JPS5846184B2 - Filter adhesion method and adhesion device for solid-state image sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an adhesive device for bonding an imaging section of a solid-state image sensor and a mosaic color filter, and more specifically, a mosaic color filter separate from the CcD solid-state image sensor and BBD solid-state image sensor. , relates to a device for positioning and bonding in a state corresponding to each picture element of an image sensor.

Solid-state image sensors are expected to greatly contribute to the miniaturization and weight reduction of video cameras, but in order to configure a color camera with a single solid-state image sensor, three-color filters (for example, red, green, (cyan) etc. must be configured in front of the image sensor.

Figure 1 shows image sensor 1 and mosaic color filter 2.
The outline is shown below.

First, in the image sensor 1, a picture element section 4, a photoconductive film 5, a transparent electrode 6, and a driving section 7 are formed on a silicon substrate 3.

Wire bonding pad 8 for connecting external leads
is formed in the drive section 7.

Next, the mosaic color filter 2 is made of an optical glass substrate 9.
A filter membrane 10 is formed thereon.

The filter film 10 has three color filters formed in a mosaic shape.

Currently, organic filters are often used as filters, and as shown in Figure 1, apart from the image sensor,
It is generally formed on optical glass 9 and bonded onto the image sensor as filter glass.

In recent years, with the demand for smaller and lighter video cameras, the area of image sensors has become smaller, and in order to maintain resolution, the pixel spacing must become closer, which increases the relative positional accuracy of the image sensor and filter. It became necessary to improve.

For example, as an adhesive specification for an image sensor and a filter,
(a) The adhesive layer thickness is 10 μm or less, and (b) the alignment accuracy is within 2 μm.

In order to satisfy this specification, it is necessary to simultaneously suppress and align the bonded surface, and, upon completion of alignment, to cure the adhesive while being pressed.

Therefore, efforts are being made to improve the fine adjustment accuracy of the equipment used.

Additionally, an ultraviolet curing adhesive is used as the adhesive.

UV-curable adhesives have almost uniform visible light transmittance.
It has high transmittance.

It is very easy to handle because it does not start curing until it is irradiated with ultraviolet light.

Furthermore, since no solvent is used, there is no risk of air bubbles forming inside the adhesive layer.

An example of a conventional image sensor and filter bonding device will be described below.

The specific plane and cross-sectional configuration of the bonding device are shown in Figure 2a,
Shown in b.

An ultraviolet curing adhesive 11 is applied to the adhesive surface of the image sensor 1.
A certain amount of the mosaic color filter 2 is placed on the image sensor 1 and temporarily pressed.

The protruding adhesive 11 is removed and it is confirmed that there is no adhesive 11 on the bonding pad 8.

The image sensor 1 with the mosaic color filter 2 temporarily pressed through the adhesive 11 is attracted to the vacuum chuck 13 mounted on the air cylinder 12.

The air cylinder 12 is raised and the upper surface of the mosaic color filter 2 is pressed against the holding plate 14 (optical glass) to press the adhesive 11.

In this state, while observing the relative positions of the image sensor 1 and the mosaic color filter 2 using the microscope 15, alignment is performed using the X-Y stage and rotational position adjustment mechanism attached to the lower part of the air cylinder 12.

After the alignment is completed, ultraviolet rays 16 are irradiated to harden the ultraviolet curable adhesive 11.

After that, the air cylinder 12 is lowered and taken out.

The conventional example described above causes the following problems.

First, when temporary pressing is performed, the dropped adhesive spills out and covers the bonding pad portion 8 .

Therefore, although the protruding adhesive is wiped off, it may adhere to the upper surface of the filter 2 or remain on the bonding pad portion 8, which is very time-consuming and lacks reliability.

Further, due to the pressure applied during alignment, there is a possibility that new adhesive will ooze out, and there is a risk that it will cover the bonding pad portion.

Removing the adhesive once cured is very difficult and leads to deterioration of the adhesive interface.

It is possible to reduce the amount of adhesive dripped to prevent it from spilling out, but this may cause bubbles to form on the adhesive surface.

In other words, unless the adhesive is dripped to the extent that it overflows and the air is completely released, problems such as insufficient adhesive and the formation of air bubbles will occur.

Removal of the adhesive that has protruded onto the bonding pad has become a major problem.

In addition, the filter holding plate that contacts and holds the mosaic color filter is made of glass, but there are problems such as insufficient holding power and scratches and chips on the top surface of the filter, and the selection of the material is also an issue.

The present invention has been made to solve the conventional problems as described above, and the present invention will be described below based on embodiments with reference to drawings.

An object of the present invention is to facilitate the removal of adhesive that protrudes from temporary pressing and to simplify the process.

That is, the present invention selectively cures the ultraviolet curable adhesive and separates it into a portion that requires curing and a portion that does not require curing.

The uncured portion (bonding pad portion) can be removed by cleaning with an organic solvent.

If selective curing is performed, alignment can be performed as is and exposure (curing) can be performed without removing the overflowing adhesive.

In other words, it is possible to eliminate the inefficient and uncertain process of removing adhesives.

The specific configuration of the present invention will be described below in FIG.

3 and 4 to selectively cure the adhesive.
Use a light shield (mask) as shown in the figure.

8 portions of the bonding pad are covered with a pad portion mask 17.
Further, the four picture elements are shielded from light by a picture element mask 18.

The mask is provided by depositing chromium or the like on the optical glass plate 14.

Ultraviolet rays 16 are irradiated to a constant width only to the pad part mask 17 and the picture element part mask 18, that is, only to the edge part of the mosaic color filter 2, to harden the adhesive.

As a result, as shown in the front view of FIG. 3, the adhesive is separated into a hardened portion 11' and an uncured adhesive portion 11''.

The adhesion between the image sensor 1 and the mosaic color filter 2 is performed primarily in an adhesive curing section 11'.

Since the entire circumference of the mosaic color filter 2 is bonded, the adhesive force is sufficient.

The uncured adhesive portion 11'' under the pad mask 1T is removed by cleaning with an organic solvent.

At this time, the cured adhesive portion 11'l prevents any adverse effects caused by washing into the adhesive layer.

In addition, the uncured adhesive portion 11'' under the picture element mask 18 is
After removing the adhesive from the pad portion 8, it is cured by re-irradiation with ultraviolet rays or heating.

The reason why the picture element part 4 is shielded from light is that the picture element part 4 may deteriorate due to the intensity of the ultraviolet rays 16.

In other words, during the first irradiation, it is desirable to cure the resin in as short a time as possible, so the intensity of the ultraviolet rays increases.

During the second irradiation (hardening of the uncured adhesive part 11'' of the picture element part 4), the irradiation time was longer than the first irradiation.
The intensity of ultraviolet rays can be lowered, and irradiation can be performed while taking into account the effect on the four picture elements.

Next, in order to prevent the ultraviolet rays 16 from going around at the edges of the mask part, a fourth
A light shielding plate 19 as shown in the figure was used.

The light shielding plate 19 has approximately the same dimensions as the pad mask 17 and prevents the ultraviolet rays 16 from entering the pad portion 8 .

The light shielding plate 19 has a thickness greater than that of the filter holding plate 20, and is placed as close to the bonding pad 8 as possible.

This light shielding plate 19 enables stable and accurate selective exposure.

Next, in order to improve alignment accuracy and prevent scratches and chipping of the mosaic color filter 2, a filter holding plate 20 is installed.
Materials were selected.

The filter holding plate 20 is attached to the center of the picture element mask 18 surface, as shown in FIG.

A strong holding force is required to hold and align the mosaic color filter 2.

Furthermore, since it comes into contact with the mosaic color filter 2, there is a risk of scratches and chips on the surface.

Therefore, in the present invention, the mosaic color filter (optical glass) 2 is made of a material that has high frictional resistance, is soft to the optical glass, and has some elasticity (acrylic, PVC,
Bake) was used.

The specific structure of the filter bonding device according to the present invention is shown in FIG.
, b.

First, the image sensor 1 with the mosaic color filter 2 temporarily pressed through an adhesive is adsorbed onto the vacuum chuck 13 mounted on the air cylinder 12 .

At this time, mosaic color filter 2 and filter holding plate 1
Roughly adjust the position of 9.

The adjustment means includes a microscope 15 provided at the top and a position adjustment mechanism (X-Y-R
direction).

Next, the air cylinder 12 is raised, and the upper surface of the mosaic color filter 2 is pressed against the filter holding plate 20, thereby pressing the adhesive 11.

In this state, the relative positions of the image sensor 1 and the mosaic color filter 2 are adjusted using the adjustment means described above.

After adjusting the position, the specified pressing pressure (5 kg/cr! ~ 8 k
g/aA) and irradiate with ultraviolet light 16.

Lower the air cylinder 12 and take it out.

After taking it out, the uncured adhesive 11'' on the bonding pad part 8 is washed and removed.

Next, the uncured adhesive 11'' of the picture element portion 4 is cured by re-irradiation with ultraviolet rays or by heating.

By using the present invention having the above configuration, it is possible to easily bond an image sensor and a filter with high precision and high quality.

In particular, it becomes easier to dispose of the adhesive that has protruded out, making it possible to achieve stable adhesion with a low defect rate.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a solid-state image pickup plate, an image sensor, and a mosaic color filter, Fig. 2 a and b are a conventional filter bonding device, Fig. 3 is a state diagram of a mask according to the present invention, and Fig. 4 is a diagram of the present invention. Figures 5a and 5b are a plan view and a side view of a filter bonding device according to the present invention. 1... Image sensor, 2... Filter, 4... Picture element section, 8... Bonding pad section, 11°11', 11". ...UV curing adhesive, 12...Air cylinder, 13.
...Vacuum chuck, 14...Glass plate,
15...Microscope, 16...Ultraviolet light, 1
γ... Pad part mask, 18... Picture element part mask, 19... Light shielding plate, 20...
・Filter holding plate.

Claims (1)

[Scope of Claims] 1. After installing a filter on a solid-state image sensor via an ultraviolet curable adhesive and aligning the solid-state image sensor and the filter, the pixel portion of the solid-state image sensor and The UV-curable adhesive corresponding to areas other than the bonding pad part is irradiated with ultraviolet rays, and then the UV-curable adhesive corresponding to the bonding pad area is removed, and then the UV-curable adhesive corresponding to the picture element area is cured by ultraviolet rays. A method for bonding a filter for a solid-state image sensor, which comprises irradiating a mold adhesive with ultraviolet light. 2. A first holding means for holding a solid-state image sensor, a second holding means for holding a filter installed on the solid-state image sensor via an ultraviolet curable adhesive, and the first and second holding means. 1. A filter bonding device for a solid-state image sensing device, comprising a moving means for relatively moving the means, and a shielding means for shielding a picture element part and a bonding pad part of the solid-state image sensing element from ultraviolet rays.