METHOD FOR FABRICATING SEMICONDUCTOR DEVICE
At least three or more plurality of chips are stacked to form a three-dimensional integrated circuit. When the plurality of chips are stacked, at least two or more of three stacking methods are used which are a wafer-to-wafer stacking method that bonds together the mutually corresponding chips each on a wafer level, a chip-to-wafer stacking method that bonds together the mutually corresponding chips including one on a chip level and the other on a wafer level, and a chip-to-chip stacking method that bonds together the mutually corresponding chips each on a chip level.
1 . A method for fabricating a semiconductor device having a three-dimensional integrated circuit formed by stacking at least three or more plurality of chips, comprising the step of:
stacking the plurality of chips using at least two or more of three stacking methods which are a wafer-to-wafer stacking method that bonds together the mutually corresponding chips each on a wafer level, a chip-to-wafer stacking method that bonds together the mutually corresponding chips including one on a chip level and the other on a wafer level, and a chip-to-chip stacking method that bonds together the mutually corresponding chips each on a chip level.
2 . The method of claim 1 , wherein, when the mutually corresponding chips are bonded together using the wafer-to-wafer stacking method, the chip-to-wafer stacking method, or the chip-to-chip stacking method, the both chips are electrically connected to each other with a through-silicon-via.
3 . A method for fabricating a semiconductor device, comprising the steps of:
(a) stacking a plurality of first wafers each provided with a plurality of memory chips so as to electrically connect the mutually corresponding memory chips to each other with first through-silicon-vias to form a wafer stack;
(b) dividing the wafer stack by dicing to form a plurality of first chip-to-chip stacks;
(c) stacking the plurality of first chip-to-chip stacks and a second wafer provided with a plurality of interface chips so as to electrically connect the first chip-to-chip stacks and the interface chips, which correspond to each other, with second through-silicon-vias to form a first chip-to-wafer stack;
(d) dividing the first chip-to-wafer stack by dicing to form a plurality of second chip-to-chip stacks;
(e) stacking the plurality of second chip-to-chip stacks and a third wafer provided with a plurality of logic chips so as to electrically connect the second chip-to-chip stacks and the logic chips, which correspond to each other, via third through-silicon-vias to form a second chip-to-wafer stack; and
(f) dividing the second chip-to-wafer stack by dicing to form a plurality of third chip-to-chip stacks.
4 . The method of claim 3 , wherein
the step (b) includes the step of fixing the wafer stack onto a support substrate, and dicing the wafer stack, and
the step (c) includes the step of forming the first chip-to-wafer stack, and then stripping the support substrate from the first chip-to-wafer stack.
5 . The method of claim 3 , further comprising, between the steps (c) and (d), the step of:
polishing the back surface of the second wafer of the first chip-to-wafer stack to thin the second wafer.
6 . The method of claim 3 , wherein the first through-silicon-vias, the second through-silicon-vias, and the third through-silicon-vias are each formed of a conductive material containing copper as a main component.
7 . The method of claim 3 , further comprising, after the step (f), the step of:
(g) stacking each of the plurality of third chip-to-chip stacks and each of a plurality of other chips to form a plurality of fourth chip-to-chip stacks.