微機電系統(tǒng)ppt課件(更新版)
【正文】 electrons in their outermost shell than the host semiconductor. They provide one extra electron or one missing electron (a hole) pared to the host atoms. These excess electrons and holes are the carriers, which carry current in semiconductor devices. The key to building semiconductor devices and integrated circuits lies in the ability to control the local doping and hence the local electronic properties of a semiconductor crystal. 7) Semiconductor Devices Understanding of how the basic devices used ICs operate is useful, because it provides some understanding of the objectives we have for IC technology. The most monly used IC devices are: 1) PN Diodes 2) Bipolar Junction Transistors 3) MOS Transistors 2. Introduction to the Lithography Process 1) Positive and Negative Resist KOH、 Acetone、 TMAH HF ? Basic step of lithography: 1） The maximum resolution of a device: where λis the wave length of light used to make image transfer. . UV λ=500nm 2） Steps: substrate preparation→ thin film addition →cast PR →pre designed mask →expose in UV light →develop PR in developing solution →Etch the thin film covered with PR in a solution that will attack the thin film but not the PR →remove PR ?? ?2) Photoresist Spin Coating 3) CleanRooms, Wafer Cleaning A very clean environment is needed for micro fabrication to prevent dirt or other particles from contamination the micro devices. Air purification: humidity(45%), temperature(70176。 A、 B: consta
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