DE2729889C3 - Process for the epitaxial growth of doped boron phosphide on a substrate - Google Patents

Description

\1

to

where M = Zn, Cd, flg. R = a hydrocarbon radical and <"'= R or halogen. in an amount of 0.05 to ίί) mol per mole of the boron compound or 2» hydrogen sulfide, hydrogen selenide, hydrogen tellurium in an amount of 10 ⁴ to 10 moles per mole of the boron compound are added.

2. The method according to claim I. characterized in that that the reaction gas 0.5 to 50 mol of the _ ■ »compounds

per mole of the boron compound / ...

! Method according to claim I, characterized in that that R is an alkyl group with 1 to 4 carbon atoms and R 'is an alkyl group with 1 to 4 carbon atoms or chlorine or bromine.

4. The method according to claim I, characterized in that that a carrier gas made of nitrogen or a noble gas that is less than "50 vol.% hydrogen contains, or uses a mixture thereof and phosphorus trichlorul and diborane in the ratio between 20 and 200 at a substrate temperature between 880 and 1100 (converts.

5 The method according to claim 4, characterized in that the concentration of the diborane in the pru Minulc flow through the reaction vessel, the reaction is between 2 χ · 10 ^h and 5x10 'Molbcinik'i

The I rlindiing concerns a procedure / to 'jpilakli »Chen growth of doped boron phosphide .ml a substrate, vv> bci borohydrides or halides mn Phosphorus hydrides or halides are called a fempe raliir between 85 (J and 11 (X) -L are implemented.

Gin such procedure is from |. of Applied Physics 42 (Jan. 1071). Pages 420-424 known.

It is difficult to obtain a high quality boron phosphate crystal because its crystal growth is more difficult than that of other Group III elements. Vl and V of the Periodic Table of the Chemical Elements (PSE). like OaAs. GaP and the like. As a result, it is extremely difficult in a doping process by the Ub group impurity element of the PSF. to generate an acceptor content or a donor content by the foreign atom element of group VIb of the PSE.

The present invention is therefore based on the object of a method for epnactic growth of doped boron phosphide on a substrate to which a high quality epitaxial boron phosphide layer of the p- or n-line type is drawn from the gas phase.

This object is achieved by the method characterized in the main claim.

The grown according to the inventive method, doped boron phosphide layer, said observing the Kikuchi bands at the reflective electron diffraction w ith an excellent crystal structure. A carrier mobility of up to 50 cm-7 V. see is obtained. As a result, the boron phosphide layer produced by the process of the present invention has excellent electrical properties.

In the claimed process, diborane is preferably used as the boron compound and phosphine or phosphorus chloride, bromide or iodide in a ratio of PH, / B> H _b or PXi (X = halogen) / -bill · of 10 to 400 as the phosphorus compound.

Boron chloride is also useful. -bromide. -iodide together with phosphorus chloride, phosphorus bromide. iodide (in a ratio of PXj / 2 (BX;) (where X = halogen) used from 10 to 400. It is preferred to work at a temperature between 950 and 1100.degree.

Another preferred embodiment of the process according to the invention consists in adding 0.5 to 50 mol of the compounds to the reaction gas

\ l

can be added per mole of the bond.

I ine further advantageous embodiment of the inven dungsgcmalien procedure is that in the general formula R is an alkyl group with I to 4 Carbon atoms and R 'is an alkyl group with I to 4 Kohlcnsloff.iliiiiiiii-n or (hlor and bromine mean

The Ir.igergas can be nitrogen or a I'dclg.is. which contains less than 40% by volume of hydrogen, or a mixture of it, phosphorus and diborane in the ratio between 20 and 200 with a level of pressure 88 (1 and IKIO (umse '/ en This is preferred /in·
I CcI ^ is .in ¹ ilei ί ι nippe llelimn.
■ iiisg <vv.ihh witil The Konzeiiir.il
the pin Mummy diirch il.is K · .iklmi
Kc.lklnMisg.is can _{hen / VMs 1} > ■ I "

Moles.

An advantageous embodiment of the invention according to the invention The method also provides that a .Silicon ·, germanium, silicon carbide-. Sapphire or Spinel, single crystal or a compound semiconductor substrate is used, which consists of a single crystal layer Boron phosphide is made up on the surface of a Silicon, germanium, silicon carbide, sapphire or spinel single crystal has been applied.

lall the xenon and argon used cn des Dibnr.ins in nsgef.ill flowing nd clvv, ι ")» 10 '

The invention is explained in more detail below with reference to the drawings. It shows

Fig. I is a graph showing the relationship between the temperature of liquid diethyl zinc and the carrier concentration of the grown boron phosphide layer, and

Fig. 2 is a schematic representation of an example for an apparatus for growing a boron phosphide semiconductor.

The reaction gas used for the growth of the boron phosphide in the Cjjphase includes combinations of boron and phosphorus hydrides, boron and phosphorus halides, borohydride and a phosphorus halide and a boron halide and a phosphorus hydride / u more typically. Borohydrides include those of the formula B _n H _nt4 , such as. B. Diborane (BiH ₀ ). BifU and BioHt ,. as well as those of the formula BnH _n , b. such as tetraborane (I) ₄ Hi ₀ ) and R-, Hn. / u Phtisphorhydnden include phosphine (PH ₁ ) and diphosphine (P> H ₄ ). Typical halides include trichloride (BCIi). Boron tribromide (BBn). Boron triiodide (BJi). Phov lhoriiiehlorid (PCIi). Phosphorus bromide (PBrι), phosphorus triiodide (PIi). Phosphorus tachloride (PCU). Phosphorus pentabromide (PBrO. Phosphorpeniaiodide (PJs).

The organic compound as the impurity source is echoed in the liquid state and the amount of Impurity to be added to the reactant gas is varied by changing the vapor pressure The fluid compound is controlled by changing the temperature, and by changing the flow rate of the carrier gas for the absorption of the organic ι Connection controls.

Examples of compounds of the formula

Dimethyl zinc. Diethyl / inc. Di-n propyl zinc. Diisopru ipylzink. Di η butyl zinc. Di see. butyl zinc. Dioctyl zinc. Didecyl zinc. Didodecyl zinc. Distearyl zinc. Dipropenyl / inc. Diphenyl zinc. Dimethylcadmium. Diethyl cadmium. Di-n prifpylciidniuim. Di π butylc idmiuni, Dioclylcad niiiini. Didodecylcadmium. Dipropenyl cadmium. Diphenyle admiuni. Dimethylqiiecksilber. Dietary mercury Di-n propy! Mercury. Diisopmpy! Mercury. Di η buty! mercury. Diovty! Mercury. Didodecyl square silver Dipheny! mercury. Methyl silver chloride. Methylmercury bronze. Melhylquci ksilber | odid. Ethyl silver chloride. Alcohol mercury bromide.

η propyl mercury ehlond. Isoprupvlqueeksilberchlo ritl. A mixture can be used for the doping! the 2 chIit Michr Veninuinigungsclemenlc enlh.ill

For the manufacture of an oil phosphide oil from ρ T ν ρ through epiukiisc. hes' .V, u hsliim one lim phosphide semiconductor line V ei twist of Phos Phosphorus chloride and diborane are particularly advantageous Adequate results are obtained by doing the Krislallwaehstiim linier use of nitrogen or a noble gas that is less than 90 vol .-% hydrogen or a mixture thereof as a carrier gas having a composition ratio of phosphorus trichloride to diborane from 20 to 200 and at a substrate concentration between 880 and 1100 "C.

The boron phosphide-I-lalhleiterschjeht produced in this way

p-type forms a specular surface and has an excellent crystal structure reflective electron diffraction are Kikuchi bands to observe. A mobility of up to 50 em-VV see is obtained. (at a thickness of 1 micron). There Diborane in the growth of the boron phosphide semiconducting layer is the speed-determining level, the film thickness can be adjusted by simply controlling the

can be precisely controlled in the amount of diborane.

Although each of the area indices (100). (110) and (111) can be used for the semiconductor substrate, becomes the best crystallinity with the semiconductor layer from the boron phosphide. the one on a (100) surface r, is formed, ei aims. In particular a BP / Si composite Semiconductor substrate consisting of a silicon substrate Boron phosphide produced thereon provides within a wide range among those according to the invention Excellent crystal ju nity.

It has been found that η-type electrical conduction is obtained when a semiconductor layer of boron phosphide is formed using only hydrogen as the carrier gas, whereas p-type electrical conduction is obtained when hydrogen is used more than! 0 vol- ¹ vol nitrogen or noble gases, such as Xet.on. Argon. Contains helium.

The invention is explained in more detail by the following examples, but without being restricted to them

example 1

Fm Si substrate with a (100) (HO) or (111) face, which have been subjected to mirror peeling

ι-, was. was on a C'-carrier coated with SiC " laid and by means of a radio frequency induction hit / ig facility. those with a quartz reaction tube was connected. heated to a wake-up temperature of 930 C, resulting in epitaxial growth

in a B; H (, - concentration of 2x10 'mol / min, and at a PHι / Β ^ Ηο molar ratio of 1 > 0 cause! became. The temperature of the liquid oil zinc contained in a stainless steel bubble counter was at the convenient point within the

t, range from -20 to 50 (held around the Diethyl zinc vapor pressure during cpilakti see growth to control hydrogen (II. ·) was used as an intake gas at the desired rate: between> and 100 cm / min. fed by means of a

in stainless steel tube used for the introduction of the Reaction gas hot about 90 (was kept in -las Quartz reaction tube and then with the reac (ioiis gas mixed. The amount of added diethylzinc (DFZ) was controlled so that cm DEC / U> H "·

>, Molar ratio of 1.0 was obtained.

The ones with Zn donerie. grown in the gas phase BP layer had a film thickness of 2 microns The Si substrate was grown by Λ ι / cn by means of Hl UNO, removed and the Tragerdiihle was

«Ι measured according to the Van der Hmiw-MelliDtlu. The layer doped with / n had a p-line. The BP layer grown in the gas phase that was not doped with zinc. had a n-solution and the carrier density is less than 5 κ 10 ^lb cm '.

hi Fig. I of the accompanying drawings shows the Relationship between the temperature of the liquid dichloride and the carrier concentration in the grown up BP-Schichl. As from the I ig. I to

can be seen, was at a temperature of the liquid wedge below O C there is no p-layer. At a temperature above 10 "C" the carrier clip took with it the rise in temperature of the liquid increases. In the reflective electron diffraction, none became significant Deterioration of the BP layer grown in the gas phase due to the addition of diethyl inks observed. ZN doping could not be satisfactory under conditions other than that The temperature range given above for the crystal growth and the range for the DEZ / B2I Lö molar ratio be achieved. The Zn content in the grown BP layer, which is determined by means of an X-ray microanalyzer was measured, was like that. that it is essentially the electrically measured carrier concentration corresponded.

Example 2

Using the same procedure as in Example 1, elemental cadmium was doped from diethylcadmium (DECd), with the epitaxial growth on the (100) surface of a Si substrate at a B ₂ I! (, - concentration of 2 10 ⁵ mol / min, a Wachsttimstemperatur of 930 ^r C and a pH i / BjUb-Moivcrhaltnis of I:.. worked 50 the Molverhälinis decd / B2II6 was 1: 5. the thus obtained grown BP-layer had a p-conduction and the carrier you The te therein was 2x10 "cm ^!. With a Rönigcn microanalyser, about 10 '^ x 10' cadmium were detected in the BP film. The carrier density in the undoped BP films was always less than 5 ^{× 10 16} cm- '.

As long as the amount of the DECd remained unchanged (DECd / B2H6 = 1: 5) showed the carrier densityc no substantial change and remained within a growth temperature range of 850 to 1000 ° C about 2 χ 10 '* cm'.

Example 3

Using 62Hh-PCh-H ₂ as the reaction gas and adding DEZ to the reaction gas, BP was doped with Zn in the same manner as in Example 1. A Si Substrai with a P-doped (lOO) face was a mil SiC-coated carbon carrier placed and heated by Radiofrcqiienzinduktionserhitzen to a set to 1000 "C growth temperature and in a quartz reaction tube was added together with H ₂ as a carrier gas B .'Hf in a concentration of 2 × 10 'mol / min. _{Phosphorus trichloride (PCh) was blown in by introducing H 2} as a carrier gas, while the vapor pressure of the PCIj was controlled by changing the liquid temperature and then mixed with the carrier gas / B ₂ Hl · was 25. Simultaneously, diethyl zinc (DEZ) was introduced into the reaction gas in the same Wt'se as in Example 1 at a DFZ'BjHh molar ratio of 5 to carry out the introduction of the Zn impurity a p-type BP epitaxial layer having a thickness of 2 microns was obtained. A grown BP layer without Zn doping had a conductivity of the η type and a carrier density of less than ⁵ × 10 17 cm. The temperature was varied during the Zn doping and the electrical properties of the grown BP layers were Measured, it was found that / was within the temperature range / between 150 and 1100 ° C and with a DEC / ßjllb -Molvciliällnis / between 0.05 and 50 satisfactory Zn-doticrlc layers could be obtained, but that the properties of the doped Layers outside of the ranges given above have been severely deteriorated. Within practically the same ranges for the growth temperature and the DEZ / B2IU molecular ratio, a satisfactory Zn doping of BP was also observed for the BCh-PCh-I Ij system. ir <There were no differences with regard to the grading effects of BP compared with the area indices (111) and (110) in Examples I and 2.

Example 4

r, a Si substrate with (100). (110) and (111) surfaces that had been subjected to mirror polishing. were: iüf a mi: SiC owed! ί porters lay! and kept at a wax temperature of 930 ° C. by means of radio frequency induction, and a B2I (, concentration of 2 × 10 'mol / min, and a PH) / B ₂ H (, molar ratio of 50) were simultaneously set HS II, 2nd part, diluted with the reaction gas, mixed with the reaction gas and introduced into a quartz reaction tube, while the quantity

> ϊ has been checked using a flow meter. the 3P doped layers had a film thickness of about 2 microns. After finishing growing up was the silicon core by etching with HF-HNOi removed and the density of triggers wtr'le according to the van der

jo Pauw method measured. The doped BP layer was n-type. An undoped layer had an η conductivity and a carrier density of less than 5 χ \ 0 ' ^b cm'. The gas flow rate at 100ccn / min .. 50ccm / min. and lOOOccm / min ..

i> which indicate the carrier density for the BP layer grown in the gas phase and which are carried out by varying the amount of the doping gas, consisting of H ₂ Si. H2Se and II2TC diluted with H2 up to 300 ppm. are in the table below

■ w I are given and these flow rates correspond to the molar ratio / between the H ₂ S. H ₂ Se. H ₂ Te and B ₂ I! * Of 0.067.0J3 and 0.67. As can be seen from the following Table I, the carrier concentration decreased with the increase in the amount carried

• n amount of H ₂ S. H ₂ Se. H ₂ Te / u.

Table I.

Relationship between the flow rate of H ₂ S, HjSe, H ₂ Te and the carrier density

Ϊ0

Carrier density

Flow rate (cm / min.) Of
H ₂ S. H ₂ Se. H ₂ Te. based on 300 ppm H;

100 500 1000

H ₂ S

H ₂ Se

H ₂ Te

8X10 '

^1.5X1O!;

2X1O ^1S

5X1O ' ^S 9X1O ^IS 8XIO ' ^S 1.5X10 '" IXIO ¹ " 1.5XlO ¹ "

Example 5

Spiking of BP with S, Sc. Te carried out in the same manner as in Example 4 using B ₂ Hi, -PCh-H ₂ as the reaction gas. A BP substrate with a (100) face for crystal growth was coated on one with SiC

C-carrier placed and kept at a growth temperature of 1000 ⁵ C by radiofrequency induction agents and B ₂ H ₆ would be introduced into a quartz reaction tube together with H ₂ carrier gas in a concentration of 2x10 " ⁵ mol / min. H2 as carrier gas was dissolved in phosphorus trichloride ( PCI ₃ ) was initiated, the PCI ₃ vapor pressure being controlled by changing the liquid temperature. The ratio between ihospliortriclilorid and diborane (molar ratio PCU ' ₂ H ₆ ) was 2.5. H ₂ S. 1I ₂ Se or H ₂ Te became at the same time was introduced into the reaction gas in the same manner as in Example 4. As a result, there was obtained a pitactic BP layer having a η conduction in a depth of 2 microns, the carrier concentration for the gas phase grown BP layer, inter use of H ₂ S, H ₂ Se and H ₂ Te, diluted pit H ₂ to 300 ppm, as foreign atom doping gas at a molar ratio of H ₂ S / B ₂ H ₆ of 0.067, H ₂ Se / B ₂ H ₆ (»on 0.067 and H ₂ Te / B ₂ H ₆ at 0.067 h was created, (fctrug 1.5 χ 10 "cm '. l.7xl0 ' ^q cm- ^J or JlOxIO ¹⁹ cm- ³ . The carrier density in the undoped grown BP layer was less than × 10 ¹⁷ cm ^-3 and the layer had an η conductivity. It ( "urde found that within the temperature range 950-1100 ⁰ C and Molverhältnisbcleiches between H ₂ S. H ₂ Se. H Te ₂ and B ₂ U of ⁴ to IO O • satisfactory, with p Se. Te doped layer was obtained, but the properties of the layer outside the ranges mentioned deteriorated greatly.

Example 6

FIG. 2 shows a schematic representation of an apparatus for the method according to the invention. A silicon substrate 16 doped with phosphorus (P) of the • -type with a specific resistance of 10 hm cm and a surface index (100) was placed on • inen C-carrier 15 coated with SiC. Then helium carrier gas was introduced by opening a Wahne ß an p'mpr Hpliumhnmhp 1 711 pinpm reaction <; - R> hr 14.

A Hadiofrequenzenergiequelle was applied to water-cooled cooling coils 13, to bring the! ^ Coated with SiC support C-inductively to the temperature of the substrate 16 of 950 ⁰ C. Then, a delusional 8 was opened and diborane (B ₂ H ₆₎ diluted with H _2, (was from a cylinder 3 in the reaction tube • Total forwards the diborane concentration was 2 χ 10 ^-5 IMOL / min. On the other hand, by operation of a Three-way stopcock 12 and a stopcock 11 on a bomb 4 introduced hydrogen into a vessel 10 into which liquid phosphorus trichloride (PCf ₃ ) 5 had been filled

Reaction tube 14 initiated. The molar ratio between the phosphorus trichloride and diborane (PCl ₃ ZB ₂ H ₆ ) was 25. The phosphorus trichloride concentration was determined by changing the flow rate of the hydrogen bubbling through and by varying the

ίο Liquid temperature and thus the vapor pressure of liquid phosphorus trichloride. controlled. The semiconductor device with grown boron phosphide had a film thickness of 2 microns.

The surface of the grown layer was mirror-like and flat, and it had satisfactory crystallinity when bent under the reflective rviikroelekirunengcicsiei ivUruc. ivic layer had a p-line and a Hall measurement showed a carrier concentration of I χ 10 "cm ^-3 and a mobility of 5 cm / 5 sec.

Example 7

A BP / Si composite semiconductor has been used as the single crystal semiconductor substrate used. The substrate consisted of a boron phosphide single crystal layer on top of a (100) face of an η-type silicon substrate was generated had been. The single crystal layer used had a thickness between 500 and 10,000 A. The single crystal layer with a mirror-shaped and flat surface showed when viewed under reflective Electron diffraction stripes and Kikuchi bands. which show that it had excellent crystallinity.

On the above substrate of the BP / Si composite semiconductor

Using the same procedures as in Example 6, a boron phosphide semiconductor layer was grown to a thickness of 5 microns by introducing a mixture of hydrogen and helium (He / H ₂ = 1) as a carrier gas from a helium bomb 1 and a hydrogen bomb 2 through Press the

to valves 6 and 7 at a growth temperature of 1000 ⁰ C. a Diborankonzentration IxIO- of ⁴ mol / min, and a PCl ₃ ZB ₂ H ₆ - ratio of 20. The surface of the grown layer was spiegeiförmig and flat and had a satisfactory crystallinity on. when tested under reflective electron diffraction. The surface had a p-conduction and the Hall measurement showed a carrier density of 5 × 10 ⁷ cm ^-3 and a mobility of 50 cm / V χ sec.

For this purpose 2 sheets of drawings

Claims (1)

Palent claims: I. A method for epitaxially growing doped boron phosphide on a substrate, wherein Boron hydrides or halides with phosphorus hydrides etc. or halides are reacted at a temperature between 850 and 1100 ° C, thereby characterized in that the reaction mixture contains compounds of the general formula