A numerical study of picosecond laser micro-grooving of single crystalline germanium: Mechanism discussion and process simulation

The fabrication of micro-holes in silicon substrates that have a proper taper, higher depth-to-diameter ratio, and better surface quality has been attracting intense interest for a long time due to its importance in the semiconductor and MEMS (Micro-Electro-Mechanical System) industry. In this paper, an experimental investigation of the machining performance of the direct and chemical-assisted picosecond laser trepanning of single crystalline silicon is conducted, with a view to assess the two machining methods. The relevant parameters affecting the trepanning process are considered, employing the orthogonal experimental design scheme. It is found that the direct laser trepanning results are associated with evident thermal defects, while the chemical-assisted method is capable of machining micro-holes with negligible thermal damage. Range analysis is then carried out, and the effects of the processing parameters on the hole characteristics are amply discussed to obtain the recommended parameters. Finally, the material removal mechanisms that are involved in the two machining methods are adequately analyzed. For the chemical-assisted trepanning case, the enhanced material removal rate may be attributed to the serious mechanical effects caused by the liquid-confined plasma and cavitation bubbles, and the chemical etching effect provided by NaOH solution.

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Fabrication of Optimally Micro-Textured Copper Substrates by Plasma Printing for Plastic Mold Packaging

International Journal of Automation Technology ◽

10.20965/ijat.2020.p0200 ◽

2020 ◽

Vol 14 (2) ◽

pp. 200-207 ◽

Cited By ~ 2

Author(s):

Tatsuhiko Aizawa ◽

Yasuo Saito ◽

Hideharu Hasegawa ◽

Kenji Wasa ◽

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...

Keyword(s):

Stress Distribution ◽

Copper Substrate ◽

Three Dimensional ◽

Picosecond Laser ◽

Numerical Control ◽

Uniform Stress ◽

Element Analysis ◽

Micro Grooving ◽

Plastic Mold ◽

Screen Printed

Micro-embossing using plasma printed micro-punch was proposed to form micro-groove textures into the copper substrate for plastic packaging of hollowed GaN HEMT-chips. In particular, the micro-groove network on the copper substrate was optimized to attain uniform stress distribution with maximum stress level being as low as possible. Three-dimensional finite element analysis was employed to investigate the optimum micro-grooving texture-topology and to attain the uniform stress distribution on the joined interface between the plastic mold and the textured copper substrate. Thereafter, plasma printing was utilized to fabricate the micro-punch for micro-embossing of the micro-grooving network into the copper substrate as a designed optimum micro-texture. This plasma printing mainly consisted of three steps. Two-dimensional micro-pattern was screen-printed onto the AISI316 die surface as a negative pattern of the optimum CAD data. The screen-printed die was plasma nitrided at 673 K for 14.4 ks at 70 Pa under the hydrogen-nitrogen mixture for selective nitrogen supersaturation onto the unprinted die surfaces. A micro-punch was developed by mechanically removing the printed parts of die material. Then, fine computer numerical control (CNC) stamping was used to yield the micro-embossed copper substrate specimens. Twelve micro-textured substrates were molded into packaged specimens by plastic molding. Finally, gross leak testing was employed to evaluate the integrity of the joined interface. The takt time required to yield the micro-grooved copper substrate by the present method was compared to the picosecond laser micro-grooving; the former showed high productivity based on this parameter.

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Direct writing of large-area micro/nano-structural arrays on single crystalline germanium substrates using femtosecond lasers

Applied Physics Letters ◽

10.1063/1.4986784 ◽

2017 ◽

Vol 110 (25) ◽

pp. 251901 ◽

Cited By ~ 6

Author(s):

Lin Li ◽

Jun Wang

Keyword(s):

Femtosecond Lasers ◽

Direct Writing ◽

Large Area ◽

Single Crystalline ◽

Germanium Substrates ◽

Crystalline Germanium

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Single Crystalline Germanium-Lead Formed by Laser-Induced Epitaxy

ECS Journal of Solid State Science and Technology ◽

10.1149/2.0331606jss ◽

2016 ◽

Vol 5 (6) ◽

pp. P353-P360 ◽

Cited By ~ 4

Author(s):

Qian Zhou ◽

Edwin Bin Leong Ong ◽

Sin Leng Lim ◽

Saumitra Vajandar ◽

Thomas Osipowicz ◽

...

Keyword(s):

Single Crystalline ◽

Crystalline Germanium

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Numerical Simulation and Prediction of Surface Heterogeneity in Diamond Turning of Single-Crystalline Germanium

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.329.397 ◽

2007 ◽

Vol 329 ◽

pp. 397-402

Author(s):

Ji Wang Yan ◽

Yu Feng Fan ◽

Nobuhito Yoshihara ◽

Tsunemoto Kuriyagawa ◽

Shoji Yokoyama

Keyword(s):

Numerical Simulation ◽

Simulation Model ◽

Surface Heterogeneity ◽

Diamond Turning ◽

Tool Geometry ◽

Single Crystalline ◽

Machining Conditions ◽

Boundary Change ◽

Systems Simulation ◽

Crystalline Germanium

This paper deals with the mechanism of surface heterogeneity due to crystallographic anisotropy effects in diamond turning of single-crystalline germanium. A microplasticity-based numerical simulation model was proposed, in which the effects of tool geometry and machining conditions can be involved. Two coefficients were introduced to compensate the Schmid factors of two different types of symmetrical slip systems. Simulation of ductile machinability was conducted on two crystallographic planes (100) and (111), and the simulation results were consistent with the experimental results. It was indicated that the simulation model can be used to predict the brittle-ductile boundary change with machining conditions and crystal orientations of germanium.

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