ETCHING - Transfer of Patterns: Wet and Dry Etching ES174...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
Transfer of Patterns: Wet and Dry Etching ES174 Photonic and Electronic Device Laboratory Lecture # 8 Text Book: Plummer, Chap. 10 Other Sources: Jaeger, Chap. 2.2
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Harvard_Fabrication_5.ppt – 2006 2 Key Ideas We are interested in removal of materials Etch Rate rate of material removal; working with thin films – so, 1-1000 nm/min dependence on concentration, agitation, temperature, density etc. of the thin film or substrate, … Etch Selectivity relative etch rates (ratio) of the thin film to the mask, substrate, or other films Etch Geometry: sidewall slope (degree of anisotropy) Reproducibility Two principal approaches Wet etching (reactants from liquid sources) Dry etching (reactants from gas/vapor phase – neutral or ionized) mask material thin film being etched substrate Anisotropic/Directional Etch Isotropic Etch
Background image of page 2
Harvard_Fabrication_5.ppt – 2006 3 Etching At its simplest, the key steps in etching would be 1: Etch species generation 2: Movement to surface Diffusion and Field-Aided 3: Adsorption 4: Reaction 5: Desorption 6: Diffusion to bulk There may be other competing and inhibiting simultaneous reactions In limits, slowest dominates F - H 2 O HF H + F - RF + DC Bias Gnd CF 4 CF + 2 O 2 F SiO 2 + 4HF = SiF 4 + 2H 2 O SiO 2 + CF 4 = SiF 4 + 2CO 2 Principal Sum Reactions F - In detail, multiple charged species, movement of species, multiple reactions 4 * 3 * 4 3 * 4 4 2 SiF F Si e CF F e CF CF F CF + + + + + + 1 2 3 4 5 6
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Harvard_Fabrication_5.ppt – 2006 4 Wet Etching Transport of reactants to surface Surface reaction Transport of products from surface Key ingredients Oxidizer: H 2 O 2 , HNO 3 , … Acid or base that dissolves the oxidized surface: H 2 SO 4 , NH 4 OH, HCl, Diluting agent for transporting reactants and products H 2 O, CH 3 COOH, … An electrochemical process Oxidation: electron loss / increase in oxidation number Reduction: electron gain/ decrease in oxidation number
Background image of page 4
Harvard_Fabrication_5.ppt – 2006 5 HNA: HydroFluoric – Nitric Acid Etching R. B. Darling
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Harvard_Fabrication_5.ppt – 2006 6 1
Background image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/04/2009 for the course ECE 5360 taught by Professor Shealy during the Fall '07 term at Cornell University (Engineering School).

Page1 / 25

ETCHING - Transfer of Patterns: Wet and Dry Etching ES174...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online