1. Contest and Pizza Party
June 11, 2013

2. Term Project on Surface Engineering (DM23757)
Objectives; Better understanding of process mechanism,
operating method and experimental results
Outline ; 상감기법 (Damascene Process) 을 응용한 창작품 제작
재료 제한 없음 (금속, 종이, 플라스틱, 세라믹, 나무 등)
Evaluation ; 1. 창의성 기술성 응용성 2
6월 7일까지 메일로 제출 늦으면 감점 -3
Contest ; June 11
1인당 1개의 작품을 전시, 1페이지에 작품에 대한 설명 첨부
학점에 35% 반영함과 동시에 상금 (3명에 10만원씩)

3. Boom Boom Speaker
최혜림
표면에 광섬유를 상감기법으로 적용하여 음악에 맞춰 불빛이 반짝이는 스피커 - 음악의 세기에 따라 스피커에 인가되는 전력의 차이가 발생함을 이용해 LED의 광량을 조절 - 빛을 전반사 시켜 손실 없이 이동 시킬 수 있는 광섬유를 이용해 LED 빛을 스피커 표면에서 빛나게 함
1. 도안 준비
2. 도안 부착
3. 스피커 가공
4. LED 연결
5. 스피커 가공 완료
6. 광섬유 준비
7. 광섬유 부착
8. LED-광섬유 연결

4. Cleaning Solution & Cleaner
Lecture 7
Cleaning Solution & Cleaner

5. Contents What is Cleaning Importance of Cleaning
Classification of Cleaning
Cleaning Solution
Selecting the cleaning solution
Development of Cleaning
Summary
Paper Review

6. 1. What is Cleaning ? Definition Pre-Cleaning Post-Cleaning
To reduce the surface contamination to a minimum level during semiconductor manufacturing processes in order to achieve higher yield.
Cleaning process for subsequent process. Ex) surface preparing, cleaning before CVD and furnace
Pre-Cleaning
To remove the contamination induced in previous process. Ex) post-CMP cleaning, Post PECVD
Post-Cleaning
Contamination
Cleaning 정의 오염물 분류

7. 1. What is Cleaning ? 전체 공정의 약 25%, 100개 이상의 공정에서 세정이 이루어짐
습식세정은 100도 이하의 온도에서 모든 물질을 용해 혹은 액중 분산시키고, 웨이퍼 표면에 손상을
주지 않는 등의 뛰어난 특징을 가지고도 그 중요성을 확보하고 있다.
요구사항 (1) 아주 청정한 표면을, (2) 부작용 없이, (3) 단시간 내에, (4) 높은 재현성을 가지고,
(5) 낮은 원가로 실현.
RCA 세정법을 기본으로 한 전통적인 반도체 습식 세정법
세정액
세정목적
부작용
H2SO4/H2O2 (SPM)
유기물, 금속
미립자
NH4OH/H2O2/H2O(APM)
미립자, 유기물 금속
HCl/H2O2/H2O(HPM)
금속(표면위)
HF/H20(DHF)
산화막, 금속(산화막내부)
귀금속(Cu등), 미립자
RCA 세정의 문제점
(1) 세정 공정수가 많다.
(2) 화학액 및 초순수의 사용량이 많다.
(3) 장치가 매우 크다.
(4) 오염 재부착으로 인해 고청정화가 곤란하다.
(5) 부식으로 인해 금속재료가 노출해 있는 표면 세정에는 사용할 수 없다.

8. 2. Importance of Cleaning
Cleaning process must be added after each process in semiconductor processes
Decrease of device dimensions
Reduction of electrical characteristics
Yield
파티클은 형상에 영향을 주고, 웨이퍼위에 있을 경우 압력이 가해졌을때 크랙이 발생할 우려가 있음. 메탈은 좁아지는 선폭 중앙에 있을 경우 도선 간에 쇼트가 생김. 정보 교환시 혼란이 발생함. 반도체 공정의 약 1/3이 세정공정임을 생각할때 세정의 중요성은 계속 커지고 있음.

9. Cleaning Mechanism 기능 1 오염의 이탈 - 파티클 오염 (불용성/난용성의 경우) → 물리력
 - 파티클 오염 (불용성/난용성의 경우) → 물리력
 - 금속오염 및 유기물 오염 → 용해 및 분해 기능
기능 2
오염의 재부착방지
 - 파티클 오염 → 제타 전위제어, 젖음성 제어 등
 - 금속 오염 → pH 산화환원전위 제어 / 킬레이트제 활용
기능 3
하부 막의 식각
 - 막 표면과 강고하게 화학 결합해 있는 오염, 막 내부에
   존재하는 오염

10. 3. Classification of Cleaning
< Mechanical Type >
Wet
Dry
Scrubber
Megasonic
Single-wafer spin
Aerosol
SCF
Contact
Noncontact
< Chemical solution >
APM (SC-1)
HPM (SC-2)
SPM
DHF
BOE
Ozonated / water
각종 화학재료의 화학식 언급 할것. Spm은 황산과 과산화 수소수.
에이피엠 암모니아. 에이치피엠 염산.
Metal
Particle
Metal
Heavy organic
Metal
Oxide Film
Metal
Oxide Film
Oxide Film
Metal

11. < SC-1 ; APM> Lift off < SC-2 ; HPM> Dissolution
4. Cleaning Solution
4 -1 RCA
< SC-1 ; APM> Lift off
Au, Ag, Cu, Ni, Cd, Zn, Co, Cr
Etching the particles
Prevention of readhesion
< SC-2 ; HPM> Dissolution
Sc2는 sc1에서 발생하는 금속오염을 제거 하기 위해. 탱크에 담그는 세정. 오염문제.
두가지 공정이 함께 사용되어진다.
HCl : H2O2 : DIW = 1:1:5 at 75~85℃
Heavy metal, Alkali ions, Metal hydroxides
Hydrophilic after the cleaning

12. Zeta Potential - Repulsive Force - Attractive Force Stern Layer +
Net
negative
charge +
Zeta potential
Stern Layer
Diffused Layer
Repulsive Force
Wafer -
Attractive Force +
Particle

13. < BOE > ; Buffered Oxide Echant
4-2. HF & BOE
< HF >
Oxide film
Metal except noble metal as Cu, Au
Impurity in oxide film
< BOE > ; Buffered Oxide Echant
H2o2를 첨가하면 FPM이라고 불린다.
NH4F + HF
Stable etch rate by buffer
High chemical wettability with surfactant

14. 4-3. O3 / HF(SCROD) Particle removal Metal removal DHF
Si + O3  SiO2 +O
Ozonated water
SiO2 + HF  H2O + SiF4
Oxide
By oxide film removal
Oxide removal
Particles removal
Particle removal
Metal removal
메커니즘 상세히 설명할것.

15. 5. Selecting the cleaning solution
Goal
Particle
Metal
Noble metal
Material of wafer Si
Copper
APM + Scrubber
SCROD
APM + Megasonic
Scrubber + DHF or HPM
Scrubber + HPM
DHF
Except

16. Reduction of process time Little light Chemistry
6. Development of Cleaning
Eco-friendly
여기서 레이저 크러스터 설명한다.
Reduction of process time
< IMEC >
Little light Chemistry

17. Brush force > Total interaction force
Scrubber Mechanism
van
der Waals
Energy
Electrostatic Energy (
Zeta Potential)
Total = +
Interaction ( (
Hamaker
Hamaker
constant
constant
Energy
+Particle
+Particle
size )
s size ) -
Attractive -
Repulsive/Attractive
Noncontact : Hydrodynamic drag force
Contact : Rotation torque of brush
Pva에 대한 사진과 설명
Brush force > Total interaction force
 Remove !

18. ∴ Physical Force > Total Energy Added chemical solution
Brush
Noncontact
Partial Contact
Full Contact
Removal force
Adhesion force
Removal force with DIW
Removal force with SC-1 N
Brush rpm
∴ Physical Force > Total Energy
Force
Scratch
Defects
Added chemical solution
Surfactant
브러쉬 컨텍 메카니즘, 2차 오염 메커니즘. 3가지 타입 설명.
버스니아 교수는 디아이워터와 풀컨텍 브러쉬 만으로 파티클이 제거되며 넌컨택에 화학액을 첨가한 경우에도 높은 알피엠에서는 제거가 가능함을 보였다. 입자가 큰 파티클 일수록 제거가 용이하다. 브러시의 간극이 좁을 수록.
< 0.1㎛, Noncontact >

19. < with surfactant >
Brush +
Brush out
< Readhesion >
Physical force
Zeta potential
< with surfactant >
Brush -
Brush out
Physical force
브러쉬의 재오염 문제 개념도 및 계면활성제의 필요성

21. Particle Deposition Mechanism
1. Physisorption(Van Der Waals Forces) :
E= - AR / 6D
2. Electrostatic Attraction
Surface charge : Zeta-Potential E
3. Chemisorption : Chemical reaction between particles and surfaces
4. Capillary Condensation : Fc = 4πRγL

22. 3 - 2. Megasonic Cavitation Acoustic streaming Radiation force
Megasonic energy( kHz)
메가소닉만으로 해결되는 것이아니라 sc-1용액이나 암모니아 용액에서 사용되어져야 효과적이다.

23. < Application of Megasonic >

24. 3 - 3. Single wafer spin < Single wafer spin >
< SEZ Spin Etcher >
단계별 드레인으로 오염의 최소화 가능, 작은 공간 설치 가능, 공정 단계의 간소화로
Lower chemical and water
High efficiency and short process time
Lower scratch by particles
With O3 / DHF / N2

25. N2 Gas is more light than CO2, Ar
Cryogenic Aerosol-based Cleaning Technology
Physical force of Aerosol
No surface tension
Conventional gas : CO2, Ar
 Damage of pattern in semiconductor
N2 Gas is more light than CO2, Ar
에어로솔로 이산화탄소, 아르곤 사용 페턴에 영향, 동일한 효과를 가지는 질소사용.

26. 3 - 5. SCF (Super Critical Fluid) cleaning
Damage of pattern in Wet cleaning by surface tension
Environment problem
Dry process
SCF Cleaning
CO2 (31℃, 7.3MPa)
Super critical fluid
:Surface tension is zero
임계유체. 에어로솔과 함께 친 환경적인 크리닝. 레이져 세정기술

27. 3-6. 기능수 세정
전해 환원수와 수소용해수의 세정능력 비교
전해 환원수에 의한 CMP후 세정효과

28. 7. Summary
Cleaning solution is selected by slurry, wafer and kind of removed material.
Cleaning station must be composed of machine and chemical solution.
Reduction of damage by surface tension.
Goal of cleaning solution is little light chemistry in the future.
Recently, many researches are progressing Cu CMP cleaning
As development of new materials and size reduction of device, cleaning solution and cleaner will be important.

29. A Study on Particle Removal of PVA Brush
Paper review
A Study on Particle Removal of PVA Brush
Cleaning based on Contact Mode

30. 2006 ITRS Road Map
2006
2008
2010
2012
Maximum Substrates Diameter (mm)
300
450
DRAM 1/2 Pitch (nm) 70 57 45 36
Particle size (nm) at front
> 90
> 65
> 45
Particle (ea/㎠) at front
> 0.17
Particle (ea/wafer) at front
< 116
< 120
< 115
< 265
Particle size (nm) at back
> 160
> 140
Particle (ea/wafer) at back
< 400
< 200
Cleaning process occupies more than 35% of semiconductor fabrication.
As pattern size decrease, effect of defect is becoming large.
Cleaning process performance affect directly device yield and cost.
Eco-friendly process
Production rate = 4 times
다음 표는 ITRS,…

31. Post-Cu CMP Cleaning CMP Process Post-Cu CMP Cleaning
Metal Trench
Electroplating Cu
Via
Substrate
Damascene Patterning
Metal Dep. & Anneal
CMP Process
Post-Cu CMP Cleaning

32. Conventional Chemical Cleaning
RCA cleaning process (SC-1, SC-2)
Wet Station
Chemical
Component
Chemical Ratio
Time
Target Contamination
SC-1
NH4OH:H2O2:H2O
(50~90 ℃)
1:1:5~0.05:1:5
10 min~
Particle,
Organic and Metal
SC-2
HCl: H2O2:H2O (80~90 ℃)
1:1:6~1:2:8
Noble Metal,
Alkaline ions
Disadvantage
Yearly chemical use / wet station
19,235 Gallon
Waste huge chemistry and DIW
Environment Problem
Cross contamination
Chemical attack (corrosion, etching)
Non-uniform cleaning performance
Yearly DI water use / wet station
64,821,120 Gallon
따라서 물리적 세정의 중요성이 커지고 있다라고 마무리
Yearly chemical cost / wet station
$ 1,136,300
Based on 8” wafer, 96 run/day
Data from Semiconductor International 2000

33. Brush Cleaning Advantage Disadvantage Does not make dusts
Typical physical properties of the PVA brush
Porosity (%)
85-95
Average pore size (㎛)
Apparent density (g/㎤)
30 % compressive stress (g/㎠)
10-110
Tensile strength (kg/㎠)
2-6
Tensile elongation (%)
Water absorption (wt%)
Maximum allowable temperature (℃)
80 dry, 60 wet
Decomposition point (℃)
170
Advantage
Disadvantage
Does not make dusts
Good chemical stability
Strong cleaning force
Double side cleaning
Pattern damage due to contact process
Contamination stuck
Inducing scratch
브러시공정이 가지는 단점을 보완하기 위하여 본 연구가 진행되었다 라고 마무리

34. Background The boundary of partial and ideal contact is vague.
J. Taylor, “Yield Enhancement through Understanding the Particle Adhesion and Removal Mechanisms in CMP and Post CMP Cleaning processes”, IEEE Advanced Semiconductor Manufacturing Conference, pp , 2000
A. A. Busnaina, “Particle Adhesion and Removal Mechanisms in Post-CMP Cleaning Processes”, IEEE Transaction on Semiconductor Manufacturing, Vol. 15, No. 4, pp , 2002
The boundary of partial and ideal contact is vague.
Difficult realization of partial and ideal contact.
While brush cleaning has been widely used, little theoretical work has been done in the fields.
연구에 앞서 사전 문헌조사를 실시하였습니다.

35. Non-contact condition Full contact condition
Monitoring System
Monitoring Sys’
Contact condition
Non-contact condition
Velocity
Gap between brush and wafer
Particle removal efficiency
Full contact condition
Friction force
Re-adhesion of particle
Monitoring Sys’
Scratch
Defectivity
AFM lithography

36. Objective

37. Particle Adhesion on Different SurfaceCu
After CMP Process
PETEOS
180 nm
PETEOS Cu - - -
Repulsive force
Attractive force - - - Cu
PETEOS
Many particles remain selectively on Cu surface, rather than on PETEOS.
We focus on the particle removal from the Cu surface after Cu CMP process.

38. Experimental Setup: GnP Cleaner system
GnP Cleaner812L
Applicable Wafer Size : 8inch and 12 inch
Configuration :
Stand alone with 4 cleaning stations
- 1 Pre Cleaning with DIW Spray
 - 2 Double-side Roll Brush Cleaning
- 1 Spin Rinse Dry with N2 Blow
Size
- 1700W 960D 1300H
- Brush size : Ø70(OD) Ø32(ID) Ø320(L)
Ø38(OD) Ø22(ID) Ø310(L)
Chemical : NH4OH ~1wt% available
Brush type : PVA brush, Both side of wafer cleaning
Brush rotation speed : Max 300rpm
Spin speed : Max 2500rpm
DI rinse / N2 blow
Control Module
- PC Monitor Interface
- Programmable Sequence
- Sequence Control: PC
Pre-cleaning
Brush scrubbing
Spin rinse dry
Megasonic

39. Definition of Terms Brush Module
1. Contact force: Contact force is defined as a force to pressurize a wafer.
Brushes
2. Friction force : Friction force is defined as a force generated between brushes and wafer
wafer
Brushes
3. Brush overlap: Brush overlap is the amount of overlap between wafer and brush.
Brush
Brush Module

40. Data Acquisition Program- CleanEYE
Contact
force
Friction
force
Contact
force
Friction
force
Contact force
Friction force

41. Brush scrubbing time (s)
Experimental Condition
Parameter
Conditions
Wafer
4 inch blanket wafer (CVD Cu deposition 1㎛)
8 inch PETEOS for re-adhesion test
Slurry
TST-D2 (Techno Semichem Co.),
Mean diameter of abrasive : 60nm
pH : 10
Cleaning solution
Citric acid (0.5 wt%), BTA (0.03 wt%)
NH4OH (1 wt%)
Pre-cleaning time (s) 10
Brush scrubbing time (s) 60
Spin dry speed (rpm)
3000
Spin dry time (s)
Brush velocity (rpm)
240
Brush gap (㎛)
Under 10
문헌연구

42. Non-Contact Condition
Ref : Busnaina et al, “Particle adhesion and removal mechanisms in post-CMP cleaning process”, 2002

43. Results of Non-Contact Condition: Brush Velocity
60 rpm
120 rpm
240 rpm

44. Results of Non-Contact Condition: Brush Gap

45. Theoretical Mechanism of Full Contact Condition
Johnson-Kendall-Roberts (JKR) equation.
P : Load R : Radius a : Contact area W : Interaction Force
FA : Adhesion force between two material
r : Contact Radius W : Thermodynamic work of adhesion
Ref : Fan Zhang et al, Journal of Electrochemical Society,1999
화학세정공정의 단점 추세 물리적 세정공정의 이점 추세
Contact Area
Small
Middle
Large
Adhesion Force
Small
Middle
Large

46. Monitoring System for Friction Force
Friction Force Monitoring Sys
Charge
Amp. F2
A/D conv. F1 PC

47. Results of Full Contact Condition: Friction Force
0.117kgf
0.195kgf
Scratch length
0.406kgf
0.601kgf

48. Scratch Test on Cu surface: Experiment
XE-100
AFM lithography mode
Probe  single crystal silicon
1000 nN ~ 6000 nN
Properties of PPP-NCHPt non-contact probe
Typical Value
Specified Values
Thickness (㎛) 4
Mean width (㎛) 30
Length (㎛)
125
Force constant (N/m) 42
10-130
Resonance frequency (kHz)
330
Guaranteed tip radius of curvature (nm)
< 10
PPP-NCHPt non-contact probe

49. Scratch Test on Cu surface: Results
4000 nN
5000 nN
6000 nN

50. Scratch Test on Cu surface: before and after
5000 nN B B
6000 nN A B A B

51. Conclusion
문헌연구
10-10 ~10-11 N
10-6 ~10-7 N

52. Conclusion
Contact condition was classified into two broad categories (non-contact and full contact) using monitoring system.
In non-contact condition, removal efficiency was dominated by velocity and gap between brush and wafer, which matched well theoretical mechanism.
High friction force have strong removal force, but it is poor to defectivity.
Through AFM scratch test, force that induced scratch could be estimated.
Full contact condition had re-adhesion problem by contaminating brush.
문헌연구