A Study on STI and Damascene CMP using Chip Level Simulation
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A Study on STI and Damascene CMP using Chip Level Simulation Kyung-Hyun Kim, Yoo-Hyon Kim*, Kwang-Bok Kim, Chang-Ki Hong, Moon-Hyun Yoo*, qTsGuSGqT{GrQGGzTpGsG Process Development Team, *CAE, Semi. R&D Center, Samsung Electronics Co., Ltd. San#24 Nongseo-Ri, Kiheung-Eup, Yongin-City, Kyungki-Do, KOREA Tel : 82-2-760-5289, Fax : 82-2-760-6120, E-mail : [email protected] ABSTRACT Simulation of chemical-mechanical polishing is important because the chip-level planarity are difficult to control. The simulator has been developed for predicting and optimizing the thickness distribution after the STI and damascene CMP as well as ILD CMP using chip-level pattern density, elastic spring model and erosion model. In this study, the results of CMP simulation is shown to agree well with the measured data. The simulator can be used to optimize CMP process conditions and to generate design rules for filling dummy patterns which are used to improve the planarity and uniformity. INTRODUCTION In chemical-mechanical polishing (CMP), the global planarity is dependent on many dynamic factors (i.e., layout, feature size, pattern density, film material, deposition process, etc.). CMP factors include time, pressure, velocity, temperature, slurry feed rate, polishing motion, slurry chemistry, slurry particle size, carrier film, pad hardness and pad conditioning. In STI CMP process, the film thickness varies on the chip because of the above many factors. As a result, it affects subsequent processes and causes poly stringer and the source of leakage currents. To suppress these phenomena, it is necessary to achieve uniform and global planarization. Therefore, simulation is getting more important to cover dynamic factors effectively and to predict topography after CMP because experiments are extremely time consuming. Although many simulation approaches have been introduced in CMP modeling so far [1-3], there has been no attempt to establish the systematic simulator that can predict the planarity after STI and damascene CMP in product level. In order to describe the planarization and erosion, we introduced the concepts of elastic model, erosion model and local density model involving surround density proposed by previous researchers [4-6]. In this study, we present a methodology to predict the planarity after STI and damascene CMP process, and verify the computation accuracy as comparing to experiment and simulation. MODELING Fig.1 depicts the flowchart in the CMP simulation system. It consists of four steps: calculation of local pattern density from e-beam data, calculation of effective pattern density using sizing and superposition, calculation of pattern density of surrounding cells by convolving the weight functions, and chip level simulation using the elastic and erosion model. The chip level simulation responses to question of local planarity and it is the most important part. One major application is to establish the monitoring points from the surrounding pattern
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