Quality Control Of Sub-micron Lithography Technology

Optical lithography has become a key link to improve the integration of the integrated circuits.The quality of lithography seriously affects the quality of the performance of devices and products yield.Experts estimate that lithography process on the yield of IC products can reach more than 50%. However, with the integration raises and width size decreases, it's more difficulty to control the lithography quality. Especially when entering the times of sub-micron line width, line width control precision requires is less than 10%, side wall angle is greater than 85°, and alignment accuracy is less than the 1 / 4 of the width, the defect control can makes the rate of finished products more than 90% .In order to improve IC performance and yield, this thesis mainly focuses on the reseans of lithography process quality abnormally. The methods can be divided into three categories.Line width and profile control are the keys of the lithography quality. This thesis analyzes the impact of the reasons which are the exposure process window, wafer flatness, resist thickness, surface reflection and standing wave effects, developing, mask, and carries out experiment, finally proposes the quality control methods.Alignment control is also an important quality control issues.This thesis analyzes the principle of alignment, different signs (LSA, LIA, FIA, WGA) of the applicable conditions, and the situation of alignment offset, and carries out experiment, finally proposes the methods of matching, testing and adjustment.Defect Control Process also affects the quality of the product, particularly when the new production lines are introduced. It can increase the rate of finished products from 20% of the stage of the trial operation to 90% of the stage of mature technology. This thesis analyzes the causes of the defects, and proposes the different control methods.This thesis also studies the impact of the process of lithography mask, and proposes 32nm resolution enhancement technology and double exposure technique, which reduce the duty ratio of the line width, and improve the impact of the exposure condition of the different width. By detecting and controlling the impact of the quality on the above aspects of lithography. This thesis bases on sub-micrometer processing platform of NSR-2005i9c lithography equipment, finally meets the requirements of 0.45um line width.