DE1208009B - Process for the production of low-dislocation single-crystal semiconductor material for a semiconductor component with pn junction - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY GERMAN '/ WWW * PATENT OFFICE Int. CL:

HOIl

EDITORIAL

German KL: 21g-11/02

Number: 1208 009

File number: C 27398 VIII c / 21 g

Filing date: July 6, 1962

Opening day: December 30, 1965

It is generally known to produce highly doped semiconductor bodies with pn junctions by introducing a To produce a mixture of several impurities or doping materials in semiconductor material. For example, it is known to have a zone of higher η-type impurity concentration in Semiconductor material of group VI of the periodic table through the use of sulfur, selenium and / or tellurium as a doping material with a proportion of less than 1% of the semiconductor material. It is also known in the production of alloyed pn junctions, faulty alloying of gold-antimony alloy material by adding small amounts of sulfur and arsenic.

When contaminants enter a body, e.g. B. diffused into a single crystal made of semiconductor material the lattice constant of the diffused layer can differ from that of the body below. The change in the lattice constant of the diffused layer caused because of the impurity atoms in the vicinity of the contact surface between the rest of the body and the diffused Layer tensions. If the lattice constants differ only slightly from each other, these tensions are evened out due to the crystalline structure. If on the other hand the deviation the lattice constant is much larger due to the presence of impurity atoms and is diffused deep enough, the resulting stresses cannot be compensated for by the lattice structure will. The tensions are rather balanced in such a case that the diffusion layer and the underlying body are connected by a series of dislocations are.

In the production of semiconductor devices with epitaxially grown layers, e.g. Tensions between the body and the layer epitaxially grown on it. Here a number of dislocations also occur on the contact surface when the difference in the lattice constant is large enough and the thickness of the epitaxially grown layer is large.

In the manufacture of transistors, the emitter zone should, if possible, have a high impurity concentration, while the other zones, in comparison, can have relatively low impurity concentrations. This has the consequence that the lattice constants of the other zones essentially correspond to the lattice constants of the pure crystal, while the outer or emitter zone has a different lattice constant
Semiconductor component with pn junction

Applicant:

International Standard Electric Corporation,

New York, N.Y. (V. St. A.)

Representative:

Dipl.-Ing. H. Ciaessen, patent attorney,

Stuttgart, Rotebühlstr. 70

Named as inventor:

Hans J. Queisser, Mt. View, Calif. (V. St. A.)

Claimed priority:

V. St. v. America July 13, 1961 (123 778)

shows. Similar relationships occur in the production of solar cells in which the aim is to achieve the Produce surface layer with a relatively high concentration of impurities. Also there the difference in the lattice constant can cause dislocations to form.

It is known that dislocations or errors in the area of the space charge zone of a pn junction in a semiconductor body significantly reduce the service life of the charge carriers. With crystals, which Have dislocations or slip planes, diffuses that used to make ohmic contacts Material faster along these slip planes or dislocations, thereby adversely affecting the arrangement will. When an arrangement is subjected to multiple diffusion processes, difficulties can arise arise from the fact that the diffusion takes place preferentially along these dislocations. Different Properties of the arrangement are likely to be affected, e.g. B. the breakdown voltage, the Occurrence of shunts etc.

The aim of the invention is essentially to provide semiconductor arrangements with planar pn junctions produce, which in the entire semiconductor body substantially uniform lattice

509 760/272

3 4

have constant and in which the emergence of zones of very different impurity dislocations is avoided. In particular, the lattice stress concentration should have such values Semiconductor devices are viewed with the assumption that harmful dislocations occur high concentration of impurities in addition to layering.

th relatively low impurity concentration, 5 The other features and advantages of the invention

no dislocations occur at their connection point - will be explained in more detail below with reference to the drawing

occur and which are explained through the entire semiconductor body:

a substantially uniform lattice constant. Fig. 1 shows an atomic plane in a pure

own. Semiconductor crystal, ζ. B. in silicon;

It is known to have a unitary semiconductor body. Fig. 2 shows an atomic plane in a semiconductor for a tip diode with two doping materials crystal, in the upper surface of which impurities of the same conductivity type are doped, one of which has a smaller atomic radius than the one larger and the other one smaller remaining crystal have been diffused;
Atomic Radius as the Atomic Radius of Semiconductor Atoms Fig. 3 shows an atomic plane in a crystal. The semiconductor body is doped in which the mean atomic radii of the impurities are essentially that of the rest of the crystal in such a quantity ratio of the doping materials that the mean atomic radius corresponds to the;

Semiconductor body corresponds to that of a non-doped semiconductor. FIGS. 4A and 4B show a solar cell with the body. By this measure, the features of the invention, and
Formation of etched pits on the semiconductor body, 20 Fig. 5 shows a transistor with two-dimensional those in the production of tip contacts of pn junctions according to the features of the invention. Disadvantage are to be prevented. During manufacture FIG. 1 shows the arrangement of atoms of the tip diode according to the last-mentioned method along a plane. The atoms are in driving is arranged on the relatively highly doped semiconductor- the same distance from each other. Thermal oxidation creates a very thin delt around an ideal crystal with a surface layer of very pure silicon. uniform lattice constants throughout the crystal. If such a tip electrode is a semiconductor body, the crystal of which is exposed to a diffusion process, then the lattice constant of that of the surface layer through which impurity atoms corresponds to one is before the placement of the blocking electrode. However, this method is only suitable for the atomic radius of less than that of the crystal atoms to diffuse into the crystal from the position of very thin layer-shaped zones on the surface; is applicable because the partition coefficient is reduced. The lattice constant becomes smaller. This gap between silicon and silicon oxide is shown in FIG. 2. If the impurity is so different that in the appropriate thickness and impurity concentration, there will generally be even stresses between the body of this layer, the difference between the grid and the thin tip surface layer. constant so large that the crystal

The present invention relates to a method that cannot compensate elastically. The under-

for the production of low-dislocation monocrystalline difference is in this case by the formation of

Semiconductor material for a semiconductor component, at 40 dislocations, which are indicated at 11,

like a pn junction between a zone with. Such dislocations are similar

low impurity concentration and a way formed when the diffused atoms

Zone with higher impurity concentration in front of a larger atomic radius than the atoms

hand is. The disadvantages mentioned last of the crystal.

according to the invention, if one is now in a suitable ratio to one another

by avoiding that to create the zone with other atoms with larger as well as atoms

higher impurity concentration at least with a smaller atomic radius than the atomic radius of the

introduces two doping materials of the same conductivity crystal, one can achieve that the

type diffused or with epitaxial mean atomic radius within the entire crystal

Grow are introduced, of which at least 50 is the same size, which is shown in FIG. 3 is indicated.

one a larger and another a smaller one In the upper part of FIG. 3 are through one

Atomic radius than the atomic radius of the semiconductor atoms diffusion process in the crystal atoms with larger ones

has, and that the proportions of and diffuses atoms with smaller atomic radii

Doping materials are chosen so that the have been. The parts marked 13 are zones,

mean atomic radius of all doping 55 used in which the atoms have a larger atomic radius,

materials approximately equal to the atomic radius of and the parts designated by 14 are zones in

Semiconductor atoms is. where the atoms have a smaller atomic radius.

With the method of the invention, it must be taken into account that the representation

borrowed thicker zones in a semiconductor body with in FIG. 3 for the sake of clarity

a uniform lattice constant can be generated. 60 is much simplified. In reality there are atoms

A semiconductor made according to the invention with small and large radii evenly across

In the event of diffusions of impurities, the entire affected crystal surface is distributed and

practically no more diffusion at grain boundaries - not on zones as shown in FIG. 3 shown

ways that run and are parallel to the surface.

thus in contrast to the last-mentioned known 65 In the following table the atomic radii of Processes during etching are not made visible silicon and various donor and acceptor can. In the known state of the art, substances were given in angstroms. The third column Surprisingly, that even with much thicker ones, the deviation of the atomic radii from silicon

Claims (1)

5 6 atoms and the corresponding impurity- impurity concentration of the order of magnitude atoms. from 10 ¹⁶ to 10 ¹⁷ per cm ~ ³ . In FIG. 4B is a gj 217 grown layer of p-conductive material ρ (7-j ι 'q7 - 0 10 shown, which has a rectifying pn junction β • _ ■> Q ⁵ Og _ q '^ q 5 with the η-conductive layer underneath oil / · _Λ -. '^ 4, QYj forms. This layer can e.g. B. as an impurity Q _a f \ ' - ^ 28 4- 011 material 19 parts aluminum to 16 parts boron in ^ j f_ \ 122 + 016 a total concentration of 10 ¹⁹ to 10 ²⁰ per cm " ³ j / -v j '^ g, Q'29, in order to minimize the impurity A _s / Λ 1 '1 £ _ o'oi ¹⁰ concentration in this layer. gj /-.N j '^ g, Q'29 Similarly, in making '' of a transistor as shown in FIG. 5 shown It can be seen from the table that the atomic radius, the collector layer 21 and the base layer 22 of boron atoms is 0.19 angstroms smaller than that of a relatively small impurity con silicon atoms. On the other hand, in comparison to the emitter layer 23, aluminum atoms have a radius that is 0.16 angstroms larger. The emitter layer can, for. B. is epitaxial than that of silicon atoms. Therefore when you have grown up. The difference in the lattice. B. will produce a p-type zone, can be boron constant are compensated by and aluminum in the silicon crystal diffuses, namely composition for the η-type emitter layer, the suitable additions and in a ratio of 19 parts of aluminum of the impurities _ao selects. It minium to 16 parts of boron. The mean atomic radius are suitable for z. B. phosphorus and antimony in then corresponds to the atomic radius of silicon. The average lattice constant, a ratio of 17 parts of phosphorus to 10 parts, is determined by the antimony. A mean lattice constant thus becomes essentially the same for the entire crystal. Possibly obtained, which essentially corresponds to the remaining low voltages can then 15 semiconductor body,
be balanced by the elasticity of the crystal. The individual claims should preferably
impurities have the same rate of diffusion so that the lattice constant throughout the 1st process for making dislocation crystal remains the same. If, on the other hand, with the 30 poor single-crystal semiconductor material for a introduced impurities the diffusion semiconductor component, in which a pn junction If the speed differs slightly, you can move between a zone with low pollution tensions due to the elasticity of the crystal concentration and a zone with higher since there is the deviation of the lattice impurity concentration, d aconstants between adjacent zones relative- 35 characterized in that to ore-moderate is low. In the epitaxial growth, at least two doping materials are formed in the region with a higher impurity concentration the impurities selected so that the same conductivity type diffuses in or at the same lattice constant as the epitaxial growth can be introduced, Has base body. For example, if a 40 of which at least one is a larger and p-type layer on the surface of a silicon- a smaller atomic radius than that of another Crystals are to be grown, then the atomic radius of the semiconductor atoms can have, and Boron and aluminum as doping material for this that the proportions of the doping layer can be used, namely in a material chosen so that the middle ratio of 19 parts aluminum to 16 parts boron. 45 atomic radius of all doping materials used - N-conductive Layers can also be approximately equal to the atomic radius of the sion or epitaxial growth with a suitable semiconductor atom. Neten combination of donor impurities 2. The method according to claim 1, characterized in be generated. It can e.g. B. Phosphorus and records that doping materials have the same diffusion Antimony in a ratio of 17 parts of phosphorus 50 sion speed are diffused. to 10 parts of antimony used to make a To obtain the mean lattice constant that is above the publications considered: entire crystal is the same size. German Auslegeschrift No. 1 037 015; Figures 4A and 4B schematically show steps of U.S. Patent No. 2,824,269; for making a solar cell. The base body 55 French additional patent specification No. 74 285 for made of η-conductive material has a relatively low French patent specification No. 1174 436. 1 sheet of drawings 509 760/272 12.65 © Bundesdruckerei Berlin