Laser-Assisted Microtechnology

Laser-Assisted Microtechnology introduces the principles and techniques of laser-assisted microtechnology with emphasis on micromachining of thin films, microprocessing of materials, maskless laser micropatterning and laser-assisted synthesis of thin-film systems. The experimental and theoretical physico-chemical basis of every technological process is presented in detail. On the basis of some characteristic examples of applications, the capabilities of the technological methods as well as the optimum conditions for their realization are discussed. In this second edition, besides the actualization of the literature, a new chapter concerning the laser-assisted wet chemical micro etching, has been added. This is a new method for direct 3D-micro structuring of solids, with a number of potential applications.

1. Introduction.- 1.1 Laser-Assisted Thin-Film Micromachining.- 1.2 Laser-Assisted Microprocessing and Modification of Materials..- 1.3 Laser Micropatterning.- 1.4 Pulsed Laser-Plasma Deposition of Thin Films.- 2. Laser-Based Equipment for Microtechnology.- 2.1 Principal Design of Laser-Based Microtechnological Equipment.- 2.2 Lasers Used in Microtechnological Systems.- 2.2.1 Lasers for Thin-Film Machining.- 2.2.2 Lasers for Microwelding and Microshaping.- 2.2.3 Lasers for Microlithography (Micropatterning).- 2.3 Optical Arrangement of the Energy Beam Line.- 2.3.1 The Beam-Contour (Focusing) Technique.- 2.3.2 The Projection Technique.- 2.3.3 The Contour-Projection Technique.- 2.3.4 The Active Projection Technique.- 2.3.5 Remarks on the Role of Light Coherence.- 2.4 Laser-Beam Trajectory Control.- 2.5 Optical Arrangement of the Visual Channel.- 3. Laser Micromachining of Thin Films.- 3.1 Physics of Laser-Induced Thin-Film Treatment.- 3.1.1 Film Heating Under the Action of Laser Radiation.- a) Absorption and Transformation of Beam Energy.- b) Film Temperature.- c) Heat Transfer to the Substrate.- d) Lateral Heat Transfer (in the Film).- e) Film-to-Substrate Adhesion.- f) Heating Non-Uniformity Along the Film Thickness.- g) Transverse Non-Uniformity of the Light-Beam Intensity Distribution.- h) Temperature Dependence of the Absorbance.- i) Temporal Variations of the Light Flux Density.- j) Cooling of Thin Films.- 3.1.2 Film Removal Under the Action of Laser Radiation.- a) Qualitative Discussion.- b) Theoretical Analysis of the Removal Process.- c) Phenomenological Two-Phase Removal Model.- d) Experimental Investigation of TAF Removal Process..- 3.2 Accuracy and Quality of Laser Thin-Film Micromachining.- 3.2.1 Thermal Distortions.- 3.2.2 Hydrodynamic Distortions.- 3.2.3 Changes of Substrate Properties During Laser Thin Film Treatment.- a) Sources of Cracks Formation.- b) Melting of the Substrate Surface Layers.- 3.3 Technological Processes in Laser Thin-Film Machining.- 3.3.1 Trimming of Thin Film Components.- a) Parameter Trimming and Repair of Hybrid Integrated Circuits.- b) Tuning of Quartz Piezoelements.- c) Functional Trimming of Thin Film Circuits.- 3.3.2 Shaping of Thin Films.- a) Photomask Repair.- b) Preparation of Passive Film Circuits.- c) Micromarking of Film Components.- 3.3.3 Information Recording by a Laser.- a) Digital Disc Information Recording.- b) Analog Data Recording.- 4. Local Laser-Induced Heat Treatment.- 4.1 Laser Heating of Absorbing Materials.- 4.1.1 Overall Characteristics of the Non-Demaging Heating..- 4.1.2 Excitation of Surface Electromagnetic Waves and Formation of Periodic Surface Structures.- 4.2 Applications of Laser Heating.- 4.2.1 Laser-Assisted Hardening.- 4.2.2 Local Laser Alloying.- 4.2.3 Local Laser-Induced Synthesis of Compounds.- 4.2.4 Laser Annealing of Ion-Implanted Semiconductors.- a) Characteristics of Laser Annealing.- b) Mechanisms of Laser Annealing.- c) Laser Annealing Capabilities as Compared with Other Methods.- 5. Laser Melting and Microwelding.- 5.1 Characteristics of the Laser-Induced Melting Process.- 5.2 Laser-Spot Microwelding.- 5.2.1 Wire Welding.- 5.2.2 Wire Welding to Contact Plates.- 5.2.3 Wire Welding to Thin Films.- 5.2.4 Welding of Thin Sheets.- 5.2.5 Laser Melt-Alloying of Metal-to-Semiconductor Contacts.- 5.3 Laser Seam-Welding.- 5.4 Factors Affecting the Laser-Welding Results.- 6. Laser Microshaping.- 6.1 Laser Hole-Drilling.- 6.1.1 The Process of Material Removal in Lase`r Hole-Drilling.- 6.1.2 Relationships for the Hole Formation in `Absorbing Media.- 6.1.3 Accuracy and Reproducibility in Single Laser-Pulse Hole-Drilling.- a) Using a Pulse of Predetermined Shape and Structure.- b) Using the Projection Technique.- c) Processing in a Cylinidrical Light Tube.- d) Additional Means and Procedures Increasing the Treatment Precision..- e) Multiple-Pulse Hole Drilling.- 6.2 Laser-Driven Materials Separation.- 6.2.1 Laser Cutting.- 6.2.2 Laser Scribing.- 6.2.3 Laser Thermal Cleaving.- 7. Maskless Laser Micropatterning.- 7.1 Thermochemical Methods for Laser Patterning.- 7.1.1 Laser-Induced Oxidation of Thin Metal Films.- a) Oxidation Lithography. Accuracy and Resolution.- b) Application of Oxidation Lithography.- 7.1.2 Laser-Induced Reduction of Metal Oxides.- 7.1.3 Laser-Induced Thermal Decomposition of Organometallic Compounds.- a) Thermal Decomposition of Solid-Phase OMC.- b) Thermal Decomposition of Gas-Phase OMC.- 7.1.4 Laser-Induced Liquid-Phase Electrochemical Deposition and Etching.- a) Deposition.- b) Etching.- 7.1.5 Thermochemical Action of Laser Radiation on Polymer Materials.- 7.2 Photochemical Methods of Laser Patterning.- 7.2.1 Laser-Induced Photo-Decomposition of Gas-Phase Organometallic Compounds.- 7.2.2 Selective Laser-Assisted Photo-Etching.- 8. Pulsed Laser-Plasma Deposition of Thin Films, and Film Structures.- 8.1 Essentials of the Pulsed-Laser Plasma-Deposition Technique.- 8.2 Characteristics of the Pulsed-Laser Plasma-Deposition Process.- 8.2.1 Laser Radiation Interaction with the Target.- a) Free-Running Mode.- b) Q-Switched Mode.- 8.2.2 Inertial Expension of Laser-Ablation Products.- 8.2.3 Plasma-Substrate Interaction.- 8.2.4 Growth Mechanism and Film Properties.- 8.3 Typical Applications of the Pulsed-Laser Plasma-Deposition Method.- a) Deposition of Metals.- b) Synthesis of Polycomponent Thin Films.- c) Laser-Plasma Deposition of Multilayer Structures.- References.