JPH06302569A - Polishing method for wafer - Google Patents

Abstract

PURPOSE:To easily convey to a next step after polishing by holding a wafer in a frame through an adhesive tape, mounting the wafer held in the frame on a chucking table of a polishing apparatus, and conveying the polished wafer to a next step through the frame. CONSTITUTION:A wafer 3 is held on a mount table 6. When the step of mounting on a chucking table 5 is conducted, the wafer 3 is attracted to the center 6a of the table 6. A frame l is attracted to a periphery 6b lowered by one step, and an adhesive tape 2 is so attracted as to be disposed snugly along an upper surface shape of the table 6. A polishing step is performed while pressing the wafer 3 under a suitable pressure. Then, the frame 1 is attracted by an attraction pad to conduct the step of conveying the polished wafer 3 to a next step. Since the wafer 3 is conveyed in a state held by the frame 1, even a large-diameter wafer reduced in thickness after the polishing is not damaged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer polishing method.

[0002]

2. Description of the Related Art Conventionally, when a back surface of a wafer is polished after forming a pattern on a semiconductor wafer, an adhesive tape is attached to protect the pattern formed on the wafer. This adhesive tape is attached to a wafer and then cut to the same size as the wafer. After the polishing is completed, the wafer is peeled off the adhesive tape and transported to the next cleaning step or dicing step.

[0003]

In recent years, the diameter of wafers tends to increase, and when a wafer having a large diameter is processed by the above-described conventional polishing method, a wafer thinned after polishing is likely to be damaged. Transport to the process becomes difficult. Therefore, it is an object of the present invention to provide a method for polishing a wafer, which is designed so as not to be damaged during the transportation to the next process even if the wafer has a large diameter and is thinned after polishing.

[0004]

As a means for technically solving this problem, the present invention provides a step of holding a wafer in a frame via an adhesive tape, and a method of polishing a wafer held in a frame by a polishing apparatus. The gist of the present invention is a method of polishing a wafer, which includes a step of placing the wafer on a chuck table, a step of polishing the wafer, and a step of transporting the polished wafer to the next step through a frame.

[0005]

[Operation] Wafers are held in a frame via adhesive tape and transported while being held in that frame even after polishing, so even large-diameter wafers thinned after polishing will not be damaged. It can be prevented.

[0006]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In FIG. 1, reference numeral 1 is a substantially ring-shaped frame, and a wafer 3 is attached to the center of the frame with an adhesive tape 2 interposed.
Is held. After the step of holding the frame 1, the wafer 3 is placed on the chuck table 5 of the polishing apparatus 4.

A communication table 5a is formed on the upper surface of the chuck table 5, and a mounting table 6 made of a porous material is mounted on the upper surface of the chuck table 5. The mounting table 6 has a central portion 6a.
Is slightly higher than the peripheral portion 6b, and a gentle slope 6c is formed between them. Further, a suction hole 7 is formed in the chuck table 5, and the suction hole 7 communicates with the communication portion 5a so that the wafer 3 can be held on the placing table 6 by a suction action.

When the step of placing the wafer on the chuck table 5 is performed, the wafer 3 is attracted to the central portion 6a of the placing table 6, the frame 1 is attracted to the lowered peripheral portion 6b, and the adhesive tape 2 is placed. It is adsorbed so as to follow the shape of the upper surface of the table 6 exactly. Therefore, the wafer 3 is held in a state of being slightly pushed up from below.

In this case, since the entire upper surface of the chuck table 5 is covered with the adhesive tape 2, it is not necessary to replace the chuck table 5 if the diameter of the wafer 3 is the same and the frame 1 has the same diameter. It does not have to be a universal chuck.

Reference numeral 8 denotes a polishing grindstone in the polishing device 4,
It is rotatably attached to the lower end of the spindle 9, and a polishing process is performed while pressing the wafer 3 with an appropriate pressure. Since the wafer 3 is held at a position one step higher than the surrounding frame 1 as described above, it can be reliably polished by the polishing grindstone 8 and contact with the frame 1 can be avoided.

Reference numeral 10 denotes a conveying means, which has a plurality of suction pads 10a as shown in FIG.
Then, a step of transporting the wafer 3 after polishing to the next step by adsorbing the frame 1 is performed. Since the wafer 3 is transported while being held by the frame 1, even a large-diameter wafer thinned after polishing can be stably transported without damage.

The mounting table of the chuck table is generally made of porous ceramics, metal having a plurality of pores formed therein, and such a material has a relatively high hardness and is polished. The wafer may be damaged when being polished by the pressing force of the grindstone. Therefore, although not necessarily limited, it is preferable that the mounting table or the upper surface of the mounting table is made of porous plastic because a cushioning action occurs and the wafer is not damaged. As the porous plastic, a fluororesin-based sintered body that does not change its shape by a polishing liquid or the like is preferable. Also, the porous diameter is 30 to 60 μm and the porosity is 4
A favorable chuck table can be obtained by forming porous plastic in the range of 0 to 50% and configuring the mounting table. Since this chuck table does not damage the mounting surface of the wafer, a tape for protecting the mounting surface, which is conventionally necessary, is not required in the wafer that does not require a frame unlike the present invention, and the tape is not wasted. It is possible to eliminate the tape attaching work and peeling work.

[0013]

As described above, according to the present invention,
The wafer is held on the frame via the adhesive tape and is transported while being held on the frame even after polishing, so even if the wafer has a large diameter thinned after polishing, it will be transported to the next process. It is not damaged, and even if the diameter of the wafer changes, if the diameter of the frame is the same, the chuck table does not need to be replaced, and the universal chuck need not be used.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a wafer polishing method according to the present invention.

FIG. 2 is an explanatory diagram showing a state in which a wafer is transported after polishing.

[Explanation of symbols]

1 ... Frame 2 ... Adhesive tape 3 ... Wafer
4 ... Polishing device 5 ... Chuck table 5a ... Communication part 6 ... Loading table 6a ... Central part 6b ... Peripheral part 6c ... Sloping surface 7 ... Suction hole 8 ...
Grinding wheel 9 ... Spindle 10 ... Conveying means 1
0a ... Suction pad

Claims (1)

[Claims] 1. A step of holding a wafer on a frame via an adhesive tape, a step of placing the wafer held on the frame on a chuck table of a polishing apparatus, a step of polishing this wafer, and a wafer after polishing. And a step of transporting the wafer to the next step via a frame.