JPS6010870B2 - Warpage correction device for thin substrates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for simultaneously processing and correcting warpage of thin substrates such as semiconductors, glass, and ceramics on both sides.

Since thin substrates such as those described above are easily elastically deformed, it is often difficult to correct warpage.

To explain this with reference to FIG. 1, W with respect to the reference plane S
, the curved thin substrate 1 can be corrected by W2 by removing the upper curved portion a or the lower protruding portion b. However, when only the upper surface curved portion a and the lower protrusion portion b are removed, effective correction is difficult because they are elastically deformed into a flat plate shape due to processing pressure. Conventionally, as shown in FIG. 2, in simultaneous double-sided lapping, the thin substrate 1 to be corrected and the compensating substrate 2, which is thicker by the amount of warpage than the thin substrate 1, are placed between the upper surface plate 3 and the lower surface plate 4. An attempt has been made to correct the thin substrate 1 by removing the curved portion on the top surface and the protruding portion at the bottom while maintaining the natural state in which the thin substrate 1 to be corrected is not elastically deformed as much as possible by supporting the pressure of the surface plate 3 with the compensating substrate 2. .

However, according to this method, in order to correct the warpage of the thin substrate 1, it is necessary to prepare a thicker compensation substrate 2.
Moreover, the number of thin substrates 1 to be modified that can be processed within one lot is therefore reduced. In addition, since most of the pressure from the upper surface plate 3 is applied to the compensation substrate 2, the thickness of the compensation substrate 2 decreases quickly, and the upper surface of the thin substrate 1 to be repaired is applied before the warpage of the thin substrate 1 to be repaired is sufficiently corrected. Pressure is applied to the plate and it deforms elastically. In other words, the correction process cannot be controlled. Therefore, the amount of correction varies depending on the time, and there is a drawback that there is no reproducibility. In view of the above-mentioned points, the present invention provides a warpage correction device for a thin substrate that can control the lowering of an upper surface plate without using a compensation substrate such as a follower, thereby eliminating the conventional drawbacks. , the drawings will be described in detail below.

FIG. 3 shows an embodiment of the present invention, in which 11 is an upper surface plate that can be driven and rotated in one direction, 12 is a lower surface plate that can be driven and rotated in the opposite direction to the upper surface plate 11, and 13 is inserted into a carrier 14. The supported thin substrate to be modified, reference numeral 15, is a supporting arm whose outer end is fixed to the upper surface plate 11 and protrudes radially outward from the rotation center of the upper surface plate 11. It is fixed at equally divided points on the circumference of the surface plate 11.

In the illustrated example, three support arms 15 are used. A micrometer head 1 17 is attached to the tip of the support arm 15.
6 is a sliding shoe that moves vertically.

Reference numeral 18 is an annular bearing which can rotate in the same manner as the upper surface plate 11, has upwardly protruding walls on its inner and outer peripheries for containing lubricating oil 19, and has a flat upper surface that faces the lower surface of the sliding shoe 17. The outer periphery is provided with teeth that mesh with the drive gear 20, and a bearing steel ball 21 is inserted into a recess formed on the lower surface and is driven by the drive gear 20 to rotate on the annular rail 22. It looks like this.

When the annular bearing 18 and the sliding shoe 17 rotate relative to each other, the sliding shoe 17 floats relative to the annular bearing 18 due to dynamic pressure. The size of the floating gap formed between the sliding shoe 17 and the annular bearing 18 due to such levitation, and therefore the vertical position of the upper surface plate 11,
Fine control can be achieved by changing the relative speed with respect to 8. This relative speed increases as the rotational direction of the annular bearing 18 is made opposite to the rotational direction of the sliding shoe 17 and increases its rotational speed, and becomes zero when the rotational direction and rotational speed of both are made equal. Of course. If you know in advance the relationship between the relative speed of the sliding shoe i7 and the annular bearing 18 and the value of the floating clearance, the floating clearance required from time to time will be determined by the corresponding relative This can be achieved by controlling the speed to match the desired speed.

Next, a method of correcting warpage of a thin substrate using the apparatus of the present invention will be explained. First, several thin substrates 13 to be corrected (almost all of the thicknesses and amounts of warpage are not the same) are inserted into each carrier 14, and the upper surface plate 11 is placed thereon. At this time, each correction list board 13 is pressed onto the lower surface plate 12 by the weight of the upper surface plate 11 and is elastically deformed. In this state before warpage correction, both sides of the thin substrate 13 to be corrected are processed to a constant thickness, the thickness of each plate is made uniform, the parallelism is corrected, and the processed state of both sides is made uniform. In this way, the thin substrate 13 to be modified
If we assume that the amount of machining to make the thickness constant is random, and then we finish by machining only the thickness d after warpage correction, we set the slide 16 on the micrometer before warp correction and then press the sliding shoe 17. clearance d between the annular bearing 18 and the annular bearing 18 in the stopped state
o+d, is formed. The annular bearing 18 is then rotated through the drive gear 20. The number of rotations at that time is 11 on the upper surface plate.
The relative speed with respect to the sliding shoe 17 when rotated is set so that the floating clearance formed between the annular bearing 18 and the sliding shoe 17 is d. In this state, upper and lower surface plates 1
1, 12 and the carrier 14, and when both sides of the thin substrate 13 to be modified are simultaneously processed and the thickness is reduced by a certain amount and the floating clearance becomes d, the rotation speed of the annular bearing 18 is increased. , the floating clearance is d2. This is ra-d
, is selected so that it is equal to the maximum amount of warpage of the thin substrate 13 to be corrected. At this time, the thin substrate 1 to be modified was elastically deformed.
3 returns to the original warped state. Thereafter, the rotational speed of the annular bearing 18 is gradually reduced to apply a small processing pressure that does not cause elastic deformation to the thin substrate 13 to be corrected, and the floating clearance is gradually reduced, thereby reducing the warpage of the thin substrate 11 to be corrected. The correction is almost completed. Finally, the annular bearing 18 is rotated in the opposite direction to follow the rotation of the upper surface plate 11 to reduce the floating clearance to zero, thereby completing the shaping process. FIG. 4 shows this correction machining process in relation to the floating clearance and the reduction in the plate thickness of the board 13 to be corrected due to the machining. Curve Q, which is a change curve of the flying clearance due to the generated dynamic pressure, shows a decrease curve of the thickness of the thin substrate 13 to be modified due to processing.

On the machine axis, A is the starting point of machining, and the plate 13 to be processed has a thickness d when it is elastically deformed by being pressed by the weight of the upper surface plate 11. is processed. Dynamic pressure starts at this point, and the rotational speed of the annular bearing 18 is increased to reduce the floating clearance to d.
2, and the A3 point at that time becomes the correction start point. The state of floating clearance is maintained for a short period of time, and then the rotational speed of the annular bearing 18 is gradually decreased, and the correction is almost completed when the floating clearance reaches d. Shaping is performed, and all machining ends at point A5.The modification characteristics (mainly the relationship between machining pressure and machining speed) differ depending on the material of the workpiece plate, but the curves 1, 0, and m, which are separated from curve P, are as described above. The case where the rotational speed reduction process of the annular bearing 18 is changed for materials with different modification characteristics as shown in FIG.

Detection of the point A2 at which the dynamic pressure action starts and the point A5 at which processing ends can be performed by setting the position in the vertical direction of the upper surface plate 11 or by using a mitt switch or the like.

In addition, since the upper surface plate 11 is supported by the support arm 15 from the point A2 where the stress action starts to the point A4 where the correction is almost completed, correction is made by detecting the change in the amount of sagging of the support arm 15 or the machining resistance. You can get an overview of the process. The apparatus of the present invention can be used for simultaneous lapping, polishing, and etching on both sides.

As described above, the present invention has a sliding shoe that can be moved up and down by a micrometer head attached to the tip of a supporting arm that projects from an upper surface plate, and that slides on an annular bearing that can independently drive and rotate the sliding shoe. By changing the relative speed of these two, it is possible to finely control the vertical position of the upper surface plate by changing the floating gap formed between them due to dynamic pressure. Warpage correction can be performed without deformation, and the correction process can be selected in accordance with the processing characteristics of the material of the thin substrate.

Furthermore, since a compensation board like a slave is not required, 1
The number of thin substrates that can be processed in a lot can be increased accordingly.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of warpage removal of a thin substrate, Fig. 2 is a sectional view of a conventional thin substrate warpage correction device, Fig. 3 is a sectional view of an embodiment of the present invention, and Fig. 4 is a correction processing process. An explanatory curve diagram of the relationship between floating clearance and processing amount is shown. 11... Upper surface plate, 12... Lower surface plate, 1
3...Thin substrate to be modified, 14...Carrier, 15...Support arm, 16...Micrometer head, 17...Sliding shoe, 18... annular bearing,
19... Lubricating oil. Ta'zu younger brother Z diagram Ta' zu 3 zu 4

Claims (1)

[Claims] 1 A carrier supporting the thin substrate to be modified is arranged between an upper surface plate and a lower surface plate, and by driving and rotating these upper surface plate, lower surface plate, and carrier respectively, both sides of the thin substrate to be modified are processed. In a thin substrate warpage correction device,
Sliding shoes that can be moved up and down by a micrometer head are attached to the protruding ends of support arms protruding from multiple locations on the upper surface plate, so that they can be driven and rotated concentrically and independently of the upper surface plate. An apparatus comprising an annular bearing that allows the sliding shoe to rotate on an upper plane through a lubricating fluid.