Abstract:
A method for anodizing silicon substrate includes forming an n-type silicon embedded layer (21) made of n-type silicon on a predetermined area of a first surface of the p-type single crystal silicon substrate (2). N-type silicon layers (4, 6) are formed on the upper surface of the p-type single crystal silicon substrate (2) and on the n-type silicon embedded layer (21). Silicon diffusion layers (5, 7) containing high-concentration p-type impurities are formed on predetermined areas of the n-type silicon layers (4, 6) to contact the n-type silicon embedded layer (21). An electrode layer (13) is formed on the lower surface of the p-type silicon substrate (2). The anode of a DC power source (15) is connected to the electrode layer (13), and the cathode is connected to a counter electrode (23), which is opposed to the p-type silicon substrate (2). A current is intensively applied to an area corresponding to an opening (21a) of the n-type silicon layer (4) in a direction from the lower surface to the upper surface of the p-type single crystal silicon substrate (2), which makes the area porous.
Abstract:
A novel porous film is disclosed comprising a network of silicon columns in a continuous void which may be fabricated using high density plasma deposition at low temperatures, i.e., less than about 250° C. This silicon film is a two-dimensional nano-sized array of rodlike columns. This void-column morphology can be controlled with deposition conditions and the porosity can be varied up to 90%. The simultaneous use of low temperature deposition and etching in the plasma approach utilized, allows for the unique opportunity of obtaining columnar structure, a continuous void, and polycrystalline column composition at the same time. Unique devices may be fabricated using this porous continuous film by plasma deposition of this film on a glass, metal foil, insulator or plastic substrates.
Abstract:
A native oxide film is formed on the surface of a silicon substrate. The native oxide film has at least island-shaped imperfect SiO.sub.2 regions not formed with a perfect SiO.sub.2 film. Before the native oxide film is formed, a mask layer having a necessary opening is formed over the silicon substrate, according to necessity. The silicon substrate is etched in a vapor phase via the imperfect SiO.sub.2 regions of the native oxide film to form a hollow under the native oxide film at least at a partial region thereof. An upper film is formed on the native oxide film to cover and close the imperfect SiO.sub.2 regions. In this manner, a minute hollow can be formed in the silicon substrate with good controllability.
Abstract:
The invention shows a doping method that can be used for doping of wafers. The method comprises making at least one ensemble of pores into a wafer matrix to be doped, depositing a vehicle layer on the substrate area of at least one said ensemble of pores and/or their walls, to form a vehicle layer as an interfacing surface for the dopant passage by diffusion. The deposition is followed by annealing said wafer in annealing specific conditions for enhancement of diffusion of said dopant from said vehicle layer via said interfacing surface into the wafer matrix to be doped. After the diffusion enhancement by annealing, the method comprises washing the vehicle layer away, by a washing agent for removal of the deposited dopant comprising material from the wafer surface and the pores. The doped porous structure of the wafer matrix comprising the dopant is then recrystallized, in a recrystallizing environment defined by recrystallizing parameters. The surface is finished and polished.
Abstract:
This disclosure enables high-productivity controlled fabrication of uniform porous semiconductor layers (made of single layer or multi-layer porous semiconductors such as porous silicon, comprising single porosity or multi-porosity layers). Some applications include fabrication of MEMS separation and sacrificial layers for die detachment and MEMS device fabrication, membrane formation and shallow trench isolation (STI) porous silicon (using porous silicon formation with an optimal porosity and its subsequent oxidation). Further, this disclosure is applicable to the general fields of photovoltaics, MEMS, including sensors and actuators, stand-alone, or integrated with integrated semiconductor microelectronics, semiconductor microelectronics chips and optoelectronics.
Abstract:
The invention proposes a particularly simple, cost-effective method for producing a micromechanical membrane structure with access from the rear of the substrate. Said method is based on a p-doped Si substrate (1) and comprises the following process steps: n-doping of at least one continuous lattice-type region (2) of the substrate surface; porous etching of a substrate region (5) below the n-doped lattice structure (2); creation of a cavity (7) in said substrate region (5) below the n-doped lattice structure (2); growing of a first monocrystalline silicon epitaxial layer (8) on the n-doped lattice structure (2). The invention is characterised in that at least one opening (6) in the n-doped lattice structure (2) is dimensioned in such a way that it is not closed by the growing first epitaxial layer (8) and instead forms an access opening (9) to the cavity (7); an oxide layer (10) is created on the cavity wall; A rear face access (13) to the cavity (7) is created, the oxide layer (10) acting as an etch stop layer; and the oxide layer (10) is removed in the region of the cavity (7) producing a rear face access (13) to the membrane structure (14) lying above the cavity (7).
Abstract:
The present invention proposes a method for producing a micromechanical membrane structure (11) having a fixed counter element (12), which starts from a p-doped silicon substrate (1). Said method comprises the following processing steps: n-doping of at least one coherent latticed area (2) of the substrate surface; (Figure 1a) porous etching of a substrate area (3) below the n-doped lattice structure (2); (Figures 1b-c) oxidation of the porous silicon; (Figure 1d) generating at least one sacrificial layer (5) above the n-doped lattice structure (2); (Figure 1e) depositing and structuring at least one thick epitaxial layer (7); (Figures 1f-g) removing the sacrificial layer (5) between the thick epitaxial layer (7) and the n-doped lattice structure (2) and generating a cavity (10) in the silicon substrate (1) below the n-doped lattice structure (2) by removing the oxidized porous silicon (oxPorSi); (Figure 1h) so that the exposed n-doped lattice structure (2) forms a membrane structure (11) and at least one fixed counter element (12) is implemented in the structured thick epitaxial layer (7).
Abstract:
Mit der vorliegenden Erfindung wird ein besonders einfaches und kostengünstiges Verfahren zur Herstellung einer mikromechanischen Membranstruktur mit Zugang von der Substratrückseite vorgeschlagen. Dieses Verfahren geht von einem p-dotierten Si-Substrat (1) ausgeht und umfasst die folgenden Prozessschritte: n-Dotierung mindestens eines zusammenhängenden gitterförmigen Bereichs (2) der Substratoberfläche, porös Ätzen eines Substratbereichs (5) unterhalb der n-dotierten Gitterstruktur (2), Erzeugen einer Kaverne (7) in diesem Substratbereich (5) unterhalb der n-dotierten Gitterstruktur (2); Aufwachsen einer ersten monokristallinen Silizium-Epitaxieschicht (8) auf der n-dotierten Gitterstruktur (2). Es ist dadurch gekennzeichnet, dass mindestens eine Öffnung (6) der n-dotierten Gitterstruktur (2) so dimensioniert wird, dass sie durch die aufwachsende erste Epitaxieschicht (8) nicht verschlossen wird sondern eine Zugangsöffnung (9) zu der Kaverne (7) bildet; dass auf der Kavernenwandung eine Oxidschicht (10) erzeugt wird; dass ein Rückseitenzugang (13) zur Kaverne (7) erzeugt wird, wobei die Oxidschicht (10) auf der Kavernenwandung als Ätzstoppschicht dient; und dass die Oxidschicht (10) im Bereich der Kaverne (7) entfernt wird, so dass ein Rückseitenzugang (13) zu der über der Kaverne (7) ausgebildeten Membranstruktur (14) entsteht.
Abstract:
Es wird ein Verfahren zur Herstellung von porösen, auf einem Siliziumsubstrat (5) in einem Array angeordneten Mikronadeln (10) zur transdermalen Verabreichung von Medikamenten und ihre Verwendung vorgestellt. Das Verfahren umfasst: Bereitstellen eines Siliziumsubstrates (5), Aufbringen einer ersten Ätzmaske, Strukturieren von Mikronadeln (10) mittels eines DRIE-Prozesses (,,deep reactive ion etching"), Entfernen der ersten Ätzmaske, zumindest teilweises Porosifizieren des Si-Substrates (5), wobei die Porosifizierung auf der Vorderseite (15) des Si-Substrates (5) beginnt und poröses Reservoir gebildet wird.
Abstract:
A microelectromechanical device (MEMS) utilizing a porous electrode surface for reducing stiction is disclosed. In one embodiment, a microelectromechanical device is an interferometric modulator 80 that includes a transparent electrode 81 having a first surface 81a; and a movable reflective electrode 82 with a second surface 82a facing the first surface 81a. The movable reflective electrode 82 is movable between a relaxed and actuated (collapsed) position. An aluminum layer is provided on either the first or second surface. The aluminum layer is then anodized to provide an aluminum oxide layer 83 which has a porous surface 83a. The porous surface 83a, in the actuated position, decreases contact area between the electrodes 81 and 82, thus reducing stiction.