Reading circuit processing method

Abstract

The invention discloses a reading circuit processing method, which comprises the following steps of: detecting a reading circuit; preparing a metal electrode on the reading circuit; preparing an indium column on the metal electrode; detecting the reading circuit; and comparing the two detection results, if a reading circuit which is normal in the first detection and abnormal in the second detection exists, marking the reading circuit as a to-be-optimized reading circuit, removing a metal electrode and an indium column on the to-be-optimized reading circuit, and then reworking. By adopting the reading circuit processing method, for the reading circuit which is detected normally for the first time but detected abnormally for the second time, the situation that problems exist in the processing process to cause abnormal detection for the second time can be determined, at the moment, the metal electrode and the indium column on the to-be-optimized reading circuit are removed, and then reworking is carried out; according to the invention, abnormal reading circuits caused by processing problems rather than self problems can be prevented from being screened out, so that the yield of finished products is effectively improved.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor process technology, and specifically relates to a readout circuit processing method. Background Art

[0002] The readout circuit of the infrared chip is a circuit connected to the infrared detector array. Its main function is to convert the infrared signals detected by the infrared detector array into electrical signals and perform necessary processing on these signals, such as amplification, filtering, analog-to-digital conversion, etc., for subsequent signal processing and imaging.

[0003] After the readout circuit is manufactured in the silicon factory, it is necessary to further manufacture indium pillars on the readout circuit to realize the flip-chip interconnection between the readout circuit and the infrared detector array. However, the yield rate of the finished product of the existing readout circuit subsequent indium pillar manufacturing process is low. Summary of the invention

[0004] The technical problem to be solved by the present application is that the yield rate of the finished product in the existing indium pillar preparation process for the readout circuit is low. In order to solve the above technical problem, a readout circuit processing method with higher yield rate is provided.

[0005] The technical solution proposed in this application is: A method for processing a readout circuit comprises the steps of: S110, testing the readout circuit; S120, preparing a metal electrode on the readout circuit; S130, preparing an indium column on a metal electrode; S140, testing the readout circuit; S150, comparing the detection results of step S110 and step S140, if there is a readout circuit that is detected normally in step S110 but abnormal in step S140, mark it as a readout circuit to be optimized, remove the metal electrodes and indium columns on the readout circuit to be optimized, and then rework it.

[0006] Furthermore, the readout circuit processing method further comprises the steps of: S160, dicing the readout circuit; Among them, after scribing, the metal electrodes and indium columns on the readout circuit to be optimized are removed, and then rework is performed.

[0007] Further, step S160 includes: S161, performing a coating process on the readout circuit; S162, dicing the readout circuit.

[0008] Furthermore, step S110 includes: S111, cleaning the readout circuit; S112, testing the readout circuit.

[0009] Furthermore, in step S111: The readout circuit is first soaked in acetone and then cleaned with alcohol.

[0010] Further, step S120 includes: S121, applying a photoresist layer on the readout circuit; S122, etching the photoresist layer to form a plurality of openings for exposing the readout circuit; S123, forming a metal electrode electrically connected to a readout circuit at the opening; S124, removing the photoresist.

[0011] Further, in step S123, a Ti layer, a Pt layer and an Au layer are sequentially formed at the opening by electron beam deposition.

[0012] Further, step S130 includes: S131, applying a photoresist layer on the readout circuit; S132, etching the photoresist layer to form a plurality of openings to expose metal electrodes; S133, forming an indium column electrically connected to the metal electrode at the opening; S134, removing the photoresist.

[0013] Furthermore, the height of the indium column is 5-15 μm.

[0014] Furthermore, in step S110 and step S140 , the readout circuit is tested by a probe station.

[0015] By adopting the above-mentioned readout circuit processing method, for a readout circuit that is normal in the first detection but abnormal in the second detection, it can be determined that there is a problem in the processing process that causes the abnormal second detection. At this time, the metal electrodes and indium columns on the readout circuit to be optimized are removed, and then rework is performed. This can avoid screening out readout circuits that are abnormal due to processing problems rather than their own problems, thereby effectively improving the yield of the finished product. DETAILED DESCRIPTION

[0016] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0017] The present application provides a readout circuit processing method, which is applied to the readout circuit after it leaves the factory and before it is interconnected with an infrared detector array, specifically to prepare indium pillars on the readout circuit, and the method can effectively improve the yield of the finished product.

[0018] In one embodiment, a readout circuit processing method comprises the steps of: S110, the readout circuit is tested, and a readout circuit with abnormal detection may be marked.

[0019] S120, preparing a metal electrode on the readout circuit.

[0020] S130, preparing an indium column on the metal electrode to facilitate subsequent interconnection with an infrared detector array.

[0021] S140, the readout circuit is tested. Similarly, it can be known that the readout circuit with abnormal detection can be marked.

[0022] S150, comparing the detection results of step S110 and step S140, if there are readout circuits that are detected normally in step S110 but abnormal in step S140, mark these readout circuits as readout circuits to be optimized, remove the metal electrodes and indium columns on the readout circuits to be optimized, and then rework them.

[0023] It should be explained that, for the above-mentioned readout circuits to be optimized, since the test result in the first test, i.e., step S110, is normal, while the second test result is abnormal, it can be determined that there are process problems during the processing of the readout circuits. Therefore, these readout circuits to be optimized can be cleaned up, that is, the structures formed during the processing can be removed, and then reworked to avoid screening out readout circuits with abnormalities due to processing problems.

[0024] It is necessary to further explain that the metal electrodes and indium pillars formed in the above processing method can be removed by grinding and polishing, and then cleaned. In addition, the above rework includes steps S120 to S140. If abnormalities are detected again after rework, the process equipment and operation procedures can be tested. If they are normal, the readout circuit can be treated as a scrap.

[0025] By adopting the above-mentioned readout circuit processing method, for a readout circuit that is normal in the first detection but abnormal in the second detection, it can be determined that there is a problem in the processing process that causes the abnormal second detection. At this time, the metal electrodes and indium columns on the readout circuit to be optimized are removed, and then rework is performed. This can avoid screening out readout circuits that are abnormal due to processing problems rather than their own problems, thereby effectively improving the yield of the finished product.

[0026] In one embodiment, the readout circuit processing method further comprises the steps of: S160, dicing the readout circuit.

[0027] It should be noted that the above rework step is performed after dicing, that is, after dicing, the metal electrodes and indium pillars on the readout circuit to be optimized are removed, and then rework is performed.

[0028] It should be noted that in the process of processing the readout circuit, the processing object is a whole wafer, and the wafer has multiple readout circuits. The multiple readout circuits on the wafer are processed at the same time to improve the processing efficiency. After the processing is completed, it is diced to generate multiple finished products. It can be seen that even if the readout circuit is detected as abnormal for the first time, it will be processed, but there is no need to re-detect the readout circuit that was detected abnormal for the first time, so as to shorten the detection time and further improve efficiency. In addition, this processing method reworks the readout circuit to be optimized separately after dicing, which is more convenient and quick.

[0029] Specifically, step S160 includes the following steps: S161, performing photoresist coating on the readout circuit, that is, coating the readout circuit with a layer of photoresist.

[0030] S162, dicing the readout circuit.

[0031] It should be explained that the photoresist treatment in step S151 can play a protective role to avoid damage to the readout circuit during the dicing process.

[0032] It should be noted that step S110 includes the following steps: S111, cleaning the readout circuit.

[0033] Specifically, the readout circuit is first soaked in acetone for preferably 10 minutes, and then cleaned with alcohol, wherein the alcohol cleaning can be performed with an alcohol spray gun.

[0034] S112, the readout circuit is tested, and any readout circuit detected to be abnormal can be marked.

[0035] It should be explained that after the readout circuit leaves the factory, it may be contaminated during transportation, such as surface contamination. In this case, direct detection may affect the detection results. Therefore, the readout circuit is first cleaned to remove surface dirt that may affect the detection results. Specifically, in this step and step S140, a probe station is used to detect the readout circuit.

[0036] It should be noted that step S120 includes the following steps: S121, applying a photoresist layer on the readout circuit.

[0037] S122, etching the photoresist layer to form a plurality of openings to expose the readout circuit.

[0038] Specifically, the opening is in a rectangular shape.

[0039] S123, forming a metal electrode electrically connected to the readout circuit at the opening.

[0040] Specifically, a Ti layer, a Pt layer and an Au layer can be sequentially formed at the opening by electron beam deposition, and the thickness of the Ti layer is 50 nm, the thickness of the Pt layer is 200 nm, and the thickness of the Au layer is 50 nm. In addition, the opening position in step S122 is determined according to actual conditions.

[0041] S124, removing the photoresist.

[0042] Specifically, the readout circuit is first immersed in the degumming solution, then heated to 80±5°C on a heating table until the metal falls off, then rinsed with acetone and alcohol in turn, and finally dried.

[0043] It should be noted that step S130 includes the following steps: S131, applying a photoresist layer on the readout circuit.

[0044] S132, etching the photoresist layer in step S131 to form a plurality of openings for exposing the metal electrodes. It should be noted that in this step, the shape of the openings is also rectangular.

[0045] S133, forming an indium column electrically connected to the metal electrode at the opening.

[0046] Specifically, an indium column is formed at the opening by evaporation, and the indium column is used to interconnect with the infrared detector array. Optionally, the height of the indium column is 5 to 15 microns, which can be welded with the infrared detector array to avoid breakpoints due to too low height, and to avoid the pressure between the infrared detector array and the infrared detector array being increased due to too high height, affecting the surrounding solder joints, thereby affecting the yield of the interconnection. Preferably, the height of the indium column is 5 μm.

[0047] S134, removing the photoresist.

[0048] Specifically, the readout circuit is first immersed in the degumming solution, then heated to 80±5°C on a heating table and immersed for at least 3 hours. Next, the edge is rinsed through a syringe, and the indium metal layer is peeled off with tweezers. Then, it is rinsed with acetone and alcohol in turn, and finally dried.

[0049] After the photoresist is removed, the surface of the readout circuit has been cleaned, so the detection in step S140 can be directly performed.

[0050] Regarding step S140, it should be noted that when using a probe station for detection, since metal electrodes and indium pillars have been formed on the readout circuit, detection can be performed through the indium pillars at this time, and detection can also be performed through other contacts on the readout circuit.

[0051] In summary, the readout circuit processing method provided by the present application has at least the following advantages: By setting up two tests and comparing the two test results, the readout circuit that has problems due to processing will be reworked to eliminate the situation where the finished product is abnormal due to processing, thereby effectively improving the yield of the finished product.

[0052] Although the embodiments of the present application have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A readout circuit processing method, characterized in that: Includes steps: S110, testing the readout circuit; S120, preparing a metal electrode on the readout circuit; S130, preparing an indium column on a metal electrode; S140, testing the readout circuit; S150, comparing the detection results of step S110 and step S140, if there is a readout circuit that is detected normally in step S110 but abnormal in step S140, mark it as a readout circuit to be optimized, remove the metal electrodes and indium columns on the readout circuit to be optimized, and then rework it.

2. The readout circuit processing method according to claim 1, characterized in that: The readout circuit processing method further comprises the steps of: S160, dicing the readout circuit; Among them, after scribing, the metal electrodes and indium columns on the readout circuit to be optimized are removed, and then rework is performed.

3. The readout circuit processing method according to claim 2, characterized in that: Step S160 includes: S161, performing a coating process on the readout circuit; S162, dicing the readout circuit.

4. The readout circuit processing method according to claim 1, characterized in that: Step S110 includes: S111, cleaning the readout circuit; S112, testing the readout circuit.

5. The circuit processing method according to claim 4, characterized in that: In step S111: The readout circuit is first soaked in acetone and then cleaned with alcohol.

6. The readout circuit processing method according to claim 1, characterized in that: Step S120 includes: S121, applying a photoresist layer on the readout circuit; S122, etching the photoresist layer to form a plurality of openings for exposing the readout circuit; S123, forming a metal electrode electrically connected to a readout circuit at the opening; S124, removing the photoresist.

7. The readout circuit processing method according to claim 6, characterized in that: In step S123 , a Ti layer, a Pt layer and an Au layer are sequentially formed at the opening by electron beam deposition.

8. The readout circuit processing method according to claim 1, characterized in that: Step S130 includes: S131, applying a photoresist layer on the readout circuit; S132, etching the photoresist layer to form a plurality of openings to expose metal electrodes; S133, forming an indium column electrically connected to the metal electrode at the opening; S134, removing the photoresist.

9. The readout circuit processing method according to claim 1 or 8, characterized in that: The height of the indium column is 5~15μm.

10. The readout circuit processing method according to claim 1, characterized in that: In step S110 and step S140 , the readout circuit is tested by a probe station.