Browsing by Author "Chang, KP"

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Characterization of self-assembled InAs quantum dots with InAlAs/InGaAs strain-reduced layers by photoluminescence spectroscopy
(2005-04-15)
Chang, KP
;
Yang, SL
;
Chuu, DS
;
Hsiao, RS
;
Chen, JF
The optoelectronic characteristics of self-assembled InAs quantum dots (QDs) with strain-reduced layers (SRLs) were investigated using photoluminescence (PL) spectroscopy. Various SRLs that combine In0.14Al0.86As and In0.14Ga0.86As with the same total thickness were examined to ascertain their confining effect on carriers in InAs QDs. The emission wavelength is blueshifted as the thickness of InAlAs is increased. The energy separation between the ground state and the first excited state of QDs with InAlAs SRLs greatly exceeds that of QDs with InGaAs SRLs. Atomic force microscopic images and PL spectra of the QD samples demonstrated that high-quality InAs QDs with long emission wavelengths and a large energy separation can be generated by growing a low-temperature, thin InAlAs SRL onto self-assembled QDs. (C) 2005 American Institute of Physics.
Copper interconnect electromigration behavior in various structures and precise bimodal fitting
(2006-02-01)
Lin, MH
;
Lin, YL
;
Chang, KP
;
Sul, KC
;
Wang, TH
Copper interconnect electromigration (EM) was examined in various structures and three low-k materials (k = 2.65-3.6) using advanced back-end-of-line (BEOL) technology. Various structures for testing were designed to identify the EM failure modes, and extensive failure analysis was carried out to reveal failure in the test structures. A strong current dependence of the electromigration lifetime in three-level via-terminated metal lines was shown. Moreover, different processing approaches lead to different EM behaviors and related failure modes. The weak links of the interconnect system were identified by evaluating various test structures. Multimodality in the electromigration behavior of Cu dual-damascene interconnects was studied. Both superposition and weak-link models were used for the statistical determination of lifetimes of each failure model (statistical method). Results correlated to the lifetimes of the respective failure models physically identified according to resistance time evolution behavior (physical method). A good agreement was achieved. The activation energies of failure modes were calculated. Results of this study suggest that the interface of Cu interconnects is the key factor in EM performance.
Electromigration lifetime improvement of copper interconnect by cap/dielectric interface treatment and geometrical design
(2005-12-01)
Lin, MH
;
Lin, YL
;
Chen, JM
;
Yeh, MS
;
Chang, KP
A significant improvement of electromigration (EM) lifetime is achieved by modification of the preclean step before cap-layer deposition and by changing Cu cap/dielectric materials. A possible mechanism for EM lifetime enhancement was proposed. Cu-silicide formation prior to cap-layer deposition and adhesion of Cu/cap interface were found to be the critical factors in controlling Cu electromigration reliability. The adhesion of the Cu/cap interface can be directly correlated to electromigration median-time-to-failure and activation energy. Effects of layout geometrical variation and stress current direction were also investigated.