JPH11219919A - Method for forming metal film and semiconductor device, and manufacture of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a metal film for forming a metal film with satisfactory adhesion on a compound layer, including at least Al and N, and preventing peeling, and a semiconductor device and a method for manufacturing it. SOLUTION: A compound layer including at least Al and N, for example, an AlN layer 4 is grown, and an Al film 5 in thickness equivalent to that several atomic layers is continuously formed on the surface, and an electrode 7 is formed on this, for example, by a lift-off method. Also the AlN layer 4 is grown, and N is extracted from the surface through a plasma processing by plasma, including oxygen or a radial processing generated by the plasma and an improved layer with Al2 O3 as main components can be formed, and the electrode 7 is formed on this. Also, the AlN layer 4 is grown, and an Al film is directly formed on the surface, while the surface is maintained to be clean, and the electrode 7 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a metal film, a semiconductor device and a method for manufacturing the same, and more particularly, to a semiconductor device using a nitride III-V compound,
For example, it is suitable for application to a field effect transistor (FET).

[0002]

2. Description of the Related Art The present applicant has filed a Japanese Patent Application No. 9-104609.
No. 2 proposed a high-performance heterojunction FET using a GaN-based semiconductor. One feature of this heterojunction FET is that a gate electrode is provided on a gate insulating film made of an AlN-based material. This is AlN
Is because the thermal conductivity is as high as 2 W / cm · K, the band gap is as large as 6.2 eV, and it has excellent properties as an insulating material. In this case, the gate electrode is usually
A metal film such as a Ti / Au film or a Ti / Pt / Au film formed on the gate insulating film made of this AlN material by a vacuum evaporation method or the like. Here, the lowermost Ti film of the metal film having such a multilayer structure is used as an adhesion layer.

[0003]

However, according to the inventor's own knowledge, as described above, a Ti / Au film or a Ti / Pt film is formed on a gate insulating film made of an AlN-based material as described above.
/ When metal films such as Au films are formed, the adhesion of these metal films to the gate insulating film is higher than when these metal films are formed on the gate insulating film made of SiO ₂ film. Bad, easy to peel off. Therefore, it has been difficult to form a gate electrode having good adhesion to the gate insulating film.

Further, according to the knowledge of the present inventor, a similar problem can generally occur when a metal film as described above is formed on a compound layer containing at least Al and N. Is what is desired.

Therefore, an object of the present invention is to improve the adhesion of a metal film to a compound layer when the metal film is formed on a compound layer containing at least Al and N;
An object of the present invention is to provide a method for forming a metal film, a semiconductor device, and a method for manufacturing the same, which can prevent peeling.

[0006]

Means for Solving the Problems The present inventor has made intensive studies in order to solve the above-mentioned problems of the prior art. The outline is described below.

As far as the present inventor knows, the fact is that the adhesion of a metal film to a compound layer containing at least Al and N, such as an AlN-based compound layer, has not been sufficiently investigated.

The inventor of the present invention has found that in the course of the trial production of the above-described heterojunction FET, the adhesion of the metal film for forming the gate electrode to the gate insulating film made of an AlN-based material is poor, and it is easy to peel off. As a result of various studies on the countermeasures, when a metal film is generally formed on a compound layer containing Al and N, the metal film is not formed directly but on the compound layer. First, it was concluded that it is effective to form an Al or Al alloy film having good adhesion to a metal film and then form a metal film thereon. The surface of the compound layer containing Al and N is subjected to plasma treatment using plasma such as oxygen or treatment with radicals generated by the plasma to extract N from the vicinity of the surface. It is also effective to form a film. Further, the compound layer containing Al and N has an AN layer at least near the surface typified by an AlN layer.
In the case of a compound layer containing l and N as main components, an Al or Al alloy film can be directly formed as a metal film on the compound layer with good adhesion.

The present invention has been devised based on the above study by the present inventors.

That is, in order to achieve the above object, a first invention of the present invention relates to a metal film forming method for forming a metal film on a compound layer containing at least Al and N, After an Al or Al alloy film is formed on the surface of the compound layer, a metal film other than the Al or Al alloy film is formed on the Al or Al alloy film.

In the first invention, the thickness of the Al or Al alloy film formed on the surface of the compound layer may be at least one atomic layer, and there is no particular upper limit.
It is sufficient if the thickness is the thickness of the atomic layer.

[0012] The second invention of the present invention relates to at least Al
In the method of forming a metal film on a compound layer containing N and N, the surface of the compound layer is subjected to a plasma treatment or a treatment with radicals generated by plasma to thereby form a vicinity of the surface of the compound layer. After extracting N from the metal layer, a metal film is formed on the compound layer.

In the second invention, the plasma is typically a plasma containing oxygen, and specifically, for example, a plasma containing oxygen (O ₂ ) or a dinitrogen monoxide (N ₂ O) ).

According to a third aspect of the present invention, at least the vicinity of the surface has an Al layer on the surface of the compound layer containing Al and N as main components.
A method of forming a metal film, characterized in that a metal film mainly comprising is formed.

In the third invention, the metal film containing Al as a main component is typically an Al or Al alloy film.

According to a fourth aspect of the present invention, at least Al
In a semiconductor device in which a metal film other than an Al or Al alloy film is provided on a compound layer containing N and N, it is required that the Al or Al alloy film be provided at least at a part of an interface between the compound layer and the metal film. It is a feature.

In the fourth invention, the thickness of the Al or Al alloy film provided at the interface between the compound layer and the metal film may be at least one atomic layer, and there is no particular upper limit. A thickness of three atomic layers is sufficient.

According to a fifth aspect of the present invention, at least Al
In a semiconductor device in which a metal film other than an Al or Al alloy film is provided on a compound layer containing N and N, the Al composition of the compound layer in at least a portion near the interface between the compound layer and the metal film is different from that of another portion. It is characterized by being larger than the Al composition.

According to a sixth aspect of the present invention, at least a portion near the surface has an Al layer on the surface of the compound layer containing Al and N as main components.
And a metal film mainly composed of:

In the sixth aspect, the metal film containing Al as a main component is typically an Al or Al alloy film.

According to a seventh aspect of the present invention, at least Al
A method of manufacturing a semiconductor device in which a metal film is formed on a compound layer containing N and N,
Alternatively, after forming the Al alloy film, a metal film other than the Al or Al alloy film is formed on the Al or Al alloy film.

In the seventh aspect, the thickness of the Al or Al alloy film formed on the surface of the compound layer may be at least one atomic layer, and there is no particular upper limit.
It is sufficient if the thickness is the thickness of the atomic layer.

According to an eighth aspect of the present invention, at least Al
In a method of manufacturing a semiconductor device in which a metal film is formed on a compound layer containing N and N, the surface of the compound layer is subjected to a plasma treatment or a treatment with radicals generated by plasma to reduce the vicinity of the surface of the compound layer. After extracting N, a metal film is formed on the compound layer.

In the eighth aspect, the plasma is typically a plasma containing oxygen, and specifically, for example, a plasma containing oxygen (O ₂ ) or a dinitrogen monoxide (N ₂ O) ).

According to a ninth aspect of the present invention, there is provided a semiconductor device having a step of forming a metal film mainly composed of Al on a compound layer mainly composed of Al and N at least near the surface. It is a manufacturing method of an apparatus.

In the ninth aspect, the metal film containing Al as a main component is typically an Al or Al alloy film.

In the present invention, the compound layer containing Al and N is typically a nitride-based III-V compound layer containing Al, for example, an Al _v Ga _{1 -v} N layer (where 0 <
v ≦ 1), especially those containing AlN as a main component, for example, A
1N layer. In general, a nitride III-V compound layer containing Al is made of a group III element other than Al,
It may contain any of a, In or B, and optionally contain As or P as a group V element. Also,
The Al alloy film is, for example, an Al-Si film, an Al-Si-C
u film and the like.

According to the first aspect of the present invention configured as described above,
According to the fourth and seventh aspects, since the base of the metal film is an Al or Al alloy film having good adhesion to the metal film,
A metal film can be formed with good adhesion on a compound layer containing at least Al and N.

According to the second and eighth aspects of the present invention configured as described above, the compound layer after the N is drawn out from the vicinity of the surface by performing the plasma processing or the processing by the radical generated by the plasma. Since the surface is generally active, when a plasma containing, for example, oxygen is used as the plasma, a modified layer such as an oxide film is formed on the surface of the compound layer by a reaction with oxygen. The modified layer thus formed generally has good adhesion to the metal film. Therefore, the adhesion of the metal film formed on the modified layer is improved.

The third aspect of the present invention constructed as described above,
According to the sixth and ninth aspects, at least the surface immediately after the growth of the compound layer containing Al and N as main components is generally slightly oxidized. This means that the binding energy of Al—N is 297 ± 96 kJ / mol, whereas the binding energy of Al—O is 507.5 ± 10.
It is considered that the cause was as large as 5 kJ / mol.
When a metal film is formed on the compound layer whose surface is oxidized, the adhesion is considered to be determined by the formation energy (ΔF) of the oxide. ΔF in the case is −204 kcal / mol
In the case of Al, ΔF is −376.7 k
much higher, cal / mol. For this reason, at least the vicinity of the surface has A on the compound layer containing Al and N as main components.
When a metal film containing l as a main component is formed, the adhesion of the metal film becomes good.

According to the fifth aspect of the present invention configured as described above, the Al composition of the compound layer in at least a part near the interface between the metal layer and the compound layer containing at least Al and N is different from that of the other. By being larger than the Al composition of the portion, the structure is similar to the case where the Al or Al alloy film is provided on at least a part of the interface between the compound layer and the metal film as in the fourth invention, Therefore, the adhesion of the metal film to the compound layer is improved.

[0032]

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

First, a method for forming an electrode according to the first embodiment of the present invention will be described.

In the first embodiment, as shown in FIG. 1A, a GaN buffer layer is first formed on a c-plane sapphire substrate 1 by a metal organic chemical vapor deposition (MOCVD) method at a substrate temperature of, for example, about 560 ° C. After the GaN layer 3 is grown at a low temperature, a GaN layer 3 and an AlN layer 4 are successively grown on the GaN buffer layer 2 by MOCVD. To give an example of the thickness of these layers, the GaN buffer layer 2 has a thickness of 30 nm, the GaN layer 3 has a thickness of 1 μm, and the AlN layer 4 has a thickness of 6 nm. As an example of the growth conditions of the GaN layer 3, trimethyl gallium (TMG) and ammonia (NH ₃ ) are used as growth raw materials, the flow rates thereof are respectively 50 SCCM and 20 SLM, and the reaction pressure is 50.
0 Torr and the substrate temperature is 1000 ° C. Also, Al
As an example of the growth conditions for the N layer 4, trimethyl aluminum (TMA) and ammonia (N
H ₃ ) and their flow rate was 10 SCCM each.
And 20 SLM, the reaction pressure is 500 Torr, and the substrate temperature is 1000 ° C.

Next, as shown in FIG. 1B, after growing the AlN layer 4, without removing the c-plane sapphire substrate 1 to the atmosphere, an Al film 5 is continuously formed on the surface of the AlN layer 4 by MOCVD, for example. A film is formed to a thickness of two atomic layers. At this time, since the Al film 5 is formed on the clean surface of the AlN layer 4, the adhesion to the AlN layer 4 is good. As an example of conditions for forming the Al film 5, TMA and H ₂ are used as growth raw materials, the flow rates thereof are respectively 10 SCCM and 20 SLM, the reaction pressure is 700 Torr, and the substrate temperature is 500 ° C.

Next, as shown in FIG. 1C, a resist pattern 6 having an inverted pattern shape of an electrode to be formed is formed on the Al film 5 by lithography using, for example, a positive resist. The thickness of the positive resist used for forming the resist pattern 6 is, for example, 1.5 μm. Next, for example, a Cu film is formed as a metal film for forming an electrode on the entire surface by, for example, a sputtering method or a vacuum evaporation method, and then a resist pattern 6 is formed on the Cu film formed thereon.
Remove with the film (lift-off). The thickness of the Cu film is, for example, 0.8 μm.

By the above steps, as shown in FIG. 1D,
An electrode 7 made of Cu is formed on the AlN layer 4 via an Al film 5.

As described above, according to the first embodiment, a Cu film as a metal film for forming an electrode is not formed directly on the AlN layer 4 but continuously formed after the AlN layer 4 is grown. Since the Cu film is formed after the Al film 5 is formed on the outermost surface, the Cu film is not formed on the AlN layer 4 having poor adhesion, but is formed on the Al film 5 having good adhesion. It is to be formed on. Therefore, the adhesion of the Cu film to the base is good, and the adhesion of the electrode 7 formed by using the Cu film is good, and peeling can be prevented.

Next, a method for forming an electrode according to the second embodiment of the present invention will be described.

In the second embodiment, first, as shown in FIG. 2A, a GaN buffer layer 2, a GaN layer 3, and an AlN layer 4 are formed on a c-plane sapphire substrate 1 in the same manner as in the first embodiment. Grow sequentially.

Next, as shown in FIG. 2B, the c-plane sapphire substrate 1 having been grown up to the AlN layer 4 is transferred from the MOCVD apparatus to another plasma processing apparatus. By irradiating the plasma 8 containing oxygen, a modified layer 9 deficient in N is formed on the outermost surface of the AlN layer 4. At this time, AlN which lacked N
The outermost surface of the layer 4 is in a chemically active state,
Is immediately oxidized, so that the modified layer 9 usually contains alumina (Al ₂ O ₃ ) as a main component. As an example of the conditions of this plasma processing, oxygen (O
₂ ) and helium (He), the flow rates thereof are respectively 100 SCCM and 500 SCCM, the pressure is 500 mTorr, the substrate temperature is 300 ° C., the RF power (13.56 MHz) is 100 W, and the processing time is 5 minutes.

Next, as shown in FIG. 2C, a resist pattern 6 having an inverted pattern shape of an electrode to be formed is formed on the modified layer 9 in the same manner as in the first embodiment. Next, for example, a Ti film is formed as a metal film for forming an electrode on the entire surface by, for example, a sputtering method or a vacuum evaporation method, and then the resist pattern 6 is removed together with the Ti film formed thereon. The thickness of this Ti film is, for example, 0.8 μm.
m.

By the above steps, as shown in FIG. 2D,
An electrode 7 made of Ti is formed on the AlN layer 4 via a modified layer 9.

According to the second embodiment, the AlN layer 4
Instead of directly forming a Ti film as a metal film for forming an electrode thereon, a modified layer 9 mainly composed of Al ₂ O ₃ is formed on the outermost surface of the AlN layer 4 after the growth of the AlN layer 4. Since the Ti film is formed after this, the Ti film is not formed on the AlN layer 4 having poor adhesion but on the modified layer 9 mainly composed of Al ₂ O ₃ having good adhesion. Is formed. Therefore, the adhesion of the Ti film to the base is good, and thus the adhesion of the electrode 7 formed using the Ti film is good, and peeling can be prevented.

Next, a method for forming an electrode according to the third embodiment of the present invention will be described.

In the second embodiment, the reformed layer 9 is formed by directly plasma-treating the outermost surface of the AlN layer 4 using the plasma 8 containing oxygen. This may cause damage to the AlN layer 4 or the interface between the AlN layer 4 and the GaN layer 3. Therefore, in the third embodiment, by irradiating the radicals generated in the plasma containing oxygen by a remote plasma method on the outermost surface of the AlN layer 4, the Al ₂ O ₃ on the outermost surface of the AlN layer 4 A modified layer 9 as a main component is formed. Other points are the same as those of the second embodiment, and the description is omitted.

According to the third embodiment, the same advantages as those of the second embodiment can be obtained, and the AlN layer 4
Alternatively, it is possible to obtain an advantage that damage generated at the interface between the AlN layer 4 and the GaN layer 3 can be reduced.

Next, a method for forming an electrode according to the fourth embodiment of the present invention will be described.

In the fourth embodiment, first, as shown in FIG. 3A, a GaN buffer layer 2, a GaN layer 3, and an AlN layer 4 are formed on a c-plane sapphire substrate 1 in the same manner as in the first embodiment. Grow sequentially.

Next, as shown in FIG. 3B, the Al
With the surface of the N layer 4 kept clean, a resist pattern 6 having an inverted pattern shape of an electrode to be formed is formed on the AlN layer 4 in the same manner as in the first embodiment. Next, the c-plane sapphire substrate 1 on which the resist pattern 6 is formed is held in a drier (not shown), and the surface of the exposed AlN layer 4 not covered with the resist pattern 6 is sufficiently dried. Next, an Al film is formed on the AlN layer 4 as a metal film for forming an electrode by, for example, a sputtering method or a vacuum evaporation method.
Is removed together with the Al film formed thereon. The thickness of the Al film is, for example, 0.8 μm.

By the above steps, as shown in FIG. 3C,
An electrode 7 made of Al is formed on the AlN layer 4.

According to the fourth embodiment, the AlN layer 4
The electrode 7 can be formed thereon with good adhesion, and the Al film 5 as an adhesion layer can be formed before forming the metal film for forming the electrode as in the first, second and third embodiments. Since there is no need to form a film or to form the modified layer 9, there is also obtained an advantage that the process can be simplified.

Next, G according to the fifth embodiment of the present invention will be described.
A method for manufacturing an aN-based FET will be described.

In the fifth embodiment, first, as shown in FIG. 4, a MOCV is formed on a c-plane sapphire substrate 11.
After the GaN buffer layer 12 is grown at a low temperature of, for example, about 560 ° C. by the method D, subsequently, the Al _x Ga ₁ -xN layer 13 ( Where 0 ≦ x ≦
1), Al _y Ga _1-y N layer 14 (where 0 <y ≦
1), n-type Al _z Ga _{1 -z} N layer 15 (where 0 ≦ z ≦
1), undoped Al _z Ga _{1 -z} N layer 16 (where 0
≦ z ≦ 1), an undoped Ga _1-u In u N layer 17 (where, 0 ≦ u ≦ 1) and Al _v Ga _1-v N layer 18 (where, 0 <v ≦ 1) a are successively grown. Where Al _y G
a _1-y N layer 14 is a barrier layer, n-type Al _z Ga _1-z N layer 1
5 the electron supply layer, an undoped Al _z Ga _1-z N layer 16 is a spacer layer, an undoped Ga _1-u In u N layer 17 is an electron transit layer, Al _v Ga _1-v N layer 18 constituting the gate insulating film I do. The thickness of the undoped Ga _1-u In u N layer 17 is, for example, 1nm or 15nm or less, preferably to 2nm or 10nm or less. N-type Al _z as electron supply layer
The doping concentration of the Ga _{1 -zN} layer 15 is, for example, 1.0 × 1
0 ¹⁹ cm ^-3 . The product of impurity concentration × thickness of the n-type Al _z Ga _{1 -zN} layer 15 is 5 × 10 ¹⁸ [cm ⁻³ ] [n
m] to 1 × 10 ²¹ [cm ⁻³ ] [nm], preferably 5 × 10 ¹⁹ [cm ⁻³ ] [nm] to 5 × 10 ²⁰ [c]
m ⁻³ ] [nm] or less.

Next, as shown in FIG. 5, Al _v Ga _1-v
After growing the N layer 18, the c-plane sapphire substrate 1 is not taken out to the atmosphere, and the Al _v
An Al film 19 is continuously formed on the surface of the Ga _1-v N layer 18. At this time, the Al film 19 is formed of the Al _v Ga _{1 -v} N layer 1.
The Al _v Ga by being deposited into 8 clean surface of the
_The adhesion to the _1-v N layer 18 is good.

Next, as shown in FIG. 6, by the same lift-off method as in the first embodiment, the Al _v Ga _{1 -vN} layer 18 is formed.
A gate electrode 20 is formed thereon. Examples of the metal film for forming the gate electrode 20 include a Ti / Au film and a Ti / Pt film.
/ Au film, Ti / W film or the like is used.

Next, a resist pattern (not shown) having openings corresponding to the source electrode and drain electrode formation portions is formed on the surface on which the gate electrode 20 is formed as described above by lithography. undoped Ga by etching the Al _v Ga _1-v N layer 18 using the resist pattern as a mask _1-u In u N layer 1
7 is partially exposed.

Next, after forming a metal film for forming a source electrode and a drain electrode on the entire surface by, for example, a vacuum evaporation method, the resist pattern is removed together with the metal film formed thereon. Thus, as shown in FIG. 7, an undoped Ga _1-u In u N layer source electrode 21 and drain electrode 22 on the 17 it is formed. As a metal film for forming the source electrode 21 and the drain electrode 22,
For example, a Ti / Al film or a Ti / Al / Pt / Au film is used. As described above, MIS (Metal-Insulator-Semic
onductor) structure and HEMT (High Electron Mobili)
A GaN-based FET having a ty transistor (ty transistor) structure is manufactured.

FIG. 8 shows an energy band diagram, particularly a conduction band, of the GaN-based FET under the flat band condition. The energy discontinuity at each heterojunction interface is
For example, ΔE _c1 = 0.639 eV, ΔE _c2 = 0.413
eV, ΔE _c3 = 0.625 eV, ΔE _c5 = 2.18 eV
It is. The electron surface density in the undoped Ga _1-u In u N layer 17 just under the gate electrode 20 is, for example, 2.0 × 10 ¹³ cm ^-2.

[0060] In FIG 7 shows the path of the electron in the undoped Ga _1-u In u N layer 17 as an electron transit layer by arrows. Further, a region where electrons are present in the undoped Ga _{1-u InuN} layer 17 is stippled.

According to the fifth embodiment, Japanese Patent Application No.
The proposed high-G _m in No. 104 609 (transconductance), in high performance GaN-based FET of the high-frequency high-power high f _T (cutoff frequency), for the same reason as the first embodiment, forming the gate insulating film Al _v Ga _1-v N
The gate electrode 19 can be formed over the layer 18 with good adhesion.

Next, G according to the sixth embodiment of the present invention will be described.
A method for manufacturing an aN-based FET will be described.

[0063] In the sixth embodiment, Al _v Ga _1-v after the N layer 18 is grown, Al by the same plasma processing as in the second embodiment on the outermost surface ₂ constituting the gate insulating film A modified layer mainly composed of O ₃ is formed, and a gate electrode 19 is formed on the modified layer by a lift-off method. Others are the same as the fifth embodiment,
Description is omitted.

According to the sixth embodiment, the same advantages as in the fifth embodiment can be obtained.

Next, G according to the seventh embodiment of the present invention will be described.
A method for manufacturing an aN-based FET will be described.

In the seventh embodiment, after an Al _v Ga _{1 -v} N layer 18 constituting a gate insulating film is grown, a plasma is formed on the outermost surface by a remote plasma method as in the third embodiment. A modified layer containing Al ₂ O ₃ as a main component is formed by treatment with radicals generated therein, and a gate electrode 19 is formed on the modified layer by a lift-off method. Others are the same as the fifth embodiment,
Description is omitted.

According to the seventh embodiment, the same advantages as in the fifth embodiment can be obtained.

Next, G according to the eighth embodiment of the present invention will be described.
A method for manufacturing an aN-based FET will be described.

In the eighth embodiment, Al _v G constituting the gate insulating film is formed in the same manner as in the fourth embodiment.
After growing the a _{1 -v} N layer 18, a gate electrode 19 made of Al is directly formed on the outermost surface by a lift-off method. Others are the same as the fifth embodiment,
Description is omitted.

According to the eighth embodiment, the same advantages as in the fifth embodiment can be obtained.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above embodiments, and various modifications based on the technical concept of the present invention are possible.

For example, the numerical values, structures, raw materials, processes, and the like described in the first to eighth embodiments are merely examples, and different numerical values, structures, raw materials, processes, and the like may be used as necessary. May be used.

[0073]

As described above, according to the present invention, when a metal film is formed on a compound layer containing at least Al and N, the adhesion of the metal film to the compound layer is improved, and Can be prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining a method for forming an electrode according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view for explaining a method of forming an electrode according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view for explaining a method of forming an electrode according to a fourth embodiment of the present invention.

FIG. 4 shows a GaN-based FE according to a fifth embodiment of the present invention.
FIG. 4 is a cross-sectional view for describing a method for manufacturing T.

FIG. 5 shows a GaN-based FE according to a fifth embodiment of the present invention.
FIG. 4 is a cross-sectional view for describing a method for manufacturing T.

FIG. 6 shows a GaN-based FE according to a fifth embodiment of the present invention.
FIG. 4 is a cross-sectional view for describing a method for manufacturing T.

FIG. 7 shows a GaN-based FE according to a fifth embodiment of the present invention.
FIG. 4 is a cross-sectional view for describing a method for manufacturing T.

FIG. 8 shows a G manufactured according to a fifth embodiment of the present invention.
FIG. 3 is an energy band diagram of an aN-based FET.

[Explanation of symbols]

1, 11 ... c-plane sapphire substrate, 3 ... GaN
Layer, 4 ... AlN layer, 5, 19 ... Al film, 7 ...
Electrode, plasma containing 8 ... oxygen, 9 ... modified _{layer, 13 ··· Al x Ga 1-} x N layer, 14 ... Al _y
Ga _1-y N layer, 15... N-type Al _z Ga _1-z N layer, 1
6 ... undoped Al _z Ga _1-z N layer, 17 ... undoped Ga _1-u In u N layer, 18 ... Al _v Ga
_1-v N layer, 20: gate electrode, 21: source electrode, 22: drain electrode

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01S 3/18 H01L 29/46 H

Claims (44)

[Claims] 1. A method for forming a metal film on a compound layer containing at least Al and N, comprising: forming an Al or Al alloy film on a surface of the compound layer; A method for forming a metal film, wherein a metal film other than the Al or Al alloy film is formed on the Al or Al alloy film. 2. The Al film formed on the surface of the compound layer.
2. The method according to claim 1, wherein the Al alloy film has a thickness of 1 to 3 atomic layers. 3. The compound layer is a nitride-based II containing Al.
2. The method according to claim 1, wherein the metal film is an IV group compound layer. 4. The method according to claim 1, wherein the compound layer is an Al _v Ga _{1 -vN} layer (where 0 <v ≦ 1). 5. The method according to claim 1, wherein the compound layer is an AlN layer. 6. A method for forming a metal film on a compound layer containing at least Al and N, wherein the surface of the compound layer is subjected to plasma treatment or treatment with radicals generated by plasma. Forming a metal film on the compound layer after extracting N from the vicinity of the surface of the compound layer. 7. The method according to claim 6, wherein the plasma is a plasma containing oxygen. 8. The nitride layer containing Al as the compound layer.
7. The method according to claim 6, wherein the metal film is an IV group compound layer. 9. The method according to claim 6, wherein the compound layer is an Al _v Ga _1-v N layer (where 0 <v ≦ 1). 10. The method according to claim 6, wherein the compound layer is an AlN layer. 11. A method for forming a metal film, wherein a metal film containing Al as a main component is formed on the surface of a compound layer containing Al and N as main components at least in the vicinity of the surface. 12. The method according to claim 11, wherein the metal film is an Al or Al alloy film. 13. The nitride-based compound containing Al as the compound layer.
12. A group II-V compound layer.
The method for forming a metal film according to the above. 14. The method according to claim 11, wherein the compound layer is an Al _v Ga _1-v N layer (where 0 <v ≦ 1). 15. The method according to claim 11, wherein the compound layer is an AlN layer. 16. A semiconductor device in which a metal film other than an Al or Al alloy film is provided on a compound layer containing at least Al and N, wherein at least a portion of an interface between the compound layer and the metal film has Al or Al A semiconductor device provided with an alloy film. 17. The semiconductor device according to claim 16, wherein said Al or Al alloy film provided at an interface between said compound layer and said metal film has a thickness of one to three atomic layers. 18. The method according to claim 18, wherein the compound layer is a nitride-based compound containing Al.
17. A group II-V compound layer.
13. The semiconductor device according to claim 1. 19. The compound layer Al _v Ga _1-v N layer (where, 0 <v ≦ 1) semiconductor device according to claim 16, wherein the a. 20. The semiconductor device according to claim 16, wherein said compound layer is an AlN layer. 21. A semiconductor device in which a metal film other than an Al or Al alloy film is provided on a compound layer containing at least Al and N, wherein at least a part near an interface between the compound layer and the metal film is provided. The Al composition of the compound layer is A
A semiconductor device characterized by being larger than 1 composition. 22. A method according to claim 1, wherein the compound layer is a nitride-based material containing Al.
22. A group II-V compound layer.
13. The semiconductor device according to claim 1. 23. The compound layer Al _v Ga _1-v N layer (where, 0 <v ≦ 1) semiconductor device according to claim 21, wherein the a. 24. The semiconductor device according to claim 21, wherein said compound layer is an AlN layer. 25. A semiconductor device wherein a metal film containing Al as a main component is provided on a surface of a compound layer containing Al and N as main components at least in the vicinity of the surface. 26. The semiconductor device according to claim 25, wherein said metal film is an Al or Al alloy film. 27. The method according to claim 27, wherein the compound layer is a nitride-based material containing Al.
26. A group II-V compound layer.
13. The semiconductor device according to claim 1. 28. The compound layer Al _v Ga _1-v N layer (where, 0 <v ≦ 1) semiconductor device according to claim 25, characterized in that the. 29. The semiconductor device according to claim 25, wherein said compound layer is an AlN layer. 30. A method of manufacturing a semiconductor device, wherein a metal film is formed on a compound layer containing at least Al and N, wherein an Al or Al alloy film is formed on a surface of the compound layer. A method for manufacturing a semiconductor device, comprising forming a metal film other than an Al or Al alloy film on an Al or Al alloy film. 31. The above A, which is formed on the surface of the above compound layer.
31. The method according to claim 30, wherein the 1 or Al alloy film has a thickness of 1 to 3 atomic layers. 32. A nitride-based compound containing Al, comprising:
31. A group II-V compound layer.
The manufacturing method of the semiconductor device described in the above. 33. The method according to claim 30, wherein the compound layer is an Al _v Ga _1-v N layer (where 0 <v ≦ 1). 34. The method according to claim 30, wherein the compound layer is an AlN layer. 35. A method for manufacturing a semiconductor device in which a metal film is formed on a compound layer containing at least Al and N, wherein the surface of the compound layer is subjected to plasma treatment or treatment with radicals generated by plasma. A method of manufacturing a semiconductor device, wherein after extracting N from the vicinity of the surface of the compound layer, a metal film is formed on the compound layer. 36. The method according to claim 35, wherein the plasma is a plasma containing oxygen. 37. The compound layer is a nitride-based compound containing Al.
36. A group II-V compound layer.
The manufacturing method of the semiconductor device described in the above. 38. The compound layer Al _v Ga _1-v N layer (where, 0 <v ≦ 1) The method of claim 35 semiconductor device, wherein it is. 39. The method according to claim 35, wherein the compound layer is an AlN layer. 40. A method of manufacturing a semiconductor device, comprising a step of forming a metal film mainly containing Al on a compound layer mainly containing Al and N at least near the surface. 41. The method according to claim 40, wherein the metal film is an Al or Al alloy film. 42. The nitride-based compound containing Al
41. A group II-V compound layer.
The manufacturing method of the semiconductor device described in the above. 43. The method according to claim 40, wherein the compound layer is an Al _v Ga _{1 -vN} layer (where 0 <v ≦ 1). 44. The method according to claim 40, wherein the compound layer is an AlN layer.