ETRI Journal, volume 16, number 1, April 1994
`
`45
`
`A Study on Modified Silicon Surface after
`CHF;3/C2F, Reactive lon Etching
`
`Hyung-Ho Park, Kwang-Ho Kwon, Sang-Hwan Lee, Byung-Hwa Koak, Sahn Nahm,
`
`Hee-Tae Lee, Kyoung-Ik Cho, Oh-Joon Kwon and Young-II Kang
`
`CONTENTS
`
`ABSTRACT
`
`I.
`If.
`
`INTRODUCTION
`EXPERIMENTAL
`
`lt. RESULTS AND DISCUSSION
`
`IV. CONCLUSIONS
`
`The effects of reactive ion etching (RIE)
`of SiOz layer in CHF3 / CoFg on the un-
`derlying Si surface have been studied by X-
`ray photoelectron spectroscopy (XPS), sec-
`ondary ion mass spectrometer, Rutherford
`backscattering spectroscopy, and high res-
`olution transmission electron microscopy.
`We found that two distinguishable modi-
`fied layers are formed by RIE :
`(i) a uni-
`form residue surface layer of 4 nm thick-
`ness composed entirely of carbon, fluo-
`rine, oxygen, and hydrogen with 9 different
`kinds of chemical bonds and (ii) a contam-
`inated silicon layer of about 50 nm thick-
`ness with carbon and fluorine atoms with-
`out any observable crystalline defects. To
`search the removal condition of the sil-
`icon surface residue, we monitored the
`changes of surface compositions for the
`etched silicon after various post treatments
`as rapid thermal anneal, O2, NF3, SF¢, and
`Cl, plasma treatments. XPS analysis re-
`vealed that NF3 treatment is most effec-
`tive. With 10 seconds exposure to NF3
`plasma, the fluorocarbon residue film de-
`composes. The remained fluorine com-
`pletely disappears after the following wet
`cleaning.
`
`IP Bridge Exhibit 2222
`IP Bridge Exhibit 2222
`TSMC v. Godo Kaisha IP Bridge 1
`TSMC v. Godo Kaisha IP Bridge 1
`IPR2017-01843
`IPR2017-01843
`
`

`

`4G
`
`Hyung-Ho Park,etal.
`
`ETRI Journal, volume 16, number 1, April 1994
`
`I.
`
`INTRODUCTION
`
`Il. EXPERIMENTAL
`
`Reactive ion etching (RIE) of SiO2 on Si
`in a fluorocarbon plasmais a standard process
`in the production of very large scale integrated
`devices, But it can cause damage and contam-
`ination effects in exposed materials [1,2].
`In fact, plasma species can be trapped in the
`silicon matrix, and residue layers can be made
`up of reactant species and reaction products.
`Various fluorocarbon plasma treatments
`and their interaction with the Si or SiOz sur-
`faces have been analyzed in recent years [3-5].
`For removal of silicon surface residue re-
`
`sulting from the RIE, oxygen plasma ashing
`or downstream soft etching treatments have
`been studied [6,7]. Although oxidizing pro-
`cess is used for removing the surface residue
`at present, this approach presents a problem of
`consuming the silicon substrate due to oxida-
`tion and changing in the physical dimension
`for a cell.
`
`In this study, a modified silicon surfaceaf-
`ter RIE in CHF3 / C2F¢ plasma has beeninter-
`preted in detail using X-ray photoelectron spec-
`troscopy (XPS), secondary ion mass spectrom-
`eter (SIMS), Rutherford backscattering spec-
`troscopy (RBS), and high resolution transmis-
`sion electron microscopy (HRTEM).
`Andas post etch treatments to removesili-
`con surface residueresulting from the RIE, the
`effects of O2, NF3, SF¢, and Clz plasmatreat-
`ments have been studied. Rapid thermal anneal
`treatment has beenalso carried out.
`
`A layer of 600 nm thick oxide was de-
`posited on a chemically cleaned 0.85-1.15
`ohm-cm, B doped (100) silicon wafer by low
`pressure chemical vapor deposition method.
`RIE process were performed in QUAD 484
`Dryteck system using a CHF3 / C2F¢ gas mix-
`ture. RF powerdensity was 1.203 W/em?. The
`gas flow was 100 sccm and the chamberpres-
`sure was 700 mTorr.
`In this experiment, 80
`seconds ofsilicon overetching was performed
`after reaching the SiO2/Si interface. The etch
`end point was detected by laser interferome-
`try. O2 plasma treatment was effectuated with
`PRstripper of Barrel type. NF3, SF¢, and Clo
`plasma treatments were carried out after RIE
`using Applied Materials Precision 5000 sys-
`tem without applying a magnetic field. The
`gas pressure was 100 mTorr and RF power was
`150 watts. Post etch treated samples were im-
`mersed in H2SQ4 / H2O2 (4/1) and in 1 / 20
`buffered HF successively to investigate the wet
`cleaning effect. Rapid thermal anneal (RTA)
`treatments were carried out at nitrogen atmo-
`sphere for 1 minute. Prior to RTA treatments,
`the wafers were given a wet cleaning.
`The XPS experiments were performed ona
`V.G. Scientific ESCALAB 200R spectrometer
`using Mg ka (1253.6 eV) operating at 300 W
`radiation. Narrow scan spectraofall regions of
`interest were recorded with 20 eV pass energy
`in order to quantify the surface composition
`and identify the elemental bondingstates. The
`
`

`

`96
`
`
` ti a
`
`104
`102
`100
`98
`Binding Energy/eV
`(a)
`
`106
`
`
`
`
`280 282 284 286 288 290 292 294 296
`Binding Energy/eV
`(b)
`
`684
`
`692
`690
`688
`686
`Binding Energy/eV
`(d)
`
`694
`
`528
`
`536
`534
`532
`530
`Binding Energy/eV
`(c)
`
`538
`
`"iz. 1. Deconvolutions of narrow scan spectra with pass energy of 20 eV for reactive ion etched sample; (a) Si 2p, (b) C
`Is, (c) O Is, and (d) F Is.
`
`SIMSresults were obtained with CAMECA
`
`IMS-4F by monitoring the negatively charged
`secondary ions using oxygen ions bombard-
`ment. The oxygen primary beam current was
`30 ‘nA with net bombarding energy of 8 keV.
`For ion channeling experiments, Het ions of
`1 MeV were used and backscattered ions were
`
`collected at the detection angle of 110 degrees
`with NEC 3SDH. The cross-sectional HRTEM
`
`analysis was carried out with Philips CM20T /
`STEM and operating voltage was 200 KV.
`
`The XPS analysis showsthat the residue
`film due to exposureof silicon surface to CHF3
`/ C2F¢ reactive ion plasma consists mainly of
`carbon and fluorine.
`
`Fig. 1 represents narrow scan spectra of
`Si, C, O, and F. No considerable peak shape
`change due to X-ray irradiation has been ob-
`served during the measurement. Their peak
`attributions, binding energy, full width at half
`maximum (FWHM),and percentof total area
`(contributionsofseveral bondsto the integrated
`peak) are listed in Table 1. The Si 2p spectrum
`
`

`

`
`
`Table 1. Decompositions of the Si 2p, C Is, O Is, and F
`1s core level distributions.
`
`
`
`
`can be resolved into Si-Si, Si-C, and Si-O/F.
`The binding energy of Si as 102.8 eV for Si-O
`bond meansthat incomplete oxidation of sili-
`con occurs [8] because 103.4 eV binding en-
`ergy is observed for normal Si-O bond in SiO».
`Andthe Si-O bond contains a small quantity of
`Si-F bond because a few fluorine is revealed
`to bind to silicon in F 1s spectrum. The C 1s
`spectrum can beresolved into 6 chemical com-
`ponents which can be attributed to C-Si, C-C
`or H, C-CF, (x <3), C-F,, C-F2, and C-F3,
`respectively. The majority of O atoms bind
`
`to Si with a binding energy of 532.6 eV. The
`O 1s binding energy of 534.8 eV seemsto be
`resulted from the bond with a high electroneg-
`ative element asfluorine. In the F ls spectrum,
`wealso find the presence of the bond with oxy-
`gen at 692.1 eV.
`
`IonCounts
`Secondary
`
`10°
`
`0
`
`200
`
`400
`
`600
`
`800
`
`1000
`
`1200
`
`Depth{angstrom)
`
`>, =, SIMSdepth profile after reactive ion etching.
`
`Fig. 2 represents the depth profile of vari-
`ous elements measured by SIMS.It is shown
`that the impurities in the ~50 nm thicksili-
`con substrate mainly consists of carbon and
`fluorine. RBS / channeling spectra are given
`in Fig. 3 for reactive ion etched silicon and
`control samples. The control sample has been
`cleaned with a buffered HF solution before
`
`RBS measurement. At 183, 236, and 273 chan-
`nels, peaks due to C, O, and F contaminants
`are shown for the reactive ion etchedsilicon,
`
`Increase in the silicon surface peak intensity
`for the reactive ion etched sample mayresult
`from the existence of the fluorocarbon residue
`
`

`

`Hyung-Ho Park, etal.=49
`ETR} Journal, volume 16, number 1, April 1994
`
`
`
`Channel
`
`Fig. 3.
`
`lon channeling spectra of control sample and
`reactive ion etched sample.
`
`film on the reactive ion etched silicon surface
`
`or from silicon crystalline defects which can be
`produced by carbon andfluorine contaminants.
`Theposition of the silicon surface peak for the
`reactive ion etched sample has been shifted by
`about2.4 keVrelative to the control sample due
`to the energy loss of Het beam during the pas-
`sage through the residue layer. To check any
`
`
`
`Fig. 4. Cross-sectional HRTEM imageof reactive ion
`etchedsilicon.
`
`possible crystalline damagein the silicon sub-
`strate containing the impurities, cross-sectional
`HRTEM images have been taken for the re-
`active ion etched silicon. About 40 nm thick
`gold is deposited to distinguish the fluorocar-
`bon residue layer from epoxy which is used for
`cross-sectional TEM specimen preparation.
`Fig. 4 represents the image. The residue
`layer is continuous and uniform. The thickness
`of the residue layer is measured as ~ 4 nm using
`a spacing of Si (111) planes of 0.313 nm as an
`internal magnification standard. The interface
`between the residue layer and silicon substrate
`is sharply defined and smooth. In the substrate
`silicon lattice image, we can find neither point
`defect cluster nor distinct planar defect. From
`these results,
`the relatively high intensity of
`silicon surface peak for the reactive ion etched
`sample compared to the control sample in ion
`channeling spectra (Fig. 3) can be attributed to
`the residue layer. Therefore we can conclude
`that under our experimental conditions the ma-
`jor modifications by RIE are the formation of
`a 4 nm thick fluorocarbon residue layer on the
`silicon surface and a ~ 50 nm thick contami-
`
`nated silicon layer which contains carbon and
`fluorine atomsbut no crystalline defect.
`Angle resolved XPS has been carried out
`for analyzing the distribution of chemical
`bondsin the residue film. The angle between
`sample surface and detector (take-off angle)
`varies from 15 to 75 degree. For the decon-
`volution of the spectra, the binding energies
`and the FWHMsin Table 1 are used.
`
`

`

` Si substrate
`Si substrate
`
`5 3 45
`
`&@ 7
`
`Take-off Angle ( °)
`(a)
`
`
`
`1S
`
`30
`
`45
`
`60
`
`75
`
`Take-off Angle (-°)
`
`(b)
`
`Take-off angle dependenciesof observed bonding
`species; (a) Si and (b) C.
`
`Fig. 5 represents the variations of chemical
`contributions to silicon and carbon with take-
`off angle. As the angle decreases, the contribu
`tion of the surface bonding state to the observed
`peak intensity increases. From the comparison
`of slope changes of bonding contributions with
`take-off angle,
`the distribution of bondings
`can be defined. Forsilicon (Fig. 5(a)), Si-C
`bonding is found to be under the Si-O bond,
`but abovethe silicon substrate.
`In Fig. 5(b),
`area % of C-CF, and C-F, (y=1,2, 3) slightly
`
`decrease and those of C-Si and C-C/H increase.
`
`Si substrate
`
`impurities penetrated
`region
`
`O-F
`
`C-F
`
`C-C/H
`B] Si-O
`3 Si-F
`BB Si-c
`
`Schematic diagram of reactive ion etchedsilicon
`surface.
`
`This implies that C-Si and C-C/H bondsexist
`under the C-F polymerlayer. Since the sample
`is exposedtoair for transfer to analyze, we have
`to always consider the physisorbed 1~2 mono-
`layer (ML)of carbon on the top of the sample.
`This physisorbed carbon causes a decrease in
`slope with take-off angle. Then although the
`slope change of C-Siis larger than C-C/H, we
`cannot say that the C-Si bond exists under the
`C-C/H bonds. With oxygen and fluorine, from
`the comparisonofthe slope changesfor the area
`% of each bond constituents, it can be said that
`O-F bondexists on the O-Si one and F-C bond
`
`exists between F-O and F-Si ones.
`
`From these results, the schematic descript
`ion of silicon surface after RIE can be given
`in Fig. 6. The physisorbed 1-2 ML of extra
`
`

`

`Atomic%
`
`Temperature( °C )
`
`. Composition change of the reactive ion etched
`silicon surface after rapid thermal anneal.
`
`carb on has not been considered. Atthe surface,
`O-F bond over C-F polymer which mainly
`composesresidue layer is found. Between the
`C-F polymerlayer and the Si substrate, C-C/H,
`Si-C, Si-O, and Si-F bondsexist.
`Fig. 7 shows a composition change of the
`reactive ion etched silicon surface using XPS
`after RTA treatment undernitrogen atmosphere
`for 1 minute, After anneal above 800°C,flu-
`orine remains under 1 atomic percent. This
`meansthat above 800°C, thermal decomposi-
`tion of residue layer is completed.
`Fig. 8 showsthe variation of chemical con-
`tributions for C 1s with annealing temperature.
`As shownin Fig. 7, area percents of C-CF, and
`C-F, bonds remain constantafter anneal above
`
`Area%
`
`Temperature( “C)
`
`The variation of chemical contributions for C Is
`
`with anneal temperature.
`
`800°C. Decrease of C-C/H bondis found due
`
`to the formation of Si-C bond between carbon
`
`and substrate silicon above 900°C.
`
`Depth profile results using SIMS for the
`annealed samples at 600°C and 800°Care pre-
`sented in Fig. 9. In Fig. 2, we have foundthat
`the thickness of contaminated silicon layer is
`~ 50 nm. RTAtreatment at 600°C is revealed
`
`to induce in-diffusion of C and F species to ~
`100 nm depth,but noin-diffusion phenomenon
`is observed for the 800°C treated specimen.
`This seems dueto the fast decompositionofthe
`C-F residue film which remains on the surface
`
`till 600°C and plays an important role of diffu-
`sion source. With 800°C annealed sample, the
`
`

`

`JonCounts
`Secondary
`IonCounts
`Secondary
`
`0
`
`400
`
`1200
`800
`Depth (angstrom)
`(a)
`
`1600
`
`2000
`
`EFRI Journal, volume 16, number i, April 1994
`
`silicon surface by XPS analysisafter the treat-
`ments. And wet cleaning process has been ap-
`plied to all of the post etch treated samples.
`The remained fluorocarbonresidue after every
`post etch treatments can be estimated from the
`changes of the fluorine and silicon composi-
`tions.
`
`Fig. 11 shows C 1s (a) and F 1s (b) peaks
`obtained after the O2 treatment. With thefirst
`1 minute exposure, the liberation of fluorine
`from fluorocarbonresidue layer proceeds. For
`the C 1s spectrum, the peaks corresponding
`to the C-F, bondings continuously decrease
`and almost disappear after 10 minutes expo-
`sure. The C- CF, contribution also decreases
`but after 2 minutes exposure, it becomes con-
`stant. It seems to be due to the appearance of
`C-O bond which has nearly the same binding
`energy as C-CF,. With fluorine, according
`0 1120=1400280 560 840
`
`
`to the exposure, the contribution of the F-O
`Depth (angstrom)
`slightly increases and that of F-Si severely in-
`(b)
`creases. The F-C bond is almost completely
`converted into F-Si bond above 20 minutes ex-
`
`
`
`
`
`Fig. “. Depth profile analysis using SIMS for annealed
`samples at (a) 600°C and (b) 800°C,for 1 minute,
`respectively.
`
`secondaryion countsprofile of carbon remains
`higher than that of fluorine. This may result
`from the almost remained carbon with C-C/H
`or Si-C bondsafter anneal above 800°C.
`O2, NF3, SFs, and Cl, plasmatreatments
`have been carried out to remove the residue
`layer as post etch treatments. Fig. 10 shows a
`composition changesof the reactive ion etched
`
`posure to the O2 plasma. Above 10 minutes
`of exposure to the O» plasma, the atomic %
`remains almost constant and the formation of
`
`S102 is almost saturated with 3-4 nm thickness.
`These bonding states of the polymer film as
`F-Si, C-O, and Si-O after the QO, treatment
`are found to be easily eliminated by succes-
`sive cleaning process. Through NF3, SF, and
`Cly treatments, no additional elements such
`as nitrogen, sulfur, and chlorine are detected.
`Surface compositions drastically change after
`
`

`

`
`
`(b)
`
`Composition changesof the reactive ion etched silicon surface after (a) O2, (b) NFs, (c) Cl, and (d) SF¢
`treatments.
`
`the treatments for 10 seconds, but maintain al-
`most constant with exposure times of 10 to 30
`seconds. The effects of post etch treatments
`seem to be saturated within 10 seconds expo-
`sure. Among the above three treatments, NF3
`treatment (Fig. 10(b)) results in the smallest
`fluorine atomic %. And after successive wet
`
`treatment, no fluorine is detected in the sample
`treated using NF3 plasma. With SF. plasma,
`the atomic % of fluorine decreases to an half
`
`value after the wet treatment, but with Cl
`
`plasmait does not change.
`Fig. 12 represents the photoelectron spec-
`tra of fluorine after NF3, SFs, and Clz plasma
`
`

`

`(a)
`
`(b)
`
`(©)
`
`be
`681
`685
`689
`693
`697
`Binding Energy /eV
`
`Photoelectron spectra of fluorine after (a) NF3,
`(b) SFand (c) Clp plasma exposures for 10 sec-
`onds, respectively.
`
`10min
`
`2min
`
`lmin
`
`Lo
`280
`286
`292
`298
`Binding Energy /eV
`
`r20min
`
`10min
`
`2min
`
`imin
`
`same with that of just reactive ion etched sam-
`ple. Fluorine mainly binds to carbon with a
`binding energy of ~ 689 eV. With SF, plasma
`treatment, fluorine peak enlarges and peak po-
`sition moves to a low binding energy value
`comparing to that of Cl2 plasma treated sam-
`ple. This is due to the increase of F-Si bond
`contribution with a binding energy of 686.9
`eceSee
`681
`685
`689
`693
`697
`eV. Increase of F-Si bond is clearly seen with
`Binding Energy /¢V
`NF3 plasma treated sample. Area of F-Si
`bond is nearly two times larger than that of
`F-C bond. This chemical state change means
`the decomposition of the residue layer and in-
`duces the easy removal of residue by succes-
`sive wet cleaning. These results show that NF3
`plasma treatment is most effective to remove
`the residue layer on the reactive ion etchedsil-
`
`Influence of O2 plasmatreatmenton (a) C ls and
`(b) F ls.
`
`exposures for 10 seconds, respectively. The
`shape and bondsdistribution of the fluorine
`peak for Clz plasma exposure is almost the
`
`

`

`Oyung-Ho Park. e. 2),
`
`v1 wt
`
`[4]
`
`[5]
`
`(6)
`
`(7]
`
`(8)
`
`to CHF; plasmas,” J. Electrochem. Soc., vol.135,
`no.6, pp. 1472-1477, 1988.
`
`A. S. Yapsir, G. Fortuno-Wiltshire, T. P. Gambino,
`R.H.Kastl, and C. C. Parks, “Near surface damage
`and contamination ofsilicon following electron cy-
`clotron resonance etching,” J. Vac, Sci. Technol. A,
`vol.8, 00.3, pp. 2939-2944, 1990.
`
`T. Kuroda and H. Iwakuro, “A study of CCL.F,
`magnetron ion etching damage and contamination
`effects in silicon,” Japan. J. Appl. Phys., vol.29,
`no.5, pp. 923-929, 1990.
`
`J. Fonash, G. S. Ocehricin,
`X. C. Mu, S.
`S. N. Chakravarti, C. Parks and J. Keller, “A study
`of CCIF;/H, reactive ion etching damage and con-
`tamination effects in silicon,”J. Appl. Phys., vol.59,
`no.8, pp. 2958-2967, 1986.
`
`D. Chu, “An integrated solution for reducing ox-
`ide etch-related damage,” Proc. Semicon/Korea
`Tech. Sympo,, Seoul, Nov. 9-10, 1993, pp. 175-184.
`
`K. Takase, T. Igarashi, N. Miyata, K. Moriki,
`R. Sugino, Y. Nara. T. Ito, M. Fujisawa and T. Hat-
`tori, “Native oxides formed during wet chemical
`treatments,” Proc. 21st Int. Conf. on Solid State
`Devices and Materials, Tokyo, Aug. 28-30, 1989,
`pp. 393-396.
`
`icon surface.
`
`Y CONCLUSIONS
`
`Bycross-sectional HRTEM analysis, about
`4 nm thick residue layer is observed onthere-
`active ion etched silicon surface in the CHF3
`/ C2Fo plasma.
`It is found that carbon in the
`residue layer consists of 6 chemical compo-
`nents as C-Si, C-C/H, C-CF, (x < 3), C-F;,
`C-F2, and C-F3 using XPS, SIMS, RBS/ chan-
`neling, and HRTEM works show that ~ 50 nm
`thick contaminated silicon layer which con-
`tains mainly carbon and fluorine, has no ob-
`servable amountof defect. With rapid thermal
`anneal, in-diffusion phenomenon of C and F
`into the silicon lattice is found under 800°C.
`NF3 treatment is revealed to be the most ef-
`fective post-etch treatment for removing the
`surface residuc. Fluorocarbon residue layer
`decomposes with 10 seconds exposure to NF3
`plasma and completely disappears with succes-
`sive wet cleaning.
`
`SeaieCES
`
`(1) J. W. Coburn,“In situ Auger electron spectroscopy
`of Si and SiO. surfaces plasma etched in CF,-
`Hz glow discharges,” J. Appl. Phys., vol.50, no.8,
`pp. 5210-5213, 1979.
`
`[2] S.J. Fonash, “An overview of dry etching damage
`and contamination effects,” J. Electrochem. Sec.,
`vol.137, no.12, pp. 3885-3892, 1990.
`
`[3] C. Cardinaud, A. Rhounna,G. Turban,and B. Grol-
`Icau, “Contamination of silicon surfaces exposed
`
`

`

`ketene y
`
`
`
`received
`Sang-Hwan Lee
`the B.S.
`and M.S. degree
`from Kyungpook National
`University in 198) and 1987,
`respectively. He joined in the
`Semiconductor
`Technology
`,
`Division of Electronics and
`le
`Telecommunication Research Institute in 1987. His
`research areas were ion MeV beam analysis and ion
`implantation damage until 1993.
`He is currently
`responsible person of opto-electronic device packaging
`in Semiconductor Packaging Research Section.
`
`Electronics and Telecommuni-
`
`Byung-Hwa Koak received
`the B.S.(1980) and M.S.(1982)
`degrees
`in
`physics
`from
`Kyunghee University.
`Since
`1985 he joined in the Semicon-
`ductor Technology Division of
`
`cation Research Institute. His research areas of interest
`
`are surface and interface analysis of semiconducting
`materials and characterization of unit process for the
`preparation of semiconducting devices. He is currently
`responsible person of secondary ion mass spectrometer
`in Materials and Characterization Section.
`
`
`
`Hyung-Ho Park received
`the B.S. degrec from Han-
`yang University
`in
`1981,
`the M.S. degree from Korea
`Advanced Institute of Science
`and Technology and the Ph.D.
`degree in material science from
`University ofBordeaux I, France in 1988. Since 1989 he
`
`has been with the Semiconductor Technology Division
`of Electronics
`and Telecommunication Research
`
`Institute. His research areas of interest are surface
`and interface analysis of semiconducting materials and
`characterization of unit process for the preparation of
`semiconducting devices. He is currently responsible
`person of X-ray photoelectron spectroscopy, Auger
`electron spectroscopy and scanning electron microscopy
`in Materials and Characterization Section.
`
`
`
`received
`Kwang-Ho Kwon
`the B.S., M.S. and Ph.D. de-
`grees in electrical engineering
`from Korea University in 1985,
`1987, and 1993. Heis currently
`a senior member of technical
`
`staff in the Process Develop-
`ment Section of Electronics and Telecommunication Re-
`
`search Institute, His research field includes semiconduc-
`
`tor processing of application specific integrated circuits.
`His currentinterests are dry etching technologies.
`
`

`

`ETRI Journal, volume 16, number 1, April 1994
`
`Hyung-Ho Park, etal.
`
`57
`
`
`
`Sahn Nahm received the B.S.
`degree from Korea University
`in 1983,and the Ph.D. degree in
`material engineering from Uni-
`versity of Maryland, USA in
`1990. He worked as Post Doc-
`
`toral Researcher in University
`
`of Maryland from Jan. 1991 to Dec. 1991. Since 1992
`he has worked in the Semiconductor Technology Divi-
`sion of Electronics and Telecommunication Research In-
`Stitute. His interesting field of researchis structural anal-
`ysis of semiconducting materials, cspecially thin film and
`hetero-epitaxial multilayers. Now heis in charge of trans-
`mission electron microscope, X-ray diffraction and TEM
`sample preparation labs in Materials and Characterization
`Section.
`
`Hee-Tae Lee
`
`received the
`
`Technology Division of Elec- tronics and Telecommunica-
`
`B.S. degree from National Cen-
`tral Vocational Training Insti-
`tute in 1978. Since 1981 he
`
`has joined the Semiconductor
`
`tion Research [nstitute. His research area of interest is
`
`optical semiconducting device fabrication. He is cur-
`rently working on optical device package.
`
`tively. He joined the Elec- tronics and Telecommunica-
`
`Oh-Joon Kwon
`received
`the B.S. and M.S. degrees
`in electronic engineering from
`Kyungpook National Univer-
`sity in 1977 and 1989, respec-
`
`tion Research Institute in 1977. He has worked in the
`
`areas Of semiconductorprocessintegration and character-
`ization of semiconducting matcrials. He is now working
`on the development of microwave deviccs.
`
`
`
`Kyoung-Ik Cho received the
`B.S, degree in materials sci-
`ence from Ulsan Institute of
`
`Technology in 1979, and the
`M.S. and Ph.D. degrees in ma-
`terials science and engineering
`from Korea AdvancedInstitute
`
`of Science and Technology, in 1981 and 1991, respec-
`tively. He joined the Electronics and Telecommunica-
`tion Research Institute (ETRI), Taejon in 1981. He is
`currently a head of Materials and Characterization Sec-
`tion in Semiconductor Technology Division at ETRI. His
`tesearch interests include characterization of semicon-
`
`ducting materials, heteroepitaxy of sémiconductor thin
`films, and structural analyses of heterointerfaces,
`
`
`
`Young-Il Kang received the
`B.S. degree in Electrical En-
`gineering from Seoul National
`University in 1966 and the M_S.
`degree from Fairleigh Dickson
`University in 1989. He joined
`Fairchild Semiconductor Ko-
`
`rea as a process enginecr in 1969 and moved to Semicon-
`ductor Technology Division of Electronics and Telecom-
`munication Research Institute. (ETRI) in 1979. He has
`worked in semiconductor process integration area for
`the most of his working time in both of Fairchild and
`ETRL.His currentinterests are failure analysis, new de-
`vice structure and process integration. He is now working
`for the new antifused programmable read only memory
`device that can be implementedeasily in the conventional
`complementary metal oxide semiconductor process and
`can be easily integrated in the application specific inte-
`prated circuit families.
`
`