Litho Works PEB and CD analysis of two

Litho. Works PEB and CD analysis of two plates August 14, 2003 Thermal analysis of two PEB plates: 093 -08_peb_bake 7. csv 093 -08_peb_bake 8. csv August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential

Summary • • These are preliminary results The first half of this analysis addresses PEB thermal analysis for PEB’s 7 & 8 ? ? • Investigates Temperature cycle Energy installed into the wafer (Temp * Time) Variation in energy installed Temperature over time contour plots The second half of the analysis examines two Nanometrics OCD data sets ? Fixed focus analysis of wafers 12, 16 • Wafer 12 = PEB 8 • Wafer 16 = PEB 7 ? The data has been modeled for across wafer variation ? Residuals to the wafer model illustrate the anticipated, non-PEB influenced performance • Statement based upon expected whole-wafer variation of PEB temperature • The last slide touches on Wafer 13 & 17 ? These are FEM arrays and warrant further study. August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 2

Initial Observations • PEB Thermal Analysis ? The Bake cycle was examined as a function of: • • Time-Temperature curve Time-temp variations across wafer. Total energy (integrated time * temperature) delivered to the wafer Energy variation across wafer due to non-uniform heating. ? PEB 7 is more uniform than PEB 8 • Not observed in the temperature or the total energy delivered • Can be seen in the plots of temperature variation from wafer mean over time and in the Energy Variation plots. ? Neither bake plate is allowing enough time for the bake temperature to achieve steady state. • See slides 26 to 28 • Feature Response ? Note: The On-Wafer sensor orientation has not been corrected or adjusted for this analysis. August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 3

Feature Response and Correlation • Feature Response ? Note: The On-Wafer sensor orientation has not been corrected or adjusted for this analysis. ? Examined wafers 12 (PEB 8) and wafer 16 (PEB 7) ? Each feature’s variation was modeled for whole-wafer variations • Wafer-model should correlate to PEB energy variations • Residuals to wafer model should be approximate equal in response – if both wafers were exposed on same scanner • Residuals to wafer model should show exposure tool performance. ? MSE Behavior • Differs significantly for Vertical (group 1) and Horizontal (group 2) features. – May be the result of scanner slit vs scan sensitivity of feature edges. – May also be from metrology tool algorithm. ? There is no strong and obvious visual correlation of PEB energy and feature response. ? There is a suggestion of PEB energy variation and SWA • Further studies ? More thought must be given to these correlations. ? FEM wafers need to be studied. August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 4

PEB #7 August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 5

PEB #7 overview • Left graphic ? Details location of sensor points • Right graphic ? Summary of rise/fall times vs temperature August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 6

Sensor variation from wafer mean • • Each site contains a plot of delta-temp versus time Area ? product of (degrees * seconds), summed over all sites. This is proportional to the energy entered into the wafer during the bake. • Area Variance ? Energy variation across the wafer ? Summed deg-sec’s over all sites reporting total variation from meantemperature over time. August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 7

Corresponding points on the graph (50. 1 sec, 113 C) • August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential Moving the mouse to a point on the temp-time curve will highlight the corresponding points on the delta-temp wafer plot 8

On-Wafer thermal loading? Area of sensor packet • • Notice how the 7 wafer-center sites are the first to rise in temperature. Note also the two sites located over the On-Wafer sensor packed lag in heading and also lag in cooling. This area also does not reach uniformity until the end of the heading cycle. ? This is most probably due to thermal-mass loading of the sensor packet. • The red-dot on each plot marks the same relative point on each site. August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 9

PEB 7; Thermal Energy Delivered thermal sensor area • • August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential Plot of thermal area (degsec) across wafer. Notice that there is a range of 168, 714 deg-sec with the upper left of the wafer receiving the most energy Thermal-package sensor area is relatively cool No activation threshold was set for this plot 10

PEB 7; Thermal Energy Delivered • • August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential Plot of area (deg-sec) integrated over time Notice that there is a range of 168, 174 deg-sec with the upper left of the wafer receiving the most energy 11

PEB 7: Thermal Energy Variance across wafer • • August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential Variation in energy (integrated temperature*time) delivered Variation is greatest at wafer’s upper left corner, least in center & right. 12

Thermal Energy Variance Across Wafer - Contour August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 13

PEB 8 Data August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential

Plate PEB 8, Bake Curve • • • August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential Top: PEB 8 Bottom: PEB 7 Curves appear very similar in shape. 15

PEB 8; Delta-Temperature Response (50. 1 sec , 113 C) • Same point is marked on the timetemp curve. ? Distribution in upper left of wafer is now very uniform. August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 16

Comparison PEB 8 vs PEB 7 PEB 8 PEB 7 • • Time-Temp Area Differences PEB 8 ? has a higher energy area. ? Exhibits greater excursion range and variation across the plate. August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 17

Comparison: Delta temperature with time PEB 8 • PEB 7 PEB 8 exhibits more variation at the bottom of the wafer. August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 18

PEB 8; Thermal energy delivered August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 19

Thermal Energy Delivered – Bake 8 Contour August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 20

PEB 8 Thermal Energy August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 21

PEB 8; Thermal Energy Variation August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 22

Comparison: Thermal Energy Delivered – PEB 8/ PEB 7 PEB 8 • • PEB 7 Both wafers as plotted on the same scale. More thermal energy delivered to PEB 7 August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 23

Thermal Energy Variation – Bake 8 Contour • • Energy delivered as a delta from the wafer average temperature. Energy = Sum((Temperature-Activation Temp. ) * Delta. Time) ? Delta. Time = time interval of sample August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 24

PEB 8: Greatest variation in thermal energy August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 25

Comparison: Thermal Energy Variation – PEB 8/ PEB 7 PEB 8 • • PEB 7 Scales vary but characteristic is same PEB 7 has significantly better energy uniformity August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 26

Comparison energy variation statistics PEB 8 • PEB 7 PEB 8 exhibits ? A greater mean temperature, range and variance of temperature than PEB 7 August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 27

PEB 8/ PEB 7; thermal variation PEB 8 • PEB 7 PEB 8 and 7 variations plotted to the same scale. August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 28

Thermal range study Bake 8 • • August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential Temperature range about the average temperature of the wafer at each timeslice. The cycled-temperature rose a total of 98. 07 degrees. Steady state uniformity is 0. 18 degree across wafer. Notice that the wafer at 121 degrees (max. temp at 134 sec. ) did not reach steady-state uniformity. 29

Thermal range study Bake 7 • • August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential Same study with PEB 7 This study shows a red square at each transition start/stop point on the curve. 30

Range Uniformity Summary Bake 8 Bake 7 Bake 8 • • Plots exhibit thermal range across the wafer at each time-slice Both plates exhibit the same steady-state thermal resolution. ? Thermal range and maximum temperatures differs by approximately one degree • • Neither plate reaches steady state while at the maximum temperature. Bake 8 has ? ? • greater across-wafer variations (9. 6 v 7. 0 degrees) Greater range at the final temperature (0. 9 v 0. 6 degree) Smoother cooling curves than 7 Near identical rise/cool thermal slopes and time at the maximum temperature compared with Bake 7 Conclusion: Bake 8 has more thermal variation across the wafer. August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 31

Thermal Uniformity at any point in time • • August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential Generate single or matrix graphics of all of the plots. A “movie” video will also be added to allow you to watch wafer heating. 32

PEB 8 – Steady State Temperature August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 33

PEB 8 Steady State Temp August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 34

Thermal changes during the up-ramp August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 35

CD data review August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential

Data Setup and Organization Wafer 12: processed on PEB plate 8, const. exp/focus 18. 5/0 Wafer 13: processed on PEB plate 8, FEM 18. 5/0 +- 0. 5/0. 05 Wafer 16: processed on PEB plate 7, const. exp/focus 18. 5/0 Wafer 17: processed on PEB plate 7, FEM 18. 5/0 +- 0. 5/0. 05 • The measurements are taken on a nominal 150: 150 grating, ? somewhat overexposed here (~140 nm average linewidth). • • All wafers have PAB step on plate 1, also attached. For the PEB data, there are several measurements for each plate, each corresponding to a different orientation of the sensor wafer. ? '3_oclock', for example, means that the wafer module is at the 3 o'clock position relative to the cassette. ? 1 -2 o'clock is the position between 1 and 2, which appears to be 3/4 of a full rotation from the orientation of the process wafer when it's on the PEB plate-since On. Wafer formats the data such that the module is situated at 3 o'clock, this means we just have to rotate the 1 -2 data 180 degrees and should have the right orientation. • Within the Nanometrics data set, there are two "groups" of data for each wafer ? group 1 corresponds to measurements made on gratings with lines of vertical orientation ? group 2 corresponds to the horizontal orientation. August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 37

Wafers 13, 15; Assumed Dose and Focus layout • Wafers 12 & 16 are fixed focus/dose August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 38

MSE behavior (12 & 16) Layout, all sites • • MSA can be used to determine the measurement quality Variation is in fact a little better for the FEM wafers than the fixed exposure. ? Probably due to the bi-modal distribution of the fixed-exposure data. August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 39

MSE; Wafer 12 (PEB 8) • August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential Horizontal and vertical features are responding differently to MSE 40

Wafer 12, TCD (fixed focus, Group #1) All features August 2003 • Vertical Features Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 41

Wafer 12, TCD group 2 (Horizontal) • August 2003 Field layout is shown on the left. Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 42

Wafer #12 –T 3 (PR) Group 1 • Group 2 Photoresist thickness behaves quite differently for vertical vs horizontal feature orientation. August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 43

Wafer 12, BCD • • Have about 3 nm of difference in mean values. Range of values is the same to within 0. 7 nm August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 44

Wafer #12, BCD Residuals to Wafer variation • • • Aberrations of scan or slit are influencing the CD variation Left = vertical features so edges are influenced by the scan Right = horizontal features so there is more slit influence. August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 45

Wafer 12; SWA August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 46

Wafer #12; SWA Residuals to wafer model • The horizontal line behavior (right) is very surprising. ? Metrology Algorithm? August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 47

Wafer #12 model; BARC T 2 • Good, repeatable to about 0. 1 nm August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 48

Wafer #12; BARC residuals • Vertical features (#1) have characteristic ring. Ring is not as evident in the horizontal features on the left. ? Scale on left is wider because of the difference in noise. August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 49

Wafer #16 (PEB 7) August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential

Wafer 16 BARC and PR August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 51

Wafer #16; Modeled wafer SWA (Group 1) August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 52

Wafer #16; Modeled wafer BCD & TCD (Group 1) August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 53

Wafer 16; Residuals to wafer BCD & TCD (Group 1) August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 54

Wafer #13 FEM; in-die groups 1 & 2 Horizontal • Different behavior and sampling of groups 1 & 2 Vertical August 2003 Litho. Works PEB - Two plate study TEA Systems Corp. Confidential 55