TY - GEN
T1 - Coupling-aware dummy metal insertion for lithography
AU - Deng, Liang
AU - Wong, Martin D.F.
AU - Chao, Kai Yuan
AU - Xiang, Hua
PY - 2007
Y1 - 2007
N2 - As integrated circuits manufacturing technology is advancing into 65nm and 45nm nodes, extensive resolution enhancement techniques (RETs) are needed to correctly manufacture a chip design. The widely used RET called off-axis illumination (OAI) introduces forbidden pitches which lead to very complex design rules. It has been observed that imposing uniformity on layout designs can substantially improve printability under OAI. For metal layers, uniformity can be achieved simply by inserting dummy metal wire segments at all free spaces. Simulation results indeed show significant improvement in printability with such a dummy metal insertion approach. To minimize mask cost, it is advantageous to use dummy metal segments that are of the same size as regular metal wires due to their simple geometry. But these dummy wires are printable and hence increase coupling capacitances and potentially affect yield. The alternative is to use a set of parallel sub-resolution thin wires (which will not be printed) to replace a printable dummy wire segment. These invisible dummy metal segments do not increase coupling capacitances but bring a higher lithography cost, which includes mask cost and RET/process expense. This paper presents a strategy for dummy metal insertion that can optimally trade off lithography cost and coupling capacitance. In particular, we present an optimal algorithm that can minimize lithography cost subject to any given coupling capacitance bound. Moreover, this dummy metal insertion will achieve a highly uniform density because of the locality of coupling capacitance, which automatically ameliorates chemical mechanical polish (CMP) problem.
AB - As integrated circuits manufacturing technology is advancing into 65nm and 45nm nodes, extensive resolution enhancement techniques (RETs) are needed to correctly manufacture a chip design. The widely used RET called off-axis illumination (OAI) introduces forbidden pitches which lead to very complex design rules. It has been observed that imposing uniformity on layout designs can substantially improve printability under OAI. For metal layers, uniformity can be achieved simply by inserting dummy metal wire segments at all free spaces. Simulation results indeed show significant improvement in printability with such a dummy metal insertion approach. To minimize mask cost, it is advantageous to use dummy metal segments that are of the same size as regular metal wires due to their simple geometry. But these dummy wires are printable and hence increase coupling capacitances and potentially affect yield. The alternative is to use a set of parallel sub-resolution thin wires (which will not be printed) to replace a printable dummy wire segment. These invisible dummy metal segments do not increase coupling capacitances but bring a higher lithography cost, which includes mask cost and RET/process expense. This paper presents a strategy for dummy metal insertion that can optimally trade off lithography cost and coupling capacitance. In particular, we present an optimal algorithm that can minimize lithography cost subject to any given coupling capacitance bound. Moreover, this dummy metal insertion will achieve a highly uniform density because of the locality of coupling capacitance, which automatically ameliorates chemical mechanical polish (CMP) problem.
UR - http://www.scopus.com/inward/record.url?scp=46649109141&partnerID=8YFLogxK
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U2 - 10.1109/ASPDAC.2007.357785
DO - 10.1109/ASPDAC.2007.357785
M3 - Conference contribution
AN - SCOPUS:46649109141
SN - 1424406293
SN - 9781424406296
T3 - Proceedings of the Asia and South Pacific Design Automation Conference, ASP-DAC
SP - 13
EP - 18
BT - Proceedings of the ASP-DAC 2007 - Asia and South Pacific Design Automation Conference 2007
T2 - ASP-DAC 2007 - Asia and South Pacific Design Automation Conference 2007
Y2 - 23 January 2007 through 27 January 2007
ER -