JP2000183352A - Substrate having silicon layer and its manufacture, and semiconductor device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent alkali metal ions from diffusing to the vicinity of the interface of a silicon layer and to form a semiconductor element of high performance in the silicon layer. SOLUTION: In a substrate, having a silicon layer 14 formed by crystal- growing silicone in low-melting point metal melting solution containing silicon on the surface of a glass substrate 12, alkali metal ions are gettered on the back side of the glass substrate 12. A gettering layer 15 formed of phosphosilicate glass, borophosphosilicate glass or borosilicate glass is formed. The gettering layer is formed on the silicon layer 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate having a silicon layer and a method of manufacturing the same, and a semiconductor device and a method of manufacturing the same. More specifically, the present invention relates to a method of forming a silicon layer and a gettering layer for gettering alkali metal ions. The present invention relates to a substrate provided, a manufacturing method thereof, a semiconductor device formed using the substrate, and a manufacturing method thereof.

[0002]

2. Description of the Related Art A MOSFET (Metal-oxide-semiconductor fiel) is formed using a single crystal silicon layer formed on a substrate.
TFT (Thin Film Transistor)
) Has electron mobility several times larger than that using a polysilicon layer and is suitable for high-speed operation. For example, "First MOS transistors on Insulator by
Silicon Satulated Liquid Solution Epitaxy. "IEEE E
LECTRON DEVICE LETTERS, 13 [5] (May 1992) RPZing
g et al., p.294-296, Japanese Patent Publication No. 4-57098, and applied physics "thin film transistor", 65 [8] (1996), Masamura Matsumura, p.842-848.

The following film forming techniques (1) to (4) are known as techniques for forming a single crystal silicon layer on which a semiconductor element is formed on a substrate.

(1) Using a single crystal silicon substrate as a seed, a silicon epitaxy layer is formed by cooling from an indium silicon solution or an indium gallium silicon solution heated to 920 ° C. to 930 ° C.
The technology of forming a silicon semiconductor layer on this layer is called "VER
Y-LOW-TEMPERATURE LIQUID-PHASE EPITAXIAL GROWTH OF
SILICON. "MATERIALS LETTERS, 9 [2,3] (Jan. 1990) S
oo Hong Lee, p53-56, "MOS transistors with epitaxi
al Si, laterally grown over SiO ₂ by liquid phase ep
itxy. "J. Applied Physics A, 54 [1] (1992) R. Bergman
n et al., p.103-105, "First MOS transistors on Ins
ulator by Silicon Satulated Liquid Solution Epitax
y. "IEEE ELECTRON DEVICE LETTERS, 13 [5] (May 1992)
It is disclosed in literatures such as RPZingg et al., P.

(2) A technique for epitaxially growing silicon on a sapphire substrate is disclosed in "High-quality CMOS in
thin (100nm) silicon on saphire. "IEEE ELECTRON DEV
ICELETTERS, 9 (Jan. 1988) GAGarcia, REReedy, and
MLBurger, pp. 32-34.

(3) A technique for forming a silicon layer on an insulating substrate by an oxygen ion implantation method is disclosed in "CMOS device fabric".
cation on buried SiO ₂ layers formed by oxygen impl
antation into silicon. "Electron.Lett., 14 [18] (Au
g. 1978) K. Izumi, M. Doken ,, and H. Ariyoshtl, p. 593-59
It is disclosed in 4.

A step is formed on a quartz substrate, a polysilicon layer is formed thereon, and this is heated to 1400 ° C. or higher by a laser beam or a strip heater. The technology for forming an epitaxially grown layer using the steps formed on a quartz substrate as the nucleus of the heated polysilicon layer is known as “Grafoepitaxy,” IEICE, 66 [5]
(May 1983) Furukawa Seijiro, p.486-489, "Crystallograph
ic orientatin of silicon on an amorphous substrate
using an artificial surface-relief grating and las
er crystallization. "Appl. Phys. Letter, 35 [1] (J
uly. 1979) Geis, MW, et al., p. 71-74, "Silicon gra
phoepitaxy "Jpn.J.Appl.Phys., Suppl.20-1 (1981) Gei
s, MW, et al., pp. 39-42.

[0008]

However, according to the prior art, it is difficult to form a single-crystal silicon layer on a large glass substrate having a relatively low strain point by a crystal growth technique such as epitaxial growth. It was difficult. In addition, it is difficult to grow a silicon crystal uniformly at a low temperature by a technique of forming a step on a glass substrate and using this as a seed for crystal growth to grow a silicon single crystal (graphoepitaxy technique). . Even if a silicon crystal can be grown using a glass substrate, sodium ions contained in the glass substrate adversely affect the semiconductor element. For example, in a MOS transistor, when sodium ions are accumulated at the interface between the gate insulating film and the silicon substrate, the threshold voltage fluctuates and the transistor performance deteriorates.

Specifically, for example, in the case of an nMOS transistor, when a potential of +3 V to +5 V is applied to the gate electrode, the nMOS transistor is turned on and a current flows. The temperature of the nMOS transistor increases in proportion to the current. Gate signal application and high temperature (100 ° C to 300 ° C)
C), sodium ions are accumulated at the interface between the gate insulating film and the silicon substrate. Thereby, the threshold voltage Vth of the nMOS transistor changes. For example, Vth
However, in an nMOS transistor having a voltage of 0.5 V to 2.0 V (normal value), the voltage changes by about 0.1 V to 2 V to the negative (-) side due to sodium ion contamination.

[0010]

SUMMARY OF THE INVENTION The present invention is directed to a substrate having a silicon layer, a method of manufacturing the same, and a semiconductor device and a method of manufacturing the same.

The first substrate having a silicon layer is a substrate having a silicon layer formed by crystal-growing silicon in a low-melting metal melt containing silicon on the surface side of a glass substrate on which a crystal growth seed is formed. And a gettering layer is formed on the back side of the glass substrate.

Here, the seed for crystal growth includes both a seed for crystal growth (normal epitaxial growth) inheriting the crystal orientation of the base and a seed for crystal growth (eg, graphoepitaxy) according to the shape of the base. Hereinafter, the seeds for crystal growth are the same as those described above.

Further, the silicon layer is formed of a single crystal, and its electron mobility is, for example, about 540 cm ² / Vs, so that the same electron mobility as that of a bulk silicon substrate can be obtained. Hereinafter, the silicon layer is similar to the above. Note that a single crystal in this specification includes a single crystal including a subgrain boundary and a dislocation.

In the first substrate, since the gettering layer is formed on the back side of the glass substrate, even if the glass substrate contains an alkali metal ion such as sodium ion, the alkali metal ion is not removed. Since it is taken into the gettering layer, diffusion to the vicinity of the interface of the silicon layer is prevented.

The second substrate having a silicon layer is a substrate having a silicon layer obtained by crystal-growing silicon in a low-melting-point metal melt containing silicon on the surface side of a glass substrate on which a crystal growth seed is formed. , A gettering layer is formed on the surface side of the silicon layer.

In the second substrate, since the gettering layer is formed on the surface of the silicon layer, alkali metal ions such as sodium ions which are to diffuse from the surface of the silicon layer are taken into the gettering layer. Therefore, diffusion to the vicinity of the interface of the silicon layer is prevented.

A method for manufacturing a first substrate having a silicon layer includes a step of forming a seed for crystal growth on the surface side of a glass substrate, and a step of forming silicon in the silicon-containing low melting point metal melt from the seed for crystal growth. Forming a silicon layer on the front surface side of the glass substrate by crystal growth, wherein a gettering layer is formed on the back surface side of the glass substrate.

In the first substrate manufacturing method, since the gettering layer is formed on the back surface of the glass substrate, even if the glass substrate contains an alkali metal ion such as sodium ion, the alkali metal ion Is taken into the gettering layer, so that diffusion to the vicinity of the interface of the silicon layer is prevented.

A method for manufacturing a second substrate having a silicon layer includes a step of forming a seed for crystal growth on the surface side of a glass substrate, and a step of forming silicon in the silicon-containing low-melting metal melt from the seed for crystal growth. Forming a silicon layer on the surface side of the glass substrate by crystal growth, a method of manufacturing a substrate having a silicon layer, the method comprising: removing metal deposited on the surface side of the silicon layer; Forming a gettering layer.

In the second method for manufacturing a substrate, since the gettering layer is formed on the surface of the silicon layer, alkali metal ions such as sodium ions which are to diffuse from the surface side of the silicon layer are taken into the gettering layer. Therefore, diffusion to the vicinity of the interface of the silicon layer is prevented.

The first semiconductor device is a semiconductor device in which a semiconductor element is formed on a silicon layer formed by crystal growth of silicon in a low melting metal melt on the surface side of a glass substrate on which a seed for crystal growth is formed. , A gettering layer is formed on the back side of the glass substrate.

In the first semiconductor device, since the gettering layer is formed on the back side of the glass substrate, even if the glass substrate contains an alkali metal ion such as sodium ion, the alkali metal ion Is trapped in the gettering layer, so that diffusion to the vicinity of the interface of the silicon layer is prevented. Therefore, the semiconductor element formed on the silicon layer is not affected by alkali metal ions contained in the glass substrate.

The second semiconductor device is a semiconductor device in which a semiconductor element is formed on a silicon layer formed by crystal growth of silicon in a low melting metal melt on the surface side of a glass substrate on which a crystal growth seed is formed. , A gettering layer is formed on the surface side of the silicon layer.

In the second semiconductor device, since the gettering layer is formed on the surface side of the silicon layer, alkali metal ions such as sodium ions which are to be diffused from the surface side of the silicon layer are deposited on the gettering layer. Since they are taken in, they are prevented from diffusing near the interface of the silicon layer. Therefore, the semiconductor element formed on the silicon layer is not affected by an alkali metal ion from the outside.

A first method for manufacturing a semiconductor device includes a step of forming a seed for crystal growth on the surface side of a glass substrate, and a step of growing silicon in a silicon-containing low-melting-point metal melt from the seed for crystal growth. Forming a silicon layer on the surface side of the glass substrate, removing metal deposited on the silicon layer, and performing a predetermined process on the silicon layer to form a semiconductor element. In the manufacturing method, a gettering layer is formed on the back side of the glass substrate.

In the first method of manufacturing a semiconductor device, since the gettering layer is formed on the back surface of the glass substrate,
Even if an alkali metal ion such as a sodium ion is contained in the glass substrate, the alkali metal ion is taken into the gettering layer, so that diffusion to the vicinity of the interface of the silicon layer is prevented. Therefore, the semiconductor element formed on the silicon layer is not affected by the alkali metal ions.

In a second method of manufacturing a semiconductor device, a step of forming a seed for crystal growth on the surface side of a glass substrate and a step of growing silicon in a silicon-containing low melting point metal melt from the seed for crystal growth as a starting point. Forming a silicon layer on the surface side of the glass substrate, removing metal deposited on the silicon layer, and performing a predetermined process on the silicon layer to form a semiconductor element. The manufacturing method includes a step of removing a metal deposited on the silicon layer, a step of forming a gettering layer on the silicon layer, and a step of performing a predetermined process on the silicon layer to form a semiconductor element. .

In the second method of manufacturing a semiconductor device, since the gettering layer is formed on the surface side of the silicon layer, alkali metal ions such as sodium ions that are to diffuse from the surface side of the silicon layer are not gettered. Since it is taken into the layer, diffusion to the vicinity of the interface of the silicon layer is prevented. Therefore, the semiconductor element formed on the silicon layer is not affected by the alkali metal ions.

Further, the first substrate or the second substrate
Since the silicon layer is formed on the glass substrate using the substrate manufacturing method described above, a silicon layer having the above-described characteristics can be obtained on the glass substrate. Then, since a predetermined process is performed on the silicon layer to form a semiconductor element, the semiconductor element has the same high-performance characteristics as those formed on a bulk silicon substrate. For example, an insulated gate field effect transistor in which a channel region, a source region, and a drain region are formed in a silicon layer is a high-speed transistor with a high current density. As described above, the silicon layer includes a high-speed, large-current-density top-gate TFT, bottom-gate TFT, dual-gate TFT, electroluminescence element, transistor for field-emission display element, diode, capacitance, resistance, photovoltaic cell ( It is possible to form semiconductor elements such as a solar cell, a light emitting element, and a light receiving element.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a substrate having a silicon layer according to the present invention, a method of manufacturing the same, a semiconductor device using the substrate and a method of manufacturing the same will be described below.

First, an embodiment of the first substrate having a silicon layer according to the present invention will be described with reference to the schematic sectional view of FIG.

As shown in FIG. 1, the first substrate 11 has a step formed on the surface side of a glass substrate 12 as a seed 13 for crystal growth.
Silicon layer 1 formed by crystal-growing silicon in a low-melting metal melt containing silicon (not shown) starting from
4 are formed. That is, the silicon layer 14
Is obtained by growing silicon in a low-melting-point metal melt containing silicon by grapho-epitaxial growth using seeds (steps) 13 for crystal growth, and is made of single-crystal silicon.
Hereinafter, the single crystal in the present specification includes a subcrystal and a single crystal containing dislocations. Thus, the silicon layer 14 formed by crystal growth on the surface side of the glass substrate 12 is formed.

On the other hand, a metal (mainly an alkali metal ion such as sodium ion) is provided on the back side of the glass substrate 12.
As a gettering layer 15, a phosphor silicate glass (hereinafter, referred to as PSG) layer is formed. This gettering layer 15 is made of boron phosphorus silicate glass (hereinafter referred to as B
PSG) layer or boron silicate glass (hereinafter BSG) layer.

The first substrate 11 includes a glass substrate 12
Since the gettering layer 15 is formed on the back side of the substrate, even if the glass substrate 12 contains an alkali metal ion such as a sodium ion, the alkali metal ion is taken into the gettering layer 15. for that reason,
Alkali metal ions such as sodium ions are prevented from diffusing near the interface with the silicon layer 14. Therefore, the glass substrate 12 can be used as the first substrate 11.

Since the silicon layer 14 is formed of a single crystal, its electron mobility is, for example, 540 cm ² /
Vs, which is equivalent to that of a bulk silicon substrate.

Next, an embodiment of the second substrate having a silicon layer according to the present invention will be described with reference to the schematic sectional view of FIG. 2, the same components as those described with reference to FIG. 1 are denoted by the same reference numerals.

As shown in FIG. 2, the second substrate 17 has a step formed on the surface side of the glass substrate 12 as a seed 13 for crystal growth.
Low melting metal melt containing silicon starting from (not shown)
A silicon layer 14 formed by crystal growth of silicon inside is formed. That is, the silicon layer 14 is formed by growing silicon in a low-melting-point metal melt containing silicon by grapho-epitaxial growth using seeds (steps) 13 for crystal growth, and is made of single crystal silicon. Thus, the silicon layer 14 formed by crystal growth on the surface side of the glass substrate 12 is formed. Further, a gettering layer 18 is formed on the silicon layer 14. The gettering layer 18 is for gettering a metal (mainly an alkali metal ion such as sodium ion), for example, PS
G is formed. Alternatively, it may be BPSG or BSG.

In the second substrate 17, the silicon layer 14
Since the gettering layer 18 is formed on the surface of the silicon layer 14, alkali metal ions such as sodium ions that are to diffuse from the surface of the silicon layer 14 are taken into the gettering layer 18. Therefore, diffusion of alkali metal ions such as sodium ions near the interface of the silicon layer 14 is prevented. Therefore, the glass substrate 12 can be used as the second substrate 17.

Since the silicon layer 14 is formed of a single crystal, its electron mobility is, for example, 540 cm.
² / Vs, which is the same electron mobility as that of a bulk silicon substrate.

Next, an embodiment of the third substrate having a silicon layer according to the present invention will be described with reference to the schematic sectional view of FIG. In FIG. 3, the same components as those described with reference to FIGS. 1 and 2 are denoted by the same reference numerals.

The third substrate 19 has a configuration in which the above-described first substrate 11 and the above-described second substrate 17 are combined. That is, the third substrate 19 has a step formed on the surface side of the glass substrate 12 as a seed 13 for crystal growth, and a low-melting-point metal melt (containing silicon) starting from the seed 13 for crystal growth. (Not shown)
A silicon layer 14 formed by crystal growth of silicon inside is formed. That is, the silicon layer 14 is formed by growing silicon in a low-melting-point metal melt containing silicon by grapho-epitaxial growth using the seeds 13 (steps) for crystal growth, and is made of single-crystal silicon. Thus, the silicon layer 14 formed by crystal growth on the surface side of the glass substrate 12 is formed.

Further, a gettering layer 18 is formed on the silicon layer 14. This gettering layer 18
It is for gettering a metal (mainly an alkali metal ion such as a sodium ion), and is formed of, for example, PSG. Alternatively, it may be BPSG or BSG.

On the other hand, a gettering layer 15 is formed on the back side of the glass substrate 12. This gettering layer 1
5 is for gettering a metal (mainly an alkali metal ion such as a sodium ion), and is formed of, for example, PSG. Alternatively, it may be BPSG or BSG.

In the third substrate 19, the glass substrate 12
Since the gettering layer 15 is formed on the back side of the substrate, even if the glass substrate 12 contains an alkali metal ion such as a sodium ion, the alkali metal ion is taken into the gettering layer 15. Further, since the gettering layer 18 is formed on the surface side of the silicon layer 14, alkali metal ions such as sodium ions that are to diffuse from the surface side of the silicon layer 14 are taken into the gettering layer 18. Therefore, diffusion of alkali metal ions such as sodium ions near the interface of the silicon layer 14 is prevented. Therefore, the glass substrate 12 can be used as the third substrate 19.

Since the silicon layer 14 is formed of a single crystal, its electron mobility is, for example, 540 cm ² /
Vs, which is equivalent to that of a bulk silicon substrate.

The first, second, and third substrates 11, 17,
In step 19, a step was used as the seed 13 for crystal growth. However, as a layer (not shown) on the glass substrate 12 for obtaining lattice matching with silicon, for example, a sapphire layer, a spinel layer, or a calcium fluoride layer was used. It can be formed and used as a seed 13 for crystal growth. In this case, the silicon layer 14 is formed by growing silicon in a low-melting-point metal melt (not shown) containing silicon from a layer capable of obtaining lattice matching with silicon as a starting point. (Normal epitaxial growth for growth).

The low-melting-point metal of the low-melting-point metal-containing liquid containing silicon described in each of the above embodiments includes one or more of indium, gallium, tin, bismuth, lead, zinc, antimony and aluminum. Seeds can be used, preferably tin, lead or an alloy of tin and lead.

Next, an embodiment of the first method for manufacturing a substrate having a silicon layer according to the present invention will be described with reference to the manufacturing process diagram of FIG. 4, the same components as those described with reference to FIGS. 1 to 3 are denoted by the same reference numerals.

As shown in FIG. 4A, a method for manufacturing a first substrate having a silicon layer includes the steps of:
A substrate on which a gettering layer 15 for gettering a metal, particularly an alkali metal ion such as a sodium ion on the back surface side is prepared. This gettering layer 1
5 is formed of, for example, a PSG film. Or B
It is also possible to form with a PSG film or a BSG film. As a method for forming the gettering layer 15, a low-temperature film forming technique is used. For example, the process temperature (substrate temperature) is 500 ° C.
~ 650 ° C. under reduced pressure CVD or substrate temperature of 4
A plasma CVD method, sputtering, or the like set at a temperature of 00 ° C. or lower is used.

Then, after forming a resist film by a normal resist coating technique and forming an etching mask (not shown) with the resist film by a lithography technique, it becomes a seed 13 for crystal growth on the surface side of the glass substrate 12 by etching. A step is formed. After that, the resist film used as the etching mask is removed.

Next, as shown in FIG. 4B, silicon in the silicon-containing low-melting-point metal melt (not shown) is crystal-grown from the seed 13 for crystal growth as a starting point. A silicon layer 14 is formed. Thus, the first substrate 11 having the silicon layer 14 is formed.

The gettering layer 15 is formed after the seed 13 for crystal growth is formed or after the silicon layer 14 is formed.
May be formed after forming.

As a method of the crystal growth, there is the following method, which will be described in detail later.

Crystal growth method: After forming a silicon thin film made of amorphous silicon or polycrystalline silicon on the surface side of a glass substrate on which a seed for crystal growth is formed, at least the silicon thin film is brought into contact with a low melting point metal melt. Then, the mixture is heated and held, and the silicon thin film is dissolved in the low-melting-point metal melt to produce a silicon-containing low-melting-point metal melt. Then, by performing a cooling process, starting from the seed for crystal growth,
Crystals of silicon in the silicon-containing low melting metal melt are grown on the surface side of the glass substrate to form a silicon layer.

Crystal growth method: A glass substrate having a crystal growth seed formed on the surface side of a glass substrate is prepared, and at least the surface side of the glass substrate is brought into contact with a silicon-containing low-melting-point metal melt, followed by cooling. Then, the silicon in the silicon-containing low-melting-point metal melt is crystal-grown on the surface side of the glass substrate starting from the seed for crystal growth to form a silicon layer.

Crystal growth method: A silicon thin film made of amorphous silicon or polycrystalline silicon and a low melting point metal layer are formed on the surface side of a glass substrate on which a seed for crystal growth has been formed, and then the low melting point metal is removed by heat treatment. Dissolve and dissolve the silicon thin film in the melt to produce a silicon-containing low melting metal melt. And perform a cooling process,
Starting from a seed for crystal growth, silicon in the silicon-containing low-melting-point metal melt is crystal-grown on the surface side of the glass substrate to form a silicon layer.

Crystal growth method: After forming a silicon-containing low melting point metal layer on the surface side of a glass substrate on which a seed for crystal growth has been formed, a silicon-containing low melting point metal melt is generated by heat treatment. Then, by performing a cooling process, the silicon in the silicon-containing low-melting-point metal melt is crystal-grown on the surface side of the glass substrate starting from the seed for crystal growth to form a silicon layer.

In the first substrate manufacturing method, since the gettering layer 15 for gettering alkali metal ions such as sodium ions is formed on the back surface of the glass substrate 12, Even if an alkali metal ion such as a sodium ion is contained, the alkali metal ion is taken into the gettering layer 15. Therefore, diffusion of alkali metal ions such as sodium ions near the interface with the silicon layer 14 formed on the glass substrate 12 is prevented. Therefore, the substrate having the silicon layer 14 on which the semiconductor element is formed is
2 can be formed.

Further, a low melting point glass substrate can be used as the glass substrate 12. The low melting point glass substrate has, for example, an aluminosilicate glass having a maximum operating temperature of 665 ° C. (because the temperature is almost the same as the strain point, hereinafter referred to as a strain point) (for example, glass code number 17 of Corning)
23), borosilicate glass having a strain point of 510 ° C. (for example, glass code number 7740 of Corning) and the like.

An embodiment of the second method for manufacturing a substrate having a silicon layer according to the present invention will be described with reference to a manufacturing process diagram of FIG. 5, the same components as those described with reference to FIGS. 1 to 3 are denoted by the same reference numerals.

As shown in FIG. 5A, a method of manufacturing a second substrate having a silicon layer is to form a resist film on the surface side of a glass substrate 12 by a normal resist coating, and then use a lithography technique. An etching mask (not shown) is formed using a resist film. Then, a seed 1 for crystal growth is formed on the surface side of the glass substrate 12 by etching.
A level difference of 3 is formed. After that, the resist film used as the etching mask is removed.

Next, as shown in FIG. 5B, silicon in the silicon-containing low-melting-point metal melt (not shown) is crystal-grown from the seed 13 for crystal growth as a starting point, and is formed on the surface side of the glass substrate 12. A silicon layer 14 is formed.

Further, as shown in FIG. 5C, after the metal (not shown) deposited on the surface side of the silicon layer 14 is removed, the surface of the silicon layer 14 is exposed to a metal such as sodium ion. A gettering layer 18 for gettering alkali metal ions is formed. This gettering layer 18 is formed of a PSG film. Or BP
It is also possible to form with an SG film or a BSG film. As a method for forming the gettering layer 18, a low-temperature film forming technique is used. For example, if the process temperature (substrate temperature) is 500 ° C.
The low pressure CVD method of about 650 ° C. or the substrate temperature of 40
A plasma CVD method, sputtering, or the like set at 0 ° C. or lower is used. Thus, the second layer having the silicon layer
Is formed.

The gettering layer 15 may be formed after the seed 13 for crystal growth is formed, after the silicon layer 14 is formed, or after the gettering layer 18 is formed.

As a method of crystal growth of the silicon single crystal, any one of the above-described methods of crystal growth or the like is used.

In the second method of manufacturing the substrate, since the gettering layer 18 is formed on the surface of the silicon layer 14, alkali metal ions such as sodium ions which are to diffuse from the surface of the silicon layer 14 are not gettered. Since it is taken into the layer 18, diffusion of alkali metal ions such as sodium ions near the interface of the silicon layer 14 is prevented. Therefore, the silicon layer 1 on which the semiconductor element is formed
4 can be formed using the glass substrate 12.

Next, a method of manufacturing the third substrate will be described below without using the drawings. Note that, of the components of the third substrate, the same components as those of the first and second substrates are denoted by the same reference numerals and described.

After the first substrate 11 is formed by the method of manufacturing the first substrate, a getter is formed on the surface of the silicon layer 14 formed on the surface side of the glass substrate 12 by the method of manufacturing the second substrate. The ring layer 18 is formed. In this case, the gettering layer 15 formed on the back surface side of the glass substrate 12 is formed of PSG, BPSG, or BSG.
The gettering layer 18 formed on the surface side of the silicon layer 14 is also formed of PSG, BPSG, or BSG.

As described above, in the third substrate in which the gettering layer 15 is formed on the back surface side of the glass substrate 12 and the gettering layer 18 is formed on the front surface side of the silicon layer 14, The same effects as those of the second substrate 17 can be obtained.

Here, a specific example of a method of growing a silicon single crystal constituting the silicon layer 14 will be described below.

The crystal growth method will be described below with reference to the manufacturing process diagram of FIG. The crystal growth method is shown in FIG.
As shown in (1), a step is formed on the surface side of the glass substrate 12 by anisotropic dry etching such as reactive ion etching to provide a seed 13 for crystal growth. Alternatively, although not shown, as a low-temperature film forming technique, a substance which is a seed for crystal growth on the surface side of the insulating substrate and has lattice matching with silicon by a low pressure CVD method, a plasma CVD method or sputtering, for example, A seed layer made of sapphire is formed. For the seed layer, spinel, calcium fluoride, or the like can be used.

Hereinafter, a case where a low melting point glass substrate is used as the glass substrate 12 and the step is used as a seed 13 for crystal growth will be described. The low-melting-point glass substrate has, for example, an aluminosilicate glass (for example, glass code number 1723 of Corning) having a maximum operating temperature of 665 ° C. (because it is almost the same as the strain point) and a strain point of 510 ° C. ° C
(For example, Corning Glass Code No. 7740).

Next, as shown in FIG. 6B, a silicon thin film 2 made of amorphous silicon or polycrystalline silicon is formed on the surface side of the glass substrate 12 by a low-temperature film forming technique.
1 is, for example, 5 nm to 10 μm (preferably 20 nm to 5 μm).
(μm). Examples of the low-temperature film forming technique include a low-pressure CVD method in which a process temperature (substrate temperature) is, for example, 500 ° C. to 650 ° C.
The VD method or the like is used.

Thereafter, as shown in FIG. 6C, the glass substrate 12 is immersed in the low melting point metal melt 22 stored in the tank, and at least the silicon thin film 21 and the low melting point metal melt 22 are melted. The silicon thin film 21 is dissolved in the low melting point metal melt 22 to generate a silicon-containing low melting point metal melt. At this time, the low melting metal melt 22
Is the maximum operating temperature of the glass substrate 12 (almost the strain point of glass)
Keep the temperature below. In addition, the low melting point metal melt 2
The temperature at which 2 maintains a molten state depends on the ratio of silicon. The atmosphere on the low melting point metal melt 22 is
The atmosphere is a hydrogen atmosphere, a mixed atmosphere of hydrogen and an inert gas (rare gas), or an inert gas (rare gas) atmosphere. Alternatively, the atmosphere may be a reducing atmosphere.

For example, when a tin-based metal melt comprising a tin melt or a tin-lead alloy melt is used as the low-melting metal melt 22, it depends on the amount of silicon dissolved in the tin-based metal melt. However, a tin-based metal melt at 400 ° C. to 1200 ° C. can be used. For example, when the ratio of the dissolved silicon is 0.0005 wt% to 0.03 wt% and the temperature of the tin-based metal melt is 400 ° C to 650 ° C, the glass substrate 12 has an aluminum silicate having a strain point of about 665 ° C. Glass may be used, and the temperature of the tin-based metal melt may be increased by 50
When the temperature is 0 ° C. or lower, borosilicate glass having a strain point of about 510 ° C. can be used.

Then, for a predetermined time, for example, 30 seconds to 60 minutes,
Preferably, the low melting point metal melt 2 is used for 10 to 30 minutes.
After the glass substrate 12 is immersed in the metal melt 2 to dissolve the silicon thin film 21 in the low-melting metal melt 22, the glass substrate 12 is pulled up from the low-melt metal melt 22 to gradually lower the glass substrate 12. Cooling (cooling processing) or cooling processing is performed with the glass substrate 12 immersed in the low-melting-point metal melt 22.

The crystal growth rate of the silicon is 0.1 μm
/ Min to 0.3 μm / min, and the cooling rate is 0.1 ° C./min to 0.3 ° C./min. For example, if the thickness of the crystal layer to be grown is 35 nm, the time required for the growth is 20 seconds ~
It's as short as 6 seconds. Therefore, the cooling operation is a lifting operation. The time required for the growth is, for example, the low melting point metal melt 1
5 can be optimized by adjusting the silicon content.

On the other hand, if the thickness of the crystal layer to be grown is 5
If it is μm, the growth time is as long as 50 minutes to 17 minutes.
Therefore, the cooling operation is cooling in a immersed state, and the cooling time requires 50 minutes to 17 minutes. The cooling time can be optimized, for example, by adjusting the content of silicon in the low melting point metal melt 15.

In this manner, as shown in FIG. 6D, the low melting point metal melt 2
2 (see (3) in FIG. 6) crystal grows (grapho-epitaxial growth) to form a silicon layer 14 of single crystal silicon on the surface side of the glass substrate 12. Since the bottom and the side wall of the step serving as the seed 13 for crystal growth are formed substantially at right angles to each other, the silicon layer 14 is composed of a (100) plane silicon single crystal. May be included. Since the thickness of the silicon layer 14 is substantially determined by, for example, the thickness of the silicon thin film 21, it is possible to control the thickness of the silicon layer 14 by controlling the thickness of the silicon thin film 21. . As a result of the crystal growth, a low melting point metal (not shown) is deposited on the silicon layer 14.

As shown above, seed 1 for crystal growth was used.
In the case where 3 is formed only with a step, single crystal silicon is deposited and grown starting from the step, and silicon layer 14 is formed in a so-called island shape. Also, the thickness of the silicon thin film 21 is increased and the interval between
By adjusting the lifting speed of the glass substrate 1,
It is also possible to form the silicon layer 14 over the entire surface side of the second.

Thereafter, the silicon layer 1 is formed using an acid such as hydrochloric acid.
4 to remove the low melting point metal (not shown). as a result,
This is a so-called SOI (Silicon on Insulator, hereinafter referred to as SOI) substrate in which a silicon layer 14 formed by depositing single crystal silicon from a crystal growth seed 13 as a starting point is formed on a glass substrate 12.

Next, the crystal growth method will be described below with reference to the manufacturing process diagram of FIG. In the crystal growth method, as shown in FIG. 7A, a glass substrate 12 similar to the crystal growth method is used and a step or a step is formed on the surface side of the glass substrate 12 by the same method as the crystal growth method. A seed layer made of a material having lattice matching with silicon (for example, sapphire, spinel, or calcium fluoride) is formed to form a seed 13 for crystal growth. Hereinafter, a case where a low melting point glass substrate is used as the glass substrate 12 and a step is used as a seed 13 for crystal growth will be described.

Thereafter, as shown in FIG. 7B, the surface side of the glass substrate 12 is immersed in a silicon-containing low melting point metal melt 23 so that at least the surface side of the glass substrate 12 and the silicon-containing low melting point metal are melted. Contact with the melting metal melt. At this time, the entire glass substrate 12 may be immersed. The temperature of the silicon-containing low melting point metal melt 23 is set to a temperature lower than the strain point of the low melting point glass. As the silicon-containing low melting point metal melt 23, for example, a silicon-containing tin-based metal melt comprising a silicon-containing tin melt or a silicon-containing tin-lead alloy melt can be used. Here, a silicon-containing tin melt was used. For example, a silicon-containing tin melt is in a molten state at about 400 ° C. to 650 ° C. when the silicon content is 0.0005% to 0.03% by weight. Therefore, the temperature applied to the glass substrate 12 is 400 ° C. to 6 ° C.
It will be about 50 ° C. Note that only the surface side of the glass substrate 12 may be immersed in the silicon-containing low-melting-point metal melt 23.

The silicon content of the above-mentioned silicon-containing tin melt is 0.0005% to 0.03% by weight, preferably 0.0035% to 0.014% by weight.
If the silicon content is less than 0.0005 wt%, the amount of silicon single crystal deposited is small, and mass productivity cannot be obtained. If the silicon content is more than 0.03 wt%, the temperature of the silicon-containing tin-based metal melt must be increased, making it difficult to use a low-melting glass substrate. However, when a quartz substrate (for example, the strain point is 990 ° C.) and a high heat-resistant glass substrate are used for the glass substrate 12, the silicon-containing tin-based metal is used in accordance with the maximum operating temperature (or the strain point) of each material. It is also possible to increase the silicon content until the melting point of the melt reaches about 1200 ° C.

When a tin-lead alloy melt containing silicon is used as the silicon-containing tin-based metal melt, for example, 0.05 wt% to 0.14 wt% of silicon is added to a tin lead alloy of 15% tin + 85% lead. Use a melt containing However, the ratio of tin to lead is an example, and is not limited to the above value, and can be appropriately selected.

Then, for a certain period of time, for example, 10 seconds to 30 minutes,
It is preferably immersed for 5 to 10 minutes. Thereafter, the glass substrate 1 is removed from the silicon-containing low melting point metal melt 23.
2 or by cooling the glass substrate 12 in a state where the glass substrate 12 is immersed in the silicon-containing low-melting-point metal melt 23, as shown in FIG. Silicon is crystal-grown (grapho-epitaxial growth) from the silicon-containing low-melting-point metal melt 23 (see (2) of FIG. 7) to form a silicon layer 14 of single-crystal silicon on the surface side of the glass substrate 12. Since the bottom of the step and the side wall of the step are formed substantially at right angles in the silicon layer 14, a (100) plane silicon single crystal is obtained.

The silicon crystal growth rate is 0.1 μm.
m / min to 0.3 μm / min, and the cooling rate is 0.1 ° C./min.
Therefore, if the thickness of the crystal layer to be grown is 35 nm, the time required for growth is as short as 20 seconds to 6 seconds. Therefore, the cooling operation is a lifting operation. The time required for the growth is optimized, for example, by adjusting the content of silicon in the silicon-containing low melting point metal melt 23. On the other hand, if the thickness of the crystal layer to be grown is 5 μm, the time required for growth is 50 minutes to 17 minutes.
Minutes and long. Therefore, the cooling operation is performed in a state of immersion, and a cooling time of 50 minutes to 17 minutes is required. The cooling time is optimized by, for example, adjusting the content of silicon in the silicon-containing low melting point metal melt 23.

Thereafter, the silicon layer 1 is formed using an acid such as hydrochloric acid.
4 to remove the tin-based metal (not shown). As a result, the seed 1 for crystal growth is formed on the glass substrate 12.
A silicon layer 14 is formed by depositing single crystal silicon starting from No. 3 to form a so-called SOI substrate.

In the above-described example, at least the glass substrate 12 is immersed in the silicon-containing low-melting-point metal melt 23, but the silicon-containing low-melting-point metal melt is applied to the surface side of the glass substrate 12 to form the glass substrate 12. The surface side may be brought into contact with the silicon-containing low-melting-point metal melt.

Next, the crystal growth method will be described below with reference to the manufacturing process diagram of FIG. In the crystal growth method, as shown in FIG. 8A, a glass substrate 12 similar to that used in the crystal growth method is used by the same method as the crystal growth method. Then, a seed layer made of a material having a step matching or lattice matching with silicon (for example, sapphire, spinel, or calcium fluoride) is formed to form a seed 13 for crystal growth. Hereinafter, a case where a low melting point glass substrate is used as the glass substrate 12 and a step is used as a seed 13 for crystal growth will be described.

Then, as shown in FIG. 8B, the silicon thin film 2 made of amorphous silicon or polycrystalline silicon is formed on the surface side of the glass substrate 12 by a low-temperature film forming technique.
1 is 5 nm to 50 nm (preferably 10 nm to 40 n
m). Further, the low melting point metal layer 2
4 is formed to a thickness of 230 to 70000 times the thickness of the silicon thin film. Here, a tin-based metal layer made of tin or a tin-lead alloy was used as the low-melting metal layer 24, and the tin-based metal layer was formed to a thickness of, for example, 40 μm to 50 μm. Either the silicon thin film 21 or the low melting point metal layer 24 may be formed first. When the low melting point metal layer 24 is formed of a tin-lead alloy, tin (15%) is used as an example.
+ Lead (85%) tin-lead alloy. The ratio of tin to lead is an example, and is not limited to the value, and can be appropriately selected. As the low-temperature film forming technique, for example, a process temperature (substrate temperature) is, for example, 500
C. to 650.degree.
Sputtering, plasma CVD, or the like set at 0 ° C. or lower is used.

Next, a heat treatment is performed. This heat treatment
In a hydrogen atmosphere, a mixed gas atmosphere of hydrogen and an inert gas, or an inert gas atmosphere, a temperature higher than the temperature at which the silicon-containing low melting point metal melt 23 is generated and lower than the maximum use temperature of the glass substrate 12 (in the case of a glass substrate, The glass substrate 12 is heated within a temperature range of less than the strain point), and the low melting point metal layer 24 is dissolved to generate a low melting point metal melt, and the silicon thin film is contained in the low melting point metal melt. Dissolve 21. As a result, as shown in FIG. 8C, the silicon-containing low melting point metal melt 2
5 is generated. Note that the atmosphere may be a reducing atmosphere.

More specifically, when the low melting point metal layer 24 is formed of a tin layer of a tin-based metal layer, the low melting point metal layer 24 has a temperature of 400 ° C. to 650 ° C.
C., preferably 500 ° C. to 600 ° C., and when the low melting point metal layer 24 is formed of a tin-lead alloy layer of a tin-based metal layer, 350 ° C. to 600 ° C., preferably 450 ° C. to 5 ° C.
Heating to 50 ° C. dissolves the tin-based metal layer to generate a tin-based metal melt and dissolves a silicon thin film in the tin-based metal melt. In this way, a silicon-containing tin-based metal melt is generated. This heat treatment is performed by a method of uniformly heating the entire substrate using an electric furnace, a lamp heating device, or the like, a method of locally heating by irradiating a laser beam, an electron beam, or the like.

The heating temperature is, for example, 0.0
005w% -0.03w% tin melt is 400
C. to 650.degree. Therefore, it is possible to use a so-called low-melting glass having a low maximum operating temperature (substantially the strain point of glass) as the glass substrate 12. Such a low-melting glass has a strain point of, for example, 665.
C. aluminosilicate glass and a borosilicate glass having a strain point of, for example, 510 ° C.

Then, at a heating temperature for a certain time (for example, 10
After holding for 2 to 60 minutes, preferably 5 to 10 minutes), a cooling process is performed to start the crystal-growing seed 13 and start the above-mentioned silicon-containing low-melting-point metal melt 23 (silicon-containing tin-based metal melt). The crystal | crystallization which melt | dissolves the silicon | silicone is grown (grapho epitaxial growth). As a result, as shown in FIG. 8D, a silicon single crystal is deposited on the surface side of the glass substrate 12 to form a silicon layer 14.
This silicon single crystal may include sub-grain boundaries and dislocations.
In the silicon layer 14, the step bottom and the step side wall are formed substantially at right angles, so that a (100) plane silicon single crystal can be obtained. The thickness of the silicon layer 14 is adjusted by, for example, the silicon concentration contained in the silicon-containing low-melting-point metal melt 23 [see (3) in FIG. 8]. As a result of the crystal growth, a low melting point metal (not shown) is formed on the silicon layer 14.
Are precipitated.

Then, the silicon layer 1 is formed using an acid such as hydrochloric acid.
4 to remove the low melting point metal (not shown). as a result,
A silicon layer 14 formed by depositing single crystal silicon starting from a seed 13 for crystal growth on a glass substrate 12 is formed, and a so-called SOI substrate is obtained. In addition, (4) of FIG.
Shows a state where the low melting point metal is removed.

Next, the crystal growth method will be described below with reference to the manufacturing process diagram of FIG. In the crystal growth method, as shown in FIG. 9A, a glass substrate 12 similar to that used in the crystal growth method is used by the same method as the crystal growth method. Then, a seed layer made of a material having a step matching or lattice matching with silicon (for example, sapphire, spinel, or calcium fluoride) is formed to form a seed 13 for crystal growth. Hereinafter, a case where a low melting point glass substrate is used as the glass substrate 12 and a step is used as a seed 13 for crystal growth will be described.

Next, as shown in FIG. 9B, a silicon-containing low melting point metal layer 26 is formed on the surface side of the glass substrate 12 to a thickness of, for example, 30 μm by a low-temperature film forming technique. Here, a silicon-containing tin-based metal made of tin containing silicon or a tin-lead alloy containing silicon is used for the silicon-containing low melting point metal layer 26. The thickness of the silicon-containing low-melting metal layer 26 is determined according to the silicon content and the thickness of the silicon layer 14 to be deposited. The low-temperature film forming technique includes, for example, a low pressure CVD method, a plasma CVD method at a process temperature (substrate temperature) of, for example, 500 ° C. to 650 ° C.
Use sputtering set at a temperature of 00 ° C. or lower.

Next, a heat treatment is performed. This heat treatment
Under a hydrogen atmosphere, a mixed gas atmosphere of hydrogen and an inert gas, or an inert gas atmosphere, the insulating substrate 11 is
50 ° C to 600 ° C, preferably 500 ° C to 600 ° C
Heat at a given temperature in ° C. As a result, the silicon-containing low-melting-point metal layer 26 is dissolved, and a silicon-containing low-melting-point metal melt 27 is generated on the surface side of the glass substrate 12 as shown in (3) of FIG. Then, the heating temperature is, for example, 60 seconds to 30 minutes, preferably 5 minutes to 10 minutes.
Hold for a minute. Here, for example, it is held for 5 minutes. In addition,
The atmosphere may be a reducing atmosphere.

Thereafter, the silicon dissolved in the silicon-containing low-melting-point metal melt 27 is crystal-grown (grapho-epitaxial growth) from the seed 13 for crystal growth by cooling. As a result, (4) in FIG.
As shown in FIG. 1, a silicon single crystal is deposited on the surface side of the glass substrate 12 to form a silicon layer 14. This silicon single crystal may include sub-grain boundaries and dislocations. In the silicon layer 14, the step bottom and the step side wall are formed substantially at right angles, so that a (100) plane silicon single crystal can be obtained. The thickness of the silicon layer 14 is adjusted by, for example, the concentration of silicon contained in the silicon-containing low-melting-point metal melt 27. As a result of the crystal growth, a tin-based metal (not shown) of a low melting point metal is deposited on the silicon layer 14.

Thereafter, the silicon layer 1 is formed using an acid such as hydrochloric acid.
4 to remove the tin-based metal (not shown). as a result,
A silicon layer 14 formed by depositing single crystal silicon starting from a seed 13 for crystal growth on a glass substrate 12 is formed, and a so-called SOI substrate is obtained. Note that (4) in FIG.
Shows a state where the tin-based metal has been removed.

The low melting point metal of the low melting point metal melt 22, the low melting point metal of the silicon-containing low melting point metal melt 23, the low melting point metal layer 24, and the low melting point metal of the silicon-containing low melting point metal layer 26 in each of the above crystal growth methods are as follows. Indium, gallium,
One or more of tin, bismuth, lead, zinc, antimony and aluminum can be used,
Preferably, tin, lead or an alloy of tin and lead is used.

In each of the above crystal growth methods, the seed 13 for crystal growth can be formed of a seed layer made of a material having lattice matching with silicon.
Such a seed layer can be formed of sapphire, spinel, calcium fluoride, or the like. For example, when the seed layer is formed of sapphire, a high-density plasma CVD method, a catalytic CVD method, etc.
It is formed by deposition to a thickness of 00 nm, preferably about 5 nm to 20 nm. Thereafter, the same process as described above is performed. In this case, instead of graphoepitaxy, single crystal silicon grows by inheriting the crystallinity of the seed layer. Since sapphire has almost the same lattice constant as single-crystal silicon, (100) single-crystal silicon [sapphire plane is (11 °)
02)] or (111) single crystal silicon (when the sapphire surface is (0001)) is epitaxially grown.

When a tin-based metal is used as a low-melting-point metal melt for dissolving a silicon thin film, even if a tin-based metal such as tin or lead is contained in the completed silicon layer, they are contained in the silicon layer. Not a career. Therefore, the silicon layer has a high resistance. In addition, tin remaining in the silicon layer electrically inactivates crystal defects, thereby reducing junction leakage and increasing electron mobility. On the other hand, when an indium-based metal (for example, indium or indium-gallium) is used for the low-melting-point metal melt, a small amount of indium remains in the silicon layer, so that the silicon layer becomes a p-type silicon layer.

In the case of the crystal growth method, a p-type impurity such as boron is mixed during the formation of the silicon thin film 21 and the impurity concentration is controlled to a predetermined amount. The silicon layer 14 becomes a p-type silicon layer having a desired concentration. On the other hand, if an n-type impurity such as phosphorus, arsenic, or antimony is mixed in and the impurity concentration is controlled to a predetermined amount, the silicon layer 14 becomes an n-type silicon layer having a desired concentration.

In the case of the crystal growth method, a desired conductivity type and impurity concentration can be obtained by doping the high-resistance silicon layer 14 with a p-type impurity or an n-type impurity. For example, if the silicon layer 14 is doped with a p-type impurity such as boron by an impurity doping technique such as ion implantation and the impurity concentration is controlled to a predetermined amount at that time, the silicon layer 14 has a desired concentration. Of a p-type silicon layer. On the other hand, for example, doping n-type impurities such as phosphorus, arsenic, and antimony, and controlling the impurity concentration to a predetermined amount at that time,
The silicon layer 14 becomes an n-type silicon layer having a desired concentration.

In the case of the crystal growth method, a p-type impurity such as boron is mixed during the formation of the silicon thin film 21 and the formation of the silicon-containing low melting point metal layer 26. If the impurity concentration is controlled to a desired amount, the silicon layer 14 becomes a p-type silicon layer having a desired concentration. On the other hand, if an n-type impurity such as phosphorus, arsenic, or antimony is mixed in and the impurity concentration is controlled to a desired amount at that time, the silicon layer 14 has a desired concentration of n.
Mold silicon layer.

When the process for forming the silicon layer 14 is performed at a temperature of 650 ° C. or lower, a low-melting glass can be used for the glass substrate 12, and a large glass substrate (a glass having an area of 1 m ² or more) can be used. It is also possible to form the silicon layer 14 on the (substrate). Further, it becomes possible to form a silicon layer continuously or discontinuously on a glass plate having a long crystal growth temperature roll. When a step is used as a seed for crystal growth, it is possible to form a silicon layer in a so-called island shape by growing a crystal starting from the step. Further advance the crystal growth,
It is also possible to form the silicon layer 14 on the entire front side of the glass substrate 12. On the other hand, when the seed layer as described above is used as a seed for crystal growth, a silicon layer can be formed on the entire surface of the seed layer. Therefore, when the silicon layer is formed in an island shape, the seed layer is patterned in an island shape before crystal growth,
Alternatively, the generated silicon layer may be patterned into an island shape.

When the above-mentioned low-melting glass is used, the constituent elements of the low-melting glass easily diffuse into the silicon layer formed by crystal growth. As a barrier layer for prevention, for example, a silicon nitride film is preferably formed to a thickness of, for example, about 1 nm to 100 nm.

The silicon layer 1 formed as described above
No. 4 has an electron mobility of about 540 cm ² / Vs. Therefore, if an appropriate amount of p-type impurity is mixed in advance to form a p-type silicon layer having a desired concentration, active regions (a channel region, a source region, and a drain region) of an n-channel insulated gate field effect transistor are manufactured. It is convenient. If an appropriate amount of an n-type impurity is mixed in advance to form an n-type silicon layer having a desired concentration, an active region (a channel region, a source region, and a drain region) of a p-channel insulated gate field effect transistor is manufactured. It is convenient. Further, a CMOS transistor can be manufactured by partially doping impurities different from the conductivity type of the silicon layer.

Next, an embodiment relating to the first semiconductor device of the present invention will be described with reference to the schematic sectional view of FIG. In FIG. 10, a MOS transistor is shown as a semiconductor element, and the same components as those described with reference to FIGS.

As shown in FIG. 10, a step serving as a seed 13 for crystal growth is formed on the surface side of the glass substrate 12, and silicon is formed by growing silicon from the seed 13 for crystal growth. A layer 14 is formed. The silicon layer 14 is formed, for example, by using silicon in a low-melting metal melt containing silicon as a seed (step) for crystal growth.
13 and is made of single crystal silicon by grapho-epitaxial growth. Thus, the silicon layer 14 formed by crystal growth on the surface side of the glass substrate 12 is formed. On the other hand, a gettering layer 15 is formed on the back side of the glass substrate 12. The gettering layer 15 is for gettering metals, mainly alkali metal ions such as sodium ions, and is formed of, for example, PSG. Alternatively, it may be formed of a BPSG layer or a BSG layer.

The semiconductor element 32 is provided on the silicon layer 14.
Are formed. This semiconductor element 32 is composed of a MOS transistor, and has a gate insulating film 3 on a silicon layer 14.
3, a gate electrode 34 is formed.
A source region 35 is formed in the silicon layer 14 on one side, and a drain region 36 is formed in the silicon layer 14 on the other side. The silicon layer 14 between the source region 35 and the drain region 36 forms a channel. The formation region 37 is formed. As described above, the first semiconductor device 31 including the semiconductor element 32 formed on the substrate 12 is configured.

In the first semiconductor device 31, since the gettering layer 15 is formed on the back surface of the glass substrate 12, even if the glass substrate 12 contains alkali metal ions such as sodium ions. Since the alkali metal ions are taken into the gettering layer 15, the alkali metal ions are prevented from diffusing near the interface of the silicon layer 14. Therefore, the semiconductor element 32 formed on the silicon layer 14 is not affected by the alkali metal ions contained in the glass substrate 12. That is, sodium ions do not accumulate at the interface between the gate insulating film 33 and the silicon layer 14 and the threshold voltage does not fluctuate due to sodium ions, so that deterioration of transistor performance is prevented.

Next, an embodiment according to the second semiconductor device of the present invention will be described with reference to a schematic sectional view of FIG. In FIG. 11, a MOS transistor is shown as a semiconductor element, and the same reference numerals are given to the same components as those described with reference to FIGS.

As shown in FIG. 11, the second semiconductor device 4
Reference numeral 1 denotes a silicon layer 14 formed by growing silicon in a low-melting-point metal melt from a crystal growth seed (step in the drawing) 13 formed on the surface side of the glass substrate 12.
A gettering layer 18 for gettering a metal, particularly an alkali metal ion such as sodium ion, is formed on the surface side of the silicon layer 14. is there. Here, the gettering layer 18 is formed of PSG via the gate insulating film 33. The gettering layer 18 can be formed of BPSG or BSG.

A gate electrode 34 is formed on the silicon layer 14 with a silicon oxide film serving as a gate insulating film 33 and a gettering layer 18 interposed therebetween. The silicon layer 14 on one side of the gate electrode 34 has a source region. 35 is formed, and the drain region 3 is formed in the silicon layer 14 on the other side.
6 is formed, and the silicon layer 14 between the source region 35 and the drain region 36 is
It is 7.

The seed 13 for crystal growth can be formed of a sapphire layer, a spinel layer, or a calcium fluoride layer, which is a layer having lattice matching with silicon, for example, in addition to the steps. . The crystal growth of silicon in the case where the seed 13 for crystal growth is formed at a step is so-called graphoepitaxy, and the crystal growth of silicon when the seed 13 for crystal growth is formed in a sapphire layer, a spinel layer or a calcium fluoride layer is as follows. This is normal epitaxial growth in which the crystal grows while inheriting the crystallinity of the base.

In the second semiconductor device 41, since the gettering layer 22 is formed on the surface side of the silicon layer 14, alkali metal ions such as sodium ions which are likely to diffuse from the surface side of the silicon layer 14 are not formed. Since it is taken into the gettering layer 18, diffusion to the vicinity of the interface of the silicon layer 14 is prevented. Therefore, the semiconductor element 42 formed on the silicon layer 14 is
2 is not affected by the alkali metal ions contained in 2. That is, the alkali metal ions are converted into the gate insulating film 33.
Is prevented from accumulating at the interface between the semiconductor layer and the silicon layer 14, and the threshold voltage does not fluctuate due to alkali metal ions, so that deterioration of transistor performance is prevented.

In the second semiconductor device 41, the glass substrate 12 has a gettering layer for gettering alkali metal ions such as sodium ions on the back surface of the glass substrate 12 like the first semiconductor device 31. 1
5 may be formed. The semiconductor device having such a configuration has the functions and effects of both the first semiconductor device 31 and the second semiconductor device 41.

Next, an embodiment of the first method of manufacturing a semiconductor device according to the present invention will be described below with reference to FIGS. 12 to 14 show a method of manufacturing a CMOS transistor as an example, and the same components as those described with reference to FIGS. 1 to 3 are given the same reference numerals.

First, as shown in FIG. 12A, the first method of manufacturing the semiconductor device is the same as the method of manufacturing the first substrate having a silicon layer described with reference to FIG. Gettering layer 1 for gettering alkali metal ions such as sodium ions on the back side of substrate 12
A glass substrate 12 on which 5 is formed is prepared. Then, seeds 13 for crystal growth are formed on the surface side of the glass substrate 12, and silicon in the silicon-containing low-melting-point metal melt is crystal-grown from the seeds 13 for crystal growth as starting points. The silicon layer 14 is formed and the first
Of the substrate 11 is formed. After that, the low melting point metal (not shown) deposited on the silicon layer 14 is removed using an acid such as hydrochloric acid. This figure shows a state where the tin-based metal (not shown) deposited on the silicon layer 14 is selectively removed.

The gettering layer 15 may be formed after the seed 13 for crystal growth is formed or after the silicon layer 14 is formed. In FIG. 12A, a case where a step is used as a seed for crystal growth is shown as a representative, but a seed layer such as a sapphire layer, a spinel layer, or the like which can obtain lattice matching with silicon is shown. Using the calcium fluoride layer as a seed for crystal growth, silicon in the silicon-containing low-melting metal melt may be crystal-grown to form the silicon layer 14.

Next, as shown in FIG. 12 after (2),
A predetermined process is performed on the silicon layer 14 so that the semiconductor device 5
1 is performed. Here, a method of manufacturing a CMOS transistor as the semiconductor element 52 will be described below.

As shown in FIG. 12 (2), a gate insulating film 51 is formed on the glass substrate 12 so as to cover the silicon layer 14 (14n, 14p). The gate insulating film 51 is formed by depositing a silicon oxide film to a thickness of, for example, 200 nm and then depositing a silicon nitride film to a thickness of, for example, 50 nm by, for example, a plasma CVD method. Each film forming temperature at that time is, for example, 40
It was set to 0 ° C.

Next, as shown in FIG. 12C, a resist film 52 is formed on the gate insulating film 51 by, for example, a spin coating method. Then, an opening 53 is formed by lithography to open the region where the channel of the n-channel MOS transistor is formed, and a resist mask is formed. That is, the resist film 52 is formed on the silicon layer 14p.
Is coated. Thereafter, using this resist film 52 as a mask, channel ion implantation of the p-channel MOS transistor is performed through the gate insulating film 51 to the silicon layer 14.
n. As the ion implantation conditions, for example, boron ions (B ⁺ ) are used as impurities, the implantation energy is, for example, 30 keV, and the dose is, for example, 2.7 × 10 ¹¹ at.
oms / cm ² . After that, the resist film 5
Remove 2. Note that the drawing shows a state before the resist film 52 is removed.

Subsequently, as shown in FIG. 13D, a resist film 54 is formed on the gate insulating film 51 by, for example, a spin coating method. Then, an opening 55 is formed by lithography to open a region where a channel of the p-channel MOS transistor is formed, and a resist mask is formed. That is, the resist film 54 is formed on the silicon layer 14n.
Is coated. Thereafter, using this resist film 54 as a mask, channel ion implantation of the p-channel MOS transistor is performed through the gate insulating film 51 to the silicon layer 14.
Perform on p. As the ion implantation conditions, for example, phosphorus ions (P ⁺ ) are used as impurities, the implantation energy is, for example, 50 keV, and the dose is, for example, 1 × 10 ¹¹ atoms
/ Cm ² . After that, the resist film 54 is removed. Note that the drawing shows a state before the resist film 54 is removed.

Next, as shown in FIG. 13 (5), a gate electrode film 56 is formed on the gate insulating film 51 by, for example, sputtering to form a molybdenum (15%) tantalum (85%) film with a thickness of, for example, 500 nm. Formed.

Then, a resist film 57 is formed on the gate electrode film 56 by, for example, a spin coating method. Then, the resist film 57 (57p, 57n) is left on the region where the gate electrode is formed by lithography. Then, the gate electrode film 56 is patterned by a dry etching technique using the resist film 57 as a mask. as a result,
As shown in FIG. 13 (6), each silicon layer 14 (14
A gate electrode 58 (58p, 58n) is formed on the p, 14n) via a gate insulating film 51. After that, the resist film 57 is removed. In the drawing, the resist film 57 is used.
Before removal.

Next, as shown in FIG. 14 (7), a resist film 59 is formed by, for example, a spin coating method so as to cover the gate electrode 58, the gate insulating film 51 and the like. Then, an opening 60 is formed by lithography to open a region where a channel of the p-channel MOS transistor is formed, and a resist mask is formed. That is, the silicon film 14n is covered with the resist film 59. afterwards,
Using the resist film 59 and the gate electrode 58p as a mask, the source and drain ions of the p-channel MOS transistor are implanted into the silicon layer 14p. As the ion implantation conditions, for example, boron difluoride (BF ₂ ⁺ ) is used as an impurity, and the implantation energy is set to, for example, 30.
keV and a dose amount of, for example, 1 × 10 ¹⁵ atoms / cm
Set to ² . After that, the resist film 59 is removed. Note that the drawing shows a state before the resist film 59 is removed.

Next, as shown in FIG. 14 (8), a resist film 61 is formed by, for example, a spin coating method so as to cover the gate electrode 58, the gate insulating film 51 and the like. Then, an opening 62 is formed by lithography to open a region where the channel of the n-channel MOS transistor is formed, and a resist mask is formed. That is, the silicon film 14p is covered with the resist film 61. After that, using the resist film 61 and the gate electrode 58n as a mask, the source of the n-channel MOS transistor is
Drain ion implantation is performed on the silicon layer 14n via the gate insulating film 51. As the ion implantation conditions, for example,
Arsenic ions (As ⁺ ) are used as impurities, the implantation energy is, for example, 70 keV, and the dose is, for example, 5 × 10 ^15.
Set to atoms / cm ² . After that, the resist film 61 is removed. The drawing shows the state before the resist film 61 is removed.

Thereafter, as shown in FIG. 14 (9), activation annealing of the source and the drain is performed, for example, for 1000 times.
At a temperature of 10 ° C. for 10 seconds to form a source region 62p on the silicon layer 14p on one side of the gate electrode 58p.
Is formed, and the drain region 6 is formed in the silicon layer 14p on the other side.
3p to form a p-channel MOS transistor 50p
Is completed. At the same time, a source region 62n is formed in the silicon layer 14n on one side of the gate electrode 58n,
Drain region 63n is formed in silicon layer 14n on the other side, and n-channel MOS transistor 50n is completed. Then, under the gate electrode 58n and the source region 62n
The silicon layer 14n between the gate region and the drain region 63n becomes the channel region of the n-channel MOS transistor 50n, and the silicon layer 14p below the gate electrode 58p and between the source region 62p and the drain region 63p is It becomes a channel area. Thus, the CMOS transistor 50 is completed.

Thereafter, although not shown, the n-channel MOS transistors 50n and 50n are
A silicon oxide film is formed to a thickness of, for example, 200 nm so as to cover the channel MOS transistor 50p and the like, and a phosphor silicate glass (PSG) film is formed to a thickness of, for example, 500 n.
m to form an interlayer insulating film. PS
The G film is formed at a phosphorus concentration of, for example, 3.5 w% to 4.0 w%.

Next, after a resist film is formed on the interlayer insulating film by, for example, a spin coating method, an opening is formed in a predetermined region where an electrode is to be formed by a lithography technique to form a resist mask. Thereafter, using the resist film as a mask, the interlayer insulating film is etched to form a connection hole. After removing the resist mask, an electrode film is formed by depositing, for example, aluminum-silicon to a thickness of, for example, 1.0 μm on the interlayer insulating film including the inside of the connection hole by, for example, sputtering. The substrate temperature during this sputtering was set to, for example, 150 ° C.

Thereafter, after forming a resist film on the electrode film by, for example, a spin coating method, the resist film is patterned by a lithography technique to leave a resist film on a predetermined region where an electrode is to be formed. Then, using this resist film as a mask, the electrode film is etched to form electrodes and wiring. Thereafter, the resist mask is removed.

In the first method for fabricating a semiconductor device, the glass substrate 12 on which the gettering layer 15 is formed on the back side is used to form a CMO comprising an n-channel MOS transistor 50n and a p-channel MOS transistor 50p.
Since the S transistor 50 is formed, alkali metal ions such as sodium ions contained in the glass substrate 12 are taken into the gettering layer 15, and the alkali metal ions are formed near the interface between the glass substrate 12 and the silicon layer 14. Metal ions will not collect. Therefore, deterioration of the performance of the CMOS transistor 50 due to the alkali metal ions can be avoided.

In addition, since the silicon layer 14 is formed by using any one of the above-described crystal growth methods, the low melting glass can be used for the glass substrate 12. Moreover, since the silicon layer 14 is formed of single crystal silicon and has the same performance as that of a bulk silicon substrate, the silicon layer 14 is subjected to a predetermined process so as to serve as a semiconductor element.
CMOS transistor 50 obtained by forming OS transistor 50n and p-channel MOS transistor 50p
Can provide the same high-performance characteristics as those formed on a bulk silicon substrate.

In the above description, a CMOS transistor has been described. However, the silicon layer 14 has a high-speed, large-current-density top-gate TFT, bottom-gate TFT, dual-gate TFT, electroluminescent element,
It is also possible to form a semiconductor element such as a transistor for a field emission display element, a diode, a capacitor, a resistor, a photocell (solar cell), a light-emitting element, a light-receiving element, or the like.

Next, an embodiment according to the second semiconductor device of the present invention will be described below. In the following,
Components similar to those of the first semiconductor device described with reference to FIG. 11 will be described by assigning the same reference numerals.

The second method of manufacturing a semiconductor device is to form a silicon layer 14 on a glass substrate 12 by any one of the above-described crystal growth methods and then to form a low melting point deposited on the silicon layer 14. The metal (not shown) is removed.

Then, after the gate insulating film 51 is formed so as to cover the silicon layer 14, the gettering layer 2 is formed.
2 and then the gate electrode film 56 is formed.
The gettering layer 22 is for gettering alkali metal ions, and is formed of phosphorus silicate glass, boron phosphorus silicate glass, or boron silicate glass. The gate insulating film 51 and the gettering layer 22
The gate electrode film 56 is formed by a low-temperature film forming technique. This low-temperature film formation technology is 450 ° C.
A low-pressure CVD method at a substrate temperature of about 650 ° C., a plasma CVD method at a substrate temperature of 400 ° C. or lower, or sputtering is used.

Thereafter, a predetermined process is performed by the same method as the method of manufacturing the first semiconductor device to form the CMOS transistor 50.

Next, an embodiment relating to the third semiconductor device of the present invention will be described below. In the following,
The same components as those of the first and second semiconductor devices will be described with the same reference numerals.

The third method for manufacturing a semiconductor device is as follows.
The method for manufacturing a semiconductor device according to the second embodiment is the same as the method for manufacturing a second semiconductor device except that a glass substrate 12 having a gettering layer 15 for gettering alkali metal ions such as sodium ions is formed on the back surface side. It is a process of. In this manufacturing method, the gettering layer 15 uses PSG, or uses BPSG or BSG. On the other hand, the gettering layer 22 formed on the surface side of the silicon layer 14 is formed by PSG. Or BPS
G or BSG.

In the third method for manufacturing a semiconductor device, the effects of both the method for manufacturing the first semiconductor device and the method for manufacturing the second semiconductor device are provided.

The method for manufacturing a silicon layer in each of the above methods for manufacturing a semiconductor device is the same as the method for manufacturing a substrate having a silicon layer.

The various numerical values described in the above embodiments are:
This is an example, and is not limited to the value, and can be appropriately changed.

[0148]

As described above, according to the first substrate having the silicon layer of the present invention, since the glass substrate having the gettering layer formed on the back surface is used, sodium is contained in the glass substrate. Even if an alkali metal ion such as an ion is contained, the alkali metal ion is taken into the gettering layer. Therefore, it is possible to prevent alkali metal ions from diffusing near the interface of the silicon layer. Therefore, a high-performance semiconductor element can be formed in the silicon layer.

According to the second substrate having a silicon layer of the present invention, since the gettering layer is formed on the surface side of the silicon layer, the alkali metal such as sodium ion which is likely to diffuse from the surface side of the silicon layer. The ions are incorporated in the gettering layer. Therefore, it is possible to prevent alkali metal ions from diffusing near the interface of the silicon layer. Therefore, a high-performance semiconductor element can be formed in the silicon layer.

According to the method for manufacturing a substrate having a silicon layer of the present invention, since a glass substrate having a gettering layer formed on the back side is used, an alkali metal ion such as sodium ion is contained in the glass substrate. Even so, the alkali metal ions are taken into the gettering layer. Therefore, diffusion of alkali metal ions in the glass substrate near the interface of the silicon layer can be prevented.

According to the method for manufacturing the second substrate having a silicon layer of the present invention, since the gettering layer is formed on the surface of the silicon layer, the alkali metal such as sodium ion which is to diffuse from the surface side of the silicon layer. The ions are taken into the gettering layer. Therefore, diffusion to the vicinity of the interface of the silicon layer is prevented.

According to the first semiconductor device of the present invention, the gettering layer is formed on the back side of the glass substrate, so that the glass substrate contains alkali metal ions such as sodium ions. However, since the alkali metal ions are taken into the gettering layer, they are prevented from diffusing near the interface of the silicon layer. Therefore, the semiconductor element formed on the silicon layer is not affected by the alkali metal ions contained in the glass substrate, so that performance can be prevented from deteriorating and a high-performance semiconductor element can be obtained.

According to the second semiconductor device of the present invention, since the gettering layer is formed on the surface side of the silicon layer, alkali metal ions such as sodium ions that diffuse from the surface side of the silicon layer are not gettered. It is taken into the ring layer. For this reason, diffusion of alkali metal ions near the interface of the silicon layer is prevented. for that reason,
Since the semiconductor element formed on the silicon layer is not affected by an alkali metal ion from the outside, the performance can be prevented from deteriorating, and a high-performance semiconductor element can be obtained.

According to the first method of manufacturing a semiconductor device of the present invention, since a glass substrate having a gettering layer formed on the back side is used, an alkali metal ion such as sodium ion is contained in the glass substrate. Even so, the alkali metal ions are taken into the gettering layer. Therefore, diffusion of alkali metal ions in the glass substrate near the interface of the silicon layer can be prevented. Therefore, the semiconductor element formed in the silicon layer is not affected by the alkali metal ions, so that a high-performance semiconductor element can be formed.

According to the second method of manufacturing a semiconductor device of the present invention, since the gettering layer is formed on the surface side of the silicon layer, the alkali metal such as sodium ions which diffuses from the surface side of the silicon layer. The ions are taken into the gettering layer. Therefore, the intrusion of alkali metal ions from the outside into the vicinity of the interface of the silicon layer can be prevented, and a high-performance semiconductor element can be formed on the silicon layer.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an embodiment of a first substrate having a silicon layer according to the present invention.

FIG. 2 is a schematic cross-sectional view showing an embodiment of a second substrate having a silicon layer according to the present invention.

FIG. 3 is a schematic sectional view showing an embodiment relating to a third substrate having a silicon layer of the present invention.

FIG. 4 is a manufacturing process diagram showing an embodiment according to a first method for manufacturing a substrate having a silicon layer of the present invention.

FIG. 5 is a manufacturing process diagram showing an embodiment according to a second method for manufacturing a substrate having a silicon layer of the present invention.

FIG. 6 is a manufacturing process diagram showing a crystal growth method for forming a silicon layer.

FIG. 7 is a manufacturing process diagram showing a crystal growth method for forming a silicon layer.

FIG. 8 is a manufacturing process diagram showing a crystal growth method for forming a silicon layer.

FIG. 9 is a manufacturing process diagram showing a crystal growth method for forming a silicon layer.

FIG. 10 is a schematic sectional view showing an embodiment according to a first semiconductor device of the present invention.

FIG. 11 is a schematic sectional view showing an embodiment according to a second semiconductor device of the present invention.

FIG. 12 is a manufacturing process diagram showing an embodiment according to the first method of manufacturing a semiconductor device of the present invention.

FIG. 13 is a manufacturing process diagram (continuing 1) showing the embodiment of the first semiconductor device manufacturing method of the present invention.

FIG. 14 is a manufacturing process diagram (continued from 2) showing the embodiment according to the first method for manufacturing a semiconductor device of the present invention.

[Explanation of symbols]

11: first substrate, 12: glass substrate, 13: seed for crystal growth, 14: silicon layer, 15: gettering layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hajime Yagi 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Yuichi Sato 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation F-term (reference) HJ01 HJ13 HJ23 HL06 HL23 NN23 NN25 NN35 QQ28

Claims (24)

[Claims] 1. A substrate having a silicon layer formed by crystal growth of silicon in a low-melting metal melt containing silicon on the front side of a glass substrate on which a seed for crystal growth is formed. A substrate having a silicon layer, on which a gettering layer is formed. 2. A substrate having a silicon layer formed by crystal-growing silicon in a low-melting-point metal melt containing silicon on the surface side of a glass substrate on which a seed for crystal growth is formed, wherein: A substrate having a silicon layer, on which a gettering layer is formed. 3. The substrate having a silicon layer according to claim 1, wherein a gettering layer is formed on a front side of the silicon layer. 4. The substrate having a silicon layer according to claim 1, wherein said gettering layer is for gettering alkali metal ions, and is made of phosphorus silicate glass, boron phosphorus silicate glass or boron silicate glass. . 5. The substrate having a silicon layer according to claim 2, wherein said gettering layer is for gettering alkali metal ions, and is made of phosphorus silicate glass, boron phosphorus silicate glass or boron silicate glass. . 6. The gettering layer formed on the back surface side of the glass substrate is for gettering alkali metal ions, and is made of phosphorus silicate glass, boron phosphorus silicate glass or boron silicate glass. The gettering layer formed on the surface side is for gettering alkali metal ions,
4. The substrate having a silicon layer according to claim 3, wherein the substrate is made of phosphorus silicate glass, boron phosphorus silicate glass, or boron silicate glass. 7. A step of forming a seed for crystal growth on the surface side of the glass substrate, and crystal-growing silicon in the silicon-containing low-melting-point metal melt from the seed for crystal growth as a starting point. Forming a silicon layer on the side of the glass substrate, wherein a gettering layer is formed on the back side of the glass substrate. 8. A step of forming a seed for crystal growth on the surface side of the glass substrate; and starting from the seed for crystal growth to grow silicon in the silicon-containing low-melting metal melt to form a seed on the surface side of the glass substrate. Forming a silicon layer on the surface of the silicon layer, comprising: forming a silicon layer on the surface of the silicon layer; and forming a gettering layer on the surface of the silicon layer. And a method of manufacturing a substrate having a silicon layer. 9. The method according to claim 1, further comprising: removing the metal deposited on the silicon layer after forming the silicon layer; and forming a gettering layer on the silicon layer. A method for manufacturing a substrate having a silicon layer according to claim 7. 10. The substrate having a silicon layer according to claim 7, wherein said gettering layer is formed of phosphorus silicate glass, boron phosphorus silicate glass or boron silicate glass for gettering alkali metal ions. Production method. 11. The substrate having a silicon layer according to claim 8, wherein said gettering layer is formed of phosphorus silicate glass, boron phosphorus silicate glass or boron silicate glass for gettering alkali metal ions. Production method. 12. A gettering layer formed on the back side of the glass substrate is formed of phosphorus silicate glass, boron phosphorus silicate glass, or boron silicate glass for gettering alkali metal ions. The gettering layer to be formed
10. A silicate glass, a boron silicate glass or a boron silicate glass for gettering alkali metal ions.
A method for manufacturing a substrate having the silicon layer as described above. 13. A semiconductor device in which a semiconductor element is formed on a silicon layer obtained by crystal-growing silicon in a low-melting-point metal melt containing silicon on the surface side of a glass substrate on which a seed for crystal growth is formed, A semiconductor device, wherein a gettering layer is formed on the back side of the glass substrate. 14. A semiconductor device in which a semiconductor element is formed on a silicon layer obtained by crystal-growing silicon in a low-melting metal melt containing silicon on the surface side of a glass substrate on which a seed for crystal growth is formed, A semiconductor device, wherein a gettering layer is formed on a surface side of the silicon layer. 15. The semiconductor device according to claim 13, wherein a gettering layer is formed on a surface side of said silicon layer. 16. The semiconductor device according to claim 13, wherein said gettering layer is for gettering alkali metal ions, and is made of phosphorus silicate glass, boron phosphorus silicate glass, or boron silicate glass. 17. The semiconductor device according to claim 14, wherein the gettering layer is for gettering alkali metal ions, and is made of phosphorus silicate glass, boron phosphorus silicate glass, or boron silicate glass. 18. The gettering layer formed on the back side of the glass substrate, for gettering alkali metal ions, is made of phosphorus silicate glass, boron phosphorus silicate glass or boron silicate glass. The gettering layer formed on the surface side is for gettering alkali metal ions,
16. The semiconductor device according to claim 15, wherein the semiconductor device is made of phosphorus silicate glass, boron phosphorus silicate glass, or boron silicate glass. 19. A step of forming a seed for crystal growth on the surface side of the glass substrate, and crystal-growing silicon in the silicon-containing low-melting-point metal melt from the seed for crystal growth to start the crystal substrate. Forming a silicon layer on the silicon layer; removing a metal deposited on the silicon layer; and performing a predetermined process on the silicon layer to form a semiconductor element. A method of manufacturing a semiconductor device, comprising: forming a gettering layer on a back surface of the glass substrate. 20. A step of forming a seed for crystal growth on the surface side of the glass substrate, and crystal-growing silicon in the silicon-containing low-melting-point metal melt from the seed for crystal growth to start the crystal substrate. Forming a silicon layer on the silicon layer; removing a metal deposited on the silicon layer; and performing a predetermined process on the silicon layer to form a semiconductor element. Removing a metal deposited on the silicon layer; and performing a predetermined process on the silicon layer for forming a gettering layer on the silicon layer to form a semiconductor element. A method for manufacturing a semiconductor device. 21. The method according to claim 19, further comprising a step of forming a gettering layer on the silicon layer after the step of removing the metal deposited on the silicon layer. . 22. The method of manufacturing a semiconductor device according to claim 19, wherein the gettering layer is formed of phosphorus silicate glass, boron phosphorus silicate glass, or boron silicate glass for gettering alkali metal ions. 23. The method according to claim 20, wherein the gettering layer is formed of phosphorus silicate glass, boron phosphorus silicate glass, or boron silicate glass for gettering alkali metal ions. 24. A gettering layer formed on the back side of the glass substrate, wherein the gettering layer is made of phosphorus silicate glass, boron phosphorus silicate glass or boron silicate glass for gettering alkali metal ions. 22. The method for manufacturing a semiconductor device according to claim 21, wherein the gettering layer formed in step (b) is formed of phosphorus silicate glass, boron phosphorus silicate glass, or boron silicate glass for gettering alkali metal ions.