Defect Control in Semiconductors

742 Pages·1990·28.737 MB·English

by  K. Sumino (Eds.)

DEFECT CONTROL
IN SEMICONDUCTORS
ProceedingsoftheInternationalConferenceon
theScienceandTechnologyofDefectControlinSemiconductors
TheYokohama21stCenturyForum
Yokohama,Japan, September17-22,1989
Editedby
K.SUMINO
Institute/orMaterialsResearch
TohokuUniversity
Sendai, Japan
VolumeII
~tt
~
~
1990
NORTH-HOLLAND
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v
PREFACE
This bookcontains 254papers presented at "The International Conference on the Science and Tech
nologyof Defect Control in Semiconductors (IC-SIDCS)" which was held on September 17-22, 1989in
Yokohama, Japan. The conferencewasorganizedas The Yokohama 21stCentury Forum 1989 to commemo
rate the centenaryofYokohama City.
Defectcontrol insemiconductorsisa keytechnology for realizing the ultimate possibilities of modern
electronics. It isobviousthatthebasisfor suchcontrolliesinan integratedknowledge ofavarietyofdefect
properties. From this viewpoint, the aim of the conference was to provide a forum for the discussion of
defect-relatedproblemsinconnectionwithdefect controlinsemiconductingmaterials. The organizersofthe
conferenceespeciallyhopedthatscientistsinthe fieldofbasicresearchandengineersinvolvedinapplication
relatedto electronicdevicescould mutually benefitfromjointdiscussion.
Basic research on defects in semiconductors seems to have initiallystartedwith the question of what
effects appear if the regular tetrahedral coordination of a typical semiconductor is disturbed locally by
the introductionof some structural defects or impuritieswhich have differentvalences, different sizesand
different inner shells. A large number of papers have so far been published in this research field. The
problems have also been discussed at a series of international conferences such as the ICDS. Fairlygreat
progressseems tohavebeenachieved inthisfield,especiallyinunderstandingthe natureofrelativelysimple
typesofdefects. However, the fieldofresearchisnowexpandingveryrapidly,and defects tobe investigated
are becoming more and morecomplicated.
On the oneside, the study ofdefects insemiconductorsisbecomingincreasinglyimportantto the field
of applications as great progress is made in electronic device technology on the basis of developments in
material-processingofsemiconductors. In the earlystages of the study,onlynegative or harmfulaspects of
defectswere recognized. Thus, defect study inthis fieldinitiallyfocused on findingmethodsofsuppressing
or avoiding generation of harmful defects during crystal growth or device processing in order to facilitate
devicefabrication. Recently, a new trend has appeared in which defects are positively utilized to improve
deviceperformanceand reliability.Typicalexamplesare intrinsicandextrinsicgetteringtechniquesinsilicon
technologyand utilizationofEL2toachievesemi-insulationofGaAs.The mostimportantmatternowseems
to be to find ways to control the distribution, density and even properties of any defects rather than to
completelyeliminatesuch defects from crystals.
As a matter of fact, when materials engineers of electronic devices attempt to apply the results of
basic research, they often feel that these results are too basic to yield practical and profitable results in
devicefabrication. Asaconsequence,aconsiderableshareofthe developmentinthe moderntechnologyof
electronicmaterialsnowseems to resultfrom experiencespracticallyencounteredduringdevicefabrication
processes. Varioustechnological difficultieshavebeenpracticallyovercomebymeans ofsuchtrial and error.
Conversely, when scientists involved in basic research observe any defect-related phenomena which are
encounteredindevicefabricationprocesses,theyrecognize thatthe phenomenaare usuallytoocomplicated
toallowforanyimmediateself-consistentinterpretation. Mostofthe importantprocesses take placeat high
temperatureswherevarious types of reactions can occur among numerous kinds of defects and impurities
bymeans of thermal activation.
However, it isobvious that no matter how complicated the phenomena seem to be, they are just the
results ofaccumulationof elementaryprocesses whichare rate-controlledbythe behaviourofsimple types
of defects and impurities. Even when engineers practically developa new technology on the basis of their
experienceindeviceproductionprocesses, itcanbe achieved more efficientlyiftheyunderstand the under
lyingphysicalphenomena correctly. So,engineers need to deepen their knowledge of the basic properties
ofdefects. At thesame time, itseems true thatvarious phenomenaencountered inthe practical fieldoften
leadscientists to newfieldsofresearch. Phenomenareallyoccuring innatureare muchricherinvarietythan
those human brains can imagine. Actually many basic studies of seminconductor defects now being done
havetheirorigin in practical device productionprocesses.
vi
At any rate, theorganizersof the conferencebelieved thatexchange betweenscientists and engineers
inthe fieldofsemiconductordefectswasbecoming more and moreimportant,and thisidea motivatedthem
to organize this conference. Indeed, human history afterthe Industrial Revolution tells us that progress in
naturalscienceand developmentoftechnologyare mutuallydependentand inseparable.Thispropositionis
obviousalsointherathernarrowfieldofsemiconductordefects.
Over460participantsfrom 24differentcountriesattendedtheconference.Discussionat each technical
session was extremely active. The organizers of the conference were well satisfied that their intention in
organizing theconferencehad beenunderstoodbyallparticipants.
The papers submitted to the conference have all been reviewed and revised as required in prepara
tion for publication. They have beenorganized into seven sections in this book, namely, General, Silicon,
BulkCompounds,Thin Layersand Heterostructure,DislocationsandDeformation-inducedDefects,Defect
Characterization,and OrganicCrystals.Althoughtheeditorrealizes that this isbyno means a uniqueway
of classifyingthe papers, he feels that this classification to some extent reflects the present level of the
science and technologyofsemiconductormaterials. He feelsalsothattheconferenceitselfwasasignificant
experimentfor finding the most effectivewayofbringing togetherscientists involvedinbasic researchand
engineersseeking to applysuchresearch.
K.Sumino
Acknowledgement
Many colleagues from both universities and industries of Japan participated eagerly in organizing the
conference.Especially,Dr.S.Kawado,Dr.J.Matsui,Dr.N.Inoueand ProfessorK.Kojimaservedassession
chairpersonsandwere incharge oforganizingsessionsrelatedtoSilicon,BulkCompounds,ThinLayersand
Heterostructure,andOrganicCrystals,respectively.Dr.I.YonenagaandMrs.U.Onoseservedasconference
secretaries.Wethankallofthecolleaguesfortheireffortswhichmade theconferencesuccessful.Weare also
gratefulto manyJapaneseindustriesfortheirfinancialsupportof theconference.
vi
At any rate, theorganizersof the conferencebelieved thatexchange betweenscientists and engineers
inthe fieldofsemiconductordefectswasbecoming more and moreimportant,and thisidea motivatedthem
to organize this conference. Indeed, human history afterthe Industrial Revolution tells us that progress in
naturalscienceand developmentoftechnologyare mutuallydependentand inseparable.Thispropositionis
obviousalsointherathernarrowfieldofsemiconductordefects.
Over460participantsfrom 24differentcountriesattendedtheconference.Discussionat each technical
session was extremely active. The organizers of the conference were well satisfied that their intention in
organizing theconferencehad beenunderstoodbyallparticipants.
The papers submitted to the conference have all been reviewed and revised as required in prepara
tion for publication. They have beenorganized into seven sections in this book, namely, General, Silicon,
BulkCompounds,Thin Layersand Heterostructure,DislocationsandDeformation-inducedDefects,Defect
Characterization,and OrganicCrystals.Althoughtheeditorrealizes that this isbyno means a uniqueway
of classifyingthe papers, he feels that this classification to some extent reflects the present level of the
science and technologyofsemiconductormaterials. He feelsalsothattheconferenceitselfwasasignificant
experimentfor finding the most effectivewayofbringing togetherscientists involvedinbasic researchand
engineersseeking to applysuchresearch.
K.Sumino
Acknowledgement
Many colleagues from both universities and industries of Japan participated eagerly in organizing the
conference.Especially,Dr.S.Kawado,Dr.J.Matsui,Dr.N.Inoueand ProfessorK.Kojimaservedassession
chairpersonsandwere incharge oforganizingsessionsrelatedtoSilicon,BulkCompounds,ThinLayersand
Heterostructure,andOrganicCrystals,respectively.Dr.I.YonenagaandMrs.U.Onoseservedasconference
secretaries.Wethankallofthecolleaguesfortheireffortswhichmade theconferencesuccessful.Weare also
gratefulto manyJapaneseindustriesfortheirfinancialsupportof theconference.
vii
ORGANIZING COMMITIEE
K.Sumino" (ThhokuUniv.): Chairman
J. Chikawa* (KEK) K.Nakaoka(NKK)
N.Inoue" (NITLSI Lab.) Y. Nannichi(ThukubaUniv.)
S.Kawado* (Sony) 1:Nishino (KobeUniv.)
K.Kojima* (YokohamaCity Univ.) 'Ia, Ogawa (NipponMining)
J.Matsui" (NEC) 'Io.Ogawa (GakushuinUniv.)
1:Abe (Shin-EtsuHandotai) M. Ogirima (Hitachi)
S.Akai (SumitomoElectric) S.Ogura(Yokohama City)
M.Akiyama (OldElectric) N. Ohba(Yokohama City)
K.Chino (SumitomoMetalMining) M. Okada (HiroshimaUniv.)
I.Fujimoto(NHK) 1:Okano(Mitsubishi-Monsanto)
N.Fujino(KyushuElectro.Metal) I. Saito(KiharaMemo. Found.)
s.
1:Fukuda(ThhokuUniv.) S~ibata (YokohamaCity)
I.Hayashi(OTRLab.) Y. Sumino(YokohamaCity)
K.Hoshikawa (NITLSI Lab.) M.Tajima (Inst.Space&Astro. Sci.)
1:Ikoma (Univ. Thkyo) Y. Thkano (Sci.Univ. Thkyo)
K.Ishihara (MatsushitaElectric) Ma. 'Ianaka (Yokohama City)
K.Kajiyama (NipponSteelCorp.) Mt. 'Ianaka (Kihara Memo.Found.)
Y.Kashiwayanagi(FurukawaElect.) I.'Ieramoto(MatsushitaElectronics)
1:Kobayashi(Kyoto Univ.) M. Umehara (MitsubishiMetals)
S.Komiya (Fujitsu) M. Watanabe (Thshiba)
M.Kotani(GakushuinUniv.) Y.Yatsurugi(KomatsuElectro.Metals)
s.
H. Kukimoto(ThkyoInst.Thch.) Yokomatsu(YokohamaCity)
N.Mikoshiba(ThhokuUniv.) A Yusa (OlympusOpt)
(*Steeringcommitteemembers)
PROGRAM COMMITIEE
K.Sumino(ThhokuUniv.)
T Abe (Shin-EtsuHandotai) K. Kojima (YokohamaCityUniv.)
M.Akiyama (OkiElectric) S.Komiya (Fujitsu)
J.Chikawa (KEK) M. Kotani(GakushuinUniv.)
I. Fujimoto(NHK) J.Matsui (NEC)
K.Hirakawa (ThkyoUniv.) T Nishino (KobeUniv.)
K.Hoshikawa (NITLSI Lab.) K.Tada (SumitomoElectric)
N. Inoue(NITLSI Lab.) Y. Thkano (Sci.Univ. Thkyo)
Y. Kashiwayanagi(Furukawa Elect.) o.Ueda (Fujitsu)
S.Kawado (Sony) M. Umeno (OsakaUniv.)
'EKobayashi(Kyoto Univ.) M. Watanabe (Thshiba)
viii
INTERNATIONALADVISORS
H. Alexander(Univ.Koln,FRG) R.C. Newman (Univ.London, UK)
J.w. Corbett(SUNY, USA) Yu.A Ossipyan (Inst. Sol.Stat. Phys.,USSR)
A.G. CuIIis(RSRE,UK) P.M.Petroff(UCSantaBarbara,USA)
H.R. Huff (SEMATECH, USA) H.J. Queisser(MaxPlanck Inst., FRG)
N.Karl (Univ.Stuttgart,FRG) H. Richter(ForschungsbereichPhys.,GDR)
L.C.Kimerling (AT&~ USA) ARW. Willoughby(Univ.Southampton, UK)
S.Martin (Lab. Electro.Phys.,France)
FUND RAISING COMMITTEE
M.Uenohara (NEC): Chairman
T Abe (Shin-EtsuHandotai) 1:Noda (OsakaTitanium)
S.Akai (SumitomoElectric) 1:Ogawa (NipponMining)
1:Iizuka (SumitomoMetals Mining) M.Ogirima (Hitachi)
A. Ishida (NIT) O. Ohtsuki (Fujitsu)
S.Kase (NSC Electron) 1:Okano(Mitsubishi-Monsanto)
Y.Kashiwayanagi(Furukawa Elect.) 1:Suwaki(Olympus Opt.)
M.~kuchi(Sony) K.Watanabe (Mitsubishi Metals)
H. Mizuno (MatsushitaElectric) Y.Yatsurugi (KomatsuElectro.Metals)
K.Nakaoka (NKK)
The Conferencewassupportedfinanciallybythe followingcompanies:
Dowa Mining Co.,Ltd. NipponTelegraph and 'IelephoneCorporation
FUJITSU LIMITED NKKCo.
The FurukawaElectricCo.,Ltd. Oki ElectricIndustryCo.,Ltd.
HitachiLtd. Olympus OpticalCo.,Ltd.
JEOLLtd. OsakaTitaniumCo., Ltd.
KawasakiSteelCorporation SharpCorporation
KomatsuElectronicMetals Co.,Ltd. Shin-EtsuHandotaiCo.,Ltd.
MatsushitaElectricIndustrial Co., Ltd. ShowaDenkoK.K
MatsushitaElectronicsCorporation SonyCorporation
Mitsubishi MetalCorporation SumitomoElectricIndustries,Ltd.
Mitsubishi MonsantoChemical Company SumitomoMetal Mining Co.,Ltd.
NEC Corporation ThomsonJapan K.K.
NipponMining Co.,Ltd. TohokuSemiconductorCorporation
NipponSteel Corporation ThshibaCorporation
Defect Control in Semiconductors
K. Sumino (ed.)
Elsevier Science Publishers B.V. (Norlh-flolland), 1990 975
OPTICALLY-DETECTED MAGNETIC RESONANCE OF DEFECTS IN THIN LAYERS AND HETEROSTRUCTURES
OF IIl-V SEMICONDUCTORS-
T.A. KENNEDY,-. E.R. GLASER,.- B. ~OLNAR,.* and M.G. SPENCER+
••Naval Research Laboratory, Washington, DC 20375, USA
+Dept. of Electrical Engineering, Howard University, Washington, DC 20059, USA
Optically-detected magnetic resonance (ODMR) experiments which identify defects and determine
their structure and symmetry in thin layers of III-V semiconductors are presented. The photolu
minescence ODMR technique is described and illustrated with the PI anitsite in lnP. Three
examples of the applications of ODMR to thin layers are given. First,nthe PI antisite, a PI -X
antisite complex, and a third unassigned resonance have been observed in B- Rnd P-implanted Rnd
annealed lnP. Second, Ga interstitials were identified in MBE-grown Al Ga, As layers. Third,
i
the symmetry of Si-donors in Al Ga As/GaAs heterostructures was founl to-te tetragonal. Some
1
related examples and possible fu!ure-Qork are also described.
1. INTRODUCTION importance of thin layers of III-V's grew with
Electron Paramagnetic Resonance (EPR) can the development of ion-implantation and organo
reveal the atomic and electronic structure of metallic-vapor-phase epitaxy (OMVPE) and molec
point defects and small clusters in non- ular-beam epitaxy (MBE).
metallic solids. Although great progess had Three successful applications of the ODMR
been made with this technique in studying technique to the study of defects in thin III-V
defects in Si by 1975, there were few results layers and heterostructures are described in
in the III-V semiconductors.1 The reason for this paper. New results on the identity of
the difference is that while in Si the host is defects produced during the P- and B-implanta
largely free of broadening by magnetic nuclei, tion and annealing of InP are presented. For
all the nuclei of the III-V family have nuclear partially annealed samples, profiling of the
moments. This broadening destroys both resolu defects is possible due to the short diffusion
tion and sensitivity. length of the photoexcited electrons and holes.
Three developments in the years following The discovery of Ga-interstitials in MBE and
1975 have made the application of magnetic OMVPE layers of Al is recounted.
xGa1-xAs
resonance to thin layers of III-V's both pos Finally, the symmetry of donor states in
sible and important. First, EPRwas success Al~Ga1_xAs/GaAs heterostructures is described.
fully used to identify a number of intrinsic The power of ODMR to elucidate details of sym
defects (vacancies, interstitials and anti metry and electronic structure is evident in
sites) in III-V materials.2 Second, the opti these experiments.
cally-detected magnetic resonance (ODMR) tech The paper is organized as follows. After
nique was applied to semiconductors with imme this introduction, the aspects of ODMR impor
diate success in II-VI materials.3 ODMR is tant to studying thin layers are described.
much more sensitive than EPR and, when detected Sections on the InP ion-implantation, Ga:i.
on photoluminescence, is ideally suited to identification, and AlxGa1_xAs/GaAs donor
study thin layers. Third, the interest in and symmetry follow. Some remarks on the future of
.Work supported in part by the Office of Naval Research.
976
this type of work conclude the paper. intensity. Thus a microwave transition induces
an optical transition because of the existence
2. OPTICALLY-DETECTED MAGNETIC RESONANCE of a selection rule.
Among the variety of possible methods of The spectrometer used for these experiments
ODMR,3.4 the detection of spin resonance as an is shown in Figure 2. An electromagnet pro-
intensity change of a donor-acceptor pair (DAP) duces magnetic fields up to 1.1 T. Microwave
luminescence has proved most useful in the power at 24 GHz is switched by a pin diode and
study of defects in thin layers. The underly sent to a TE cavity with a large optical
o11
ing physics can be understood with the aid of window. The cavity with sample is cooled to
Figure 1. Above bandgap laser excitation pro 1.6 K by immersion in an optical cryostat.
duces electrons and holes to a depth of about Optical excitation with power density of about
0.3 ~m. The carriers are trapped by donors and 1 W/cm2 is provided by either a Kr, Ar or HeNe
acceptors, which are assumed for simplicity to laser. The luminescence is detected with
have spin of 1/2, to form the excited state either a Si photodiode or a cooled Ge photo
with spin combinations shown in the upper por- diode.
tion of the figure. Recombination of the The power of the ODMR technique can be
states with parallel spins is hindered since illustrated by taking the PI = signal in LEC
the ground state has zero spin. If the spin grown InP:Zn as an example.s A broad, two-line
lattice relaxation is slow, the populations of spectrum is observed on a deep photolumines
the parallel-aligned states build up. Micro cence band (See Figure 3). The magnetic reso
wave-induced resonance of the donor (or accep nance properties are a g-value (2.00) near the
tor) transfers the relative spin from parallel free electron position and a strong, isotropic
to anti-parallel resulting in a rapid recombi hyperfine interaction (A = 100 mT) from a spin
nation which increases the photoluminescence
D° AO
-.....----+1/2 +1/2
~--,.--- -1/2 +1/2
SIGNAL
_--r-+---+1/2 -1/2
AVERAGER
-1/2 - 1/2
-.1-_+--+-__
rvv
PL
Kr+ LASER
FIGURE 1
Spin states for a donor-acceptor pair. Donor FIGURE 2
magnetic resonance transfers spins to the ODMR spectrometer. Often the 0.25 m spectro
anti-parallel excited states which decay rap meter is replaced by a filter for greater
idly to the ground state. throughput.
977
3. ISOELECTRONIC IMPLANTATION OF InP
z InP:Zn
Implantation-doping involves the choice of a
~ 2-74-H
:::::> starting material, the implantation, and
-.J
z subsequent annealing to· activate the dopants
and to reduce the damage produced by the
W
<.? implantation. Be diffuses outside the desired
Z
<{ region upon annealing. Co-implantation of P or
I
U As with Be is known to hinder the redistribu
0.8 0.9 1.0 tion of the highly mobile Be-atoms. In this
MAGNETIC FIELD (T) work, ODMR has been applied to P- and B-implan
tation of InP in order to identify the point
defects occurring at each processing step.
FIGURE 3
The samples were prepared starting with
Pxn ODMR. The two-line spectrum results from
the strong 31p central hyperfine interaction. LEC-grown, Fe-doped InP wafers. Multi-energy
implantations were used to produce square
profiles. For example, a P-implantation
1/2 nucleus. These features can be uniquely
sequence was 3xl013 cm-2 at 380 keV, 2x1013
assigned to the Pxn antisite defect first
cm-2 at 240 keV, and 1.2x1013 cm-2 at 130 keV.
observed using EPR.6
This sequence results in a P-concentration of
The deep luminescence has a sublinear depen
about 1018 cm-3 to a depth of 6000 A. Anneals
dence on excitation power characteristic of DAP
were carried out with the sample in close pro
recombination. Because of the Zn-doping of the
ximity to oxidized Si at a temperature of 600
starting materials, the optical process is
or 750°C for 15 minutes.
likely to be
ODMR experiments were performed on samples
Pxn+ + ZnO ~ Pxn++ + Zn- + photon,
with different processing. Three distinct
where the paramagnetic state of the antisite is
spectra were observed.
one-plus since it is a double donor and the
A P-implanted sample with a 600°C anneal
spin 3/2 character of the acceptor can also be
exhibited different spectra depending on the
taken into account.3 Spectral dependence of
wavelength of the laser (See Figure 4). Blue
the ODMR shows that the transition is around
excitation produced a negative two-line spec
0.8 eV, which gives the optical energy of the
trum while red excitation gave a positive
Pxn+/Pxn++ level from the Zn acceptor level.
single line. Thus the carrier-diffusion
Thus the ODMR provides a measure of the energy
lengths in the implanted region of this sample
level of the antisite in addition to its iden
are short enough that changing the energy of
tity.
above-gap excitation allows a profiling of the
The InP:Zn starting material has a hole den
defects. The two-line spectrum has resonance
sity of about 1016 cm-3. The antisite concen
parameters identical to those of the Pxn anti
tration is deduced to be greater than 2x101S
site described in the previous section. Thus
cm-3 from a complete analysis of the ODMR.7
antisites are found in this implanted and
Noting the signal-to-noise ratio of the PXn
annealed material. The single line seen with
ODMR, these concentrations seem to be about
red excitation has a g-value of 2.00 ± 0.01 and
optimal for the technique. Thus the overall
a linewidth of 35 mT. Without a resolved hyp
sensitivity in a favorable case is better than
erfine interaction or other information, it is
a part-per-million with respect to the host
difficult to make a definite assignment of this
lattice.
spectrum. It could be due to a vacancy, the lnp