1 L. Pang, eBeam Initiative Reception at BACUS 2015

Mask Metrology in the ILT World

Linyong (Leo) Pang D2S, Inc.

Sept. 29, 2015 Managing Company Sponsor

2 L. Pang, eBeam Initiative Reception at BACUS 2015

A Decade of ILT!

6 Papers

2 Foundries

1 Memory

1 Mask shop

2005

3 L. Pang, eBeam Initiative Reception at BACUS 2015

ILT Adopted as the Way Forward

>200 Papers Officially

announced

2014 panel

Today

ILT expertise proliferated

4 L. Pang, eBeam Initiative Reception at BACUS 2015

But What About CD Metrology?

VS

B.G. Kim, et al., BACUS, 2012

New World: ILT Mask Pattern

Old World: Conventional Mask Pattern

B.G. Kim, et al., PMJ, 2009

5 L. Pang, eBeam Initiative Reception at BACUS 2015

ILT CD is not just line width: it’s 2D!

What to use as a reference?

Which mask issues impact the wafer?

Contour and EPE

Simulated mask pattern

Wafer plane analysis

What is CD In the ILT World?

6 L. Pang, eBeam Initiative Reception at BACUS 2015

Mask Plane Metrology: Contour and EPE Measurements

•  EPE measured on entire contour •  Histogram: mean, 3 sigma

7 L. Pang, eBeam Initiative Reception at BACUS 2015

Mask Plane Metrology: Contour and EPE Measurements

EPE measured on entire contour

PV band

8 L. Pang, eBeam Initiative Reception at BACUS 2015

Mask Plane Metrology: Contour and EPE Measurements

0

5000

10000

15000

20000

-6 -5.6 -5.2 -4.8 -4.4 -4 -3.6 -3.2 -2.8 -2.4 -2 -1.6 -1.2 -0.8 -0.4 0

EPE Histogram (Mask)

Count 95883 Min (nm) -6.00 Max (nm) -0.84 Mean (nm) -1.83 Median (nm) -1.71 3 Sigma (nm) 2.14

9 L. Pang, eBeam Initiative Reception at BACUS 2015

Mask Plane Metrology: What is the Target for EPE?

OPC Design •  No corner

rounding •  Affected by

corner EPE

•  What OPC thinks the mask shape will be

Simulated mask pattern •  Model of

actual mask shape

Mask Shape

10 L. Pang, eBeam Initiative Reception at BACUS 2015

Wafer Plane Metrology: Traditional CD and Wafer Impact in One Simulation

11 L. Pang, eBeam Initiative Reception at BACUS 2015

Wafer Plane Metrology: Traditional CD and Wafer Impact in One Simulation

12 L. Pang, eBeam Initiative Reception at BACUS 2015

Wafer Plane Metrology: Traditional CD and Wafer Impact in One Simulation

0 500

1000 1500 2000 2500 3000 3500 4000

-10 -9.6 -9.2 -8.8 -8.4 -8 -7.6 -7.2 -6.8 -6.4 -6 -5.6 -5.2 -4.8 -4.4 -4

EPE Histogram (Wafer)

Count 23468 Min (nm) -9.14 Max (nm) -4.12 Mean (nm) -5.91 Median (nm) -5.81 3 Sigma (nm) 2.80

13 L. Pang, eBeam Initiative Reception at BACUS 2015

Mask CDU ≠ Wafer CDU: Wafer Metrology is Required

0 500

1000 1500 2000 2500 3000 3500 4000

-10 -9.6 -9.2 -8.8 -8.4 -8 -7.6 -7.2 -6.8 -6.4 -6 -5.6 -5.2 -4.8 -4.4 -4

EPE Histogram (Wafer)

0

5000

10000

15000

20000

-6 -5.6 -5.2 -4.8 -4.4 -4 -3.6 -3.2 -2.8 -2.4 -2 -1.6 -1.2 -0.8 -0.4 0

EPE Histogram (Mask)

14 L. Pang, eBeam Initiative Reception at BACUS 2015

Old World: Mask CD Only ILT World: Mask and Wafer

Mask CD Metrology

Mask Plane Metrology

Contour

EPE

Wafer Plane Metrology

CD

EPE

2D Metrology

Convert back to 1D Metrology

15 L. Pang, eBeam Initiative Reception at BACUS 2015

With GPU, the Simulation-based Wafer Plane Metrology is Real Time

16 L. Pang, eBeam Initiative Reception at BACUS 2015

2D 3D

Mask

Aerial image

0

500

1000

1500

2000

2500

3000

FRM3D GPU FDTD CPU GPU 3D mask sim >1000 times faster

Runtime (seconds)

With GPU, the Simulation-based Wafer Plane Metrology is Real Time

17 L. Pang, eBeam Initiative Reception at BACUS 2015

Future: Improve Mask and Wafer Quality

Mask plane & wafer plane

metrology

Mask writer GEC

Wafer dose map

•  Shorten time to get wafer CDU map

•  Attain SEM-level repeatable accuracy

•  Improve mask writing

18 L. Pang, eBeam Initiative Reception at BACUS 2015

The New ILT World Calls for New CD Metrology: Mask and Wafer!

Mask Wafer

19 L. Pang, eBeam Initiative Reception at BACUS 2015

The New ILT World Calls for New CD Metrology: Mask and Wafer!

Wafer

CD, EPE, PV Band, Histogram

0

2000

4000

-10

-9.6

-9.2

-8.8

-8.4 -8

-7

.6 -7

.2 -6

.8 -6

.4 -6

-5.6

-5.2

-4.8

-4.4 -4

EPE Histogram (Wafer)

Mask

Contour, EPE, PV Band, Histogram

0

10000

20000

-6

-5.6

-5.2

-4.8

-4.4 -4

-3

.6 -3

.2 -2

.8 -2

.4 -2

-1.6

-1.2

-0.8

-0.4 0

EPE Histogram (Mask)

GPU = Real-time for mask + wafer

20 L. Pang, eBeam Initiative Reception at BACUS 2015