Coventor (France)

This paper reports gravity and film stress effects on the up and down motion of a MEMS deformable mirror, actuated electrostatically by an array of pistons. To keep the inter-electrode gap small for efficient electrostatic force actuation, the pistons are located close to the underside of the mirror and move independently as the mirror deforms. The mirror membrane is 8 mm in diameter, 2µm thick and made of single crystal silicon. With a horizontal orientation the relatively large weight of the pistons, fabricated into thick silicon substrate, deform the mirror. However, by placing the device vertically, a bidirectional motion and upward displacement of 0.2 µm with 30 V actuation was confirmed. The cause of unexpected small, localized downward displacement, was also investigated via finite element analysis.

With the rising demand for integrated silicon photonics as a technology platform, it becomes crucial to provide variation-aware models and design for manufacturability (DFM) methods to inform the design of silicon photonic devices and circuits. In this paper, we demonstrate the application of the adjoint method to estimating the sensitivity of photonic components against key process variations inherited from integrated circuit fabrication technologies. In particular, we examine the impact of line edge roughness (LER) on a passive Y-branch, and validate our results with ensemble virtual fabrication simulations. The adjoint sensitivity and variance estimation of Y-branch transmission imbalance is seen to be highly efficient in comparison to direct ensemble simulation.

In this paper, we model fin pitch walk based on a process flow simulation using the Coventor SEMulator3D virtual platform. A taper angle of the fin core is introduced into the model to provide good agreement with silicon data. The impact on various Self-Aligned Quadruple Patterning process steps is assessed. Etch sensitivity to pattern density is reproduced in the model and provides insight on the effect of fin height variability.

This paper assesses Self-Aligned Block (SAB) and Fully Self-Aligned Via (FSAV) approaches to patterning using a iN5 (imec node 5 nm) vehicle and Metal 2 Self-Aligned Quadruple Patterning. We analyze SAB printability in the lithography process using process optimization, and demonstrate the effect of SAB on patterning yield for a (8 M2 lines x 6 M1 lines x 6 Via) structure. We show that FSAV, compared to standard Via patterning, has no beneficial impact but prevents dielectric breakdown between two adjacent M1 lines.

This paper proposes a framework for system-level modeling and simulation of a Micro Electro-Mechanical System (MEMS). We show how a reduced-order model of MEMS can be integrated into SystemC-AMS. We propose the use of an external linear algebra library and alternative time integration method. Both are used to customize a Timed Data Flow (TDF) module to address MEMS modeling. Experiments are conducted on a biaxial accelerometer to verify its response to a ramp impulse. Our implementation runs about twice as fast as the state space resolution currently implemented in SystemC-AMS 2.0. Results highlight potential improvements of SystemC-AMS standard to correctly simulate the analog behavior of MEMS devices.

The effects of heat sink orientation and metal foam geometry on the pool boiling characteristics of FC -72 in high porosity aluminum metal foam heat sinks are reported. Experiments are conducted on two different foam samples with almost identical porosities but different numbers of pores per inch (PPI). The height of the metal foam in each case is gradually reduced and for each height the foam is tested with the heater surface oriented horizontally and vertically. The effects of varying foam height and different orientations on the onset of nucleate boiling, heat transfer performance and the critical heat flux are studied. Hysteresis and incipience excursion are almost absent when the foam is oriented vertically. The heat transfer performance of the high PPI sample in nucleate boilin g deteriorates in the vertical orientation while that of the low PPI sample shows a two tailed trend, first decreasing and then increasing with reduction in foam height. The temperature jump, marking transition from nucleate to film boiling, and the critic al heat flux both increase with decreasing height in the low PPI sample for both orientations. This temperature jump is however seen to decrease in the vertical orientation as the PPI is increased. At 40 PPI, no temperature jump is observed and transition is seen to occur very smoothly indicating an optimum pore spacing.