JP2570839B2 - Al-Cu alloy thin film forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an Al-based wiring for an integrated circuit device or the like.
The present invention relates to a method for forming a Cu alloy thin film.

[Conventional technology]

The aluminum-based thin film for forming the wiring of the integrated circuit device needs to be deposited on the step portion with good coverage, and the bias sputtering method (J. Electrochem.
Soc., 1985, 132, 1466) and chemical vapor deposition (J. Eletcrochem. Soc, Magazine, 1984, 131, 2175).
Page published paper) (hereinafter abbreviated as CVD method).

In addition, there is a report in which Si is added to Al in the CVD method having excellent step coverage (Paper No. 28a-v-6, second edition, p. 605, Proceedings of the 35th Federation of Applied Physics Related Lectures, p. 605).

[Problems to be solved by the invention]

However, along with the miniaturization of LSIs, it is necessary to miniaturize the wiring width used and the contact holes of the electrodes, and therefore, electromigration and stress migration due to an increase in current density have become a problem. Generally, Al has a small atomic weight and is easy to move, so that the above-described problem occurs. It is known that the addition of Cu to Al has an effect on migration in the sputtering method, but the conventional sputtering method cannot cope with miniaturization of LSI. The same addition is possible by the bias sputtering method, but the sample is exposed to the impact of charged particles such as ions and electrons due to the application of a bias, causing the characteristics of the element and wiring to fluctuate. It is known to

Although a method of forming an Al-Si film using CVD with good step coverage has been reported, Si is deposited at a contact portion at a normally required process temperature, and an increase in contact resistance is observed. Contact failure has been reported (Digest of Technical Papers, 1986 Symposiu
m on VLSI Technology Paper No. V-4, pp. 55-56, May 19
86).

For this reason, a technique that simultaneously satisfies both step coverage and electromigration resistance has not been realized.

An object of the present invention is to provide a method for forming an Al—Cu alloy thin film that simultaneously satisfies step coverage and electromigration resistance.

[Means for solving the problem]

To achieve the above object, in the Al-Cu alloy thin film forming method of the present invention, the organic aluminum as a raw material of aluminum, cyclopentadienyl copper triethyl phosphine adduct _{Cu (C 5 H 5) ·} P (C 2 H 5 ₃ ) A copper raw material is used, and an Al—Cu alloy thin film is formed from these raw materials using a chemical vapor deposition method.

[Action]

The present invention utilizes the fact that the source gases are hardly reacted only by being mixed during transportation, and that the respective metals are generated by thermal decomposition on the wafer surface. In other words, the decomposition temperature is 250 ° C or higher for organic aluminum as an Al raw material, and 130 ° C or higher for cyclodienyl copper triethylphosphine adduct as a Cu raw material. accumulate. Further, by controlling the flow rate of each source gas, Al and
The composition ratio of Cu can be controlled.

It has been reported that an Al-Cu alloy film formed by sputtering is effective for stress migration (Proceeding o
f Second International IEEE VLSI Mulilevel Interco
nnection Conference pp.173-179, June 1985). This is thought to be because the migration of Al atoms is suppressed by the addition of Cu, and thus the migration resistance of Al is enhanced. Therefore, an Al—Cu alloy film formed by CVD is also expected to have excellent migration resistance.

〔Example〕

FIG. 1 is a configuration diagram of a gas mixer and a low-pressure CVD apparatus for forming an Al—Cu alloy thin film. In the figure, 1 is a hydrogen gas cylinder, 2 is a mass flow controller for adjusting the flow rate of hydrogen gas, 3 is a bubbler container for mixing organic Al raw material with hydrogen gas, and 4 is a temperature control for controlling the temperature of the bubbler. Vessel, 9 is a vessel for mixing the copper raw material with hydrogen gas, 10 is a temperature controller for controlling the temperature of the vessel, 11 is a mass flow controller for controlling the flow rate of hydrogen gas for controlling the flow rate of the copper raw material. 5 is a growth chamber, 6 is a wafer, 7 is a heater for controlling the temperature of the wafer, and 8 is an exhaust system.

First, dimethyl aluminum hydride is sealed in the bubbler container 3, the hydrogen gas is caused to flow while being controlled by the mass flow controller 2, and the vapor pressure component of the raw material is mixed in the bubbler container 3 at a partial pressure ratio. In addition, a cyclopentadienyl copper triethylphosphine adduct (Cu (C
₅ H ₅ ) · P (C ₂ H ₅ ) ₃ ) is sealed, and the hydrogen gas is allowed to flow while being controlled by the mass flow controller 11, and the vapor pressure component of the raw material is mixed in the vessel 9 at a partial pressure ratio. The carrier gas containing these raw materials is mixed and introduced into the growth chamber 5 which has been reduced in pressure (several Torr) by the exhaust system 8. At this time, the pressure in the growth chamber 5 is 1 Torr, the carrier gas is hydrogen and the mass flow controller 2 controls the pressure to 60 SCCM, the temperature of the bubbler vessel 3 is adjusted to 25 ° C. by the temperature controller 4, and the temperature of the vessel 9 is adjusted to the temperature. The temperature is kept at 80 ° C. in the vessel 10. At this time,
The partial pressure of the Al source gas is 0.1 Torr, and the partial pressure of the copper source gas is 0.05 t
estimated as orr. The wafer 6 placed in the growth chamber 5 is maintained at 250 ° C. by the heater 7. The introduced raw material is heated on the wafer 6 to deposit an Al-Cu alloy by thermal decomposition. The film deposited in this manner was excellent in step coverage, and contained about 1% of Cu in Al and had excellent migration resistance.

In the present invention, the following applications are possible. As a raw material, other organic aluminum such as triisobutylaluminum, dimethylaluminum chloride and methylaluminum dichloride can be used instead of dimethylaluminum hydride.

〔The invention's effect〕

As described above, according to the present invention, there is an effect that an Al—Cu alloy thin film having high migration resistance can be formed by using a CVD method capable of filling a fine contact hole.

[Brief description of the drawings]

 FIG. 1 is a block diagram of an apparatus for implementing the method of the present invention. DESCRIPTION OF SYMBOLS 1 ... Hydrogen cylinder 2 ... Mass flow controller 3 ... Bubbler container 4 ... Temperature controller 5 ... Growth chamber, 6 ... Wafer 7 ... Heater, 8 ... Exhaust system 9 ... Container, 10 ... Temperature controller 11 ... Mass flow controller

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-74650 (JP, A) JP-A-63-179076 (JP, A) JP-A-62-202079 (JP, A) JP-A 55-746 138856 (JP, A) JP-A-1-11975 (JP, A) U.S. Pat. Society 92:17 (1970-8) 5114-5117 IEEE IEDM Proceeding (1993) 277-280.

Claims (1)

(57) [Claims] An organic aluminum is used as an aluminum source, a cyclopentadienyl copper triethylphosphine adduct Cu (C ₅ H ₅ ) .P (C ₂ H ₅ ) ₃ is used as a copper source, and a chemical vapor deposition method is used. A method for forming an Al-Cu alloy thin film, comprising forming an Al-Cu alloy thin film from these raw materials.