JP3348261B2 - Substrate bonding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of bonding a substrate to a supporting substrate, that is, a grinding mounting step, which is a pretreatment step of a grinding step for thinning the substrate. More particularly, the present invention relates to a grinding and mounting process for attaching a semiconductor device wafer substrate to a support substrate.

[0002]

2. Description of the Related Art In order to grind a semiconductor substrate with high precision, a mounting method is required in which a semiconductor substrate is bonded to a support substrate and fixed so that the whole becomes uniform.
As a method for performing such mounting, a method using a flexible support substrate as shown in FIG. 3 and a method using a hard support substrate as shown in FIG.
No. 44).

In the case of FIG. 3, a semiconductor device wafer substrate 1 which is a wafer on which semiconductor elements are formed and a flexible grinding protection sheet 2 having an adhesive on the back surface serving as a support substrate.
And grinding protection sheet bonding rollers 3, 4
And the semiconductor device wafer substrate 1 is pressed by the grinding protection sheet bonding rollers 3 and 4 so that the surface of the semiconductor device wafer substrate 1 on which the semiconductor element is formed is brought into contact with the bonding surface of the grinding protection sheet 2 and bonded. Was.

In the case of FIG. 4, the bonding apparatus comprises an aluminum cast heater 13a provided on a base 17 via a heat insulating material layer 14a, and an extending portion 19 fixed to the base 17 by a support post 18. The lift shaft 16 is actuated by a pressing mechanism inserted into the shaft, an aluminum cast heater 13b attached to the end of the lift shaft 16 via a heat insulating material layer 14b, and a pressing body 15 made of a heat-resistant cushion material.

A bonding plate 12 on which a number of semiconductor wafers 11 are bonded by wax is placed on the heater 13a, and the elevating shaft 16 is lowered to heat and press at about 190.degree. C. for about 90 seconds and then at about 90.degree. By heating at a low temperature for about 90 seconds, a temperature gradient was not generated between the upper surface and the lower surface of the wax film, so that the final thickness of the wax film was kept constant.

[0006]

However, in the prior art shown in FIG. 3, the semiconductor device wafer substrate 1 is held by the grinding protection sheet 2 which is a sheet-like flexible support substrate.
There is a disadvantage that breakage is likely to occur during handling in the processing step after grinding to a thickness of 20 to 30 μm.

Further, there has been a problem that dust and air bubbles are mixed in the contact surface between the semiconductor device wafer substrate 1 and the grinding protection sheet 2 and it becomes difficult to uniformly bond the whole.

On the other hand, the prior art shown in FIG.
No. 944), the heaters 13a and 13b serving as the reference surfaces when pressed are made of aluminum having a large thermal expansion coefficient, so that the reference surfaces have large thermal distortion and the upper and lower reference surfaces are heated. The heat distortion became larger, and it was difficult to make the final film thickness of the wax uniform.

In this case, since the pressing body 15 made of a cushion material is fixed to the upper heater 13b, which is a heating surface, the pressing body 15 is deteriorated by heat over a long period of use, and uniform pressing is difficult. Had the disadvantage of becoming Furthermore, since the support substrate 12 is opaque, it is difficult to easily confirm the bonding state, and there is a problem in workability.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to manufacture a grinding mount structure in which the whole is uniformly bonded irrespective of the state of the substrate bonding apparatus, and also to prevent breakage of the substrate during handling. It is assumed that.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a method of forming a bonded substrate by bonding a substrate (1 in FIG. 1) on a supporting substrate (23 in FIG. 1) with an adhesive (22 in FIG. 1). The bonded substrate is placed on a lower reference surface (28a in FIG. 1), which is a reference surface on the side where the substrate bonding apparatus is not heated, via a resilient plate-like body (25 in FIG. 1). The bonded substrate was brought into contact with the upper reference surface (28b in FIG. 1) heated to a temperature and preheated, and the bonding material (2 in FIG. 1) was contacted.
2) dissolving, and then pressurizing the bonded substrate to release the excess adhesive (31 in FIG. 1) from the bonding surface.

In this case, the pressing body (2 in FIG. 1) which forms the upper and lower flat reference surfaces (28a and 28b in FIG. 1).
Ceramics are used as 7a, 27b), an elastic resin such as frustoconical silicon rubber is used as an elastic plate-like body (25 in FIG. 1), and a glass substrate is used as a support substrate (23 in FIG. 1). As the material (22 in FIG. 1), wax that has been defoamed in advance is used, and a resilient plate (2 in FIG. 1) is further used.
It is desirable to interpose a release sheet member (24 in FIG. 1) such as paraffin paper between 5) and the substrate (1 in FIG. 1).

[0013]

According to the present invention, only one of the pressing members constituting the flat reference surface is heated to reduce thermal distortion and maintain the flatness of the reference surface with high accuracy. By mounting on the other non-heated reference surface, deterioration due to heat is eliminated, and the elastic plate-like body is not fixed to the reference surface even when degraded over time, so a new elasticity that does not always deteriorate Uniform pressing can be obtained by using the conductive plate.

Then, before the final pressurization, the bonding substrate is brought into contact with the pre-heated upper reference surface, which is preliminarily heated to a predetermined temperature, and the adhesive is melted, so that the upper surface of the adhesive is A uniform pressure can be obtained by preventing a temperature gradient from occurring with the lower surface.

Further, when ceramic is used as the pressing body, a reference plane having a high degree of flatness with less distortion due to heat is obtained because the coefficient of thermal expansion of the ceramic is low, and the elasticity of the elastic plate-like body such as frustoconical silicon rubber is used. When a conductive resin is used, a more uniform pressing can be obtained in the case of a so-called “single-wafer processing”.

Further, since the supporting substrate is a glass substrate, damage during handling in the grinding step or the subsequent processing step is reduced, and the adhesion state such as the state of containing air bubbles can be easily visually checked before the grinding step. You can check.

When a wax defoamed in advance is used as the adhesive (22 in FIG. 1), a uniform and stable film thickness can be obtained because there are almost no air bubbles. When a sheet-like member such as paraffin paper is interposed between the elastic substrate and the pressure-released member, the elastic plate-like body can be attached without applying a tensile force to the bonded substrate that naturally adheres to the upper reference surface. Therefore, unnecessary force is not applied to the wax that is not completely solidified, and the film thickness can be kept uniform.

[0018]

FIG. 1 shows the manufacturing steps of an embodiment of the present invention using the substrate bonding apparatus shown in FIG. 2 in the order of steps.

First, the surface of the Si semiconductor device wafer substrate 1 on which the elements are formed is bonded and adhered to a transparent hard support substrate 23 such as a glass substrate in a clean atmosphere using a defoamed wax 22. A laminated substrate is formed. The defoaming process in this case is to rotate the wax in a plate-like body while applying pressure, and to push out bubbles in the wax in the radial direction by using centrifugal force.

Next, a silicon rubber having a truncated cone shape is placed on a lower pressing body 27a made of a material having a low coefficient of thermal expansion such as ceramics and serving as a sample base of a substrate bonding apparatus and having a flatness of a lower reference surface 28a of about 1 μm. An elastic plate 25 made of such an elastic resin as above is placed, and a bonded substrate is placed on the elastic plate 25 via a separation sheet member 24 such as paraffin paper. [FIG. 1 (A)]

The upper pressing body 27b constituting the upper reference surface 28b of the substrate bonding apparatus is heated to 80 to 90 ° C. in advance by a heater 26 whose temperature is controlled by a control system 30 having a microcomputer. The air cylinder 29 controlled by the control system 30 is driven to push up the lower reference surface 28a to move the bonded substrate to the upper reference surface 28b.
Gently, and left in this state for 5 minutes for preheating to uniformly dissolve the wax 22. [Figure 1
(B)]

Next, while maintaining this heating state, the lower reference surface 28a is further raised by the air cylinder 29, and the control system 30 controls the pressure and the amount of movement while controlling the pressure and the amount of movement.
Excess wax 31 is extruded to the outer periphery of the semiconductor device wafer substrate 1 by pressing the bonded substrate for 10 to 10 minutes. [FIG. 1 (C)]

In this case, it is desirable to fix a dial gauge on the surface of the lower pressing body 27a and measure the amount of movement by bringing the tip of the dial gauge into contact with the upper reference surface 28b.

Thereafter, the pressure is released by controlling the air cylinder 29, and the lower reference surface 28a is lowered.
In this case, the bonded substrate is held on the upper reference surface 28b by natural suction because the contact portion with the upper reference surface 28b is in a vacuum state. [FIG. 1 (D)]

Next, the bonded substrate is placed on the upper reference surface 28.
Then, after removing from the sheet b, the temperature is lowered to room temperature, and after removing the release sheet-like member 24 such as paraffin paper, excess wax 31 is removed and sent to the grinding process.

The air cylinder 29 operates only when the door 20 attached to the support column 21 of the substrate bonding apparatus is closed, and when the bonded substrate is installed on the lower reference surface 28a. Before that, it is necessary to clean the upper and lower reference surfaces 28a and 28b cleanly.

Although there is no particular limitation in the above embodiment, in the case of a so-called "single-wafer processing" in which semiconductor device wafer substrates are processed one by one, the diameter of the top surface of the semiconductor device wafer substrate is reduced. The effect was remarkable when a frustoconical elastic plate-like body smaller than the diameter of the substrate was used.

Further, in the above embodiment, the semiconductor device wafer substrate constituting the three-dimensional semiconductor integrated circuit has been described. However, the present invention is not limited to such a Si semiconductor device wafer substrate. And a compound semiconductor wafer such as GaAs.

[0029]

As described above, according to the present invention, it is possible to obtain a bonded substrate in which the entirety is uniformly bonded, to improve the grinding accuracy in the grinding process, and to reduce the supporting substrate. Since it is harder than the protective sheet, the thin layer semiconductor wafer after grinding is less likely to be damaged and handling becomes easier.

[Brief description of the drawings]

FIG. 1 is a process diagram showing a semiconductor device wafer substrate bonding process according to an embodiment of the present invention.

FIG. 2 is a sectional view of a substrate bonding apparatus used in an embodiment of the present invention.

FIG. 3 is a view showing a substrate bonding step using a conventional grinding protection sheet.

FIG. 4 is a view showing a substrate bonding process using a conventional rigid support substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor device wafer substrate 2 Grinding protection sheet 3 Grinding protection sheet bonding roller 4 Grinding protection sheet bonding roller 11 Semiconductor wafer 12 Adhesion plate (support substrate) 13a Lower aluminum cast heater 13b Upper aluminum cast heater 14a Heat insulating material layer 14b Insulating material layer 15 Pressing body 16 Elevating shaft 17 Base 18 Support 19 Extending part 20 Door 21 Support post 22 Wax 23 Transparent support substrate 24 Paraffin paper 25 Elastic resin 26 Heating heater 27a Lower pressing body (sample table) 27b Upper part Pressing body 28a Lower reference plane 28b Upper reference plane 29 Push-up mechanism (air cylinder) 30 Control system 31 Excessive wax

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-82493 (JP, A) JP-A-61-29878 (JP, A) JP-A-63-221970 (JP, A) JP-A-6-221970 124929 (JP, A) JP-A-64-78735 (JP, A) JP-A-63-198351 (JP, A) JP-A-6-29385 (JP, A) JP-A-2-68436 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/304

Claims (8)

(57) [Claims] A step of bonding a substrate to a supporting substrate with an adhesive to form a bonded substrate, and mounting the bonded substrate on a flat lower reference surface of a substrate bonding apparatus via an elastic plate-like body. Placing the bonded substrate in contact with a flat upper reference surface pre-heated to a predetermined temperature and preheating to dissolve the adhesive, and further pressing the bonded substrate to apply excess adhesive A step of releasing the substrate from the bonding surface. 2. The method according to claim 1, wherein the pressing members forming the upper and lower reference surfaces are made of ceramics. 3. The method according to claim 1, wherein the supporting substrate is a glass substrate. 4. The method for bonding substrates according to claim 1, wherein said elastic plate-like body is a truncated conical elastic resin. 5. The method according to claim 4, wherein the elastic resin is silicon rubber. 6. The method for bonding substrates according to claim 1, wherein a sheet-like member for peeling is provided between said elastic plate-like body and said substrate. 7. The method according to claim 6, wherein the release sheet member is paraffin paper. 8. The method according to claim 1, wherein the adhesive is a defoamed wax.