Wafer for heightening and infrared detector

Abstract

The utility model discloses a wafer for heightening and an infrared detector, which are applied to the field of infrared detection, and the wafer for heightening is an integrally formed wafer structure. The wafer for heightening comprises a first surface close to the device wafer and a second surface close to the window wafer; the wafer for heightening comprises an infrared light passing area, and a through hole corresponding to the active area of the device wafer is formed in the infrared light passing area in the direction from the first surface to the second surface. According to the utility model, the height-increasing wafer is prepared by integrally forming the wafer, so that the problem that the height of the wall body is limited when the wall body and the infrared window are produced and prepared by using one wafer can be avoided, and when a device is prepared by using wafer-level packaging, the height of the wall body can be increased on the basis of ensuring the preparation efficiency through the integrally-formed height-increasing wafer provided by the utility model. And the distance between the infrared window and the focal plane is increased, so that the influence of the window light-passing area defect on the detection imaging quality is weakened, and the detection accuracy is improved.

Description

Technical Field

[0001] The utility model relates to the field of infrared detection, and particularly to a wafer for heightening and an infrared detector. Background Art

[0002] With the rapid development of the semiconductor industry, wafer-level packaging has gradually become the mainstream of chip packaging. Taking the uncooled infrared detector as an example, its wafer-level packaging takes the wafer as the processing object, and a large number of chips are simultaneously packaged on the wafer to form a detector and aging tests are carried out. Compared with the traditional packaging form, wafer-level packaging has the advantages of high efficiency, short cycle, low cost, etc. However, its infrared window is closer to the focal plane, resulting in a large impact of the window light-transmitting area defect on the detection imaging quality, seriously restricting the yield of wafer-level packaging and the application of the detector. At present, in the conventional scheme of wafer-level packaging, a wall is prepared to keep the distance between the infrared window and the focal plane. However, the existing wall and the infrared window are produced and prepared in a single wafer. Due to the design and process limitations on the height of the wall, the defect in the window light-transmitting area affects the detection imaging quality.

[0003] Therefore, how to provide a solution to weaken the impact of the window light-transmitting area defect on the detection imaging quality on the basis of the wafer-level packaging process is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Utility Model

[0004] In view of this, the purpose of the utility model is to provide a wafer for heightening and an infrared detector, which solve the problem that in the prior art, the wall and the infrared window are produced and prepared in a single wafer, and due to the design and process limitations on the height of the wall, the infrared window is closer to the focal plane, resulting in the defect in the window light-transmitting area affecting the detection imaging quality.

[0005] To solve the above technical problem, the utility model provides a wafer for heightening, and the wafer for heightening is a wafer structure formed integrally.

[0006] The wafer for heightening includes a first surface facing the device wafer and a second surface facing the window wafer.

[0007] The wafer for heightening includes an infrared light passing area, and through holes corresponding to the active areas of the device wafer are arranged in the infrared light passing area along the direction from the first surface to the second surface.

[0008] Optionally, the area outside the infrared light passing area at the first surface includes a bonding area and a scribe lane area.

[0009] A concave structure is formed at the scribe lane area.

[0010] Optionally, the depth of the recessed structure is one fifth of the total thickness of the wafer for heightening.

[0011] Optionally, the total thickness of the wafer for heightening is 100 microns to 1000 microns;

[0012] The depth of the recessed structure is 20 microns to 200 microns.

[0013] Optionally, the wafer for heightening is a silicon wafer for heightening, or a germanium wafer for heightening, or a glass wafer for heightening.

[0014] The present utility model further provides an infrared detector, comprising a device wafer, a window wafer and a wall;

[0015] The wall comprises the wafer for heightening as described above;

[0016] The device wafer is bonded to the first surface of the wafer for heightening, and the window wafer is bonded to the side of the wall facing away from the device wafer;

[0017] The through hole in the wafer for heightening corresponds to the active region of the device wafer.

[0018] Optionally, the wall comprises a plurality of stacked wafers for heightening.

[0019] Optionally, a getter is provided on the side wall of the through hole in the wafer for heightening.

[0020] Optionally, the getter is provided on the inner surface of the window wafer corresponding to the region other than the active region of the device wafer.

[0021] Optionally, a first welding layer is provided in the region where the device wafer is bonded to the first surface of the wafer for heightening;

[0022] A second welding layer is provided in the region where the window wafer is bonded to the side of the wall facing away from the device wafer;

[0023] The melting point temperature of the first welding layer is different from that of the second welding layer.

[0024] It can be seen that the wafer for height increase provided by the present utility model is a wafer structure formed integrally. The wafer for height increase includes a first surface facing the device wafer and a second surface facing the window wafer. The wafer for height increase includes an infrared light passing area, and through holes corresponding to the active area of the device wafer are arranged in the infrared light passing area along the direction from the first surface to the second surface. By using integral wafer forming to prepare the wafer for height increase, the present utility model can avoid the problem that the height of the wall is limited when using a single wafer to produce and prepare the wall and the infrared window. Moreover, when applying wafer-level packaging to prepare devices, the wafer for height increase prepared by integral forming in the present utility model can, on the basis of ensuring the preparation efficiency, increase the distance between the infrared window and the focal plane, thereby reducing the influence of the defects in the window light passing area on the detection imaging quality and improving the detection accuracy.

[0025] In addition, the present utility model also provides an infrared detector, which also has the above beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0027] Figure 1 FIG. 1 is a schematic structural diagram of a wafer for height increase provided by an embodiment of the present utility model;

[0028] Figure 2 FIG. 2 is a top view structural diagram of a wafer for height increase provided by an embodiment of the present utility model;

[0029] Figure 3 FIG. 3 is a schematic structural diagram of an infrared detector provided by an embodiment of the present utility model;

[0030] Figure 4 FIG. 4 is an exemplary diagram of a method for preparing an infrared detector provided by an embodiment of the present utility model;

[0031] Figures 1 to 4 In the figures, the reference numerals are explained as follows:

[0032] 1 - Wall, 2 - Device wafer, 3 - Window wafer, 11 - First surface, 12 - Second surface, 13 - Welding layer, 131 - First welding layer, 132 - Second welding layer, 21 - Focal plane;

[0033] 10 - Through hole, 20 - Bonding area, 30 - Depressed structure, 40 - Getter. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Apparently, the described embodiments are only a part rather than all of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0035] Please refer to Figure 1 , Figure 1 , which is a schematic structural diagram of a wafer for heightening provided by an embodiment of the present utility model. The wafer for heightening can be set as an integrally formed wafer structure;

[0036] The wafer for heightening includes a first surface 11 facing the device wafer and a second surface 12 facing the window wafer;

[0037] The wafer for heightening includes an infrared light passing area. In the infrared light passing area, a through hole 10 corresponding to the active area of the device wafer is provided along the direction from the first surface 11 to the second surface 12.

[0038] It should be noted that in this embodiment, a welding layer 13 can be provided in the bonding area 20 for wafer-level bonding connection with the device wafer or the window wafer. In this embodiment, the wafer for heightening is provided corresponding to the device wafer and the window wafer to prepare an infrared detection structure, that is, in this embodiment, the first surface 11 of the wafer for heightening faces the device wafer, the second surface 12 faces the window wafer, and in the infrared light passing area of the wafer for heightening, a through hole 10 is provided corresponding to the active area of the device wafer. Generally, the through hole 10 is directly opposite to the active area of the device wafer, and further, the infrared light entering from the window wafer passes through the through hole 10 and irradiates the active area of the device wafer, and the infrared light is detected. In this embodiment, the infrared light passing area, that is, the area through which the infrared light incident from the window wafer finally reaches the active area on the surface of the device wafer, generally, the infrared light passing area is set as the area where the through hole 10 is located in the above-mentioned wafer for heightening. In addition, the wafer for heightening is prepared by integrally forming the entire wafer to form the wafer for heightening, that is, the wafer for heightening is provided corresponding to multiple active areas on the surface of the device wafer. Specifically, the through holes 10 in the wafer for heightening correspond one by one to all the active areas on the surface of the device wafer, improving the preparation and laying efficiency of the wafer for heightening. In this embodiment, the wafer for heightening can also refer to Figure 2 , Figure 2 , which is a top view structural diagram of a wafer for heightening provided by an embodiment of the present utility model. In addition, in this embodiment, the active area of the above-mentioned device wafer is the pixel area of the infrared detection device.

[0039] In a specific embodiment, the first surface 11 of the above-mentioned height-increasing wafer can be bonded to the device wafer, and the second surface 12 of the above-mentioned height-increasing wafer can be bonded to the window wafer. That is, in the infrared detection structure formed at this time, only one layer of height-increasing wafer is provided between the window wafer and the device wafer. In addition, in this embodiment, the through holes 10 of the window wafer, the device wafer, and the height-increasing wafer are cooperatively arranged to form a sealed vacuum cavity structure.

[0040] Further, in order to avoid damaging and injuring the device wafer during subsequent dicing, it is possible to set the area outside the infrared light passing area at the first surface 11, including the bonding area 20 and the scribe lane area;

[0041] A recessed structure 30 is formed at the scribe lane area.

[0042] It should be noted that in this embodiment, after the height-increasing wafer, the device wafer, and the window wafer are matched and connected, during subsequent dicing, it is necessary to first cut the window wafer and the height-increasing wafer and expose the pads on the surface of the device wafer for external conductive connection. However, due to limited precision during the dicing process, the device wafer is easily scratched and damaged. Therefore, in this embodiment, by setting the recessed structure 30 in the scribe lane area at the first surface 11 of the height-increasing wafer, when dicing the window wafer and the height-increasing wafer, it can stop at a certain distance from the device wafer to avoid scratching the device wafer, and a cavity is formed between the recessed structure 30 and the device wafer during packaging.

[0043] In this embodiment, it is possible to set the first surface 11 of the height-increasing wafer to be composed of an infrared light passing area, a bonding area 20, and a scribe lane area. The through holes 10 are provided at the infrared light passing area, the bonding area 20 is used for bonding to the device wafer, and the scribe lane area corresponds to the metal pad area on the surface of the device wafer. During subsequent dicing, the dicing is performed at the dicing area, specifically at the formed recessed structure 30, to avoid damaging the device wafer.

[0044] Further, in order to ensure that the device wafer is not scratched during dicing and to ensure the preparation yield, the depth of the above-mentioned recessed structure 30 can be set to one-fifth of the total thickness of the height-increasing wafer.

[0045] It should be noted that in this embodiment, by setting the depth of the recessed structure 30 to one-fifth of the total thickness of the height-increasing wafer, while balancing the preparation efficiency of the height-increasing wafer, it also avoids damaging the device wafer during dicing and ensures the preparation yield.

[0046] Further, in order to ensure that the device wafer is not damaged during dicing of the window wafer and the height-increasing wafer, to ensure the adaptability of the height-increasing wafer and facilitate preparation, the total thickness of the above-mentioned height-increasing wafer can be set to 100 microns to 1000 microns;

[0047] The depth of the recessed structure 30 can be correspondingly set to be from 20 micrometers to 200 micrometers.

[0048] It should be noted that in this embodiment, the total thickness of the wafer for heightening is set to be from 100 micrometers to 1000 micrometers, and correspondingly, the recessed structure 30 is set to be from 20 micrometers to 200 micrometers, that is, the thickness of the above-mentioned recessed structure 30 always remains one-fifth of the total thickness of the wafer for heightening.

[0049] Furthermore, in order to ensure that when the wafer for heightening is installed between the device wafer and the window wafer, only the distance between the two is increased and other functions are not affected, the above-mentioned wafer for heightening can be set as a silicon wafer for heightening, or a germanium wafer for heightening, or a glass wafer for heightening.

[0050] In a feasible embodiment, the method for fabricating the above-mentioned wafer for heightening may include the following steps:

[0051] S101: Provide a wafer preform.

[0052] It should be noted that in this embodiment, the wafer preform can be a wafer substrate structure without a fabricated functional layer. In this embodiment, the wafer structure is processed to form a special morphology to be used as the wafer for heightening.

[0053] S102: Set through holes in the wafer preform in the direction from the first surface to the second surface corresponding to the infrared light passing area to complete the fabrication of the wafer for heightening; the first surface is the surface of the wafer preform that faces the device wafer after the wafer for heightening is fabricated; the second surface is the surface of the wafer preform that faces the window wafer after the wafer for heightening is fabricated; the infrared light passing area is the area of the wafer preform corresponding to the active area of the device wafer.

[0054] It should be noted that in this embodiment, through holes are opened in the provided wafer preform corresponding to the infrared light passing area to complete the fabrication of the wafer for heightening. Among them, when the through holes are connected to the device wafer in a matching manner, the through holes correspond to the active areas of the device wafer. Specifically, each through hole corresponds to one active area.

[0055] Furthermore, in order to avoid damage and injury to the device wafer during subsequent dicing, it may further include:

[0056] Fabricate a recessed structure at the scribing lane area divided in the area outside the infrared light passing area on the first surface.

[0057] It should be noted that the specific process for preparing the concave structure in this embodiment is not limited. For example, it can be carried out before preparing the through-hole, that is, the step of "preparing the concave structure at the scribe lane area divided in the area outside the infrared light passing area of the first surface" is executed before the above step S102. Or, after setting the through-hole corresponding to the active area of the device wafer in the wafer preform along the direction from the first surface to the second surface, the above concave structure can be prepared to complete the preparation of the wafer for heightening.

[0058] The wafer for heightening provided by the embodiment of the present invention is an integrally formed wafer structure. The wafer for heightening includes a first surface 11 facing the device wafer and a second surface 12 facing the window wafer. The wafer for heightening includes an infrared light passing area, and through-holes 10 corresponding to the active areas of the device wafer are provided in the infrared light passing area along the direction from the first surface 11 to the second surface 12. By using the integrally formed wafer to prepare the wafer for heightening, the present invention can avoid the problem that the height of the wall is limited when using a single wafer to produce and prepare the wall and the infrared window. And when applying wafer-level packaging to prepare devices, based on ensuring the preparation efficiency, the distance between the infrared window and the focal plane is increased by the integrally formed wafer for heightening in the present invention, thereby weakening the influence of the defects in the window light passing area on the detection imaging quality and improving the detection accuracy.

[0059] In addition, in the embodiment of the present invention, a concave structure 30 is provided in the scribe lane area on the first surface 11 of the wafer for heightening. When scribing, the cutting of the window wafer and the wafer for heightening can stop at a certain distance from the device wafer to avoid scratching the device wafer; by setting the depth of the concave structure 30 to one-fifth of the total thickness of the wafer for heightening, while balancing the preparation efficiency of the wafer for heightening, it also avoids damaging the device wafer during scribing and ensures the preparation yield; the total thickness of the wafer for heightening is set to be 100 microns to 1000 microns, and correspondingly, the concave structure 30 is set to be 20 microns to 200 microns, and the thickness of the concave structure 30 always remains one-fifth of the total thickness of the wafer for heightening, ensuring that the device wafer will not be damaged when scribing the window wafer and the wafer for heightening, ensuring the adaptability of the wafer for heightening and facilitating the preparation; the wafer for heightening is set to be a silicon wafer for heightening, or a germanium wafer for heightening, or a glass wafer for heightening, ensuring that when the wafer for heightening is installed between the device wafer and the window wafer, only the distance between the two is increased and other functions are not affected.

[0060] Next, an infrared detector provided by the embodiment of the present invention will be introduced. The infrared detector described below can be mutually referred to with the wafer for heightening described above.

[0061] Specifically, please refer to Figure 3 , Figure 3The structural schematic diagram of an infrared detector provided by an embodiment of the present utility model may include:

[0062] A device wafer 2, a window wafer 3, and a wall body 1;

[0063] The wall body 1 includes the wafer for heightening as described above;

[0064] The device wafer 2 is bonded to the first surface of the wafer for heightening, and the window wafer 3 is bonded to the side of the wall body 1 facing away from the device wafer 2;

[0065] The through hole in the wafer for heightening corresponds to the active region of the device wafer 2.

[0066] It should be noted that in this embodiment, the wall body 1 includes at least one wafer for heightening. The wafer for heightening is an integrally formed wafer structure, including at least a first surface facing the device wafer 2 and a second surface facing the window wafer 3. The wafer for heightening includes an infrared light passing region, and through holes corresponding to the active region of the device wafer 2 are arranged in the infrared light passing region along the direction from the first surface to the second surface. In this embodiment, the wall body 1 is used to adjust the distance between the window wafer 3 and the device wafer 2 to avoid the focal plane distance between the infrared window of the infrared detector and the surface of the device wafer 2 being relatively close, resulting in a large impact on the detection imaging quality by the defects in the window light passing area. One side of the wall body 1 is bonded and connected to the device wafer 2, and the other side is bonded and connected to the window wafer 3. At the same time, the first surface of the wafer for heightening is arranged on one side of the wall body 1 to bond the first surface of the wafer for heightening to the device wafer 2, and the through holes arranged in the wafer for heightening are correspondingly arranged with the active region in the device wafer 2, so that the infrared light entering through the window wafer 3 reaches the active region of the device wafer 2 through the through holes. It should be noted that in a specific implementation manner, other functional layers may also be added outside the wafer for heightening exposed on one side of the wall body 1. At this time, the functional layer outside the wafer for heightening is bonded and connected to the device wafer 2. It should be noted that in this embodiment, a welding layer 13 is arranged in the bonding region for wafer-level bonding, and a focal plane 21 for receiving infrared light exists at the active region of the device wafer 2.

[0067] Further, in order to increase the thickness range of the wall body 1, it may be set that the above-mentioned wall body 1 includes a plurality of stacked wafers for heightening.

[0068] It should be noted that in this embodiment, when the wall body 1 includes a plurality of stacked wafers for heightening, the overall height of the wall body 1 can be adjusted according to the number of the wafers for heightening arranged, thereby increasing the flexibility of the setting of the wall body 1.

[0069] Further, in order to improve the detection accuracy of the infrared detector, it may be set that a getter 40 is arranged on the side wall of the through hole in the above-mentioned wafer for heightening.

[0070] It should be noted that in this embodiment, by disposing a getter 40 on the sidewall of the through hole of the height-increasing wafer, it is possible to ensure that the cavity is in a vacuum structure after final packaging, thereby improving the detection accuracy of the infrared detector. Further, a getter 40 can also be disposed on the inner surface of the window wafer 3.

[0071] Further, in order to increase the laying area of the getter 40, it can be set that the inner surface of the window wafer 3 corresponding to the area outside the active region of the device wafer 2 is provided with a getter 40.

[0072] It should be noted that in this embodiment, a getter 40 is simultaneously disposed on the inner surface of the window wafer 3 corresponding to the area outside the active region of the device wafer 2, further ensuring a vacuum between the window wafer 3 and the device wafer 2 and improving the detection accuracy.

[0073] Further, in order to ensure the smooth progress of the bonding connection, a first welding layer is provided in the bonding region of the first surface of the device wafer 2 and the height-increasing wafer;

[0074] A second welding layer is provided in the bonding region of the window wafer 3 and the side of the wall body 1 facing away from the device wafer 2;

[0075] The melting point temperature of the first welding layer is different from that of the second welding layer.

[0076] It should be noted that when the steps of wafer-level bonding processing are performed step by step in this embodiment, the melting point temperature of the welding layer for the first wafer-level bonding processing can be set to be higher than that of the welding layer for the subsequent wafer-level bonding processing, so as to avoid melting the welding layer during the first wafer-level bonding processing when performing the subsequent wafer-level bonding, thereby ensuring the smooth completion of the wafer-level bonding. That is, the melting point temperature of the first welding layer is different from that of the second welding layer to facilitate wafer-level bonding and avoid packaging failure when bonding step by step. In this embodiment, both the first welding layer and the second welding layer belong to Figure 3 the welding layer 13, and the first welding layer and the second welding layer are only used to distinguish the welding layers 13 at different positions.

[0077] In a feasible embodiment, the method for manufacturing the infrared detector may include the following steps:

[0078] Step S11: Provide a device wafer, a window wafer, and a wafer preform; the wafer preform includes a first surface and a second surface, and both the first surface and the second surface include a bonding region and an infrared light passing region corresponding to the active region of the device wafer; the first surface is the surface of the wafer preform for bonding with the device wafer, and the second surface is the surface of the wafer preform for bonding with the window wafer.

[0079] Step S12: Prepare a first welding layer in the bonding region located on the first surface.

[0080] Step S13: Prepare a second welding layer in the bonding region located on the second surface.

[0081] Step S14: Use the first welding layer to bond the wafer preform to the device wafer.

[0082] Step S15: Use the second welding layer to bond the wafer preform to the window wafer.

[0083] Step S16: Complete the preparation of the infrared detector.

[0084] Before bonding the wafer preform to the device wafer, and / or before performing wafer-level bonding of the wafer preform to the window wafer, it further includes:

[0085] In the wafer preform, along the direction from the first surface to the second surface, a through hole is provided corresponding to the infrared light passing region.

[0086] It should be noted that in this embodiment, steps S202 to S205 are taken as an example for illustration in sequence, but the specific order of actual steps S202 to S205 is not fixed. It only needs to ensure that step S204 is executed after step S202, and step S205 is executed after step S203, that is, a welding layer needs to be correspondingly set before the bonding process. In this embodiment, the step of providing the through hole only needs to be executed before bonding the wafer preform to the device wafer, or before performing wafer-level bonding of the wafer preform to the window wafer, that is, the through hole is prepared in the wafer preform before complete bonding and encapsulation. Preferably, the above through hole can be prepared after the welding layer is completed and before the bonding process. Or specifically, the wafer preform can be first bonded to the window wafer, and then the above through hole is prepared in the wafer preform, and after preparing the above through hole, the wafer preform is bonded to the device wafer.

[0087] Furthermore, in order to avoid damaging and injuring the device wafer during subsequent dicing, before bonding the wafer preform to the device wafer, and / or before performing wafer-level bonding of the wafer preform to the window wafer, it may further include:

[0088] On the first surface of the wafer preform, a recessed structure is prepared corresponding to the active region of the device wafer.

[0089] It should be noted that in this embodiment, the step of preparing the recessed structure only needs to be executed before bonding the wafer preform to the device wafer, or before performing wafer-level bonding of the wafer preform to the window wafer.

[0090] Further, in order to ensure the successful completion of the wafer bonding process, when the wafer preform is first bonded to the device wafer and then to the window wafer, the melting point temperature of the first solder layer is higher than that of the second solder layer.

[0091] When the wafer preform is first bonded to the window wafer and then to the device wafer, the melting point temperature of the first solder layer is lower than that of the second solder layer.

[0092] It should be noted that when the steps of wafer-level bonding process are executed step by step in this embodiment, the melting point temperature of the solder layer for the wafer-level bonding process performed first can be set higher than that of the solder layer for the subsequent wafer-level bonding process, so as to avoid melting the solder layer during the previous wafer-level bonding process when performing the subsequent wafer-level bonding, thereby ensuring the successful completion of the wafer-level bonding.

[0093] Applying the infrared detector provided by the embodiment of the present invention, which includes a device wafer 2, a window wafer 3 and a wall body 1. The wall body 1 includes the wafer for heightening as described above. The device wafer 2 is bonded to the first surface of the wafer for heightening, and the window wafer 3 is bonded to the side of the wall body 1 facing away from the device wafer 2. The through holes in the wafer for heightening correspond to the active regions of the device wafer 2. The above-mentioned wafer for heightening is a monolithic wafer structure, at least including a first surface facing the device wafer 2 and a second surface facing the window wafer 3. The wafer for heightening includes an infrared light passing region, and through holes corresponding to the active regions of the device wafer 2 are arranged in the infrared light passing region along the direction from the first surface to the second surface. By using monolithic wafer preparation to prepare the wafer for heightening, the present invention can avoid the problem of limited height of the wall body 1 when using a single wafer to produce and prepare the wall body 1 and the infrared window. Moreover, when applying wafer-level packaging to prepare devices, based on ensuring the preparation efficiency, the distance between the infrared window and the focal plane is increased by the wafer for heightening prepared by monolithic forming in the present invention, thereby reducing the influence of the defects in the window light passing area on the detection imaging quality and improving the detection accuracy.

[0094] In addition, in the embodiment of the present utility model, by arranging a plurality of stacked wafers for heightening in the wall 1, the overall height of the wall 1 can be adjusted according to the number of the wafers for heightening, thereby improving the flexibility of the setting of the wall 1; by arranging getter 40 on the side wall of the through hole of the wafer for heightening, it can be ensured that the cavity is in a vacuum structure after final encapsulation, improving the detection accuracy of the infrared detector; at the same time, on the inner surface of the window wafer 3, getter 40 is arranged corresponding to the area outside the active area of the device wafer 2, further ensuring that a vacuum is maintained between the window wafer 3 and the device wafer 2 and improving the detection accuracy; the melting point temperatures of the first welding layer and the second welding layer are set to be different, so as to facilitate wafer-level bonding and avoid encapsulation failure when bonding is carried out step by step.

[0095] To make the infrared detector provided by the present utility model easier to understand, for the above method for preparing an infrared detector, reference can be made to Figure 4 , Figure 4 which is an exemplary diagram of a method for preparing an infrared detector provided by an embodiment of the present utility model. Specifically, it may include the following steps:

[0096] Step S1: Provide a device wafer, a window wafer, and a wafer preform; the wafer preform includes a first surface and a second surface, and both the first surface and the second surface include a bonding region and an infrared light passing region corresponding to the active area of the device wafer; the first surface is the surface of the wafer preform for bonding with the device wafer, and the second surface is the surface of the wafer preform for bonding with the window wafer. The thickness of the wafer preform can be set to 100 microns to 1000 microns, and the material of the wafer preform can be selected from silicon, germanium, and glass.

[0097] Step S2: By means of photolithography and dry etching, on the first surface of the wafer preform, in the scribing lane region corresponding to the active area of the device wafer, etch inward to a depth of 20 microns to 200 microns without etching through the wafer preform to form a concave structure 30. This concave structure 30 is used to expose the pads on the surface of the device wafer after the wafer dicing is finally completed.

[0098] Step S3: By means of evaporation coating, or magnetron sputtering, or electroplating, etc., deposit a second welding layer 132 on the bonding region of the second surface of the wafer preform. The second welding layer 132 is made of a high melting point material, such as AuSn (gold-tin eutectic), Au-Au (gold-gold), Si-Si (silicon-silicon), Cu-Cu (copper-copper), Au-Al (gold-aluminum), and glass paste, etc.

[0099] Step S4: By means of dry etching, or wet etching, or laser etching, in the wafer preform along the direction from the first surface to the second surface, set a through hole 10 corresponding to the active area of the device wafer in the infrared light passing region. At this time, the wafer preform is prepared to form a wafer for heightening.

[0100] Step S5: Using the second bonding layer 132, perform wafer-level bonding on the height-increasing wafer and the window wafer to form a window wafer assembly. The bonding process can be completed by eutectic bonding or diffusion bonding according to the bonding layer material used.

[0101] Step S6: By means of evaporation coating, magnetron sputtering, electroplating or the like, deposit a solder seed layer and a first bonding layer 131 on the bonding area located on the first surface. The first bonding layer 131 is made of a low-melting-point material, and the melting temperature of the first bonding layer 131 is lower than that of the second bonding layer 132. For example, SnAg (tin-silver alloy), InAg (indium-silver alloy), SnPb (tin-lead alloy), Au-Au (gold-gold), Si-Si (silicon-silicon), Cu-Cu (copper-copper), Au-Al (gold-aluminum), Cu-Sn (copper-tin), etc. can be selected.

[0102] Step S7: Deposit an getter 40 and other functional areas on the surface of the window wafer. The other functional areas include, but are not limited to, a window antireflection area. The window antireflection area can be coated with a film or provided with microstructures. In addition, the getter 40 can also be deposited on the sidewalls of the through holes 10 of the height-increasing wafer, thereby increasing the area of the getter 40.

[0103] Step S8: Using the first bonding layer 131, perform bonding treatment on the height-increasing wafer and the device wafer. Eutectic bonding or diffusion bonding can be selected according to the material of the first bonding layer 131 used.

[0104] Step S9: Perform wafer dicing treatment on the concave structure 30 in the dicing channel area of the height-increasing wafer to form individual detectors.

[0105] The present utility model provides a structural packaging solution suitable for wafer-level packaging of uncooled infrared detectors. By means of wafer-level bonding, the height-increasing wafer is matched into the detector. On the premise of ensuring the reliability of the detector vacuum packaging, the tolerance of the detector to window defects is improved, and the influence of window surface defects on the detector imaging is effectively reduced.

[0106] In the present specification, the various embodiments are described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other.

[0107] In addition, it should be noted that in this article, relationships such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant is intended to cover non-exclusive inclusion.

[0108] The above has introduced in detail a kind of wafer for heightening and an infrared detector provided by the present utility model. Specific examples are used in this article to elaborate on the principle and implementation manner of the present utility model. The description of the above embodiments is only used to help understand the structure and its core idea of the present utility model; at the same time, for those of ordinary skill in the art, according to the idea of the present utility model, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present utility model.

Claims

1. A wafer for height increase, characterized in that, The wafer for heightening is an integrally formed wafer structure; The wafer for heightening includes a first surface (11) facing the device wafer (2) and a second surface (12) facing the window wafer (3); The wafer for heightening includes an infrared light passing region, and through holes (10) corresponding to the active regions of the device wafer (2) are arranged in the infrared light passing region along the direction from the first surface (11) to the second surface (12); 2. The wafer for height increase according to claim 1, wherein Regions other than the infrared light passing region at the first surface (11) include a bonding region (20) and a scribe lane region; A concave structure (30) is formed in the scribe lane region; 3. The wafer for height increase according to claim 2, characterized in that, The depth of the concave structure (30) is one-fifth of the total thickness of the wafer for heightening; 4. The wafer for height increase according to claim 3, characterized in that, The total thickness of the wafer for heightening is 100 microns to 1000 microns; The depth of the concave structure (30) is 20 microns to 200 microns; 5. The wafer for height increase according to claim 1, wherein The wafer for heightening is a silicon wafer for heightening, or a germanium wafer for heightening, or a glass wafer for heightening; 6. An infrared detector, characterized in that, It includes a device wafer (2), a window wafer (3) and a wall body (1); The wall body (1) includes the wafer for heightening as described in any one of claims 1 to 5; The device wafer (2) is bonded to the first surface (11) of the wafer for heightening, and the window wafer (3) is bonded to one side of the wall body (1) facing away from the device wafer (2); The through holes (10) in the wafer for heightening correspond to the active regions of the device wafer (2); 7. The infrared detector according to claim 6, characterized in that, The wall body (1) includes a plurality of stacked wafers for heightening; 8. The infrared detector according to claim 6, wherein Getters are arranged on the side walls of the through holes (10) in the wafer for heightening; 9. The infrared detector according to claim 8, characterized in that Getters (40) are arranged on the inner surface of the window wafer (3) corresponding to the regions other than the active regions of the device wafer (2); 10. The infrared detector according to claim 6, characterized in that, A first welding layer (131) is arranged in the region where the device wafer (2) is bonded to the first surface (11) of the wafer for heightening; A second welding layer (132) is arranged in the region where the window wafer (3) is bonded to one side of the wall body (1) facing away from the device wafer (2); The melting point temperature of the first welding layer (131) is different from the melting point temperature of the second welding layer (132).

Images