EP0591496A1

EP0591496A1 - Use of organo-metallic compounds for precipitating metals on substrates

Info

Publication number: EP0591496A1
Application number: EP93908955A
Authority: EP
Inventors: Ludwig Pohl; Herbert Schumann; Wilfried Wassermann; Thomas Seuss; Oliver Just
Original assignee: Merck Patent GmbH
Current assignee: Merck Patent GmbH
Priority date: 1992-04-23
Filing date: 1993-04-19
Publication date: 1994-04-13
Also published as: WO1993022472A1; KR940701462A; DE4213292A1; JPH06508890A

Abstract

On utilise des composés organométalliques contenant comme constituant métallique un élément du 2ème ou du 4ème groupe principal, du 1er au 8ème sous-groupe, des terres rares ou du bismuth, afin de précipiter des métaux sur des substrats. De nouveaux composés de ce type sont également décrits.Organometallic compounds are used containing as metallic constituent an element of the 2nd or 4th main group, from the 1st to the 8th subgroup, rare earths or bismuth, in order to precipitate metals on substrates. New compounds of this type are also described.

Description

Use of organometallic compounds to deposit the metal on substrates

The invention relates to the use of organometallic compounds which are metal as an element of the 2nd or

4th main group, the 1st-8th Subgroup containing rare earths or bismuth for the production of thin films or epitaxial layers by deposition of the metal, primarily from the liquid or the gas phase, with decomposition of the organometallic compounds.

The deposition of such layers from either pure elements or from a combination with e.g. Nitrogen, arsenic or phosphorus can be used to manufacture electrical, electronic, optical or optoelectronic switching elements, compound semiconductors and lasers.

The properties of these films depend on the deposition conditions and the chemical composition of the deposited film.

These layers can be deposited from the solid, liquid or gas phase. All known methods such as the Metal-Organic Chemical Vapor Deposition (MOCVD) method, the Photo-Metal-Organic Vapor Phase, are used for the separation from the gas phase

(Photo-MOVP) method, in which the substances by

UV radiation can be decomposed using the Laser Chemical Vapor Deposition (Laser CVD) method or the Metal-Organic

Magnetron sputtering (MOMS) method in question. The advantages over other methods are controllable

Layer growth, precise doping control as well as easy handling and product friendliness due to the normal or low pressure conditions.

The MOCVD method uses organometallic compounds that decompose when the metal is deposited at a temperature below 1100 ° C. Typical apparatuses currently used for MOCVD consist of a "bubbler" with a feed for the organometallic component, a reaction chamber that contains what is to be coated

Contains substrate, and a source for a carrier gas which is said to be inert to the organometallic component. The

"bubbler" is kept at a constant, relatively low temperature, which is preferably above the melting point of the organometallic compound, but far below the decomposition temperature. The reaction or decomposition chamber preferably has a much higher temperature, which is below 1100 ° C, at which the organometallic compound decomposes completely and the metal is deposited. The organometallic compound is brought into the vapor state by the carrier gas and is carried into the decomposition chamber with the carrier gas. The mass flow of the steam can be controlled well, and thus controlled growth of the thin layers is also possible. The other methods of gas phase separation differ from this essentially only in the way in which the energy required for the decomposition is supplied. A disadvantage of the methods of gas phase deposition is that they are technically and apparatus-intensive and that they require complex control and monitoring of numerous process parameters. If there are no such systems for gas phase separation, methods for separation from the liquid or solid phase are more favorable. Here, the substrate merely has to be provided with a liquid or solid coating which contains a suitable organometallic compound and then thermally treated, for example, to decompose the organometallic compound.

The metal is deposited from the liquid phase, for example, using the spin-on technique. Here, a certain amount of the liquid solution or formulation is applied to the center of the substrate and this is then rotated at a preselected speed. A film of uniform layer thickness is formed on the surface of the substrate, the thickness of which can be adjusted by the spin speed and the viscosity of the formulation and the content of metal can be predetermined by the concentration of the organometallic compound. After evaporation of the solvent and heating above the decomposition temperature of the organometallic compound, the metal layer is obtained on the substrate. So far, mainly metal alkyls such as trimethyl gallium, trimethyl aluminum or trimethyl indium have been used to produce epitaxial layers. These compounds are extremely sensitive to air and moisture, self-igniting and sometimes decomposable above room temperature. Therefore, complex precautionary measures are necessary for their manufacture, transport, storage and use of these compounds. Due to the

Sensitivity is problematic and disposal is practically impossible.

Stabilized metal alkyls, such as adducts with Lewis bases, such as e.g. Trimethylamine and triphenylphosphine (e.g. described in GB 21 23 422,

EP-A 108469 or EP-A 176537) or intramolecularly stabilized compounds of this type (e.g. described in

DE-OS 36 31 469 and DE-OS 38 41 643) can only be used in gas phase deposition methods due to either insufficient stability or excessive volatility.

It was an object of the present invention to find metal organyles which are insensitive and easy to handle and which are suitable both for the separation from the liquid and from the gas phase.

It has now been found that multiply coordinated organometallic compounds which as metal are an element of the 2nd or 4th main group, the 1st-8th Sub-group of the periodic table, an element from the group of rare earths or bismuth, which meet the above conditions in an excellent manner. The invention thus relates to the use of organometallic compounds of the formula I. wherein

R ¹ H, an alkyl group with 1-8 C atoms, which can be partially or completely fluorinated, a cycloalkyl or cycloalkenyl group with 3-8 C atoms or an aryl group,

M is a metal of the 2nd or 4th main group, the 1st,

2nd, 3rd, 4th, 5th, 6th, 7th or 8th subgroup, from the rare earth or bismuth group, n 1, 2, 3 or 4,

0, 1, 2 or 3 means n + o corresponds to the oxidation state of the metal, Z,

- (CHR ² ) _m -,

-NR ² -, or

X '

or

A is a cyclohexane, cyclohexene, cyclohexadiene or phenyl ring,

B is a cyclopentane, cyclopentene or cyclopentadiene ring,

Y and Y 'are each independently - (CH ₂ ) _s -NR ³ R ⁴ ,

- (CH ₂ ) _s -PR ³ R ⁴ , - (CH ₂ ) _s -As ^R3 R ⁴ or - (CH ₂ ) _s -SbR ³ R ⁴ , R ² H, F or alkyl with 1-8 C atoms, the

Alkyl group can be partially or completely fluorinated,

R ³ and R ⁴ each independently of one another H, an alkyl group with 1-8 C atoms, which can be partially or completely fluorinated, a cycloalkenyl or cycloalkyl group with 3-8 C atoms or an aryl group, m 1, 2, 3 or 4 and s, r, p and q each independently represent 0, 1, 2 or 3, it being possible for the compounds of the formula I to have additionally bound one or more neutral ligands, with the proviso that if M = Zn, X then not - (CHR ² ) _m - means for the deposition of the metal on substrates by spin-on or gas phase deposition.

The invention furthermore relates to a method for producing thin films or layers on substrates by

Metal deposition from organometallic compounds, the organometallic compounds of the formula I being used as organometallic compounds. The invention further relates to new compounds of the formula I which correspond to the formula II

wherein R ¹ , o, M, X ', Y, Y' and n have the meaning given in formula I.

Some of the compounds of the formula I are known. For example, coordination chemical studies on zinc dialkyls or on corresponding cadmium and mercury compounds have been described by K.-H. Thiele et al. in Z. anorg. allg. Chem., 462 (1980) 152 or by E. Langguth et al. in Z. anorg. allg. Chem., 530 (1985) 69. The preparation of tetrakis (3-dimethylamine propyl) zirconium was described by E. Langguth et al. in Z. anorg. allg. Chem., 505 (1983) 127. The use of these substances for metal deposition is not mentioned there.

The compounds of the formulas I and II are multi-coordinated and intramolecularly stabilized by electron transfer from the nitrogen, phosphorus, arsenic or antimony atom of group V to the electron-poor metal. They therefore have a particularly high stability against air and oxygen. They are very easy to use because they are not self-igniting and do not decompose at room temperature. Allow to reach 1100 ° C by temperature influence but they decompose with the deposition of the metal. It has been shown that the compounds of the formulas I and II are suitable both for the deposition of the metal from the liquid and from the gas phase. Since the compounds of the formulas I and II contain stable and easily removable leaving groups, there is little incorporation of carbon, which has great advantages for the quality of the end products.

In the formulas I, II and III above and below and in all sub-formulas, M denotes a metal of the 2nd or

4. Main group, preferably magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), germanium (Ge), tin (Sn) or lead (Pb) or bismuth (Bi), a metal of the 5th Main group.

Ca, Ba, Sr, Sn, Bi and Pb are particularly preferred,

Furthermore M means a metal of the 1st, 2nd, 3rd , 4th, 5th, 6th, 7th or 8th subgroup of the periodic table and therefore preferably means copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg ), Scandium (Sc), yttrium (Y), lanthanum (La), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr ), Molybdenum (Mo), tungsten (W), manganese (Mn), rhenium (Re), iron (Fe), cobalt (Co), nickel (Ni), rhodium (Rh), palladium (Pd) or platinum (Pt ). The metals Cd, Zn, Pb, Cu, Mn, Sn, Zr, Hg, Y, Ta, Ti, Ag, Au, Fe, Pd, Ni or Pd are very particularly preferred. M also means a metal from the group of rare earths and accordingly means cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu),

Gadolinium (Gd), Terbium (Tb), Dysprosium (Dy), Holmium (Ho), Erbium (Er), Thulium (Tm), Ytterbium (Yb) or Lutetium (Lu). Ce, Gd, Yb, Pr and Nd are particularly preferred.

The radicals R ¹ , R ³ and R ⁴ each preferably represent a straight-chain or branched alkyl group with 1-8 C atoms, preferably with 1-5 C atoms. The alkyl groups are preferably straight-chain and accordingly preferably mean methyl, ethyl, propyl, butyl, pentyl, further also hexyl, heptyl, octyl, isopropyl, sec-butyl, tert-butyl, 2-methylpentyl, 3-methylpentyl or 2 -Octyl. The alkyl radicals can be partially or completely fluorinated and, for example, monofluoromethyl, difluoromethyl, trifluoromethyl, difluoroethyl,

Trifluoroethyl, Pentaflourethyl or Trifluorpropyl mean.

If R ¹ , R ³ and / or R ^{4 represent} a cycloalkyl or cycloalkenyl group with 3-8 C atoms, they preferably mean cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, cyclohexenyl, cyclohexadienyl, cycloheptyl, cycloheptenyl, cycloheptadienyl, cycloo , Cyclooctenyl, Cyclooctadienyl, Cyclooctatrienyl, Cyclooctatetraenyl or particularly preferably Cyclopentadienyl.

Furthermore, compounds of the formula I or II are preferred in which R ¹ , R ³ and / or R ^{4 are} aryl groups. Aryl group preferably means a phenyl group. This phenyl group can also be substituted. Since these substituents have no significant influence on the intended use, all substituents are allowed who have no disruptive influence on the decomposition reaction. The radical R ¹ and also the radicals R ³ and R ⁴ can occur several times and then have different or the same meaning. n + o corresponds to the oxidation level of the metal used. For example, if M = Zn is n + o = 2, if M = Zr is n + o = 4 and if M = Ca is n + o = 2. n is 1, 2, 3 or 4, o is preferably 0, 1 or 2.

Z means the structural elements -X-Y or

Sub-formulas II and III are thus obtained

The sub-formula II contains new compounds which are also the subject of the invention. Since Y and Y 'can have different meanings, the formulas II and III comprise the compounds of the sub-formulas IIa-IId and IIIa-IIId:

The compounds of the formulas IIa, IIb, IIc, IIIa, IIIb and IIIc are particularly preferred. The compounds of the formulas IIa, IIIa and IIIc are particularly preferred.

For M = Zn the sub-formulas IIa, IIb, IIc, IId, IIIb, IIIc and IIId come into question. The compounds of the formulas Ila, Ilb, IIc, Illb and IIIc are preferred. In the formulas and sub-formulas above and below, A preferably denotes a cyclohexane or phenyl ring, B preferably represents a cyclopentane or cyclopentadiene ring.

Y and Y 'each independently

- (CH ₂ ) _s -NR ³ R ⁴ , - (CH ₂ ) _s -PR ³ R ⁴ , - (CH ₂ ) _s -AsR ³ R ⁴ or - (CH ₂ ) _s -SbR ³ R ⁴ . The groups - (CH ₂ ) _s -NR ³ R ' ¹ and - (CH ₂ ) _s -PR ³ R ⁴ are particularly preferred - Y = Y' is preferred.

R ² is preferably H or an alkyl group with 1-8 C atoms, preferably with 1-4 C atoms, which can also be partially or completely fluorinated. Accordingly, R ² preferably denotes methyl, ethyl, propyl, butyl, trifluoromethyl, tetrafluoroethyl, pentafluoroethyl or heptafluoropropyl, further also pentyl, hexyl, heptyl, octyl, nonafluorobutyl, trifluorhexyl or also difluoropentyl. R ² also means F.

If R ² occurs more than once, the meanings can be the same or different. Then preferably only one R ² does not have the meaning of H. m is 1, 2, 3 or 4, preferably 2 or 3. r, p and q each independently mean 0, 1, 2 or 3, preferably 0, 1 or 2. s is preferably 1 or 2, more preferably also 0. The following group of compounds (1) - (40) represents an exemplary selection of particularly preferred representatives of the formulas I, II or III.

(33) Mg [(CH ₂ ) ₃ -NR ³ R ⁴ ] ₂

(34) Ca [(CH ₂ ) ₃ -NR ³ R ⁴ ] ₂

(35) Sr [(CH ₂ ) ₃ -NR ³ R ⁴ ] ₂

(36) Ba [(CH ₂ ) ₃ -NR ³ R ⁴ ] ₂

(37) V [(CH ₂ ) ₃ -NR ³ R ⁴ ] ₃

(38) Cd [(CH ₂ ) ₃ -NR ³ R ⁴ ] ₂

(39) Hg [(CH ₂ ) ₃ -NR ³ R ⁴ ] ₂

(40) Zr [(CH ₂ ) ₃ -NR ³ R ⁴ ] ₄

The compounds of the formula I can additionally contain one or more neutral ligands of the primary, secondary or tertiary amine type, but also diamines or corresponding

Have bound phosphines, diphosphines, arsanes or diarsanes. The coordination number depends on the size of the central atom and the size of the ligands and varies between 4 and 9.

The known compounds of the formula I and the new compounds of the formula II are prepared by methods known per se, as described in the literature (for example G. Bahr, P. Burbar, Methods of Organic Chemistry, Volume XIII / 4, Georg Thieme Verlag, Stuttgart (1970)) are described, under reaction conditions that are known and suitable for the reactions mentioned. Use can also be made of variants which are known per se and are not mentioned here in detail. For example, compounds of the formulas I and II can be prepared by metal (alkyl) chloride with an alkali metal organyl of the corresponding Lewis base or a

Grignard compound in an inert solvent.

The reactions are preferably carried out in inert solvents. Suitable solvents are all those who do not interfere with the reaction and who do not

Intervene in the reaction. The reaction temperatures correspond essentially to those known from the literature for the preparation of similar compounds.

The organometallic compounds according to the invention prove to be exceptionally stable to air, air humidity and oxygen. They show no change even if they are exposed to the air for a long time. They are stable at room temperature, but can be decomposed at elevated temperatures with metal deposition. In addition, they show only a low vapor pressure at room temperature and are therefore not very volatile. Their solubility in organic

Solvents such as aliphatic or aromatic hydrocarbons or ether are excellent.

Because of these properties, the organometallic compounds of the formula I are in principle suitable for all methods of depositing metals by decomposing organometallic compounds.

The organometallic compounds of the formula I are particularly suitable and preferably to be used for the deposition of the metal from the liquid or the gas phase. In the process according to the invention for the production of thin films or epitaxial layers on any substrates, methods known per se for the deposition from the liquid or the gas phase can be used, but in which the metal organic compounds of the formula I are used.

Liquid bunny deposition can be carried out, for example, by using a substrate, e.g. one

Silicon wafers coated with a liquid formulation which contains an organometallic compound of the formula I - in the simplest case this is a solution of this compound in an organic solvent. This coating can preferably be carried out by the known method of "spin coating", which has already been described.

The reaction conditions for the gas phase deposition processes known per se and already described here can be selected analogously to the values known from the literature and familiar to the person skilled in the art.

For the production of mixed metal layers, compound semiconductors, electrical, electronic, optical and optoelectronic components or semiconductor lasers, the formulation can also contain compounds of different metals and other elements of the periodic table, preferably compounds of elements of the 5th main group. During the decomposition process, one or more compounds suitable under the reaction conditions used, in particular arsenic, antimony or

Phosphors, such as AsH ₃ , As (CH ₃ ) ₃ , or others

Dopants are supplied. Mainly organometallic compounds of iron, magnesium, zinc or chromium can also be used as dopants. Frequently used compounds are Zn (CH ₃ ) ₂ , Mg (CH ₃ ) ₂ or Fe (C ₅ H ₅ ) ₂ .

It is also possible to add the compounds of the formula I themselves as dopants in deposition processes of other organometallic compounds.

Those produced by the processes of the invention

Layers can be used for a wide variety of components, depending on which metal connections are used. For example, the thin film systems produced according to the invention can be used for capacitors, sensors, superconductors, metal films, diodes, fast transistors, electro-optical switches, optical memories and much more.

The following examples are intended to explain the invention in more detail, temperatures are always given in degrees Celsius.

Mp. Means melting point and Kp. Boiling point. example 1

A solution of 0.28 mol of barium chloride in 100 ml is added dropwise at room temperature to a 24.3 g (1.0 mol) of magnesium and 102.1 g (0.84 mol) of 3-dimethylaminopropyl chloride in Grignard reagent prepared in 500 ml of THF THF and then heated to 70 ° C for 2 h. After cooling down

Insoluble matter was separated off by filtration, the solvent was removed and the residue was distilled in vacuo. Bis (3-dimethylaminopropyl) barium is obtained.

You get analog

Bis (3-dimethylaminopropyl) strontium

Bis (3-dimethylaminopropyl) calcium

Example 2

A Grignard reagent prepared from 4.9 g (0.2 mol) of Mg and 19.4 g (0.16 mol) of 3-diethylaminopropyl chloride in 100 ml of THF is mixed with 0.05 mol of barium chloride in 100 ml of THF at room temperature. When the reaction has ended, the mixture is stirred at room temperature for 24 h, filtered, the solvent is removed and the residue is distilled in vacuo. You get

Bis (3-diethylaminopropyl) barium. The following are produced analogously

Bis (3-diethylaminopropyl) strontium

Bis (3-diethylaminopropyl) calcium

Bis (3-diethylaminopropyl) cadmium

Bis (3-diethylaminopropyl) mercury

Example 3 Analogously to Example 1, bis (3-dimethylaminopropyl) cadmium is obtained from 3-dimethylaminopropyl magnesium chloride and cadmium chloride as a colorless liquid with a boiling point of 62 ° C./0.3 mbar. Example 4 Analogously to Example 1, bis (3-dimethylamino-propyl) mercury is obtained from 3-dimethylaminopropyl-magnesium chloride and mercury chloride as a colorless liquid with a boiling point of 96 ° C./0.05 mbar.

Example 5

A Grignard reagent is prepared from 6.1 g (0.25 mol) of Mg and 24.3 g (0.2 mol) of 3-dimethylaminopropyl chloride in 100 ml of THF. About 80 ml of THF are then removed and 50 ml of pentane are added to the concentrated solution. Precipitated magnesium chloride is removed by filtration and the residue is distilled in vacuo. You get

Bis (3-dimethylaminopropyl) magnesium as a white solid with bp 170 ° C / 0.05 mbar. The following is obtained analogously: bis (3-diethylaminopropyl) magnesium Example 6

A solution of 8.71 g of 3-dimethylaminopropyllithium in 150 ml of diethyl ether at a temperature of -5 ° C. with exclusion of light is mixed with 5.45 g of ZrCl ₄ , then stirred for one hour and then the solvent is removed in vacuo. The residue is extracted several times with n-pentane. The combined extracts are filtered and cooled to a temperature of -78 ° C, with colorless needles of

Eliminate tetrakis (3-dimethylaminopropyl) zirconium.

Example 7

An ethereal solution of 12 g of 3-dimethylamino-propyllithium is added dropwise to a suspension of 16 g of CrCl ₃ 3 THF in 200 ml of diethyl ether at a temperature of -30 ° C. in the course of 4 hours. The mixture is stirred for a further 2 hours, the ether is removed and the residue is extracted with n-pentane. Red crystals of tris (3-dimethylaminopropyl) chromium separate from the extract at -78 ° C.

Claims

1. Use of organometallic compounds

Formula I. wherein

M is a metal of the 2nd or 4th main group, the

1st, 2nd , 3rd, 4th, 5th, 6th, 7th or 8th subgroup, from the group of rare earths or bismuth, n is 1, 2, 3 or 4, o is 0, 1, 2 or 3, n + o corresponds to the oxidation state of the metal, Z X - (CHR ² ) _m -,

-NR ² -, or .

X '

.

or

-

A is a cyclohexane, cyclohexene, cyclohexadiene or phenyl ring,

B is a cyclopentane, cyclopentene or cyclopentadiene ring,

Y and Y 'are each independently - (CH ₂ ) _s -NR ³ R ⁴ ,

- (CH ₂ ) _s -PR ³ R ⁴ , - (CH ₂ ) _s -AsR ³ R ⁴ or - (CH ₂ ) _s -SbR ³ R ⁴ , R ^{2 is} H, F or alkyl having 1-8 C atoms, where the alkyl group can be partially or completely fluorinated, R ³ and R ^{4 are} each independently H, one

Alkyl group with 1-8 C atoms, which can be partially or completely fluorinated, a cycloalkenyl or cycloalkyl group with 3-8 C atoms or an aryl group, m 1, 2, 3 or 4 and s, r, p and q each independently 0, 1,

2 or 3 mean, where the compounds of the formula I may additionally have bound one or more neutral ligands, with the measure that in the case M = Zn, X then not

- (CHR ² ) _m - means for the deposition of the metal on substrates by spin-on or gas phase deposition. Use of organometallic compounds

Formula I according to claim 1 for the deposition of epitaxial layers.

3. Process for the production of thin films or layers on substrates by metal deposition from organometallic compounds, characterized in that the compounds of the formula I according to Claim 1 are used as organometallic compounds.

4. The method according to claim 4, characterized in that for the manufacture of electrical, dielectric, electronic, optical and optoelectronic systems during the deposition process one or more compounds of arsenic, antimony or phosphorus which are suitable under the reaction conditions used are supplied.

5. The method according to claim 4, characterized in that in addition to the organometallic compounds

Formula I adds dopants during the deposition process.

6. The method according to claim 4, characterized in that the compounds of formula I according to claim 1 are added as dopants during the deposition process of other organometallic compounds.

7. Compounds of formula II

wherein R ¹ , o, M, X ', Y, Y' and n are those in formula I in

Claim 1 have given meaning. Compounds of formula II according to claim 7, characterized in that they additionally have one or more neutral ligands coordinated.