JP2000183138A - Wax bonding tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce tolerance at wax bonding and control the wax thickness with reproducibility by a method, wherein there is provided a partial spherical body having its center on a piston center axis at a top end part of the piston for pressing a workpiece semiconductor wafer. SOLUTION: A top end part 44 of a piston 4 has heat-resistance, and is constituted with a fluororesin, in which even if a wax 3 is slightly adhered thereto, it solidifies, so that it will not be bonded with a semiconductor wafer 1, and the top end 441 is formed to be hemi-spherical, and it is crimped and fixed to the piston 4. Here, the piston 4 is dropped, and the top end 441 of the top end part 44 is brought into contact with the surface of a workpiece semiconductor wafer 1. Since the wax 3 has melted, the semiconductor wafer 1 is moved, and the center of the workpiece semiconductor wafer 1 is made to coincide with the top end 441 for positioning. Since the top end 441 has a spherical surface, it comes into contact with the surface of the workpiece semiconductor wafer 1 at a single point, and most part turns into a force of pressing in a right-angled direction to the surface of a base stand 2, and it is possible to uniformly apply force on the plane of the workpiece semiconductor wafer 1 and the wax 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wax bonding jig, and more particularly to a wax bonding jig which solves the above-mentioned problem of controlling the thickness of a wax with a small tolerance and controlling reproducibility satisfactorily.

[0002]

2. Description of the Related Art A conventional example of wax bonding will be described with reference to FIG. The semiconductor material is used for manufacturing various semiconductor devices. In manufacturing any of the semiconductor devices, the semiconductor wafer 1 is generally sliced in a final manufacturing process of the semiconductor device. For sophisticated semiconductor devices, 500-300 early in the manufacturing process
It is required to finish the semiconductor wafer 1 having a thickness of about μm into a semiconductor wafer having a thickness of about 150 to 50 μm in a final finishing step. As a method of thinning the semiconductor wafer 1, the semiconductor wafer 1 to be processed is temporarily bonded to a base 2 using wax 3, and then lapping and polishing techniques are applied. The technique of realizing the thinning of the required accuracy is adopted. That is,
As the lapping and polishing techniques have advanced and the processing accuracy has been sufficiently ensured and the required thinning can be realized, this polishing technique is adopted for thinning the semiconductor wafer 1. Reached. In FIG. 4, 4
Denotes a piston, and 5 denotes a spring that biases the piston 4 downward. These are used to hold the semiconductor wafer 1 on the base 2 until the wax 3 cools and solidifies when the semiconductor wafer 1 is temporarily bonded to the base 2 via the wax 3. When the semiconductor wafer 1 is cooled and solidified and joined to the base 2, the semiconductor wafer 1 is lifted from the surface of the semiconductor wafer 1.

However, when the semiconductor wafer 1 to be processed is temporarily bonded to the base 2 with the wax 3, the final finished thickness of the semiconductor wafer 1 becomes extremely thin, and the thickness of the wax 3 becomes smaller. It is too thick to be neglected compared to the final finish thickness, or the semiconductor wafer 1
If the surface itself has irregularities and other variations, it is not always possible to ensure high accuracy of the finally finished thinned semiconductor wafer 1. That is, the thickness of the wax 3 must be sufficiently smaller than the dimensions of the chips when the chips are cut out from the semiconductor wafer 1 and cleaved. Therefore, it is necessary to minimize the tolerance in the bonding process using the wax 3.

Heretofore, the temporary joining process using the wax 3 has to be performed manually by a skilled worker or by using an expensive vacuum pressure joining device. In the case of manual operation by an operator, a wax 3 is applied to the base 2 heated to the working temperature, and the semiconductor wafer 1 to be processed is pressed against the base 2 so that air bubbles do not enter the wax 3. The tip portion 44 of the piston 4 is pressed against the semiconductor wafer 1 to be processed by the spring 5 to apply pressure.
Is naturally cooled and solidified.

[0005]

As described above, when the semiconductor wafer 1 is temporarily joined to the base 2 manually by way of the wax 3, the tip 44 of the piston 4 is attached to the semiconductor wafer 1. When the semiconductor wafer 1 is pressed against the surface of the semiconductor wafer 1, the surface of the semiconductor wafer 1 to be processed may be inclined as shown in FIG. In the case of FIG. 5, the direction of the pressure applied to the semiconductor wafer 1 from the front end portion 44 of the piston 4 is vertical, but the direction of the pressure actually applied to the surface of the semiconductor wafer 1 via the front end of the front end portion 44 is It is inclined by the amount that one surface is inclined. by the way,
As shown in FIG. 5, the portion that actually contacts and engages with the surface of the semiconductor wafer 1 is not the planar shape of the tip of the tip portion 44 but protrudes.
Pressure is applied to the surface from the right end of the tip 44 of the piston 4. Therefore, this pressure also generates components other than the vertical component and the horizontal component with respect to the semiconductor wafer 1, and the pressure applied to the wax 3 from the lower surface of the semiconductor wafer 1 varies depending on the lower surface of the wafer 1 and is not uniform. Therefore, the lower surface of the semiconductor wafer 1 cannot be mounted parallel to the base 2. That is, it is difficult to accurately control the thickness of the wax 3. Overcoming this difficulty and joining the semiconductor wafer 1 to the base 2 manually requires considerable skill. Similarly, when the surface roughness of the semiconductor wafer 1 to be processed is large and the surface has irregularities, similarly, it is difficult to control the thickness of the wax 3. When the wax 3 adheres to the surface of the semiconductor wafer 1 or the tip 44 of the piston 4, the wax 3 solidifies and joins the surface of the semiconductor wafer 1 and the tip 44 of the piston 4 to form the semiconductor wafer 1 itself. And it may be difficult to remove the joint without damaging the joint to the base 2.

According to the present invention, when the shape of the tip portion of the piston and the material constituting the tip portion are improved and the semiconductor wafer to be processed and the base table are temporarily joined by wax, the tolerance of the wax thickness is reduced to a small degree. It is another object of the present invention to provide a wax bonding jig which satisfactorily controls the reproducibility and solves the above-mentioned problem.

[0007]

A wax bonding jig for bonding a semiconductor wafer to be processed 1 to a base 2 with wax 3, comprising a piston 4 for pressing the semiconductor wafer 1 to be processed, The tip 441 of the tip 44 of the piston 4 constitutes a wax joining jig configured as a partial sphere having a center on the central axis of the piston 4.

Claim 2: In the wax joining jig according to claim 1, a counterbore having a diameter which is fitted and positioned slightly larger than the diameter of the base 2 so as to be rotated. A wax bonding jig including the base support 21 on which the base 23 was formed was formed. Claim 3:
In the wax bonding jig according to any one of claims 1 and 2, a dummy wafer bonding recess 22 is formed in the base 2, and the dummy wafer 11 is bonded thereto, and the dummy wafer 11 is pressed. A dummy wafer piston 42;
The tip 441 ′ of 4 ′ constituted a wax bonding jig configured as a partial sphere having a center on the central axis of the dummy wafer piston 42.

Further, in the wax bonding jig according to the third aspect, the dummy wafer 11 is slightly harder than the semiconductor wafer 1 to be processed, and is processed when the polishing is performed under the same conditions. A wax bonding jig made of a semiconductor flake having a low speed was constructed. Claim 5: In the wax bonding jig according to any one of claims 1 to 4, the lower plate 61 and the upper plate 6
2 and a jig frame 6 composed of a column 63 for interconnecting the lower plate 61 and the upper plate 62, and a base support 2 is provided at the center of the upper surface of the lower plate 61.
The heat-resistant bearings 41 ′ are attached and fixed directly above each of the peripheral portions of the upper plate 61 corresponding to the dummy wafer bonding recesses 22, and the heat-resistant bearings 41 are attached and fixed to the central portions thereof. The dummy wafer piston 42 is inserted and fitted into the heat-resistant bearing 41 ′ at the periphery of the upper plate 62, and the piston 4 is connected to the heat-resistant bearing 41 at the center of the upper plate 62.
To form a wax bonding jig which was inserted through and fitted.

Claim 6: Claims 1 to 5
In the wax jig described in any of the above,
Both the tip 441 of the tip 44 of the piston 4 and the tip 441 'of the tip 44' of the dummy wafer piston 42 constitute a wax bonding jig made of fluorine resin.

[0011]

An embodiment of the present invention will be described with reference to FIG. The jig frame 6 includes a lower plate 61 made of a disk, an upper plate 62 made of a disk, and a column 63 for connecting and supporting the lower plate 61 and the upper plate 62.
It is composed of The base support 21 is positioned and fixed at the center of the upper surface of the lower plate 61. The lower plate 61 and the base support 21 are made of brass having good thermal conductivity to facilitate heating. A counterbore 23 is formed concentrically on the upper surface including the center of the base support 21.
Is formed, on which the base 2 is fitted and positioned. The diameter of the counterbore 23 is extremely slightly larger than the diameter of the base 2 and is a diameter that can be fitted and positioned and rotated. At the center of the surface of the base 2, a marker X indicating where the center of the semiconductor wafer 1 to be processed is to be positioned is attached. In the peripheral portion of the base 2, dummy wafer bonding recesses 22 are formed at three locations at equal angular intervals of 120 ° in the circumferential direction. Dummy wafer bonding recess 2
2 is a dummy wafer 1 via wax indicated by oblique lines.
1 is fixedly joined. The thickness of the wax indicated by the diagonal lines is made as thin as possible to join the dummy wafer 11 to the dummy wafer joining recess 22. As the dummy wafer 11, a semiconductor flake having a slightly higher hardness than the semiconductor wafer 1 to be processed and having a low processing speed when polished under the same conditions is used. The surfaces of the dummy wafers 11 bonded and fixed to the three dummy wafer bonding recesses 22 are located in a common plane. Dummy wafer 11
Is previously bonded to the three dummy wafer bonding recesses 22 of the base 2 with the surface positioned in a common plane as described above. At the time of bonding the dummy wafer 11, the surface of the dummy wafer 11 is pressurized under predetermined weighting conditions described later, and waits until the wax cools and solidifies. A heat-resistant bearing 41 is attached and fixed to the center of the upper plate 62, and the piston 4 for pressing the semiconductor wafer 1 to be processed is inserted and fitted into the bearing. A heat-resistant bearing 41 ′ is attached and fixed directly above each of the peripheral edges of the upper plate 62 corresponding to the dummy wafer bonding recesses 22. A dummy wafer piston 42 for pressing the dummy wafer 11 is inserted and fitted into each of the three heat-resistant bearings 41 '. The heat-resistant bearing 41 plays a role in smoothing the sliding of the piston 4 and the dummy wafer piston 42. In addition, a screw portion is formed at the upper end of the piston 4 and the dummy wafer piston 42, and the weight 7 is screwed. The weighting condition can be changed by increasing or decreasing the number of weights 7 to be screwed. The distal end portion 44 of the piston 4 is made of a fluororesin which has heat resistance and does not solidify even when the wax 3 adheres to the semiconductor wafer 1 even if the wax 3 slightly adheres. The distal end 441 is formed in a hemispherical shape. And fixed to the piston 4 by pressure bonding. Tip 44 ′ of dummy wafer piston 42
Similarly, it is made of a fluororesin which has heat resistance and does not solidify even if the wax 3 adheres to some extent and does not bond with the dummy wafer 11.
1 ′ is formed in a hemispherical shape, and is fixed to the piston 42 by crimping.

Here, the step of polishing and thinning the semiconductor wafer 1 to be processed will be described. First, the lower plate 61 and the base support 21 are heated by a suitable heating device to a working temperature at which the wax melts. The base 2 that previously joins the dummy wafer 11 to the three dummy wafer joining recesses 22 is fitted into the counterbore 23, and this is rotated to position each of the three dummy wafers 11 directly below the dummy wafer piston 42. I do. The temperatures of the semiconductor wafer 1 to be processed and the base 2 will soon rise to the working temperature.

A wax 3 is applied with reference to a marker x provided on the center of the surface of the base 2 at the working temperature, and the semiconductor wafer to be processed is watched while paying attention to air bubbles. 1 is joined. The three dummy wafer pistons 42 are lowered, the tips 441 'of these tips 44' are brought into contact with the surface of the dummy wafer 11, and the weight 7 corresponding to a predetermined load condition is screwed into the upper end of the piston to apply a load. Load.

Similarly, the piston 4 is lowered to bring the tip 441 of the tip 44 into contact with the surface of the semiconductor wafer 1 to be processed. At this time, since the wax 3 is melted, the semiconductor wafer 1 is moved so that the center of the semiconductor wafer 1 to be processed is properly aligned with the tip 441 of the tip 44 of the piston 4 and positioned. Here, as described above, the tip 441 has a spherical surface, and thus contacts the surface of the semiconductor wafer 1 to be processed at one point. Next, the weight 7 corresponding to the predetermined load condition is screwed into the piston 4.
The vertical downward load is applied perpendicularly to the surface of the semiconductor wafer 1 from the piston 4 via this one point which comes into contact with the semiconductor wafer 1 to be processed. This load applied at right angles to the surface is almost the same as the force that presses the semiconductor wafer 1 to be processed in the direction perpendicular to the surface of the base table 2 and the negligible force that presses the semiconductor wafer 1 in the direction parallel to the surface of the base table 2. Decomposed. That is, as shown in FIG. 3A, almost all of the force applied from the piston 4 to the semiconductor wafer 1 to be processed is a force for pressing the surface of the base 2 in a direction perpendicular to the surface of the base wafer 2. A force is uniformly applied to the whole and the surface of the wax 3. Even if there is a very slight force pressing in a direction parallel to the surface of the base 2, this does not act as a downward force on the entire semiconductor wafer 1 to be processed and the plane of the wax 3. As shown in FIG. 3B, the force is not applied unevenly. The tip 441 'of the tip 44' of the dummy wafer piston 42 and the dummy wafer 11
The same applies to.

In the above-mentioned pressurized state, the wax 3 is naturally cooled and solidified. By adding uniform power to the surface of the wax 3, the in-plane distribution of the thickness of the solidified wax 3 falls within a very small tolerance of about 0 to 0.2 μm. As described above, the base table having the surface positioned in the common plane at the dummy wafer bonding recessed portions 22 formed at three places on the peripheral edge, bonding the dummy wafer 11 and bonding the semiconductor wafer 1 to be processed at the center. 2 were constructed. The piston 4 and the dummy wafer piston 42 are raised, and the base 2 is removed from the wax bonding jig. The base plate of the polishing apparatus has a completely flat surface, and the semiconductor wafer 1 bonded to the base 2 is polished by the base plate while supplying an abrasive to the surface. Exfoliate. In this case, the thickness of the dummy wafer 11 is set to be smaller than the thickness of the semiconductor wafer 1 to be processed, this is set as a reference thickness, and polishing is performed. When the semiconductor wafer 1 to be processed is polished to a certain extent by the platen, the surface of the platen comes into contact with the surfaces of the three dummy wafers 11 at the same time.
The polishing is terminated when the state of polishing the surface of No. 1 is obtained.

[0016]

As described above, the wax bonding jig of the present invention forms a hemisphere at the tip of the tip of the piston when the semiconductor wafer to be processed is joined to the base table by wax. It contacts the surface of the semiconductor wafer to be processed at one point. Here, the weight corresponding to the predetermined load condition is screwed into the piston, and the vertical downward load caused by the weight is applied to the surface of the piston through this one point which comes into contact with the semiconductor wafer to be processed. As a result of being applied at a right angle, almost all of the force applied from the piston to the semiconductor wafer to be processed is a force that presses the surface of the base table in a direction perpendicular to the entire surface of the semiconductor wafer to be processed and the wax uniformly. Will be. There is also a negligible force that presses in a direction parallel to the surface of the base, but this does not act as a downward force on the entire semiconductor wafer to be processed and in the plane of the wax. Accordingly, when the semiconductor wafer to be processed and the base table are joined by the wax, the wax thickness can be controlled with small tolerance and reproducible. Since the tip of the tip of the piston is made of fluororesin, wax is less likely to adhere to the tip, and there is almost no possibility of damaging the semiconductor wafer itself and the bonding of the semiconductor wafer to the base. .

[Brief description of the drawings]

FIG. 1 is a view for explaining an embodiment of a wax bonding jig.

FIG. 2 is a diagram showing a part of the embodiment of FIG. 1;

FIG. 3 is a diagram illustrating the pressure of the wax bonding operation.

FIG. 4 is a diagram illustrating a conventional example of a wax bonding jig.

FIG. 5 is a view for explaining the wax bonding operation of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor wafer 11 Dummy wafer 2 Base stand 21 Base stand receiving 22 Dummy wafer bonding recess 23 Counterbore 3 Wax 4 Piston 41, 41 'Heat-resistant bearing 42 Dummy wafer piston 44, 44' Tip 441, 441 'Tip 5 Spring 6 Jig frame 61 Lower plate 62 Upper plate 63 Support 7 Weight

Claims (6)

[Claims] 1. A wax bonding jig for bonding a semiconductor wafer to be processed to a base table with wax, comprising a piston for pressurizing the semiconductor wafer to be processed, wherein the tip of the tip of the piston is centered on the axis of the piston. A wax bonding jig characterized by being configured as a partial sphere having: 2. The base according to claim 1, wherein a counterbore having a diameter which is fitted and positioned slightly larger than the diameter of the base and is rotated. A wax bonding jig comprising a support. 3. The wax bonding jig according to claim 1, wherein a dummy wafer bonding recess is formed in the base, and the dummy wafer is bonded thereto, and the dummy wafer is added. A wax bonding jig, comprising: a dummy wafer piston to be pressed; and a tip of a tip portion of the dummy wafer piston is formed as a partial sphere having a center on an axis of the dummy wafer piston. 4. The wax bonding jig according to claim 3, wherein the dummy wafer has a slightly higher hardness than the semiconductor wafer to be processed and has a lower processing speed than the semiconductor flakes when polished under the same conditions. A wax bonding jig characterized by being formed. 5. The wax bonding jig according to claim 1, wherein the jig comprises a lower plate, an upper plate, a lower plate, and a column interconnecting the upper plate. Equipped with a jig frame, a base support is positioned and fixed at the center of the upper surface of the lower plate, and heat-resistant bearings are attached to the upper edge of the upper plate, directly above each corresponding to the dummy wafer bonding recess. A heat-resistant bearing is attached and fixed at the center of the upper plate, and the dummy wafer piston is inserted and fitted into the heat-resistant bearing at the periphery of the upper plate, and the piston is inserted and fitted into the heat-resistant bearing at the center of the upper plate. A wax bonding jig characterized by the above. 6. The wax bonding jig according to claim 1, wherein both the tip of the tip of the piston and the tip of the tip of the dummy wafer piston are made of fluororesin. A wax bonding jig characterized by being provided.