Method for producing semiconductor substrate

Abstract

There is provided a method for suppressing the occurrence of defects such as voids or blisters even in the laminated wafer having no oxide film wherein hydrogen ions are implanted into a wafer for active layer having no oxide film on its surface to form a hydrogen ion implanted layer, and ions other than hydrogen are implanted up to a position that a depth from the surface side the hydrogen ion implantation is shallower than the hydrogen ion implanted layer, and the wafer for active layer is laminated onto a wafer for support substrate, and then the wafer for active layer is exfoliated at the hydrogen ion implanted layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart showing procedures of producing a semiconductor substrate by the conventional lamination process;

FIG. 2 is a flow chart showing procedures of producing a semiconductor substrate according to the invention;

FIG. 3 is a flow chart showing procedures of producing a semiconductor substrate according to the invention;

FIG. 4 is a flow chart showing procedures of producing a semiconductor substrate according to the invention;

FIG. 5 is a graph showing a relation between atomic mass of each element and a ratio of oxygen atom recoiled in the element implantation to the each element ion;

FIG. 6 is a graph showing adequate implantation doses of argon ions and oxygen ions; and

FIG. 7 is a flow chart showing procedures of producing a semiconductor substrate according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention lies in that when a semiconductor substrate is produced by directly silicon wafers to each other without using an oxide film, ions other than hydrogen ions implanted for exfoliating the wafer for the active layer is implanted in a dose enough to suppress hydrogen ion diffusion in thermal exfoliation, and concrete methods therefor are explained individually.

In the method according to the first invention shown in FIG. 2, a wafer 1 for an active layer and a wafer 2 for a support substrate are previously provided (step (a)). Firstly, hydrogen ions are implanted into the wafer 1 for the active layer without forming an oxide film to form an ion implanted layer 3 in the interior of the wafer 1 for the active layer (step (b)).

Thereafter, ions other than hydrogen such as oxygen ions or argon ions are implanted up to a position that a depth from the surface side the hydrogen ion implantation is shallower than the hydrogen ion implanted layer 3 (step (c)). By the implantation of the oxygen ions or argon ions are implanted a dose of ions sufficient to suppress the occurrence of void or blister defects in the active layer.

Then, the wafer 1 for the active layer is laminated at the ion implanted side to the wafer 2 for the support substrate (step (d)), and an exfoliation heat treatment is applied to partly exfoliate the wafer 1 for the active layer at the ion implanted layer 3 as a cleavage plane (exfoliation face) (step (e)), and thereafter the re-oxidation treatment (step (f)), removal of oxide film 4 (step (g)) and planarization treatment (step (h)) are carried out to produce a semiconductor substrate 6 in which a silicon layer 5 is formed on the wafer 2 for the support substrate.

As the planarization treatment is suitable a treatment in Ar or H₂ atmosphere at a high temperature above 1100° C.

In the above method, the ions other than hydrogen are particularly implanted at the step (c), so that the diffusion of hydrogen into the laminated interface at the exfoliation heat treatment of the step (e) is suppressed by such implanted ions to suppress the occurrence of voids or blisters, and hence the semiconductor substrate is obtained by directly laminating silicon wafers to each other without using the oxide film.

The condition for implanting the ions other than hydrogen required for the suppression of void or blister defects in the active layer is explained in detail below.

That is, the dose of the ions other than hydrogen is derived from a relational equation to the thickness of the oxide film in the implantation as follows. Moreover, the upper limit can be determined experimentally, and is 1×10¹⁶ atoms/cm² for argon ions and 2×10¹⁶ atoms/cm² for oxygen ions, respectively.

In the method according to the second invention shown in FIG. 3, a wafer 1 for an active layer and a wafer 2 for a support substrate are previously provided (step (a)). Firstly, ions other than hydrogen such as oxygen ions or argon ions are implanted into the wafer 1 for the active layer up to a position shallower than an exfoliation region of the wafer 1 for the active layer without forming an oxide film (step (b)). Thereafter, hydrogen ions are implanted into the exfoliation region to form a hydrogen ion implanted layer 3 (step (c)).

Then, the wafer 1 for the active layer is laminated at the ion implanted side to the wafer 2 for the support substrate (step (d)), and an exfoliation heat treatment is applied to partly exfoliate the wafer 1 for the active layer at the ion implanted layer 3 as a cleavage plane (exfoliation face) (step (e)), and thereafter the re-oxidation treatment (step (f)), removal of oxide film 4 (step (g)) and planarization treatment (step (h)) are carried out to produce a semiconductor substrate 6 in which a silicon layer 5 is formed on the wafer 2 for the support substrate.

In the above method, the ions other than hydrogen are particularly implanted at the step (b), so that the diffusion of hydrogen into the laminated interface at the exfoliation heat treatment of the step (e) is suppressed by such implanted ions to suppress the occurrence of voids or blisters, and hence the semiconductor substrate is obtained by directly laminating silicon wafers to each other without using the oxide film.

Even in the method of FIG. 3, it is preferable to conduct the implantation of argon ions or oxygen ions in the same manner as in the method of FIG. 2.

In the method according to the third invention shown in FIG. 4, a wafer 1 for an active layer and a wafer 2 for a support substrate are previously provided (step (a)). Firstly, an oxide film 7 is formed on the wafer 1 for the active layer (step (b)), and hydrogen ions are implanted into the wafer 1 for the active layer to form an ion implanted layer 3 in the interior of the wafer 1 for the active layer (step (c)).

Thereafter, ions other than hydrogen such as oxygen ions or argon ions are implanted up to a position that a depth from the surface side the hydrogen ion implantation is shallower than the hydrogen ion implanted layer 3 (step (d)). By the implantation of the oxygen ions or argon ions are implanted a dose of ions and oxygen sufficient to suppress the occurrence of void or blister defects in the active layer by such ions themselves and oxygen sputtered by such ions.

Then, the oxide film 7 is completely removed by using a chemical polishing treatment with an etching solution composed mainly of, for example, hydrofluoric acid (hereinafter referred to as HF treatment) (step (e)), and the wafer 1 for the active layer is laminated at the ion implanted side to the wafer 2 for the support substrate (step (f)), and an exfoliation heat treatment is applied to partly exfoliate the wafer 1 for the active layer at the ion implanted layer 3 as a cleavage plane (exfoliation face) (step (g)), and thereafter the re-oxidation treatment (step (h)), removal of oxide film 4 (step (i)) and planarization treatment (step (j)) are carried out to produce a semiconductor substrate 6 in which a silicon layer 5 is formed on the wafer 2 for the support substrate.

In the above method, the ions other than hydrogen are particularly implanted at the step (d) in addition to the hydrogen ion implantation of the preceding step, so that the diffusion of hydrogen into the laminated interface at the exfoliation heat treatment of the step (e) is suppressed by such implanted ions and oxygen sufficiently sputtered at these steps to suppress the occurrence of voids or blisters, and hence the semiconductor substrate is obtained by directly laminating silicon wafers to each other without using the oxide film.

Here, there is explained the condition for sputtering oxygen from the oxide film through the implantation of oxygen ions or argon ions in addition to the implantation of hydrogen ions to implant oxygen required for the suppression of void or blister defects in the active layer is explained in detail below.

Now, in order that ND defined in the equation (I) satisfies N_D>4.2×10¹⁴ atoms/cm² by implanting ions other than hydrogen, it is required to make up a shortfall of N_HO (oxygen introduced into the active layer by hydrogen ion implantation) with N_IO (oxygen introduced into the active layer by an element other than hydrogen) and N_ID (defect introduced into the active layer by implanting ions other than hydrogen).

There are B, P and As as an element generally implanted into the wafer. In Table 1 is shown a dose of oxygen introduced by a recoil phenomenon in the implantation of such an element ion, i.e. a recoil phenomenon that when the element ion is implanted through the oxide film, oxygen atom is sputtered from the oxide film by the implanted ion to strike into Si crystal. In FIG. 5 are shown results arranged as a relation between atomic mass of each element and a ratio of oxygen atom recoiled in the implantation of the element to the element ion (recoil ratio). From the results of FIG. 5, a recoil ratio R_Z of a certain element can be represented by the following equation (III):

R_Z=0.0007×q_z^1.325   (III)

where q_z is an atomic mass.

TABLE 1
Thickness of oxide film: 1 nm, Ion dose: 1.00 × 1013 atoms/cm2
		Recoiled oxygen	Oxygen
	Atomic	atom/implanted	concentration at
Element	mass	element ion	interface of Si/SiO2: B
B	11	0.0150	1.50 × 1018
P	31	0.0680	6.80 × 1018
As	75	0.1900	1.90 × 1018

Each recoil ratio of hydrogen, oxygen and argon is determined according to the equation (III) as follows:

Hydrogen:R_H=0.0007 (q_H=1)

Oxygen:R_O=0.0277 (q_O=16)

Argon:R_Ar=0.0934 (q_Ar=40)

When argon ions are implanted after the hydrogen ion implantation at hydrogen dose: 6×10¹⁶ atoms/cm² and implantation energy: 50 keV, a relation between implantation dose of argon ions and thickness of oxide film is determined in order that N_D defined in the equation (I) satisfies N_D>4.2×10¹⁴ atoms/cm².

At first, the equation (I) in the implantation of argon ions is represented as follows:

N_D=N_HO+N_ArO+N_ArD   (I)

When N_HO, N_ArO and N_ArD are

N_HO=D_H(hydrogen dose)×t_box(thickness of oxide film)×k_HO(coefficient)   (II)

(where D_H=6×10¹⁶ atoms/cm² and k_HO=4.76×102 8/cm)),

N_ArO=D_Ar(argon dose)×t_box(thickness of oxide film)×k_ArO(coefficient)

(where k_ArO=R_Ar/R_H×k_HO=0.0934/0.000×4.67×10²=6.23×10⁴) and N_ArD=D_Ar, the above equation (I) is

N_D=N_HO+N_ArO+N_ArD=D_H×t_box×k_HO+D_Ar×t_box×k_ArO+D_Ar=4.2×10¹⁴ atoms/cm²,

from which the implantation dose of argon ions is D_Ar=(4.2×10¹⁴−6.0×10¹⁶×t_box×4.67×10²)/(t_box×6.23×10⁴+1).

Similarly, when oxygen ions are implanted after the hydrogen ion implantation at hydrogen dose: 6×10¹⁶ atoms/cm² and implantation energy: 50 keV, a relation between implantation dose of oxygen ions and thickness of oxide film is determined in order that N_D defined in the equation (I) satisfies N_D>4.2×10¹⁴ atoms/cm².

At first, the equation (I) in the implantation of oxygen ions is represented as follows:

N_D=N_HO+N_OO+N_OD   (I)

When N_HO, N_OO and N_OD are

N_HO=D_H(hydrogen dose)×t_box (thickness of oxide film)×k_HO(coefficient)   (II)

(where D_H=6×10¹⁶ atoms/cm² and k_HO=4.76×10² (/cm)), N_OO=D_O (oxygen dose)×t_box (thickness of oxide film)×k_OO (coefficient)(where k_OO=R_O/R_H×k_HO=0.0277/0.0007×4.67×10²=1.85×10⁴) and N_OD=D_O, the above equation (I) is

N_D=N_HO+N_OO+N_OD=D_H×t_box×k_HO+D_O×t_box×kOO+D_O=4.2×10¹⁴ atoms/cm², form which the implantation dose of oxygen ions is D_O=(4.2×10¹⁴−6.0×10¹⁶ ×t_box×4.67×10²)/(t_box×1.85×10⁴+1).

In FIG. 6 are shown results obtained by arranging the above adequate implantation doses of argon ions and oxygen ions by the thickness of the oxide film. Moreover, the upper limit on the implantation doses of argon ions and oxygen ions in FIG. 6 is set due to the fact that though defects are introduced into the active layer by implanting the argon ions and oxygen ions, if the implantation dose is too large, the crystallinity of the active layer is broken and the good active layer is not obtained. The upper limit is experimentally 1×10¹⁶ atoms/cm² in case of the argon ions and 2×10¹⁶ atoms/cm² in case of the oxygen ions, respectively.

In the method according to the fourth invention shown in FIG. 7, a wafer 1 for an active layer and a wafer 2 for a support substrate are previously provided (step (a)). Firstly, an oxide film 7 is formed on the wafer 1 for the active layer (step (b)), and ions other than hydrogen such as oxygen ions or argon ions are implanted into the wafer 1 for the active layer up to a position shallower than an exfoliation region of the wafer 1 for the active layer (step (c)). Thereafter, hydrogen ions are implanted into the exfoliation region to form a hydrogen ion implanted layer 3 (step (d)).

Then, the oxide film 7 is completely removed by using, for example, HF treatment (step (e)), and the wafer 1 for the active layer is laminated at the ion implanted side to the wafer 2 for the support substrate (step (f)), and an exfoliation heat treatment is applied to partly exfoliate the wafer 1 for the active layer at the ion implanted layer 3 as a cleavage plane (exfoliation face) (step (g)), and thereafter the re-oxidation treatment (step (h)), removal of oxide film 4 (step (i)) and planarization treatment (step j)) are carried out to produce a semiconductor substrate 6 in which a silicon layer 5 is formed on the wafer 2 for the support substrate.

In the above method, the ions other than hydrogen are particularly implanted at the step (c) in addition to the hydrogen ion implantation of the subsequent step, so that the diffusion of hydrogen into the laminated interface at the exfoliation heat treatment of the step (e) is suppressed by such implanted ions and oxygen sufficiently sputtered at these steps to suppress the occurrence of voids or blisters, and hence the semiconductor substrate is obtained by directly laminating silicon wafers to each other without using the oxide film.

Even in the method shown in FIG. 7, it is preferable to conduct the implantation of argon ions or oxygen ions within the preferable range shown in FIG. 6.

In any methods shown in FIGS. 2, 3, 4 and 7, it is preferable to conduct the plasma treatment for increasing the adhesion strength at the laminated interface prior to the lamination between the wafer for the active layer and the wafer for the support substrate. Since the plasma treatment has effects of activating the laminated surface and removing organic substance adhered to the surface, the adhesion strength of the laminated interface is improved to bring about the decrease of voids or blisters. Moreover, the conditions of the plasma treatment are not particularly limited, but the similar effects can be typically developed by treating the wafers in a gas of oxygen, nitrogen, hydrogen or the like for several tens seconds.

COMPARATIVE EXAMPLE 1

A laminated semiconductor substrate is prepared by forming an oxide film of 150 nm in thickness on the surface of the wafer for the active layer and implanting hydrogen ions so as to come a peak of the implantation dose (ion implanted layer) to a depth position of 500 nm from the surface of the wafer for the active layer, and then laminating the wafer for the active layer at its ion implanted side to the wafer for the support substrate and conducting the exfoliation heat treatment to exfoliate the wafer for the active layer at the hydrogen ion implanted peak region (ion implanted layer), and thereafter conducting an oxidation treatment and removing the oxide film and conducting the planarization treatment.

COMPARATIVE EXAMPLE 2

A laminated semiconductor substrate is prepared by implanting hydrogen ions so as to come a peak of the implantation dose (ion implanted layer) to a depth position of 500 nm from the surface of the wafer for the active layer without forming an oxide film on the surface of the wafer for the active layer as shown in FIG. 1, and laminating the wafer for the active layer at its ion implanted side to the wafer for the support substrate and conducting the exfoliation heat treatment to exfoliate the wafer for the active layer at the hydrogen ion implanted peak region (ion implanted layer), and thereafter conducting an oxidation treatment and removing the oxide film and conducting the planarization treatment.

COMPARATIVE EXAMPLE 1

A laminated semiconductor substrate is prepared by implanting hydrogen ions so as to come a peak of the implantation dose (ion implanted layer) to a depth position of 500 nm from the surface of the wafer for the active layer without forming an oxide film on the surface of the wafer for the active layer as shown in FIG. 1, and then subjecting the surfaces of the wafer for the active layer and the wafer for the support substrate to an oxygen plasma treatment and laminating the wafer for the active layer at its ion implanted side to the wafer for the support substrate and conducting the exfoliation heat treatment to exfoliate the wafer for the active layer at the hydrogen ion implanted peak region (ion implanted layer), and thereafter conducting an oxidation treatment and removing the oxide film and conducting the planarization treatment.

INVENTION EXAMPLE 1

According to the method shown in FIG. 2, a laminated semiconductor substrate is prepared by implanting hydrogen ions so as to come a peak of the implantation dose (ion implanted layer) to a depth position of 500 nm from the surface of the wafer for the active layer without forming an oxide film on the surface of the wafer for the active layer, and further implanting oxygen ions so as to come a peak of the implantation dose to a depth position of 50 nm from the surface of the wafer for the active layer, and laminating the wafer for the active layer at its ion implanted side to the wafer for the support substrate after the implantation of both the ions, and conducting the exfoliation heat treatment to exfoliate the wafer for the active layer at the hydrogen ion implanted peak region (ion implanted layer), and thereafter conducting an oxidation treatment and removing the oxide film and conducting the planarization treatment.

INVENTION EXAMPLE 2

According to the method shown in FIG. 3, a laminated semiconductor substrate is prepared by implanting oxygen ions so as to come a peak of the implantation dose to a depth position of 50 nm from the surface of the wafer for the active layer without forming an oxide film on the surface of the wafer for the active layer, and further implanting hydrogen ions so as to come a peak of the implantation dose (ion implanted layer) to a depth position of 500 nm from the surface of the wafer for the active layer, and laminating the wafer for the active layer at its ion implanted side to the wafer for the support substrate after the implantation of both the ions, and conducting the exfoliation heat treatment to exfoliate the wafer for the active layer at the hydrogen ion implanted peak region (ion implanted layer), and thereafter conducting an oxidation treatment and removing the oxide film and conducting the planarization treatment.

INVENTION EXAMPLE 3

According to the method shown in FIG. 2, a laminated semiconductor substrate is prepared by implanting hydrogen ions so as to come a peak of the implantation dose (ion implanted layer) to a depth position of 500 nm from the surface of the wafer for the active layer without forming an oxide film on the surface of the wafer for the active layer, and further implanting argon ions so as to come a peak of the implantation dose to a depth position of 50 nm from the surface of the wafer for the active layer, and laminating the wafer for the active layer at its ion implanted side to the wafer for the support substrate after the implantation of both the ions, and conducting the exfoliation heat treatment to exfoliate the wafer for the active layer at the hydrogen ion implanted peak region (ion implanted layer), and thereafter conducting an oxidation treatment and removing the oxide film and conducting the planarization treatment.

INVENTION EXAMPLE 4

According to the method shown in FIG. 3, a laminated semiconductor substrate is prepared by implanting argon ions so as to come a peak of the implantation dose to a depth position of 50 nm from the surface of the wafer for the active layer without forming an oxide film on the surface of the wafer for the active layer, and further implanting hydrogen ions so as to come a peak of the implantation dose (ion implanted layer) to a depth position of 500 nm from the surface of the wafer for the active layer, and laminating the wafer for the active layer at its ion implanted side to the wafer for the support substrate after the implantation of both the ions, and conducting the exfoliation heat treatment to exfoliate the wafer for the active layer at the hydrogen ion implanted peak region (ion implanted layer), and thereafter conducting an oxidation treatment and removing the oxide film and conducting the planarization treatment.

INVENTION EXAMPLE 5

According to the method shown in FIG. 4, a laminated semiconductor substrate is prepared by forming an oxide film of 20 nm on the wafer for the active layer, implanting hydrogen ions so as to come a peak of the implantation dose (ion implanted layer) to a depth position of 500 nm from the surface of the wafer for the active layer, and further implanting oxygen ions so as to come a peak of the implantation dose to a depth position of 50 nm from the surface of the wafer for the active layer, and then completely removing the oxide film through HF treatment, and laminating the wafer for the active layer at its ion implanted side to the wafer for the support substrate, and conducting the exfoliation heat treatment to exfoliate the wafer for the active layer at the hydrogen ion implanted peak region (ion implanted layer), and thereafter conducting an oxidation treatment and removing the oxide film and conducting the planarization treatment.

INVENTION EXAMPLE 6

According to the method shown in FIG. 4, a laminated semiconductor substrate is prepared by forming an oxide film of 20 nm on the wafer for the active layer, implanting oxygen ions so as to come a peak of the implantation dose to a depth position of 50 nm from the surface of the wafer for the active layer, and further implanting hydrogen ions so as to come a peak of the implantation dose (ion implanted layer) to a depth position of 500 nm from the surface of the wafer for the active layer, and laminating the wafer for the active layer at its ion implanted side to the wafer for the support substrate after the implantation of both the ions, and conducting the exfoliation heat treatment to exfoliate the wafer for the active layer at the hydrogen ion implanted peak region (ion implanted layer), and thereafter conducting an oxidation treatment and removing the oxide film and conducting the planarization treatment.

INVENTION EXAMPLE 7

According to the method shown in FIG. 4, a laminated semiconductor substrate is prepared by forming an oxide film of 20 nm on the wafer for the active layer, implanting hydrogen ions so as to come a peak of the implantation dose (ion implanted layer) to a depth position of 500 nm from the surface of the wafer for the active layer, and further implanting argon ions so as to come a peak of the implantation dose to a depth position of 50 nm from the surface of the wafer for the active layer, and then completely removing the oxide film through HF treatment, and laminating the wafer for the active layer at its ion implanted side to the wafer for the support substrate, and conducting the exfoliation heat treatment to exfoliate the wafer for the active layer at the hydrogen ion implanted peak region (ion implanted layer), and thereafter conducting an oxidation treatment and removing the oxide film and conducting the planarization treatment.

INVENTION EXAMPLE 8

According to the method shown in FIG. 7, a laminated semiconductor substrate is prepared by forming an oxide film of 20 nm on the wafer for the active layer, implanting argon ions so as to come a peak of the implantation dose to a depth position of 50 nm from the surface of the wafer for the active layer, and further implanting hydrogen ions so as to come a peak of the implantation dose (ion implanted layer) to a depth position of 500 nm from the surface of the wafer for the active layer, and laminating the wafer for the active layer at its ion implanted side to the wafer for the support substrate after the implantation of both the ions, and conducting the exfoliation heat treatment to exfoliate the wafer for the active layer at the hydrogen ion implanted peak region (ion implanted layer), and thereafter conducting an oxidation treatment and removing the oxide film and conducting the planarization treatment.

INVENTION EXAMPLE 9-16

In these examples, the same procedures as in Invention Examples 1-8 are repeated, respectively, except that the surfaces of the wafer for the active loayer and the wafer for the support substrate are subjected to an oxygen plasma treatment prior to the lamination between the wafer for the active layer and the wafer for the support substrate. Moreover, the plasma treatment is carried out under condition that the wafers are kept for 20 seconds after the interior of the reaction chamber replaced with oxygen gas is rendered into a vacuum state.

In the above examples, the ion implantation conditions are as follows.

• Hydrogen dose: 6.0×10¹⁶ atoms/cm² and implantation energy: 50 keV
• Oxygen dose: 1.0×10¹⁶ atoms/cm² and implantation energy: 50 keV
• Argon dose: 1.0×10¹⁶ atoms/cm² and implantation energy: 80 keV

With respect to the thus obtained semiconductor substrates, the quantity of defects generated is visually measured as a count of defect number under a high-intensity light-gathering lamp or a fluorescent lamp. The results are shown in Table 2. As seen from Table 2, the occurrence of defects is suppressed in the semiconductor substrates according to the invention even when the oxide film is not existent.

	TABLE 2
	Thickness of				Defect number
	oxide film	Ion	Ion	Plasma	(defects/300 mm
	(nm)	implantation 1	implantation 2	treatment	wafer)
Comparative	150	H	—	—	not more than 2
Example 1
Comparative	—	H	—	—	50
Example 2
Comparative	—	H	—	◯	30
Example 3
Invention	—	H	O	—	not more than 20
Example 1
Invention	—	O	H	—	not more than 10
Example 2
Invention	—	H	Ar	—	not more than 15
Example 3
Invention	—	Ar	H	—	not more than 5
Example 4
Invention	20	H	O	—	not more than 10
Example 5
Invention	20	O	H	—	not more than 2
Example 6
Invention	20	H	Ar	—	not more than 10
Example 7
Invention	20	Ar	H	—	not more than 2
Example 8
Invention	—	H	O	◯	not more than 10
Example 9
Invention	—	O	H	◯	not more than 5
Example 10
Invention	—	H	Ar	◯	not more than 10
Example 11
Invention	—	Ar	H	◯	not more than 2
Example 12
Invention	20	H	O	◯	not more than 5
Example 13
Invention	20	O	H	◯	not more than 1
Example 14
Invention	20	H	Ar	◯	not more than 5
Example 15
Invention	20	Ar	H	◯	not more than 1
Example 16

As shown in Table 2, when hydrogen ions are first implanted, the organic substance existing on the surface of the wafer is easily adhered onto the wafer and the blisters are easily generated. Therefore, it is preferable to first implant ions other than hydrogen, and it is more preferable to clean the wafer after the implantation of ions other than hydrogen and then implant hydrogen ions.

Claims

1. A method for producing a semiconductor substrate, which comprises the steps of implanting hydrogen ions into a wafer for an active layer having no oxide film on its surface to form a hydrogen ion implanted layer, implanting ions other than hydrogen up to a position that a depth from the surface side the hydrogen ion implantation is shallower than the hydrogen ion implanted layer, laminating the wafer for the active layer at the ion implanted side to a wafer for a support substrate, and then exfoliating the wafer for the active layer at the hydrogen ion implanted layer.

2. A method for producing a semiconductor substrate, which comprises the steps of implanting ions other than hydrogen into a wafer for an active layer having no oxide film on its surface up to a position shallower than an exfoliation region of the wafer for the active layer, implanting hydrogen ions into the exfoliation region to form a hydrogen ion implanted layer, laminating the wafer for the active layer at the ion implanted side to a wafer for a support substrate, and then exfoliating the wafer for the active layer at the hydrogen ion implanted layer.

3. A method for producing a semiconductor substrate, which comprises the steps of forming an oxide film on a wafer for an active layer, implanting hydrogen ions into the wafer for the active layer to form a hydrogen ion implanted layer, implanting ions other than hydrogen up to a position that a depth from the surface side the hydrogen ion implantation is shallower than the hydrogen ion implanted layer, removing the oxide film from the wafer for the active layer, laminating the wafer for the active layer at the ion implanted side to a wafer for a support substrate, and then exfoliating the wafer for the active layer at the hydrogen ion implanted layer.

4. A method for producing a semiconductor substrate, which comprises the steps of forming an oxide film on a wafer for an active layer, implanting ions other than hydrogen into a wafer for an active layer having no oxide film on its surface up to a position shallower than an exfoliation region of the wafer for the active layer, implanting hydrogen ions into the exfoliation region to form a hydrogen ion implanted layer, removing the oxide film from the wafer for the active layer, laminating the wafer for the active layer at the ion implanted side to a wafer for a support substrate, and then exfoliating the wafer for the active layer at the hydrogen ion implanted layer.

5. A method for producing a semiconductor substrate according to any one of items (1)-(4), wherein a plasma treatment is carried out prior to the lamination of the wafer for the active layer and the wafer for the support substrate.