AN OUTLINE OF DIFFERENT THIN FILM TECHNIQUES

1. Vapor Deposition Pattern Transfer: Additive techniques-Physical and Chemical Vapor Deposition RAJEEV R PILLAI

4. Physical vapor deposition (PVD): thermal evaporation 6 The number of molecules leaving a unit area of evaporant per second

5. Physical vapor deposition (PVD): thermal evaporation The cosine law This is the relation between vapor pressure of the evaporant and the evaporation rate. If a high vacuum is established, most molecules/atoms will reach the substrate without intervening collisions. Atoms and molecules flow through the orifice in a single straight track,or we have free molecular flow : The fraction of particles scattered by collisions with atoms of residual gas is proportional to: The source-to-wafer distance must be smaler than the mean free path (e.g, 25 to 70 cm)

6. Physical vapor deposition (PVD): thermal evaporation From kinetic theory the mean free path relates to the total pressure as: Since the thickness of the deposited film, t, is proportional To the cos  , the ratio of the film thickness shown in the Figure on the right with  = 0° is given as:

7. Physical vapor deposition (PVD): sputtering -V working voltage - i discharge current - d, anode-cathode distance - P T , gas pressure - k proportionality constant Momentum transfer

8. Evaporation and sputtering: comparison

23. Electrochemical deposition :electrodeposition-thermodynamics (E) E 2 > E 1 : - battery E 2 < E 1 : + E ext > E cell to afford deposition (Nernst equation) 1. Free energy change for ion in the solution to atom in the metal (cathodic reaction): or also 2. The electrical work, w, performed in electrodeposition at constant pressure and constant temperature: and since  V =0 3. Substituting Equation (2) in (1) one gets (1) (2) 4. Repeat (1) and (2) for anodic reaction: or

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