JP2002290842A - Manufacturing method for solid-state image sensing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce variance in relative position precision among respective solid-state image sensing devices to an optical lens. SOLUTION: A lens array 33 which has optical lenses 34 is bonded onto one main surface of a wafer 31 where image sensors 32 are formed in array. At this point, they are bonded so that mutual positioning marks A and B meet each other, and consequently the optical lenses 34 correspond to the photodetection areas of the image sensors 32. The wafer 31 where the lens array 33 is bonded is divided according to the array of the image sensors 32 to form respective solid-state image sensing devices.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a solid-state imaging device for storing information charges corresponding to an image of a subject to be incident.

[0002]

2. Description of the Related Art A camera unit mounted on a digital still camera or the like is a lens unit in which a CCD (charge coupled device) image sensor is mounted on a circuit board, and the image sensor is mounted with an optical lens in another process. Formed by packaging.

FIG. 9 is a plan view showing the structure of an image sensor, for example, a frame transfer type image sensor. In the frame transfer type image sensor, an imaging unit 1, a storage unit 2, a horizontal transfer unit 3, and an output unit 4 are formed on one chip. The imaging unit 1 includes a plurality of vertical shift registers arranged in parallel with each other, and each bit of these vertical shift registers forms each light receiving bit. The imaging unit 1 accumulates information charges generated according to incident light in each bit during a light receiving period, and transfers and outputs the information charges in a vertical direction according to a frame transfer clock φf during a transfer period.

The storage section 2 is composed of a plurality of vertical shift registers continuous from the image pickup section 1, and takes in and accumulates information charges output from the image pickup section 1 during a transfer period according to a vertical transfer clock φv. The horizontal transfer unit 3 includes one row of horizontal shift registers in which each column of the vertical shift register continuous from the imaging unit 1 and the storage unit 2 corresponds to each bit, and receives an output transferred from the storage unit 2 for each bit. Outputs information charges in units of one pixel in accordance with the horizontal transfer clock φh. The output unit 4 includes an electrically independent capacitance, an amplifier for extracting a potential change of the capacitance, and a reset transistor for discharging information charges accumulated in the capacitance.
, The information charges output in pixel units are sequentially converted into voltage values and output as video signals Y (t).

FIG. 10 is a sectional view schematically showing a camera unit having an image sensor and a lens unit mounted on a circuit board.

The package 11 has a box shape having a concave portion of a predetermined depth, and houses an image sensor having the same configuration as that shown in FIG. This package 11
, A plurality of leads 12 are embedded, external leads are arranged along the side surface of the package 11, and internal leads are arranged around the image sensor in the concave portion. Electrodes provided as input terminals on the periphery of the image sensor are connected to the internal leads of the plurality of leads 12 by wire bonding. Then, a transparent plate made of a glass material or a resin material is mounted so as to cover the concave portion of the package, and the wiring connecting the image sensor and the lead 12 is protected. The circuit board 13 is made of an insulating material such as a glass epoxy resin, and has a wiring pattern formed of copper foil on one or both surfaces. This circuit board 13 includes
Through holes 14 corresponding to the plurality of leads 12 of the package 11 are formed, and the package 11 is mounted at a predetermined position by passing the leads 12 through the through holes 14. Thereby, the package 1 is arranged such that the wiring pattern of the circuit board 13 corresponds to the external electrode of the image sensor.
1 is attached. Through these wiring patterns, an image sensor and a drive circuit for driving the image sensor, a signal processing circuit for capturing an output video signal, and the like are connected. The circuit board 13 has a pair of through holes for positioning with the lens unit 16.
It is provided as.

The lens unit 16 includes a mount 17 and a lens barrel 18. The mounting portion 17 is provided with positioning pins 19 on the surface to be bonded to the circuit board 13 so as to correspond to the positioning holes 15, and is mounted on the circuit board 13 through the positioning pins 19. An optical lens 20 is attached to the lens barrel 18 at a position corresponding to the light receiving area of the image sensor.

[0008]

The relative positional accuracy between the optical lens and the light receiving area of the image sensor greatly affects the image signal output through the camera unit.
Therefore, high positional accuracy is required for the alignment between the image sensor and the optical lens. However, since the relative positional accuracy between the optical lens and the light receiving area of the image sensor depends on many components, it is difficult to make it uniform in each camera unit.

For this reason, when the camera unit is formed, it is necessary to detect a relative positional shift between the optical lens and the light receiving area of the image sensor and correct the respective positions. Such a process is performed for each camera unit, and causes an increase in the number of camera unit manufacturing steps, resulting in an increase in manufacturing cost.

In view of the above, the present invention has been made in view of the above-mentioned problem, and reduces a variation in relative positional accuracy between an optical lens and a light receiving area of an image sensor. In addition, a camera unit is formed. An object of the present invention is to provide a method for manufacturing a solid-state imaging device that can reduce the number of steps.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is characterized in that information charges are received by receiving a subject image in a light receiving area in which a plurality of light receiving pixels are arranged. In the method of manufacturing a solid-state imaging device for storing,
A first step of forming the plurality of light receiving areas on one main surface of the substrate, and an optical lens for forming a subject image on the light receiving area corresponding to the arrangement of the plurality of light receiving areas formed on the substrate A second step of bonding a plurality of lens arrays formed on one main surface of the substrate, and a third step of dividing the substrate to which the lens array is bonded according to the arrangement of the plurality of light receiving regions. And the step of

In a method of manufacturing a solid-state imaging device for receiving an image of a subject in a light-receiving region in which a plurality of light-receiving pixels are arranged and accumulating information charges, a plurality of light-receiving regions are formed on one main surface of a substrate. And a lens array in which a plurality of optical lenses for forming a subject image in the light receiving area are formed in correspondence with the arrangement of the plurality of light receiving areas formed on the substrate. A second step of adhering to a first main surface of a spacer array having a plurality of openings formed corresponding to the first step, and a second main surface of the spacer array and a first main surface of the substrate, A third step of adhering the openings and the light receiving areas so as to correspond to each other, and a fourth step of dividing the substrate to which the spacer array is adhered according to the arrangement of the plurality of light receiving areas. Characterized by

[0013]

1 to 4 are views for explaining a first embodiment of the present invention.

First Step First, a single-crystal silicon ingot is prepared by cutting the outer periphery of a single-crystal silicon ingot to a wafer diameter and thinly slicing it to prepare a single-crystal silicon wafer 31. At this time, an orientation flat for determining the in-plane crystal orientation of the wafer 31 is formed at one end of the wafer 31 at the stage of grinding the outer periphery of the single crystal silicon ingot. Subsequently, a plurality of image sensors 32 are formed on the wafer 31 as shown in FIG. On the wafer 31, a well-known film forming step, photolithography step, etching step, and impurity adding step are repeated to form a transfer electrode, an insulating film, wiring, and the like in a multilayer structure, and a plurality of light receiving regions are formed. Are arranged in an array. The image sensor 32
Is equivalent to that shown in FIG. Further, an alignment mark A serving as a positioning mark at the time of bonding with another wafer is marked in a region on the wafer 31 where the image sensor 32 is not formed.

Second Step Subsequently, as shown in FIG. 2, a wafer 31 is bonded to a lens array 33 on which a plurality of optical lenses 34 are formed. The optical lens 34 is formed corresponding to the arrangement of the light receiving areas of the image sensor 32 formed on the wafer 31,
The light incident surface and the light exit surface have different curvatures from each other. The lens array 33 is formed of, for example, a material transparent to visible light, such as a glass resin, and has a size of the wafer 31.
, Or larger than the wafer 31. Further, one end of the lens array 33 has a wafer 3
An orientation flat equivalent to 1 is formed, and an alignment mark B is marked on the surface thereof in correspondence with the alignment mark A of the wafer 31.

The light receiving area of the image sensor 32 and the optical lens 34 are aligned with reference to the alignment marks A and B, and are performed with high accuracy using an electron microscope or a projection exposure device. Thereby, the image sensor 32
And each of the optical lenses 34 corresponds to the light receiving area. The bonding of the lens array 33 and the wafer 31 is performed as follows.
Only the surface where the lens array 33 and the wafer 31 are in contact with each other is bonded, and for example, by using a technique such as screen printing, an epoxy-based transparent adhesive is uniformly applied to only the surfaces to be bonded to each other. .

Third Step Then, as shown in FIG. 3, the lens array 33 and the wafer 31 are bonded and divided according to the arrangement of the image sensors 32 formed on the wafer 31. FIG. 3 is an enlarged view of a part of the bonding of the lens array 33 and the wafer 31. Using a dicing blade 50, dicing is performed collectively vertically and horizontally along a scribe line S located at the center of the gap between the chips. Thereby, a plurality of solid-state imaging devices as shown in FIG. 4 are formed.

FIG. 5 is a sectional view schematically showing a solid-state imaging device formed by the above-described manufacturing method. In this figure, the same components as those in FIGS. 1 to 4 are denoted by the same reference numerals. The image sensor 32 is formed by the first process, and a plurality of shift registers are formed by forming a transfer electrode, an insulating film, wiring, and the like in a multilayer structure on a semiconductor substrate. Each bit of the plurality of shift registers corresponds to each light receiving pixel, and generates information charges in response to a subject image incident through the optical lens 34. Then, the generated information charges are accumulated in each light receiving pixel, and are sequentially transferred in response to an input clock pulse. Note that this image sensor 32 is a well-known CSP (Chi
p Scale Package) structure is preferable, and a plurality of external electrodes 42 (for example, solder balls) connected to the wiring pattern on the circuit board are formed on the surface opposite to the light receiving area side, and Connected to the wiring pattern on the circuit board. The lens chip 41 is formed by dividing the lens array 33 into chip size units according to the arrangement of a plurality of image sensors 32 formed on the wafer 31. In the lens chip 41, an optical lens 34 having substantially the same size as the light receiving area of the image sensor 32 or having an outer periphery larger than the light receiving area is positioned at a position corresponding to the light receiving area 40 of the image sensor 32. I have. The optical lens 34 is formed of a compound lens having different curvatures on the light incident surface and the light exit surface, and the respective curvatures r1 and r2, the distance h between the respective curved surfaces, and the distance d with the light receiving region 40 are appropriate. And the incident subject image is formed on the light receiving area 40.

As described above, the wafer 31 and the lens array 3
After bonding 3, the number of steps can be reduced by forming a solid-state imaging device by dividing into chip size units. In other words, it is possible to reduce the process of detecting the variation in the relative positional accuracy between the optical lens 34 and the light receiving region 40 of the image sensor 32 and the process of correcting the positional deviation between the optical lens 34 and the light receiving region 40 of the solid-state imaging device. it can. In addition, the step of aligning the optical lens 34 and the image sensor 32 can be performed only when the step of bonding the wafer 31 and the lens array 33 is performed.

FIG. 6 is a diagram for explaining a second embodiment of the present invention. In the same steps as in the first embodiment of the present invention, detailed description is omitted for simplification of the description.

First Step As shown in FIG. 1, a plurality of light receiving regions are formed on one main surface of a wafer 31, and a plurality of image sensors 32 are arranged in an array.

Second Step Subsequently, as shown in FIG. 6, the lens array 33 on which the plurality of optical lenses 34 are formed is bonded to the first main surface of the spacer array 51. The lens array 31 is the same as that shown in FIG.
Has the same structure as that shown in FIG. Spacer array 51
Is formed of a material transparent to visible light, such as a glass resin having a thermal expansion coefficient equivalent to that of the lens array 33, and has a size equal to or larger than that of the wafer 31. Is done. Spacer array 51
7, a plurality of openings 52 are formed, as shown in FIG.
Each opening 52 is formed corresponding to the arrangement of the optical lenses 34 formed in the lens array 33. This opening 52
Has an outer diameter corresponding to the outer diameter of the optical lens 34, and is formed at least as large as the outer diameter of the optical lens 34. Further, one end of the spacer array 51 has a wafer 3
1, an alignment flat is formed, and an alignment mark C corresponding to the alignment marks A and B is marked in a region where a plurality of openings 52 are not formed. By bonding the alignment mark C so as to match the alignment mark B, the opening 54 and the optical lens 34 correspond to each other. The bonding of the lens array 33 and the spacer array 51
For example, an epoxy-based transparent adhesive is uniformly applied only on the surface where the spacer array 51 contacts.

Third Step Subsequently, the second main surface of the spacer array 51 and the wafer 3
The surface on which one of the plurality of image sensors 32 is formed is attached. The bonding of the spacer array 51 and the wafer 31 is performed with reference to the alignment marks A and C, whereby each opening 52 and each image sensor 32 are attached.
Correspond to the light receiving areas. Also in these laminations, for example, an epoxy-based transparent adhesive is uniformly applied only to surfaces that are in contact with each other.

Fourth Step Then, the substrate formed so as to sandwich the spacer array 51 is divided according to the arrangement of the image sensors 32 on the wafer 31. This division is performed by using a dicing blade 50 to collectively dice vertically and horizontally, whereby a plurality of solid-state imaging devices as shown in FIG. 8 are formed.

FIG. 8 is a sectional view schematically showing a solid-state imaging device formed by the above-described manufacturing method. Note that the same members as those in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted. The spacer 61 is formed by being divided into each chip size unit in a state where the spacer array 51 is sandwiched between the wafer 31 and the lens array 52. The spacer 61 has a curvature r1 of the optical lens 34,
The thickness d and the material are appropriately set according to r2, the distance h between the curved surfaces, and the material of the optical lens 34.

As described above, by providing the spacer 61 between the lens chip 41 and the image sensor 31, it is possible to flexibly cope with a problem in manufacturing the optical lens 34.

[0027]

According to the present invention, the number of steps for manufacturing a camera unit can be reduced by dividing the wafer into a unit of a chip after bonding the lens and the lens array, which is effective in reducing the manufacturing cost of the camera unit. It is.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a first step of a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a second step of the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a third step of the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a third step of the first embodiment of the present invention.

FIG. 5 is a sectional view schematically showing a solid-state imaging device according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a second embodiment of the present invention.

FIG. 7 is a diagram illustrating a second embodiment of the present invention.

FIG. 8 is a cross-sectional view schematically illustrating a solid-state imaging device according to a second embodiment of the present invention.

FIG. 9 is a plan view showing a configuration of a conventional solid-state imaging device.

FIG. 10 is a cross-sectional view schematically showing a conventional camera unit.

[Explanation of symbols]

 1: imaging unit 2: storage unit 3: horizontal transfer unit 4: output unit 11: package 12: lead 13: circuit board 14: through hole 15: positioning hole 16: lens unit 17: mount unit 18: lens barrel unit 19: Positioning pin 20: Optical lens 31: Wafer 32: Image sensor 33: Lens array 34: Optical lens 50: Dicing blade 51: Spacer array 61: Spacer

Claims (2)

[Claims] 1. A method of manufacturing a solid-state imaging device for receiving an image of a subject in a light-receiving region in which a plurality of light-receiving pixels are arranged and accumulating information charges, wherein the plurality of light-receiving regions are formed on one main surface of a substrate. A lens array in which a plurality of optical lenses for forming a subject image in the light receiving area are formed in correspondence with the arrangement of the plurality of light receiving areas formed on the substrate; A solid-state image pickup device, comprising: a second step of adhering the lens array on the substrate; and a third step of dividing the substrate to which the lens array is adhered according to the arrangement of the plurality of light receiving regions. Production method. 2. A method of manufacturing a solid-state imaging device for receiving an image of a subject in a light-receiving region in which a plurality of light-receiving pixels are arranged and accumulating information charges, wherein the plurality of light-receiving regions are formed on one main surface of a substrate. A lens array in which a plurality of optical lenses for forming a subject image on the light receiving area are formed in correspondence with the arrangement of the plurality of light receiving areas formed on the substrate; A second step of adhering to a first main surface of a spacer array having a plurality of openings formed corresponding to: a second main surface of the spacer array and a first main surface of the substrate; A third step of bonding the openings and the light receiving areas so as to correspond to each other; and a fourth step of dividing the substrate to which the spacer array is bonded according to the arrangement of the plurality of light receiving areas. Solid characterized by the following Manufacturing method of the image elements.