LT6449B - Point contact device of low resistance - Google Patents

Abstract

The invention relates to the field of electronics concerned with development and production of semiconductor or other material devices having negative impact of spreading resistance in small area contact regions. The aim of the invention is to reduce the negative influence of a point contact in electronic devices. The purpose is achieved by replacing the continuous semiconductor layer that is located directly under the metal layer in a metal-semiconductor point contact by the array of small-radius point contacts or semiconductor columns. Thus instead of a single large-radius point contact one gets a spot of the same external area containing a series of small-radius point contacts arranged together in parallel. Such a configuration makes it possible to obtain a device having lower spreading resistance and to decrease its negative effect on electric current flow and heating of the contact area, as well as on electromotive force formation under the action of electromagnetic radiation.

Description

TECHNICAL FIELD OF INVENTION

The present invention relates to the field of electronics related to the design and manufacture of devices for semiconductor or other materials which exhibit negative point contact effects in areas of small area contact.

State of the art

In the semiconductor electronics industry, it is relevant to develop electronic devices of the smallest possible dimensions; the dimensions of the metal semiconductor contact are reduced accordingly. However, reducing them increases the resistance of the structure. This results in increased electrical losses in the electrical circuit, undesirable heating of the contact environment and the structure itself. In addition, electromagnetic fields in a point-contact environment may induce an electro-driving signal, which in some cases may be undesirable or even harmful.

Cylindrical point contact metal-semiconductor shielding resistance is expressed as:

(D

Here, p is the specific impedance of the semiconductor [Ω-m], or ₀ is the contact radius [m].

In order to reduce the point contact impedance according to formula (1) it is possible to:

• reduce the resistivity of the semiconductor, or • increase the contact area.

For this purpose, the contact area may be simply alloyed (European Patent 0033876), an additional continuous conductive semiconductor layer (U.S. Pat.

For light emitting diodes, photodiodes, solar cells, it is important to create light fluxes that obstruct electrical contact, but with minimal loss of electrical current. One way is to use light-transparent, electrically conductive contacts, which completely avoids the point contact in the semiconductor device. Another way of forming metal-to-semiconductor contact with the smallest possible area is undesirable due to the inevitable amplification of the point resistance impedance. Therefore, electrical contacts are made in the configuration of thin combs (as in solar cells) or with additional fingers that find conditions for a more even flow of current (see, for example, European Patent 2337096). In order to obtain an even distribution of the electric current in the LED, U.S. Patent No. 6,410,943 proposes to form opposite diode point contacts so that the misalignments they produce compensate for each other.

It is suggested to apply the second electrical contact of the diode not on the other side of the semiconductor layer, but close to the point, by enclosing the latter with a tight metal ring to reduce current inequalities due to spot contact (U.S. Patent 3,387,189). Another proposed method is to form a second electrical contact, not a flat, but semiconductor capsule, the highly doped surface of which surrounds the point contact (German Patent 3710503).

U.S. Pat. The idea of a parallel connection is also used in JA V patent 200502694, but only the configuration of a multiple connection to the same contact is proposed here.

The closest analog would be a strip-shaped metal-semiconductor contact electronic device - a strip diode (S. Ashmont and A. Ring. Electric properties of small area nn + -junctions in Silicon. Lith. J. Phys., V.27, No.3, pp. 297303, 1987), in which the point contact between a small diameter circular metal and a semiconductor is replaced by a larger area narrow strip contact. The width of the strip is significantly less than its length. Such a device has a lower total electrical resistance, but has a larger contact area compared to a point contact area and, at the same time, a larger device dimension.

The essence of the invention

The object of the invention is to reduce the negative influence of the point contact on the electronic devices.

The objective is achieved by continuous contact of the metal and the semiconductor by an array of point contacts. In this way, instead of one larger radius point contact, a device of the same outer area is created, which has many small radius point contacts connected in parallel. The device of this configuration enables to obtain a lower resistance of the point contact shield and to reduce its negative influence on the current flow and heating of the point contact area, as well as the generation of electric power under the influence of electromagnetic radiation.

Drawing description of drawings

FIG. 1 is a side elevational view of a device with a point metal-to-semiconductor contact;

FIG. 2 - A device with a point contact array, with the surface of the semiconductor intact.

FIG. 3, a device where the array of semiconductor columns is fabricated in a mesadar configuration;

FIG. 4 is a device where the array of semiconductor columns is fabricated in an expansion configuration.

The parts shown in the drawings are:

- semiconductor; 2 - metal layer with outer radius ro; 3 is an array of metal layers of radius r each; 4 - Dielectric.

Description of Embodiment of the Invention

The low impedance point contact device consists of a semiconductor 1, the surface of which is formed by a point contact array located between the metal layer 2 and the continuous semiconductor 1.

The low impedance point contact device is realized in this way. On the surface of a continuous semiconductor 1, a semiconductor technology (metal deposition and chemical etching, electrochemical mating, plasmochemical etching, cultivation or otherwise) is used to create a small radius r point contact without changing the semiconductor array (Fig. 2) or forming a semiconductor array. 3 and Fig. 4). The lower part of the columns is evenly connected to the continuous region 1 of the semiconductor. The top of the columns is covered with a metal layer 2, which is needed to form the metal-semiconductor contact. The metal layer 2 is coated so that it does not reach the solid region of the semiconductor 1, which is located below the low-radius r point contact array (Fig. 2) or the semiconductor column array (Fig. 3 and Fig. 4). The metal layer can be seamless as shown in the figures. If desired, the metal layer may be formed in the form of a mesh with open cavities above the gaps between the small radius r point contacts or over the gaps between the semiconductor columns. This allows radiation (for example, light) to pass under the metal layer.

The low impedance spot contact device of Fig. 2, the low beam spot contact radius r and the low beam spot contact density (total contact area S relative to the metal layer area S _o above them) and the low impedance spot contact device shown in FIG. In Fig. 3 or Fig. 4, the radius r and the density of the columns (the total area S occupied by all column substrates relative to the area So of the metal layer above them) of the array of semiconductor arrays are chosen such that the total resistivity of the structure is less than FIG. 1 of the unmodified spot contact apparatus of Figure 1 having an area So; umbrella resistance.

The ratio of the shear impedance R _{t of the} low impedance point contact device to the unmodified point contact shield impedance R _o t, where the metal layer area So is the same in both cases, is given by:

In Equation 2, for example, selecting r / r ₀ = 0.3 and S / So = 0.7 reduces the shield impedance of the device by more than 2.3 times; o With r / r ₀ = 0.1 and S / S _o = 0.5, the shear impedance of the unit is reduced by as much as 5 times.

A low impedance point contact device may include not only a point contact between metal and semiconductor, but also other materials.

Claims (10)

Definition of the invention 1. A low-resistance point contact device, characterized in that it consists of a more electrically conductive material, a small area of islet array (3) located between the more electrically conductive layer (2) and a continuous area (1) of less conductive material while retaining it. the area of the more electrically conductive layer (2). 2. A low-resistance point contact device, characterized in that it consists of a small area of the metal islets (3) between the metal layer (2) and the region of the solid semiconductor (1) while maintaining the same area of the metal layer (2). 3. A low-resistance point contact device comprising an array of columns of less electrically conductive material located between an electrically more conductive layer (2) and a continuous area of less conductive material (1) while retaining the same electrically conductive layer (2) area. 4. A low-resistance point contact device according to claim 3, characterized in that it comprises an array of semiconductor columns located between the metal layer (2) and the continuous semiconductor (1) area, maintaining the same area of the metal layer (2). 5. A low-resistance point contact device according to claim 4, characterized in that the array of semiconductor columns is formed in the mesadarine above the continuous semiconductor (1). 6. A low-resistance point contact device according to claim 4, characterized in that the array of semiconductor columns is formed by deepening the semiconductor (1). 7. A low-resistance point contact device according to claim 4, characterized in that the array of semiconductor columns is formed by a material removal (etching) process. 8. A low-resistance point contact device according to claim 4, characterized in that the array of semiconductor columns is formed by extending the material. 9. A low-resistance point contact device according to claim 2, characterized in that the metal layer (2) is not integral but in the form of a network with open cavities above the gaps between a small area of metal islets forming the array (3). Low-resistance point contact device according to claim 7 or 8, characterized in that the metal layer (2) is not integral but in the form of a network with open cavities above the gaps between the columns forming an array of semiconductor columns.