KR100416741B1 - Rear locally sintered silicon solar cell - Google Patents

Abstract

PURPOSE: A rear locally sintered silicon solar cell is provided to omit a conventional oxidation process and eliminate the necessity of expensive equipment like an oxidation furnace by simultaneously forming a titanium oxide layer and a silicon oxide layer on the front and rear surfaces of a silicon substrate. CONSTITUTION: A p-type silicon substrate(21) is prepared. An n¬+ semiconductor layer(24), a SiO2 layer(22') and a TiO2 layer(23') are sequentially formed on the front surface of the substrate having a pyramid structure. A plurality of line-type front surface electrodes(25) are formed of a conductive metal, formed in parallel with the front surface of the substrate and separated from each other by a predetermined interval. An n¬++ semiconductor layer(26) is formed under the front surface electrode. A rear surface electrode(29) is formed on the planarized rear surface of the substrate, composed of a silicon oxide layer, a titanium oxide layer and a conductive metal. A locally diffused p¬+ semiconductor layer(27) is diffused to the inside of the rear surface of the silicon substrate. A conductive metal layer(28) is formed in a predetermined region between the titanium oxide layer and the rear surface electrode on the rear surface of the silicon substrate.

Description

Rear Part Sintered Silicon Solar Cell

The present invention relates to a backside partially sintered silicon solar cell, and in detail, a titanium oxide film on the front and back of the silicon substrate, and partially diffused p on the back of the substrate.⁺brother By forming a semiconductor layer and forming a front electrode which is distinct from a conventional recessed electrode type silicon solar cell, a rear part sintered type silicon solar cell having a titanium oxide deactivated emitter insulating film having low manufacturing cost and excellent energy conversion efficiency ( TiO₂passivated Emitter, rear Locally Sintered silicon solar cell (TELS).

The solar cell uses photovoltaic power of a semiconductor and is made by combining a p-type semiconductor and an n-type semiconductor. When light enters the junction (pn junction) of the p-type semiconductor and the n-type semiconductor, negative charges (electrons) and positive charges (holes) are generated in the semiconductors by the light energy.

The electrons and holes generated by the light energy move to the n-type semiconductor side and the P-type semiconductor side by the internal electric field, and are collected at both electrode portions. Connecting these two electrodes with wires allows the current to flow and can be used as power from the outside.

Solar cells can be classified into screen printing solar cells (SPSCs) and buried contact solar cells (BCSCs) according to the shape of the electrodes. Here, the SPSC is generally easy to manufacture, but the energy conversion efficiency is small.

On the other hand, BCSC can be manufactured at almost the same manufacturing cost as SPSC, and energy conversion efficiency is higher than that of SPSC.

1 is a view showing a cross-sectional structure of a typical BCSC.

Referring to this, the n ⁺ type semiconductor layer 12 and the silicon oxide film 13 are sequentially formed as an oxide film on the p-type silicon substrate 11, and the front electrode 17 is formed in a groove deep into the substrate. Formed.

The p ⁺ type semiconductor layer 15 and the back electrode 16 are sequentially formed on the back surface of the silicon substrate 11.

By the way, BCSC having the structure as described above has the following problems.

First, in order to form a silicon oxide film on the front and back of the silicon substrate, an expensive oxidation furnace must be provided and a long time high temperature oxidation process is required. In addition, since hydrogen gas is commonly used in such an oxidation process, there is a risk in manufacturing process.

Second, in order to form the front electrode, deep grooves must be formed in the entire surface of the silicon substrate. In addition, expensive equipment such as a laser scriber, etc. are required in the process of forming the grooves, and manufacturing time is required.

Third, since the oxide film and the rear electrode are sequentially formed on the back surface of the silicon substrate on which the pyramid structure is formed, dislocation defects are relatively large, and the back reflection effect obtained by forming the aluminum layer on the back surface of the silicon substrate is low.

The technical problem to be achieved by the present invention is to solve the above problems by performing a spray deposition process of titanium oxide instead of the conventional oxidation process to form a titanium oxide film on the front and back of the silicon substrate, respectively, and to form a partially diffused emitter layer on the back of the substrate At the same time, it is to provide a backside partial sintered silicon solar cell having a titanium oxide deactivated emitter insulating film having excellent energy conversion efficiency at a reduced manufacturing cost by forming a front electrode different from a conventional recessed electrode type silicon solar cell.

1 is a view showing a cross-sectional structure of a conventional recessed electrode type silicon solar cell,

2 is a view showing a cross-sectional structure of a backside partially sintered silicon solar cell according to the present invention.

* Description of the symbols for the main parts of the drawings *

11, 21 ... p-type silicon substrate 12, 24 ... n ⁺ type semiconductor layer

13, 22, 22 '... silicon oxide (SiO ₂ ) film 15 ... p ⁺ type semiconductor layer

16, 29 ... rear electrode 17 ... front electrode

23, 23 '... titanium oxide (TiO ₂ ) film 25 ... line type front electrode

26 ... n ⁺⁺ type semiconductor layer 27 ... partially diffused p ⁺ type semiconductor layer

28 ... conductive metal layer

An object of the present invention is a p-type silicon substrate; N sequentially formed on the entire surface of the substrate on which the pyramid structure is formed⁺Semiconductor layer, silicon oxide (SiO₂Film and titanium oxide (TiO)₂)membrane; A plurality of line type front electrodes formed on the front surface of the substrate to be equally spaced apart at predetermined intervals and made of a conductive metal; N formed under the front electrode⁺⁺Type semiconductor layer; A back electrode made of a silicon oxide film, a titanium oxide film and a conductive metal sequentially formed on the back surface of the planarized substrate; Partial diffusion p formed by diffusion into the back surface of the silicon⁺brother A semiconductor layer; And a conductive metal layer formed in a predetermined region between the titanium oxide film on the back surface of the silicon substrate and the back electrode.

The conductive metal is selected from nickel (Ni), copper (Cu), aluminum (Al), silver (Ag), palladium (Pd), titanium (Ti) and oxides thereof.

The partial diffusion p⁺brother It is preferable that the semiconductor layer is made of aluminum (Al), because in the case of diffusing other p-type impurities such as boron (B) instead of aluminum, expensive diffusion equipment is necessary, which increases manufacturing costs. .

Hereinafter, with reference to FIG. 2, a backside partial sintered silicon solar cell according to the present invention will be described.

N on the front surface of the p-type silicon substrate 21 on which the random pyramid structure is formed.⁺brother The semiconductor layer 24, the silicon oxide film 22 ', and the titanium oxide film 23' are sequentially formed.

The silicon oxide film 22 'and the titanium oxide film 23' are sequentially formed by spray deposition of a compound containing titanium and oxygen on the entire surface of the silicon substrate, followed by spray deposition. In this case, as the compound containing titanium and oxygen, tetraisopropyl titanate, titanium tetrachloride, or the like may be used. Here, the thickness of the titanium oxide film and the silicon oxide film is changed depending on the experimental conditions such as deposition conditions, the silicon oxide film is generally formed thinner than the titanium oxide.

The front surface of the silicon substrate 21 is formed to be equally spaced apart at predetermined intervals, and a plurality of line type front electrode 25 made of a conductive metal is formed. The front electrode 25 collects current generated in the pn junction silicon substrate and contacts the external terminal, and is formed by plating a conductive metal by an electroless plating method or an electroplating method capable of selective plating. In particular, when plating copper (Cu) as the conductive metal, an electroless plating method is used, and when plating silver (Ag) as the conductive metal, an electroplating method is preferably used. At this time, before plating copper or silver, it is preferable to first form a nickel (Ni) plating layer as an intermediate | middle layer for improving the adhesive force of this metal plating layer and a to-be-coated object.

An n ⁺⁺ type semiconductor layer 26 for reducing the electrical contact resistance between the plurality of line type front electrodes 25 and the silicon substrate 21 is formed as shown in FIG.

A silicon oxide film 22, a titanium oxide film 23, and an aluminum layer 29, which is a back electrode, are sequentially formed on the back surface of the planarized silicon substrate 21. The partial diffusion p obtained by partial diffusion of aluminum using a metal mask in the back surface of this silicon substrate 21.⁺brother The semiconductor layer 27 is formed.

A conductive metal layer 28 is formed in a predetermined region between the titanium oxide 23 and the back electrode 29. This conductive metal layer is simultaneously produced during the formation of the front electrode 25.

In the silicon solar cell of the present invention having the structure as described above, the titanium oxide film formed on the front and rear surfaces of the silicon substrate simultaneously acts as an antireflection, insulation and protective film and also acts as a mask during the diffusion process. In addition, a partial diffusion P ⁺ type semiconductor layer is formed on the backside of the planarized silicon substrate, thereby reducing potential defects on the backside of the substrate and reducing recombination of minority charge carriers, thereby improving energy conversion efficiency. In addition, when the front electrode is formed, grooves are not deeply formed into the substrate as in the prior art, and high-temperature oxidation processes are not required when forming the oxide film, so expensive equipment such as laser equipment or an oxidation furnace is unnecessary, thus greatly reducing manufacturing time and cost. can do.

According to the present invention, the following effects are obtained.

First, by using a spray deposition process of a titanium oxide film, it is possible to simultaneously form a titanium oxide and a silicon oxide film on the front and back of the silicon substrate. The double film thus formed simultaneously serves as an antireflection film, an insulating film, and a protective film. Therefore, the conventional oxidation process can be omitted, thereby simplifying the manufacturing process, thereby reducing manufacturing time and reducing manufacturing costs by eliminating the need for expensive equipment such as an oxidation furnace.

Second, unlike conventional recessed electrode type silicon solar cells, expensive grooves, such as laser scribers, are unnecessary and manufacturing time is not required because the grooves do not need to be manufactured deeply into the substrate when the front electrode is formed.

Third, the open voltage of the battery is improved by reducing the recombination and potential defects of carriers in the back of the silicon substrate by forming a partially diffused p ⁺ type semiconductor layer on the back of the planarized silicon substrate. As a result, the energy conversion efficiency is improved.

Fourth, in the formation of the partially-diffused p ⁺ type semiconductor layer, a conventional photolithography process is used, whereas the present invention uses a vacuum deposition method using a metal mask, which is easy to manufacture and saves manufacturing time. have.

Claims (3)

p-type silicon substrate; An n ⁺ -type semiconductor layer, a silicon oxide (SiO ₂ ) film and a titanium oxide (TiO ₂ ) film sequentially formed on the entire surface of the substrate on which the pyramid structure is formed; A plurality of line type front electrodes formed on the front surface of the substrate to be equally spaced apart at predetermined intervals and made of a conductive metal; An n ⁺⁺ type semiconductor layer formed under the front electrode; A back electrode made of a silicon oxide film, a titanium oxide film and a conductive metal sequentially formed on the back surface of the planarized substrate; Partial diffusion p formed by diffusion into the back surface of the silicon⁺brother A semiconductor layer; And A backside partially sintered silicon solar cell comprising a conductive metal layer formed in a predetermined region between a titanium oxide film on a back surface of a silicon substrate and a back electrode. The method of claim 1, wherein the conductive metal is selected from the group consisting of nickel (Ni), copper (Cu), aluminum (Al), silver (Ag), palladium (Pd), titanium (Ti) and oxides thereof. Rear part sintered silicon solar cell. The method of claim 1, wherein the partial diffusion p⁺brother A backside partially sintered silicon solar cell, wherein the semiconductor layer is made of aluminum.

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