JPS58143569A - Semiconductor element - Google Patents

Abstract

PURPOSE:To obtain the III-V group compound semiconductor element having an electrode film with which both ohmic and bonding characteristics are fully satisfied by a method wherein said semiconductor element is comosed of a bonding layer consisting of a basic ohmic layer, having an excellent ohmic contact with the electrode film, and a single crystal metal film which is combinedly used as a wiring for connection to the outside part. CONSTITUTION:Zn, as an ohmic layer, is vacuum-evaporated on the surface of a P type GaP crystal substrate having the density of 10<17>cm<-3> or thereabout. A resistance heating, an electron beam evaporation and the like may be used, but taking into consideration of the combination with the process to be performed subsequently, the vapor-deposition using a cluster ion beam is considered to the the best. Then, an Au film, which will be turned to a bonding layer, is vapor-deposited using the cluster ion beam. When the sample is heat-treated in Ar at 500 deg.C for twenty minutes, a perfect ohmic property can be obtained. When a heat treatment is performed at the lower temperature of 200-300 deg.C for ten minutes, an excellent ohmic property can also be obtained. Also, excellent bondability is obtained and a thermo-press welding and a supersonic bonding can be performed excellently, thereby enabling to have greater tensile strength than that of the bonding performed using an Au wire of 50mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a V-group compound semiconductor device, and more particularly to a semiconductor device with an improved electrode configuration.

[Technical background of the invention and one point in between]

As 1-V group compound semiconductor elements, light-emitting diodes, semiconductor radars, sensors, GTHK fog transistors, etc. have been put into practical use, and GaM ALC has been put into practical use.
It's coming. Problems common to these devices include electrical conductivity between the compound semiconductor surface and the electrode film, and electrical conductivity between the compound semiconductor surface and the electrode film, as well as the electrical conductivity between the conductive wire and the conductive wire that leads to the external terminal.
Ingredients can be mentioned. The former is directly related to the quality of element characteristics, and the latter is directly related to the quality of device characteristics.

Examples of these will be explained using a compound semiconductor light emitting device, which has one of the simplest structures. Although the schematic WA is shown in the m1 diagram, the p
sIl crystal layer 2t - by liquid phase growth method or vapor phase growth method)
The entire P-N junction surface is formed by growing the N-type, which is exposed to the outside. *Emit light from the association plane.In the example in Figure 1, light mainly comes out from the 211 plane, but in the opposite case, in other words, if an N-type crystal layer is formed on the Pfi substrate and the 9-structure structure also emits light. is mainly N
Light exits from the 111th surface to the outside. The light emitting characteristics greatly depend on the characteristics of the quartz having a so-called crystal structure, such as the materials of the substrate and the crystal layer, and the P-N junction characteristics, and once these are determined, the light emitting characteristics are necessarily determined. but,
In order to take full advantage of the characteristics of the crystal structure, we need a part that reliably transmits input to the crystal structure, that is, an electrode film on the surface of the crystal structure,
The good conductive wire that connects the film and the input terminal must operate reliably.The role of the former electrode film is the ohmic property between the electrode film and the compound semiconductor interface, and the latter problem is is K11, since the good conductive cotton and the electrode film have no resistance.
Is it good? It is important to have the property of That is, the former influences device characteristics, and the latter influences device characteristics.

The material of the metal film that causes ohmic error is said to be the material of a compound semiconductor, but many documents have been published.
Those combinations are well known. For example, V @
L, RIDEOUT arrival 1m Review @f t
k@Theory and T@chn@logyta
r Qhasio Contaets to Grou
pl1l-V Cornpo-und 8*mi@o
ndIIators' (Solid 5tate El
ec-4reviB, 1975, V@j 18. p
For example, for P-GaP, Au-Zml [N-Ga
Au-81 film for P, Mu-Zn for P-GaAs K, or Au-In J[I! , N-Ga
It is said that Mu-W-81 film, Au'-80 film, etc. are good for Mu-2, but the component ratios such as Mu-Zn%Au-8i are different between GaP and GaAs.

In order to bring these alloy films into ohmic contact with the compound semiconductor interface, heat treatment is performed after the films are formed. The optimum temperature for each combination is different.'-5tX404)
Heat treatment is performed for 10 to 30 minutes at a temperature between ℃ and 50℃ to remove the electronic barrier between the film and the interface, allowing the constituent elements to mutually diffuse, and making ohmic contact. Shumei.

Next, a highly conductive wire, such as an Au1i or At line fN y f, is inked on the surface of this metal film, but it is impossible to ink the surface of this metal film to the extent that there is almost no ink on the surface of this metal film. The reason for this is that Ga element, which is a constituent element of the substrate, is deposited on the surface of the Ifi film to form a Ga layer. Au1m! Alternatively, the kt helix can be easily non-bonded to a single AuM or AjJ[, or it cannot be bonded to a Ga layer at all. The cause of this is the heat treatment process for producing the ohmic and radial characteristics mentioned above. That is, by heating, the 7C element of g moves into the compound semiconductor, and the compound semiconductor log moves into the film. The former is diffusion into the crystal.

The diffusion rate is more than two orders of magnitude faster in the case of the second case because the diffusion takes place within a solid thin film.

The former phenomenon is limited to the vicinity of the crystal interface and contributes to the ohmic characteristics, but the latter phenomenon, as described above, is an unfavorable phenomenon for the bonding process because it causes the entire Ga layer to be deposited. Furthermore, since the Ga element moves quickly in Au and At, this is a problem that needs to be solved as soon as possible for compound semiconductor devices.

K, which achieves both ohmic properties and non-damping properties, must prevent the migration of Ga elements, and the most effective method for this is to provide a barrier layer in the middle of the metal film. That is, the above-mentioned ohmic and dielectric alloy film is formed on the compound semiconductor surface, and a barrier layer is formed thereon, followed by a dendritic film and a multi-layered electrode film structure. . This barrier layer is
In order to function to stop the movement of the a element, careful attention must be paid to the material of the film, the thickness of the film, etc. The present inventors have data that TaM is optimal (411i1.
N56-12017ta).

However, in order to mass-produce and reduce costs, it is preferable to eliminate the process of forming a multilayer film and the need to form %Kra@.

[Purpose of the invention]

The present invention provides a 9-III compound semiconductor device having an electrode film that satisfactorily satisfies both ohmic and indinder characteristics without forming a barrier layer.

[Summary of the invention]

Unexploded IjlFi, the electrode film shows good electrical contact, the underlying electrical contact, and the external El! 271477
Assuming that the layer is a single crystal metal film, the moving speed of the Ga force jI! is suppressed to 17,100 or less compared to conventional films, and the movement of Ga elements is extremely slowed down to prevent accumulation of Ga elements on the electrode layer surface.

〔Effect of the invention〕

According to the present invention, by using a single crystal metal film as a bonding layer on the surface portion of the electrode film, G
& It is possible to suppress the migration and deposition of elements and ensure good induration properties.

Further, according to the present invention, by using a single crystal metal film, it is possible to reduce electrode resistance and improve yield. The former can reduce resistance by as much as 40% compared to conventional microcrystalline films, reducing input/output losses. As for the latter, improvements in uniformity during film formation and uniformity during microfabrication are particularly remarkable. Furthermore, since the binder layer is made into a single crystal, the process for producing electrical and electrical characteristics can be simplified. This is because the OLED layer is sandwiched between the compound semiconductor crystal and the interconnection layer crystal, so the diffusion of elements in the OLED layer is rounded toward the semiconductor crystal. Complete heat treatment is possible at low temperatures and in a short time! This greatly contributes to process reduction.

[Embodiments of the invention]

Example 1 Zn is vacuum-deposited as an electrolytic layer on the surface of a P-type GaP crystal substrate having a concentration on the order of 10"cxs-'.

Although this method may be an electron beam, **, etc. for resistance heating trenches, vapor deposition using a cluster ion beam is best in combination with the next step. Next, A becomes the 272477th layer.
Deposited by cluster ion beam. When this sample is heat treated in Ar for 5oots for 20 minutes, perfect ohmic properties are obtained. 200-300 at low temperature
Good electrical resistance can be obtained even after heat treatment at ℃ for 10 minutes. In addition, the I-digging property is good using both thermocompression bonding and ultrasonic-digging methods, and when it is graded with A+a@ of 50μ solution, it has a tensile IJ of 1 degree or more of 100gr.

When the A-film is deposited by ordinary resistance heating or electron beam evaporation, the tensile strength tf is 20 gr or less, and the O
In other words, there are many samples in which the - mark comes off with just a slight touch. The film thickness of Zm and Au is P
It varies depending on the impurity concentration of the layer, the heat treatment temperature f, and the treatment time.
Under the conditions of 1500℃ and 20 minutes, %Z! 1111
Thickness is 5001~1000X% A1 film thickness is 3000~5
0001 is sufficient.

Example 2 Examples 1 and 1) 9. wl was formed on the same GaP substrate by the same means, heat treated, and indexed. However, Au1ll and Mu are changed to Muil and kA lines, respectively. Furthermore, under the conditions of the cluster ion beam, the same results as in Example 1 were obtained regarding the bending and buttock properties of the sample. The film thickness is also almost the same.

Example 3 For the N GaP crystal substrate surface with a concentration on the order of 10"cs-", a Sl film or a G film was applied as an electrical layer (instead of a Zn film) using a cluster ion beam. Make an appearance,
- To form the A-film or MutH as the binder layer using an ion beam at 0115°C,
After heat treatment in Ar for 10 minutes, the ohmic property is completely removed. Although the film thickness was evaluated as being good and almost the same results as in Example 1 were obtained, the optimum value of the film thickness was slightly different.

all or G@ membranes are at 200X~6001, A%I
Or MutM is 3000 to 50001-t''.

lI example-4 10'31" machine 0'm1ll t'4 riP If
The same effect was obtained in GaAm and uN type Gaps crystals. That is, by forming a laminate of a Tet;j Z m film and Au [or ht 61 Talistar ion P5] on p @ GaAs ilK, it is possible to satisfy both the ``O'' and ``Ndiff'' characteristics. 11.

Next, the reason why good results can be obtained by the present invention will be described below. First, a schematic diagram of the cluster ion beam is shown in Figure 2. Since this beam forming method is well known, it will be briefly explained. An evaporation source 22 is placed opposite to a substrate 21. Substrate 21
A PN junction is formed with a GaP substrate, an evaporation source 22 and a kiZ n + 81 * G
It is a single metal evaporation source such as @, MuurkL, etc. In the case of a laminated structure, the evaporation source 21 can be easily replaced by rotating the evaporation source 22. The evaporation source 21 consists of a heat-resistant metal 723 and a heater 24, and each metal can be melted and heated to the evaporation temperature. . There is an injection nozzle 21 in the hole 121, and evaporated metal comes out from the nozzle 2I as well.

The evaporated metal can be adiabatically expanded due to the Katsura shape of the nozzle, the internal pressure of the large tube, and the surrounding pressure, and several hundred neutral atoms form a cluster-like atomic group vapor. I can do it. Before the atomic group reaches the substrate 21, the ionizing electron emitting filament 26 ionizes about one O atom in the atomic group, and the accelerating electrode J1 ionizes them to accelerate nine atomic groups, that is, Tarastar ions. , substrate 11f
Cg center to form a film 21 on the substrate surface. The advantage of this Tarastar ion beam evaporation method is that if the conditions are properly selected, it is possible to form a single crystal film in 1i. That is, factors such as the material of the substrate, the surface orientation, the temperature, the purity of the evaporation source material, the evaporation temperature, the ionization filament current, the accelerating voltage, the degree of vacuum, etc. may be controlled.

In the case of the embodiment of the present invention, Zll, 8 is added to take into account the ohmic and ri characteristics, and in order to crystallize the 51 or Aj film.
1. After forming a thin metal film of Ga, immediately apply Ga on the surface.
Since w119 causes muL1M to grow, the phenomenon becomes complicated.
>, it is not possible to treat each factor separately. However, as an average value in the example, GaP★9 requires careful chemical and physical cleaning of the G1S substrate, and I
Heating to around 300°C in a vacuum of 0-' Torr or less,
0 to 100 for ionizing Zn or 81 or G membrane
mA and 0 to S kVt as an accelerating voltage are applied to form a cluster ion beam on the substrate surface, and immediately after the vacuum is broken, the roots are replaced to form a MU or MU L film. The conditions were such that the substrate temperature and degree of vacuum were constant, 15001 A was applied to the ionization filament, and an accelerating voltage of 8 kV was applied.

As mentioned above, the properties of this sandal are opaque, resilient, and indestructible, but the properties of the film alone are not. Ta. Since it is not possible to completely eliminate the influence of the crystal transfer, ohmic, and reflective films on the substrate itself, we use KU or MTLI formed by cluster ion beam and MUT or AA film formed by ordinary resistance heating or electron beam evaporation. The most reliable data is the comparison with As a result, the film produced by the conventional method is a complete collection of microcrystals, and a signal from a single crystal can be detected in its entirety, and an infinite number of grain boundaries naturally exist within the film. On the other hand, the film made of cluster ion C-5 is single crystal/
9-1/ appears clearly, there is almost no microcrystalline signal, and it can be said that there are almost no grain boundaries in the film. However, when viewing the field of view, the orientation of the crystal changes somewhat and becomes rounded, and a completely defect-free crystal film does not grow. However, it shows sufficient ability to improve the bending characteristics. This is because the film is crystallized, the grain boundaries are extremely small, and the movement of Qa is reduced. The reason why the rate of diffusion movement in the film and the bulk differs by more than two orders of magnitude is because the presence of grain boundaries differs by more than two orders of magnitude), and migration occurs at the grain boundaries where they are most mobile. .

In addition, in the above, only examples for GaP%GaA-substrates have been described.9) Other compound semiconductors.

For example, ImP%Iamb%GaN etc. or a mixed compound semiconductor, for example GaAjmu-1f mGaAjA
s fathom K Can be used for 4 times, can also be used as an ohmi, layer, 8m,
Of course, films such as I, Ag, B, etc. can also be used. In addition, it is not necessary for these layers to be a single substance, and even an omniscient alloy film can sufficiently function as a pericarp. Another aspect of the present invention is a monolithic Gm
It can also be fully utilized for As-IC, optical IC, etc.

In these cases, the above-mentioned one-inning layer also serves as a wiring layer, and this wiring layer has a low resistance due to single crystallization, so excellent device characteristics can be obtained. Further, as a method for obtaining a single crystallized film, in addition to the cluster ion beam evaporation method, molecular beam epitaxy method, ion evaporation method in ultra-high vacuum, etc. can also be used.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a compound semiconductor light emitting device, and FIG. 2 is a conceptual diagram of a cluster ion beam evaporation method used in an example of the present invention. J...Ni1GaA easy (or GaP) substrate, 2...
- P-type crystal layer, 3, 4... electrode. Patent attorney Suzue Takehiko 11 Figure 2 293-

Claims (4)

[Claims] (1) In a Rin-V group compound semiconductor device having f'Nli junction, the PGM layer and Nl constituting the PN junction
One pole of one layer is composed of an electrical conductor layer showing good electrical contact and an inducting layer which also serves as a ninth interconnection layer to be combined with the outer conductor layer, and the conductor layer is made of a single layer. A semiconductor element characterized by being composed of a crystalline metal film. (2) The semiconductor device according to claim 1, wherein the single-crystal gold film layer is formed by a cluster ion beam deposition method. (3) Oden, rear layer is Zm, Gm ral t8
The semiconductor device according to claim 1, which is a single metal or alloy layer consisting of m*I@*muC1B. (4) The semiconductor device according to claim 1, wherein the single crystal metal film is AiI or Mut.