Spectral feature selection and pulse timing control of a pulsed light beam

A method comprising:

• while producing a burst of pulses of an amplified light beam at a pulse repetition rate in response to a trigger signal, the amplified light beam supplied to a lithography exposure apparatus, driving a spectral feature adjuster among a set of discrete states, with each discrete state corresponding to a discrete value of the spectral feature of the amplified light beam;
• in between the production of the bursts of pulses and while no trigger signal is being received, driving the spectral feature adjuster;
• and
• ensuring that the spectral feature adjuster is in one of the discrete states that corresponds to a discrete value of the spectral feature of the amplified light beam when a pulse in the next burst is produced by adjusting a trigger inter-burst time interval such that an inter-burst time interval is an integer multiple of a time interval between pulses of the amplified light beam and adjusting one or more parameters associated with driving the spectral feature adjuster in between the production of the bursts of pulses based on an indication from the lithography exposure apparatus about the time at which it will request the production of the next burst.

A method comprising:

• while an optical source is producing a burst of pulses of an amplified light beam at a pulse repetition rate in response to a trigger signal, the amplified light beam supplied to a lithography exposure apparatus, driving a spectral feature adjuster among a set of discrete states based on a driving signal, with each discrete state corresponding to a discrete value of the spectral feature of the amplified light beam such that a pulse in the burst that is produced when the spectral feature adjuster is in one of the discrete states has a spectral feature that corresponds to that discrete state;
• in between the production of the bursts of pulses and while no trigger signal is being received, continuing to drive the spectral feature adjuster in a manner that is related to information received from the lithography exposure apparatus;
• and
• adjusting one or more of:
• an instruction to the lithography exposure apparatus, the driving signal to the spectral feature adjuster, and the instruction to the optical source to thereby produce a pulse in the next burst at the moment when the spectral feature adjuster is in one of the discrete states.

An apparatus comprising:

• an interface configured to communicate with a lithography exposure apparatus, and to receive information from the lithography exposure apparatus;
• a spectral feature adjuster;
• and
• an optical apparatus comprising an optical source and a control apparatus, the optical apparatus being in communication with the interface and the spectral feature adjuster, and configured to:
• using the optical source, produce a burst of pulses of an amplified light beam at a pulse repetition rate for use by the lithography exposure apparatus for patterning a substrate;
• while producing a burst of pulses of the amplified light beam at a pulse repetition rate in response to a trigger signal, the amplified light beam supplied to the lithography exposure apparatus, using the control apparatus, drive the spectral feature adjuster among a set of discrete states, with each discrete state corresponding to a discrete value of the spectral feature of the amplified light beam;
• in between the production of the bursts of pulses and while no trigger signal is being received, using the control apparatus, drive the spectral feature adjuster;
• and
• using the control apparatus, ensure that the spectral feature adjuster is in one of the discrete states that corresponds to a discrete value of the spectral feature of the amplified light beam when a pulse in the next burst is produced by one or more of:
• adjusting a trigger inter-burst time interval such that an inter-burst time interval is an integer multiple of a time interval between pulses of the amplified light beam;
• adjusting one or more parameters associated with driving the spectral feature adjuster in between the production of the bursts of pulses based on an indication from the lithography exposure apparatus about the time at which it will request the production of the next burst;
• delaying, for a period of time greater than zero, the production of the next burst of pulses relative to a request from the lithography exposure apparatus to produce the next burst of pulses;
• and
• sending a signal to the lithography exposure apparatus, the signal including information related to how the spectral feature adjuster is being driven in between the production of the bursts of pulses.