High Planarization Efficiency and Wide Process Window Using Electro-chemical Mechanical Planarization (Ecmp TM )
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High Planarization Efficiency and Wide Process Window Using Electro-chemical Mechanical Planarization (EcmpTM) Feng Q Liu, Liang Chen, Alain Duboust, Stan Tsai, Antoine Manens, Yan Wang, Wei-Yung Hsu Thin Films Group, Applied Materials, Inc. 3050 Bowers Ave., P. O. Box 58039, Santa Clara, CA 95054, USA Contact: [email protected] ABSTRACT EcmpTM is a revolutionary planarization technology uniquely combining removal rate controlled by charge with superior planarization efficiency in the near no shear regime. In addition, the electrochemical removal mechanism has excellent within-wafer profile control. Multiple electrical zones configuration combined with a precise end-point control by electric charge, make it more predictable to control the remaining thickness and profile of copper film. The factors affecting the planarization such as the concentration and the efficiency of the inhibitors will be discussed in this paper. Meanwhile a planarization mechanism for Ecmp will be proposed to match the high planarization efficiency. The effects of applied voltage on removal rate and planarization efficiency will be presented in this paper. The electrical feature allows Ecmp to be a planarization process with removal rate independent of down force, enabling a wide removal rate window based on applied voltage. INTRODUCTION Chemical Mechanical Planarization (CMP) is a balanced polish process, relying on the chemical interaction of the slurry with polishing substrate and mechanical down force applied to the substrate[1]. For the fabrication of 65nm and beyond technology nodes with fragile low k dielectric and copper, the down force of CMP process must be greatly reduced or eliminated to manage the low mechanical strength of low k dielectric, and to reduce dishing and erosion [2-3]. The Electrochemical Mechanical Planarization (Ecmp) process was developed to fulfill the strict technical and manufacturing challenges for 65nm and beyond technology nodes in the fabrication of advanced interconnects [4]. Above all of the challenges faced by CMP process, the main issue is the lower removal rate due to the low mechanical down force required by the low k dielectric; secondary issues involve low k dielectric damage during metal layer polishing, metal layer peeling, erosion, etc. In this new Ecmp technology and process, electrical potential is the driving force to oxidize metal copper to the ions. Then, copper ions react with chemistry in electrolyte to go in solution or form a passivation layer. Since this passivation layer is removed easily, mechanical down force is not a factor to achieve high removal rate in Ecmp process, enabling the use of a virtually no-down force (
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