SBIR Phase I: Ultrathin SiC-on-Insulator (SiCOI) for ALE Growth of Low-Defect GaN

这个小型企业创新研究（SBIR）第一阶段项目探索使用低缺陷，高质量的碳化硅在SOI（绝缘体上硅）结构上作为晶格匹配衬底，用于通过原子层外延（ALE）生长GaN。最近的实验已经通过低能氧注入分离（SIMOX）工艺在SiO2上制备了厚度为140埃的单晶硅。 SiC薄膜将通过碳化SIMOX晶片的单晶硅顶层来制备。 碳化技术在Si上外延SiC中产生了最低的缺陷密度;然而，由于不同的晶格常数，在界面处存在应变层，这限制了这种材料用于器件应用的有用性。 薄的Si膜允许整个Si层快速转化为SiC，并导致SiC仅与SiO2接触，SiO2是无定形的并在碳化温度下软化。 在没有晶格失配的情况下，消除了应力源（类似于SIMOX），从而为形成高质量的SiC层铺平了道路。 SiC的生长在SIMOX结构上的初步工作表明，与那些生长在厚SIMOX或块状Si上的SiC相比，SiC的质量非常好。 第一阶段将在不同的材料和工艺条件下生产SiC薄膜，GaN将通过ALE在缺陷最低的材料上生长。 如果获得批准，第二阶段将包括工艺参数的优化和器件结构的制造。 制造大面积、廉价的Si基衬底以生长低缺陷的SiC和GaN薄膜是抗辐射、高温电子学的基础。 这些衬底对于将LED、激光器、探测器和各种其他器件集成到硅微电子芯片中至关重要。

This Small Business Innovation Research (SBIR) Phase I project explores the use of low-defect, high-quality silicon carbide on ultrathin silicon-on-insulator (SOI) structures as a lattice-matched substrate for growth of GaN by atomic layer epitaxy (ALE). Recent experiments have fabricated ultrathin Si on SiO2 as thin as 140 Angstroms by the low-energy Separation by IMplantation of OXygen (SIMOX) process. SiC thin films will be fabricated by carbonizing the ultrathin Si top layer of SIMOX wafers. The carbonization technique has produced the lowest defect density in epitaxial SiC on Si; however, due to different lattice constants, a strained layer exists at the interface which limits the usefulness of this material for device applications. Thin Si films allow rapid conversion of the entire Si layer to SiC and result in SiC in contact only with SiO2, which is amorphous and softens at the carbonization temperature. In the absence of a lattice mismatch, the source of stress is eliminated (similar to SIMOX), thus paving the way for formation of a high-quality SiC layer. Preliminary work on the growth of SiC on ultrathin SIMOX structures suggests very good quality SiC as compared to those grown on thick SIMOX or bulk Si. Phase I will produce SiC films under varying material and processing conditions, and GaN will be grown by ALE on the lowest-defect material. If approved, Phase II would include optimization of processing parameters, and fabrication of device structures. Fabrication of large-area, inexpensive, Si-based substrates for growth of low-defect SiC and GaN films are the basis for radiation-hard, high-temperature electronics. These substrates are essential for integration of LEDs, lasers, detectors, and a variety of other devices into silicon-microelectronic chips.