JPH01135439A - Adhesion of wafer and device thereof - Google Patents

Abstract

PURPOSE:To prevent wax from including gas foams and obtain a uniform thickness of wax and improve adhesion precision by forcibly curving a wafer and mounting said wafer onto a polishing rotary disc from the projection surface part of the curved part and allowing the wafer to be attached. CONSTITUTION:A vacuum chuck 1 is made of polymer, and the adsorbing plane 1' is formed into spherical form, and an adsorbing hole is drilled in concentric form. When a wafer 2 is loaded onto the adsorbing plane 1' of the vacuum chuck 1 and attracted, said wafer 2 is curved into the arcuate form corresponding to the curvature of the adsorbing plane 1'. The wafer surface or a polishing rotary disc 4 is applied with wax 3, and the wafer 2 is transported onto the polishing rotary disc 4 from the projection surface part side of the curved part, and the attraction of the vacuum chuck is suspended, and then the wafer 2 is made flat on the disc 4 by the restoring force which the wafer 2 possesses itself. In this case, if the wax 3 is made soft, the wax 3 and gas foams 4 are extruded in the restoring process of the wafer 2, and a uniform thickness of the wax 3 can be realized, and the gulfing of air can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wafer bonding method and a bonding device for bonding a wafer serving as a substrate of a semiconductor material onto a rotating polishing disk.

[Conventional technology]

In a wafer polishing method in which one side of the wafer is bonded to a rotating polishing disk using wax such as paraffin, and the other side is subjected to lapping or mirror polishing, the wafer is bonded flat to the rotating disk for polishing. is important. Conventionally, when bonding wafers, wax was applied to one side of the wafer or a rotating polishing disk, the wafer was placed, and the wafer was pressed onto the rotating polishing disk with a presser rod or moved in parallel to bond the wafer. Afterwards, it was subjected to polishing. As shown in FIG. 8(a), a warped wafer 2 is suctioned with a vacuum chuck 1 having a flat suction surface 1" as shown in FIG. 8(b) (with a vacuum pump 12, wax 3 is After coating, the top surface of the polishing rotating disk 4
It was pressed and adhered as shown in Figure (C).

[Problem that the invention seeks to solve]

However, when a wafer is bonded onto a rotating polishing disk, air bubbles may be included between the wafer and the disk, or the thickness of the wax may be uneven, resulting in unevenness remaining on the polished surface of the wafer. The wafer has a non-uniform thickness. In addition, once air bubbles are included, it is very difficult to remove them, and in the conventional method described above, the wafer is placed flat on the polishing rotating disk, so the wafer is simply pressed against it, This problem could not be solved simply by moving in parallel.

Therefore, it is an object of the present invention to provide a bonding method and an apparatus therefor that can improve bonding accuracy by preventing air bubbles from being placed on a wafer on a disk, and by allowing the wax to be stored with a uniform thickness. shall be.

[Means for solving problems]

In order to achieve the above object, the present invention involves forcibly bending a wafer, and placing the wafer from the convex side of the curved portion R on a rotating polishing disk and bonding it, or further placing the wafer on the rotating disk for polishing. The device rotates the wafer while holding it down. To force the wafer to curve, use a convex suction surface,
In particular, we use a vacuum chuck with a spherical suction surface,
The wafer is attracted to the suction surface and curved, and the convex side of the curved part of the wafer is placed on the upper surface of the disk! The wafer is adhered onto the disc by placing the wafer on the disk for 32 seconds, or by rotating the wafer while pressing it using a stamping jig. A wafer bonding device for this purpose includes a vacuum chuck having a convex suction surface, a bending means for adsorbing the wafer to the vacuum chuck and bending the wafer, and then attaching the wafer from the convex side of the curved portion onto the polishing rotating disk. ! ! The present invention is characterized in that a wafer bonding device is used, which includes a mounting means for placing a wafer on the polishing rotating disk, and a stamping jig that presses and rotates the wafer that has been subjected to IFH on the polishing rotating disk to bond the wafer.

[Effect]

In a wafer bonding method in which a wafer is bonded to a polishing rotating disk using wax, the wafer is forcibly curved, placed on the polishing rotating disk from the convex side of the curved part, and bonded. As shown in FIG. 3, the wafer 2 is flattened on the disk 4 by the restoring force of the wafer itself. At this time, during the process of restoring the wafer, the wax in the direction of the arrow shown in the figure and the action of pushing out the air bubbles work, making the thickness of the wax uniform and preventing air from getting caught between the wafer and the disk. It is made of lacquer that can be bonded without incorporating air bubbles.

Moreover, by rotating and bonding the wafer while pressing it, the bonding accuracy can be further improved.

〔Example〕

Hereinafter, embodiments will be described according to the drawings.

Figure 1 is a side view and bottom view of the vacuum chuck of the present invention, Figure 2 is a side view of a wafer being sucked by the vacuum chuck of the present invention, and Figure 3 is a wafer placed on a disk by the vacuum chuck. Figure 4 shows the measurement points on the wafer used to measure the amount of wafer warpage. Figure 5 shows the wafer attached by hand. FIG. 6 is an explanatory diagram showing the process of wafer attachment, and No. 7 is a side view of the bonding apparatus of the present invention.

In the figure, I is a vacuum chuck, 1゛ is a spherical suction surface, 1'' is a suction hole, 2 is a wafer, 3 is wax, 4 is a polishing rotating disk, 5 is an inversion arm, 6 is a stamping jig, 7 is a stamping Cylinder, 8 is a cylinder for wafer rotation,
Reference numeral 9 indicates a fixing member, lO indicates an inversion center, and 11 indicates a lifting cylinder.

The vacuum chuck 1 of the present invention shown in FIG. 1(a) is made of a polymer such as Teflon and has an air passage in the shaft connected to a vacuum pump, and the suction surface 1' is formed in a spherical shape. As shown in the figure ('b), the bottom surface is provided with concentric suction holes 1'', which are connected to the air passages.

When a wafer 2 is placed on the suction surface of the vacuum chuck 1 and suction is performed by a vacuum pump, the wafer 2 is suctioned, and the wafer 2 corresponds to the curvature of the suction surface of the vacuum chuck l as shown in FIG. It curves into a circular arc. At this time, the relationship between the diameter of the suction surface of the vacuum chuck I and the diameter of the wafer is preferably in the range D/4<a<0.

Further, the symbol X shown in FIG. 2 represents the warpage of the wafer. The amount of warpage of the wafer is as shown in Figure 4.
Select two measurement points, 1 on the orientation flat side and 2.3.4 at 90@ clockwise, measure the warped silkworms at each measurement point before and after adsorption with an electric micrometer detector, and calculate the difference. The average value was determined. As a result, the relationship between warpage and wafer diameter is as follows: When the thickness is 0.4 to 0.6 mm and the wafer diameter is 5 cm, the warpage is 20 to 5011 m.
Similarly, it was found that 30 to 80 μm is desirable for 7.5 cm, and 40 to 100 μm for 4 inches.

If the amount of warpage is larger than this range, the wafer may break, and if it is smaller, the effects of the present invention cannot be achieved.

The wax used is oil wax, paraffin wax, or a mixture thereof. Appropriate means such as a spin cord are used for coating, and the wax may be coated on the wafer surface or on a rotating polishing disk.

Next, as shown in FIG. 3, when the wafer is placed on the polishing rotary disk 4 from the convex side of the curved portion and the suction of the vacuum chuck is stopped, the wafer 2 is lifted onto the disk 4 by the restoring force of the wafer itself. to flatten it.

At this time, by softening the wax with an appropriate heating means, during the wafer restoration process, the hewanox in the direction of the arrow shown in Figure 3 and the action of pushing out air bubbles are activated, so that the thickness of the wax can be made uniform. Moreover, since it is possible to prevent air from being trapped between the wafer and the disk, it is possible to bond the wafer without incorporating air bubbles.

As a means for placing the wafer on the disk, it is preferable to use an inverted vacuum chuck, as shown in FIG. 6, for example. That is, the vacuum chuck 5 is used as a wafer suction means.
The suction surface of the inverting arm 5 is provided so as to face upward on the end of the inversion arm 5,
While adsorbing the wax-coated wafer 2, the inversion arm is inverted about the inversion center 10, and the convex side of the curved part of the wafer is placed on the polishing rotary disk 4 placed on the other end side of the inversion arm. It will be placed from By using such a reversing chuck, the wafer can be reliably placed on the disk.

In order to further improve the adhesion accuracy of the wafer 2 adhered to the disk in this way, the stamping jig 6 placed on the disk 4 rotates the wafer while pressing it onto the disk. The stamping jig 6, as shown in FIG.
It is operated by a stamping cylinder 7 and a wafer rotation cylinder 8 that rotates the wafer during stamping.

The contact surface with the wafer is made of an oil-resistant elastic member such as silicone rubber, and its shape is an arcuate convex surface. The wafer rotation cylinder 8 allows the wafer 2 to be rotated in one direction, to improve adhesion accuracy, and to improve adhesion accuracy, as well as to rotate the wafer 2 to the position before rotation, or after rotation at a certain angle. Try to return it to the previous position. Preferably, the method of rotating 5 to 90 inches and returning to the position before rotation is repeated 1 to 5 times.

Next, the wafer bonding process using an inversion chuck will be explained. First, the wafer 2 is attracted onto the inversion chuck 1, and then the inversion arm 5 is moved 180 degrees as shown in FIG.
@ Invert the wafer, then lower the inverting section using the lift cylinder 11 until the wafer contacts the disk 4, and stop suctioning the wafer when the tip of the wafer contacts the disk, the wafer will rise above the disk by its restoring force. Glue it in a flat shape. Next, the stamping jig is lowered from above the wafer, the wafer is pressed onto the disc, and while the wafer is pressed, the stamping jig is rotated by a wafer rotation cylinder to perfect the bonding state.

The method for bonding wafers has been explained above, and as shown in Figure 7, the equipment for this purpose consists of a wafer supply section consisting of a vacuum chuck, a wafer pressure section consisting of a stamping jig, and a rotating polishing disk. has been done.

The wafer supply unit is composed of an inversion vacuum chuck connected to a vacuum pump, a mechanism for inverting the inversion arm 180', and a lifting cylinder 11 that lowers the wafer attracted to the inversion arm until it contacts the disk. . The wafer pressing section also includes a stamping jig, a stamping cylinder 7 that raises and lowers the stamping jig, and a wafer rotation cylinder 8 that rotates the stamping jig by a certain angle when the wafer is pressed onto the disk by the stamping jig. The whole is supported by a fixed frame 9.

The operations of these mechanisms are automated by sequentially controlling them with appropriate control means according to the process diagram shown in FIG.

〔Effect of the invention〕

Regarding the wafer bonded on the disk in this way,
The accuracy of the application was measured. First, FIG. 5(a) shows a wafer pasted onto a disk by hand, and FIG. 5(b) shows a wafer pasted onto a disk using the method of the present invention.
The thickness of the wafer from the top of the disk was observed using the interference fringe method, and in the case where the wafer was pasted by hand, many Newton rings were observed with steep contour lines, and the center was observed to have a convex shape. . On the other hand, in the case of the adhesive adhered to the disc according to the present invention, this is not observed and it is observed that the adhesive adheres to the disc in an extremely flat manner.

Also, the pasting process is based on the total thickness change of the previous wafer (Total thickness change).
Th1ckness Variati.

n) and the total thickness change obtained by measuring the parallelism between the wafer and the disk surface using the interference fringe method when the wafer is attached to the disk using the vacuum chuck of the present invention. Accuracy was measured. As a result, 4 to 6
The adhesion accuracy was 1 μm, but the wafer was stamped and
When repeating the operation of rotating 5 degrees and then returning to the starting position twice, the accuracy was less than 1 μm, and the air bubbles were completely removed and the wax was also made uniform.

[Brief explanation of the drawing]

Figure 1 is a side view and bottom view of the vacuum chuck of the present invention, Figure 2 is a side view of a wafer being sucked by the vacuum chuck of the present invention, and Figure 3 is a wafer placed in an R position on a disk by the vacuum chuck. Figure 4 shows the measurement points on the wafer used for measurement with a wafer warp meter, Figure 5 shows the wafer attached by hand. 6 is an explanatory diagram showing the process of wafer attachment, FIG. 7 is a side view of the bonding device of the present invention, and FIG. 8 is a conventional vacuum chuck. A process diagram of a wafer bonding method according to the present invention is shown. In the figure, l is a vacuum chuck, lo is a spherical suction surface, 1" is a suction hole, 2 is a wafer, 3 is a wax, 4 is a rotating disk for polishing, 5 is an inversion arm, 6 is a stamping jig, and 7 is for pressing. Stamping cylinder, 8 is a wafer rotation cylinder, 9 is a fixing member, 10 is an inversion center, 11 is an elevating cylinder, 12 is a vacuum source. Fig. 2 Fig. 4 Fig. 5 Fig. 6 Sukhno Robin 7 ″ Daily rotation figure 8 (α) (I)) (C)

Claims (5)

[Claims] (1) In a wafer bonding method in which a wafer is bonded to a rotating polishing disk using wax, the wafer is forcibly curved, placed on the rotating polishing disk from the convex side of the curved portion, and bonded. A wafer bonding method characterized by: (2) In a wafer bonding method in which a wafer is bonded to a polishing rotating disk using wax, the wafer is forcibly curved and placed on the polishing rotating disk from the convex side of the curved portion, and the wafer is A wafer bonding method characterized by rotating and bonding while holding down a wafer. (3) In a wafer bonding method in which a wafer is bonded to a polishing rotating disk using wax, the wafer is sucked by a vacuum chuck having a convex suction surface and curved, and the polishing is performed from the convex side of the curved portion. A method for adhering wafers, which comprises placing the wafer on a rotating disk, rotating the wafer while pressing it with a stamping jig, and adhering the wafer. (4) A wafer bonding device for bonding a wafer to a polishing rotating disk using wax, which includes a vacuum chuck having a convex suction surface, a bending means for adsorbing the wafer to the vacuum chuck and bending the wafer; A wafer placement means for placing a wafer on a polishing rotating disk from the convex side of the curved portion, and a wafer placed on the polishing rotating disk is pressed and rotated to adhere the wafer onto the polishing rotating disk. Wafer bonding equipment consisting of a stamping jig. (5) As a means for placing the wafer, the vacuum chuck is provided upward on the end of the reversing arm, attracts the wafer, and inverts the wafer around the other end of the reversing arm. 5. The wafer bonding apparatus according to claim 4, wherein the wafer is placed on a rotating polishing disk placed in the wafer from the convex side of the curved portion of the wafer.