Method for manufacturing lens unit, lens unit, imaging device, and endoscope

Abstract

A manufacturing method of a lens unit (1) includes: a step (S20) of manufacturing a stacked wafer (1W) including a plurality of optical wafers (10W, 20W, 30W) and having a first main surface (1SA) and a second main surface (1SB), the plurality of optical wafers (10W, 20W, 30W) including an optical wafer (20W) provided with a light-shielding layer (40); a step (S40) of forming, using a cutting blade (80), grooves (T1) of a depth at which the light-shielding layer (40) is cut in a lattice shape on the first main surface (1SA) or the second main surface (2SB) of the stacked wafer (1W); and a step (S50) of performing stealth dicing along the grooves (T1) using a filamentation laser to divide the stacked wafer (1W) into a plurality of lens units (1).

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a lens unit having step aberration on the side, a lens unit having step aberration on the side, an imaging device having a lens unit having step aberration on the side, and an endoscope including the imaging device, wherein the imaging device has a lens unit having step aberration on the side. Background Technology

[0002] To minimize invasiveness, it is important to reduce the diameter of the lens unit of the imaging device located at the front end of the endoscope.

[0003] International Publication No. 2017 / 203592 discloses a lens unit as a wafer-level stack capable of efficiently manufacturing small-diameter lens units. The wafer-level stack is manufactured by cutting a stack of wafers, wherein the stack of wafers comprises multiple optical wafers, each containing multiple lens elements.

[0004] In the case of a laminated wafer containing a hybrid optical wafer with multiple resin lenses disposed on a glass wafer, gaps may appear in the glass wafer during dicing. Therefore, it is not easy to manufacture a lens unit containing hybrid lenses. Furthermore, if gaps exist in the glass substrate of the diced hybrid lens, the reliability of the lens unit may be reduced.

[0005] Japanese Patent Application Publication No. 2009-072829 discloses a cutting method using a filamentation laser that can quickly process glass without creating gaps in it.

[0006] However, lasers cannot cut through light-shielding layers. Therefore, for example, lasers cannot be used to cut stacked wafers containing aperture layers.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: International Publication No. 2017 / 203592

[0010] Patent Document 2: Japanese Patent Application Publication No. 2009-072829 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] The purpose of the embodiments of the present invention is to provide a method for manufacturing a lens unit that is easy to manufacture and has high reliability, a lens unit that is easy to manufacture and has high reliability, an imaging device having a lens unit that is easy to manufacture and has high reliability, and an endoscope having a lens unit that is easy to manufacture and has high reliability.

[0013] Methods for solving problems

[0014] The method for manufacturing a lens unit according to the embodiment includes the following steps: a step of fabricating a stacked wafer comprising a plurality of optical wafers, the plurality of optical wafers comprising optical wafers on which a light-shielding layer constituting an aperture is disposed on a glass wafer, the stacked wafer having a first main surface and a second main surface opposite to the first main surface; a step of forming grooves of a depth for cutting the light-shielding layer in a grid pattern on the first main surface or the second main surface of the stacked wafer using a cutting blade; and a step of performing stealth cutting along the grooves using a silk-like laser to divide the stacked wafer into a plurality of lens units.

[0015] The lens unit of the embodiment has a plurality of optical elements, including a hybrid lens element having a glass substrate, a light-shielding layer forming an aperture, and a resin lens. The lens unit has four sides respectively having: a first region in which the side of the light-shielding layer is exposed and has a linear mark inclined relative to the optical axis; and a second region in which the second region is located further away from the optical axis than the first region and does not have the linear mark.

[0016] The imaging device of the embodiment includes a lens unit and an imaging unit. The lens unit has a plurality of optical elements, including a hybrid lens element. The hybrid lens element has a glass substrate, a light-shielding layer forming an aperture, and a resin lens. The four sides of the lens unit each have: a first region in which the side of the light-shielding layer is exposed and has a linear mark inclined relative to the optical axis; and a second region in which the second region is located further away from the optical axis than the first region and does not have the linear mark.

[0017] The endoscope of the embodiment includes a camera device having a lens unit and a camera unit. The lens unit has multiple optical elements, including a hybrid lens element. The hybrid lens element has a glass substrate, a light-shielding layer forming an aperture, and a resin lens. The lens unit has four sides respectively having: a first region in which the side of the light-shielding layer is exposed and has a linear mark inclined relative to the optical axis; and a second region located further away from the optical axis than the first region and without the linear mark.

[0018] Invention Effects

[0019] According to embodiments of the present invention, a method for manufacturing a lens unit that is easy to manufacture and has high reliability, a lens unit that is easy to manufacture and has high reliability, an imaging device having a lens unit that is easy to manufacture and has high reliability, and an endoscope having a lens unit that is easy to manufacture and has high reliability can be provided. Attached Figure Description

[0020] Figure 1 This is a perspective view of the camera device according to the first embodiment.

[0021] Figure 2 It is along Figure 1 A sectional view along line II-II.

[0022] Figure 3 This is a flowchart of the manufacturing method of the camera device according to the first embodiment.

[0023] Figure 4 This is an exploded perspective view illustrating the manufacturing method of the camera device according to the first embodiment.

[0024] Figure 5 This is a cross-sectional view used to illustrate the manufacturing method of the camera device according to the first embodiment.

[0025] Figure 6 This is a cross-sectional view used to illustrate the manufacturing method of the camera device according to the first embodiment.

[0026] Figure 7 This is a cross-sectional view of the camera device of the first embodiment, variant 1.

[0027] Figure 8 This is a cross-sectional view of the camera device of Modified Example 2 of the first embodiment.

[0028] Figure 9 This is a three-dimensional view of the endoscope according to the second embodiment. Detailed Implementation

[0029] <First Implementation Method>

[0030] Figure 1 , Figure 2 The imaging device 2 of the illustrated embodiment includes a lens unit 1 and an imaging unit 60. Reference numeral O indicates the optical axis of the lens unit 1. The imaging unit 60 receives the subject image converged by the lens unit 1 and converts it into an imaging signal.

[0031] Furthermore, in the following description, the accompanying drawings of each embodiment are schematic. The relationship between the thickness and width of each part, the ratio of the thickness of each part, and the relative angles, etc., differ from the actual structure. The drawings also include parts with different dimensional relationships and ratios. Some constituent elements are omitted from the illustration.

[0032] The lens unit 1 includes a first optical element 10 having an incident surface 1SA, a second optical element 20, and a third optical element 30 having an exit surface 1SB. The first optical element 10, the second optical element 20, and the third optical element 30 are stacked in sequence.

[0033] The first optical element 10 uses a first glass substrate 11 as a base, the first glass substrate 11 having a first main surface 11SA as an incident surface 1SA and a second main surface 11SB opposite to the first main surface 11SA. The first optical element 10 is a hybrid lens element having a resin lens 12 as a concave lens on the second main surface 11SB.

[0034] The second optical element 20 uses a second glass substrate 21 as its base, which has a third main surface 21SA and a fourth main surface 21SB opposite to the third main surface 21SA. The third main surface 21SA is arranged opposite to the second main surface 21SB. The second optical element 20 is a hybrid lens element having a resin lens 22 as a convex lens on the third main surface 21SA and a resin lens 23 as a convex lens on the fourth main surface 21SB. A light-shielding layer 40, which constitutes an aperture and is made of a metal mainly composed of chromium or titanium, is disposed on the fourth main surface 21SB.

[0035] The third optical element 30 is a third glass substrate 31, which has a fifth main surface 31SA and a sixth main surface 31SB, which is the opposite side of the fifth main surface 31SA and serves as the emission surface 1SB. The fifth main surface 31SA is arranged opposite to the fourth main surface 21SB.

[0036] The first glass substrate 11, the second glass substrate 21, and the third glass substrate 31 are, for example, made of borosilicate glass, quartz glass, or sapphire glass.

[0037] The first optical element 10 and the second optical element 20, the second optical element 20 and the third optical element 30 are respectively bonded by an adhesive layer 50 made of resin.

[0038] Furthermore, the structure of the lens unit of the present invention is not limited to the structure of lens unit 1 in this embodiment, and can be set according to specifications. For example, the lens unit may not only have lens elements, but also spacer elements that define the distance between lenses and multiple light-shielding layers.

[0039] An imaging unit 60 is bonded to the sixth main surface 31SB (emission surface 1SB) of the third optical element 30 via an adhesive layer 51. Within the imaging unit 60, a glass cover 63 is bonded to the imaging element 61 via an adhesive layer 62. The lens unit 1 images the subject onto the imaging element 61. The imaging element 61 is a CMOS (Complementary Metal Oxide Semiconductor) light-receiving element or a CCD (Charge Coupled Device).

[0040] The lens unit 1 has four sides 1SS, each having: a first region 1SSA in which the side of the light-shielding layer 40 is exposed and has a linear mark that is inclined relative to the optical axis direction; and a second region 1SSB, which is located further away from the optical axis O than the first region 1SSA and does not have the linear mark.

[0041] Linear marks are characteristic of the cut surface of the first region 1SSA, which is cut using a first method with a cutting blade. On the other hand, the second region is characterized by the cut surface of the cut surface, which is cut using a second method without a cutting blade.

[0042] The light-shielding layer 40 is cut using a first method with a cutting blade, thus exposing the side in the first region 1SSA.

[0043] As described later, the cutting amount of the second method is smaller than that of the first method. Therefore, the second region 1SSB is located further away from the optical axis O than the first region 1SSA. In other words, there is a step at the boundary between the first region 1SSA and the second region 1SSB in the side surface 1SS of the lens unit 1 (the side surface 21SS of the second glass substrate 21).

[0044] Furthermore, the length L1 of the first region 1SSA along the direction parallel to the optical axis is shorter than the length L2 of the second region 1SSB. In other words, the length L2 of the side surface formed by the invisible cut of the lens unit 1 is longer than the depth L2 of the groove formed by the cutting blade.

[0045] In lens unit 1, the second method is stealth cutting using a filament laser. The light-shielding layer 40, which cannot be cut by laser, is cut using the first method with a cutting blade. Furthermore, the incident surface 1SA, which is most prone to notching, is cut last by the second method, which prevents notches from being formed in the glass substrate. Therefore, lens unit 1 is easy to manufacture and has high reliability.

[0046] <Manufacturing Method>

[0047] Lens unit 1 is a wafer-level optical unit manufactured by cutting a stacked wafer 1W on which multiple optical wafers are stacked, wherein the multiple optical wafers are arranged in a matrix with multiple optical elements.

[0048] The following is in accordance with Figure 3 The flowchart is shown to illustrate how to pass through a stacked wafer 1W (refer to...). Figure 4 ) A stacked chip 2W (refer to) is configured with multiple camera units 60 Figure 5 , Figure 6 The method of manufacturing camera device 2 by cutting off the part of the camera is used as an example to illustrate this.

[0049] <Process S10> Fabrication of multiple optical wafers

[0050] like Figure 4 As shown, the optical wafer 10W is fabricated by arranging a plurality of resin lenses 12 on the second main surface 11SB of the glass wafer 11W. The reference numeral CL denotes multiple cut lines in a lattice pattern. The resin lenses 12 are preferably made of energy-curable resin.

[0051] Energy-curing resins undergo cross-linking or polymerization reactions by receiving energy from external sources such as heat, ultraviolet light, or electron beams. Examples of energy-curing resins include transparent, ultraviolet-curable silicone resins, epoxy resins, and acrylic resins. It should be noted that "transparent" refers to a material with minimal light absorption and scattering, sufficient to withstand use within the operating wavelength range.

[0052] Since it is uncured, a liquid or gel-like resin is applied to the glass wafer 11W, and the resin lens 12 is manufactured by molding by irradiating the resin with ultraviolet light while pressing it against a mold with a recess having a specified inner surface shape. Furthermore, to improve the interfacial adhesion strength between the glass and the resin, it is preferable to perform a silane coupling treatment on the glass wafer before applying the resin.

[0053] Since the outer surface shape of the resin lens manufactured by molding is transferred to the inner surface shape of the mold, it is easy to produce aspherical lenses with an outer edge that also serves as a spacer.

[0054] Optical wafer 20W is fabricated in the same manner as optical wafer 10W. In optical wafer 20W, a light-shielding layer 40 is disposed before the resin lens 23 is disposed on the fourth principal surface 21SB of glass wafer 21W. For example, multiple light-shielding layers 40 are fabricated by patterning a metal layer disposed on the fourth principal surface 21SB using a sputtering method. The light-shielding layer 40 is mainly composed of chromium or titanium. "Main component" means 90% by weight or more. To ensure light-shielding properties, the thickness of the light-shielding layer 40 is, for example, 0.2 μm to 2 μm.

[0055] <Process S20> Wafer Stacking

[0056] like Figure 4 As shown, optical wafers 10W, 20W, and 30W are stacked. Although not shown, adhesive layers 50 are respectively applied to the resin lens 12 of optical wafer 10W, the resin lens 22 of optical wafer 20W, and the resin lens 23 using a transfer method. The adhesive layers 50 can be applied, for example, using an inkjet printing method. The adhesive layers 50 are, for example, thermosetting epoxy resin. The optical element wafers (optical wafers) 10W-30W are stacked and bonded to fabricate the stacked wafer 1W. The stacked wafer 1W has an incident surface 1SA and an exit surface 1SB opposite to the incident surface 1SA.

[0057] <Process S30> Configure camera unit

[0058] Multiple camera units 60 are bonded to the exit surface 1SB (sixth main surface 31SB) of the stacked wafer 1W using adhesive layer 51, thereby fabricating the stacked wafer 2W.

[0059] The camera unit 60 is manufactured by cutting a camera chip to which a glass wafer is bonded using a transparent adhesive on a camera element chip containing multiple light-receiving circuits. Alternatively, the camera chip can be bonded to a stacked chip 1W to manufacture a stacked chip 2W.

[0060] <Process S40> Forming the groove

[0061] like Figure 5 As shown, the incident surface 1SA (first main surface 11SA) of the optical wafer 10W is attached to a fixing component such as a dicing tape 90 in the laminated wafer 2W. Then, a dicing blade 80 is used to form a groove T1 on the laminated wafer 2W along a grid-like cutting line CL to cut the depth of the light-shielding layer 40.

[0062] <Process S50> Laser Cutting

[0063] like Figure 6 As shown, along the groove T1 (cutting line CL), a filament laser is used for stealth cutting to divide the stacked wafer 2W into multiple lens units 1.

[0064] Filamentation is a significant phenomenon in high-intensity femtosecond lasers. It is a dynamic, nonlinear optical effect that propagates in equilibrium through the convergence and divergence of light, allowing light to travel long distances while remaining focused, thereby generating linear plasma. Therefore, in a stacked wafer 2W that is stealthily cut using a filamentation laser, a modified region is generated along the scanning direction. The stacked wafer 2W with the modified region is then divided into multiple lens units 1 along the scanning direction, i.e., along the groove T1, by applying external stress. The stress applied to the stacked wafer 2W for this division can be mechanically applied or generated through thermal treatment.

[0065] The width (cutting depth) of the groove T1 formed by the cutting blade 80 is 50μm-200μm, while the cutting depth of the filamentary laser is only 1μm-3μm. In principle, a machining mark parallel to the optical axis is generated in the second region 1SSB segmented by the filamentary laser. However, due to the extremely fine nature of these machining marks, most are not clearly observable.

[0066] The imaging device 2 is manufactured using a wafer-level process, resulting in a small diameter and ease of fabrication. Furthermore, when cutting the stacked wafer 1W, the optical wafer 10W, which is particularly prone to breakage and adheres to the cutting strip 90, is separated using stealth dicing with a silk laser. Therefore, the lens unit 1 and the imaging device 2 are easy to manufacture, and since there are no gaps in the glass substrate, reliability is high.

[0067] Alternatively, the camera device 2 can be manufactured by arranging the camera unit 60 in the lens unit 1 manufactured by cutting the laminated wafer 1W.

[0068] When cutting the stacked wafer 1W, a groove can be formed on the incident surface 1SA using a dicing blade, and the wafer can be divided along the groove by stealth dicing. However, the length L2 of the second region 1SSB formed by stealth dicing is shorter than the depth of the groove formed by the dicing blade (the length L1 of the first region). Therefore, the time required for groove formation is longer compared to the case where the groove is formed on the exit surface. Therefore, it is preferable to form the groove on the exit surface. In other words, it is preferable that the length L2 of the second region 1SSB formed by stealth dicing is longer than the depth of the groove formed by the dicing blade (the length L1 of the first region).

[0069] <Modifications of the First Embodiment>

[0070] The lens units 1A and 1B and the imaging devices 2A and 2B in the modified examples of the first embodiment are similar to those of lens unit 1 and imaging device 2, and have the same effect. Therefore, the same reference numerals are used to label the constituent elements with the same function and the description is omitted.

[0071] <Modification 1 of the first embodiment>

[0072] Figure 7 The imaging device 2A (lens unit 1A) of this modified example shown has a light-shielding layer 40A disposed on the first optical element 10. That is, the light-shielding layer 40A is disposed on the second main surface 11SB of the first glass substrate 11.

[0073] Although not shown in the figure, during the manufacture of lens unit 1A, the exit surface 1SB of the stacked wafer 1W is fixed to a cutting strip. Grooves of the depth required to cut the light-shielding layer 40A are formed in a lattice pattern on the incident surface 1SA. Lens unit 1A is divided by stealth cutting using a filamentary laser irradiated along the grooves. Then, imaging device 2A is manufactured by arranging imaging unit 60 within the monolithic lens unit 1A.

[0074] In lens unit 1A, a groove is formed on the incident surface 1SA. The length L1 of the first region 1SSA of the side surface 1SS cut by a blade is shorter than the length L2 of the second region 1SSB of the side surface 1SS cut by stealth cutting. Therefore, the time required for lens unit 1A to cut is shorter.

[0075] <Modification 2 of the first embodiment>

[0076] Figure 8 The imaging device 2B (lens unit 1B) of this modified example has light-shielding layers 40 and 40A, made of light-shielding resin, serving as adhesive layers on the first optical element 10 and the second optical element 20. Furthermore, the third optical element 30A is a filter element that removes unwanted infrared radiation (e.g., light with wavelengths above 700 nm). The third optical element 30A cannot be laser-cut.

[0077] Although not illustrated, during the manufacture of lens unit 1B, the incident surface 1SA of the stacked wafer 2W is fixed to the dicing strip 90. Grooves of a depth sufficient to cut the filter wafer and the light-shielding layers 40 and 40A are formed in a grid pattern on the exit surface 1SB. The bottom surface of the grooves is located within the first glass wafer.

[0078] In the lens unit 1B, the side surfaces of the light-shielding layers 40 and 40A and the side surface of the third optical element 30A, which serves as a filter element, are exposed in the first region 1SSA, which is the wall surface of the groove formed by the cutting blade.

[0079] The optical wafer 10W, which is particularly prone to breakage and adhered to the cutting strip 90, is divided using stealth cutting with a silk laser. Therefore, the lens unit 1B and the imaging device 2B are easy to manufacture, and since there are no gaps in the first glass substrate 11, reliability is high.

[0080] <Second Implementation Method>

[0081] Figure 9 The endoscope 9 of this embodiment shown includes a front end portion 9A, an insertion portion 9B extending from the front end portion 9A, an operation portion 9C disposed at the base end side of the insertion portion 9B, and a universal cable 9D extending from the operation portion 9C. An imaging device 2 (2A, 2B) including lens units 1 (1A, 1B) is disposed at the front end portion 9A. Imaging signals output from the imaging device 2 are transmitted to a processor (not shown) via a cable inserted into the universal cable 9D. Additionally, drive signals from the processor to the imaging device 2 are also transmitted via a cable inserted into the universal cable 9D.

[0082] The endoscope 9 can be a flexible endoscope with a flexible insertion part 9B, or a rigid endoscope with a rigid insertion part 9B. Furthermore, the endoscope 9 can be used for medical or industrial purposes.

[0083] The endoscope 9 is equipped with an imaging device 2 (2A, 2B) including lens units 1 (1A, 1B), which makes it easy to manufacture and highly reliable.

[0084] This invention is not limited to the embodiments described above, and various modifications, combinations, and applications can be made without departing from the spirit of the invention.

[0085] Label Explanation

[0086] 1, 1A, 1B... Lens Units

[0087] 1W...Layered Chips

[0088] 2, 2A, 2B... camera devices

[0089] 2W...Layered Chips

[0090] 9...Endoscope

[0091] 10...First optical element

[0092] 11...First glass substrate

[0093] 12... Resin lens

[0094] 20...Second optical element

[0095] 21...Second glass substrate

[0096] 22...Resin lens

[0097] 23...Resin Lens

[0098] 30, 30A... Third optical element

[0099] 31...Third glass substrate

[0100] 40, 40A... Light-shielding layer

[0101] 50, 51... Adhesive layers

[0102] 60... camera units

[0103] 80...cutting blade

[0104] 90...cutting strip

Claims

1. A method for manufacturing a lens unit, characterized in that, It includes the following processes: The process of fabricating a stacked wafer, wherein the stacked wafer comprises a plurality of optical wafers, the plurality of optical wafers comprising an optical wafer on which a light-shielding layer constituting an aperture is disposed, and the stacked wafer has a first main surface and a second main surface opposite to the first main surface; The process of forming grooves in a grid pattern on the first or second main surface of the stacked wafer to cut the light-shielding layer to a certain depth using a cutting blade; as well as The process of using a silk-like laser to perform stealth cutting along the groove to divide the stacked wafer into multiple lens units. The lens unit has four sides, each having a first region, in which the side of the light-shielding layer is exposed, and the first region has a linear mark that is inclined relative to the optical axis direction. And a second region, which is located further away from the optical axis than the first region and is free of the linear marks.

2. The method for manufacturing a lens unit according to claim 1, characterized in that, The stacked wafer comprises multiple light-shielding layers. All light-shielding layers contained in the stacked wafer are cut off by forming the grooves.

3. The method for manufacturing a lens unit according to claim 1, characterized in that, The stacked wafers include filter wafers. The filter wafer is cut by forming the groove.

4. The method for manufacturing a lens unit according to claim 2, characterized in that, The stacked wafers have an adhesive layer made of a light-shielding resin, which bonds the plurality of optical wafers. The adhesive layer is cut off by forming the groove.

5. The method for manufacturing a lens unit according to claim 2, characterized in that, The filamentation laser is irradiated onto the bottom surface of the groove.

6. The method for manufacturing a lens unit according to claim 5, characterized in that, The length of the side surface formed by the invisible cut of the lens unit is longer than the depth of the groove formed by the cutting blade.

7. A lens unit, characterized in that, The lens unit has multiple optical elements, including a hybrid lens element. The hybrid lens element has a glass substrate, a light-shielding layer forming an aperture, and a resin lens. The lens unit has four sides, each having a first region, in which the side of the light-shielding layer is exposed, and the first region has a linear mark that is inclined relative to the optical axis direction. And a second region, which is located further away from the optical axis than the first region and is free of the linear marks.

8. The lens unit according to claim 7, characterized in that, The plurality of optical elements include filter elements. The first region includes the side surface of the filter element.

9. A camera device, characterized in that, The camera device includes a lens unit and a camera unit. The lens unit has multiple optical elements, including a hybrid lens element. The hybrid lens element has a glass substrate, a light-shielding layer forming an aperture, and a resin lens. The four sides of the lens unit each have a first region, in which the side of the light-shielding layer is exposed, and the first region has a linear mark that is inclined relative to the optical axis direction. And a second region, which is located further away from the optical axis than the first region and is free of the linear marks.

10. An endoscope, characterized in that, The endoscope includes a camera device with a lens unit and a camera unit. The lens unit has multiple optical elements, including a hybrid lens element. The hybrid lens element has a glass substrate, a light-shielding layer forming an aperture, and a resin lens. The four sides of the lens unit each have a first region, in which the side of the light-shielding layer is exposed, and the first region has a linear mark that is inclined relative to the optical axis direction. And a second region, which is located further away from the optical axis than the first region and is free of the linear marks.

Images