Copper (1) precursors for chemical deposit in gas phase of metal

Details Copper (1) precursors for chemical deposit in gas phase of metal Copper (1) precursors for chemical deposit in gas phase of metal

1999-12-15

2000-10-10

Nazario-Gonzalez, Porfirio

Organic compounds -- part of the class 532-570 series

Organic compounds

Heavy metal containing

356117, 4272481, 427587, C07F 108, C23C 1600

Patent

active

061303453

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to the chemical deposit method in gas phase of pure metals such as copper and silver, in the electronics industry, for the production of integrated circuits. This method, called CVD for "Chemical Vapor Deposition" is widely used to produce, from precursors of said metals in oxidised form (+1), the interconnections and metallisation of integrated circuits measuring 0.25 .mu.m or less.
Numerous copper precursors are known in the prior art for the fabrication of films made up of said pure metal. The most promising precursors are complex compounds of oxidised copper (+1) stabilised by a ligand in which the copper is compounded with a .beta.-diketonate having the following general formula: ##STR1## in which R, R' and R", identical or different, are chosen from among a hydrogen atom, a halogen atom such as fluorine, a lower alkyl optionally substituted by one or more fluorine atoms.
Preferred complexes are those in which R is a hydrogen atom and R' and R" are perfluorine alkyls, advantageously --CF.sub.3 groups meeting the following structural formula: ##STR2##
Such complexes and the way they are used in the CVD method are, for example, described in U.S. Pat. Nos. 5,085,731, 5,096,737, 5,098,516, 5,144,049, 5,187,300 whose teaching on the CVD method is incorporated herein by reference.
The work conducted on these precursors demonstrates that their molecular structure is decisive for the reproducible production of films of good quality (P. Doppelt and T. H. Baum, MRS Bull. XIX(8) 41, 1994). However, the electronics industry does not have available an ideal precursor for the reproducible fabrication of electronic circuits containing thin copper films to enable defect-free filling of vertical lines and interconnections that offers low resistivity and good long term thermal stability.
As reported in the above-mentioned patents, the formation of metallic copper results from the dismutation of two copper molecules (I) on a surface heated to a temperature close to 200.degree. C. in accordance with the following reaction:
The nature of the Lewis base L, also called hereafter the ligand, only slightly influences the nature of the copper films obtained by CVD. Copper films are generally very pure, free of carbon or oxygen atoms (less than 1%), and resistivity in the region of 1.8 .mu..OMEGA. is frequently found in copper films obtained by CVD; this value is very close to the one found in solid copper (1.67 .mu..OMEGA..cm). On the other hand, the nature of ligand L determines the volatility of the complex and consequently the rate of deposit of the copper obtained.
In the prior art, more than 80 copper complexes (I) (hfac) are known which have been tested for the CVD of copper, such as for example: least one non-aromatic insaturation cited in U.S. Pat. No. 5,098,516; U.S. Pat. No. 5,096,737; C.sub.1 to C.sub.8.
The three copper precursors for CVD, liquid at ambient temperature, given in Table I below have been the subject of particular study:


TABLE I ______________________________________ Precursors Volatility ______________________________________ Very volatile up to 200 nm/min (H .sub.2 O) - Scarcely volatile: 140 nm/min - Very volatile up to 400 nm/min. Formation of a less volatile secondary product ______________________________________
Among the latter, the (3-hexyne) Cu(hfac) complex is the one which gives the highest growth rate. On the other hand, it has recently been shown that it leads to the formation of dinuclear complexes which form a major obstacle to its use (P. Doppelt and T. H. Baum, Journal of Organometallic Chemistry 517, 53-62, 1996).
In order to remedy this disadvantage, the inventors have examined electronic phenomena related to the formation of dinuclear complexes during the use of a copper complex for CVD stabilised by a ligand made up of an alkyne whether substituted or not. Research work conducted has been able to demonstrate that the formation of these dinuclear species is helped when the alkyne carries electron-donor groups, such a

REFERENCES:
patent: 5144049 (1992-09-01), Norman et al.
patent: 5663391 (1997-09-01), Machida et al.

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