Downloaded 569 times
Uploaded byDeepak Rawat
Etching
Etching is used in IC fabrication to remove unwanted materials and leave a required pattern. There are two main types: wet etching uses liquid chemicals, while plasma etching uses ion bombardment in a plasma. Plasma etching is faster, easier, and more directional than wet etching. It allows for anisotropic etching profiles with better resolution, cleanliness and process control compared to isotropic wet etching.
More Related Content
Etching
- 1. Etching By Deepak Rawat GBPECPauri Uttarakhand India(246001) (An important step in IC fabrication )
- 2. Outline What isEtching Steps preceding Etching in IC Fabrication Types of Etching Simple Idea of Wet Etching Plasma Etching What is Plasma Anisotropy and Selectivity Advantage of Plasma Etching over Wet Etching
- 3. What is Etching Simply removing unwanted materials from the surface to form a required pattern
- 4. Steps Preceding Etchingin IC Fabrication 1. 2. 3. 4.
- 5. Types of Etching Two types of Etching ◦ Wet Etching: ◦ Etching is done by liquid chemicals ◦ Unmasked areas are etched away by the chemical reactions (Oxidation and Reduction ) ◦ Plasma Etching (Dry Etching): ◦ Etching is done exposing the material into bombardment of ions in Plasma
- 6. Simple idea ofWet Etching Etchants: KOH, HF, BF6, BCl3 SiO 2 6HF H2SiF6 2H2O
- 7. Plasma Etching (DryEtching) Faster and Easier way Both chemical and ionic species play the roll
- 8. What is Plasma State of mater which consist free electrons and cations Plasma looks similar to the gases Plasma is also called as ionised gases
- 9. In Plasmahigh number of electrons does not move around in orbits Plasma is created when gas is either exposed to high temp. Or high voltage
- 10. Due tothese free electrons and cations Plasma easily conducts electricity and also produce magnetic field. Nature also produces plasma by means of fire and lightning.
- 11. What happensinside plasma
- 12. Physical Etching insidethe Plasma Etching species are ions like CF3 + or Ar+ which remove material by ion-bombardment. Ion etching is much more directional (anisotropic) due to directional acceleration of ions by high E field Mask Film + + Ionic species + + + +
- 13. Anisotropy Etchant cannot distinguishes b/w vertical or horizontal dimensions (isotropic). Anisotropy = 1 – dH/dV Wet etching is isotropic and dry etching is anisotropic.
- 14. Selectivity Etchant shoulddistinguish b/w SiO2 and Si wafer. Wet Etching is Selective than Dry Etching.
- 15. Advantages of PlasmaEtching over Wet Etching Eliminates handling of dangerous acids and solvents. Uses small amounts of chemicals. Anisotropic etch profiles. High resolution and cleanliness. Less undercutting. Better process control.