Exam2Fall2004Solution

Exam2Fall2004Solution - ECE 6450 Introduction to...

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Unformatted text preview: ECE 6450 Introduction to Microelectronics Technology Exam 2 October 14, 2004 Dr. W. Alan Doolittle go a 5 Print your name clearly: Instructions: Read all the problems carefully and thoroughly before you begin working. You are allowed to use 1 new sheet of notes (2 pages front and back), your sheet from previous exams as well as a calculator. There are 100 total points in this exam. Observe the point value of each problem and allocate your time accordingly. SHOW ALL WORK AND CIRCLE YOUR FINAL ANSWER WITH THE PROPER UNITS INDICATED. Write legibly. If I can not read it, it will be considered to be a wrong answer. Do all work on the paper provided. Turn in all scratch paper, even if it did not lead to an answer. Report any and all ethics violations to the instructor. Good luck! Sign your name on ONE of the two following cases: I did not observe any ethical Violations dunng this exam: —~_—._——a__——~_ I observed an ethical violation during this exam: Problem 1. (20 points total): TruefFalse and Multiple Choice (circle the answer or answers that are correct): a.) (3 points) The most damage in an Ion Implantation process results from nuclear collisions ) .. is more dominant at high implant energy 3. occurs at the surface occurs near the projected range b.) (3 points) If you have a 10 liter/sec pump connected to a tube with a conductance of 10 literx’ second, the effective pumping speed is 1.) 20 litersfsec. 2. 10 litersfsec. 5 liters/sec. 4.) none of the above. (1 points each) c.) Radiant P wer loss dominates over conduction and convection at high temperatures @ or False (circle the correct answer) d.) A rapid thermal diffilsion c result in more rapid diffusion than a furnace at the same tempera I due to a reducglalctivation energy for diffiision. Tru r False (circle the correct answer) e.) Damascene processing involves polishing oxides and metals to achieve a “globally planar” surface necessary for high resolution lithography. or False (circle the correct answer) f.) Solvents act as “thinners” to make the photoresist a liquid. False (circle the correct answer) -_ 7 ‘i- g.) Plasmas posses fiMed central region called a glow discharge region. True 0 (Else; crrcle the correct answer) h.) The conductance of a tube decreases with decreasing pressure. r False (circle the correct answer) i.) Anisotropy can be nhanced by increasing pressure. True or Fals (circle the correct answer) j.) Anisotropy can be increased by increasing the DC bias between the glow discharge region and the wafer. (fir False (circle the correct answer) k.) Thermal equilibr' always hold true for an RTP process. True 0%??? (circle the correct answer) 1.) For a wafer in an RTP system, a yellow glow (it ~590 run) from a wafer indicates a hotter temperature tlfiuaured glow (k~620 run) from the same type of wafer. -\[email protected] False (circle the correct answer) m.) Ion pumps armrfl‘fgggpod rough vacuum pumps. True 0 -¢b}z‘(circle the correct answer) n.) An Reactive Ion Etching system is a plasma etching system operated at lower pressure and higher bi . . a chieve high anisotmpy. @o False (circle the correct answer) 0.) A long mean free path results from a high pressure and is very useful to achieve undercut features with a large etch bias. True (circle the correct answer) p.) Whew, I a SW5 I made it through all those trueffalse questions! @0319 (circle the correct answer) \( I r!” 859%?!" 619 0L5??? Problem 2. (30 points total): 1E+19 : 1E+13 é 1E+17 1E+16 I i 5E+15 cm'3 Concentration 1E+14 5 1E+13 ; 1E+12 - - I ; i l - 0 500 1000 1500 2000 2500 3000 3500 Depth (A) As an engineer for National Semiconductor, you are asked to develop a pup Bipolar Junction Transistor (BJT) profile as shown above. The p-type bulk wafer concentration is 5x1015 cm'3 . The implanter your company uses has a beam current of 2 A. The n~type base implant is performed first so the peak concentration is Ie19 cm'3 and 400 angstroms (A) as noted in the figure. The emitter implant is then performed so the peak concentration is 1e17 cm"3 and 645 angstroms (A) as noted in the figure. Given the following relationships for the projected range and stragglc, what implant energy and implant time must you use for a 200 mm diameter wafer for each implant? n-typcdopant: RP:1[ A 26%5/70 AR :0 =0.75[ A o p-typedopant: Rp =§f A : ARP=UP=1[ A :2 $0 I; You may Show your work here em f‘i'tééf‘ I : J50 "l‘ éemmc/s é'exfefiwef; («2 2M ’4 ' Q gt? he V “I WHH 4“ ’ a“??? * E I S, T:‘\L€}7) [6-132’7flflcm Tie—6 fin T. fecww/f I @ (311/9 é DWfFe/ Problem 3. (50 points total): A common positive photoresist, Shipley MICROPOSH‘ 32313 more RESiSY Figure ‘2’. Contrast Curve Microposit S 1813, has a contrast curve as shown in the figure to the right (taken from actual datasheets). It is found that the thickness of the resist remaining after exposure and deveIOpment has a slope (as indicated by the linear regression fit line in the figure) of, «crzmuzeo PHOTORESJS? mamas-s asmmmo tum} {9%)Thickness Remaining : 4.3416 - 2.2681 Loglo (Dose) a) (10 Points) Find D0 b) (10 Points) Find D100 . , 0.0 0.2 (3.33 0.6 0.8 1.0 L2 fxi 2.6 LS 2.0 c) (15 Points) It is found that for a 1 pm thick LOG Wmmflmmmmm resist, a pattern is not able to be transferred using an exposure tool with a MTF of 0.4. Explain Why [in I sentence! and support your answer with numerical calculations. d) (15 Points) If the resist from part (c) has an absorption coefficient, on = 1.07 um'l what new thickness of resist is required to transfer image using the exposure tool with a MTF of 0.4? p.0fmq§;££’ OH 0:09 W—Fhicf—lneéfi : O Fr ejccépd) 4R9. marmafific} fluid/(“£55 1 I (“0 J OH' [195 x Far {5* 93%:6/ 395:} f—‘—_—--— m ) ( a : {82.07 m Mam-‘7 p“, z 10 b) O (Q- a,3az6J/.g.nési) —~/ 2.1 a) 00 z ‘0 Z ‘; t [734sz {Oé'ag“" h yfnfég tom“: :7“ n0 graCe/ PAY—F‘- aq< CWT! *0 6 j You may Show your work here I I 0’0 Y: ELM : [meme _ M 3’3 “£0,697 Jam—E) ({Am J}? 1' fl + 9:07 3, P3“: “0.6;27 F ayatwerh $0 +f‘an52é‘f/ we mee/ C‘JMTF z. MTF V gm Yb! 4 (9H 10”“ W 30W-) 4 $4 +[0*‘~‘)M (0,6){OWL [‘1‘ VV 4. @§€?€ Y > 1 7 7 i I V: 2.7.7 4 F“! ER 5 Goamflaém 7 7—K dig??? “‘L 'fi'flzf ...
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Exam2Fall2004Solution - ECE 6450 Introduction to...

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