Potassium Hydroxide Etching

The reaction channels were made in silicon by several photolithographic steps, followed by potassium hydroxide etching [13,14]. Silicon oxide was thermally grovm over the silicon. Nickel thin films were vapor-deposited. Pyrex was anodically bonded to such a modified micro structured silicon wafer. 

The dual-channel reactor is a silicon chip device and was manufactured by photolithography and potassium hydroxide etching [274]. Silicon oxide was thermally grown on silicon and thin films of nickel were evaporated for passivation because direct fluorination was carried out in this device. Pyrex was bonded anodically to the modified microstructured silicon wafer (see Figure 4.34, top). 

C. Nital is perhaps the most common etchant and stain for silicates and improves with age. Nital is 1.5 mL of nitric acid (HNO ) in 100 mL of ethyl, methyl, isopropyl, or amyl alcohol. The author routinely uses asolution of 1 mL of HNOj and 99 mL of anhydrous isopropyl alcohol. The solution quickly reacts in 6 to 10 seconds with alite and belite. At a 0.05% dilution the reaction time is 20 to 40 seconds. Ono (1995) relates alite reactivity to color produced with 0.2% nital. Depending on the relative reactivity of silicates, alite normally turns blue to green, belite is brown to blue—both silicates showing details of internal structure. Nital superimposed on a 20-second potassium hydroxide etch turns C3A light brown and colors the silicates. 

Anisotropic Etching, Fig. 1 Example of a masked silicon wafer with a (111) surface orientation (a) before, (b) during, (c) and after exposure to a potassium hydroxide etch... 

KOH Potassium hydroxide etch, silicon wet etching method... 

The steam reformer is a serpentine channel with a channel width of 1000 fim and depth of 230 fim (Figure 15). Four reformers were fabricated per single 100 mm silicon wafer polished on both sides. In the procedure employed to fabricate the reactors, plasma enhanced chemical vapor deposition (PECVD) was used to deposit silicon nitride, an etch stop for a silicon wet etch later in the process, on both sides of the wafer. Next, the desired pattern was transferred to the back of the wafer using photolithography, and the silicon nitride was plasma etched. Potassium hydroxide was then used to etch the exposed silicon to the desired depth. Copper, approximately 33 nm thick, which was used as the reforming catalyst, was then deposited by sputter deposition. The reactor inlet was made by etching a 1 mm hole into the end... 

The micro channel system was fabricated by standard silicon micromachining via etching of a silicon wafer with potassium hydroxide using thermal oxide as an etch mask [6], The double mixing tee configuration consists of six micro channels. For fluid connection, an outlet hole was drilled into the silicon chip. The chip was anodically bonded to a glass slide with three inlet holes, clamped in a holder and, thereby, connected to a commercially available quench-flow instrument... 

Measurements. The morphology of the blends was studied by optical microscopy (Leitz Dialux Pol), transmission electron microscopy (Jeol 100 U), and scanning electron microscopy (Cambridge MK II). Ultramicrotome sections were made with an LKB Ultratome III. Samples for scanning electron microscopy were obtained by fracturing sheets at low temperature. The fracture surfaces were etched with a 30% potassium hydroxide solution to hydrolyse the polycarbonate phase. Stress-relaxation and tensile stress-strain experiments were performed with an Instron testing machine equipped with a thermostatic chamber. Relaxation measurements were carried out in flexion (E > 108 dyn/cm2) or in traction (E < 108 dyn/cm2). Prior to each experiment, the samples were annealed to obtain volumetric equilibrium. 

Abrasion -1- etching in potassium hydroxide and potassium ferricyanide 3.0-3.4 1.75-2.0... 

Potassium Hydroxide Silicone Oils etch A3 70 200 0.021 30 8 5 <2 <2 100 >=95 O Hoechst Cei. Vectra C8T0 10% gl7m1n. plaiebie grade Moechst Cel. Vectra A350... 

Figure 10-3 illustrates how the angles of etching can be controlled using an anisotropic etchant. The most widely used anisotropic etchant is potassium hydroxide (KOH). Most etchants will not etch impure silicon at the same rate as pure silicon this fact can be used to the advantage of the... 

A planar substrate, such as silicon wafer, could be micromachined by a sequence of deposition and etching processes. This results in three-dimensional microstructures which can be implemented in cavities, grooves, holes, diaphragms, cantilever beams etc. The process referred to as silicon micromachining often employs anisotropic etchants such as potassium hydroxide and ethylene diamine pyrocatechol. The crystallographic orientation is important as the above-mentioned etchants show an etch-rate anisotropy. The ratio for the (100)-, (110)- and (111)- planes is typically 100 16 1. The technique of electrochemical etch stop could be applied for control of the microstructural dimensions. An alternative... 

The experimental preparation procedure consists of the application of periodic potential routines to pure metal wires that were previously chemically etched to achieve a polished surface before immersion in the electrolyte solution. The most common electrolyte solutions that can be employed are diluted or high concentrated sodium or potassium hydroxide. 

In the same years, new methods to fabricate open microchannel structures in silicon or glass substrate using various etching techniques were developed, such as reactive ion etching, hydrofluoric acid, or potassium hydroxide wet etching. 

Tips are normally made of thin metal wires (ca. 0.25 mm), such as tungsten, platinum, or alloys (such as platinum-iridium and platinum-rhodium). Gold and silver tips can also be useful in some systems. To obtain the desired high resolution of the STM. it is necessary to have a very sharp tip with which to acquire the images. Tips can be prepared electrocheinically by etching the metal in a convenient solution, such as potassium hydroxide for W or basic aqueous cyanide solution for Pt-Ir tips. They can also be... 

A staining procedure for calcium fluoroaluminate (rare in normal clinker) was developed by microsco-pists in the 1960s at the PC A laboratories. It is based on the slightly different activities of C A and CjjA CaF. A polished surface of clinker, etched for 3 seconds in distilled water with a pH of 6.5 to 7.0, reveals C A as a bluish color. The surface is then given a second polish and a 30-second etch with a 0.1-molar potassium hydroxide solution that reveals CjjA CaF as a deep brownish-purple hue. Comments on each of these etches follow. 

B. Potassium hydroxide is used for detection of fluoroaluminate. The section surface should be repolished after the water etch. The freshly polished clinker surface is then exposed to 0.1-molar potassium hydroxide solution for 30 seconds. The fluoroaluminate compound is identified by the definitive brownish purple interference color that is deeper in hue and sharper in outline than the one that, as mentioned, is sometimes visible after the 30 second distilled water etch. 

Bosch process Deep reactive-ion etching (DRIE) Etching single crystalline materials Physical-chemical etching Potassium hydroxide (KOH) etching Silicon etching... 

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