Spectral scatterometry for 2D trench metrology of low-K dual-damascene interconnect

Abstract

phone 1 972 995-4463; fax 1 972 995-2770 Texas Instruments Incorporated, PO BOX 650311, MS3735, Dallas, TX 75265. ABSTRACTA systematic study has been conducted to evaluate accuracy and precision of spectral scatterometry used for twodimensional (2D) characterization of trenches formed in fluorinated silicon glass (FSG). Experiments were done on short-flow dual-damascene Cu interconnect material. Trench critical dimensions (CD) obtained using KLA-Tencor's spectral scatterometer were correlated with data collected using CD atomic force microscope (AFM), CD scanning electron microscope (SEM) and transmission electron microscope (TEM). 3 major trench characteristics were analyzed: trench width, trench depth and sidewall angle. Spectral scatterometry demonstrated an excellent correlation (above 0.96) with CD AFM and SEM in tested trench width range of (80-240) nm and trench depth range of (410-450) nm. Spectral scatterometry showed acceptable correlation of 0.55 and minimal offset of 0.05º with AFM in tested sidewall angle range of (87.5-89) degrees. Spectral scatterometry has demonstrated better than 1.0 nm and 0.2º dynamic precision (3σ) for both width and height and sidewall angle, respectively. We conclude that KLA-Tencor's SpectraCD system is capable of accurate and precise 2D characterization of FSG trenches. We recommend scatterometry as a high throughput and non-destructive metrology for trench linewidth and depth monitoring in low-K dielectric interconnect manufacturing.

Characterization and Control of Etch Processes Using Multiple Metrologies

“…Scatterometry has been very successfully applied to CD measurements of polysilicon gates, back-end trench layers, and lithography applications [7,8,9]. The fast MAM times are a natural advantage for inline measurements, especially relative to the profilometer method.…”

Immersion scatterometry for improved feature resolution and high speed acquisition of resist profiles

“…1,2,3,4,5,6,7 Integrated metrology variations have been demonstrated for wafer-to-wafer feedfoward and feedback control of photolithography and reactive ion etch steps. 8,9,10 University research demonstrations have used both SR 5,11 and SE 12 for both ex situ, detailed topography extraction and in a real-time, in situ mode to monitor the evolution of topography in reactive ion etch systems during oxygen-plasma trim-back of photoresist lines, the evolution of shallow trenches in crystalline Si, and the etching of poly-Si gate test structures.…”