JP2002299589A - Adhesive semiconductor substrate - Google Patents

Abstract

(57) [Problem] To enable a support substrate to be peeled as easily as possible and to suppress an increase in manufacturing cost as much as possible. SOLUTION: A first substrate 11, a second substrate 12, and
The first and second substrates are provided between the first and second substrates for bonding the first and second substrates, and are made of a material having a higher etching rate than the etching rates of the first and second substrates. And the intervening layer 13 that has been removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive semiconductor substrate, and more particularly, to an adhesive semiconductor substrate capable of separating a bonded support substrate after or during a process for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art Generally, semiconductor devices are formed on the surface of a semiconductor wafer. The depth required for device operation is several μm
Therefore, even a thick one such as a high withstand voltage element is at most 200 μm
It is about. On the other hand, the wafer must have a certain thickness in terms of strength and handling, and the standard thickness is 625 μm for a silicon wafer having a diameter of 150 mm or less, and 725 μm for a silicon wafer having a diameter of 200 mm.

Therefore, a few hundred μm on the back side of the wafer is an unnecessary area in terms of device characteristics. In addition to the unnecessary portions, the extra thickness portion often deteriorates the device characteristics, such as an increase in electric resistance and a carrier remaining at the time of switching to hinder high-speed operation.

[0004] For this reason, it is ideal to use a wafer having a thickness necessary for the element. However, when the thickness is small, the wafer is often broken and cannot be handled.

As a countermeasure, a method has been attempted in which a thin wafer is bonded to a support substrate to perform an element structure process, and finally the support substrate is peeled off.

[0006] Wafer bonding is ideal for such a purpose because the wafer can be firmly integrated without using an adhesive. However, there is a case where a problem arises in that the supporting substrate cannot be peeled off due to high bonding strength. is there.

As a solution to this, as shown in FIG. 6, a semiconductor substrate 21 and a support substrate 22 are sandwiched with an oxide film 23 interposed therebetween.
SOI (Silicon On Insulato)
r) It has been proposed to use a bonded wafer 20 having a structure. That is, after forming elements on the semiconductor substrate 21, a protective film (not shown) is provided on the surface, the bonded wafer 20 is immersed in hydrofluoric acid, and the intermediate oxide film 23 is selectively etched. The support substrate 22 is separated.

[0008]

However, in this method, the etching of the oxide film 23 requires more than one week, and there is a problem that it is difficult to maintain the protective film.

As another method, the supporting substrate 22 and the oxide film 2
3 can be etched from the back side. If the support substrate 22 is etched with hydrofluoric acid, the etching stops at the oxide film 23. After that, the oxide film 23 may be etched with hydrofluoric acid. Further, it can be combined with a method of thinning the support substrate by mechanical grinding.

However, in this method, the supporting substrate 22
Is disposable, which causes a problem that the manufacturing cost is increased.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above circumstances, and an object of the present invention is to make it possible to peel a supporting substrate as easily as possible and to suppress an increase in manufacturing cost as much as possible. It is an object of the present invention to provide a bonded semiconductor substrate that can be used.

[0012]

According to the present invention, there is provided an adhesive semiconductor substrate comprising a first substrate, a second substrate, and the first substrate for bonding the first substrate and the second substrate. A first substrate and a second substrate provided between the substrate and the second substrate;
And an intervening layer made of a material faster than the etching rate of the substrate and partially removed.

Preferably, the portion from which the intervening layer has been removed is a continuous space.

It is preferable that the peripheral portions of the first and second substrates are joined and integrated via an intervening layer.

[0015] The first and second substrates may be made of silicon, and the intervening layer may be a silicon oxide film.

Further, the adhesive semiconductor substrate according to the present invention comprises:
A first substrate provided with a plurality of grooves on a surface thereof, a second substrate, and a first substrate and a second substrate for bonding the first substrate and the second substrate. An intervening layer provided between the first and second substrates and made of a material faster than the etching rate of the first and second substrates.

[0017]

Embodiments of the present invention will be described with reference to the drawings.

(First Embodiment) A first embodiment of an adhesive semiconductor substrate according to the present invention will be described with reference to FIGS. 1 (a) and 1 (b). FIG. 1A is a cross-sectional view showing the configuration of the first embodiment, and is a cutting line BB ′ shown in FIG. 1B.
1 (b) is a cross-sectional view taken along a cutting line AA ′ shown in FIG. 1 (a).

In the adhesive semiconductor substrate of this embodiment, an element forming substrate 11 made of, for example, silicon is bonded and integrated with a supporting substrate 12 via an intervening layer 13 made of, for example, an oxide film. Then, a structure in which a part of the oxide film 13 is removed to form a continuous space is formed. In this embodiment, as shown in FIG. 1B, the divided oxide film 13 is, for example, a square having a side length of 20 μm, and
They are arranged at a pitch of μm. With this configuration, the bonding area is reduced to 1/25 as compared with the entire surface bonding, and the bonding strength is reduced in proportion thereto, but a sufficient strength to withstand the element forming process is maintained.

When the support substrate 12 is removed, a protective film (not shown) may be provided on the surface of the element forming substrate 11 if necessary, and may be immersed in hydrofluoric acid. At this time, if a hydrofluoric acid tank is installed in a vacuum vessel, and the air is drawn between the oxide films 23 by evacuating and dipping in hydrofluoric acid, hydrofluoric acid can easily penetrate into the interior. In the present embodiment, since a continuous space is formed by removing a part of the oxide film 23, the etching can be performed in a short time because hydrofluoric acid can easily enter the inside of the oxide film 23. The support substrate 12 can be easily separated in 30 to 60 minutes. Further, since the separated support substrate has a mirror-finished surface, it can be reused as it is. For this reason, an increase in manufacturing cost can be suppressed as much as possible.

Next, a method for manufacturing the bonded semiconductor substrate of the first embodiment will be described with reference to FIG. FIG. 2 is a cross-sectional view showing a manufacturing process of the bonded semiconductor substrate of the first embodiment.

First, a support substrate 12 is prepared, and its surface is oxidized to provide an oxide film 13 (see FIG. 2A). Note that the thickness of the oxide film 13 was 1.5 μm. Next, the oxide film 13
Is partially removed by patterning (see FIG. 2B). The pattern may be arbitrarily determined, and may be determined based on the required adhesive strength and etching time. In addition, it is not necessary to remove all of the oxide film, and it is sufficient to simply dent the surface.

Next, the supporting substrate 12 is replaced with the element forming substrate 11.
Adhesive and integrated. The element forming substrate 11 may be of a desired thickness from the beginning, or a wafer of a standard thickness may be bonded, and then the thickness may be reduced by polishing or the like.

As can be understood from the above description, the intervening layer 13 need not be an oxide film as long as the material has a higher etching rate than the element forming substrate 11 and the supporting substrate 12. Nor.

The element forming substrate 11 may not be a silicon substrate.

(Second Embodiment) Next, a second embodiment of the adhesive semiconductor substrate according to the present invention will be described with reference to FIG. FIG. 3 corresponds to FIG. 1B of the first embodiment.
It is sectional drawing of 2nd Embodiment. As shown in FIG. 3, the adhesive semiconductor substrate 10A according to the second embodiment is different from the adhesive semiconductor substrate 10 according to the first embodiment in that an oxide film 13a is left around the entire substrate. The pattern is devised. The thickness t of the oxide film 13a in the horizontal direction was 10 μm. The pattern of the inner oxide film 13 may be arbitrary.

In the first embodiment, since there is a gap in the oxide film 13, there is an inconvenience that a chemical permeates into the gap during the element forming process. However, the second embodiment has an effect of preventing this.

In the second embodiment, as in the first embodiment, the support substrate 12 can be peeled as easily as possible, and the increase in the manufacturing cost is suppressed as much as possible. be able to.

(Third Embodiment) Next, a third embodiment of the adhesive semiconductor substrate according to the present invention will be described with reference to FIG. FIG. 4 is a cross-sectional view showing a manufacturing process of the bonded semiconductor substrate of this embodiment. The adhesive semiconductor substrate 10B of this embodiment has a configuration in which GaAs is used as the support substrate 42 and GaAlAs is used as the intervening layer 43.
In addition, blade dicing, which does not require a mask and can be easily performed, can be used for removing the intervening layer 43.

First, on the surface of a GaAs support substrate 42 having a diameter of 100 mm and a thickness of 625 μm, an AlGaAs layer 43 having an Al composition ratio of 0.75 is epitaxially grown to a thickness of 5 μm as an intervening layer (see FIG. 4A). ). continue,
Using a diamond blade having a thickness of 120 μm, a groove 44 having a depth of 4 μm was formed on the surface of the intervening layer 43 by 150 μm.
m, and a part of the intervening layer 43 is removed (see FIG. 4B).

Next, the diameter is 100 mm and the thickness is 120 μm.
m of the device forming substrate 41 of GaAs
The adhesive semiconductor substrate of the present embodiment is obtained by bonding and integration with the support substrate 42 via 3 (see FIG. 4C). An element is formed on the element forming substrate 41 of the adhesive semiconductor substrate 10B, a protective film (not shown) is formed on the entire surface, and then the intermediate layer 43 is selectively etched using hydrofluoric acid to form an element. The substrate 41 and the supporting substrate 42 are separated (see FIG. 4D).

The intervening layer having an Al mixed crystal ratio of 0.75 has an etching rate of about 10 μm / min with respect to hydrofluoric acid. On the other hand, since the element forming substrate 41 and the supporting substrate 42 made of GaAs are not substantially etched by hydrofluoric acid, selective etching becomes possible. Thereby, the support substrate can be easily peeled off. Further, since the intervening layer 43 is selectively removed from the separated support substrate 42, the support substrate 42 can be reused, thereby suppressing an increase in manufacturing cost.

As described above, in the adhesive semiconductor substrate of this embodiment, the supporting substrate can be peeled as easily as possible, and the increase in manufacturing cost can be suppressed as much as possible. .

(Fourth Embodiment) Next, a fourth embodiment of the adhesive semiconductor substrate according to the present invention will be described with reference to FIG. FIG. 5 is a cross-sectional view illustrating a manufacturing process of the bonded semiconductor substrate 10C of the present embodiment. The adhesive semiconductor substrate 10C of this embodiment has a configuration in which it is not necessary to remove a part of the intervening layer 53.

First, as shown in FIG. 5A, a groove 54 is provided on the surface of a support substrate 52 made of silicon. In the present embodiment, the support substrate 52 having a plane orientation of (100) is selectively etched by KOH using an oxide film as a mask, and a V-shaped groove 54 having a wall surface orientation of (111) is provided. Groove 54
Is 10 μm, the depth becomes 7.1 μm. The groove 54 may be formed by another method, for example, isotropic etching or blade dicing.

Next, the substrate is thermally oxidized to provide an intervening layer 53 made of an oxide film having a thickness of 1 μm on the surface of the substrate (see FIG. 5C). Thereafter, an element forming substrate 51 is bonded and integrated to this substrate to obtain an adhesive semiconductor substrate of the present embodiment (see FIG. 5D).

In this embodiment, although a part of the intervening layer 53 is not removed, since the grooves 54 are continuous, etching for efficiently separating the supporting substrate is performed as in the other embodiments. It can be carried out. Further, since the groove 54 is provided in the separated support substrate 52, the second and subsequent reuses can be performed from the formation of the intervening layer 53.

As described above, also in the adhesive semiconductor substrate of the present embodiment, the supporting substrate can be peeled as easily as possible, and the increase in manufacturing cost can be suppressed as much as possible. .

[0039]

As described above, according to the present invention, the supporting substrate can be peeled as easily as possible, and the increase in the manufacturing cost can be suppressed as much as possible.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the configuration of a first embodiment of an adhesive semiconductor substrate according to the present invention.

FIG. 2 is a manufacturing process cross-sectional view showing a manufacturing process of the bonded semiconductor substrate of the first embodiment.

FIG. 3 is a sectional view showing a configuration of a second embodiment of the adhesive semiconductor substrate according to the present invention.

FIG. 4 is a sectional view showing a manufacturing process of a third embodiment of the adhesive semiconductor substrate according to the present invention.

FIG. 5 is a sectional view showing a manufacturing process of a fourth embodiment of the bonded semiconductor substrate according to the present invention.

FIG. 6 is a cross-sectional view showing a configuration of a conventional adhesive semiconductor substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10, 10A Adhesive semiconductor substrate 11 Element formation substrate 12 Support substrate 13, 13a Oxide film (intervening layer) 20 Adhesive semiconductor substrate 21 Element formation substrate 22 Oxide film 23 Support substrate

Claims (5)

[Claims] A first substrate, a second substrate, and a first substrate provided between the first substrate and the second substrate for bonding the first substrate and the second substrate. And an intermediate layer made of a material having a higher etching rate than the etching rates of the first and second substrates and partially removed. 2. The adhesive semiconductor substrate according to claim 1, wherein the portion from which the intervening layer is removed is a continuous space. 3. The adhesive semiconductor substrate according to claim 1, wherein peripheral portions of said first and second substrates are joined and integrated via an intervening layer. 4. The adhesive semiconductor substrate according to claim 1, wherein said first and second substrates are made of silicon, and said intervening layer is a silicon oxide film. 5. A first substrate having a plurality of grooves on its surface, a second substrate, and the first substrate and the second substrate for bonding the first substrate and the second substrate. And an intervening layer provided between the first and second substrates and made of a material faster than the etching rate of the first and second substrates.