JPH0651251B2 - Wafer manufacturing method and manufacturing apparatus therefor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a wafer manufacturing method and a manufacturing apparatus for bonding a wafer, which is a substrate of a semiconductor material, onto a polishing rotary disk and then polishing the wafer.

[Conventional technology]

In a wafer polishing method in which one surface of a wafer is bonded to a polishing rotary disk by using wax such as paraffin and the other surface is lapped or mirror-finished, the wafer is flatly bonded to the polishing rotary disk. is important. Conventionally, when bonding wafers, wax is applied to one of the wafer and the rotary disc for polishing, the wafer is placed, and the wafer is bonded by pressing it on the rotary disc for polishing or moving it in parallel. Later, it was subjected to polishing. As shown in FIG. 8 (a), the warped wafer 2 is sucked by the vacuum chuck 1 having the flat suction surface 1 ″ by the vacuum pump 12 as shown in FIG. 8 (b), and the wax 3 is applied. After that, it was pressed and adhered to the upper surface 4 of the rotary disc for polishing as shown in FIG.

[Problems to be solved by the invention]

However, when the wafer is bonded onto the rotating disk for polishing, air bubbles are included between the wafer and the disk, and unevenness of the wax thickness causes unevenness to remain on the polishing surface of the wafer. The parts are scraped off and the wafer has a non-uniform thickness. Further, once air bubbles are contained, it is very difficult to remove it, and in the above-mentioned conventional method, since the wafer is placed in a flat shape when it is placed on the rotary disc for polishing, the wafer is simply pressed or parallel I couldn't solve this problem just by moving.

Therefore, the present invention does not contain air bubbles when placing the wafer on the disc, and can be placed so that the thickness of the wax is uniform, the bonding accuracy is improved, and the wafer can be formed into a uniform film thickness. And an apparatus therefor.

[Means for solving problems]

In order to achieve the above object, the present invention forcibly bends a wafer, mounts it on a polishing rotary disk from the convex side of the curved portion, and rotates the wafer while pressing it to bond it. After that, it is polished.

In order to forcibly bend the wafer, a vacuum chuck having a convex suction surface, especially a spherical suction surface is used, and the wafer is sucked and curved on the suction surface. The wafer is placed from the convex surface side of the section, and is rotated while pressing the wafer with a stamping jig to bond the wafer to the disk, and then polishing is performed.

Further, a wafer manufacturing apparatus therefor includes a vacuum chuck having a convex suction surface, a bending means for adsorbing a wafer to the vacuum chuck to bend the wafer, and then a polishing rotary disk from the convex side of the curved portion of the wafer. And a stamping jig for rotating and adhering the wafer mounted on the polishing rotary disk while pressing it.

[Action]

In a wafer manufacturing method in which a wafer is adhered to a polishing rotary disk using wax and then is polished, the wafer is forcibly curved, and the wafer is placed on the polishing rotary disk from the convex side of the curved portion and bonded. Thus, 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, in the process of restoring the wafer, the action of pushing out the wax and bubbles in the direction of the arrow shown in the figure works, so that the thickness of the wax can be made uniform, and the inclusion of air between the wafer and the disc can be prevented. Because it can be bonded without incorporating air bubbles. Further, since the bonding accuracy can be improved by rotating and bonding the wafer while pressing it, the wafer can be polished to a uniform film thickness.

〔Example〕

 Embodiments will be described below with reference to the drawings.

FIG. 1 is a side view and a bottom view of the vacuum chuck of the present invention, FIG. 2 is a side view when a wafer is sucked by the vacuum chuck of the present invention, and FIG. 3 is a wafer placed on a disk by the vacuum chuck. Fig. 4 is a diagram showing a state in which the wafer is adhered to the disk due to the restoring force, Fig. 4 is a diagram showing measurement points on the wafer used for measuring the amount of warp of the wafer, and Fig. 5 is a diagram showing the wafer stuck by hand. And FIG. 6 is a comparison diagram of an interference fringe method for those adhered by the method of the present invention, FIG. 6 is an explanatory view showing a wafer adhering process, and FIG. 7 is a side view of the adhering device of the present invention.

In the figure, 1 is a vacuum chuck, 1'is a spherical suction surface, 1 "is a suction hole, 2 is a wafer, 3 is a wax, 4 is a rotary disk for polishing, 5 is a reversing arm, 6 is a stamping jig, and 7 is stamping. Cylinder, 8 is a wafer rotation cylinder,
Reference numeral 9 is a fixing member, 10 is an inversion center portion, and 11 is an elevating 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 connected to a vacuum pump in its shaft, and an adsorption surface 1'is formed in a spherical shape. As shown in FIG. 2B, suction holes 1 ″ are concentrically formed on the bottom surface and are connected to the air passages.

When the wafer 2 is placed on the suction surface of the vacuum chuck 1 and sucked by the vacuum pump, the wafer 2 is sucked,
As shown in FIG. 2, the wafer 2 is curved in an arc shape corresponding to the curvature of the suction surface of the vacuum chuck 1. At this time, the relationship between the diameter d of the suction surface of the vacuum chuck 1 and the diameter D of the wafer is preferably in the range of D / 4 <d <D.

Further, x shown in FIG. 2 represents the amount of warp of the wafer. As shown in FIG. 4, the warp amount of the wafer is 4 on the wafer.
Select one measurement point, ie, 1 on the orientation flat side, 2, 3, 4 by 90 ° clockwise, and measure the amount of warpage at each measurement point before and after adsorption with an electric micrometer detector and calculate the difference. The average value was calculated. As a result, the relationship between the amount of warp and the diameter of the wafer is 0.4 to 0.6 mm, and when the diameter of the wafer is 5 cm, the amount of warp is 20 to 50 μm.
Similarly, it has been found that in the case of 7.5 cm, 30 to 80 μm is desirable, and in the case of 4 inches, 40 to 100 μm is desirable. If the amount of warpage is larger than this range, the wafer may crack, and if it is smaller, the effect of the present invention cannot be achieved.

As the wax, fat wax, paraffin wax, or a mixture thereof is used, and an appropriate means such as spin coating is adopted for coating, and the wax may be coated on the wafer surface or on the rotary disk for polishing.

Next, as shown in FIG. 3, the wafer is placed on the polishing rotary disk 4 from the convex surface side of the curved portion, and when suction of the vacuum chuck is stopped, the wafer 2 is placed on the disk 4 by the restoring force of the wafer itself. Flatten with. At this time, by softening the wax by a suitable heating means, the wax and bubbles are pushed out in the direction of the arrow shown in FIG. 3 during the process of restoring the wafer, so that the thickness of the wax is made uniform. In addition, since air can be prevented from being entrapped between the wafer and the disk, it is possible to adhere without incorporating air bubbles.

As means for mounting the wafer on the disk, for example, the sixth
As shown, an inverted vacuum chuck may be used. That is, as the wafer suction means, the suction surface of the vacuum chuck 5 is provided so as to face upward on the end of the reversing arm 5, the wafer 2 coated with wax is adsorbed, and the reversing arm is reversed about the reversing center 10. The wafer is placed on the polishing rotary disk 4 disposed on the other end side of the reversing arm from the convex surface side of the curved portion of the wafer. By using such an inversion chuck, the wafer can be reliably placed on the disk.

In order to further increase the bonding accuracy of the wafer 2 bonded on the disk in this way, the wafer is rotated while being pressed against the disk by the stamping jig 6 arranged on the disk 4. The stamping jig 6 is, as shown in FIG.
It is operated by a stamping cylinder 7 and a wafer rotating cylinder 8 that rotates a wafer during stamping. For the contact surface with the wafer, an oil-resistant elastic member such as silicon rubber is used, and its shape is an arcuate convex surface portion. The wafer rotation cylinder 8 causes the wafer 2 to rotate in one direction to a position before rotation or to rotate at a certain angle in order to improve bonding accuracy and also to align the wafer. Try to return to the previous position. Preferably, the method of rotating by 5 to 90 ° and returning to the position before rotation is repeated 1 to 5 times.

Next, the wafer adhering process using the reversing chuck will be described. First, the wafer 2 is sucked onto the reversing chuck 1 and then the reversing arm 5 is moved to 180 degrees as shown in FIG.
Inverted, then the elevating cylinder 11 lowers the reversal part until the wafer comes into contact with the disk 4, and when suction of the wafer is stopped at the stage when the tip of the wafer comes into contact with the disk, the wafer is restored by the restoring force. Glue flat to Next, the stamping jig is lowered from the upper part of the wafer, the wafer is pressed onto the disk, and the stamping jig is rotated by the wafer rotating cylinder in the pressed state to complete the bonded state.

The wafer bonding method has been described above. As a device therefor, as shown in FIG. 7, a wafer supply unit including a vacuum chuck, a wafer pressing unit including a stamping jig, and a rotary disk for polishing are used. Has been done.

The wafer supply unit is composed of a reversing vacuum chuck connected to a vacuum pump, a mechanism for reversing the reversing arm by 180 °, and an elevating cylinder 11 for lowering the wafer adsorbed by the reversing arm until it contacts the disk. . The wafer pressing unit includes a stamping jig, a stamping cylinder 7 for moving the stamping jig up and down,
And a wafer rotating cylinder 8 for rotating the stamping jig by a predetermined angle when the wafer is pressed onto the disk by the stamping jig, and the whole is supported by a fixed frame 9.

The operation of these various mechanisms is automated by sequentially controlling them by appropriate control means in accordance with the process chart shown in FIG.

〔The invention's effect〕

Regarding the wafer bonded on the disk in this way,
The sticking accuracy was measured. First, FIG. 5 (a) shows a wafer stuck on a disk by hand, and FIG. 5 (b) shows a wafer stuck on a disk using the method of the present invention.
The thickness of the wafer from the top surface of the disk is observed by the interference fringe method, but when it is attached by hand, Newton's rings are often observed in sharp contour lines, and it is observed that the center is convex. . On the other hand, in the case of the one stuck on the disc according to the present invention, it is not seen, and it is observed that the disc is adhered to the disc in a very flat state.

In addition, the total thickness change of the wafer before attachment (Total T
Hickness Variation) and the total thickness change obtained by measuring the parallelism between the wafer and the disk surface by the interference fringe method in the state of being stuck on the disk using the vacuum chuck of the present invention. The accuracy was measured. As a result, the bonding accuracy was 4 to 6 μm at the stage of bonding and stamping on the disk by the vacuum chuck of the present invention, the operation of rotating the wafer by 15 ° while stamping, and then returning to the initial position is repeated twice. As a result, the accuracy was 1 μm or less, the bubbles were completely removed, and the wax was uniformized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view and a bottom view of a vacuum chuck of the present invention, FIG. 2 is a side view of a wafer chucked by the vacuum chuck of the present invention, and FIG. FIG. 4 is a diagram showing a state in which a wafer is placed on a disk and adhered to the disk by the restoring force of the wafer. FIG. 4 is a view showing measurement points on the wafer used for measuring the amount of warp of the wafer. FIG. 6 is a comparison diagram of an interference fringe method between a wafer stuck by hand and a wafer stuck by the method of the present invention, FIG. 6 is an explanatory view showing a wafer sticking step, FIG. 7 is a side view of a manufacturing apparatus of the present invention, and FIG. The figure shows a process diagram of a conventional wafer bonding method using a vacuum chuck. In the figure, 1 is a vacuum chuck, 1'is a spherical suction surface, 1 '' is a suction hole, 2 is a wafer, 3 is a wax, 4 is a rotary disk for polishing, 5 is a reversing arm, 6 is a stamping jig, and 7 is a pressing member. A stamping cylinder, 8 a wafer rotating cylinder, 9 a fixing member, 10 an inversion center, 11 an elevating cylinder, and 12 a vacuum source.

Claims (4)

[Claims] 1. In a wafer manufacturing method in which a wafer is adhered to a rotary disc for polishing with wax and then subjected to polishing, the wafer is forcibly curved and the rotary disc for polishing is polished from the convex side of the curved portion. And put it on top,
A method for manufacturing a wafer, which comprises pressing the wafer while rotating it to bond the wafer, and then polishing the wafer. 2. A wafer manufacturing method in which a wafer is adhered to a polishing rotary disk with wax and then subjected to polishing. In the wafer manufacturing method, the wafer is attracted and curved by a vacuum chuck having a convex attraction surface, and the curved portion A wafer manufacturing method comprising placing a wafer on a polishing rotary disk from the convex surface side, rotating the wafer while pressing it with a stamping jig to bond the wafer, and then polishing the wafer. 3. A wafer manufacturing apparatus in which a wafer is adhered to a polishing rotary disk using wax and then subjected to polishing processing, wherein the adhering means includes a vacuum chuck having a convex suction surface, and the wafer is attached to the vacuum chuck. A bending means for adsorbing and bending, a wafer placing means for placing the wafer on the polishing rotary disc from the convex side of the curved portion of the wafer, and a rotation while pressing the wafer placed on the polishing rotary disc. A wafer manufacturing apparatus comprising a stamping jig for adhering a wafer onto a polishing rotary disk. 4. As the wafer mounting means, the vacuum chuck is provided upward on an end portion of a reversing arm so as to adsorb the wafer and reversing the other end portion of the reversing arm as a center, and the other end of the reversing arm. The wafer manufacturing apparatus according to claim 3, wherein the wafer is mounted on a polishing rotary disk arranged on the side of the wafer from the convex surface side of the curved portion of the wafer.