JP3461819B2 - Manufacturing method of semiconductor crystal film - Google Patents

Description

Detailed Description of the Invention

[0001]

2. Description of the Related Art The main reason why semiconductor devices using Si crystals have been able to realize multi-functionality and high speed one after another is mainly due to the miniaturization of elements. In order to improve device performance in the future, further miniaturization will be required,
There are many technical issues that must be overcome in order to further miniaturize devices. Furthermore, no matter how miniaturized, the maximum performance of the device is limited by the physical characteristics (eg, mobility) of the material called Si crystal. That is, it can be said that it is difficult to dramatically improve the device performance as long as a material called Si crystal is used.

Therefore, in recent years, a device using a group IV element mixed crystal semiconductor has attracted attention, instead of a technique of miniaturization. Among them, silicon germanium carbon (Si _1-xy Ge _x C _y : 0) which is a group IV element mixed crystal semiconductor containing C
Recently, researches on ≦ x ≦ 1, 0 ≦ y ≦ 1) have been actively conducted. The Si _1-xy Ge _x C _y crystal can be regarded as an improved material of a silicon germanium (Si _1-x Ge _x : 0 ≦ x ≦ 1) crystal which is actually applied to a device. This Si _1-xy Ge _x C
_{The y} crystal has the following excellent characteristics as compared with the Si _1-x Ge _x crystal.

First, as the first characteristic, Si _1-xy Ge _x C
_{The y} crystal has a characteristic that the compressive strain at the time of heterojunction with the Si crystal is smaller than that of the Si _1-x Ge _x crystal, and the reason will be described below.

Si_1-xGe_x By crystal and Si crystal
When the terror junction is formed, Si_1-xGe_x Crystal is Si
Larger lattice constant than crystal, so large compressive strain is likely to occur
Yes. If this compressive strain occurs in the crystal, dislocations tend to occur.
Therefore, the value of the critical film thickness decreases and dislocations are not generated.
The thickness of the film that can be deposited without limitation is limited.
Relaxation with dislocation generation tends to occur during heat treatment
Become. On the other hand, this Si_1-xGe_x Si in the crystal
Si with C added, which has a smaller atomic radius than Ge_1-xyGe_xC
_y The lattice constant of the crystal is Si_1-xGe_x Smaller than a crystal. This
Therefore, S grown epitaxially on Si crystal
i_1-xyGe_xC_y Odor of crystal and Si crystal
Therefore, if large compressive strain is hard to occur and thermal resistance is high,
It is considered. Furthermore, about 1/8 of the Ge composition ratio x
Si with C composition ratio y_1-xyGe_xC _y In crystals, Si
It is possible to make a lattice match with the crystal.

The second characteristic is Si _1-xy G
As described below, the e _x C _y crystal has a characteristic that a band offset occurs in both the conduction band and the valence band when a heterojunction is formed with the Si crystal.

First, when a Si _1-x Ge _x crystal and a Si crystal form a heterojunction, band offset occurs only in the valence band region of the Si _1-x Ge _x crystal in the band structure of the hetero crystal, and the conduction band. Since it does not occur in the region, Si _1-x
When forming a high-speed MOS transistor having a Ge _x crystal portion as a channel, a p-channel transistor can be manufactured, but an n-channel transistor cannot be manufactured. In contrast, when the Si _1-xy Ge _x C _y crystal and the Si crystal to form a heterojunction, Si _1-xy Ge _x C _y crystal Ge
When the content rate and the C content rate are high (when the Ge content rate is several tens at.% And the C content rate is several at.% Or more), band offset occurs in both the valence band and the conduction band. (K. Brunner et al., J.Vac.Sci.Technol.
B16, 1701 (1998)). In this case, carrier confinement is possible in both the conduction band and the valence band,
It is possible to manufacture not only p-channel but also n-channel transistors.

Next, as a third characteristic, C has a characteristic of suppressing diffusion of impurities such as B (boron). This property works very effectively in manufacturing a device that needs to appropriately control the profile of B,
It is also useful when stabilizing the manufacturing process of semiconductor devices. For example, when manufacturing an ultrafast npn bipolar transistor having a narrow base region or a field effect transistor using δ-doping, by using a semiconductor layer containing C in a region doped with B, diffusion of B by heat treatment is prevented, It is possible to manufacture a device having a doping profile as designed.

As described above, the Si _1-xy Ge _x C _y crystal which is a _Group IV crystal containing C is a material having properties superior to those of the Si crystal and the Si _1-x Ge _x crystal.

[0009]

However, it is more difficult to manufacture a high-quality Si _1-xy Ge _x C _y crystal than a Si _1-x Ge _x crystal due to the peculiar properties of C as described below. .

First, the solid solubility of C atoms in Si crystals and Ge crystals is very low (about 10 ¹⁷ in Si crystals in a thermal equilibrium state).
/ cm ³ , about 10 ⁸ / cm ^{3 for} Ge crystals, high content (a
It is difficult to manufacture a crystal containing C atoms of (t.% order) in a thermal equilibrium state such as a melting method.

Further, the C atom has a property of easily entering not only the lattice position of the crystal but also the lattice. In this specification, for the sake of convenience, C which has entered the lattice position of the crystal is used.
An atom is called a C atom at a lattice position, and a C atom that has entered between the lattices of a crystal is called an interstitial C atom. Furthermore, C atoms tend to selectively bond with Si atoms in the crystal lattice,
iC crystal (crystalline silicon carbide) or amorphous Si
A structure close to C is likely to be formed, and such a local structure causes deterioration of crystal quality.

As described above, it is difficult to make Si _1-xy
A conventional method for producing a Ge _x C _y crystal is CV.
D (Chemical Vapor Deposition) method, gas source MB
E (Molecular Beam Epitaxy) method and solid source MB
A method called E (Molecular Beam Epitaxy) method has been used. Next, these methods and their problems will be described.

First, the CVD method and the gas source MBE method will be described. The CVD method and the gas source MBE method are the same crystal growth method in that the raw material gas is thermally decomposed on the substrate surface to perform crystal growth. Usually Si
_When growing a _1-xy Ge _x C _y crystal on a Si crystal,
With the Si substrate heated in a vacuum container, Si _1-xy G
SiH ₄ or Si, which is the raw material of Si that constitutes the e _x C _y crystal
A silane-based gas such as ₂ H ₆ , a GeH ₄ gas which is a raw material of Ge, and a gas containing C such as SiH ₃ CH ₃ or C ₂ H ₂ which is a raw material of C are simultaneously supplied into the vacuum container. But CV
Even in the D method and the gas source MBE method, C does not freely enter the crystal lattice position, and there is a certain limit value in the C content ratio in the lattice position. If this limit value is exceeded and C is attempted to be incorporated into the crystal, the quality of the Si _1-xy Ge _x C _y crystal will be significantly deteriorated. In particular, Si _1-xy Ge _x has no defects and high crystallinity so that it can be applied to semiconductor devices.
C _y crystal at present is that the C content can not be realized unless less about 2at.%.

Next, the solid source MBE method will be described.
It Si by solid source MBE method _1-xyGe_xC_y crystal
In the case of producing, Si, Ge,
Crystallized by irradiating the substrate with molecular beam generated by evaporation of C
Grow. Usually, the molecular beams of Si and Ge are Si and Ge.
Method of irradiating the crystal with electron beam or heating with a crucible
Generated by the method. On the other hand, for C, the graph
It is common to heat and evaporate the oxide into a molecular beam.
Is. Also in this solid source MBE method, the above-mentioned C
As in the VD method, when the Ge content is high, C is the lattice position.
It has been recently reported that it is difficult to enter (J.P. Liu a
nd H.J.Osten, Appl.Phys.Lett.76, 3546 (20
00)).

As described above, the CVD method using a gas as a raw material, the gas source MBE method, and the solid source MBE method using a solid material, which are often used for producing Si _1-xy Ge _x C _y crystals. In either case, if the Ge content is high, the C content that can enter the lattice position is low.

By the way, the inventors_1-xyGe_xC
_y Crystal, containing sufficient Ge for use as a semiconductor crystal film
Cause of difficulty in obtaining C and C content at the same time
As a result, the compatibility between Ge atoms and C atoms is poor, and
_1-xyGe_xC_y Maximum content of C in lattice position of crystal
Clearly the value changes depending on the Ge content
did. (Y.Kanzawa K.Nozawa, T.Saitoh and M.Kubo,
Appl.Phys.Lett.77, 3962 (2000)). Figure 1 shows UHV-
Single layer Si on Si substrate by CVD method_1-xyGe_xC
_yCan enter lattice positions when crystals are deposited
The maximum C content is plotted on the vertical axis and the Ge content is plotted on the horizontal axis.
It is the graph The raw material is Si ₂H₆gas,
GeH_FourGas, SiH₃CH₃ Substrate during growth using gas
Was 490 ° C. As you can see from Figure 1, an example
For example, Si having a Ge content of about 13 at.%_1-xy
Ge_xC_y The crystal has a C content of about 1.9 at.%.
Although it enters the lattice position, the Ge content is about 35 at.%
Is Si_1-xyGe_xC_y In the crystal, C is in the lattice position
Only about 0.8 at.% Can be entered. That is,
Si_{1 -xy}Ge_xC_yGe content increases in crystals
The higher the value, the lower the maximum value of C content in the lattice position.
It means to do.

The object of the present invention is to improve the solid solution limit of C due to the poor bonding property between Ge and C during the deposition of the Si _1-xy Ge _x C _y layer, and thus various An object of the present invention is to provide a method for manufacturing a semiconductor crystal film that can be used for manufacturing a semiconductor.

[0018]

A method for manufacturing a semiconductor crystal film according to the present invention comprises a substrate, at least one atomic layer of which is made of Si, G.
a step of epitaxially growing a crystal layer containing e and C, and a step of covering at least a part of the crystal layer containing Si, Ge and C with atomic hydrogen, and containing Si, Ge and C Is a method of epitaxially growing a crystal film.

By this method, the proportion of Ge atoms to which H atoms are attached among Ge atoms existing on the outermost surface of the substrate on which the crystal is growing is increased as compared with the conventional manufacturing method. When a H atom is attached to the Ge atom existing on the outermost surface of the crystal, a phenomenon occurs in which the Ge atom is replaced with Si existing in the lower layer. Therefore, in the production method of the present invention, compared with the conventional production method, Many Ge atoms are underlying Si
It will replace atoms. As a result, the proportion of Ge atoms among the atoms existing on the outermost surface of the substrate on which the crystal is grown is decreased, which increases the C content in the crystal film containing Si, Ge and C. Can be made.

In the above method for producing a semiconductor crystal film, a source gas containing silicon (Si), a source gas containing germanium (Ge) and a source gas containing carbon (C) are pyrolyzed. A crystal layer containing Si, Ge and C can be formed. At this time, monosilane (SiH ₄ ) and disilane (S) are used as the source gas containing silicon (Si).
i ₂ H ₆ ), dichlorosilane (SiH ₂ Cl ₂ ) or trisilane (Si ₃ H ₈ ) is used, and germanium (GeH ₄ ) is used as the source gas containing germanium (Ge). It is preferable to use monomethylsilane (SiH ₃ CH ₃ ) as the source gas containing (C).

In the above-mentioned method for producing a semiconductor crystal film, the above-mentioned substrate is irradiated with a molecular beam of Si, a molecular beam of Ge and a molecular beam of C generated by evaporation of solid Si, solid Ge and solid C, respectively. The above Si, Ge
A crystal layer containing C and C can also be formed.

In the method of manufacturing a semiconductor crystal film described above, after the process of epitaxially growing at least one atomic layer of the crystal layer containing Si, Ge and C on the substrate, the crystal containing Si, Ge and C is formed. At least a portion of the layer is covered with atomic hydrogen and then at least one atomic layer of Si, Ge and C is deposited.
The method may further include a step of epitaxially growing a crystal layer containing.

In the method of manufacturing a semiconductor crystal film described above, the step of epitaxially growing a crystal layer containing at least one atomic layer of Si, Ge and C and the step of supplying atomic hydrogen may be alternately repeated.

In the method of manufacturing a semiconductor crystal film described above,
Atomic hydrogen is supplied by at least one atomic layer of the above Si,
It can also be carried out simultaneously with the epitaxial growth of the crystal layer containing Ge and C.

The above atomic hydrogen can be generated by using plasma or filament.

[0026]

DETAILED DESCRIPTION OF THE INVENTION -Si _1-xy Ge _x C _y analysis of crystal growth process - we, the Si _1-xy Ge _x C _y layer, the C atoms higher the Ge content x One of the reasons why it is difficult to enter the crystal lattice position was considered as follows. Si
_The higher the Ge content _{x in the 1-xy} Ge _x C _y layer, the higher the Ge content of the atoms on the outermost surface where crystal growth occurs.
The proportion of atoms increases and the proportion of Si atoms decreases. Then, since the compatibility between C atoms and Ge atoms is worse than the compatibility between C atoms and Si atoms, the region where C atoms cannot bond increases in the outermost surface of the growing crystal. As a result, it is considered that when epitaxially growing the Si _1-xy Ge _x C _y layer, the amount of C that can enter the lattice position in the crystal is reduced.

On the other hand, in the Si _1-xy Ge _x C _y layer, when the proportion of Ge atoms is low and the proportion of Si is high among the atoms existing on the outermost surface of crystal growth, a new layer is formed on the outermost surface of crystal growth. When forming the Si _1-xy Ge _x C _y layer, C atoms can enter the lattice position of the crystal with a relatively high content rate. That is, Si ₁₋ having a high Ge content x
_{Even in the xy} Ge _x C _y layer, when growing a crystal, S
If the proportion of Ge atoms among the atoms existing on the outermost surface on which the i _1-xy Ge _x C _y layer is deposited can be reduced, then C can be reduced in the newly deposited Si _1-xy Ge _x C _y layer. It should be easy for atoms to enter.

Therefore, in the present invention, Si _1-xy Ge _x C _{y is used.}
As a method of reducing the proportion of Ge atoms among the atoms existing on the outermost surface of the substrate when growing a crystal, a source gas and atomic hydrogen are supplied onto the substrate to supply Si _1-xy.
A method of growing a Ge _x C _y crystal is proposed.

(First Embodiment) A method for manufacturing a semiconductor crystal film according to a first embodiment of the present invention will be described below with reference to FIG.
A description will be given with reference to (a) to (d) and FIGS. 3 (a) to (c). First, referring to FIGS. 2A to 2D, S
The process of epitaxially growing the i _1-xy Ge _x C _y layer will be described.

First, in the step shown in FIG. 2A, the Si substrate 11 on which crystal growth is to be performed is washed. Specifically, S
The i-substrate 11 is washed with a sulfuric acid-hydrogen peroxide water mixed solution, and S
Organic substances and metal contaminants on the surface of the i substrate 11 are removed.
Next, the Si substrate 11 is washed with an ammonia-hydrogen peroxide aqueous solution to remove the deposits on the surface of the Si substrate 11. Further, the natural oxide film on the surface of the Si substrate 11 is removed using a hydrofluoric acid solution. Finally, the Si substrate 11 is again immersed in the ammonia-hydrogen peroxide aqueous solution to form a thin protective oxide film on the surface of the Si substrate.

Next, the cleaned Si substrate 11 is introduced into the crystal growth apparatus. Then, the inside of the growth apparatus is once set to 2.6.
A vacuum is drawn to a pressure of about 10 ⁻⁷ Pa, and the Si substrate 11 is heated to a temperature of 850 ° C. in a vacuum or a hydrogen gas atmosphere. As a result, the Si substrate 11 is subjected to the cleaning process described above.
The protective oxide film formed on the surface is removed to expose the surface of the clean Si substrate 11. At this time, among the Si atoms 12 arranged on the outermost surface of the Si substrate 11, H atoms 13 are attached to a certain proportion of Si atoms, and other Si atoms do not bond with the H atoms 13 and The dangling bond is exposed.

Next, in a step shown in FIG. 2B, a Si _1-xy Ge _x C _y crystal is grown on the Si substrate 11. Specifically, the temperature of the surface of the Si substrate 11 is set to, for example, 490
In the state where the temperature is lowered to about 0 ° C., the source gas of the Si _1-xy Ge _x C _y crystal is supplied onto the upper surface of the Si substrate 11 to
Grow a crystal of about atomic layer. At this time, Ge atoms 15 are present on the outermost surface of the grown crystal at a ratio of about 100 x% (for example, about 30 at.%).
It can be considered that the i atom 16 is present in a proportion of about 100 (1-xy)% and the C atom 14 is present in a proportion of about 100y%. Moreover, H atoms 13 are attached to the atoms existing on the outermost surface of the substrate at a certain ratio. The conditions of the source gas and the partial pressure are Si ₂ H ₆ gas of about 9.1 × 10 ⁻³ Pa and GeH ₄ gas.
The gas is about 4.3 × 10 ^-2 Pa, and the SiH ₃ CH ₃ gas is 1.
It is about 7 × 10 ⁻³ Pa. Here, the crystal may be grown while keeping the ratio of the partial pressures of the source gases of Si, Ge and C constant, or may be grown while being changed.

Next, in the step shown in FIG. 2C, when atomic hydrogen is supplied onto the substrate after the source gas is supplied, almost all of the outermost surface of the substrate is covered with H atoms. At this time, the Ge atom on the outermost surface of the substrate is considered to be bonded to the H atom.

Here, the Ge atom 1 existing on the outermost surface of the substrate
Ge atom to which H atom is attached and its Ge
A phenomenon occurs in which Si atoms existing in the lower layer of the atoms are replaced with each other. The substrate temperature at this time is kept at 500 ° C. or lower, preferably 400 ° C. or lower. As an example of means for obtaining atomic hydrogen, there is a means for making hydrogen molecules into an atomic state by using a radical cell using a helicon wave plasma system,
In that case, the pressure for supplying atomic hydrogen is 6.5 ×
Set to about 10 ⁻⁴ Pa.

Next, in the step shown in FIG. 2D, Si ₂ H ₆ gas and GeH, which are source gases of the Si _{1-x- y} Ge _x C _y crystal, are formed on the substrate after the atomic hydrogen is supplied. ₄ gas, SiH ₃ CH
₃ Gas is supplied again, and atomic hydrogen is further supplied. Then, Ge contained in the newly formed outermost Si _1-xy Ge _x C _y layer moves to the lower layer. Here, since Ge moves to the lower layer in the state where the Ge composition ratio is lowered, it is considered that the Ge composition ratio of the lower layer is recovered to an average composition ratio of Si _1-xy Ge _x C _y crystals. To be From this, when the supply of the source gas of the Si _1-xy Ge _x C _y crystal and the supply of atomic hydrogen are repeated, a layer in which Ge is distributed almost uniformly except the outermost surface layer is formed.

By such a method, for example, in the conventional manufacturing method in which atomic hydrogen is not supplied, the Ge content is 3
C atoms can be mixed in only about 1.2 at.% At the lattice position of the Si _1-xy Ge _x C _y crystal of 0 at.
at the lattice position of the Si _1-xy Ge _x C _y crystal that is at.
It becomes possible to mix C atoms up to about 1.6 at.

Next, when atomic hydrogen is supplied, Si _1-xy
The reason why the content of C atoms in the lattice position of the Ge _x C _y crystal increases will be described in detail with reference to FIGS. 3A to 3C show growth of the Si _1-xy Ge _x C _y layer before and after exposure to atomic hydrogen in the growth process of the Si _1-xy Ge _x C _y crystal according to this embodiment. It is sectional drawing which shows a state. Note that FIGS. 3A to 3C
Then, for simplification, one atomic layer of Si is formed on the Si substrate 11.
Consider a state in which a _1-xy Ge _x C _y layer is deposited.

As shown in FIG. 3A, in the substrate to which the source gas is supplied but the atomic hydrogen is not supplied, the Si atoms 16 and the Ge atoms 15 existing on the outermost surface of the substrate are
The H atom 13 is attached with a certain probability. At this time, if the temperature of the substrate increases, the ratio of H atoms 13 attached decreases. Further, the H atom 13 is more Si than the Ge atom 15.
G that exists on the outermost surface of the substrate because it easily attaches to the atoms 12
It is considered that the proportion of Ge atoms to which the H atoms 13 are attached is low among the e atoms 15.

Therefore, in the step shown in FIG. 3B, when the atomic hydrogen is exposed on the substrate in the above-mentioned state, almost the entire outermost surface of the substrate is covered with the atomic hydrogen. As a result, Si atoms 16 and Ge atoms 15 existing on the outermost surface of the substrate
The ratio of Si atoms and Ge atoms to which the H atoms 13 are attached increases.

Then, in the step shown in FIG. 3C, when the substrate after being exposed to the atomic hydrogen is further subjected to heat treatment at a temperature lower than about 500 ° C., among Ge atoms 15 existing on the outermost surface of the substrate, A phenomenon occurs in which Ge atoms added with H atoms and Si atoms existing in the lower layer of the Ge atoms are replaced with each other. This is because under such conditions, the exchange of Ge atoms and Si atoms is more stable in terms of energy (Y. Kobayashi, K. Sumitomo, K. Sh.
iraishi, T.Urisu and T.Ogino, Surf.Sci. 436, 9
(1999)).

In FIG. 3C, all Ge atoms satisfying the above-mentioned conditions are replaced with Si atoms existing in the lower layer, but not all are necessarily replaced. Note that if atomic hydrogen is supplied to the substrate and then the temperature of the substrate is set to a temperature higher than 500 ° C., the H atoms attached to the outermost surface of the substrate are easily desorbed. Therefore,
By making the temperature lower than about 500 ° C., the outermost surface of the substrate can be more surely covered with H atoms, and the substitution of Ge atoms with Si atoms existing in the lower layer of the Ge atoms can be promoted.

As described above, when atomic hydrogen is supplied onto the substrate, H atoms are newly added to the atoms existing on the outermost surface of the substrate.
Of the atoms existing on the outermost surface of the substrate, H
The ratio of atoms to which the atoms 13 are attached is higher than that before the supply of atomic hydrogen. Therefore, G existing on the outermost surface of the substrate
The proportion of Ge atoms to which H atoms 13 are attached among the e atoms 15 also increases from before the atomic hydrogen was supplied. As a result, in the manufacturing method according to the present embodiment, as compared with the conventional manufacturing method in which atomic hydrogen is not exposed, Ge atoms are present in the lower layer of Si.
The probability of replacing atoms is high. Then, it is possible to reduce the proportion of Ge atoms among the atoms existing on the outermost surface of the substrate when the crystal source gas is supplied, and it is easy for C atoms supplied from the source gas to enter the crystal lattice positions. Become.

As described in the prior art, one of the major factors that makes it difficult for C atoms to enter the lattice position is the poor compatibility between C atoms and Ge atoms. However, in the method of manufacturing the semiconductor crystal film according to the present embodiment, Si _1-xy Ge _x
In the substrate for newly depositing the C _y layer, by moving Ge atoms that are incompatible with C atoms to the atomic layer existing below the atomic layer on the outermost surface, the Ge atomic density on the outermost surface is reduced, It is possible to increase the ratio of the lattice position C.

(Second Embodiment) Hereinafter, a method for manufacturing a semiconductor crystal film according to a second embodiment of the present invention will be described with reference to FIG.
A description will be given with reference to (a) to (c).

In this embodiment, among the atoms existing on the outermost surface of the substrate when growing the Si _1-xy Ge _x C _y layer, Ge
UHV-CV as a method of reducing the proportion of atoms
A method is used in which the source gas and atomic hydrogen are simultaneously supplied to the substrate to supply the Si _1-xy Ge _x C _y layer using the D method.

First, in the step shown in FIG. 4A, the Si substrate is subjected to pretreatment including cleaning treatment by the same method as that described in the first embodiment, and then the Si substrate is subjected to an ultrahigh vacuum. Is heated to expose the clean surface of the Si substrate 11.

Next, in the step shown in FIG. 4B, the temperature of the Si substrate 11 is lowered to a temperature of, for example, about 490 ° C., and the source gas and atomic hydrogen are simultaneously supplied onto the Si substrate 11. . The temperature at which the source gas and the atomic hydrogen are supplied is preferably about 500 ° C. or lower. By setting this temperature range, the growth of the Si _1-xy Ge _x C _y layer and the diffusion action of the Ge atoms to the lower layer can be simultaneously performed. The raw material gas and the pressure in the apparatus are about 9.1 × 10 ⁻³ Pa for Si ₂ H ₆ gas and 4.3 × 10 ⁻² for GeH ₄ gas.
The pressure is about Pa and the SiH ₃ CH ₃ gas is about 1.7 × 10 ⁻³ Pa. Atomic hydrogen is supplied at a pressure of about 6.5 × 10 ⁻⁴ Pa by atomizing H molecules using a radical cell using a helicon wave plasma system.

When crystal growth is performed in such a state, atomic hydrogen can always be supplied to the outermost surface of the substrate on which the crystal growth is occurring. It is possible to keep the ratio of H atoms adhering to the hydrogen atoms higher than that in the conventional manufacturing method in which atomic hydrogen is not supplied. Therefore, Ge existing on the outermost surface
The proportion of Ge atoms to which H atoms are attached also increases among the atoms. As a result, a larger proportion of Ge atoms than in the conventional manufacturing method replaces Si atoms existing in the lower layer of the Ge atoms.

Then, in the step shown in FIG. 4C, the source gas and atomic hydrogen are simultaneously supplied onto the substrate until a predetermined film thickness is obtained.

Through the above steps, in the present embodiment, the proportion of Ge atoms among the atoms on the outermost surface of the substrate on which crystal growth is occurring is reduced in comparison with the conventional manufacturing method. Since the occupying ratio increases, C atoms easily enter the crystal lattice position. As a result, Si _1-xy G
The proportion of the lattice position C in the e _x C _y layer can be increased.

(Third Embodiment) Hereinafter, a method for manufacturing a semiconductor crystal film according to a third embodiment of the present invention will be described with reference to FIG.
A description will be given with reference to (a) to (d).

In this embodiment, among the atoms existing on the outermost surface of the substrate when growing the Si _1-xy Ge _x C _y layer, Ge
As a method of reducing the proportion of atoms, a method of growing a Si _1-xy Ge _x C _y layer by using a solid source MBE method and alternately supplying molecular beams of Si, Ge, and C and atomic hydrogen is proposed. To do.

First, the step shown in FIG. 5A, that is, the first step
In the process similar to the process described in the above embodiment, the Si substrate 11
After performing a pretreatment including a cleaning treatment, the Si substrate 11 is heated in an ultrahigh vacuum to expose the clean surface of the Si substrate 11.

Next, in the step shown in FIG. 5B, with the temperature of the Si substrate 11 being lowered to a temperature of, for example, about 400 ° C., molecular beams of Si, Ge and C are formed on the Si substrate 11. Irradiating the substrate, one atomic layer of Si _1-xy Ge _x C
Grow the _y- layer. At this time, the Si molecular beam and the Ge molecular beam are generated by, for example, irradiating the Si crystal and the Ge crystal with electron beams and evaporating. On the other hand, the molecular beam of C is generated by, for example, electrically heating a graphite filament and evaporating it. According to such a solid source MBE method, Si _1-xy Ge _x C _y can be obtained even at a low temperature.
The advantage is that layers can be grown.

Next, in the step shown in FIG. 5C, Si and G
Atomic hydrogen is exposed on the substrate after the supply of the molecular beams of e and C is stopped. Atomic hydrogen is generated using, for example, a radical cell using a helicon wave plasma system. Here, by exposing the atomic hydrogen onto the substrate, the ratio of the atoms to which hydrogen is attached among the atoms on the outermost surface where the crystal is growing is increased. As a result, more Ge atoms are replaced with the underlying Si than in the conventional manufacturing method.

Thereafter, in the step shown in FIG. 5D, the supply of the molecular beam of Si, Ge, C onto the substrate and the supply of atomic hydrogen are repeated until a predetermined film thickness is obtained.

Through the above steps, in the present embodiment, the proportion of Ge atoms among the atoms on the outermost surface of the substrate on which crystal growth is occurring is reduced, and conversely, Si atoms are reduced in comparison with the conventional manufacturing method. Since the occupying ratio increases, C atoms easily enter the crystal lattice position. As a result, Si _1-xy G
The proportion of the lattice position C in the e _x C _y layer can be increased.

(Fourth Embodiment) A method for manufacturing a semiconductor crystal film according to a fourth embodiment of the present invention will be described below.

In this embodiment, among the atoms existing on the outermost surface of the substrate when growing the Si _1-xy Ge _x C _y layer, Ge
As a method of reducing the proportion of atoms, a method of growing a Si _{1-x- y} Ge _{x Cy} layer by using a solid source MBE method and simultaneously supplying a molecular beam of Si, Ge, and C and atomic hydrogen To use.

First, in a step similar to the step described in the first embodiment, the Si substrate is subjected to pretreatment including cleaning treatment, and then the Si substrate is heated in an ultrahigh vacuum to clean the surface of the Si substrate. Expose.

Next, with the temperature of the substrate lowered to, for example, about 400 ° C., the molecular beams of Si, Ge and C and atomic hydrogen are simultaneously exposed on the substrate, and 1 An atomic layer of Si _1-xy Ge _x C _y layer is grown. At this time, the Si molecular beam and the Ge molecular beam are generated by, for example, irradiating the Si crystal and the Ge crystal with electron beams and evaporating. On the other hand, the molecular beam of C, for example, electrically heats a graphite filament,
It is generated by evaporation. Atomic hydrogen is, for example,
It is generated using a radical cell using the helicon wave plasma method. When the Si _1-xy Ge _x C _y layer is grown in this manner, atomic hydrogen is always supplied to the outermost surface on which the crystal is growing, so that among the atoms on the outermost surface on which the crystal is growing, The proportion of atoms to which hydrogen is attached can be kept high. As a result, more Ge atoms can replace the underlying Si than in the conventional manufacturing method.

Thereafter, the molecular beams of Si, Ge, and C and atomic hydrogen are simultaneously supplied onto the substrate until a predetermined film thickness is obtained.

Through the above steps, in the present embodiment, the proportion of Ge atoms among the atoms on the outermost surface of the substrate on which crystal growth is occurring is reduced, and conversely, Si atoms are changed, as compared with the conventional manufacturing method. Since the occupying ratio increases, C atoms easily enter the crystal lattice position. As a result, Si _1-xy G
The proportion of the lattice position C in the e _x C _y layer can be increased.

(Other Embodiments) In the first and second embodiments, as a method for growing a crystal, UHV-
Although the CVD method is used, in the present invention, another CVD method such as the LP-CVD method may be used, and an MBE method of a gas source that suppresses the partial pressure of the raw material gas may be used.

Further, in the first and second embodiments, the above Si ₂ H ₆ was used as the source gas, but in the present invention, SiH ₄ , SiH ₂ Cl ₂ , Si ₃ H ₈ is used instead. Good.

In the third and fourth embodiments, Si and G are used.
Although the method of irradiating the electron beam is used to generate the molecular beam of e, a method of heating the crucible with a heater may be used.

In addition, in the first to fourth embodiments, Si _1-xy Ge _x C _y is grown until atomic hydrogen is supplied.
As described above, the layer may be at least one atomic layer, and in the present invention, it may be at least one atomic layer, and may be several atomic layers. That is, the process of growing several atomic layers and the process of covering with atomic hydrogen may be repeated alternately.

Further, in the first to fourth embodiments, Si
Although the case of growing the Si _1-xy Ge _x C _y layer directly on the substrate has been described, in the present invention, the Si substrate and the Si _1-xy Ge _x C _y layer are grown.
A buffer layer made of Si or Si _1-x Ge _x may be interposed between the layer and the C _y layer.

Further, in the first to fourth embodiments, the method of using the radical cell using the helicon wave plasma system has been described as the method of generating atomic hydrogen.
In the present invention, pyrolysis by filament heating may be used.

In addition, in the first to fourth embodiments, when the atomic hydrogen is exposed and then the substrate temperature is maintained, Ge to which atomic hydrogen adheres and Si located below the atomic hydrogen are exchanged. Stated. However, in the present invention, it is not necessary to make a clear distinction between the time of exposing the atomic hydrogen and the time of the above-mentioned replacement.

In addition, in the first to fourth embodiments,
The case of growing the Si _1-xy Ge _x C _y layer on the Si layer has been described, but in the present invention, it may be grown on a layer other than the Si layer such as the Si _1-x Ge _x layer. .

Further, in the first and third embodiments, the case where hydrogen molecules are decomposed into atomic hydrogen outside the crystal growth apparatus has been described, but in the present invention, hydrogen is generated inside the crystal growth apparatus. The molecule may be decomposed to supply atomic hydrogen. For example, in the first embodiment, after the supply of the raw material gas for the Si _1-xy Ge _x C _y crystal is stopped in the step shown in FIG. 2B, the process is performed in the apparatus in the step shown in FIG. 2C. Atomic hydrogen may be generated by decomposing hydrogen molecules using a filament or the like.

The conditions for carrying out the present invention are not limited to the conditions (for example, gas species, pressure, temperature, etc.) described in the first to fourth embodiments.

[0074]

According to the present invention, Si _1-xy Ge _x containing a high proportion of lattice positions C while having a high Ge content.
It enables the production of the C _y layer.

[Brief description of drawings]

FIG. 1 Si _1-xy produced by a conventional manufacturing method
It is the graph which plotted the maximum value of C content rate which can enter into the lattice position in the Ge _x C _y layer on the vertical axis, and plotted the Ge content rate on the horizontal axis.

2A to 2D are cross-sectional views showing a manufacturing process of the semiconductor crystal film according to the first embodiment.

3A to 3C are cross-sectional views showing a process before and after exposing the substrate to atomic hydrogen in the process of manufacturing the semiconductor crystal film according to the first embodiment.

4A to 4C are cross-sectional views showing a manufacturing process of a semiconductor crystal film according to a second embodiment.

5A to 5D are cross-sectional views showing a method for manufacturing a semiconductor crystal film according to a third embodiment.

[Explanation of symbols]

11 Si substrate 12 Si atom 13 H atom 14 C atom 15 Ge atom 16 Si atom

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI H01L 21/203 H01L 21/203 M 21/324 21/324 P (72) Inventor Minoru Kubo 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita (56) Reference JP 2000-351694 (JP, A) JP 2000-269476 (JP, A) JP 11-329973 (JP, A) JP 9-278597 (JP , A) JP 7-22330 (JP, A) JP 64-15912 (JP, A) JP 6-326030 (JP, A) JP 7-273041 (JP, A) JP 9-82637 (JP, A) JP-A-2-260666 (JP, A) JP-A-10-256158 (JP, A) JP-A-6-151313 (JP, A) JP-A-11-251248 (JP, A) JP-A-8-162409 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/205 C30B 23/08 C30B 25/02 C30B 29/52 H01L 21/20 H01L 21/203 H01L 21/324

Claims (8)

(57) [Claims] 1. A substrate comprising at least one atomic layer of Si,
A semiconductor crystal film, comprising: a step of epitaxially growing a crystal layer containing Ge and C; and a step of covering at least a part of the crystal layer containing Si, Ge and C with atomic hydrogen. Manufacturing method. 2. The method for producing a semiconductor crystal film according to claim 1, wherein a source gas containing silicon (Si), a source gas containing germanium (Ge), and a source gas containing carbon (C). A method for producing a semiconductor crystal film, characterized in that the crystal layer containing Si, Ge and C is formed by thermally decomposing and. 3. The method for producing a semiconductor crystal film according to claim 1, wherein a Si molecular beam, a Ge molecular beam and a C molecular beam generated by evaporation of solid Si, solid Ge and solid C are generated. By irradiating the substrate, the Si, Ge and C
A method for producing a semiconductor crystal film, which comprises forming a crystal layer containing: 4. The method for producing a semiconductor crystal film according to claim 1, wherein a crystal layer containing at least one atomic layer of Si, Ge and C is epitaxially grown on the substrate. After the step of performing, a step of covering at least a part of the above-mentioned crystal layer containing Si, Ge and C with atomic hydrogen is performed, and thereafter, a crystal layer containing at least one atomic layer of Si, Ge and C. 2. A method for manufacturing a semiconductor crystal film, further comprising the step of epitaxially growing. 5. The method for producing a semiconductor crystal film according to claim 4, comprising a step of epitaxially growing a crystal layer containing at least one atomic layer of Si, Ge and C, and a step of supplying atomic hydrogen. A method for manufacturing a semiconductor crystal film, characterized in that the method is repeated alternately. 6. The method for producing a semiconductor crystal film according to claim 1, wherein the atomic hydrogen is supplied by at least one atomic layer of Si,
A method for producing a semiconductor crystal film, which is characterized in that it is repeated simultaneously with epitaxial growth of a crystal layer containing Ge and C. 7. The method for producing a semiconductor crystal film according to claim 2, wherein the source gas containing silicon (Si) is:
Monosilane (SiH ₄ ), disilane (Si ₂ H ₆ ), dichlorosilane (SiH ₂ Cl ₂ ) or trisilane (S
i ₃ H ₈ ) and the above germanium (Ge)
A method for manufacturing a semiconductor crystal film, wherein germane (GeH ₄ ) is used as the source gas containing C, and monomethylsilane (SiH ₃ CH ₃ ) is used as the source gas containing the carbon (C). 8. The method for producing a semiconductor crystal film according to claim 1, wherein the atomic hydrogen is generated by using plasma or a filament. TECHNICAL FIELD The present invention relates to a method for producing a semiconductor crystal film having a crystal film containing Si, Ge and C.