Slide 1

9.2 GIA CNG VI C MEMS FABRICATION:

MEMS l cc h thng vi c in c kch thc cc chi tit nm trong thang o Micromet. Trong phn ny chng ta s kho st cc phng php ch to cc b phn ca MEMS nh bnh rng, dy xch, u d, thanh chn ang c s dng hin nay, gm 3 loi chnh: gia cng khi, gia cng b mt, LIGA. Ngoi ra cn c gia cng s dng tia LASER

9.2.1 GIA CNG VI C KHI - Bulk Micromachining: y l phng php lu i nht trong k thut gia cng vi c. L cch to ra trn phin vt liu cc l su, cc rnh, cc ch lm dng cc phng php ha, l n mn (tm thc). Phng php ny ly tng t hin tng n mn ni trong t nhin to thnh hang ng v k thut ch to nh ca ngi xa.

C 2 phng php c bn:n mn t - Chemical Wet Etching : y l phng php ph bin nht khi tin hnh gia cng vi c khi. Trong phng php ny cng chia lm 2 loi l khc ng hng v khc d hng isotropy & anisotropy. n mn kh: n mn bng cch cho kh hoc hi ha cht tc dng, thng l nhit cao.

Di y l m t quy trnh n mn t:1.Ngi ta to mt lp mt n trn tm nn ging nh khun cho chi tit cn tao.2. Dung dung dich n mon bo i phn khng c lp mt na bao v. 3. Loai bo phn mt na ta c phn chi tit nh mong mun. 9.2.1 GIA CNG VI C KHI - Bulk Micromachining: 9.2.1 GIA CNG VI C KHI - Bulk Micromachining: Trong ky thut n mon t s thanh cng c quyt inh bi tc n mon cua hn hp n mon i vi 2 loai vt liu lam nn va mt na. (selective) Trong hinh 1, mau vang la lp se bi n mon. Mau xanh la lp c gi lai.1: la chon khng tt mc du n mon phn trn nhng cung n mon phn vt liu nn xanh bn di.2. La chon tt khng lam tn hai n vt kiu nn.Trong hinh 2,mau o: lp mt na, mau vang: lp cn c n mon.1: qua trinh n mon ng hng hoan hao tao ra vach bn cong.2: qua trinh n mon di hng tao ra vach bn thng.

Hinh 2

Hinh 1 9.2.1 GIA CNG VI C KHI - Bulk Micromachining:

Trong phng php n mn ng hng, theo l thuyt qu trnh khc xy ra vi tc bng nhau mi hng. Nhng thc nghim cho thy qu trnh khc mt bn din ra chm hn khi khng c khuy. Do khi tin hnh khc ng hng thng tin hnh khuy mnh.

B n mon s dung cho tm wafer 4-inch cua vin cng ngh LAAS - Toulouse Phap. 9.2.1 GIA CNG VI C KHI - Bulk Micromachining: Phng php n mn d hng c s dng ph bin hn trong phng php n mn t. Trong phng php ny ngi ta iu chnh tc n mn ngm tm nn trong hn hp ha cht theo nhng hng khc nhau. Mi qu trnh khc u yu cu s dng vt liu lm khun gn vi vt liu nn. Trong phng php n mn t ng hng v d hng u yu cu mt n cho tm nn chun xc. Silicon Nitride c tc n mn chm hn so vi Silicon Oxide nn thng c s dng trong phng php n mn t ng hng cung nh di hng. Tuy nhin trong phng phap n mon di hng, SiO2 cung thng c s dung nhng cn phai kim tra day cua lp mt na khi s dung KOH lam cht n mon do khi o tc n mon cua oxit co th tng cao. Cac cht can quang khng c s dung trong bt c loai n mon di hng nao. Nhiu kim loai bao gm TA, Au, Cr, Ag, Cu chiu n mon tt vi dung mi n mon EDP va Al i vi TMAH trong mt s iu kin nht inh. 9.2.1 GIA CNG VI C KHI - Bulk Micromachining:

Hnh bn l cc dng chi tit kiu kim t thp ngc v h hnh thang c tao ra bng phng php n mn d hng. Cn ch l hnh dng ca khun nh hng quyt nh n s n mn chm hn ca mt v tc n mn ca n chm hn nhng mt khc khong 1000 ln. Cn chu y rng tc n mon, ti k tc n mon (100/111) va la chon vt liu phu thuc chu yu bi nhit va thanh phn hn hp cht hoa hoc n mon.

Hnh bn l hnh nh chp c t knh hin vi in t qut SEMS th hin b mt ca tm nn silicon sau khi c x l bng phng php n mn t d ng7 9.2.1 GIA CNG VI C KHI - Bulk Micromachining: Thng thng khi gia cng vi c khi yu cu tao nhng mang mong silicon hoc kim soat su n mon. Vi bt c qua trinh x ly hoa hoc nao se co s khac nhau khi gia cng nhng tm nn khac nhau. Thi gian n mon quyt inh ti su cn n mon cung rt kho iu khin. Do o at c cht lng cao trong phng phap n mon di hng, linh vc ch tao MEMS a phat trin mt giai phap goi la dng n mon (etch stops). Etch Stops a iu khin c qua trinh n mon va tao c s ng nht v su n mon trn wafer. Co 2 loai etch stop c ban c s dung:+ Dopant etch stops: s dung cht ban dn pha tap nguyn t nng Boron lam lp chn n mon do co tc n mon rt chm.+ electrochemical etch stops: la phng phap thng c s dung nht hin nay. S dung in cc ban dn loai n tao lp tip xuc p-n ngn chn s n mon. 9.2.2 GIA CNG VI C TRN B MT Surface Micromachining:Gia cng vi c b mt cung la mt phng phap rt ph bin trong qua trinh san xut cac thit bi MEMS. Phng php ny thc hin bng cch ph mt lp mng mng ln b mt ca tm nn to ra cu trc cho chi tit ca MEMS. N c dng ch to cc chi tit ca MEMS nh bnh rng, dy ai ca bnh rng, cc u d ...

Microgears: hnh chp ca phng th nghim quc gia Courtesy of SandiaHnh bn l nh chp qua knh hin vi in t qut SEM ca mt bnh rng. N c kch thc rt mng xp x 2-3 micromet v kch thc b mt hng trm micromet. Kch thc 1 rng ca n nh hn ng knh ca 1 hng cu ng knh khong 8 n 10 micromet. 9.2.2 GIA CNG VI C TRN B MT Surface Micromachining: Gia cng vi c b mt to cc cu trc v chi tit bng phng php gi l Deposition photolithography NH. y cng l phng php c s dng trong ch to chip my tnh CMOS.

Lp cu trc, lp hy sinh c ph ln, lm khun v n mn trn tm nn. Lp hy sinh c ph gia lp nn v lp cu trc to ra phn khng gian trng cho chi tit v khi qu trnh kt thc, lp hy sinh c loi b i.Mt phn ca chi tit vi c c to t lp mng ph mng.Mi cu trc cn 1 lp hy sinh. 9.2.2 GIA CNG VI C TRN B MT Surface Micromachining: Qu trnh ch to 1 u d:Mt lp hy sinh c ph ln tm nn, sau 1 lp cn quang c ph ln lm khun cho chi tit, s dng k thut photolithography. Sau cho n mn lp hy sinh v loi b lp cn quang, ta c lp hy sinh hon chnh.Sau , lp cu trc li c ph ln trn phn khun bng lp hy sinh va to v lp li qu trnh lm khun cn quang, n mn c c phn chi tit.Cui cng l loi b lp hy sinh ban u to ra chi tit u d hon chnh nh hnh bn

9.2.2 GIA CNG VI C TRN B MT Surface Micromachining:Lp hy sinh c s dng khi xy dng nhng chi tit phc tp nh cc b phn chuyn ng.S dng nhiu lp hy sinh khc nhau trong qu trnh ch to.Tt c cc lp hy sinh cn c loi b khi qu trnh ch to kt thc.Phng php s dng lp hy sinh c ly tng t vic xy dng cng Keystone. u tin ngi ta to ra khung bng g v t cc phin ln khung g , sau cng t vin Keystone ln v g b khung g ra nhng cc vin khng m to thnh hnh cng nh hnh bn. y, khung g ng vai tr nh lp hy sinh c s dng trong qu trnh xy dng v b i khi hon tt.

9.2.2 GIA CNG VI C TRN B MT Surface Micromachining: Lp u tin c th l lp cch in hay lp hy sinh, thng lm bng SiO2 c ngng t trn b mt tm nn bng phng php kch thch nhit. dy ca lp Oxit c th c iu khin bi mc nhit v m. nhng lp tip theo cng l nhng mng mng bng silicon nitride. Nhng lp ny c ph bng phng php ha l ph t pha hi - CVD. Kim loi v hp kim c ph ln bng phng php Spider in hay Evaporation.

Qu trnh kch thch nhit

ng ngng t 9.2.2 GIA CNG VI C TRN B MT Surface Micromachining:

u tin l qu trnh to khun s dng phng php quang khc. Ph ln wafer 1 lp cn quang S dng tia cc tm chiu x ln tm Wafer ta c mt n cho lp ph u tin. S dng phng php n mn loi b phn lp ph khng c mt n bo v. Loi b lp cn quang i, ta c khun. Qu trnh ny c lp li cho cc lp tip theo to thnh chi tit cn ch to.

Micro Actuator 9.2.2 GIA CNG VI C TRN B MT Surface Micromachining:

Comb Driver

Chain and GearPhng php ny c dng ch to ra nhiu chi tit s dng cho thng mi nh cc b phn ca my tnh, Iphone, xe hi, cc cm bin, b truyn ng siu nh, th RFID ... 9.2.3 LIGA Lithographie Galvanofoforunning un Abformung:

LIGA l k thut c pht trin c vo u nhng nm 80. nh tn gi ca n, k thut ny da trn 3 k thut c bn l khc hnh (Lithography), m in (electroforming) v lm khun (molding). y l k thut cho php to ra h vi c 3 chiu ch khng phi 2 chiu nh cc cch khc hnh hnh thng. n c th to ra nhng chi tit m nhng k thut khc trong khi hay khc b mt khng th d dng thc hin c vi t l hnh dng cao hn hn. Hnh bn l nh ca mt cu trc a gc v mt bnh rng vi t l lch thc rt cao c th c to ra s dng k thut LIGA.

9.2.5 LIGA Lithographie Galvanofoforunning un Abformung:

HARMST- High Aspect Ratio Microstructure Technology: cho php to ra nhng chi tit c cao vi milimet trong khi b rng ch vi micromet.c dng ch to cc chi tit, khun hoc du khc. Cho php sn xut hng lot cc chi tit kch thc micro bng nhiu loi vt liu khc nhau: polyme, kim loi hay hp kim.Cu trc to ra c chiu r rng v b mt tt.Bn cnh l hnh nh bnh rng ca 1 ng c in - hnh chp ca phng th nghim quc gia Courtesy of Sandia 9.2.5 LIGA Lithographie Galvanofoforunning un Abformung:

Cc giai on ca k thut LIGA kh ging vi 2 k thut surface v bulk:

DepositExposeDevelopElectroformPlanarizeStripRelease

9.2.5 LIGA Lithographie Galvanofoforunning un Abformung: Vt liu nhy sng: PMMA (polymethyl methacrylacte) hay Pleaxiglass Lp mt n c lm bng ng hoc vng (vt liu khng cho tia x truyn qua) t trn tm vt liu cho tia x truyn qua (Beryllium). Ngun sng thng s dng tia X (ly t my gia tc). Deposit: ph 1 lp vt liu nhy vi tia X nh PMMA ln b mt tm bn dn. Expose: tip dng k thut quang khc to mt n khun ri dng tia X chiu ln. 9.2.5 LIGA Lithographie Galvanofoforunning un Abformung:

Develop: loi b i phn vt liu b tia X chiu vo ta c khun ca chi tit.Electroform: tin hnh m in ln phn khun. 9.2.5 LIGA Lithographie Galvanofoforunning un Abformung: Planarize: tin hnh CMP mi phng phn chi tit li ln. Strip: loi b phn vt liu nhy tia X ban u (PMMA). Release: ly chi tit ra khi tm nn. Sau y l qu trnh ch to bnh rng bng phng php LIGA

9.2.4 HN - Wafer Bonding: Wafer Bonding l mt phng php ch to cc vi chi tit bng cch hn ni li 2 hay nhiu wafer vi nhau to ra tm wafer a lp hay cc chi tit vi c phc tp nh ng dn, b ngm. C 3 loi c bn bao gm: hn trc tip hay hn lin kt - Fusion Bonding; hn im - Anodic Bonding v hn s dng lp trung gian. D l phng php no cng yu cu tm wafer cn c lm phng, nhn v sch. Hn trc tip s dng ghp 2 tm wafer hay 1 tm wafer vi 1 tm khc b oxit ha vi nhau. Phng php ny c dng to nhng chi tit nh thng ng hay b cha c su vi micro vi mt mng silicon nitride bn trn. Mt phng php ph bin khc l hn im hn 1 tm wafer vi 1 tm wafer Pyrex 7740 s dng trng in t v gia nhit. phng php ny da trn nguyn l Pyrex 7740 giu ion Na+. Mt in p dng t trn tm wafer dn ion Na+ t tm Pyrex sang tm nn. Kt hp vi gia nhit, khi cc ion tip xc ti b mt tm wafer, to ra mt lng nhit va hn dnh 2 tm wafer li. Phng php ny c li th hn phng php trc tip yu cu tm wafer cn c lm phng, nhn v sch. Ngoi ra Pyrex 7740 c h s n nhit gn vi Silicon nn to ra lp silicon sau khi hn t b bin dng khi nhit cao. y l phng php c s dng ph bin trong k thut ng gi MEMS. Cn mt phng php khc s dng trong k thut ch to MEMS l hn vi lp trung gian bng vng ph trn b mt ca mt trong hai tm wafer. Do nhit cao, vng khuych tn vo silicon rt nhanh nn lm gim nhit cn hn. Ngoi ra cn s dng 1 s cht khc nh thy tinh, polymer lm lp trung gian. 9.2.5 GIA CNG BNG TIA LASER: C th dng tia laze to ra nhng chi tit theo kiu khot ln lt. phng php ny thng c s dng trong gia cng vi mch nhng t c s dng trong gia cng cc chi tit MEMS do gia cng chm. Do , trong cng ngh MEMS, cch ny thng ch lm khun. Lazer c s dng l loi Eximer gia cng trn Polymers. 1.19 3.14 Cu hi trc nghim:1. Ti sao phi thc hin tin trnh khuy khi tin hnh phng php n mn t ng hng.a. Do tc n mn ca lp mt n chm hn so vi lp nn.b. Do mt phn b cc ht trong tm nn khng ng u.c. Do tc n mn ca hn hp n mn i vi mt bn chm hn so vi hng khc.d. ha tan hn hp cht n mn.2. Trong phng php gia cng vi c b mt, cn phi to bao nhiu lp hy sinh?a. 1b. 2c. 3d. Ty theo cu trc ca chi tit cn ch to.3. Trong k thut LIGA, c im no u th hn so vi phng php Surface v Bulk?C kh nng ch to chi tit c cu trc phc tp vi t l hnh dng cao.b. C chi ph sn xut r hn.c. Phng php tin hnh n gin.d. Tt c u sai.