Preparation And Micro-structure Analysis Of Porous Silicon

Since the 1990's, Micro-Electronic-Mechanical-Systems (MEMS) has been rapidly developed. Now, MEMS has become one of the most popular spots in the most promising field of information. It can be considered that MEMS technology will bring about a great or even trigger impact on a new industrial revolution. As one of the emerging materials of MEMS as insulation and sacrificial Layer, porous silicon which has good mechanical and thermal properties is of the concern by people gradually.However, the preparation and micro-structure with the parameters of the relationship between the parameters of porous silicon has become a very important issue which should be explored and resolved.In this paper, preparation and micro-structure analysis of the basic nature parameters for porous silicon is done. The research of porous silicon used as the application insulation in MEMS is done. The mainly work completed as:1. By dual chamber electro-chemical anodizing way , porous silicon films are prepared in the p-type silicon-chip<100>. In the experiment, SiO₂ and Cr were used as a masking layer for porous silicon. By changing the different parameters of the preparation, porous silicon films with different micro-structure are made. Through the observation of raman laser, the Raman spectra film location of porous silicon is observated.2. Through weighing, the porosity of porous silicon films are calculated. Aperture and the section of the porous silicon are observed by using the field emission scanning electron microscopy (SEM) and atomic force scanning electron microscope (AFM). Find out that the aperture size range from 15 to 35 nm.Used the nanoprobe instrument measure the thickness of porous Silicon, find that them range in 40 -140μrn.3. According to the microscopic observation plans, the impact of HF concentration, corrosion of time and corrosion current density on the thickness, the pore size and porosity of porous silicon is analysed. As a conclution: with the HF concentration increasing, the diameter and reduce the porosity of porous silicon decreased. With the corrosion current density increasing, the aperture porosity and thickness of porous silicon increased.With the time of corrosion increasing, the thickness of porous silicon came firstly rise then tends to smooth. When kept in vacuum, the research of porous silicon film's internal crack which was caculated.4. The the thermal conductivity of porous silicon thin film with different parameters are simulated by software FLUENT. Also, the thermal conductivity comparisions amony-different materials are done.