scholarly journals Laser-based Thickness Control in a Double-Side Polishing System for Silicon Wafers

Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1603
Author(s):  
Liang Zhu ◽  
Biao Mei ◽  
Weidong Zhu ◽  
Wei Li
Keyword(s):  
Feedback Control ◽  
Thickness Variation ◽  
Laser Probe ◽  
Thickness Control ◽  
B Spline ◽  
Wafer Thickness ◽  
Dsp System ◽  
Scan Data ◽  
And Control ◽  
Thickness Function

Thickness control is a critical process of automated polishing of large and thin Si wafers in the semiconductor industry. In this paper, an elaborate double-side polishing (DSP) system is demonstrated, which has a polishing unit with feedback control of wafer thickness based on the scan data of a laser probe. Firstly, the mechanical structure, as well as the signal transmission and control of the DSP system, are discussed, in which the thickness feedback control is emphasized. Then, the precise positioning of the laser probe is explored to obtain the continuous and valid scan data of the wafer thickness. After that, a B-spline model is applied for the characterization of the wafer thickness function to provide the thickness control system with credible thickness deviation information. Finally, experiments of wafer-thickness evaluation and control are conducted on the presented DSP system. With the advisable number of control points in B-spline fitting, the thickness variation can be effectively controlled in wafer polishing with the DSP system, according to the experimental results of curve fitting and the statistical analysis of the experimental data.

Development of Ultra-Precision Grinder for 300mm Wafers

2012 ◽  
Vol 565 ◽  
pp. 609-614 ◽  
Author(s):  
X.L. Zhu ◽  
Z.G. Dong ◽  
Ren Ke Kang ◽  
D.M. Guo
Keyword(s):  
Shape Control ◽  
State Of The Art ◽  
Surface Shape ◽  
Wafer Surface ◽  
Thickness Variation ◽  
Grinding Forces ◽  
Wafer Thickness ◽  
Ultra Precision ◽  
Total Thickness Variation ◽  
And Control

This study presents design of an ultra-precision wafer grinder which incorporates state-of-the-art automatic supervision and control system. The wafer grinder is characterized by wafer surface shape control, grinding forces and wafer thickness monitoring systems. The design provides a totally integrated solution to the ultra-precision grinder that is capable of grinding silicon wafers with surface roughness Ra<3 nm and total thickness variation<2µm/300mm.

Fractal analysis and control of the competition model

2016 ◽  
Vol 09 (03) ◽  
pp. 1650045 ◽  
Author(s):  
Mianmian Zhang ◽  
Yongping Zhang
Keyword(s):  
Feedback Control ◽  
Mathematical Models ◽  
Fractal Analysis ◽  
Fractal Geometry ◽  
Julia Set ◽  
Julia Sets ◽  
Competition Model ◽  
Simulation Results ◽  
Population Competition ◽  
And Control

Lotka–Volterra population competition model plays an important role in mathematical models. In this paper, Julia set of the competition model is introduced by use of the ideas and methods of Julia set in fractal geometry. Then feedback control is taken on the Julia set of the model. And synchronization of two different Julia sets of the model with different parameters is discussed, which makes one Julia set change to be another. The simulation results show the efficacy of these methods.

scholarly journals Chaos and Control in Coronary Artery System

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Yanxiang Shi
Keyword(s):  
Coronary Artery ◽  
Feedback Control ◽  
Numerical Simulations ◽  
Melnikov Method ◽  
Phase Portraits ◽  
Bifurcation Diagrams ◽  
Nonlinear Dynamical ◽  
The Road ◽  
Two Systems ◽  
And Control

Two types of coronary artery system N-type and S-type, are investigated. The threshold conditions for the occurrence of Smale horseshoe chaos are obtained by using Melnikov method. Numerical simulations including phase portraits, potential diagram, homoclinic bifurcation curve diagrams, bifurcation diagrams, and Poincaré maps not only prove the correctness of theoretical analysis but also show the interesting bifurcation diagrams and the more new complex dynamical behaviors. Numerical simulations are used to investigate the nonlinear dynamical characteristics and complexity of the two systems, revealing bifurcation forms and the road leading to chaotic motion. Finally the chaotic states of the two systems are effectively controlled by two control methods: variable feedback control and coupled feedback control.

Dynamics and control of resistive wall modes with magnetic feedback control coils: experiment and theory

2005 ◽  
Vol 45 (4) ◽  
pp. 285-293 ◽  
Author(s):  
M.E Mauel ◽  
J Bialek ◽  
A.H Boozer ◽  
C Cates ◽  
R James ◽  
...  
Keyword(s):  
Feedback Control ◽  
Dynamics And Control ◽  
Resistive Wall ◽  
And Control ◽  
Resistive Wall Modes

Controlling the Thickness Uniformity in Equal Channel Angular Rolling (ECAR)

2007 ◽  
Vol 539-543 ◽  
pp. 2872-2877 ◽  
Author(s):  
Young Hoon Chung ◽  
Jong Woo Park ◽  
Kyong Hwan Lee
Keyword(s):  
Shear Strain ◽  
Shear Deformation ◽  
Control Mechanism ◽  
Sheet Thickness ◽  
Surface Friction ◽  
Metal Sheet ◽  
Thickness Variation ◽  
Thickness Control ◽  
Thickness Uniformity ◽  
Elastic Unit

As the surface friction between feeding rolls and metal sheet generates the feeding power of ECAR, the generated feeding power is low, and the friction between the metal sheet and ECAR die should be minimized. However, for obtaining a large shear deformation by ECAR, the metal sheet should be tightly contacted with the wall of ECAR die. In this condition, the thickness of the metal sheet is continuously increased during ECAR. A new ECAR apparatus is developed for maximizing the shear deformation and obtaining sheet thickness uniformity, and succeeding continuous ECAR with such a limited feeding power. By controlling the outlet gap of the ECAR die with elastic unit, the thickness of the metal sheet is kept uniform. Detailed thickness control mechanism during the new ECAR process is analyzed. A sheet of Al 6063 alloy that is 1-pass deformed with the new ECAR apparatus shows below ±0.037 mm of thickness variation and 0.61 of shear strain.

Modeling and Control of a Rotary Crane

1985 ◽  
Vol 107 (3) ◽  
pp. 200-206 ◽  
Author(s):  
Y. Sakawa ◽  
A. Nakazumi
Keyword(s):  
Feedback Control ◽  
Equilibrium State ◽  
Open Loop ◽  
The State ◽  
Control Input ◽  
Loop Control ◽  
Modeling And Control ◽  
Control Scheme ◽  
Rotary Crane ◽  
And Control

In this paper we first derive a dynamical model for the control of a rotary crane, which makes three kinds of motion (rotation, load hoisting, and boom hoisting) simultaneously. The goal is to transfer a load to a desired place in such a way that at the end of transfer the swing of the load decays as quickly as possible. We first apply an open-loop control input to the system such that the state of the system can be transferred to a neighborhood of the equilibrium state. Then we apply a feedback control signal so that the state of the system approaches the equilibrium state as quickly as possible. The results of computer simulation prove that the open-loop plus feedback control scheme works well.

DESIGN AND ANALYSIS OF FLC AND FEEDBACK CONTROL FOR THREE FINGER GRIPPER SYSTEM

2016 ◽  
Vol 78 (10-4) ◽  
Author(s):  
Nor Anis Aneza Lokman ◽  
Hamzah Ahmad ◽  
Mohd Razali Daud
Keyword(s):  
Fuzzy Logic ◽  
Feedback Control ◽  
System Performance ◽  
Fuzzy Membership ◽  
Logic Design ◽  
Matlab Simulink ◽  
Good Grasp ◽  
Research Findings ◽  
And Control

This paper presents the fuzzy logic design and control for three finger gripper system to grasp an object. Two objectives are mainly considered in this work, which are the analysis of different membership types and the gripper performance with feedback and without feedback control to support current research findings. The comparison is also including different number of rules analysis as well as the fuzzy membership types. The simulation and analysis are carried by using MATLAB Simulink and SimMechanics toolboxes to analyze the system performance. The result shows that the gripper system with trapezoidal memberships achieved faster response and good grasp. Besides that, the proposed system with feedback has produced the best result to grasp the object with suitable torques and angles in comparison to the non-feedback gripper system.

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