What are the functions of phosphorous acid in chips?

Phosphorous acid has a wide range of applications in water treatment, halogen-free flame retardant production, and water-soluble fertilizer processing. Electronic-grade phosphorous acid generally has very low requirements for impurities, phosphates, and sulfates. But what role does H3PO3 play in the electronics industry, particularly in the production of chips, semiconductors, wafers, and integrated circuits? This question is likely unfamiliar to many. Below, we will provide a detailed analysis of the principles behind phosphorous acid's cleaning effects on chips.

Phosphorous acid is highly acidic. The OH- and HPO₃²⁻it contains can form chelates and precipitate with gold, copper, iron, and aluminum, preventing these metal ions from adsorbing on the surface of silicon chips and altering their conductivity. When applied to the surface of silicon chips and quenched at 800℃, phosphorus atoms integrate into the silicon lattice, forming a PSI framework that enables photoelectric conversion. Compared to traditional cleaning processes, this solution causes less damage to the silicon wafer surface, helping to improve battery conversion efficiency.

In semiconductor chip production, phosphorous acid solutions prevent copper ion oxidation, ensuring smoothness and conductivity during electroplating. In the circuit board etching process, it can act as a reducing agent and a pH adjuster, preventing oxidation of related equipment. In some HCl + hydrogen peroxide cleaning formulas, a small amount of H3PO3 is often added to enhance cleaning effectiveness. This may be due to a synergistic effect between H3PO3, hydrogen chloride, and hydrogen peroxide.

In summary, phosphorous acid works on chips primarily through its ability to reduce low-valent phosphorus and chelate other metallic impurities. It's important to note that conventional phosphorous acid should never be used in electronic packaging, semiconductor manufacturing, or chip production. Because it contains high levels of phosphates, sulfates, heavy metals, aluminum, iron, and organic matter, it not only fails to achieve a chelating cleaning effect but can also have serious adverse effects on equipment.