Laser Induced Plasma Deposition Technique And Its Application

Laser has played a very important role in scientific research and industrial production because of its high brightness,good directivity,high peak power and small spot size.In recent years,laser induced deposition technology has attracted more and more attention,and has been widely used in the fields of thin film fabrication,micro device fabrication,circuit repair,and so on.Laser induced plasma deposition technique is one of the most important research area of laser induced deposition technology.It has huge application prospects because of its advantages of simple process,high flexibility,easy realization,etc.In this thesis,two inexpensive,easily-maintained and high-efficiency lasers,i.e.,nanosecond pulsed lasers with a wavelength of 355nm and nanosecond pulsed lasers with a wavelength of 1064nm,were used to deposit copper materials on the surface of silicate glass.The influences of laser processing parameters including energy density(fluence),scan speed,defocus,number of processing,spot overlap,etc.on the deposition results were explored.The deposition fluence thresholds of ultraviolet(UV)laser and infrared(IR)laser were determined by laser induced plasma deposition of single copper line.When the UV laser energy density reached 8J/cm~2 and the IR laser energy density reached 12.5J/cm~2,obvious deposition phenomena were observed.In addition,laser scan speed,defocus,number of processing,etc.had a significant effect on the line width and morphology of the deposited lines,and the variation trend of the line width from the two lasers was similar.In the fabrication of large-area copper layer,the variations of the morphology,deposition thickness and surface roughness of the copper deposition layer under different lasers and laser parameters were investigated.Here,laser spot overlap was found to be an important factor.If the spot overlap was too high,the deposition of copper would fail.Therefore,the spot overlap of the UV laser was limited in the range of-20%to 50%,and that of the IR laser was in the range of-20%to 40%.In these ranges,with the increase of the spot overlap,the morphology of the copper deposition layer changed from pit erosion to horizontal groove.For IR laser,the copper particles were accumulated on the glass surface.The thickness and surface roughness of copper deposition layer under the irradiation of two lasers increased first and then decreased.The X-ray diffraction(XRD)analysis of the copper deposition layer and the analysis of the structure and properties of the glass surface showed that,during the laser induced plasma deposition,no observable oxidation of the copper deposition layer occurred,and the element copper might diffuse into the interior of the glass.Additionally,it was found that the UV laser had a stronger etching effect on the glass.The further study on the copper layer by laser induced plasma deposition showed that the copper deposition layer could serve as a catalytically active center for electroless copper plating.However,the adhesion of the copper layer was poor because most of the copper particles attached to the surface of glass and the surface roughness of the glass was too small.Therefore,in the current situation,this technique was only suitable for the application of lower-adhesion-strength copper layer.This technique,combined with computer and numerical control machine,could easily realize the fabrication of complex patterns,text,drawing pictures,color marks,etc.