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Weir PW. Analysis of wafer-chuck influence on features. Dataset: 80_D2_1_2 Features: Device: 8-25 6x5 1:1 / Level: ASML AMD 100 1-2 T 320-640nm LotName No:80D2_1_2 03-Nov-03. TEA Systems Corp. 65 Schlossburg St. Alburtis, PA 18011 610 682 4146 TZavecz@enter.net November 12, 2003.
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Weir PW Analysis of wafer-chuck influence on features Dataset: 80_D2_1_2 Features: Device: 8-25 6x5 1:1 / Level: ASML AMD 100 1-2 T 320-640nmLotName No:80D2_1_2 03-Nov-03 TEA Systems Corp. 65 Schlossburg St. Alburtis, PA 18011 610 682 4146 TZavecz@enter.net November 12, 2003
Investigation • Each wafer chuck provides kinematic support for the wafer on 3 pins • Located at an approximate radius of 30 mm from wafer center • Separated by 60degrees • Pin is 2 mm in diameter • Wafer is then suspended above the chuck by approximately 75 um. Weir PW - Wafer Chuck Influence on CDs
Raw data measured Locations on Wafer • Scatter tool data used: • Nanometrics • Weir PW analysis • Data included: • BCD • TCD • SWA • T3 (Resist) • T2 (BARC) • Die Size is (25,28)mm Locations on Field Weir PW - Wafer Chuck Influence on CDs
Wafer Modeled BARC • Wafer systematic errors have been removed. Weir PW - Wafer Chuck Influence on CDs
BARC: Wafer cross-section • Examination of cross-section as shown • Notice definite step at wafer 30 mm diameter Potential pad site Weir PW - Wafer Chuck Influence on CDs
BARC radial • Step occurs outside of pin radius = 30 mm. Weir PW - Wafer Chuck Influence on CDs
Photoresist • Wafer-systematic errors have been removed • Mean value of 211.8 nm also removed • Three points may show as slightly shifted contacts. • Note circled points Weir PW - Wafer Chuck Influence on CDs
BCD – Wafer & Average field removed • Plotting Bottom CD after removal of: • Wafer aberrations • Average field. 3 potential locations of wafer pads Weir PW - Wafer Chuck Influence on CDs
Top CD variation after mean field is removed • Examine the CD variation after having remove: • Wafer systematic errors and • The average field.(reticle) Weir PW - Wafer Chuck Influence on CDs
Top CDs and radius • Notice “dip” located at the 30 mm radius • From here on we will restrict the analysis radius to 94 mm • Excludes the bad data points shown at the edge-bead. Weir PW - Wafer Chuck Influence on CDs
Conclusion & discussion points • BARC, Photoresist and Bottom CD’s suggest there is an effect occurring at the 30 mm wafer radius. • Bottom CD and photoresist strongly suggest the presence of 3 sites at the radius and spacing suggested by the wafer-chuck pins. • BARC has a radial height variation that also suggests something strong happening below this 30 mm radius. • Top CD shows some reaction but it is not as apparent as with the previous variables discussed. • SWA does not show the effect Weir PW - Wafer Chuck Influence on CDs
Raw BARC Thickness (T2) Weir PW - Wafer Chuck Influence on CDs
Wafer Modeled BARC • Wafer systematic errors have been removed. Weir PW - Wafer Chuck Influence on CDs
BARC: Wafer cross-section • Examination of cross-section as shown • Notice definite step at wafer 30 mm diameter Potential pad site Weir PW - Wafer Chuck Influence on CDs
BARC radial • Step occurs outside of pin radius = 30 mm. Weir PW - Wafer Chuck Influence on CDs
Weir PW Measurement of Bottom Raw – Bottom CDs Weir PW - Wafer Chuck Influence on CDs
Wafer Modeled Bottom - CD Weir PW - Wafer Chuck Influence on CDs
Histogram after wafer aberrations are removed Weir PW - Wafer Chuck Influence on CDs
BCD – Wafer errors removed • Data removed: • Wafer systematic • Mean Bottom CD offset = 94.09 nm • Display is dominated by the signature of the reticle. Weir PW - Wafer Chuck Influence on CDs
BCD – Wafer & Average field removed • Plotting Bottom CD after removal of: • Wafer aberrations • Average field. 3 potential locations of wafer pads Weir PW - Wafer Chuck Influence on CDs
Top CD; Wafer Model • Offset is not plotted • We’ll now remove these systematic errors. Weir PW - Wafer Chuck Influence on CDs
Top CD variation after mean field is removed • Examine the CD variation after having remove: • Wafer systematic errors and • The average field.(reticle) Weir PW - Wafer Chuck Influence on CDs
Top CDs and radius • Notice “dip” located at the 30 mm radius • From here on we will restrict the analysis radius to 94 mm • Excludes the bad data points shown at the edge-bead. Weir PW - Wafer Chuck Influence on CDs
SWA Wafer Model • SWA variation across systematic error model • Offset of 86.1 deg. Is not included. Weir PW - Wafer Chuck Influence on CDs
SWA residuals • Removed • Wafer model • Average Field • Each site is averaged & then removed. • SWA exhibits only the variation caused by the start and top of the exposure scan. • Does not show any reaction at 30 mm radius Weir PW - Wafer Chuck Influence on CDs
Photoresist • Wafer-systematic errors have been removed • Mean value of 211.8 nm also removed • Three points may show as slightly shifted contacts. • Note circled points Weir PW - Wafer Chuck Influence on CDs