Double-sided heterogeneous structure micro-lens chip for rapid positioning, and manufacturing method and application of double-sided heterogeneous structure micro-lens chip

Abstract

The invention discloses a double-sided heterogeneous structure microlens chip for rapid positioning, and a manufacturing method and application thereof. The micro lens chip comprises a chip substrate, a micro lens and a positioning structure. The chip substrate is provided with a first surface and a second surface which are back to back, the micro lens is formed on the first surface, and the positioning structure is formed on the second surface; the positioning structure is provided with a convex part and a groove part, and the end part of the convex part is positioned on a positioning plane; the focused light penetrates through the groove part, and the focus falls on the positioning plane or has a fixed distance relation with the positioning plane. According to the invention, the positioning structure for accurate alignment is formed on the other surface of the micro lens, and the depth of the groove of the positioning structure is fixed, so that a fixed relation is formed between the focal position of the lens chip and the positioning plane, and after the positioning plane is directly or indirectly attached to the photoelectric detector to form the fixed relation, the lens chip can be fixed. And the focus can directly fall on the sensing surface of the photoelectric detector, so that the lens positioning efficiency and accuracy are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor micro-nano processing and optical communication technology, and in particular to a double-sided heterogeneous structure microlens chip for rapid positioning, a manufacturing method and application thereof. Background Art

[0002] With the development of science and technology, the traditional contact temperature measurement method can no longer meet the temperature measurement needs in some modern fields, and the demand for non-contact and long-distance temperature measurement technology is increasing. Non-contact infrared temperature measurement is also called radiation temperature measurement, which generally uses thermoelectric or photoelectric detectors as detection elements. The infrared radiation generated by the thermal effect uses microlenses to converge the infrared light, and uses photoelectric detectors to measure the absorbed infrared radiation, indirectly measuring the temperature of the object radiating infrared light. However, Figure 1 As shown, in the traditional installation method, there is a certain distance between the microlens and the photodetector, which is not convenient for quickly and accurately locating the chip position. Summary of the invention

[0003] In view of the deficiencies of the prior art, the object of the present invention is to provide a double-sided heterogeneous structure microlens chip for rapid positioning, and a manufacturing method and application thereof.

[0004] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes:

[0005] In a first aspect, the present invention provides a double-sided heterogeneous structure microlens chip for rapid positioning, which includes a chip substrate, a microlens and a positioning structure;

[0006] The chip substrate has a first surface and a second surface facing each other, the microlens is formed on the first surface, and the positioning structure is formed on the second surface; the positioning structure has a protrusion arranged along the periphery of the second surface and a groove arranged in the middle of the second surface and surrounded by the protrusion, and the end of the protrusion is located on a positioning plane;

[0007] The light refracted by the microlens can pass through the chip substrate and through the groove portion, and the focus falls on the positioning plane or has a fixed first distance relationship with the positioning plane.

[0008] In a second aspect, the present invention further provides a method for preparing the above-mentioned double-sided heterogeneous structure microlens chip, which comprises:

[0009] Microlenses and alignment marks are constructed on one side of the substrate by patterned etching;

[0010] The positioning structure is formed on the other side of the substrate by patterned etching using the alignment mark, and the positioning structure is made to correspond to the position of the microlens.

[0011] In a third aspect, the present invention also provides application of the above-mentioned double-sided heterogeneous structure microlens chip in the rapid installation and positioning of microlenses.

[0012] In a fourth aspect, the present invention further provides a photoelectric detection combination structure, which includes the above-mentioned double-sided heterogeneous structure microlens chip and a photoelectric detector;

[0013] The photodetector has a mounting plane and a photosensitive surface. The mounting plane is bonded and fixed to the positioning plane of the double-sided heterogeneous structure microlens chip. The photosensitive surface and the mounting plane are in the same plane, or have a known and fixed second distance relationship and the second distance relationship matches the first distance relationship, so that the focus of the light falls on the photosensitive surface.

[0014] Based on the above technical solution, compared with the prior art, the beneficial effects of the present invention at least include:

[0015] The double-sided heterogeneous structure microlens chip provided by the present invention forms a precisely aligned positioning structure on the other side of the microlens, and the groove depth of the positioning structure is fixed, so that a fixed relationship is formed between the focal position of the lens chip and the positioning plane. When the positioning plane is directly or indirectly bonded to the photodetector to form a fixed relationship during installation, the focus can be directly placed on the sensing surface of the photodetector, which significantly improves the efficiency and accuracy of lens positioning.

[0016] The above description is only an overview of the technical solution of the present invention. In order to enable those skilled in the art to more clearly understand the technical means of the present application and implement them according to the contents of the specification, the following is a description of the preferred embodiments of the present invention in conjunction with detailed drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the positional relationship between a traditional lens and a photoelectric detector provided by the background technology of the present invention;

[0018] Figure 2 It is a schematic diagram of the positional relationship between a microlens chip and a photodetector provided in a typical implementation case of the present invention;

[0019] Figure 3 It is a schematic diagram of the structure of a microlens chip provided by a typical implementation case of the present invention.

[0020] Description of reference numerals:

[0021] 1. Light; 2. Microlens chip; 3. Photodetector. DETAILED DESCRIPTION

[0022] In view of the deficiencies in the prior art, the inventor of this case has proposed the technical solution of the present invention after long-term research and extensive practice. The technical solution, its implementation process and principle will be further explained as follows.

[0023] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0024] Moreover, relational terms such as “first” and “second” are merely used to distinguish one component or method step from another with the same name, but do not necessarily require or imply any such actual relationship or order between these components or method steps.

[0025] An embodiment of the present invention provides a double-sided heterogeneous structure microlens chip for rapid positioning, comprising a chip substrate, a microlens and a positioning structure; the chip substrate has a first surface and a second surface facing each other, the microlens is formed on the first surface, and the positioning structure is formed on the second surface; the positioning structure has a protrusion arranged along the periphery of the second surface and a groove portion arranged in the middle of the second surface and surrounded by the protrusion, and the end of the protrusion is on a positioning plane; the light refracted by the microlens can pass through the chip substrate and pass through the groove portion, and the focus falls on the positioning plane or has a fixed first distance relationship with the positioning plane.

[0026] Normally, it is expected that the focus falls directly on the positioning plane. In this case, the positioning plane of the chip is directly installed on the plane where the photosensitive surface of the detector is located. However, if the actual photosensitive surface has a certain deviation from the positioning plane, for example, there is a hollow frame between the positioning plane and the photosensitive surface, then the focus needs to be set at a position that exceeds the positioning plane by a certain distance, and the distance is equal to the thickness of the frame, and vice versa. The raised portion can be a complete enclosed groove portion, or it can be a discontinuous and interrupted surrounding groove portion. Various methods are possible, but at least the end face of the raised portion away from the root is required to form a positioning plane for contacting another plane to fix the position of the microlens.

[0027] As some examples of the above technical solutions, the present invention adopts a double-sided overlay process to form a double-sided heterogeneous structure to achieve accurate and rapid positioning of the silicon lens and the photodetector. This positioning mainly refers to the positioning and focusing of the distance on the optical axis, which is achieved through graphic design. The dimensional accuracy of the groove part on the back is very easy to control at the micron level. Therefore, the photodetector and one side of the lens chip are combined in a fixed plane to avoid axial position deviation of the lens and the detector.

[0028] As for some specific structural details, in some embodiments, the groove portion has a bottom surface and side walls, the bottom surface is perpendicular to the optical axis of the microlens; and the light refracted by the microlens forms a light spot area on the plane where the bottom surface is located, and the light spot area is within the contour of the bottom surface.

[0029] In some embodiments, the side wall is perpendicular to the bottom surface; or, the side wall forms an angle greater than 90° with the bottom surface, and the distance between the point on the side wall and the optical axis tends to increase in the direction away from the bottom surface. The above technical solution proposes two side wall forms, one is an inclined side wall, and the other is a vertical side wall. The inclined side wall is easier to process and has a slight effect on the propagation of light. It can be used when the precision required is not high. The bottom of the vertical side wall groove is smoother and has the least effect on the light path itself.

[0030] In some embodiments, the angle formed by the side wall and the bottom surface is in the range of 90-170°.

[0031] In addition, an embodiment of the present invention further provides a method for preparing the above-mentioned double-sided heterogeneous structure microlens chip, which comprises the following steps:

[0032] Microlenses and alignment marks are constructed on one side of the substrate by patterned etching;

[0033] The positioning structure is formed on the other side of the substrate by patterned etching using the alignment mark, and the positioning structure is made to correspond to the position of the microlens.

[0034] In some embodiments, the preparation method may specifically include the following process flow:

[0035] After forming the microlens, the chip substrate is processed by thinning and coating to form a first design distance, wherein the first design distance refers to the distance from the junction of the microlens and the chip substrate to the positioning plane;

[0036] Performing mask construction and reactive etching on the second surface to form the positioning structure, and controlling the depth of reactive etching to form a second designed distance, wherein the second designed distance refers to the distance from the bottom of the groove portion to the positioning plane;

[0037] The first design distance and the second design distance satisfy optical laws so that the focal position of the light is determined.

[0038] Specifically, in some embodiments, the optical law is expressed as:

[0039]

[0040] The focal length f of the lens can be expressed as:

[0041]

[0042] Among them, f represents the focal design distance, which refers to the distance from the desired focal point to the first surface; D is the bottom diameter of the microlens, R represents the curvature radius of the microlens spherical cap; h represents the spherical cap height of the microlens; and n represents the refractive index of the chip substrate.

[0043] The above calculation method provides a basic method for calculating the focal length of the lens, but the actual focal length may be affected by the thickness of the substrate. When the R value of the lens is much larger than the substrate thickness, the effect of the substrate thickness on the actual focal length can be ignored. If the two are approximate and need to be considered accurately, professional software is required for auxiliary calculation.

[0044] As a typical example, the depth of the groove portion (ie, the second designed distance d) is mainly controlled by etching time and etching rate, and the depth error can be controlled within 0.5 um.

[0045] As some typical application examples of the above technical solutions, a specific preparation process provided by the present invention etches the required pattern on the first side of the silicon wafer, and then uses the double-sided overlay process to accurately align and make the corresponding structure on the second side of the silicon wafer; by etching different patterns on both sides of the silicon wafer, a special-shaped conjoined morphology structure is made in the same vertical substrate, and the intersection of the two pattern structures is still a complete whole, thereby obtaining a double-sided heterogeneous structure, which is specifically performed according to the following steps:

[0046] (1) Produce symbols for two-side alignment and various required array patterns on two mask plates;

[0047] (2) After the surface of the substrate is cleaned, the following operations are performed on the front side (i.e., the first side) and the back side (i.e., the second side) of the silicon wafer:

[0048] Spin-coat photoresist evenly on the front of the silicon wafer, and then cure the liquid photoresist into solid photoresist by baking to form a uniform photoresist layer;

[0049] (3) performing ultraviolet exposure on the photoresist layer on the silicon wafer in an ultraviolet exposure machine;

[0050] (4) developing the desired pattern with a developer and producing the desired lens morphology by reflow;

[0051] (5) etching the desired lens morphology on the silicon wafer by an etching method, wherein the lens etching height ranges from 1 to 300 μm;

[0052] (6) After the above etching is completed, the entire silicon wafer is de-bonded and cleaned to complete the necessary semiconductor processes such as thinning and coating. The first side of the existing pattern is coated with a uniform coating to form a protective layer to protect the formed three-dimensional structure from being scratched or etched again;

[0053] (7) Perform the following operations on the second side, i.e., the back side, of the wafer:

[0054] Clean the second side, throw glue, bake glue, and prepare for exposure of the second side;

[0055] Use precise double-sided alignment technology to accurately position and UV-expose the second side of the silicon wafer;

[0056] Use developer to develop the desired pattern and protect the parts that do not need to be etched;

[0057] The reactive etching method is used again to etch the required structures on the second side of the silicon wafer to complete the double-sided patterning.

[0058] The embodiment of the present invention also provides the application of the above-mentioned double-sided heterogeneous structure microlens chip in the rapid installation and positioning of microlenses.

[0059] As a specific manifestation of the above application, see Figure 2 As shown, an embodiment of the present invention further provides a photoelectric detection combination structure, which includes a double-sided heterogeneous structure microlens chip 2 and a photoelectric detector 3 provided in any of the above embodiments;

[0060] The photodetector 3 has a mounting plane and a photosensitive surface. The mounting plane is fitted and fixed to the positioning plane of the double-sided heterogeneous structure microlens chip 2. The photosensitive surface and the mounting plane are in the same plane, or have a known and fixed second distance relationship and the second distance relationship matches the first distance relationship, so that the focus of the light 1 falls on the photosensitive surface.

[0061] In some embodiments, the photodetector 3 may include an infrared photodetector. It should be noted that the typical implementation case of the present invention takes the infrared detector 3 as a representative case, but it does not mean that the same technical concept cannot be extended to other bands, such as ultraviolet or visible bands.

[0062] The technical solution of the present invention is further described in detail below through several embodiments and in conjunction with the accompanying drawings. However, the selected embodiments are only used to illustrate the present invention, and do not limit the scope of the present invention.

[0063] Example 1

[0064] This embodiment provides a double-sided heterogeneous structure microlens chip with a front lens and a back groove, and its structure is as follows: Figure 2As shown in the microlens chip 2 in FIG. 1 , the focal length of the front microlens is related to the refractive index and curvature radius of the material itself. The distance D from the front plane of the front microlens root to the positioning plane of the back is , and the depth d of the groove on the back is adjusted by the etching process. The side wall of the groove is perpendicular to the bottom surface. The substrate used to make the lens is not limited to the silicon wafer. The refractive index n is determined by the material of the substrate. Therefore, the focusing point of the light perpendicularly incident on the microlens just falls on the plane where the outermost (rightmost in the figure) end face of the back groove is located.

[0065] When assembling the detection structure, the microlens chip is directly attached to the surface of a planar photodetector, and the central area of ​​the surface is the photosensitive surface of the photodetector. At this time, the focus of the vertically incident light falls exactly on the photosensitive surface.

[0066] Example 2

[0067] This embodiment is substantially the same as Embodiment 1, except that Figure 3 As shown, the side wall of the back groove is outwardly inclined, and the angle formed between it and the bottom surface is 170°.

[0068] Using the same optical principle, through direct bonding, the focus of this embodiment can still fall on the photosensitive surface of the photodetector.

[0069] What is different from the first embodiment is that due to the design of the above-mentioned inclined angle, the processing cost is lower, and it is more advantageous than the first embodiment in some application fields with relatively lower requirements.

[0070] Example 3

[0071] This embodiment is generally the same as Embodiment 1, with the main difference being that, when the mounting plane and the photosensitive surface of the photodetector are not on the same plane, the position of the focus can be adjusted (beyond the positioning plane or retracted into the groove portion) by adjusting the etching process and adjusting the etching depth of the groove portion to match the above-mentioned photodetectors of different shapes.

[0072] Based on the above embodiments, it can be clearly seen that the double-sided heterogeneous structure microlens chip provided by the present invention forms a precisely aligned positioning structure on the other side of the microlens, and the groove depth of the positioning structure is fixed, so that a fixed relationship is formed between the focal position of the lens chip and the positioning plane. When the positioning plane is directly or indirectly bonded to the photodetector to form a fixed relationship during installation, the focus can be directly placed on the sensing surface of the photodetector, which significantly improves the efficiency and accuracy of lens positioning.

[0073] It should be understood that the above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A double-sided heterogeneous structure microlens chip for rapid positioning, characterized in that: It includes a chip substrate, a micro lens and a positioning structure; The chip substrate has a first surface and a second surface facing each other, the microlens is formed on the first surface, and the positioning structure is formed on the second surface; The positioning structure comprises a protrusion arranged along the outer periphery of the second surface and a groove arranged in the middle of the second surface and surrounded by the protrusion, and an end of the protrusion is located on a positioning plane; The light refracted by the microlens can pass through the chip substrate and through the groove portion, and the focus falls on the positioning plane or has a fixed first distance relationship with the positioning plane.

2. The double-sided heterogeneous structure microlens chip according to claim 1, characterized in that: The groove portion has a bottom surface and a side wall, and the bottom surface is perpendicular to the optical axis of the microlens; The light refracted by the microlens forms a light spot area on the plane where the bottom surface is located, and the light spot area is within the contour of the bottom surface.

3. The double-sided heterogeneous structure microlens chip according to claim 2, characterized in that: The side wall is perpendicular to the bottom surface; Alternatively, the side wall and the bottom surface form an angle greater than 90°, and the distance between a point on the side wall and the optical axis tends to increase in a direction away from the bottom surface.

4. The double-sided heterogeneous structure microlens chip according to claim 3, characterized in that: The angle formed by the side wall and the bottom surface is in the range of 90-170°.

5. The method for preparing a double-sided heterogeneous structure microlens chip according to any one of claims 1 to 4, characterized in that: include: Microlenses and alignment marks are constructed on one side of the substrate by patterned etching; The positioning structure is formed on the other side of the substrate by patterned etching using the alignment mark, and the positioning structure is made to correspond to the position of the microlens.

6. The preparation method according to claim 5, characterized in that: Specifically include: After forming the microlens, the chip substrate is processed by thinning and coating to form a first design distance, wherein the first design distance refers to the distance from the junction of the microlens and the chip substrate to the positioning plane; Performing mask construction and reactive etching on the second surface to form the positioning structure, and controlling the depth of reactive etching to form a second designed distance, wherein the second designed distance refers to the distance from the bottom of the groove portion to the positioning plane; The first design distance and the second design distance satisfy optical laws so that the focal position of the light is determined.

7. The preparation method according to claim 6, characterized in that: The optical law is expressed as: The focal length f of the lens is expressed as: Among them, f represents the focal design distance, which refers to the distance from the desired focal point to the first surface; D is the bottom diameter of the microlens, R represents the curvature radius of the microlens spherical cap; h represents the spherical cap height of the microlens; and n represents the refractive index of the chip substrate.

8. Application of the double-sided heterogeneous structure microlens chip according to any one of claims 1 to 4 in the rapid installation and positioning of microlenses.

9. A photoelectric detection combination structure, characterized in that: A double-sided heterogeneous structure microlens chip and a photodetector comprising any one of claims 1 to 4; The photodetector has a mounting plane and a photosensitive surface. The mounting plane is bonded and fixed to the positioning plane of the double-sided heterogeneous structure microlens chip. The photosensitive surface and the mounting plane are in the same plane, or have a known and fixed second distance relationship and the second distance relationship matches the first distance relationship, so that the focus of the light falls on the photosensitive surface.

10. The photoelectric detection assembly structure according to claim 5, characterized in that: The photodetector comprises an infrared photodetector.

Images