A cleaning method for a micro-bridge structure of a non-cooled infrared focal plane detector
By combining multiple spraying and immersion with hydroxylamine solution, isopropanol solvent, and deionized water with megaphonic cleaning, the problem of easy damage to the microbridge structure of uncooled infrared focal plane detectors during the cleaning process was solved, achieving effective cleaning and improved yield.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SUZHOU ZERO PERCEPTION TECH CO LTD
- Filing Date
- 2023-09-05
- Publication Date
- 2026-07-21
AI Technical Summary
The microbridge structure of uncooled infrared focal plane detectors is easily damaged during cleaning, leading to performance degradation and reduced yield. Existing technologies cannot effectively clean it, thus increasing production costs.
A method combining multiple spraying and immersion with hydroxylamine solution, isopropanol solvent, and deionized water, along with megaphonic cleaning, was employed. The spraying pressure and frequency were controlled to avoid the inherent frequencies of the microbridge structure and membrane layer. The membrane was then cleaned and dried multiple times.
Effective cleaning of the microbridge structure of uncooled infrared focal plane detectors ensures its integrity, improves yield, and reduces production costs.
Smart Images
Figure CN117046789B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a chip cleaning method, and more particularly to a cleaning method for a microbridge structure of an uncooled infrared focal plane detector. Background Technology
[0002] In the production process of uncooled infrared focal plane array detectors, the suspended microbridge structure uses polyimide as a sacrificial layer, which plays a supporting role throughout the process, assisting in the successful formation of the microbridge structure. After the overall microbridge structure manufacturing process is completed, a release process is required to remove the original supporting polyimide layer (release: a process of etching polyimide with oxygen plasma). Finally, the overall structure is supported by two piers and the legs on the microbridge structure, as detailed below. Figure 1 As shown in the schematic diagram, the linewidth of the microbridge legs is typically 350nm-200nm. The manufacturing of uncooled infrared focal plane array detectors involves standard MEMS manufacturing processes. Under normal MEMS manufacturing procedures, cleaning is required after oxygen plasma etching to remove polymer residues left after etching. However, because the microbridge structure of uncooled infrared focal plane array detectors is a suspended structure after the release process, this microbridge structure is relatively fragile and cannot withstand the damage caused by conventional cleaning processes. Because the microbridge structure is easily damaged, existing technologies often do not clean it. Both cleaning and lack thereof in existing technologies directly reduce the overall performance and yield of uncooled infrared focal plane array detectors and significantly increase production costs. Summary of the Invention
[0003] The technical problem solved by this invention is to provide a cleaning method for the microbridge structure of an uncooled infrared focal plane detector, overcoming the technical problem that the microbridge structure of an uncooled infrared focal plane detector is easily damaged and leads to failure during the cleaning process in the prior art.
[0004] The technical solution of this invention is: to provide a cleaning method for the microbridge structure of an uncooled infrared focal plane detector, wherein the microbridge structure of the uncooled infrared focal plane detector to be cleaned includes a suspended structure formed by a release process, and the method includes the following steps: The uncooled infrared focal plane detector chip is first sprayed with a hydroxylamine-containing solution at a pressure of 0.2 MPa to 1 MPa, and then immersed in the hydroxylamine-containing solution, which also performs the first cleaning of the uncooled infrared focal plane detector chip. The uncooled infrared focal plane detector chip is first sprayed with isopropanol solvent at a pressure of 0.2 MPa to 1 MPa, and then the uncooled infrared focal plane detector chip is immersed in isopropanol solvent, while the uncooled infrared focal plane detector chip is cleaned a second time. The uncooled infrared focal plane detector chip is first sprayed with deionized water at a pressure of 0.2 MPa to 1 MPa, and then immersed in deionized water. At the same time, the uncooled infrared focal plane detector chip is cleaned for the third time. The uncooled infrared focal plane detector chip is first sprayed with isopropanol solvent at a pressure of 0.2 MPa to 1 MPa, and then the uncooled infrared focal plane detector chip is immersed in isopropanol solvent, while the uncooled infrared focal plane detector chip is cleaned for the fourth time. The cleaned uncooled infrared focal plane detector wafer is then dried.
[0005] Mega-acoustic cleaning is used when cleaning the uncooled infrared focal plane detector chip.
[0006] A further technical solution of the present invention is that the frequency of mega-acoustic cleaning is different from the inherent frequency of the microbridge structure and the film layer in the uncooled infrared focal plane detector.
[0007] A further technical solution of the present invention is to control the spray pressure by controlling the spray frequency and the spray volume.
[0008] A further technical solution of the present invention is that the frequency of megasonic cleaning is different from the inherent frequency of the microbridge structure and the film layer in the uncooled infrared focal plane detector, while the frequency of megasonic cleaning can achieve the cleaning effect.
[0009] A further technical solution of the present invention is: spraying with a solution containing hydroxylamine in two stages, after the first spraying, letting it stand for more than 1 minute before the second spraying, and then letting it stand for more than 30 seconds.
[0010] A further technical solution of the present invention is: to immerse the microbridge wafer of the uncooled infrared focal plane detector in a cleaning solution containing hydroxylamine for 40 to 60 minutes at a temperature of 55°C to 70°C.
[0011] A further technical solution of the present invention is: the isopropanol solvent is used for spraying in two stages. After the first spray, the mixture is left to stand for more than 1 minute before the second spray is performed, and then left to stand for more than 30 seconds.
[0012] A further technical solution of the present invention is: the uncooled infrared focal plane detector chip is first immersed in isopropanol solvent for 10 to 15 minutes.
[0013] A further technical solution of the present invention is to immerse the uncooled infrared focal plane detector chip in deionized water for 5 to 8 minutes.
[0014] A further technical solution of the present invention is: during drying, the drying time at room temperature is greater than 30 minutes, and then the product is placed in an oven for baking at 120°C for 3 to 5 minutes.
[0015] A further technical solution of the present invention is that the concentration of the isopropanol solvent is greater than 95%.
[0016] The technical effect of this invention is: to provide a cleaning method for the microbridge structure of an uncooled infrared focal plane detector, comprising the following steps: first spraying the uncooled infrared focal plane detector wafer with a hydroxylamine-containing solution at a pressure of 0.2 MPa to 1 MPa; then immersing the uncooled infrared focal plane detector wafer in the hydroxylamine-containing solution, while simultaneously performing a first megaphonic cleaning of the uncooled infrared focal plane detector wafer; secondly spraying the uncooled infrared focal plane detector wafer with isopropanol solvent at a pressure of 0.2 MPa to 1 MPa; then immersing the uncooled infrared focal plane detector wafer in the isopropanol solvent, while simultaneously performing a first megaphonic cleaning of the uncooled infrared focal plane detector wafer. The uncooled infrared focal plane detector chip undergoes a second megaphonic cleaning. First, deionized water is sprayed onto the chip at a pressure of 0.2 MPa to 1 MPa, followed by immersion in deionized water and a third megaphonic cleaning. Then, isopropanol solvent is sprayed onto the chip at a pressure of 0.2 MPa to 1 MPa, followed by immersion in isopropanol solvent and a fourth megaphonic cleaning. Finally, the cleaned chip is dried. This invention, by employing a combined spraying and immersion method, ensures the integrity of the microbridge structure while also guaranteeing the cleaning environment. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the suspended microbridge structure of a single pixel in the uncooled infrared focal plane detector of the present invention.
[0018] Figure 2 This is the cleaning step of the present invention. Implementation
[0019] The technical solution of the present invention will be further described below with reference to specific embodiments.
[0020] like Figure 1 , Figure 2 As shown, a specific embodiment of the present invention is: providing a cleaning method for the microbridge structure of an uncooled infrared focal plane detector, wherein the microbridge structure of the uncooled infrared focal plane detector to be cleaned includes a suspended structure formed by a release process, comprising the following steps: The uncooled infrared focal plane detector chip is first sprayed with a hydroxylamine-containing solution at a pressure of 0.2 MPa to 1 MPa, and then immersed in the hydroxylamine-containing solution, which also performs the first cleaning of the uncooled infrared focal plane detector chip.
[0021] The specific implementation process is as follows: A cleaning solution containing hydroxylamine is used to spray and then immerse the microbridge wafer of the uncooled infrared focal plane detector after cleaning. Specifically, the microbridge wafer is sprayed entirely before cleaning. The spraying frequency and volume are controlled to manage the force exerted on the microbridge wafer. Because the amount of hydroxylamine-containing solution used is relatively small, the tension between it and the microbridge structure of the uncooled infrared focal plane detector is relatively small and controllable. Finally, during immersion, when the solution comes into direct contact with the hydroxylamine solution, the sprayed solution also acts as a tension buffer, reducing the direct impact of the cleaning solution on the suspended microbridge structure of the uncooled infrared focal plane detector, thus providing protection and cushioning.
[0022] In a preferred embodiment, the hydroxylamine-containing solution is sprayed twice. After the first spray, the sample is allowed to stand for more than 1 minute before the second spray, followed by a stand for more than 30 seconds. The first spray is smaller in both quantity and frequency compared to the second spray. The first spray is primarily for initial tension control, while the stand is mainly to ensure sufficient contact between the cleaning solution and the microbridge structure. The second spray is primarily to enhance the buffering effect between the cleaning solution and the microbridge structure. After spraying, the cleaning solution is slowly introduced, immersing the microbridge wafer of the uncooled infrared focal plane detector in the hydroxylamine-containing cleaning solution for 40 to 60 minutes at a temperature of 55°C to 70°C. Simultaneously, megasonic cleaning is performed. The frequency of megasonic cleaning is higher than 1 MHz. This frequency differs from the inherent frequency of the microbridge structure and its films in the uncooled infrared focal plane detector, thus avoiding the inherent frequencies of the microbridge structure and its individual films while ensuring effective cleaning. However, simply increasing the frequency of the megohmmeter while decreasing the energy will have no cleaning effect at all, and some residue will still remain on the microbridge structure, greatly reducing the cleaning effect.
[0023] The uncooled infrared focal plane detector chip is first sprayed with isopropanol solvent at a pressure of 0.2 MPa to 1 MPa, and then immersed in isopropanol solvent, while simultaneously performing a second cleaning.
[0024] The specific implementation process is as follows: The uncooled infrared focal plane detector wafer is first sprayed with isopropanol solvent at a pressure of 0.2 MPa to 1 MPa. The spraying is mainly to neutralize the hydroxylamine-containing cleaning solution and enhance the buffering effect between the solvent and the microbridge structure. The isopropanol concentration is above 95%. Then, the uncooled infrared focal plane detector wafer is immersed in isopropanol solvent, simultaneously performing a second cleaning. The immersion time in isopropanol solvent is 10 to 15 minutes.
[0025] In a preferred embodiment, the isopropanol solvent spraying is performed in two stages. After the first spray, the solution is allowed to stand for more than 1 minute before the second spray, followed by a stand for more than 30 seconds. The first stand is primarily to allow the isopropanol solvent to neutralize any residual hydroxylamine-containing cleaning solution, and the first spray is mainly for initial tension control. The second spray, after allowing the isopropanol solvent to stand for more than 30 seconds, is primarily to enhance the buffering effect between the solvent and the microbridge structure. The amount and frequency of the first spray are significantly less than those of the second spray.
[0026] After spraying and settling, isopropanol solvent is slowly introduced, and the uncooled infrared focal plane detector chip is immersed in the isopropanol solvent at room temperature for 10 to 15 minutes. At the same time, megasonic cleaning is performed. The frequency of megasonic cleaning is higher than 1 MHz. The frequency of megasonic cleaning is different from the inherent frequency of the microbridge structure and its film layers in the uncooled infrared focal plane detector. This not only avoids the inherent frequency of the microbridge structure and its various film layers, but also ensures the cleaning effect.
[0027] The uncooled infrared focal plane detector chip is first sprayed with deionized water at a pressure of 0.2 MPa to 1 MPa, and then immersed in deionized water. At the same time, the uncooled infrared focal plane detector chip is cleaned a third time.
[0028] The specific implementation process is as follows: The uncooled infrared focal plane detector wafer is first sprayed with deionized water at a pressure of 0.2 MPa to 1 MPa. This spraying is primarily for initial tension control and to enhance the buffering effect between the deionized water and the microbridge structure. Then, the uncooled infrared focal plane detector wafer is immersed in deionized water, simultaneously undergoing a third cleaning. In a preferred embodiment, the immersion time in deionized water is 40 to 60 minutes, and the solution temperature during immersion is 55°C to 70°C.
[0029] In a preferred embodiment, the deionized water spraying is also divided into two spraying processes. After the first spray, the solution is allowed to stand for more than 1 minute before the second spray, followed by a stand for more than 30 seconds. The first stand for more than 1 minute is primarily to allow the deionized water to neutralize any residual isopropanol solvent, and the first spray is mainly for initial tension control. The isopropanol solvent to be sprayed is then allowed to stand for more than 30 seconds before the second spray, which is mainly to enhance the buffering effect between the solvent and the microbridge structure. The amount and frequency of the first spray are significantly less than those of the second spray.
[0030] After spraying and settling, deionized water is slowly introduced, and the uncooled infrared focal plane detector chip is immersed in the deionized water at room temperature for 5 to 8 minutes. At the same time, mega-acoustic cleaning is performed. The frequency of mega-acoustic cleaning is higher than 1 MHz. The frequency of mega-acoustic cleaning is different from the inherent frequency of the microbridge structure and its film layers in the uncooled infrared focal plane detector. This not only avoids the inherent frequency of the microbridge structure and its various film layers, but also ensures the cleaning effect.
[0031] The uncooled infrared focal plane detector chip is first sprayed with isopropanol solvent at a pressure of 0.2 MPa to 1 MPa, and then immersed in isopropanol solvent, while simultaneously performing a fourth cleaning.
[0032] The specific implementation process is as follows: The uncooled infrared focal plane detector wafer is first sprayed with isopropanol solvent at a pressure of 0.2 MPa to 1 MPa. The spraying is mainly to neutralize the hydroxylamine-containing cleaning solution and enhance the buffering effect between the solvent and the microbridge structure. The isopropanol concentration is above 95%. Then, the uncooled infrared focal plane detector wafer is immersed in isopropanol solvent, simultaneously performing a second cleaning. The immersion time in isopropanol solvent is 10 to 15 minutes.
[0033] In a preferred embodiment, the isopropanol solvent spraying is performed in two stages. After the first spray, the mixture is allowed to stand for more than one minute before the second spray, followed by a stand for more than 30 seconds. The first stand of more than one minute is primarily to allow the isopropanol solvent to neutralize any residual deionized water. The isopropanol solvent, similar to alcohol, readily evaporates, carrying away any remaining deionized water and preventing water stains. The first spray is mainly for initial tension control. The second spray, after allowing the isopropanol solvent to stand for more than 30 seconds, enhances the buffering effect between the isopropanol solvent and the microbridge structure. The amount and frequency of the first spray are significantly less than those of the second spray.
[0034] After spraying and settling, isopropanol solvent is slowly introduced, and the uncooled infrared focal plane detector chip is immersed in the isopropanol solvent at room temperature for 10 to 15 minutes. At the same time, megasonic cleaning is performed. The frequency of megasonic cleaning is higher than 1 MHz. The frequency of megasonic cleaning is different from the inherent frequency of the microbridge structure and its film layers in the uncooled infrared focal plane detector. This not only avoids the inherent frequency of the microbridge structure and its various film layers, but also ensures the cleaning effect.
[0035] The cleaned uncooled infrared focal plane detector wafer is then dried.
[0036] The specific implementation process is as follows: During drying, the drying time at room temperature is more than 30 minutes, and then it is put into the oven for baking at 120℃ for 3 to 5 minutes.
[0037] In a preferred embodiment, the spraying pressure is controlled by adjusting the spraying frequency and the amount of liquid sprayed during the spraying steps, with the spraying pressure maintained between 0.2 MPa and 1 MPa. This achieves the cleaning purpose without damaging the microbridge structure of the uncooled infrared focal plane detector chip.
[0038] In a preferred embodiment, megaphonic cleaning is employed in the cleaning steps, typically using frequencies higher than 1 MHz. The frequency of megaphonic cleaning differs from the inherent frequencies of the microbridge structure and its films in the uncooled infrared focal plane detector. This not only avoids the inherent frequencies of the microbridge structure and its individual films but also ensures effective cleaning.
[0039] The technical effect of this invention is: to provide a cleaning method for a microbridge structure of an uncooled infrared focal plane detector, comprising the following steps: first spraying the uncooled infrared focal plane detector wafer with a hydroxylamine-containing solution, then immersing the uncooled infrared focal plane detector wafer in the hydroxylamine-containing solution, while simultaneously performing a first megaacoustic cleaning; first spraying the uncooled infrared focal plane detector wafer with isopropanol solvent, then immersing the uncooled infrared focal plane detector wafer in isopropanol solvent, while simultaneously performing a second megaacoustic cleaning; first spraying the uncooled infrared focal plane detector wafer with deionized water, then immersing the uncooled infrared focal plane detector wafer in deionized water, while simultaneously performing a third megaacoustic cleaning; first spraying the uncooled infrared focal plane detector wafer with isopropanol solvent, then immersing the uncooled infrared focal plane detector wafer in isopropanol solvent, while simultaneously performing a fourth megaacoustic cleaning; the spraying pressure is 0.2 MPa to 1 MPa. The uncooled infrared focal plane detector wafer is then dried after cleaning. This invention employs a combined spraying and immersion method to ensure the integrity of the microbridge structure while also guaranteeing a suitable cleaning environment.
[0040] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.
Claims
1. A method for cleaning the microbridge structure of an uncooled infrared focal plane detector, wherein the microbridge structure of the uncooled infrared focal plane detector to be cleaned includes a suspended structure formed by a release process, characterized in that, Includes the following steps: The uncooled infrared focal plane detector chip is first sprayed with a hydroxylamine-containing solution at a pressure of 0.2 MPa to 1 MPa, and then immersed in the hydroxylamine-containing solution, which also performs the first cleaning of the uncooled infrared focal plane detector chip. The uncooled infrared focal plane detector chip is first sprayed with isopropanol solvent at a pressure of 0.2 MPa to 1 MPa, and then the uncooled infrared focal plane detector chip is immersed in isopropanol solvent, while the uncooled infrared focal plane detector chip is cleaned a second time. The uncooled infrared focal plane detector chip is first sprayed with deionized water at a pressure of 0.2 MPa to 1 MPa, and then immersed in deionized water. At the same time, the uncooled infrared focal plane detector chip is cleaned for the third time. The uncooled infrared focal plane detector chip is first sprayed with isopropanol solvent at a pressure of 0.2 MPa to 1 MPa, and then the uncooled infrared focal plane detector chip is immersed in isopropanol solvent, while the uncooled infrared focal plane detector chip is cleaned for the fourth time. The cleaned uncooled infrared focal plane detector wafer is then dried. When cleaning the uncooled infrared focal plane detector chip, mega-acoustic cleaning is used. The spray pressure is controlled by controlling the spray frequency and the amount of spray liquid. The frequency of mega-acoustic cleaning is different from the inherent frequency of the microbridge structure and the film layer in the uncooled infrared focal plane detector. At the same time, the frequency of mega-acoustic cleaning can achieve the cleaning effect.
2. The cleaning method for the microbridge structure of the uncooled infrared focal plane detector according to claim 1, characterized in that, The solution containing hydroxylamine was sprayed twice. After the first spray, the solution was allowed to stand for more than 1 minute before the second spray was performed, and then the solution was allowed to stand for more than 30 seconds.
3. The cleaning method for the microbridge structure of the uncooled infrared focal plane detector according to claim 1, characterized in that, The microbridge wafer of the uncooled infrared focal plane detector was immersed in a cleaning solution containing hydroxylamine for 40 to 60 minutes at a temperature of 55°C to 70°C.
4. The cleaning method for the microbridge structure of the uncooled infrared focal plane detector according to claim 1, characterized in that, The process involves spraying with isopropanol solvent in two stages. After the first spray, the mixture is allowed to stand for more than 1 minute before the second spray, and then allowed to stand for more than 30 seconds.
5. The cleaning method for the microbridge structure of the uncooled infrared focal plane detector according to claim 1, characterized in that, The uncooled infrared focal plane detector chip was immersed in isopropanol solvent for 10 to 15 minutes.
6. The cleaning method for the microbridge structure of the uncooled infrared focal plane detector according to claim 1, characterized in that, The uncooled infrared focal plane detector chip was immersed in deionized water for 5 to 8 minutes.
7. The cleaning method for the microbridge structure of the uncooled infrared focal plane detector according to claim 1, characterized in that, During drying, the drying time should be greater than 30 minutes at room temperature, and then the product should be baked in an oven at 120℃ for 3 to 5 minutes.