Design And Implementation Of A Small Laser Direct Writing System

Photolithography is an important technology in the processing and manufacturing of planar semiconductor devices.Compared with the traditional mask lithography,the laser direct writing technology has the advantages of no need to mask,flexible processing and low requirement for the surface roughness.It has been used in many fields,such as integrated circuit manufacturing,material etching,diffractive optical element processing,two-dimensional material processing and so on.Besides improving the spatial resolution and efficiency of laser direct writing,enriching its function and expanding its application field,miniaturization is also one of the important directions for the development of laser direct writing technology.Although the existing commercial large scale laser direct writing instruments are more mature,but the price is expensive and the hardware and software are relatively solidified,it is difficult to upgrade quickly according to the needs of the users.The small desktop laser direct writing system corresponding to it has small area and relatively low price.It is especially suitable for the fabrication of microscale electronic and optoelectronic unit prototype devices,the surface treatment of materials,and the laboratory preparation of small and medium scale devices such as microfluidic chip processing.Based on this purpose,a small UV laser direct writing system based on cage system has been developed.The system has the advantages of easy to assemble and debug and be flexible and versatile.The paper mainly includes:First,from the background of the research of lithography technology,this paper briefly introduces the basic origin,advantages and development process of laser direct writing technology.On this basis,it puts forward the research idea and research purpose of this paper.Secondly,it discusses the main basic principles of laser direct writing technology.Then,we introduce the use of the cage.The small laser direct writing system developed by the system includes the design and debugging of the hardware and software of the system,and the implementation of photoresist based writing.Finally,we discuss the process optimization of the metal array structure and the micro nano unit prototype device by using the system.The main conclusions include the following aspects:(1)we use the Thorlabs cage system to build the optical path,easy to realize the coaxial adjustment of the optical path,reduce the difficulty of the optical path debugging,and improve the stability of the system.The system mainly writing optical routing optical path,illumination and self focusing optical path of three parts.The 405single mode fiber laser is used as a writing source,which is combined with the step motor,the piezoelectric objective and the commercial auto focusing system.The real time autofocus is written.The direct writing range is up to(limited to the range of the sample table)+10 mm,the positive photoresist(AZMIR703,thickness 1?m)is written in a line width of 1.5?m,and the point scanning mode is used.The steady speed of the lithography is 100 dot/s(1?m~2/dot).(2)using graphical programming language LabVIEW,through reading the DXF files saved by AutoCAD,the direct writing control of preset graphics is realized,in order to improve the rate of photolithography and time synchronization,we choose FPGA,digital clock with 0.25?s and 1 MHz,and analog output of 16 bit resolution to solve the problem that the communication rate of the computer is slow and the time of communication is unstable.(3)Using CMOS camera to collect images,measure distance and set the starting point to achieve orientation,alignment and inscription.(4)a suitable photoresist is selected through experimental comparison.spot scanning lithography is realized.The relation between laser power and focusing position and line width is discussed,and the optimized lithography process conditions are obtained.