The Fabrication of Megasonic Agitated Module (MAM) for the Improved Characteristics of Wet Etching

Tae Gyu Park,Sang Sik Yang,Dong Chul Han 대한전기학회 2008 Journal of Electrical Engineering & Technology Vol.3 No.2

The MAM (Megasonic Agitated Module) has been fabricated for improving the characteristics of wet etching. The characteristics of the MAM are investigated during the wet etching with and without megasonic agitation in this paper. The adoption of the MAM has improved the characteristics of wet etching, such as the etch rate, etch uniformity, and surface roughness. Especially, the etching uniformity on the entire wafer was less than ± 1 % in both cases of Si and glass. Generally, the initial root-mean-square roughness (Rrms) of the single crystal silicon was 0.23㎚. Roughnesses of 566㎚ and 66㎚ have been achieved with magnetic stirring and ultrasonic agitation, respectively, by some researchers. In this paper, the roughness of the etched Si surface is less than 60㎚. Wet etching of silicon with megasonic agitation can maintain nearly the original surface roughness during etching. The results verified that megasonic agitation is an effective way to improve etching characteristics of the etch rate, etch uniformity, and surface roughness and that the developed micromachining system is suitable for the fabrication of devices with complex structures.

Anisotropic/Isotropic Atomic Layer Etching of Metals

Doo San Kim,Ju Eun Kim,You Jung Gill,Yun Jong Jang,Ye Eun Kim,Kyong Nam Kim,Geun Young Yeom,Dong Woo Kim 한국진공학회(ASCT) 2020 Applied Science and Convergence Technology Vol.29 No.3

To determine a suitable etching method for the fabrication of semiconductors with a few nm or less thickness, many atomic layer etching (ALE) techniques have been studied. Previously, ALE studies on silicon-based materials have been reported; however, recently, the number of ALE studies on metals have also been increasing. Metals are applied to semiconductor devices as electrodes and hard mask materials, thus, there is an increasing need for precise etching using ALE techniques. Therefore, in this brief review, recently reported ALE studies on metals will be summarized, and the ALE process results for various metals will be described for two ALE methods, namely, anisotropic ALE and isotropic ALE.

Metal-assisted chemical etching of Ge surface and its effect on photovoltaic devices

Lee, Seunghyo,Choo, Hyeokseong,Kim, Changheon,Oh, Eunseok,Seo, Dongwan,Lim, Sangwoo Elsevier 2016 APPLIED SURFACE SCIENCE - Vol.371 No.-

<P><B>Abstract</B></P> <P>Ge surfaces were etched by means of metal-assisted chemical etching (MaCE). The behavior of the MaCE reaction in diluted H<SUB>2</SUB>O<SUB>2</SUB> was compared with that of a conventional etchant of HF/H<SUB>2</SUB>O<SUB>2</SUB>/H<SUB>2</SUB>O mixture (FPM). Herein we first report that a pyramidal structure on Ge (001) can be prepared by MaCE in dilute H<SUB>2</SUB>O<SUB>2</SUB> solution, without the use of HF. Contrastingly, an octagonal trench structure was prepared by 4/5/1 FPM treatment of Ge (001) surface. This octagonal structure consisted of a square base, four large facets connected to the base, and other four small facets adjacent to the four large facets, which were considered to be (001), {110}, and {111}, respectively. The octagonal trench was formed as a result of the difference in etch rate of Ge depending on the orientation: {100}>{110}>{111}. Ge surfaces treated by MaCE exhibited improved solar cell efficiency due to their improved light absorption, which led to significant increases in the cells’ short circuit current and fill factor. The results suggest that optimized MaCE procedures can be an effective method to improve the performance of Ge-based photovoltaic devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ge surface was textured by metal-assisted chemical etching. </LI> <LI> Metal-assisted chemical etching of Ge in H<SUB>2</SUB>O<SUB>2</SUB> produced upward pyramidal structures. </LI> <LI> Metal-assisted chemical etching of Ge in HF-H<SUB>2</SUB>O<SUB>2</SUB> mixture produced octagonal trenches. </LI> <LI> Solar cell efficiency could be improved by metal-assisted chemical etching. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

트랜치 구조 및 강자성체 박막을 이용한 홀 센서의 감도 대칭성 구현

박재성(Jae-Sung Park),최채형(Chae-Hyoung Choi) 대한전자공학회 2008 電子工學會論文誌-SC (System and control) Vol.45 No.4

일반적으로 종래의 3 차원 홀 센서는 일반적으로 Bz에 대한 감도가 Bx, By에 대한 감도의 약 1/10정도에 그친다. 따라서 본 연구에서는 새로운 구조를 갖는 3 차원 홀 센서를 제안하였다. 이방성 식각을 이용하여 트랜치를 형성함으로써 감도를 약 6배 증가시켰다. 또한 자속을 집속시키기 위하여 웨이퍼 후면에 강자성체 박막을 증착시킴으로써 Bz에 대한 감도를 Bx, By에 대한 감도의 약 80%정도로 증가시켰다. 제작된 센서의 감도는 각각 361V/AㆍT, 335V/AㆍT, 그리고 286V/AㆍT로 측정되었다. 센서는 360° 회전체에 대해 사인파의 출력을 가졌다. 패키징 된 센서의 감응부의 면적은 1.2×1.2㎟이었다. 센서의 선형성은 오차가 ±3%로 우수하였다. 제작된 센서의 분해능은 약 1×10<SUP>-5</SUP>T였다. Generally, for conventional 3-D Hall sensor it is general that the sensitivity for Bz is about 1/10 compared with those for Bx or By. Therefore, in this work, we proposed 3-D Hall sensor with new structures. We have increased the sensitivity about 6 times to form the trench using anisotropic etching. And we have increased the sensitivity for the Bz by 80 % compared with those of Bx and By using deposition of the ferromagnetic thin films on the bottom surface of the wafer to concentrate the magnetic fluxes. Sensitivities of the fabricated sensor with Ni/Fe film for Bx, By, and Bz were measured as 361㎷/T, 335㎷/T, and 286㎷/T, respectively. It has also showed sine wave of Hall voltages over a 360° rotation. A packaged sensing part was 1.2×1.2㎟. The measured linearity of the sensor was within ±3% of error. Resolution of the fabricated sensor was measured by 1×10<SUP>-5</SUP>T.

화재감지용 광섬유 캔틸레버형 센서 응용 연구

김낙철(Nag-Cheol Kim),박형준(Hyoung-Jun Park) 산업기술교육훈련학회 2020 산업기술연구논문지 (JITR) Vol.25 No.4

Through sprinkler reaction time index (RTI) characterization, the lower the RTI, the faster the sprinkler reacts to fire. The optical properties of an optical fire sensor were combined with a silicon anisotropic etching-process technique to link the fire detection and sprinkler operating time. The sprinkler motion model adopted in this study with sprinkling density was three types: RTI 350, RTI 80, and RTI 80. An optical fiber cantilever-type sensor for fire detection with V-groove support was designed and manufactured. From the analysis results of measurement factors, such as the bending degree of the optical fiber cantilever-type, the frequency variation with the beam length, and the resonant frequency, the cantilever-type sensor can be used as an optical fire sensor for fire detection linking sprinkler RTI.

Megasonic wave를 이용한 실리콘 이방성 습식 식각의 특성 개선

제우성,석창길,Che Woo-Seong,Suk Chang-Gil 한국마이크로전자및패키징학회 2004 마이크로전자 및 패키징학회지 Vol.11 No.4

메가소닉파을 이용하여 KOH 용액에서의 실리콘 이방성 습식 식각의 특성들을 개선하기 위한 새로운 방법에 관한 연구를 하였다. P형 6인치 실리콘 웨이퍼를 메가소닉파를 이용한 상태와 이용하지 않은 상태에서 식각 실험을 각각 수행하여 식각 특성들을 비교하였다. 메가소닉파는 식각균일도, 표면 조도 등과 같은 습식 식각의 특성들을 개선시키는 것으로 나타났다. 메가소닉파를 이용했을 때 식각 균일도는 전체 웨이퍼 표면의 ${\pm}1\%$ 이하이며, 메가소닉파를 이용하지 않았을 때는 ${\pm}20\%$이상이다. 식각 공정에 사용한 초기의 실리콘웨이퍼의 제곱 평균 표면 조도($R_{rms}$)는 0.23 nm이다. 자기 진동과 초음파 진동을 이용한 식각에서의 평균 표면 조도는 각각 566 nm, 66 nm로 보고 되었지만, 메가소닉파를 이용하여 $37{\mu}m$ 깊이로 식각한 경우 평균 표면 조도가 1.7nm임을 실험을 통하여 검증하였다. 이러한 결과는 메가소닉파를 이용한 식각 방법이 식각 균일도, 표면 평균 조도 등과 같은 식각 특성들을 개선시키는데 효과적인 방법임을 알 수 있다. A new method to improve the wet etching characteristics is described. The anisotropic wet-etching of (100) Si with megasonic wave has been studied in KOH solution. Etching characteristics of p-type (100) 6 inch Si have been explored with and without megasonic irradiation. It has been observed that megasonic irradiation improves the characteristics of wet etching such as an etch uniformity and surface roughness. The etching uniformity on the whole wafer with and without megasonic irradiation were less than ${\pm}1\%$ and more than $20\%$, respectively. The initial root-mean-square roughness($R_{rms}$) of single crystal silicon is 0.23 nm. It has been reported that the roughnesses with magnetic stirring and ultrasonic agitation were 566 nm and 66 nm, respectively. Comparing with the results, etching with megasonic irradiation achieved the Rrms of 1.7 nm on the surface after the $37{\mu}m$ of etching depth. Wet etching of silicon with megasonic irradiation can maintain nearly the original surface roughness after etching process. The results have verified that the megasonic irradiation is an effective way to improve the etching characteristics such as etch uniformity and surface roughness.

멤브레인 구조 제작은 위한 단결정 실리콘의 이방성 습식 식각

조남인,강창민 한국반도체디스플레이기술학회 2003 한국반도체장비학회지 Vol.2 No.4

반도체 장비의 기능성과 신뢰성을 높이기 위하여 부품의 제조기술은 점차 마이크로 머신 기술을 요구하고 있다. 마이크로머신 기술 중 hot junction이 위치하는 멤브레인 구조는 각종 센서와 히터의 미세부품에서 가장 이용도가 큰 구조이다. 실험에서는 마이크로머신의 기본 구조인 멤브레인 형태를 만들기 위해 KOH 용액과 TMAH 용액으로 단결정 실리콘을 이방성 습식식각 하였다. 실험결과, 식각액의 온도와 농도, 마스크 패턴과 웨이퍼의 결정성의 일치 등을 고려해야 하며, 식각 속도는 KOH 농도 및 온도에 따라 크게 변함을 알 수 있었다. KOH 용액은 30 wt% 80~$90^{\circ}C$ 온도 범위에서 가장 좋은 특성을 나타냈다. 한편, TMAH용액이 실리콘을 식각하는 용액으로 관심을 끄는 것은 단결정에서 상대적으로 $SiO_2$ 박막을 마스크로 사용할 수 있을 뿐 아니라 $SiO_2$ 박막을 마스크로 사용할 수 있을 뿐 아니라 다른 식각액보다 찌꺼기가 적다는 장점 때문이다. 그러나, 다른 용액에 비해 가격이 고가이며 식각 속도가 낮다는 것이 실용적인 측면에서 큰 단점이다. 실험결과를 종합적으로 고려할 때 KOH 용액 농도 30wt%와 온도 $90^{\circ}C$가 마이크로머신 기술에 의한 멤브레인 구조 제작에서 적합한 공정조건이라고 할 수 있다. We have studied micro-machining technologies to fabricate parts and sensors used in the semiconductor equipment. The studies were based on the silicon integrated circuit processes, and composed of the anisotropic etching of single crystal silicon to fabricate a membrane structure for hot and cold junctions in the infrared absorber. KOH and TMAH were used as etching solutions for the anisotropic wet etching for membrane structure formation. The etching characteristic was observed for the each solution, and etching rate was measured depending upon the temperature and concentration of the etching solution. The different characteristics were observed according to pattern directions and etchant concentration. The pattern was made to incline $45^{\circ}$ on the primary flat, and optimum etching property was obtained in the case of 30 wt% and $90^{\circ}C$ of KOH etching solution for the formation of the membrane structure.

압력센서용 다이아프램 제작을 위한 TMAH/AP 식각특성

윤의중,김좌연 한국반도체디스플레이기술학회 2003 한국반도체장비학회지 Vol.2 No.4

In this paper, Si anisotropic etching characteristics of tetramethylammonium hydroxide (TMAH)/ammonium persulfate (AP) solutions were investigated to realize the optimum structure of a diaphragm for the piezoresistive pressure sensor application. Due to its low toxicity and its high compatibility with the CMOS processing, TMAH was used as Si anisotropic etchants. The variations of Si etch rate on the etching temperature, TMAH concentration, and etching time were obtained. With increasing the etching temperature and decreasing TMAH concentrations, the Si etch rate is increased while a significant non-uniformity exists on the etched surface because of formation of hillocks on the <100> surface. With the addition of AP to TMAH solution, the Si etch rate is increased and an improvement in flatness on the etching front is observed. The Si etch rate is also maximized with increasing the number of addition of AP to TMAH solution per one hour. The Si square diaphragms of 20$\mu\textrm{m}$ thickness and 100-400 $\mu\textrm{m}$ one-side length were fabricated successfully by adding AP of (5/6)g to 800 ml TMAH solution every 10 minutes.

반도체 미세공정 기술을 이용한 Hollow형 실리콘 미세바늘 어레이의 제작

金承國(Seung Kook Kim),張鍾賢(Jong-hyeon Chang),金秉玟(Byoungmin Kim),梁翔植(Sang Sik Yang),黃仁式(In Sik Hwang),朴政浩(Jungho Pak) 대한전기학회 2007 전기학회논문지 Vol.56 No.12

Hollow-type microneedle array can be used for painless, continuous and stable drug delivery through a human skin. The needles must be sharp and have sufficient length in order to penetrate the epidermis. An array of hollow-type silicon microneedles was fabricated by using deep reactive ion etching and HNA wet etching with two oxide masks. Isotropic etching was used to create tapered tips of the needles, and anisotropic etching of Bosch process was used to make the extended length and holes of microneedles. The microneedles were formed by three steps of isotropic, anisotropic, and isotropic etching in order. The holes were made by one anisotropic etching step. The fabricated microneedles have 170 ㎛ width, 40 ㎛ hole diameter and 230 ㎛ length.

이방성 에칭 첨가제 기술로 제작된 인쇄회로 열교환기의 성능 평가

김보겸(Bo Kyem Kim),류진우(Jin Woo Yoo),홍오원(O Won Hong),이동규(Dong Kyu Lee),윤석호(Seok Ho Yoon) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

A printed circuit heat exchanger (PCHE) which is a type of plate-fin heat exchanger, has been considered as an alternative heat exchanger for wide industries requirements of high efficiency and compactness. The PCHE consists of metal plates which flow channels are etched and these plates are stacked by diffusion bonding. There are many methods for etching process, and chemical etching is preferred for a precise micro channel production. But the chemical etching technology etches plates isotropically because vertical and lateral etching rate are same. To control etching rate of each direction, anisotropic etching inhibitor method is suggested. These technology decrease the lateral etching speed by coating the channel wall. In addition, the rib length can be reduced, and the number of flow channels in the same plate area may increase. In this study, we compared the heat transfer performance of lab-scale PCHE which produced by the anisotropic etching inhibitor method and original ones by using water as working fluid. As a result, the heat performance of PCHE with new etching method is higher than the original ones.