Mask and reticle protection with atomic layer deposition (ALD)

A method comprising the steps of:

• (a) depositing by continuous-flow plasma enhanced atomic layer deposition (PEALD), a conformal coating on all sides and a distal end of a pattern existing on an substrate of a lithography mask, said pattern meant for absorbing electromagnetic radiation incident on said lithography mask;
• (b) retaining said conformal coating on said all sides and said distal end for protecting said pattern;
• (c) suppressing an electrostatic charge differential in said pattern by causing said conformal coating to act as a leaky dielectric, said causing done by a controlled doping of hydrogen in said conformal coating;
• (d) said PEALD performed by placing said substrate atop a platen inside a chamber, said chamber further having a planar inductively coupled plasma (ICP) source laterally affixed at its distal end from said substrate;
• (e) isolating said substrate from said ICP source in said chamber by a metal plate laterally affixed above said substrate and a ceramic plate laterally affixed below said metal plate but above said substrate, said metal plate and said ceramic plate having a first plurality of holes and a second plurality of holes respectively such that each of said first plurality of holes is aligned with a corresponding hole of said second plurality of holes, where each of said second plurality of holes is designed to have a diameter less than two Debye lengths of a plasma generated by said ICP source above said metal plate;
• (f) continuously flowing a gas A at a steady-state pressure to said ICP source to continuously generate said plasma;
• (g) grounding said metal plate to terminate said plasma;
• (h) passing into said chamber a pulse of a gas B below said ceramic plate, whereby excited neutrals from said gas A, said gas B and said substrate react in a self-limiting manner to produce said conformal coating on said substrate;
• and
• (i) providing said conformal coating to be SiO2;
• wherein said PEALD occurs at a temperature in the range of 20-80° C. and at a rate of 1.7-1.8 Angstroms per cycle, and said PEALD has a cycle-time equal to the sum of the duration of said pulse in step (h) and a time period until said pulse in step (h) has decayed to said steady-state pressure, and wherein said conformal coating does not contain spurious crystalline particles.