Photosensitive resin composition, pattern forming process, and fabrication of opto-semiconductor device

A photosensitive resin composition comprising:

• (A) a vinyl ether compound,
• (B) an epoxy-containing silicone resin, and
• (C) a photoacid generator,
• wherein the epoxy-containing silicone resin (B) consists of repeating units having the formulae (B1) to (B6):
• wherein R11 to R14 are each independently a C1-C20 monovalent hydrocarbon group which may contain a heteroatom, m is each independently an integer of 1 to 600, with the proviso that when m is an integer of at least 2, groups R13 may be identical or different and groups R14 may be identical or different,
• a, b, c, d, e and f are numbers in the range:
• 0≤a≤1, 0≤b≤1, 0≤c≤1, 0≤d≤1, 0≤e≤1, 0≤f≤1, 0<c+d+e+f≤1, 0<a+b≤1 and a+b+c+d+e+f=1,
• X1 is a divalent group having the formula (X1):
• wherein R21 to R24 are each independently a C1-C20 monovalent hydrocarbon group which may contain a heteroatom, p is an integer of 1 to 600, with the proviso that when p is an integer of at least 2, groups R23 may be identical or different and groups R24 may be identical or different, R25 is each independently hydrogen or methyl, x is each independently an integer of 0 to 7,
• X2 is a divalent group having the formula (X2):
• wherein Y1 is a single bond, methylene, propane-2,2-diyl, 1,1,1,3,3,3-hexafluoropropane-2,2-diyl, or fluorene-9,9-diyl, R31 and R32 are each independently a C1-C4 alkyl or alkoxy group, g and h are each independently 0, 1 or 2, with the proviso that groups R31 may be identical or different when g is 2, and groups R32 may be identical or different when h is 2, R33 is each independently hydrogen or methyl, y is each independently an integer of 0 to 7,
• X3 is a divalent group having the formula (X3):
• wherein R41 is each independently hydrogen or methyl, z is each independently an integer of 0 to 7, and R42 is a C1-C8 monovalent hydrocarbon group which may contain an ester bond or ether bond or a group having the formula (X3-1):
• wherein R43 is a C1-C8 divalent hydrocarbon group which may contain an ester bond or ether bond.