) 3 having a small mechanical strength such as an acceleration sensor are formed on a semiconductor substrate 2 in a predetermined arrangement. ing.

The structures 3 having a small mechanical strength are composed of 1
Each of the plurality of caps 1a formed on the protection sheet 1
Covered by The cap 1a is formed by projecting the protective sheet 1 by a predetermined height, and has a shape such that when the protective sheet 1 is attached to the semiconductor substrate 2, it does not come into contact with a structure 3 having a small mechanical strength. Has become.

As the protective sheet 1, a UV-curable pressure-sensitive adhesive sheet is used. For example, as the base material of the protective sheet 1, a polyolefin or the like is used, and an adhesive having a peel strength of, for example, about 1000 g / 25 mm is used. Then, the semiconductor substrate 2 shown in FIG. 1A is mounted on a dicing sheet 4 coated with an adhesive as shown in FIG.
Is cut along a scribe line to be divided into individual chips. Specifically, the semiconductor substrate 2 is diced and cut at a predetermined pitch in two directions, that is, a vertical direction and a horizontal direction, which are perpendicular to each other, and is divided into rectangular chips. By this dicing step, the protective sheet 1 mounted on the semiconductor substrate 2
Is divided with For this reason, after that, a step of joining the protection sheet 1 divided at one end and combining them into one is performed.

The joining process of the divided protective sheet 1 will be described with reference to FIG. FIG. 2 shows a state where the protection sheet 1 is joined by welding. As shown in this figure, welding of the divided protective sheet 1 is performed by a comb-shaped heater 6 which can be heated by a heater 6a. The comb-shaped heater 6 is provided with a plurality of comb teeth 6b arranged at intervals corresponding to a pitch of the dicing cut. When the comb-shaped heater 6 is positioned on the semiconductor substrate 2, the plurality of comb teeth 6b are formed. Each of them corresponds to each of the cut portions X of the divided protective sheet 1. Then, the comb-shaped heater 6 is heated by a supply from a power source or the like (not shown), and the comb-shaped heater 6 is moved in the dicing cut direction by a moving mechanism (not shown), so that the plurality of comb teeth 6b weld each of the cut portions X. It is going to do.

Since dicing is performed in the above two directions, a plurality of comb teeth 6 b corresponding to the vertical pitch and the horizontal pitch of the chip are prepared, and the comb-shaped heater 6 is Scanning is performed in two directions, a vertical direction and a horizontal direction, in accordance with the cut portion X, and the cut portions X in two directions are welded together. As a result, the welding step is completed, and the protection sheet 1 in which the cut portions X in the two directions are welded and divided is integrated again, that is, becomes one sheet. In FIG. 2, the welded portion (on the front side of the drawing) of the cut portion X is indicated by a dotted line.
The parts that are still cut are indicated by solid lines.

After the welding step is completed, the protective sheet 1 is irradiated with UV light by a UV irradiation device (not shown),
The adhesive strength of the protective sheet 1 is reduced. Next, the protective sheet 1 is peeled from the semiconductor substrate 2. The peeling of the protective sheet 1 from the semiconductor substrate 2 is performed using the drum 10 shown in FIGS. Hereinafter, the drum 10 will be described with reference to FIGS. 3A is an arrow view of the cylindrical drum 104, FIG. 3B is a front view of the drum 10, and FIG.
It is sectional drawing in the -A arrow direction.

As shown in FIG. 2A, the drum 10 has a hollow cylindrical shape inside. As shown in FIGS. 3B and 3C, the cavity of the drum 10 has a length L at φd. One end 10a of the end surface of the cylindrical drum 10 has a suction port 10 communicating with a cavity in the drum 10.
b is formed. The suction port 10b is formed so as to protrude from the end face of the drum 10, and a vacuum pump or the like can be connected to the protruding portion.

On the other hand, on the outer periphery of the drum 10, a concave portion 10c is provided.
Are formed. The unfolded shape of the concave portion 10c is a substantially circular shape having a diameter D. This diameter D is
The diameter is slightly smaller than the diameter of the semiconductor substrate 2, for example, about 6 mm when a 6-inch semiconductor substrate 2 is used. The step (depth) C of the concave portion 10c is larger than the height (projection amount) of the cap 1a formed on the protective sheet 1. For example, if the height of the cap 1a of the protective sheet 1 is 0.5 mm, it is desirable that the step C be 1 mm or more.

Further, a plurality of suction holes 10d communicating with the cavity in the drum 10 are formed in the bottom surface of the concave portion 10c. The suction hole 10d is connected to the suction port 10b through a cavity in the drum 10. The drum 10 has such a configuration. Since the diameter D and the step C of the concave portion 10c formed in the drum 10 are as described above, the protection sheet 1 does not interfere with the elements such as the structure 3 on the semiconductor substrate 2, that is, When the protective sheet 1 comes into contact with the inside of the concave portion 10c, the protective sheet 1 does not come into contact with an element such as the structure 3.

Next, a procedure for peeling the protective sheet 1 using the drum 10 having the above-described configuration will be described with reference to a cross-sectional view showing a step of peeling the protective sheet 1 shown in FIG. FIG. 4 shows a cross section taken along the line AA in FIG. 3B, as in FIG. 3C. First, as shown in FIG. 4A, a drum 10 is prepared by winding a peeling adhesive sheet 11 around the outer periphery of a drum 10 with the adhesive surface facing upward. The peeling pressure-sensitive adhesive sheet 11 used at this time only needs to use a material other than thermosetting as a pressure-sensitive adhesive, and the pressure-sensitive adhesive strength may be 5 N / 25 mm or more when the material to be adhered is SUS. desirable. Further, as the sheet base material of the peelable pressure-sensitive adhesive sheet 11, one having good heat shrinkability is suitable.

Next, a vacuum pump (not shown) is connected to the suction port 10b shown in FIG. 3 (a), and the drum 10 is rotated around the center of the cylindrical shape while performing suction with the vacuum pump. Then, as shown in FIG. 4B, the hot air 12a generated by the hot air blower 12 is applied to the peeling adhesive sheet 11 while the drum 10 is rotated. At this time, the temperature of the hot air 12a generated by the hot air blower 12 is set to, for example, 60 ° C. or more, and the hot air 12a facilitates plastic deformation (shrinkage) of the thermoplastic adhesive sheet 11 for peeling. The peeling adhesive sheet 11 in such a state is provided with the suction port 10b.
And a cavity 10 which is plastically deformed by a suction force of a vacuum pump through a suction hole 10 d to form a recess 10 formed in the drum 10.
c and is in close contact with the bottom surface of the recess 10c.

Thereafter, the recess 10 formed in the drum 10
The drum 10 is moved onto the semiconductor substrate 2 with the peeling adhesive sheet 11 in close contact with the bottom surface of FIG.
As shown in (c), the end of the semiconductor substrate 2 and the recess 10c
Align and place the ends. Specifically, the peeling adhesive sheet 11 interposed so that the recess 10c is located inside the outer diameter of the semiconductor substrate 2, that is, outside the recess 10c.
Of the semiconductor substrate 2 is brought into contact with the protective sheet 1 near the outer periphery of the semiconductor substrate 2.

Subsequently, as shown in FIG. 4D, when the drum 10 is rotated in the direction of the arrow, the protective sheet 1 near the outer periphery of the semiconductor substrate 2 is sequentially peeled off with the rotation of the drum 10. Close contact with 11. At this time, since the concave portion 10c is formed in the drum 10 and the peeling adhesive sheet 11 is stored in the concave portion 10c, the cap 1a is completely stored in the concave portion 10c. For this reason, the cap 1 a formed on the protective sheet 1 is not pressed by the drum 10 or the peeling adhesive sheet 11, so that the structure 3 having a small mechanical strength formed on the semiconductor substrate 2 is not damaged. Can be

When the drum 10 is further rotated, the protective sheet 1 further comes into close contact with the adhesive sheet 11 for peeling, and the protective sheet 1 peels sequentially from the end. And when the drum 10 is rotated as it is,
The semiconductor substrate 2 is completely peeled off from the protective sheet 1. The situation at this time is shown in FIG. 5 for reference. In this manner, the protection sheet 1 divided by the dicing cut is joined again to form a single sheet, and the protection sheet 1 is peeled off by the adhesive force of the release adhesive sheet 11, so that the protection sheets 1 are collectively assembled. And can be easily separated from the semiconductor substrate 2.

Also, a concave portion 10c is provided in the drum 10 so that the cap 1a of the protective sheet 1 is not crushed by the peeling adhesive sheet 11, and the peeling adhesive sheet 11 is attached only to the outer peripheral portion of the protective sheet 1. Therefore, the protective sheet 1 can be peeled off from the semiconductor substrate 2 without destroying the structure 3 having a small mechanical strength formed on the semiconductor substrate 2.

Conventionally, since the protective sheet is peeled off from the semiconductor substrate by heat treatment in a heating furnace or the like, the protective sheet must necessarily have the property of heat shrinkage. Was to be limited. However, in the case where the protective sheet 1 is peeled by the peeling adhesive sheet 11 as in the present embodiment, such a necessity is not required, so that the range of choice of the protective sheet 1 can be expanded. (Second Embodiment) In the first embodiment, the adhesive sheet 11 is provided on the drum 10 provided with the concave portion 10c, and the protective sheet 1 is separated from the semiconductor substrate 2 by using the drum 10 with the adhesive sheet 11. In this embodiment, the case where the protective sheet 1 is separated from the semiconductor substrate 2 without using the drum 10 is shown.
Note that the configuration and the like of the semiconductor substrate 2 provided with the protection sheet 1 are the same as those of the first embodiment, and will not be described here.

FIG. 6A is a perspective view of the release adhesive sheet 21 used in the present embodiment. However, in this drawing, the portion of the release adhesive sheet 21 is indicated by oblique lines. In the present embodiment, as the peeling adhesive sheet 21, a sheet obtained by cutting and opening a circular hole 21 a having a diameter D in the center of the planar adhesive sheet 21 is used. The diameter D of the hole 21a formed in the release adhesive sheet 21 is the same as in the first embodiment.
The diameter is slightly smaller than the diameter of the semiconductor substrate 2, for example, about 6 mm when a 6-inch semiconductor substrate 2 is used.

The release adhesive sheet 21 having the hole 21a having the diameter D is positioned so that the cap 1a of the protective sheet 1 is inserted into the hole 21a having the diameter D. Stick it on. As a result, the portion of the peeling adhesive sheet 21 outside the hole 21 a is in close contact with the protective sheet 1 near the outer periphery of the semiconductor substrate 2. For example, when the diameter D is smaller than the diameter of the semiconductor substrate 2 by about 6 mm as described above, the adhesive width is 3 mm.

Thereafter, as shown in FIG. 6B, when the peeling adhesive sheet 21 is turned from the end of the protective sheet 1,
The protective sheet 1 can be peeled from the semiconductor substrate 2 together with the release adhesive sheet 21 by the adhesive force of the release adhesive sheet 21. In this way, if the holes 21a are formed in the peeling adhesive sheet 21 so that the cap 1a of the protective sheet 1 is not crushed by the peeling adhesive sheet 21, the protective sheet 1 can be peeled without using the drum 10. Can be.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view showing a semiconductor substrate 2 provided with a protective sheet 1, and FIG. 1B is a cross-sectional view showing the semiconductor substrate 2 during a dicing process.

FIG. 2 is an explanatory view showing a welding step for integrating the protective sheet 1;

FIG. 3 is a diagram for explaining the drum 10,
(A) is a perspective view of the drum 10, (b) is a side view of the drum 10, and (c) is a cross-sectional view taken along the line AA of (b).

FIG. 4 is an explanatory view showing a peeling step of the protective sheet 1.

FIG. 5 is an explanatory view showing a peeling step of the protective sheet 1.

FIG. 6 (a) is a view showing a peeling pressure-sensitive adhesive sheet 21 according to a second embodiment, and FIG. 6 (b) is a diagram showing a step of peeling a protective sheet 1 using the peeling pressure-sensitive adhesive sheet 21 of (a). FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Protective sheet, 1a ... Cap, 2 ... Semiconductor substrate, 3
... Structure, etc., 4 ... Dicing sheet, 5 ... Dicing blade, 6 ... Comb heater, 10 ... Drum, 10a ... Drum end face, 10b ... Suction port, 10c ... Recess, 10d ... Suction hole, 11, 21 ... Peel off Pressure-sensitive adhesive sheet, 12 ... warm air heater,
X: cutting part.

Claims (8)

[Claims] 1. A semiconductor substrate (2) having a plurality of elements (3) formed on a surface thereof, a protective sheet (1) mounted on the surface to cover the plurality of elements, and the semiconductor substrate is diced. A method of peeling the protective sheet from the semiconductor substrate after the above, wherein the protective sheet cut and divided by dicing cut of the semiconductor substrate is joined at the cut portion (X) to be integrated, A method for peeling a protective sheet, comprising: adhering an adhesive sheet (11, 21) to a protective sheet; and peeling the integrated protective sheet from the semiconductor substrate by the adhesive force of the adhesive sheet. 2. The method according to claim 2, wherein in the step of peeling off the protective sheet, a portion to be an outer periphery of the protective sheet and the adhesive sheet (11, 21) are brought into close contact with each other so as to surround the plurality of elements. The method for peeling a protective sheet according to claim 1. 3. The protective sheet peeling method according to claim 1, wherein the step of integrating the protective sheet is performed by welding the cut portion by heat treatment. 4. The method according to claim 1, wherein the plurality of elements are a structure or a movable part having a small mechanical strength. 5. The projections and depressions (1a) on the protective sheet for protecting the structure or the movable part having a small mechanical strength.
5. The method according to claim 4, wherein the protective sheet is formed. 6. The step of peeling off the protective sheet, the step of preparing a cylindrical member (10) around which the adhesive sheet is wound so that the adhesive surface of the adhesive sheet faces the upper surface; A step of winding the protective sheet in close contact with the adhesive sheet by rotating the semiconductor sheet on the semiconductor substrate.
The method for peeling a protective sheet according to any one of the above. 7. The step of peeling off the protective sheet, wherein the pressure-sensitive adhesive sheet is wound so that the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet faces the upper surface, and the structure having a small mechanical strength or a recess capable of accommodating a movable portion. A step of preparing a cylindrical member (10) on which (10c) is formed; a step of accommodating a portion of the pressure-sensitive adhesive sheet arranged on the concave portion in the concave portion; The method for peeling a protective sheet according to claim 5, further comprising: winding the protective sheet in close contact with an adhesive sheet by rotating the protective sheet on a substrate. 8. A suction hole (10d) communicating with the outside of the cylindrical member is formed on a bottom surface of the concave portion, and the pressure-sensitive adhesive sheet on the concave portion is sucked through the communication hole to form the pressure-sensitive adhesive sheet. The method according to claim 7, wherein a portion of the protective sheet disposed on the concave portion is accommodated in the concave portion.