High-aspect-ratio patterning by ClF3-Ar neutral cluster etching

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• The reactive gas cluster injection process is an etching method that uses a neutral cluster beam without plasma. This process can avoid damage caused by energetic ion irradiation and vacuum UV light from plasma. The characteristics of etching by ClF3–Ar gas cluster injection were investigated at various target distances, pattern widths, and sample temperatures. As a result, the relationship between the etching conditions and the aspect ratio was clarified, and an equation that can predict the maximum limit of aspect ratio was derived from the ClF3 flux and pattern widths. Then high aspect etching with an aspect ratio exceeding 20 is realized. And also, 3D lever structure of 6 layers can be fabricated by double-angled etching with neutral cluster injection at the condition for high aspect etching.

Section: Introductionmentioning

confidence: 99%

High aspect (>20) etching with reactive gas cluster injection

SEKI¹,

Yamamoto²,

Koike³

et al. 2022

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“…27,28) The beam is capable of high-aspectratio etching at feature sizes of less than 100 nm. 29) To increase the Si processing area, a reactive gas cluster injection system with a scanning function was developed. 30) When etching was performed with scanning, the aspect ratio decreased because of the etching of the side walls by the gas retained in the trench.…”

Section: Introductionmentioning

confidence: 99%

Angled etching of Si by ClF₃–Ar gas cluster injection

Seki

Yamamoto

Kozawa

et al. 2017

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Reactive gas cluster injection is an etching method that uses a neutral cluster beam without ions. This process can avoid damage caused by energetic ion irradiation and vacuum UV light from plasma. ClF 3 -Ar gas cluster injection was performed using a nozzle placed at various angles in the range of 0-78°from the normal to the sample. The Si substrate was anisotropically etched in the direction of the cluster beam, although the incident angle of the cluster beam was oblique. Oblique holes of 100 nm diameter and oblique square pillars of 3 µm width were fabricated with a high aspect ratio by angled cluster injection. It is expected that this process will create unprecedented structures for use in micro-electromechanical systems (MEMSs) or photonic crystals.

“…Therefore, the reactive gas cluster injection process can achieve anisotropic etching with high speed, high selectivity, high precision, and low damage. [14][15][16] However, the diameter of the etching area with a neutral cluster beam is typically a few mm, which corresponds to the beam diameter. The wafer size for Si device processing is generally more than 4 inch, and in the minimal fab, which is a new semiconductor manufacturing system, the minimal wafer size is half an inch.…”

Section: Introductionmentioning

confidence: 99%

Reactive etching by ClF₃–Ar neutral cluster beam with scanning

Seki

Senoo²,

Koike³

et al. 2016

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A reactive gas cluster injection system with a scanning function was developed in order to increase the processing area. High-precision anisotropic etching with an aspect ratio of 7 was achieved for ClF3 cluster etching without scanning. However, with scanning, the aspect ratio for etching decreased to 1.5 because the side walls were etched by the gas retained in the trench. By reducing the source gas pressure, increasing the target distance, and mixing He in the source gas, anisotropic etching with an aspect ratio of about 6.3 was achieved with this apparatus.