This document discusses fabricating 3D SiNx self-rolled tubes for use as on-chip inductors. The current limitations of RFIC inductors include large footprint, low quality factor, and high fabrication costs. This project focuses on using self-rolled SiNx tubes as a 3D structure to address these limitations. Key steps in the process include lithography, etching, deposition, and metrology. Measurement results found the fabricated tubes achieved over 25 turns with 60nm gold, the best reported. Inductance was as high as 10nH per cell and transformer turn ratio reached 26:1, showing promising performance benefits over conventional inductors.

1. 𝑆𝑖𝑁𝑥 Self Rolled-up Tube Inductors
Siyu LiuMentor: Wen Huang Faculty Advisor: Xiuling Li
Introduction Overview Process
Result & Measurement
Limitations of current RFIC
inductors:
 Require large on-chip footprint
 Large parasite effect / low Q
factor
 High fabrication cost
Objective:
This project focuses on fabricating
3D structure via self rolled-up 𝑆𝑖𝑁𝑥
tubes
• Lithography: the process of transferring
patterns of geometric shapes in a mask to
a thin layer of radiation-sensitive material
(called resist) covering the surface of a
semiconductor wafer.
• Etching: selectively dissolve the surface
of (a semiconductor or printed circuit) with
a solvent, laser, or stream of electrons.
• Metrology: measurement
• Deposition: adding a thin film of material
onto a substrate or onto previously
deposited layers
I would like to extend my heartfelt gratitude to my
mentor Wen Huang, my faculty advisor Professor
Xiuling Li, and my group mate Jingchao Zhou for their
patient guidance and valuable advice throughout the
research program.
Future research directions may include:
1. Stimulate and optimize the self-rolled-up transformers.
2. Fabricate optimized devices and test their performances.
Reference:
1. Huang, W et al., Nano Letters, 2012, 12, 6283-6288.
2. Hsu, H.M. et al., IEEE Trans. Electron Devices, 2012, 59(11), 3061-3068.
3. Xiuling Li, J. Phys. D: Appl. Phys. 41 (2008) 193001 (12pp)
In our experiment, 𝐴𝑙2 𝑂3 cover layer employed 𝑆𝑖𝑁𝑥 micro-tube can obtain more than 25 turns with 60 nm
𝐴𝑢 metal on top, which is the best results reported so far. The inductance could be as high as 10 nH/cell
for the on-chip inductor, and turn ratio could be as high as 26:1 for the on-chip transformer.
SEM images of fabricated device(credits to Wen Huang)
Figure.4
Simulation(HFSS)
Figure.5
Fabrication
Figure.6
Test
Figure.2
Cross section
Figure.1
Structure
Potential large turn density coil
Small footprint
Low transition cost for the industry
Promising performance
Figure1.3.4.6 Photo credits to Wen Huang
Figure.3
Mask Design
Photo found onlinePhotos found online