Improved understanding of metal ion reservoirs within barrier-metal systems

Within integrated circuits there are many instances where low current densi ty lines feed directly (without a via) into a single line of much higher cu rrent density, for example with clock or power supply distribution. This wo rk demonstrates and discusses increased lifetime with increasing numbers of current feed lines in a barrier metal interconnect system. The low current density feed lines (branches) act as reservoirs or sources of additional A l and Cu ions, which can re-fill portions of voids and/or slow void growth in the high current density line (trunk). it is discussed that any area of metal at a lower current density might be considered a reservoir or source of metal ions for higher current density regions, and can effectively exten d the lifetime of the higher current density region. Narrow lines may get m ore benefit than wide lines. Increasing reservoir size will increase lifeti me, within limits. (C) 2001 Elsevier Science Ltd. All rights reserved.