Post on 19-Mar-2020
Development of High Density
Optical Storage Media
高密度光儲存媒體之發展
何永鈞
國立中興大學材料工程學系
2002. 04. 26
Outline
Development History of Optical Storage
Media
Classification for Optical Storage Media
Principles of Optical Storage Technology
High Density Optical Storage Media
Conclusions
Development History of Optical Storage Disc
1981 1983 1985 1987 1989 19911993 1995 1997 1999 2001 2003
CD-DA
CD-RO M
CD-RW
Photo CD
Video CD
CD-R
CD-MO
CD-I
DVD-RAM 2..6GB
DVD ROM & Video
DVD–RAM/R/RW 4.7GB
DVD Audio
DVR 22.5GB
DVD+R /RW 4.7GB
Classification for Optical Storage Disc
Read-Only ：CD-DA、CD-ROM、VCD、
DVD-Video、DVD-ROM、DVD-Audio
Recordable：CD-R、DVD-R
Rewritable：CD-RW、DVD-RAM、DVD-
RW、DVD+RW、DVR
Read-Only Disc Structure
Mastering→ Replication→ metallization→
Lacquering ( bonding )→ Printing
Recordable Disc Structure
Mastering→ Replication→ Dye coating→metallization→ Lacquering→ Printing
Recordable Disc Structure
Mastering→ Replication→ Dye coating→metallization→ Bonding→ Printing
Mastering→ Replication→ ZnS-SiO2/AgInTeSb/ZnS-SiO2/Al-Ti Sputtering → Lacquering→ Printing
Rewritable Disc Structure
Rewritable Disc Structure
Pick-up Head
Optical Path of Pick-up Head
Read for Read-Only Disc
00000100010000000100000000010000
Land Pit Land Pit Land
Read for Read-Only Disc
Read and Record for Recordable Disc
After RecordedBefore Recorded
Write strategy
Write、Erase and Read for Rewritable Disc
Initialized Active Layer Written Bit
Temp.
Tm
Tg
Write Read Erase
Time
Multi-Media Applications
1997 2000 2005 2010 2015
4.7 GB 15GB 36GB 100GB 1TB
VideoROM2 hrs
VideoRAM2 hrs
HDTV4 hrs
3-DVideo
Interactive3-D Video
Capacity
Transfer Rate
Seek Time
20 MB/s 50-100 MB/s 100-250 MB/s 1 GB/s
30 ms 10-20 ms 5-10 ms 1-2 ms
How to Increase Recording Density？
Spot Size Reduction
Volumetric Storage
Data Format
Disc Fabrication
High DensityOptical
Storage Media
Multi-layer
Photo-induced
HolographicECC
Multi-level
Modulation
Short λ High NA Near-Field Super Resolution
High-tech mastering L/G and Deep Groove
How to Increase Recording Density？
Reduce Laser Spot Size
Short Wavelength（λ=400nm）、High Numerical Aperture （NA=0.8）
Solid Immersion Lens (SLI) : To Increase Numerical Aperture
Super-RENS
Increase Coding Efficiency ：Multi-level Coding
Multiple-layer Structure ：Multi-layer Recording
Volumetric Recording ：Holographic Optical Recording
DVR ( λ = 400 nm ＆ NA = 0.85 )
Blue Laser
High NA double-Lens
Assemble
0.1mm Hard Cover Layer
Single layer capacity 22.5GB
DVR ( λ = 400 nm ＆ NA = 0.85 )
Solid Immersion Lens
Excess theoretical NA limit
“1”
Air Gap ：10 ∼ 100 nm
Near Field Recording
Laser spot size ＜ 100 nm
Single layer capacity 100Gdisc
f
NA=0.55~0.8
n1=1.45~1.9 h < λ
會聚透鏡
半球型SIL
SUPER-RENS
Optical Super-Resolution
Near Field Structure
Can read pit length < 60 nm
Single layer capacity 200GB
SUPER-RENS
Diffraction-Limit
Spot size ∼0.6 λ/NA
SUPER-RENS
0 50 100 150 2000
100
200
300
400
500
600
700
Tim e(ns)
Tem
pera
ture
(C)
Tx
Tm
recording layer
mask layer
front partrear part
read
out s
igna
l
mask layerrecording layer middle dielectric layer
SUPER-RENS
Requirements for mask layer
Fast Response
High sensitivity
Large transmittance change
High stability
SUPER-RENS
Transmitted Type Scattering Type
Multi-level
Multi-level is to improve the coding efficiency of
recording bits to increase recording density
PPM ：Pit Position ModulationPWM ：Pit Width Modulation
Multi-level Pulse Depth Modulation
Multi-Level Rewritable
Matsushita - Mark Radial Width Modula
Multiple-level Reflection Modulation
Terabyte Optical Storage
3D Storage3D3D StorageStorage
Multi-function／Volumeric optical disks Holographic Memory
Fluorescent Multilayer Disc （FMD）
US Constellation 3D
(C3D) Company
06/2000：40GB
Analogue Video Disc
10/2000： 50GB Digital
Video Disc
Future > 100GB
Fluorescent Multilayer Disc （FMD）
Fluorescent Multilayer Disc （FMD）
Advantages
Every layer is transparent. There is no reflective
interface between layers.
The exciting radiation energy can be achieved by
absorption of 1% incident light.
The exciting fluorescent signals won’t be absorbed by
other fluorescent materials.
Fluorescent Multilayer Disc （FMD）
With larger tolerance for the imperfection of storage
media as well as disc drive.
Compatible with the existing CD and DVD systems.
Read and write can be performed simultaneously. Data
transfer rate is much higher than that of single layer
disc.
Fluorescent Multilayer Disc （FMD）
Fluorescent Multilayer Disc （FMD）
螢光材料的選擇
必須與基版的材料相容，亦即可被塗佈於基版上且在多層的
製造程序中自始至終必須維持它的特性而不變質。
螢光材料的吸收波長最好是與市售低價格、穩定度高的半導
體雷射波長相同，例如紅光雷射系統650nm。
所放射出的螢光波長最好比入射雷射光高50nm左右，如此較
易分離入射和信號光源。
此材料應該有高的螢光轉換效率。
Fluorescent Multilayer Disc （FMD）
此材料的折射率（Refraction Index）應該要稍大於聚碳酸
樹酯的折射率。
此材料在合理的時間範圍內應該維持穩定不能變質，當其暴
露於周遭的光線（Ambient Light）或讀取光源不能產生劣
化。
若應用於旋轉的碟片系統而非卡片式的系統，尚須具備快速
的反應時間（1 nsec）及訊號強度在高飽和水平（Saturated
Level；1mW/cm2）。
Holographic Optical Recording
原理：
經由物體反射的物光與參考光
因重疊而干涉，在全像底片上
以光柵的形式將訊號記錄下
來。記錄媒體讀取時，需要與
記錄相同的參考光，藉由物光
的還原來讀取訊號。
全像片
物光
物體
參考光
全像片
實像
參考光
原物光再生
直接穿透光
Holographic Optical Recording
Holographic Optical Recording
Holographic Optical Recording
High data transfer rate Rewritable Disc
Requirements for phase change materials
High Photo-sensitivity
Large optical contrast between crystalline and
amorphous phases
High thermal stability
High structural stability
Fast re-crystallization rate
How to increase re-crystallization rate ?
Optimum recording layer
thickness
thickness ~ 30 nm
t (nucleation) ~ 17 ns
CET ~ 38 ns
Crystallization acceleration layer
SiC or GeN
t (nucleation) ~ 14 ns
CET ~ 27 ns
GeSbTe + O2
How to increase re-crystallization rate ?
How to increase re-crystallization rate ?
7800.50
6580.60
6580.85
4000.85
AgInSbTe
Ge2Sb2Te5
0.0 0.4 0.8 1.2 1.6 2.0Reciprocal Spot Diameter ( µm-1 )
Max
imum
Use
r Dat
a R
ate
( Mbi
t/s)
0
10
20
30
40
50
60
70
80
Fast Growth Materials
0 10 20 30 40 50 60 70 80 90 100100
90
80
7060
5040
30
0
10
20
90
100
80
70
60
50
40
3020
10
0Te (at%) Sb (at%)
Ge (at%)
Conclusions
“ Higher recording density “、” Larger
capacity “ and “ Faster data transfer rate “
is the trend in the development of optical
storage medium !!
Thank you !!