ILD CMP 스크래치와 관련된 슬러리 부산물의 물리적, 화학적 특성 평가

Abstract

ABSTRACT

Oxide CMP process has been well accepted for the planarization of the dielectric oxide film and becomes a critical process in ULSI manufacturing due to the rapid shrinkage of the design rule for the device. But CMP process generates defects inevitably such as micro-scratch, pit, and polishing residue. As the design rule becomes smaller and smaller, among these defects micro-scratches cause severe circuit failure, the reduction of durability and reliability and the increase of current leakage in semiconductor. It is important to develop post CMP cleaning process to observe scratches since they are not easy to detect on flat oxide surfaces. A new method was proposed to detect scratches and also the dependency of these scratches on process parameters such as pressure, slurry concentration and type of conditioner was examined. The variation of the scratches was observed by varying head pressure, slurry concentration and diamond conditioner. The number of scratches was increased with increase of both pressure and slurry concentration. And some study has been done on understanding the scratch generation, but there is no elaborated information. In this work, understanding of type, size, location, number and source of the scratches on scratch generation and the change of scratch shape with change of scratch source were discussed. It was found that the presence of dried/large slurry particles will produce more number of scratches than diamond particles. The pad debris didn’t show much effect in increasing the number of scratches. The distributions of scratch shape were obtained as a function of scratch source. The large particles will generate mostly chatter type scratches, where as diamond particles generated line type scratches. Both chatter type and line type scratches were varied slightly with the presence of pad debris. However in detail study with pad debris is necessary to understand the typical role of pad debris in generating the scratches. And CMP by-products could be generated from many consumables during CMP process. To analyze CMP by-products, DI water and slurry were gathered during conditioning and polishing. In the case of conditioning with DI water, pad particles were observed in used DI water. These pad debris which were over 1um size had irregular shape and size. These weren’t detected during ex-situ conditioning, but pad debris was observed during in-situ conditioning. These large particles could induce scratches during polishing.