We report on CMOS-integrated vertically stacked gate-all-around (GAA) Si nanowire (NW) MOSFETs with in-situ doped source-drain stressors and dual work function metal gates. We demonstrate that oxidation-induced SiGe/Si fin deformation by STI densification is effectively suppressed by a SiN liner. This SiN fin protection improves the controllability of nanowire formation. In addition, highly-selective Si nano-wire release and inner spacer cavity formation without Si re-flow are demonstrated. Finally, for the first time we report functional ring oscillators based on stacked Si NW-FETs.

This study examines different approaches to determining the chip failure rate that occurs due to dielectric cracking under C4 sites during chip joining. We show that testing of the strength of individual C4s by a single bump shear technique gives a strength distribution that is well described by a Weibull distribution with a Weibull modulus that lies in the range 10-20. Simulations of the spatial distribution of failing C4s during a chip joining test using this distribution, however, are found to be inconsistent with those observed experimentally. From this observation we conclude that the observed fails arise from a defect population that is not well characterized by single bump shear tests. We propose an alternative to SBS testing in which we directly count the number of fails that occur at a given stress level by comparing the location of the fails observed in multiple sonoscan images of chips to the C4 stress map calculated from a finite element model. An example is presented where the strength distribution of the defect tail is characterized from the analysis of C4 fails induced by an accelerated chip joining test. From this distribution we show how it is possible to project chip failure rates that arise from a manufacturing chip joining process.

The paper examines the factors that affect the formation of delaminations under C4 joints during chip joining. Through multiscale finite element modeling and chip joining experiments we find that two important parameters determining the susceptibility to C4 delaminations( white bumps) are the effective modulus of the low-K levels in the BEOL stack and the thickness of the upper level in the stack that are built in an oxide dielectric. A simple effective spring model is developed to estimate the impact of metal loading at the via and line levels of interconnect structure on the effective modulus of the low-K dielectric stack. The importance of the effective modulus as a parameter controlling white bump formation is confirmed using a purpose built chip in which the effective modulus is modulated in each corner of the chip. Based on the observations from chip joining experiments it is demonstrated that failng BEOL structures can be differentiated from safe structures using a fail/safe map that is constructed using the effective modulus of the low-K levels and the thickness of the oxide levels as the two axes of the map.

During technology development, the study of low-k TDDB is important for assuring robust chip reliability. It has been proposed that the fundamentals of low-k TDDB are closely correlated with the leakage conduction mechanism of low-k dielectrics. In addition, low-k breakdown could also be catalyzed by Cu migration occurring mostly at the interface between capping layer and low-k dielectrics. In this study, we conducted several important experiments including leakage modulation by changing the capping layer without changing the electric field, TDDB modulation by liner-free interconnect build, 3D on-flight stress-induced leakage current (SILC) measurement, triangular voltage sweep (TVS) versus TDDB, and Cu-free interconnect build at 32nm to experimentally confirm the proposed electron fluence driven, Cu catalyzed interface low-k breakdown model.

We address package-induced degradation of BEOL interconnects and approaches for recovery. For dielectrics, we cover process options and position in stack for ULK films and how these lead to differences in strength. Experiments were designed to cross-compare multiple methods to test susceptibility of BEOL interconnect to CPI damage. We also address how Chip Package Interaction changes as BEOL features and layout evolve.

There is an ongoing need in the microelectronics industry to increase circuit density in multilevel back-end-of line (BEOL) interconnects to improve the operating speed and reduce power consumption. One way to maintain capacitance-resistance (RC) performance, without de grading yield or reliability is through introduction of porous ultra low-kappa materials (ULK) as interlevel dielectrics (ILD). This paper presents the ability to tune ULK films through simple processing optimization steps to meet the specific integration requirements. Balancing composition of the film to minimize damage needs to be coupled with improving mechanical integrity for packing compatibility.

A cost effective 28nm CMOS Interconnect technology is presented for 28nm node high performance and low power applications. Full entitlement of ultra low-k (ULK) inter-level dielectric is enabled. Copper wiring levels can be combined up to a total of 11 levels. The inter-level dielectric was optimized for low k-value and high strength. The feature profiles were optimized to enable defect-free metallization using conventional tools and processes. High yields and robust reliability were demonstrated.

A tool has been developed that can be used to characterize or validate a BEOL interconnect technology. It connects various process assumptions directly to electrical parameters including resistance. The resistance of narrow copper lines is becoming a challenging parameter, not only in terms of controlling its value but also understanding the underlying mechanisms. The resistance was measured for 45nm-node interconnects and compared to the theory of electron scattering. This work will demonstrate how valuable it is to directly link the electrical models to the physical on-wafer dimensions and in turn to the process assumptions. For example, one can generate a tolerance pareto for physical and or electrical parameters that immediately identifies those process sectors that have the largest contribution to the overall tolerance. It also can be used to easily generate resistance versus capacitance plots which provide a good BEOL performance gauge. Several examples for 45nm BEOL will be given to demonstrate the value of these tools.

The integration of porous ultra low-k (ULK) films, with k = 2.2, into future technology nodes can add risk to yield and reliability. The porosity of the film makes it more susceptible to damage from CMP process. This work investigates the shifts in the dielectric constant (k) and refractive index (RI) that various barrier slurries have induced on ULK films. Post CMP treatment of these films seems to help in recovering the material property shifts caused by these barrier slurries. Chemical characterization of these films helped in identifying the reason for shifts that were induced in these films after exposure to CMP slurries.

Optimization of SiCOH interfacial strength to underlying SiCHN is a key requirement for establishing a reliable manufacturing process for a low k interlevel dielectric. After discovering that the interfacial failure was a near-interface cohesive failure in the SiCOH film, improved interfacial strength was accomplished by engineering a graded transition region from an initial oxide layer to the bulk SiCOH film. Film deposition conditions were tuned to provide ideal film composition profile, without any carbon spike, throughout this transition region. Deposition conditions were also optimized to avoid known problems with SiCOH, such as plasma instabilities and generation of gas phase nucleated defects. This process optimization approach has been successfully performed for 3 generation nodes (90, 65 & 45nm) involving various SiCOH versions with k=3.0, 2.7 & 2.4.

Abstract not Available.

Ion exchange systems for the removal of nutrient pollutants, even at extremely low concentrations, from wastewater effluents are a major environmental need. This work reports on the features of batch sorption processes for the ultimate removal and recovery of reactive phosphorus, nitrogen, and sulfur anions from aquaculture production wastewater effluents. The sorbent used was a crosslinked polyamine (PAA·HCl) polymeric hydrogel. The PAA·HCl hydrogels were prepared by chemically crosslinking aqueous solutions of linear PAA·HCl chains with epichlorohydrin (EPI). The nutrient anion binding capacity of the gels was studied as a function of various processing parameters. Lab scale batch and experiments showed maximum anion removal, from aquaculture wastewater, with regard to PO43− by 99%, NO3− by 70%, and SO42− by 95%. PO43− diffusivities of 16, 10, and 8×10−6 cm2/s were measured at pH levels of 5.5, 7.0, and 8.5.

This work reports on morphological features of hydrogels, which have been used for the ultimate removal and recovery of nutrient and toxic anions from wastewater effluents. The sorbent used was crosslinked polyamine (PAA center dot HCl) polymeric hydrogels. The surface topography and morphology of these hydrogels were characterized by tapping mode atomic force microscopy. The change of the gel surface in response to the degree of crosslinking was observed via phase imaging. The crosslinker amount affects both the crosslink density and uniformity. Phase images were recorded at moderate to hard tapping conditions (A(sp)/A(0) = 0.3-0.6) and related to surface stiffness variations associated with Young's modulus (E) change. Bright ellipse and sponge-like domains of submicrometer scale were found on irregularly crosslinked gels, while the gel topography was uniform in gels that were prepared with a more regular distribution of crosslinks. The observed AFM domain size was strongly affected by the gel's degree of crosslinking. (c) 2005 Elsevier Ltd. All rights reserved.

This work reports on the features of a sorption processes for the ultimate removal and recovery of reactive phosphorus from aquaculture and poultry production wastewater effluents. The sorbent used was a cross-linked polyamine (PAA-HCl) polymeric hydrogel. The PAA-HCl hydrogels were prepared by chemically cross-linking aqueous solutions of linear PAA-HCl chains with epichlorohydrin (EPI). The phosphorus binding capacity of the gels was measured in standard aqueous solutions as a function of ionic strength. Equilibrium PO4(3-), loadings of 100 mg anion/g gel were obtained. The regeneration ability of the gels was demonstrated by release of the bound phosphorus anions upon washing with 1-2 M NaOH solution, providing opportunities to recover and reuse the gel over multiple cycles. The ionic polyamine gels have been demonstrated to be appropriate materials for treating poultry and aquaculture wastewater effluents. Upon treatment phosphorus anion concentrations were reduced to levels suitable for discharge into natural surface waters.

Systems that are capable of removing highly toxic anions from wastewater effluents, even at extremely low concentrations, are a major need in the defense industry. This study reports on the features of two new batch and continuous-flow sorption processes with regard to ultimate removal and recovery of the perchlorate (ClO4-) anion from ammonium perchlorate (NH4ClO4) wastewater. The sorbent developed is a crosslinked poly(allylamine hydrochloride) (PAA . HCl) polymeric hydrogel. The pH-sensitive PAA . HCl hydrogels were synthesized by chemically crosslinking a solution of linear PAA . HCl chains with epichlorohydrin (EPI). The perchlorate-binding capacity of the polymer gels was measured in standard solutions and studied as a function of gel synthesis parameters. Equilibrium perchlorate loadings of 5770 +/- 870 mg ClO4-/g gel were calculated from measurement of the decrease in perchlorate concentration in aqueous standard solutions using UV-Vis spectrophotometry. Batch experiments in wastewater originating from the Naval Surface Warfare Center (NSWC) Indian Head Division showed that perchlorate concentrations decreased by 85% Preliminary lab-scale packed-column experiments in wastewater achieved up to 40% reduction in total perchlorate content. The regeneration ability of the gels was demonstrated by release of the bound perchlorate anions, upon washing with a LN NaOH solution, providing opportunities to recover and reuse the hydrogel over multiple regeneration cycles. The PAA . HCl hydrogels are demonstrated to be appropriate materials for treating wastewaters that contain ammonium perchlorate. (C) 2001 John Wiley & Sons, Inc.

We have developed poly(allyl amine hydrochloride) (PAA . HCl) polymer hydrogels, that efficiently remove nitrate (NO3-), nitrite (NO2-), and orthophosphate (PO43-) nutrient anions from the aquaculture wastewater. The hydrogels were prepared by chemically crosslinking linear PAA . HCl chains with epichlorohydrin (EPI). The anion binding capacity of the pH sensitive polymer gels was measured in standard solutions and studied as a function of gel synthesis parameters. Equilibrium NO3-N, NO2-N, and PO4-P loading of 15, 1.6, and 17 mg/g of dry gel, respectively, were calculated from the measurement of decrease in anion concentration in aqueous solutions using UV-vis spectrophotometry. Batch experiments showed that nutrient concentrations in aquaculture wastewater effluents decreased with regard to PO4-P by 98 + %, NO3-N by 50 + % and NO2-N by 85 + % within 3 h of reaction. The regeneration of the hydrogels was demonstrated by the release of bound nutrient anions upon washing the gels with a 1 N NaOH solution. These results have demonstrated that the hydrogels are appropriate materials for treating aquaculture wastewater effluents, and reducing the nutrient anion concentrations to levels, less than 10 mg/l NO3-N, 0.08 mg/l NO2-N, and 0.3 mg/l PO4-P, suitable for discharge into natural surface waters. (C) 2000 Elsevier Science B.V. All rights reserved.

Methods that will remove conventional nutrient pollutants such as reactive phosphorus, even at extremely low concentrations, from wastewater effluents are a major need in the aquaculture industry. In this study, novel phosphate binding crosslinked poly(allylamine), PAA HCl, polymeric hydrogel materials were developed, which efficiently bind phosphate anions in aquaculture wastewater effluents. The polymeric hydrogels were synthesized by chemically crosslinking linear PAA HCl chains with epichlorohydrin. The phosphate binding capacity of the synthesized pH sensitive polymer gels was studied as a function of various gel processing parameters. Equilibrium orthophosphate O loadings of 47 mg g(-1) polymer, were calculated from direct measurement of the decrease in phosphate concentration in aqueous solutions using UV spectroscopy. Experiments showed that pollutant concentrations in aquaculture wastewater effluents decreased with regard to by more than 99%. The ability of the gels to bind phosphates was not fouled by particulate or dissolved complex organics and inorganics, or counterions which are present in aquaculture wastewater effluents. The hydrogels can be regenerated by release of the bound phosphates upon washing with a 1 N NaOH solution. Results demonstrated that the novel crosslinked polymeric hydrogels are appropriate materials for treating aquaculture wastewater effluents, and reducing the phosphorus concentrations to levels, less than 0.01 ppm, suitable for discharge to natural surface waters. (C) 1999 Elsevier Science B.V. All rights reserved.