Writing NanoImprint Templates
by
Shaped E-Beam Lithography
Dirk Beyer, Peter Hudek, Olaf Fortagne, Timothy Groves, Juergen Gramss
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
Framework
Close Cooperation between: Leica Microsystems Lithography Motorola IMS - Chips
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
Template Writing Strategy
Active imprint area 25mm x 25mm
6025 plate with layout of four SFIL templates
Single SFIL pedestal template, 65mmx 65mm external dimension
Template obtained by dicing a 6025 plate
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
Template Writing Strategy
Conventional template process using 15nm of Cr as hard mask
- 6” blank covered with a 15nm Cr-layer (Motorola) - 180nm spin coated ZEP 7000 resist (Leica) - Exposure at Leica SB350 MW (Leica) - Multiple puddle developed 60s in ZED500 developer (Leica)
- Cr-layer etching with Cl-based RIE & resist removal (Motorola)
- Pattern transfer through Cr into SiO2 in a F-based RIE to a depth of 100-200nm (Motorola)
Motorola Pattern Transfer Process
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography NNT‘04
Template Writing Strategy
Critical Specs:
- Minimum Feature Size: Gate / Contact at 1x - Image Placement (25mm x 25mm) - CD Uniformity - Defects
Writing Options:
Gaussian Beam - high Resolution but low Throughput, not optimized for Placement Variable Shaped Beam - better Throughput, excellent Placement, but.......
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography NNT‘04
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
Mask Maker‘s Tool Today:
- 50kV Variable Shaped E-Beam, Vector Scan - 1nm Grid - Up to 20A/cm² for high Throughput - Continuously Moving Stage - Step and Repeat Stage - Robotic Reticle Management Station - Handles Blanks & Substrate Holders Up To 9 Inch - Data Preparation Interface to CATS & MGS - Proximity Correction (Hardware or Software)
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
General View SB350
Reticle Management Station (CAR) Control Electronic Equipment Controller
Asyst Versaport 2200 Operator (outside)
Basic Unit Operator (grey room)
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
Outer Handling Station
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
Chamber & Mask Stage Assembly
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
Cassette for Mask 6025
calibration detector mask 6025 baseplate (Zerodur)
contact
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
MW & DW Specifications
Placement Overlay CD Uniformity DW Resolution
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
Placement
Leica SB350 MW
(0,48m clear lines) Image Placement 3 10 / 8 nm
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
Placement
Leica SB350 MW
(0,48m opaque lines) Image Placement 3 9 / 8 nm
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
Overlay
Leica SB350 MW
Mask to Mask Overlay 3 8 / 8nm
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
CD Uniformity
Leica SB350 MW
(0,48m clear lines) CD - Uniformity 3 7 / 6 nm
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
1x Resolution
60nm
Writing on 300mm Wafers
70/240nm L/S
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
1x Resolution
45nm SRAM Gate Patterning
45nm 50 nm
after lithography 1st 65nm node structures 114 nm gate on active
(active and gate have been printed using SB350 DW)
Leica Microsystems Lithography GmbH
after etch
Source: MEDEA+ T201: Final Report
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
Resolution Capabilities
Gaussian Beam Variable Shaped Beam
One exposure shot One exposure shot Pattern contour Increased Throughput: (some degree of parallelism introduced into the exposure process)
Beam Shape:
Fixed (focused) Variable in x and y axis
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography NNT‘04
Resolution Capabilities
Generation of Axis-Parallel 45o Rotated Rectangles and Triangles
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography NNT‘04
Resolution Capabilities
Rectangular Shaped Beam
Beam Blur & Aerial Image Slope
Determined by: - optical aberrations; - space charge effect
y c ty cuiity cu ty acuiit edge edge edge edge e m eam eam Beam
Leica Microsystems Lithography GmbH
Influence: - CD Linearity/Uniformity
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
Resolution Capabilities
20%-80% Edge acuity versus aperture angle for four different probe currents and two emission currents in the best focus plane.
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography NNT‘04
Resolution Capabilities
Aerial Image Resolution controls printable feature size
Single – Line exposure Line - Array exposure
Position [nm]
Position [nm]
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
1nm CD Control
Nominal Line Width: 0.92µm (No Proximity Correction applied)
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography NNT‘04
Tasks to be solved:
- find a trade off between throughput and resolution
- optimize the dose control
Proximity Correction
Beam current is fixed at production tools !
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
Dose Control
Pattern design
Proximity affected pattern (after Lift-Off)
Contours simulation
INTRA
INTER
Proximity Effect - an example
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography NNT‘04
Dose Control
PEC-Input Parameters Determination
(Fine-Tuning of the Point-Spread Function)
Including Exposure, Resist patterning & Pattern transfer processes Exposure, „PROX-In“ – software package
Reconstruction / Back-Simulation of Patterns and/or Pattern Geometry Variations
- uses non-corrected simple test patterns exposed in an exposure wedge; - CD-measurements of patterns in selected/specified points; - Search for optimized input parameters to reconstruct the measured data -> Back-Simulation.
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography NNT‘04
Dose Control
„FinePSF – „Fine-Tuning“
Dose Factor
2-Gauss PSF
Measured
Amount of exposure energy required to produce the proper dimension of the written feature
Simulated Linewidth
Dose Factor
3-Gauss PSF
after „Fine-Tuning“ of the PSF parameters ...
Measured
„Dose to Size“
Leica Microsystems Lithography GmbH
Simulated Linewidth
Writing NanoImprint Templates by Shaped E-Beam Lithography NNT‘04
Dose Control
Line in „Duty-Ratio“
Linewidth
The shape of the measured curve is process-dependent !
Measured Simulated
Duty.Ratio: Duty.Ratio:
(1:1)
(1:2)
(1:3)
(1:10)
(1:20)
Single Line
NNT‘04
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography
Dose Control
Proximity Effect Correction – a Recipe
Expose of Pattern for Monitoring on Test Blank Development and Development and Etching/Cleaning Etching CD measurement CD measurement „Beta“ - Simulation „Beta“„Beta“ simulation Program program
Result: Parameter Result: Parameter ( ( , , , , ) ) for complete for complete process Process
Back simulation of Back Simulation of - incl. tool and , , , , - incl. Tool and process influences Process influences
Output: ,,Calculation Output: Calculation of of and and
Expose of CD Test Pattern and CD Measurement
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
Dose Control
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
Results
Leica SB350 MW
100nm Test data provided by Motorola
Leica Microsystems Lithography GmbH
50nm
40nm
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
Results
Trenches etched into quartz
50nm
40nm
33nm
29nm
Contacts
55nm Test data provided by Motorola
Leica Microsystems Lithography GmbH
44nm
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04
Results
Gaussian Beam
(Leica VB6) 100keV
ONE SHOT
Shaped Beam
(Leica SB350 MW) 50keV
ONE SHOT
100nm
50nm
40nm
Template Results: Gaussian vs. Shaped Beam
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography NNT‘04
Summary
- Well proven Production Tools for Mask Making and Wafer Direct Writing are available to fabricate S-FIL Templates
- It is essential to adapt the Tool to the Technology Process
- 33nm L/S and 44nm Contacts are well resolved using ZEP700 and a Motorola Pattern Transfer Process
- Standardization of Templates is necessary
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography NNT‘04
Thank you for your Attention!
Leica Microsystems Lithography GmbH
Writing NanoImprint Templates by Shaped E-Beam Lithography
NNT‘04