Question

(20 pts.) Question 3 Al um film of silicon dioxide is to be etched with an etch rate of 800 nm/min. Process data show that the thickness may vary up to 3% and the etch rate may vary up to 5 %. (i) specify the time duration that verifies the etching process clears the oxide film from all the exposed areas of the wafer; (ii) For this time duration, calculate how much undercut will occur at the top and bottom of the oxide film, both maximum and minimum values (i.e. next to photoresist and next to the Si surface denoted by a and b in the figure below). Hint: time of etch thickness to be etched / etch rate photoresist Silicon dioxide Si

Answer 1

pafe no: objeitave is the teme duraton the -Answe - -find ayf etching proces and the undercut ipat vegifres fird me of etching (To fheVasiato0 given informaton Ву тhе e tme af etching 4Ren Consicered mot Can be Calcudated by time af etehing xio 800x i 3 tEne af etchiny S min

Page no undercut- To nd a Vaguaton 0f there be.cause Bu in he hickness anol 40xlo9 o.03 o m/min in tAe rate aud this Valiaton is Re t happen under cut SoLe reason -for an Cases in to t anol takaing are o here wohere the hicknecs. Case he enample of a Yate is &4o nM the O. 97um and Analysing afuch a eituaton he undercuf af 0.03 um and at tRe bottom top ould be the m/min rati of &40 wsrth a shich is t would etch of loso nm 0.9 ushich rmeau Phab is an undercu at tee bottom. Explanation andl Considening this all te with - explanatory Cases the asolutoon is Sele