Weir PWWeir PWWeir PWWeir 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 4146TZavecz@enter.net

November 12, 2003

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -2-TEA Systems Corp. Confidential

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.

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -3-TEA Systems Corp. Confidential

Raw data measured

• Scatter tool data used: Nanometrics

• Weir PW analysis

• Data included: BCD TCD SWA T3 (Resist) T2 (BARC)

• Die Size is (25,28)mm

T2 (nm) T3 (nm) MSE BCD (nm) SWA (°) TCD (nm) Z(µm)Count 1099 1105 1110 1094 1110 1078 1110Mean 72.83577798 213.7036 84.339436 93.80762 86.10995 72.67932 -181.5712

Median 38.915 261.73 3498.6597 100 55.216 40.215 -194.4SEM 0.07762979 0.419608 21.710465 0.308246 0.192121 0.157673 0.227958

Maximum 77.83 350 6997.1172 200 87.448 80.43 -127.1Minimum 0 173.46 0.2021 0 22.984 0 -261.7

Range 77.83 176.54 6996.9151 200 64.464 80.43 134.6MinMax 77.83 350 6997.1172 200 87.448 80.43 -261.7

Variance 6.622996366 194.5581 523192.18 103.9468 40.97071 26.79985 57.68076StDev 2.573518286 13.94841 723.32024 10.19543 6.400837 5.176857 7.594785

Mean+3Sigma 80.55633284 255.5488 2254.3002 124.3939 105.3125 88.20989 -204.3555

Locations on Field

Locations on Wafer

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -4-TEA Systems Corp. Confidential

Wafer Modeled BARC

• Wafer systematic errors have been removed.

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -5-TEA Systems Corp. Confidential

BARC: Wafer cross-section

• Examination of cross-section as shown

• Notice definite step at wafer 30 mm diameter

Potential pad site

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -6-TEA Systems Corp. Confidential

BARC radial

• Step occurs outside of pin radius = 30 mm.

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -7-TEA Systems Corp. Confidential

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

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -8-TEA Systems Corp. Confidential

BCD – Wafer & Average field removed

• Plotting Bottom CD after removal of: Wafer aberrations Average field.

3 potential locations of wafer pads

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -9-TEA Systems Corp. Confidential

Top CD variation after mean field is removed

• Examine the CD variation after having remove: Wafer systematic errors and The average field.(reticle)

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -10-TEA Systems Corp. Confidential

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.

TCD (nm) vs field radius

-7.00

-6.00

-5.00

-4.00

-3.00

-2.00

-1.00

0.00

1.00

2.00

3.00

4.00

5.00

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Radius

To

p C

D

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -11-TEA Systems Corp. Confidential

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

TEA Systems Corp. Confidential

Analysis Slides presented as backup data

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -13-TEA Systems Corp. Confidential

Raw BARC Thickness (T2)

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -14-TEA Systems Corp. Confidential

Wafer Modeled BARC

• Wafer systematic errors have been removed.

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -15-TEA Systems Corp. Confidential

BARC: Wafer cross-section

• Examination of cross-section as shown

• Notice definite step at wafer 30 mm diameter

Potential pad site

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -16-TEA Systems Corp. Confidential

BARC radial

• Step occurs outside of pin radius = 30 mm.

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -17-TEA Systems Corp. Confidential

Weir PWMeasurement of Bottom

Raw – Bottom CDs

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -18-TEA Systems Corp. Confidential

Wafer Modeled Bottom - CD

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -19-TEA Systems Corp. Confidential

Histogram after wafer aberrations are removed

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -20-TEA Systems Corp. Confidential

BCD – Wafer errors removed

• Data removed: Wafer systematic Mean Bottom CD

offset = 94.09 nm

• Display is dominated by the signature of the reticle.

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -21-TEA Systems Corp. Confidential

BCD – Wafer & Average field removed

• Plotting Bottom CD after removal of: Wafer aberrations Average field.

3 potential locations of wafer pads

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -22-TEA Systems Corp. Confidential

Top CD; Wafer Model

• Offset is not plotted

• We’ll now remove these systematic errors.

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -23-TEA Systems Corp. Confidential

Top CD variation after mean field is removed

• Examine the CD variation after having remove: Wafer systematic errors and The average field.(reticle)

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -24-TEA Systems Corp. Confidential

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.

TCD (nm) vs field radius

-7.00

-6.00

-5.00

-4.00

-3.00

-2.00

-1.00

0.00

1.00

2.00

3.00

4.00

5.00

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Radius

To

p C

D

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -25-TEA Systems Corp. Confidential

SWA Wafer Model

• SWA variation across systematic error model

• Offset of 86.1 deg. Is not included.

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -26-TEA Systems Corp. Confidential

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

November 2003 Weir PW - Wafer Chuck Influence on CDs Page -27-TEA Systems Corp. Confidential

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