JP5162607B2 - Assembling the camera module - Google Patents

Description

  The present invention relates to a method for assembling an ultra-small camera module comprising a solid-state imaging device to which a wafer level, chip size, and package mounting technology is applied and an optical lens for forming an image at the center of the light receiving surface. It is.

  A solid-state imaging device chip is formed by forming an imaging element and an optical element such as a microlens on a semiconductor substrate (hereinafter referred to as a “wafer”) and hermetically sealing it. It is used as a light receiving sensor for video equipment such as a camera for mobile phones.

  FIG. 3A schematically shows an example of a structural cross-sectional view of a typical solid-state image pickup device chip (this is referred to as “chip on which a solid-state image pickup device is formed”) used in a conventional camera module. FIG. In this solid-state imaging device chip 100, a large number of photodiodes 101 functioning as light receiving surfaces are formed on the surface of the semiconductor substrate S, and microlenses 102 are provided via color filters 103 corresponding to the respective photodiodes. . Then, wire bonding 104 is applied to each of a large number of electrode terminals provided around the chip, and these are packaged.

  FIG. 3B is a diagram schematically showing an example of a structural cross-sectional view of a camera module completed by attaching a lens unit to the solid-state imaging device chip 100 shown in FIG. Note that an alternate long and short dash line that vertically cuts through the center of the figure indicates the optical axis of the lens 116. The solid-state imaging device chip 100 is attached to a circuit board 110, and a circuit is configured by a printed wiring 111 called an FPCB (Flexible Printing Circuit Board), and a socket 112 serves as an interface of this circuit.

  An infrared blocking filter 113 is provided above the light receiving surface of the solid-state image sensor chip 100. Both are fixed by a lens barrel holder (lens barrel support) 114 attached to the circuit board 110 together with the chip 100. The lens barrel holder 114 and the lens barrel (lens holding frame) 115 are provided with screw grooves, and both are fixed by screwing.

  During this assembly process, the optical axis (the one-dot chain line in the figure) of the condensing lens 116 coincides with the center of the light receiving surface of the solid-state imaging device chip 100, and the light receiving surface is installed perpendicular to the optical axis. (Optical axis alignment) is required.

JP 2005-286422 A International Publication No. 2006/73085

  However, since the solid-state image sensor chip 110 having a conventional package structure that employs the wire bonding method has a lot of gaps with respect to the lens barrel holder 114, the optical axis is likely to be shifted when the camera module is assembled. Axis alignment is required, and this is a factor that reduces the yield in the manufacturing process.

  The reason is that when the solid-state imaging device chip is mounted on the substrate by the die bonder, positional variations are likely to occur, and the optical axis is likely to be shifted. Also, when the lens barrel holder is mounted on the substrate, positional variations are likely to occur, which is considered to be one of the factors that cause the optical axis to deviate.

  Moreover, the assembly error of the optical axis alignment allowed in the solid-state imaging device applying the wafer level chip size package mounting technology that is required to be lower than the conventional one is compared with the previous generation wire bonding method etc. It is a well-known fact that it is at least an order of magnitude smaller.

  Further, in the case of a conventional package in which a large number of wire bonds are applied to the end face of the solid-state image sensor chip, the lens barrel holder is fixed to the circuit board, but not to the solid-state image sensor chip. For this reason, there has been a problem that the optical axis tends to shift during the assembly process of the lens barrel. Therefore, as a matter of course, it was also vulnerable to external shocks.

  In terms of mechanical strength, as described in Patent Document 2, a technique of providing a protective frame around a chip having a known wafer level, chip size, and package structure is also known. However, only a configuration that increases the strength of the solid-state imaging device itself is disclosed.

  The present invention has been made in view of the above, and has as its main technical problem to provide a novel method for assembling a camera module that does not require optical axis alignment after the assembly of the camera module.

  The present invention relates to paragraphs [0018] to [0025] (embodiments) and [0028] to [0033] (second modified example, etc.) of the original specification of Japanese Patent Application No. 2006-351923, which is the basic application of the present application. The configuration for realizing the technical idea related to the portion described in the modified example is used as a problem solving means.

The first camera module assembling method according to the present invention includes an end face (T) that is flush with the through electrode (15) for passing through the inside of the light receiving surface and connecting to the terminal on the back surface side and is perpendicular to the light receiving surface. A solid-state imaging device chip (10) having a wafer level chip size package structure, and a substantially cylindrical outer frame (24) covering the periphery of the solid-state imaging device chip. And
By screwing and fixing a lens barrel (25) in which one or a plurality of lenses (26) condensing on the light receiving surface is horizontally supported and fixed in a hollow manner at the periphery thereof, to one end of the outer frame body, The step of arranging the lens barrel so that the center of the light receiving surface and the center of the optical axis of the lens coincide with each other on the basis of the vertical wall inside the other end of the outer frame,
Characterized in that it comprises a step of fixing said and the vertical end faces to the vertical wall and without clearance fit to the lower end from the upper end of the solid-state imaging device chip above the solid-state image pickup device chip and the outer frame body across said end face And

  In the present invention, “the center of the light receiving surface” refers to a diagonal center portion of a rectangular light receiving region including a photodiode and a microlens. Since the solid-state image sensor chip is provided with peripheral circuits, registers, and the like, the center of the light receiving surface is not necessarily at the center of the solid-state image sensor chip. That is, aligning the optical axis is nothing but adjusting so that the center of the optical axis of the lens coincides with the center of the light receiving surface and the light receiving surface is fixed perpendicular to the optical axis.

  Wafer level chip size package is a mounting technology that separates the elements after forming the elements and wiring process on a single semiconductor wafer, and is flat on the four end faces T cut along the scribe line. (In the present specification, this is referred to as “a flush end face”).

  In the present invention, since a solid-state image sensor chip having a through electrode and an electrode terminal such as a solder ball is presupposed in the present invention, the “same end surface” of the solid-state image sensor chip is used as a reference plane for optical axis alignment. be able to. As a result, the position of the center of the light receiving surface of the solid-state image sensor chip can be specified with reference to the flush end surface of the solid-state image sensor chip, and the optical axis alignment is completed when the assembly is completed.

  Therefore, even in a wafer level chip size package that requires extremely high assembly accuracy, optical axis alignment can be performed strictly, and it is not necessary to perform optical axis alignment after the assembly process.

  Furthermore, the camera module assembled by the first camera module assembling method according to the present invention has a lens barrel fixed to one end of the outer frame, and a solid-state image sensor chip on the vertical wall inside the other end of the outer frame. The vertical end surface of the solid-state image sensor chip is fitted with no gap from the upper end to the lower end of the solid-state image sensor chip, so it has greater mechanical strength than any other type of camera module, including camera modules with known chip size and package structure. Can be secured.

The second camera module assembling method according to the present invention includes an end surface (T) that is flush with the through electrode (15) for passing through the inside of the light receiving surface and connecting to a terminal on the back surface side and is perpendicular to the light receiving surface. A solid-state imaging device chip (10) having a wafer level chip size package structure, and a substantially cylindrical outer frame (24) covering the periphery of the solid-state imaging device chip. And
One or a plurality of lenses (26) for condensing on the light receiving surface is horizontally supported at the periphery of the lens (26) so as to be fixed to one end of the outer frame body, whereby the vertical inside the other end of the outer frame body is secured. Placing the lens such that the center of the light receiving surface and the center of the optical axis of the lens coincide with a wall as a reference;
Characterized in that it comprises a step of fixing said and the vertical end faces to the vertical wall and without clearance fit to the lower end from the upper end of the solid-state imaging device chip above the solid-state image pickup device chip and the outer frame body across said end face And

The solid-state image pickup device chip in the first or the assembly process of the second camera module according to the present invention, together with obtained if a microlens on the light receiving surface, the upper surface portion of the microlenses, a relatively refractive index than the microlens A low transparent material may be provided. The transparent material is preferably a transparent resin containing fine pores dispersed therein. As a result, high sensitivity can be maintained without substantially impairing the light collecting effect of the microlens.

  The outer frame body 24 (24a to 24c) in the method for assembling the first or second camera module according to the present invention is preferably made of a light-shielding material. In this case, since the outer frame body 24 is configured to cover the side end surface of the solid-state imaging device chip 10, the periphery of the lens barrel lens is completely covered when the assembly is completed, so that the light shielding performance is further increased. The optical performance is improved.

  The camera module assembling method according to the present invention does not require alignment of the optical axis after assembling the camera module, and can ensure the overall mechanical strength including the optical system.

FIG. 1A is a diagram schematically showing a structural cross-sectional view of a solid-state imaging device chip used in a camera module according to the present invention. FIG. 1B shows a basic configuration of a camera module completed by attaching a lens unit to the solid-state image sensor chip. FIG. 2A is a diagram showing a first modification of the embodiment of the present invention. FIG. 2B is a diagram showing a second modification of the embodiment of the present invention. FIG. 3A is a diagram schematically showing an example of a structural cross-sectional view of a typical solid-state imaging device chip used in a conventional camera module. FIG. 3B is a diagram schematically showing an example of a structural cross-sectional view of a camera module completed by attaching a lens unit to the solid-state imaging device chip shown in FIG.

(Embodiment)
FIG. 1 is a diagram for explaining a configuration of a first camera module according to the present invention, and FIG. 1A is a structural cross-sectional view of a solid-state imaging device chip used in the camera module according to the present invention. It is the figure shown typically. In this solid-state imaging device chip 10, a large number of photodiodes 11 functioning as light receiving surfaces are formed on the surface of the semiconductor substrate S, and microlenses 12 are provided via color filters 13 corresponding to the respective photodiodes. .

  As is clear from FIG. 1A, this solid-state imaging device chip 10 has a three-dimensional wafer level chip size package structure (in particular, a through electrode 15 and a solder ball (BGA or LGA) 19 inside). Type and called “3D-CSP”). A transparent plate 16 is provided on the microlens 12, and the transparent plate 16 is supported by ribs 17 surrounding the four sides. The rib 17 is a part where a scribe line for separating into individual pieces is formed after the imaging element chip is formed, and a dicing process is performed along the scribe line after completing all processes in a wafer state. The rib 17 plays a role of separating the chips, but a flat end face T always appears after separation. (Conversely, the structure in which the end faces obtained by dicing after singulation are not flush is not possible as a structure obtained from the manufacturing process of a normal wafer level chip size package. This point is extremely important. .)

  FIG. 1B shows a basic configuration of a camera module completed by attaching a lens unit to the solid-state image sensor chip 10. The configuration in which the outer frame body 24 is screwed to the lens barrel 25 is the same as in the prior art, but the lower part of the outer frame body 24 is fitted to the position adjustment frame 18 provided on the four end faces T of the solid-state image sensor chip 10. It is provided to do. The position adjustment frame 18 is not essential, and is an arbitrary configuration for functioning as a spacer. This is because not only the light receiving unit (light receiving surface) but also the peripheral circuits are formed on the same substrate in the solid-state image pickup device chip. This is because it may not coincide with the center.

  When the position adjustment frame 18 is not necessary, the end surface T that contacts the cut surface of the rib is directly fitted to the outer frame body 24. In this sense, the position adjustment frame may be asymmetric. A solder ball 19 such as a ball grid array (BGA) is provided on the bottom of the solid-state imaging device chip 10, and the camera module is attached to the circuit board 20.

  The outer frame body 24 and the solid-state image sensor chip 10 are fixed by an adhesive. At this time, a recess 27 may be provided as a space for retracting excess adhesive. Both the outer frame body 24 and the position adjustment frame 18 are made of a light-shielding material.

  Thus, by providing a space for fixing the solid-state image sensor chip 10 designed so that the optical axis of the entire camera is aligned with the outer frame body 24 and adopting a configuration in which the solid-state image sensor chip 10 is loaded therein, The optical axis of the entire camera is difficult to shift.

  When a protective frame that surrounds a rectangular chip separated along the scribe line is provided for a solid-state image sensor chip with a wafer level, chip size, and package structure, mechanical strength increases, and external shocks are prevented. In addition to being strong, there are advantages such as blocking light from the side, but the present invention further integrates the protective frame and the outer frame for supporting the lens (or lens barrel). The structure is characterized in that it eliminates the need to align the optical axis of the lens.

  That is, as shown in FIG. 3B, in the case of a conventional package in which a large number of wire bonds are applied to the end face of the solid-state image pickup device chip 100, the lens barrel holder 114 is fixed to the circuit board. The chip 100 is not fixed. For this reason, there has been a problem that the optical axis tends to shift during the assembly process of the lens barrel. However, in the case of the camera module according to the present invention, the solid-state imaging device chip having the wafer level, chip size, and package structure fits exactly in the space provided in the lower part of the outer frame body 24, so that there is a problem that the optical axis is shifted. Does not occur.

(First modification)
FIG. 2A is a diagram showing a first modification of the embodiment of the present invention, and shows a configuration in which the infrared blocking filter 23 is provided on the lens barrel side. In addition, the same code | symbol is used for the site | part which shows the same function as FIG. According to this structure, since it is not necessary to provide an infrared shielding filter on the outer frame body 24a side, the structure is simplified.

  Also in this case, since the optical axis of the camera is determined by the outer frame body 24b for positioning the solid-state imaging device chip 10, the optical axis is shifted during the assembly process by designing the optical axis in advance. There is nothing.

(Second modification)
FIG. 2B is a view showing a second modification of the embodiment of the present invention, and shows a configuration in which a lens barrel and an outer frame are integrally formed. In addition, the same code | symbol is used for the site | part which shows the same function as FIG. Conventionally, the lens barrel and the solid-state imaging device chip are configured separately and are generally screwed and fixed, but in this embodiment, the lens barrel is integrally formed with the outer frame, In other words, the outer frame body 24c having a special structure integrated with the lens barrel is provided.

  As described above, since the outer frame 24c is integrated with the lens barrel, the optical axis is more difficult to shift, and the assembly process using a die bonder or the like is not necessary, thereby further simplifying the assembly process. .

(Other variations)
The internal structure of the camera module according to the present invention is not particularly limited as long as it is applied to a solid-state imaging device chip adopting a wafer level chip size package structure. For example, all of the solid-state imaging device chip structures shown in the above-described embodiments (including modifications) are provided with a transparent plate 16 on the upper surface of the microlens 12 (see FIG. 1A). The space between the transparent plate and the microlens surrounded by the ribs 17 is filled with air (refractive index = 1), but instead of providing a gap with the ribs 12 and the transparent plate 16, it is more relative to the microlens. Alternatively, the gap may be filled with a transparent material having a low refractive index. In particular, in recent years, when a microlens is formed of a high refractive index material having a refractive index value exceeding 2, for example, the selection range of the transparent material to be filled is further expanded, and a material having a higher refractive index can be used.

  As the transparent material, a material having a lower refractive index than that of the microlens is selected. Specifically, for example, it is preferable to use a thermosetting transparent resin or a UV curable transparent resin containing fine pores dispersed therein. For this purpose, a normal spin coat method is used to maintain a thickness of several μm so that the entire surface of the wafer (wafer before singulation) is almost uniform, and pores are formed by a relatively low temperature thermosetting process. By curing while expanding, a homogeneous transparent resin having a refractive index in a range of theoretically less than 1.0 to 1.5 (in practice, a refractive index of about 1.1 to 1.4) is formed. be able to. When this low refractive index resin is used, high sensitivity can be maintained without substantially impairing the light collecting effect of the microlens.

Furthermore, practically as a low refractive index transparent material, for example, in a highly integrated semiconductor integrated circuit device (LSI) having a refractive index lower than the refractive index of silicon dioxide (SiO ₂ ) or microlens material covering the light receiving surface. Of course, it is possible to use low-permittivity, low-density dielectrics such as interlayer insulation films for multilayer wiring, or viscous materials such as polymer compounds. Even when a protective layer made of hard transparent resin or the like is provided on the transparent material, the optical characteristic loss due to the difference in refractive index between each layer is negligible.

Other applicable transparent materials include translucent low-density dielectric films such as silicon dioxide (SiO ₂ ), porous silica films, organic-inorganic hybrid films, and polymer compounds, which are relatively in comparison to microlenses. It must be of low refractive index.

  Moreover, it is also possible to laminate | stack the infrared rays shielding film on the surface as needed. In that case, the infrared shielding filter 23 shown in FIGS. 1B, 2A, and 2B is not necessary.

  As described above, the solid-state imaging device chip 10 to be loaded has a wafer level chip size package structure that is separated into pieces by dicing after completion of the chip (however, the four end faces are flush), in particular. It is not limited.

  An ultra-small camera module incorporating a solid-state imaging device to which wafer level chip size package mounting technology is applied is applied to many devices such as a mobile phone with a camera function. Industrial applicability is extremely large as a technology that can effectively suppress the optical axis shift in the process.

DESCRIPTION OF SYMBOLS 10 Solid-state image sensor chip | tip 12 Micro lens 15 Through electrode 18 Position adjustment frame 20 Circuit board 24 Outer frame body 25 Lens barrel

Claims (7)

Solid-state imaging of a wafer level chip size package structure comprising a light receiving surface and a through electrode (15) penetrating the inside and connecting to a terminal on the back surface side and an end surface (T) flush with the light receiving surface and perpendicular to the light receiving surface An element chip (10);
An assembly method of a camera module including a substantially cylindrical outer frame (24) covering the periphery of the solid-state imaging device chip,
By screwing and fixing a lens barrel (25) in which one or a plurality of lenses (26) condensing on the light receiving surface is horizontally supported and fixed in a hollow manner at the periphery thereof, to one end of the outer frame body, The step of arranging the lens barrel so that the center of the light receiving surface and the center of the optical axis of the lens coincide with each other on the basis of the vertical wall inside the other end of the outer frame,
Characterized in that it comprises a step of fixing said and said end faces perpendicular to the vertical wall and without clearance fit to the lower end from the upper end of the solid-state imaging device chip above the solid-state image pickup device chip and the outer frame body across said end face How to assemble the camera module. Solid-state imaging of a wafer level chip size package structure comprising a light receiving surface and a through electrode (15) penetrating the inside and connecting to a terminal on the back surface side and an end surface (T) flush with the light receiving surface and perpendicular to the light receiving surface An element chip (10);
An assembly method of a camera module including a substantially cylindrical outer frame (24) covering the periphery of the solid-state imaging device chip,
One or a plurality of lenses (26) for condensing light on the light receiving surface is fixed to one end of the outer frame body by supporting it horizontally and hollowly at the peripheral edge of the outer frame body. Placing the lens such that the center of the light receiving surface and the center of the optical axis of the lens coincide with a wall as a reference;
Characterized in that it comprises a step of fixing said and said end faces perpendicular to the vertical wall and without clearance fit to the lower end from the upper end of the solid-state imaging device chip above the solid-state image pickup device chip and the outer frame body across said end face How to assemble the camera module. The solid-state image sensor chip is
A microlens (12) is provided on the light receiving surface,
The method for assembling a camera module according to claim 1, wherein a transparent material having a refractive index relatively lower than that of the microlens is provided on an upper surface portion of the microlens.   4. The method for assembling a camera module according to claim 3, wherein the transparent material is a transparent resin containing fine pores dispersed therein.   The method of assembling a camera module according to claim 1, wherein the outer frame body is made of a light-shielding material. Solid-state imaging of a wafer level chip size package structure comprising a light receiving surface and a through electrode (15) penetrating the inside and connecting to a terminal on the back surface side and an end surface (T) flush with the light receiving surface and perpendicular to the light receiving surface An element chip (10);
A camera module formed by fitting a substantially cylindrical outer frame (24) covering the periphery of the solid-state imaging device chip,
A lens barrel (25) in which one or a plurality of lenses (26) condensing on the light receiving surface is horizontally supported and fixed in a hollow manner at the periphery thereof is screwed and fixed to one end of the outer frame body,
The lens barrel is disposed so that the center of the light receiving surface and the optical axis center of the lens coincide with each other with the vertical wall inside the other end of the outer frame as a reference,
Wherein the end faces perpendicular to said vertical wall is fixed and the outer frame body and the solid-state imaging device chip and without clearance fit to the lower end from the upper end of the solid-state imaging element chip across the end surface The camera module. Wafer level chip size package comprising a light receiving surface and a through electrode (15) penetrating the inside and connecting to a terminal on the back surface side such as a solder ball and an end surface (T) that is flush with and perpendicular to the light receiving surface A solid-state imaging device chip (10) having a structure;
A camera module formed by fitting a substantially cylindrical outer frame (24) covering the periphery of the solid-state imaging device chip,
One or more lenses (26) for condensing on the light receiving surface are fixed to one end of the outer frame body while being horizontally supported horizontally at the peripheral edge thereof,
The lens is arranged so that the center of the light receiving surface coincides with the optical axis center of the lens with respect to a vertical wall inside the other end of the outer frame body,
Wherein the end faces perpendicular to said vertical wall is fixed and the outer frame body and the solid-state imaging device chip and without clearance fit to the lower end from the upper end of the solid-state imaging element chip across the end surface The camera module.

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