JP2001118760A - Method for sticking semiconductor wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for sticking a semiconductor wafer, capable of sticking it without the need of vacuum when degassing. SOLUTION: After mounting a reinforcing plate on a heating means 1, it is heated, an adhesive material 3 in the state of high viscosity is applied onto the reinforcing plate 2, then the semiconductor wafer 4 is mounted on the reinforcing plate 2 through the adhesive material 3, and then it is pressed and adhered. Then, after the heating means 1 is heated and the temperature is raised to reduce the viscosity of the adhesive material 3, uniform weight is applied from the side of the semiconductor wafer 4. Further, the heating of the heating means 1 is stopped and the semiconductor wafer 4 is stuck to the reinforcing plate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for attaching a semiconductor wafer to a reinforcing plate using an adhesive.

[0002]

2. Description of the Related Art In a semiconductor process, after a semiconductor element such as a light emitting diode or a transistor is formed on a front surface of a semiconductor wafer, the back surface is sometimes mechanically or chemically polished to reduce the thickness. This thinning is performed by attaching the semiconductor wafer to the reinforcing plate such that the front side faces the reinforcing plate. What should be noted when attaching the adhesive to the reinforcing plate is that bubbles are not included in the adhesive. The inclusion of bubbles causes the following problems when the material of the semiconductor wafer is a brittle material such as InP or GaAs. The first problem is that when a semiconductor wafer bonded to a reinforcing plate is polished with a grinding wheel or the like, bubbles in the cured adhesive expand due to heat generation, and the swelled portion is excessively shaved and the thickness is reduced. It is to be uniform. The second problem is that if a heat treatment is performed in a process after the semiconductor wafer is thinned, bubbles expand, applying stress to the semiconductor wafer and damaging the semiconductor wafer itself. In particular, when the portion of the semiconductor wafer expanded by bubbles during polishing is excessively shaved and thinned, the possibility of breakage increases.

[0003] As a method for solving this problem, there is a method disclosed in Japanese Patent Laid-Open No. 7-37768. This comprises a vacuum vessel, a suspending device arranged in the vacuum vessel and suspending a weight, a hot plate disposed opposite to the weight at a predetermined interval, and a hot plate cooling supporting the hot plate. This is a method in which a reinforcing plate is placed on the hot plate using a vacuum device comprising a semiconductor device, and a semiconductor wafer is brought into close contact with the reinforcing plate via a hot melt adhesive. This way,
Before placing the semiconductor wafer, the hot melt adhesive is evacuated to remove volatile components, etc., and then the semiconductor wafer is brought into close contact to perform a defoaming process, so that bubbles remaining in the cured hot melt adhesive are sufficiently reduced. it can.

[0004]

However, after the semiconductor wafer and the reinforcing plate are set in the vacuum container, a vacuum is applied, the semiconductor wafer is attached to the reinforcing plate, and the inside of the vacuum container is returned to atmospheric pressure. Since the work of taking out from the vacuum vessel is required, a great number of man-hours are required, and the productivity is low.

The present invention has been made in order to solve the above-mentioned problems, and provides a method of attaching a semiconductor wafer which can be attached without removing a vacuum for removing bubbles. The purpose is to do.

[0006]

According to a first aspect of the present invention, there is provided a method for attaching a semiconductor wafer, comprising the steps of: placing a reinforcing plate on a heating means; heating the adhesive; and heating the adhesive having a high viscosity. It is applied on the reinforcing plate, and then, after placing the semiconductor wafer on the reinforcing plate via the adhesive, the semiconductor wafer is pressurized and adhered. After raising the temperature to a temperature at which the viscosity becomes low, a uniform load is applied from the semiconductor wafer side, and further, the heating of the heating means is stopped, and the semiconductor wafer is placed on the reinforcing plate via the adhesive. It is characterized in that it is attached.
According to a second aspect of the present invention, in the method of attaching a semiconductor wafer according to the first aspect, the reinforcing plate has a thermal expansion coefficient substantially equal to that of the semiconductor wafer.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for attaching a semiconductor wafer according to an embodiment of the present invention will be described with reference to FIGS. 1A and 1B are views showing a method of attaching a semiconductor wafer according to the present invention, in which FIG. 1A is a cross-sectional view showing an adhesive application step, and FIG. 1B is a cross-sectional view showing a state where a semiconductor wafer is placed in the bonding step. (C) is a cross-sectional view showing a state where the semiconductor wafers are bonded in the bonding step, and (D) is a cross-sectional view showing the weight pressing step.

(Adhesive Coating Step) As shown in FIG. 1A, after a reinforcing plate 2 is placed on a hot plate 1, it is heated to 120 ° C. and then adhered in a state of high viscosity. The agent 3 is applied near the center of the heated reinforcing plate 2. In the above step, the reinforcing plate 2 may be placed after heating the hot plate 1 to raise the temperature to 120 ° C. In this state, since the viscosity of the adhesive 3 is high, the adhesive 3 stays on the reinforcing plate 2 without spreading. Here, as a material of the adhesive 3, a hot melt type wax having a flow start temperature of 94.7 ° C. (Alcowax manufactured by Nikka Seiko Co., Ltd.) is used.
As a material of the reinforcing plate 2, G
When aAs was used, borosilicate glass having a thermal expansion coefficient substantially equal to this was used. The material of the reinforcing plate 2 may be any material having a thermal expansion coefficient substantially equal to that of the material used for the semiconductor wafer 4.

(Adhesion Step) Next, as shown in FIG. 1B, vacuum tweezers 5 are placed on the adhesive 3 accumulated on the reinforcing plate 2.
After the semiconductor wafer 4 made of a GaAs-based material is placed with the surface 4a on which the semiconductor elements are formed facing the reinforcing plate 2, the back surface 4b of the semiconductor wafer 4 is lightly pressed by the vacuum tweezers 5.

In this way, as shown in FIG. 1C, the adhesive 3 is spread from the vicinity of the center of the reinforcing plate 2 toward the peripheral portion, and the semiconductor wafer 4 is bonded to the reinforcing plate 2 via the adhesive 3. . At this time, since the adhesive 3 is spread while expelling air between the semiconductor wafer 4 and the reinforcing plate 2, air bubbles are included in the adhesive 3 bonded between the semiconductor wafer 4 and the reinforcing plate 2. Can be prevented.

(Weight Pressing Step) Further, as shown in FIG. 1 (D), the hot plate 1 is heated to 180 ° C., the viscosity of the adhesive 3 is sufficiently reduced, and After the weight 6 is placed on the hot plate 1 and a uniform load is applied, the heating of the hot plate 1 is stopped and the hot plate 1 is cooled to room temperature. Thus, the semiconductor wafer 4 stuck on the reinforcing plate 2 via the adhesive 3 is obtained.

As described above, after the reinforcing plate 2 is placed on the hot plate 1, it is heated and the adhesive 3 having a high viscosity is applied.
Is applied to the vicinity of the center of the heated reinforcing plate 2, and then the semiconductor wafer 4 is placed on the reinforcing plate 2 via the adhesive 3, and then bonded by applying pressure. Then, after a uniform weight is applied from the semiconductor wafer 4 side while the temperature is increased until the viscosity of the adhesive 3 becomes low, the heating of the hot plate 1 is stopped, and Since the semiconductor wafer 4 is attached to the reinforcing plate 2, a vacuum device for removing air bubbles, which has been conventionally required, is not required, so that the number of man-hours is greatly reduced and the productivity is improved. Also,
Since the reinforcing plate 2 has substantially the same coefficient of thermal expansion as the semiconductor wafer 4, stress caused by a difference in the coefficient of thermal expansion when heated by the hot plate 1 can be reduced.
The semiconductor wafer 4 can be uniformly attached to the reinforcing plate 2 via the adhesive 3.

[0013]

According to the method of attaching a semiconductor wafer of the present invention, a reinforcing plate is placed on a heating means, and then heated and an adhesive having a high viscosity is applied to the heated reinforcing plate. Then, after placing the semiconductor wafer on the reinforcing plate via the adhesive, the semiconductor wafer is bonded by pressing, and subsequently, the heating means is heated to a temperature at which the viscosity of the adhesive becomes low. After being raised to a uniform weight from the semiconductor wafer side, further, the heating of the heating means is stopped,
Since the semiconductor wafer is attached to the reinforcing plate via the adhesive, a vacuum device for removing bubbles, which has been conventionally required, is not required, so that the number of man-hours is greatly reduced and productivity is improved.

[Brief description of the drawings]

FIGS. 1A and 1B are views showing a method of attaching a semiconductor wafer according to the present invention, wherein FIG. 1A is a cross-sectional view showing an adhesive application step, and FIG.
FIG. 4 is a cross-sectional view showing a state where a semiconductor wafer in a bonding step is mounted, FIG. 4C is a cross-sectional view showing a state in which the semiconductor wafer is bonded in the bonding step, and FIG. 4D is a cross-sectional view showing a weight pressing step.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Hot plate (heating means), 2 ... Reinforcement plate, 3 ... Adhesive, 4 ... Semiconductor wafer, 5 ... Vacuum tweezers, 6 ... Weight

Claims (2)

[Claims] 1. After placing a reinforcing plate on a heating means, heating and applying an adhesive having a high viscosity to the heated reinforcing plate, and then applying the semiconductor wafer through the adhesive to the semiconductor wafer. After placing on the reinforcing plate, it is bonded by pressing, and subsequently,
After heating the heating means and raising the temperature to a temperature at which the viscosity of the adhesive becomes low, a uniform load is applied from the semiconductor wafer side, and further, the heating of the heating means is stopped, and the bonding is performed. A method of attaching the semiconductor wafer to the reinforcing plate via an agent. 2. The method according to claim 1, wherein the reinforcing plate has a thermal expansion coefficient substantially equal to that of the semiconductor wafer.