Adaptive Piezo-Controlled Carrier for CMP Processing
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Adaptive Piezo-Controlled Carrier for CMP Processing Christian-Toralf Weber1, Jürgen Weiser1, Dieter Zeidler2, Johann W. Bartha2 1 IGAM - Engineering Company for Applied Mechanics Ltd., Steinfeldstraße 3-5, D-39179 Barleben, Germany, www.igam-mbh.de 2 Semiconductor and Microsystems Technology Laboratory, Dresden University of Technology, Nöthnitzer Straße 64, D-01062 Dresden, Germany, www.tu-dresden.de/etihm
ABSTRACT
The IGAM engineering company for applied mechanics Ltd. developed an active piezocontrolled carrier for CMP. It uses several, by means of piezo-stacks individually controllable rings. The carrier is optimized regarding its stiffness and reliability by means of threedimensional finite element calculations. The high stiffness and positioning accuracy of the system allows the exact control of different surface profiles and thus the purposeful attitude of the pressure and removal profile independently of the polishing pressure. Tests show a very homogeneous pressure and removal distribution in the circumference of the wafer. The concept is transferable on further wafer diameters, whereby the width of the individual zones can be widely adapted to the requirements of the desired removal profile. Results of finite element analysis for a 12” prototype are available. The variable concept allows to upgrade existing CMP machines. The aims of current developments are the integration of in-situ-pressure determination to control the process, wireless transfer of energy and data to the carrier and the control of the local removal profile.
COMPANY AND PRODUCTS
The IGAM engineering company for applied mechanics Ltd., founded in 2000, is a specialized provider of innovative engineering services. The business fields of our company spans from technical consultancy through to development and implementation of mechanical and adaptronic systems. We develop and sell active systems for vibration and noise reduction, as well as active tools for surface processing like grinding and polishing of high precise surfaces [1]. Our customers are active in many fields: from general mechanical engineering, optical and semiconductor industry, vehicle construction up to medical technologies.
Figure 1. Carrier with Electronics.
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INTENTION
For the surface processing of semiconductors and micro systems the chemical-mechanical planarization was established. With ever smaller structures increasingly higher demands are created on the accuracy of the planarization processes An as evenly as possible removal rate (RR) respectively a low non-uniformity (WIWNU) is one of the major requirements. Nonuniformities of the removal appear especially in the boundary region at the wafer edge, but can be observed also within the entire wafer surface [3, 4]. Attempts have been made to adjust pneumatically or hydraulically the back pressure of special rings, of the carrier to obtain a uniform removal profile. It has been shown that there is a strong functional dependence between the adjusted polishing force and the local pressure distributi
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