PRECURSORS FOR DEPOSITION OF METAL OXIDE LAYERS OR FILMS
Rare earth metal precursors, for use in MOCVD techniques have a ligand of the general formula OCR 1 (R 2 )CH 2 X, wherein R 1 is H or an alkyl group, R 2 is an optionally substituted alkyl group and X is selected from OR and NR 2 , wherein R is an alkyl group or a substituted alkyl group. Methods of making such precursors and methods of depositing metal oxide layers from such precursors are also described.
1 . Rare earth metal precursors, for use in MOCVD techniques having a ligand of the general formula OCR 1 (R 2 )CH 2 X, wherein R 1 is H or an alkyl group, R 2 is an optionally substituted alkyl group and X is selected from OR and NR 2 , wherein R is an alkyl group or a substituted alkyl group.
2 . A precursor as claimed in claim 1 having the following general formula:
M[OCR 1 (R 2 )(CH 2 ) n X] 3
wherein M is a rare earth metal R 1 is H or an alkyl group, R 2 is an optionally substituted alkyl group and X is selected from OR and NR 2 , wherein R is an alkyl group or a substituted alkyl group, n=1 to 4.
3 . A precursor as claimed in claim 1 or 2 , wherein M is praseodymium.
4 . A precursor as claimed in any one of claims 1 to 3 , wherein the ligand of the formula OCR 1 (R 2 )(CH 2 ) n X is 1-methoxy-2-methyl-2-propanolate (mmp) [OCMe 2 CH 2 OMe].
5 . A precursor as claimed in claim 1 or 2 , wherein the ligand is chosen from the group of OCH(Me)CH 2 OMe, OCEt 2 CH 2 OMe, OCH(Et)CH 2 OMe, OC(Pr i ) 2 CH 2 OMe, OCH(Pr i )CH 2 OMe, OC(Bu t ) 2 CH 2 OMe, OCH(Bu t )CH 2 OMe, OCH(Bu t )CH 2 OEt, OC(Bu t ) 2 CH 2 OEt, OC(Pr i ) 2 CH 2 OEt, OCH(Bu t )CH 2 NEt 2 , OC(Pr i ) 2 CH 2 OC 2 H 4 OMe and OC(Bu t )(CH 2 OPr i ) 2 .
6 . Pr(mmp) 3 .
7 . La(mmp) 3 .
8 . Gd(mmp) 3 .
9 . Nd(mmp) 3 .
10 . A method of making rare earth metal oxide precursors for use in MOCVD techniques comprising reacting a ligand HOCR 1 (R 2 )(CH 2 ) n X, wherein R 1 is H or an alkyl group, R 2 is an optionally substituted alkyl group and X is selected from OR and NR 2 , wherein R is an alkyl group or a substituted alkyl group, n=1 to 4, with the corresponding rare earth metal alkylamide M(NR 2 ) 3 or silylamide precursor M(N(SiR 3 ) 2 ) 3 precursor, Pr{N(SiMe 3 ) 2 } 3 , wherein R=alkyl, in appropriate molar proportions.
11 . A method as claimed in claim 10 , wherein the ligand is mmpH.
12 . A method as claimed in claim 10 or 11 , wherein the rare earth metal compound is praseodymium. silylamide.
13 . A method as claimed in claim 10 or 11 , wherein in the rare earth metal alkylamide or silylamide R is selected from Me, Et and Pr i .
14 . A method of making lanthanide and rare earth element complexes of the formula M[OCR 1 (R 2 )CH 2 X] 3 , wherein R 1 is H or an alkyl group, R 2 is an optionally substituted alkyl group and X is selected from OR and NR 2 , wherein R is an alkyl group or a substituted alkyl group and n=1 to 4, comprising the salt exchange reaction of M(NO 3 ) 3 (tetraglyme) with an akali metal or alkaline earth metal salt of [OCR 1 (R 2 )CH 2 X] 3 (mmp) in tetrahydrofuran solvent.
15 . A method as claimed in claim 14 , wherein the alkali metal salt is Na(mmp).
16 . A method as claimed in claim 14 or 15 , wherein the rare earth metal complex prepared is selected from Sc(mmp) 3 , Y(mmp) 3 and Ln(mmp) a .
17 . A method of depositing single or mixed oxide layers or films by MOCVD using a rare earth metal precursors having a ligand of the general formula OCR'(R 2 )CH 2 X, wherein R 1 is H or an alkyl group, R 2 is an optionally substituted alkyl group and X is selected from OR and NR 2 , wherein R is an alkyl group or a substituted alkyl group, in which the precursor is contained in a metalorganic bubbler.
18 . A method of depositing single or mixed oxide layers or films by MOCVD using a rare earth metal precursors having a ligand of the general formula OCR 1 (R 2 )CH 2 X, wherein R 1 is H or an alkyl group, R 2 is an optionally substituted alkyl group and X is selected from OR and NR 2 , wherein R is an alkyl group or a substituted alkyl group, or by liquid injection MOCVD, in which the precursor is dissolved in an appropriate inert organic solvent and then evaporated into the vapour phase using a heated evaporator.
19 . A method as claimed in claim 18 , wherein the solvent is selected from aliphatic hydrocarbons, aromatic hydrocarbons and aliphatic and cyclic ethers.
20 . A method as claimed in claim 19 , wherein the aliphatic hydrocarbon solvent is selected from hexane, heptane and nonane.
21 . A method as claimed in claim 19 , wherein the aromatic hydrocarbon solvent is toluene.
22 . A method as claimed in any one of claims 18 to 21 , wherein the solvent contains an additive selected from polydentate ethers and donor functionalised alcohols.
23 . A method as claimed in claim 22 , wherein the polydentate ether is selected from diglyme, CH 3 —O—(CH 2 CH 2 O) 2 CH 3 , triglyme, CH 3 —O—(CH 2 CH 2 O) 3 CH 3 , and tetraglyme, CH 3 —O—(CH 2 CH 2 O) 4 CH 3 .
24 . A method as claimed in claim 22 , wherein the donor functionalised alcohol is 1-methoxy-2-methyl-2-propanol HOCMe 2 CH 2 OMe (mmpH).
25 . A method as claimed in claim 22 , 23 or 24 , wherein the amount of additive added to the solvent is at least 3 mol. equiv.:mol. equiv of precursor.
26 . A method as claimed in claim 25 , wherein the amount of additive added to the solvent is in the region of 3 mol. equiv.
27 . A method as claimed in any one of claims 18 to 26 , wherein the precursor has the following general formula:
M[OCR 1 (R 2 )(CH 2 ) n X] 3
wherein M is a rare earth metal R 1 is H or an alkyl group, R 2 is an optionally substituted alkyl group and X is selected from OR and NR 2 , wherein R is an alkyl group or a substituted alkyl group, n=1 to 4.
28 . A method as claimed in any one of claims 18 to 27 , wherein M is praseodymium.
29 . A method as claimed in any one of claims 18 to 28 , wherein the ligand of the formula OCR 1 (R 2 )(CH 2 ) n X is 1-methoxy-2-methyl-2-propanolate (mmp) [OCMe 2 CH 2 OMe].
30 . A method as claimed in any one of claims 18 to 28 , wherein the ligand is chosen from the group of OCH(Me)CH 2 OMe, OCEt 2 CH 2 OMe, OCH(Et)CH 2 OMe, OC(Pr i ) 2 CH 2 OMe, OCH(Pr i )CH 2 OMe, OC(Bu t ) 2 CH 2 OMe, OCH(Bu t )CH 2 OMe, OCH(Bu t )CH 2 OEt, OC(Bu t ) 2 CH 2 OEt, OC(Pr i ) 2 CH 2 OEt, OCH(Bu t )CH 2 NEt 2 , OC(Pr i ) 2 CH 2 OC 2 H 4 OMe and OC(Bu t )(CH 2 OPr i ) 2 .
31 . A method as claimed in any one of claims 18 to 30 , wherein the precursor is Pr(mmp) 3 .
32 . A method as claimed in any one of claims 18 to 30 , wherein the precursor is La(mmp) 3 .
33 . A method as claimed in any one of claims 18 to 30 , wherein the precursor is Gd(mmp) 3 .
34 . A method as claimed in any one of claims 18 to 30 , wherein the precursor is Nd(mmp) 3 .
35 . A method of depositing single or mixed oxide layers or films by atomic layer deposition (ALD) using a rare earth metal precursors having a ligand of the general formula OCR 1 (R 2 )CH 2 X, wherein R 1 is H or an alkyl group, R 2 is an optionally substituted alkyl group and X is selected from OR and NR 2 , wherein R is an alkyl group or a substituted alkyl group.
36 . A method as claimed in claim 35 , wherein metal oxide film being deposited is a praseodymium oxide film.
37 . A method of depositing single or mixed oxide layers or films by a non-vapour phase deposition technique using a rare earth metal precursors having a ligand of the general formula OCR 1 (R 2 )CH 2 X, wherein R 2 is H or an alkyl group, R 2 is an optionally substituted alkyl group and X is selected from OR and NR 2 , wherein R is an alkyl group or a substituted alkyl group.
38 . A method as claimed in claim 37 , wherein the technique used is selected from sol-gel deposition and metal-organic decomposition.
39 . A method as claimed in any one of claims 17 to 38 , wherein M is selected from La, Ce, Gd, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tin, Yb and Lu as well as Group IIIB elements including Sc and Y.
40 . A method as claimed in any one of claims 17 to 39 carried out with appropriate co-precursors, for the MOCVD of multi-component oxides.