DE1191493B - Method for producing a semiconductor component with a zone divided into two parts by a recess forming a closed line - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY GERMAN #fS PATENTAMT Int. α .:

HOIl

EDITORIAL

German class: 21g-11/02

Number: 1191493

File number: S 76830 VIII c / 21 g

Filing date: November 25, 1961

Opening day: April 22, 1965

The invention relates to a method for producing a semiconductor component with an im essential monocrystalline semiconductor body which contains at least two zones of different conductivity types and one zone of which by a one closed line forming recess is separated into two parts. According to the invention this is The method is improved by first forming the recess up to at least 80% of its final volume is mechanically incorporated and that then by etching the disturbed surface layer of the Semiconductor body is removed in the recess.

It has already become known a method for producing a semiconductor arrangement in which a Semiconductor body with a fused electrode, e.g. B. made of indium, and then a part of the electrode edge removed mechanically, a subsequent groove in the semiconductor body attached by mechanical means and finally other parts of the electrode edge and the wall of the groove in the semiconductor body can be removed by etching. Through this measure will be Defects in the crystal lattice at the edge of the electrode are removed and thus the electrical properties of the component is improved, in particular the breakdown voltage is increased. An exact measurement the depth of the groove is not necessary here.

Semiconductor components have also already become known which have an incorporated recess have, which is used, for example, to separate 3 ″ of two zones. For example, semiconductor bodies by heating in an atmosphere containing a dopant with a surface layer provided, which also contains this dopant after the treatment. Of the The core of the semiconductor body remains unchanged. By appropriate selection of the dopant achieve that between the unchanged core and the doped surface layer a pn junction is created. You can z. B. a semiconductor body made of η-conductive germanium or Silicon in an atmosphere containing boron or aluminum with a p-conductive surface layer or a p-conducting semiconductor body by diffusion of phosphorus with an n-conducting body Surface layer provided.

By incorporating a trench, this surface layer can be divided into different zones, whereby z. B. a pnp or npn semiconductor body of a transistor is formed. Up to now, this trench has been incorporated by etching. The surface of the semiconductor body is a method for producing a semiconductor component with one through one
closed line forming indentation
zone divided into two parts

Applicant:

Siemens-Schuckertwerke Aktiengesellschaft,

Berlin and Erlangen,

Erlangen, Werner-von-Siemens-Str. 50

Named as inventor:

Dr. Kurt Raithel, Uttenreuth;

Rene Rosenheinrich, Ebermannstadt

covered with a material that is insensitive to the etching attack, then it is in this Material at the point at which the trench is to be etched, an interruption is created and then placed the entire semiconductor body in an etching solution. The etching attack only takes place the interruption takes place, while the rest of the surface is protected by the insensitive material remain.

It is known, for example, to cover the surface of semiconductor bodies made of silicon with pizzas cover, which is resistant to the usual etching solutions (e.g. CP).

This method has certain disadvantages which are overcome by the invention. So is z. B. the etching attack unevenly, since the removal of the pizein already takes place unevenly. The mark the place at which the trench is to be created shows a different width. this leads to to the fact that a different amount of etching liquid is supplied to the individual points of the marked area will. In addition, gas bubbles arise during the etching process, which cause the etching attack hinder locally and thus also lead to an uneven etching attack. Finally grab it the known etching solutions the semiconductor material preferentially to lattice defects, which also Deviations from the prescribed etching depth arise. All of these imbalances result

509 540/274

3 4

to the fact that one with relatively high surcharges and leads to a slowing down of the etching attack.

must work at the etching times and depths, as potash or

yes, a certain minimum value of the incorporated caustic soda at room temperature.

Deepening must be achieved, if the drawing should be used to further individual

the purpose, namely the separation of the superiors and advantages of the invention is described

surface layer in different zones, can be achieved.

the should. This has the disadvantage that at F i g. 1 shows a cross section of a

the preferred points of the etching attack of this well-known method manufactured element;

F i g penetrates relatively far into the semiconductor material. Figure 2 shows the cross section of an element that

and thus produced to an undesired mechanical io by the method according to the invention

Leads to weakening of the semiconductor body. became;

If now, according to the invention, the depression in FIG. 3 shows a modification, while the
two stages incorporated into the semiconductor body F i g. 4 represents a complete component,
is, initially mechanically and subsequently, all figures are enlarged by etching, so this can be 15 and, for the sake of clarity, distorted, namely in the range that the greater part of the processing, namely the thickness ratios, are enlarged more, shown. borrowed the mechanical part, perfectly uniform. The component according to FIG. 1 can be done in the following way , while only the rest of the reworking can be done in a gender manner:
the disadvantages just described can occur in a semiconductor wafer of one conductivity by etching . 20 type, a substance causing the opposite conductivity, in particular the small thickness of such a semi-type, is diffused in through a heating pre-conductor body leads to the described difficulty. After a certain period of time, that is the case. It is usually around pulleys vop required penetration depth reached, and the diffusion few millimeters up to about 30 mm diameter is canceled by turning on and whereupon the mm with a thickness of about 0.15 to 0.4. The surface indentation redoped by foreign atoms must reach approximately into the middle of the material layer by etching a circular ring , with one side of the redoped upper trench being divided into two zones. As a result, the surface layer has to be completely cut through, rest on the unchanged core 2, which therefore leaves no bridges , and two semiconductor wafers through a trench 3 whereby, on the other hand, the depression is not separated into the 30 separated zones 4 and 5. As can be seen from the drawing can clearly see the opposite side of the surface layer, the etched trench 3 is allowed to submit an un. Desired mechanical weakening of the semiconductor In the last case, a disadvantage occurs, which results in the component, since the trench is almost up to even when the semiconductor wafer is cut through half of the wafer thickness into the wafer. Which has to be enough for a comparatively small amount.

A thin central zone is then sufficient for the Die F i g. 2 shows a semiconductor wafer, for example using the semiconductor arrangement produced in this way, made of high-resistance (o = 100 ohm · cm) n-conductors , which in operation are on convertible silicon, in the surface of which there is a decisive potential Both surfaces - opposite conductivity type causing substance to isolate zones from each other. It comes at the 40, for example, aluminum that has been diffused in. This surface of the semiconductor body to rollover can be carried out, for example, so that the over the central zone. In particular, when semiconductor wafers, expediently with a peak blocking voltage of up to 1000 V, a number of other semiconductor wafers occur together, the creepage path from one upper area of an aluminum sample in an evacuated quartz vessel surface zone to the other with a thickness of the middle 45 is melted down and in this vessel an area of 0.12 mm, for example, is too short and heated and longer time, for example 30 hours, requires additional measures. In contrast, a long, at a temperature of 1220 to 1240 ° C width of the recess of z. B. 0.5 to 1 mm are held between. After this treatment, the surface layer of the halves mostly consists of the surface zones , in particular the conductor disk, when it is doped to the greater extent with aluminum according to the invention, while the core 11 is mechanically incorporated and remains unchanged has remained η-conductive.

by also having a completely uniform width . circular trench 13 milled, through which one proceeds in such a way that the recess, the aluminum-doped surface layer, is divided into at least 80% of the two end volume, ie, practically zones 14 and 15. To switch schematically in its depth, mechanical work in the half of the trench 13, a is incorporated conductor body on its end, and that only the surface are set with diamonds occupied hollow cylinder disturbed by the mechanical machining top but it can also be a unreinforced metallic hollow surface layer then removed by etching cylinder, z. B. made of brass, but will. In this case, an etching solution is advantageously used in this case, with the aid of the semiconductor, which only attacks the disrupted surface layer surface for the emery powder and whose etching attack is provided when the necessary milling attack is reached.
of undisturbed semiconductor material practically comes to a standstill. For this purpose, one can see that one has proven itself in the form of the slow-acting etching solution , which is in no way limited from 65 wells, since 1 part hydrofluoric acid (40%), 1 part smoking salt With the help of the mechanical attack, practically every pitric acid and at least 1 part of glacial acetic acid can be incorporated into the semiconductor material. Which is set. The acetic acid acts as a moderator. Fig. 3 shows an example of another type of process

depth 13 α. In this case, the entire edge of the semiconductor wafer was processed. This results in a particularly long creepage path on the semiconductor surface between zones 14 and 15.

The F i g. 4 shows a four-layer arrangement as it is e.g. B. from the component according to FIG. 2 manufactured can be. The zone 15 is contacted over a large area by a metallic electrode 16, which 2. B. can be generated by alloying a gold-boron foil (0.03% B). Zone 14 is contacted by an annular electrode 17, which can be produced in the same way. A part is made by alloying a smaller circular disc made of a gold-antimony foil (0.5% Sb) the p-conductive zone 14 is redoped to the η-line and forms the zone 18, which is through the electrode 19 is contacted.

Appropriately, all alloys are carried out in a single heating process. The foils can, for. B. have a thickness of 30 μ ao, and the alloy can at about 700 ° C be carried out, at least above the eutectic temperature of gold and silicon (approx 370 ° C).

Another important advantage of the method according to the invention must be emphasized, which consists in the fact that the order of the individual process steps can be reversed, the manufacture of a semiconductor device, such as. B. according to the F i g. 4, are needed. So can e.g. B. the incorporation of the recess 13 at the very end after all diffusion and alloying processes be carried out because the semiconductor component is contaminated by pizzas or the like. Can no longer occur.

Claims (4)

Patent claims: 1. A method for producing a semiconductor component having a substantially single crystal Semiconductor body, the at least two zones of different conductivity types contains and one zone of which by a recess forming a closed line in two parts is separated, characterized in that the recess is first up to at least 80% of their final volume is incorporated mechanically and that then through Etching the disturbed surface layer of the semiconductor body in the recess is removed. 2. The method according to claim 1, characterized in that the disturbed surface layer is removed with the help of a slow-acting etching solution. 3. The method according to claim 2, characterized in that for the slow-acting etching solution a mixture of 1 part hydrofluoric acid, 1 part fuming nitric acid and at least 1 part glacial acetic acid is used. 4. The method according to claim 2, characterized in that for the slow-acting etching solution Potash is used. Considered publications:
German Patent No. 1029 485;
German Auslegeschriften No. 1 018 455, ^
1092131. 1 sheet of drawings 509 540/274 4.65 ® Bundesdruckerei Berlin