JPH09167856A - Compound semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to well prevent deposition of Al on the surface of an anode electrode by a method wherein the anode electrode is constituted of an ohmiccontact layer, which is provided in ohmic contact to a compound semiconductor region, a diffusion barrier layer, which is formed on the ohmic contact layer, and metal layer for connection use, which is formed on the diffusion barrier later. SOLUTION: An anode electrode 8 is formed on the upper surface of a contact layer 7, which is the uppermost layer of a light-emitting diode, and this anode electrode 8 is provided with an AuGeNi layer 8a, which is used as an ohmic contact layer, and is provided with an Au layer 8b for enhancing a conceivability, a diffusion barrier layer 8c containing nitrogen and oxygen, a Ti layer 8d having an action a diffusion barrier action and continuity and an Au layer 8e which is used as a metal layer for connection use for enhancing a wire bonding, which are formed in order on the layer 8a. Thereby, deposition of Al on the surface of the electrode 8 can be well prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compound semiconductor device comprising an Al-containing compound semiconductor region and an electrode formed on this region, the electrode having an Al diffusion barrier layer.

[0002]

Prior Art and Problems to be Solved by the Invention Al
As a contact electrode for a compound semiconductor region containing (aluminum), an electrode having an Au (gold) layer on its upper surface and enabling ball bonding of an Au wire is known. However, when the semiconductor element having the Au electrode is subjected to heat treatment or the like, Al in the compound semiconductor region under the electrode is deposited on the surface of the electrode, and Al oxide is formed on this surface.
The connection strength of the u-wire to the electrode surface is weakened.

As a means for solving the above problems, it is known to form a diffusion barrier layer for preventing Al diffusion between electrode layers. For example, it is known that Ti (titanium) has a diffusion preventing effect on Al, and a lot of documents introduce a diffusion barrier metal layer made of Ti. However, Ti may have a defect in the layer due to heat treatment or the like, and the desired diffusion preventing effect cannot be obtained. Therefore, today, the diffusion barrier metal layer is formed of Ti.
Instead of TiN, an attempt has been made to form TiN (titanium nitride). TiN is also expected to exert a higher level of diffusion prevention effect because it also inactivates the crystal grain boundaries that are diffusion paths for Al. However, this T
With the diffusion barrier layer made of iN, it is difficult to obtain a good diffusion preventing effect over a long period of time, and it is the actual situation that it has not reached the level of practical use.

Therefore, it is an object of the present invention to provide a compound semiconductor device provided with an electrode capable of favorably preventing Al from depositing on the electrode surface.

[0005]

The present invention for achieving the above object provides a compound semiconductor device having an electrode on a compound semiconductor region containing Al, wherein the electrode is in ohmic contact with the compound semiconductor region. Ohmic contact layer and Ti (titanium), N (nitrogen) and O formed on the ohmic contact layer to prevent Al diffusion.
A compound semiconductor, comprising: a diffusion barrier layer containing (oxygen); and a connection metal layer formed on the diffusion barrier layer by a material capable of connecting a metal lead member. It is related to the device. It should be noted that, as described in claim 2, T is provided between the diffusion barrier layer and the connection metal layer.
It is desirable to provide the i layer. In addition, as described in claim 3, the ohmic contact layer may be an AuGeNi layer or an AuBe layer.
(Gold beryllium) layer, and A between this and the diffusion barrier layer
It is desirable to provide a u layer. Further, as described in claim 4, it is desirable that the diffusion barrier layer is a layer having a composition of Ti 15 to 30 atom%, that is, mol% N 45 to 80 atom%, that is, mol% O 5 to 25 atom%, that is, mol%. .

[0006]

The function and effect of the invention: A layer containing Ti, N and O (TiNO) as an Al diffusion barrier layer according to the invention of each claim.
The layer) has a better effect of preventing diffusion of Al than TiN. That is, since O (oxygen) has a smaller atomic radius than N (nitrogen), it fills the portion not filled with N at the Ti interface. Therefore, as compared with the diffusion barrier layer made of TiN, a diffusion path of Al is less likely to occur, and the Al diffusion blocking effect is improved. Therefore, the deposition of Al on the electrode surface is suppressed, Al oxide is less likely to be formed on the electrode surface, and a decrease in the connection strength of the lead member such as a metal thin wire can be prevented. Further, as described in claim 2, when a Ti layer is provided between the Au layer and the diffusion barrier layer, Ti is Au and Ti.
Since it makes good contact with both NO, a low resistance electrode can be formed well. In addition, as described in claim 3, by arranging the AuGeNi layer or the AuBe layer, the Au layer, and the TiNO layer in this order on the AlGaAs semiconductor region, the TiNO layer can be satisfactorily coupled to the AuBeNi layer or the AuBe layer. Further, as described in claim 4, by making the ratio of N larger than that of O, it is possible to prevent the conductivity of the diffusion barrier layer from being significantly lowered.

[0007]

EXAMPLES Next, a light emitting diode as a compound semiconductor device according to an example of the present invention will be described with reference to FIGS. The light emitting diode shown in FIG. 1 includes a p-type GaAs substrate layer 1, a p-type GaAs buffer layer 2, and a p-type AlGaInP.
Cladding layer 3, AlGaInP active layer 4, n-type AlGa
A semiconductor substrate in which an In-type clad layer 5, a p-type AlGaInP current blocking layer 6, and an n-type AlGaAs contact layer 7 are sequentially stacked, an anode electrode 8 formed on the upper surface of the contact layer 7, and a lower surface of the substrate layer 1. And a cathode electrode 9. The other parts except the anode electrode 8 are similar to the conventional light emitting diode. A fine metal wire 10 made of Au is bonded to the anode electrode 8 as shown by a broken line.

In the light emitting diode of this embodiment, the structure of the anode electrode 8 is different from the conventional one, and as shown in FIG. 2, the electrode 8 is AuGeNi as an ohmic contact layer on the AlGaAs contact layer 7 which is a compound semiconductor region. A layer 8a, an Au layer 8b for improving the connectivity, a TiNO layer 8c as a diffusion barrier layer, a Ti layer 8d having a diffusion barrier function and a function of assisting the connection, and a connection for improving the wire bonding. Au layer 8e as a metal layer for use
And are sequentially laminated. As an example of the thickness of each layer, the AuGeNi layer 8a is about 0.1 μm, the Au layer 8b is about 0.18 μm, the TiNO layer 8c is about 0.15 μm, and T
The i layer 8d is about 0.01 μm, and the Au layer 8e is about 2 μm. The anode electrode 8 having the above structure is made of Au in the lowermost layer.
The GeNi layer 8a to the uppermost Au layer 8e can be formed by a series of continuous vapor deposition methods. That is, the evaporation source is replaced with a metal material forming the layers to be sequentially formed, and molecules evaporated from the evaporation source are laminated on one main surface of the contact layer 7. In the present embodiment, the so-called electron beam heating type vacuum vapor deposition in which the vaporization source is irradiated with an electron beam to heat the vaporization source is used.However, another vapor deposition method of heating without using the electron beam is used. Is also good. Further, in this example, a so-called reactive vapor deposition method was used. That is, taking the formation of the TiNO layer 8c as an example, Ti is used as the evaporation material, and a mixed gas of N ₂ and O ₂ is used as the atmosphere gas in the bell jar.
While the molecules of the mixed gas and the gas molecules of the reaction product freely fly around in the air to be vapor-deposited, the Ti molecules from the evaporation source are almost distributed to one main surface of the Au layer 8b. This is a method in which the gas molecules and the Ti molecules are allowed to react on the main surface by going straight to form a compound of both. However, it may be formed by other methods. The composition ratio of Ti, N and O of the TiNO layer 8c of this embodiment is Ti: 25 atomic% or mol%, N: 60 atomic% or mol%, O: 15 atomic% or mol%.

According to this embodiment, in addition to the effects already described in the section of the description of the effects of the invention, the following effects can be obtained. (1) TiNO layer 8c and lower compound semiconductor AlG
Since there is no Ti layer between the aAs contact layers 7,
A good ohmic contact is formed. Ti is Al, Ga
Although it has a strong reactivity with Al, it hardly reacts with As, and it is considered that when Ti reaches the interface with the AlGaAs semiconductor layer, grain boundaries that are not sufficiently alloyed exist at the interface. . (2) Since the thickness of the TiNO layer 8c is 0.3 μm or less, the conductivity is hardly reduced by providing the TiNO layer 8c. That is, the TiNO layer 8c is 0.3
If the thickness is thicker than μm, the resistance of the electrode 8 increases due to the provision thereof, which is not desirable, but if the thickness is 0.3 μm or less, the resistance of the electrode 8 falls within a range in which there is no problem. (3) Since the thickness of the TiNO layer 8c is 0.1 μm or more, cracks and the like do not occur in the TiNO layer 8c, and the Al diffusion preventing effect is excellently obtained. If the TiNO layer 8c becomes thinner than 0.1 μm, cracks and the like are likely to occur in the layer, Al infiltrates through the cracks, and it becomes impossible to obtain a sufficient Al diffusion preventing effect. (4) Compared with TiN composed of the bond of Ti and N, TiO composed of the bond of Ti and O easily lowers the conductivity within the layer. However, in this embodiment, since the content of O is smaller than that of N, the conductivity is not greatly impaired.

[0010]

[Modification] The present invention is not limited to the above-described embodiment, but can be modified. For example, if necessary, Au
The layer 8b and / or the Ti layer 8d can be omitted. Further, the structure of the semiconductor layer in the semiconductor substrate can be modified in various ways. Further, the same effect can be obtained by forming the compound semiconductor region containing Al as a p-type conductivity type and forming the ohmic contact layer as an ohmic contact layer for p-type by an AuBe (gold beryllium) layer.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a light emitting diode according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the electrode of FIG. 1 in detail.

[Explanation of symbols]

 8a AuGeNi layer 8b Au layer 8c TiNO layer 8d Ti layer 8e Au layer

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[Procedure amendment]

[Submission date] January 27, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

[0007]

EXAMPLES Next, a light emitting diode as a compound semiconductor device according to an example of the present invention will be described with reference to FIGS. The light emitting diode shown in FIG. 1 includes a p-type GaAs substrate layer 1, a p-type GaAs buffer layer 2, and a p-type AlGaInP.
Cladding layer 3, AlGaInP active layer 4, n-type AlGa
An In P clad layer 5, a semiconductor substrate a p-type AlGaInP current blocking layer 6, n-type AlGaAs contact layer 7 are sequentially stacked, formed on the lower surface of the contact layer anode electrode 8 is formed on the upper surface 7 and the substrate layer 1 And the cathode electrode 9 is formed. The other parts except the anode electrode 8 are similar to the conventional light emitting diode. Further, as shown by the broken line, the metal thin wire 1 made of Au is formed on the anode electrode 8.
0 is bonded.

Claims (4)

[Claims] 1. In a compound semiconductor device having an electrode on a compound semiconductor region containing Al, an ohmic contact layer in which the electrode is in ohmic contact with the compound semiconductor region, and the ohmic contact layer for preventing Al diffusion. Ti (titanium), N (nitrogen) and O (oxygen) formed on the contact layer
And a connection metal layer formed on the diffusion barrier layer by a material capable of connecting a metal lead member. 2. The connection metal layer is an Au layer, and the electrode further has a Ti layer between the diffusion barrier layer and the connection metal layer. Compound semiconductor device. 3. The compound semiconductor region is an AlGaAs semiconductor region, and the ohmic contact layer is AuGeNi.
3. The compound semiconductor device according to claim 1, wherein the compound semiconductor device is a layer or AuBe, and the electrode further has an Au layer between the ohmic contact layer and the diffusion barrier layer. 4. The diffusion barrier layer is a layer having a composition in which Ti is 15 to 30 atom% N is 45 to 80 atom% O is 5 to 25 atom%. The compound semiconductor device described.