Papers by Author: Zone Ching Lin

Abstract: The study mainly explores the surface profile of sapphire wafer after polishing by the method of chemical mechanical polishing (CMP). Pattern-free polishing slurry with SiO₂ abrasive particle is used to polish the sapphire wafer. This paper observes the phenomena of surface profile and surface scratches of sapphire wafer under different pressures and different rotational velocities during CMP. The study uses atomic force microscope (AFM) to scan the surface of sapphire wafer focusing on three axial lines of 0∘, 45∘and 90∘from the position of near edge passing the center of sapphire wafer. The study also selects five positions on a specific area to draw the surface profiles on the axial lines of 0∘, 45∘and 90∘. It can be observed that the central area of sapphire wafer has lower depression than other areas because the central area is polished more polishing times. Besides, the depression on the central area of sapphire wafer has a greater depression value and it has more and larger surface scratches when it is polished under a greater down force and at a faster rotational velocity.

Abstract: The paper innovatively proposes using atomic force microscopy (AFM) and the concept of specific down force energy (SDFE) to establish a method for fabricating T shape nanochannel grooves on silicon (Si) substrate. Using the single-pass multi-layer cutting method of nanochannel groove using AFM proposed by the paper, a nanochannel looked like T shape is fabricated. For fabricating T shape nanochannel, it is set that cutting is firstly carried out for one pass on each cutting layer at a fixed down force. Then the probe carries out cutting for repeated passes. Using this cutting way by AFM and SDFE theory, the cutting depth and width of each pass can be predicted. The results of simulation and experiment of fabricating method for T shape nanochannel is further compared.

Abstract: Abstract. An orthogonal cutting is a symmetric cutting thus it can be modified as a two dimensional cutting. This paper uses quasi-steady molecular statics method to carry out simulation of two dimensional nanoscale cutting copper work piece by the diamond tools. For the two dimensional quasi-steady molecular statics nanoscale cutting model used by this paper, when the cutting tool moves on a copper work piece, displacement of atoms is caused due to the effects of potential on each other. After a small distance that each atom moves is directly solved by the calculated trajectory of each atom, the concept of force balance is used. The minimum energy method is employed to carry out the search, and obtain the new movement position for each atom. Based on the simulation results, this paper studies the chip formation shape and cutting forces in x direction and y direction.

Abstract: The three-dimensional quasi-steady molecular statics nanocutting model developed by this paper carries out simulation analysis of nanocutting of sapphire substrate in order to explore the effects of tools with the same tip radii of probe and straight-line cutting at different cutting depths, on cutting force. The three-dimensional quasi-steady molecular statics nanocutting sapphire workpiece model first assumes the trajectory of each atom of the sapphire workpiecs being cut whenever the diamond cutter goes forward one step. It then uses the optimization search method to solve the force equilibrium equation of the Morse force in the X, Y and Z directions when each atom moves a small distance, so as to find the new movement position of each atom, and step by step calculates the behavior during cutting. And from the simulation results of cutting force, down force and side force, it is found that under the actions of cutting tools with the same tip radius of probe, cutting force enlarges with the increase of cutting depth. This result is identical to the actual experimental phenomena of nanocutting. From this, it is known that the simulation model developed in this study is reasonable.

Abstract: This article presents a quasi-steady molecular statics nanocutting simulation model for simulating orthogonal two dimension cutting copper materials with different point defects by using diamond cutters. The analyses of cutting action, cutting force, equivalent strain and equivalent stress are taken during nanocutting copper material with point defect. The two dimensional quasisteady molecular statics nanocutting model first assumes the trajectory of each atom of copper workpiece being cut whenever the diamond cutter goes forward one step. It then uses the Hooke- Jeeves search method to solve the force equilibrium equation of the Morse force in X and Y directions when each copper atom moves a small distance, so as to find the new movement position of each copper atom. Then, the displacement of the acquired new position of each atom combined with the concept of shape function of finite element method are employed to calculate the equivalent strain of the copper workpiece during nanocutting . By using the relationship equation of the flow stress-strain curve, the equivalent stress of the copper workpiece during cutting can also be calculated