Patent ID: 6198159
Filing Date: 2001-03-06
Classification: B32B,B81B,B81C,H01L

Abstract:
A bonded wafer comprising at least two wafer layers and a joining agent which joins the wafer layers together, the joining agent being a polyimide film which is an amorphous, heat fusion bonding aromatic polyimide (X) layer alone or a heat fusion bonding aromatic polyimide material comprising a substrate polyimide (Y) layer and an amorphous, heat fusion bonding aromatic polyimide (S) layer on each side of the substrate polyimide (Y) layer, wherein the amorphous, heat fusion bonding aromatic polyimide (X) (a) is an amorphous, heat fusion bonding aromatic polyimide obtained from a polyamic acid, obtained by reacting (i) an aromatic tetracarboxylic acid component selected from the group consisting of aromatic tetracarbxylic acids, aromatic tetracarboxylic dianhydrides and aromatic tetracarboxylic acid esters with (ii) an aromatic diamine under the condition that the tetracarboxylic acid component is present excessively or that terminal groups of the aromatic diamine are sealed with a dicarboxylic anhydride, (b) has an .eta. inh (0.5 g/dl in N-methyl-2-pyrrolidone (30.degree. C.)) of 0.5 to 3, and (i) has a crystallinity of not higher than 1%, and wherein at least part of the polyimide film can be removed from the bonded waver, and the peeling strength of the wafer is at least 100 kgf/cm.sup.2.