JP3998138B2 - Substituted cycloalkene novel copper precursor for chemical vapor deposition of copper metal thin films - Google Patents

Description

  The present invention relates to the synthesis of volatile liquid copper precursors and the application of the precursors in chemical vapor deposition of copper metal thin films.

  In recent years, interest in chemical vapor deposition of copper metal thin films has increased. A copper metal thin film material has a low resistance value of up to 1.7 μΩ · cm and a high electric transfer resistance value, and is thus considered to be ideal as a material used for metal interconnection in an integrated circuit.

  Copper chemical vapor deposition (CVD) requires the use of stable and volatile precursors. For commercialization, the cost of the copper precursor becomes a problem. In addition, the copper precursor should have good adhesion to the metal nitride coated substrate, a low resistance value of up to 1.8 μΩ · cm, high compatibility with the surface structure, and good electromigration resistance. The CVD process is generally performed at high temperatures, but in this process, the copper precursor is to achieve a moderate deposition rate in the CVD liquid delivery line or without decomposing while in the evaporator. It must have sufficient vapor pressure and must be stable at the deposition temperature.

Copper metal thin films are provided by chemical vapor deposition using various copper precursors. In 1990, D.C. B. In "Low-Temperature Chemical Vapor Deposition of High Purity Copper from an Organometallic Source " by Beach et al. (Chem.Mater. (2) 216 ( 1990)), pure copper ^{_{film, (η 5 -C 5 H 5}} ) Cu It is obtained by CVD using (PMe ₃ ). At about the same time, Hampden-Smith, M.M. J. et al. Chem. Mater. (2) 636 (1990) shows the same result by using (tert-BuO) Cu (PMe ₃ ). However, these copper films contain carbon and phosphorus. Carbon and phosphorus are elements that constitute contaminants when used as interconnects in integrated circuits. Therefore, these copper films cannot be used as interconnectors in microprocessors. A study of copper precursors conducted in the early 1990s was a series of copper fluoride (I) β-diketonate complexes that have proven to be very promising materials for use in chemical vapor deposition of copper metal thin films Concentrated on the evaluation.

  Copper fluoride (I) β-diketone acid complexes are disclosed in U.S. Pat. No. 4,385,005, issued on May 24, 1983, “Process for separating unhydrated hydrocarbons using silver complexes with fluoride, Synthesized by Gerald Doyle, as described in US Pat. No. 4,425,281, “Copper or silver complexes with fluorinated diketones and unsaturated ligands” granted on January 10, 1984. In US Pat. Nos. 4,385,005 and 4,425,281, Gerald Doyle presents a synthetic method and its application in the separation of unsaturated organic hydrocarbons.

  U.S. Pat. No. 5,096,737 granted to Baum et al. On March 17, 1992, “Ligand Stabilization + 1 Metal Beta-Diketate Coordination Complexes and Thirteen Use in Chemical Vapor Depot Met. Application examples of copper (I) β-diketonic acid complexes as copper precursors for the provision of copper thin films by CVD are described. Copper thin films have been provided by chemical vapor deposition using these precursors. Among several liquid copper precursors, 1,5-dimethyl 1 mixed with 1,6-dimethyl 1,5-cyclooctadiene copper (I) hexafluoroacetylacetonate ((DMCOD) Cu (hfac)) , 5-cyclooctadiene copper (I) hexafluoroacetylacetonic acid and hexyne copper (I) hexafluoroacetylacetonic acid ((HYN) Cu (hfac)) mixed 1,5-dimethyl 1,5-cyclooctadiene Copper (I) hexafluoroacetylacetonic acid was evaluated in detail. A copper thin film deposited using (DMCOD) Cu (hfac) has good adhesion to a metal or metal nitride substrate, but has a high resistance value of up to 2.5 μΩ · cm and a slow deposition rate. When (HYN) Cu (hfac) is used, the adhesion of the copper film to the TiN substrate is low and the resistance value is high, up to 2.1 μΩ · cm.

  Another compound, 2-butyne copper (I) (hfac) ((BUY) Cu (hfac)), forms a copper film having a low resistance value of up to 1.93 μΩ · cm, but has a low adhesiveness, Since it is expensive and the compound is solid, it needs to be vaporized before CVD.

  The formation of copper (I) (hfac) is described in US Pat. No. 5,085,731, “Volatile liquid preparations for the chemical vapor deposition of copper” granted to Norman et al. On Feb. 4, 1992. As described above, a series of trialkylvinylsilanes (TMVS) stabilized and thereby improved copper films were obtained. A copper film deposited using a liquid copper precursor of (hfac) Cu (TMVS) has a low resistance value and an appropriate adhesion to a substrate. Although this liquid copper precursor has been used for some time to provide copper metal films by CVD, it still has some drawbacks. Stability, poor copper film adhesion, and the cost of trimethylvinylsilane stabilizers are major obstacles preventing this technology from being widely used.

  Other references include Gerald Doyle, K. et al. A. Eriksen and D.M. Van Engen's Organometallics 4,830 (1985), Thomas H. et al. Baum and Carl E.M. Larson's Chem. Mater. 4, 365 (1992), as well as Thomas H. et al. Baum and Carl E.M. Larson's J.M. Electrochem. Soc. 140 (1) and 154 (1993).

  Methods for forming volatile copper precursors for chemical vapor deposition of copper metal thin films are described by the chemical formula (n-Rm-cyclohexene) Cu (I) (hfac) or (n-Rm-cyclopentene) Cu (I ) (Hfac). Here, n, m = 1 to 6, and R is alkyl such as methyl and ethyl.

  It is an object of the present invention to provide a series of new highly volatile liquid copper precursors for chemical vapor deposition of copper metal thin films.

  Another object of the present invention is to provide such precursors in an economical and stable manner.

  These and other objects and advantages of the present invention will become more apparent upon reading the following description with reference to the drawings.

  The present invention relates to a series of volatile copper precursor chemical vapor deposition (CVD) synthesis and precursor synthesis for the formation of copper metal thin films. Copper films deposited using these novel liquid copper precursors have good electrical properties and good for metals and metal nitride substrates such as W, Ti, TiN, Ta, TaN, Al, Pt, etc. It shows adhesiveness.

In order to achieve the object of the present invention, the precursor is:
a. Having high volatile liquid phase and fast copper deposition rate to form copper thin films,
b. Stable at room temperature for easy storage and handling,
c. It is necessary to have a reasonable synthesis cost for commercialization.

Using this new copper precursor, the copper film provided by CVD is
a. Good adhesion to metals and metal nitride substrates such as TiN, WN, TaN, etc.
b. Having a low resistance value of up to 1.9 μΩ · cm,
c. Has a high electromigration resistance,
d. It must have good compatibility with extreme surface morphology.

  The invention described herein is a novel highly volatile liquid thin metal copper precursor, known (1-methyl-1-cyclohexene) -copper (I) hexafluoroacetylacetonic acid, ie, (1M1CH) Cu ( I) Preparation of (hfac). The price of 1-methyl-1-cyclohexene is about 120 USD per 100 g. This is much lower than the price of trimethylvinylsilane used in the prior art, generally about $ 180 per 100 g. Experimentally, CVD tests using this precursor have shown that this new highly volatile liquid copper thin metal precursor has the desired properties and meets all the above requirements.

Copper films deposited using these novel liquid copper precursors show good electrical properties, good for metals and metal nitride substrates such as W, Ti, TiN, Ta, TaN, Al, Pt, etc. Excellent adhesion. These organometallic copper complexes are (n-R-m-cyclohexene) Cu (I) (hfac) shown in FIG. 1 or (n-R-m-cyclopentene) Cu (I) (hfac) shown in FIG. ). Here, (n, m = 1 to 6), and R is alkyl such as methyl and ethyl. Preferably, R is CH ₃ , thereby forming a (1-methyl-1-cyclohexene) Cu (I) (hfac) compound as shown in FIG.

  All steps in the synthesis process are performed in a dry glove box without air or by using standard Schlenk techniques. The solvent is purified before synthesis. Dichloromethane is refluxed and distilled under nitrogen in the presence of calcium hydride before use. In a preferred embodiment, 1-methyl-1-cyclohexene and 1,1,1,5,5,5-hexafluoroacetylacetone are from Aldrich and Strem, respectively, and are used as is without further purification. .

  Synthetic procedures for organometallic copper (I) complexes are described in US Pat. No. 4,385,005 (see above). In US Pat. No. 4,385,005, copper monoxide can react with unsaturated organic hydrocarbons and 1,1,1,5,5,5-hexafluoroacetylacetone in dichloromethane or THF. Are listed. The reaction is represented by the following formula:

ここで、Ｌは、不飽和有機炭化水素配位子である。

Here, L is an unsaturated organic hydrocarbon ligand.

  Although the desired product is obtained by synthesizing (1M1CH) Cu (hfac) according to the synthetic procedure described above, unfortunately, this product is not stable for extended periods at room temperature. To solve the stability problem, about 5% (% by weight of product) of 1-methyl-1-cyclohexene is introduced into the product for stabilization. By following this procedure, no solid precipitate is observed after the compound has been allowed to stand for 1 month.

In the synthesis of (1M1CH) Cu (hfac), 41.26 g Cu ₂ O (0.29 mol) is placed in a 500 ml round bottom flask containing 200 mL CH ₂ Cl ₂ . The flask is equipped with a stir bar. To this Cu ₂ O dichloromethane red solution, 57 mL of 1-methyl-1-cyclohexene (0.48 mol) is added. This solution is stirred for about 5 minutes at room temperature. 100 g of 1,1,1,5,5,5-hexafluoroacetylacetone (0.48 mol) is introduced with stirring. After 1 minute, the color of the solution gradually turns green. The green solution is stirred continuously for another 10 minutes and filtered through celite. The pore size of the Celite filter is between about 10 μm and 25 μm.

  The green filtrate is stripped under vacuum for 2 hours, then heated to 35 ° C. under vacuum and stripped for another half hour. This produces a green liquid organometallic copper compound containing a small number of small green crystals. The compound is then filtered through a fine filter (1 μm) to yield 145.7 g of product with a yield of 82.64% based on hfac. The theoretical yield based on H (hfac) is 176.3 g. For stabilization, 1-methyl-1-cyclohexene (6.437 g) is introduced into the product (138.621, total 145.058 grams). The product contains 4.44% free 1-methyl-1-cyclohexene.

  NMR structural analysis is performed with a QE 300 MHz NMR instrument. The results are as follows.

（１Ｍ１ＣＨ）Ｃｕ（ｈｆａｃ）液体前駆物質を用いる、ＣＶＤによる銅金属薄膜堆積の結果は、非常に良好である。銅薄膜は、金属または窒化金属の基板に対する良好な接着性、１．８μΩ・ｃｍまでの低い抵抗値、および非常に良好な再現性を示す。前駆物質は、非常に揮発的であり、非常に速い堆積速度、すなわち、１分あたり約５００Åの堆積速度が、５０℃の非常に低い蒸発器温度で、０．１ｍｌ／分の液体注入速度を用いて、達成される。

The results of copper metal thin film deposition by CVD using (1M1CH) Cu (hfac) liquid precursor are very good. The copper thin film exhibits good adhesion to a metal or metal nitride substrate, a resistance value as low as 1.8 μΩ · cm, and very good reproducibility. The precursor is very volatile, with a very fast deposition rate, i.e. a deposition rate of about 500 liters per minute, with a liquid injection rate of 0.1 ml / min at a very low evaporator temperature of 50 ° C. To achieve.

  Thus, a novel synthesis method is adopted for the synthesis of (1-methyl-1-cyclohexene) copper (I) (hexafluoroacetylacetonic acid). (1-Methyl-1-cyclohexene) copper (I) (hexafluoroacetylacetonic acid) is a novel liquid copper precursor that contains about 5% 1-methyl-1-cyclohexene as a stabilizer at room temperature. It becomes stable and has high volatility. A copper film provided by chemical vapor deposition of (1-methyl-1-cyclohexene) copper (I) (hexafluoroacetylacetonic acid) has good adhesion to metal and metal nitride substrates and low resistance. Copper films provided by chemical vapor deposition using (1-methyl-1-cyclohexene) copper (I) (hexafluoroacetylacetonic acid) are useful and fully functional in IC devices.

  While the preferred embodiment of the invention and several variations thereof have been disclosed, it will be apparent that further variations or modifications may be made without departing from the scope of the invention as set forth in the appended claims. is there.

FIG. 1 is a diagram illustrating the structure of (nRm-cyclohexene) Cu (I) (hfac). FIG. 2 is a diagram illustrating the structure of (nRm-cyclopentene) Cu (I) (hfac). FIG. 3 is a diagram illustrating the structure of (1-methyl-1-cyclohexene) Cu (I) (hfac).

Claims (9)

A method of forming a volatile liquid copper precursor for chemical vapor deposition of a copper metal thin film comprising:
Placing 200 mL of CH ₂ Cl ₂ in a container;
Adding about 41.26 g (0.29 mol) of Cu ₂ O to form a Cu ₂ O dichloromethane red solution;
Adding 57 mL (0.48 mol) of 1-methyl-1-cyclohexene;
Stirring the solution at room temperature for about 5 minutes;
Adding about 0.48 mol of β-diketone;
Stirring for about 11 minutes;
Filtering the solution through Celite having a filter pore size between about 10 μm and 25 μm;
Stripping the solution under vacuum for about 2 hours;
Heating the solution to about 35 ° C. under vacuum and stripping for about 30 minutes;
Filtering the solution with a fine filter having a pore size of about 1 μm;
Adding from about 5% to about 10% by weight of stabilizing ligand. The method of claim 1, wherein adding about 0.48 mol of β-diketone comprises adding about 100 g of 1,1,1,5,5,5-hexafluoroacetylacetone. The step of adding the stabilizing ligand comprises adding about 6.437 g of 1-methyl-1-cyclohexene to (n-Rm-cyclohexene) Cu (I) (hfac) and (nR-m -Cyclopentene) A step of producing a copper precursor having a chemical formula selected from the chemical formula group consisting of Cu (I) (hfac), wherein (n, m = 1-6), wherein R is 2. The method of claim 1 comprising the step of being an alkyl selected from the alkyl group consisting of methyl and ethyl. A method of forming a volatile copper precursor for chemical vapor deposition of a copper metal thin film comprising (n-Rm-cyclohexene) Cu (I) (hfac) and (n-Rm-cyclopentene) Cu ( I) forming a volatile liquid having a chemical formula selected from the chemical formula group consisting of (hfac), where n, m = 1-6, and R is an alkyl consisting of methyl and ethyl A method comprising the step of being alkyl selected from the group. 5. The method of claim 4, comprising the step of adding a stabilizing ligand. 6. The method of claim 5, wherein adding the stabilizing ligand comprises adding 1-methyl-1-cyclohexene. 7. The method of claim 6, wherein adding 1-methyl-1-cyclohexene comprises adding about 5% to about 10% by weight of 1-methyl-1-cyclohexene. The method of claim 4, further comprising adding a β-diketone. 9. The method of claim 8, wherein adding the [beta] -diketone comprises adding 1,1,1,5,5,5-hexafluoroacetylacetone.

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