SBIR Phase I: Novel Wafer Fabrication Technology for Semiconductor Sensors

这个小企业创新研究第一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。 分离的层将被转移和键合到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。 在升高的温度下由快速热退火引起的热冲击可产生使层分离的横向裂纹。 在第一阶段，将通过找到层分离的条件并通过分析分离层的结晶质量来证明可行性。 该项目的商业应用是红外光电探测器和焦平面阵列，用于许多工业和科学传感器应用，包括环境监测，化学生物检测以及医疗和空间传感器。 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。 所提出的技术具有通过离子束切片从单个块体晶体生产许多优质衬底的优点，从而提供了生产可靠且可再现的优质材料的经济方式。 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。

This Small Business Innovation Research Phase I 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 onto 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 shock induced by rapid thermal annealing at elevated temperatures may generate lateral crack enabling the layer separation. In Phase I, the feasibility will be demonstrated by finding the conditions of layer separation and by analyzing the separated layer in terms of crystalline quality. The commercial application of this project is in IR photodetectors and focal plane arrays for many industrial and scientific sensor applications including environmental monitoring, chem-bio detection and medical and space sensors. 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 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.