JPH05243593A - Manufacturing method of ohmic contact between metallic foil and semiconductor material - Google Patents

Abstract

PURPOSE: To realize a large-scaled area opto-electric transducer element array, by compressing a metallic material and a semiconductor material in a limited period, with limited pressure, and temperature higher than 400 deg.C between a first projecting face and a second face. CONSTITUTION: A back side connection foil 407 and an additional polyester material 405 are formed in a P-type area 401, and electrical insulation is formed against an N-type surface area 406. Then, the connection foil 407 is supported so as not to be moved up and down, electrical connection 408 is formed between the P-type area 401 and the foil 407 by applying almost 5 pound pressure to each sphere about at 260 deg.C, and a polyester sheet is connected in a method for constituting a layer 413 as substantially continued matrix supporting materials. Therefore, a solar energy transforming element with a large area for electrically changing incident energy into potential can be realized by using this method.

Description

Detailed Description of the Invention

The present invention relates to a large-scale photoelectric conversion device which can be manufactured at a low temperature, is low in price, and can tolerate some circuit malfunctions, and a manufacturing method thereof.

[0002] With the increasing chances of knowing that we have limited biofuel resources remaining, and also due to the growing need to develop renewable and effective energy resources, a considerable amount of research has taken place in the development of solar energy. Is being done against.

A significant problem with the development of opto-electrical converters has been the cost of materials for semiconductor converters. This semiconductor material, typically silicon, uses a PN junction to create a potential when exposed to light. However, in order to operate correctly, typical systems require large amounts of semiconductor material to obtain a relatively small area. A further problem encountered is that the thickness of the semiconductor material must be able to withstand the tensile forces of the bend, and that it is designed to have the minimum softness necessary for normal operation or use. It must be a unit cell. Third is the issue of tolerance to defects in large area cell arrays. In other words, when only one short circuit occurs, the generated electricity may escape through the shorted cell and affect all the units.

One of the solutions to these problems is 19
60th M.M. B.
Suggested in a paper by Prince titled "Large-Scale Silicon Solar Cells." He suggests using a semiconductor matrix with plastic spheres. However, problems have arisen with making electrical connections. See Section G, page 9, 209, chapter 9, semiconductors and semimetals, by Harold Hobel for an example.

Accordingly, it is an object of the present invention to provide a large area opto-electrical conversion element array with a minimum of semiconductor material.

A second object of the present invention is to provide a flexible array of photoelectric conversion elements which can be bent or deformed without being damaged even when manufactured in a thin film form.

A third object of the present invention is to provide a large area light which is tolerant to a malfunction due to a short circuit, which can handle some short-circuited cells without degrading electrical performance. To develop an array of electrical elements.

A fourth object of the invention is also to provide a low cost manufacturing process for making large area optoelectronic device arrays in which the required maximum temperature is below 400 ° C.

Another object of the invention is to add very little additional cost to complete the assembly,
It is to provide a continuous interconnect system that is connected during the manufacturing process of placing semiconductor spheres and is coplanar with the array.

In accordance with the present invention, a radiant energy conversion system can be provided that includes a matrix support member having a metal foil. The metal foil has first and second layers of polymeric material disposed on opposite sides thereof and has holes through the foil at spaced locations in the support member. A substantially spherical semiconductor cell is formed in each hole, and each cell has a P-type region and an N-type region. The N-type regions contact the metal foil in their respective holes and conductive means are formed along one side of the support member to connect the P-type regions of each cell. Each connection to the P-type region consists of an electrode with a predetermined resistance value.

Furthermore, the plurality of matrix-supported spherical assemblies are connected in series with each other, the connections being coplanar with the assembly and not substantially greater than the thickness of the assembly. It is provided to have thickness.

A method of making a radiant energy conversion element is described in N
Doping the surface of a plurality of semiconductor spheres of P-type material with a mold-type doping material, providing a metal foil between two layers of polymeric material, and piercing the foil to mount these spheres Put a sphere in the process and this hole and make a metallic foil,
Making electrical connection to the N-type surface region of each sphere, surrounding and sealing the sphere, and removing the first side of the foil of the sphere to form a P-type second surface The process includes exposing the regions and making ohmic contacts in each P-type region with a predetermined resistance.

The method may also further include the step of adding another layer of plastic material to the foil assembly of the sphere to increase the thickness of the matrix-supporting layer to approximately the average diameter of the sphere.

Each step in the above method is carried out at a temperature below 400 ° C.

Furthermore, the sphere foil assembly is electrically interconnected continuously such that the thickness of successive interconnects does not exceed the average diameter of the sphere.

The present invention will be described in detail below with reference to the drawings.

Referring first to FIG. 1, there is shown a perspective view of a portion of a completed transducer array in which several silicon spheres 110 are provided on top of the completed assembly. .. The metal foil 103 forms an electrical connection to the sphere on the N-type surface area shown at 104. The metal foil 105 is electrically connected to the P-type region indicated by 109. The top portion of the sphere 106 is embedded in the matrix assembly, leaving a small portion of the top of the sphere in the air. The plastic layer 102 is made of a polyester material and is transparent to incident light and allows it to pass through. The plastic layer 101 is also made of polyester material and is shown at 107 to have a cut in the metal foil 105 and the metal foil 103, both a matrix support and an electrical insulator. This provides a perfectly conductive sphere 111 to provide coplanar electrical interconnection between the assembly parts of the matrix,
Serial interconnections are possible. Note that the plastic layer 102 can be removed after making the ohmic contact in the P-type region.

In another embodiment, metal wires are placed in place of the spheres 111 instead of the spheres 111 to provide electrical interconnection between the upper foil 103 and the lower foil 105.

Referring now to FIG. 2, FIG. 2a shows a cross sectional view of a polymer foil thin film. 203 is a thin film provided between two layers of polyester sheets 202 and 201, each having a thickness of approximately 2 mils (0.127 mm).
It is a mil (0.127 mm) thick aluminum foil. FIG. 2b shows the thin film after the step of making holes, and FIG. 2c shows the thin film after placing the semiconductor sphere 204 in the hole. Prior to insertion, the sphere 204 has N-type dopant regions diffused over the surface 205, consisting essentially of P-type regions. By inserting into the hole, an electrical connection is formed between the N-type surface region 204 and the aluminum foil 203. The spheres can be centered using a pressure process that applies pressure to the sphere / foil / plastic assembly between the relatively soft surfaces to position the spheres approximately in the center of the holes made in the membrane.

Referring now to FIG. 3, FIG. 3a shows the result of performing a second pressurizing step in which a layer of plastic material surrounds the sphere 301 to create a seal. this is,
This is done by applying a pressure of approximately 0.1 pounds for each sphere at a temperature of approximately 250 ° C. Thus, the polyester material forms a seal at 301 and adheres tightly to the sphere.

FIG. 3b is a cross-sectional view of the sphere after an etching step in which an N-type selective etch is performed on one side of the matrix of firmly anchored spheres. This removes the surface material from the sphere, leaving the N-type surface material 302 connected to the metal foil, and the P-type region 303 undergoes the next processing step.

Referring to FIG. 4, the assembly of FIG. 4a is upside down and a backside connection foil 407 is formed in the exposed P-type region of the surface. Additional polyester material 405 is formed to provide electrical isolation to N-type surface region 406. An electrical connection to the P-type region 401 applies pressure to the entire matrix and is formed at position 408. An additional polyester sheet is formed over cell 411 and a surface-pressed sheet 410, such as a Teflon coated 409 stainless steel foil, is provided to maintain symmetry during the compression process. The Teflon coating 409 is provided so that it does not bond to the N-type surface region of the sphere and is easy to remove after the final compression bonding step. In the compression bonding step, the connection foil 407 is supported on a desired surface so as not to move at least in the vertical direction.

In FIG. 4b, at a temperature of approximately 260 ° C., approximately 5 pounds of pressure is applied to each sphere to form an electrical connection between the P-type region and the foil, with layer 413 essentially continuous. The polyester sheets are bonded together in such a way as to be a matrix support material. When a 14 mil (0.3556 mm) diameter sphere is bonded to a 0.5 mil (0.127 mm) aluminum foil, in this example 0.5 for each sphere.
The use of pressures from pounds to 10 pounds has been effective, however, sufficient pressure to deform the metal significantly is required to create a repeatable connection. The silicon spheres can also crack if excessive pressure is applied.

The light striking the surface reaches the junction 414 and creates an electrical potential between the foils 412 and 407. The polyester sheet 413 is essentially transparent to light and also insulates the N-type regions from the P-type connection regions. Further, the uppermost foil 412 acts as an optical reflection plate that causes irregular reflection, so that the sphere 414 can receive light more easily. This is possible by directing the matte side of the foil towards the light source.

With the array exposing the entire upper hemisphere of the semiconductor cell and bringing the spheres in close proximity, the effective P-N junction area exposed to light is larger than the planar surface area of the array.

The interconnection of adjacent matrix assemblies is
Using the method of interrupting the foil shown at 107 in FIG. 1 and using a globally diffused N-type cell or a globally conductive sphere 111 which acts as a short circuit between the connecting foils. And easily formed. Furthermore, in order to form a short-circuit connection between the foils, it is possible to use short-circuiting spheres, such as aluminum or nickel balls, or wires of a certain length having a diameter approximately equal to the diameter of the sphere.

Referring to FIG. 5, a method of internally connecting adjacent assemblies is shown to form a series electrical connection. The foil 51 connects to the N-type region of the sphere 53, and the sphere 5
4 is shown connected to the P-type region. 52 in series
Indicated by. Polyester insulation and support material layer 5
5 surrounds the continuous internal connection substantially seamlessly.

The foil used in the examples of this specification is intended to be a metal sheet having a thickness of 6 mils (0.1524 mm) or less and having special stretchable properties. The foil used in this example is usually wound on a roll, which is usually used for cooking or wrapping things.
Various common 3 mil foils with a thickness of from 1 to 2 mils (0.0127 to 0.0508 mm). Aluminum alloys are also effective.

By using the above method, it is possible to manufacture a large-area solar energy conversion device that converts incident energy into an electric potential. In the process of the present invention, an element array having a wide area can be formed at a relatively low temperature, so that it has a great advantage that the cost is low and the circuit is extremely tolerant to short circuits. Therefore, I am convinced that a more economical energy conversion device could be provided.

While this invention has been described and illustrated with respect to particular embodiments, it is believed that variations and modifications do not depart from the spirit and principles of the invention presented herein.

In addition to the above description, the following items will be further disclosed. (1) a. A step of forming a first convex surface and a second surface and giving one of the above surfaces semiconductor characteristics, and b. Between the first convex surface and the second surface Compressing the metal foil at a temperature lower than 400 ° C. for a controlled period and pressure, and forming an ohmic contact with a semiconductor material having a predetermined resistance value.

(2) The ohmic contact of paragraph 1, wherein the method further comprises the step of maintaining the controlled pressure for a period of time during which the temperature of the first convex surface, the second surface and the metal foil is lowered. How to form.

(3) A method of forming an ohmic contact according to the first item, wherein the semiconductor material has P-type conductivity.

(4) A method of forming the ohmic contact according to the first aspect, wherein the metal foil contains aluminum.

(5) a. A semiconductor material; b. A metal foil connected to the semiconductor material, which has a predetermined electrical resistivity and physical bonding characteristics of the foil to the semiconductor material. A semiconductor device having a connecting metal foil.

(6) The semiconductor of paragraph 5 wherein the semiconductor device is further a polymeric material located at and around the location of the connection and having improved foil physical bond characteristics to the semiconductor material. apparatus.

(7) The semiconductor device according to the fifth item, wherein the semiconductor material contains P-type silicon.

(8) The semiconductor device according to item 5, wherein the metal foil contains aluminum.

(9) It is an object to manufacture an ohmic contact between a semiconductor material and a metal foil capable of guaranteeing sufficient mechanical strength without deteriorating electrical performance. Therefore, between the first convex surface and the second surface, the metal material and the semiconductor material are pressure-bonded under a controlled period and pressure and a temperature of 400 ° C. or less to form an ohmic contact therebetween.

[Brief description of drawings]

FIG. 1 is a perspective view showing a part of a radiant energy converter.

FIG. 2 is a diagram of consecutive processing steps, of which (a)
Figure 3 is a cross-sectional view of a foil-plastic thin film. (b) is a cross-sectional view of the plastic-foil thin film after the holes are punched. (c) is a cross-sectional view of the foil-plastic thin film after being doped.

FIG. 3 is a diagram showing steps added to a processing step,
(a) is a cross-sectional view showing the foil-plastic thin film and the sphere after sealing the sphere with plastic. (b) is
FIG. 4 is a cross-sectional view showing a foil-plastic thin film and a sphere with the sealed N-type surface material portion removed.

FIG. 4 shows a cross section of an energy conversion device of an embodiment,
(a) is a cross-sectional view of the completed assembly before the final high thermocompression bonding process is performed by providing the second metal foil. (b) is a sectional view of a completed cell in which two foils formed in the completed radiant energy converter are connected.

FIG. 5 illustrates a selectable embodiment of the present invention showing a selectable method of interconnecting adjacent matrix assemblies.

[Explanation of symbols]

 401 P-type region 404, 412 Metal foil 406 N-type region 407 Connection foil

Claims (4)

[Claims] 1. A step of forming a first convex surface and a second surface, wherein one of the surfaces has semiconductor characteristics, and b. A step of forming the first convex surface and the second surface. And compressing the metal foil at a temperature lower than 400 ° C. for a controlled period of time and at a temperature lower than 400 ° C. to form an ohmic contact with a semiconductor material having a predetermined resistance value. 2. The method further comprises the first convex surface,
The method of forming an ohmic contact of claim 1 including the step of maintaining the controlled pressure during the period of lowering the temperature of the second surface and the metal foil. 3. The method for forming an ohmic contact according to claim 1, wherein the semiconductor material has P-type conductivity. 4. The method of forming an ohmic contact of claim 1, wherein the metal foil comprises aluminum.