MOCVD半導體製程即時監控系統

1. MOCVD半導體製程即時監控系統
Speaker: Ju-Yi Lee
Department of Mechanical Engineering, National Central University, Taiwan.

2. Outline
1. Introduction
2. Principle
3. System configuration
4. Experiments & Results
5. Conclusion

3. INTRODUCTION
Background
Literatures review
Commercial products
Purpose

4. 紅豆餅

5. Background
• Thin film deposition
• Metal Organic Chemical Vapor Deposition
 Application
- Solar cell
- Power chip
 Process condition
- High temperature
- High vacuum
Deposition
Chemical Vapor Deposition
MOCVD
PECVD
Physical Vapor Deposition
Evaporation
Sputtering
Vapor
Deposition
Liquid Phase
Epitaxy
Wafer
Curvature
Growth
Rate
Film
Uniformity
Wafer
Temperature
Source: itri

6. Literatures review (Growth rate & Temperature)
• Thin film growth rate measurement
 Quartz crystal microbalance
a
 Reflectance interferometry
b
• Temperature measurement
 Two-color and Multi-wavelength pyrometry
c
a: C. S. Lu and O. Lewis, “Investigation of film ‐ thickness determination by oscillating quartz
resonators with large mass load”, 1972.
b: J.A. Dobrowolski, “Optical Properties of Thin Films and Coating” Chap.42 of Handbook of Optics,
McGraw-Hill, Inc, 1995.
c: B. Müller, U. Renz, “Development of a fast fiber-optic two-color pyrometer for the temperature
measurement of surfaces with varying emissivities”, Review of Scientific Instruments, 2001.
Source: ADVANTEST
Source: c

7. Literatures review (Temperature on surface)
• Wafer materials：Si, Sapphire, SiC, etc.
• GaN/InGaN layer measurement
Material transmittance
400 nm wavelength
No Fabry-Pérot interferometer

8. Literatures review (Wafer curvature)
• LayTec EpiCurveTT：
 Curvature range: -7000 km-1(convex) to +800 km-1(concave)
 Aspherical bowing curvature measurements with an
Advanced Resolution option
Source:LayTec

9. Commercial products
• FRT, kSA, LayTec, etc.
• The accuracy of equipment：
e.g., LayTec EpiTT
» Typical growth rate accuracy better than ±1%
» Typical wafer temperature accuracy better than ±1℃

10. Purpose
• Monitor of wafer parameters
Growth rate & Temperature monitoring devices
Enhance quality
Cost down
Source: LayTec

11. PRINCIPLE
Measurement of Growth rate
Blackbody Radiation Theorem
Measurement of Temperature
Curvature measurement

12. Measurement of Growth rate
• Index of refraction and growth rate
  nfsolven 
nTn
w
G
24




nGw

4

sL RRR  0
T
w
2

2
2
2
0
2
0
)(
)(
)(
)(
s
s
L
nn
nn
nn
nn
R






             021214214122f(n)
222234
 LsssLssssLsLL RnnnnRnnnnnRnnRnR
)cos(21
)cos(2
00
002


ss
ss
RRRR
RRRR
rR



nGtnd





22

Substrate
Light Ii
Reflected
Light Io
2
22
2
2
0
2
0
2
0
02
00
)(
)(
)(
)(
s
s
s
s
ss
nn
nn
NN
NN
rR
nn
nn
NN
NN
rR













13. Blackbody Radiation Theorem
0 1000 2000 3000 4000 5000 6000 7000
0
5
10
15
20
25
30
600℃
700℃
800℃
900℃
1000℃
1100℃
1200℃
(nm)
E
b
(Wm-2
sr-1
nm-1
)
• Planck’s law
 
1
1
,
2
5
1


T
cb
e
c
TE



• Kirchhoff’s law
• Real-body radiation
   TETE breal ,,  



 1
  1
1c
2c
: Planck’s first constant
: Planck’s second constant


: Absorption
: Reflectance
 : Transmittance
 : Emissivity

14. Measurement of temperature
• Opaque & Specular substrate
1
T
=
1
Tcal
-
l
c2
ln
s
scal
R 1
• Temperature equation
• Thermal signal
s = C0 eEb = C0 e
c1
l5
exp -
c2
lT
æ
è
ç
ö
ø
÷
r
A
r

s
Filter
Detector
0C : System constant
cal: Calibration parameter

15. PD
PC
DAQ
NBF(switch)
Lens
Lens
BS
LD
Lock-in
Amplifier
Wafer
View port
Vacuum
Chamber
FG
System configuration(Temperature & Growth rate)
Lens
Lens
BS
NBF
Wafer
LD
LD
Lens
PD
NBF
BS
Wafer
PD
Measurement system schematic diagram and optical configuration
400 nm
635 nm
940 nm

16. 翹曲量測
• 提出一套創新的晶圓翹曲量測技術
• 此套技術以疊紋理論、閃頻技術等進行高速旋轉下
晶圓翹曲量測
與台灣科技大學機械系謝宏麟教授團隊共同合作逐點掃描式量測系統
閃頻式量測系統

17. EXPERIMENTS & RESULTS

18. Air film simulation
• 以空氣膜實驗來模擬薄膜沉積，並驗
證系統量測能力
• 以位移台去推動楔形稜鏡來模擬薄膜
生長之情形
時間範圍
(秒)
折射率 折射率
差量
(%)
空氣膜
成長速率
(nm/s)
位移平台
移動速率
(nm/s)
成長速率
差量
(%)
0-30 1.0042 0.39 26.06 26.18 -0.46
30-60 1.0041 0.39 26.37 26.29 0.30
60-90 1.0045 0.40 59.08 59.32 0.40
90-120 1.0044 0.40 59.10 59.01 0.15
120-150 1.0039 0.39 83.21 83.70 -0.58
150-180 1.0040 0.39 83.25 83.62 -0.42空氣膜實驗架構圖

19. ZnO thin film deposition
Index of refraction Thin film thickness (mm)
Reference Measured Reference Measured
1.998 1.96 0.2727 0.272*
Relative difference: 2% Relative difference: 0.3%
Table. 1 Measurement results of the ZnO thin film
Measured thickness = Growth rate × depositing time
= 0.1515 Å /s × 5 hr
• The ZnO thin film deposit on the silicon wafer
• Monitor the growth rate, refractive index, thickness of ZnO
ZnO deposit on the wafer by radio-frequency
sputter
Reflectance Curve of ZnO film

20. Wafer temperature measurement
CP 400 nm 940 nm
(a). (b). (b)-(a) (c). (c)-(a)
455.4 450.5 -4.9 456.5 1.1
542.1 540.4 -2.3 541.3 -0.8
615.5 615.1 -0.4 615.7 0.2
701.7 702.0 0.3 701.8 0.1
781.6 780.8 -0.8 781.2 -0.4
858.5 858.6 0.1 858.6 0.1
943.0 943.2 0.2 943.1 0.1
Table. 2 The Measurement results and compare with
commercial pyrometer, (a) measured by commercial pyrometer,
CP, (b) by 400 nm NBF, and (c) by 940 nm NBF. (unit: °C).
Measurement system set on the heating chamber
600 650 700 750 800 850 900 950 1000
-3
-2
-1
0
1
2
3
Time(s)
Temperature(℃)
System resolution：0.67 ℃ at 580 ℃
• Heating single silicon wafer by the heating
vacuum chamber
• Monitor the wafer surface temperature and
analysis the system resolution

21. 高速旋轉下晶圓溫度量測
0 0.06 0.12 0.18 0.24 0.3 0.36 0.42 0.48 0.54 0.6
500
520
540
560
580
600
620
640
660
Time(s)
Temperature(?)
PMT-200rpm
轉速/
光偵測器
200rpm 400rpm 800rpm
PDA 0.42℃ 0.46℃ 0.56℃
APD -0.58℃ -1℃ 0.48℃
PMT -0.24℃ -0.56℃ 0.2℃
與靜止時量測矽晶圓溫度(550.1℃)差量 於200rpm下資料擷取圖形
晶圓
載盤
• 因製程需求，晶圓在製程時需要以旋轉來達
到良好的薄膜均勻性
• 將一矽晶圓放置於加熱腔體，待加熱穩定後，
進行不同轉速的驗證系統
• 接收940 nm波段熱輻射來進行量測
• 400 nm波段之熱輻射訊號太弱，再進行旋轉
量測時無法解析

22. 膜厚/溫度量測系統整合
成長速率
(nm/s)
未發射率補
償之
直流項溫度
(℃)
具發射率補
償之
直流項溫度
(℃)
差量
(℃)
13.11 602.35 600.15 2.2
29.71 602.25 600.15 2.1
• 膜厚量測所得反射率，經由克希荷夫定律推得其
發射率，藉由此發射率來校正溫度量測結果。
整合系統量測架構圖
溫度歷時曲線與補償前後差量結果

23. 驗證傾斜角度晶圓翹曲量測能力
• 驗證本量測系統具備全域式傾斜角
度量測能力
量測結果：

24. 藍寶石晶圓翹曲量測
• 量測藍寶石晶圓翹曲與表面輪廓重
建
量測
位置
10mm
高度值
(μm)
15mm
高度值
(μm)
20mm
高度值
(μm)
25mm
高度值
(μm)
30mm
高度值
(μm)
35mm
高度值
(μm)
1(黑) 3.67 6.28 8.30 8.21 6.13 3.28
2(紅) 5.21 8.01 9.84 9.75 7.52 4.48
3(藍) 7.04 9.94 12.11 11.42 9.31 6.29
4(粉) 5.58 8.74 11.42 10.61 8.03 4.74
5(綠) 4.45 7.64 9.32 8.82 6.34 3.12
pitch:100 μm

25. 於高速旋轉下晶圓翹曲量測
• 放置一藍寶石晶圓於旋轉平台上進行旋轉
• 分別進行700 rpm、1100 rpm、1500 rpm轉速下的晶
圓翹曲量測
700rpm 1100rpm 1500rpm

26. Conclusion
• An in-situ monitoring system for MOCVD process
• Performance(compared with commercial pyrometer)
Thin film parameters measurement
» Relative difference of refractive index < 2%
» Relative difference of thickness < 0.3%
Temperature measurement
» Relative difference is less than 1%
» Measurement limit：above 450 ℃
Wafer curvature measurement
» Relative difference is about 1%

27. Conclusion
• Future works
Improve dynamic measurement
Modular & Compatible
High quality hardware
- Cooling system
- Low noise

28. Thank you for your listening
Acknowledge: This research was supported by the
Ministry of Science and Technology, Taiwan
(MOST 104-2218-E-008-002)