Polyimide structures for micro-electro-mechanical system (mems) - based applications.

Abstract

This Ph.D. thesis studies and experimentally examines applicability of thin polymer films as structural substitutes for crystaline Si in bimorph MEMS structures. The two shapes (bi - morph) and transient state between the ON - OFF resting positions, that such deformable MEMS structures assume, largely depend on thermo-mechanical characteristics of the structural materials, influencing response time, efficiency and delivered force and/or sensitivity. For the first time, thermal characteristics (e.g. Coefficent of Thermal Expansion (CTE)  and the Glass Transient Temperature Tg) of trully thin (2m – 10m) polyimide (PI) films have been examined and the relationship with respect to film thickness and film coating processing parameters (e.g. soft - baking and hard-baking temperature profiles) has been established. The correlations between the film thickness and respective CTEs - , as well as respective glass transition temperatures, Tgs have been experimentally established. Experimentally established thermo - mechanical characteristics of PI films were then used for software simulation, functionalisation and modelling of the next generation of bimorph microsensors and microactuators based on PI - metal and PI - PI architecture...

U okviru ove doktorske disertacije proučena je i eksperimentalno ispitana mogućnost primene tankih polimernih filmova kao zamene za silicijum kod bimorfnih MEMS struktura. Ponašanje deformabilnih bimorfnih MEMS struktura (oblik, položaj u mirovanju i u stanju pobude) veoma zavisi od termomehaničkih karakteristika samih strukturnih materijala, a koje samim tim imaju uticaja i na vreme odziva, efikasnost i primenjenu snagu i/ili osetljivost. Prvi put su u radu ispitivane toplotne karakteristike (koeficijent toplotnog širenja, , i temperatura prelaza u staklasto stanje, Tg) tankih poliimidnih filmova (2 m - 10 m) u zavisnosti od debljine filma i procesnih parametara (temperature umrežavanja, kao i temperaturnog profila koji je korišćen pri umrežavanju polimera). Na osnovu eksperimentalnih podataka izvedene su korelacije izmeĎu debljine filma i koeficijenta toplotnog širenja, , kao i temperature prelaza u staklasto stanje, Tg. Pomoću toplotnih karakteristika PI filmova izvršena je simulacija, funkcionalizacija i modelovanje nove generacije bimorfnih mikrosenzora i mikropokretača tipa metal - poliimid i poliimid - poliimid...