DIRECT ELECTRON-BEAM WRITING WITH HIGH ASPECT RATIO

FOR FABRICATING ION-BEAM LITHOGRAPHY MASK

DIRECT ELECTRON-BEAM WRITING WITH HIGH ASPECT RATIO

FOR FABRICATING ION-BEAM LITHOGRAPHY MASK

2002. 04. 20.

Byeonug-Nam Lee, Yong-Hoon ChoDepartment of Physics, Chungbuk National University,

Cheongju 361-763, Korea.

Young-Seok Kim, and Wan Hong, Hyung-joo WooParticle Beam Application Team, Korea Institute of Geoscience and Mineral Resources, Daejeon, 305-35

0, Korea.

Introduction

Introduction

Lithography, it is that technology is able to transcribe narrow linewidth, exercises an effect on improvements in accumulation of DRAM and operation capacity of CPU. So, the main issue confronting the semiconductory industry is what the next generation lithography (NGL) should be. Problems of optical lithographyo The optical lithography can’t embody proven resolution below 0.1 ㎛ . (e.g., embodiment 0.13 ㎛ by ArF laser [193nm])o Optical lithography has aspect ratio about with 1:1,so that it don’t suit MEMS's purpose.(MEMS needs high aspect ratio.)

o aspect ratio: h / s

Masked Ion Beam Lithography (MIBL) is one of the most promising candidates. MIBL is a technology to produce advanced, very large scale integrated (VSLI) and nanometer-scale circuits. The strengths of MIBL include proven resolution below 0.04 ㎛ , wide exposure latitude, large depth of field, high throughput, and the possibility of avoiding substrate damage.

h

s

E-beam writing system E-beam writing system

EDA (digital-to-analog)

converter DA (digital-to-analog)

converter EDA (digital-to-analog)

converter DA (digital-to-analog)

converter (5MHz)

COMPUTER COMPUTER COMPUTER Writing tool

Home made writing program

SEM (Scanning Electron Microscopy)

SEM (Scanning Electron Microscopy)

SEM (Scanning Electron Microscopy)

SEM (Scanning Electron Microscopy)

COMPUTER COMPUTER COMPUTER Drawing toolAutoCAD-polyline

COMPUTER COMPUTER COMPUTER COMPUTER

dxf.file

•Output voltage control

Control signal=output voltage(V)

32768 10 (= Max V)

* Analog out put: 2

* Analog range: -10~ +10v

•Output voltage: divide into 65536 (16 bit)

Structure of blank & Final Ion-beam Mask Structure of blank & Final Ion-beam Mask

PMMA 0.4 ㎛Au 0.03 ㎛Ti 0.003 ㎛

Si3 N4 4 ㎛

Si

Blank Mask fFinal Ion-beam Mask

Ion beam

Si

Si(B) ,Si3N4

Ti

Au

Summary of sample stage & e-beam lith. Summary of sample stage & e-beam lith.

Faraday cup

Standard sample

mask

o Acc. voltage: 40 KeVo Writing 시 Beam current :10 ~ 20 Pao Writing 시 magnification : × 1000 o Focusing magnification on Standard sa

mple : × 300,000

65536

6553

6

o A screen of SEM is divided into a lattice of 65536 × 65536.

o The position of electron beam spot is lineally changed by run voltage

o Every lattice has voltage rectangular coordinates ; (Vx,Vy)

Designed pattern

Pattern designs Pattern designs The Pattern designs is using AutoCAD. o A space between two points is 1 ㎛ on Auto CAD coordinates.

16nm 50nm50nm

a) b)

Primary factor of aspect ratio & linewidth Primary factor of aspect ratio & linewidth

Aspect Ratio

&Line width

Develop - Developer - Temperature - Time

Blank Mask - Resist thickness - Resist uniformity

E-Beam Writing- Focusing- dosage- Beam energy

0.08 ㎛ 디자인 선 폭의 현상조건 실험0.08 ㎛ 디자인 선 폭의 현상조건 실험

mask( ㎛ )

가장 작은 선 폭

디자인( ㎛ )

writing

Dose(c/ ㎛ 2)

PMMA 0.35/Au 0.05/Ti 0.001/Si

0.1 100 ~ 450100

develop

time

(sec)

temp.

(℃)

developer rinse

60 ~120

60

35,4035

Morpholine 20%Ethanolamine 5%

diethylenglykol-monobutylether 60%Agua Regia 15%

diethylenglykol-monobutylether 80%

DI 20%

* 빨간 글씨 : 최적 조건

0.08 ㎛ 디자인 선 폭 최적화 조건0.08 ㎛ 디자인 선 폭 최적화 조건mask( ㎛ )

디자인 선 폭 ( ㎛ )

writing

Dose(c/ ㎛ 2)

PMMA 0.4/Au 0.05/Ti 0.001/

Si

0.1 250 ~ 550

350

develop

time

(sec)

temp.(℃)

developer rinse

60 Room temp.

Etoxyethanol 30% Methanol 70%

Methanol

현상된 선 폭( ㎛ )

종횡 비

0.167 1:2.4* 빨간 글씨 : 최적 조건

0.08 ㎛ 디자인 선 폭 최적화 조건0.08 ㎛ 디자인 선 폭 최적화 조건mask( ㎛ )

디자인 선 폭 ( ㎛ )

writing

Dose(c/ ㎛ 2)

PMMA 0.4/Au 0.05/Ti 0.001/

Si

0.08 200 ~ 550

350

develop

time

(sec)

temp.(℃)

developer rinse

60 Room temp.

Etoxyethanol 30% Methanol 70%

Methanol

현상된 선 폭( ㎛ )

종횡 비

0.135 1 : 3* 빨간 글씨 : 최적 조건

0.08㎛디자인350 μc/㎛2

KIGAM 20KV ×35,000 8mm

0.08㎛디자인350 μc/㎛2

KIGAM 20KV ×35,000 8mm

0.08㎛디자인350 μc/㎛2

KIGAM 20KV ×35,000 8mm

0.08 ㎛ 디자인350 μc/㎛2

KIGAM 20KV ×35,000 8mm

0.08㎛디자인350 μc/㎛2

KIGAM 20KV ×35,000 8mm

0.08 ㎛ 디자인350 μc/㎛2

KIGAM 20KV ×35,000 8mm

0.135( ㎛ )

0.05 ㎛ 디자인 선 폭 최적화 조건0.05 ㎛ 디자인 선 폭 최적화 조건mask( ㎛ )

디자인 선 폭( ㎛ )

writing

Dose(c/ ㎛ 2)

PMMA 0.4/Au 0.05/Ti 0.001/

Si

shasha7 200 ~1700

1400

develop

time

(sec)

temp.(℃)

developer rinse

60 Room temp.

Etoxyethanol 30% Methanol 70%

Methanol

현상된 선 폭( ㎛ )

종횡 비

0.14 1 : 2.5* 빨간 글씨 : 최적 조건

Result of proximity Control Result of proximity Control

조건 변화 0.08 ㎛ 디자인

선 폭 내 전자빔 조사량 차별화

현상된 선 폭

0.086 ~ 0.092 ( ㎛ )

Summary

Summary

Masked Ion Beam Lithography (MIBL) is one of the most promising candidates 차세대 노광 기술인 이온 빔 노광 기술 용 0.1 m 이하의 선 폭에 종횡비가 1:7 인 마스크 개발 목표로 실험을 수행하였다 .

A multiple-pass writing method has been implemented, which has significantly improved image placement of final ion beam masks. This method was optimized for image-size and defect performance on the e-beam lithography system. Image placement of 60nm was achieved. we could obtain an e-beam writing pattern with a line-width of ~ 80 nm and an aspect ratio of 1:5~.

실험결과는 Proximity Control 한 결과와 하지 않은 결과로 나누어 볼 수 있는데 , Proximity Control 한 결과 디자인 선 폭과 유사하게 현상되었다 . 실험은 0.086 선 폭에 종횡 비 1:4.65 인 패턴을 형성하였다 .

패턴 형성은 Proximity Control 한 결과가 계선 되었다 .