Title The Effect of Polyimide Fixation on Thermal Performance of GaAs Cantilever Based MEMS: A 3D Numerical Analysis with DEETEN Eduard Burian 1 and Tibor Lalinský 2 1 LOX Technologies, Bratislava, Slovakia, www.loxtec.com, [email protected]2 Institute of Electrical Engineering of SAS, Bratislava, Slovakia, [email protected]
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Title The Effect of Polyimide Fixation on Thermal Performance of GaAs Cantilever Based MEMS: A 3D Numerical Analysis with DEETEN Eduard Burian 1 and Tibor.
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Title
The Effect of Polyimide Fixation on Thermal Performance of GaAs Cantilever Based MEMS: A 3D Numerical Analysis with DEETEN
Eduard Burian1 and Tibor Lalinský2
1 LOX Technologies, Bratislava, Slovakia, www.loxtec.com, [email protected] Institute of Electrical Engineering of SAS, Bratislava, Slovakia, [email protected]
Contents
1. Introduction2. Basics of DEETEN3. Studied MTC MEMS4. Results of DEETEN Simulations5. Conclusions
Introduction
In the first part of this presentation, we refer of a novel simulation technology DEETEN, of its principles and implementation for thermal analysis of micromechanical systems.
In the second part, we refer of results of DEETEN 3D thermal analysis of a GaAs Micromechanical Thermal Converter, particularly, to analysis of thermal effect of polyimide fixation of the cantilever beam of this MEMS.
Basics of DEETEN
Differential Equations Efficient Treatment by Eliminative Nestingis a novel software simulation technology capable of efficient multi-million-point 3D simulations on a conventional PC. It takes simple math of finite difference method and field relaxation algorithms together with modern software technologies to achieve impressive computational performance.
The efficiency and performance of DEETEN is achieved by:• recursive domain decomposition of simulation space• topology and field complexity is considered in created domain chain• multigrid capability, pre-computed field is smoothed on finer meshes• simple discretization algorithms based on finite differences method• solution to PDEs by field relaxation algorithms • computer-friendly (octree) domain structure defined by means of
OOP
Basics of DEETEN / the D10 domain
D10 domain consist of 10x10x10=1000 mesh points from those 8x8x8=512 points are inner 6x8x8=384 of the outer points contribute to solution of
PDEs in a parent domain, up to 8 smaller child domains can
exist the child domain is half the size of the parent domain inner volume of a child matches perfectly with one inner
parent octant domain chaining can go on till desired spatial resolution
is achieved
Basics of DEETEN / domain overlapping
Defined conditions assure that two neighboring child domains are overlapped so that a part of the boundary of one child domain covers with the first plane of inner points of the other, even in the case they have no common parent. Inner volumes of child domains, which never overlap, create a smooth simulation mesh necessary for sequential (domain-by-domain) treatment of PDEs.
example of domain structure by cantilever MTC simulation
upper level domains only
Basics of DEETEN / 3D domain structure
Micromechanical Thermal Converter (MTC) is being developed as key par of the Microwave Transmitted Power Sensor (MTPS) at Institute of Electrical Engineering of SAS. We studied two MTC topologies:
1. cantilever-based MTCtwo 1-2m thin GaAs cantilevers with
2. isolated membrane-like MTCGaAs “island” 1m thin is floating
on polyimide membrane
Studied MTC MEMS / topologies
Contact pad
Cantilever
pHEMT - HeaterpHEMT–Temperature sensor
Polyimide membrane
Polyimide membrane
MEMS were kept in air and ambient temperature is 300K air thermal conductance is included into model power dissipation in a HFET heater is set to 1mW
Cantilever MTC: main domain dimensions 1.6x1.6x0.16mm domain level limit set to 5, i.e. spatial resolution 1:256 at
maximum typically 1500 domains were created, with 1.5M mesh points in comparison, regular rectangular mesh requires 2563=16.7M
points
Membrane-like MTC: main domain dimensions 1.0x1.0x0.1mm domain level limit set to 6, I.e. spatial resolution 1:512 at
maximum typically 2500 domains, 2.5M mesh points in comparison to regular rectangular mesh with 5123=134M
points
Studied MTC MEMS / simulation conditions
Polyimide-fixed cantilever beams: TMAX=9.96K
Non-fixed cantilever beams: TMAX=10.11K
Polyimide-induced degradation does not exceed 2% Heat dissipation through metallic leads results is ~40%
Results of DEETEN simulations / cantilever MTC
Maximuim temperature in center: TMAX=16.76K
Effective thermal resistance ~13K/mW
Results of DEETEN simulations / membrane-like MTC
In thermal investigations of two design of a MTC MEMS, DEETEN has been proven as viable and promising technology.
Joining advanced numerical methods for PDE solving with modern, object-oriented software technologies can substantially improve computational performance in electrophysical simulations.
Next plans: more detailed thermal investigation of MEMS details in 100-10nm range simulation of complex thermal, electronic and mechanic