Pulsed plasmas have been proposed many years ago by research labs and have shown a great potential for etch process improvement. Nevertheless, they have been introduced in manufacturing only recently and the exact characteristics of pulsed plasmas in industrial scale reactors are hardly known. In this paper, we have characterized silicon etching in pulsed HBr/O2 plasmas using advanced plasma diagnostics (mass spectrometry and ion flux probe) in a 300 mm industrial reactor. We show that pulsing the plasma at low duty cycle reduces the gas molecules dissociation and plasma temperature, as well as the flux of energetic ions to the wafer. The ions during silicon etching are mostly silicon-containing ions that are heavier at low duty cycle. Silicon patterns etched using pulsed plasmas present improved profiles, which is attributed to more uniform passivation layers at low duty cycle.
Since more than 30 years, CW plasmas have been used in the microelectronics industry to pattern complex
stacks of materials involved in Integrated Circuit technologies. Even if miniaturization challenges have been successfully
addressed thanks to plasma patterning technologies, several fundamental limitations of the plasmas remain and are
limiting our ability to shrink further the device dimensions. In this work, we analyze the capabilities of synchronized
pulsed ICP technologies and their potential benefits for front end etch process performance.
The impact of duty cycle and frequency on the ion energy distribution function and plasma chemistry is
analyzed. Our results show that decreasing the duty cycle in ICP plasmas generates less fragmentation of the feed gas
stock molecules compared to CW plasmas, leading in final to a decrease of the radical density in the plasma. On a process point of view, we have studied the etching of ultra-thin layers (SiO2, HfO2,SiN spacer) involved in front end processes and investigated what synchronized pulsed plasmas could bring to substrate damage and selectivity issues.
We report the first experimental evidence for direct particle acceleration by stimulated emission of radiation (PASER)
namely, energy stored in microscopic cavities such as molecules, that otherwise may be used to amplify radiation, may
be directly utilized for acceleration of a train of electron micro-bunches. In the framework of this proof-of-principle
experiment, conducted at the Brookhaven National Laboratory, a 45MeV electron macro-bunch was modulated by its
interaction with a high-power CO2 laser pulse, within an adequate wiggler, and then injected into an excited CO2 gas
mixture. The emerging micro-bunches experienced a 0.15% relative change in the kinetic energy, in a less than 40cm
long interaction region. Both the fundamental frequency of the train of micro-bunches and the active medium main
resonance frequency are matched. This proof-of-principle experiment demonstrates, for the first time ever, the feasibility
of coherent collisions of the second kind i.e., a particle analog of the laser.
Conference Committee Involvement (2)
Commercial and Biomedical Applications of Ultrafast Lasers IX
25 January 2009 | San Jose, California, United States
Commercial and Biomedical Applications of Ultrafast Lasers VIII
20 January 2008 | San Jose, California, United States
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