Polymer resist. PMMA is a common resist for EBL and imprint having resolution su
ID: 1059795 • Letter: P
Question
Polymer resist. PMMA is a common resist for EBL and imprint having resolution sub-10nm, or much higher for nanoimprint. The intrinsic sizes of PMMA are chain length when the chain is fully extended; and diameter when the chain is fully rolled within a sphere (see figure below). For molecular weight 100kg mol (1 mol = 6.02 x 10^23), what is the N (number of repeating unit of MMA)? If each repeating unit has a length of 0.2nm: what is the chain length when it is fully extended into a line? PMMA has a density of 1.2g/cm^3, what is the diameter of the sphere when it is fully rolled into a sphere shape?Explanation / Answer
a) The number of repeating units of MMA is given as:
N = Mn/M0
where Mn = number average molecular weight = 100 kg./ mol = 100,000 g/mol
M0 = weight of each monomer unit of MMA = 5(C) + 8(H) + 2(O) = 5(12) + 8(1) + 2(16) = 60+8+32= 100 g/mol
N = 100,000/100 = 1000 repeat units
b) Given length of each repeat unit = 0.2 nm
Length of chain when fully extended = 0.2 * 1000 = 200 nm