The Waferstepper Challenge: Innovation and Reliability despite Complexity

Transcription

1 : Innovation and Reliability despite Complexity by Gerrit Muller University of South-Eastern Norway-NISE Abstract The function of the waferstepper is explained and its most important characteristics. The dynamic market provides continuous technological challenges, resulting in ever increasing performance, but also complexity. Despite the exponential increase of performance and complexity, the reliability must be good. The reliability is crucial when the stepper is used in volume production. The ASML engineering style plays a central role in tackling this challenge. Three key aspects of this style are: Feedback, Focus and Future awareness. The concurrent application of these three aspects has so far been proven to be effective. Distribution This article or presentation is written as part of the Gaudí project. The Gaudí project philosophy is to improve by obtaining frequent feedback. Frequent feedback is pursued by an open creation process. This document is published as intermediate or nearly mature version to get feedback. Further distribution is allowed as long as the document remains complete and unchanged. status: finished

2 Twinscan AT Gerrit Muller ASMLtwinscanPhoto

3 What is a waferstepper source reticle lens wafer 3 Gerrit Muller ASMLlithographyPrinciple

4 From stepping to scanning n n+1 stepper: wafer step static exposure of field reticle slit 250 mm/s vx vy vy expose step expose expose step expose t t scanner: dynamic exposure through slit 4 Gerrit Muller ASMLstepperVsScanner

5 Key specifications waferstepper imaging alignment 130 nm line width 45 nm overlay 10 nm critical dimension 5 Gerrit Muller ASMLkeySpecifications

6 Moore s law 1000 line width in nm Gerrit Muller ASMLmooresLaw

7 Overlay budget (1999) global alignment accuracy 6 nm off axis pos. meas. accuracy 4nm stage Al. pos. meas. accuracy 4 nm off axis Sensor repro 3 nm blue align sensor repro 3 nm reticule 15 nm lens matching 25 nm system adjustment accuracy 2 nm interferometer stability 1 nm process overlay 80 nm matched machine 60 nm process dependency sensor 5 nm single machine 30 nm matching accuracy 5 nm stage overlay 12 nm stage grid accuracy 5 nm metrology stability 5 nm position accuracy 7 nm alignment repro 5 nm frame stability 2.5 nm tracking error X, Y 2.5 nm tracking error phi 75 nrad tracking error WS 2 nm tracking error RS 1 nm 7 Gerrit Muller ASMLoverlayBudget

8 Everything influences overlay Overlay Influence Diagram. (Maarten Bonnema, ) Heat flow from LoS into IF beams and compartment Fiducial Stability Fiducial Calibration Reticle Heating Reticle Errors Illumination settings (NA ) Light Energy Reticle Clamping induced Distortion Chuck expansion P and T of Air, Turbulences : Fiducial Heat flow from SS into RS chuck and compartment Metroframe Temperature Drift -> Effect on Showers -> Effect on Position of mirrors and IF's Airmount Noise, Limited Vibration Isolation Metroframe vibration due to water cooling (lens and coolplates) RS Bal Mass LoS Motor Airmount s T stability in LS lightpath Baseframe SS Motor ATHENA Measurement Accuracy ATHENA Mounting Accuracy/Stability LS Disturbance of Horizontal WS Servo by LS setpoints Wafer Distortion due to Wafer table/chuck Wafer Expansion by input temperature offset Wafer Expansion by Exposure Z-sensors T at top element of Lens (Mag) P and T in Lens Compartment Athena Chuck deformation Reticle RS Chuck Acceler ometer s P&T correction of Lens Lens Acceler ometer s Wafer WS Chuck SS Motor Air Foot Chuck Dimensional Stability Lens Heating IF Ref-IF Accuracy of Lensmanipulators Lens Dynamics WS Balance Mass Z-mirror Ref-IF Airshower RS RS Sensorframe + IF Block Metroframe IF LoS Motor Heat flow from SS into WS chuck Airshower WS IF Block Gravity Compensator noise Inaccurate Lens acceleration Feedforward Sound TIS Measurement Fiducial Stability Fiducial Calibration Heat flow from LoS into IF beams Data Delay Metrology inaccuracy Metrology Errors Metrolog y Servo error Feedforward errors HP Inaccuracy HP Rack MO PAC/PA 8 Gerrit Muller ASMLoverlayInfluenceDiagram

9 Challenge: Exponential Increase innovation performance imaging overlay productivity complexity feedback and adjustments hw and sw components reliability robustness 9 Gerrit Muller ASMLproblemIRC

10 The Software Reliability Threat manyears and LOC (lines of code) per product Mloc Mloc kloc Based on average 3 errors/kloc k 1000 typical amount of errors per product 10 Gerrit Muller ASMLproblem

11 Success factor: ASML system engineering style feedback budget & measure focus future keydrivers roadmaps 11 Gerrit Muller ASMLstyleSE

12 Feedback as technical design pattern x R z R x z v=250mm/s a=10m/s 2 6 degrees of freedom R y y level sensor required position (time) position control actual position feedback frequency: 4 khz (250 usec) feedback: fast and accurate waferstage interfero- meters actuators 12 Gerrit Muller ASMLfeedbackWS

13 Feedback as development process pattern stepsize: elapsed time: 3 months 25 months Target Start 13 Gerrit Muller LWAfeedbackLarge

14 Feedback (2) stepsize: elapsed time 3 months 25 months Target 2 months 12 months Target Start Start 14 Gerrit Muller LWAfeedbackMedium

15 Feedback (3) stepsize: elapsed time 3 months 25 months 2 months 12 months 1 month 8 months Target Target Target Start Start Start Small feedback cycles result in Faster Time to Market 15 Gerrit Muller LWAfeedbackSmall

16 MTBF as function of time MTBF in hours new variant 100 new generation 10 time after first installation 0 1 year 2 years 16 Gerrit Muller ASMLuptimeTrend

17 Focus via key drivers Mission statement Value of Ownership Cost per function Customer satisfaction Critical Dimension Overlay Productivity Product added value First year's shipment 17 Gerrit Muller ASMLkeyDrivers

18 Productivity decomposed throughput yield stepper costs scheduled maintenance Productivity uptime / maintenance installation time minimize unscheduled downtime MTBF MTTR economic lifetime 18 Gerrit Muller ASMLproductivityKeyDriver

19 Future aware TWINSCAN Platform Roadmap 70nm Generation (SIA)* 100nm 130nm 150nm NA max = 0.75 AT: nm NA max = 0.70 AT: nm Legend 193nm 248nm 365nm >250nm (non critical) * NA max = 0.65 AT: nm First product ship *ITRS Roadmap, 1999 Update 19 Gerrit Muller ASMLtwinscanRoadmap

20 Conclusion ASML System Engineering style feedback future aware focus imaging innovation overlay complexity reliability 20 Gerrit Muller ASMLconclusion

21 Nota Bene disclaimer The case material is based on actual data, from a complex context with large commercial interests. The material is simplified to increase the accessibility, while at the same time small changes have been made to remove commercial sensitivity. Commercial sensitivity is further reduced by using relatively old data (between 5 and 10 years in the past). Care has been taken that the illustrative value is maintained 21 Gerrit Muller CaseDisclaimer