Tokyo Electron (Ireland)

This paper present an optimized CoZrTaB-based laminated thin films with a novel wet etch-able oxide dielectric material. Wet etching capability was studied on the stack material exhibiting a narrow and clean undercut. Good uniaxial anisotropy with low coercivity was achieved via in-situ magnetic alignment during magnetron sputtering. Permeability of 432 and Q-factor of 23.4 at 100 MHz were observed in high frequency permeameter measurement. Finally thermal annealing was carried out at various temperatures. Uniaxial anisotropy was maintained up to 300 °C, while an enhancement of permeability (by 25%) was observed.

Atomic layer deposition (ALD) has recently received increasing attention for the growth of high-conformity silicon nitride (SiN) thin films. In particular, plasma enhanced ALD (PEALD) allows SiN deposition at substantially lower temperatures (< 400 °C) with better film properties, compared to thermal ALD. These advantages make PEALD more attractive for ultra large scale integrated circuit (ULSI) device fabrication where the growth of aspect ratio independent and high-quality conformal thin dielectric films is tremendously important. The PEALD of SiN films involves a repetitive two-step process: (1) adsorption and decomposition of silicon-containing precursors and ii) nitridation of the Si-rich surface by active N species emanating from the plasma. Halogenated silanes such as hexachlorodisilane, bis(tertiary-butyl-amino)- silane, and dicholorosilane (DCS, SiH2Cl2) have been utilized as Si precursors. Despite previous studies, the underlying reaction mechanisms of these Si precursors with a N-rich SiN surface during PEALD still remain uncertain. Parameters controlling the rate of growth and uniformity have been demonstrated experimentally, but without knowledge of the reaction mechanisms, direct contributions of specific process conditions cannot be explained. Using first-principles density functional theory (DFT) calculations combined with experimental characterization, we have examined and identified a novel mechanism for the adsorption and decomposition of DCS on a N-rich SiN surface. Our study predicts that the DCS adsorption and dissociation can occur by overcoming a moderate barrier (~ 0.3 eV), far lower than the prohibitively large barriers predicted for previously proposed mechanisms. Through a detailed electronic structure analysis of the reaction intermediates, we have also elucidated the principles underlying the reaction mechanism, notably the hypervalent nature of Si which permits the facile reaction of molecularly adsorbed DCS with primary and secondary amines on the surface, followed by simultaneous Cl release and deportation steps and subsequent HCl formation and desorption. We have examined the same mechanism utilizing alternative precursors and the predicted trends are found to be corroborated with the important properties of the system. Understanding these principles allows us to develop guidelines for processing conditions, such as the importance of maintaining the proper surface composition to facilitate Si precursor adsorption and dissociation. Our study provides insight into the SiN ALD process via chlorosilanes and guidelines to control the deposition for high-quality SiN films and provides a framework for future theoretical studies of surface reactions during ALD.

Introduction As semiconductor devices become smaller and more highly integrated, it becomes necessary to remove increasingly smaller particles. Currently, various processes such as atomized spray cleaning are being used for particle removal. This method is good for removing larger particles, but it is difficult to remove smaller particles with this kind of process. During atomized spray cleaning there is a boundary layer at the substrate surface which reduces the shear stress that ultimately provides the force to move particles away from the surface. Similarly, if the carrier gas flow rate is increased in order to get higher particle removal efficiency (PRE), above a certain amount there is the possibility of pattern damage. In the case of chemical cleaning, for example SC1 (ammonia + peroxide) cleaning on Si substrates, there is the concern of film loss due to etching of the substrate as well. In this paper, we propose a new cleaning method for removing smaller particles without pattern damage or film loss. New process Solid Phase Clean is a process that uses a polymer to coat the surface of the substrate. The polymer film covers the particles and then directly removes the particles when the film is removed. Furthermore, it does not attack fine patterns and does not etch the substrate material. Figure 1 shows the Solid Phase Clean process. The first step is polymer coating. Particles are covered with the polymer and encapsulated by it. The second step is treatment. The polymer is removed by a treatment liquid, and the particles are removed with the polymer during this step. Experimental Figure 2 shows particle removal evaluation. Smaller particles down to (30nm) were successfully removed. This process achieved higher particle removal performance than atomized spray, especially with particles under 100nm. Figures 3 and 4 show pattern damage and substrate etching results. They show that there is low risk of substrate damage occurring. Mechanism Figure 5 shows the cleaning energy model for this process. We considered the interface energies of each of the touching phases: polymer, particle, substrate, and treatment liquid. Figure 5 E(a) is the condition where the particle is lifted off of the substrate, and Figure 5 E(b)shows the condition where the particle stays attached to substrate. By calculating the total interface energy of these systems, we modeled the cleaning mechanism of this process. Energy to remove particle; Δ\U0001d438 (mN/m2) = \U0001d438 (a)−\U0001d438(b) = (1−\U0001d719)(\U0001d6fe14+\U0001d6fe24−\U0001d6fe12 )+\U0001d719(\U0001d6fe23−\U0001d6fe34) If Δ\U0001d438<0, particles would be removed. - \U0001d6fe\U0001d456\U0001d457: surface energy of interface between phases \U0001d456 and \U0001d457 -\U0001d719: fraction of particle surface area that is not touching substrate (0.5<\U0001d719<1). - (a) : total surface energy of interface particle is lifted off of substrate - (b) : total surface energy of interface particle stays attached to substrate Figure 6 shows the calculation of the interface energy. As this figure shows that −Δ\U0001d438 is over 0, it predicts that particles will be removed. Conclusion Solid Phase Clean is a new cleaning technology that allows removal of smaller particles. By using a polymer to coat the substrate and particles, the polymer is able to directly apply force to the particles and remove them. With this process we achieved high particle removal performance without pattern damage or significant etching of the substrate. We also estimate the removal force and developed a model for particle removal performance of this process by use of an interface energy model. Figure 1

As semiconductor devices become smaller and more highly integrated, it becomes necessary to remove increasingly smaller particles. Currently, various processes such as atomized spray cleaning or chemical cleaning are being used for particle removal, but as particles get smaller these methods have problems of pattern damage or unacceptable film loss. In this paper, we propose a new cleaning method called Solid Phase Clean that uses a polymer film to remove smaller particles without pattern damage or film loss, and accompanying theory to explain its mechanism in terms of surface energies.

This paper presents a theoretical analysis of a 180 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">deg</sup> hybrid coupler based on coupled lines. The analysis is applicable for the case where the non-TEM nature of coupled lines must be considered. The method used to analyze the coupler is based on an analytical <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i> matrix approach, which provides suitable expressions for the design of the coupler. The design procedure is demonstrated by the fabrication of a 24-GHz coupler using low-temperature co-fired ceramic. The realized coupler has non-interspersed inputs and outputs, reduced substrate area and robustness to layer misalignment. The measured characteristics are in good agreement with simulations and demonstrate good performance of the fabricated coupler. An application example of the hybrid coupler in a compact-sized phasing network for an in-phase/quadrature mixer is also described.

In a shared medium network like the 802.11b WLAN, predicting the quality of VoIP calls from the resource usage of the wireless medium is highly desirable. Analyzing the bandwidth usage at the L2/MAC layer may be especially useful for potential QoS provisioning and call admission schemes. This paper experimentally investigates the relationship between resource utilization in WLANs and the quality of VoIP calls transmitted over wireless medium. Specifically we evaluate how the amount of free bandwidth influences transmission impairments (i.e. delay, loss, and jitter) and thus call quality. Resource utilization (under the MAC bandwidth components framework) is calculated by a WLAN resource monitoring application that passively "sniffs" packets at the L2/MAC layer and analyses their headers and temporal characteristics. The quality of VoIP calls is predicted using an extended version of the ITU-T E-model, which estimates user satisfaction from time varying transmission impairments