Improvement of Barrier Properties of TaN Film by Plasma Enhanced Atomic Layer Deposition
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0914-F09-09
Improvement of Barrier Properties of TaN Film by Plasma Enhanced Atomic Layer Deposition In Cheol Baek1, Han Choon Lee1, Cheonman Sim1, Jae Won Han1, Kee Ho Kim1, Soo Hyun Kim2, and Sahng Kyoo Lee2 1 Advanced Nano-tech Development Division, Dongbu Electronics, 474-1 Sangwoo-ri, Gamgokmyeon, Eumseong-gun, Chungbuk, 369-852, Korea, Republic of 2 Advanced Development Team, IPS Ltd., 33, Jije-dong, Pyeongtaek, Gyeonggi-do, 450-090, Korea, Republic of
ABSTRACT The barrier metal properties of Plasma Enhanced ALD (PEALD) TaN deposited on low-k
℃
dielectric film (SiCOH) with a k value of 3.0 at a deposition temperature of 300 by using pentakis (ethylmethylamino) tantalum (PEMAT) and various plasma gases was investigated. The film resistivity of TaN is about 1000 µΩ· under the plasma power of 200 W and the frequency
㎝
㎝
of 400 KHz, respectively. The resistivity was significantly reduced by approximately 360 µΩ· for the optimized condition of 300 W and 13.56 MHz. In addition, good uniformity was obtained by applying two-step plasma treatment process. The film thickness per cycl of the TaN using
Å
Å
two-step plasma was decreased from 1.0 to 0.65 by reducing a base pressure, indicating the increase of the film density. The PEALD TaN with almost 100% coverage in this paper’s dual damascene structure has a contact resistance of about 1.6 Ω/chain at via size of 0.19um.
INTRODUCTION A bilayer of TaN/Ta deposited by PVD has been typically used as the Cu diffusion barrier. As the device dimension of the integrated circuits continues to shrink with technology development, PVD has the limitation to achieve conformal step coverage across the dual damascene structure. Atomic layer deposition (ALD) is being actively developed as an attractive candidate to deposition of TaN Cu barrier layer in the Cu/low k interconnects for 65nm technology node and beyond.[1,2] However, this ALD with halogen precursors has problems such as high deposition temperatures and high Cl contamination.[3] The Cl impurities lead to corrosion of the Cu interconnect lines.[4] Therefore, the ALD with metal-organic precursors has been suggested to solve these problems.[5] However, the diffusion barrier layers deposited using the ALD method with metal-organic precursor shows relatively high carbon impurity incorporation, poor film density, and high resistivity. Recently, many studies have suggested the use of plasma to improve the film quality and to overcome the problem involved in the conventional ALD.[6,7] However, relatively little research has been carried out on the uniformity of PEALD TaN film. The uniformity within wafer is an important factor for fabrication of semiconductor device.
In this work, we will introduce a PEALD process by applying two-step plasma treatment which is improved the uniformity and achieved low resistivity and low impurity concentration.
EXPERIMENT The PEALD TaN was deposited on a SiCOH low-k dielectric film (k = 3.0) at a deposition temperature 300 by using pentakis (ethylmethylamino) tantalum (PEMAT) and various
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