equation (5.21) – dnq exposure mechanism
DESCRIPTION
Figure 5.1 Resist parameters A and B as a function of wavelength measured with a UV spectrophotometer for a typical g-line resist (a 5-arylsulfonate DNQ). . Equation (5.21) – DNQ exposure mechanism. (a). (b). - PowerPoint PPT PresentationTRANSCRIPT
Chris A. Mack, Fundamental Principles of Optical Lithography, (c) 2007
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Wavelength (nm)
0.0
0.3
0.6
0.9
1.2
1.5
300 340 380 420 460 500
A
B
Res
ist A
and
B (1
/m
)
Figure 5.1 Resist parameters A and B as a function of wavelength measured with a UV spectrophotometer for a typical g-line resist (a 5-arylsulfonate DNQ).
Chris A. Mack, Fundamental Principles of Optical Lithography, (c) 2007
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SO2 R
UV
O N2
SO2 R
C=O
+ N2 H2O
SO2 R
COOH
Equation (5.21) – DNQ exposure mechanism
Chris A. Mack, Fundamental Principles of Optical Lithography, (c) 2007
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-500 -300 -100 100 300 500 0.0
0.3
0.6
0.9
1.2
1.5
Aer
ial I
mag
e In
tens
ity
Horizontal Position (nm)
-500 -300 -100 100 300 500 0.0
0.2
0.4
0.6
0.8
1.0
Rel
ativ
e P
AC
Con
cent
ratio
n
Horizontal Position (nm)
(a) (b)
Figure 5.2 The exposure process takes an aerial image (a) and converts it into a latent image (b).
Chris A. Mack, Fundamental Principles of Optical Lithography, (c) 2007
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SO2 R
O N2
SO2 R
C=O
+ N2 X
Equation (5.36) – Thermal decomposition of DNQ
Chris A. Mack, Fundamental Principles of Optical Lithography, (c) 2007
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SO2 R
C=O
+ H2O
SO2 R
COOH
SO2 R
C=O
SO2 R
CO
Resin O
CH3
OH
CH3
OH
CH3
Equations (5.46) and (5.47) – DNQ thermal decomposition products
Chris A. Mack, Fundamental Principles of Optical Lithography, (c) 2007
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0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 20 40 60 80 100 120
Bake Time (min)
80 ºC 95 ºC 110 ºC 125 ºC
A (1
/m
)
-4.5
-4.0
-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
0
Bake Time (min)
Ln(A
/AN
B)
15 30 45 60 75 90
(a) (b)
Figure 5.3 The variation of the resist absorption parameter A with post-apply bake time and temperature for Kodak 820 resist at 365 nm (a convection oven bake was used): a) linear plot, and b) logarithmic plot.
Chris A. Mack, Fundamental Principles of Optical Lithography, (c) 2007
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0.00
0.02
0.04
0.06
0.08
0.10
0.12
0 100 200 300 400 500
Depth into Resist (nm)
Sol
vent
Mas
s Fa
ctio
n 90 ºC
100 ºC
110 ºC
Figure 5.4 Predicted variation of solvent concentration as a function of depth into the resist at the end of a 60 s post-apply bake.
Chris A. Mack, Fundamental Principles of Optical Lithography, (c) 2007
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6
7
8
9
10
11
12
13
14
15
0.00245 0.0025 0.00255 0.0026 0.00265 0.0027
1/Absolute Temperature (K)
ln(D
iffus
ivity
)
s = 0.05
s = 0.10
Tg
Figure 5.5 Temperature dependence of solvent diffusivity (using the parameters from Table 5.1 and assuming a solvent mass fractions of 0.05 and 0.1) showing an essentially fixed diffusivity below the glass transition temperature.
Chris A. Mack, Fundamental Principles of Optical Lithography, (c) 2007
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Figure 5.6 Lower solvent content at the top of this 248 nm resist leads to reduced acid diffusion during PEB, and thus the presence of standing waves only at the top of the resist (photo courtesy of John Petersen, used with permission).
Chris A. Mack, Fundamental Principles of Optical Lithography, (c) 2007
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(a) (b) (c)
Figure 5.7 Typical i-line photoresist profile simulations (using PROLITH) for resist on silicon as a function of the PEB diffusion length: (a) 20nm, (b) 40nm, and (c) 60nm.
Chris A. Mack, Fundamental Principles of Optical Lithography, (c) 2007
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0
20
40
60
80
100
0 20 40 60 80 100 Time (sec)
Res
ist T
empe
ratu
re (º
C)
Hotplate Chill plate Xfer
Figure 5.8 Typical wafer bake profile (60 s bake followed by a 10 s transfer to a chill plate).
Chris A. Mack, Fundamental Principles of Optical Lithography, (c) 2007
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High Thermal Mass Hotplate High Thermal Mass Hotplate
Wafer
Figure 5.9 Proximity bake of a wafer on a hot plate showing (in a highly exaggerated way) how wafer warpage leads to a variation in proximity gap (drawing not to scale).
Chris A. Mack, Fundamental Principles of Optical Lithography, (c) 2007
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UP
Light Source
Collimating Lens
Bandpass Filter
Resist Coated Glass Substrate
Light Meter
A/D
Figure 5.10. Experimental configuration for the measurement of the ABC parameters.
Chris A. Mack, Fundamental Principles of Optical Lithography, (c) 2007
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0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 200 400 600 800 1000
Exposure Dose (mJ/cm2)
Tran
smitt
ance
Figure 5.11. Typical transmittance curve of a positive g- or i-line bleaching photoresist measured using an apparatus similar to that pictured in Figure 5.10.
Chris A. Mack, Fundamental Principles of Optical Lithography, (c) 2007
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0.0
0.2
0.4
0.6
0.8
1.0
0 100 200 300 400 Exposure Dose (mJ/cm2)
Tran
smitt
ance
80 ºC
125 ºC
Figure 5.12. Two transmittance curves for Kodak 820 resist at 365 nm. The curves are for a convection oven post-apply bake of 30 minutes at the temperatures shown.