Wafer processing base
Provided is a substrate for processing a wafer. The present invention can provide a substrate having excellent heat resistance and dimensional stability. The present invention can provide a substrate that has excellent stress relaxation properties, and therefore can prevent a wafer from being destroyed due to residual stress. Also, the present invention can provide a substrate that can prevent a wafer from being damaged or fried off due to a non-uniformly applied pressure during the wafer processing process, and that exhibits excellent cuttability. For these reasons, the substrate can be useful as a sheet for processing a wafer in various wafer preparation processes such as dicing, back-grinding, and picking-up.
1. A pressure-sensitive adhesive sheet for processing a wafer, comprising:
a heat resistant substrate that is a photo-cured product of a photo-curable composition, and
a pressure-sensitive adhesive layer formed on one or both sides of the substrate and coming in contact with the substrate,
wherein the photo-curable composition comprises a high-molecular weight acrylic polymer and a monomer component,
wherein the substrate has a glass transition temperature of −20° C. to 45° C. and a toughness of 10 kg·mm to 250 kg·mm at 23° C.,
wherein the high-molecular weight acrylic polymer comprises a partially polymerized product of a monomer mixture including:
(a) an alkyl(meth)acrylate having an alkyl group having 1 to 14 carbon atoms;
(b) at least one selected from the group consisting of a (meth)acrylate having an alkoxy group; a (meth)acrylate having a alicyclic group; a (meth)acrylate having an aromatic group; and a (meth)acrylate having a heterocyclic moiety; and
(c) a monomer having a hydroxyl group, carboxyl group, nitrogen-containing group or glycidyl group, and
wherein the monomer mixture does not include urethane acrylate.
2. The pressure-sensitive adhesive sheet for processing a wafer according to claim 1 , wherein the substrate has a glass transition temperature of −10° C. to 40° C.
3. The pressure-sensitive adhesive sheet for processing a wafer according to claim 1 , wherein the substrate has a toughness of 10 kg·mm to 200 kg·mm at 23° C.
4. The pressure-sensitive adhesive sheet for processing a wafer according to claim 1 , wherein the substrate has a toughness of 10 kg·mm to 250 kg·mm at 20° C. to 25° C.
5. The pressure-sensitive adhesive sheet for processing a wafer according to claim 1 , wherein the high-molecular weight acrylic polymer has an average molecular weight of 500 to 1,000,000.
6. The pressure-sensitive adhesive sheet for processing a wafer according to claim 1 , wherein the photo-curable composition further comprises multi-functional acrylate.
7. The pressure-sensitive adhesive sheet for processing a wafer according to claim 1 , wherein the photo-curable composition further comprises a photoinitiator.
8. The pressure-sensitive adhesive sheet for processing a wafer according to claim 1 , wherein the substrate has a thickness of 5 μm to 400 μm.
9. The pressure-sensitive adhesive sheet for processing a wafer according to claim 1 , wherein the pressure-sensitive adhesive layer comprising an acrylic polymer that is cross-linked by a multi-functional cross-linking agent.