An improved die seal ring is described which includes at least one break. In the region of the break in the die seal ring, the doping is modified so that the impedance of the electrical path across the break through the substrate is increased. Offsets in the break may also be used and the offset may be within a break in a track and/or between breaks in different tracks, where the die seal ring includes more than one track.
1. An integrated circuit die comprising:
electronic circuitry formed on a substrate; and
a seal ring around a periphery of the die, the seal ring comprising at least one break; and
a block doped region around the break, said block doped region being of the same conduction type as the substrate and modified by introduction of a well and a surface doped area both of which are of an opposite conduction type to the substrate in the break so as to increase the electrical impedance of a path through the substrate across the break.
2. An integrated circuit die according to claim 1 , wherein silicidation in said block doped region is blocked in at least a portion away from a metal contact to the substrate.
3. An integrated circuit die according to claim 1 , wherein the seal ring comprises at least one track and wherein the break comprises an offset break within a track.
4. An integrated circuit die according to claim 3 , wherein the offset break is formed using 45° bends.
5. An integrated circuit die according to claim 1 , wherein the seal ring comprises at least two tracks and wherein the break comprises an offset break between tracks.
6. An integrated circuit die according to claim 1 , wherein the seal ring comprises a first and a second track and wherein the at least one break comprises an offset break within each track and wherein the offset break in the first track is offset from the offset break in the second track.
7. An integrated circuit die according to claim 6 , wherein a width of the second track is increased in a region around the offset break within the second track and a width of the first track is decreased within the region around the offset break within the second track.
8. An integrated circuit die according to claim 1 , wherein the offset break is formed in each metal layer and each continuous conductive layer in the seal ring.
9. An integrated circuit die according to claim 1 , wherein the doping in the seal ring in the block doped region around the break is modified to increase electrical impedance of a path laterally through the substrate across the break.
10. An integrated circuit die according to claim 1 , wherein doping in the seal ring, away from the break, is unmodified.
11. An integrated circuit die comprising:
electronic circuitry formed on a substrate; and
a seal ring around a periphery of the die, the seal ring comprising a first and a second track and at least one break pair;
wherein said break pair comprises an offset break within each track; wherein the offset break in the first track is offset from the offset break in the second track; and wherein a width of the second track is increased in a region around the offset break within the second track and a width of the first track is decreased within the region around the offset break within the second track.
12. An integrated circuit die according to claim 11 , further comprising a region around the break pair in which the doping is modified to increase electrical impedance of a path through the substrate across the break.