Intriguing etch resistance evolution in hybrid resists synthesized by vapor phase infiltrationNikhil Tiwale1, Ashwanth Subramanian2, Kim Kisslinger1, Ming Lu1, Jiyoung Kim3, Aaron Stein1, and Chang-Yong Nam1,2

1Center for Functional Nanomaterials, Brookhaven National Laboratory2Department of Materials Science and Chemical Engineering, Stony Brook University3Department of Materials Science and Engineering, University of Texas at Dallas

This research used resources of the Center for Functional Nanomaterials, which is a U.S. DOE Office of Science Facility, at Brookhaven National Laboratory under Contract No. DE-SC0012704.

1. High Resolution Resist challenge: Pattern transfer

▪Hard to combine high-resolution and high-aspect ratio pattern transfer

▪Alternative: Adding inorganics to resists

▪Higher mechanical strength:Avoids pattern collapse

▪Enhanced etch resistance:High-aspect ratio pattern transfer even at small resist thickness

2. Infiltration synthesis of hybrids using ALD system

3. Physical vs. chemical etch resistance of hybrid resist

6. CFN Facilities Used

7. Acknowledgements

5. High aspect ratio pattern transfer using cryogenic Si etch

Li et al., Chem. Soc. Rev. 46, 4855 (2017)

X

X

Higher ResolutionHigh aspect ratio

Pattern collapseThinner Resist

Low aspect ratio pattern transfer

Improved patterningHigh Etch resistance

resist

Improved pattern transfer

Subramanian, Tiwale, Nam, JOM 71, 185 (2019)

▪Infiltration synthesis

▪Derived from ALD; relies on permeation of gas species in polymers

▪Inorganic precursor infiltrates into the matrix of polymer resists, creating hybrid resists

Infiltration Synthesis

Etch process dependence Process

Temp.(°C)

Pressure(mTorr)

RF Power(W)

ICP Power(W)

Gas flow rate(sccm)

O2 Etch(chemical etch)

20 30 200 0 O2: 50

SiO2 Etch(Physical etch)

25 15 40 700O2: 1.5

CHF3: 50

Cryogenic Si Etch(chemical + physical)

-100 15 15 800O2: 12SF6: 40

▪More enhanced chemical etch resistance than physical etch resistance

▪Infiltration enabled by chemical binding of inorganic precursor with polymer

▪Hybridization has made the resist chemically more robust

4. AlOx-infiltrated SU-8: Weak organic-inorganic interaction

MOx infiltration in SU-8 facilitated by residual solvent molecule

Ye, Nam et al., Chem. Mater. 29, 4535 (2017)

Unique ultrahigh elastic energy storage in AlOx-SU-8 hybrid

▪AlOx-SU-8 hybrid: Weak interaction between organic and inorganic networks

▪Nearly similar etch resistance change for both chemical and physical etch processes

ProcessTemp.

(°C)Pressure(mTorr)

RF Power(W)

ICP Power(W)

Gas flow rate(sccm)

CryogenicSi etch

-100 15 15 800O2: 16SF6: 40

Infiltration Selectivity Comment

2-Cycle ~20 More than ZEP

4-Cycle ~70 More than SiO2

8-Cycle ~300

Cryo Si etch rate & selectivity

▪High aspect ratio of ~17, Si nanostructures▪More than 530 nm depth with LW down to ~30 nm

Tiwale, Nam et al., J. Mater. Chem. C 7, 8803 (2019)

Tiwale, Nam et al., Proc. SPIE 11326, Advances in Patterning Materials and Processes XXXVII, 113260J (2020)

▪CFN Materials Synthesis and Characterization: Cambridge NanoTechSavannah 100 Atomic Layer Deposition, March Plasma CS1710F, Hitachi S-4800 SEM, J. A. Woollam M-2000

▪CFN Nanofabrication: JEOL JBX-6300FS Electron Beam Lithography, Oxford Plasmalab 100 ICP-RIE,

▪CFN Proximal Probes: Park NX-20 Atomic Force Microscope

▪NSLS-II Beamline: 21-ID-2 ESM-XPEEM Beamline, 21-ID-1 ESM-ARPES Beamline

Dusoe, Nam et al., Nano Lett. 17, 7416 (2017)

Infiltration synthesis: Precursor diffusion & binding into polymer matrix

ALD: Surface-limited reaction & thin film deposition