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In order to reduce resistance-capacitance (RC) delay of back-end-of-line (BEOL), a low-dielectric constant (low-k) material with the dielectric constant (k) below 4.0 has been introduced to be used as an insulator of Cu integration from 130 nm technological node. In this study, the electrical and reliability characteristics of various commercial low-k dielectric films with k value ranging from 3.6~2.5 deposited using plasma-enhanced chemical vapor deposition (PECVD) were investigated. In addition to FSG and dense OSG low-k dielectric films, porous OSG (P-OSG) films with two different sacrificial organic porogen precursors (alpha terpinene (ATRP) and cyclooctane (C8H16) were also compared. Although P-OSG films have a low k value, their resistance to the process integration is relatively low, resulting in a higher increase of k value and a degraded reliability performance as compared to OSG film. Hence, it is doubtable to use porous OSG films with a higher porosity in the following advanced technology nodes. Furthermore, the sacrificial porogen precursor used for porous OSG film deposition influences the film’s property. The P-OSG film for ATRP precursor has a better mechanical, electrical, and reliability characteristics as compared to that for C8H16 precursor in this study.

Localizing a tiny fault causing abnormal leakage current in a large area P/N junction for a large MOS, diode or BJT structure by nano-probing was demonstrated. The localization was realized through probing the contacts on the junctions and comparing the reversed bias junction current for each contact which maintain the same polarity on the P/N junction. The tiny fault location which is causing the leakage in the large area P/N junction is indicated by the contact with the largest current due to the lowest sheet row resistance path to the fault as measured by nano-probing. Therefore, the success rate to identify the real physical fault by TEM and the ability to take the precise process action to correct the problem is greatly increased by this method. An artificial fault experiment induced by use of FIB as well as real case studies also verifies this method is valid and useful.