JPH06196674A - Manufacture of semiconductor substrate - Google Patents

Abstract

PURPOSE:To realize the manufacture of a semiconductor substrate, in which a dicing process is eliminated and the contamination of silicon powder generated by the dicing process and the reduction of the area of the substrate are prevented, in manufacture, in which the semiconductor substrate with a single- crystal semiconductor layer is acquired on an insulator through a laminating method. CONSTITUTION:The manufacture of a semiconductor substrate has a process (1), in which a P-type silicon substrate 5 with a thin N-type silicon layer 4 is formed onto one main surface, a process (2), in which the side of the N-type silicon layer 4 of the substrate is laminated on another substrate 13 through an insulating film 3, a process (3), in which an N-type semiconductor 14 is shaped on the peripheral section of at least the N-type silicon layer 4 and an opening section is formed to the main surface of the P-type silicon substrate 5, and a process (4), in which the P-type silicon substrate 5 is removed through etching electrochemically while the N-type semiconductor 14 is used as one electrode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor substrate, and more particularly to a method for forming a semiconductor substrate suitable for an integrated circuit formed on a single crystal layer on an insulator.

[0002]

[Prior Art A] Conventionally, the following method has been known as a method for manufacturing a semiconductor substrate suitable for an integrated circuit formed in a single crystal layer on an insulator. Two silicon substrates are used, one silicon substrate is formed with an insulating film such as a silicon oxide film or a silicon nitride film, and the other P-type silicon substrate is formed with N-type silicon on the surface and then an oxide film is formed. A method of forming a single crystal silicon thin film on an insulating film by forming two layers of silicon substrates by heating and bonding the two silicon substrates through an insulating film There is.

According to this method, a thin N-type silicon layer having a surface covered with a silicon oxide film 3 is formed on a first silicon substrate 2 on which a silicon oxide film 1 is formed as shown in FIG. A second P-type silicon substrate 5 having 4 is prepared.

Next, as shown in FIG. 3- (2), the first silicon substrate 2 and the second silicon substrate 5 are arranged such that the thin N-type silicon layer 4 faces the first silicon substrate 2. After the bonding, the silicon oxide film 3 covering the portion of the second silicon substrate 5 not facing the first silicon substrate 2 is removed by etching, and then the electrode 6 is formed.

Next, as shown in FIG. 3- (3), the second P-type silicon substrate 5 other than the electrode 6 is N-doped by using the apparatus shown in FIG.
When the electrode 6 formed on the type silicon layer 4 is positively etched, the thin N-type silicon layer 4 is formed on the silicon oxide films 1 and 3.

In FIG. 4, 7 is a container, 8 is an electrolytic solution, and 9
Is a platinum electrode, 10 is a heater, 11 is a silicon substrate obtained by bonding the first silicon substrate 2 and the second P-type silicon substrate 5, and 12 is a constant voltage source.

Next, as shown in FIG. 3- (4), the first silicon substrate 2 immediately below the second silicon substrate 5 and the second P-type silicon substrate 5 at the portion of the electrode 6 are removed by dicing.

[Conventional Example B] Further, conventionally, the following method has been known as a method for manufacturing a semiconductor substrate suitable for an integrated circuit formed in a single crystal layer on an insulator. Two silicon substrates are used, one silicon substrate is formed with an insulating film such as a silicon oxide film or a silicon nitride film, and the other P-type silicon substrate is formed with N-type silicon on the surface and then an oxide film is formed. A method of forming a single crystal silicon thin film on an insulating film by forming two layers of silicon substrates by heating and bonding the two silicon substrates through an insulating film There is.

According to this method, a thin N-type silicon layer having a surface covered with a silicon oxide film 3 is formed on a first silicon substrate 2 on which a silicon oxide film 1 is formed as shown in FIG. 8- (1). A second P-type silicon substrate 5 having 4 is prepared.

Next, as shown in FIG. 8- (2), the first silicon substrate 2 and the second silicon substrate 5 are formed into a thin film of N.
After bonding the type silicon layer 4 to the first silicon substrate 2 so as to face each other, the silicon oxide film 3 covering the N type silicon layer 4 and the P type silicon substrate 5 is partially removed by etching, and then the electrode 6 and the electrode 26 are formed.

Next, as shown in FIG. 8- (3), the electrode 6
The second P-type silicon substrate other than the electrodes 6 and 26 by applying a positive potential to the N-type silicon layer 4 connected to the electrode 26 and a negative potential to the P-type silicon substrate connected to the electrode 26. 5 to the N-type silicon layer 4 using the apparatus of FIG.
When the etching is performed up to, the thin N-type silicon layer 4 is formed on the silicon oxide films 1 and 3.

In FIG. 9, 7 is a container, 8 is an electrolytic solution, and 9
Is a platinum electrode, 10 is a heater, 11 is a silicon substrate obtained by bonding the first silicon substrate 2 and the second P-type silicon substrate 5, 32 is a potentiostat, and 33 is a reference electrode.

Next, as shown in FIG. 8- (4), the first silicon substrate 2 immediately below the second silicon substrate and the second P-type silicon substrate 5 at the electrode 6 and the electrode 26 are removed by dicing. To do.

[0014]

However, in the above-mentioned conventional bonding method, since the electrodes are formed on the second P-type silicon substrate and the N-type silicon layer 4, the electrodes are formed by dicing after etching. It has to be removed, and the silicon powder produced during this dicing contaminates the N-type silicon layer 4 and deteriorates the characteristics of the semiconductor integrated device using such a substrate.

Another problem is that the area of the N-type silicon layer is reduced when the electrodes are removed.

[Object of the Invention] An object of the present invention is to eliminate a dicing step and prevent silicon powder contamination caused by the dicing step in a manufacturing method in which a semiconductor substrate having a single crystal semiconductor layer on an insulator is obtained by a bonding method. Another object of the present invention is to realize a semiconductor substrate manufacturing method that can obtain a high-quality semiconductor substrate without contamination and can prevent the reduction of the substrate area due to the dicing process.

[0017]

As a means for solving the above-mentioned problems, the present invention comprises a step of forming a P-type silicon substrate having a thin N-type silicon layer on one main surface, and the step of forming the substrate. A step of adhering the N-type silicon layer side to another substrate via an insulating film; and an N-type semiconductor at least at the peripheral portion of the N-type silicon layer, leaving an opening in the main surface of the P-type silicon substrate. And a step of electrochemically removing the P-type silicon substrate by using the N-type semiconductor as one electrode, and a method of manufacturing the semiconductor substrate is provided. .

As another means, a step of forming a P-type silicon substrate having a thin N-type silicon layer on one main surface, a step of covering the substrate with an insulating film, and the N-type silicon layer of the substrate. The side of the substrate is bonded to another substrate via the insulating film, the step of removing the insulating film at the peripheral portion of the substrate, leaving an opening in the main surface of the P-type silicon substrate,
At least the step of forming an N-type semiconductor in the peripheral portion of the N-type silicon layer, and the step of electrochemically removing the P-type silicon substrate by using the N-type semiconductor as one electrode are removed. And a method for manufacturing a semiconductor substrate.

Furthermore, the N-type semiconductor is a metal,
The metal may be used as the electrode.

Further, a step of forming a P-type silicon substrate having a thin N-type silicon layer on one main surface, and a step of attaching the N-type silicon layer side of the substrate to the other substrate via an insulating film. A step of combining, a step of removing the insulating film on the peripheral portion of the substrate, and a step of forming an N-type silicon layer on the peripheral portion of the N-type silicon layer while leaving an opening on the main surface of the P-type silicon substrate. , P on the lower peripheral edge of the P-type silicon substrate
A semiconductor substrate comprising: a step of forming a P-type silicon layer; and a step of electrochemically removing the P-type silicon substrate by using the N-type silicon layer and the P-type silicon layer as two electrodes. The manufacturing method is used as the means.

Also, the semiconductor substrate manufacturing method is characterized in that the peripheral portion includes a part of the main surface of the N-type silicon layer.

[0022]

According to the means of the present invention, an N-type semiconductor layer, a metal layer, an N-type silicon layer, and a P-type silicon layer, which are electrode regions, are formed on the peripheral portions of the N-type silicon layer and the P-type silicon substrate. By depositing and electrochemically etching the P-type silicon substrate using these layers as electrodes, the P-type silicon substrate is removed by etching from the opening portion of the main surface of the P-type silicon substrate, and is left at the end of etching. The formed electrode also has a shape that does not particularly need to be removed. Therefore, a dicing process for removing the electrode region is not necessary, and it is possible to prevent contamination of the substrate with silicon powder and reduction of the substrate area due to dicing.

Further, the insulating film at the peripheral portion including a part of the main surface of the N-type silicon layer at the bonding interface is removed, and a thin film for an electrode such as an N-type semiconductor layer is also formed at the lower peripheral portion of the N-type silicon layer. Can be deposited to flatten the surface of the N-type silicon layer after the P-type silicon substrate is removed by etching.

[0024]

EXAMPLES Example A As one embodiment of the present invention, a silicon oxide film is formed on the surface of at least one of a P-type silicon substrate having an N-type layer on the surface and the other substrate. The film formed on the surface is not limited to the silicon oxide film, but may be a silicon nitride film or a SiON film as long as it is an insulating film.

Next, the P-type silicon substrate and the other substrate are bonded together.

Further, the silicon substrate having the N-type layer is not limited to the silicon substrate and may be attached to an insulating substrate such as a quartz substrate or ceramic. The silicon substrate having the N-type layer may not have the insulating film.

Next, the bonded insulating film at the interface is etched up to the peripheral edge of the N-type silicon layer to form N-type polycrystalline silicon as an electrode region on the peripheral edge. The film formed on the peripheral portion of the N-type silicon layer is not limited to polycrystalline silicon, but may be a metal having resistance to an etchant for etching amorphous silicon or P-type silicon.

Next, the P-type silicon is selectively etched.

[Embodiment A1] An embodiment of the present invention will be described below in detail with reference to the drawings. 1- (1) to (4)
FIG. 6 is a cross-sectional view for explaining a process of the first embodiment of the method for manufacturing a semiconductor substrate of the present invention. The same components as those in FIG. 3 have the same reference numerals.

First, as shown in FIG. 1- (1), P is implanted into a P-type silicon substrate 5 having a substrate concentration of 1E16 (cm ⁻³ ) at 6E13 (cm ⁻² ) and 30 KeV, and then 110
Annealing is performed at 0 ° C. to form an N-type silicon layer 4 on the surface, and further oxidation is performed to form a silicon oxide film 3 of 5000 Å.

Next, as shown in FIG. 1- (2), the N-type silicon layer 4 of the P-type silicon substrate 5 is attached so that the N-type silicon layer 4 faces the quartz substrate 13 and heat-treated in nitrogen at 500 ° C.
The bonding between the mold silicon substrate 5 and the quartz substrate 13 is strengthened.

Next, as shown in FIG. 1- (3), the silicon oxide film 3 is etched for 15 minutes using buffered hydrofluoric acid in which the ratio of hydrofluoric acid and ammonium fluoride is 1: 8.
Is etched to the peripheral portion of the N-type silicon layer 4, and then P
When 5000 Å of doped polycrystalline silicon 14 is deposited, the region where the silicon oxide film 3 is removed at the peripheral portion of the N-type silicon substrate is filled with the polycrystalline silicon 14. Further, the polycrystalline silicon 14 on the P-type silicon substrate 5 is removed.

Next, as shown in FIG. 1- (4), the P-type silicon substrate 5 is etched using the apparatus of FIG.
A thin film of the N-type silicon layer 4 is formed on the silicon oxide film 3.

In the etching apparatus of FIG. 5, the same components as those in FIG. 4 are designated by the same reference numerals. In FIG. 5, reference numeral 15 is an electrically conductive electrolytic solution used for making contact between the polycrystalline silicon 14 and the electrode 16 without etching the quartz substrate 13, and 17 is an electrically conductive electrolytic solution 15 and P.
This is a seal portion that isolates the etching solution 8 that etches the mold silicon substrate 5.

As an example of the etching solution 8, hydrazine and water are mixed at a ratio of 1: 1 and heated to 90 ° C. to have a thickness of 525 μm.
When the m-type P-type silicon substrate 5 is etched, since the etching rate is 4 μm / min, the etching is performed in 130 minutes. The electrolytic solution 15 for making contact between the polycrystalline silicon 14 and the electrode 16 may be an acid such as sulfuric acid other than hydrazine as long as the electrolytic solution does not etch the polycrystalline silicon 14. Alternatively, the electrode 16 and the polycrystalline silicon 14 may be brought into direct contact with each other without using the electrolytic solution 15.

[Embodiment A2] Another embodiment of the present invention will be described below with reference to the drawings. 2A to 2D are process sectional views showing a method for manufacturing a substrate according to the present invention.

As shown in FIG. 2- (1), as in the first embodiment, after the N-type silicon layer 4 is formed on the P-type silicon substrate 5, the silicon oxide film 3 is formed.

Further, after bonding the silicon substrate 18 and the N-type silicon layer 4 of the P-type silicon substrate 5 so as to face each other, heat treatment is performed in nitrogen at 1000 ° C. to improve the bonding strength.

Next, as shown in FIG. 2- (2), the silicon oxide film 3 is etched to the peripheral edge of the N-type silicon layer 4 using buffered hydrofluoric acid, and the tungsten 19 is removed by 50.
When deposited by 00Å, tungsten 19 is deposited on the P-type silicon substrate 5 and the silicon substrate 18.

Next, as shown in FIG. 2- (3), after the tungsten 19 on the surfaces of the P-type silicon substrate 5 and the silicon substrate 18 is etched by plasma etching, the etching apparatus shown in FIG. When the P-type silicon substrate 5 is etched, a thin film of the N-type silicon layer 4 is formed on the oxide film 3 on the silicon substrate 18.

[Embodiment B] As one embodiment of the present invention, a silicon oxide film is formed on the surface of the other substrate to which a P-type silicon substrate having an N-type layer is attached. The film formed on the surface is not limited to the silicon oxide film, but may be a silicon nitride film or a SiON film as long as it is an insulating film.

An insulating film may be formed on the surface of the P type silicon substrate having the N type layer.

Next, the N-type layer of the P-type silicon substrate and the other substrate are bonded together. Further, the silicon substrate having the N-type layer is not limited to the silicon substrate and may be attached to an insulating substrate such as a quartz substrate or ceramic. The silicon substrate having the N-type layer may not have the insulating film.

Next, the insulating film at the bonded interface is etched up to the peripheral edge of the N-type silicon layer to form N-type polycrystalline silicon and P-type polycrystalline silicon at the peripheral edge. The film formed on the peripheral portion of the N-type silicon layer is not limited to polycrystalline silicon, but may be a metal having resistance to an etchant for etching amorphous silicon or P-type silicon.

Next, the P-type silicon is selectively etched using the N-type polycrystalline silicon and the P-type polycrystalline silicon as electrodes.

[Embodiment B1] An embodiment of the present invention will be described in detail below with reference to the drawings. 6- (1) to (4)
FIG. 6 is a cross-sectional view for explaining a process of the embodiment of the method for manufacturing a semiconductor substrate of the present invention. The same components as those of FIG. 8 are designated by the same reference numerals.

First, as shown in FIG. 6- (1), P is implanted into a P-type silicon substrate 5 having a substrate concentration of 1E16 (cm ⁻³ ) at 6E13 (cm ⁻² ) and 30 KeV, and then 110
Annealing is performed at 0 ° C. to form an N-type silicon layer 4 on the surface, and further oxidation is performed to form a silicon oxide film 3 of 5000 Å.

Next, the N-type silicon layer 4 of the P-type silicon substrate 5 is bonded so as to face the quartz substrate 34, and 5
Heat treatment is performed in nitrogen at 00 ° C. to firmly bond the P-type silicon substrate 5 and the quartz substrate 34.

Next, as shown in FIG. 6- (2), the silicon oxide film 3 is etched for 15 minutes using buffered hydrofluoric acid in which the ratio of hydrofluoric acid and ammonium fluoride is 1: 8.
Is etched to the peripheral edge of the N-type silicon layer 4 and then 5000 Å of polycrystalline silicon 35 is deposited, the region where the silicon oxide film 3 is removed at the peripheral edge of the silicon substrate is filled with the polycrystalline silicon 35.

Next, as shown in FIG. 6- (3), RIE is performed.
The polycrystalline silicon 35 on the P-type silicon substrate 5 is removed by ion implantation, and P ions 36 and B ions 37 are further implanted by ion implantation.
After obliquely injecting, the oxide film 38 is formed to 30 by CVD.
00Å Accumulate. Further, when annealed, P-doped N-type polycrystalline silicon 39, B-doped P-type polycrystalline silicon 20 and P-type diffusion layer 21 are formed.

Next, as shown in FIG. 6- (4), the electrode 22
And 23 are formed, and the P-type silicon substrate 5 is etched using the apparatus of FIG. 9, a thin film of the N-type silicon layer 4 is formed on the silicon oxide film 3.

As an example of the etching solution 8, hydrazine and water are mixed at a ratio of 1: 1 and heated to 90 ° C. to have a thickness of 525 μm.
When the m-type P-type silicon substrate 5 is etched, since the etching rate is 4 μm / min, the etching is performed in 130 minutes.

[Embodiment B2] Another embodiment of the present invention will be described below with reference to the drawings. 7A to 7D are process cross-sectional views showing a method for manufacturing a substrate according to the present invention.

As shown in FIG. 7- (1), as in Example B1, the N-type silicon layer 4 is formed on the P-type silicon substrate 5, and then the silicon oxide film 3 is formed.

Further, a silicon nitride film 25 having a thickness of 1500 Å is formed on the N-type silicon substrate 24 and then partially opened.

Next, as shown in FIG. 7- (2), the N-type silicon layers 4 of the P-type silicon substrate 5 are bonded so as to face each other, and then heat-treated in nitrogen at 1000 ° C. to improve the bonding strength. Let Further, the silicon oxide film 3 is etched to the peripheral edge of the N-type silicon layer 4 using buffered hydrofluoric acid, and then the polycrystalline silicon 35 is deposited at 5000 Å.

Next, as shown in FIG. 7- (3), RIE
Is used to etch the polycrystalline silicon 35 facing the P-type silicon substrate 5, and then B ions 37 are formed by ion implantation.
Is obliquely implanted, and a CVD oxide film 38 is further added to 3000
Å Accumulate.

Next, when annealing is performed, N-type impurities diffuse from the N-type silicon substrate 24 into the polycrystalline silicon 35 to form an N-type polycrystalline silicon layer 39, and the ion-implanted P-type impurities diffuse into the polycrystalline silicon 35. Thus, the P-type polycrystalline silicon layer 20 and the P-type diffusion layer 21 are formed.

Next, after forming the electrodes 22 and 23, as shown in FIG.
When the P-type silicon substrate 5 is etched with the electrode 22 made positive and the electrode 23 made negative with respect to the reference electrode 33 by using the device of No. 3, the N-type is formed on the silicon nitride film 25 and the oxide film 3 on the silicon substrate 24. A thin film of the silicon layer 4 is formed.

[0060]

As described above, according to the present invention,
By forming the electrode region on the peripheral portion of the thin N-type silicon layer, when the P-type silicon is electrochemically etched, unnecessary portions of the electrode region are simultaneously removed by etching, and the electrode left at the end of the etching is also removed. Also, it is a shape that does not particularly need to be removed. Therefore, a dicing process for removing the electrode region is not necessary, and it is possible to prevent contamination of the substrate with silicon powder and reduction of the substrate area due to dicing. Therefore, a high-quality semiconductor substrate can be manufactured without waste, and the effect of improving the characteristics of an integrated circuit using this substrate can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic process sectional view showing an embodiment of the present invention.

FIG. 2 is a schematic process sectional view showing another embodiment of the present invention.

FIG. 3 is a schematic process sectional view showing a conventional method for manufacturing a semiconductor substrate.

FIG. 4 is a schematic configuration diagram of a conventional etching apparatus.

FIG. 5 is a schematic configuration diagram of an etching apparatus of an embodiment.

FIG. 6 is a schematic process sectional view showing an embodiment of the present invention.

FIG. 7 is a schematic process sectional view showing another embodiment of the present invention.

FIG. 8 is a schematic process cross-sectional view showing a conventional method for manufacturing a semiconductor substrate.

FIG. 9 is a schematic configuration diagram of an etching apparatus.

[Explanation of symbols]

 1,3 Silicon oxide film 2 Silicon substrate 4 N-type silicon layer 5 P-type silicon substrate 6 Electrode 7 Container 8 Etching solution 9 Platinum electrode 10 Heater 11 Bonded silicon substrate 12 Constant voltage power supply 13 Quartz substrate 14 Polycrystalline silicon film 15 Electrolyte 16 Electrode 17 Seal part 18 Silicon substrate 19 Tungsten 20 B-doped polycrystalline silicon film 21 P-type diffusion layer 22, 23, 26 Electrode 24 N-type silicon substrate 25 Silicon nitride film 32 Potentiostat 33 Reference electrode 34 Quartz substrate 35 Multi Crystal silicon film 36 P ion 37 B ion 38 CVD oxide film 39 P-doped polycrystalline silicon film

Claims (6)

[Claims] 1. A step of forming a P-type silicon substrate having a thin N-type silicon layer on one main surface, and bonding the N-type silicon layer side of the substrate to another substrate via an insulating film. A step of forming an N-type semiconductor layer on at least a peripheral portion of the N-type silicon layer while leaving an opening in the main surface of the P-type silicon substrate; and using the N-type semiconductor as one electrode, A step of electrochemically removing the type silicon substrate, and a method of manufacturing a semiconductor substrate. 2. A step of forming a P-type silicon substrate having a thin N-type silicon layer on one main surface, a step of covering the substrate with an insulating film, and a step of covering the N-type silicon layer side of the substrate with A step of adhering to another substrate via an insulating film; a step of removing the insulating film at the peripheral portion of the substrate; and an opening portion left on the main surface of the P-type silicon substrate to leave at least the peripheral edge of the N-type silicon layer. A step of forming an N-type semiconductor layer in the portion, and a step of electrochemically removing the P-type silicon substrate by etching using the N-type semiconductor as one electrode. . 3. The method for manufacturing a semiconductor substrate according to claim 1, wherein the N-type semiconductor is a metal, and the metal is used as the electrode. 4. A step of forming a P-type silicon substrate having a thin N-type silicon layer on one main surface, and bonding the N-type silicon layer side of the substrate to another substrate via an insulating film. A step of removing the insulating film on the peripheral portion of the substrate, and a step of forming an N-type silicon layer on the peripheral portion of the N-type silicon layer leaving an opening on the main surface of the P-type silicon substrate, Forming a P-type silicon layer on the lower peripheral portion of the P-type silicon substrate, and electrochemically removing the P-type silicon substrate by using the N-type silicon layer and the P-type silicon layer as two electrodes And a method for manufacturing a semiconductor substrate. 5. The method of manufacturing a semiconductor substrate according to claim 1, wherein the peripheral portion includes a part of a main surface of the N-type silicon layer. 6. The method of manufacturing a semiconductor substrate according to claim 1, wherein the bonding step includes heat treatment.