Proposal and experimental study of a high‐precision polycrystalline‐silicon film resistor with a quasi‐double‐layer structure

We propose a high-precision polycrystalline-silicon film resistor having a quasi-double-layer (QDL) composed of a large-grain layer and a small-grain layer. The electrical characteristics of the polycrystalline-silicon film resistor can be controlled by varying the shapes of the crystal grains. Therefore, we fabricated a QDL structure composed of a large-grain layer with a resistance having a positive temperature coefficient and a small-grain layer having a negative temperature coefficient by making the top of a small-grain polycrystalline-silicon film amorphous by ion implantation followed by recrystallization in thermal processing. This technique is equivalent to macroscopically controlling the grain diameter in the entire film. In this paper, the QDL structure is clearly (1) effective in lessening the effect of fluctuations in the deposited film thickness on variations in the resistance and (2) can control the resistance and its temperature coefficient by adjusting the ion implantation energy and varying the ratio of the large-grain layer and the small-grain layer. We also show that it is possible to produce a polycrystalline-silicon film resistor having any temperature coefficient by using the proposed structure in the resistive elements. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 87(7): 9–17, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10174