Winterthur 2008 Presentation [Compatibility Mode]

Winterthur - May 8, 2008


� The Accuflo® series of products from Honeywell are based on an organic polymer system designed to provide• Superior gap fill capability upon spin/bake deposition• Superior flow / planarization properties during thermal cure

� The product family has evolved:• T-13 First Generation for sacrificial etch back planarization

• T-25 • T-27

• T-31

Next Gen for ultra deep feature fill and masking• Improved planarization for T-27

Third Gen for optical applications• Low temp cure, high clarity

• Allowed use of CMP only where necessary

Background

2


Topics� Material Background (Accuflo T27 and T31)� Applications and Objectives� Film Deposition

• Coat/Bake Process� Film Properties

• Film and Gap-fill / Planarization• Crosslinking

� Crosslinking temperature� Mw as a function of bake temperature

• Thermal Stability� Up to 300°C – single cycle� Up to 220 and 300°C – 2 cycles

• Optical Properties � n and k vs. bake temperature and ambient� Transmittance vs. bake temperature and ambient

• Mechanical Properties• Formulation stability

� Summary

3


� 100% organic polymer with properties specifically designed to provide excellent feature fill and planarization.

� Film thickness - from 1,000 Å to 3.5 µm

� Shelf life: 1 year at room temperature

� Baked film is easily removed using a standard O2 plasma etch or ash, or H2SO4 + H2O2 (piranha) strip.

� Polymer melt temperature ~ 160 °C (non crosslinked polymer only). Once the polymer crosslinks (T ≥ 200 °C) the melt temperature increases.

� Modulus = 8.6 GPa, Hardness = 0.49 GPa (2 µm thick film baked at 160/200/200°C),

� AccufloT27 provides limited solvent resistance beginning at 210°C. Complete solvent resistance ≥ 230 °C (120 sec bake)

� AccufloT27 offers absorption at 193 nm and 248 nm enabling its use as the planarizing and absorbing layer for a trilayer resist process

Introduction to Accuflo-T27

4


Sacrificial planarization

• Accuflo T27 is used for planarization enhancement in currently manufactured devices employing Al metallization.

• The use of Accuflo T-27 provided a significant enhancement of DOF for litho at M3 from 0.4 to 1.2 µm DOF (Forester et al, VMIC 1994)

• The planarization capabilities were comparable to that obtained using CMP processes 5


8000

8400

8800

9200

9600

10000

180 190 200 210 220 230 240

Second Bake Temperature, °C

Etc

h R

ate,

Å/m

in

90 s bake 120 s bake

Dry etch rate for Accuflo T27

• Plasma etch: TEL DRM etcher Unity 2

• O2 400 sccm, 150 mTorr, RF 400 mW, Gap 37 mm

• High etch rate allows for high throughput device ma nufacturing 6


• Accuflo T27 permits selective removal of dopants in DRAM manufacturing schemes

• Outstanding planarization capabilities permit filling of high aspect ratio trenches for memory applications (up to 70:1 aspect ratio) with a material which is stable at room temperature.

DRAM Process Review

7

Winterthur - May 8, 2008SEM photo used with permission

Planarization and partial etchback

• Void free fill of 8 µm deep trenches for DRAM

• Selective removal of dopants by partial etchback of Accuflo T27

8


Introduction to Accuflo-T31

� Builds off existing Honeywell Accuflo technology

� Crosslinks at low temperature

� Offers improved optical clarity and transparency in the visible portion of the spectrum.

� Entirely organic polymer film

� Minimum film cure temperature ~ 130°C• Facilitates multi-coat processing to achieve very thick films without thermal

degradation & loss of optical clarity in the visible region

� Thermally stable to temperatures of ~275°C

� Excellent gap fill and planarization

� Wide film thickness range (300Å to 5 µm) in a single coating or multiple coatings with intermediate bakes for thick films.

� Good adhesion to adjacent films

� Optical properties (n & k) can be tuned for applications in the areas of displays, light projection & coupling, and multilayer resist patterning

9


Single step bake (60 – 90 s per plate)

Minimum bake temperature = 140°C (film crosslinked at ~ 130°C)

Maximum bake temperature* = 300°C (thermal degradation of film begins at ~ 275°C )

Two step bake (60 – 90 s per plate)

Bake 1 = 80°C

Bake 2 = 140 - 300°C *

• Final bake temperature of Accuflo T31 should equal or exceed that of any subsequent processing steps

Bake Ambient

Nitrogen - preferred (preserves transparency in the visible spectrum at bake T > 225°C )

Dry Air – only at low bake T < 225°C due to loss of transparency

Coat and bake process

10


• Outstanding solvent resistance even at 140°C bake

• Minimum film bake temperature to support the coated film is ~ 130°C

Crosslinking Temperature Characterization

Bake Temp (°C) for 60 s

Film Thickness after coat/bake

Film Thickness after PGMEA

(attempted strip)Film Thickness

Average Std. dev Average Std. dev Loss, Å % Retention

140 2794.2 11.5 2773.7 3.8 20.4 99.3

160 2760.9 5.1 2747.8 2.3 13.1 99.5

180 2738.0 7.5 2715.6 6.2 22.4 99.2

200 2729.1 5.5 2707.6 10.1 21.5 99.2

(Film remains on substrate)

11


• Excellent solvent resistance (no film loss or inter mixing)

• No interface observed between the two coats of Accu flo-T31

• Ultimate film thickness limitation of multiple coat ings not yet established

• Opens possibility of bonding surfaces together (3D packaging)

Coat/Bake Process:(1st coating) SS 1500 rpmBake 140°C/60 s

(2nd coating) SS 1500 rpmBake 140°C/60 s

Final bake: 200°C/ 60 s

Multiple coating

12


• Regime where film is removed (dissolved by solvent) from substrate• Low molecular weight material permits facile reflow• Observe a rapid onset of Mw increase with temperature• At T ≥105°C – film not fully soluble in THF after coat/bak e sequence• Activation energy is 24.3 kcal/mol• To enhance planarization, a dual bake can be used in which the initial low temperature

bake (80-90°C) maximizes reflow prior to cure• Applications: Flexible display substrate planarization/HART for DRAM

• Increase in Mw begins at ~ 80°C and is complete by ~ 120°C

Mw as a function of Bake Temperature

0

5000

10000

15000

20000

20 40 60 80 100 120

Bake Temperature (°C/ 60s)

Mw

4x

3x

2x

1xln(Mw) = -12233(1/T) + 42.259

R2 = 0.9689

0

2

4

6

8

10

12

0.00265 0.0027 0.00275 0.0028 0.00285

1/T(K)

Ln

Mw

12x10x8x6x4x2x

0

5000

10000

15000

20000

20 40 60 80 100 120

Bake Temperature (°C/ 60s)

Mw

4x

3x

2x

1xln(Mw) = -12233(1/T) + 42.259

R2 = 0.9689

0

2

4

6

8

10

12

0.00265 0.0027 0.00275 0.0028 0.00285

1/T(K)

Ln

Mw

12x10x8x6x4x2x

ln(Mw) = -12233(1/T) + 42.259

R2 = 0.9689

0

2

4

6

8

10

12

0.00265 0.0027 0.00275 0.0028 0.00285

1/T(K)

Ln

Mw

12x10x8x6x4x2x

13


Excellent planarization of the via array topography

Gap fill / Planarization

14


Weight loss vs. temperature shows two distinct regi ons:

• Weight loss due to PGMEA solvent evaporation and cr osslinking chemistry

• Weight loss due to volatilization and some thermal decomposition of polymer

Film coated/baked 3 x (60°C/120 s) to prevent chemi cal reaction/mechanically removed

TGA method: purge nitrogen at 25°C for 20min, ramp to 300°C at 10°C/min

Thermal stability up to 300˚C

33.83°C

0.32% Wt. loss @25C + 34-190C

12.28% Wt. loss @34-190C

250.35°C

190.03°C

0.57% Wt. loss @190-250C

2.55% Wt. loss @250-300C

0

50

100

150

200

250

300

Tem

pera

ture

(°C

)

80

85

90

95

100

Wei

ght (

%)

0 10 20 30 40 50Time (min) Universal V4.2E TA Instruments

Wt. loss due to solvent loss & cross-linking process

Wt. loss due to thermal decomposition of polymer

33.83°C

0.32% Wt. loss @25C + 34-190C

12.28% Wt. loss @34-190C

250.35°C

190.03°C

0.57% Wt. loss @190-250C

2.55% Wt. loss @250-300C

0

50

100

150

200

250

300

Tem

pera

ture

(°C

)

80

85

90

95

100

Wei

ght (

%)

0 10 20 30 40 50Time (min) Universal V4.2E TA Instruments


Wt. loss due to thermal decomposition of polymer

Temperature (˚C)

Weight loss (%)

34-190 12.28

190-250 0.57

250-300 2.55

15


• Very low weight loss during the second thermal cycl e

• Low outgassing is critical for any subsequent overc oat material to prevent adhesion failure (application: trilayer resist)

TGA method: purge nitrogen at 25°C for 20min, ramp to 220°C at 5°C/min, hold 5min at 220°C, ramp to 25°C at 40°C/min, ramp to 220°C at 5 °C/min, hold 5min at 220°C.

Thermal stability up to 220˚C; 2 cycles

0.35% Wt. loss 20min at 25C + 25-30C

30.60°C

12.31% Wt. loss @ 30-220C+5min @ 220C

61.66°C

206.17°C

0.01% Wt. loss @ 220-62C+@ 62-206C0.10% Wt. loss @ 206-220C+5min @220C

0

50

100

150

200

250

Tem

pera

ture

(°C

)

86

88

90

92

94

96

98

100

Wei

ght (

%)

0 20 40 60 80 100 120Time (min) Universal V4.2E TA Instruments


0.35% Wt. loss 20min at 25C + 25-30C

30.60°C

12.31% Wt. loss @ 30-220C+5min @ 220C

61.66°C

206.17°C

0.01% Wt. loss @ 220-62C+@ 62-206C0.10% Wt. loss @ 206-220C+5min @220C

0

50

100

150

200

250

Tem

pera

ture

(°C

)

86

88

90

92

94

96

98

100

Wei

ght (

%)

0 20 40 60 80 100 120Time (min) Universal V4.2E TA Instruments


Temperature (˚C)Weight loss (%)

30-220 + 5min at 220 12.31

220-62 (cooling) + 62-206 (heating)

0.01

206-220 + 5min at 220 0.1

16


Very low weight loss during the second thermal cycl e

TGA method: purge nitrogen at 25 °C for 20min, ramp to 300 °C at 5°C/min, hold 15min at 300°C, ramp to 25 °C at 40°C/min, ramp to 300 °C at 5°C/min, hold 15min at 300 °C.

Thermal stability up to 300˚C; 2 cycles

Temperature (˚C)Weight loss

(%)

25-200 13.72

200-250 0.61

250-300 + 15min at 300

0.1

300-68 + 68-300 0.06

15min at 300 0.21

17


• 2R fitting done to determine accurate values of n a nd k

• Absorbs in the UV spectrum & transparent in the vis ible spectrum

• At bake temperatures ≥≥≥≥ 250ºC absorption starts to occur in visible region

150°C 200°C

n vs. λ

k vs. λ

n vs. λ

k vs. λ

300°C250°C

n vs. λ n vs. λ

k vs. λ k vs. λ

Optical properties – n & k vs. bake temperature in air

18


• Accuflo-T31 demonstrates a marked improvement in tr ansmittance relative to T27

• Greater than 90% transparency across visible spectr um for T31

Optical properties – Transmittance vs. bake temperat ure

Temperature (300°C/N2)

% T

200nm 300nm 400nm 500nm 800nm 900nm

Accuflo T27 87.172 61.852 79.456 86.826 99.709 98.95

Accuflo T31 80.655 72.282 93.729 94.775 99.493 98.772

19


• Baking above 250°C decreases transmittance

• >90% Transmittance across visible spectrum

Optical Properties – Transmittance vs. Bake Temperature

Temperature% T

200nm 300nm 400nm 500nm 800nm 900nm

200 74.375 85.202 95.902 96.224 99.802 99.101

250 79.939 85.603 96.909 96.27 99.668 98.948

300 80.655 72.282 93.729 94.775 99.493 98.772

20


• Use of a low temperature process ( ≤200°C) permits preservation of optical clarity even when processed in air

Optical Properties – Transmittance vs. Bake Temperature

Temperature (°C)

% T

200nm 300nm 400nm 500nm 800nm 900nm

200 89.878 85.411 95.657 95.965 99.727 99.001

250 92.795 57.127 72.063 89.926 99.407 98.543

300 62.969 35.152 63.188 86.308 99.849 99.083

21


Enhanced optical transparency and next Gen material s

Accuflo-T31160ºC bake providessolvent resistance

Next generation Accuflo material After 160/170°C 60 s/60 s; After 250ºC/ 60 min air

• Use of lower temperature bakes for Accuflo T-31 increases the transmittance and extends the optical clarity to lower wavelengths

Next Gen Accuflo material provides:• Solvent resistance• >95% transparency from 300-900 nm• High transparency when cured in air(250°C/60 min)

22


• Film modulus and hardness are invariant across bake temperatures

• No loss of mechanical properties associated with in corporation of low temperature curing capability

Mechanical Properties

60 s bake / 2 µm filmBake temperature (˚C)

E (GPa)E std. dev.

(GPa)H (GPa)

H std. dev (GPa)

150 7.776 0.229 0.498 0.023

150 7.977 0.176 0.561 0.019

250 7.626 0.157 0.533 0.014

250 7.595 0.133 0.523 0.013

23


• Formulation characterized at four storage temperatu res (-20°(not shown), 4°, 21°and 40°C)

• Material is quite stable at 4°C (refrigerated stora ge) and plans in place to extend stability to room temperature

Formulation Stability

1200

5200

9200

13200

0 25 50 75 100Days

Mw

Aging at 40°CAging at 21°CAging at 4°C

12X

8X

4X

X

24


Thank You

� Accuflo-T31 builds off the existing Honeywell Accuflo technology in that Accuflo-T31 can be crosslinked at much lower temperatures.

� Lower temperature applications for Accuflo-T31 identified in the areas of tri-layer resist patterning, display and other light coupling applications

� Accuflo-T31 offers improved optical transparency in the visible region as compared to existing Accuflo technology

� Applicable to both sacrificial and permanent film uses

Summary

Documents

Winterthur 2008 Presentation [Compatibility Mode]