Photoresist

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N 2 is weakly bonded and UV light will free N 2 from Carbon ring leaving behind a reactive site, more stable to move 1 Carbon outside the ring with oxygen covalently bonded to form Ketene Presence of H 2 O, final rearrangement results in carboxylic acid Figure 8.6 Photolysis and subsequent reactions of DQ upon UV exposure.
Light, water are the main drivers of this process Starting material will not dissolve in the developer; carboxylic acid, however, readily reacts with and dissolves in basic solutions (pH > 7); novolac resin dissolves easily in developer Typical developer solutions are KOH or NAOH diluted with water Dark areas of the photomask will protect the resist from light and will “stay” after developing → positive image Negative resists are suited to features > 2 µm due to swelling during development; they are based on a resin of cyclized polyisoprene p and bis-aryl diazide (PAC); these compounds lose N 2 on light exposure and form free radicals that react with a site in the resin; this cross- linking produces a highly insoluble film in the developer and pattern is formed by washing away the unpolymerized resist → negative image
Page 1 and 2: Chapter 8 Photoresists
Page 3 and 4: Photoresists (PR) or resists Three
Page 5 and 6: Substitute: Methyl group Chlorine A
Page 7: Positive resist In i-line and g-lin
Page 11 and 12: Contrast, γ , is the slope of the
Page 13 and 14: Figure 8.9 Typical process flow in
Page 15 and 16: Industrial systems are called “co
Page 17: Exposing resist over topology cause

Photoresist

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