A kind of focal plane detector and its indium ball array preparation method

Abstract

This application discloses a focal plane detector and its indium ball array preparation method, the method includes obtaining a pre-processed readout circuit chip with a photoresist and a first metal layer distributed on the upper surface; the photoresist corresponds to the pixels other than the input stage In the region, the first metal layer covers the photoresist and the input-level pixel; the terrace-shaped dielectric film layer is formed in the area corresponding to the input-level pixel on the first metal layer, and the readout circuit chip is processed; the terrace-shaped dielectric film layer The top is planar, the side is an inclined surface, and the size of the bottom is smaller than the pixel size of the input level; the second metal layer is prepared on the upper surface of the readout circuit chip after processing; the second metal layer is connected with the first metal layer; Prepare the indium film layer on the surface of the metal layer, and remove the photoresist and the first metal layer, the second metal layer, and the indium film layer corresponding to the photoresist; The film layer forms indium balls on the top of the mesa dielectric film layer to obtain an array of indium balls, and the size and height of the indium balls are uniform.

Description

technical field [0001] The present application relates to the technical field of detectors, in particular to a focal plane detector and an indium ball array preparation method thereof. Background technique [0002] The focal plane detector is connected by a detector chip and a readout circuit chip with an indium ball array through a flip-chip interconnection process, and is widely used in military and civil fields such as early warning detection, infrared reconnaissance, and imaging guidance. [0003] At present, when preparing the indium ball array on the readout circuit chip, the method of thick glue stripping is usually used, and the indium is completed through thin glue photolithography, bottom metal deposition, metal stripping, thick glue photolithography, indium evaporation, and indium column stripping. In the preparation of the pillars, the indium pillars are reflowed at high temperature to form indium balls. The morphology and height uniformity of the indium pillars ...

AI Technical Summary

Problems solved by technology

The size, shape, and height uniformity of indium columns directly determine the connectivity rate of the interconnection between the readout circuit chip and the detector chip. In order to ensure that the focal plane detector has good electrical performance and strong reliability, usually Higher indium columns need to be prepared, so thicker indium films need to be grown. Therefore, there is a strong connection between the photoresist surface and the indium film on the sidewall formed by thick-resist lithography and the indium columns on the metal surface, resulting in There is a significant difference in the height of the indium column after peeling off, resulting in a significant difference in the size and height of the indium ball, which in turn affects the connectivity between the detector chip and the readout circuit chip, and the unconnected pixels will become invalid pixels , making the effective pixel rate of the detector chip lower

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