4. CZOCHRALSKI CRYSTAL GROWTH
1. POLYCRYSTALLINE SILICON
2. TO PRODUCE SINGLE CRYSTAL Si INGOTS
3. QUARTZ CRUCIBLE = POLYSi + DOPANT
4. Si MELTING POINT : 1420º C
5. ● Dip single crystal rod of Si –seed crystal
● Slowly Pull the seed crystal
● During pulling, seed crystal & crucible rotate
in opposite direction
● Si INGOT DIAMETER:10-15cm,
● Length 100 cm
● INGOT TRIMMING & GRINDING
● Top & bottom portions of ingot cut off
D=10 ,12.5, 15cm
8. 02 EPITAXAIL GROWTH
• A reaction chamber
consists of long
cylindrical quartz tube
encircled by an RF
induction coil
•The silicon wafers
placed on a rectangular
graphite rod called
BOAT
•Heat by 1200º C
•Various gases required
for the growth
CONSTRUCTION
9. 03 OXIDATION
• has the property of preventing the diffusion of almost all impurities through it.
•hard protective coating & is unaffected by almost all reagents except by hydrochloric acid , it stands
against any contamination.
•By selective etching of SiO2, diffusion of impurities through carefully defined windows in the SiO2 can
be accomplished to fabricate various components
• THERMAL OXIDATION:
12. 2 Processes:
(i) PHOTOGRAPHIC MASK – to generate the patterns
(ii) Photo etching – to remove from desired regions
• coat wafer with photosensitive emulsion
•Film thickness: 5000-10000Aº
•UV rays exposed – KPR Kodak photoresist to be polymerized
•Remove the mask
•Dip wafer in trichloroethylene chemical
•Pattern generated
•Dip in Hydrofluoric acid
•Removes silicondioxide
•TECHNIQUES
•X-ray
•Electron Beam Lithography
13. DIFFUSION
05
• Diffusion of impurities
•Quartz boat 20 cleaned wafers
•Pushed into the hot zone
•1000ºC
•BORON- BORON OXIDE, BORON CHLORIDE
•PHOSPHOROUS- PHOSPHOROUS PENTAOXIDE, PHOSPHOROUS OXYCHOLORIDE
•Sweep the impurities –dry oxygen / nitrogen used
•2 hrs duration to diffuse
14. Fonts & colors used
(https://fonts.google.com/specimen/Mukta)
#38076e #6e009a #861a97
#ffffff
6. ION IMPLANTATION
• add impurities in Si wafer
•Si wafers placed in a target chamber
•Scan by beam of high energy dopant ions (20-250KV)
•Low temp
•Controlled from outside