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High-End EUV Photomask Repairs for Advanced Nodes

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High-end EUV Photomask Repairs for advanced nodes

Dr. Michael Waldow

Product Manager

vZTech - Virtual SMS Tech Conference, 18.05.2021

Agenda

1 Introduction

2 High-end EUV photomask repairs

3 Summary

  • Carl ZEISS SMT GmbH, Dr. Michael Waldow, Semiconductor Mask Solutions
  • 18.05.2021
  • 2

Agenda

1 Introduction

2 High-end EUV photomask repairs

3 Summary

  • Carl ZEISS SMT GmbH, Dr. Michael Waldow, Semiconductor Mask Solutions
  • 18.05.2021
  • 3

Introduction

EUV High-Volume manufacturing ramping up

SAMSUNG newsroom MAY 21, 2021

“…new production line in Pyeongtaek, Korea…will produce 14-

nanometer DRAM and 5-nanometer logic, …based on EUV...”

Anandtech.com - APRIL 02, 2021
C. C. Wei – TSMC - CEO & Vice Chairman* JULY 16, 2020

‚Next, let me talk about our N5 ramp up and N4 introduction. N5 is the foundry industry's most advanced solution with best PPA. N5 is already in volume

production with good yield, while we continue to improve the productivity and performance of the EUV tools. We are seeing robust

demand for N5 and expect a strong ramp of N5 in the second half of this year, driven by both 5G smartphones and HPC applications.‘
“… South Korea authorities this week gave SK Hynix a green light to build a new, 120 trillion won ($106.35 billion) fab complex….

using process technologies that rely on extreme ultraviolet lithography (EUV)…’

▪ EUV is becoming more and more important and

Intel: The Empire Strikes Back**

MAY 21, 2021

amount of EUV lithographic layers is rising

‚while the outlook on EUV was still quite uncertain. Hence, Intel's initial 7nm

seems to have used EUV quite conservatively, in relatively few layers. Intel said the new 7nm process flow (as it has been developed since mid-2020) uses over

100% more EUV. We have now fully embraced EUV", Pat Gelsinger

said…’

▪ First consumer products based on EUV technology are already on the market

▪ On the other hand EUV photomasks possess the highest numbers of defects

Sources

Efficient and reliable way to repair high- end photomasks is essential

**Q2 2020 Taiwan Semiconductor Manufacturing Co Ltd Earnings Call,

**https://seekingalpha.com/article/4427816-intel-the-empire-strikes-back

  • Carl ZEISS SMT GmbH, Dr. Michael Waldow, Semiconductor Mask Solutions
  • 18.05.2021
  • 4

Introduction – Photomask repair

MeRiT® Mask repair technology

Photomask repair tool MeRiT® at a glance

▪ MeRiT® neXT system is the industry-standard

for high-end photomask repair systems
▪ Enables the repair of smallest defects on todays’ photomasks

Principle of operation

▪ Exposure with focused electron beam

▪ Adsorption of precursor molecules

  • Repair of clear defects - deposition
  • Repair of opaque defects - etching

  • Carl ZEISS SMT GmbH, Dr. Michael Waldow, Semiconductor Mask Solutions
  • 18.05.2021
  • 5

What is contributing to resolution of MeRiT® Tools

Analogy: What contributes to draw with high accuracy?

Analogy: Contributions to draw with high accuracy

Ink Spilling

Drawing
Small

Shiver/

Tremor
Sharpness

  • Carl ZEISS SMT GmbH, Dr. Michael Waldow, Semiconductor Mask Solutions
  • 18.05.2021
  • 6

What is contributing to resolution of MeRiT® Tools

Transfer to MeRiT® technology - Electron beam as a pen and precursor molecules as ink

Contributions to MeRiT® repair resolution

Secondary Electrons

Repair
Resolution

System

Jitter
E- Beam Spot Size

  • Carl ZEISS SMT GmbH, Dr. Michael Waldow, Semiconductor Mask Solutions
  • 18.05.2021
  • 7

Contributing to resolution of MeRiT® Tools

Main factor I to Repair Resolution – Secondary Electrons

Secondary electrons as function of electron voltage

140% 120% 100%

80%

60%

Secondary Electrons

40% 20%

0%

Repair
Resolution

  • 200
  • 400
  • 600
  • 800
  • 1000
  • 1500
  • 2000

Electron beam voltage [V]

▪ Scattered secondary electrons increase significantly with increasing voltages

E- Beam Spot
Size
System Jitter

Higher repair resolutions can be achieved by operation at lower electron beam voltages

  • Carl ZEISS SMT GmbH, Dr. Michael Waldow, Semiconductor Mask Solutions
  • 18.05.2021
  • 8

Contributing to resolution of MeRiT® Tools

Main factor II to Repair Resolution – Electron Beam Spot Size

Beam spot size as function of electron voltage

140% 120% 100%
80%

Standard column

New column

60%

Secondary Electrons

40% 20%
0%

Repair
Resolution

  • 200
  • 400
  • 600
  • 800
  • 1000
  • 1500
  • 2000

Electron beam voltage [V]

▪ In general electron beam column resolution decreases with

E- Beam Spot Size

decreasing voltage

System Jitter

For higher repair resolution a new column with a smaller beam spot size at given voltage need to be used

  • Carl ZEISS SMT GmbH, Dr. Michael Waldow, Semiconductor Mask Solutions
  • 18.05.2021
  • 9

Contributing to resolution of MeRiT® Tools

Main factor III to Repair Resolution – System Dynamics

Tool jitter as as function of diffrent tool platforms

Tool Jitter MeRIT tools
100%
75%

Standard Tool Platform

50% 25%
0%

New Tool PLatform

Secondary Electrons

-25% -50% -75%
-100%

Repair
Resolution

  • 0
  • 0,2
  • 0,4
  • 0,6
  • 0,8
  • 1
  • 1,2
  • 1,4

Time [s]

▪ MeRiT® repair resolution is detoriated by tool vibrations/jitter

System

Jitter

E- Beam Spot
Size

In order to make use of full potential of new MeRiT® repair tools, system jitter has to be minimized

  • Carl ZEISS SMT GmbH, Dr. Michael Waldow, Semiconductor Mask Solutions
  • 18.05.2021
  • 10

MeRiT® LE overview

Next generation mask repair tool

MeRiT® LE - What‘s new?

1. MeRiT® LE is operating at lower electron voltage

▪ Tool is optimized for lower energy of 400eV compared to

MeRiT® neXT, which operates at 600eV

2. MeRiT® LE is equiped with a new electron beam column

▪ Tool is equipped with Low-kV Objective Lens optimized for low beam energies

3. Improved system jitter enabling highest repair resolution

▪ Re-designed tool platform including improved acoustic enclosure and improved tool damping

  • Carl ZEISS SMT GmbH, Dr. Michael Waldow, Semiconductor Mask Solutions
  • 18.05.2021
  • 11

Agenda

1 Introduction

2 High-end EUV photomask repairs

3 Summary

  • Carl ZEISS SMT GmbH, Dr. Michael Waldow, Semiconductor Mask Solutions
  • 18.05.2021
  • 12

High-end EUV photomask repairs

MeRiT® repair and AIMS® EUV actinic measurements in the mask shop ecosystem

Mask making process

Pattern
Generation

Cleaning

  • Metrology
  • Tuning
  • Inspection
  • Disposition
  • Repair

Verification

MeRiT® Repair

AIMS® EUV

AIMS® EUV

  • 1
  • 2
  • 4

3





  • Defective
  • Defect-free

  • EUV mask
  • EUV mask

Printability test by
AIMS® EUV technology
Detailed analysis by high resolution e-beam
E-beam mask repair by MeRiT®
Printability check after repair by AIMS® EUV

  • Carl ZEISS SMT GmbH, Dr. Michael Waldow, Semiconductor Mask Solutions
  • 18.05.2021
  • 13

High-end EUV photomask repairs

EUV ETCH repair of bridge defect

Bridge Defect

Defect Type: Bridge defect

▪ Length 500nm ▪ Half-Pitch 60nm on mask

MeRiT® LE repair

Pre-repair SEM image

MeRiT® LE

Post-repair SEM image

repair

AIMS® EUV analysis

  • Carl ZEISS SMT GmbH, Dr. Michael Waldow, Semiconductor Mask Solutions
  • 18.05.2021
  • 14

High-end EUV photomask repairs

AIMS® EUV Analysis of bridge defect repair

Analysis of CD with AIMS™ Auto Analysis (AAA)

Post-repair aerial image by AIMS™ EUV

Bridge Defect

x

MeRiT® LE repair

Shown results are at best focus

y

Along center of defect

▪ Along the center of the defect the CD variation is

AIMS® EUV analysis

below the CD variation of the reference structures
▪ A maximum ΔCD of 2.6nm results for the repair

Successful EUV bridge repair verified by AIMS® EUV

  • Carl ZEISS SMT GmbH, Dr. Michael Waldow, Semiconductor Mask Solutions
  • 18.05.2021
  • 15

High-end EUV photomask repairs

Small extrusion defect on a EUV photomask

Defect Type: Extrusion

Bridge Defect

Analysis of CD with AIMS® Auto Analysis (AAA)

▪ Length 500nm ▪ Half-Pitch 88nm on mask

98 96 94 92 90 88 86 84

CD Along center of defect

SEM defect image

Tiny <10nm extrusion!

AIMS® EUV

printability test

AIMS® EUV defect image

  • -500
  • 0
  • 500

Y position / nm

MeRiT® LE repair

▪ Aerial image is clearly affected by tiny extrusion defect
▪ On average detected CD deviation from reference analysed to be smaller than 10nm

  • Carl ZEISS SMT GmbH, Dr. Michael Waldow, Semiconductor Mask Solutions
  • 18.05.2021
  • 16

High-end EUV photomask repairs

EUV ETCH repair of small extrusion defect

Defect Type: Extrusion repair

▪ Length 500nm

Extrusion Defect

▪ Half-Pitch 88nm on mask

Tiny <10nm extrusion!

MeRiT® LE repair

Pre-repair SEM image

AIMS® EUV analysis

MeRiT® LE repair

Post-repair SEM image

  • Carl ZEISS SMT GmbH, Dr. Michael Waldow, Semiconductor Mask Solutions
  • 18.05.2021
  • 17

High-end EUV repairs

AIMS® EUV Analysis of tiny extrusion repair

Analysis of CD with AIMS® Auto Analysis (AAA)

Post-repair aerial image by AIMS® EUV

Extrusion Defect

92 90 88 86 84

Repair

x

MeRiT® LE repair

Shown results are at best focus

y

Along center of defect

  • 0
  • 500
  • 1000
  • 1500

CD Center Y [nm]

▪ Along the center of the defect the CD variation is

AIMS® EUV analysis

below the CD variation of the reference structures
▪ A maximum ΔCD of 3.3nm results for the repair

Successful tiny extrusion repair <10nm verified by AIMS® EUV

  • Carl ZEISS SMT GmbH, Dr. Michael Waldow, Semiconductor Mask Solutions
  • 18.05.2021
  • 18

High-end EUV photomask repairs

EUV DEPO broken-line defect repair

Defect Type: Broken-line

▪ Length 500nm

Broken Line Defect

▪ Half-Pitch 60nm on mask

MeRiT® LE repair

Pre-repair SEM image

MeRiT® LE

AIMS® EUV analysis

Post-repair SEM image

repair

  • Carl ZEISS SMT GmbH, Dr. Michael Waldow, Semiconductor Mask Solutions
  • 18.05.2021
  • 19

High-end EUV photomask repairs

AIMS® EUV Analysis of broken line defect repair

Post-repair aerial image by AIMS™ EUV

Analysis of CD with AIMS™ Auto Analysis (AAA)

Broken Line Defect

62 61 60 59 58 57 56

x

MeRiT® LE repair

Shown results are at best focus

Along center of defect

y

  • -800
  • -600
  • -400
  • -200
  • 0
  • 200
  • 400
  • 600
  • 800

y / nm

▪ Along the center of the defect the CD variation is

AIMS® EUV analysis

about the CD variation of the reference structures
▪ A maximum ΔCD of 3.8nm results for the repair

Successful EUV broken line repair verified by AIMS® EUV

  • Carl ZEISS SMT GmbH, Dr. Michael Waldow, Semiconductor Mask Solutions
  • 18.05.2021
  • 20

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  • Contact Photolithography at Sub-Micrometer Scale Using a Soft Photomask

    Contact Photolithography at Sub-Micrometer Scale Using a Soft Photomask

    micromachines Article Contact Photolithography at Sub-Micrometer Scale Using a Soft Photomask Chun-Ying Wu , Heng Hsieh and Yung-Chun Lee * Department of Mechanical Engineering, National Cheng Kung University, Tainan 70101, Taiwan * Correspondence: [email protected] Received: 14 July 2019; Accepted: 16 August 2019; Published: 18 August 2019 Abstract: This paper proposes a method for improving the patterning resolution of conventional contact photolithography from the micrometer, down to the sub-micrometer scale. The key element is a soft polydimethylsiloxane (PDMS) photomask, which is first replicated from a silicon mold and then patterned with a black photoresist (PR) layer to selectively block ultraviolet (UV) light. This soft PDMS photomask can easily form an intimate and conformable contact with a PR-coated substrate and hence can perform contact photolithography with high pattern resolution. The fabrication processes of this black-PR/PDMS soft photomask are experimentally carried out. Using the fabricated soft photomask, UV patterning by contact photolithography with the smallest line-width of 170 nm over a 4” wafer area was successfully achieved. The advantages and potentials of this new type of contact photolithography will be addressed. Keywords: soft photomask; contact photolithography; black photoresist; ultraviolet patterning; sub-micrometer scale 1. Introduction Photolithography technologies have been successfully developed in the past few decades and are now the most mature and dominant method for micro- and nanofabrication in the industry [1–4]. There are basically two categories of photolithography. The image-projection photolithography utilizes an ultraviolet (UV) light source and an optical image projection system to project a de-magnified pattern defined by a glass or quartz photomask onto a photo-sensitive layer (known as a photoresist (PR) layer) deposited on a substrate.
  • Prototyping of Masks, Masters, and Stamps/Molds for Soft Lithography Using an Office Printer and Photographic Reduction

    Prototyping of Masks, Masters, and Stamps/Molds for Soft Lithography Using an Office Printer and Photographic Reduction

    Anal. Chem. 2000, 72, 3176-3180 Prototyping of Masks, Masters, and Stamps/Molds for Soft Lithography Using an Office Printer and Photographic Reduction Tao Deng, Hongkai Wu, Scott T. Brittain, and George M. Whitesides* Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138 This paper describes a practical method for the fabrication microelectronics,6 because it bypasses the requirement for chrome of photomasks, masters, and stamps/molds used in soft masks. It also obviates the need for more readily available but lithography that minimizes the need for specialized equip- still specialized devices such as high-resolution printers.7 The work ment. In this method, CAD files are first printed onto reported here does not represent new science: it intentionally paper using an office printer with resolution of 600 dots/ focused on the exploitation of the simplest and most broadly in. Photographic reduction of these printed patterns available techniques that we could identify for forming patterns transfers the images onto 35-mm film or microfiche. with features useful in functional microstructures. These straight- These photographic films can be used, after development, forward methods, when combined with soft lithography,8 extend as photomasks in 1:1 contact photolithography. With the the capability for microfabrication of laboratories that have no (or resulting photoresist masters, it is straightforward to limited) access to the facilities required to fabricate chrome masks fabricate poly(dimethylsiloxane) (PDMS) stamps/molds or to carry out high-resolution printing. for soft lithography. This process can generate micro- The objective of this work is to develop and compare methods structures as small as 15 µm; the overall time to go from for generating microstructures using facilities readily and inex- CAD file to PDMS stamp is 4-24 h.