Ram Technology, High-Purity Hydrofluoric Acid Product Mass Production Expected... Hydrofluoric Acid Production Technology Patent

Plan to Expand Production Facilities for Mass Production of Ultra-High Purity Hydrogen Fluoride

[Asia Economy Reporter Hyungsoo Park] Ram Technology, a domestic semiconductor material company, registered a patent related to the production of ultra-high purity hydrofluoric acid on the 1st of last month. The technology features refining ultra-high purity hydrofluoric acid with higher purity by improving the problems of the existing method and producing semiconductor-grade hydrofluoric acid products using it.

The existing method required various refining processes such as distillation, electrolysis, adsorption, and membrane separation using fluorite, but the production method developed by Ram Technology omits these pretreatment processes.

Impurities in hydrofluoric acid for semiconductor processes affect the semiconductor process, so technology that removes even trace impurities is required. Ram Technology aims to reduce the concentration of single metal impurities in semiconductor-grade hydrofluoric acid products to below 1 ppt through hydrofluoric acid refinement, and such hydrofluoric acid (HF) is expected to be used in various industrial fields.

The aforementioned hydrofluoric acid is the most commonly produced among fluorine compounds and is supplied in anhydrous form as hydrofluoric acid and in aqueous solution (hydrous) form containing ultrapure water.

Hydrofluoric acid is produced through various refining processes such as distillation, electrolysis, adsorption, and membrane separation using hydrofluoric acid raw materials, among which distillation using fractional distillation is widely used. Hydrofluoric acid is manufactured by adding sulfuric acid to fluorite (CaF2) and heating simultaneously.

The crude hydrofluoric acid produced through the above reaction contains various impurities such as SO2 and trace amounts of AsF3, BF3, PF5, SiF4, FeF3, SF6 in addition to hydrofluoric acid. The crude hydrofluoric acid is a raw material obtained from the reaction of fluorite and sulfuric acid and contains excess impurities (at the % level) without separate pretreatment. Using crude hydrofluoric acid significantly reduces raw material supply costs compared to conventional hydrofluoric acid, and by excluding pretreatment processes, it simplifies the process and lowers production costs.

The impurities are removed through various refining processes including pretreatment, and industrial hydrofluoric acid production is possible using hydrofluoric acid with a purity of 99.9%.

Low-purity hydrofluoric acid such as industrial hydrofluoric acid is used for industrial purposes. Ultra-high purity hydrofluoric acid is required for etching and cleaning in semiconductor and display applications. If impurities exist in hydrofluoric acid for semiconductor manufacturing processes, they remain on the wafer during etching and cleaning, causing pattern formation defects and reducing semiconductor production yield.

Ultra-high purity hydrofluoric acid is used to reduce defect rates. However, as the purity of hydrofluoric acid increases, refining costs increase, and caution is required against contamination during storage and handling. There are disadvantages such as low production efficiency and low product conversion rates to high-purity hydrofluoric acid.

Most impurities contained in hydrofluoric acid can be removed through distillation refining, but impurities such as arsenic (As) exist as arsenic trifluoride (AsF3) in anhydrous hydrofluoric acid. The impurity has a boiling point of 57.13℃, which is not much different from the boiling point of hydrofluoric acid (HF) at 19.5℃, and forms an azeotrope, making separation by distillation refining difficult.

Arsenic fluorides cause not only adverse effects on semiconductor device characteristics but also problems in equipment corrosion and environmental aspects, so it is desirable to remove them during the ultra-high purity hydrofluoric acid manufacturing process. A method has been proposed to remove arsenic fluorides in hydrofluoric acid and produce high-purity hydrofluoric acid by mixing oxidizing agent aqueous solutions such as hydrogen peroxide or potassium permanganate with hydrofluoric acid.

This method causes production loss and generates a large amount of reaction byproducts because hydrofluoric acid partially dissolves in the water of the oxidizing agent aqueous solution, and hydrofluoric acid containing moisture is much more corrosive than hydrofluoric acid. The preventive maintenance (PM) cycle of production facilities is shortened, reducing process productivity, causing process problems and safety issues related to hydrofluoric acid.

The pretreatment process for removing impurities such as arsenic is performed before the hydrofluoric acid production process from hydrofluoric acid, resulting in additional equipment and increased process costs. Even with pretreatment, residual impurities in hydrofluoric acid are not easily removed in the refining process, making it difficult to produce high-purity, especially ultra-high purity hydrofluoric acid.

The process for producing ultra-high purity hydrofluoric acid proceeds in the order of pretreatment of crude hydrofluoric acid and refining, but Ram Technology's production method excludes the pretreatment process and performs refining using crude hydrofluoric acid as raw material, developing a method to manufacture ultra-high purity hydrofluoric acid.

Ram Technology's production method is the result of extensive research to produce ultra-high purity hydrofluoric acid without pretreatment. A gas stream that oxidizes and removes impurities in crude hydrofluoric acid coexisting in gas and liquid phases inside a multi-stage distillation tower is injected. An Advanced Process Control (APC) module is applied as the injection process processor to immediately apply the refining process according to the quality of the raw crude hydrofluoric acid. Ultra-high purity hydrofluoric acid can be continuously produced with a high mass production conversion rate.

In particular, the gas stream is introduced into the first multi-stage distillation tower where crude hydrofluoric acid is introduced to minimize impurities. Even if the composition or content of impurities in crude hydrofluoric acid is inconsistent, ultra-high purity hydrofluoric acid with uniform quality can be produced with high efficiency. This method simplifies the refining process, enabling economical and efficient production of ultra-high purity hydrofluoric acid. The production method developed by Ram Technology inputs crude hydrofluoric acid as raw material, enabling 24-hour continuous refining, and presents a refining method and refining apparatus capable of producing ultra-high purity hydrofluoric acid at ppt or ppq levels through automatic control.

In the recovery unit, a device for recovering refined ultra-high purity hydrofluoric acid, the ultra-high purity hydrofluoric acid is recovered in a gaseous state after passing through the last multi-stage distillation tower or recovered in a liquefied liquid state after passing through a condenser. In other words, ultra-high purity liquid hydrofluoric acid and gaseous hydrofluoric acid, which did not exist before, are simultaneously produced. Refining of ultra-high purity hydrofluoric acid is automatically controlled by the advanced process control unit (500) to enable continuous processing.

The advanced process control unit (500) is a device including an Advanced Process Control (APC) module. The APC module is a mathematical model that simultaneously considers the dynamic relationships among many process operation variables and is a multivariable predictive control technology that maintains stable and economical optimal operating conditions.

The APC module is a technology that improves overall plant efficiency and operational convenience using software rather than plant equipment reinforcement. By controlling the refining process from crude hydrofluoric acid to ultra-high purity hydrofluoric acid with the APC module, product yield improvement and upgrade are achieved, and operating costs and giveaway are reduced.

Also, even if the quality of crude hydrofluoric acid used as raw material varies, the quality of the final ultra-high purity hydrofluoric acid can be standardized, and uniform ultra-high purity hydrofluoric acid is produced with this module. The reason uniform ultra-high purity hydrofluoric acid can be obtained is due to the multivariable predictive control technology using a computer that controls the process to maintain it more stably and economically.

Multivariable predictive control technology simultaneously considers the effects of several control variables on other controlled variables and controls the manipulated variables simultaneously to satisfy each target value of the controlled variables. It designs a gas stream appropriate for the impurity concentration, sends the measured impurity concentration to the APC module, and changes the composition and injection amount of the gas stream during first, second, and nth gas stream injections according to the set impurity concentration.

The hydrofluoric acid finally obtained can be obtained as an ultra-high purity material with uniform quality. The refining method and refining apparatus according to Ram Technology's patented production method enable continuous processing and 24-hour operation by automatic control through the APC module. It has the advantage of improving production and processing capacity of ultra-high purity hydrofluoric acid at low cost.

By using crude hydrofluoric acid manufactured by the reaction of fluorite and sulfuric acid without pretreatment of the conventional raw hydrofluoric acid, the process is simplified and pretreatment costs are reduced. Even if the composition or content of impurities in crude hydrofluoric acid is inconsistent, ultra-high purity hydrofluoric acid can be produced with high efficiency. The ultra-high purity hydrofluoric acid thus produced has minimized moisture content and excellent stability.

Ram Technology's ultra-high purity hydrofluoric acid production method features an automatic control system (APC module) compared to existing production methods, enabling the production of uniform ultra-high purity hydrofluoric acid and minimizing product defects caused by quality degradation, leading to product price competitiveness.

Ram Technology is currently promoting the expansion of a new factory in Dangjin, and upon completion, it is expected to accelerate domestic semiconductor-grade hydrofluoric acid production and gradually increase domestic market share.