Metallization method
View Patent ↗Disclosed herein is a metallization method, comprising (a) forming on a first surface of a substrate an underlayer from an underlayer composition comprising: a first polymer comprising an acid-labile group, and a sensitizing group, wherein (i) the first polymer comprises the sensitizing group or (ii) a compound that is distinct from the first polymer comprises the sensitizing group; wherein the underlayer has a first thickness; (b) forming on the underlayer a photoresist layer from a photoresist composition comprising: a second polymer comprising an acid-labile group, and a photoacid generator; wherein the photoresist layer has a second thickness; (c) pattern-wise exposing the photoresist layer to activating radiation; (d) developing the exposed photoresist layer with a basic developer.
1 . A metallization method, comprising:
(a) forming on a first surface of a substrate an underlayer from an underlayer composition comprising: a first polymer comprising an acid-labile group, and a sensitizing group, wherein the sensitizing group is a polycyclic aromatic group, and wherein the first polymer comprises the sensitizing group; wherein the underlayer has a first thickness;
(b) forming on the underlayer a photoresist layer from a photoresist composition comprising: a second polymer comprising an acid-labile group, and a photoacid generator; wherein the photoresist layer has a second thickness;
(c) pattern-wise exposing the photoresist layer to activating radiation;
(d) developing the exposed photoresist layer with a basic developer, thereby removing portions of the photoresist layer and portions of the underlayer to form a relief pattern, wherein the relief pattern has an undercut profile at the first surface, wherein a maximum height of an undercut in the relief pattern measured from the first surface is greater than the first thickness; and
(e) after forming the relief pattern, plating a metal on the first surface of the substrate.
2 . The metallization method of claim 1 , further comprising (f) removing the photoresist and underlayer after plating the metal.
3 . The metallization method of claim 1 , wherein the sensitizing group is an anthracene or anthracene-derivative group.
4 . The metallization method of claim 1 , wherein the underlayer composition is free of photoacid generators.
5 . The metallization method of claim 1 , wherein the first thickness is 200 nm or less.
6 . The metallization method of claim 1 , wherein a ratio of the first thickness to the second thickness is less than 0.01.
7 . The metallization method of claim 1 , wherein the acid-labile group of the first polymer and the acid-labile group of the second polymer are independently a tertiary ester group or an acetal group.
8 . The metallization method of claim 1 , wherein the second polymer comprises a repeat unit formed from a vinyl aromatic monomer.