Sputtering process

1. A SEMINAR ON SPUTTERING PROCESS Presented By K. GANAPATHI RAO (13031D6003) Presence of Mr. Sumair sir

2. Outline Introduction. Sputtering Process. Sputtering Yield. Sputtering Deposition Film Growth. Application Of Sputtering. Additional Methods. Applications Of Thin Film.

3. Solids Zero Dimension 3D 2D 1D

4. Thin films Thin films are thin material layers ranging from fractions of a nanometer (monolayer) to several micrometers in thickness .

5. Synthesis of thin films

6. Sputtering – General Sputtering is a term used to describe the mechanism in which atoms are ejected from the surface of a material when that surface is stuck by sufficiency energetic particles. First discovered in 1852, and developed as a thin film deposition technique by Langmuir in 1920. Metallic films: Al-alloys, Ti, Tantalum, Nickel, Cobalt, Gold, etc.

7. Reasons for sputtering Use large-area-targets which gives uniform thickness over the wafer. Control the thickness by Deposition time and other parameters. Even materials with very high melting points are easily sputtered. Sputtered films typically have a better adhesion on the substrate. Sputtering can be performed top-down.

8. Basic Model

9. Requirements Vacuum. Inert gas. Power supply. Sputtering gas.

10. Sputtering steps Ions are generated and directed at a target. The ions sputter targets atoms. The ejected atoms are transported to the substrate. Atoms condense and form a thin film.

11. Sputtering yield Defined as the number of atoms ejected per incident ion. Determines the deposition rate. Depends on: Mass of bombarding ions. Energy of the bombarding ions. Direction of incidence of ions (angle). Pressure.

12. Mass & size of atoms Molecule size – need to be about the same size as the sputtered material too big cause layer deformation and yield a lot of material on walls. too small cause layer deformation w.r.t not proper ejecting atoms. Target deformation = Less uniform deposition.

13. Energy Of The Bombarding Ions Ion energy Vs. sputter yield:

14. Direction There is a probability that atom C will be ejected from the surface as a result of the surface being stuck by atom A. In oblique angle (45º-90º) there is higher probability for sputtering, which occur closer to the surface.

15. Direction Of Incidence Of Ions Sputter yield peaks at <90º. Atoms leave the surface with cosine distribution.

16. Pressure Pressure reduction – allow better deposited atoms/molecules flux flow towards the substrate. Expressed by “Mean free path” which is the average distance an atom can move, in one direction without colliding at another atom.

17. Sputtering deposition film growth Sputtered atoms have velocities of 3-6 E5 cm/sec and energy of 10-40 eV . Many of these atoms deposited upon the substrate. Thus, sputtered atoms will suffer one or more collision with the sputter gas.

18. Sputtering deposition film growth The sputter atoms have: Arrive at surface with reduce energy (1-2 eV ). Be backscattered to target/chamber. The sputtering gas pressure can impact on film deposition parameters, such as Deposition rate and composition of the film.

19. Sputtering deposition film growth

20. Application of Sputtering Thin film deposition: Microelectronics Decorative coating Protective coating Etching of targets: Microelectronics patterning CMOS, NMOS, PMOS fabrication Surface treatment: Hardening

21. Sputtering – additional methods Reactive & Non reactive sputtering RF & DC sputtering Magnetron sputtering Collimated sputtering Ion-Beam sputtering

22. A pplications Of Thin Film Technology Microelectronics CPU processors, cell phones, ipod , watches, batteries, Solar Panels

23. AR ( anti-reflective coatings ) On cars, jewelry , mirrors , night vision goggles Oxidation resistance on cutting tools, chemical factories. M edical drug delivery Applications Of Thin Film Technology

24. VIDEOS 1 2 3

25. References Hand book of thin film deposition process and techniques- By Krishna Seshan Thin Film Phenomena -  Kasturi L. Chopra   http://en.wikipedia.org/wiki/Thin-film_memory http://www.uccs.edu/~tchriste/courses/PHYS549/549lectures/ http://nptel.iitm.ac.in/syllabus/syllabus.php?subjectId=115102019 http://www.azom.com/article.aspx?ArticleID=8796