Method for Inspection of Phase Defects in Extreme Ultraviolet Lithography Mask

Wei Cheng; Sikun Li; Xiangzhao Wang

doi:10.3788/AOS221209

Acta Optica Sinica, Volume. 43, Issue 1, 0112001(2023)

Method for Inspection of Phase Defects in Extreme Ultraviolet Lithography Mask

Wei Cheng^1,2, Sikun Li^1,2、*, and Xiangzhao Wang^1,2、**

¹Laboratory of Information Optics and Optoelectronic Technology, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China

²Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China

show less

Abstract Get PDF(in Chinese)

Figures & Tables(12)

Fig. 1. Schematic diagram of defective mask blanks. (a) Bump defect; (b) pit defect

Download full size

Fig. 2. Flow chart for inspection of phase defects based on aerial images

Download full size

Fig. 3. Schematic diagram of inspection for defect type and location based on convolutional neural network

Download full size

Fig. 4. Schematic diagram of inspection for defect surface profile parameters based on MLP

Download full size

Fig. 5. Aerial images of defective mask blanks with different defect parameters. (a) Mask A; (b) mask B; (c) mask C; (d) mask D; (e) mask E; (f) mask F

Download full size

Fig. 6. Inspection result of defect type factor

Download full size

Fig. 7. Inspection results of defect position coordinates. (a) x-direction coordinates of bump defects; (b) y-direction coordinates of bump defects; (c) x-direction coordinates of pit defects; (d) y-direction coordinates of pit defects

Download full size

Fig. 8. Inspection results of defect top profile parameters. (a) Surface height of bump defect; (b) surface FWHM of bump defect; (c) surface height of pit defect; (d) surface FWHM of pit defect

Download full size

Table 1. Parameter setting for imaging simulation

View table

Table 1. Parameter setting for imaging simulation

Simulation object	Submodule	Description
Optics	Illumination	Wavelength： 13.5 nm； chief ray angle： 6°； annular source； $σ_{i n} = 0.6$ ； $σ_{o u t} = 0.8$
Optics	Projection	$N A_{o b j}$ =0.0825
Mask	Multilayer	40 pairs of Mo/Si bilayers； Mo thickness： 2.78 nm； Si thickness： 4.17 nm； refractive index of Mo： 0.9238-0.0064j； refractive index of Si： 0.9990-0.0018j
Mask	Substrate	SiO₂ thickness： 30 nm； refractive index of SiO₂： 0.9260 - 0.0436j

Table 2. Parameter setting of different defective masks unit: nm
View table
Table 2. Parameter setting of different defective masks unit: nm
Mask $x_{p o s}$ $y_{p o s}$ $h_{t o p}$ $ω_{t o p}$ $h_{b o t}$ $ω_{b o t}$
Mask A 0 0 2 30 10 20
Mask B 0 0 4 35 15 25
Mask C 40 40 4 35 15 25
Mask D 0 0 -2 30 -10 20
Mask E 0 0 -4 35 -15 25
Mask F 40 40 -4 35 -15 25

Table 3. Absolute error distribution of inspection results of defect surface profile parameters
View table
Table 3. Absolute error distribution of inspection results of defect surface profile parameters
Defect type $h_{t o p}$ $ω_{t o p}$
$M_{A E} \leq 0.10 n m$ $M_{A E} \leq 0.30 n m$ $M_{A E} \leq 0.50 n m$ $M_{A E} \leq 1.00 n m$ $M_{A E} \leq 3.00 n m$ $M_{A E} \leq 5.00 n m$
Bump defect 85.9% 97.7% 99.2% 85.9% 97.7% 100.0%
Pit defect 56.3% 90.6% 98.4% 85.2% 100.0% 100.0%

Table 4. Inspection results for type, location and surface profile parameters of phase defects with and without noise

View table

Table 4. Inspection results for type, location and surface profile parameters of phase defects with and without noise

Defect type	Noise type	SNR /dB	Classification accuracy /%	MAE of $x_{p o s}$ /nm	MAE of $y_{p o s}$ /nm	MAE of $h_{t o p}$ /nm	MAE of $ω_{t o p}$ /nm
Bump defect	Without noise		100	1.06	0.51	0.06	0.55
Bump defect	Gaussian	57.9	100	1.06	0.53	0.09	0.82
Bump defect	Gaussian	52.9	100	1.06	0.55	0.18	1.37
Bump defect	Gaussian	47.9	100	1.20	0.59	0.24	2.07
Bump defect	Poisson	52.9	100	1.07	0.55	0.14	1.42
Pit defect	Without noise		100	1.70	0.97	0.12	0.57
Pit defect	Gaussian	57.9	100	1.71	1.01	0.13	0.64
Pit defect	Gaussian	52.9	100	1.75	1.01	0.18	0.94
Pit defect	Gaussian	47.9	100	1.73	1.20	0.27	1.51
Pit defect	Poisson	52.9	100	1.71	1.07	0.17	0.85

Tools

Get Citation

Copy Citation Text

Wei Cheng, Sikun Li, Xiangzhao Wang. Method for Inspection of Phase Defects in Extreme Ultraviolet Lithography Mask[J]. Acta Optica Sinica, 2023, 43(1): 0112001

Download Citation

EndNote(RIS)BibTex Plain Text

Set citation alerts for article

Save article for my favorites

Paper Information

Category: Instrumentation, Measurement and Metrology

Received: May. 27, 2022

Accepted: Jun. 20, 2022

Published Online: Jan. 6, 2023

The Author Email: Li Sikun (lisikun@siom.ac.cn), Wang Xiangzhao (wxz26267@siom.ac.cn)

DOI:10.3788/AOS221209

Topics

laser devices and laser physics

Lasers and Laser Optics

Laser physics

laser manufacturing

Instrumentation, Measurement and Metrology

Table 1. Parameter setting for imaging simulation

Table 1. Parameter setting for imaging simulation

Table 2. Parameter setting of different defective masks unit: nm

Table 2. Parameter setting of different defective masks unit: nm

Table 3. Absolute error distribution of inspection results of defect surface profile parameters

Table 3. Absolute error distribution of inspection results of defect surface profile parameters

Table 4. Inspection results for type, location and surface profile parameters of phase defects with and without noise

Table 4. Inspection results for type, location and surface profile parameters of phase defects with and without noise