Metallization method

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,
• 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.