Cymer, Inc.

Rahul Ahlawat

Kevin M O'Brien

Tanuj Aggarwal

Kuo-Tai Teng

Thomas Patrick Duffey

Joshua Jon Thornes

Gamaralalage G Padmabandu

Edward Siqi Luo

Piraj Fozoonmayeh

Apparatus for and method of controlling a laser system capable of generating bursts of pulses of laser radiation having multiple alternate wavelengths in which an element controlling the wavelength is pre-positioned between bursts to be between its position for generating one wavelength and its position for generating another wavelength. Also disclosed is a system that determines an optimal control waveform for the element to move between positions using quadratic programming, dynamic programing, inversion feed forward control, or iterative learning control. A data storage device such as a pre-populated lookup table or a field programmable gate array may be used to store at least one optimal control parameter for each of a plurality of repetition rates.

Apparatus for and method of modulating a light source wavelength

A radiation system for controlling pulses of radiation comprising an optical element configured to interact with the pulses of radiation to control a characteristic of the pulses of radiation, an actuator configured to actuate the optical element according to a control signal received from a controller, the control signal at least partially depending on a reference pulse repetition rate of the radiation system and, a processor configured to receive pulse information from the controller and use the pulse information to determine an adjustment to the control signal. The radiation system may be used to improve an accuracy of a lithographic apparatus operating in a multi-focal imaging mode.

Method of compensating wavelength error induced by repetition rate deviation

An apparatus includes: a gas maintenance system having a gas supply system fluidly connected to one or more gas discharge chambers; a detection apparatus fluidly connected to each gas discharge chamber; and a control system connected to the gas maintenance system and the detection apparatus. The detection apparatus includes: a vessel defining a reaction cavity that houses a metal oxide and is fluidly connected to the gas discharge chamber for receiving mixed gas including fluorine from the gas discharge chamber in the reaction cavity, the vessel enabling a reaction between the fluorine of the received mixed gas and the metal oxide to form a new gas mixture including oxygen; and an oxygen sensor fluidly connected to the new gas mixture to sense an amount of oxygen within the new gas mixture. The control system is configured to estimate a concentration of fluorine in the received mixed gas.

Fluorine detection in a gas discharge light source

A wavelength error for each pulse in a first subset of pulses emitted from an optical source is determined, the wavelength error being the difference between a wavelength for a particular pulse and a target wavelength; a pulse-by-pulse correction signal is determined based on the determined wavelength error, the pulse-by-pulse correction signal including a correction signal associated with each pulse in the first subset of pulses; and a correction based on the determined pulse-by-pulse correction signal is applied to each pulse in a second subset of pulses emitted from the optical source, where applying a correction to a pulse in the second subset of pulses reduces the wavelength error of the pulse in the second subset of pulses.

Wavelength stabilization for an optical source

Wafer positioning errors in stepper-scanners contribute to imaging defects. Changing the wavelength of the light source's generated light can compensate for wafer positional errors in the Z-direction. The wafer's real-time z-position is determined and a change in wavelength target to offset this error is communicated to the light source. The light source uses this change in wavelength target in a feed-forward operation and, in an embodiment, in combination with existing feedback operations, on a pulse-by-pulse basis for subsequent pulses in a current burst of pulses in addition to receiving the newly-specified laser wavelength target for a subsequent burst of laser pulses.

Wavelength control system for pulse-by-pulse wavelength target tracking in DUV light source

A gas discharge light source includes a gas discharge system that includes one or more gas discharge chambers. Each of the gas discharge chambers in the gas discharge system is filled with a respective gas mixture. For each gas discharge chamber, a pulsed energy is supplied to the respective gas mixture by activating its associated energy source to thereby produce a pulsed amplified light beam from the gas discharge chamber. One or more properties of the gas discharge system are determined. A gas maintenance scheme is selected from among a plurality of possible schemes based on the determined one or more properties of the gas discharge system. The selected gas maintenance scheme is applied to the gas discharge system. A gas maintenance scheme includes one or more parameters related to adding one or more supplemental gas mixtures to the gas discharge chambers of the gas discharge system.

Gas mixture control in a gas discharge light source

A system includes a first actuation module coupled to a first actuatable apparatus of an optical source, the first actuatable apparatus being altered by the first actuation module to adjust the spectral feature of the pulsed light beam; a second actuation module coupled to a second actuatable apparatus of the optical source, the second actuatable apparatus being altered by the second actuation module to adjust the spectral feature of the pulsed light beam; and a control system configured to receive an indication regarding the operating state of the first actuatable apparatus; and send a signal to the second actuation module to adjust the spectral feature of the pulsed light beam to either: prevent the first actuatable apparatus from saturating based on the operating state of the first actuatable apparatus, or desaturate the first actuatable apparatus if the first actuatable apparatus is saturated.

Pulsed light beam spectral feature control

A system includes a first actuatable apparatus of an optical source, the first actuatable apparatus being altered within a range of values about a target value to thereby alter a spectral feature of the light beam; a second actuatable apparatus of the optical source, the second actuatable apparatus being altered to thereby alter the spectral feature of the light beam; a metrology system including an observation system configured to output an indication of a deviation between the actual value at which the first actuatable apparatus is operating and the target value; and a control system configured to determine whether the deviation is greater than an acceptable deviation, and, if it is greater than the acceptable deviation, then send a signal to a second actuation module controlling the second actuatable apparatus to adjust the actual value at which the first actuatable apparatus is operating to be closer to the target value.

A pulsed light beam emitted from an optical source is received, the pulsed light beam being associated with a temporal repetition rate; a frequency of a disturbance in the optical source is determined, the frequency being an aliased frequency that varies with the temporal repetition rate of the pulsed light beam; a correction waveform is generated based on the aliased frequency; and the disturbance in the optical source is compensated by modifying a characteristic of the pulsed light beam based on the generated correction waveform.

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San Diego, CA, United States of America

Rahul Ahlawat