Abstract

Temperature sensitivity of Si based rings can be nullified by the use of polymer over-cladding. Integration of athermal passive rings in an electronic-photonic architecture requires the possibility of multi-layer depositions with patterned structures. This requires establishing UV, thermal and plasma stability of the polymer during multi-layer stacking. UV stability is enhanced by UV curing to saturation levels. However, thermal stability is limited by the decomposition temperature of the polymer. Further, robust performance in oxidizing atmosphere and plasma exposure requires a SiO2/SiNx based dielectric coatings on the polymer. This communication uses a low temperature (130°C) High Density Plasma Chemical Vapor Deposition (HDPCVD) for dielectric encapsulation of polymer cladded Si rings to make them suitable for device layer deposition. UV induced cross-linking and annealing under vacuum make polymer robust and stable for Electron Cyclotron Resonance (ECR)-PECVD deposition of 500nm SiO2/SiNx. The thermo-optic (TO) properties of the polymer cladded athermal rings do not change after dielectric cap deposition opening up possibilities of device deposition on top of the passive athermal rings. Back-end CMOS compatibility requires polymer materials with high decomposition temperature (> 400°C) that have low TO coefficients. This encourages the use of SiNx core waveguides in the back-end architecture for athermal applications.

© 2012 OSA

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References

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2011 (1)

G. Coppola, L. Sirleto, I. Rendina, and M. Iodice, “Advance in thermo-optical switches: principles, materials, design and device structure,” Opt. Eng.50(7), 071112 (2011).
[CrossRef]

2010 (1)

2009 (1)

2008 (2)

J.-M. Lee, D.-J. Kim, G.-H. Kim, O.-K. Kwon, K.-J. Kim, and G. Kim, “Controlling temperature dependence of silicon waveguides using slot structure,” Opt. Express16(3), 1645–1652 (2008).
[CrossRef]

W. N. Ye, J. Michel, and L. C. Kimerling, “Athermal high-index-contrast waveguide design,” IEEE Photon. Technol. Lett.20(11), 882–884 (2008).
[CrossRef]

2007 (1)

2002 (1)

H. Ma, A. K. Y. Jen, and L. R. Dalton, “Polymer-based optical waveguides: materials, processing, and devices,” Adv. Mater. (Deerfield Beach Fla.)14(19), 1339–1365 (2002).
[CrossRef]

2001 (1)

M. Hasegawa and K. Horie, “Photophysics, photochemistry and optical properties of polyimides,” Prog. Polym. Sci.26(2), 259–335 (2001).
[CrossRef]

2000 (1)

L. Eldada and L. W. Shacklette, “Advances in polymer integrated optics,” IEEE J. Sel. Top. Quantum Electron.6(1), 54–68 (2000).
[CrossRef]

1999 (1)

C. Doughty, D. C. Knick, J. B. Bailey, and J. E. Spencer, “Silicon nitride films deposited at substrate temperatures < 100 C in a permanent magnet electron cyclotron resonance plasma,” J. Vac. Sci. Technol. A17(5), 2612–2618 (1999).
[CrossRef]

1995 (1)

K. L. Seaward, J. E. Turner, K. Nauka, and A. M. E. Nel, “Role of ions in electron cyclotron resonance plasma-enhanced chemical vapor deposition of silicon dioxide,” J. Vac. Sci. Technol. B13(1), 118–124 (1995).
[CrossRef]

1983 (1)

S. Matsuo and M. Kiuchi, “Low temperature chemical vapor deposition method utilizing an electron cyclotron resonance plasma,” Jpn. J. Appl. Phys.22(Part 2, No. 4), L210–L212 (1983).
[CrossRef]

Baets, R.

Bailey, J. B.

C. Doughty, D. C. Knick, J. B. Bailey, and J. E. Spencer, “Silicon nitride films deposited at substrate temperatures < 100 C in a permanent magnet electron cyclotron resonance plasma,” J. Vac. Sci. Technol. A17(5), 2612–2618 (1999).
[CrossRef]

Beals, M. A.

Bogaerts, W.

Carothers, D. N.

Chen, Y. K.

Coppola, G.

G. Coppola, L. Sirleto, I. Rendina, and M. Iodice, “Advance in thermo-optical switches: principles, materials, design and device structure,” Opt. Eng.50(7), 071112 (2011).
[CrossRef]

Dalton, L. R.

H. Ma, A. K. Y. Jen, and L. R. Dalton, “Polymer-based optical waveguides: materials, processing, and devices,” Adv. Mater. (Deerfield Beach Fla.)14(19), 1339–1365 (2002).
[CrossRef]

Doughty, C.

C. Doughty, D. C. Knick, J. B. Bailey, and J. E. Spencer, “Silicon nitride films deposited at substrate temperatures < 100 C in a permanent magnet electron cyclotron resonance plasma,” J. Vac. Sci. Technol. A17(5), 2612–2618 (1999).
[CrossRef]

Dumon, P.

Eldada, L.

L. Eldada and L. W. Shacklette, “Advances in polymer integrated optics,” IEEE J. Sel. Top. Quantum Electron.6(1), 54–68 (2000).
[CrossRef]

Gill, D. M.

Grove, M. J.

Han, X.

Hasegawa, M.

M. Hasegawa and K. Horie, “Photophysics, photochemistry and optical properties of polyimides,” Prog. Polym. Sci.26(2), 259–335 (2001).
[CrossRef]

Horie, K.

M. Hasegawa and K. Horie, “Photophysics, photochemistry and optical properties of polyimides,” Prog. Polym. Sci.26(2), 259–335 (2001).
[CrossRef]

Hu, J.

Iodice, M.

G. Coppola, L. Sirleto, I. Rendina, and M. Iodice, “Advance in thermo-optical switches: principles, materials, design and device structure,” Opt. Eng.50(7), 071112 (2011).
[CrossRef]

Izuhara, T.

Jen, A. K. Y.

H. Ma, A. K. Y. Jen, and L. R. Dalton, “Polymer-based optical waveguides: materials, processing, and devices,” Adv. Mater. (Deerfield Beach Fla.)14(19), 1339–1365 (2002).
[CrossRef]

Jian, X.

Kim, D.-J.

Kim, G.

Kim, G.-H.

Kim, K.-J.

Kimerling, L. C.

Kiuchi, M.

S. Matsuo and M. Kiuchi, “Low temperature chemical vapor deposition method utilizing an electron cyclotron resonance plasma,” Jpn. J. Appl. Phys.22(Part 2, No. 4), L210–L212 (1983).
[CrossRef]

Knick, D. C.

C. Doughty, D. C. Knick, J. B. Bailey, and J. E. Spencer, “Silicon nitride films deposited at substrate temperatures < 100 C in a permanent magnet electron cyclotron resonance plasma,” J. Vac. Sci. Technol. A17(5), 2612–2618 (1999).
[CrossRef]

Kwon, O.-K.

Lee, J.-M.

Ma, H.

H. Ma, A. K. Y. Jen, and L. R. Dalton, “Polymer-based optical waveguides: materials, processing, and devices,” Adv. Mater. (Deerfield Beach Fla.)14(19), 1339–1365 (2002).
[CrossRef]

Matsuo, S.

S. Matsuo and M. Kiuchi, “Low temperature chemical vapor deposition method utilizing an electron cyclotron resonance plasma,” Jpn. J. Appl. Phys.22(Part 2, No. 4), L210–L212 (1983).
[CrossRef]

Michel, J.

Morthier, G.

Nauka, K.

K. L. Seaward, J. E. Turner, K. Nauka, and A. M. E. Nel, “Role of ions in electron cyclotron resonance plasma-enhanced chemical vapor deposition of silicon dioxide,” J. Vac. Sci. Technol. B13(1), 118–124 (1995).
[CrossRef]

Nel, A. M. E.

K. L. Seaward, J. E. Turner, K. Nauka, and A. M. E. Nel, “Role of ions in electron cyclotron resonance plasma-enhanced chemical vapor deposition of silicon dioxide,” J. Vac. Sci. Technol. B13(1), 118–124 (1995).
[CrossRef]

Patel, S. S.

Pomerene, A. T. S.

Raghunathan, V.

Rasras, M. S.

Rendina, I.

G. Coppola, L. Sirleto, I. Rendina, and M. Iodice, “Advance in thermo-optical switches: principles, materials, design and device structure,” Opt. Eng.50(7), 071112 (2011).
[CrossRef]

Seaward, K. L.

K. L. Seaward, J. E. Turner, K. Nauka, and A. M. E. Nel, “Role of ions in electron cyclotron resonance plasma-enhanced chemical vapor deposition of silicon dioxide,” J. Vac. Sci. Technol. B13(1), 118–124 (1995).
[CrossRef]

Shacklette, L. W.

L. Eldada and L. W. Shacklette, “Advances in polymer integrated optics,” IEEE J. Sel. Top. Quantum Electron.6(1), 54–68 (2000).
[CrossRef]

Sirleto, L.

G. Coppola, L. Sirleto, I. Rendina, and M. Iodice, “Advance in thermo-optical switches: principles, materials, design and device structure,” Opt. Eng.50(7), 071112 (2011).
[CrossRef]

Sparacin, D. K.

Spencer, J. E.

C. Doughty, D. C. Knick, J. B. Bailey, and J. E. Spencer, “Silicon nitride films deposited at substrate temperatures < 100 C in a permanent magnet electron cyclotron resonance plasma,” J. Vac. Sci. Technol. A17(5), 2612–2618 (1999).
[CrossRef]

Teng, J.

Tu, K. Y.

Turner, J. E.

K. L. Seaward, J. E. Turner, K. Nauka, and A. M. E. Nel, “Role of ions in electron cyclotron resonance plasma-enhanced chemical vapor deposition of silicon dioxide,” J. Vac. Sci. Technol. B13(1), 118–124 (1995).
[CrossRef]

White, A. E.

Ye, W. N.

Zhang, H.

Zhao, M.

Adv. Mater. (Deerfield Beach Fla.) (1)

H. Ma, A. K. Y. Jen, and L. R. Dalton, “Polymer-based optical waveguides: materials, processing, and devices,” Adv. Mater. (Deerfield Beach Fla.)14(19), 1339–1365 (2002).
[CrossRef]

IEEE J. Sel. Top. Quantum Electron. (1)

L. Eldada and L. W. Shacklette, “Advances in polymer integrated optics,” IEEE J. Sel. Top. Quantum Electron.6(1), 54–68 (2000).
[CrossRef]

IEEE Photon. Technol. Lett. (1)

W. N. Ye, J. Michel, and L. C. Kimerling, “Athermal high-index-contrast waveguide design,” IEEE Photon. Technol. Lett.20(11), 882–884 (2008).
[CrossRef]

J. Lightwave Technol. (1)

J. Vac. Sci. Technol. A (1)

C. Doughty, D. C. Knick, J. B. Bailey, and J. E. Spencer, “Silicon nitride films deposited at substrate temperatures < 100 C in a permanent magnet electron cyclotron resonance plasma,” J. Vac. Sci. Technol. A17(5), 2612–2618 (1999).
[CrossRef]

J. Vac. Sci. Technol. B (1)

K. L. Seaward, J. E. Turner, K. Nauka, and A. M. E. Nel, “Role of ions in electron cyclotron resonance plasma-enhanced chemical vapor deposition of silicon dioxide,” J. Vac. Sci. Technol. B13(1), 118–124 (1995).
[CrossRef]

Jpn. J. Appl. Phys. (1)

S. Matsuo and M. Kiuchi, “Low temperature chemical vapor deposition method utilizing an electron cyclotron resonance plasma,” Jpn. J. Appl. Phys.22(Part 2, No. 4), L210–L212 (1983).
[CrossRef]

Opt. Eng. (1)

G. Coppola, L. Sirleto, I. Rendina, and M. Iodice, “Advance in thermo-optical switches: principles, materials, design and device structure,” Opt. Eng.50(7), 071112 (2011).
[CrossRef]

Opt. Express (3)

Prog. Polym. Sci. (1)

M. Hasegawa and K. Horie, “Photophysics, photochemistry and optical properties of polyimides,” Prog. Polym. Sci.26(2), 259–335 (2001).
[CrossRef]

Other (3)

International Technology Roadmap for Semiconductors, “Interconnect,” (ITRS, 2009). http://www.itrs.net/Links/2009ITRS/2009Chapters_2009Tables/2009_Interconnect.pdf

M. Georgas, J. Leu, B. Moss, C. Sun, and V. Stojanovic, “Addressing link-level design tradeoffs for integrated photonic interconnects,” in Custom Integrated Circuits Conference (Institute of Electrical and Electronics Engineers, 2011), 978–1-4577–0233–5/11.

V. Raghunathan, J. Hu, W. N. Ye, and J. Michel, and L. C. Kimerling, “Athermal silicon ring resonators,” in Conference on Integrated Photonic Research, Silicon and Nanophotonics, Technical Digest (CD) (Optical Society of America, 2010), paperIMC5.

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Figures (6)

Fig. 1
Fig. 1

(a)Top view of the unclad a-Si resonator shows the racetrack configuration that is used for TO measurements. (b) Cross-sectional SEM of the device shows 509nm × 209nm a-Si core with 2.75μm SiO2 under-cladding and 2.87μm EP polymer over-clad. The design rule involves expanding the TM mode into the polymer cladding, thereby, negating the positive TO effects from the core.

Fig. 2
Fig. 2

Experimental data suggests that UV exposure has minimal effect on the TO response of an athermal ring. Curing of spun-on polymer by exposing it to a 5mW/cm2 UV radiation for 20 minutes creates enough cross-linking and structural reorganization within polymer thereby making it stable to any further UV exposure (λ: 365-405nm, Dose: 9.5mJ/cm2). Variation of experimental TO values around the linear fit is within the expected limits ( ± 5pm/K) arising from thickness non-uniformity ( ± 6nm) during a-Si deposition.

Fig. 3
Fig. 3

TGA measurement of the polymer sample in N2 atmosphere reveals weight loss above350°C at a heating rate of 10°C/min. Multi-layer depositions on polymer film needs to be carried out at temperatures less than 300°C to prevent any weight loss resulting in polymer degradation.

Fig. 4
Fig. 4

(a) SEM image of the plasma exposed athermal device confirms the etching of polymer top cladding. (b) TO performance of the ring exposed to Argon plasma reveals increased TDWS values (around 40 pm/K) due to the absence of polymer.

Fig. 5
Fig. 5

(a) SEM confirms the successful deposition of dielectrics on the polymer cladding. Cross-sectional SEM of 505nm × 209nm a-Si with 3μm SiO2 under-clad, 2.47μm EP polymer over-clad encapsulated with a 488nm SiNx. (b) Cross-sectional SEM of 509nm × 209nm a-Si with 3μm SiO2 under-clad, 2.29μm EP polymer over-clad encapsulated with a 526nm SiO2 cap.

Fig. 6
Fig. 6

The TDWS response doesn’t change significantly after the dielectric (SiO2/SiNx) deposition on the polymer. The scatter in experimental TDWS values are within the expected variation ( ± 5pm/K) due to 3% thickness non-uniformity during the deposition of 205nm thick a-Si film.

Tables (2)

Tables Icon

Table 1 HDPCVD Conditions for SiO2 and SiNx on the Polymer Cladded Devices

Tables Icon

Table 2 Polymer Cladding Choices for a Given core for Athermal Application. SiNx core having a low TO coefficient can be compensated with a low TO coefficient polymer. Such polymers have a high decomposition temperature and hence are compatible with back-end CMOS processes.

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