JP2531825B2 - Wafer bonding method and apparatus used for the method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a bonding method for fixing a semiconductor wafer (hereinafter abbreviated as “wafer”) to a ceramic plate in performing mirror polishing. It relates to a device used directly for carrying out the bonding method.

(Prior Art) Wafers are bonded to a ceramic plate with wax and subjected to mirror polishing. The thickness of the wax layer on the lower surface of the wafer is related to the finishing processing accuracy in the mirror polishing. That is, when the wax layer is thick, unevenness in thickness may occur on the mirror-polished polished surface, or parallelism may become poor, causing swelling.

Therefore, the wax has been conventionally manually permeated into the lower surface of the wafer while paying attention to make the thickness of the wax layer existing on the lower surface of the wafer as thin as possible. Specifically, after injecting the wax into the lower surface of the wafer, the operator squeezes out the wax existing on the lower surface of the wafer using a jig, or presses the flat precision surface of the press platen onto the upper surface of the wafer. , The wax on the bottom of the wafer was squeezed out. The thickness of the wax layer thinned by these means was 0.5 μ to 1.0 μ.

(Problems to be Solved by the Invention) As described above, the conventional wax layer has a variation in thickness, which causes a variation in the finishing accuracy of the mirror polishing, thereby making the wax layer thinner and uniform. However, there has been a demand for means for solving this problem.

Furthermore, in the case of processing by hand work, the wax is heated to 150 to 160 ° C when squeezing out, but due to this heat etc. there is a limit to the size and weight of the ceramic plate used, so the maximum number of wafers to be attached is maximum. In addition to being limited to about 5 sheets, when the wafer has a large diameter (for example, 5 inches φ), there is a problem that the thickness of the wax layer for one wafer is not uniform in each part.

The present invention proposes a wafer bonding method and a device used for the method, which can make the wax layer thinner and more uniform.

(Means for Solving the Problems) That is, according to the invention described in the first claim of the present application, a wafer is placed on a ceramic plate, a lower surface of the wafer is impregnated with wax, and the upper surface of the wafer is supported while energizing the wax. In the method of bonding a wafer by pressing and fixing the wafer to a ceramic plate, pressing on the upper surface of the wafer is performed by a non-rotating header having a curved surface portion on the lower surface and a swing arm protruding upward on the upper surface. The lower surface of the wafer is formed by pressing the upper surface of the wafer while mechanically rolling the header by rocking the rocking arm, and squeezing out excess wax existing on the lower surface of the wafer. Is a method for adhering a wafer having a structure in which the wax layer is thinly formed.

According to the second aspect of the present invention, a load plate vertically moved by the operation of a cylinder, a header projecting from the lower surface of the load plate to press the upper surface of the wafer, and a tilting motion of the header are provided. A header mounted on an upper part of the load plate and reciprocally rotated within a certain angle range;
The lower surface has a curved portion, and the upper surface has a swinging arm projecting upward, and the load plate allows the swinging arm to linearly reciprocate in only one direction by loosely fitting the central portion of the swinging arm. The rocking plate has a restricting hole for allowing the top part of the rocking arm to be loosely fitted so as to move the top part in the radial direction of the rocking plate.

(Operation) According to the first aspect of the invention, since the pressing force on the wafer is performed by the mechanically rolling head, the pressing force is always constant and the wax layer on the lower surface of the wafer is uniform. .

According to the second aspect of the invention, the lower surface of the wafer is pressed by the header projecting below the load plate, and at the same time, the swing plate is rotated within a certain angle range to tilt the swing arm. , The pressing point on the upper surface of the wafer having the curved surface is moved from one end to the other end,
As a result, the wax existing on the lower surface of the wafer is squeezed out.

(Example) Hereinafter, the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment of the device according to the present invention, FIG. 2 is an enlarged sectional view of the same waist portion, FIG. 3 is an enlarged sectional view taken along line III-III in FIG. 2, and FIG. Supplementary explanatory diagram regarding the shape, FIG. 5 is a V-V arrow view in FIG. 2,
FIG. 6 is a diagram for explaining the movement of the load point with respect to the wafer, and FIGS. 7 (a) and 7 (b) are diagrams for carrying out the present invention.

 First, the bonding device will be described.

As shown in FIG. 1, the bonding device of the present application has a gate pillar 2 standing on a pedestal 1, a temperature-adjustable cushion plate 3 placed on the pedestal 1, and the gate pillar 2, the pedestal 1 and a roof plate 4 as described above. A load plate 5, a header 6 and an oscillating plate 7, which will be described later, are arranged in the space partitioned by.

Reference numeral 8 denotes a cylinder attached to the center of the roof plate 4, the operating rod 9 of the cylinder 8 projects downward, and the above-mentioned load plate 5 is attached to the lower end of the operating rod 9. That is, the load plate 5 moves up and down by the operation of the cylinder 8. The load plate 5 has an upper portion having a small diameter (hereinafter, the portion is referred to as "boss portion 5a") and a lower portion having a large diameter (hereinafter, the portion is referred to as "flange portion 5b").
The upper plate 10 is attached to the upper surface of the load plate 5, and the legs 11 are attached to the upper plate 10 at the end edges in a hanging shape. On the upper plate 10, a hooking alloy tool 12 for fixing to the operating rod 9 is fixed, and on the upper plate 10, a screw hole 15 is formed so that a plurality of weights 13 are fixed by bolts 14. There is. Reference numeral 16 is a bearing of a gear 17 which will be described later.
16 is also mounted on the top plate 10. The above-mentioned leg 11 is the gatepost 2
It is engaged by a guide piece 18 mounted on the load plate 5, so that the load plate 5 does not rotate accidentally.

The header 6 is projectingly provided on the lower surface of the load plate 5 described above. This header 6 has a heat-retaining function of 150 to 160 ° C., its lower surface is a curved surface 19, and its upper surface has a prism-shaped rocking arm 20 projecting from the top of the rocking arm 20. It has 21. However, the curved surface 19 is formed only in the central portion, and the end edge portion is formed to be a straight line when viewed from the side. If the end edge is curved, line pressing will be applied to all parts of the wafer 22.
This is because a crack 23 may occur at the end of the wafer 22 as shown in the figure.

Reference numeral 24 is a rotary roller attached to the lower part of the swing arm 20, and the rotary roller 24 plays a role of receiving the load of the load plate 5. Reference numeral 25 is a retaining pin attached to the swing arm 20 slightly above the rotary roller 24.

The header 6 including the swing arm 20 is attached to the load plate 5 via the frame 26.

Specifically, the receiving hole 27 is formed in the lower surface of the load plate 5.
And a frame 26 is fitted into the receiving hole 27, and a top plate of the frame 26 is formed.
28 and the bottom of the receiving hole 27 (a portion that is recessed upward in the drawing) are connected by a wire 29 and a spring 30, and the retaining pin 25 is provided above the top body 28 of the frame body 26, The rotating roller 24 is located below the top plate 28, in other words, the retaining pin 25
The header 6 is attached with the top plate 28 sandwiched between the rotary roller 24 and the rotary roller 24.

Reference numeral 34 is a restriction hole penetrating the flange portion 5b of the load plate 5, and the restriction hole 34 is formed as an elongated hole facing the center of the load plate 5 like the groove holes 32 and 33. Hole 34
The prismatic swinging arm 20 of the header 6 is inserted into this. Therefore, the swing arm 20 is configured to swing in the direction of the center of the load plate 5.

The rocking plate 7 is rotatably attached to the boss portion 5a of the load plate 5 and meshes with a gear 17 driven by a motor 36. Then, the rocking plate 7 is attached to the rocking plate 7.
A long hole 35 is formed such that one end comes closer to the center of the rocking hole and the other end goes away, and the spherical head 21 of the swing arm 20 is fitted into the long hole 35. In other words, by driving the motor 36, through the gear 17,
The oscillating plate 7 is reciprocally rotated by a predetermined angle (the angle within which the spherical head 21 moves from one end of the elongated hole 35 to the other end), and the spherical head is moved.
The oscillating plate 21 is configured to reciprocate linearly in the radial direction.

Next, a description will be given of the execution of bonding using the above-described apparatus of this example.

First, place 12 wafers of a 4-inch diameter wafer 22 at a predetermined position on a ceramic plate 38 and inject 8 pieces of a 5-inch diameter wafer 22 into which wax 39 is injected, and the wax 39 penetrates into the lower surface of the wafer 22. (See FIG. 7).

On the other hand, the cylinder 8 is driven to raise the load plate 5, the frame body 26 attached to the load plate 5 and the header 6 on which the frame body 26 is suspended by about 125 mm, and the spherical head 21 is elongated. Set it on the edge near the outside of 35, and place the wax-impregnated ceramic plate 38 prepared above from 150 to 1
The cushion plate 3 heated to 60 ° C. is aligned and set, and the cushioning material 40 is applied to the upper surface of the wafer 22. The cushioning material 40 is a paper having a pressure of about 80 μm, and has two roles of imparting a pressure gradient to the pressing force of the curved surface 19 and preventing foreign matter from entering.

Next, the cylinder 8 is operated to lower the load plate 5, and the headers 6 heated to 150 to 160 ° C. are transferred to the wafers.
The wafer 22 is brought into a state of being loaded by causing the outer edge of the wafer 22 to be negotiated. Here, the edge of the wafer 22 is apt to generate a crack 23 when receiving a pressing force, but in this case, the wafer 22 is pressed by the flat surface portion of the header 6 and the crack 23 does not occur.

Then, the motor 36 is driven to intervene the gear 17 to rotate the oscillating plate 7. As a result, the spherical head 21 of the oscillating arm 20 moves in the elongated hole 35 from the outer side to the inner side to form the curved surface of the header 6. Department
19 rolls, and the pressing point by the header 6 moves from the outer edge to the inner edge of the wafer 22. During this process, the load plate 5 and other loads are always applied to the wafer 22 via the rotating roller 24, and thus the wax 39 (which is received by the cushion plate 3 and the header 6 to flow on the lower surface of the wafer 22 and flows). Wax with improved properties
39) will be squeezed out from the outside to the inside.

The level L of the load applied to the rotary roller 24 when the header 6 rolls fluctuates, but in the above-described embodiment, the frame body 26 is attached to the load plate 5 by the wire 29 and the spring 30. The spring 30 expands and contracts when the level L changes, and the load itself does not change.

Thus, if the pressing point moves to the inside, the wafer
22 The wax layer on the lower surface is 0.4 μm or less. Here, the cylinder 8 is operated to pull up the load plate 5 and the header 6 to the upper limit position, and the motor 36 is reversely driven to rotate the rocking plate 7 in the reverse direction. , Return the header 6 to its original position.

The movement of the device so far is one cycle, which is about 90 seconds. The movement of one cycle of the above apparatus can be automatically performed by using a sensor or a limit switch, and the buzzer can be used to notify the end of one cycle.

(Effects of the Invention) As described above, according to the invention of the present application, it is possible to reduce the thickness of the wax to 0.4 μ or less without variation, and as a result, the processing accuracy in mirror polishing is significantly improved. Further, the device of the present invention has the advantage that the labor can be saved and the adhesion process can be increased.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the device according to the present invention, FIG. 2 is an enlarged sectional view of an essential part thereof, FIG. 3 is an enlarged sectional view of III-III in FIG. 2, and FIG. 4 is a header. 5 is a supplementary explanatory view relating to the shape of FIG.
FIG. 6 is a diagram for explaining the movement of the load point with respect to the wafer, and FIGS. 7 (a) and 7 (b) are diagrams for carrying out the present invention. 5 ... Load plate, 6 ... Header, 7 ... Oscillating plate,
8 ... Cylinder 20 ... Oscillating arm, 22 ... Wafer, 35 ... Oblong hole 38 ... Ceramic plate, 39 ... Wax

Claims (2)

(57) [Claims] 1. A method for adhering a wafer, wherein a wafer is placed on a ceramic plate, the lower surface of the wafer is impregnated with wax, and the upper surface of the wafer is pressed while heating the wax to fix the wafer to the ceramic plate. The pressing of the wafer to the upper surface is performed by a non-rotating header having a curved surface portion on the lower surface and a swinging arm protruding upward on the upper surface.
By swinging the swing arm, the upper surface of the wafer is pressed while being mechanically rolled, and excess wax existing on the lower surface of the wafer is squeezed out to form a thin wax layer on the lower surface of the wafer. A method for adhering a wafer, which is characterized in that 2. A load plate, which is moved up and down by the operation of a cylinder, a header projecting from the lower surface of the load plate to press the upper surface of the wafer, and an upper portion of the load plate for tilting the header. And a swing plate that is reciprocally rotated within an angle range. The header has a curved portion on a lower surface and an upwardly protruding swing arm. There is a restriction hole for loosely fitting the central portion of the arm to allow the swing arm to linearly reciprocate only in one direction, and the swing plate loosely fits the top portion of the swing arm to move the top portion. An adhesive device having an elongated hole for moving the oscillating plate in the radial direction.