Mallik, Try the following:
  he protocol I use for borosilicate (soda lime and quartz have different
temps):

  1. Clean with pirrhana
  2. AHP clean or (easier) Oxygen plasma
  3. Sandwich the 2 pieces
  4. put in oven:
        Ramp to 650 C at 5C/min
        hold for 4 hours
        let cool slowly to room temp (~ -5C/min) or naturally by oven off and
  closed.
    I've also bonded glass with an intermediate layer of ITO and Si that I got
from a paper. From my
experience, it's probablistic. Search on google. Also
the surface roughness of glass is critical, preferably ~ 10 Angstrom roughness.
-Ziggy