Sunghwan Min

Through-package-via formation and metallization of glass interposers

Interposer technology has evolved from ceramic to organic materials and most recently to silicon. Organic substrates exhibit poor dimensional stability, thus requiring large capture pads which make them unsuitable for very high I/Os with fine pitch interconnections. Therefore, there has been a trend to develop silicon interposers. Silicon interposers however, suffer in two ways; 1) they are expensive to process due to the need for electrical insulation around via walls, and 2) they are limited in size by the silicon wafer from which they originate. In this paper, glass is proposed as a superior alternative interposer technology to address the limitations of both silicon and organic interposers. The inherent electrical properties of glass, together with large area panel size availability, make it superior compared to organic and silicon-based interposers. Glass however, is not without its challenges. It suffers in two ways: 1) formation of vias at low cost, and 2) its lower thermal conductivity compared to silicon. This research explores glass as an interposer material, and addresses the above key challenges in through package via (TPV) formation and subsequent low cost and large area metallization to achieve very high I/Os at fine pitch.

Construction of broadband passive macromodels from frequency data for simulation of distributed interconnect networks

This paper discusses a method for the construction of multiport broadband passive macromodels using frequency data obtained from an electromagnetic simulation or measurements. This data could represent the frequency response of a distributed interconnect system. The macromodels are generated using rational functions by solving an eigenvalue problem. For numerical computation, the macromodels are represented as a summation of rational functions consisting of low-pass, band-pass, high-pass, and all-pass filters. The stability and passivity of the macromodels are enforced through constraints on the poles and residues of rational functions. To enable the construction of broadband macromodels, methods based on band division, selector, subband reordering, subband dilation, and pole replacement have been used. Two test cases that describe the performance of the proposed algorithm, and three test cases that are representative of distributed systems have been analyzed to verify the efficiency of the method.

Modeling and analysis of power distribution networks for Gigabit applications

As the operating frequency of digital systems increases and voltage swing decreases, it becomes very important to characterize and analyze power distribution networks (PDNs) accurately. This paper presents the modeling, simulation, and characterization of the PDN in a high-speed printed circuit board (PCB) designed for chip-to-chip communication at a data rate of 3.2 Gbps. The test board consists of transmitter and receiver chips wirebonded onto plastic ball grid array (PGBA) packages on a PCB. In this paper, a hybrid method has been applied for analysis, which consists of the transmission matrix method (TMM) in the frequency domain and macromodeling method in the time domain. As an initial step, power/ground planes have been modeled using TMM. Then, the macromodel of the power/ground planes has been generated at the desired ports using macromodeling. Finally, the macromodel of the planes, transmission lines, and nonlinear drivers have been simulated in standard SPICE-based circuit simulators for computing power supply noise. In addition to noise computation, the self and transfer impedances of power/ground planes have been computed and the effect of decoupling capacitors on power supply noise has been analyzed. The methods discussed have been validated using hardware measurements.

Chip-last embedded actives and passives in thin organic package for 1–110 GHz multi-band applications

This paper presents for the first time a novel manufacturing-compatible organic substrate and interconnect technology using ultra-thin chip-last embedded active and passive components for digital, analog, MEMS, RF, microwave and millimeter wave applications. The architecture of the platform consists of a low-CTE thin core and minimum number of thin build up organic dielectric and conductive layers. This organic substrate is based on a new generation of low-loss and thermally-stable thermosetting polymers (RXP-1 and RXP-4). Unlike LCP- and Teflon-based materials, the RXP material system is fully compatible with conventional FR-4 manufacturing processes. Ultra-thin silicon test die (55µm thick) has been embedded in a 60µm deep cavity with a 6-metal layer RXP substrate and a total thickness of 0.22mm. The embedded IC is interconnected to the substrate by ultra-fine pitch Cu-to-Cu bonding with polymer adhesives. This novel interconnection process performed at 180°C, has passed 1,000 thermal shock cycles in reliability testing. Because of manufacturing process simplicity and unparalleled set of benefits, the chip-last technology described in this paper provides the benefits of chip-first without its disadvantages and thus enables highly miniaturized, multi-band, high performance 3D modules by stacking embedded 3D ICs or packages with embedded actives, passives and MEMS devices.

Design and fabrication of bandpass filters in glass interposer with through-package-vias (TPV)

This paper presents the integration of WLAN (2.4 and 5GHz) bandpass filters in glass interposer using through-package vias. The filters include novel embedded passive components such as stitched capacitors with reduced shunt parasitics and via-based inductors that provide area reduction. The filters designed for 2.4 GHz showed an insertion loss of less than 2dB and better than 15dB return loss, while the 5GHz filters showed an insertion loss of less than 1dB with better than 20dB return loss. Stop-band rejection of over 35dB was observed at 2.2 GHz on the 2.4 GHz bandpass filters. The measured results showed good agreement with the simulated values and indicated that the performance on glass interposer closely matches the performance of the more expensive high resistivity silicon with similar properties.

Efficient construction of two-port passive macromodels for resonant networks

This paper discusses an efficient method for the construction of two-port macromodels by ensuring the stability and passivity of the circuit. The macromodels are based on rational functions that are generated by solving an eigenvalue problem. The passivity is enforced through constraints on the residue of the rational function. This method was applied on simulation and measured data and found to give good results.

High performance spiral inductors embedded on organic substrates for SOP applications

This paper presents the design, measured data, and systematic analysis of spiral embedded inductors fabricated on standard organic substrates using low-cost, large-area MCM-L technology. Several configurations for inductors were investigated to optimize the inductor layout dimensions such as conductor width, number of turns, inner diameter, spacing between inductor and ground, and inductor area. A maximum Q of 100 was measured for a 3.6 nH inductor at 1.8 GHz on an organic substrate with a self resonance frequency of 10.6 GHz within an inductor core area of 0.72 mm/sup 2/. The effects of configurational variables on inductor characteristics such as quality factor, self-resonance frequency, and inductance are discussed. High-Q inductors embedded on organic substrates can find numerous RF and microwave system-on-package (SOP) applications, such as VCOs, IF/RF bandpass filters, LNAs, etc., in which IC chips are flip-chip mounted on the package substrate.

Characterization of Next Generation Thin Low-K and Low-Loss Organic Dielectrics From 1 to 110 GHz

This paper presents, for the first time, characterization results of next generation dielectric core and build up material called RXP, which has low dielectric constant (2.93-3.48) and low loss tangent (0.0037-0.006) up to 110 GHz. Unlike LCP, this material can be made ultra-thin with low processing temperature and is ideally suited for mobile applications. Causal models suitable for high frequency applications have been extracted by measuring the response of cavity resonators using vector network analyzer and surface profiler.

Filter integration in ultra thin organic substrate via 3D stitched capacitor

This paper presents filters integrated in ultra thin multilayer organic substrate using 3D stitched capacitor alleviating shunt parasitics and providing tunable capacitors. Insertion loss of less than 2.2dB, return loss of greater than 15dB at 2.4 GHz and attenuation of greater than 30dB below 2.0 GHz and at 4.7 GHz were measured. The measured results showed good agreement with simulated results. This paper demonstrated 2.4 GHz bandpass filters with size of 2.2mm × 3.0mm × 0.2mm (1.2mm3) in ultra thin organic RXP substrate.

A compact third-order 5 GHz bandpass filter with enhanced stopband characteristics in ultra thin organic substrate

A lumped-element bandpass filter based on new RXP ultra-thin organic technology with enhanced stopband rejections is proposed in this paper. The design is based on a third-order capacitively-coupled resonator circuit with unique resonator and ground inductor. For demonstration of the proposed circuit and RXP technology, a 5 GHz bandpass filter has been implemented in a four-metal layer 0.191 mm thin RXP substrate. The measured results have a good agreement with the simulation and show that insertion loss is less than 1.24 dB with larger than 1 GHz bandwidth and sharp rejections at both low and high stopband.