Thick-film coating process for preparing TSV three-dimensional integrated RDL electroplated mask

Abstract

The invention discloses a thick-film coating process for preparing a TSV three-dimensional integrated RDL electroplated mask. The technology comprises the following steps: a Ti adhesion layer and a Cu seed layer are sequentially sputtered on the surface of an insulated layer of a TSV blind hole electroplated wafer; a thick film is prepared in a mode of gluing for two times and baking for two times, a thick photoresist is coated at low speed for the first time, a thin photoresist is coated at high speed for the second time, time and temperature of the two-time baking vary according to the thickness ratio of the upper glue layer to the lower glue layer, and the ratio of the accumulated baking time of the bottom glue layer to the baking time of the surface glue layer is the thickness ratio of the two; and exposure, development and hardbaking are then carried out for preparing the RDL electroplated mask. Through adjusting parameters of two-time gluing and conditions of baking, uniformity of the thick film layer and resolution of lithography can be ensured; through strong exposure, quick development and low-temperature and long-time hardbaking, the mask which is high in precision, steep in side wall, higher in thickness and higher in uniformity can be manufactured; and the technology of the invention can be applied to RDL interconnecting wire whose electroplated layer is higher than 20mum and appearance is clear and neat.

Description

technical field [0001] The invention belongs to the technical field of microelectronics, in particular to a thick glue process for preparing a TSV three-dimensionally integrated RDL electroplating mask. Background technique [0002] At present, the RDL wiring used in TSV three-dimensional integration is generally prepared by electroplating process. The quality of the mask in the electroplating process is the key to realizing high-quality RDL. In order to improve the electrical interconnection characteristics of ultra-thin wafers and TC( The reliability of Thermal cycling) and HTS (High Temperature Storage) requires the thickness of RDL lines to be as high as 20 μm or more. However, to prepare such a thick electroplating mask, the uniformity of the mask, the photolithographic resolution, and the steepness of the sidewall will be the key factors affecting the RDL electroplating process. [0003] "Research on AZ4620 Thick Resist Photolithography Process for Micro Device Proces...

AI Technical Summary

Problems solved by technology

But the main problem of this method is: AZ4620 has a limited coating thickness, which cannot meet the needs of electroplating RDL lines above 20 μm

But the main problems are: first, due to the fluidity of the photoresist, the morphology of the film is constantly changing, it is difficult to obtain an ideal film only by controlling the coating method, the process parameter window is not clear, and the film obtained by this method The internal stress of the layer is relatively large; the second is that the second glue coating is directly carried out without baking after the first glue coating. If the speed is not controlled properly, a large part of the surface glue will be thrown out, which will eventually lead to an insignificant increase in the thickness of the second glue coating, which is difficult to Fabrication of Thick Adhesive Masks Required for RDL Plating of TSV Stereo Integration

However, the disadvantages of making RDL electroplating mask by this method are as follows: First, there is a large internal stress in SU-8 thick glue, especially for ultra-thin wafers with a thickness less than 100 μm in TSV three-dimensional integration, when its thickness is close to the thickness of the glue layer Severe bending or even slivers will occur; the second is that the thermal expansion effect of SU-8 glue in the electroplating solution will cause the line width of the electroformed structure to decrease, which seriously affects the accuracy of the electroplating pattern size; the third is that after the baking process, the SU-8 -8 glue will be highly cross-linked and difficult to be completely removed

However, the problems of this method are as follows: firstly, it is difficult to ensure high-quality outline structure lines by two times of photolithography and electroplating, and the process is relatively cumbersome; The height of the mask after engraving is inconsistent, and it is difficult to ensure the flatness of the surface after overflow plating; third, this method has strict requirements on the height difference between the surface of the electroplating structure and the photoresist, and requires a high degree of process control, resulting in Low preparation efficiency

[0006] Therefore, the existing thick mask preparation technology cannot meet the requirements of RDL electroplating in TSV three-dimensional integration for thicker, higher uniformity, and steep sidewall masks, and the removal of glue is cumbersome, and it cannot be compatible with the TSV three-dimensional integration process. The disadvantage of high cost,

Images