Abstract: A method and system for controlling a silicon nitride etching bath provides the etching bath including phosphoric acid heated to an elevated temperature. The concentration of silicon in the phosphoric acid is controlled to maintain a desired level associated with a desired silicon nitride/silicon oxide etch selectivity. Silicon concentration is measured while the silicon remains in soluble form and prior to silica precipitation. Responsive to the measuring, fresh heated phosphoric acid is added to the etching bath when necessary to maintain the desired concentration and silicon nitride:silicon oxide etch selectivity and prevent silica precipitation. The addition of fresh heated phosphoric acid enables the etching bath to remain at a steady state temperature. Atomic absorption spectroscopy may be used to monitor the silicon concentration which may be obtained by diluting a sample of phosphoric acid with cold deionized water and measuring before silica precipitation occurs.

Abstract: An apparatus for wafer cleaning includes an enclosure. A stage is within the enclosure. At least one first wall is within the enclosure, around the stage. A plate is within the enclosure and above the stage, operable to enclose a first region between the stage and the first wall. The apparatus further includes an exhauster fluidly coupled to the first region between the stage and the first wall.

Abstract: A vehicle air cleaner includes a filter material and a frame, which is formed integral around the circumferential edge of the filter material. The filter material is curved into a plurality of V-shaped air intake grooves able to let air filtered and sucked into an engine quickly and effectively. The frame has its upper edge formed with an arc-shaped current guiding surface able to smoothly guide air to move downward into the air intake grooves. The vehicle air cleaner of the invention is able to filter air effectively, avoid clogging of the filter material, and increase quantity of air sucked into the engine for carrying out complete combustion so as to lower exhaust and maintain good air quality.

Abstract: An air filter-shaping mold includes an upper and a lower mold base combined together. The upper and the lower mold base are respectively formed with plural curved separating plates. A filter material having the same shape as the separating plates is placed on the separating plates of the lower mold base for carrying out forming of an air filter, able to save labor and time in making molds and cost on material, to position the filter material precisely, to elevate production efficiency and to stabilize quality of products.