Xu bdihig trong kiem tra cac linh kien

Hinh 1: Cdc Ung dung cua cdm bien dUa tren cdng nghe MEMS

Xu bdihig trong kiem tra cac linh kien

MEMS

(Phdn ddu)

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EMS hien dang dUgc coi la mdt trong nhQng edng nghe hUa hen nhat eua the ky XXI va ed tiem nang cich mang hoi cic sin phi'm cdng nghiep va tieu dung. LTnh vUe MEMS bao ham su ket hpp giQa cic cau true co cd kich thudc micro v i cic mach dien tQ tich hpp tren cung mdt chip.

Cum tU MEMS cung bao gdm c i phuong phip che tao die trUng, v i eau tnic mdi ciia thiet bj v i sin phi'm. MEMS la mdt cdng nghe ed khi ning eho phep sU phit trien cic sin phi'm thdmg minh, t i n g khi ning tinh toan eua cic yeu td vi dien tQ vdi cic vi cim bien v i cac bd vi kich hoat cd khi nang nhin biet va dieu khien. Ngoai ra, MEMS cdn md rdng khi nang thiet ke v i Ung dung. Hien nay rat nhieu cic loai cim bien mdi dua tren cdng nghe MEMS dang dugc phit trien manh me v i ngay cang dugc cii

thien ve chat lupng vdi ri't nhieu cic Qng dung nhU: cac cam bien gia tdc va gia tdc gde dugc tieh hpp trong cac dien thoai di ddng, hay nhU cic cim bien i p suit dugc g i n tren eae xe d td.

Chinh vi sU phat trien manh me eiia edng nghe MEMS, nhQng quy trinh kie'm tra danh gii chit lUpng eua cic sin pha'm MEMS la mdt nhu eau can thiet de nang cao chit lupng cho qua trinh sin xuit, tQ do cd the cii thien va tich hpp them cac tinh ning cho cac sin phi'm MEMS (sU tU can chinh - self calibration). Trong sd niy Tap ehi Tu ddng hda ngay nay se gidi thieu cung ban dpc mdt sd loai sai sd CO bin i n h hudng den cac linh kien MEMS, mpt sd thiet bj va quy trinh de kiem tra linh kien MEMS cung nhU nhQng djnh hudng phat trien cho loai linh kien nay trong tUOng lai.

Automation Today /1+2, 2012

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Hinh 2. He thdng kHm tra dd gid hda tUddng

CAC LOAI SAI HdNG THl/dNG GAP

Doi vdi mdt he thdng vi co thi cic sai hdng dupc chia thanh hai nhdm. Nhdm thQ nhat bao gdm nhQng sai hong dan den hdng toan bd linh kien, bing 1. Nhdm thU hai la nhQng sai hdng ve thdng sd he thdng hoac nhQng sal hong ngau nhien dan den linh kien lam vide sai chQc nang hoac true trie trong q u i trinh l i m vide.

Neu sai hdng i n h hUdng tdi cic tham sd chQc ning, thuong l i trpng lupng, dp ben hoac he sd suy giim thi thudng phii dUpc nam trong gidi han cho phep. Trong nhung trUdng hpp niy, cac tinh chat ddng v i tTnh thuong di ciing nhau. NhU vay, nhQng tinh chat ve chQc nang cd the la chi thj giin tiep eiia nhQng sai hdng v i t ly cua linh kien vi cP. SQ i n h hUdng cua mdt vai phuong thuc l<ie'm tra cd the dugc kie'm chQng nhd cic md hinh sai hong vat ly v i md phdng sQ dung phuong phap phan tQ hQu han. Mdt vi du eua sQ i n h hudng niy l i chit luong cua chin khdng len die tuyen dao ddng ciia cau true cpng hUdng v i do dd i n h hudng tdi tan sd giao dong va he sd pham chat cua dao ddng.

Bing 2 Net ke nhQng Idi thdng sd cd the gap trong vi xii ly nhidt linh kidn MEMS. Cau true hinh hpc cung nhi/

eiu true v i die tuyen v i t lidu bj i n h hudng trudc het bdi q u i trinh ch^ tao. NhQng thdng sd nay, sau dd, inh hudng tdi eic thdng sd quyet dmh die tinh didn hoac co eua cic t h i n h phan trong he thdng nhu dp cQng, trong lupng, hidu n i n g hay didn trd. Trong kiem tra danh gia, cic die tuydn nhu tan sd cpng hudng, lay gde (offset) va dp nhay cd th^ dUpc theo ddi.

D$c luyen cau triic O.k

c Sai hong bicii, be rpng, cliicu (lai, dp day

• 1 "1 khoang L Ma s i t va b i m dinh

• ( au Iriic thieu

( au tnic treo hojc phan I<h6nj.' CO djnh cua cau tnic

( hai lupng chan khong hoj ap .suat

DJc t u y ^ CO nhi^t ciia % .it l i ^ u H

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• D p ddn nhi$t \k d i | n d u i j ? B H$ so p h i t X9 biic x ^ V f e ^ l

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Bien thien ciia h? so c a

• D p ben, bien d^ng dan hoi

• Trpng lirpng

J l i e so suy giam dp nhot u

Dap i j n ^ h^ thong

• Tan so dao dpng

" H f so phSm chat

^ Phi tuyen

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iiyOn (..111 true cua \ a l dan He ninj.'

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Diicrny mo ta qua Irinh pha tap

D5c tuyen nhipt dipn ciia vat li^u

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Dicn Iro neng cua silic da tinli va k i m loai

Dien Ira tiep xiic

1 le so nhi?t ciia silic da tinh va k i m loai

He so ap tro ciia silic da tinh the va k i m loai

H? so Seebeck ciia silic da tinh the va k i m loai

H i n g so di^n moi va he so tdn!

hao

Nhicu dien Imh ki?n

Dap

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Dicn tro kv sinh 1 u kv sinh t ' a n i k\ sinh

mg h? thong Dich goc Dvi nha\ iha\ doi

Thav doi d j c tuyen tro khang

Loi cau tnic di^n tii Ngan mach

Silic da tinh the, don ldp, hai lop

• Giu silic da tinh va kim loai Kim loai, dom Idrp, hai ldn LOI vat dan

Silic da tinh Cac ldp kim loai

• TiSp xiic kim loai - silic

Ldi vi cau tnic co khi Bj ddnh thimg

• Ben ngoii cau tnic do d^c - Ben trong cau tnic c i m bidn

Ldi CO khi

- Vi cau tnic khdng tich rdi Ma sit tTnh

- Ldi khoang

" Cau tnic bat ddi xung

• Khic

Bdng 1. Cdc sal hdng cd the gdy loi cua mdt linh klin MEMS, tUdng thich nhiet vdi cau true CMOS, do loi sdn xuat

Bdng 2. Phdn logi cdc l6l thdng s6 cua linh kien l\AEMS tuang thich nhiet vdivixUly.

Mdt linh kien MEMS bao gom cau true ecf va cau true didn do dd cic sai hdng doi vol loai linh kien nay cung dupc chia t h i n h hai loai: sai hong tren cau true cO va sai hdng trdn cau tnic didn. Cac sai hong cau true eo co the la vd cau true hoac cic cau true chua tach rdi dan den sii hoat ddng khdng chinh xae ctia linh kien. Voi eau true dien dd cd thd* la sU n g i n maeh trong mach dien hoac cic phan tQ mach didn cd sai hong ve dp dan trong qua trinh che tao.

Bing 3 la vi du vd mdt cam bien tQ vdi nhQng loi moi trudng, co v i nhiet tidu bieu

Khi mdt he thdng l i m viee, vdi eae loi vat ly trong cau true didn hoac cP cd the dugc xae dinh vdi eae bvldc kiem tra tUPng ddi don gian d cap dp he thdng. Tuy nhidn, mdt q u i trinh nhu vay thudng cd nhung han che bdi vi nhQng Idi chinh chi cd the dupc xac dinh bang phUPng phap gian tiep v i do tan so edng hudng hoac dp nhay khi cd sU kich thich vat ly.

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Tl/ dong hoa ngay nay / 1 + 2 , 2012

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Sai hong dif n

Gia tri dien tra ngoai pham vi cho phep

He so ap dien tra ngoai pham vi cho phep

Mach dien ngan mach hoac gian doan

Ngan mach trong cau di^n tra Sai hong cc

Do Cling nam ngoai pham vi cho phep

Khoi lugmg qua lan

He so suy giam ngoai gia tri cho phep

Lo tren cau tnic

Vo hoac cac cau tnic chira tach rai

Thong s6 dif n kiem tra Offset

Do nhay Offset Dp nh?iy

Thong so difn Iciem tra Tan so cpng hudmg Tan so cpng huang va dp nhay

Dp nhay va he so pham chat

Dp phi tuyen Dp nhay

Bdng 3: NhUng sai hdng ca vd diin hay gap vd cdc thdng sd di kiim tra

KIEM TRA 6 CAP D O PHIEN (SILICON)

Mdt vi cim bien silic tich hpp thudng cd cic ket ndi dien giQa cic phan tQ, cd the lap trinh dugc vdi mdt ngudn dien cung cap cho hoat ddng eiia cim bien. Cam bien la mdt linh kien dung di phat hien eic tin hieu khdng dien tQ mdi trUdng va chuyen tin hieu dd thanh tin hieu dien, do dd khi kiem tra mdt cim bien, de tao ra tin hieu dien d dau ra ta can tie ddng v i o cim bien eic kich thich vat ly. Cic thdng sd gay ra Idi thudng l i nhiet dp, i p suat, dp am, Qng suit... cac thdng sd nay can dugc tinh den khi thUe hien mdt qua trinh kiem tra. Qua trinh kiem tra mdt thiet bj MEMS thudng ed hai cap dp:

cap dp phien va cap do thiet bj. Trong qua trinh kiem tra d cap dp thiet bj, thiet bj thudng dugc cho tuong t i c vdi mdi trudng xung quanh do dd cic kich thich vat ly va cic phep do kiem tra tren mdt thiet bj hoan chinh dugc thuc hien khi de dang.

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Hinh 3: cdc cdp do kiem tra Id cdn thiet cho cdc logi linh kiem MEMS

Tuy nhien thQ nghiem d cap dp thiet bj cd nhQng nhQpc diem ding ke': mdt trong sd dd la sU cham tre ciia vide xic djnh Idi do chu trinh che tao gay ra. Ben canh dd lim ting ehi phi cua mdt qua trinh ddng vd thiet bj. Mdt

khia canh quan trpng phii xem xet la thdi gian can thiet de phin hdi nhQng thdng tin ve nhQng sai hdng trd lai qua trinh sin xuat. Phien hoac linh kien thudng dugc che tao trong phdng sach trong khi qua trinh ddng vd lai dien ra tai noi khic do dd viec dUa nhQng thdng tin ve sai hdng trd lai noi sin xuat ed the' mat hing tuan hoac hang thing dan den sQ chim che trong viee eii thien qua trinh sin xuat phien. Odi vdi cic linh kien MEMS, q u i trinh kiem tra d mQc dp phien hieu q u i hOn rat nhieu so vdi vide kiem tra khi linh kien d i dQpc ddng vd. Hon nQa qua trinh kiem tra tren linh kien hoan chinh thQdng tdn kem hOn so vdi q u i trinh kiem tra d cap dp phien (khoang 10%). Do dd cic phQOng phip kiem tra d cap dp phien ngay cang dQpc cai thien de nang hieu qui eho qua trinh che tao cung nhU de tang chat lUpng eua sin pham.

Kich thich vgt ly

Thiet bj do dac

Gii tri do dac Phan tur kiem tra

Muc dich

Thdi gian kiem tra

Cap d9 phien

Khdng co day tlu cac loai tie dpng

Re

Gii tri dau ra, dau chua qua xu ly

Kiem tra cac thdng sd lien quan den Silic

Kiem tra cac chiic nang ca bin

Ngan

Cap d} thiet bi

Co the cd nhieu loai tic dpng

Dat

Cic gii tri dau ra, dau vio da qua xii ly

Kiem tra toin bd thiet bi bao gdm ci qui trinh ddng vd

Kiem tra chiic nang co bin, dp chinh xac, tinh thirc te, tinh dn dinh Dii

Bdng 4: So sdnh hai cdp do kiem tra

KIEM TRA 6 CAP DO PHIEN

Mdt he thdng kie'm tra d cap dp phien bao gdm bdn thanh phan chinh:

• Cac diem kiem tra

• Oau dd ket ndi cac phan tQ mach dien

• Mam cap giQ phien

• Cic thiet bj do dien tQ

Phien thQdng dQpc dat vao mam cap rdi ket ndi cic dau dd sau dd dQpc giQ tren mam bang cich hut chin khdng, qua trinh nay dupc thUe hien tU ddng. Toan bd he thdng dUpc giQ trong dieu kien nhiet dp tQ -65°C den 2000c, mdt sd trQdng hpp die biet cd the len den 300°C.

Ben canh dd mdt sd linh kien ddi hdi phai kiem tra trong mdi trudng chin khdng hoac i p suit thap.

Cd ba phuong phip co bin de thQ nghiem linh kien MEMS tich hpp d cap dp phien. Cich thQc thdng thQdng la sQ dung cic mach tQong tu va mach ky thuat sd de thQ nghiem cic chQc nang ciia linh kien. Phuong phap thQ hai l i sQ dung cic kich thich vat ly tuy nhien cung ed nhQng han che. Cich thQ ba thay the kich thich v i t ly bang each kich thich dien de kie'm tra linh kien.

SU ting trudng nhanh chdng cua cac thj trudng cho cic thanh phan MEMS da dan den sU md rdng ding ke' pham vi sin pham cua cac n h i cung cap thiet bj kiem tra

Automation Today /1+2, 2012

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Hinh 4: VIdu vi kIch thIch vdt ly cho qud trinh kiim tra Unh klin MEMS dcdp do phien

vi vay hien nay rat nhieu cic loai linh kien MEMS ngoii cic chuc ning chii yeu, cac yeu td i n h hudng ddn dp nhay ciia linh kien cung da dupc thuc hien. Ddi vdi cic linh kien MEMS thi nhiet dp la yeu td giy i n h hudng nhieu nhat den hoat ddng cua linh kien, ben canh dd thi ap suit cung CO vai trd ri't quan trpng.

Yeu to anh htrdrng L i n h kign

Cam hien nhiet dd Cam bien ap suat C am bien khi

Cam bien buc xa Cain bien gia tdc Cam bien van tdc

t!6c

Microphone HF-MEMS Vi liuane

G i i trj dj) dSc trirng^

Nhiet dd Ap suit Thinh phin khi Tdc dp ddng khi Ap suit Cudng dp birc xa

Gia tdc

Dp nghieng, van tdc goc

A p s u i t ;

Tan sd cdng hudng

Nhi?t do. ip suat mdi trudng

Nhi?t dp

Nhiet dp

Ap suit, nhiet dp, img suit

Gia tdc xoin, ip suit, img suit

Nhipt dp

Nhipt dp. i p suat, rung dpng \ a gia loc

Rung dpng

Goc p h i n xa

Bang 5: Mgt sd ddc trUhg linh kiin MEMS vd cdc yeu tddnh hUdng

De kiem tra mdt linh kien MEMS d cap dp phien ngudi ta thudng sQdung hai he kie'm tra: he kin v i he md. Vdi he kin thQdng dQpc dung de kiem tra cac loai cim bien i p suat, cam bien khi, cim bien do dp am... Vdi cic cim bien gia toe, cim bien co v i cim bien quang thi ta dung he md.

KIEM TRA d

CAP 0 6 PHI^N

CHO

C A M B I I N AP

SUAT

Odi vdi cim bien i p suit thudng dugc kiem tra d cap do phien bing cich sQdung phin tQ chuyen ddi cua c i m bien ap suit la mdt tam silicon cd the udn cong ve mdt phia dudi tic dung cua i p suit. Ap suit niy cd the tQ mdt vai mbars eho den xap xi 100 bar. Khi cd tie dung ciia i p suat, tam silicon bi udn cong v i dUa tren sQ thay ddi Qng suat tren tam silicon nay (xic djnh bang mdt cau true cau dien trd) ta se xic djnh dQpc g i i trj tin hieu dau ra theo i p suat tic dung, tQdd cd the xic djnh dQpc dp nhay cua cam bien. Oe d i t mdt i p suit vao cim bien thudng cd 3 cich:

• Ap suat dupc tic dung tQ phia trdn cua phien silic

• Ap suit dQpc t i c dung tQ phia dUdi cua phien silic

• Toin bd he kiem tra dUpc d i t trong budng chan khdng

(',ii h lac dyng

ap sual

So (16

( iicli thirc Yen lo anh hirdng

Msin che Dai ip

SUiil

Ap siiiil lac dyng tir j Ap suat lic dyng tir j Sir dyng budng chin phia tren ' phia dudi khdng

¥

^{/ • -}

Ap suat lir phia tren A p su.il l u phia T o i n bp h? trong chin

! dudi khdng Nhiel dp

NhivM <t(>

Linh ho(it, cd the mo long I )cii 7 bar

Nhicl do

Bdng 6: So sdnh cdc phUdng phdp tdc dung dp suA

Ap suit b| gidi h^n Rai linh ho?t, cd nhieu lya chpn

( h a n khong S<T cap den chin khdng ih.ip

Dpt chin khdng cao t 50 bar

bien ( i i . i thanh

I V U I , J c i v i l

Vila Re ^Dit

KliM TRA 6

CAP D O PHI^N

CHO

C A M BI^N

GIA T6C

Odi vdi cim bien gia tdc ngUdI ta sQ dung mdt bp tao rung dong de tao ra gia toe dat len be mat cam bien, dai gia toe nay eo the tu 1 g den hang tram g (g la gia toe trpng trudng = 9.8 m/s2) tuy theo tan so hoat dpng eiJa cam bien. Cac he kiem tra cam bien gia toe thuong la ban tif ddng hoac dieu chinh b^ng tay, he nay eo the dat themap suit hoac khi de khao sat eae yeu to anh hudng. He lam vide trong khoang nhiet do Xii -650C den 2000C.

Hinh 5: Oetgo gia toe diing cho he kiem tra cam bien gia toe

K\iM TRA CAP o p PHIEN CHO CAM BIEN KHI DUa tren cac yeu cau hpp phap eijng nhucac dieu kien an toan va thuan tien khi sii dijng, cam bien khi dUa tren cPsd MEMS dang trd nen co vai trd quan trpng. Trong ifng dung eho ky thuat d td, cdng nghiep hoac dan dung, nhu Tv dpng hoa ngay nay / 1 + 2 , 2012

^MAm jr

Hinh 6. He thong kiem tra cdm bien cao tdn RF

cau do ludng v i dieu chinh khi ddc nhU COX hoac NOX ngay cang eao. SQ dung eic budng chin khdng hay i p suit thap ket hpp vdi dieu khien ddng khi eho phep djnh lupng chinh xic va khdng tiep xiic cac khi dp d ndng dp thap tdi ppm (mdt phan trieu).

KIEM TRA CAP

Dd PHI^N CHO

CAM BI^N S6NG CAO TAN

Kiem tra trong chin khdng die biet can thiet cho linh kien MEMS, linh kien ed the lam vide d tan sd eao. Vdi cic thinh phan chuyen mach co khi, chin khdng se giiip tranh hieu Qng banh dinh, am hda eau tnic vi co eung nhQ hieu Qng nhdt khi va nhieu loan do i m trong khoang trdng.

NhQng phep kiem tra niy dQpc khuyen nghj sQ dung dau bPm chin khdng bin tu ddng vdi sd lUpng tay dd v i dau dd cao tan du dung, trong trudng hpp can thiet tan sd cd the len tdi 100 GHz. Nhieu Qng dung ddi hdi bd g i phien cd gia nhiet trong khoing tU -65°C den 250°C. NhQng die tuyen cua thiet bj kiem tra loai nay da dQpc sQ dung l i :

• Bd chia lade

• Bd phin tich dich chuyen eo

KIEM TRA

CAP D6 PHI^N

CHO CHudi

CAM BI^N H 6 N G NGOAI

MEMS

Cim bien hdng ngoai thudng dUpc sQ dung de do nhiet dp cua mdt ddi tupng cd khi nang phit bUc xa hdng ngoai. Oe kiem tra, nhQng thinh phan cim bien can tiep xuc vdi bQc xa hdng ngoai vdi bQdc sdng xic djnh. BQc xa dQpc tao bdi nhd bd phit tich hpp tren mdt man chip. Odng thdi, nhiet dp cua phien cung phii dQpc khdng che va bQdc khdi tao cho phep kiem tra dQpc thQc hien trong chin khdng. Vdi phien d i cd cim bien, can cd td hpp the chQa cic dau dd dQpc dau ndi vdi thiet bj do thdng qua nhQng kim loai dQpc ma ving hoac ma hpp kim trinh sai hdng vat ly giy ra.

(Tiep theo so thdng 3/2012

Hinh 7. Cdm bien hong ngogi

Automation Today / l-i-2, 2012