Precursors for deposition of metal oxide layers or films

Abstract

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.