Effect of Wettability of Poly Silicon on CMP Behavior
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0991-C09-06
Effect of Wettability of Poly Silicon on CMP Behavior Young-Jae Kang1, Bong-Kyun Kang1, In-Kwon Kim1, Jin-Goo Park1, Yi-Koan Hong2, SangYeob Han2, Seong-Kyu Yun2, Bo-Un Yoon2, and Chang-Ki Hong2 1
Metallurgy & Materials Eng., Hanyang University, 1271 Sa-1dong, Sangrok-gu, Ansan, 426791, Korea, Republic of 2
Process Development, Memory Division, Device Solution Network, Samsung Electronics, San #16, Banwol-Dong, Hwasung, 445-701, Korea, Republic of ABSTRACT The hydrophobicity of poly Si is reported to introduce different polishing behavior with careful control of post CMP cleaning process. The purpose of this study was to investigate the effect of poly Si wettability on its CMP behavior. The adhesion force of polymeric particle on the poly Si wafer surfaces was measured in the KOH solution (pH 11) as a function of solution A concentration. Adhesion force decreased and saturated as a function of concentration of solution A. The change of surface wettability affects not only the polishing rates but also the level of contamination on wafer because the interactions between particles and substrates are dependent on the wettability of the surface. Also, hydrophobic poly Si surfaces attracted much more pad particles with water marks than hydrophilic. INTRODUCTION As the design rule decreases in semiconductor manufacturing industry, multilayer integration using CMP is being widely adopted to obtain a flat surface during processing [1]. By applying CMP to poly Si surface micromaching, micromechanical devices can be realized with planarized surface topographies, improved pattern definition, delineation, and resolution, and reduced surface and side wall roughness [2]. In the micro-scale heat transfer applications such as micro-channel, thermal insulation layer or heat exchanger the use of poly Si, which has a very large thermal conductivity, to form the main structure is very important due to its large thermal conduction and heat loss as mentioned [3]. Poly Si CMP uses either the same or similar pads or slurries as those for oxide CMP. Poly Si CMP is consecutively used in order to form self aligned memory cell contact pad [4]. After CMP process, the wafer surface was contaminated with abrasive particle and polymeric residues from pad, retainer ring, and other consumables. Poly Si surface is hydrophobic in nature. Therefore, after CMP, the poly Si surface attracts more hydrophobic organic residues than the oxide surface. The purpose of this study was to investigate the adhesion and removal of the polymeric residues as a function of wettability of the poly Si surface during poly Si CMP process. EXPEREMENT In order to investigate the effect of poly Si wettability on organic type defects in poly Si CMP, contact angles of poly Si and adhesion force were measured. Contact angle was characterized by using a drop shape contact angle analysis system (Krüss, G10). All force curve
measurements were carried out using an Atomic Force Microscope (AFM, PSIA, XE-100). The 40 µm diameter sized irregular polymeric pad particle a
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