Via hole technology for microstrip transmission lines and passive elements on high resistivity silicon

Abstract

A process is described for the realization of via holes for microstrip transmission lines and passive elements on high resistivity Silicon (p > 4000 Rcm, 100 mm diameter, 100 pm thickness). Via hole etching with vertical sidewalls is performed using an advanced silicon etch (ASE) process. The measured and simulated inductance of the gold metallized via hole is 22 pH. Measurements on a ring resonator -isolated by 550 nm thermal oxide from the substrate -yield a dielectric constant E, = 11.2 and a loss tangent tan6 around for the 4000 Rcm silicon substrate. Attenuation of microstrip trans-mission lines are -= 0.1 dB/mm at 20 GHz.

A Through-Wafer Interconnect in Silicon for RFICs

“…Substrates had a resistivity of [10][11][12][13][14][15][16][17][18][19][20] cm. In the following paragraphs, we give details about each of the key process steps in our technology.…”

“…Previous DRIE-via technologies use a thin coating of metal to line the inside surface of the via [9], [10], whereas others fill the via with highly doped polysilicon to achieve a low-impedance interconnect [11]. These different via technologies have found applications in three-dimensional (3-D) chip stacks [5], as a substrate coil inductor [9], microstrip substrate interconnect [10], and in MEMS [7], [11].…”

“…These different via technologies have found applications in three-dimensional (3-D) chip stacks [5], as a substrate coil inductor [9], microstrip substrate interconnect [10], and in MEMS [7], [11]. The novelty of our via technology is that it features an insulator liner and a solid metal core.…”

Coplanar and microstrip oscillators in SiGe SIMMWIC technology

“…MST enables high Q resonators, lower attenuation, better RF packaging characteristics and well-known design and simulation software. Our recently developed MST technology uses 100 µm substrate thickness and circular via-holes with vertical sidewalls and a diameter of 80 µm [3]. Passive elements like resistors, MIM capacitors and spiral inductors have been realized, tested and mo deled [3].…”

“…In this paper, results are shown on a low noise coplanar 24 GHz SiGe HBT LC oscillator, a coplanar 27 GHz SiGe HBT voltage controlled oscillator (VCO), and a low phase noise microstrip 27 GHz SiGe HBT VCO with a recently developed MST technology [3].…”