1. A lithographic apparatus comprising:
a radiation source configured to produce extreme ultraviolet radiation, the radiation source including
a chamber in which a plasma is generated;
a mirror configured to reflect radiation emitted by the plasma, the mirror including a multi-layer structure including alternating MoSi layers, wherein a boundary Mo layer or a boundary Si layer or a boundary diffusion barrier layer of the alternating layers forms a top layer of the mirror, the top layer facing inwardly with respect to the chamber; and
a hydrogen radical generator configured to generate hydrogen radicals in the chamber, the hydrogen radicals configured to remove debris generated by the plasma from the mirror;
a support constructed and arranged to support a patterning device, the patterning device being configured to pattern the extreme ultraviolet radiation to form a patterned beam of radiation; and
a projection system constructed and arranged to project the patterned beam of radiation onto a substrate.
2. The apparatus of claim 1, wherein the mirror forms a part of a multi-layer collector mirror.
3. The apparatus of claim 1, wherein the debris comprises tin particles.
4. The apparatus of claim 1, wherein the radiation source is a laser produced plasma source.
5. The apparatus of claim 1, wherein the radiation source is a discharge produced plasma source.
6. The apparatus of claim 1, wherein hydrogen having a pressure of about 100 Pa is supplied to the chamber.
7. The apparatus of claim 1, wherein the mirror is free of a capping layer.
8. The apparatus of claim 1, wherein the multi-layer structure including alternating MoSi layers, is provided with at least one diffusion barrier layer.
9. The apparatus of claim 8, wherein the diffusion barrier includes B4C.
10. A radiation source configured to produce extreme ultraviolet radiation, the radiation source comprising:
a chamber in which a plasma is generated;
a mirror configured to reflect radiation emitted by the plasma, the mirror including a multi-layer structure including alternating MoSi layers, wherein a boundary Mo layer or a boundary Si layer or a boundary diffusion barrier layer of the alternating layers forms a top layer of the mirror, the top layer facing inwardly with respect to the chamber; and
a hydrogen radical generator configured to generate hydrogen radicals in the chamber, the hydrogen radicals configured to remove debris generated by the plasma from the mirror.
11. The radiation source of claim 10, wherein the mirror forms a part of a multi-layer collector mirror.
12. The radiation source of claim 10, wherein the debris comprises tin particles.
13. The radiation source of claim 10, wherein the radiation source is a laser produced plasma source.
14. The radiation source of claim 10, wherein the radiation source is a discharge produced plasma source.
15. The radiation source of claim 10, wherein hydrogen having a pressure of about 100 Pa is supplied to the chamber.
16. The radiation source of claim 10, wherein the mirror is free of a capping layer.
17. The radiation source of claim 10, wherein the multi-layer structure including alternating MoSi layers, is provided with at least one diffusion barrier layer.
18. The radiation source of claim 17, wherein the diffusion barrier includes B4C.
19. A device manufacturing method comprising:
generating a plasma that emits a beam of radiation;
reflecting the beam of radiation with a mirror, the mirror including a multi-layer structure including alternating MoSi layers, wherein a boundary Mo layer or a boundary Si layer or a boundary diffusion barrier layer of the alternating layers forms a top layer of the mirror, the top layer facing inwardly with respect to the chamber;
directing the beam of radiation onto a target portion of a substrate; and
removing debris produced by the plasma from a surface of the mirror with hydrogen radicals.
20. A mirror cleaning method, comprising:
removing debris using hydrogen radicals from a mirror that is arranged for reflecting a beam of extreme ultraviolet radiation emitted by a plasma in a chamber, the mirror including a multi-layer structure including alternating MoSi layers, wherein a boundary Mo layer or a boundary Si layer or a boundary diffusion barrier layer of the alternating layers forms a top layer of the mirror, the top layer facing inwardly with respect to the chamber.
21. The mirror cleaning method according to claim 20, further comprising removing debris from the top layer of the mirror.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A process for generating stimuli for use in a cochlear implant, including the steps of:
receiving an audio signal and processing it so as to define signals within each of a set of frequency channels;
determining the peaks in each of said signals, including the time of each peak and its intensity;
prioritising each of said peaks according to a predetermined instruction set,
placing each peak, in order of priority, into a buffer in a time slot corresponding to the time of the peak in said channel; and
outputting a set of data for use in generating stimulus instructions from said buffer.
2. An cochlear implant device, including
a filter for receiving an audio signal and processing it so as to define signals within each of a set of frequency channels;
processing means adapted to determine the peaks in each of said signals, including the time of each peak and its intensity, and to prioritise each of said channels in response to a predetermined instruction set;
said processing means further placing each peak, in order of priority, into a buffer, so that each peak is placed into a time slot corresponding to the time of the peak in said channel, the output of said buffer being used in generating stimulus instructions for said device.
3. A binaural cochlear implant system, including two intracochlear implants adapted for implantation in the cochleas of a user, each of said cochlear implants utilising a speech processing strategy wherein the electrical stimuli are matched to the relative timing of the relevant audio signals as detected at each ear, such that the interaural time delays between the audio signals at each ear are substantially preserved in electrical stimuli at each ear.
4. A process according to claim 1, wherein said predetermined instruction set includes an arbitration scheme to be applied when peaks occur on more than one channel within the same sampling period, said arbitration scheme being such that up to a predefined frequency channel, priority is given to low frequency channels over high frequency channels unless the higher frequency channel has an amplitude which is larger by a predefined amount than the lower channel, and wherein for channels higher than the predefined channel, priority is given only on the basis of low frequency channels over high frequency channels, and wherein if no appropriate time slot is available for lower priority channels, the peak on that channel is discarded.
5. A process according to claim 1, wherein said predetermined instruction set includes a rate limitation method, wherein a minimum time interval between peaks on each channel is specified, and peaks occurring within said interval are discarded.
6. A process according to claim 1, wherein the output data is such that stimuli are presented at electrodes in an order which corresponds to the order of the corresponding peaks in the audio signal.
7. A process according to claim 6, wherein the stimuli are further presented with a relative timing which substantially corresponds to the timing of the corresponding peaks in the audio spectrum.
8. A process for generating stimuli for use in a cochlear implant, including the steps of:
receiving an audio signal and processing it so as to define signals within each of a set of frequency channels;
determining the peaks in each of said signals, including the time of each peak and its intensity;
applying an arbitration scheme when peaks occur in more than one channel within the same sampling period; and
outputting a set of data for use in generating stimulus instructions from said buffer,
characterised in that said arbitration scheme operates so that up to a predefined frequency channel, priority is given to low frequency channels over high frequency channels unless the higher frequency channel has an amplitude which is larger by a predefined amount than the lower channel, and wherein for channels higher than the predefined channel, priority is given only on the basis of low frequency channels over high frequency channels, and wherein if no appropriate time slot is available for lower priority channels, the peak on that channel is discarded.
9. A process according to claim 6, wherein said process further includes a rate limitation step applied after the peaks have been determined, wherein a minimum time -interval between peaks on a channel is specified, and peaks occurring within said interval are discarded.