DE1146722B - Heat treatment of semiconductor materials - Google Patents

Description

GERMAN

PATENT OFFICE

N18937VIb / 48b

REGISTRATION DATE: SEPTEMBER 20, 1960

NOTICE THE REGISTRATION AND ISSUE OF EDITORIAL: APRIL 4, 1963

In the manufacture of semiconductor materials and bodies from these materials, see the Practice often applying heat treatments, e.g. B. to separate the material from the gas phase, too its purification or processing into monocrystalline bodies. Examples of these treatments are z. B. Treatments in which a body of semiconductor material by solidification of a melt of the Material grows rod-shaped, like zone melting, either in an elongated Crucible according to P fan η or without crucible according to Keck can be carried out, and the pulling up of Crystals from a melt of semiconductor material using the Czochralski method. Another An example is the deposition of semiconductor material on a carrier, e.g. B. by sublimation or decomposition volatile compounds when heated.

Changes in such treatments generally occur, e.g. B. Melt formation, solidification and shape changes that are visible and that can be seen by observing these changes is able to follow the course of the treatment and regulate it if necessary. It is Z. B. at Treatments in which a body made of semiconductor material is rod-shaped by solidification of a melt grows, it is important that the rod thickness is monitored and controlled by the observer as it grows, e.g. B. by regulating the heat supply to the melt. When separating semiconductor material from the gas phase on a support, it is desirable to determine the degree of growth of the deposited material by observation to follow up and to regulate based on this observation in order to achieve the most effective and get regular weaning.

Because it is undesirable for semiconductor materials to carry out the heat treatments in air such a treatment carried out in a room in which the desired composition of the atmosphere can be adjusted. The room is generally at least partially transparent Material such as quartz glass, existing wall to enable observation.

It has been found, however, that fogging of the semiconductor material on the wall of the Space is formed that prevents direct observation of the material to be treated. Such a Fogging occurs particularly when higher temperatures are used and / or when the gas pressure is very low in the room, e.g. B. in a heat treatment in a vacuum on.

The invention aims, inter alia, during a heat treatment of semiconductor material a Heat treatment of semiconductor materials

Applicant:

N. V. Philips' Gloeilampenfabrieken, Eindhoven (Netherlands)

Representative: Dr. rer. nat. P. Roßbach, patent attorney, Hamburg 1, Mönckebergstr. 7th

Claimed priority: The Netherlands, September 24, 1959 (No. 243 734)

Jan Goorissen, Eindhoven (Netherlands), has been named as the inventor

to enable permanent observation of the appearances. She uses the property of a semiconductor material as opposed to that

as to a metal for infrared radiation, for example is permeable in a certain wavelength range, so that infrared rays with one wavelength within this area also allowed through by the condensation of the semiconductor material on the wall will. A common transparent wall part made of quartz glass is generally used for such rays also permeable.

The difficulties described above are alleviated by the use according to the invention an infrared imager for observing the heat treatment in a room with an infrared radiation permeable wall part subjected semiconductor material bypassed. Under an infrared imager is to be understood here generally as a device that converts an infrared radiation image into an image able to transform visible light. The image converter can e.g. B. an infrared observation device known in the art, as described in "Proceedings of the I. R. Ε.", 47 (1959-05), No. 5, Part 1, p. 904 or a flat image intensifier sensitive to infrared radiation. Also can according to principles known from television technology, an image pickup tube that is sensitive to infrared radiation Find use, whereby the signal delivered by this tube in a picture tube in a visible Image is converted. The infrared image converter must be used for the

309 548/201

let infrared radiation be sensitive. The wavelength range of the transmitted radiation is limited on the short-wave side by an absorption limit of the semiconductor material, which with the energy gap, hereinafter referred to as the band gap, between the valence band and the conduction band of the semiconductor material and which, the larger the band gap, with a the smaller the wavelength. In general, high-frequency generator is supplied briskly. As a result Due to the high temperature of the melt, part of the silicon evaporates from zone 5 and partially settles as an opaque trail 7 on the inside of the quartz glass tube 1, whereby observation the zone with the naked eye is prevented. The device further contains an infrared image converter, which is indicated in the figure by a schematically illustrated infrared observation device 8 with

the heated half of a converging lens or a lens system for infrared can be used as an infrared radiation source

Conductor material itself, but this material can also be irradiated with infrared radiation.

It has also been found that the use of an infrared imager has other advantages may have, e.g. B. when fog occurs during treatment, the infrared radiation in a lot scatter to a lesser extent and, if they consist of semiconductor material, also absorb less than visible radiation. Furthermore, when a layer of semiconductor material is deposited on a carrier, the Layer thickness determined during deposition with HiHe from interference reflected infrared radiation what with visible radiation due to the mostly high absorption capacity of the semiconductor material red radiation 9 and a vacuum tube 10 is provided, which consists of a photocathode 11, which among other things for infrared radiation with wavelengths greater than 1.1 μ, the absorption limit of silicon is, a set of electrodes, not shown, and a cathode-luminescent screen 12 consists. During the treatment, infrared radiation is emitted from the heated molten zone 5, where the part with wavelengths over 1.1 μ is almost unhindered by the on the inner wall of the quartz glass tube 1 deposited silicon layer 7 passes through and captured by the infrared observation device 8 ■ can be. With the help of the lens or the lens system 9, an infrared image of the melted

is generally not possible for visible light. 25 zen zone 5 designed on the photocathode. the Although the observation is made with an infrared electron imager emitted from the photocathode 11 in the presence of a conventional with the help of the electrodes, not shown Wall part made of quartz glass in general purpose tubes thrown onto the screen 12, whereby a Can be carried out moderately, can also be made from other invisible image of the molten zone 5 on this Infrared-permeable materials existing wall parts 30 screen results. On the basis of this picture the observer is chosen be e.g. B. parts from other infrared penetrators are able to use the crucible-free zone melting process

to pursue and, if necessary, regulate, e.g. B. by changing the supplied from the generator to the coil High-frequency current without the silicon fitting 7 on the quartz glass tube 1 being an obstacle works.

With the hooves of the image converter, you can also observe the rod parts 3 and 4 by irradiating them with infrared radiation. It has been found — in this figure, 1 denotes a vertical tube 40, that generally normal daylight from it contains quartz glass, within which a vertical tube already contains enough infrared radiation.
Rod 2 made of silicon is arranged. Although in this example only the crucible-free one exists

from two solid parts 3 and 4, which is discussed above and below, zone melting of silicon, a holder (not shown) can be attached, and an infrared image converter, of course, also in the case of intermediate, approximately teardrop-shaped molten heat treatments of other semiconductor materials, zone 5, which is carried out by means of a high frequency coil 6 and other types of heat treatments are used. As a result of the high surface tension, e.g. B. when zone melting in a crucible, the melt, the melted zone 5 is held between the two rod parts 3 and 4 when crystals are drawn up from the melt. The deposition of semiconductor material by sublimation quartz glass tube 1 and the rod 2 are not due to 50 or decomposition of volatile compounds, etc., without

casual types of glass or a window made of the same material or a different semiconductor material with an equal or greater band gap than the material to be treated.

The invention is explained in more detail below with reference to the drawing, in which the figure shows a Vertical section through a device for crucible-free zone melting is partially shown schematically.

means shown gradually moved down in the vertical direction, while the coil 6 does not take its place changes, whereby the molten zone 5 migrates through the silicon rod 2, the rod part 3 gradually melts at the lower end and the rod part 4 gradually grows at the upper end.

The shape and length of the molten zone 5 and the diameter of the growing rod part 4 can be determined by the strength of the current in the high-frequency coil, that of a not shown exceed the scope of the present invention.

Claims (1)

PATENT CLAIM: Use of an infrared imager to observe the heat treatment in one Room with a part of the wall made of semiconductor material that is transparent to infrared radiation. 1 sheet of drawings © 309 548/201 3.