Laser produced plasma EUV light source
View Patent ↗Methods and apparatus for producing EUV from plasma are disclosed. The apparatus includes a plasma generating system comprising a source of target material droplets and a laser producing a beam irradiating the droplets at an irradiation region. The plasma produces EUV radiation, wherein the droplet source comprises a nozzle having an orifice configured for ejecting a fluid and a sub-system having an electro-actuable element producing a disturbance in the fluid to cause at least some of the droplets to coalesce prior to being irradiated. The electro-actuable element is coupled to nozzle using an adhesive that has a high modulus at the nozzle operating temperature. Improvements also include tuning the nozzle assembly to more closely match the modulation waveform frequency with one of the resonance frequencies of the nozzle assembly by optimizing one of a mass, a shape, or material composition of at least one component in the nozzle assembly.
1. A plasma generating system comprising a source of target material droplets and a laser producing a beam irradiating the droplets at an irradiation region, the plasma producing EUV radiation, wherein the droplet source comprises a nozzle having an orifice configured for ejecting a fluid and a sub-system having an electro-actuable element producing a disturbance in the fluid to cause at least some of the droplets to coalesce prior to being irradiated, the electro-actuable element being coupled to nozzle using an adhesive having a modulus between 0.5 GPa and 5 GPa at a nozzle operating temperature between 240 degrees Celsius and 270 degrees Celsius.
2. The plasma generating system of claim 1 wherein said electro-actuable element is a piezoelectric modulator.
3. The plasma generating system of claim 1 wherein the disturbance comprises a frequency-modulated waveform.
4. The plasma generating system of claim 1 wherein the disturbance comprises an amplitude-modulated waveform.
5. The plasma generating system of claim 1 wherein the disturbance comprises a series of pulsed disturbances, with each pulsed disturbance of the series of pulsed disturbances having at least one of a sufficiently short rise-time and sufficiently short fall-time to generate a fundamental frequency and at least one harmonic of the fundamental frequency.
6. The plasma generating system of claim 1 wherein said adhesive is polyimide-based.
7. The plasma generating system of claim 1 wherein said adhesive is bismaleimide-based.
8. The plasma generating system of claim 1 wherein said adhesive includes a mixture of resin and particles of solid material.
9. The plasma generating system of claim 8 wherein said particles of solid material represent microparticles of one of silver, silica, or alumina.
10. The plasma generating system of claim 8 wherein said particles of solid material comprise about 20% to 90% of the total volume.