Growth of polycrystalline silicon at 470 °C by magnetron sputtering onto a sputtered μc-hydrogenated silicon seed layer

Abstract

We deposit polycrystalline silicon (px-Si) with mean grain diameter ∼400 Å using dc magnetron sputtering of a Si target in an Ar plasma. We analyze the nucleation process and crystallite size as a function of film thickness using in situ, real time spectroscopic ellipsometry. For direct deposition on glass substrates at 470 °C, the initial ∼0.3 μm is amorphous silicon, then crystalline nuclei appear, and the growth becomes fully polycrystalline by ∼0.6 μm. To promote nucleation, we deposit a 100 Å layer of μc-Si:H (hydrogenated polycrystalline silicon with a mean grain diameter of ∼60 Å) by sputtering in an Ar plus H2 atmosphere at 210 °C. Returning to an Ar-only plasma at 470 °C, px-Si grows on this seeded substrate with no detectable amorphous interfacial layer. Since magnetron sputtering is a large-area, high throughput technique, this two-step process appears technologically attractive.