On the Existence of the Anomaly in the2 H(d, n) and2 H(d,p) Reactions atE d ≈100 keV

An electrothermal equation of a polysilicon thermal flexure actuator is presented, which takes heat conduction, air convection and radiation into account. A numerical method is developed to solve the equation. The deflection model based on the matrix displacement method, i.e. finite element method (FEM) in structural mechanics, is given. It transforms deflection equations into a matrix and is easy to calculate numerically. Simulation results for the actuator with typical dimensions are presented. Discussions are finally given. IntroductionCompared to electro-statically driven actuators, thermallydriven counterparts have got much less research. In fact, however, the thermally-driven actuators have many advantages. Their operation voltage could be set to standard IC voltage. They could be designed without close dimensional tolerances.A polysilicon thermal flexure actuator is one of the thermally driven actuators [1, 2]. Its sketch map is shown in Fig. 1. The cold arm and hot arm are usually made of polysilicon. When current passes through the arms, the hot arm would be heated to higher temperature than the cold one, which results in larger expansion of the hot arm than the cold one. The arms are jointed at the free end which forces the actuator tip to move laterally towards the cold arm side. The actuator has been widely used in microgrippers [2], optical fiber switches [3,4] and micro mechanical digital-to-analog converter [5]. In order to make the actuator operate efficiently, a finite element model (FEM) [6, 7] and analytical methods [8,9] have been used to study the actuator.The analytical methods considered only the heat conduction, which operates well under low input power. The FEM analysis has used the available software such as ANSYS for macro structure. With the development of micro-electro-mechanical system (MEMS), a CAD tool specified to MEMS is required [10]. The purpose of this paper is to develop a numerical simulation method for the polysilicon thermal flexure actuator.There are two steps to calculate the displacement of actuator tip. The first is to compute temperature distribution of all arms. An electrothermal model is presented which considers heat conduction, convection and radiation. A numerical solution is then developed to solve the equation. The second step is to calculate the deflection of the actuator. In order to incorporate the algorithm into computer programming, a matrix displacement method is used which transforms structural mechanics equations to matrix equations. There are a lot of numerical solutions available for them. The numerical results are finally given so as to compare those with the experiments. Electrothermal modelThe original electrothermal model of a polysilicon thermal flexure actuator considers only heat conduction [8,9]. In order to set up an equation including convection and radiation, a new electrothermal model has to be developed. A one-dimension model is developed here because the length size of each arm is much larger than its width and thickness size. The one-di...

“…Let's take a cell in an arm formed with the interval dx, section width w and height h. Following the principle of heat transfer [11], (1) heat conduction into the cell:…”

Section: Electrothermal Modelmentioning

confidence: 99%

“…A polysilicon thermal flexure actuator is one of the thermally driven actuators [1,2]. Its sketch map is shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of a polysilicon thermal flexure actuator

Kuang¹,

Huang²,

Lee

2002

“…The thermal microactuators are generally based on thermal expansion effects utilizing either monograph [1] or bimorph structures [2][3][4][5]. For thermally driven microactuators with lateral motion, Guckel et al [6] proposed a new flexure actuator and fabricated it using LIGA process. It is based on the asymmetrical thermal expansion of microstructures.…”

Section: Introductionmentioning

confidence: 99%

Analytical modeling and optimization for a laterally-driven polysilicon thermal actuator

Huang

Lee

1999

An electro-thermally and laterally driven microactuator is analytically examined which is based on the asymmetrical thermal expansion of the microstructure with different lengths of two beams. Deflection of the microactuator is modeled by the structural analysis. Analytical results are compared with the finite element model (FEM) results, and show a reasonable agreement. The magnitude of the deflection depends strongly on the geometry of the microactuator. The analytical model allows one to optimize efficiently the laterally driven thermal actuators.

“…A thin ®lm of gold is then electroplated. The lead/tin mask uses a sputtered Ti/Cu/Ti plating base [11]. Excellent adhesion of the photoresist to the titanium was obtained.…”

Section: X-ray Mask Fabricationmentioning

confidence: 99%

Large area, cost effective X-ray masks for high energy photons

Fischer

Chaudhuri

Stiers

et al. 2000

The cost effectiveness of the deep X-ray lithography and electrodeposition process, LIGA, depends directly on the throughput of the process. The use of high energy photons allows the exposure of stacked photoresist and results in high throughput. High energy X-ray exposures require a different mask than low energy X-ray exposures. The high energy mask allows a large area exposure but requires a thicker X-ray absorber. The cost of generating high energy X-ray masks can be drastically reduced by using a thick optical photoresist process rather than an X-ray exposure process. The cost can be further reduced by using alternatives to the typical X-ray absorber, gold. High atomic weight (high Z) materials are ideal absorbers. Lead has been demonstrated as being a useable alternative as an X-ray absorber. IntroductionThe basic deep X-ray lithography and electrodeposition process creates submicron tolerance, prismatic patterned, thick photoresist. Photoresist recesses are electroplated to produce metal structures. High throughput may be obtained using one of three methods. The original process uses the resulting metal pattern as a mold in an injection molding process [1]. Electro-discharge machining [2] using precision LIGA discharge tips has recently been shown to be an excellent, cost effective method of producing precision die molds. An alternative to the injection molding process uses high energy photon exposures and stacked photoresist [3,4] to obtain high throughput without requiring the use of injection molding. Thicknesses of 10 cm of photoresist have been exposed [5] using high energy photons.Alternative methods of exposing thick resist layers have been introduced. Successive exposure and development processes using conformal masks make it possible to fabricate thick microstructures [6]. However, the process is not cost effective when compared to high energy photon exposures which produce the same result in one exposure. High energy exposures produce a higher degree of precision and cost effectiveness from sample to sample. This is due to the fact that the same mask is used on successive samples. The large expense of mask making is a one time overhead cost. Using the same mask guarantees identical patterns for all printed samples. Deep X-ray lithographyDeep X-ray lithography requires complete exposure of the unshielded area while keeping X-ray doses in the masked area low enough so that the photoresist which is shielded is not attacked in the subsequent developing process.X-ray power decays through all substances and this attenuation is given by an exponential decay law, px p o e ÀxaL W/cm 2 1where p is the X-ray power per unit area and L is called the absorption length. The absorption length is dependent on the photon energy and type of material. The absorption length for high energy photons (at 20,000 eV: L Si = 1000 lm, L PMMA = 2 cm) allows for the exposure of extremely thick photoresist (to a practical maximum of $3L) and this enables highly parallel exposures. A computer program [7] written for exposure de...