SBIR Phase I: Novel Wafer Fabrication Technology for Semiconductor Sensors

这个小型企业创新研究的第一阶段项目是针对碲化镉锌（CdZnTe）单晶薄膜的开发，通过使用离子束层分离工艺从大块单晶中分离出来。分离的层将被转移并粘合到硅晶片上，作为碲化汞镉（HgCdTe）薄膜外延生长的衬底。HgCdTe薄膜是红外探测器的研究热点。离子束层分离工艺将允许从单个块状晶体中制造大量薄膜，从而为红外探测器材料提供经济的晶圆生产技术。高能（MeV）光离子将用于在大块晶体中产生埋藏的损坏层。高温快速热退火引起的热冲击可能产生侧向裂纹，使层分离。在第一阶段，将通过寻找层分离的条件和从晶体质量方面分析分离层来证明可行性。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、医疗和空间传感器。CdTe和（Cd,Zn）Te合金晶体的生长采用了各种技术，包括区域精炼、垂直梯度冷冻（VGF）、液体封装法（LEC）、水平和垂直Bridgman技术。由于产量变化，这些方法都没有产生足够的材料与质量需要今天的红外（IR）探测器的应用。该技术的优点是可以通过离子束切片的方法从单个块状晶体中生产出许多高质量的衬底，从而为生产可靠和可重复的高质量材料提供了一种经济的方法。此外，通过在更便宜的Si衬底上以地砖模式堆叠更小的薄片，可以实现用于HgCdTe生长的大面积CdZnTe衬底。与硅衬底的结合也将使红外探测器与电子器件集成在一个芯片上。

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.