CN-116973362-B - Method for judging abnormal flip interconnection and communication of infrared focal plane device

CN116973362BCN 116973362 BCN116973362 BCN 116973362BCN-116973362-B

Abstract

The invention discloses a method for judging abnormal connection of flip-chip interconnection of an infrared focal plane device, which comprises the steps of selecting the same layer of layer out layer on four corners of a reading circuit as a reference surface, enabling the reference surface to be close to an antireflection film of a focal plane of an infrared detector, carrying out 3D measurement on the four corners of the focal plane of the infrared detector, wherein a measurement area needs to comprise the antireflection film of the focal plane of the infrared detector and the found same layer of layer out layer on the reading circuit, carrying out height measurement on the measurement area, measuring the height from the antireflection film to the reading circuit, calculating the height difference of the four corners, and judging whether the flip-chip interconnection is abnormal or not. The invention can rapidly and effectively judge whether the communication abnormality is caused by flip-chip interconnection abnormality or not, and does not cause any damage to the infrared focal plane.

Inventors

YANG SHUNHU
WANG QIONGFANG
TANG YAO
LI XIONGJUN
ZHANG YING
GUO RUI
ZHANG XUEBIN

Assignees

昆明物理研究所

Dates

Publication Date: 20260512
Application Date: 20230707

Claims (4)

1. The method for judging the abnormal interconnection and communication of the flip-chip infrared focal plane device is characterized by comprising the following steps of: Step 1, preparing a microscope with 3D measurement and an infrared detector focal plane which needs to be tested and is manufactured by adopting a flip-chip interconnection process, wherein the infrared detector focal plane device consists of a reading circuit, a tellurium-cadmium-mercury film, an antireflection film and filling glue; step 2, finding the same layer of lay out layer on four corners of the infrared detector reading circuit under the microscope field of view to serve as a reference surface, wherein the position is close to an antireflection film of the focal plane of the infrared detector; step3, 3D measurement is carried out on the four corner areas found in the step 2, and the measurement areas need to comprise a reference plane of a reading circuit and an antireflection film area of a focal plane of the infrared detector; step 4, measuring the height of the 3D measuring graph obtained in the step 3, and measuring the height of the antireflection film to the selected reference surface on the reading circuit in the step 2; step 5, calculating the relative height difference of the four points by using the heights obtained in the step 4, and judging whether flip-chip interconnection communication abnormality exists or not according to whether the relative height difference of each measuring point exceeds a threshold value; The height difference of the antireflection film is recorded as delta H 1 , the thickness difference of the tellurium-cadmium-mercury film is recorded as delta H 2 , the height difference of the indium column is recorded as delta H 3 , and when the relative height difference of the antireflection film on a reading circuit exceeds a threshold delta H=delta H 1 +Δh 2 +Δh 3 , the flip-chip interconnection communication abnormality is considered.
2. The method for determining abnormal flip-chip interconnection connectivity of an infrared focal plane device according to claim 1, wherein the step 5 further comprises: After the flip-chip interconnection communication abnormality is judged, whether the welding pressure is too large or too small is further judged.
3. The method for determining abnormal flip-chip interconnection connectivity of an infrared focal plane device according to claim 2, wherein: if the height difference of a certain measuring point exceeds a threshold value delta H, meanwhile, a black white point appears at the position corresponding to the focal plane signal response graph signal, and the signal of a part of pixels of the GPOL-V characteristic curve is saturated, judging that the welding pressure at the measuring point is overlarge.
4. The method for determining abnormal flip-chip interconnection connectivity of an infrared focal plane device according to claim 2, wherein: If the height difference of a certain measuring point exceeds a threshold value delta H, and at the same time, black white points appear at the positions corresponding to the focal plane signal response chart signals and the signals of the pixels of the GPOL-V characteristic curve part appear in a non-conducting state, judging that the welding pressure at the measuring point is too small.

Description

Method for judging abnormal flip interconnection and communication of infrared focal plane device Technical Field The invention belongs to the technical field of infrared detectors, and particularly relates to a method for judging abnormal flip interconnection and communication of an infrared focal plane device. Background The flip-chip interconnection technology is used as one of important technologies in the infrared detector manufacturing process, has good electrical properties, has good electromagnetic interference resistance because of short connecting wires and small parasitic impedance, and can realize electrical and mechanical interconnection at the same time. With the continuous development of infrared detector technology, the pixel spacing is continuously reduced, and the small pixel device brings imaging advantages and challenges to the device process. At present, the manufacturing process of the infrared detector focal plane adopting the flip-chip interconnection process comprises the steps of connecting a detector chip and a readout circuit together in a flip-chip interconnection mode, improving interconnection reliability through a lower filling process, removing a substrate through a back thinning process, plating an antireflection film through a back antireflection process, and testing until the focal plane process is finished. For flip-chip interconnects, the requirements for leveling and alignment are also higher. When the leveling error is larger, uneven pressure is caused during flip-chip interconnection pressure welding, and the phenomenon of overlarge or overlarge pressure occurs at the corners, so that signals on the corners are abnormal during device imaging. The signal abnormality is mainly divided into two types, one is that the pressure is too large, the indium column is too large when the flip-chip interconnection is carried out, the adjacent indium column is bridged, the short circuit is caused, and the signal abnormality is caused, and the other is that the pressure is too small, the indium column is smaller, the communication between a device and a reading circuit is not realized, and the signal is weak or not. At present, the flip-chip interconnection result is mainly judged according to the test result, the test result mainly comprises a response signal diagram and a GPOL-V characteristic curve, the response diagram corresponding to the position of heavy pressure or light pressure is provided with small signals or blind pixels when seen from the response signal diagram, the GPOL-V characteristic curve is provided with excessive pressure, so that no communication is represented as an unopened state, and excessive pressure adhesion is represented as a saturated state. However, these electrical performance states are not in a one-to-one relationship with flip-chip interconnect anomalies, which simply must result in the electrical performance states described above, but which may result from multiple factors occurring singly or together. For example, many steps such as non-opening of the PN junction opening or excessive deep hole depth, abnormal contact of the metal electrode, etc. in the device process may cause abnormal communication, so that the judgment of abnormal communication cannot be achieved only by the test result. The other method is to confirm the shape and the height of the indium column after the film on the infrared focal plane is corroded, but the method causes irreversible damage to the infrared focal plane, has complex steps and consumes time. Therefore, there is currently no fast, economical and easy method for determining flip-chip interconnect anomalies. Disclosure of Invention The invention aims to overcome the defects and provide an economic and simple method for judging the abnormal connection of the flip-chip interconnection of the infrared focal plane device. The infrared detector focal plane device after the back antireflection technology is finished consists of a reading circuit, a tellurium-cadmium-mercury film, an antireflection film and filling glue. The method for judging flip interconnection abnormality comprises the following steps: step (1), preparing a microscope with 3D measurement and an infrared detector focal plane to be tested; Step (2), finding the same layer of lay out layer on four corners of the infrared detector reading circuit under the microscope field of view to serve as a reference surface, wherein the position is close to an antireflection film of the infrared detector focal plane, so that the subsequent measurement is convenient; Step (3), 3D measurement is carried out on the four areas found in the step (2), and the measurement areas need to comprise a reference plane of a reading circuit and an antireflection film area of a focal plane of the infrared detector; Step (4), measuring the height of the 3D measuring graph obtained in the step (3), and measuring the height of the antireflection film to the selected reference plane