HighbrightnessLPPEUVsourcefor% metrologyapplicaons · HighbrightnessLPPEUVsourcefor%...
1
High brightness LPP EUV source for metrology applica:ons Konstan’n Koshelev 1,2 , Alexander Vinokhodov 1 , Mikhail Krivokorytov 1 , Yuri Sidelnikov 2 , Oleg Yakushev 1 , Samir Ellwi* 3 , Denis Glushkov 3 , Pavel Seroglazov 3 1 – RnD-ISAN/EUV Labs, Troitsk, 142190 Russia; 2 – Institute for Spectroscopy RAS, Troitsk, 142090 Russia; 3 – ISTEQ, 5656 AG Eindhoven * – [email protected] Mo:va:on An inspec’on tool is needed to provide feedback on any defects at each semiconductor manufacturing process step. Indeed, inspec’on at the ac’nic wavelength is required in order to detect defects on EUVL photomasks that would otherwise print onto wafers. Metrology tools include Ac’nic Blank Inspec’on (ABI), Ac’nic PaTern Inspec’on (API) and Aerial Image Measurement System (AIMS), which all require high brightness. There are some essen’al parameters needed from the EUV source to fulfil mask inspec’on requirements. Examples of these requirements are; firstly, source brightness, this is necessary due to the limited sensi’vity of imaging sensors. Hence, the need for high throughput is cri’cal for inspec’on. Secondly, metrology tools have a specific requirement regarding energy stability, which is mainly driven by the need to resolve the required cri’cal dimension (CD). CONCLUSIONS 1. The droplet generator based on induced Rayleigh jet breakup was developed. 2. The high droplet posi:on stability and mass uniformity was demonstrated both in short & long term opera:on. 3. The flexibility of opera:on regimes (droplet diameter, velocity and frequency) was demonstrated. 4. Two types of jet modula:on was developed: piezo in hot zone, which limits an opera:on temperature (250˚C), and waveguide with piezo at room temperature, which allows to operate at higher temperatures. 5. Was shown that such DG can be used for high brightness and high stability LPP EUV source. The work was supported by the Ministry of Educa’on and Science of the Russian Federa’on under the Agreement № 14.579.21.0004 (a unique iden’fier for Applied Scien’fic Research (project) RFMEFI57914X0004). Droplet target parameters: Parameter Value (Std %) Pulse energy, mJ 100 (9.9 %) Pulse width, ns 28 (8.1 %) Peak intensity, MW 2 (10.9 %) Focal spot size (FWHM) 50 um Average power density at focal spot, W/cm 2 1.8*10 11 (13 %) Laser parameters: 4˚ GIS spectrometer; I, II, III – diffrac’on orders laser Xray photodiode 720 um Source size ~ 100 um (FWHM) Plasma image inband EUV by pinhole camera EUV pulsetopulse stability can be improved via improving laser parameters: energy pulse, poin:ng and pulse dura:on stability X Y CE 2π = 2.3 % ε Ωinband = 4.2*10 4 J/Sr Scaling law for brightness B 13.5 ≈ 0.5 W/mm 2 Sr (10 Hz); B 13.5 ≈ 50 W/mm 2 Sr (1 kHz); B 13.5 ≈ 400 W/mm 2 Sr (8 kHz) The key requirements for the Ac:nic inspec:on tool: • High brightness (>100 W/mm 2 /sr) • Stability of plasma posi:on < 3% of FWHM* • Energy stability < 3.5% (3σ) pulsetopulse • Cleanliness 100% (debris containment must be included in the source) • Availability / Reliability * The posi’onal stability requirement varies depending on source characteris’cs and the illumina’on concept. Source requirements Classical :n DG approach Lithium jet approach Diameter, um 70 Temperature, K 413 Material Sn/In XY posi’on Std, um σ x ≈σ y ≈ 0.5 um Proof of concept with 10 Hz Nd:YAG laser Emission spectrum, plasma size and brightness Examples of DG opera:on High brightness can be achieved Correla:on of EUV and laser pulse energies Jet approach provides extreme stability, renewable and infinite in space target Conversion efficiency (Peak values) 4 th Interna’onal EUVL symposium, 2005 Lithium has rela:vely high conversion efficiency and number of advantages, which makes it highly arrac:ve for the ac:nic source development: • Li produces narrow inband spectral emission and low ultravioletvisible outof band radia’on • No spectral purity filter needed • Lithium has low ion energy intensity • Debris mi’ga’on is considerably less in comparison to Tin, which in turn gives longer component life’me • No opening of the vacuum chamber is needed 1. Li target has no debris in comparison to the Sn target: due to “closed LPP chamber” design using selfcleaning radia:on input and output windows. 2. Long source life:me: EUV op:cs placed outside the LPP chamber. 3. High spectral purity: usage of Li plasma with narrow “inband” line spectra, concentrated at 13.5nm. 4. High EUV dose stability: provided by stable posi:on of the target and its infinite size. 5. Long (infinite) duty cycle: provided by con:nuous opera:on of liquid lithium pump. Advantages of lithium target Nozzle: 30 um Modula’on frequency: 40 kHz Pressure: 5 bar Droplet diameter: 46 um Droplet velocity: 7 m/s Droplet diameter range: 4565um Droplet diameter STD: 1% Center of mass displacement: σ x = 0.5 um; σ y = 0.8 um High target posi:on stability ISTEQ and RnDISAN have developed a new concept of a compact highbrightness lithium EUV source: to Li pump Drive laser input window EUV light output window LPP plasma λ = 13.5nm f = up to 10kHz B = up to 1kW/mm 2 *sr Li stream from the pump Source components : • Target: con’nuous Li liquid jet • Drive laser: Nd:YAG, 1.06um, up to 10 kHz, 1 kW [to be selected] • Selfcleaning Input and Output windows • Recycling target system Main source parameters: • Wavelength: 13.5nm • Brightness: up to 1kW/mm 2 sr • Frequency: up to 10kHz • Collectable inband power: >60mW • Etendue: 2410 5 mm 2 sr Preliminary experiments have been successfully performed and the feasibility of the approach has been proved. Unique hardware has been developed and tested, making the technology ready for implementa:on: Lithium jet EUV brightness: up to 1 kW/mm 2 sr Centrifugal pump for genera’on of liquid lithium jet was tested under varying condi’ons, up to 200 hours in nonstop regime at temperature of 350℃ Liquid lithium pump CE mean:2.3% CE std: 0.1%
Transcript of HighbrightnessLPPEUVsourcefor% metrologyapplicaons · HighbrightnessLPPEUVsourcefor%...
High brightness LPP EUV source for metrology applica:ons
Konstan'n Koshelev1,2, Alexander Vinokhodov1, Mikhail Krivokorytov1, Yuri Sidelnikov2, Oleg Yakushev1, Samir Ellwi*3, Denis Glushkov3, Pavel Seroglazov3
1 – RnD-ISAN/EUV Labs, Troitsk, 142190 Russia; 2 – Institute for Spectroscopy RAS, Troitsk, 142090 Russia; 3 – ISTEQ, 5656 AG Eindhoven * – [email protected]
Mo:va:on An inspec'on tool is needed to provide feedback on any defects at each semiconductor manufacturing process step. Indeed, inspec'on at the ac'nic wavelength is required in order to detect defects on EUVL photomasks that would otherwise print onto wafers. Metrology tools include Ac'nic Blank Inspec'on (ABI), Ac'nic PaTern Inspec'on (API) and Aerial Image Measurement System (AIMS), which all require high brightness. There are some essen'al parameters needed from the EUV source to fulfil mask inspec'on requirements. Examples of these requirements are; firstly, source brightness, this is necessary due to the limited sensi'vity of imaging sensors. Hence, the need for high throughput is cri'cal for inspec'on. Secondly, metrology tools have a specific requirement regarding energy stability, which is mainly driven by the need to resolve the required cri'cal dimension (CD).
CONCLUSIONS 1. The droplet generator based on induced Rayleigh jet breakup was developed. 2. The high droplet posi:on stability and mass uniformity was demonstrated both in short & long term
opera:on. 3. The flexibility of opera:on regimes (droplet diameter, velocity and frequency) was demonstrated. 4. Two types of jet modula:on was developed: piezo in hot zone, which limits an opera:on
temperature (250˚C), and waveguide with piezo at room temperature, which allows to operate at higher temperatures.
5. Was shown that such DG can be used for high brightness and high stability LPP EUV source. The work was supported by the Ministry of Educa'on and Science of the Russian Federa'on under the Agreement № 14.579.21.0004 (a unique iden'fier for Applied Scien'fic Research (project) RFMEFI57914X0004).
Droplet target parameters: Parameter Value (Std %) Pulse energy, mJ 100 (9.9 %) Pulse width, ns 28 (8.1 %) Peak intensity, MW 2 (10.9 %) Focal spot size (FWHM) 50 um Average power density at focal spot, W/cm2
1.8*1011 (13 %)
Laser parameters:
4˚ GIS spectrometer; I, II, III – diffrac'on orders
laser
X-‐ray photodiode
720 um
Source size ~ 100 um (FWHM)
Plasma image in-‐band EUV by pinhole camera
EUV pulse-‐to-‐pulse stability can be improved via improving laser parameters: energy pulse, poin:ng and pulse dura:on stability
X Y
CE2π = 2.3 %
εΩinband = 4.2*10-‐4 J/Sr
Scaling law for brightness B13.5 ≈ 0.5 W/mm2Sr (10 Hz); B13.5 ≈ 50 W/mm2Sr (1 kHz); B13.5 ≈ 400 W/mm2Sr (8 kHz)
The key requirements for the Ac:nic inspec:on tool: • High brightness (>100 W/mm2/sr) • Stability of plasma posi:on < 3% of FWHM* • Energy stability < 3.5% (3σ) pulse-‐to-‐pulse • Cleanliness 100% (debris containment must be included in the source) • Availability / Reliability * The posi'onal stability requirement varies depending on source characteris'cs and the illumina'on concept.
Source requirements
Classical :n DG approach Lithium jet approach
Diameter, um 70
Temperature, K 413
Material Sn/In
X-‐Y posi'on Std, um σx ≈ σy ≈ 0.5 um
Proof of concept with 10 Hz Nd:YAG laser
Emission spectrum, plasma size and brightness
Examples of DG opera:on
High brightness can be achieved
Correla:on of EUV and laser pulse energies
Jet approach provides extreme stability, renewable and infinite in space target
Conversion efficiency (Peak values)
4th Interna'onal EUVL symposium, 2005
Lithium has rela:vely high conversion efficiency and number of advantages, which makes it highly arrac:ve for the ac:nic source development: • Li produces narrow in-‐band spectral emission and low ultraviolet-‐visible out-‐of-‐band radia'on
• No spectral purity filter needed • Lithium has low ion energy intensity • Debris mi'ga'on is considerably less in comparison to Tin, which in turn gives longer component life'me
• No opening of the vacuum chamber is needed
1. Li target has no debris in comparison to the Sn target: due to “closed LPP chamber” design using self-‐cleaning radia:on input and output windows.
2. Long source life:me: EUV op:cs placed outside the LPP chamber.
3. High spectral purity: usage of Li plasma with narrow “in-‐band” line spectra, concentrated at 13.5nm.
4. High EUV dose stability: provided by stable posi:on of the target and its infinite size.
5. Long (infinite) duty cycle: provided by con:nuous opera:on of liquid lithium pump.
Advantages of lithium target Nozzle: 30 um Modula'on frequency: 40 kHz Pressure: 5 bar Droplet diameter: 46 um Droplet velocity: 7 m/s Droplet diameter range: 45-‐65um Droplet diameter STD: 1% Center of mass displacement: σx = 0.5 um; σy = 0.8 um High target posi:on stability
ISTEQ and RnD-‐ISAN have developed a new concept of a compact high-‐brightness lithium EUV source:
to Li pump
Drive laser input window
EUV light output window
LPP plasma λ = 13.5nm f = up to 10kHz B = up to 1kW/mm2*sr
Li stream from the pump
Source components : • Target: con'nuous Li liquid jet • Drive laser: Nd:YAG, 1.06um, up to 10 kHz, 1 kW [to be selected]
• Self-‐cleaning Input and Output windows
• Recycling target system Main source parameters: • Wavelength: 13.5nm • Brightness: up to 1kW/mm2·∙sr • Frequency: up to 10kHz • Collectable in-‐band power: >60mW • Etendue: 2-‐4·∙10-‐5mm2·∙sr
Preliminary experiments have been successfully performed and the feasibility of the approach has been proved. Unique hardware has been developed and tested, making the technology ready for implementa:on:
Lithium jet
EUV brightness: up to 1 kW/mm2·∙sr
Centrifugal pump for genera'on of liquid lithium jet was tested under varying condi'ons, up to 200 hours in non-‐stop regime at temperature of 350℃
Liquid lithium pump
CE mean:2.3% CE std: 0.1%
