JP5445030B2 - Camera module and manufacturing method thereof - Google Patents

Description

  The present invention relates to a camera module, and more particularly to a technique for thinning a camera module to be mounted on a mobile phone.

  It is common practice to attach a camera to a mobile phone. The camera is built in a mobile phone as a camera module that uses a charge coupled type (CCD type) or complementary oxide semiconductor type (C-M0S type) solid-state imaging device in the camera body, and in addition a lens. ing.

  As shown in FIG. 4, there are two cameras that are mounted on the mobile phone 40. The first camera 41 is a high-definition camera having about 5 to 10 million pixels, and is not much different from a normal camera. The second camera 42 is a video dedicated camera having about 100,000 to 300,000 pixels, and is mainly a videophone camera. By operating the input button 43, the caller himself / herself or the other party's face can be shown on the display screen 44.

  As shown in FIG. 5, the conventional camera module is a camera module 50 including a solid-state imaging device 51 and about two to three lenses 52a and 52b, and is entirely supported by a camera frame 53 made of synthetic resin. ing. The camera frame 53 is colored black to block light from the surroundings. On the light receiving element surface of the solid-state image sensor 51, color separation color filters and condensing microlenses are formed for each pixel, but are too small to be shown in FIG. Further, the cover glass 54 protects the surface.

  As shown in FIG. 5, the solid-state imaging device 51 of the camera module 50 is electrically connected by an electrode of a conductive layer 56 of a printed circuit board 55, a wire bond ink, a pole grid array (hereinafter referred to as BGA) system, or the like. The image information converted into electrical signals is taken out.

  However, since the camera module 50 as shown in FIG. 5 uses a camera frame 53 made of synthetic resin, there is a problem that it is difficult to perform automatic mounting by the reflow method. Furthermore, it is inevitable that the printed circuit board 55 is bulky in the vertical direction due to the thickness of the printed circuit board 55 itself. This has hindered the reduction in thickness and weight of mobile phones.

  Therefore, a structure that can be manufactured by a wafer process has been proposed for the purpose of reducing the size and thickness of the camera module. The camera module 60 shown in FIG. 6 is an example. In FIG. 6, a silicon substrate 1 that is a solid-state image sensor has a color separation color filter 16 and a light condensing microlens 17 formed in each pixel on the light receiving element surface on the upper surface thereof. An electrical signal of image information obtained by the solid-state imaging device is guided to the back surface of the silicon substrate 1 by a conductive material 2 that fills or coats the through silicon via (hereinafter referred to as TSV) and is patterned. The insulating layer 3 and the conductive layer 4 enable connection to an external circuit at the connection terminal 5 by the BGA method.

Above the silicon substrate 1, a sealing glass plate 7 is bonded through a frame wall 6 to make the light receiving region airtight. Although the thickness of the frame wall 6 is exaggerated in the figure, it is as thin as about 50 μm. On the sealing glass plate 7, a first lens body 14 formed by forming a lens made of a transparent resin on the front and back surfaces of the first lens base 9 is overlaid through a first spacer 8 made of glass. Further, a second lens body 15 formed by forming a lens made of a transparent resin is overlapped on the front and back surfaces of the second lens base 11 through a second spacer 12 made of glass. In the illustrated example, the first lens body 14 is a concave lens, and the second lens body is a convex lens. A lens made of a transparent resin is produced by a fine molding method or a photolithography method. Finally, the cover glass plate 13 is bonded through the third spacer 12. The cover glass plate 13 often serves also as an infrared cut glass.

  The camera module 60 shown in FIG. 6 shows only one product, but in the actual manufacturing process, a processing process for a glass plate having a diameter of 20 to 30 cm is combined with a processing process for a silicon wafer having a diameter of 20 to 30 cm. Literally manufactured by a wafer process, and finally cut individually in a dicing process to form one camera module. In the camera module 60 of FIG. 6, if it is a second camera mounted on a mobile phone, the size of the silicon substrate 1 is only about 3 mm square, so 1,600 to 2,800 pieces from a single wafer of 20 cm in diameter. Can be taken.

  However, the camera module 60 of FIG. 6 also has a problem to be solved. This is because the spacers 8, 10 and 12 and the lens bases 9 and 11 stacked on the silicon substrate 1 are all made of glass and have sufficient strength to circulate the wafer process production line. The thickness is about 0.4 mm. For this reason, the height of the lens portion of the camera module 60 is considerably increased, which hinders the reduction in size and thickness of the camera module.

  In particular, the thickness of the spacers 8, 10, and 12 is related to the thickness of the lens elements 9a, 9b, 11a, and 11b formed on both surfaces of the lens bases 9 and 11, and the thickness of the lens elements 9a, 9b, 11a, and 11b. As the thickness increases, the thicknesses of the spacers 8, 10, and 12 increase, which is a bottleneck for thinning the camera module 60.

JP 2008-124919 A

  The present invention is intended to realize further thinning of the camera module manufactured by the wafer process described above, and the manufacturing process does not require manpower or labor, and the wafer is processed in the process. The present invention provides a structure of a camera module that can be easily and mass-produced by adopting a process, and a manufacturing method thereof.

The camera module according to the present invention comprises:
A sealing glass plate is bonded via a frame wall on a solid-state imaging device in which a color separation color filter and a condensing microlens are formed for each pixel on the light receiving element surface on the upper surface. In addition,
Absorbing glass plate comprising a lens body, the lens elements made of etched recesses in a transparent resin lens substrate having etched recesses formed on the front and rear surfaces of the area where the lens elements, wherein the etch concave portion is the thickness of the front and back of the lens element the formed lens body formed as,
It is characterized in that at least one sheet is laminated without interposing a spacer .

A method for manufacturing a camera module according to the present invention includes:
It is characterized in that at least the following steps (a) to ( d ) are performed on a solid-state imaging device manufactured in a large number by imposing a wafer on a wafer process.
(A) A multi-sided arrangement in which the positional relationship with the solid-state imaging device is matched to a glass plate having the same diameter and thickness of 0.4 mm to 2.0 mm as a silicon wafer for producing a solid-state imaging device serving as a lens substrate By the process of forming a large number of etching recesses on the front and back surfaces to be the formation location of the lens element,
(B) a step of forming a lens element made of a transparent resin in an etching recess of a lens base having a large number of the etching recesses so that the etching recess absorbs the thickness of the lens elements on the front and back sides to form a lens body;
(C) A sealing glass plate is bonded via a frame wall on a solid-state imaging device in which a color separation color filter and a condensing microlens are formed for each pixel on the light receiving element surface on the upper surface. In addition, a process in which at least one lens body is laminated without using a spacer in a state in which the positional relationship is aligned, to form a camera module.
( D ) A step of cutting along the cutting line between the camera modules to separate each camera module.

According to the present invention, a concave portion is formed on the front and back surfaces of a glass wafer by a wafer process, and a lens is formed and accommodated in the concave portion, whereby the thickness of the camera module can be reduced, and at the same time, a conventionally required spacer The member can be omitted.
Therefore, from the solid-state imaging device formation sky on the silicon wafer to the completion of the camera module, it can be manufactured consistently by a wafer process without human intervention, and the manufacturing process is suitable for mass production and contributes to cost reduction.
Since this camera module is thin and light, a portable camera using the camera module is also reduced in size and weight.

It is a figure of the cross-sectional view explaining the structure of the camera module which accommodated the lens in the recessed part which becomes this invention. It is process drawing of the cross sectional view explaining the process of forming a recessed part in the front and back of a glass wafer and forming a lens in this recessed part which become this invention. It is process drawing of the cross sectional view which illustrates typically an example of the camera module manufacturing process which becomes this invention. It is a schematic diagram explaining a camera module being mounted on a mobile phone. It is a figure of the cross-sectional view explaining the structure of the conventional camera module. It is a figure of the cross-sectional view explaining the structure of the camera module of a conventional structure. It is a figure of the sectional view explaining typically signs that a lens is formed in a crevice of a glass wafer using a gradation mask.

Hereinafter, the present invention will be described with reference to FIGS.
FIG. 1 shows a camera module 60 according to an embodiment of the present invention. The part of the solid-state image sensor is basically the same as the camera module of FIG. In FIG. 1, a silicon substrate 1 of a solid-state imaging device has a color separation color filter 16 and a condensing microlens 17 formed for each pixel on the light receiving element surface on the upper surface thereof. The electrical signal of the image information obtained by the solid-state imaging device is guided to the back surface of the silicon substrate 1 through the aluminum electrode 18 by the conductive material 2 that fills or coats the through-silicon via (TSV), The patterned insulating layer 3 and conductive layer 4 enable connection to an external circuit at the connection terminal 5 by the BGA method.

  Above the silicon substrate 1, a sealing glass plate 7 is bonded through a frame wall 6 to make the light receiving region airtight. Although the thickness of the frame wall 6 is exaggerated in the drawing, it is as thin as about 50 μm. On the sealing glass plate 7, in the illustrated embodiment, the first lens body 19 is directly laminated without using a spacer. The first lens base 20 of the first lens body 19 has a concave portion at the center on the front and back surfaces thereof, a convex lens element 20a is formed at the concave portion on the upper surface, and a concave lens element 20b is formed at the concave portion on the lower surface. ing.

  Unlike the conventional example, the reason why the first lens body 19 can be laminated on the solid-state image sensor without using a spacer is that the concave portion formed in the first lens base 20 is the thickness of the lens elements 20a and 20b. It is because it absorbs. Of course, it is not denied that a spacer is interposed between the sealing glass plate 7 and the first lens body 19, but in that case, a spacer thinner than the conventional example is sufficient. As a preferred embodiment, it is recommended that the original thickness of the first lens base 20 be increased by a necessary amount to omit the spacer component because it is simple in terms of structure and manufacturing.

  Further, in the embodiment of FIG. 1, the second lens body 21 is laminated and bonded onto the first lens body 19. In the illustrated example, the first lens body 19 is a concave lens, and the second lens body 21 is a convex lens. The lens elements 20a, 20b, 22a, and 22b made of transparent resin are formed by a fine molding method (also referred to as a nano-implant molding method) or a photolithography method.

  Finally, the cover glass plate 13 is attached. The cover glass plate 13 often serves also as an infrared cut glass.

  In addition, an electroless plating layer 61 for preventing flare and having a light shielding property may be provided on the side wall. The material is a single plating layer of a metal selected from nickel, chromium, cobalt, iron, copper, gold, etc., as well as an alloy selected from a combination of nickel-iron, cobalt-iron, copper-iron, etc. An electroplating layer is mentioned. In addition, a metal such as copper is electrolessly plated, and then the surface thereof is chemically or oxidized to form a metal compound to form a metal light-shielding layer having a low light reflectance on the surface.

  The electroless plating layer 61 preferably has a high light-shielding performance of an optical density of 2.0 or more by a Macbeth densitometer. From this point of view, it is convenient to use a metal as the light-shielding layer. In the normally used metal plating layer 61, a thickness of 0.1 to 1.0 μm is sufficient to achieve an optical density of 2.0 or more.

  A method for manufacturing a camera module according to the present invention will be described below in detail with reference to FIGS. 2 (a) to 2 (e) and FIGS.

FIG. 2 shows an example of a manufacturing method of the lens bodies 19 and 21 (see FIG. 1) used in the present invention. FIG. 2 (a) shows a glass plate 23 to be the lens bases 20 and 22, and the material thereof is, for example, borosilicate glass, alumina silicate glass, soda lime glass or the like. Its size is the same diameter as the silicon wafer for producing the solid-state imaging device, for example, 20 to 30 cm. Its thickness is about 0.4 mm to 2.0 mm. If the thickness is less than 0.4 mm, the material is not robust and cannot be applied to the wafer process processing and manufacturing apparatus, so this thickness is the lower limit. The upper limit is determined in consideration of the relationship with the thickness of the lens element to be applied in a later process and the lens design for ensuring the required optical path length. However, for the purpose of the present invention, the thickness of the glass plate 23 should be as thin as possible.

  Hydrofluoric acid resistant resist films 24a and 24b are formed in a pattern on both surfaces of the glass plate 23. As the resist film, a commercially available hydrofluoric acid-resistant photosensitive resin is used. If a photosensitive resin is used, resist films 24a and 24b having a desired pattern can be formed on both surfaces of the glass plate 23 by a series of photolithography processes including coating, pattern exposure, development, and heat fixing. In addition to this organic photosensitive resin, the lower side is supplemented with a patterned thin film of metal nickel, silver, chrome, etc. to make a double layer of a metal layer and a photosensitive resin. It is also practical to do.

  Next, the glass plate 23 is wet-etched with a hydrofluoric acid-based etchant. The hydrofluoric acid-based etching solution is preferably a mixed system of hydrofluoric acid + ammonium fluoride, hydrofluoric acid and sulfuric acid, hydrochloric acid, phosphoric acid, or ammonium salt, rather than hydrofluoric acid alone. Compared to hydrofluoric acid alone, the etching rate is increased and the smoothness of the etched surface is improved. In any case, it is used in an aqueous solution. FIG. 2B shows a state after the etching is finished. The portions where the resists 24a and 24b are not provided are dissolved to form the recesses 26a and 26b.

  Next, as shown in FIG. 2 (c), the resist films 24a and 24b are peeled off by contacting with an alkaline aqueous solution such as caustic soda, caustic potash or sodium carbonate. The completed lens base 20 having a plurality of etching recesses on the front and back surfaces is continuously provided by a frame-like body 27 that maintains the original thickness.

  Next, lens elements 28a and 28b are formed in the etching recesses 26a and 26b on the front and back sides. The lens elements 28a and 28b are generally made of a transparent synthetic resin. There are two types of preparation methods.

  One is the application of microfabrication technology called nano-imprint molding. In this method, a female mold of the lens element 28 is previously made of metal or glass, a release agent is applied to the molding surface, and a transparent resin uniformly applied to the etching recess 26 (that is, a photosensitive resin) The lens element is formed by pressing the female mold. After molding, if the transparent resin is photosensitive, the lens element can be cured by performing overall exposure and heat treatment. Although the lens element 28 is small, it has a diameter of about 2.5 mm and is sufficiently large for this molding method.

  The other is the application of photolithography. FIG. 7 schematically shows a creation means by the photolithography method. In this method, the transparent resin used as the lens element 28 is the photosensitive resin 71, and preferably a positive photosensitive resin 71 is used. In this method, in order to create the shape of the lens element 28 by the exposure method, a special exposure mask 72 called a gradation mask is used. The mask 72 is formed by forming a light-shielding film 73 on a transparent substrate having a high light transmittance for the thin film portion of the lens element 28 to be created and a light transmittance for the thick film portion of the lens element 28. It is. It can be said that the mask 72 has a light-shielding film 73 with gradation of gradation. This gradation of gradation is achieved by a partial difference in the number (rough density) per unit area of small-diameter dots (halftone dots) that are not resolved by the light used for exposure.

As shown in FIG. 7 (a), the positive photosensitive resin 71 coated on the one surface of the lens base 20 with a uniform thickness is passed through an exposure mask 72 having a light-shielding film 73 having a gradation pattern. The parallel light 75 is irradiated from the above. In the example shown in the figure, a lot of light is blocked in the central portion, and more light passes through the mask 72 as it goes to the peripheral portion. Thereafter, if a known process from development to heat fixing is performed, a convex lens element 28 as shown in FIG. 7B can be formed in the concave portion of the lens base 20. It is obvious that the lens element can be formed in the concave portion on the back surface by repeating the same process on the back surface of the lens base 20.

  The advantage of using positive photosensitive resin 71 in this method is that it is easier to correlate between the amount of irradiated light and the film thickness of the photosensitive resin remaining after development than with negative photosensitive resin. is there.

  Thus, as shown in FIG. 2 (d), a lens structure 29 in which a large number of lens bodies 19 are connected is formed by either of the above-mentioned two types of means. The lens body 21 is also created by the same means.

  Subsequently, a process of completing a camera module by combining a solid-state imaging device and a lens body will be described with reference to FIGS.

  As described above, this step can be continuously performed by a wafer process. That is, as shown in FIG. 3A, a large number of solid-state imaging elements 31 are formed on a silicon wafer 30 having a diameter of 20 to 30 cm. In general, a color filter for color separation, a microlens for condensing light to a light receiving unit, and the like are formed on the light receiving surface of each solid-state imaging device, and a BGA as an external connection terminal is provided on the back surface of the wafer. These are too small for illustration. A frame wall 32 is formed on the surface of each solid-state imaging device 31 so as to surround the periphery. Although the thickness of the frame wall 32 is exaggerated in the figure, it is as thin as about 50 μm.

  Next, as shown in FIG. 3B, a sealing glass plate 33 is attached to the frame wall 32. The sealing glass plate 33 is a glass plate having the same diameter as that of the silicon wafer 30. The frame wall 32 is a material having an adhesive property with the sealing glass 33.

  Next, as shown in FIG. 3C, a lens structure 29 in which a large number of first lens bodies 19 are arranged is laminated. The bonding is performed between the surface of the sealing glass plate 33 and the lower surface of the frame-shaped body 27 of the lens structure 29.

  Next, as shown in FIG. 3D, the second lens structure 34 is bonded and bonded. The joining is a joining of a frame-like body 35 in which a large number of lens bodies 21 are arranged and the frame-like bodies 27.

  Finally, the cover glass plate 36 is bonded. The state shown in FIG. 3 (e) is a state in which lens bodies and transparent glass plates are stacked on a multi-layer floor on a silicon wafer 30, and a camera module is manufactured by multi-sided attachment. If the center part of the frame-like bodies 27 and 35 is set as a cutting line and is cut from the top to the bottom with a dicing machine, as shown in FIG. 38 is obtained.

  Specific examples of the present invention will be described below. The composition ratios in the examples are mass ratios unless otherwise specified.

(1) Preparation of lens body For an alumina borosilicate glass wafer having a thickness of 0.5 mm and a diameter of 20 cm (Zn0 ₂ 1%, Al ₂ O ₃ 5%, B ₂ O ₃ 40%, SiO ₂ 14%) A 200-nm-thick metal chromium layer is formed on both sides, and an acrylic-epoxy photosensitive resin is applied to a thickness of 2 μm. A resist film was formed in which a portion corresponding to 1 was an opening. With this resist film, the underlying metal chromium screen was etched to form a corrosion resistant film made of a double film made of a cured product of metal chromium and a photosensitive resin. The shape of the corrosion-resistant film has an opening where an etching recess should be formed.

Subsequently, glass etching was performed by a dipping method at room temperature with a mixed etching solution of 10% hydrofluoric acid and 10% NH4OH to form an etching recess having a depth of 125 μm from both sides.

  Subsequently, a novolac resin-based positive type transparent photosensitive resin, trade name AZ-1350 (manufactured by Hoechst Japan Co., Ltd.) is applied to the glass wafer surface to a thickness of 100 μm, and the gradation mask shown in FIG. The lens element was exposed and developed using 73 to form a convex lens element only in the etching concave part, and then subjected to a heating process at 180 ° C. for 30 minutes to smooth the surface of the lens element and fix and cure it at the same time. . Through similar processes, a convex lens element is formed on the back surface of the glass wafer, and a lens structure 29 in which a large number of convex lens bodies are connected to a glass wafer having a diameter of 20 cm via a frame 27 is created. did.

  The concave lens structure can also be formed in the same process except that the density of the dot pattern is reversed from that when the gradation mask is formed as a convex lens.

(2) Stacking with Solid-State Imaging Device A description will be given based on FIGS. A large number of solid-state imaging devices 31 shown in FIG. 3A were formed on a silicon wafer 30 having a thickness of 0.25 mm and a diameter of 20 cm. A sealing glass plate 33 having a thickness of 0.4 mm and a diameter of 20 cm was bonded to the upper surface by using the frame wall 32 provided on the upper surface of the solid-state imaging device 31 instead of the spacer / adhesive layer. (See Fig. 3 (b))
Next, an epoxy-urethane adhesive is applied to the lower surface of the frame-like body 27 of the concave lens-shaped first lens structure 29 by a roll coating method at about 5 μm. At this time, since the lens element of the first lens structure 29 is located behind the frame-like body 27, no adhesive is applied to the lens element. The adhesive is applied only to the lower surface of the frame 27. In this state, the first lens structure 29 was joined to the solid-state imaging device 31 in alignment. (See Figure 3 (c))
Next, a convex lens-shaped second lens structure 34 is laminated on the first lens structure 29 and bonded together by a similar method. At this time, it goes without saying that the lens structure and the solid-state imaging device are aligned. (See Fig. 3 (d))
Subsequently, a cover glass having a thickness of 0.4 mm and a diameter of 20 cm was bonded onto the second lens structure 34. The method is to apply the adhesive selectively by the roll coat method in the same manner as described above only on the upper surface of the frame-like body 35 which is the uppermost surface of the second lens structure 34, and press the cover glass with a uniform pressure, Heat-cured. (See Fig. 3 (e))
Finally, by using a dicing apparatus using a 450 mesh resin blade, a cutting groove was formed from the surface with the central portion of the frame-shaped body as a cutting line. Thereafter, it was separated into individual camera modules 38 to obtain a finished product in the state shown in FIG.

  As described above, when the camera module of the present invention is formed on a single silicon wafer with multiple faces, parts such as spacers can be omitted, and the overall thickness can be reduced. Combined with the convenience when it is incorporated into the above, it is suitable for mass production, contributes to cost reduction, and is extremely excellent in practical use.

1. Silicon substrate 2, through hole (conductive material)
3, insulating layer 4, conductive layer,
5. Connection terminal (BGA)
6, frame walls 7, 33, sealing glass plate 8, first spacer 9, first lens base 10, second spacer 11, second lens base 11a, 11b, lens 12, third spacer 13, 54, cover glass Plate 14, first lens body 15, second lens body 16, color filter 17, microlenses 19 and 21, lens bodies 20 and 22, lens base 23, glass plate 24, resist film 26, recesses 27 and 35, frame shape Body 28, lens element 29, lens structure 30, silicon wafers 31, 51, solid-state imaging device 32, frame wall 36, cover glass plates 38, 50, 60, camera module 61, light shielding film 40, mobile phone 41, first Camera 42, second camera 43, input button 44, display surfaces 52a and 52b, lens 53, camera frame 55, printed circuit board 56, conductive layer 71, positive photosensitive resin 72 Exposure mask 73, the light shielding film 75, the parallel light

Claims (6)

A sealing glass plate is bonded via a frame wall on a solid-state imaging device in which a color separation color filter and a condensing microlens are formed for each pixel on the light receiving element surface on the upper surface. In addition,
Absorbing glass plate comprising a lens body, the lens elements made of etched recesses in a transparent resin lens substrate having etched recesses formed on the front and rear surfaces of the area where the lens elements, wherein the etch concave portion is the thickness of the front and back of the lens element the formed lens body formed as,
A camera module , wherein at least one sheet is laminated without a spacer . 2. The camera module according to claim 1, wherein the lens element is formed on a photosensitive resin applied to the etching recess by a nano-imprint molding method or a photolithography method. When laminating the first lens body and the second lens body from the solid-state imaging device side, the second lens body is configured to be joined around the etching recesses of the first and second lens bodies. The camera module according to claim 1 or 2. A method for manufacturing a camera module, comprising: performing at least the following steps (a) to ( d ) on a solid-state image pickup device produced in a number of ways on a wafer by a wafer process.
(A) A multi-sided arrangement in which the positional relationship with the solid-state imaging device is matched to a glass plate having the same diameter and thickness of 0.4 mm to 2.0 mm as a silicon wafer for producing a solid-state imaging device serving as a lens substrate By the process of forming a large number of etching recesses on the front and back surfaces to be the formation location of the lens element,
(B) a step of forming a lens element made of a transparent resin in an etching recess of a lens base having a large number of the etching recesses so that the etching recess absorbs the thickness of the lens elements on the front and back sides to form a lens body;
(C) A sealing glass plate is bonded via a frame wall on a solid-state imaging device in which a color separation color filter and a condensing microlens are formed for each pixel on the light receiving element surface on the upper surface. In addition, a process in which at least one lens body is laminated without using a spacer in a state in which the positional relationship is aligned, to form a camera module.
( D ) A step of cutting along the cutting line between the camera modules to separate each camera module. 5. The method of manufacturing a camera module according to claim 4, wherein the lens element is formed by a nano-imprint molding method or a photolithography method on a photosensitive resin applied to the etching recess. In the step (c), when laminating the first lens body and the second lens body from the solid-state imaging device side, the second lens body is bonded around the etching recesses of the first and second lens bodies. The method of manufacturing a camera module according to claim 4 or 5, characterized in that:

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