JPH0332212B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a wafer processing method. Semiconductor wafers are required to be extremely flat because warping and deformation have a negative effect on the semiconductor devices manufactured, and are subjected to mirror finishing or wrapping. By the way, conventionally, when mirror polishing or wrapping is performed on one side of a wafer, as shown in FIG. After the wafer 3 is placed on the disk 1 and held down by the wafer presser rod 4 and pasted onto the disk 1, a mirror finishing or wrapping process is performed. However, in the above conventional method, if the wafer 3 is warped or deformed, the wafer presser rod 4
Since the wafer 3 cannot be straightened flat, the processed surface of the wafer 3 attached to the flat disk 1 via the wax 2 is parallel to the top surface of the disk 1, as shown in FIG. 1b. do not become. In such a state, for example, when mirror-finishing a wafer, only the surface of the wafer 3' after processing becomes parallel to the upper surface of the disk 1, as shown in FIG.
The disadvantage was that the inner thickness varied. The present invention has been made in order to eliminate the above-mentioned drawbacks, and it is an object of the present invention to provide a wafer processing method that can mirror-finish or wrap a wafer to a uniform thickness. That is, the present invention is a method in which a wafer is attached to a flat disk using wax, and one side is subjected to mirror polishing or wrapping. It is characterized in that it is pasted by moving it parallel to the disk on the applied wax. In the present invention, the wafer chucked by a vacuum chuck is rotated and moved parallel to the disk over the wax coated on the upper surface of the disk. This is to improve the adhesion of the wafer by removing air bubbles between the wax and the wax. The above-mentioned parallel movement is performed by circular movement or linear movement, but circular movement is preferable in order to improve the adhesion of the wafer. At this time, if the wafer movement distance is less than 10 mm, the effect of wax elongation and bubble removal will be low, so the wafer movement distance must be 10 mm or more. Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 2a to 2e. Example First, the warpage is 15 and 30 according to JISH0611 standard.
A wafer 11 (shown in FIG. 2a) having a diameter of 1 inch and a thickness of about 650 μm was chucked by a vacuum chuck 12 having a diameter smaller than that of the wafer 11 to flatten the wafer 11 (shown in FIG. 2b). Next, a vacuum chuck 12 is applied to the top surface of the disk 14 whose top surface is coated with wax 13.
The more chucked wafer 11 is transferred to the disk 14.
It was pressed parallel to the top surface. Next, the eccentric shaft 15 connected on the vacuum chuck 12
The wafer 11 was rotated and moved approximately 20 mm in a circular motion parallel to the disk 14 (Fig. 2c).
(Illustrated). By the above operation, wafer 11 and disk 1
Since the wax 13 between the wafers 11 and 4 is spread thinly and uniformly, and air bubbles between the wafer 11 and the wax 13 are removed, the adhesion of the wafer 11 is improved. Therefore, even if the vacuum chuck 12 is removed, the wafer 1
1 was attached to the upper surface of the disk 14 while being kept parallel to it (as shown in FIG. 2d). Next, mirror finishing was performed on the surface of the pasted wafer according to a conventional method to obtain a semiconductor wafer 11' for integrated circuits (second
(illustrated in Figure e). After mirror polishing, the adhesion accuracy and processing accuracy of the 100 wafers obtained were measured and the results are shown in the table below. In the comparative example in the table, the adhesion accuracy and processing accuracy were measured for 100 wafers that were adhered to a disk and mirror-finished using a conventional method using a wafer presser bar. Here, the attachment accuracy is determined by measuring the wax thickness between the wafer and the disk using an electric micrometer at four points 5 mm from the wafer's outer circumference as shown in Figure 3 when the wafer is attached to the disk. The average value of the difference between the maximum value and the minimum value of thickness and its standard deviation σx are shown. In addition, processing accuracy depends on the wafer thickness after mirror finishing.
It was measured according to the JISH0611 standard, and the table below shows the average value of the difference between the maximum value and the minimum value of wafer thickness and its standard deviation σy.

[Table] As is clear from the table above, the warpage is 15 and 3.
For all of the wafers with 0.0 wafers, both the average value and the standard deviation of the pasting accuracy are smaller in the example than in the comparative example. This shows that the method of attaching the wafer to the disk by the method of the present invention spreads the wax uniformly, and thus shows that the wafer is flat. As a result, for both wafers with warpage of 15 and 30, both the average value and the standard deviation of the processing accuracy in the example are smaller than in the comparative example. That is, it is shown that when a wafer attached to a disk is mirror-finished by the method of the present invention, a wafer with a uniform thickness and no variation can be obtained. As detailed above, according to the present invention, a wafer can be mirror-finished or wrapped to have a uniform thickness, and semiconductor devices with consistent quality can be obtained from this wafer.

[Brief explanation of drawings]

Figures 1 a to c are cross-sectional views showing a conventional wafer processing method, Figures 2 a to e are cross-sectional views showing a wafer processing method in an embodiment of the present invention, and Figure 3 shows points where wax thickness is measured. FIG. 11...Wafer, 12...Vacuum chuck, 13
...Wax, 14...Disc, 15...Eccentric shaft.

Claims (1)

[Claims] 1. In a method in which a wafer is attached to a flat disk using wax and one side is mirror-finished or wrapped, the processed surface of the wafer is chucked with a vacuum chuck, and while the wafer is rotated,
A method for processing a wafer, characterized in that the wafer is pasted by moving it parallel to the disk on wax applied to the upper surface of the disk.