AVS 45th International Symposium
    Vacuum Metallurgy Division Monday Sessions
       Session VM-MoA

Paper VM-MoA2
Low Temperature Polycrystalline Silicon Resistors on Glass Substrates

Monday, November 2, 1998, 2:20 pm, Room 328

Session: Plasma Assisted Surface Treatments and Coatings
Presenter: A.T. Krishnan, Pennsylvania State University
Authors: A.T. Krishnan, Pennsylvania State University
S.H. Bae, Pennsylvania State University
S.J. Fonash, Pennsylvania State University
Correspondent: Click to Email
Polycrystalline silicon (poly-Si) thin film resistors have been processed on glass substrates at low temperatures (<300@degree@C) using a novel approach. This approach involves direct deposition of n+ polycrystalline silicon thin films using an electron cyclotron resonance (ECR) high density plasma (HDP) tool, with phosphine as the dopant source. These n+ poly-Si films have been deposited on both Corning 1737 glass and soda-lime glass substrates at 300@degree@C. The dependence of film quality on film thickness has been exploited to obtain devices with resistivities over a range of 1-10 ohm-cm. The range of resistivities that can be obtained can be further increased by altering the phosphine flow rate. The deposition rates are of the order of 100 Å per minute. The temperature coefficient of resistivity of these devices is less than 2000 ppm/@degree@C. Preliminary studies indicate that it is possible to obtain n+ poly-Si films at temperatures lower than 200@degree@C, which would allow the use of clear flexible plastic substrates. Thin film resistors processed at low temperatures find a wide range of applications, such as flat panel displays, multi-chip modules,@footnote 1@ anolog circuits, @footnote 2@ and high frequency applications.@footnote 3@ In CMOS technology, low temperature resistor fabrication would enable integration of resistors on fully processed Si chips. Conventional non silicon based resistor technology requires more than one material, such as a cermet for high resistivities and a metal for low resistivities, to achieve a wide resistivity range. Currently existing Si based resistor technologies, like LPCVD cannot be used for low temperature applications, because of the high deposition temperatures (600@degree@C, which is close to aluminum melting point) or higher temperatures needed for dopant activation (700-800@degree@C). The HDP technique allows the use of a single material (n doped poly-Si) to obtain a wide range of resistivities. Because it is Si based, it is compatible with current ULSI processing techniques. Its low deposition temperature and the fact that no annealing is required to activate dopants makes it ideally suited for low temperature applications listed above. @FootnoteText@ @footnote 1@Integration of passive components for microwave filters in MCM-D, Pieters, Philip; Brebels, Steven; Beyne, Eric, Proceedings of the 1997 6th International Conference and Exhibition on Multichip Modules 1997 Denver, CO, USA p 357-362. @footnote 2@BiCMOS analog front-end circuit for an FDM-based ADSL system Langford, D. Scott; Tesch, Bruce J.; Williams, Brian E.; Nelson, G. Rodney; Ross, Robert B.; Bechtel, Gerry R.; Lewis, Mike G, Proceedings of the 1997 Bipolar/BiCMOS Circuits and Technology p 180-182. @footnote 3@110 GHz slow-wave electrodes for velocity-matched distributed MSM photodetectors with integrated bias load, Pfitzenmaier, H.; Boettcher, E.H.; Droege, E.; Bimberg, D, Proceedings of the 1997 IEEE Lasers and Electro-Optics Society Annual Meeting, USA p 218-219