The "negative etching method" is often used to fabricate thin film resistors. The first photoetching and etching are carried out to obtain the whole pattern of electrodes and resistors, and then the resistance pattern is obtained by lithography and etching with the selective mask of the coated resistance mask. The biggest problem with this approach is that the registration window is narrow. Since the "alignment mark" is limited to the edge of a particular structure, it is not a guarantee of registration anywhere. Registration will be affected by lens distortion, abnormal clamping of ceramic plates, misalignment of mask patterns, and distortion of ceramic plates themselves.
Therefore, in order to fabricate thin film resistance by etching method of negative plate, we usually align the "alignment mark" between the cover mask and the upper layer of microstructure, and then observe whether the pattern on the two is correct or not, and if there is a misalignment, fine-tuning is carried out. After the full registration of the graphics, then do the exposure and other work.
When ordinary contact or proximity lithography machine is used to cover the resistance,
once there is a chain reaction when the pattern is not set, and then the resistance pattern corrosion dislocation, the light one will cause a large deviation of the resistance value. The most important factor is that the microwave circuit pattern is destroyed, which directly affects the yield of the product. Therefore, in general, it is necessary to take timely rework when the misalignment is found in the mirror inspection, but the production efficiency is not high because of the cost of work and waste.
As can be seen from the above, the thin film resistance production method is very important, if the incorrect production method is adopted, there is a great difference between the precision and the production cost of the thin film resistance obtained by the incorrect production method. In addition, the fabrication of thin film resistors is an important step in the production of hybrid microwave integrated circuits, and the advantages and disadvantages of the preparation methods are also discussed. To a large extent, the production efficiency and yield of microwave integrated circuits are determined.
