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应用一种新的两步氧化工艺在多孔硅样品上生长硅分子外延层,能获得大的硅-绝缘体(SOI)结构。第一步低温氧化,氧化底层的大孔硅,以避免多孔硅结构破裂,保障给多孔层氧化提供横向氧源通道。第二步,用较高的温度来氧化剩余多孔硅和硅分子束外延层的底下部分,该部分氧化所需的氧就是通过已氧化的多孔硅底层提供的。新的多孔硅结构是由具有小孔性的顶部多孔硅层和具有大孔性的第二层组成。前者适用于随后将进行的硅外延生长,后者不仅为SOI氧化提供氧通道,而且可以调节多孔硅氧化的体积膨胀。已成功地制造出325μm×2mm的SOI。在10V偏压下,SOI结构的击穿电压约为400V,而SOI层和衬底之间的漏电流密度低于3nA·cm~(-2)。在具有良好特性的SOI结构上已经制造出n沟金属-氧化物-硅场效应晶体管,这表明这种技术适用于超大规模集成电路。
A new two-step oxidation process is used to grow silicon molecular epitaxial layers on porous silicon samples to obtain large silicon-insulator (SOI) structures. The first step of low temperature oxidation, the oxidation of the underlying macroporous silicon, in order to prevent the porous silicon structure rupture, to protect the porous layer to provide horizontal oxygen channel oxidation. In the second step, the lower portion of the remaining porous Si and Si molecular beam epitaxy layer is oxidized at a higher temperature, and the oxygen required for the partial oxidation is supplied through the oxidized porous Si substrate. The new porous silicon structure is composed of a top porous silicon layer having a pinhole and a second layer having a macroporosity. The former is suitable for the subsequent epitaxial growth of silicon, which not only provides oxygen channels for SOI oxidation but also regulates the volume expansion of porous silicon oxidation. SOI of 325 μm × 2 mm has been successfully manufactured. The breakdown voltage of the SOI structure is about 400V at a bias voltage of 10V while the leakage current density between the SOI layer and the substrate is less than 3nA · cm -2. N-channel metal-oxide-silicon field-effect transistors have been fabricated on well-characterized SOI structures, demonstrating that this technique is suitable for very large scale integrated circuits.