Measurement method of in-depth profiles of recombination lifetime in epitaxial Si layer with test element pattern

为获得高质量的硅光探测器，研究了采用低阻衬底的高阻外延片。在界面引入了黄油层，它对外延层(外延层)的结晶质量有很大的影响。利用电导调制技术自动测量外延层的复合寿命。在外延层表面形成横向p^+-n^--n^+二极管测试结构以评估少子寿命。复合寿命的深度分布由横向的p^+-n^--n^+二极管和衬底与顶表面之间垂直的n^+-n^--n^+结构的电流-电压曲线得到。我们测量了在有和没有缓冲层的外延层中的寿命。此外，还测量了有缓冲层和无缓冲层的光电二极管的光响应。复合寿命的分布取决于外延层的厚度，而不取决于缓冲层的厚度。外延层中的复合寿命变得非常均匀和长，甚至在界面区也是如此，通过测量寿命深度分布证实了这一点。然后在上述优质外延片上制作了硅光电二极管，并对其光电特性进行了评价。热氧化过程中氧原子从衬底进入外延层的观察。外延层中的氧从衬底扩散。

For the high quality Si Photodetector, the high resistivity epitaxial wafer using the low resistivity substrate were studied. The butter layer was introduced in the interface, and it was very effective on the crystal quality of the epitaxial layer (epilayer). Recombination lifetime of a epilayer is automatically measured by using the conductivity modulation technique. A lateral p^+-n^--n^+ diode test structure on the surface of the epilayer is formed to evaluate the minority carrier lifetime. Depth profiles of the recombination lifetime are obtained from current-voltage curves of a lateral p^+-n^--n^+ diode and a vertical n^+-n^--n^+ structure between the substrate and the top surface. We measure the lifetime in epilayers with and without a buffer-layer. In addition, photo-response of photodiodes with and without the buffer-layer is measured. Profiles of the recombination lifetime depend on the thickness of the epilayer but not on the thickness of the buffer-layer. Recombination lifetime in the epilayer became very uniform and long even in the interface region which was confirmed by measuring the lifetime depth profiles. Then Si Photodiode was fabricated on the above high quality epitaxial wafer and its epitaxial wafer and its optoelectric characteristics was evaluated. The observation of oxygen atoms from the substrate into the epilayer during thermal oxidation. The oxygen in the epilayer was diffused from the substrate.