The Research On The Lithography System Optimization And The Grating Mask Proifle Parameters Controlling In The Fabrication Of The Holographic Grating

As a part of the National Key Technologies R&D Program for the11thFive-yearPlan, the research is mostly focused on the exposure system, the adjustment, and theprofile controlling. Firstly, the radio between the radius of the pinhole and the waist ofthe laser is established. In order to stop the higher spatial frequencies beam anddecrease the diffraction effect, it's the worthy work to optimize the configuration ofthe spatial filter. The phase distortion of diffraction wavefronts and the Gaussiancharacteristics change of diffraction beam is analyzed, the optimal ratio between1.52<a/0<2.2is given, so put the axe in the helve of standard absence in the spatialfilter of the lithography system. Secondly, talk about the conditionality of the Lloyd'slithography system. Based on the simple trigonometry of the light in the Lloyd'slithography system, the grating exposed area depend on the mirror size, incident lightradius, the optical path difference, the contrast, the coherence length of the laser havebeen given, then the conditionality of the configuration and the fringe contrast to thegrating exposed area is discussed; Thirdly, a method of adjusting the groove densityspatial frequency multiplication of plane holographic grating is discussed. Therelationship between the period of the reference grating and the interference fringe pattern is proved in theory. Point out the equation regulation in the groove densityalignment. The method's precision for the different width of the reference grating isalso analyzed. Fourthly, analyze the characteristic of different beamsplitters inholographic grating lithography system. Based on the working theory of the cube andgrating beamsplitters, the relation between the phase distortion, the alignment errorand the using parameters of the exposal system is discussed, then come the conclusionthat using the grating beamsplitter can improve the stability of the lithography systemfor some degree, especially in the large system parameter and in the large-area gratingfabrication for long time exposure. Fifth, the q-parameters of Gaussian beam is usedto describe the wavefront aberration of the interference image according to thedifferent axis alignment error in the grating exposure system. The spatial phase of thetwo Gaussian beams and the mathematical expression of moiré pattern is given, thenthe relation between the system adjustment error and the wavefront aberration isdiscussed. The conclusion shows that: the relative defocus of the left and the rightcollimating systems is the most critical parameter, which influences the wavefrontaberration strongly. The wavefront aberration is also increased according to thedecreased focal length. The results obtained from an initial set of experiments to be ingood agreement with the theoretical analysis. Sixth, in order to analyze the profileevolvement, to control the profile of groove in grating fabrication, based on thenonlinearity of the photoresist curve in development processing, a binary resistmathematical model for simulating the profile evolution of grating is present. Dutycycle and the groove depth of the profile which depend on the contrast and exposuredose can easily be understudied. The complete photoresist curve can be divided intothree sections, the effect of each section in the profile formation of grating masks isdiscussed, then the simulation surface-relief profile model is presented. Conclusionshows that, the duty cycle of the grating mask shrinks as the exposure dose isincreased and the contrast loss; The nonlinearity of photoresist response curve is incontrol, the groove is inclined to be rectangular, trapezoidal or sinusoidal.