SBIR Phase II: Novel Wafer Fabrication Technology for Semiconductor Sensors

这个小企业创新研究（SBIR）第二阶段项目是针对碲锌镉（CdZnTe）单晶薄膜的发展，通过使用离子束层分离工艺从大块单晶。分离出的层将被转移并结合到硅（Si）晶片上，用作碲镉汞（HgCdTe）薄膜外延生长的衬底。HgCdTe薄膜是红外探测器的重要材料。离子束层分离工艺将允许从单个块状晶体制造大量的膜，从而为红外探测器材料提供经济的晶片生产技术。高能（MeV）轻离子将被用来在大块晶体中产生掩埋损伤层。在升高的温度下的热退火可能产生横向裂纹，从而使得层分离。第一阶段已表明这一办法的可行性。第二阶段的研究目标是优化晶圆级分离的工艺参数，而不打破和发展的过程中转移到硅晶片上的分离膜。由此制造的晶片将用于HgCdTe的外延生长和红外探测器的制造。CdTe和（Cd，Zn）Te合金晶体的生长方法有区域精炼法、垂直梯度凝固法（VGF）、液封直拉法（LEC）、水平布里奇曼法和垂直布里奇曼法。由于产量不一，这些方法都没有产生足够的材料，具有当今红外（IR）检测器应用所需的质量。提出的方法已被开发，以克服这些limitation.Commercialized，所提出的技术具有生产许多高品质的基板从一个单一的大块晶体的离子束切片的优势，从而提供了一个经济的方式生产可靠的和可再生的质量材料。此外，用于生长HgCdTe的大面积CdZnTe衬底将可能通过在较便宜的Si衬底上以地砖图案堆叠较小的切片来实现。与硅衬底的结合也将允许在单个芯片上集成红外探测器和电子器件。红外光电探测器和焦平面阵列在许多工业和科学应用中具有重要意义，包括环境监测、化学生物检测、医学和空间传感器。

This Small Business Innovation Research (SBIR) Phase II project is directed toward the development of cadmium zinc telluride (CdZnTe) single crystal films by using an ion beam layer separation process from bulk single crystals. The separated layers will be transferred and bonded on to silicon (Si) wafers for applications as substrates for epitaxial growth of mercury cadmium telluride (HgCdTe) films. HgCdTe films are of interest in infrared detectors. The ion beam layer separation process will allow the fabrication of a large number of films from a single bulk crystal, thus providing an economical wafer production technology for infrared detector materials. High-energy (MeV) light ions will be used to produce a buried damaged layer in the bulk crystal. Thermal annealing at elevated temperatures may generate lateral crack enabling the layer separation. Phase I has shown the feasibility of this approach. Phase II research objectives are to optimize the process parameters for wafer-scale separation without breaking and develop the process to transfer the separated films on to Si wafers. The wafers thus fabricated will be used for epitaxial growth of HgCdTe and fabrication of IR detectors. CdTe and (Cd,Zn)Te alloy crystals have been grown by various techniques including zone refining, vertical gradient freeze (VGF), liquid encapsulated Czochralski (LEC) methods, horizontal and vertical Bridgman techniques. Due to variable yields, none of these methods have produced enough material with the quality needed for today's infrared (IR) detector applications. The proposed method has been developed to overcome these limitations.Commercially, the proposed technique has the advantage of producing many good quality substrates from a single bulk crystal by ion beam slicing, thus providing an economic way of producing reliable and reproducible quality material. Also, large area CdZnTe substrate for the growth of HgCdTe will be possible by stacking smaller slices in a floor tile pattern on cheaper Si substrates. Bonding with Si substrate will also allow the integration of IR detectors with electronics on a single chip. IR photodetectors and focal plane arrays are of interest in many industrial and scientific applications including environmental monitoring, chem-bio detection, medical and space sensors.