水素イオン注入により発生したシリコン結晶内プレートレットのTEM観察

愛総研・研究報告

創 刊 号 平 成11年 31

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水素イオン注入により発生したシリコン結晶内フ。レートレットのTEM

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井 村 徹

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Abs位act: A damaged layer formed by high dose hydrogen implantation into a silicon

wafer has been observed with cross sectional Transmission Electron Microscopy (XTEM). Hydrogen ions were implanted仇

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n-type(10的siliconat 80ke V with a

dose of 1.0x1017 atoms/cm2• Four kinds ofmajor d

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， cts， i.e.， (1) '"'-'(4)observed as in

the following， are investigated;

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point-l枕ed

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向ceand pr伊ctionrange (Rp)，

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(100)platelets existing around the Rp，β) (lll)platelets existing in the deeper region than the Rp，

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dislocation-like loops in the region deeper than the damaged layer. In the sample with lower implantation dose， iム 8.0x1016ato問 Icm2，the dislocation loop was not observed.

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fter300"C annealing， cracks were observed at the Rp. After475 "cannealing， the (111)platelets disappeared. In addition， the depth pro..

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leofhydrogen distribution was measured by Secondary lon Mass Spectroscopy (S1MS). Si-H bond condition was investigated by Fourier Transform lnfrared spectroscopy (F刀R).Comparing those results with the results obtained by XTEM， it is found that the point defects and platelets contain hydrogen atoms， and (111)platelets involve Si2・H6bond. 1. In仕oduction Hydrogen in silicon play組 importantro11 in technological applications

，

for exampl巴宅 passivation of the elec位icalproperties of 1)愛知工業大学総合技術研究所(豊田市) 2)愛知工業大学機械工学科(豊田市) 3)愛知工業大学電子工学科(豊田市) shallow acceptors

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donors

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and other point defects.

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the field of Silicon On

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sulator (SOl) material technology

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micro slicing process of silicon by hydrogen implantation technique has been recognized rem訂kably.百1Is

new process referred as Smart-cut process seems to hav巴advantages泊respectof cost and

32 _{TEM Observation of Ihe Plalelels in Hydrogen Implanted Silicon'創刊号・平成11年}

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Fig.1 XTEM Bright Field image， damaged layer as 1.0 x 1017_{dose implant巴dand defects.}

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TEM Observa.!ion01the Pla.telets in Hydrogen Implanted Silicon 33 The mostint巴:restingprocedure in this process is as follows; after hydrogen implantation

，

implantation on the d巴f巴ctshave been studied using a combination of cross s巴ctional Transrnission El巴ctron Microscopy (XTEM)

，

S巴condary Ion Mass Spec佐oscopy (SIMS) and Fourier Transform h企紅ed spectroscopy (FTIR).百lech姐 gesof micros住ucture in the damaged layer at various annealing te血peratur巴s are also investigated. 20Experiments Implantation of Fig.3 XTEM image， damaged layer as8.0x 1016dos巴implanted hydrogen ions was made

in(100)oriented silicon. after4750_C annealed 司 閣官吉国 around the projection rang巴 (Rp). During thermal annealingラ implanted hydrogen in silicon diffuses into the defects and the defects form cracks parallel to the surface， resulting in a very thin sliced silicon formation. Howeverラth巴 underlying mechanism is not well understood [3，4]， Inthe pres巴ntpaperヲimplantationofhydrogen into silicon is mad巴asa function of dos巴and temperature. The effl巴cts of hydrogen lO1:三:22 101三21 10E20 lOE19 lOE22 lOE21 lOE20 lOE19

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D巴pth The dos巴sranges企om1.0 x1016 tol.OxlO17_{Hcm-2. Samples were cut into} disks of 3mm in diameter and mechanically polished down. Th巴nthe disks were dimpl巴dat the c巴nter and thinned down by紅gon ion milling. The bright field imag巴S阻 dalso high resolution pictures of the damages and defl巴ctsinduced by

hydrog巴nimplantation wer巴takenby XTEM.

The depth profile of hydrogen in silicon was

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4 0 0

C>

C

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〈μ 口-:1.) Fig.4Hydrogen concentration obtained by SIMS.(as implanted and after4000C anneal_巴d)

TEM Observation of the Platelets i Hnydrogen Implanted Silicon'創刊号・平成11年 th巴 quantities of def巴，cts were obviously d巴cr巴ased.Especiallyラthelarg巴d巴fectslike a dislocation loop existing in th巴deeperregion disappeared. Th悶ラ the samples皿nealed at 3750C and 4750C were examined. These S釘nplesimplanted at a dose of 8.0xl016 Hcm大 After 3750C annealing

，

it was obse円巴dthat (100) platelets began expanding and changing to cracks. After th巴 475 OC annealing

，

the (111) plat巴lets disappeared (shown in Fig.3). The hydrogen concentratlOns were obtained 合om SIMS profiles (shown in Fig.4). The depth of highest concentr且tlOnreglOn was

magre巴mentwith the depth of damaged layer.It

shows the defects contain hydrogen. Comp紅ing with those implanted and annealed at 400oC

，

th巴 maximum value of conc巴ntrationwas d巴creas巴d after annealing. The thickn巴ss of high concentration r巴gionwas incr巴as巴d.This shows hydrogen has a trend to mov巴towardto surface. IncidentallyラtheFTIR results obtained with th巴 samples of (a) as implanted， (b) after 3000C JJi

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determin巴dby SIMS. In order to巴xamin巴 也c

bonding condition between hydrogen and siliconラ FTIR was utiliz巴d. Fig.5 Si-H bonding condition obtained by FTIR (as implanted， after 3000C and 4750C) 2400 盤 15 Fig目6Platelet concentration and hydrogen dos巴.

HydroEJo凶X10'6H/C~Cl)

3. Results and DIiscussion Fig.l shows th巴damagedlayers exarnined by XTEM after1.0x1017Hcm，2 dose implantation.

The depth of the layer was almost the same as th巴 depth of theoretical Rp. Four kinds of defects (1)"'-'(4) were observ巴d(shown in Fig.l) around this lay巴r.(1) (100) platelets existing parallel to th巴 surface. (2) (111) platel巴ts existing betw巴巴nthe Rp and deep巴rregion than the Rp. (3) small defects like a point defect existing in the shallow region ofthe layer.(4) l訂ge d巴f巴cts like a dislocation loop existing in the de巴P巴r r巴gion than the Rp. Fig.2 shows th巴 damaged lay巴:rs after 8.0x1016Hcn12 _dose implantation. Comparing with Fig.1， B 2 0 7 4 6 5 3 ( コ Z )_{百 一} ω百 一 且 ﹄ O L ω ﹄_E コ Z

TEM Observation of the Platelets in Hydrogen Implanted Silicon 35 ~ 0.15 E E

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A 昌弘 A th巴lengthof plat巴letdid not change significantly.Ackn.owledg ements This work partially supported by The Naito Research Grant and

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5 司 自 1 0 ~ 15 Research Foundation for the Electrotechnology of Chubu. The author would like to thank S. Yamauchi and H.

Hyd~ogen dose(X1 0 rOH/cm ζ)

Fig.7 Platelet width and hydrogen dose目

annealed and (c) after 4750C _叩nealed

，

w_巴re shown in Fig.5. The value ofpeak且t2070 [cm-1]

in as-implanted samples decreased after 3000C and 4750C annealing. The peaks at 2070 [cm.1_] correspond to the exist巴nc巴ofSi₂-H₆ bond. This tempera印re is s但ne as the temperature of disapp巴aranceof th巴(111)platelets， so that it was confirmed that the (111) plat巴letsinvolve Si2-H6 bonds. Comp紅白gthe damag巴dlayers at various ranges of dose examined by XTEM，社le number of platelet increased with dose， especially increased rapidly at th号3.0x1016

atoms/cm2 _{dose or more as shown in Figure 6.}

Th巴 width of platelet at the damaged layer became wider with dos巴shownin Figure 7

，

but Ohshima

，

Research LaboratoriesラDensoCo.

，

Ltd. for their supplies of silicon wafers and SIMS data. References 1. M. Bru巴1，El巴ctronicslett巴 民6th_July， _vo1.₃₁ (1995) 1201 2. M. Bruel

，

Nucl.Inst. and Meth. B 108 (1996) 313 3. S. Muto

，

S. Takeda and M. Hirata: Philosop. Magaz. A 72(1995) 1057 4. M. K. Weldon， V. E. Marsico et al.:J. Vac. Sci. Technol.B 15(1997)1065 ( 受 理 平 成11年3月20日)