JPH0121556Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention relates to an improvement of an orientation flat formed on a solar cell element substrate, particularly a semiconductor substrate thereof.

<Prior art> Semiconductor substrates for manufacturing semiconductor substrates are often cut into wafer shapes from silicon single crystal ingots produced by crystal growth, and then subjected to appropriate surface polishing etc. to be used in the semiconductor manufacturing process. has been done.

Single-crystal silicon substrates are also used in single-crystal solar cell elements, but the crystal orientation of the substrate is chosen so that the wafer surface is <100>. That is <100>
By selecting an etching solution, the surface of the substrate can be processed into sawtooth-like irregularities, which serves to suppress reflections on the light-receiving surface of the solar cell, thereby increasing photoelectric conversion efficiency.

Since a silicon substrate cut out from a single crystal ingot has a disk shape, a part of the circular substrate 1 is cut out in a straight line as an orientation flat 2 for use in indicating the orientation and alignment of the substrate. . The orientation flat 2 is generally (011) formed. When a semiconductor device is manufactured using a silicon single crystal substrate having the above <100> plane, if the direction of cracks that occur during the manufacturing process is examined, the direction will be perpendicular or parallel to the orientation flat 2. ing.

However, as mentioned above, when producing solar cell elements using <100> silicon single crystal substrates, recently, for reasons such as cost reduction, screen printing technology is used to apply electrode material to the substrate surface. The electrodes are formed by firing. When forming electrodes by screen printing in this way, the printing direction is chosen to be perpendicular or parallel to the orientation flat in consideration of workability, etc., and this printing direction prevents cracking of the semiconductor substrate. Because the direction is the same, cracks occur during work, causing a decrease in yield.

<Purpose of the invention> The present invention improves the drawbacks of the conventional semiconductor substrates described above and provides a solar cell element substrate that can prevent cracking of the solar cell element substrate that is likely to occur during the screen printing process for forming electrodes.

<Embodiment> In FIG. 1, a silicon single crystal semiconductor substrate 3 exhibiting a predetermined conductivity type of p or n is processed to have a <100> plane orientation. For the semiconductor substrate 3,
[011] An orientation flat 4 is formed on the end face at a predetermined angle θ within a range of 90° or less, preferably 45°. That is, the orientation flat 4 is formed in an intermediate direction, avoiding the direction in which the semiconductor substrate 3 is likely to break.

In order to make the semiconductor substrate 3 a high-efficiency solar cell element, fine sawtooth-like irregularities are formed on at least the polished light-receiving surface. To process the unevenness, a <100> silicon single crystal substrate is processed using NaOH or
Formed by exposure to an alkaline aqueous solution such as KOH.

A pn junction is formed on the surface of the silicon single crystal substrate 3 having an uneven surface so as to have a photoelectric conversion function. The p-n junction is heated in an impurity atmosphere exhibiting conductivity opposite to the p- or n-type conductivity exhibited by the semiconductor substrate 3, or heated in a solution that can generate an oxide and become an antireflection film through heat treatment. It is formed by adding an impurity exhibiting opposite conductivity in advance, applying this solution to the surface of the semiconductor substrate and heating it, and converting the surface to the opposite conductivity type while heating.

On the surface of the semiconductor substrate on which the p-n junction has been formed, p-side and n-side electrode materials are printed by screen printing, and electrodes in ohmic contact with the semiconductor substrate are formed by firing, thereby forming a solar cell element.

The process of screen printing the electrode material is aligned by the orientation flat 4 of the semiconductor substrate, so the printing direction is different from the conventional process and is performed in the direction of arrow A or B. Therefore, the semiconductor substrate is almost never cracked.

<Effects> According to the present invention, the orientation flat formed by cutting out the periphery of the (100) silicon single crystal circular substrate is shifted from the (011) direction, thereby making it possible to improve semiconductor devices. Cracks and damage to the substrate that occur during the manufacturing process can be prevented, and the yield of solar cell element substrates can be increased.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention;
FIG. 2 is a plan view of a conventional semiconductor substrate. 3...Silicon crystal semiconductor substrate, 4...Orientation flat, A, B...Screen printing direction.

Claims (1)

[Scope of utility model registration request] From 011 plane to silicon single crystal substrate with 100 planes
An orientation flat is formed at a position shifted by a predetermined angle within 90 degrees, and minute irregularities are formed on the light receiving surface of the 100 plane, and an orientation flat is formed at a position shifted by a predetermined angle from the 011 plane. 1. A solar cell element substrate comprising screen-printed electrodes printed in vertical or parallel directions.