Refrigeration type infrared detector chip structure and preparation method thereof
Patent Information
- Application Number
- CN202611112186.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-24
- Publication Date
- 2026-10-27
AI Technical Summary
[0005]现有红外探测器芯片结构中，产生热量的读出电路与需要保持低温的红外光敏芯片直接接触，读出电路工作时产生局部的热量，会导致红外光敏芯片区域性温度变化，进而影响探测器性能
本申请提出了一种制冷型红外探测器芯片结构，此结构将需要保持稳定低温的红外光敏芯片和读出电路分置于冷量传输层两面。利用冷量传输结构两面冷量传输效率的差异，实现红外光敏芯片高冷量传输，读出电路低冷量传输，对红外光敏芯片和读出电路实现分别控温。本申请的方案利用读出电路可高温工作，对冷量需求极低的特点，既保证的红外光敏芯片的稳定低温需求，又降低了红外探测器芯片的总冷量需求，解决了传统红外探测器冷量传输先经过读出电路，冷量被电路无效消耗后到达红外芯片的制冷效率低问题，为实现高性能红外探测器组件小型化提供了解决方案。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor processing technology in microelectronics, and in particular to a cooled infrared detector chip structure and its fabrication method. Background Technology
[0002] Infrared focal plane array technology has significant advantages such as wide spectral response band, ability to obtain more information about ground targets, and ability to work day and night. It is widely used in fields such as agricultural and animal husbandry, forest resource surveys, development and management, weather forecasting, geothermal distribution, earthquakes, volcanic activity, and space astronomical exploration.
[0003] The infrared focal plane detector is mainly composed of a detector chip (photosensitive chip), readout circuit, metal Dewar, refrigerator and processing circuit. The detector chip and readout circuit are interconnected by flip chip to form a chip set packaged in the metal Dewar. The refrigerator provides the low temperature environment required for the detector to work.
[0004] With the development of technology, the trend of miniaturization, integration and intelligence of infrared detectors has gradually deepened. Under this trend, the design of readout circuits with more complex functions, higher operating frequencies and stronger signal response rates have led to a significant increase in the power consumption per unit area of infrared detectors. The higher thermal power consumption not only puts forward higher requirements for the cooling capacity of the refrigerator, but also directly affects the continuity, stability and reliability of the detector's high-performance operation. Therefore, the design of infrared detector chip structure that is easier to achieve efficient cooling has become the key to improving the performance of infrared detectors and further miniaturization, integration and intelligence.
[0005] In existing infrared detector chip structures, the heat-generating readout circuit is in direct contact with the infrared photosensitive chip, which needs to be kept at a low temperature. The readout circuit generates localized heat during operation, causing regional temperature variations in the infrared photosensitive chip and consequently affecting detector performance. Furthermore, due to the limitations of traditional infrared detector chip structures, the cooling energy generated by the infrared detector's cooling system must be transferred through the readout circuit, resulting in a significant amount of cooling energy being consumed within the silicon-based readout circuit, which requires little or no cooling. Summary of the Invention
[0006] To address the shortcomings of the existing technology, this invention provides a cooled infrared detector chip structure and its fabrication method, employing the following technical solution: In a first aspect, a cooled infrared detector chip structure is provided, comprising: A cold energy transfer layer is fabricated on which a metal via array is arranged in the same way as the pixels of the infrared photosensitive chip. An infrared photosensitive chip is disposed on the first surface of the cold energy transfer layer, and the pixels of the infrared photosensitive chip are electrically bonded to the metal via array. A readout circuit is disposed on the second surface of the cold energy transfer layer opposite to the first surface. The readout circuit is electrically connected to the metal via array through metal bumps. A gap exists between the cold energy transfer layer and the readout circuit, and the gap is filled with a material for isolating cold energy. The efficiency of the cold energy transfer layer in transferring cold energy to the infrared photosensitive chip is higher than that in transferring cold energy to the readout circuit, thereby enabling separate temperature control for the infrared photosensitive chip and the readout circuit.
[0007] In a second aspect, a method for fabricating a cooled infrared detector chip structure is provided, comprising: A metal via array and a double-sided alignment mark are fabricated on a cold energy transfer layer, penetrating its first and second surfaces; the infrared photosensitive chip of the metal via array has the same pixel arrangement. The pixel electrodes of the infrared photosensitive chip are aligned with the metal vias on the first surface of the cold energy transfer layer according to the double-sided alignment marks, and then electrically connected and bonded. Metal bumps are fabricated on the second surface of the cold energy transfer layer and on the readout circuit, respectively. The readout circuit is connected to the second surface of the cold energy transfer layer via the metal bumps using a flip-chip interconnect process. The gap between the cold energy transfer layer and the readout circuit is filled with a material for insulating against cold energy.
[0008] This application has the following beneficial effects: This application proposes a cooled infrared detector chip structure. This structure separates the infrared photosensitive chip, which requires a stable low temperature, and the readout circuit, placing them on opposite sides of a cold energy transfer layer. By utilizing the difference in cold energy transfer efficiency between the two sides of the cold energy transfer structure, high cold energy transfer is achieved for the infrared photosensitive chip, while low cold energy transfer is achieved for the readout circuit, enabling separate temperature control for both. This solution leverages the readout circuit's ability to operate at high temperatures with extremely low cold energy requirements, ensuring the stable low temperature requirement of the infrared photosensitive chip while reducing the overall cold energy requirement of the infrared detector chip. It solves the problem of low cooling efficiency in traditional infrared detectors, where cold energy transfer first passes through the readout circuit, resulting in inefficient cooling before reaching the infrared chip. This provides a solution for miniaturizing high-performance infrared detector components. Attached Figure Description
[0009] Figure 1 This is a schematic diagram of a conventional infrared detector chip structure provided in an embodiment of this application; Figure 2 This is a schematic diagram of a cooled infrared detector chip structure provided in an embodiment of this application; Figure 3 A top view of a cooled infrared detector chip structure provided in an embodiment of this application; Figure 4 A schematic diagram of a cold energy transfer path provided in an embodiment of this application; Figure 5 A schematic diagram of a metal via array on the surface of a cold energy transfer layer provided in an embodiment of this application; Figure 6 A front view of a cold energy transport layer provided in an embodiment of this application; Figure 7 A side view of a cold energy transfer layer provided in an embodiment of this application; Figure 8 A schematic diagram illustrating the bonding of an infrared photosensitive chip to a cold energy transport layer, provided as an embodiment of this application; Figure 9 A schematic diagram of a cold energy transfer layer with metal bumps provided in an embodiment of this application; Figure 10 A schematic diagram of a readout circuit with metal bumps on its surface provided in an embodiment of this application; Figure 11 A schematic diagram illustrating the connection between a readout circuit and a cold energy transfer layer, provided in an embodiment of this application; Figure 12 This is a schematic diagram of an epoxy resin filling between a readout circuit and a cold energy transfer layer, provided in an embodiment of this application. Detailed Implementation
[0010] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the technical solutions in the embodiments of this application are clearly described. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art are within the scope of protection of this application.
[0011] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.
[0012] The steps described in this application and the flowcharts in the accompanying drawings are not necessarily strictly executed according to the step numbers; the execution order of the steps can be changed. Furthermore, certain steps can be omitted, multiple steps can be combined into one step, and / or one step can be broken down into multiple steps.
[0013] With technological advancements, the readout circuitry of infrared detectors has become more complex and operates at higher frequencies, leading to increased power consumption and heat generation and a greater demand for cooling. Existing infrared detector chip structures, due to thermal coupling between the readout circuitry and the photosensitive chip, are unsuitable for next-generation high-performance readout circuits. Some related technologies employ an indium pillar array between the photosensitive element array and the readout circuitry, filling the gaps between the indium pillars with adhesive. However, these solutions still fail to address the thermal impact of the readout circuitry's heat generation on the photosensitive chip and the ineffective loss of cooling during transmission.
[0014] Based on this, a cooled infrared detector chip structure is provided in this specification, which will be described in detail below with reference to the accompanying drawings and preferred embodiments.
[0015] Please see Figure 1-12 This application provides a cooled infrared detector chip structure, including: A cold energy transfer layer is fabricated on which a metal via array is arranged in the same way as the pixel arrangement of the infrared photosensitive chip. An infrared photosensitive chip is disposed on the first surface of the cold energy transfer layer, and the pixels of the infrared photosensitive chip are electrically bonded to the metal via array. A readout circuit is disposed on the second surface of the cold energy transfer layer opposite to the first surface. The readout circuit is electrically connected to the metal via array through metal bumps. A gap exists between the cold energy transfer layer and the readout circuit, and the gap is filled with a material for isolating cold energy. The efficiency of the cold energy transfer layer in transferring cold energy to the infrared photosensitive chip is higher than that in transferring cold energy to the readout circuit, thereby enabling separate temperature control for the infrared photosensitive chip and the readout circuit.
[0016] Based on the above scheme, this application places the infrared photosensitive chip and the readout circuit, which require stable low temperatures, on opposite sides of the cold energy transfer layer. Utilizing the different operating temperatures of the readout circuit and the infrared photosensitive chip, the two chips are cooled separately. By leveraging the difference in cold energy transfer efficiency between the two sides of the cold energy transfer layer, high cold energy transfer is achieved for the infrared photosensitive chip, while low cold energy transfer is achieved for the readout circuit. This allows for separate temperature control of the infrared photosensitive chip and the readout circuit, significantly reducing the chip's cold energy requirements. To ensure efficient cold energy transfer to the infrared photosensitive chip, the electrical leads of the infrared chip are first bonded to the cold energy transfer layer. Then, the electrical signal generated by the infrared photosensitive chip is transmitted to the other side of the cold energy transfer layer through a straight metal via. Finally, the readout circuit is connected to the cold energy transfer layer via metal bumps to read and output the photosensitive chip signal. Since the readout circuit and the cold energy transfer layer are only connected by metal bumps, and an insulating layer is electrically filled inside the gap between the circuit and the cold energy transfer layer for heat insulation and improved reliability, the cold energy inside the cold energy transfer layer is concentrated on cooling the infrared photosensitive chip, with only a small amount transferred to the readout circuit. This ensures the stable low-temperature requirements of the infrared photosensitive chip, avoids the heat generated by the readout circuit affecting the performance of the infrared photosensitive chip, and reduces the total cooling requirements of the infrared detector chip.
[0017] Furthermore, the metal via array is an array structure with internally filled metal that is electrically isolated from each other.
[0018] Furthermore, the infrared photosensitive chip is permanently bonded to the cold energy transfer layer. The cold energy transfer layer is tightly bonded to the infrared photosensitive chip, resulting in high cold energy transfer efficiency.
[0019] Furthermore, the material filling the gap is epoxy resin, which is used to isolate cold energy transmission while improving structural reliability.
[0020] Furthermore, the metal bumps are made of copper or aluminum. Since the readout circuit does not need to be kept at a low temperature, the metal sites required for the interconnection on the circuit surface can use low-resistance metals such as copper and aluminum.
[0021] In some possible implementations, the cold transfer layer can be configured as a cold conduction substrate, specifically a plate-shaped thermally conductive substrate, for transferring the cold energy of the refrigerator.
[0022] Corresponding to the above-described cooled infrared detector chip structure embodiment, this application embodiment provides a method for fabricating the above-described cooled infrared detector chip structure, including: Step 1: Prepare a metal via array and a double-sided alignment mark that penetrate the first and second surfaces of a cold energy transfer layer; the infrared photosensitive chip of the metal via array has the same pixel arrangement.
[0023] Specifically, such as Figure 5-7As shown, through-hole arrays of internally filled metals that are electrically isolated from each other and double-sided alignment marks are prepared on the surface of the cold energy transport layer using methods such as photolithography, reactive particle etching, and electroplating.
[0024] Step 2: Align the pixel electrode of the infrared photosensitive chip with the metal via on the first surface of the cold energy transfer layer according to the double-sided alignment mark, and then electrically connect and bond them together.
[0025] Specifically, such as Figure 8 As shown, the infrared photosensitive chip pixel is aligned with the metal via on the surface of the cold energy readout structure according to the alignment mark, the via is electrically connected to the pixel, and then permanent bonding is performed; thus realizing the electrical connection and physical connection between the infrared photosensitive chip and the cold energy transfer layer.
[0026] Step 3: Prepare metal bumps on the second surface of the cold energy transfer layer and on the readout circuit, respectively.
[0027] Specifically, such as Figure 9-10 As shown, low-resistance metal bumps such as copper and aluminum are fabricated on the other side of the readout circuit and the cold energy transfer layer.
[0028] Step 4: Using a flip-chip interconnect process, connect the readout circuit to the second surface of the cold energy transfer layer via the metal bumps.
[0029] Specifically, such as Figure 11 As shown, flip-chip interconnects are used to connect the readout circuitry to the cold charge transfer layer via metal bumps.
[0030] Step 5: Fill the gap between the cold energy transfer layer and the readout circuit with a material for insulating against cold energy.
[0031] Specifically, such as Figure 12 As shown, epoxy resin is filled in the gap between the cold energy transfer layer and the readout circuit to isolate the cold energy and improve reliability.
[0032] The above-described method for fabricating a cooled infrared detector chip structure achieves the steps and processes of the embodiments described above, and can achieve the same technical effect. To avoid repetition, it will not be described again here.
[0033] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.
[0034] It is understood that the embodiments of this application have been described above in conjunction with the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. As those skilled in the art will know, various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, those skilled in the art, under the guidance or instruction of this application, can modify these features and embodiments to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, this invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of this invention.
Claims
1. A cooled infrared detector chip structure, characterized in that, include: A cold energy transfer layer is fabricated on which a metal via array is arranged in the same way as the pixels of the infrared photosensitive chip. An infrared photosensitive chip is disposed on the first surface of the cold energy transfer layer, and the pixels of the infrared photosensitive chip are electrically bonded to the metal via array. A readout circuit is disposed on the second surface of the cold energy transfer layer opposite to the first surface. The readout circuit is electrically connected to the metal via array through metal bumps. A gap exists between the cold energy transfer layer and the readout circuit, and the gap is filled with a material for isolating cold energy. The efficiency of the cold energy transfer layer in transferring cold energy to the infrared photosensitive chip is higher than that in transferring cold energy to the readout circuit, thereby enabling separate temperature control for the infrared photosensitive chip and the readout circuit.
2. The cooled infrared detector chip structure according to claim 1, characterized in that, The metal via array is an array structure filled with internal metal that is electrically isolated from each other.
3. The cooled infrared detector chip structure according to claim 1, characterized in that, The infrared photosensitive chip is permanently bonded to the cold energy transfer layer.
4. The cooled infrared detector chip structure according to claim 1, characterized in that, The gap is filled with epoxy resin, which is used to isolate cold energy transmission while improving structural reliability.
5. The cooled infrared detector chip structure according to claim 1, characterized in that, The metal bumps are made of copper or aluminum.
6. A method for fabricating a cooled infrared detector chip structure, characterized in that, Fabricating a cooled infrared detector chip structure as described in any one of claims 1-5, comprising: A metal via array and a double-sided alignment mark are fabricated on a cold energy transfer layer, penetrating its first and second surfaces; the infrared photosensitive chip of the metal via array has the same pixel arrangement. The pixel electrodes of the infrared photosensitive chip are aligned with the metal vias on the first surface of the cold energy transfer layer according to the double-sided alignment marks, and then electrically connected and bonded. Metal bumps are fabricated on the second surface of the cold energy transfer layer and on the readout circuit, respectively. The readout circuit is connected to the second surface of the cold energy transfer layer via the metal bumps using a flip-chip interconnect process. The gap between the cold energy transfer layer and the readout circuit is filled with a material for insulating against cold energy.