Patent ID: 7526698

Claim:
A semiconductor structure, comprising: (a) a first semiconductor chip and a second semiconductor chip, wherein the first semiconductor chip is on top of and bonded to the second semiconductor chip, wherein the first semiconductor chip comprises a first functional circuit including a first latch, wherein the second semiconductor chip comprises a second functional circuit including a second latch, wherein the first and second functional circuits are functionally identical, and wherein the second semiconductor chip further comprises a first comparing circuit electrically connected to the second latch; and (b) a first coupling via electrically connecting the first latch of the first semiconductor chip to the first comparing circuit of the second semiconductor chip, wherein the first comparing circuit is configured to: (i) receive a first content of the first latch indirectly through the first coupling via, (ii) receive a second content of the second latch directly, and (iii) compare the first and second contents and assert a first mismatch signal in response to the first and second contents being different.