This paper presents a critical review of conventional and novel planarization processes such as Glass Flow, Etchback with or without a sacrificial layer, SOG, BSQ, Polyimide, Substrate-biased PECVD, and Pillars. Key issues in a planarization process, e.g., surface morphology, process simplicity and reliability, material characteristics, and etch control are discussed. A comparison of various planarization processes is tabulated. The future trend of the planarization technology is examined according to the above principles.
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