Wide-area Surface Topography Measurement And Preparation Of Multi-probe

As the semiconductor technology constantly moving towards tinier technology node, related film deposition, lithography, etching and doping process are prompted to develop rapidly. Shorter wavelength of exposure light source and larger lens opening rate are applied to the micro machining, making the depth of focus become shallow. Therefore the exposure precision is affected by the photoresist surface undulation. So it is required to measure the flatness of photoresist film.Based on the necessity of measuring photoresist surface morphology, a new measurement method of combining optical measurement and mechanical multi-probe method was proposed in this paper. Wide-area surface topography measurement system was established, and error separation techniques were explored in the scanning measurement to measure the surface morphology in high precision and speed. Then an independent multi-probe in two dimensions based on Si-based Si3N4 elastic film was designed and fabricated. The following is the main research content of this article.Firstly, according to the development of lithography and photoresist coating characteristics, the measurement of photoresist surface morphology is put forward. Compare advantages and disadvantages of the existing surface measurement methods and introduce the development of scanning probe, multi-probe and their applications.Secondly, wide-area optical-mechanical multi-probe measurement method has been proposed according to the working principle of the contact mode of AFM and the characteristics of optical measurement. This article elaborated the feature of this method, discussed the principle and the scanning mode and studied the feasibility of this method in theory. We designed the wide-area optical-mechanical multi-probe measurement system and applied the multi-ball-cantilever in the system, indicating the feasibility of this method by measurement experiment of the resin model and the height of standard notch.Thirdly, we construed the error separation model of the measurement system, expounded least-squares solution for simultaneous linear equations which can not only remove the translation error but also take the zero error into consideration. The rotation error should be removed by the autocollimator when we used the least square equation method. We established the theoretical calculation model of the multi-probe measurement method which was suitable for optical-mechanical multi-probe system. We took systematic error and random error into consideration, analyzed the measurement uncertainty of the surface morphology and calculated the unknown parameters by the least squares method.Fourthly, a 9×9 two-dimensional-grid multi-probe, Si-based Si3N4 elastic film independent multi-probe, was preliminary designed. We got optimized geometric parameters of the multi-probe by analyzing the effect of thickness and area of Si3N4 elastic film on measurement range with ANSYS finite element software. Then, according to the simulation results, silicon cups of the independent multi-probe were completed successfully by anisotropic and isotropic etching, Si3N4 elastic film was deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) and probes of SU-8 were obtained by Lithography. Thus we prepared the independent multi-probe based on Si-based Si3N4 elastic film and measured its parameters.The research content of this paper provided a new perspective of measurement for the wide-area surface morphology measurement, expounded a multi-probe scanning method and its data processing and explored the design and preparation of two dimensional independent multi-probe based on Si-based Si3N4 elastic film, which are of certain value of reference.