Zhou G.,Zhejiang Agriculture And forestry University |
Chen R.,Zhejiang Sci-Tech University |
Ru G.,ASML Inc
Laser Physics Letters | Year: 2014
An analytical expression of an Airy beam propagating in a strongly nonlocal nonlinear media is derived. The analytical expressions of the corresponding characteristic parameters for the Airy beam, such as the centre of gravity, the effective beam size, the curvature radius, the kurtosis parameter, and the linear momentum, have also been presented, respectively. The normalized intensity distribution and these characteristic parameters are pictorially demonstrated in the strongly nonlocal nonlinear media, respectively. It shows all the characteristic parameters versus the axial propagation distance are periodic. The period of the linear momentum versus the axial propagation distance is T = 2πz0/η The period of other characteristic parameters and the normalized intensity is T = πz0/η. The periodic behavior of the Airy beam in the strongly nonlocal nonlinear media has promising application in optical switch and optical micromanipulation. © 2014 Astro Ltd.
Butler H.,ASML Inc
IEEE Transactions on Control Systems Technology | Year: 2013
The wafer stage and reticle stage in a lithographic tool, used to manufacture integrated circuits (ICs), operate at nanometer accuracy during a scanning motion. The position accuracy and settling time after accelerating to the scanning velocity are largely determined by the feedforward controller. The feedforward controller calculates the required force for the stage to move according to its position profile by multiplying the reference acceleration with the known stage mass. Two effects limit the accuracy directly after the acceleration phase. First, the actual stage acceleration in response to the controller-calculated force depends on the position of the stage in its working range. A variation of 0.1% is observed. Second, dynamic resonances in the stage response require a higher-order feedforward model. Combined, these effects result in a 20-30 nm peak position error. This brief investigates online adaptation of the feedforward mass parameter, with the aim of reducing the position-dependent stage behavior. Adaptation of only the feedforward mass is shown not to be able to compensate for stage dynamics, additionally requiring a higher-order feedforward element. From the control force and the measured motion response, the feedforward mass parameter is estimated on line. Least-squares estimation is fast enough to update the mass parameter during the acceleration phase, which takes less than 100 ms. This brief addresses a number of practical aspects and shows that adaptive feedforward estimation in combination with higher-order feedforward reduces the peak position error consistently by creating position-independent behavior. © 1993-2012 IEEE.
Finders J.,ASML Inc
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014
With Critical Dimension Uniformity requirements in optical lithography getting tighter and tighter, phenomena that previously could be ignored now need a detailed understanding and control strategy. Amongst those are the effects introduced by the finite height of the mask absorber (Mask 3D) and the finite resist height (Resist 3D). We will explain them by analyzing wafer Critical Dimension (CD) data through focus and dose and categorizing those using simple figures of merit: Best focus differences between features, Bossung tilt through focus and sidewall angle through dose. We will study the phenomena and show a methodology and gauges to discriminate between Mask 3D and Resist 3D. This will enable the end-user to judge the effects, which are highly application dependent, and choose to put the effort for future nodes either on Mask 3D or Resist 3D or both. In the second part we will focus on the solutions. The main focus is on immersion lithography we but will show the extendibility of some of the work to EUV. © 2014 SPIE.
Butler H.,ASML Inc
IEEE Control Systems Magazine | Year: 2011
Lithographic steppers and scanners are highly complex machines used to manufacture integrated circuits (ICs). These devices use an optical system to form an image of a pattern on a quartz plate, called the reticle, onto a photosensitive layer on a substrate, called the wafer. The circular wafer, having a diameter of 200 or 300 mm, is usually made of silicon. Since one wafer can contain many ICs, typically 100 or more, the wafer needs to be repositioned from exposure to exposure. Exposure itself takes place during a scanning motion of the wafer and the reticle. © 2011 IEEE.
Van Den Brink M.,ASML Inc
Digest of Technical Papers - IEEE International Solid-State Circuits Conference | Year: 2013
Chip makers are increasingly concerned about the shrink and cost. This concern drives different lithography solutions for different products. Two major trends can be observed: aggressive adoption of EUV, or aggressive extension of immersion. Further cost reduction could be achieved by introducing 450mm wafers. © 2013 IEEE.