DE2559841C2 - Method for doping semiconductor material - Google Patents

Description

> 40 to 60 SiO ₂ 10 to 30 Al ₂ O ₃ 20 to 40 B ₂ O ₃ 3 to 20 RO,

where RO is: MgO, CaO, SrO, BaO or their

Mixtures, with BaO 1 to 15 and

BO

less than 0.5 alkali metal oxides and up to 10 of Oxides other than alkali metal oxides, which are not harmful to semiconductor material doping.

2. The method according to claim 1, characterized in that the non-harmful oxides for the semiconductor material doping TiO ₂ and / or ZrO ₂ have been used.

3. The method according to claim 1 or 2, characterized in that glass ceramic disks are used which (in mol%)> 40 to 55 SiO ₂ , 10 to 30 Al ₂ O ₃ , 20 to 40 B ₂ O ₃ , 3 to 15 BaO, 5 to 15 RO,

where RO is alkaline earth oxides with 4> contain.

The invention relates to a method for doping semiconductor material from the gas phase by heating together with disks of boron oxide-containing silicate material arranged at a distance to 700 to 125O ⁰ C

One method of the type described above is from US-PS 35 30 016 become known. Here, disks are used as a source of doping material, which consist of a base body made of silicon, which has a relatively thin surface layer (7500-13000 A) made of borosilicate The wafers are heated in the presence of the semiconductor material, whereby Boron impurities from the surface layer diffuse into the semiconductor material to produce a to form active impurities-containing layer.

The disadvantage of the known methods is that they can only be used to a limited extent, since they are used to carry out them only the relatively thin surface layer of the silicon base body is available for doping. About that In addition, the production of the doping material source is relatively complicated and expensive, since this is done here Boron impurities are diffused into an oxide layer present on the surface of a silicon base body in order to form the borosilicate layer. For example, liquid boron tribromide is used to carry out the diffusion process.

The subject of the application is based on the task of a method of the type mentioned to create that the limits of the known process does not have and that works more economically than this.

In a method described at the outset, this object is achieved according to the invention in that semi-crystalline glass ceramic panes are used, obtained by thermal in situ crystallization of a barium aluminum borosilicate glass which has the following composition (in mol%):

> 40 to 60 SiO ₂ , 10 to 30 Al ₂ O ₃ , 20 to 40 B ₂ O ₃ , 3 to 20 RO, where RO is: MgO, CaO, SrO, BaO or their

Mixtures with BaO 1 to 15 and 4> 1 J5, less

than 0.5 alkali metal oxides and up to 10 of for the Semiconductor material doping does not harm others Oxides as alkali metal oxides.

According to the invention, a special group of B ₂ O 3 -containing doping material dispensers made of glass ceramic is used which, at high doping levels temperatures, for example above 1050 ⁰ C, are thermally stable and solid. These materials have at temperatures above 1050 ° C and even at higher temperatures of 1250 ⁰ C a good dimensional stability, even if the material in the form of thin Panes present The starting glasses, which are thermally crystallized from glass ceramic to form the doping material dispenser, can be melted quickly are and are resistant to uncontrolled devitrification.

It is of the utmost importance that the above-described property of dimensional stability of the glass-ceramic material at high temperatures with relatively high B ₂ O ₃ contents, although the thermal stability and strength of the Material generally decreases with increasing concentration of B ₂ O _3; This is because the speed at which the B ₂ O ₃ vapors are generated by the doping material dispenser made of glass ceramic during doping generally increases with the concentration of B ₂ O ₃ in the doping material dispenser.

In the case of high-temperature doping (e.g. at over 1050 ° C.), with a high B ₂ O ₃ concentration in the donor, the boron can pass over in such a high proportion that a much stronger precipitate occurs The semiconductor material arises when it can be dissolved and diffused into the semiconductor. If that The semiconductor material to be doped consists of silicon, is formed by the reaction of the excess boron the silicon a precipitate of undesirable

so composition that most likely consists of borosilicide this undesirable compound is considered dark, brown or bluish-yellow dye, depending on the thickness, visible. It is believed that color and intensity due to the interference pattern this dye on the amount of undesirable Dependent on precipitation. The bluish yellow dye indicates a greater accumulation of undesirable precipitate. This precipitation is by nature electrically insulating and must from that doped semiconductor material are removed. the However, the borosilicide compound cannot be easily removed by washing with hydrogen fluoride and usually not by an oxidizing reaction in an oxygen-containing atmosphere be eliminated. Precipitation is usually more pronounced when fresh Bordotier material dispensers be used. In the method according to the invention is thereby.

that the glass ceramic panes used have a very specific combination of concentrations of BaO, B2O3, Al2O3 and SiO ₂ , not only enables controlled doping at high temperatures (e.g.> 1050 ° C), but also the tendency to form the aforementioned undesired insulating deposit and thermal stability and strength at such temperatures are ensured, even if the dopant dispenser is in the form of a thin disk

The doping material dispenser used according to the invention in the form of solid, dimensionally stable, essentially alkali metal oxide-free barium aluminum borosilicate glass ceramic disks are kept in contact with the semiconductor material in the gas phase (in the presence or absence of a carrier gas) at an elevated temperature for a period of time sufficient to prevent the B. _{To transport 2} O _{3 of} the doping material dispenser onto the surface of the semiconductor material. The semiconductor material treated in this way is then heated, with or without the further presence of the glass ceramic panes, for a period of time which is sufficient to allow the boron to diffuse into the semiconductor material to the desired depth.

In an economically important embodiment of the process according to the invention, as Semiconductor material η-conducting silicon semiconductors used in which a boron-containing layer is produced which forms a p-type region. The back of the chip or the silicon wafer retains its n-conductivity, so that semiconductors with p-n junction are created.

The invention is described in connection with the expression "transport of B ₂ O ₃ in the gaseous state", since there are no more detailed studies on the boron-containing substance that evaporates from the glass ceramic dispenser. Accordingly, this term includes any boron-containing substance responsible for the transport effect. The diffusion process is described in connection with the term "boron diffusion in the semiconductor", since there are also no precise studies on the boron-containing substance that actually diffuses in. Accordingly, this expression includes any boron-containing substance responsible for the diffusion doping effect. The boron precipitates from the gaseous phase on the surface of the semiconductor and diffuses over a defined depth into the semiconductor material. The concentration and the depth of the transition are proportional to the time and temperature of the doping and diffusion process.

The glass ceramic doping material must be solid and dimensionally stable at the doping temperatures, so that no deformation problems occur if the doping material source has a planar shape. In the case of planar diffusion doping, a planar surface of a solid doping material donor and a planar surface of the semiconductor to be doped face parallel 60 during the diffusion heat treatment. Since the concentration of B ₂ O ₃ on the surface of the semiconductor is a function of the distance between the planar surfaces, the dimensional stability of the dopant dispenser is of the utmost importance in order to achieve uniformity in the boron distribution on the surface of the silicon semiconductor.
The glass ceramic panes used according to the invention are made from certain barium aluminum borosilicate glasses which are essentially free of alkali metal oxides. With "essentially alkali-free" it is meant that the glasses only _{contain so much alkali metal oxides (e.g. K 2} O, Na ₂ O and Li ₂ O) that no vapor phase is formed which contains such oxides at the doping temperatures . It has been found that the presence of such alkali metal oxides in the vapor phase induces undesirable properties in the electrical conductivity of the resulting semiconductors

The proportion of the alkali metal oxides must be less than 0.5 mol% and preferably less than 0.1 mol% glass ceramic doping material mixture amount. Preferably no alkali metal oxides are contained at all, although this is not always possible as the raw material often contains alkali metal oxides as impurities contains

As oxides which are not harmful to the doping of the semiconductor material, TiO ₂ and / or ZrO ₂ can have been used as nucleating agents.

The term "glass ceramic" is used here according to its usual meaning and relates on a semi-crystalline ceramic composed of at least one crystalline phase which is arbitrarily in a remaining vitreous phase is dispersed is composed. Such a crystalline phase is through formed the in-situ thermal crystallization of an original glass mixture

Glass ceramic panes of the following composition are preferably used in which long service life as well as effective and controlled boron doping and high dimensional stability at high temperatures result in:

> 40-55 SiO ₂
10-30Al ₂ O ₃
20-40B ₂ O ₃
3-15BaO
5-15 RO

where RO is alkaline earth oxides and 4> > 2.

The heat treatment process for producing glass-ceramic from a glass usually includes nucleation at about the upper cooling temperature (viscosity 10 ¹³ poise) of the original glass, a development stage at a temperature below the softening point of the original glass (preferably at a viscosity in the region of 10 ⁸ to 10 ¹² poise) and a crystallization stage (at a temperature preferably between 65 to 150 ° C above the softening point of the original glass (ie viscosity of 10 ⁷ · ⁶⁵ poise).

Although the crystallization process itself is not part of the present invention. the following description is given in the interests of completeness of the disclosure. The original glass to be crystallized is heated to a temperature ^{equivalent to a viscosity of 10 13} poise and held at that temperature long enough to allow the formation of submicroscopic crystals dispersed in a vitreous matrix. This is known as nucleation. The time required for the nucleation period depends on the composition and is normally between ¹ Å and 24 hours. The vitreous material that makes up the nuclei

is then heated to a temperature corresponding to ^{a viscosity of approximately 10 8 poise.} This thermal state is maintained for a sufficiently long time to allow partial crystallization to form a solid crystalline structure. The submicron nuclei dispersed in the vitreous matrix as the result of the nucleation phase act as growth centers for the solid framework that forms during this second or developmental phase of the heating cycle. This development phase depends on the composition and is typically ¹ A to 4 hours. At this stage of development, a solid, skeletal crystal-like structure should be created to support the rest of the material when the temperature is increased for complete crystallization.

The method according to the invention is illustrated below using examples in conjunction with the drawing explained. It shows

F i g. 1 shows a section through a semiconductor body which, according to the doping method described was produced,

F i g. 2 is a perspective view of a semicrystalline glass ceramic disk serving as a doping material donor and containing B ₂ O ₃

F i g. 3 is a longitudinal section through a fire-resistant container in which a number of solid B2O3-containing glass ceramic wafers and a number of silicon wafers for carrying out the Doping method are arranged.

As can be seen from the drawing, a suitable η-conductive silicon substrate 10 is made with the aid of one of the known techniques prepared to produce a single crystal silicon body. For example For example, a single-crystal ingot can be formed from high-purity silicon. The ingot is made in Cut transversely, and the resulting cubes are cut up to form the silicon wafers desired dimensions. The surface of the substrate can be cleaned and cleaned appropriately Polishing to be prepared. The polished and cleaned silicon material can, however, also be obtained commercially can be obtained. Polishing or cleaning the surface can be done by mechanical means such as Sanding or similar by chemical means, such as Etching, which is known and does not form part of the invention, can also be completed η-conductive silicon wafer form part of a complex semiconductor and already have one or more Have p-n junctions in any geometric arrangement. The only important feature is that Accordingly, at least a part of the surface of the silicon wafer present has n-line As used herein, the term η-conductive silicon also includes complex semiconductors that have alternating p- and η-conductive zones.

In the case of conventionally grown crystals, the surface can be chemically polished with a suitable etchant, e.g. B. a solution of three parts by volume of hydrogen fluoride, three parts by volume of acetic acid and five parts by volume of nitric acid. On the other hand, the surface may by sanding or etching with a hot solution of water containing about 10% sodium hydroxide at room temperature or up to about 90 ⁰ C, to be prepared. These cleaning and etching work serve to remove pollutants from the surface and provide a uniform surface of particular smoothness. Such preparatory work is known.

It has been found that the formation of a p-n junction according to the present invention in FIG the desired level for an η-conductive silicon element with a specific resistance of about 10 ohm-cm is created. It is easy to see the exact size and nature of the slices is not critical. The disks normally used can, for example, have a diameter of 2.5; 5 or 7.5 cm. The thickness can be between 0.125mm and 0.5mm, although these are also changed can. Typical disks are between 0.2 mm and 0.25 mm thick. Likewise, the specific lies Resistance of suitable η-conductive silicon starting materials between about 0.0001 and about 100 ohm-cm.

As in Fig. 1, an oxide layer 11 has formed A mask or protective layer may be used to form on the surface of the disc 10 create any pattern as is known in the art. The layer or film 11 is of vitreous in nature and contains boron in some form.

The temperature of the doping process is such that at the same time some boron from the film or Precipitation 11 diffused into the disk 10 and there a thin boron-containing surface layer 12 adjacent to the layer 11 forms. The layer 12 represents a barrier or boundary layer in the area is formed between the boron-penetrated surface layer 11 and the η-conductive silicon 10 The depth of the transition zone can vary, but is usually up to about ΙΟμπι. The minimum thickness can vary and is about 0.1 μm.

The electrically insulating precipitate forms on, in or below this glass-like layer 11, believed to be composed of borosilicide. The present invention is the The tendency to form such an insulating deposit is reduced and the removal of the deposited crowd relieved.

F i g. 2 shows a plate or disk of the B ₂ O ₃ -containing doping material dispenser made of glass ceramic, which serves as a supplier for the B2O3 vapors for contact with the silicon disks

If the ceramic glass is introduced into a suitable oven 14, and when exposed to temperatures between 700-1250 ⁰ C, in particular between 1050 to 1200 ° C, is exposed, it sets B ₂ O ₃ vapors released, which then by the high-temperature zone of the furnace to Contact with the silicon wafers, which are attached in the vicinity of the doping material wafer, flows. Viewed overall, the method for diffusing boron consists in that at least one semiconductor silicon wafer is introduced into a furnace; Also, a glass-ceramic pane in the oven in the neighborhood, but not disposed in direct contact with the silicon element Then, the silicon wafer and the ceramic glass will be an elevated temperature exposure in the above described range of 700-1250 ⁰ C. At these temperatures, the dopant is B ₂ O 3 -Free vapors, which then flow through the furnace and come into contact with at least part of the surface of the silicon wafer. This process is maintained for a sufficiently long period of time to allow diffusion of the boron into at least a part of the surface of the silicon wafer, vm a

To form diffusion zone therein. After the B2O3 vapors have reacted with the hot silicon surface, the diffuses with continued heating elemental boron in the silicon chip. This boron diffusion stage can, if desired, in the absence of Glass ceramic panel can be carried out.

The doping process can be further controlled and improved by adding a free-flowing inert Carrier gas such as argon or nitrogen is used. The term "inert gas" is intended to mean that Gas does not react chemically with the BaCV vapors and the hot silicon surface occurs.

This is shown in FIG. 3 shown in which the carrier gas of Enters on the left and flows over the disk 14, where the B2O3 is released and the available ones Surfaces of this silicon disk! 0 touched by If two silicon wafers are stored back to back, the back of each chip does not come with the Boron in contact and accordingly retains its original property as η-conductive silicon. After this Doping process, the diffusion depth can be increased by a simple Heat treatment in an inert atmosphere allows the transition to diffuse deeper. This can, if desired, be made in a separate oven. The above operation was made because of its large size economic importance applied to silicon semiconductors described. The same process can However, they are also used in germanium semiconductors, although the temperatures are somewhat lower Doping of germanium must be used because of its melting point of 937 ° C.

When preparing the glass-ceramic doping material, suitable starting materials that contain the Containing corresponding compositions, are melted to form a homogeneous glass mass form. For example, compositions described above can be used at 1500 ° C to 1650 ° C in one Heat-resistant crucibles are melted to obtain a homogeneous glass. Usually needed this melting process takes about 15 minutes to several hours to achieve homogeneity. It It may be desirable to add additional B2O3 to the melt in order to reduce the losses due to evaporation balance. It is desirable to keep the melting time as short as possible in order to reduce the losses To keep evaporation low. The starting material should also be as pure as possible in order to avoid its presence to keep contamination as low as possible.

The glass ceramic panes can be produced in different ways. The original glass can are melted from organometallic derivatives in order to reduce the content of undesired constituents as possible to keep low, as is disclosed in US-PS 36 40 093, or it can be from the usual high purity glass-forming components are melted.

The presence of impurities can adversely affect the electrical properties of the doped silicon semiconductor. Impurities that must be particularly avoided or kept to an absolute minimum are alkali metal oxides (i.e. Li ₂ O, Na ₂ O, K ₂ O, Cs ₂ O or Rb ₂ O) and other high vapor pressure metal oxides such as PbO, CuO and SnO ₂ .

After the glass compositions have melted and form a homogeneous molten mass, the glasses can be brought into any desired shape. Usually this takes place by the Glass is placed in preheated graphite molds that have the shape of a right circular cylinder with a Have a diameter approximately equal to that of the final disks. The glass can then The cooling process is suspended, and after cooling, the glass bars or cylinders taken, checked for cracks and then sliced, the thickness usually between 0.625 mm and 2.5 mm. The glass panes can then be converted into glass ceramic.

Another possibility is to use the glass ingot or a part of a drilled out of the core Subjecting heat treatment to form the glass-ceramic; this glass ceramic is then sliced cut. Because of the very good regulation possibilities, a larger amount of silicon elements by a suitable arrangement of a large number of glass ceramic doping material disks in a container as in FIG. 3 shown.

The doping is carried out by placing the glass ceramic doping material chips close to and parallel to the Silicon wafers that are to be doped are arranged without touching them. The distance at which the best results are obtained is about 3 mm. In a slotted quartz case or other fire-resistant crucibles, vessels, etc. can contain 100 or more silicon chips or disks in the The same strength can be doped by alternating a glass ceramic disk and a pair of disks Are arranged back to back with opposing front sides, the silicon wafers and the glass-ceramic panels are substantially parallel to one another. The arrangement can according to F i g. 3 take place.

The time and temperature of the doping conditions are selected to provide the appropriate p-n junction depth and the appropriate sheet resistance for the desired task. This is shown in shown in the following examples

The distance between the chips in the container, the selection of the surrounding inert carrier gas and the flow

Silicon chips that point in the direction of the flow of the surrounding gas have the same amount of doping preserved like those directed against the current.

In the following examples all are percentages in mol% and all temperatures in ° C, unless otherwise indicated

Example 1 part A

0.453 kg of high-purity raw materials were in a platinum crucible at 1620 ° C for about 5 to 6 Melted for hours in an electric furnace in an air atmosphere with occasional manual stirring, to obtain a clear, molten, homogeneous glass mass of the following composition:

component

Moi-%

SiO ₃ Al ₂ O ₃ 42.9 B ₂ O, 29.6 Al ₂ O ₃ 19.0 EntalkaJtoeUlloxkle 8.8 BaO 5.4 MgO 3.1 ->->

Alkaline earth metal oxides

The molten glass was removed from the furnace and poured into a steel mold (at room temperature), which had a cylindrical cavity 6.3 cm deep and 6.3 cm in diameter. Than the glass the point when it became stiff and firm, it was immediately placed in a heat treating furnace of a temperature of 720 ° C, brought and subjected to the following crystallization heat treatment.

part B
Crystallization heat treatment

The glass cylinder of Part A was left on for 16 hours kept at a temperature of 720 ° C. Then the temperature was raised to 1200 ° C. and for 1 hour held. The furnace was then switched off and allowed to cool to room temperature. The one obtained in this way, not porous glass ceramic cylinders had a milky white opaque appearance.

The glass ceramic material was uniformly cut to a diameter of 3.8 cm using a grinding wheel brought and with the help of a diamond saw into several thin glass ceramic disks about a thickness Cut 1mm to 2.5mm.

Part C.
Flat diffusion doping

The planar diffusion doping was carried out by cutting the glass ceramic panels from part B about 0.3 to 0.6 cm away from the silicon wafers to be doped and arranged in parallel opposition to them became. The glass ceramic disks and the silicon disks were placed in slotted quartz glass bowls alternating arrangement of a glass ceramic disk, silicon disk etc. The arrangement is shown in Fig. 3 shown.

The silicon wafers used in this example originally had η conduction and pointed a resistivity of about 0.1 to 0.5 ohm-cm.

The assembly was placed in a diffusion furnace through the nitrogen at one flow rate of 1 l / min flowed as an inert carrier gas, as shown in FIG. 3, while the doping time> / 2 Hour at a temperature of 1150 ° C.

At the end of this diffusion doping period, the silicon wafer was then cooled to room temperature it was etched with dilute hydrofluoric acid to remove the vitreous layer. The silicon wafer was checked and only a barely noticeable color on the surface showed the presence of some borosilicide.

The surfaces of the doped silicon wafers were p-conductive. The surface tests of the doped Slices are carried out with a four-point conductivity probe. The surface resistance was about 4 ohms. The light color did not prevent the measurement of the surface conductivity.

The doped disks (even the thin 1 mm thick disks) were at the end of the diffusion doping process neither collapsed nor otherwise deformed, making them unsuitable for further plane Endowments would be. If an η-conducting germanium semiconductor is doped in a corresponding manner, then are slightly lower temperatures are required because of the germanium melting point at 937 ° C.

The previous operations were repeated with the modification that during the last 5 to 10 minutes of the doping period oxygen gas instead of nitrogen gas with the same flow rate was used. Under these conditions there was still a slight color on the silicon visible of the doping, which, however, could be completely removed by etching hydrogen fluoride. The received The surface resistance of the doped silicon was around 4 Ohm / D.

Example 2
Part A

The following table shows the extended service life of the glass ceramic panes even after extended use Periods of stressful operating conditions in terms of time and temperature. The expression »Service life« refers to the entire period of time over which the special glass ceramic panel was used for actual doping. In many cases of use, the useful life the glass ceramic panel is not exceeded even after 800 hours of use.

In Table A below, the temperature for the previous usage time is the same as that Temperature for the listed doping test. The doping materials and methods are the same as in Example 1 with time and temperature values as given below.

Table A. temperature
° C Stroke resistance
MC · p-doping
Time (hours)
1/4 1/2 1 171 115 (11 / D)
2 Usage time
Hours (before
this test) 875 238 78 56 86 45 925 107 39 32 43 ⁵⁵ 64 975 52 21 16 24 820 1025 31 10 7th 12th 735 1075 14th 5 64 1125 7th . 4th 3 ⁶⁰ 64 1150 3 172 1175 4th 2 132 1200 3 59

At the end of the tests described in Table A above, the doping disks were not healthy.

ken or otherwise deformed so that they can be used for further even doping would have been useless. The physical appearance of the doping disks was in essentially the same as before doping, and they were still the same at the end of the test Dopability even though the doping disks have not been treated or refreshed in any way.

Furthermore, the silicon wafers that were doped with the doping material had a useful life no dark color for more than about 150 to 200 hours, indicating little or no borosilicide compounds indicated on the surface. In the examples where a slight color appeared, this could be caused by the Supply of oxygen in the doping furnace towards the end of the doping period, followed by hydrogen fluoride etching, removed.

part B

Doping procedures and materials as described in Part A of this example were used (except that the silicon to be doped was originally η-conductive with a resistivity of 4 to 7 ohm-cm). The time was "Λ hour, wherein the individual ceramic disks of a previous usage time were as shown exposed at the same temperature as the specified test temperature. The doping was carried out at two test temperatures of 975 ⁰ C and 1025 ⁰ C. The results are shown below in Table B. specified.

Table B. HäefcMwMcr-
staad (U / O)
according to p-DolienMg
at 97S ⁰ CfBr
l / 2Smede stood (n 43
meta p4) iHii ι — u,
at l «S« C (left
1 / 2StUMdB Previous
Usage time 39 21 0 37 18th 25th 36 2.1 50 36 21 75 21 ioo 39 20th 125 37 22nd 150 175 40 22nd 200 39 21 225 21 250

Previous
Usage time Surface resistance
stand (U / D)
after p-doping
at 975 ⁰ C door
1/2 hour Surface resistance
stand (Ii / D)
after p-doping
at 1025 ⁰ C for
1/2 hour 275 21 3βΟ 39 21 325 3J0 375 39 21 400 425 41 22nd 4SQ 415 40 22nd 500 525 550 40 23 575 600 625 41 23 725 37 21 825 39

At the end of these test periods, none of the dopant disks (even the thin disks of 1 mm thick) deformed and retained their plane shape, which makes them suitable for additional plane doping processes power. The physical appearance of the doping disks was essentially the same as before the doping, and the doping ability was still present at the end of the test, although the doping disks in no way treated or refreshed.

Furthermore, the silicon wafers, which were doped with the doping material, had a Use time of more than 150 hours has been used, no dark color on what the presence indicates little or no borosilicide compound on the surface.

Examples 3-6

Various dopant dispensers were made from barium aluminum silicate glass ceramic and evaluated according to the methods of Example 1. The results are given in the table below.

BebpMNr.
3

SiO ₂ , Moi-% 4M 55.0 55.0 1 * 0 Al ₂ Oj, mol% 2Qj6 11.0 17.0 354 » B ₂ O ₃ , Moi-% 2 * 4 30.0 20.0 <ß Alkaline earth U oxides, mol% u. 4.0 8.0 3vO BaO, Μομ% 5.5 3.0 5.0 ι η MgO, mol% 1.7 1.0 3.0

13th

continuation Example no.

3 4

AtjOj / ErdalkalimetaUoxkie, mol% 2.85 2.75 2.13 3.25. Glass quality, mol% clear clear clear clear Crystallization heat treatment ⁰ C for (hours) 720 (64) 720 (16) 720 (16) 720 (16) ° C for (hours) 1200 (1) 1200 (3) 1200 (3) 1200 (3)

Sheet resistance (12 / D) after p-doping for 1/2 hour at ⁰ C

1150 4.3 3.9 4.0 3.9

In each of the above examples, the nature and appearance of the dopant dispensed essentially the same before and after doping. There was no slump or any other physically! Deformations even with thin panes 1 mm thick.

1 sheet of drawings

Claims (1)

Patent claims: 1. A method for doping semiconductor material from the gas phase by heating together with spaced-apart boron oxide-containing silicate material disks to 700 to 125O ⁰ C, characterized in that semi-crystalline glass ceramic disks are used which have been obtained by thermal in-situ crystallization of a barium aluminum borosilicate glass, the following Composition (in mol%) has: