Highly uniform sieving structure by corner lithography and silicon wet etching

B. Schurink, E.J.W. Berenschot, R.M. Tiggelaar, R. Luttge

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10 Citaties (Scopus)

Uittreksel

We describe and demonstrate a fabrication process for silicon sieves with highly-uniform, micron-sized pyramidal shaped pores featuring squared apertures. These sieves are fabricated over areas of several square millimetres by means of double-side standard UV-lithography and wet etching in (1 0 0)-silicon. We intend to use these sieves for hydrodynamic cell capture devices (sieves), suitable for integration of electrodes for electrophysiological measurements of neuronal networks. For the fabrication process, standard plain silicon wafers are used, without the need for etch-stop layers or silicon-on-insulator. To ensure that the sieve contains pores with identical aperture sizes by merely the use of a timed etch-stop, sacrificial octahedral structures are formed underneath each pore by means of corner lithography. These sacrificial structures counteract non-uniformities in the thickness of the layer defining the sieve, resulting from the deep (>500 μm) anisotropic backside wet etch process. For our intended use, we aimed for pyramidal pits with a base length of 20 μm and an aperture at their tips of 3 μm over a circular sieve area with a diameter of 2.4 mm. In order to minimize the non-uniformity in sieve thickness, the deep back-etch is studied by applying KOH and TMAH etchants using variations in temperature of the etchant as well as variations in size and shape of the applied mask opening on the backside of the silicon substrate. With optimal conditions, both etchants can be used to successfully realize sieves. However, the best results are obtained for a back-etch in TMAH (25 wt%, 71 °C) with Triton X (0.1 vol%) as an additive. The later conditions yield a non-uniformity of 0.7 μm for a sieve thickness of 18 μm. Within the sieve area, all 900 square pores, evenly distributed with a 70 μm pitch, have an aperture of 3.2 ± 0.1 μm.

Originele taal-2Engels
Pagina's (van-tot)12-18
Aantal pagina's7
TijdschriftMicroelectronic Engineering
Volume144
DOI's
StatusGepubliceerd - 16 aug 2015

Vingerafdruk

sieves
Sieves
Wet etching
Silicon
Lithography
lithography
etching
silicon
etchants
apertures
nonuniformity
porosity
Fabrication
fabrication
plains
Silicon wafers
Masks
masks
Hydrodynamics
hydrodynamics

Citeer dit

Schurink, B. ; Berenschot, E.J.W. ; Tiggelaar, R.M. ; Luttge, R. / Highly uniform sieving structure by corner lithography and silicon wet etching. In: Microelectronic Engineering. 2015 ; Vol. 144. blz. 12-18.
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abstract = "We describe and demonstrate a fabrication process for silicon sieves with highly-uniform, micron-sized pyramidal shaped pores featuring squared apertures. These sieves are fabricated over areas of several square millimetres by means of double-side standard UV-lithography and wet etching in (1 0 0)-silicon. We intend to use these sieves for hydrodynamic cell capture devices (sieves), suitable for integration of electrodes for electrophysiological measurements of neuronal networks. For the fabrication process, standard plain silicon wafers are used, without the need for etch-stop layers or silicon-on-insulator. To ensure that the sieve contains pores with identical aperture sizes by merely the use of a timed etch-stop, sacrificial octahedral structures are formed underneath each pore by means of corner lithography. These sacrificial structures counteract non-uniformities in the thickness of the layer defining the sieve, resulting from the deep (>500 μm) anisotropic backside wet etch process. For our intended use, we aimed for pyramidal pits with a base length of 20 μm and an aperture at their tips of 3 μm over a circular sieve area with a diameter of 2.4 mm. In order to minimize the non-uniformity in sieve thickness, the deep back-etch is studied by applying KOH and TMAH etchants using variations in temperature of the etchant as well as variations in size and shape of the applied mask opening on the backside of the silicon substrate. With optimal conditions, both etchants can be used to successfully realize sieves. However, the best results are obtained for a back-etch in TMAH (25 wt{\%}, 71 °C) with Triton X (0.1 vol{\%}) as an additive. The later conditions yield a non-uniformity of 0.7 μm for a sieve thickness of 18 μm. Within the sieve area, all 900 square pores, evenly distributed with a 70 μm pitch, have an aperture of 3.2 ± 0.1 μm.",
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Highly uniform sieving structure by corner lithography and silicon wet etching. / Schurink, B.; Berenschot, E.J.W.; Tiggelaar, R.M.; Luttge, R.

In: Microelectronic Engineering, Vol. 144, 16.08.2015, blz. 12-18.

Onderzoeksoutput: Bijdrage aan tijdschriftTijdschriftartikelAcademicpeer review

TY - JOUR

T1 - Highly uniform sieving structure by corner lithography and silicon wet etching

AU - Schurink, B.

AU - Berenschot, E.J.W.

AU - Tiggelaar, R.M.

AU - Luttge, R.

PY - 2015/8/16

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N2 - We describe and demonstrate a fabrication process for silicon sieves with highly-uniform, micron-sized pyramidal shaped pores featuring squared apertures. These sieves are fabricated over areas of several square millimetres by means of double-side standard UV-lithography and wet etching in (1 0 0)-silicon. We intend to use these sieves for hydrodynamic cell capture devices (sieves), suitable for integration of electrodes for electrophysiological measurements of neuronal networks. For the fabrication process, standard plain silicon wafers are used, without the need for etch-stop layers or silicon-on-insulator. To ensure that the sieve contains pores with identical aperture sizes by merely the use of a timed etch-stop, sacrificial octahedral structures are formed underneath each pore by means of corner lithography. These sacrificial structures counteract non-uniformities in the thickness of the layer defining the sieve, resulting from the deep (>500 μm) anisotropic backside wet etch process. For our intended use, we aimed for pyramidal pits with a base length of 20 μm and an aperture at their tips of 3 μm over a circular sieve area with a diameter of 2.4 mm. In order to minimize the non-uniformity in sieve thickness, the deep back-etch is studied by applying KOH and TMAH etchants using variations in temperature of the etchant as well as variations in size and shape of the applied mask opening on the backside of the silicon substrate. With optimal conditions, both etchants can be used to successfully realize sieves. However, the best results are obtained for a back-etch in TMAH (25 wt%, 71 °C) with Triton X (0.1 vol%) as an additive. The later conditions yield a non-uniformity of 0.7 μm for a sieve thickness of 18 μm. Within the sieve area, all 900 square pores, evenly distributed with a 70 μm pitch, have an aperture of 3.2 ± 0.1 μm.

AB - We describe and demonstrate a fabrication process for silicon sieves with highly-uniform, micron-sized pyramidal shaped pores featuring squared apertures. These sieves are fabricated over areas of several square millimetres by means of double-side standard UV-lithography and wet etching in (1 0 0)-silicon. We intend to use these sieves for hydrodynamic cell capture devices (sieves), suitable for integration of electrodes for electrophysiological measurements of neuronal networks. For the fabrication process, standard plain silicon wafers are used, without the need for etch-stop layers or silicon-on-insulator. To ensure that the sieve contains pores with identical aperture sizes by merely the use of a timed etch-stop, sacrificial octahedral structures are formed underneath each pore by means of corner lithography. These sacrificial structures counteract non-uniformities in the thickness of the layer defining the sieve, resulting from the deep (>500 μm) anisotropic backside wet etch process. For our intended use, we aimed for pyramidal pits with a base length of 20 μm and an aperture at their tips of 3 μm over a circular sieve area with a diameter of 2.4 mm. In order to minimize the non-uniformity in sieve thickness, the deep back-etch is studied by applying KOH and TMAH etchants using variations in temperature of the etchant as well as variations in size and shape of the applied mask opening on the backside of the silicon substrate. With optimal conditions, both etchants can be used to successfully realize sieves. However, the best results are obtained for a back-etch in TMAH (25 wt%, 71 °C) with Triton X (0.1 vol%) as an additive. The later conditions yield a non-uniformity of 0.7 μm for a sieve thickness of 18 μm. Within the sieve area, all 900 square pores, evenly distributed with a 70 μm pitch, have an aperture of 3.2 ± 0.1 μm.

KW - Corner lithography

KW - Sacrificial structures

KW - Silicon sieves

KW - Uniform anisotropic wet etching

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