PARC’s on-chip microcoil demonstrates world-record performance Koenraad Van Schuylenbergh , Christopher L. Chua, David K. Fork, Jeng-Ping Lu and Bernie Griffiths¹ Palo Alto Research Center ¹ Mixed Signal Systems Inc., Scotts Valley OUT-OF-PLANE INDUCTORS • Inductor losses: – Magnetic field in substrate eddy currents – Skin and proximity effects – Capacitive substrate coupling • Solution = out of plane and parallel to substrate
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
1
PARC’s on-chip microcoil demonstrates world-record performanceKoenraad Van Schuylenbergh, Christopher L. Chua, David K. Fork, Jeng-Ping Lu and Bernie Griffiths¹
Palo Alto Research Center
¹ Mixed Signal Systems Inc., Scotts Valley
OUT-OF-PLANE INDUCTORS
• Inductor losses:– Magnetic field in substrate ⇒ eddy currents– Skin and proximity effects– Capacitive substrate coupling
• Solution = out of plane and parallel to substrate
2
STRESSEDMETAL™ TECHNOLOGY
σ∆Y
hr =Pressure [mTorr]
Stress [Gpa]
0 1 2 3 4 5
2
1
0
-1
-2 compressivecompressive
tensiletensile
neutralneutral
Film stress varies with ambient sputter pressure
STRESSEDMETAL™ MICROCOIL
• 3-dimensional MoCr scaffolds
• electroplated after self assembly, electroforms seam
3
INDUCTOR SELF ASSEMBLY
beforebefore afterafter
life video at www.parc.com/solutions/oopcoil
Video recording of an actual assembly, NOT a simulation.
WAFER-SCALE SELF ASSEMBLY
• unmodified 0.6µm BiCMOS wafer (X-FAB xb06).
• Each coil contacts the ESD unprotected base of a RF BJT.
• The StressedMetal™ process did not degrade the BJTs’ RF performance.
4
MICROCOIL CHARACTERIZATION
• One-port RF-IV impedance measurement: Z = R + j.ω.L
• Convert to equiv. Ls-Rs-Cs model for better physical understanding
• Integration on various substrates incl. active circuit wafers
• StressedMetal™ coils on 15..20Ω.cm silicon:– Q = 40..50 with thin aluminum GND– Q = 60..80+ with thick copper GND
– Both values are the highest published at around 1GHz for unaltered low resistance silicon. The numbers on thick copper are very close to the theoretical maximum based on skin effect alone.
• Monolithic balanced BiCMOS oscillators: StressedMetal™ coils on Al yield 12.3dB PN improvement @ 100kHz over in-plane spirals (normalized 14.6dB)
• Up to 6dB better phase noise possible with copper GND