JPH01216540A - Method and apparatus for adhering semiconductor substrate - Google Patents

Abstract

PURPOSE:To obtain an adhered state of a whole surface adherence with a small amount of adhering material by coating the surface of a wafer with wax, then inverting and steadily placing it on a preheated surface plate, and eccentrically circularly moving it along the outer periphery of the wafer while pressurizing a press head. CONSTITUTION:A wafer is inverted and placed on a surface plate 3 preheated to approx. 80-120 deg.C, and the wafer 1 is steadily placed at a predetermined position on the plate through a wax film 2. A press head 4 having substantially the same size as the diameter of the wafer is pressed on the rear face of the wafer to pressurize it. Then, the center of the head 4 is displaced by (d) from the center (o) of the wafer, and the push rod 5 of the head 4 is so eccentrically rotatably moved as to move the center (o) of the wafer on a circle having a radius (d) at the center (o) of the wafer as a center. Thus, the operation of eccentrically moving the head and pressing it to the rear face of the wafer is repeated to obtain a completely contact state without air bubble remainder over the whole surface of the wafer.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method and apparatus for bonding a semiconductor substrate to a surface plate during surface polishing of the semiconductor substrate.

(Prior Art) In recent years, semiconductor technology has made remarkable progress, and as the performance of semiconductor elements has improved, the production volume has also increased dramatically. Generally, a large number of semiconductor devices are manufactured simultaneously on a mirror-polished semiconductor substrate (wafer) using imaging technology. In such a semiconductor device manufacturing process, the quality of the wafer, which is a base material, is extremely important in order to mass-produce highly reliable, high-performance devices with good yield.

The wafer manufacturing process includes various polishing operations, and extremely high precision processing is required. In order to perform such precision polishing on a large amount of wafers, a plurality of wafers are usually glued onto a surface plate and a large number of such surface plates are slid on the polishing disk. Therefore, the quality of the adhesion of the wafer to the surface of the surface plate affects the accuracy of the polishing process, which in turn greatly affects the performance and yield of semiconductor devices.

A conventional method of bonding a wafer to the surface of a surface plate is as follows. That is, as shown in Figure 2, the process is as follows: (1) First, wax, which is an adhesive, is applied to the wafer surface at room temperature, and (2) it is baked at 60 to 70°C to remove all the volatile content in the wax. After removing (
3) Surface plate (glass plate) preheated to 80-120℃
A method is adopted in which the wafer is inverted and left standing, and (4) a press head is pressed against the back surface of the wafer to apply pressure and bond the wafer (JP-A-54-123148, JP-A-52-155494).
(See Japanese Patent Application Laid-Open No. 56-55052).

(Problem to be solved by the invention) However, when using the above method, the adhesion of the wafer was poor despite the large amount of wax used, and air bubbles remained between the wafer and the surface plate. However, no matter how high the pressure is, it is difficult to remove the bubbles. If the wafer is polished with air bubbles remaining, the wafer surface will be undulated (
dimples) occur, resulting in a quality that cannot be used as a wafer for high-performance devices.

An object of the present invention is to provide a bonding method and apparatus for bonding a wafer to a surface plate that can achieve complete adhesion over the entire surface.

(Means for Solving the Problems) In order to solve the above problems, in the present invention, wax is applied to the wafer surface, the wafer is inverted and placed on a preheated surface plate, and a pre-laser head is pressed against the back surface of the wafer. This is achieved by applying pressure to the wafer, and then moving the press head eccentrically along the outer circumference of the wafer while applying pressure.

In addition, in order to carry out the above method, a press head having a diameter approximately the same as the wafer diameter is used, and a pressurizing device that loads the press head via a push rod connected to the press head, and a pressure device that applies pressure to the press head along the outer periphery of the wafer. Provided is a bonding device for semiconductor substrates, which has a rotational drive device that causes an eccentric circular movement.

The present invention will be explained below with reference to the drawings.

FIG. 1 is a process diagram illustrating the bonding method of the present invention. First, adhesive wax 2 is applied to the surface of wafer 1 at room temperature (FIG. 1(a)). The wax may be liquid, solid, or sticky, and any commonly used wax can be used. The smaller the amount of wax applied, the better.
It is enough.

Next, the wax-coated wafer was heated to 60-70°C for 5 to 50 minutes.
Baking is performed for 10 minutes to remove volatile components in the wax (FIG. 1(b)).

The wafer is inverted and placed on a surface plate (glass plate) 3 that has been preheated to 80 to 120° C., and the wafer lf is placed at a predetermined position on the surface plate through the wax film 2t'' (Fig. 1). (C)).

A press head 4 having a size approximately equal to the diameter of the wafer #1 is pressed against the back surface of the wafer to apply pressure (FIG. 1(d)). The press head 4 is made of a rigid body such as stainless steel, and as shown in FIG. 2, a comb-type cushion 5 with a convex surface is attached to its surface to prevent damage to the wafer l. There is. Further, a push rod 6 is connected to the press head 4, and a pressure device 7 (not shown) and a rotation drive device 8 (not shown) are attached to the other end of the push rod 6.

On the wafer 1 placed on the surface plate 3,
Align the center of the wafer with the center of the wafer and gently press it against the wafer. The pressure at this time is 50 to 500 on the wafer surface.
Requires fl/cyn2. Preferably, the suppression is increased gradually. The fourth device for applying pressure
Both the piston method shown in FIG. 4(a) and the weight method shown in FIG. 4(b) can be used. Figure 4b
), 7 is a piston connected to the push rod, and is joined within the cylinder 8.

Inside the cylinder 8 is a pressurized fluid 9f such as water, air, oil, etc.

When introduced, via piston 7! Pressure can be applied to the rest head 4. The piston system has the advantage of being able to change the pressure continuously.

Further, in FIG. 4(b), a weight W is placed on a weight receiver 6a installed on the upper part of the push rod 6 to apply pressure to the press head 4. Weight eat, W
This is a method in which the pressure is increased stepwise by increasing the pressure sequentially such as 2 and w.

Next, the center of the press head 4 is shifted by a distance d from the center O of the wafer, and the push rod 5 of the press head 4 is eccentrically rotated so as to move on a circle having a radius d centered at the wafer center ot. At this time, the load on the press head remains applied (FIG. 1(e)).

The locus of the eccentric rotational motion is shown in Figure 3.

In FIG. 3, 0 is the center of the wafer 1, and initially the center of the press head 4 also coincides with this position. A is the outer circumference of the wafer 1. When rotating the press head 4, the center is shifted from the center O by a distance d, and the press head 4 is eccentrically rotated so that the center of the press spatula P traces a locus passing on the arc C in the figure. At this time, if the trajectory drawn by the outermost edge of the press head 4 is plotted, it becomes a circle that is distanced by d from the outer periphery of Waeno Sl, as shown in FIG. 3B. The size of d is 1 to 5
(2) is appropriate, and in the case of a silicon wafer with a diameter of 6 inches, it is good to set it to about 2 vm. As described above, by applying eccentric rotational motion to the press head and repeating the pressing operation from the back surface of the wafer several times, it is possible to obtain a complete adhesion state over the entire surface of the wafer with no remaining air bubbles.

(Function) Due to the eccentric rotation movement, air bubbles remaining on the bonding surface are pushed out to the periphery, and at the same time, excess adhesive wax is also pushed out to the wafer periphery, resulting in a complete bonding state with a small amount of wax.

In addition, a ring of oozing wax is formed around the wafer, which has the effect of preventing polishing powder from entering the interface and adhering to the wafer surface as foreign matter.

(Effects of the Invention) According to the present invention, it is possible to obtain a bonded state in which the entire surface is in close contact using a small amount of bonding material. It has high polishing efficiency and produces mirror-finished wafers with a good finish.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the present invention in detail, FIG. 2 is a sectional view of the press head, and FIG. 3 is a diagram showing the locus of the press head.
FIG. 4 is a diagram illustrating a pressurizing method of the press head. Patent Applicant Showa Denko Silicon Co., Ltd. Showa Denko Co., Ltd. Agent Patent Attorney Tera 1) Actual Figure 1 (Wax coating) (Baking) (Silently placed on a surface plate (a) (b) (C
) (pressure) (rotation suppression) Fig. 2, Fig. 3, Fig. 4

Claims (3)

[Claims] (1) After applying an adhesive to the surface of the semiconductor substrate, place it on a preheated surface plate through the adhesive, apply a press head to the back of the substrate, and press the press head while eccentrically moving the substrate along its outer periphery. A method for bonding semiconductor substrates characterized by circular motion. (2) After applying an adhesive to the surface of the semiconductor substrate, it is placed on a preheated surface plate via the adhesive, and pressurized by pressing a press head against the back of the substrate with the center of the press head aligned with the center of the substrate. A method for bonding semiconductor substrates, characterized in that the press head is then eccentrically moved while being pressurized and moved in a circular motion along the outer periphery of the substrate. (3) A device for bonding a semiconductor substrate coated with an adhesive onto a surface plate, which is equipped with a press head having a diameter approximately the same as the diameter of the semiconductor substrate, and a push rod in the center of the press head. A bonding device for semiconductor substrates, characterized in that a pressure device that applies a load to a press head and a rotation drive device that causes eccentric circular movement are combined.