Earticle

There has been an increase of using Bosch Process to fabricate MEMS Device, TSV, Power chip for straight etching profile. Essentially, the interest of TSV technology is rapidly floated, accordingly the demand of Bosch Process is able to hold the prominent position for straight etching of Si or another wafers. Recently, the process to prevent under etching or over etching using EPD equipment is widely used for improvement of mechanical, electrical properties of devices. As an EPD device, the OES is widely used to find accurate end point of etching. However, it is difficult to maintain the light source from view port of chamber because of contamination caused by ion conflict and byproducts in the chamber. In this study, we adapted the SPOES to avoid lose of signal and detect less open ratio under 1 %. We use 12inch Si wafer and execute the through etching 500um of thickness. Furthermore, to get the clear EPD data, we developed an algorithm to only receive the etching part without deposition part. The results showed possible to find End Point of under 1 % of open ratio etching process.

The effect of the duty cycle on the etching process and on the formation of silicon grass for different etching widths was investigated. As the duty cycle is defined as the chuck power application per second, it determines the etch rate and etching profiles. It was found that decreasing the duty cycle improves the etching profiles of the trench but it may also cause the formation of silicon grass at the bottom when the nominal width is significantly large. Therefore, for a large nominal width, lowering the duty cycle promotes the formation of silicon grass. Moreover, a large duty cycle induces undercut on the sidewall, which is deleterious to the etching profiles. Activation of the chuck power is controlled by the duty cycle and it also accelerates photo resist erosion or a bowing effect. Therefore, when the duty cycle becomes large, the etch rate is drastically enhanced. Finally, we can conclude that a low duty cycle is suitable for a Bosch process in order to prevent undesirable etching side effects, such as undercut or bowing.

본 논문은 암모니아의 친환경적 생산 기술로서 전기화학적 질산염 환원 반응(nitrate reduction reaction, NO₃RR)의 최신 연구 동향을 종합적으로 고찰한다. 기존의 하버-보쉬 공정은 고온·고압 및 화석연료 기반 수소 사용으로 인해 막대한 CO₂가 배출되는 구조적 한계를 지니고 있으며, 이에 따라 탄소중립 시대에 적합한 대체 암모니아 생산 기술 개발이 요구되고 있다. NO₃RR은 수계 오염의 주요 원인인 질산염을 제거하면서 동시에 NH₃를 생산할 수 있어 환경 정화와 자원 회수를 동시에 달성할 수 있는 장점을 갖는다. 본 리뷰에서는 먼저 하버-보쉬 공정 개발 과정과 현황에 대하여 고찰한 후, 탄소 저감 및 친환경적 암모니아 생산이 가능한 NO₃RR 반응에 대하여 정리하였다. 질산염 환원의 다전자 전달 반응 메커니즘을 정리하고, NO₃^- → NO₂^- 초기 활성화와 NH₂OH → NH₃ 최종 수소화 단계가 선택성과 반응 속도를 지배하는 주요 과정임을 고찰하였다. 이후 귀금속 기반 촉매의 표면 구조·결함·합금화 전략을 통해 NO₃RR에서 높은 패러데이 효율과 NH₃ 선택도를 나타낸 사례를 비교·분석하였다. 또한 비귀금속 촉매에서 나타나는 계면 전자 구조 조절, 산소 빈자리, 단원자 촉매 설계, 합금의 시너지 효과 등 비용 효율적이면서 고성능을 달성하기 위한 설계 전략을 정리하였다. 본 논문은 NO₃RR을 기반으로 한 전기화학적 암모니아 생산 기술이 하버-보쉬 공정을 보완하거나 대체할 잠재력을 지니고 있음을 제시하며, 향후 촉매 설계의 방향성과 실제 폐수 처리 응용으로의 확장 가능성을 제안한다.

This paper provides a comprehensive overview of the recent research trends in the electrochemical nitrate reduction reaction (NO₃RR) as an environmentally sustainable route for ammonia synthesis. The conventional Haber-Bosch process suffers from intrinsic limitations, including high-temperature and high-pressure operation requirements and reliance on fossil-fuel-derived hydrogen, resulting in substantial CO₂ emissions. Consequently, the development of alternative ammonia production technologies compatible with carbon neutrality has become imperative. NO₃RR offers both environmental remediation and resource recovery benefits by removing nitrate, a major contaminant in aquatic environments, while simultaneously producing NH₃. This review first examines the historical development and current status of the Haber-Bosch process, followed by an analysis of NO₃RR as a carbon-reducing and environmentally benign ammonia production pathway. The multi-electron transfer mechanism of nitrate reduction is summarized and the key processes governing the reaction selectivity and kinetics are the NO₃^- → NO₂^- initial activation step and the NH₂OH → NH₃ final hydrogenation step. Subsequently, catalytic systems based on noble metals are compared, focusing on how surface structure, defect engineering, and alloying strategies achieve high Faradaic efficiency and NH₃ selectivity. Non-noble metal catalysts are also discussed, emphasizing cost-effective yet high-performance design principles such as interfacial electronic modulation, oxygen vacancy engineering, single-atom catalytic sites, and synergistic alloy effects. Overall, this paper suggests that NO₃RR-based electrochemical ammonia synthesis could potentially complement or even replace the Haber-Bosch process. Lastly, future directions in catalyst design and the practical applicability of NO₃RR for wastewater treatment are proposed.

Bosch 공정의 식각 단계에서 Ar을 첨가하였을 때 Si의 식각특성을 관찰하기 위하여 식각 단계에서 $SF_6$ 플라즈마만 사용한 경우와 Ar 유속비율이 20%인 $SF_6$/Ar 플라즈마를 각각 사용하여 Si을 Bosch 공정으로 식각하였다. Bosch 공정의 식각 단계에서 $SF_6$ 플라즈마에 Ar 가스를 첨가하면 $Ar^+$ 이온에 의한 이온포격이 증가하였고 이는 Si 입자의 스퍼터링을 초래할 뿐 아니라 F 라디칼과 Si의 화학반응을 가속하였다. 그 결과 식각 단계에서 20%의 Ar이 첨가되어 Bosch 공정으로 수행된 Si의 식각속도는 Ar이 첨가되지 않은 경우보다 10% 이상 빨라졌고 식각프로파일도 더욱 비등방적이었다. 이 연구의 결과는 Bosch 공정으로 Si을 식각할 때 식각속도와 식각프로파일의 비등방성을 개선하는데 필요한 기초자료로 사용될 수 있을 것으로 판단된다.

The etch rate and etch profile of Si was investigated when Ar was added to an $SF_6$ plasma in the etch step of the Bosch process. A Si substrate was etched with the Bosch process using $SF_6$ and $SF_6$/Ar plasmas, respectively, in the etch step to analyze the effects of Ar addition on the etch characteristics of Si. When the Ar flow rate in the $SF_6$ plasma was increased, the etch rate of the Si substrate increased, had a maximum at 20% of the Ar flow rate, and then decreased. This was because the addition of Ar to the $SF_6$ plasma in the etch step of the Bosch process resulted in the bombardment of Ar ions on the Si substrate. This enhanced the chemical reactions (thus etch rates) between F radicals and Si as well as led to sputtering of Si particles. Consequently, the etch rate was higher more than 10% and the etch profile was more anisotropic when the Si substrate was etched with the Bosch process using a $SF_6$/Ar (20% of Ar flow rate) plasma during the etch step. This work revealed a feasibility to improve the etch rate and anisotropic etch profile of Si performed with the Bosch process.

이 연구는 일본 규슈 북쪽 서단(西端)에 위치한 작은 도시지만, 제1,2차 세계대전에서 구(舊)일본 해군의 군사적 요충지 역할을 맡은 군항도시 사세보(佐世保)가 관광도시로 전환되는 그 과정의 설계와 실천 과정에 기반을 두고 있다. 1983년 개장한 나가사키(長崎) ‘오란다무라(Holland Village)’는 지역경제에 많은 파급효과를 가져왔고, 1992년 개장한 ‘하우스텐보스(Huis Ten Bosch)’는 관광도시로의 전환에 있어 ‘결정체’와 같은 역할을 했다. 오랜 기간 군항도시의 역할이 지속된 사세보는 전전기(戦前期)와 전후기(戦後期)를 거치며 어두운 전쟁의 체험과 역사적 흔적을 남겼다. 하지만 사세보 시민들이 염원하던 ‘평화산업항만도시’로의 전환에 있어 결정체 역할을 한 ‘하우스텐보스’의 개장은 마치 어두운 전쟁의 역사의 흔적을 지우듯 나가사키의 역사와 문화라는 옷을 입혀 그 부지위에 자리 잡았다. 하우스텐보스가 조성된 부지는 전전기에는 해군병교 하리오(針尾)분교가, 전후기에는 인양자들의 숙소이자 인양 원호국이 자리잡고 있었던 곳이었다. 이처럼 사세보의 어두운 역사의 땅 위에 하우스텐보스가 지어지며 군항도시에서 관광도시로 전환된 과정을 흥미롭게 살펴보고자 한다.

This study is based on the design and practice of Sasebo, a military port city that served as a military hub for the former Japanese Navy in World Wars I and II, and is located in the western end of Kyushu, Japan. Nagasaki's Holland Village, which opened in 1983, had a lot of ripple effects on the local economy, and Huis Ten Bosch, which opened in 1992, played a "crystal" in the transition to a tourist city. Sasebo, where the role of a military port city continued for a long time, went through the pre-war and post-war periods, leaving behind dark war experiences and historical traces. However, the opening of "Haustenbos," which played a decisive role in the transition to a "peaceful industrial port city" that Sasebo citizens hoped for, was placed on the site by dressing up as Nagasaki's history and culture as if erasing traces of the dark history of war. The site where Haustenbos was built was the site of Hario Branch, a naval bridge, in the pre-war period, and in the post-war period, it was a lodging for the adopted children and a relief country. I would like to take an interesting look at the process of being built on such a dark land of history and converted into a tourist city.