Plasma sources for EUV lithography exposure tools

Abstract

The source is an integral part of an extreme ultraviolet lithography (EUVL) tool. Such a source, as well as the EUVL tool, has to fulfil extremely high demands both technical and cost oriented. The EUVL tool operates at a wavelength in the range 13–14 nm, which requires a major re-thinking of state-of-the-art lithography systems operating in the DUV range. The light production mechanism changes from conventional lamps and lasers to relatively high temperature emitting plasmas. The light transport, mainly refractive for DUV, should become reflective for EUV. The source specifications are derived from the customer requirements for the complete tool, which are: throughput, cost of ownership (CoO) and imaging quality. The EUVL system is considered as a follow up of the existing DUV based lithography technology and, while improving the feature resolution, it has to maintain high wafer throughput performance, which is driven by the overall CoO picture. This in turn puts quite high requirements on the collectable in-band power produced by an EUV source. Increased, due to improved feature resolution, critical dimension (CD) control requirements, together with reflective optics restrictions, necessitate pulse-to-pulse repeatability, spatial stability control and repetition rates, which are substantially better than those of current optical systems. All together the following aspects of the source specification will be addressed: the operating wavelength, the EUV power, the hot spot size, the collectable angle, the repetition rate, the pulse-to-pulse repeatability and the debris induced lifetime of components.

Characterization and optimization of the laser-produced plasma EUV source at 13.5 nm based on a double-stream Xe/He gas puff target

“…The miniaturization in electronics strongly depends on the EUV technology progress acquiring powerful EUV light sources [2]. Recently, a growing number of compact EUV plasma sources have been developed including laser-produced plasmas (LPP) [3,4]. The EUV source for exposure tools for high-volume manufacturing basically has to meet industrial requirements of power in-band (at 13.5 nm within 2% BW) and may not have an impact on the lifetime of the reflective optics.…”

Critical Review of Current Trends in ASIC Writing and Layout Analysis

“…Several studies are ongoing to establish a stable light source for the Extreme UV lithography [7][8][9][10]. Laser Produced Plasma (LPP) system is used to produce short wavelength light by utilizing a high power laser to create high energy plasma that emits light inside a vacuum chamber.…”

Narrowband and tunable anomalous transmission filters for spectral monitoring in the extreme ultraviolet wavelength region

“…Thereby, even smaller changes in these conditions can lead to significant variations of the in-band power over time. This cannot be tolerated because maintaining a stable power in the 13.5 nm-band is crucial to avoid over or under-exposure of the resist leading to loss of resolution [9]. In-situ spectrally resolved monitoring of the power emitted across any relevant EUV ranges and, particularly, an output monitoring at 13.5 nm wavelength might then be used for a tight control of the plasma excitation parameters.…”