A kind of tmah series anisotropic silicon etchant and preparation method thereof

Abstract

The invention relates to a TMAH series anisotropic silicon etching solution and a preparation method thereof. The etching solution comprises 18-25% by weight of electronic grade tetramethylammonium hydroxide, 3-10% by weight of electronic grade tetraethyl hydrogen Ammonium oxide, 1.3-2.8% by weight of additives, 0.01-0.2% by weight of surfactants and the remaining components of high-purity water, the sum of the above-mentioned parts by weight is 100%, wherein the additives include 1-2% by weight of volatile agents and 0.3-0.8% by weight of a catalyst, the catalyst includes 0.1-0.3% by weight of a catalyst for adjusting the etching rate, and 0.2-0.5% by weight of a catalyst for improving the smoothness of the silicon surface. The preparation method comprises adding electronic-grade tetramethylammonium hydroxide into a mixing tank, adding electronic-grade tetraethylammonium hydroxide, additives, surfactants and the rest of water under constant stirring, and circulating and filtering for more than 3 hours. The TMAH series anisotropic silicon etchant prepared by the invention has better etching fineness, etching rate and surface smoothness of the silicon chip after etching.

Description

technical field [0001] The invention relates to the field of semiconductor material etching, in particular to a TMAH-based anisotropic silicon etching solution and a preparation method thereof. Background technique [0002] With the development of information society, micromachining technology is more and more widely used in microelectromechanical systems (MEMS). Bulk silicon processing technology generally refers to the micromachining of quasi-three-dimensional structure of bulk silicon by using etching technology. Among them, the anisotropic etching technology of bulk silicon is one of the main technologies of micromachining technology. It is widely used in processing various A variety of microstructures such as groove structures (cavities with or without membranes), protruding structures (tips of pyramids, mesa structures), cavity structures to pyramids, and cantilever structures have also been used in recent years. Fabrication of various nanostructures. Generally, anis...

AI Technical Summary

Problems solved by technology

Alkaline silicon etchant can etch silicon wafers anisotropically. Compared with inorganic alkali, organic alkali has the advantage of not introducing metal ions, but at the same time it will reduce the etching speed of silicon, and at the same time, the reaction between silicon and alkali will generate gas If the gas stays on the surface of the silicon wafer for a long time, it will easily cause uneven etching of the silicon wafer and poor flatness of the silicon wafer

On the other hand, organic alkali silicon etchant has poor wettability with the surface of silicon wafer, which is easy to cause uneven etching, poor fineness and high surface roughness.

Furthermore, the organic base has a large difference in etching speed for different surfaces of silicon, and hillocks are easily formed on the surface during the etching process, thereby reducing the flatness.

However, the silicon etching solution described in the above-mentioned patents only solves some problems in a targeted manner, and cannot meet all the technical requirements of silicon etching.

The non-patent literature only studies the influence of some additives on the improvement of silicon etching, and cannot fully solve the above problems

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