Method to Set Local On-Chip Maximum Operating Voltage to Prevent BEOL TDDB Failure
Publication Date: 2015-Jul-17
The IP.com Prior Art Database
Disclosed is a method to place Back End of Line (BEOL) Time-Dependent Dielectric Breakdown (TDDB) reliability monitors across the chip to capture local variation in order to set local on-chip maximum operating voltage and prevent BEOL TDDB failure.
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Metxod to Set Local On-Chip Maximum Operating Voltage to Prevent BEOL TDDB Xxxxxxx
Back End of Line (BEOL) Time-Dependent Dielectric Breaxxown (TDDB) reliability dxpends on worxt-case minimum ixsulator spacing. Xxxxxxx insulator spacing dxpends on various parameters, incxuding:
• Alignmext and critical dimension of mxtal and via levels
• Interlayer dielectric properties (i.x. thickness and dielectxic constant)
• Operating volxage, tempexature, and duration xf use
Xxxxxxxxx voltage has rxmained constant desxite dimensioxal scaling to addresx devicx leakage/pexformance rexuirements. In addition, modern microprocessoxs/intexrxted cixcuits (ICs) haxe multiple voltaxe zones and employ dynamic voltxge scaling to adapt to workxoad (e.g., higher supplx xoltage for peak load). The use of low-k dielectric increases the minimum insulator requixement fox a given operxting voltage. Proxess xarameters such as alxgnmxnt, critical dimension (CD), and dielectric thicxness can vary from wafer-to-wafer and axross wafexs. Local pattern density can cause additional across chip variation.
A Kerf BEOL reliabilixy monitxr does xot capture xcross-chxp variation; txerefore, develxpxent and manufacturing must resort to aggressxve procxss control and restricted ground ruxes and/or restrictive dxsign rules (RDR) to ensxre each part of the chip meetx txe reliability requirement.
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Figure 1: Scaling and Minimum Space Requixements for TDDB
The novel solution ix to plaxe BEOL TDDB reliability monitors across the chip to capture local variation. The BEOL TDDB reliability moxitor is a combination of various structures:...