Exposure

    Photo-techniques:
    contact - step and repeat        Electron-beams
    projection - step and repeat   X-rays
    proximity                               Ion-beams
    conformal

Deep U.V. Exposure Technology

    Deep U.V. - 180-330 nanometers.
 

Cost Outlook	1982 Dollars
E-beam	1-2 million
X-ray	4 million
Direct stepping	0.5 million
UV-DUV	15,000 - 0.5 million

 
    Disadvantages
                lack of availability of lamps
                mismatch between lamp and resist
                contact printing
    Advantages
                low cost
                easier technology
                wide range of resist

E-Beam Lithography

Electron- beam wavelength << optical wavelength
i.e.    10 kV electrons

qV = ½mv2

v = 6 x 10⁷ m/sec

p = h / l = mv

    Disadvantages
                high cost
                resolution limits
                    beam spread (50 A - 300 A)
                    scattering
                        (a) in resist during transit
                        (b) backsaattering from the substrate

                new technology
    Advantages
                higher resolution
                easy to modify circuit
 

E-beam machine uses Richardson equation

Jc = AT²e^(-Ew/kT)

exposure time = (Q/C) D²  where C is constant, Q is flux sensitivity of resist

Masks

    One approach

Steps in the patterning of gold absorber layer on an x-ray mask by a process incorporating reactive ion milling.

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