Abstract
Abstract—Buffered hydrofluoric (BHF) acid was used in a TFT manufacturing process as a typical wet chemical agent. Hazing of an LCD glass substrate surface was sometimes observed after BHF chemical treatment during manufacturing. The haze consists of many micro‐sized hillocks on the substrate surface. This paper describes the formation and suppression mechanism of a typical LCD glass substrate made of Corning code 1737 glass. The hillocks were observed on an etched glass surface when NH4F was added with HF as the buffered solution. Among the reaction products, ammonium‐based crystals were partially soluble in the etching solution. These ammonium‐based crystals were formed during BHF etching by masking an area of glass surface until the crystals were dissolved in the etching solution. In addition, hillocks composed of glass substrate material were detected on the masked area. The hillock density contour as the function of HF and NH4F concentration was drawn for an etching rate of from about 0.03 to 0.13 μm/min. Hazing was effectively suppressed by dilution or agitation of BHF.
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