JPH11162801A - Semiconductor substrate and manufacturing method thereof, and semiconductor device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a semiconductor device with greatly improved yield by forming a semiconductor layer with uniform thickness of element on a base substrate. SOLUTION: A silicon substrate of crystal plane orientation <111> is used as a substrate 11, an oxide film 3 for insulating and a polysilicon film 4 for sticking are put between the substrate 11 and a base substrate 2, and thus in selectively polishing using the oxide film 3 as a stopper, the silicon of the plane orientation <111> is hardly etched by chemical agents, and a semiconductor layer having uniform thickness can be formed as an element region.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor substrate for forming a semiconductor element and a method for manufacturing the same, and a semiconductor device and a method for manufacturing the same.

[0002]

2. Description of the Related Art A large scale integrated circuit is formed on an insulator.
OI (Silicon on Insulator) technology is an important technology for achieving high speed, high withstand voltage, radiation resistance, low voltage, and low power consumption of large-scale integrated circuits.

Conventionally, in the manufacture of this type of semiconductor device, after a pattern of an element formation region is formed through a predetermined process on a semiconductor substrate for forming a semiconductor element, it is bonded to a base substrate, and an oxide film is used as a stopper. A method of reducing the thickness of an SOI layer (substrate for forming a semiconductor element) by selective polishing has been performed.

FIGS. 13 to 18 are schematic cross-sectional views showing an example of a conventional manufacturing process for forming such an SOI layer (however, steps in an initial stage are omitted).

As shown in FIG. 13, single crystal silicon having a <100> crystal plane orientation is used as a semiconductor substrate 1 for forming a semiconductor element, and a projection 5 having a predetermined pattern is formed by etching.
And a concave portion 6 are formed on one surface of the substrate 1, an oxide film 3 made of SiO ₂ is formed on the same surface by CVD (chemical vapor deposition) or thermal oxidation, and further a polysilicon film is formed by CVD. 4, 4 'are formed on both sides.

Next, as shown in FIG. 14, both surfaces on which the polysilicon films 4, 4 'are formed are polished by mechanical polishing. As a result, the polysilicon film 4 'on the surface on which the unevenness is not formed is removed, and the polysilicon film 4 on the uneven surface side is flattened.

Next, as shown in FIG. 15, a base substrate 2 made of single crystal silicon having a crystal plane orientation of <100> is bonded onto the flattened polysilicon film 4. Here, since the base substrate 2 and the polysilicon film 4 are made of the same material, they can be bonded without using an adhesive.

Next, as shown in FIG. 16, the upper and lower sides are turned upside down from the state shown in FIG.

Next, as shown in FIG. 17, the surface of the substrate 1 is ground to a predetermined thickness by mechanical grinding using a diamond-bonded grindstone or the like.

[0010] Next, as shown in FIG.
Is polished until the insulating film 3 is exposed by selective polishing while supplying a chemical solution (for example, an amine-based) (in other words, the insulating film 3 is used as a stopper) to form a semiconductor element forming region (hereinafter, referred to as an element region). .) 8 is formed. FIG.
Shows a state of one element region 8 and its vicinity at the time of selective polishing, and a part of FIG. 18 is enlarged for easy understanding.

That is, in this selective polishing, the surface of the substrate 1 is pressed against a polishing pad 9 provided on a rotating disk (not shown), and the disk is rotated while supplying a chemical solution (for example, an amine-based material) to thereby form the insulating film 3. Is used as a stopper for polishing.

[0012]

As shown in FIG.
The polishing proceeds to the stopper 3 by the selective polishing due to the wiping effect of the polishing pad 9 and the etching by the chemical solution, but after the stopper 3, the wiping effect by the polishing pad 9 is weakened, and the chemical etching effect is greatly affected, and the polishing proceeds. I do. However, the time required for polishing to reach the insulating film 3 varies depending on the location or each substrate due to a variation in the thickness of the silicon layer 1 up to the insulating film 3 serving as a stopper and a variation in the polishing rate. .

Therefore, the portion which has reached the insulating film 3 earlier is affected by the chemical etching and the dishing proceeds, and the SO
The thickness of the I layer 8 varies. In the portion where the polishing has reached earlier, as the element region 8 has a finer pattern, the wiping effect is almost eliminated, and the polishing proceeds only by the chemical etching. As shown in FIG.
The depression 10 is easily formed on the surface of the element region 8. Here, "dishing" means a phenomenon in which a semiconductor layer made of polysilicon is eroded by a chemical solution and the center of the surface is dished.

As described above, the abnormal dent on the surface of the element region 8 has a significant effect on the performance of the semiconductor element formed in the element region in the subsequent steps, lowering the product yield and hindering the manufacture of the semiconductor element. Becomes

The present invention has been made in view of the above circumstances, and it is possible to manufacture a device in which a semiconductor layer for forming a device is uniformly formed on a base substrate made of a semiconductor and the yield is greatly improved. For example, an object of the present invention is to provide a semiconductor substrate for SOI and a method for manufacturing the same, and a semiconductor device and a method for manufacturing the same.

[0016]

Means for Solving the Problems The present inventor has made intensive studies to solve the above-mentioned object, and as a result, has found an effective solution to achieve the present invention.

That is, the present invention relates to a semiconductor substrate in which a semiconductor layer for forming a semiconductor element having a crystal plane orientation of <111> is integrated with a base substrate made of a semiconductor via an insulating film. .

According to the present invention, a semiconductor layer having a crystal plane orientation of <111> is formed on a base substrate made of a semiconductor via an insulating film for forming a semiconductor element. In this case, the semiconductor layer is hardly etched by the chemical liquid. As a result, dishing as described above is greatly reduced, and the semiconductor layer is polished to a substantially uniform flat surface. When an element is formed using such a semiconductor, the yield of products can be improved. .

Further, according to the present invention, a semiconductor layer for forming a semiconductor element having a crystal plane orientation of <111> is integrated on a base substrate made of a semiconductor via an insulating film, and the semiconductor layer is integrated with the semiconductor layer. The present invention relates to a semiconductor device provided with:

According to the present invention, since a semiconductor layer is similarly formed using the above-described semiconductor substrate, it is possible to provide a semiconductor device in which a semiconductor element provided in this semiconductor layer is formed favorably.

In the present invention, the crystal plane orientation is preferably <111>.
Forming one surface of a semiconductor substrate for forming a semiconductor element, forming an insulating film on the entire surface of the processed surface, flattening a surface on the insulating film, Bonding the oxidized surface to a base substrate made of a semiconductor, polishing the semiconductor substrate from the surface to the insulating film, and insulatingly separating the semiconductor substrate into a semiconductor element forming semiconductor layer by the insulating film. The present invention relates to a method for manufacturing a semiconductor substrate having:

According to the present invention, the crystal plane orientation is <111>
After performing predetermined processing on one main surface of a semiconductor substrate for forming a semiconductor element, a base substrate made of a semiconductor is bonded to this surface, and the semiconductor substrate is formed by polishing the semiconductor substrate from the surface. Therefore, for example, it is possible to provide a method of manufacturing a semiconductor substrate in which a semiconductor layer is hardly etched by a chemical solution during selective polishing, and a semiconductor layer is formed on a substantially uniform flat surface.

In the present invention, the crystal plane orientation is preferably <111>.
Forming one surface of a semiconductor substrate for forming a semiconductor element, forming an insulating film on the entire surface of the processed surface, flattening a surface on the insulating film, Bonding the oxidized surface to a base substrate made of a semiconductor, polishing the semiconductor substrate from the surface to the insulating film, and insulatingly separating the semiconductor substrate into a semiconductor element forming semiconductor layer by the insulating film. And a step of forming a predetermined semiconductor element on the semiconductor layer.

According to the present invention, since a semiconductor element is formed on the basis of the above-described manufacture of a semiconductor substrate, a good method of manufacturing a semiconductor device can be provided.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION In the above-described semiconductor substrate and the method of manufacturing the same, and the semiconductor device and the method of manufacturing the same according to the present invention, the crystal orientation of the base substrate may be <100>, and the crystal orientation of the base substrate may be <100. 111>.

An oxide film is formed as the insulating film in an uneven shape in cross section, and the semiconductor layer is buried in the concave portion, and a plurality of adjacent semiconductor layers are insulated by the convex portion of the oxide film. It is desirable to have been.

In this case, a semiconductor material is interposed under the oxide film, and the oxide film and the semiconductor material are previously provided integrally with the semiconductor layer in a state where the bottom surface of the semiconductor material is flattened. It is desirable that the bottom surface is bonded to the base substrate.

That is, a semiconductor material layer is formed in advance on the oxide film, and is planarized to form the planarized surface, and the semiconductor substrate is bonded to the base substrate via the planarized surface. desirable.

In this case, for example, an adhesive may be used for bonding. For example, SiO ₂ may be used as a material of the oxide film.
By using a material made of silicon for the semiconductor material layer and the base substrate, bonding can be performed without using an adhesive. Further, the oxide film may be flattened without the intervening semiconductor material layer, and may be bonded to the base substrate with an adhesive.

Further, a chemical solution is used for polishing up to the insulating film. As the chemical solution, for example, amines such as ethylenediamine / pyrocatechol are suitable, but other known chemical solutions may be used. Is also good.

In the above-mentioned polishing, the semiconductor layer can be formed favorably by performing mechanical polishing and chemical polishing, and a semiconductor element can be suitably formed on this semiconductor layer.

[0032]

The present invention will be described below in more detail with reference to examples.

FIGS. 1 to 9 are schematic views showing the steps of forming an SOI layer according to this embodiment. Note that the same reference numerals are used for parts common to the above-described conventional example.

As shown in FIG. 1, the substrate 11 of this embodiment
Differs from the conventional example described above in that a single crystal silicon substrate having a crystal plane orientation of <111> is used as a substrate for forming a semiconductor element.

Then, as shown in FIG. 2, the convex portion 5 and the concave portion 6 having a predetermined pattern are formed on the upper surface of the substrate 11 by etching including photolithography.

Next, as shown in FIG. 3, the surface on which the convex portions 5 and the concave portions 6 are formed is made of SiO ₂ by CVD or thermal oxidation.
An oxide film 3 is formed.

Next, as shown in FIG. 4, a polysilicon layer 4 is formed on the oxide film 3 by a CVD method, and a polysilicon layer 4 'is also formed on a surface opposite to this surface. The polysilicon layer 4 is for flattening by polishing described later, and the thickness of the polysilicon layer 4 'is slightly smaller than the step size of the unevenness on the surface of the polysilicon layer 4 on the opposite side.

Next, the substrate 11 having the polysilicon layers 4 and 4 'formed on both surfaces as described above is mechanically polished on the uneven surface, and the back surface is also mechanically polished as shown in FIG. Then, the polysilicon layer 4 having the uneven surface is flattened, and the polysilicon layer 4 'on the opposite side is removed.

Next, as shown in FIG. 6, a base substrate 2 made of silicon is bonded on the flattened polysilicon layer 4. The crystal orientation <1 for the base substrate 2
00>, the polysilicon layer 4 and the base substrate 2 are bonded together without using an adhesive because they are made of the same material, silicon. That is, the polysilicon layer 4 is interposed between the oxide film 3 and the base substrate 2 for this bonding.

Next, as shown in FIG. 7, the substrate is turned upside down from the state shown in FIG.
I do.

Next, as shown in FIG. 8, the surface of the substrate 11 is ground by a predetermined amount by mechanical grinding using a diamond-bonded grindstone or the like.

Next, as shown in FIG. 9, the surface of the substrate 11 is further polished until the projections (upper projections in the state of FIG. 9) of the insulating film 3 are exposed, and selective polishing using a chemical solution is performed. As a result, the silicon of the substrate 11 in FIG.
O ₂ ) 3 is etched flat by the difference of the etch rate, is insulated and separated into a plurality of element regions 8 divided by the convex portions of the insulating film 3, and is embedded in the concave portions of the insulating film 3.

FIG. 10 shows a state at the time of the selective polishing described above, and is a partially enlarged view of FIG. 9 for easy understanding. As shown in the figure, in this selective polishing, the surface of the substrate 11 in the state of FIG. 8 is pressed against a polishing pad 9 provided on a rotating disk (not shown), and an amine (for example, diethylenediamine / pyrocatechol) as a chemical liquid is applied to the polishing surface. The polishing is performed by rotating the disk while supplying.

That is, Si (OH) ₄ ²⁻ is formed on the surface of silicon by the ionization reaction and the oxidation-reduction reaction of the amine, which generates pyrocatechol and a chelate and dissolves in the amine liquid. Polishing proceeds by rotating the polishing pad 9 and wiping it off. However, SiO _2, which is the material of the oxide film 3, is not polished because it does not react with amine.

In this embodiment, since silicon having a crystal plane orientation of <111> is used as the material of the substrate 11,
The chemical etching rate by the chemical liquid is about 1/10 of that of silicon having a plane orientation of <100> described in the conventional example, and the <111> silicon in the element region 8 is eroded by the chemical liquid during selective polishing. The proportion is significantly reduced. As a result, as shown in FIG.
(That is, dishing) is greatly reduced as compared with the conventional example (see FIG. 19).

Therefore, after the mechanical polishing for forming the state shown in FIG. 8 and the point at which the action of chemical etching is mainly performed to form the state shown in FIG. Since the polishing rate is 1/10 of that of silicon polishing, the chemical liquid only acts after reaching the oxide film 3 serving as a stopper. The degree is greatly reduced, and the variation in the thickness of the element region 8 is significantly reduced.

In general, when the pattern size of the element region 8 is small, the influence on the surface of the element region 8 made of silicon is hardly affected by mechanical polishing, and the influence of the above-described chemical liquid is large. However,
As is clear from the experimental data shown in FIG. 11, in the case of the present invention 12A, even though the size of the element region 8 is small, the dishing amount is smaller than that of the conventional example 12B, which shows the superiority of the present invention. It is.

That is, in the case of a pattern size of 20 μm square or more, the effect of polishing by mechanical action is large,
When the pattern size is less than μm square, the polishing is further affected by the mechanical action at a depth of 20 nm further from the oxide film stopper, and thereafter it is caused by the chemical etching action. However, when this chemical etching action is based on the present invention, Is greatly reduced.

According to the present embodiment, the single crystal silicon having the crystal plane orientation <111> is used as the material of the substrate 11, so that the single crystal silicon having the crystal plane orientation of <100> can be used during selective polishing. Erosion by the chemical liquid is reduced to about 1/10. For this reason, a fine pattern (especially 20 μm)
m or less), the uniformity of the thickness of the element region is improved.

On the SOI substrate after the selective polishing, predetermined semiconductor elements are formed in each element region 8 according to the purpose. FIG. 12 is a schematic cross-sectional view showing a bipolar transistor element, and illustrates an element formed in a state as shown in FIG.

FIG. 12A shows a state before element formation (a state where the selective polishing step is completed). For example, the element region 8 is an N-type collector region 13. Then, as shown in FIG. 12B, after the P-type base layer 14, the N ⁺ -type collector extraction region 16, the P-type base layer 14, and the N ⁺ -type emitter region are formed in the element region 8, A predetermined contact hole is provided by photolithography in an insulating film 17 made of SiO _2, and an emitter electrode 18, a base electrode 19 and a collector electrode 2 are formed through the contact hole.
0 is formed, for example, an NPN-type bipolar transistor is manufactured. Note that a normal impurity diffusion method can be applied as a method for forming each of the above regions, and the conductivity type of each region may be reversed.

According to this bipolar transistor, since the variation in the thickness of the SOI layer is reduced as described above, the thickness of the SOI layer (that is, the element region 8) is reduced and the production of the SOI substrate is stabilized. In addition, even if the interface state density on the surface of the element region 8 is increased by the above-described polishing, the bipolar transistor is not significantly affected by the interface state density. Therefore, the method and the SOI substrate according to the present invention are suitable for devices such as bipolar transistors. Further, various devices using a stable SOI layer can be manufactured and their characteristics can be stabilized.

[0053]

As described above, according to the present invention, the crystal plane orientation is <1 on a base substrate made of a semiconductor via an insulating film.
Since the semiconductor layer for forming a semiconductor element, which is 11>, is integrated, for example, the semiconductor layer is not easily etched by a chemical solution during selective polishing. As a result, a semiconductor substrate in which the semiconductor layer is formed on a substantially uniform flat surface (or thickness) can be obtained, the yield of products can be improved, and a semiconductor layer such as a thinned SOI substrate can be used. A stable semiconductor element can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one manufacturing process of an SOI substrate according to the present invention.

FIG. 2 is a schematic cross-sectional view showing another process of the same.

FIG. 3 is a schematic cross-sectional view showing another process of the same.

FIG. 4 is a schematic cross-sectional view showing another process of the same.

FIG. 5 is a schematic cross-sectional view showing another process of the same.

FIG. 6 is a schematic cross-sectional view showing another process of the same.

FIG. 7 is a schematic cross-sectional view showing another process of the same.

FIG. 8 is a schematic sectional view showing another process of the same.

FIG. 9 is a schematic cross-sectional view showing still another process.

FIG. 10 is an enlarged sectional view of a portion showing a selective polishing state.

FIG. 11 is a graph showing the experimental data.

12A and 12B show a bipolar transistor using an SOI substrate, in which FIG. 12A is an enlarged sectional view of a main part showing a state before element formation and FIG. 12B showing a state after element formation.

FIG. 13 is a schematic cross-sectional view showing one manufacturing step of a conventional SOI substrate.

FIG. 14 is a schematic cross-sectional view showing another process of the same.

FIG. 15 is a schematic cross-sectional view showing another process of the same.

FIG. 16 is a schematic sectional view showing another process of the same.

FIG. 17 is a schematic sectional view showing another process of the same.

FIG. 18 is a schematic sectional view showing still another step of the same.

FIG. 19 is an enlarged sectional view of a part showing the selective polishing state.

[Explanation of symbols]

1, 11: substrate, 2: base substrate, 3: oxide film (insulating film), 4, 4 ': polysilicon, 5: convex portion, 6: concave portion,
8: element region, 9: polishing pad, 10, 10A: dent,
12A: Trend line (this embodiment), 12B: Trend line (conventional example), 13: N-type collector region, 14: P-type base region, 15: N ⁺ type emitter region, 16 ... N ⁺ type collector extraction region

Claims (16)

[Claims] 1. A semiconductor substrate in which a semiconductor layer for forming a semiconductor element having a crystal plane orientation of <111> is integrated with a base substrate made of a semiconductor via an insulating film. 2. The method according to claim 1, wherein the crystal orientation of the base substrate is <100.
> Or <111>. The semiconductor substrate according to claim 1, wherein 3. An oxide film is formed as the insulating film in an uneven shape in cross section, and the semiconductor layer is buried in a concave portion thereof, and a plurality of adjacent semiconductor layers are insulated and separated by a convex portion of the oxide film. The semiconductor substrate according to claim 1, wherein: 4. A semiconductor material is interposed under the oxide film, and the oxide film and the semiconductor material are previously provided integrally with the semiconductor layer in a state where the bottom surface of the semiconductor material is flattened. 4. The semiconductor substrate according to claim 3, wherein the semiconductor substrate is bonded to the base substrate. 5. A semiconductor substrate for forming a semiconductor element having a crystal plane orientation of <111> is integrated with a base substrate made of a semiconductor via an insulating film, and the semiconductor element is provided on the semiconductor layer. Semiconductor device. 6. The base substrate having a crystal plane orientation of <100
> Or <111>. The semiconductor device according to claim 5, wherein 7. An oxide film is formed as the insulating film in an uneven shape in cross section, and the semiconductor layer is buried in a concave portion of the oxide film. A plurality of adjacent semiconductor layers are insulated and separated by the convex portion of the oxide film. The semiconductor device according to claim 5, wherein: 8. A semiconductor material is interposed under the oxide film, and the oxide film and the semiconductor material are previously provided integrally with the semiconductor layer in a state where the bottom surface of the semiconductor material is flattened. 8. The semiconductor device according to claim 7, wherein the semiconductor device is attached to the base substrate. 9. A step of forming an uneven surface on one main surface of a semiconductor substrate for forming a semiconductor element having a crystal plane orientation of <111>, a step of forming an insulating film over the entire surface of the uneven surface, and the insulating film A step of flattening an upper surface, a step of bonding the flattened surface to a base substrate made of a semiconductor, and a step of polishing the semiconductor substrate from the surface to the insulating film, and using the insulating film to form the semiconductor substrate into a semiconductor. Isolating and separating into a semiconductor layer for element formation. 10. The method according to claim 9, wherein mechanical polishing and chemical polishing are performed as the polishing. 11. An oxide film as the insulating film is formed in an uneven shape in cross section, the semiconductor layer is buried in a concave portion of the oxide film by the polishing, and a plurality of semiconductor layers adjacent by a convex portion of the oxide film are interposed. 10. The method of manufacturing a semiconductor substrate according to claim 9, wherein the semiconductor substrate is insulated and separated. 12. A semiconductor material layer is formed on the oxide film, the semiconductor material layer is flattened to form the flattened surface, and the semiconductor substrate is bonded to the base substrate via the flattened surface. 10. The method for manufacturing a semiconductor substrate according to item 9. 13. A step of forming an uneven surface on one main surface of a semiconductor substrate for forming a semiconductor element having a crystal plane orientation of <111>; a step of forming an insulating film over the entire surface of the uneven processed surface; A step of flattening the upper surface, a step of bonding the flattened surface to a base substrate made of a semiconductor, and a step of polishing the semiconductor substrate from the surface to the insulating film, and using the insulating film to divide the semiconductor substrate into an element. A method for manufacturing a semiconductor device, comprising: a step of insulatingly separating a semiconductor layer for formation; and a step of forming a predetermined semiconductor element in the semiconductor layer. 14. The method according to claim 13, wherein mechanical polishing and chemical polishing are performed as the polishing. 15. An oxide film as the insulating film is formed in an uneven shape in cross section, and the semiconductor layer is buried in the concave portion of the oxide film by the polishing, and the plurality of semiconductor layers adjacent to each other by the convex portion of the oxide film. 14. Insulating and isolating
3. The method for manufacturing a semiconductor device according to item 1. 16. A semiconductor material layer is formed on the oxide film, the semiconductor material layer is planarized to form the planarized surface, and the semiconductor substrate is bonded to the base substrate via the planarized surface. 14. The method for manufacturing a semiconductor device according to item 13.