tailieunhanh - The MEMS Handbook (1st Ed) - M. Gad el Hak Part 7

Tham khảo tài liệu 'the mems handbook (1st ed) - m. gad el hak part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Decorating armor. From Harris T. W. Chemical Milling Clarendon Press Oxford 1976. With permission. Isotropic etching has been used in silicon semiconductor processing since its beginning in the early 1950s. Representative work from that period is the impressive series of papers by Robbins and Schwartz 1959 1960 and Schwartz and Robbins 1961 1976 on chemical isotropic etching and Uhlir s paper on electrochemical isotropic etching Uhlir 1956 . The usual chemical isotropic etchant used for silicon was HF in combination with HNO3 with or without acetic acid or water as diluent Robbins and Schwartz 1959 1960 Schwartz and Robbins 1961 1976 . The early work on isotropic etching in an electrochemical cell . electropolishing was carried out mostly in nonaqueous solutions avoiding black or red deposits that formed on the silicon surface in aqueous solutions Hallas 1971 . Turner showed that if a critical current density is exceeded silicon can be electropolished in aqueous HF solutions without the formation of any deposits Turner 1958 . In the mid-1960s the Bell Telephone Laboratories started the work on anisotropic Si etching in mixtures of at first KOH water and alcohol and later in KOH and water. This need for high aspect ratio cuts in silicon arose for making dielectrically isolated structures in integrated circuits such as for beam leads. Chemical and electrochemical anisotropic etching methods were pursued Stoller and Wolff 1966 Stoller 1970 Forster and Singleton 1966 Kenney 1967 Lepselter 1966 1967 Waggener 1970 Kragness and Waggener 1973 Waggener et al. 1967a 1967b Bean and Runyan 1977 . In the mid-1970s a new surge of activity in anisotropic etching was associated with the work on V-groove and U-groove transistors Rodgers et al. 1976 1977 Ammar and Rodgers 1980 . The first use of Si as a micromechanical element can be traced back to a discovery and an idea from the mid-1950s and early 1960s respectively. The discovery was the large piezoresistance in Si and Ge by