| Lithography is a key processing technology in the field of IC manufacturing.With the improvement of lithography technology,higher requirements are put forward for the surface defect size and surface particle control of substrate.Therefore,it is necessary to detect the substrate surface before lithography to estimate the surface cleanliness.In micro-/nano-lithography,there is an increasing demand for surface particle detection,and the laboratory lacks simple,cost-effective and highly sensitive particle detection devices.lens.In view of the above problems,this thesis carried out the research on the detection of substrate surface particles.The main contents of the thesis includes:1.The scattering light field of the particles on the substrates is simulated by using the finite-difference time-domain algorithm.The influence of the incident Angle of light wave,wavelength of light source,shape(sphere,tetrahedron and cube),size(100nm-1300nm)and other factors on the distribution of scattering field is analyzed,which provides a basis for the construction of the detection system.2.On the basis of simulating and analyzing the scattered light field of particles,and based on the dark field microscopic principle of off-axis laser illumination,a particle detection system on substrate surface was designed and constructed.The influence of hardware parameters on detection resolution is analyzed.Based on the system,a detection process of surface particles is presented,whose main steps are image acquisition,image processing and data analysis.During the step of image acquisition,the dark field images in the target area are acquired in real time by the CMOS controlled by the graphic operation interface based on C++,the dark field image is processed to obtain a binary image reflecting the particle distribution in the target region.Finally,the region growth method was used to segment the region of the particles in the binary image and extract the corresponding number of pixels.On this basis,the approximate measurement of particle diameter was completed.3.Four types of experiments were conducted by using the established detection system and the proposed detection process.First,the smallest diameter of the particles that can be detected by the system is measured.Experimental results show that the microspheres with a diameter of 100 nm can be detected at the minimum.Then the effect of surface roughness on the detection performance was studied.Besides,the system could not directly distinguish the small particles with the diameter lower than the diffraction limit of the objective lens.Using the scattering light intensity,the approximate value of the diameter of the measured microsphere can be calculated.The detection effect of transparent substrate was also analyzed.On this basis,a simple method to distinguish the small particles was proposed. |
