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Chemical vapor deposition TiN process for contact/via barrier applications

 

作者: Ajit Paranjpe,   Mazhar IslamRaja,  

 

期刊: Journal of Vacuum Science&Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena  (AIP Available online 1995)
卷期: Volume 13, issue 5  

页码: 2105-2114

 

ISSN:1071-1023

 

年代: 1995

 

DOI:10.1116/1.588084

 

出版商: American Vacuum Society

 

关键词: ACTIVATION ENERGY;COMPUTERIZED SIMULATION;ELECTRIC CONDUCTIVITY;ELECTRIC CONTACTS;ROUGHNESS;STRESSES;TEMPERATURE DEPENDENCE;TITANIUM NITRIDES;TiN

 

数据来源: AIP

 

摘要:

Chemical vapor deposition (CVD) TiN is an attractive replacement for PVD TiN as a barrier and glue layer for subhalf‐micron contacts and vias. CVD TiN films have been deposited in a commercial reactor via the thermal decomposition of tetrakis‐dimethyl‐amino‐titanium (TDMAT) precursor in an N2ambient. The deposition can be characterized by a simple Arrhenius rate expression with a half‐order dependence on TDMAT concentration and an activation energy of 0.53 eV. Designed experiments show that the deposition transitions from being kinetically limited at high TDMAT flow rates and low temperatures to transport limited at the other extreme. In the kinetically limited regime, the deposition rate increases with increasing TDMAT mole fraction and increasing temperature. Step coverage simulations have been performed by couplingSPEEDIE(a profile evolution program) with the Arrhenius rate expression. Experimental and simulated step coverages show good agreement over a wide range of process conditions. Step coverage improves with increasing deposition rate and decreasing temperature. Adequate deposition rates (≳400 Å/min) with good deposition uniformity and high step coverage (50%–85%) can be achieved. Film stress and roughness are mostly invariant with process conditions. These films are close to stoichiometric (i.e., 1:1 Ti:N ratio), but contain up to 30% carbon. Exposure of these films to air causes rapid oxidation with a steady state concentration of 15%–20% oxygen after 24 h of air exposure.The high carbon concentration results in high film resistivity (5000 μΩ cm), which doubles after 24 h of air exposure due to oxidation of the film. Film resistivity decreases and film stability improves with increasing N2flow rate. Electrical characterization of two process variants have been performed. The first provides a film with 85% step coverage with a resistivity of 5600 μΩ cm, while the second process achieves a lower resistivity of 3700 μΩ cm and a lower step coverage of 50%. Electrical performance of both films is similar. Contact induced diode leakage is lower for CVD TiN compared to PVD TiN. Contact resistance for 100–200 Å CVD TiN is comparable or lower than 500 Å PVD TiN. A 100 Å CVD TiN barrier is adequate; 300 Å CVD TiN is too thick because of high film resistivity. An Al–Cu/100–300 Å CVD TiN/Si stack shows lower resistance increase after 450–500 °C, 30 min N2anneal compared to a Al–Cu/200 Å PVD TiN/Si stack indicating that CVD TiN is a superior barrier and is more inert than PVD TiN.

 

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