WO2024027151A1

WO2024027151A1 - Detection module, detector and laser radar

Info

Publication number: WO2024027151A1
Application number: PCT/CN2023/079995
Authority: WO
Inventors: 陈垚江; 陈杰; 刘颖彪; 吴攸; 向少卿
Original assignee: 上海禾赛科技有限公司
Priority date: 2022-08-05
Filing date: 2023-03-07
Publication date: 2024-02-08
Also published as: CN117553910A

Abstract

A detection module, a detector and a laser radar. The detection module comprises: a photosensitive array (110), which comprises multiple photosensitive devices (111); and a micro-lens array (120), which is suitable for converging light to the photosensitive array (110) and comprises multiple micro-lens units (121) in one-to-one correspondence with the multiple photosensitive devices (111). In a plane of the surface of parallel photosensitive arrays (110), the projections of two adjacent micro-lens units (121) share one boundary. Every three boundaries share one intersection point such that the fill factor can be effectively improved, the light convergence capability of the micro-lens array (120) is improved, and the detection capability is improved. Moreover, the arrangement can reduce the manufacturing difficulty of the micro-lens array (120), effectively improve the yield and reduce the process cost.

Description

Detection modules, detectors and lidar

This application claims priority to the Chinese patent application filed with the China Patent Office on August 5, 2022, with the application number 202210940183X and the invention name "Detection Module, Detector and Lidar", the entire content of which is incorporated into this application by reference. .

Technical field

The invention relates to the field of laser detection, and in particular to a detection module, a detector and a laser radar.

Background technique

In applications such as remote sensing, gas detection, and lidar, the detection efficiency of the detector is directly related to the system performance. The single photon avalanche diode (SPAD) device is a highly sensitive detection device that can detect extremely weak light signals and is more suitable for the above applications. The detection efficiency of the SPAD device is positively related to the area ratio of the photosensitive area, that is, the higher the area utilization rate of the SPAD, the higher the detection efficiency.

However, in practical applications, due to the existence of electrodes, protective rings and other structures, the non-photosensitive area in the SPAD device always occupies a certain area, resulting in the area utilization rate of the photosensitive area of the SPAD device not reaching 100%. On the other hand, in order to obtain higher array resolution and dynamic range, the smaller the size of the individual SPAD devices in the SPAD array, the better. The reduction in the size of a single SPAD device will reduce the area of the photosensitive area and the non-photosensitive area together. If the area of the non-photosensitive area cannot be further reduced, the area utilization rate of the SPAD will decrease as the size of the SPAD unit decreases, affecting the detection efficiency. .

In order to improve the detection efficiency of the SPAD array with smaller unit size, a microlens array is set up in the optical path of the SPAD array. Each microlens unit converges light to the SPAD device, increasing the intensity of light received by the photosensitive area of the SPAD device, thus effectively improving detection efficiency while the size of the photosensitive area remains unchanged.

However, even if a microlens array is provided, the improvement in detection efficiency of the SPAD array is still not ideal.

Contents of the invention

The problem solved by the present invention is to provide a detection module, detector and laser radar to further improve detection efficiency.

In order to solve the above problems, the present invention provides a detection module, including:

Photosensitive array, the photosensitive array includes a plurality of photosensitive devices; a microlens array, the microlens array is suitable for converging light to the photosensitive array, the microlens array includes: a plurality of microlens units, the plurality of microlens units The lens units correspond to the plurality of photosensitive devices one-to-one; in a plane parallel to the surface of the photosensitive array, the projections of two adjacent micro-lens units share a boundary, and every three of the boundaries share an intersection point.

Optionally, in a plane parallel to the surface of the photosensitive array, the projection of the microlens unit is a hexagon.

Optionally, in a plane parallel to the surface of the photosensitive array, in the projection of any microlens unit, the difference between any side length and the average value of the side lengths is less than 10% of the average value.

Optionally, the projection of the microlens unit is a regular hexagon.

Optionally, the geometric center of the projection of the microlens unit is aligned with the photosensitive area of the corresponding photosensitive device.

Optionally, in a plane parallel to the surface of the photosensitive array, the distance between the geometric center of the projection of the microlens unit and the geometric center of the projection of the photosensitive area of the corresponding photosensitive device is smaller than the projection of the microlens unit. 20% of the length of either side.

Optionally, the microlens unit includes: a lens portion; in the microlens array, the lens portions of multiple microlens units are closely arranged so that the fill factor of the microlens array is greater than 60%.

Optionally, the difference in size of different microlens units in a direction perpendicular to the surface of the photosensitive array is less than 5 microns.

Optionally, the sizes of different microlens units are the same in the direction perpendicular to the surface of the photosensitive array.

Optionally, the center spacing of adjacent microlens units is in the range of 5 microns to 25 microns, wherein the center spacing of adjacent microlens units is in a plane parallel to the surface of the photosensitive array, and the projection of the adjacent microlens units is The distance between geometric centers.

Optionally, the maximum curvature radius of the continuous curved surface of the microlens unit is 0.5 to 1.5 times the center distance of adjacent microlens units.

Optionally, in a plane parallel to the surface of the photosensitive array, the projected shape of the photosensitive area of the photosensitive device is a rectangle, a hexagon or a circle.

Optionally, the plurality of microlens units are arranged in an array along the intersecting first direction and the second direction; the angle between the first direction and the second direction is not equal to 90 degrees.

Optionally, in a plane parallel to the surface of the photosensitive array, the distance between the boundary of the photosensitive area of the photosensitive device and the boundary of the photosensitive device is in the range of 0 microns to 5 microns.

Optionally, the photosensitive device is a SPAD device.

Optionally, the microlens unit includes: a lens part, and the thickness of the lens part at the edge position is smaller than the thickness of the lens part at the center position.

Optionally, each microlens unit further includes: a connecting portion filled between the lens portions of adjacent microlens units.

Optionally, the surface of the lens part is a continuously curved surface.

Optionally, the surface of the lens part includes: a top area, the top area is located at a position where the thickness of the lens part is maximum, and the surface of the lens part in the top area is a plane parallel to the surface of the photosensitive array.

Optionally, the surface of the lens part further includes: a connecting area surrounding the top area; the connecting area is a continuous curved surface, or the connecting area is a folded surface connected by multiple planes.

Correspondingly, the present invention also provides a detector, which includes: a detection module, and the detection module is the detection module of the present invention.

In addition, the present invention also provides a laser radar, including: a detector, and the detector is the detector of the present invention.

Compared with the existing technology, the technical solution of the present invention has the following advantages:

In the technical solution of the present invention, in a plane parallel to the surface of the photosensitive array, the projections of two adjacent microlens units share a boundary, and every three of the boundaries share an intersection point. Through the above arrangement, the filling factor can be effectively increased, and the light gathering ability of the microlens array can be improved, which is conducive to the improvement of detection capabilities; and this arrangement can also reduce the difficulty of preparing the microlens array and effectively improve the yield. Reduce process costs.

Description of the drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting creative efforts.

Figure 1 is a schematic diagram of the three-dimensional structure of a discrete microlens array;

Figure 2 is a schematic diagram of the three-dimensional structure of a continuous microlens array;

Figure 3 is a schematic diagram of the three-dimensional structure of another microlens array;

Figure 4 is a schematic top structural view of an embodiment of the detection module of the present invention;

Figure 5 is a schematic top structural view of the photosensitive array in the embodiment of the detection module shown in Figure 4;

Figure 6 is a schematic three-dimensional structural diagram of the microlens array in the embodiment of the detection module shown in Figure 4;

Figure 7 is a schematic top structural view of the microlens array in the embodiment of the detection module shown in Figure 4;

Figure 8 is a schematic cross-sectional structural diagram of the microlens array along line A1A2 in the embodiment of the detection module shown in Figure 7;

Figure 9 is a schematic top structural view of the microlens array in another embodiment of the detection module of the present invention;

Figure 10 is a schematic cross-sectional structural diagram of the microlens array along the dotted line B1B2 in the embodiment of the detection module shown in Figure 9;

Figure 11 is a schematic cross-sectional structural diagram of a microlens unit in the microlens array in another embodiment of the detection module of the present invention;

Figure 12 is a schematic diagram of the process of forming the microlens array in one embodiment of the detection module of the present invention;

Figure 13 is a schematic side structural view of a microlens unit in the microlens array in an embodiment of the detection module of the present invention;

Figure 14 is a schematic three-dimensional structural diagram of the microlens array in another embodiment of the detection module of the present invention;

Figure 15 is a schematic top structural view of the microlens array in the embodiment of the detection module shown in Figure 14;

Figure 16 shows the filling coefficients of the honeycomb microlens array and the square microlens array when the distance between adjacent lens parts of the detection module of the present invention is 1 μm.

Detailed ways

It can be known from the background art that even if a microlens array is provided in the prior art, the improvement of the detection efficiency of the SPAD array is still not ideal. The reason for the poor detection efficiency improvement is now analyzed based on the structure of the existing microlens array.

There are two main factors that affect the improvement of the detection efficiency of SPAD devices by microlenses: one is the filling factor of the microlenses, and the other is the convergence ability of the microlenses. Among them, the filling factor of the microlens is defined as the proportion of the curved surface part of the microlens in the total area of the microlens array, because only the entrance The light hitting the curved surface part of the microlens will be condensed, and it is possible to enter the photosensitive area of the SPAD device; secondly, the condensing ability of the microlens is related to the radius of curvature of the curved surface part of the microlens. The smaller the curvature radius, the smaller the convergence of the microlens. The stronger the ability, that is, the smaller the radius of curvature of the microlens, the more light can be gathered into the photosensitive area of the SPAD device, thereby effectively improving the detection efficiency.

Based on the curved shape of the microlens, microlens arrays can be divided into discrete microlens arrays (as shown in Figure 1) and continuous microlens arrays (as shown in Figure 2).

Among them, the discrete microlens is shown in Figure 1. The row and column directions of the microlens array are orthogonal. Therefore, in the top view, every two microlenses share a boundary, and every four boundaries share an intersection point. Each microlens occupies The area is a square; therefore, in a hemispherical microlens, the curved surface part cannot completely occupy the corner positions of the square, that is to say, this kind of microlens cannot converge the incident light at the four corners of the square area, that is, the filling of the microlens The coefficient is less than 100%, so the effect on improving detection efficiency is limited.

In order to solve the problem of low microlens filling factor, one solution is to prepare a continuous microlens array, as shown in Figure 2. The continuous microlens array is based on the above discrete microlens array, and further improves the microlens array. Achieved by performing one or more etchings. Since the corner positions are relatively flat, the etching depth at the corner positions of the square area is greater compared to the curved surface part of the central part to make the curved surface part of the microlens closer to a hemispherical shape, thereby making the fill factor reach 100%.

However, in this method, the etching process is more difficult, especially when the curvature radius of the curved surface part of the microlens is large, and the height difference between the center position and the corner position of the square area is large, the etching process is more difficult, that is, The larger the curvature radius of the curved surface part of the microlens, the greater the process difficulty of the continuous microlens array. Therefore, in order to ensure the performance and yield of the formed microlens array, in the continuous microlens array, the curvature radius of the curved surface part of the microlens is relatively small, so the effect on improving detection efficiency is also limited.

In addition, in another solution, during the preparation process of discrete microlenses, the microlens cross-section is prepared into a square shape, but the curved surface of the microlens is usually formed through a thermal reflow process, so the curved surface formed after thermal reflow is only The middle part is close to hemispherical, and the edge part is particularly In particular, the radius of curvature of the edge along the diagonal direction will be too large (as shown in Figure 3); an excessively large radius of curvature cannot guarantee the convergence ability of the microlens. Therefore, although the method of forming square cross-section microlenses can improve the filling factor, it will affect the focusing ability of the microlenses and still cannot further improve the detection efficiency.

In summary, the light-gathering ability of existing microlens arrays is limited by the structure and preparation process, thus affecting the improvement of detection efficiency.

In order to solve the above technical problems, the present invention provides a detection module, including:

The technical solution of the present invention is that in a plane parallel to the surface of the photosensitive array, the projections of two adjacent microlens units share a boundary, and every three of the boundaries share an intersection point. Through the above arrangement, the filling factor can be effectively increased, and the light gathering ability of the microlens array can be improved, which is conducive to improving the detection capability of the photosensitive device; and this arrangement can also reduce the difficulty of preparing the microlens array, and can effectively improve the quality of the microlens array. efficiency and reduce process costs.

In order to make the above objects, features and advantages of the present invention more obvious and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Referring to Figure 4, a schematic top structural view of an embodiment of the detection module of the present invention is shown.

It should be noted that, for clarity of display, FIG. 4 only shows a schematic top view of a partial area of the detection module.

The detection module includes: a photosensitive array 110, the photosensitive array 110 includes a plurality of photosensitive devices 111; a microlens array 120, the microlens array 120 is suitable for converging light to the photosensitive array 110, the microlens array 120 It includes: a plurality of microlens units 121, which correspond to the plurality of photosensitive devices 111 one by one; in the plane XOY parallel to the surface of the photosensitive array 110, two adjacent microlens units The projections of element 121 share a boundary, and every three said boundaries share an intersection point.

The projections of two adjacent microlens units 121 share a boundary, and every three boundaries share an intersection point. Compared with the prior art microlens array in which rows and columns are orthogonal and every four boundaries share an intersection point, the technology of the present invention The solution can effectively increase the filling factor and improve the light gathering ability of the microlens array 120, which is conducive to improving the detection capability of the photosensitive device; and this arrangement can also reduce the difficulty of preparing the microlens array 120 and effectively reduce the process difficulty. .

The photosensitive array 110 is used to receive light and perform photoelectric conversion.

In some embodiments of the present invention, in the plane XOY parallel to the surface of the photosensitive array 110, the projection of the microlens unit 121 is a hexagon.

By arranging the microlens unit in a hexagonal shape, the microlens array can be arranged in a honeycomb-like dense arrangement, which can further increase the filling factor and improve the light gathering ability of the microlens array 120, thereby further improving the detection capability of the photosensitive device.

With reference to FIG. 5 , a schematic top structural view of the photosensitive array in the embodiment of the detection module shown in FIG. 4 is shown.

As shown in Figure 5, in some embodiments of the present invention, within the plane XOY parallel to the surface of the photosensitive array 110, the shape of the projection of the photosensitive area of the photosensitive device 111 (the area filled with dotted texture in Figure 5) is a rectangle. , to simplify the preparation process of the photosensitive device 111.

In other embodiments of the present invention, in a plane parallel to the surface of the photosensitive array, the projected shape of the photosensitive area of the photosensitive device may also be a circle, a hexagon, or other polygonal shapes.

In some embodiments of the present invention, the photosensitive device 111 is a SPAD device.

In some embodiments of the present invention, in the plane XOY parallel to the surface of the photosensitive array 110, the distance d between the boundary of the photosensitive area of the photosensitive device 111 and the boundary of the photosensitive device 111 is in the range of 0 microns to 5 microns. . Preferably, the distance d between the boundary of the photosensitive area of the photosensitive device 111 and the boundary of the photosensitive device 111 is in the range of 1 micron to 4 microns.

On the one hand, the photosensitive area of the photosensitive device 111 is smaller than the entire photosensitive device 111, so that the photosensitive area of the photosensitive device 111 is located within the range of the microlens unit 121, and the microlens unit 121 can focus the incident light on The photosensitive area of the photosensitive device 111; on the other hand, the photosensitive area of the photosensitive device 111 cannot be too small, otherwise the requirements for the focusing ability of the microlens will be too high. At the same time, it is ensured that the photosensitive area of the photosensitive device 111 is within the photosensitive area. The area ratio of device 111 can improve detection efficiency.

Continuing to refer to FIG. 4 , the detection module further includes: a microlens array 120 having a plurality of microlens units 121 .

Referring to Figures 6 and 7 in conjunction, Figure 6 shows a schematic three-dimensional structural diagram of the microlens array in the embodiment of the detection module shown in Figure 4, and Figure 7 shows a schematic diagram of the microlens array in the embodiment of the detection module shown in Figure 4. Schematic diagram of the top view structure of the lens array.

The microlens array 120 is used to converge light to the photosensitive area of the photosensitive device 111 in the photosensitive array 110 to improve detection efficiency.

The multiple microlens units 121 of the microlens array 120 correspond to the multiple photosensitive devices 111 of the photosensitive array 110 one-to-one, that is, one microlens unit 121 corresponds to one photosensitive device 111, and each microlens unit 121 corresponds to one photosensitive device 111. The microlens unit 121 converges the transmitted light to the corresponding photosensitive area of the photosensitive device 111 .

In order to ensure that the microlens unit 121 can converge light into the corresponding photosensitive device 111, in some embodiments of the present invention, the geometric center of the projection of the microlens unit 121 is opposite to the photosensitive area of the corresponding photosensitive device 111. allow.

Specifically, in some embodiments, in the plane XOY parallel to the surface of the photosensitive array 110, the distance between the geometric center of the projection of the microlens unit 121 and the geometric center of the projection of the photosensitive area of the corresponding photosensitive device 111 is less than 20% of the length a of any side of the projection of the microlens unit 121, thereby ensuring that the photosensitive area of the photosensitive device 111 is aligned with the center of the microlens unit 121 as much as possible, and receiving as much light as possible from the microlens Units gather light.

The microlens unit 121 has a hexagonal cross-section; that is, it is parallel to the photosensitive array 110 In the plane XOY of the surface, the projection of the microlens unit 121 is a hexagon. Therefore, in some embodiments of the present invention, the plurality of microlens units 121 are arranged in an array along the intersecting first direction OX and the second direction OY; the angle between the first direction and the second direction Not equal to 90 degrees.

As shown in Figures 6 and 7, in some embodiments, the projection of the microlens unit 121 is a regular hexagon, and the angle between the first direction OX and the second direction OY is 60°, so that Achieve honeycomb close arrangement.

It should be noted that the plurality of microlens units 121 of the microlens array 120 correspond to the plurality of photosensitive devices 111 of the photosensitive array 110; the plurality of microlens units 121 are aligned along the intersecting first direction OX and The second direction OY is arranged in an array; the angle between the first direction and the second direction is not equal to 90 degrees, so the plurality of photosensitive devices 111 of the photosensitive array 110 are also arranged along the intersecting first direction OX and the second direction OY are arranged in an array, and the angle between the first direction and the second direction is not equal to 90 degrees.

Specifically, in the embodiment shown in FIG. 5 , the plurality of photosensitive devices 111 of the photosensitive array 110 are also arranged in an array along the intersecting first direction OX and the second direction OY. The first direction and the second direction OY are arranged in an array. The angle between the two directions is equal to 60 degrees, that is, the plurality of photosensitive devices 111 are also densely packed in a honeycomb shape.

The microlens unit 121 has a hexagonal cross-section, so the microlens array 120 is densely packed in a honeycomb shape; therefore, the microlens array 120 has a higher filling factor and can better gather light, which is beneficial to detection. Improvement of abilities.

In some embodiments of the present invention, in the plane XOY parallel to the surface of the photosensitive array 110, in the projection of any microlens unit 121, the difference between any side length a and the average value of the side lengths is less than 10% of the average value. Specifically, in some embodiments, the projection of the microlens unit is a regular hexagon. The arrangement of the microlens array 120 is made as close to a honeycomb shape as possible, that is, each microlens unit 121 occupies a regular hexagonal area, so as to obtain a filling factor as high as possible.

In some embodiments of the present invention, the center distance w of adjacent microlens units 121 is 5 In the range of micrometers to 25 micrometers, the center distance w of adjacent microlens units 121 is the distance between the geometric centers of projections of adjacent microlens units 121 in the plane XOY parallel to the surface of the photosensitive array 110 . If the center distance w of the microlens unit 121 is too small, the requirements for the formation process of the photosensitive device 111 and the microlens unit 121 are too high, and the process quality is difficult to guarantee; if the center distance w of the microlens unit 121 is too large, the corresponding photosensitive device 121 The size is also relatively large, which may slow down the response speed of SPAD.

With reference to FIG. 8 , a schematic cross-sectional structural diagram of the microlens array along line A1A2 in the embodiment of the detection module shown in FIG. 7 is shown.

In some embodiments of the present invention, in the direction Z perpendicular to the surface of the photosensitive array 110, the difference in the size H of different microlens units 121 is less than 5 microns. That is to say, the difference in the thickness of different microlens units 121 is less than 5 microns. Micron. Controlling the difference in thickness of different microlens units 121 ensures the uniformity of the overall thickness of the microlens array 120 and improves the surface flatness of the microlens array 120, which can effectively reduce the difficulty of assembly, packaging and other processes.

In some embodiments of the present invention, in the direction z perpendicular to the surface of the photosensitive array 120, the sizes H of different microlens units 121 are the same, that is, the thicknesses of different microlens units 120 in the microlens array 120 are all equal.

In addition, as shown in FIG. 8 , in some embodiments of the invention, the microlens unit 120 includes a lens portion 122 , and the thickness h2 of the lens portion 122 at the edge is smaller than the thickness h1 of the lens portion 122 at the center. Specifically, the difference between the thicknesses h2 and h1 is determined by the cross-sectional size and the radius of curvature of the lens portion.

The lens portion 122 is used to collect light to achieve the optical function of the microlens unit 120 .

In some embodiments of the present invention, in the microlens array 120, the lens portions 122 of multiple microlens units 121 are closely arranged so that the fill factor of the microlens array 120 is greater than 60%. Specifically, in the embodiment shown in FIGS. 6 to 8 , the microlens array 120 is a continuous microlens array, that is, in the microlens array 120 , the lens portion 122 is filled with In the micro lens unit 121, the lens portions 122 of adjacent micro lens units 122 are in surface contact. Therefore, in the embodiment shown in FIGS. 6 to 8 , the fill factor of the microlens array 120 is close to 100%.

As shown in FIG. 8 , in some embodiments of the present invention, the surface of the lens portion 122 is a continuously curved surface. That is to say, the surface of the lens portion 122 facing away from the photosensitive device 111 is a curved surface that can be guided everywhere. Therefore, the surface of the lens portion 122 forms a convex lens to achieve light convergence.

The radius of curvature of the continuous curved surface is related to the ability of the lens portion 122 to condense light. In some embodiments of the present invention, the center distance w of adjacent micro lens units 121 is in the range of 5 microns to 25 microns. Therefore, the maximum curvature radius R of the continuous curved surface of the micro lens unit 121 is the center distance of adjacent micro lens units. 0.5 to 1.5 times, that is, the maximum curvature radius R of the continuous curved surface of the lens portion 122 is 0.5 to 1.5 times the center distance of adjacent micro lens units to obtain good convergence ability.

It should be noted that the surface of the lens part 122 being a continuous curved surface is just an example. In other embodiments of the present invention, the surface of the lens part 122 may also include at least a partial plane.

Specifically, in the embodiment shown in FIGS. 9 and 10 , the surface of the lens part 222 includes: a top area 223 , the top area 223 is located at the position where the thickness of the lens part 222 is the largest, and the lens part of the top area 223 The surface of 222 is a plane parallel to the surface of the photosensitive array (not shown in the figure). Making the top area of the lens portion 222 flat can effectively improve the consistency of the thickness of different microlens units in the microlens array, thereby improving the flatness of the surface of the microlens array and reducing the difficulty of subsequent processes. .

As shown in FIGS. 9 and 10 , the surface of the lens part 222 also includes: a connection area 224 surrounding the top area 223 ; the connection area 224 is a continuous curved surface. In other embodiments of the present invention, as shown in FIG. 11 , the connection area 324 may also be a folded surface connected by multiple planes. That is to say, the connection area surrounding the top area 323 on the surface of the lens part 322 Area 324 is composed of a plurality of interconnected planes, and the deflection direction of each plane relative to a plane parallel to the surface of the photosensitive array (not shown in the figure) is beneficial to Deflect light toward the photosensitive area of the photosensitive device.

It should be noted that, as shown in Figure 12, the process of forming the microlens array includes:

S1. As shown in Figure 12(a) and (b), after obtaining the photosensitive array 121, form a flat layer 122 on the photosensitive array 121;

S2. As shown in Figure 12(c), form a lens material layer 123 on the flat layer 122;

S3. As shown in Figure 12(d), the lens layer is patterned to form a plurality of discrete prefabricated columns 124. The plurality of prefabricated columns 124 are connected to the plurality of photosensitive devices in the photosensitive array 121 one by one. correspond;

S4. As shown in Figure 12(e), perform heat reflow on a plurality of the prefabricated columns 124 to form a curved surface.

Wherein, the flat layer 122 and the lens material layer 123 are usually made of materials with the same refractive index. Specifically, the flat layer 122 and the lens material layer 123 are usually made of materials with a refractive index between 2 and 2.5 to better realize the light converging effect of the microlens array.

In addition, the microlens array is a continuous microlens array, that is, the filling factor of the microlens array 120 is close to 100%, and the surfaces of adjacent microlens units are connected to each other. Therefore, the process of forming the microlens array also includes:

S5. As shown in FIG. 12(f), after thermal reflow, the lens part and the flat layer 122 are etched, and finally a continuous microlens array with connected curved surfaces is formed on the flat layer 122.

As shown in Figure 13, when the microlens unit is set to a hexagonal shape and the microlens array is set to a honeycomb dense arrangement, the height difference d between the edge and the corner of the microlens unit is smaller. That is to say, after thermal reflow, the flat The required etching depth of the layer is smaller and the process difficulty is lower, which can improve the yield and reduce the process cost. Specifically, compared with the existing rectangular and square arrays, in the honeycomb-shaped densely packed microlens array, the height difference d between the edges and corners of the microlens units can be reduced by 2/3.

It should be noted that in the embodiments shown in Figures 4 to 13, in the hexagonal area occupied by each microlens unit, the microlens arrays are continuous microlens arrays; in other embodiments of the present invention, in each microlens unit Within each microlens unit, the microlens array may also be a discrete microlens array.

Referring to Figures 14 to 15, Figure 14 is a schematic three-dimensional structural diagram of the microlens array in another embodiment of the detection module of the present invention; Figure 15 is a top view structure of the microlens array in the embodiment of the detection module shown in Figure 14 Schematic diagram.

The same points as the previous embodiments will not be described again here. The difference from the previous embodiments is that in some embodiments of the present invention, the microlens array 220 is a discrete microlens array.

Therefore, as shown in FIGS. 14 and 15 , in some embodiments of the present invention, each microlens unit 421 further includes: a connecting portion 425 filled between the lens portions 422 of adjacent microlens units 421 .

The connecting portion 425 serves as a spacer band surrounding the lens portion 422 and filling between the lens portions 422 of adjacent micro lens units 421 .

In some embodiments of the present invention, the filling factor of the microlens array 120 is greater than 60%. That is to say, in the embodiments shown in Figures 14 and 15, in the plane XOY parallel to the surface of the photosensitive array, the lens The total projected area of the portions 422 accounts for more than 60% of the total area of the microlens array.

As shown in FIG. 15 , in the discrete microlens array, there is a gap g between adjacent lens portions 422 . When the distance g between adjacent lens parts is equal, the microlens unit 421 is arranged in a hexagonal shape and the microlens array 420 is arranged in a honeycomb-like close-packed shape, which can effectively improve the filling factor.

Referring to FIG. 16 , the filling factors of the honeycomb microlens array and the square microlens array when the distance between adjacent lens portions is 1 μm are shown.

Among them, the horizontal axis represents the area occupied by the microlens unit; the vertical axis represents the filling factor of the microlens; the solid line 151 represents the change of the filling factor of the honeycomb microlens array; the dotted line represents Fill factor variation of square microlens array.

As shown in Figure 16, compared with the square microlens array, the filling factor of the honeycomb microlens array is significantly improved, and the detection efficiency will be correspondingly improved.

The detection module is the detection module of the present invention. Therefore, for the specific technical solution of the detection module, reference is made to the foregoing embodiment of the detection module, and the present invention will not be repeated here.

In the detection module, the cross-sectional shape of the microlens unit is hexagonal, the microlens array is arranged in a honeycomb shape, the microlens array has a higher filling factor and lower preparation difficulty, so the The microlens array has better light convergence ability; the better light convergence ability of the microlens array can effectively improve the detection efficiency of the detector.

Correspondingly, the present invention also provides a laser radar, including: a detector, and the detector is the detector of the present invention.

The detector is the detector of the present invention. Therefore, for the specific technical solution of the detector, reference is made to the foregoing embodiment of the detector, and the present invention will not be repeated here.

The detector has better detection efficiency, so the lidar has better ranging capabilities and better performance.

In summary, in a plane parallel to the surface of the photosensitive array, the projection of the microlens unit is a hexagon, and the microlens array is densely packed in a honeycomb shape. By configuring the microlens unit to be hexagonal and the microlens array to be closely packed in a honeycomb shape, the filling factor can be effectively increased, and the light gathering ability of the microlens array can be improved, which is conducive to the improvement of detection capabilities; and this The setting method can also reduce the difficulty of preparing the microlens array and can effectively reduce the process difficulty.

Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

A detection module, characterized by including:

A photosensitive array, the photosensitive array includes a plurality of photosensitive devices;

A microlens array, the microlens array is suitable for converging light to the photosensitive array, the microlens array includes: a plurality of microlens units, the plurality of microlens units correspond to the plurality of photosensitive devices in one-to-one correspondence;

In a plane parallel to the surface of the photosensitive array, the projections of two adjacent microlens units share a boundary, and every three boundaries share an intersection point.
The detection module according to claim 1, wherein in a plane parallel to the photosensitive array, the projection of the microlens unit is a hexagon.
The detection module according to claim 2, wherein in a plane parallel to the surface of the photosensitive array, in the projection of any microlens unit, the difference between any side length and the average value of the side length is less than the average value. 10%.
The detection module according to claim 2 or 3, characterized in that the projection of the microlens unit is a regular hexagon.
The detection module of claim 1, wherein the geometric center of the projection of the microlens unit is aligned with the photosensitive area of the corresponding photosensitive device.
The detection module of claim 5, wherein in a plane parallel to the surface of the photosensitive array, the distance between the geometric center of the projection of the microlens unit and the geometric center of the projection of the photosensitive area of the corresponding photosensitive device is The distance is less than 20% of the length of either side of the projection of the microlens unit.
The detection module of claim 1, wherein the microlens unit includes: a lens part, and in the microlens array, the lens parts of a plurality of microlens units are closely arranged to ensure that the microlens array is filled with The coefficient is greater than 60%.
The detection module of claim 1, wherein the difference in size of different microlens units in a direction perpendicular to the surface of the photosensitive array is less than 5 microns.
The detection module according to claim 8, wherein the sizes of different microlens units are the same in the direction perpendicular to the surface of the photosensitive array.
The detection module of claim 1, wherein the center distance between adjacent microlens units is in the range of 5 microns to 25 microns, wherein the center distance between adjacent microlens units is a plane parallel to the surface of the photosensitive array Within, the distance between the geometric centers of projections of adjacent microlens units.
The detection module of claim 10, wherein the maximum curvature radius of the continuous curved surface of the microlens unit is 0.5 to 1.5 times the center distance of adjacent microlens units.
The detection module according to claim 1, wherein in a plane parallel to the surface of the photosensitive array, the projected shape of the photosensitive area of the photosensitive device is a rectangle, a hexagon or a circle.
The detection module according to claim 1 or 12, wherein the plurality of microlens units are arranged in an array along the intersecting first direction and the second direction; The angle between them is not equal to 90 degrees.
The detection module according to claim 1, wherein in a plane parallel to the surface of the photosensitive array, the distance between the boundary of the photosensitive area of the photosensitive device and the boundary of the photosensitive device is between 0 microns and 5 microns. within the range.
The detection module of claim 1, wherein the photosensitive device is a SPAD device.
The detection module of claim 1, wherein the microlens unit includes a lens portion, and the thickness of the lens portion at the edge is smaller than the thickness of the lens portion at the center.
The detection module of claim 16, wherein each microlens unit further includes: a connecting portion filled between lens portions of adjacent microlens units.
The detection module according to claim 16, wherein the surface of the lens part is a continuous surface.
The detection module according to claim 16, wherein the surface of the lens part includes: a top area, the top area is located at the position where the thickness of the lens part is maximum, and the surface of the lens part in the top area is parallel on the plane of the surface of the photosensitive array.
The detection module of claim 19, wherein the surface of the lens part further includes: a connection area surrounding the top area; the connection area is a continuous curved surface, or the connection area is Folded surfaces with multiple connected planes.
A detector, characterized in that it includes: a detection module, the detection module is as described in any one of claims 1 to 20.
A lidar, characterized in that it includes: a detector, and the detector is as claimed in claim 21.