DE1207636B - Process for the production of wafers from monocrystalline silicon and / or germanium for semiconductor components - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. σ .:

German class: 4Od-3/00

Number: 1 207 636

File number: S 73154 VI a / 40 d

Filing date: March 27, 1961

Opening day: December 23, 1965

In semiconductor technology, disks made of germanium or silicon are required, which then either can be processed directly into semiconductor components or as oriented seeds for monocrystalline Serve growing the semiconductor material from the gas phase, as it is for example in the German patent 865 160 is described.

In all cases, the smooth surfaces of the panes are important because of the properties of the surface the quality of the semiconductor components obtained, ζ. B. transistors and directional conductors, decisively influenced will.

Semiconductor rods are usually available as starting material, which can be drawn from the Melt according to Czochralski, by application crucible-free zone melting or by depositing silicon and / or germanium from a gaseous silicon or germanium compound in monocrystalline form on a thin, wire-shaped monocrystalline bodies were obtained from the semiconductor material in question.

Such a semiconductor single crystal rod must be in a number of disks are dismantled, generally through perpendicular to the rod axis Cuts are generated. This is usually done by sawing. Because of the high price of the semiconductor material, which is primarily defined by the to achieve the required purity or a Impairment content is due to the necessary large technical effort, is in such a Proceeding the problem of cutting losses is vital. So there were numerous Attempts have been made which should satisfactorily cope with the problem of cutting losses. These attempts have so far hardly produced any noteworthy results.

In order to appreciate the problem of cutting losses, the following remarks are made. A z. B. off A silicon rod with a diameter of 10 mm and a length of 200 mm costs around DM 500.00. In practice, about 220 slices with a thickness of 0.5 to 0.6 mm are obtained from such a rod. Experience has shown that cutting loss is around 40% when sawing alone. On the other hand appears but a sawing of the crystal is the only way to create flat and defined interfaces to get.

So that the problem of cutting losses can be solved satisfactorily in this way, it is a prerequisite to have rods with an exactly dimensionally stable diameter available, because rods with un-procedural methods for producing disks from
single crystal silicon and / or germanium
for semiconductor components

Applicant:

Siemens & Halske Aktiengesellschaft,
Berlin and Munich,
Munich 2, Wittelsbacherplatz 2

Named as inventor:

Dr. Josef Grabmaier, Vaterstetten

uniform diameter would result not only in disks of unequal size, but also The quality and thus the usefulness of the cleavage surfaces obtained, as experience has shown, significantly depends on the uniformity of the diameter of the available monocrystalline silicon or germanium rod.

In the German patent specification 1170 150 is a method for pulling rod-shaped semiconductor crystals, in particular of germanium, from the melt using a seed crystal, which is brought into contact with the melt and then gradually withdrawn from it, whereby the material carried along by the seed crystal in the form of a solidifying strand of liquid solidified successively from the melt to form a rod-shaped body, which is described is characterized in that the solidifying strand of liquid by the electric field one or more measuring electrodes out and the capacity of the measuring electrode or the measuring electrodes is continuously monitored with regard to the material passed by them, one due to deviations of the diameter of the strand of material leaving the melt Capacity from a setpoint by applying compensatory measures, e.g. B. by temperature change or changing the pulling speed.

This process is able to produce rod-shaped semiconductor crystals with a high degree of uniformity

509 759/457

Claims (1)

3 4 Bar diameter, regardless of whether it is scratched with a point. The length of the notch is not a melt held in a crucible (crucible-critical. Experience has shown that na- loose zone melting) is worked. This naturally grown crystal structure, It can also be used for the production of single crystal Linen rods with any orientation of their longitudinal discs can be done by splitting. To the- use axis, the seed crystal used is therefore a pressure-resistant cutting edge is then monocrystalline and the orientation of its criterion is set against the scratched point and under one against Stable grid to the direction of pulling in a corresponding way the outer surface of the part to be separated blunt is set. fen angle pressed into the notch, causing the rod According to the above statements, as a result of the point or cutting edge, the invention relates to a method for producing a pressure effect at the scratched point of disks of monocrystalline silicon and / or disks. For this purpose it is possible to use the tool used for the germanium, with the diameter of the scratches, if desired, thin single crystal disks with the resulting compressive load from a liner rod made of one of these materials set with {111} - * 5 may be. With diamond tools this or {100} - or {221} - or {112 ~} ~ orientation is generally not the case, which is why its longitudinal axis is drawn and perpendicular to its longitudinal axis in plane-parallel through a correspondingly pressure-resistant material Slice is disassembled. z. B. made of high quality steel, existing gap according to the invention, the rod on its jacket tool must be replaced.
surface perpendicular to the longitudinal axis in the thickness of the ao. In order to avoid the necessary spacing required in many cases by placing a second tool on the scratched notch and using lateral pressure and / or pulling through the scratching, using the cleavage It is advisable to use these crystals to separate the incised point after scratching a notch. In doing so, flat discs on one side of the notch, all-parallel, with the desired thickness and, generally speaking, the longer rod part, are held and for orientation. part of the rod located on the other side of the notch, If the axis of the rod to be cut is one of the slices to be cut, indicated at the notch Has orientations, the point is detached. In general, this is sufficient by a blow performed in the manner indicated against the pane to be separated Scoring produced essentially tiny notches or pressure from the same side as that the notch is located between successive and to the rod axis, perpendicular to the pane to be separated standing crystal planes, e.g. B. acts between chen. {lll} planes when the axis of the rod is the In the drawing is an example of the procedure has {lll} direction. These listed crystals are shown according to the invention. A germanium but are characterized by the fact that they have a rod 1, which is equipped with a holding device (not shown) on the one hand, crystal planes with the closest packing of spheres in the direction shown in the drawing are, d. H. Layers with a large accumulation of is pressed against a base 2 is means of Lattice blocks, and that on the other hand between a sharp-edged cutting edge 4 on the previous one Adjacent levels of this type only little Si-Si or scratches generated notch 3 split. To this Ge-Ge compounds effective 40 ways per unit area can produce disks from 50 μ to 2 mm thick are. These two characteristic features for and above can be established without difficulty. Cleavage planes are the cause of the possibility of particularly smooth, even surfaces of the a slight severing of crystal rods or split-off slices is obtained from experience for easy separation of defined slice dimensions when the area newly formed during splitting Chen of such rods parallel to the aforementioned 45 is greater than the square of the thickness of the disks. excellent crystal planes. The fracture surfaces result in the method according to the invention the slices produced in this way have the following advantages: firstly, almost no cuts completely smooth and even, so that there is no need for grinding, secondly, no introduction of undesirable and / or lapping and / or mechanical polishing th impurities when separating, what when this fracture surface is not required. 50 sawing of the crystals is by no means guaranteed, third Treatment is at most a surface cleaning of an undisturbed surface, without further and / or a short-term etching treatment is necessary, losses of material are processed further immediately in order to be able to possibly subsequently formed oxide,
len to eliminate. Will contact with air or other oxidizing media switched off, so can 55 claims:
if necessary to an etching treatment completely be waived. 1. Method of making slices from Because of the hardness of the rods to be treated, monocrystalline silicon and / or germanium, the choice of the work to be used for scribing - with the diameter of the desired one constructions materials limited. First and foremost, there is a single crystal thin rod with 60 disks Diamond in question, so that the notches are expediently made of one of these materials with {111} or by scoring with a diamond tip or diamond {100} or {221} or {112 "} orientation cutting edge can be generated. The depth of the notch of its longitudinal axis is drawn and perpendicular to it to be only a few microns and is most simplified on the longitudinal axis into plane-parallel slices generated by laying it in a guide, characterized in that held the rod by applying the appropriate pressure to the rod on its lateral surface perpendicular to the Tangential against the surface of the rod, longitudinal axis in the thickness of the desired washer perpendicular small diamonds moving to its longitudinal axis are scored at corresponding distances and by lateral pressure and / or tension, taking advantage of the cleavage of these crystals on the incised area is separated. 2. The method according to claim 1, characterized in that the held in a guide Rod by an under appropriate pressure tangentially against the surface of the rod pressed tip or cutting edge moved perpendicular to its longitudinal axis hard material, especially diamond, is scratched. 3. The method according to claim 1 or 2, characterized in that a fixed cutting edge or The point is set on the incised point and at an obtuse angle to the surface line of the The disc to be separated is pressed into the notch and the disc as a result of the Tool transferred pressure is split off. 4. The method according to claim 1 or 2, characterized in that after the scratching one Notch the disc to be separated separated from the held rod by pressure or impact will. 5. The method according to any one of claims 1 to 4, characterized in that the gap surface greater than the square of the thickness of the slice to be separated is chosen. For this purpose, 1 sheet of drawings 509 759/457 12.65 © Bundesdruckerei Berlin