》 Growth methods
〉 Al₂O₃(Sapphire) 성장방법
당사는 키로풀로스(Kyropulos), 백다사로프(Bagdasarov)(혹은 HDC) 그리고 스테파노프(Stepanov)(혹은 EFG)등 세 종류의 다른 성장 방법으로 사파이어 제품을 공급하고 있습니다.
〉 Bagdasrov (HDC) 방식
크리스탈이 수평한 배모양의 컨테이너에 녹여서 시간당 8~10㎜의 속도로 성장 시킨다.
이 방법으로 성장을 하면 커다란 널빤지 형태로 되며 거의 완벽한 가장자리(edges)와 특정의 결정방향을 얻을 수 있다.
<C-면, M-면, R-면 혹은 임의적 방향>
성장로 단면
성장로 단면
백다사로프 방식에 의한 사파이어 성장은 높은 광학전 품질을 보유하고 있다(2등급~3＼등급).
이 방법으로 성장된 대표적인 잉곳의 형태는 두꺼운 장방형을 이룬다(220㎜×250㎜×T25~35㎜).
소재로는 직경 2"~8"(두께>3㎜) 규격의 사파이어 잉곳/반가공품/윈도우를 제작하는데 최적의 조건이다.
백다사로프 방법에 의해 제조된 C-면(Plane)은 직경 최대 8"의 블루 LED 제조용으로 적용된다.
〉 Kyropulos 방식
이 방법에 의한 결정화 과정은 최저 온도에서 녹이는 특징으로 인해 씨드 부분에서 시작한다.
사파이어의 모양과 크기는 온도 영역에 의해 좌우되는데 이는 크리스탈과 융용 레벨 밀도의 차이에 의존한다.
성장 스피드는 대략 0.15㎏/hr 이며 크리스탈 크기는 크러시블의 크기에 따라 다르지만 현재 가장 크게는 300㎜ 까지 가능하다.
〉 스테파노프 혹 EFG 공법
성장 속도 1~4㎝/hour 비활성 매체(아르곤) 사용, 공법은 복잡한 형태의 크리스탈 성장이 가능하다.
스테파노프 (혹 EFG) 공법은 특정 형태의 성장에 쓰인다.(튜브, 라드, 쉬트 및 섬유 형태 포함)
EFG 기술은 독특한 형태와 실링 조립을 가능하게 하며 폭 70㎜의 길이 500㎜까지의 리본형태,
튜브는 OD 85㎜, 크러시블은 OD 65㎜까지 가능하다.
이 공법으로 성장시킨 크리스탈은 다른 수정 성장방향(오리엔테이션)을 가지며
주로 산업적, 기계적 용도로 쓰이고, 낮은 등급의 적용에 쓰인다.(4~6등급 자재).
》 Quality grade
〉 Al₂O₃ (Sapphire) - Quality Grade
Our six grades sapphire material, is selected for specific applications and priced according to quality.
The transmission of all optical grades is above 80% in the non-vacuum spectrum (from 0.25 to 4.5㎜) and all grades are available
Below you can find a schematic description of how various defects appear in the Polarized/Focused light:
For surface queality of optical components (windows) we always use US Military Specificaion for optical components (MIL-0-13830) when describing the surface quality.
Please always specify the requires surface quality in accordance with MIL-0-13830 (see details below):
SCRATCH: Any marking or tearing of the glass surface.
GRUSH or RUB SCRATCH: A hairline scratch.
DIG: A small rough spot on the glass surface similar to pits in appearance. A bubble is considered a dig.
Surface quality is to be specified by a number such as 60/40, which would permit a scratch width of 60㎛(0.0158 inches).
Optical Flatness
》 Chemical analysis
〉 Al₂O₃ - Chemical Admistures' Concentrations Analysis
The composition of admistures are measured by the method of spark mass-spectrometry at a mass-spectrometer
with double focusing JMS-01-BM2 produced by JEOL (Japan).
Mass-specters with high resolution are registeres on photographic plates UV-4.
For qualitative interpretation of the mass-specters we use a microdensitometer MDM6 produced by Joyce Loeble (Great Britain) in combination with a mini-computer NOVA4 (USA).
The quantities of admixtures are calculated with the help of a MS&GC Lab software.
The random error or the analysis results corelates with the standard relative devitation 0.15-0.30.
The percentatage of inert gases and transuranium slements in our sapphire material are below the limit
where it can be detected - 0.01 ppm.
Below you can see typical concentrations of metallic impurities in sapphire crystals used for LEDc and SOS applications
The analysis results are given in parts million (1ppm-0.0001%)
We gurantee theat total concentration of metallic impurities in sapphire crystals used for optical applications will not exceed 50ppm and the material purity will not be less then 99.995%.
》 Crystalline
〉 Al₂O₃ - contral of Crystalline Perfection
To contral the crystalline quality, Rocking curves are measurec in the laboratory of State Research Scientific with the X-Ray installation of super-high resolution (up to 0.1 arc-secong).
The incident light has the wavelength of 2.8 Angstroms.
The rocking curves were measured with the help of an automated two-crystal x-ray spectrometer(CuKα1-ray, monochromator GaAs (511), monochromator angle 90.14 degrees) with a temperature stabilizing device.
The spectrometer is constructed on the basis of a commercial power supply "Iris" and a topogrphic camera RT-2. The rocking curves were being taken in a non-stop mode, at the angular speed of 0.0003 deg/min.
We also took the symmetrical Gragg reflection from the plane of wafer areas at the angles of 90 deg.
(the angle wasn't specified). Each point size 5㎜.
Below please see typical rocking curves of our substrates used for Blue LEDs applications:
The quality of a substrate (absence od insertioons, block marks, twins, dislocations and polycrystallin areas) are controlled by the width of the rocking curves. Typical curve width (at 0.5*Max level) odf Kyropulos made material of the Grades 2-4 is 10-20 arc seconds (EPD<1000 per sq cm) while for Bagdasarov method it is 20-30 arc seconds (EPD<3000 per sq cm).
》 Surface for epi
〉 Al₂O₃-Control of the Surface Quality (for EPI-polished surface only)
We currently guarantee surface roughness Ra < 0.3㎚ for our EPI-polished substrates for HB LEDs and SOS applications.
Here is an example of AFM image of the EPI-polished surface of 3' C-plane substate.
》 Optical
〉 Al₂O₃-Contral of optical transmittance
Another important parameter which to be contralled is optical transmittance.
This characteristic is especially important for material used for Blue LEDs applications.
Most LEDs makers pay particular in the Institute of Applied Physics Russian Academy of Science on the UV VIS installation for wavelength from 200㎚ up to 800㎚ for both-sided EPI-polished substrate with 0.43㎜ thicknedd.
Measurements are made in the same 5 points as the rocking curves.
Our standard EPI-polished substrated have the following transmittances:
Our standard 0.43㎜ thick two-sides polished sapphire substrate has the followinf transmittance: at 0.2um>/=78%
at 0.36-0.8 um range >/=85%
