<p>A wafer-scale metal self-rolled-up membrane platform has been proposed for the design and fabrication of radio-frequency on-chip lumped passive components, which is demonstrated on a commercial 4-inch sapphire batch fabrication line. Compared to the traditional methodology including planar or SiN<sub>x</sub> based self-rolled-up membrane processing technologies to obtain the most basic passive lumped components, such as inductors and capacitors on the chip, this platform enables more compact three-dimensional construction of the component device structure with higher electrical performance. For demonstration, batches of wafer-scale RF inductors and capacitors are fabricated through precise design based on electromagnetic analysis. Measurement results show that radio-frequency inductor samples obtain inductance of 0.6 nH~3.4 nH and a maximum quality factor of 3.1 ~ 7.3 with the largest inductance density of 2.26<InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41467_2025_57769_Article_IEq1.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="66" /> </InlineMediaObject> <EquationSource Format="TEX">$\,{{{\rm{\mu }}}}{{{\rm{H}}}}/{{{{\rm{mm}}}}}^{2}$</EquationSource> <EquationSource Format="MATHML"><math> <mspace width="0.25em" /> <mi mathvariant="normal">μ</mi> <mi mathvariant="normal">H</mi> <mo>/</mo> <msup> <mrow> <mi mathvariant="normal">mm</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msup> </math></EquationSource> </InlineEquation>, and a typical RF capacitor sample show capacitance of 0.5 pF with the largest capacitance density of 1528.4 <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41467_2025_57769_Article_IEq2.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="62" /> </InlineMediaObject> <EquationSource Format="TEX">${{{\rm{pF}}}}/{{{{\rm{mm}}}}}^{2}$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">pF</mi> <mo>/</mo> <msup> <mrow> <mi mathvariant="normal">mm</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msup> </math></EquationSource> </InlineEquation>. After post electroplating, coper layer thickness of a 1.1 nH inductor is increased to be ~ 2.7 μm from 120 nm with the inner diameter of 80 μm, and the maximum quality factor is significantly increased to 18 @ 1.4 GHz. Standalone inductors can be successfully cut off from a 4-inch sapphire wafer by using laser modification cutting.</p>

Wafer-scale platform for on-chip 3D radio frequency lumped passive components using metal self-rolled-up membrane technique

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2025年3月13日

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Zhikun Zhou,
Zihan Zhang,
Hanlin Zhang,
Xianchao Wei,
Wei He,
Quhuan Shen,
Xiuwen Bi,
Tao Yuan,
Xiaochen Chen,
Lei Sang,
Wen Huang

摘要

A wafer-scale metal self-rolled-up membrane platform has been proposed for the design and fabrication of radio-frequency on-chip lumped passive components, which is demonstrated on a commercial 4-inch sapphire batch fabrication line. Compared to the traditional methodology including planar or SiN_x based self-rolled-up membrane processing technologies to obtain the most basic passive lumped components, such as inductors and capacitors on the chip, this platform enables more compact three-dimensional construction of the component device structure with higher electrical performance. For demonstration, batches of wafer-scale RF inductors and capacitors are fabricated through precise design based on electromagnetic analysis. Measurement results show that radio-frequency inductor samples obtain inductance of 0.6 nH~3.4 nH and a maximum quality factor of 3.1 ~ 7.3 with the largest inductance density of 2.26 $\,{{{\rm{\mu }}}}{{{\rm{H}}}}/{{{{\rm{mm}}}}}^{2}$ $μ H / {mm}^{2}$ , and a typical RF capacitor sample show capacitance of 0.5 pF with the largest capacitance density of 1528.4 ${{{\rm{pF}}}}/{{{{\rm{mm}}}}}^{2}$ $pF / {mm}^{2}$ . After post electroplating, coper layer thickness of a 1.1 nH inductor is increased to be ~ 2.7 μm from 120 nm with the inner diameter of 80 μm, and the maximum quality factor is significantly increased to 18 @ 1.4 GHz. Standalone inductors can be successfully cut off from a 4-inch sapphire wafer by using laser modification cutting.