18.

High - Density Recording on Air - Stabilized Flexible Optical Disk

Nobuaki Onagi, Yasutomo Aman, Shozo Murata, Jyunichi Kitabayashi, Kazuhiro Ogawa,
Keisuke Uchida( Ricoh Company Ltd.)
Abstract
Using high NA lens is important for highly density recording. But its working distance anddefocus margin is small. To overcome the problem, a flexible substrate disk and air stabilizer
was used.

The stabilizer is placed on a substrate side of a flexible disk, with an optical pickup

set on the opposite side of the stabilizer. This system reduces disk axial runout by the stabilizer.
Therefore the stabilizer does not cause scratching of the disk surface on the pickup side. If thedisk rotates in closing the stabilizer and disk, airflow is generated between the stabilizer and thedisk surface. This airflow reduces axial runout of the disk. This new system showed small axial
runout, so this system could record signal which density was 0.13?m/bit. This time, we report
new stabilizer system. This is more suitable than only one point stabilizer system for reduction
characteristic of axial runout.

1.

Crystal structure and its thermal behavior of Ge8Sb2Te11 (GeTe:Sb2Te3 =8:1), a suitable material for high-speed and high-density phase-change recording
Toshiyuki Matsunaga* and Noboru Yamada(* Matsushita Technoresearch, Inc. Matsushita Electric Industrial Co., Ltd. )Abstract
In Blu-ray discs, on which as much as 50 GB of information can be recorded by blue-violet
laser, the thickness of recording film is now only several nanometers to realize higher densityand faster recording. For Blu-ray disc, such GeTe-rich pseudobinary compounds asGe8Sb2Te11 (GeTe:Sb2Te3 = 8:1) are adopted to enable sufficient optical changes between theamorphous and crystalline states of the film, which are transparent and opaque to the light,respectively. We investigated in detail the crystal structure and its temperature dependency in
Ge8Sb2Te11 by powder X-ray diffraction using a synchrotron radiation facility and examinedthe chemical bonding nature by molecular orbital calculation, which revealed followings.
Erased (laser-crystallized) area of the film is an aggregate of microcrystallites. In thesecrystallites, an enormous number of free (conduction) electrons are present, which makes it
opaque to light at visible and near-visible wavelengths. The density of free electrons rises withincreased GeTe content, emphasizing the difference in optical properties between theamorphous and crystalline phases. This is presumed to enable sufficient optical changes even invery thin films only a few nanometers thick used for Blu-ray discs.

2,

Structural investigation of Sb-Te sputtered films

Kouichi Kifune1, Yoshiki Kubota1, Toshiyuki Matsunaga2, and Noboru Yamada3(1Osaka Women’s University, 2Matsushita Technoresearch Inc., 3Matsushita Electric IndustrialCo., Ltd.)
Abstract
X-ray structure analysis was carried out about Sb-Te sputtered films with different compositions.
It turned out that the structure of every specimen is based on the cubic close-packed structure,
and a stacking period changes with composition.

3.

Crystal Structure and Feasibility for 16x DVD-Rewritable Media of In-Sb Phase-Change

Material
Hiroshi Miura1), Eiko Suzuki1), Hiroko Tashiro1), Makoto Harigaya1), Kazunori Ito1), Noriyuki
Iwata2), Atsuyuki Watada2), Katsuhiko Tani2), Yoshiyuki Nakata3), and Shuichi Emura4)( 1)RICOH COMPANY, Ltd., 3) Iwaki Meisei University, 4) Osaka University)
Abstract
Recently, several Sb-based materials, Ga-Sb, Ge-Sb and In-Sb, have been proposed asphase-change layer of high-speed rewritable media. In-Sb forms the cubic crystal structure andhas particularly fast crystallization speed compared with the other materials, which form
hexagonal crystal structure similar to Sb. However, this material segregates InSb (In:Sb=1:1) at
the composition around eutectic. This causes significant degradation of the reflectivity ofphase-change media after a thermal aging test. Increasing Sb concentration higher than 80% iseffective to suppress the degradation and change the crystal structure of In-Sb from cubic tohexagonal. At In18Sb82, although the main crystal structure remained cubic, the degradation ofreflectivity was suppressed less than 2% and the maximum erase velocity was 56 m/s. Jitteraround 12% was obtained as the overwriting characteristics at 56m/s (DVD16X) with thiscomposition. It suggests that this material can be applied to 16x DVD rewritable media.

4.

Optical property analysis for readout mechanism evaluation of super-RENS disk

Takashi Nakano(National Institute of Advanced Industrial Science and Technology (AIST))
Abstract
The optical properties of super-resolution signals in the Fourier-plane of focus showedreadout-power dependence. The properties could be explained by a shift of aspecial-temperature region in a laser spot under a ferroelectric catastrophe model.

5.

Diffractive electro-magnetic photonics for physical description of optically nonlinear andanisotropic media
MyoungJune Kim, HakCheol XueZhe Li, SangYoul Kim(Ajou University)
Abstract
Using Huygens -Fresnel principle, Simulator of disk preformat and phase change multiplayer
was programmed. Focusing of light is approximated with Fourier transformation. As an
important effect of focusing, nonlinear deviation of complex refraction index was widelysurveyed. Maxwell-Jones Matrix and Jones-Fresnel Reflection & Transmission Coefficient wasderived from complex refractive index function matrix(CRIFM), and analyzed the effect of
nonlinear component in optical disk reproducing signal of Optical Storage-Recording Materials.

6.

Electric properties of thin GeSbTe and AgInSbTe films by annealing

You Yina, Hayato Soneb, and Sumio Hosakab(aSatellite Venture Business Laboratory, bDepartment Nano-material Systems, GunmaUniversity)
Abstract
We have studied electric properties of 20nm and 50nm-thick Ge2Sb2Te5 and AgInSbTe films fornonvolatile memory cell. The thin films were prepared as a film sample and a device sample
after annealing at various temperatures from 140 oC to 415 oC. Large dynamic range ofchanging resistance for film samples is confirmed but the device sample has narrow range,
which is not essential. We discuss on the resistance changes of some samples for miniaturizing
the phase change memory element.

7.

Phase Change RAM-A High performance Nonvolatile Memory Technology for Stand

Alone and Embedded Applications
Hideki Horii(Samsung Electronics Co., Ltd.)

8.

Phase-change optical disk came from behind and won!

Isao Satoh( Matsushita Electric Industrial Co., Ltd.)
Abstract
Phase-change technology has been dominating the rewritable optical discs like CD-RW, DVD,BD and HD DVD. It could be a big surprise when we came back to the end of the 1980s.
Author has engaged in phase-change optical disc technology from 1980. He was an eyewitness
and also one of the key figures realized these achievements. In this paper, the history of opticaldisc media is reviewed and the universal knowledge to gain the supremacy of formatʼs wars.
It was really interesting, challenging, and energy-consuming experiences.

9.

Theoretical and Experimental Study on Evaluation of the Initialization Conditions ofPhase-Change Optical Discs: Proposal of Pulse Initialization
Toshimichi Shintani a) , Hiroyuki Minemura a) , Yoshiaki Ogino b) , Noriyuki Ishikawa b) andEiji Sahota b)( a) Hitachi, Ltd. b) Hitachi Computer Peripherals Co., Ltd.)
Abstract
The relationship between the initialization conditions and the overwrite characteristics wasinvestigated for phase-change optical discs. The results show that the initialized states can be
categorized into insufficient, sufficient and damaged states. Initialization with low velocities
lowers the margin of the sufficient state. Pulse initialization with a low velocity resulted in goodoverwrite characteristics.

10.

Observation of Low reflectivity Crystallized State of Phase Change Optical Disc

Shinji Shirasaka a), Yoshiharu Tami a), Yoshiaki Ogino a), Eiji Sahota a)
Shintaniand Toshimichib)(a)Hitachi Computer Peripherals Co.,Ltd, b)Hitachi, Ltd.)
Abstract
Two type of crystallized states with Phase change optical disc exist at the initializing process.
The difference between each of state is not only the reflectivity but initial jitter of overwrite. Sofocus on the erase power of overwrite, observe the specification of low reflectivity crystallizedstate.

11.

Blu-ray Disc Mastering Using deep-UV Laser Beam Recorder

Takashi Ohgo, Tetsuya kondo, Eiji Nakagawa, Takashi Tsurukubo, and Toshiya Saito(Victor Company of Japan, Ltd.)
AbstractThe authors have developed a novel laser beam mastering system using a deep-UV laser for ahigh-density optical disc. Technologies of direct focus servo, recording signal compensation andhigh contrast photoresist material are applied in the laser beam recorder. The evaluation results
for the 25-Gbyte-capacity Blu-ray ROM (BD-ROM) disc revealed that uniform recording andreasonable jitter can be realized. Furthermore, the evaluation of the Blu-ray Rewritable(BD-RE) disc indicated the wide process margin and confirmed that the disc was practical forapplication in the market. Although the optics consists of conventional 266 nm laser withnumerical aperture (NA) 0.9 objective lens, it successfully realizes both BD-ROM and BD-REmastering.

12.

TeOx-based film as Heat-mode type Photoresist

Eiichi Ito*, Yuko Kawaguchi, Morio Tomiyama, Shinya Abe and Eiji Ohno,(Matsushita Electric Industrial Co., Ltd.)ABSTRACT:
Conventional mastering technologies employ photolithography with photon-mode recording.
The size of patterns has been downsized by shortening wave length of exposure source. Leading
mastering technologies for Blu-ray Disc ROM, which require forming pits smaller than 150nm,
employ electron beam. But it costs much. Recently some technologies of photolithography with
heat-mode recording were reported. The technologies enable laser light to form pits for Blu-ray
Disc ROM because heat-mode recording enable forming much smaller pits than the beam spot.
Heat-mode mastering technologies without electron beam have advantages to build low-costmastering system.

The key to establish it is development of new photoresist.

We discoveredthat TeOx-based material is useful as heat-mode type photoresist. Thermal Isolation Filmdrastically improved the patterning resolution. TeOx-based photoresist and Thermal Isolation
Film enable BD-ROM mastering. The jitter values satisfy Blu-ray Disc system were obtained at
the full range of replicated discs. Furthermore we made the mechanism of TeOx-based
photoresist clear to present a beneficial guidance for researching new heat-mode typephotoresists. Segregation of TeO2 and TeOx-based material and dissolution of TeO2 are themechanism how TeOx works as heat-mode type photoresist. This mechanism is applicable forother heat-mode type recordable materials that are recoded by condensation or crystallization.

13.

Dielectric-Thin-Film with High-Deposition-Rate for HD DVD Rewritable Media

Eiji Kariyada, Shuichi Ohkubo, Hideki Tanabe, and Tatsunori Ide(NEC Corporation)
Abstract
We have developed a method for sputtering low-n dielectric thin films more rapidly than theconventional SiO2 dielectric thin films. We have found that the deposition rate for the SiNiON
film using a SiNi target with argon, oxygen, and nitrogen mixed gas was four times faster thanthat for the conventional SiO2 film and was almost the same as that for the ZnS-SiO2 film. Bothfilms had almost similar refractive indexes. We have also confirmed that the rewritable media
with the SiNiON film had excellent R/W characteristics.

14.

216Mbps Speed 50GB Phase Change Write Once Disc

Reiji Tamura(Hitachi Maxell Ltd.)
Abstract15.

100Mbps High-Speed Write/Read Characteristics for a 50 GB/layer Optical disk

J. Ushiyama 1 ,A. Hirotsune 1 , H.Minemura 1 , H.Kudo 1 , H.Miyamoto 1 , R.Tamura 2 ,K.Adachi 2(1:Hitachi Ltd., 2: HitachiMaxell Ltd.)
Abstract
High-density write/read technology for 50 GB/layer at a data transfer rate of 100 Mbps wasdeveloped. Good bit error rates under 1x10-4 were obtained in a condition using a phase-change
WO-disk and a3-beam cross-talk-canceller.

16.

High Speed Crystallization Materials for the Rewritable HD DVD

Tsukasa Nakai, Sumio Ashida, Keiichiro Yusu, Noritake Ohmachi, Kazuyo Umezawa,
Naomasa Nakamura(Toshiba Corporation)
Abstract
We have investigated high speed crystallization materials of the Rewritable HD DVD media.
Two key materials were used in order to achieve faster crystallization for the phase-change
recording media, a novel pseudo-binary alloy film as the recording layer and improved hafniumoxide-based composite material as the interface layers. The HD DVD format is anext-generation optical recording system having blue-violet lasers with the wavelength of 405nm, numerical aperture (NA) of 0.65 and light incidence on 0.6-mm-thick substrate having theland and groove format. The feasibility of higher data transfer rate, 2X or more has beensuccessfully demonstrated for the dual-layer type HD DVD-ARW having the user data capacityof more than 30 GB.

17.

High Density Near Field Optical Disc Recording using Phase Change Media andPolycarbonate Substrate
Ariyoshi Nakaoki, Masataka Shinoda, Kmihiro Saito, Takao Kondo, Tsutomu Ishimoto,Takeshi Matsui, Kim Sunmin( Sony Corporation)
Abstract
A high density recording on optical disc with near field technology has been examined. We had
succeeded in achieving a high numerical aperture (NA) of 1.83 by the developed solid
immersion lens (SIL) which were made by high refractive index material (n=2.0). The gap
distance between SIL and disc surface was kept about 20 nm by optical servo system. In orderto realize the near field recording, we adopted a molded polycarbonate substrate and a phasechange media. The embossed pattern on substrate was created by the drawing system with anelectron beam and the track pitch was 160 nm. The top layer of SiN was deposited because ofoptical optimization and thermal optimization. We observed the clear eye pattern of recorded
17pp pattern which were recorded by blue laser of 405 nm with varying a pit length from 110nm to 50 nm. We measured the bit error rate by an adaptive 8 taps PRML and obtained a valueof 5x10-4 at bit length of 55 nm.

19.

High-transmittance Write-once Medium with Te-O-Pd Film Suitable for Multilayer Discon BD Format
Hideki KITAURA, Katsuyuki TAKAHASHI, Haruhiko HABUTA, Noboru YAMADA(Matsushita Electric Industrial Co., Ltd.)
Abstract
We have developed a high-transmittance write-once medium with Te-O-Pd recording film. The
medium shows transmittance of 78% and 2T CNR of 43 dB as high as that of L1 ofconventional dual layer medium on BD format.