JPH0140072B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an adhesive that can be spray-cleaned to efficiently remove adhesive adhered to the periphery of a semiconductor wafer when polishing the semiconductor wafer after adhering it to a processing plate using an adhesive. This relates to a method for removing.

When polishing (lapping, polishing) a semiconductor wafer, it is necessary to fix the wafer onto a polishing plate using an adhesive such as wax.
As shown in Fig. 1, the wafer is fixed by heating the polishing plate 1 with a heater 2 (a in the figure) and applying an adhesive 3 such as wax to the heated plate 1 (b in the figure). Further, after adhering the wafer 4 thereon (FIG. 3(c)), the adhesive 3 such as wax attached around the wafer 4 is removed (FIG. 2(d)). Conventional removal methods in this case include, for example, immersion using a highly soluble organic solvent such as trichlene, simultaneous immersion and stirring or immersion and vibration (ultrasonic waves), or immersion in a steam bath. However, as shown in Fig. 2, part of the adhesive 3 that contributes to the adhesion between the wafer 4 and the plate 1 is dissolved away or swollen. As a result of the decrease in adhesive strength, the wafer 4 being polished may be damaged or the wafer 4 may be damaged.
The disadvantage is that the back surface is corroded and dirt (foreign matter) adheres to it due to the chemical action of the polishing liquid. In addition, due to this drawback, methods of wiping by soaking gauze, cotton, paper, etc. in an organic solvent are also used instead of the solvent dipping method, but these methods have extremely poor workability and cannot be adopted as a mass production method. do not have.

The present invention aims to provide a method for removing adhesive that eliminates the drawbacks of the conventional methods described above, and its gist is to provide a method for removing adhesive that adheres to the surface and side surfaces of a semiconductor wafer that is adhered to a processing plate with an adhesive. In the method of removing only the adhesive that does not contribute to the bonding using an organic solvent, while the processing plate is rotated, a sprayed organic solvent and high pressure gas are simultaneously applied onto the wafer and the processing plate using a nozzle facing the processing plate. Characterized by spraying.

Hereinafter, the adhesive removal method according to the present invention will be explained based on the embodiments shown in the drawings.

FIG. 3 is a principle diagram illustrating the removal method according to the present invention. When polishing a semiconductor wafer, first, the wafer 4 is fixed to a plate 1 on a rotating table 5 using an adhesive 3 such as wax. The feature of the method of the present invention is that a highly soluble organic solvent such as trichlene is used to remove the adhesive 3 using a nozzle 6 provided above the wafer 4 (workpiece) and facing the wafer 4 using nitrogen gas or The purpose is to reliably remove only the adhesive 3 that does not contribute to adhesion of the wafer 4 by spraying the adhesive 3 together with the high-pressure gas.
Note that the pipe 7 that supplies the organic solvent to the nozzle 6 is connected to a pipe that supplies high-pressure gas such as nitrogen gas, and each pipe is provided with a switching solenoid valve 8.

In this embodiment, the nozzle 6 is applied to the wafer 4 on the rotary table 5.
Since high-pressure gas is sprayed together with a more organic solvent, only the unnecessary adhesive can be reliably removed, and the sprayed organic solvent dries quickly without remaining on the plate 1 and wafer 4. There is no possibility that part of the adhesive 3 contributing to the adhesion between the wafer 4 and the plate 1 as shown in FIG. 2 will be dissolved. Of course, after spraying the organic solvent and high pressure gas for a certain period of time, the pressure feeding of the organic solvent is stopped and only high pressure gas such as nitrogen gas is sprayed from the nozzle 6 to quickly dry the residue of the organic solvent on the adhesive 3. Needless to say, the effects of the present invention are further enhanced.

In addition, when spraying an organic solvent,
plate 1 from the nozzle 6 provided above the wafer 4.
When the organic solvent and high-pressure gas are radiated in a fan shape opposite to the direction of rotation of the wafer 4, a shadow area 3' is created where the organic solvent cannot be directly blown onto the adhesive 3 due to the shape of the wafer 4, and a quick drying effect is achieved. Since this is improved, the effect of removing unnecessary portions of the adhesive 3 in the present invention is further enhanced. At this time, the position of the nozzle 6 and the spraying angle of the organic solvent to be sprayed are determined relative to each other by the amount of the organic solvent to be sprayed, the spraying speed, and the dissolving power for the adhesive, and are not limited in any way. However, in order to further enhance the effect of the present invention, the spraying angle is set for the nozzle 6, and the rotation axis of the plate 1 is tilted, so that the workpiece fixing surface of the plate 1 is tilted. Just rotate it.

For reference, an experimental example is shown in which the thickness of Electron Wax (product name) is first applied on the polishing plate.
After coating to a thickness of 100μ, the workpiece
A GaAs semiconductor wafer was bonded, and pressure was applied for a certain period of time so that the thickness of the adhesive layer between the workpiece and the processing plate was 10 μm or less. Next, spray from the nozzle above the wafer at a pressure of 3Kg/ ^cm2 .
When sprayed in a fan shape at 200c.c./min,
It was possible to remove unnecessary wax around 10 wafers in one minute. By the way, when removing unnecessary wax using the above-mentioned wiping method under the same conditions, it took 70 minutes to remove unnecessary wax around 10 wafers, proving that it was actually 1/70 as effective. Ta.

As described above based on the embodiments shown in the drawings, according to the removal method of the present invention, there is no melting or swelling of the adhesive at the bottom of the workpiece, and unnecessary adhesive is quickly and uniformly removed. It becomes possible to do so.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the process for removing unnecessary adhesive from bonding workpieces, Figure 2 is an explanatory diagram showing defects caused by the conventional removal method, and Figure 3 is an explanatory diagram showing the process of removing unnecessary adhesive from bonding workpieces. It is a principle diagram explaining the invention method. In the drawing, 1 is a plate, 2 is a heater, 3 is an adhesive, 4 is a workpiece, 5 is a rotating table, 6 is a nozzle,
7 is a pipe, and 8 is a switching solenoid valve.

Claims (1)

[Claims] 1. A method in which only the adhesive that does not contribute to adhesion that is attached to the surface and side surfaces of a semiconductor wafer that is adhered to a processing plate with an adhesive is removed using an organic solvent,
A method for removing adhesive by spray cleaning, characterized in that while rotating the processing plate, a sprayed organic solvent and high-pressure gas are simultaneously sprayed onto the wafer and the processing plate using a nozzle facing the processing plate.