JPH1145862A - Manufacture of semiconductor substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable separation, while ion implantation in forming an ion implantation layer for separation is carried out with a low dose. SOLUTION: On a surface portion of a bonding wafer 15 made of a single- crystal silicon substrate, grooves 16 are formed which extend longitudinally and laterally to partition the wafer into regions, each corresponding to one chip, and which have a depth greater than an ion implantation layer 17 and are not open at peripheral edge portions of the bonding wafer 15. Hydrogen gas is ionized and implanted with respect to the bonding wafer 15, thus forming the ion implantation layer 17 for separation at a predetermined depth. Then, the bonding wafer 15 is bonded to a base substrate 12, having an insulating film 13 formed thereon in advance. At this point, sealed hollow portions 18 are formed by the grooves 16. After that, a separation step of separating the bonding wafer 15 on the ion implantation layer 17 is carried out by heat treatment. At this point, air within the hollow portions 18 expands thermally to promote the separation.

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 in which a single crystal semiconductor layer for element formation is provided on a base substrate in an insulated state from the base substrate.

[0002]

As this type of semiconductor substrate, for example, an SOI (Silicon On Insul) formed by providing a silicon single crystal layer on a silicon substrate via an insulating film.
ator) There is a substrate. As a method for manufacturing the SOI substrate, for example, a manufacturing method using bonding has been proposed as disclosed in Japanese Patent Application Laid-Open No. 5-211128.

In this method, as shown in FIG. 5, an SOI substrate is manufactured through three stages (processes). That is, in the first stage, as shown in FIG. 5A, for example, a process of ionizing hydrogen gas and accelerating it with a predetermined implantation energy into the bonded substrate 1 made of a silicon single crystal substrate is performed. Thus, the ion implantation layer 2 is formed at a predetermined depth position of the bonded substrate 1. In this case, the layer above the ion-implanted layer 2 in the bonded substrate 1 becomes the silicon single-crystal thin film layer 1a finally desired to be obtained.

In the next second stage, as shown in FIG. 5 (b), the bonded substrate 1 is turned upside down on the upper surface of a base substrate 3 made of, for example, a silicon single crystal substrate, as shown in FIG. 5 (a). The laminating step is performed in the state of being bonded. At this time, an insulating film 4 made of an oxide film is formed on the surface of the base substrate 3 in advance. Then, in the third step, as shown in FIG. 5C, a step of separating the silicon single crystal thin film layer 1a from the bonded substrate 1 along the ion implantation layer 2 by a heat treatment at 400 to 600 ° C., for example. Done.

As a result, the silicon single crystal thin film layer 1a is bonded to the base substrate 3 with the insulating film 4 interposed therebetween, and then the peeled surface is polished as shown in FIG. The high quality silicon single crystal thin film layer 1a
Is obtained. Note that the bonded substrate 1 can be reused while reducing its thickness.

By the way, in order to surely separate (crack) the ion-implanted layer 2 in the above-mentioned separating step, the dose of hydrogen ions must be set to 1 in the ion-implanting step.
It was necessary to be about × 10 ¹⁶ atoms / cm 2.
Therefore, in the above-described conventional method, a relatively long time is required for the ion implantation process.

The present invention has been made in view of the above circumstances, and an object of the present invention is to bond a bonded substrate having an ion-implanted layer formed thereon to a base substrate and then cut off the bonded substrate at the ion-implanted layer. In view of the above, an object of the present invention is to provide a method of manufacturing a semiconductor substrate, which enables peeling while performing ion implantation at a low dose, and thereby can reduce the time required for the step of forming an ion-implanted layer.

[0008]

The method of manufacturing a semiconductor substrate according to the present invention is a method for manufacturing a semiconductor substrate having a single crystal semiconductor layer for forming an element provided on a base substrate via an insulating film. Then, ion implantation is performed at a predetermined depth of the surface portion of the bonded substrate made of a single crystal semiconductor, thereby peeling off in a state where a single crystal thin film layer to be a single crystal semiconductor layer is secured in a surface layer portion of the bonded substrate. Ion-implanted layer forming step of forming an ion-implanted layer for bonding, and laminating a laminated substrate having a single-crystal thin film layer formed on the base substrate via an insulating film on the surface of the single-crystal thin film layer And a peeling step of separating the bonded substrate bonded on the base substrate by an ion implantation layer by heat treatment, and bonding the base substrate and the bonded substrate in a bonded state of the base substrate and the bonded substrate. Matching Between the plate, it has a feature where the hollow portion of the sealed state is formed partially removed form the single-crystal thin film layer and the ion implantation layer (invention of claim 1).

According to this, in the step of forming an ion-implanted layer, a single-crystal thin-film layer having a form partitioned by the ion-implanted layer is formed on the surface layer of the bonded substrate. A laminated substrate is bonded on the surface of the single crystal thin film layer. In this lamination state, between the base substrate and the lamination substrate, the sealed hollow portion is a form in which the single crystal thin film layer and the ion implantation layer are partially removed, that is, from the ion implantation layer of the lamination substrate. The base is also formed in a state where a part of the bulk portion on the base side is exposed. Then, from this state, a peeling step of separating the bonded substrate by the ion implantation layer by heat treatment is performed, and on the base substrate,
A semiconductor substrate having a single crystal semiconductor layer for element formation is obtained via the insulating film.

[0010] At this time, since the hermetically sealed hollow portion is formed between the base substrate and the bonded substrate, the gas in the hollow portion thermally expands by the heat treatment in the peeling step,
The pressure expands the hollow portion, in other words, acts as a force in the direction of peeling the base side of the bonded substrate from the base substrate with respect to the ion-implanted layer from the base substrate. For this reason, a force that promotes separation can be obtained from the inside, so that separation can be easily performed in the ion implantation layer even if the defect state (ion implantation amount) in the ion implantation layer is not sufficient. Become like This means that separation can be easily performed even if the dose of implanted ions in the ion implantation layer is reduced.

Therefore, according to the method of manufacturing a semiconductor substrate according to the first aspect of the present invention, the bonded substrate having the ion-implanted layer formed thereon is bonded to the base substrate and then separated at the ion-implanted layer. The present invention has an excellent practical effect that it enables separation while keeping the ion implantation at a low dose, and thus can reduce the time required for the step of forming an ion-implanted layer. .

In this case, as a method of forming a closed hollow portion, a groove portion which is deeper than the depth of the ion-implanted layer and is not opened at the peripheral edge of the bonded substrate is formed on the surface portion of the bonded substrate. Attachment to the base substrate may be performed at a portion other than the groove. At this time, the formation of the groove is
It may be performed before the ion implantation layer forming step (the invention of claim 2) or after the ion implantation layer forming step (the invention of claim 3). Thus, the hollow portion can be easily formed.

Further, at this time, the groove can be formed in such a form that a single crystal semiconductor layer for element formation provided on the base substrate is divided into one element unit, one well unit, one circuit unit or one chip. The invention of claim 4). According to this, it is possible to obtain a semiconductor substrate in which a single crystal semiconductor layer for element formation on the base substrate is separated in advance for each element, each well, each circuit, or each chip.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to an SOI (Si / Si) having a silicon single crystal layer provided on a silicon substrate via an insulating film.
A first embodiment (corresponding to claims 1, 2 and 4) applied to the manufacture of a (icon on insulator) substrate will be described with reference to FIGS.

First, as shown in FIG. 1E, a semiconductor substrate (SOI substrate) 11 obtained by the manufacturing method according to this embodiment is placed on a base substrate 12 made of, for example, a single crystal silicon substrate (silicon wafer). And a single crystal semiconductor layer 14 for element formation made of silicon single crystal via an insulating film 13 made of a silicon oxide film. In this case, the single-crystal semiconductor layer 14 is not provided on the entire surface of the base substrate 12, but is ultimately one chip (or one chip).
It is provided in such a form that it is separated at intervals for each region (element unit, well unit, circuit unit).

Now, a method of manufacturing the semiconductor substrate 11 will be described in the following order. FIG. 3 schematically illustrates a process of manufacturing the semiconductor substrate 11 according to the present embodiment. That is, first, in the process P1, the bonded substrate 15 (see FIGS. 1 and 2)
) Is performed. The bonded substrate 15 is made of a high-quality single-crystal silicon substrate (silicon wafer) and has a thickness of, for example, 600 in an initial state.
It is about μm. In this step P1, FIG.
As shown in (1), a groove 16 is formed on the surface of the bonded substrate 15 by a known process such as formation of a resist pattern by photolithography and dry etching.

As shown exaggeratedly in FIG. 2, this groove 16 (shown with diagonal lines in FIG. 2 for convenience) is bonded to the finally obtained single crystal semiconductor layer 14. The surface of the mating substrate 15 is divided into one chip (or one element unit,
(A well unit, a circuit unit) and are formed so as to extend in the vertical and horizontal directions so as to be divided into regions corresponding to regions. At this time, the groove 16 is formed to have a depth dimension (for example, about 3 μm) deeper than the ion implantation layer 17 described later.
6 is formed so as not to be opened at the peripheral edge of the bonded substrate 15.

In the next step P2, an ion implantation layer forming step for the bonded substrate 15 is performed. This process P
2, as shown in FIG. 1 (b), for example, hydrogen gas is ionized and injected at a predetermined injection energy into the surface portion of the bonded substrate 15. At a predetermined depth position (for example, at a position of 1 μm from the surface) of the bonded substrate 15, an ion implantation layer 17 for separation, which is a region having a high concentration of implanted hydrogen ions, is formed.

At this time, the ion-implanted layer 17 is formed at a position shallower than the depth of the groove 16 and
The thin single-crystal thin-film layer 15 a made of silicon single crystal (which will later become the single-crystal semiconductor layer 14) is formed in a surface layer portion excluding the groove portion 16 in a form partitioned by the ion-implanted layer 17. become. In the groove 16, the ion-implanted layer exists at a predetermined depth from the bottom of the groove 16.

As will be described later, the dose of hydrogen ions at this time is about 1 × 10 ¹⁵ atoms / cm 2. Although not shown, this ion implantation layer forming step is performed in a state where an oxide film for preventing contamination during ion implantation is formed on the surface of the bonded substrate 15 as much as possible. The oxide film is removed by chemical etching or the like using an aqueous solution.

In step P3, a bonding step of bonding the bonding substrate 15 to the base substrate 12 is performed. In this step P3, as shown in FIG. 1C, an insulating film (oxide film) 13 is previously formed on the surface of the base substrate 12 by thermal oxidation or a deposition method such as PVD or CVD. The bonded substrate 15 is bonded to the base substrate 12 in a state where it is turned upside down from FIG. 1B, that is, on the surface of the single crystal thin film layer 15a.

As is well known, at the time of bonding, the surfaces of the base substrate 12 and the bonded substrate 15 are sequentially washed with a mixed solution of, for example, sulfuric acid and hydrogen peroxide 4: 1 and pure water. After performing, the amount of adsorbed water is controlled by spin drying to bring the bonding surfaces into close contact. As a result, the base substrate 12 and the bonded substrate 15 are bonded by a silanol group formed on the bonded surface and a hydrogen bond of a water molecule adsorbed on the surface.

As shown in FIG. 1C, the single crystal thin film layer 15 is formed on the base substrate 12 with the insulating film 13 interposed therebetween.
a, the ion implantation layer 17 and the base portion (bulk portion) of the bonded substrate 15 are integrated in a laminated form. Since the bonded substrate 15 has the groove 16, the single crystal thin film layer 1 is provided between the groove 16 and the surface of the base substrate 12.
The hollow portion 18 is formed in a form in which 5a and the ion implantation layer 17 are partially removed. At this time, the groove 1
Since 6 is closed at the end of the bonded substrate 15, the formed hollow portion 18 is in a closed state.

In the next step P4, a peeling step of separating the bonded substrate 15 bonded to the base substrate 12 by the ion implantation layer 17 is performed. In this step P4, as shown in FIG. 1D, the bonded substrate 15 is heat-treated in a nitrogen atmosphere or an oxygen atmosphere, for example, at 400 to 600 ° C.
This is performed based on the fact that defects are concentrated in the ion implantation layer 17 inside and cracks occur in the ion implantation layer 17.

By this heat treatment, a dehydration-condensation reaction occurs on the bonding surface between the base substrate 12 and the bonding substrate 15, so that the bonding is more firmly performed. And with this,
The gas (air) in the hollow portion 18 formed in a sealed state between the base substrate 12 and the bonded substrate 15 thermally expands, and the pressure expands the hollow portion 18, in other words, the bonded substrate 15. 1C, the bottom of the groove 16 is pressed upward in FIG. 1C, and the base of the bonded substrate 15 is peeled from the base substrate 12 with respect to the ion-implanted layer 17 to act as a force. .

As a result, a force that promotes peeling can be obtained from the inside, so that even if the ion implantation amount in the ion implantation layer 16 is not sufficient, the ion implantation layer
7 can be easily performed. As a result, the single crystal thin film layer 15a provided on the ion implantation layer 17 of the bonded substrate 15 is peeled off, so that the single crystal thin film layer 15a is transferred to the front side of the base substrate 12, so that the insulating film is formed on the base substrate 12. The semiconductor substrate 11 having the single-crystal semiconductor layer 14 (single-crystal thin-film layer 15a) is obtained through the intermediary of the semiconductor substrate 11.

Subsequently, in step P5, the obtained semiconductor substrate 11 is subjected to a high-temperature annealing treatment at a temperature of, for example, 1000 ° C. to 1200 ° C. As a result, the bonding of the peeled surfaces is strengthened, and defect recovery and the like are achieved. Further, in step P6, as shown in FIG. 1E, surface polishing is performed on the surface (peeled surface) of the bonded substrate 15 from which the obtained semiconductor substrate 11 and single crystal thin film layer 15a have been peeled. . Thus, fine irregularities on the peeled surface are removed.

In the state shown in FIG. 1E, the single-crystal semiconductor layer 14 is separated into regions corresponding to one chip, and a concave state is formed between them (a state in which the insulating film 13 is exposed).
However, if necessary, the concave portion may be embedded with an insulating film (oxide film) or the like by using, for example, a CVD method. Further, the bonded substrate 15 on the side from which the single crystal thin film layer 15a has been peeled off is repeatedly used for manufacturing the next semiconductor substrate 11 while reducing its thickness.

As described above, according to the present embodiment, the hollow portion 18 is formed by forming the groove 16 in the bonded substrate 15 and then bonding the base substrate 12 to the groove, so that the hollow portion 18 is formed during the heat treatment in the peeling step. The thermal expansion of the air in section 18
It was used as a force to promote peeling. Therefore,
Even if the ion implantation amount in the ion implantation layer 17 is not sufficient, the separation in the ion implantation layer 17 can be easily performed.

As a result, according to the present embodiment, the ion implantation can be performed at a lower dose than that of the conventional ion implantation, but the separation can be performed, and the time required for forming the ion implantation layer 17 can be greatly reduced. An excellent practical effect that it can be achieved. Incidentally, in this embodiment, the dose amount of hydrogen ions is set to 1 × 10 ¹⁶ atoms / cm 2
Thus, the time required for ion implantation can be reduced to less than half that of the conventional case, by an order of magnitude of about 1 × 10 ¹⁵ atoms / cm 2.

FIG. 4 shows a second embodiment of the present invention.
). This embodiment differs from the first embodiment in that the order of execution of the groove forming step and the ion implantation layer forming step on the bonded substrate 15 is reversed. That is, as shown in FIG. 4A, first, an ion implantation layer forming step is performed on the bonded substrate 15, and an ion-implanted layer 17 for separation is formed at a predetermined depth position of the bonded substrate 15.

Next, as shown in FIG. 4B, a groove forming step is performed, and a groove is formed on the surface of the bonded substrate 15 at a depth deeper than the ion-implanted layer 17 and at the end of the bonded substrate 15. The closed groove 16 is formed. After that, similarly to the first embodiment, bonding to the base substrate 12 (FIG. 4C), peeling (FIG. 4D), and surface polishing (FIG. 4).
Steps such as (e)) are performed, and the semiconductor substrate 11 is obtained.

According to such an embodiment, similarly to the first embodiment, the hermetically sealed hollow portion 18 is formed by providing the groove 16 in the bonding substrate 15 and bonding the groove to the base substrate 12. Since it is formed, the thermal expansion of the air in the hollow portion 18 can be used as a force that promotes separation.
As a result, separation can be performed while ion implantation is performed at a low dose, and the time required for forming the ion-implanted layer 17 can be significantly reduced. Further, in the present embodiment, no ion-implanted layer remains below the bottom of the groove 16 in the peeled bonded substrate 15 (FIG. 4D).
In addition, when the peeled bonded substrate 15 is reused after polishing the surface, there is an advantage that the thickness of the layer to be removed from the surface portion can be reduced.

In addition, the present invention is not limited to the above-described embodiments. For example, the material of the base substrate may be a ceramic substrate or a quartz substrate. Also,
As a gas used for ion implantation, besides hydrogen gas,
Various gases such as a rare gas such as helium and neon, fluorine gas, and chlorine gas can be employed. In this case, an appropriate dose amount, peeling temperature, and the like differ depending on the type of ions used. Furthermore, the dose amount, the thickness of each part, and the like are merely examples, and the present invention can be implemented with appropriate changes without departing from the scope of the invention.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention, and is a schematic longitudinal sectional view showing states in a manufacturing process in order.

FIG. 2 is a plan view schematically showing a state of a groove formed in a bonded substrate.

FIG. 3 is a diagram schematically showing a manufacturing process of a semiconductor substrate.

FIG. 4 is a view corresponding to FIG. 1, showing a second embodiment of the present invention;

FIG. 5 is a diagram corresponding to FIG. 1 showing a conventional example.

[Explanation of symbols]

In the drawings, 11 is a semiconductor substrate, 12 is a base substrate, 13 is an insulating film, 14 is a single crystal semiconductor layer, 15 is a bonded substrate, 1
5a is a single crystal thin film layer, 16 is a groove, 17 is an ion implanted layer, and 18 is a hollow part.

Claims (4)

[Claims] An insulating film (1) is formed on a base substrate (12).
3) A method for producing a semiconductor substrate (11) provided with a single crystal semiconductor layer (14) for element formation via 3), wherein a surface portion of a bonded substrate (15) made of a single crystal semiconductor is By performing ion implantation to a predetermined depth, an ion-implanted layer for peeling is obtained in a state where a single-crystal thin-film layer (15a) to be a single-crystal semiconductor layer (14) is secured in a surface layer portion of the bonded substrate (15). Ion implantation layer forming step (P) for forming (17)
2) and the single-crystal thin film layer (1) with respect to the base substrate (12).
A laminating step (P3) of laminating the laminated substrate (15) on which the 5a) is formed on the surface of the single crystal thin film layer (15a) via an insulating film (13), and on the base substrate (12). A peeling step (P4) of separating the bonded substrate (15) bonded to the above at the ion implantation layer (17) by heat treatment, and bonding the base substrate (12) and the bonded substrate (15). In the bonding state, a hermetically sealed hollow portion (18) partially connects the single crystal thin film layer (15a) and the ion implantation layer (17) between the base substrate (12) and the bonding substrate (15). A method for manufacturing a semiconductor substrate, wherein the semiconductor substrate is formed in a removed form. 2. Prior to the step of forming an ion-implanted layer (P2), a groove (16) serving as the hollow portion (18) is formed on the surface of the bonded substrate (15) in accordance with the depth of the ion-implantation. 2. The method of manufacturing a semiconductor substrate according to claim 1, wherein a groove forming step (P1) of forming a groove deep and not to be opened at a peripheral edge of the bonded substrate (15) is performed. 3. After the step (P2) of forming an ion-implanted layer, a groove (16) serving as the hollow portion (18) is formed deeper than the depth of the ion-implanted in the surface of the bonded substrate (15). 2. The method of manufacturing a semiconductor substrate according to claim 1, wherein a step of forming a groove is formed so that the peripheral edge of the bonded substrate is not opened. 4. The groove portion (16) is formed by forming a single crystal semiconductor layer (14) for element formation provided on the base substrate (12) in units of one element, unit of well, unit of circuit, or unit of one chip. 4. The method for manufacturing a semiconductor substrate according to claim 2, wherein the semiconductor substrate is formed in a form of partitioning the substrate.