JP2940455B2 - Compound semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a compound semiconductor device comprising a compound semiconductor region containing Al and an electrode formed on this region, wherein the electrode has an Al diffusion barrier layer.

[0002]

BACKGROUND OF THE INVENTION Problems to be Solved by the Invention
2. Description of the Related Art As a contact electrode of a compound semiconductor region containing (aluminum), an electrode having an upper surface formed of an Au (gold) layer and enabling ball bonding of an Au wire is known. However, when heat treatment or the like is performed on the semiconductor element having the Au electrode, Al in the compound semiconductor region below the electrode precipitates on the surface of the electrode, and an Al oxide is formed on the surface.
The connection strength of the u wire to the electrode surface is reduced.

As a means for solving the above problem, it is known to form a diffusion barrier layer for preventing the diffusion of Al between electrode layers. For example, it is known that Ti (titanium) has a diffusion preventing effect on Al, and a large number of documents introduce a diffusion barrier metal layer made of Ti. However, Ti may have defects in its 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 made of Ti
Instead of TiN (titanium nitride). TiN is also expected to exhibit a higher level of diffusion prevention effect because it also inactivates the crystal grain boundaries that serve as Al diffusion paths. However, this T
It is difficult to obtain a good diffusion preventing effect over a long period of time by using a diffusion barrier layer made of iN, and in fact, it has not reached the level of practical use.

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

[0005]

In order to achieve the above object, the present invention 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. An ohmic contact layer, and Ti (titanium), N (nitrogen) and O formed on the ohmic contact layer to prevent diffusion of Al.
A compound semiconductor, comprising: a diffusion barrier layer containing (oxygen); and a connection metal layer formed on the diffusion barrier layer with a material capable of connecting a metal lead member. It relates to the element. In addition, as described in claim 2, T.sub.T is located between the diffusion barrier layer and the connection metal layer.
It is desirable to provide an i-layer. The ohmic contact layer may be formed of an AuGeNi layer or an AuBe.
(Gold beryllium) layer, and A
It is desirable to provide a u layer. It is preferable that the diffusion barrier layer is a layer having a composition of 15 to 30 atomic% of Ti, ie, mol%, 45 to 80 atomic% of N, ie, mol%, and 5 to 25 atomic%, ie, mol%. .

[0006]

According to the present invention, a layer containing Ti, N and O (TiNO) is used as an Al diffusion barrier layer.
The layer) exerts a better effect of preventing the diffusion of Al than TiN. That is, since O (oxygen) has a smaller atomic radius than N (nitrogen), it fills a portion of the Ti interface that is not filled with N. Therefore, compared with the diffusion barrier layer made of TiN, an Al diffusion path (path) is less likely to occur, and the effect of preventing Al diffusion is improved. For this reason, precipitation 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 lead members such as thin metal wires can be prevented. Further, when a Ti layer is provided between the Au layer and the diffusion barrier layer, Ti becomes Au and Ti
Since both electrodes are in good contact with NO, a low-resistance electrode can be formed satisfactorily. In addition, by arranging an AuGeNi layer or an AuBe layer, an Au layer, and a TiNO layer in 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 setting the ratio of N to be larger than O, it is possible to prevent a significant decrease in conductivity of the diffusion barrier layer.

[0007]

Next, a light emitting diode as a compound semiconductor device according to an embodiment of the present invention will be described with reference to FIGS. 1 includes a p-type GaAs substrate layer 1, a p-type GaAs buffer layer 2, a p-type AlGaInP
Clad 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 Cathode electrode 9. The other parts except the anode electrode 8 are the same as those of the conventional light emitting diode. The anode electrode 8 has a thin metal wire 1 made of Au as shown by a broken line.
0 is bonded.

In the light emitting diode of this embodiment, the structure of the anode electrode 8 is different from the conventional structure. As shown in FIG. 2, the electrode 8 is formed on the AlGaAs contact layer 7 which is a compound semiconductor region by AuGeNi as an ohmic contact layer. A layer 8a, an Au layer 8b for improving connectivity, a TiNO layer 8c as a diffusion barrier layer, a Ti layer 8d having a diffusion barrier function and a function of assisting connection, and a connection for improving wire bonding. Layer 8e as metal layer for use
Are sequentially laminated. To illustrate 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,
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 formed of the lowermost Au layer.
From the GeNi layer 8a to the uppermost Au layer 8e, it can be formed by a series of continuous vapor deposition methods. That is, the evaporation source is formed by laminating molecules evaporated from the evaporation source on one main surface of the contact layer 7 instead of the metal material constituting the layer to be sequentially formed. In the present embodiment, a so-called electron beam heating type vacuum deposition in which the evaporation source is irradiated with an electron beam to heat the evaporation source is used, but another method of heating without using the electron beam is used. Is also good. In this embodiment, a so-called reactive evaporation method is used. That is, taking the formation of the TiNO layer 8c as an example, Ti is used as the evaporating 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, in some cases, the gas molecules of the reaction product freely fly around in the air for vapor deposition, Ti molecules from the evaporation source are almost completely transferred to one main surface of the Au layer 8b. In this method, gas molecules and Ti molecules are reacted on the main surface to form a compound of both. However, it may be formed by other methods. The composition ratio of Ti, N, and O in the TiNO layer 8c of this embodiment is set to 25 atomic% or mol% of Ti, 60 atomic% or mol% of N, and 15 atomic% or mol% of O.

According to this embodiment, the following operation and effect can be obtained in addition to the effects already described in the section of the operation and effect of the invention. (1) TiNO layer 8c and lower compound semiconductor AlG
Since no Ti layer is interposed between the aAs contact layers 7,
Good ohmic contact is formed. Ti is Al, Ga
It is considered that since Ti has almost no reactivity with As, it hardly reacts with As, and when Ti reaches the interface with the AlGaAs semiconductor layer, there is a grain boundary which is not sufficiently alloyed at the interface. . (2) Since the thickness of the TiNO layer 8c is 0.3 μm or less, there is almost no decrease in conductivity due to the provision of the TiNO layer 8c. That is, the TiNO layer 8c has a thickness of 0.3.
If the thickness is larger than μm, the resistance of the electrode 8 increases due to the provision thereof, which is not desirable. However, if it is 0.3 μm or less, the resistance of the electrode 8 becomes a value 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 effect of preventing Al diffusion can be obtained well. If the TiNO layer 8c is thinner than 0.1 μm, cracks and the like are likely to occur in the layer, and Al enters from the cracks, so that the effect of preventing Al diffusion cannot be sufficiently obtained. (4) TiO composed of a bond of Ti and O is more likely to lower the conductivity in the layer than TiN composed of a bond of Ti and N. However, in this embodiment, the content of O is smaller than that of N, so that the conductivity is not significantly impaired.

[0010]

[Modifications] 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 configuration of the semiconductor layer in the semiconductor substrate can be variously modified. Further, the same effect can be obtained even if the compound semiconductor region containing Al is of p-type conductivity and the ohmic contact layer is formed of an AuBe (gold beryllium) layer as the p-type ohmic contact 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 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

Claims (4)

(57) [Claims] 1. A compound semiconductor device having an electrode on a compound semiconductor region containing Al, wherein the electrode has an ohmic contact layer in ohmic contact with the compound semiconductor region and the ohmic contact layer for preventing diffusion of Al. Ti (titanium), N (nitrogen) and O (oxygen) formed on the contact layer
And a connection metal layer formed on the diffusion barrier layer with a material capable of connecting a metal lead member. 2. The method according to claim 1, wherein 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 electrode is a layer or AuBe, and the electrode further has an Au layer between the ohmic contact layer and the diffusion barrier layer. 4. 4. The diffusion barrier layer according to claim 1, wherein the composition is such that Ti is 15 to 30 atomic%, N is 45 to 80 atomic%, and O is 5 to 25 atomic%. The compound semiconductor device according to any one of the preceding claims.