专用集成电路作业.doc

Assignment 21. Give a descriptive definition for each of the following terms.(1) Starting substrate(2) Active region: The regions between these thick SiO2 layers(3) LOCOS process: LOCal Oxidation of Silicon(1) Field oxide layer: 重掺杂硅区上均生长一层厚的氧化层(2) Shallow Trench Isolation (STI): an integrated circuit feature which prevents electrical current leakage between adjacent semiconductor device components(3) Positive resist : a type of photoresist in which the portion of the photoresist that is exposed to light becomes soluble to the photoresist developernegative resist: a type of photoresist in which the portion of the photoresist that is exposed to light becomes insoluble to the photoresist developer(4) Sputtering: a process whereby atoms are ejected from a solid target material due to bombardment of the target by energetic particles(5) Reactive ion etching: an etching technology that High-energy ions from the plasma, generated under low pressure (vacuum) by an electromagnetic field, attack the wafer surface and react with it(6) Strong inversion layer: 半导体表面的少数载流子浓度等于体内的多数载流子浓度时, 半导体表面形成的一种表面势近似为不变的数值，耗尽层电荷及耗尽层厚度有极大值状态称为强反型态。(7) Threshold voltage of MOS transistor：the gate voltage where an inversion layer forms at the interface between the insulating layer (oxide) and the substrate (body) of the transistor2. P- type well in a 250nm technology has the doping concentration NA = 1015atoms cm-3. Find the limiting value of depletion-layer width wd and the total charge Qd contained in the depletion region. Use at 300K;3. Compute the NMOS and PMOS saturation currents ISATN and ISATP per micron of width for a 180nm technology. Assume a channel length of 200nm, , VTN = 0.5V, VTP = -0.5V, VDD =1.8V. Use NMOS:PMOS:4. As the value of the drain-source voltage is further increased, the assumption that the channel voltage is larger than the threshold all along the channel ceases to hold. This happens when VGS - V(x) VT. At that point, the induced charge is zero, and the conducting channel disappears or is pinched off. No channel exists in the vicinity of the drain region and the current ID remains constant (or saturates). Please explain why the current can keep constant instead of being zero while the conducting channel has already disappeared?Reference:1 James D. Plummer, et al., “Chapter 2 Modern CMOS Technology,” Silicon VLSI Technology: Fundamentals, Practice and Modeling, Prentice Hall, 2000. (Available at our course website)当增加到时，漏极附近的耗尽层即在上部合拢，这种状态称为预夹断。预夹断后，漏极电流。因为这时沟道仍然存在，沟道内的电场仍能使多数载流子