Light Sources for EUV Mask Metrology. Heiko Feldmann, Ulrich Müller

Transcription

1 Light Sources for EUV Mask Metrology Heiko Feldmann, Ulrich Müller Dublin, October 9, 2012

2 Agenda Actinic Metrology in Mask Making The AIMS EUV Concept Metrology Performance Drivers and their Relation to the Source Overview: Top Level Criteria for the Next Generation AIMS EUV Source 2

3 Agenda Actinic Metrology in Mask Making The AIMS EUV Concept Metrology Performance Drivers and their Relation to the Source Overview: Top Level Criteria for the Next Generation AIMS EUV Source 3

4 Metrology for EUV Mask Manufacturing Blank Substrate Substrate Inspection Mirror Deposition Blank Inspection Structuring Registration Pattern Inspection Review Repair Repair Verification Delivery Substrate Inspection Blank Inspection Pattern Inspection Defect Maps for Review AIMS EUV Review & Verification Actinic Metrology is required to predict printing behaviour of hot spots in the mask pattern 4

5 The AIMS TM in the mask manufacturing process: It is required for producing defect free masks Printability test by AIMS - technology 1 Printability check of repaired defects by AIMS 4 Defective mask Repaired and accepted mask Detailed analysis by high resolution electron beam E-beam mask repair by MeRiT MG 2 3 5

6 Schedule to EUV mask defect printability review established: AIMS EUV development program started Ideas and concepts Detailed design Delivery AIMS EUV C&F study 39 months of main development project SEMATECH TWG: AIMS EUV ultimately needed for high volume EUVL AIMS EUV Development Start First AIMS EUV Delivery Carl Zeiss SMT is currently building a first generation AIMS tool supporting the 16nm node. For the 11nm node, an extension will be required. 6

7 Agenda Actinic Metrology in Mask Making The AIMS EUV Concept Metrology Performance Drivers and their Relation to the Source Overview: Top Level Criteria for the Next Generation AIMS EUV Source 7

8 Preliminary layout of the AIMS EUV Supply compartment incl. media, climate control and e - racks Vacuum Handling Source module Air Handling Main Vacuum Chamber incl. EUV optics, stage Vacuum chamber service access 1 8

9 AIMS EUV design phase ongoing: Preliminary layout Metrology Core EUV-source Stage Handling 1m Vacuum pumps Optics Module 9

10 The Illumination Concept Source Brightness is important at collector 10 mw Field stop: clipping for uniformity ~ 10W EUV after field stop 4 uw Pupil stop: clipping for homogeneity after blades 1 uw Mask Most of the EUV radiation is lost due to geometrical clipping. To maximize the photon count within the limited etendue, Brightness is more important then source power! Setting blade 10

11 Agenda Actinic Metrology in Mask Making The AIMS EUV Concept Metrology Performance Drivers and their Relation to the Source Overview: Top Level Criteria for the Next Generation AIMS EUV Source 11

12 z defocus AIMS Aerial Image Metrology System Aerial image 3D intensity distribution as generated by the mask Intensity in resist Threshold x,y across the wafer CD - critical dimension 10-20nm Measurement through focus The 3D aerial image measured by AIMS is influenced by - Illlumination distribution - Mask structures (and possible defects) - NA of the projection optics 12

13 Measurement Accuracy Drivers: Image Stability focus instability The aerial image and the mask must be stabilized in the nm range. unaberrated image lateral instability This requirement drives a large effort in mechatronics layout of the metrology core. 13

14 Measurement Accuracy Drivers: Aberrations spherical aberration Aberrations must be at the same sub-nm level as for lithography scanner optics. coma This drives efforts in optics design and manufacturing. 14

15 Measurement Accuracy Drivers: Dose Control low dose target dose high dose Dose is a critical parameter for CD measurement. Defocussed measurements are much more critical than at the best focus positions. Dose control drives most of the source requirements: Power stability Homogeneity Position and shape stability (see following slide) 15

16 BACUS 2011 AIMS EUV Design: Metrology Source stability current baseline source next generation source Compensational strategies for source instabilities established Next generation source needs to be on a comparable stability level as the current baseline source 16

17 Measurement Accuracy Drivers: Noise from CCD and shot noise noise The suppression of shot noise drives the exposure dose and thus requires high transmission optics and high quantum efficency requires a high brightness source to limit the exposure time 17

18 Time per site [a.u.] Optimization for photon efficiency has improved the run rate Run rate improvement: 1,00 Transmission 0,75 Frame transfer 0,50 Stage move CCD overhead Exposure Fast stage 0,25 0,00 first concept now Nearly all time is used for exposure Photon efficiency = Optimization of application performance 18

19 Agenda Actinic Metrology in Mask Making The AIMS EUV Concept Metrology Performance Drivers and their Relation to the Source Overview: Top Level Criteria for the Next Generation AIMS EUV Source 19

20 Top Level Criteria for Next Generation AIMS Source We are looking for a next generation source for AIMS EUV based on the key parameters* Stability Plasma position <3% of FWHM Energy stability <3.5% (3s) pulse-to-pulse Brightness > 30W/mm2/sr (minimum) >100 W/mm2/sr (target) Cleanliness 100% Availability / Reliability *These are our key guiding parameters for the search and early selection. They will be modified and extended for different source concepts individually. For detailed information, please contact Heiko Feldmann 20

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22 References Dirk Hellweg et. al. Closing the Infrastructure Gap Status of the AIMS EUV Project Proc. SPIE 8322 Dirk Hellweg et. al. AIMS EUV - the actinic aerial image review platform for EUV masks Proc. SPIE 7969 Anthony Garetto et. al. Status of the AIMS EUV Project, BACUS 2012, to be published Heiko Feldmann et. al. Actinic Review of EUV Masks Proc. SPIE