A study on dielectric properties of a new polyimide ®lm suitable for interlayer dielectric material in microelectronics applications q A. Kuntman a, * , H. Kuntman b,1 a Department of Electrical and Electronics Engineering, Faculty of Engineering, Istanbul University, Avcilar 34850, Istanbul, Turkey b Department of Electronics and Communication Engineering, Faculty of Electrical and Electronics, Istanbul Technical University, Maslak 80626, Istanbul, Turkey Accepted 5 May 2000 Abstract Interlayer dielectric ®lm formation under Al wirings for VLSI and ULSI devices requires low temperature processing and high surface planarization capability. Polymers as a dielectric material play a signi®cant role in achieving the current state-of-the art in microelectronics. In this work, the dielectric properties of a new polyimide material suitable for microelectronics applications have been investigated. The polyimide was synthesized following the synthesis of 4,4 0 -bis(3-aminophenoxy)diphenyl sulfone (DAPDS), by nucleophilic aromatic substitution of 4,4 0 -dichlorodiphenyl sulfone with m-aminophenol, DAPDS/pyromellitic dianhydride (PMDA). Using this speci®c poly- imide, a metal±polyimide±silicon (MIS) structure was manufactured to demonstrate the dielectric properties of the material. The properties of the MIS capacitance have been examined by deriving an electrical model of the MIS structure. q 2000 Published by Elsevier Science Ltd. Keywords: Properties and characterization; Device technology; Materials systems 1. Introduction Interlayer dielectric ®lm formation under Al wirings for VLSI and ULSI devices requires low temperature proces- sing and high surface planarization capability. Polymers as a dielectric material play a signi®cant role in achieving the current state-of-the art in microelectronics [1±27]. Poly- meric materials are not only found in ®nal products such as housing of components, packaging of integrated circuit (IC) chips, and intermetallic dielectric layers, but they are also employed extensively in major processing steps such as resists in microlithography. Especially, polyimides (PI), cyclic-chain polymers, have desirable properties for use in the microelectronics industry because they are a group of excellent high temperature heat-resistant organic polymers and have good planarization capability and electrical insu- lating properties [3±5]. Shrinking dimensions of the struc- tures on integrated circuits have led to a need for interlayer dielectric materials with low dielectric constants. Multilevel structures consisting of alternating metal and dielectric layers are necessary to achieve interconnecting of high density or VLSI circuits using CMOS or bipolar technology. For interconnect dimensions ,0.5 mm, such as the 0.25 mm generation and beyond, high thermally stable organic poly- mers which exhibit suf®ciently low permittivity would be needed. Recently, several papers have reported the use of polyimide for multilevel interconnect systems [6±9,26,27]. In this work, the dielectric properties of a recently reported new polyimide material [9,12,27] suitable for microelectronics applications have been investigated. The polyimide was synthesized following the synthesis of 4,4 0 - bis(3-aminophenoxy)diphenyl sulfone (DAPDS), by nucleophilic aromatic substitution of 4,4 0 -dichlorodiphenyl sulfone with m-aminophenol, DAPDS/pyromellitic dianhy- dride (PMDA) [12]. It was further shown that the new poly- imide material exhibits good adhesion as patterned on metal, ®lls small gaps, is patternable, and provides small capacity at low temperature as a stand-alone polyimide [9,27]. Using this speci®c polyimide, a metal±polyimide± silicon (MIS) structure was manifactured to demonstrate the dielectric properties of the material. The properties of the MIS capacitance have been examined by deriving an elec- trical model of the MIS structure. The model parameters were optimized to provide a good ®t with the experimental Microelectronics Journal 31 (2000) 629±634 Microelectronics Journal 0026-2692/00/$ - see front matter q 2000 Published by Elsevier Science Ltd. PII: S0026-2692(00)00067-7 www.elsevier.com/locate/mejo q This work partially supported by the Research Fund of University of Istanbul. Project number O È -479/280998. * Corresponding author. Tel.: 190-212-591-1998, ext. 1298; fax 190- 212-591-1997. E-mail addresses: akuntman@istanbul.edu.tr (A. Kuntman), kuntman@ehb.itu.edu.tr (H. Kuntman). 1 Tel: 190-212-285-36-47; fax: 190-212-285-35-65.