JP2014192382A - Semiconductor device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply form a non-metal Ge compound layer of Sr or Ba at a boundary face between a Ge-based semiconductor region and an insulation film to achieve reduced manufacturing cost and improved electrical characteristics of a semiconductor device.SOLUTION: A semiconductor device manufacturing method comprises: a process of forming an oxide film 12 containing Sr or Ba on a Ge-based semiconductor region 11; a process of forming a metal film 13 on the oxide film 12; a process of performing a heat treatment to form a metal oxide film 23 by oxidizing the metal film 13 by oxygen in the oxide film 12 and form an Sr film 22 or a Ba film by reducing the oxide film 12; a process of reacting the Sr film 22 or the Ba film with the semiconductor region 11 to form a non-metal compound layer 32; and a process of forming a gate electrode 15 on the metal oxide film 23.

Description

  The present invention relates to a method for manufacturing a semiconductor device having a nonmetallic compound layer of Sr or Ba on a semiconductor region containing Ge as a main component.

  One technical problem of Ge-MIS (Metal Insulator Semiconductor) devices is thermal instability at the interface between the insulator and the Ge substrate. In particular, the problem is that the reducing gas GeO is degassed from the interface. Along with this degassing, there are concerns about deterioration of interface characteristics and further reduction of mobility.

  As one of the solutions, it has been reported that mixing N or Zr with interfacial Ge oxide increases the thermal stability of the interface and can suppress degassing (see Non-Patent Document 1). However, this method has poor interface characteristics and low mobility due to the influence of the Ge oxide.

As another solution, a method in which a thermally unstable Ge oxide is not formed at the insulating film / Ge interface has been studied. For example, interfacial Ge oxide layer formation is suppressed by a method of forming Ge ₃ N ₄ by plasma nitriding (see Non-Patent Document 2) or a method of forming a Si cap layer on a Ge substrate (see Non-Patent Document 1). A method is being considered.

  However, plasma nitridation can form a fresh reaction interface and is expected to improve interface characteristics, but there is a concern that mobility deteriorates as nitrogen is introduced into the interface. The formation of the Si cap layer includes the deterioration of mobility due to crystal defects caused by lattice multiplier mismatch at the Si / Ge interface, the Ge diffusion to the insulating film / Si interface and the formation of the Ge oxide interface layer, and the insulating film / There is concern about deterioration of substrate interface characteristics.

  On the other hand, it has been reported that a non-oxide and non-metal strontium-germanium compound (SrGex) functions well as an interface layer of an insulating film / Ge interface in a MIS device (see Patent Document 1). However, in device fabrication, a metal Sr that is highly reactive in the atmosphere is used, so an ultrahigh vacuum is basically required, and device fabrication takes time. For this reason, a simple device fabrication process has been desired.

JP 2010-67929 A

Kamata, Y., Materials Today (2008) 11, 30 Takagi, S., et al., Microelectron. Eng. (2007) 84, 2314

  The present invention has been made in view of the above circumstances, and the object of the present invention is to easily provide a non-metallic compound layer of Sr or Ba at the interface between a semiconductor region mainly containing Ge and an insulating film. It is an object of the present invention to provide a method for manufacturing a semiconductor device, which can be formed in a continuous manner and can contribute to a reduction in manufacturing cost of a semiconductor device and an improvement in electrical characteristics.

  A method for manufacturing a semiconductor device according to one embodiment of the present invention includes a step of forming an oxide film containing Sr or Ba over a semiconductor region containing Ge as a main component, and a step of forming a metal film over the oxide film. And a step of performing heat treatment after forming the metal film to oxidize the metal film with oxygen in the oxide film to form a metal oxide film and reducing the oxide film to form an Sr film or a Ba film. And a step of reacting the Sr film or Ba film with the semiconductor region to form a nonmetallic compound layer, and a step of forming a gate electrode on the metal oxide film.

  The method for manufacturing a semiconductor device according to another aspect of the present invention includes a step of forming an oxide film containing Sr or Ba over a semiconductor region containing Ge as a main component, and a metal film over the oxide film. Forming a protective insulating film for suppressing oxidation of the metal film on the metal film, and performing a heat treatment after forming the protective insulating film, and the metal film in the oxide film Forming a metal oxide film by oxidizing with oxygen, reducing the oxide film to form an Sr film or Ba film, and reacting the Sr film or Ba film with the semiconductor region to form a nonmetallic compound layer And forming a gate electrode on the protective insulating film or on the metal oxide film after removing the protective insulating film.

  According to still another aspect of the present invention, there is provided a method for manufacturing a semiconductor device comprising: forming an oxide film containing Sr or Ba on a semiconductor region containing Ge as a main component; and forming a metal film on the oxide film. Forming a protective insulating film for suppressing oxidation of the metal film on the metal film, forming a gate electrode on the protective insulating film, and forming the gate electrode A step of performing heat treatment later to oxidize the metal film with oxygen in the oxide film to form a metal oxide film, and reduce the oxide film to form an Sr film or Ba film; and the Sr film or Ba And a step of reacting the film with the semiconductor region to form a nonmetallic compound layer.

  In the method for manufacturing a semiconductor device according to the present invention, an oxide film containing Sr or Ba is formed by a film forming apparatus that does not require an ultra-high vacuum apparatus, and this oxide film is reduced by reaction with a metal to reduce Sr or Ba. By generating, a nonmetallic compound layer with Sr or Ba can be formed on the semiconductor region containing Ge as a main component. Accordingly, it is possible to improve the electrical characteristics of the semiconductor device, reduce the time required for device fabrication, and reduce the cost required for device fabrication.

Sectional drawing which shows the manufacturing process of the semiconductor device concerning 1st Embodiment. Sectional drawing which shows the manufacturing process of the semiconductor device concerning 2nd Embodiment. Sectional drawing which shows the manufacturing process of the semiconductor device concerning 3rd Embodiment. The figure which shows the XPS-Hf4f spectrum of each gate stack before heat processing. The figure which shows the XPS-Hf4f spectrum of each gate stack before heat processing. FIG. 3 is a schematic diagram illustrating a gate stack structure of a semiconductor device. The figure which is for demonstrating 4th Embodiment, and shows the XPS-Hf4f spectrum of each gate stack before heat processing and after heat processing. The figure which is for demonstrating 4th Embodiment, and shows the XPS-Hf4f spectrum of each gate stack before heat processing and after heat processing. The figure which is for demonstrating 4th Embodiment, and shows the XPS-Hf4f spectrum of each gate stack before heat processing and after heat processing. The figure which is for demonstrating 4th Embodiment, and shows the XPS-Hf4f spectrum of each gate stack before heat processing and after heat processing. The figure which is for demonstrating 4th Embodiment, and shows the XPS-Hf4f spectrum of each gate stack before heat processing and after heat processing. The figure which shows the XPS-Hf4f spectrum of each gate stack at the time of changing heat processing temperature. The figure which shows the gate leak current density (Jg) -gate voltage (Vg) characteristic of a MIS capacitor. The figure which shows the capacity | capacitance (C) -gate voltage (Vg) characteristic of a MIS capacitor. For the purpose of describing a modified example of the present invention, the strontium oxide is deposited by sputtering shows an XPS of Sr ₃ d peak in the case of heat treatment Fig.

  Embodiments of the present invention will be described below with reference to the drawings.

  In addition, the same code | symbol shall be attached | subjected to a common structure through each embodiment, and the overlapping description is abbreviate | omitted. Each figure is a schematic diagram for promoting explanation and understanding of the invention, and its shape, dimensions, ratio, and the like are different from those of an actual device. However, these are in consideration of the following explanation and known techniques. The design can be changed as appropriate.

(First embodiment)
FIG. 1A to FIG. 1E are cross-sectional views showing manufacturing steps of the MIS device according to the first embodiment.

First, as shown in FIG. 1A, an SrO film 12 is deposited on a pretreated Ge substrate (semiconductor region) 11 by sputtering using a strontium peroxide (SrO ₂ ) target or a strontium oxide target. Then, an Hf film 13 is formed on the deposited SrO film 12 by sputtering using an Hf target.

Next, heat treatment causes oxygen in the SrO film 12 as an oxide film to move to the Hf film 13 as a metal film, reducing SrO and oxidizing Hf. As a result, as shown in FIG. 1B, an Sr film 22 and an HfO ₂ film (metal oxide film) 23 are formed. Here, in order to improve the insulating properties of HfO ₂ , heat treatment in an oxygen atmosphere or plasma treatment containing oxygen may be appropriately added.

Next, as shown in FIG. 1C, the Sr film 22 is reacted with the Ge substrate 11 to form a strontium-germanium compound (SrGex, x is arbitrary) film 32 as a nonmetallic compound layer. Here, the formation of SrGex following the reduction of SrO may be performed in the above order, or may proceed simultaneously. SrGex is preferably composed of a combination of stable compositions SrGe ₂ , SrGe, Sr ₂ Ge, Sr ₄ Ge _3, and the crystallinity is preferably amorphous. Furthermore, part or all of Sr may be replaced with Ba.

  Next, as shown in FIG. 1D, a TaN film 15 as a gate electrode is formed by sputtering using a Ta target in an argon and nitrogen atmosphere. Thereby, a gate stack of the MIS device is manufactured.

  Next, as shown in FIG. 1E, the gate stack is processed into a gate pattern, and source / drain regions (not shown) are formed on both sides of the gate pattern by using ion implantation or the like, whereby a field effect transistor is formed. (FET) will be completed.

  The source / drain region is not limited to ion implantation, and the source / drain may be formed by a metal / semiconductor junction that does not use ion implantation, a so-called Schottky junction. For example, Ni may react with Ge at 350 ° C. to form a NiGe compound, and this NiGe / Ge junction may be used as the source / drain of a Ge p-channel FET. Further, a combination of ion implantation and Schottky junction, for example, one in which conductive impurities are segregated at the metal / semiconductor interface may be used for the source / drain regions.

  As described above, according to the present embodiment, the SrO film 12 is formed by a film forming apparatus that does not require an ultrahigh vacuum apparatus, and this is reduced, so that film formation in an ultrahigh vacuum is not required. A metal Sr film 22 can be generated. Then, by reacting the metal Sr and the Ge substrate, the SrGex film 32 as a non-metallic compound layer containing Ge can be formed. Accordingly, the time required for manufacturing the MIS device can be shortened and the device manufacturing cost can be reduced as compared with the method of forming the Sr film in an ultrahigh vacuum as well as improving the electrical characteristics of the semiconductor device. Can be reduced.

(Second Embodiment)
FIGS. 2A to 2D are cross-sectional views showing the manufacturing process of the MIS device according to the second embodiment. In addition, the same code | symbol is attached | subjected to FIG. 1 (a)-the same part as (e), and the detailed description is abbreviate | omitted.

First, as shown in FIG. 2A, as in the first embodiment, the SrO film 12 is deposited on the pretreated Ge substrate 11, and the Hf film 13 is formed on the deposited SrO film 12. To do. Then, an Al ₂ O ₃ film (protective insulating film) 14 as a cap layer is formed on the Hf film 13 by sputtering using an Al ₂ O ₃ target.

Next, as shown in FIG. 2B, heat treatment moves oxygen in the SrO film 12 to the Hf film 13 to reduce SrO and oxidize Hf. Thereby, as shown in FIG. 2B, the Sr film 22 and the HfO ₂ film 23 are formed. Then, as shown in FIG. 2C, the SrGex film 32 is formed by reacting the Sr film 22 with the Ge substrate 11.

  Next, as shown in FIG. 2D, a TaN film 15 as a gate electrode is formed by sputtering using a Ta target in an argon and nitrogen atmosphere. Thereby, a gate stack of the MIS device is manufactured.

  Thereafter, as in the first embodiment, the field effect transistor (FET) is completed by processing the gate stack into a gate pattern and forming source / drain regions using ion implantation or the like. .

As described above, according to the present embodiment, similarly to the first embodiment, the metal Sr film 22 is generated on the Ge substrate 11 without forming a film in an ultrahigh vacuum. An SrGex film 32 can be formed at the interface with the HfO ₂ film 23. Therefore, the same effect as the first embodiment can be obtained. Further, by providing the cap layer 14, it is possible to suppress oxidation from the surface of the Hf film 13, and there is an advantage that the SrO film 12 can be sufficiently reduced even if the Hf film 13 is thinned.

(Third embodiment)
FIGS. 3A to 3C are cross-sectional views showing manufacturing steps of the MIS device according to the third embodiment. In addition, the same code | symbol is attached | subjected to FIG. 1 (a)-the same part as (e), and the detailed description is abbreviate | omitted.

First, as shown in FIG. 3A, as in the first embodiment, the SrO film 12 is deposited on the pretreated Ge substrate 11, and the Hf film 13 is formed on the deposited SrO film 12. To do. Then, an Al ₂ O ₃ film (protective insulating film) 14 as a cap layer is formed on the Hf film 13 by a sputtering method using an Al ₂ O ₃ target. A TaN film 15 as a gate electrode is formed by sputtering in a nitrogen atmosphere. Thereby, a gate stack of the MIS device is manufactured.

Next, heat treatment moves oxygen in the SrO film 12 to the Hf film 13 to reduce SrO and oxidize Hf. Thereby, as shown in FIG. 3B, the Sr film 22 and the HfO ₂ film 23 are formed. Then, as shown in FIG. 3C, the SrGex film 32 is formed by reacting the Sr film 22 with the Ge substrate 11.

  Thereafter, as in the first embodiment, the field effect transistor (FET) is completed by processing the gate stack into a gate pattern and forming source / drain regions using ion implantation or the like. .

As described above, according to the present embodiment, similarly to the first embodiment, the metal Sr film 22 is generated on the Ge substrate 11 without forming a film in an ultrahigh vacuum. An SrGex film 32 can be formed at the interface with the HfO ₂ film 23. Accordingly, the same effect as that of the first embodiment can be obtained, and the same effect as that of the second embodiment can also be obtained by providing the cap layer 14.

(Explanation on gate stack fabrication)
Hereinafter, the gate stack fabrication in the processes of the first to third embodiments will be described in more detail.

The desired structure is a structure in which the interface in contact with the Ge substrate is a compound SrGex layer of Sr and Ge, and the upper metal Hf is completely oxidized to become HfO ₂ . The process challenge for making this structure is that there is a sufficient amount of Hf to reduce SrO. In principle, even if Hf remains on the electrode side, it can be used as an electrode, that is, a TaN / Hf / HfO ₂ / SrGex / Ge gate stack structure is also possible.

  First, the oxidation of Hf will be described. Factors that oxidize Hf include those caused by oxygen in SrO, those caused by oxygen in the atmosphere, and moisture. Therefore, in order to reduce SrO, it is necessary to form a sufficient amount of Hf in consideration of surface oxidation, or to form a cap layer for suppressing Hf from oxidizing from the surface.

  Therefore, the oxidation of Hf during the Hf film formation was examined. FIG. 4 is a diagram showing the chemical bonding state of Hf4f in the X-ray photoelectron spectroscopy (XPS) analysis immediately after the stack formation (as-depo) in FIG. FIG. 5 is a view showing the chemical bonding state of XPS-Hf4f including the case where the cap layer is formed as shown in FIG.

Note that A to E in FIG. 5 correspond to the stack structure of FIGS. In FIG. 6, (a) is Hf: 2 nm / SrO: 1 nm / Ge, (b) is Al ₂ O ₃ : 1 nm / Hf: 2 nm / SrO: 1 nm / Ge, and (c) is HfO ₂ : 1 nm / Hf: 2 nm / SrO: 1 nm / Ge, (d) is Al ₂ O ₃ : 2 nm / Hf: 2 nm / SrO: 1 nm / Ge, (e) is Al ₂ O ₃ : 1 nm / Hf: 3 nm / SrO: 1 nm / Ge is there.

  From FIG. 4, when attention is paid to the difference between the Hf-Hf regions where the Hf amounts are 1 nm and 2 nm, it can be seen that Hf: 1 nm is almost entirely oxidized during as-depo, but if the film is formed to 2 nm, Hf metal remains. Further, when the amount of Hf—Hf of Hf: 2 nm / SrO: 0.2 nm / Ge of FIG. 4 and Hf: 2 nm / SrO: 1 nm / Ge of FIG. 5 is compared, SrO is 0.8 nm thicker than 0.2 nm and 1 nm. In this case, it is noted that Hf−Hf disappears. This suggests that O in SrO oxidizes Hf immediately after Hf deposition and is reduced itself to Sr. It is known that the Hf-O component is detected even when the interface with the Ge substrate is deeper than the XPS photoelectron escape depth, that is, even when the Hf is thick, so that Hf is also oxidized from the surface.

As a cap layer for suppressing the surface oxidation of Hf that reduces SrO, HfO ₂ or Al ₂ O ₃ can be used. As shown in FIG. 5, when HfO ₂ and Al ₂ O ₃ are deposited on 1 nm and Hf, respectively, HfO ₂ remains a little, and Al ₂ O ₃ is almost oxidized. However, it is possible to leave Hf by increasing the thickness of Al ₂ O ₃ to 2 nm. Furthermore, it is possible to increase the remaining amount of Hf metal by increasing the thickness of Hf from 2 nm to 3 nm.

  As the cap layer, other insulating films such as zirconium oxide, tantalum oxide, titanium oxide, lanthanum oxide, and silicon oxide can be used. Furthermore, an oxynitride or nitride in which at least a part of these oxygens is replaced with nitrogen may be used.

  The above is summarized as follows. Hf reduces the underlying SrO immediately after deposition, but simultaneously oxidizes from the surface.

Hf + 2SrO → HfO ₂ + Sr (1)
Therefore, considering reaction formula (1), SrO that can be reduced with 1 mol of Hf is 2 mol. Therefore, when Hf is 0.5 mol relative to 1 mol of SrO, SrO can be reduced exactly, and when it is 0.5 mol or less, SrO remains, and when it is 0.5 mol or more, Hf remains. Since the Hf residue can be oxidized by additional heat treatment or plasma treatment in an atmosphere containing oxygen, it is preferable to deposit Hf in an amount sufficient to reduce SrO and oxidize the Hf residue.

The densities of SrO and Hf are 4.7 (g / cm ³ ) and 13.31 (g / cm ³ ), respectively, and the atomic weights of Sr, O, and Hf are 87.62 (g / mol) and 16.0 (g, respectively). / Mol), 178.49 (g / mol), SrO contains 5.364e ⁻⁹ (mol) of Sr in 1 nm × 1 cm ² and Hf is 7.457e ⁻⁹ (1 nm × 1 cm ^2. mol). Therefore, in principle, in order to reduce 1 nm of SrO, 0.36 nm (= 5.364e ⁻⁹ /2/7.457e ⁻⁹ ) of Hf is necessary.

  As described above, since the surface is oxidized by about 1.6 nm (= 2−0.36), when there is no cap layer and the SrO film thickness is T1 (nm), Hf is 0.36 × T1 + 1.6 ( nm) or more. When there is a cap layer, the oxidation suppression film thickness by the cap layer is set to T2 (this can be evaluated from XPS or a cross-sectional TEM image, for example), and 0.36 × T1 + 1.6−T2 (nm) or more is required.

In consideration of surface oxidation, a cap layer may be formed on the Hf surface until at least SrO is reduced. Since the gate insulating film needs to be thin to some extent, the cap layer may be removed after the SrO reduction. , For example, Al ₂ O ₃ capping layer on the HfO ₂ can be removed selectively with respect to the underlying HfO ₂ with hydrochloric acid solution. Further, an insulating film such as HfO ₂ may be added after the SrO reduction.

(Fourth embodiment)
This embodiment is basically the same as the first to third embodiments, but is characterized in that the heat treatment temperature when heat treating the SrO film 12 is changed between 300 ° C. and 700 ° C. . Note that a temperature exceeding 700 ° C. is undesirable because it adversely affects Ge as a base substrate.

  Although it has been described above that SrO is reduced immediately after Hf deposition, it is not clear whether all of it is reduced. Therefore, in the case of the structure in which the metal Hf remains, the result of XPS examining the temperature at which the metal Hf is oxidized by heat treatment, that is, the temperature at which SrO is reduced is shown below.

  The XPS-Hf4f spectra of the samples (a) to (e) in FIG. 6 that were heat-treated at 300, 500, and 700 ° C. for 1 minute in a nitrogen atmosphere immediately after film formation are shown in FIGS. 6A corresponds to FIG. 7, FIG. 6B corresponds to FIG. 8, FIG. 6C corresponds to FIG. 9, FIG. 10D corresponds to FIG. 10, and FIG. Each graph is as-depo, 300 ° C, 500 ° C, 700 ° C. From these spectra, it can be seen that heat treatment at a temperature higher than 300 ° C., for example, 500 ° C. or higher is required to oxidize Hf, that is, reduce SrO. Since the temperature region is a temperature region where metal strontium and germanium react, the reduced strontium immediately reacts with germanium to form SrGex.

  The heat treatment temperature was examined in more detail. FIG. 12 (a) shows XPS for the case where the system of Hf: 2 nm / SrO: 0.2 nm / Ge was heat-treated in an oxygen atmosphere at temperatures of 250, 350, 450, and 550 ° C. for 1 minute, and the case of as-depo. It is the figure which compared -Hf4f spectrum. It can be seen that the metal Hf component remains up to 450 ° C., but the metal Hf component disappears at 550 ° C. This result is a result that compensates for the above result, and as a result, the oxidation of the metal Hf does not proceed up to 450 ° C., and all is oxidized at 500 ° C. or higher. However, this temperature region is dependent on the atmosphere. Although the above examined the heat treatment temperature dependence in an oxygen atmosphere, FIG. 12B shows a comparison of Hf4f spectra when the atmosphere is changed to oxygen, nitrogen, and hydrogen at 450 ° C. In the oxygen atmosphere, the metal Hf component remains as described above, but it can be seen that all the metal Hf is oxidized in the nitrogen and hydrogen atmosphere. This can be understood by considering the following two reaction equations.

Hf + 2SrO → HfO ₂ + Sr (1)
Hf + O ₂ → HfO ₂ (2)
Although there is HfO ₂ on the right side in the reaction formula (1), when the reaction formula (2) proceeds to the right, this corresponds to an increase in HfO ₂ in the reaction formula (1). ) Increases the amount of ingredients that progress to the left. That is, since oxygen is supplied from the atmosphere in the heat treatment to the Hf / SrO interface and Hf is oxidized, the reduction of SrO is difficult to proceed. Therefore, the oxidation-reduction reaction between Hf / SrO is atmosphere-dependent and the oxidation atmosphere Then it can be interpreted that the reaction has become difficult. In the first place, it was expected that the metal Hf component was more likely to be reduced if Hf was easily oxidized in an oxygen atmosphere, but the result was the opposite, and 450 ° C. was not sufficient to oxidize bulk Hf, and Hf / This is probably because the oxidation of Hf proceeds in a special environment called the SrO interface. Eventually, it was found that an oxidation-reduction reaction can occur between Hf / SrO at 500 ° C. or higher in an oxygen atmosphere and at 450 ° C. or higher in an atmosphere having a low oxygen partial pressure such as nitrogen or hydrogen.

  When the cap layer is formed, surface oxidation tends to be suppressed, but it is difficult to determine the bonding state of Sr at the interface by XPS, and the goal is to produce a MIS device having good electrical characteristics. Therefore, the following description will be made using the MIS capacitor characteristics.

First, the heat treatment temperature dependence of the gate leakage current density Jg (A / cm ² ) of the MIS capacitor in which the TaN electrode is formed in the structure of FIGS. 6A to 6E is shown in FIGS. Shown in In addition, since the element isolation region is formed in the capacitor, the damage at the time of processing the gate electrode is small, and the leakage current component due to processing is small. Since the Ge substrate used is n-type, the region where the sign of the gate voltage Vg (V) is negative is the depletion side, and the positive region is the accumulation side. Jg tends to decrease as the heat treatment temperature increases. As a typical capacity-voltage characteristic (CV characteristic), the CV characteristic at 100 kHz is shown in FIG. 14 for the sample heat-treated at 600 ° C. in FIG. From this figure, it can be seen that good MIS characteristics are shown.

  Thus, by setting the heat treatment temperature in the oxidation of the Hf film 13 and the reduction of the SrO film 12 in the range of 500 ° C. to 700 ° C., the oxidation-reduction reaction between Hf / SrO can be performed efficiently. Therefore, it is possible to realize good electrical characteristics as a MIS device.

(Modification)
The present invention is not limited to the above-described embodiments.

The underlayer for depositing each layer is not necessarily limited to a single crystal Ge substrate, and may be a semiconductor region containing Ge. For example, polycrystalline Ge, amorphous Ge, and C, Si, and Sn may be included in these Ge regions. Further, the semiconductor region may be formed on an oxide, for example, a form such as GOI (Germanium On Insulator) or TFT (thin film transistor).
The method for forming a film of strontium oxide is not limited to the sputtering method, but a general method such as vapor deposition, chemical vapor deposition (CVD), atomic layer deposition (ALD), or pulsed laser deposition (PLD). A good deposition method.

  The metal that reduces strontium oxide may be other than Hf. Metals having a larger Gibbs free energy difference than SrO, such as Zr, Ta, Y, Al, Ti, lanthanoid metals (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), Si, Ca, Mg, or a composite thereof may be used. Furthermore, the metal nitride may be sufficient. For example, TaN, TiN or the like may be used.

FIG. 15 shows XPS Sr ₃ d when strontium oxide is deposited on Hf, Al, TiN by sputtering (FIG. 15A) and heat-treated at 700 ° C. for 1 minute in a nitrogen atmosphere (FIG. 15B). A peak is shown. It can be seen that a part of the peak due to SrO is changed to Sr after the heat treatment. Furthermore, since the oxidation peak of the base metal increased, it can be seen that strontium oxide can be reduced with these metals and nitrides.

  In the embodiment, Sr is used as a metal for combining with Ge, but barium (Ba) may be used instead. That is, after forming an oxide film containing Ba on the semiconductor region, oxidation and reduction by heat treatment may be performed to form a nonmetallic compound semiconductor layer containing Ba.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

11 ... Ge substrate (semiconductor region)
12 ... SrO film (oxide film)
13 ... Hf film (metal film)
14… Al ₂ O ₃ film (protective insulating film)
15 ... TaN film (gate electrode)
22 ... Sr film 23 ... HfO ₂ film (metal oxide film)
32 ... SrGex film (non-metallic compound layer)

Claims (7)

Forming an oxide film containing Sr or Ba on a semiconductor region containing Ge as a main component;
Forming a metal film on the oxide film;
Forming a metal oxide film by performing a heat treatment after forming the metal film, oxidizing the metal film with oxygen in the oxide film, and forming an Sr film or a Ba film by reducing the oxide film; ,
Reacting the Sr film or Ba film with the semiconductor region to form a non-metallic compound layer;
Forming a gate electrode on the metal oxide film;
A method for manufacturing a semiconductor device, comprising: Forming an oxide film containing Sr or Ba on a semiconductor region containing Ge as a main component;
Forming a metal film on the oxide film;
Forming a protective insulating film for suppressing oxidation of the metal film on the metal film;
Forming a protective oxide film and then performing a heat treatment to oxidize the metal film with oxygen in the oxide film to form a metal oxide film and reduce the oxide film to form an Sr film or a Ba film; When,
Reacting the Sr film or Ba film with the semiconductor region to form a non-metallic compound layer;
Forming a gate electrode on the protective insulating film or on the metal oxide film after removing the protective insulating film;
A method for manufacturing a semiconductor device, comprising: Forming an oxide film containing Sr or Ba on a semiconductor region containing Ge as a main component;
Forming a metal film on the oxide film;
Forming a protective insulating film for suppressing oxidation of the metal film on the metal film;
Forming a gate electrode on the protective insulating film;
Forming a metal oxide film by performing heat treatment after forming the gate electrode, oxidizing the metal film with oxygen in the oxide film, and forming an Sr film or a Ba film by reducing the oxide film; ,
Reacting the Sr film or Ba film with the semiconductor region to form a non-metallic compound layer;
A method for manufacturing a semiconductor device, comprising:   The method for manufacturing a semiconductor device according to claim 1, wherein the oxidation of the metal film and the compounding of the Sr film or Ba film and the semiconductor region are simultaneously performed.   The method for manufacturing a semiconductor device according to claim 1, wherein the heat treatment in the oxidation of the metal film and the reduction of the oxide film is performed in a range of 500 ° C. to 700 ° C. 5.   The method for manufacturing a semiconductor device according to claim 1, wherein Hf is used as the metal film. The method for manufacturing a semiconductor device according to claim 2, wherein Al ₂ O ₃ or HfO ₂ is used as the protective insulating film.

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