APPLIED MATERIALS EXHIBIT 1042 (Part 2 of 3)
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`Appendix 1029-B
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`Appendix 1029-C
`Appendix 1029-C
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`FMTFMT SE
`LDRLDR nas a22002417a 4500
`00001
`014532647
`00003
`Uk
`00005
`20200701010345.0
`00007
`ta
`00008
`840320c19629999xxuer p 0 a0eng
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`02 00220 |a 0003-6951
`04040
`|a Uk |c Uk |d Uk
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`08 0408204 |a 621 |2 21
`08084
`|a PQ 00 |2 blsrissc
`
`24 0024500 |a Applied physics letters.
`26260
`|a New York : |b American Institute of Physics, |c 1962-
`30300
`|a v. ; |c 27 cm.
`31310
`|a Fortnightly
`33336
`|a text |2 rdacontent
`33337
`|a unmediated |2 rdamedia
`33338
`|a volume |2 rdacarrier
`59595
`|a SEE ALSO SERIAL RECORDS KCS SE.
`55555
`|a Cumulative index.
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`71 27102 |a American Institute of Physics.
`94945
`|a APPLIED PHYSICS LETTERS
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`85 7185271 |a British Library |b STI |k (P) |h PQ 00 |m -E(12) |2 blsrissc
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`86 0866 0 |a Volume 1(1962)- ; Deficient: v. 62, no.27, 1993
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`85 4985249 |a British Library |b DSC |j 1576.400000
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`86 0866 0 |a Volume 1 (1962)- |z UKRR Retained Title
`SYSYS 014532647
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`Accessibility Terms of use © The British Library Board
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`P2
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`p //p moca b uk/ /?fu c=d ec & oca _base=PR MO&doc_ umbe =014532647&fo ma =001&co _ g=e g
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`Page 1 of 1
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`Page 1 of 1
`Appendix 1029-C
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`Appendix 1029-D
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`Early Citations to Dogheche
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`y
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`c!2000 The Japan Society of Applied Physics
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`Deposition of AlN Thin Films with Cubic Crystal Structures on Silicon Substrates
`at Room Temperature
`Zhong-Min REN, Yong-Feng LU, Yeow-Whatt GOH, Tow-Chong CHONG, Mei-Ling NG1, Jian-Ping WANG1,
`Boon-Aik CHEONG1 and Yun-Fook LIEW1
`Laser Microprocessing Laboratory, Department of Electrical Engineering and Data Storage Institute, National University of Singapore,
`10 Kent Ridge Crescent, Singapore 119260
`1Data Storage Institute, 5 Engineering Drive 1, Singapore 117608
`(Received September 20, 1999 accepted for publication March 6, 2000)
`Cubic AlN thin films were deposited at room temperature by nitrogen-ion-assisted pulsed laser ablation of a hexagonal
`AlN target. The full-width at half maximum (FWHM) of the X-ray diffraction peak in the θ ∼ 2θ scan can reach a value of
`0.27degrees. In the Raman spectroscopy measurement, a new peak at 2333cm−1 originating from cubic AlN polycrystalline
`was observed. Nitrogen ions not only effectively promote the formation of stable Al–N bonds but also improve the crystal
`properties of the deposited thin films. A nitrogen ion energy of 400eV is proposed for the thin-film deposition.
`KEYWORDS: AlN pulsed laser deposition thin films cubic crystalline Raman spectroscopy XRD XPS
`
`produced by a 1-cm Kaufman-type ion source irradiated the
`substrate surface to assist the deposition. The ion flux was
`set at 1mA/cm2. The deposition rate was 0.1 nm/s as mea-
`sured by a microbalance mounted on the substrate. Si(100)
`wafers were used as substrates. The deposited thin films have
`thicknesses of around 200 ∼ 300nm. After deposition, X-ray
`diffraction (XRD), Raman spectroscopy and X-ray photoelec-
`tron spectroscopy (XPS) measurements were carried out to
`characterize the crystal, chemical binding and compositional
`properties of the deposited thin films.
`Figure 1 shows the XRD θ ∼ 2θ spectrum of an AlN
`thin film deposited by 400eV nitrogen ion bombardment.
`The measurements were performed on a Philips X’Pert-MRD
`system. Cu Kα irradiation with an average wavelength of
`1.5418Å was used as an X-ray source in the diffraction mea-
`surements. In the spectrum, besides the Si(200) and Si(400)
`diffraction peaks, there are four distinct peaks at 2θ = 38.5,
`44.7, 65.3 and 78.3, corresponding respectively to orienta-
`tions of (111), (200), (220) and (311) of the cubic AlN crys-
`tal22) although the crystal structure of the target is hexagonal.
`Hexagonal structures are not detected from Fig. 1 when the
`resolution of the MRD system is taken into account. The
`FWHM of the AlN(200) peak is about 0.27degrees, lower
`than that of films deposited by plasma source molecular beam
`epitaxy.6) The formation of AlN cubic structures on Si(100)
`
`Si(400)
`
`AlN(311)
`
`AlN(220)
`
`AlN(111)
`
`AlN(200)
`
`Si(200)
`
`20
`
`Intensity(arb.unit)
`
`40
`
`60
`
`80
`
`2
`Fig. 1. XRD θ ∼ 2θ spectrum of a AlN thin film deposited by KrF laser
`l
`400 V
`T
`
`
`
`Recently there has been tremendous interest in the synthe-
`sis of AlN thin film due to its wide band gap and other desir-
`able properties of thermal conductivity, electrical resistivity
`(dielectric constant) and acoustic properties.1–3) Many exper-
`imental methods have been used to deposit AlN thin films, in-
`cluding metalorganic chemical vapor deposition (MOCVD),4)
`plasma-assisted molecular beam epitaxy (PAMBE),5–7) RF re-
`active magnetron sputtering,8–11) ion-assisted chemical vapor
`deposition12) and pulsed laser deposition (PLD).13–19) A num-
`ber of new theoretical works have also been published re-
`cently.20 21) Almost all the deposition methods require high
`substrate temperatures (normally above 600◦C) although the
`defects both inside the thin films and at the interface between
`the substrate and the thin film cannot be avoided.6) To date, all
`the deposited AlN thin films have hexagonal structures with a
`highly textured orientation of (0001) on sapphire, silicon and
`glass substrates.3 6 7 9 10 18 19)
`In our study, we attempted to use pulsed laser ablation to
`deposit AlN thin films on silicon substrates at room tempera-
`ture. PLD has been proven to be suitable to fabricate AlN thin
`films on silicon and sapphire substrates. Compared with other
`methods, PLD has two main aspects of advantages. First, it
`can faithfully transfer the target material to the substrate sur-
`face without an obvious change in the compositional ratios of
`compound materials. Second, the energetic radicals in the ab-
`lated plume are beneficial to the formation of ideal crystalline
`structures in the deposited thin films. In our experiments, the
`ion-assisted PLD combines the advantages of ion bombard-
`ment and laser ablation. With this approach, we can indepen-
`dently control the energies of the AlN radicals in the ablated
`plasma and the nitrogen ions in the ion beam to improve the
`quality of the deposited thin films. Moreover, the nitrogen
`ions can also compensate for the loss of nitrogen species in
`the ablation process.
`In the experiment, we used a KrF excimer laser at a wave-
`length of 248nm to ablate an AlN target. The deposition was
`carried out in a PLD system with a background vacuum of
`1×10−6 Torr. An AlN target with a standard hexagonal crys-
`tal structure and a purity of 99.995% was mounted on a target
`holder that was rotated by an external motor. The target was
`placed 2cm away from the substrate surface. The laser pulse
`duration was 30ns The laser fluence was set at 2J cm−2 with
`
`Page 163 of 304
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`L424
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`Jpn. J. Appl. Phys. Vol. 39 (2000) Pt. 2, No. 5A
`
`Z.-M. REN et al.
`
`For the thin films deposited without nitrogen ions, no obvi-
`ous Raman peak can be observed, implying that the nitrogen
`ions can effectively improve the crystal property of the thin
`film. Although it induces defects, ion implantation can possi-
`bly benefit the growth of the crystal grains. The energetic ni-
`trogen ions can enhance the chemical combinations between
`Al and N atoms and thus lead to more and larger AlN crystal
`grains.
`The chemical binding and compositional properties of
`the AlN thin films were analyzed by XPS measurements.
`Figure 3 shows the XPS Al 2p spectra for three AlN thin films
`deposited with different ion energies. The binding energy of
`the Al 2p electron increases slightly with increasing nitrogen
`ion energy from 100 to 400eV, due to the fact that the ener-
`getic nitrogen ions can effectively react with Al atoms to form
`AlN compounds. The binding energy of the Al 2p electron in
`the AlN compound is higher than that in atomic Al due to the
`weak shielding effect. Higher ion energy can lead to the for-
`
`Al 2p
`100 eV
`
`200 eV
`
`400 eV
`
`Intensity(arb.unit)
`
`Intensity(arb.unit)
`
`Intensity(arb.unit)
`
`70
`
`82
`
`80
`78
`76
`74
`72
`Binding Energy (eV)
`Fig. 3. XPS Al 2p spectra for AlN thin films deposited under different ni-
`trogen ion energies of 100, 200, and 400eV. The laser fluence is 2J/cm2.
`The ion flux is 1mA/cm2.
`
`(a)
`
`400 eV N+
`
`N-Al
`
`N 1s
`
`N-N
`
`398
`
`(b)
`
`398
`
`406
`404
`402
`400
`Binding Energy (eV)
`N2 atmosphere
`N-N
`
`408
`
`N 1s
`
`N-Al
`
`406
`404
`402
`400
`Binding Energy (eV)
`f AlN
`fil
`
`408
`
`400 V N+
`
`F
`
`4 XPS N
`
`
`
`substrates is different from most other research results in
`which hexagonal AlN structures are formed.15 18 19) In the
`detailed studies6 7) of the microstructures and initial stages
`of thin-film deposition, AlN films have an initial amorphous
`region at the interface between the substrate and the thin
`film, followed by c-axis-oriented columnar grains. Substrate
`temperatures higher than 600◦C can significantly reduce the
`amorphous regions at the interface and promote to grow AlN
`with hexagonal (0001) orientation. However, in our deposi-
`tion, since substrate temperature is low, the c-axis-orientated
`growth of hexagonal AlN is not preferred. Instead, another
`metastable state of the crystal AlN with a cubic structure was
`obtained from our deposition, although the hexagonal AlN is
`possibly in a much stable state. The PLD at room temperature
`with the assistance of ion-beam coprocessing leads to mainly
`(111)-oriented c-AlN thin films.
`We also deposited AlN thin films without nitrogen ion
`bombardment. These deposited thin films exhibit no XRD
`peaks, indicating only amorphous structures. The result re-
`veals the important role of nitrogen ions in the synthesis of
`AlN thin films with cubic crystal structures. Moreover, ni-
`trogen ion energy lower than 400eV leads to weaker and
`broader XRD peaks. Therefore, nitrogen ions with an en-
`ergy of 400eV can effectively assist in the formation of cu-
`bic crystalline structures in the deposited thin films. When
`the nitrogen ion energy exceeds 400eV, the deposition will
`be impeded due to the resputtering effect caused by the ion
`bombardment.
`Figure 2 shows the Raman spectra of the AlN thin films de-
`posited under the different nitrogen ion energies of 100, 200,
`and 400eV. Similar to most other research findings,19 23 24)
`the Raman peaks of the AlN thin films are weak. The peaks at
`618, 670 and 826cm−1 reflect the phonon modes of E1(TO),
`A1(LO) and E1(LO), respectively,23 24) indicating the crystal
`structures of the deposited thin films. The intensities of these
`Raman peaks increase with increasing nitrogen ion energy
`from 100 to 400eV, implying that the nitrogen ion energy of
`400eV is optimal for the deposition of crystal AlN thin films,
`in agreement with the XRD analysis result. Besides these
`peaks, there is a sharp and strong peak at 2333cm−1 which is
`observed for the first time. The intensity of this peak also in-
`creases with the nitrogen ion energy and reaches a maximum
`when the ion energy increases to 400eV. Therefore, this peak
`must originate from the cubic structure of AlN.
`
`Intensity(arb.unit)
`
`400 eV
`
`200 eV
`
`2333
`
`826
`670
`618
`
`Si
`
`100 eV
`2700
`
`Si
`1800
`900
`Raman Shift (cm-1)
`Fig. 2. Raman spectra of AlN thin films deposited under different nitrogen
`f 00 200
`400 V T l
`fl
`2J/
`2 T
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`Page 164 of 304
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`

`

`Jpn. J. Appl. Phys. Vb]. 39 (2000) Pt. 2, No. 5A
`
`Z.-M. man et a1.
`
`L425
`
`mation of more Al—N bonds and therefore an increase in the
`
`Al 2p binding energy.
`Figure 4 shows two XPS N ls spectra for AlN thin films
`deposited with and without the assistance of nitrogen ions,
`respectively. It is evident that, in the thin films, there are two
`nitrogen statuses related to N—N and N—Al bonds. The differ—
`ence between these two spectra in Fig. 4 is quite obvious. The
`thin film deposited in the N2 atmosphere has a very strong N—
`N peak whereas that deposited with 400 eV N+ implantation
`has a strong N—Al peak. The nitrogen ions in the deposition
`promote the formation of Al—N bonds and reduce the density
`of N—N bonds. Therefore, nitrogen ions with an energy of
`about 400 eV are beneficial to the synthesis of AlN thin films,
`in agreement with the above XRD and Raman results.
`The N/Al atomic ratio of the deposited thin films is in the
`range of 0.90 to 1.12. The N/Al atomic ratio is evaluated us-
`ing N : A1 = AN/SN : Am/SAI, where AN and Am are the
`areas under the N15 and A12p peaks, and the constants SN
`and SM are the sensitivity factors of nitrogen and aluminum,
`respectively. The ratio is slightly lower than 1.0 when the
`ion energy is 400eV, due to the resputtering effect. Depo-
`sition with ion-beam bombardment is a nonequilibrium pro-
`cess. The low substrate temperature does not provide any en-
`ergy for the equilibrium growth of an AlN crystal. The de-
`position is accomplished by energetic ions with energies of
`about 400eV. Therefore, the crystalline growth mechanism
`is quite different from other deposition methods where high
`substrate temperatures and low ion energies are employed.
`Hexagonal AlN thin films were deposited by PLD at substrate
`temperatures above 675°C15-13) and by RF magnetic sputter-
`ing and molecular beam epitaxy with substrate temperatures
`higher than 400°C,6-9' 10-19) even on silicon°*9'18) and glasslo)
`substrates. However, in our deposition, the c-axis-oriented
`growth which leads to the hexagonal structure is not possible
`due to the low substrate temperature. In contrast, the ener-
`getic ions promote the formation of another metastable state
`of crystal A1N with a cubic structure. Therefore, the use of
`nitrogen ions with the energy of about 400 eV plays an im—
`portant role in the formation of a cubic AlN crystal.
`In summary, AlN thin films were deposited at room tem—
`perature on Si( 100) substrates by nitrogen-ion—assisted pulsed
`laser ablation of a hexagonal AlN target. The thin films
`have cubic crystal structures with orientations of (l l l), (200),
`(220) and (311), diflerent from most other research results in
`which hexagonal AlN was obtained. Energetic nitrogen ion
`implantation plays an important role in the formation of a cu—
`
`bic AlN crystal. Anion energy of 400 eV was determined to
`be appropriate for the deposition process.
`
`Acknowledgements
`The authors would like to thank Miss. H. L. Koh for her
`technical assistance in this research.
`
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`

`

`JOURNAL OF APPLIED PHYSICS
`VOLUME 88, NUMBER 12
`15 DECEMBER 2000
`Room temperature synthesis of c-AlN thin films by nitrogen-ion-assisted
`pulsed laser deposition
`Z. M. Ren, Y. F. Lu,a) and H. Q. Ni
`Laser Microprocessing Laboratory, Department of Electrical Engineering and Data Storage Institute,
`National University of Singapore, 10 Kent Ridge Crescent, 119260 Singapore
`T. Y. F. Liew, B. A. Cheong, S. K. Chow, M. L. Ng, and J. P. Wang
`Data Storage Institute, 5 Engineering Drive 1, 117608 Singapore
`共Received 10 April 2000; accepted for publication 28 August 2000兲
`Cubic aluminum nitride (c-AlN) thin films have been deposited at room temperature on silicon
`substrates by nitrogen-ion-assisted pulsed laser ablation of a hexagonal AlN target. The deposited
`thin films exhibit good crystal properties with sharp x-ray diffraction peaks. The influences of the
`nitrogen ion energy on the morphological, compositional, and electronic properties of the AlN thin
`films have been studied. The nitrogen ions can effectively promote the formation of Al–N bonds
`and improve the crystal properties of the deposited thin films. A nitrogen ion energy of 400 eV is
`proposed to deposit high quality c-AlN thin films. © 2000 American Institute of Physics.
`关S0021-8979共00兲03623-9兴
`
`I. INTRODUCTION
`Aluminum nitride is increasingly receiving high interest
`from the material research community due to its wide band
`gap, high thermal conductivity, high electrical resistivity 共di-
`electric constant兲, and good acoustic properties.1–3 Many re-
`search groups are exploring the synthesis of high quality
`AlN. Some experimental methods have been used to deposit
`AlN thin films,
`including metalorganic chemical vapor
`deposition,4 plasma-assisted molecular beam epitaxy,5–7 rf
`reactive magnetron sputtering,8–11 ion-assisted chemical va-
`por deposition12 and pulsed laser deposition 共PLD兲.13–19
`Most of the deposition methods require high substrate tem-
`peratures 共normally above 800 C兲 although the defects, both
`in the thin films and at the interface between the substrate
`and the thin film, cannot be avoided.6 Such a high substrate
`temperature is undesirable for semiconductor industries and,
`therefore, impedes the practical applications of the AlN ma-
`terial. To date, most of the deposited AlN thin films have
`hexagonal structures with a highly textured orientation of
`共0001兲 on sapphire, silicon, and glass substrates.
`In this study, PLD was used to deposit AlN thin films on
`silicon substrates at room temperature. PLD has been proven
`to be suitable to fabricate AlN thin films on silicon and sap-
`phire substrates.13–19
`In the experiments, nitrogen-ion-
`assisted PLD combines the advantages of both PLD and ion
`bombardment. With this technology, we can independently
`control the energy of the AlN radicals in the ablated plasma
`as well as the nitrogen ions in the ion beam to determine the
`optimal conditions to obtain high quality thin films. More-
`over, the nitrogen ion implantation can also compensate for
`the loss of nitrogen species in the ablation process.
`
`a兲Electronic mail: eleluyf@nus edu sg
`
`II. EXPERIMENT
`In the experimental set up, as shown in Fig. 1, a KrF
`excimer laser at a wavelength of 248 nm was used as a light
`source to ablate an AlN target. The deposition was carried
`out on a PLD system with a background vacuum of 1
`⫻10⫺6 Torr. The AlN target with a hexagonal crystal struc-
`ture and a purity of 99.995% was mounted on a target holder
`that was rotated by an external motor. The target was placed
`2 cm away from the substrate surface. The laser pulse dura-
`tion was 30 ns. The laser fluence at the target was around 2
`Jcm⫺2 with a repetition rate of 10 Hz. The laser spot size on
`the target surface was about 5 mm2. A nitrogen ion beam
`which was produced by a 1 cm Kaufman-type ion source
`irradiated the substrate surface spontaneously to assist the
`deposition. The ion flux was adjusted in a range of 1–2
`mA/cm2. The energetic nitrogen ions traveled 10 cm distance
`before arriving on the substrate. The incident angle of the ion
`beam was 45 . By monitoring the microbalance mounted on
`the substrate, the deposition rate was set at ⭐1 Å/s by ad-
`justing the ion beam flux. Si共100兲 wafers were used as sub-
`strates. Before deposition, the polished Si 共100兲 substrates
`were cleaned by acetone in an ultrasonic bath.
`X-ray diffraction 共XRD兲, x-ray photoelectron spectros-
`copy 共XPS兲, Raman spectroscopy, and Fourier transfer infra-
`red 共FTIR兲 spectroscopy measurements were carried out to
`characterize the crystal, compositional, and electronic prop-
`erties of the deposited thin films. XRD measurements were
`performed on a Philips X’Pert-MRD system. Cu K␣irradia-
`tion with an average wavelength of 1.5418 Å was used as the
`x-ray source in the diffraction measurements. XPS measure-
`ments were carried out using a Mg K␣ 1253.6 eV x-ray
`source with power of 300 W. Raman spectroscopy measure-
`ments were done on a Renishaw Raman Scope. FTIR mea-
`surements were carried out by a micro-FTIR spectrometer
`共model FTS 6000 by BIO-RAD兲.
`
`0021 8979/2000/88(12)/7346/5/$17 00
`
`7346
`
`© 2000 American nstitute of Physics
`
`Page 167 of 304
`
`

`

`J Appl Phys Vol 88 No 12 15 December 2000
`
`Ren etal.
`
`7347
`
`FIG 1 Experimental setup In a vacuum chamber, a KrF excimer laser
`beam is focused to ablate a ceramic AlN target which is rotated by an
`external motor A N⫹ beam is bombarding on the substrate surface simul-
`taneously to assist the AlN deposition A microbalance where Si substrates
`are attached is use to monitor the deposition rate the AlN thin films
`
`III. RESULTS AND DISCUSSIONS
`Figure 2 shows the XRD ␪–2␪spectrum of an AlN thin
`film deposited with 400 eV N⫹ bombardment. In the spec-
`trum, besides the Si共200兲 and Si共400兲 diffraction peaks, there
`are four obvious peaks at 2␪⫽38.37 , 44.74 , 65.58 , and
`78.09 , corresponding to orientations of 共111兲, 共200兲, 共220兲,
`and 共311兲, respectively, of the c-AlN crystalline with rock-
`salt structure20 though the crystal structure of the target is
`hexagonal. The formation of cubic crystal structures of AlN
`on Si共100兲 substrates is unique compared with most of other
`works where hexagonal crystal structures were formed.15 18 19
`In other studies6 7 of the microstrucrures and initial stages of
`thin film deposition, AlN films formed an initial amorphous
`region at the interface between the substrate and the thin
`film, followed by c-axis oriented columnar grains. Substrate
`temperature above 600 C can significantly reduce the amor-
`phous region at the interface and promote the hexagonal
`共0001兲 orientation of AlN. However, in this study, since high
`substrate temperature was not used, the c-axis orientated
`growth of hexagonal AlN was not promoted. Instead, another
`metastable state of cubic crystalline AlN was obtained, al-
`though the hexagonal AlN crystal is possibly more stable due
`to its close packed stacking.
`In the experiments, AlN thin films were also deposited
`without N⫹ bombardment. The deposited thin films exhibit
`no XRD peaks, indicating amorphous structures. This result
`
`FIG 2 XRD ␪–2␪spectrum of an AlN thin film deposited by KrF laser
`ablation with 400 eV N⫹ bombardment at room temperature The laser
`fluence is 2 J/cm2
`
`FIG 3 Optical microscopic images of AlN thin films deposited with dif-
`ferent N⫹ energies: 共a兲 0 共in N2 atmosphere with a pressure of 100 mTorr兲,
`共b兲 100, 共c兲 200, and 共d兲 400 eV
`
`demonstrates the important role of the nitrogen ions in the
`synthesis of AlN thin films with cubic crystal structures.
`Moreover, N⫹ energies lower than 400 eV lead to weaker
`and broader XRD peaks. Therefore, the nitrogen ions with
`the energy of 400 eV can effectively assist the formation of
`cubic crystalline in the deposited thin films. When nitrogen
`ion energy exceeds 400 eV, the deposition will be impeded
`due to the resputtering effect caused by the ion bombard-
`ment.
`The deposition with the assistance of ion-beam bom-
`bardment is a nonequilibrium process. The low substrate
`temperature does not provide any energy for the equilibrium
`growth of crystalline AlN. The deposition is accomplished
`with energetic ions of hundreds eV. Therefore, the crystalline
`growth mechanism is quite different from other deposition
`methods where high substrate temperatures and low ion en-
`ergies were employed. Hexagonal AlN thin films were de-
`posited by PLD at
`substrate temperature higher
`than
`675 C15 18 and by rf magnetic sputtering and molecular
`beam epitaxy with substrate temperature higher
`than
`400 C6 9 10 19 on silicon6 9 18 and glass substrates.10 However,
`in this study, the c-axis oriented growth which leads to hex-
`agonal structures is not possible due to the lack of high sub-
`strate temperatures. On the contrary, the energetic nitrogen
`ions of 400 eV promote the formation of cubic AlN crystals.
`Figures 3共a兲–3共d兲 present the surface morphologies of
`the AlN thin