Mask aligner lithography simulation for layout verification and optimization using OPC methodology

Transcription

1 Mask aligner lithography simulation for layout verification and optimization usg OPC methodology H. Lerch 1, D. Ritter 2, B. Meliorisz 2,3 1 AMO GmbH, Germany 2 GenISys GmbH, Germany 3 Fraunhofer IISB, Germany

2 Contents Introduction Mask aligner lithography simulation OPC Methodologies Conclusions and outlook

3 Contents Introduction Mask aligner lithography simulation OPC Methodologies Conclusions and outlook

4 Introduction Mask aligner lithography (contact/proximity prtg) illumation source mask coated wafer gap: 0 µm (contact) µm (proximity) MA 6 manual aligner from Süss (source: website of Süss)

5 Introduction Mask aligner lithography (contact/proximity prtg) Pros Cons Simple Large area Thick resist, high topography cost-efficient high throughput resolution relatively poor Application areas education, research, development LED panels MEMS When ever possible use proximity prtg! Simulation helps to extend the limits and avoid switchg to projection lithography

6 Contents Introduction Mask aligner lithography simulation OPC Methodologies Conclusions and outlook

7 Mask aligner litho simulation The litho challenge: get the exposure... just right. Exposure? Source: spectrum, shape, tensity Stack? Which resist? Coatg materials? Proximity gap? Small gap: good resolution, but contamation and defects Gap variations due to topography, non-flatness of wafer Mask layout? Do we get the tended pattern? Image degradation due to diffraction, resist development Which are the critical cases?

8 Mask aligner litho simulation Optimization of various parameters via simulation Source Wavelength Source coherence / shape Gap Dose Resist/wafer stack Resist type, thickness, process parameters Coatg Mask layout Pattern fidelity OPC methods Advanced mask technologies (phase shift, grey tones)

9 Contents Introduction Mask aligner lithography simulation OPC Methodologies A biasg example OPC for dots/holes Conclusions and outlook

10 OPC methodologies Artifacts known from projection prtg appear proximity prtg as well... le end shorteng Corner roundg iso-dense bias Solution high-end projection prtg: pre-distortion of the mask geometry to restore image fidelity OPC

11 OPC methodologies Typical OPC methods high-end projection prtg iso-dense bias mask biasg subresolution features le end shorteng serif hammerhead mousebite corner roundg serif Will it work also for mask aligner litho?

12 Contents Introduction Mask aligner lithography simulation OPC methodologies A biasg example OPC for dots/holes Conclusions and outlook

13 A biasg example Process wdow analysis for 3 µm dense and iso les 3 µm dense le on mask target: 3 µm +/- 10% 3 µm iso le on mask target: 3 µm +/- 10% gap: 15 µm gap: 15 µm Common dose latitude is much worse than the sgle dose latitudes!

14 A biasg example Let s try to modify the lewidths on mask (biasg) Common dose latitude vs. iso and dense lw on mask unbiased prox. gap: 15 µm target lw: 3 µm +/- 10% pitch for dense le: 6 µm

15 A biasg example Patterng at 20 µm gap 3 µm dense le on mask target: 3 µm +/- 10% Process wdow analysis 3 µm iso le on mask target: 3 µm +/- 10% gap: 20 µm gap: 20 µm Common dose latitude is zero! No chance to prt both dense and iso les with the given tolerance!

16 A biasg example Biasg for 20 µm gap Common dose latitude vs. iso and dense lw on mask prox. gap: 20 µm target lw: 3 µm +/-10% unbiased pitch for dense le: 6 µm

17 A biasg example Takg to account gap variations Common dose latitude at 15-µm-gap Common dose latitude at 20-µm-gap Dependg on the density of your structures, a certa bias will be necessary Simulation helps to fd the optimal parameter set

18 Contents Introduction Mask aligner lithography simulation OPC methodologies A biasg example OPC for dots/holes Conclusions and outlook

19 OPC for dots/holes Mask layout with serif type #2 with serif type #1 origal pattern, 5 µm x 5 µm

20 OPC for dots/holes Mask layout

21 OPC for dots/holes Comparison simulation to experiment - dots

22 OPC for dots/holes Comparison simulation to experiment - holes

23 Contents Introduction Mask aligner lithography simulation OPC methodologies Conclusions and outlook

24 Conclusions and outlook Lithography simulation is a valuable tool for process development layout verification and optimization Mask aligner simulation enables the development of OPC methodologies similar to projection lithography Biasg helps to enlarge the process latitude Assist features help to restore image fidelity Next steps: Adjust OPC structures for mask aligner lithography Develop tools for automation and the basis for model based OPC

25 Thank you for your attention!