MEMS复习攻略

1、特此感谢：卓著、王明斗、兰天翔、唐小涛、周孝吉对本攻略的贡献。董建鹏 2015/1/14简述：1、只是包含MEMS中需要自己总结的内容比较多的知识（除ppt6-7一些琐碎的概念，其他章节部分需要总结的基本已涵盖）。2、时间仓促，做得可能不是很完善请谅解。3、英语水平有限，单词语法错误自己改正4、若有错误或没有涉及到的还望大家补充改正（英语）。5、.祝各位取得好成绩！1. difference:MEMS is a process technology used to create tiny integrated devices or systems that combine mechanical

2、 and electrical components. NEMS is a great development of MEMS. Content: (1) Scale size (2) Material (3) Process technologyMEMSNEMSBasicmaterialSiliconCarbonMEMS NEMS Scale Size 1.Component:1um100um2.Device :0.1mm1mm 1nm100nm (4) Principle (5) Feature (6) Application (自己酌情删减)MEMSNEMSProcess technol

3、ogy1.Miniaturized machine tool2.Wet etching3.Dryetching(RIE AND DRIE )4.Electro discharge machining(EDM):5.LIGA(X-ray)1.AFM/STM induced oxidation method2.Electron-beam lithography(>20nm)3.Atom or molecule assembly techniqueMEMSNEMSprinciple1.High power density (Micro-scale effect)2.Large surface

4、area to volume ratio makes surface effects dominant over volume effect. 3.Large thermal conductivity 1.Nano-scale effect 2.Quantum effect3.Interfacial effect MEMS NEMS feature1.Two dimension or quasi- Three dimension Structure 2.High precision 2-D control3.Integration mass production4.low power and

5、less inertia 1.Ultra-small dimension2.Ultra-high frequency Response(more than 100MHZ) 3.Ultro-low power MEMSNEMSApplication1.Targeted drug delivery system2.Miniature robot system 1.Biological motor2.Ultra-high frequency RF resonator 2. 扰动执行器的组成及其运动过程：Scratch Drive Actuator (SDA)（1）component：plate bu

6、shing insulator（绝缘体） substrate (2) processa） Applied voltage bends SDA downwardb) When released, SDA returns to original shapec) Reapplying voltage causes SDA to move a distance dx3. Pattern transfer（1）thin film on substrate Silicon dioxide is deposited as structural or sacrificial on the substrate

7、by PVD or CVD. （2）photoresist coatedResist typically 1 um. Spin resist always be used to achieve a uniform thin surface.（3）pattern photoresistWafer is transferred to an exposure system where it is placed between a photomask and exposed with an ultra violet radiation.（4）resist developmentThe photores

8、ist coated wafer undergoes development stage where selective dissolving of photoresist takes place.（5）etch of the thin filmThe silicon dioxide exposed on the air is etched by dry etching or wet etching. The silicon covered by the remained photoresist is saved.（6）resist stripplingRemove the photoresi

9、st.4. AlignmentThere are two kinds of Alignment(1) Alignment between multiple layers(2) Alignment between two sides of a wafer(1)Alignment for multiple layersFirst, we need alignment marks on both wafer and maskSecond, capture the image of the alignment mark of the mask in the microscopeThird, move

10、in the wafer and then see the alignment mask of the waferFourth, adjust the position of the wafer, so that the alignment marks of the wafer and mask match.This is how we do alignment for one-side alignment. Alignment for multiple layers means that you repeat this process every time when you add anot

11、her layer.(2) Alignment between two sidesThe situation is that we try to align the pattern on two side of a wafer. Lets say there are A side and B side. A side is already fabricated.First, move in the mask till we can see the alignment mark of the mask, and then restore this image in computer.Second

12、, move in the wafer with the B side towards the microscope. Third, adjust the position of the wafer, till the image of the alignment mark of the wafer match the alignment mark of the mask (the image in computer).之前我有和一些同学说对准分为三种，即单面，双面和多层，经过讨论改为两种，只有双面和多层。多层可看作单面的重复，故将二者合为一种。5. LIGA processLIGA原理：Pa

13、rt1. Resist moulding and 1st electroforming:Step1: Irradiation and DevelopingImplementing irradiation based on the resist and subsequently achieving the resist structure.以光刻胶（Resist）为基底，进行光刻。此例中掩膜板(Mask membrane)是蜂窝煤状，故形成的光刻胶结构（Resist structure）亦是如此。Step 2: 1st electroforming and Removal of the resi

14、st structureElectroforming based on the resist structure, then stripping the mould and therefore obtain the final product.在光刻胶结构(Resisit structure)上进行电镀，然后进行脱模处理。脱模后的金属结构就是需要的最终产品（Final Product）。Part2. Plastic moulding and 2nd electroforming:Step1: Mould filling and Mould removalFilling the final pr

15、oduct with plastic, then separating them for the plastic mould.向最终产品中填注塑料，反求出塑料模型。分离并得到塑料模型。Step2: 2nd electroforming and Removal of the plastic mouldElectroforming based on the plastic mould, then stripping the mould and therefore obtain the final product.在塑料模型上进行电镀，然后进行脱模处理，脱模后的金属结构就是需要的最终产品（Final

16、 Product）。Repeat Part2.Step2 and you will get more products.然后无限重复Part2.Step2,就可以获得更多的最终产品。个人理解:很难将电镀层（Mould insert）与光刻胶结构完整分离，所以在第一次脱模的时候，我们用溶液将光刻胶结构融化；再加上光刻胶本身容易磨损，导致光刻胶结构只能是一次性的模型，不能重复使用。而在第二次脱模的时候，塑料模型是可以完整分离的，所以塑料模型是可以重复使用的模型，能够投入生产中使用。总而言之，LIGA技术的目的就是做出一个传统方法不易加工的（如例中的深孔），可重复使用的塑料模型，从而帮助我们进行生产

17、。考试直接抄这些就可以了：Part1. Resist moulding and 1st electroforming:Step1: Irradiation and DevelopingImplementing irradiation based on the resist and subsequently achieving the resist structure.Step 2: 1st electroforming and Removal of the resist structureElectroforming based on the resist structure, then st

18、ripping the mould and therefore obtain the final product.Part2. Plastic moulding and 2nd electroforming:Step1: Mould filling and Mould removalFilling the final product with plastic, then separating them for the plastic mould.Step2: 2nd electroforming and Removal of the plastic mouldElectroforming ba

19、sed on the plastic mould, then stripping the mould and therefore obtain the final product.Repeat Part2.Step2 and you will get more products.6. 加速度传感器（不考计算）（1） 种类 （2）机理 （3）构造过程（用图描述）(1) MEMS intertia sensors includes micro accelerometer and micro gyroscope. Micro accelerometer includes capacitive mic

20、ro accelerometer and piezoresistive micro accelerometer.(2) principle解释：看ppt上的内容有点一头雾水，大家可以参考下下面的中文（得到惯性质量块的位移由此即可测得加速度，不过自我感觉还是没有解释清楚ppt的内容，谁搞懂了可以上传修正一下） （2） fabrication：piezoresistive micro accelerometer(自己写的,可能很不完善请谅解，谁有这块内容望补充)(a) deposit silicon nitride at both sides of the silicon wafer.(b) De

21、posit 1st sacrificial layer polysilicon at the front side of silicon wafer and pattern the 1st payer(c) Deposit 2st silicon nitride at front side of silicon wafer and 1st silicon nitride at the back side of silicon wafer(d) Pattern 1st layer at the front side of silicon wafer and layer poly0 at the back side of the silicon wafer(e) Deposit and pattern metal layer (nickel)(f) Anisotropic etching to get the groove.Capacitive micro accelerometer:7. 陀螺仪（老师画重点时没