ASML Holding

About: ASML Holding is a company organization based out in Veldhoven, Netherlands. It is known for research contribution in the topics: Substrate (printing) & Extreme ultraviolet lithography. The organization has 5170 authors who have published 5078 publications receiving 59255 citations. The organization is also known as: ASM Lithography & ASML.

Data-based feed-forward control in MIMO motion systems

Abstract: For MIMO motion systems, a data-based feedforward control is derived and implemented on a wafer stage of a wafer scanner. On the basis of a quadratic objective function related to a performance-relevant time-frame of the servo error signals, the coefficients of a set of finite impulse response (FIR) filters are optimized using a Gauss-Newton method. Applied to the wafer stage both the optimization algorithm and the FIR filter structure provide the means to significantly improve upon scanning performance. This includes improved settling behavior, the reduced effect of cross talk by MIMO feedforward forces, and the generalizing properties of these forces at set-points other than for which is optimized.

Control of Wafer Scanners: Methods and Developments

Abstract: In this tutorial paper, control design aspects of wafer scanners used in the semiconductor industry will be highlighted. At the same time, challenges for control design development as to meet the ever increasing demands on accuracy and speed are presented. Mechatronic systems that will be discussed are: (a) the light source needed to generate the ultraviolet light that is used for wafer exposure, (b) the optical and metrology systems needed for accurate measurement and imaging, and (c) the reticle and wafer stage systems needed for accurate and fast positioning. The control challenges associated with these systems mainly involve dealing with: (a) rejection of high frequency aliased disturbances, (b) large-scale or fast-updated (state) reconstruction, (c) vibration control and isolation in view of structural vibrations and disturbances, (d) inherent design tradeoffs like Bode's sensitivity integral and gain-phase relationships, (e) multivariable plant identification of (quasi-static) deformations and structural dynamics for point-of-interest control, and (f) thermal modelling, model reduction, and the control of (local) time-varying deformation. Results will be discussed using representative examples.

Immersion specific defect mechanisms: findings and recommendations for their control

Abstract: Defectivity has been one of the largest unknowns in immersion lithography. It is critical to understand if there are any immersion specific defect modes, and if so, what their underlying mechanisms are. Through this understanding, any identified defect modes can be reduced or eliminated to help advance immersion lithography to high yield manufacturing. Since February 2005, an ASML XT:1250Di immersion scanner has been operational at IMEC. A joint program was established to understand immersion defectivity by bringing together expertise from IMEC, ASML, resist vendors, IC manufactures, TEL, and KLA-Tencor. This paper will cover the results from these efforts. The new immersion specific defect modes that will be discussed are air bubbles in the immersion fluid, water marks, wafer edge film peeling, and particle transport. As part of the effort to understand the parameters that drive these defects, IMEC has also developed novel techniques for characterizing resist leaching and water uptake. The findings of our investigations into each immersion specific defect mechanism and their influencing factors will be given in this paper, and an attempt will be made to provide recommendations for a process space to operate in to limit these defects.

A study of swing-curve physics in diffraction-based overlay

Abstract: With the increase of process complexity in advanced nodes, the requirements of process robustness in overlay metrology continues to tighten. Especially with the introduction of newer materials in the film-stack along with typical stack variations (thickness, optical properties, profile asymmetry etc.), the signal formation physics in diffraction-based overlay (DBO) becomes an important aspect to apply in overlay metrology target and recipe selection. In order to address the signal formation physics, an effort is made towards studying the swing-curve phenomena through wavelength and polarizations on production stacks using simulations as well as experimental technique using DBO. The results provide a wealth of information on target and recipe selection for robustness. Details from simulation and measurements will be reported in this technical publication.

Method of determining a measurement subset of metrology points on a substrate, associated apparatus and computer program

Abstract: A method of determining a measurement subset of metrology point locations which includes a subset of potential metrology point locations on a substrate. The method including identifying a plurality of candidate metrology point locations from the potential metrology point locations. A change in the level of informativity imparted by the measurement subset of metrology point locations which is attributable to the inclusion of that candidate metrology point location into the measurement subset of metrology point locations is evaluated for each of the candidate metrology point locations. The candidate metrology point locations which have the greatest increase in the level of informativity attributed thereto are selected for inclusion into the measurement subset of metrology point locations.