JPH0250628B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a solid-state image sensor. In particular, the present invention provides a method suitable for positioning and bonding a color filter having a separate mosaic pattern to a CCD solid-state image sensor or a BBD solid-state image sensor in a state corresponding to each pixel of the image sensor. It is something to do.

Solid-state image sensors are expected to greatly contribute to making video cameras smaller and lighter.
In order to configure a color camera with a single solid-state image sensor, a three-color filter (for example, red, green, and cyan) is required.
etc. must be configured in front of the image sensor. At present, organic filters are often used as filters, and are generally formed on optical glass separately from the image sensor and bonded as filter glass onto the image sensor.

Strong adhesive strength could be obtained by using a thermosetting resin, which is widely used for bonding optical lenses.

However, with the demand for smaller and lighter video cameras, the area of image sensors has also become smaller.
In order to maintain resolution, the pixels must be spaced close to each other, making it necessary to improve the relative positional accuracy between the image sensor and the filter, which cannot be achieved with conventional adhesive methods using thermosetting resin. It turned out to be enough.

In other words, it is necessary to achieve an adhesive surface area of approximately 200 ^mm2 , an adhesive thickness of 10 μm or less, and an alignment accuracy (relative positioning accuracy between the image sensor pattern and the filter mosaic pattern) of approximately 2 μm. Pressing and alignment must be performed at the same time, and once alignment is completed, the adhesive must be cured while being pressed.

However, with conventional thermosetting resins, when alignment is performed with a resin thickness of about 10 μm, hardening begins gradually, resulting in poor color S/N ratio and frizz due to uneven thickness and poor alignment during adhesion. In more severe cases, color misregistration may occur.

Therefore, it is ideal to use an ultraviolet curable resin that does not cure at all during alignment but cures in a short time when exposed to ultraviolet rays.

However, because UV-curable resins cure extremely quickly, it is extremely difficult to stop the curing process at an appropriate degree of curing. Moreover, once cured, it is easily re-dissolved in commonly used organic solvents. This makes it very inconvenient as an adhesive for this purpose.

For example, as shown in FIG. 1, a solid-state image sensor is provided with a pixel section 2 consisting of a photodiode for sensing an optical image, a charge transfer element for transferring an optical signal, etc. in the center of a p-type base substrate 1, and A drive circuit section 3 such as a cyst register or a CCD for driving the picture element section 2 is provided around the picture element section 2, and an insulating film 4 is provided above the drive circuit section 3. On the upper part of this insulating film 4, a conductor wiring part 6 and a photoconductive film connecting electrode 7 are connected to the terminals of the drive circuit part 3 through the opening of the insulating film 4 and extend to the external wiring pad part 5. It is provided. Furthermore, a photoconductive film (for example, ZnSe-Zn _1-x
Cd _x Te, amorphous silicon, etc.) 8 and a transparent electrode 9 are laminated, and a color filter 11 is further adhered with an adhesive 10 interposed therebetween. Reference numeral 17 indicates individual image sensor portions of the solid-state image sensor.

In a color solid-state image sensor, when the color filter 11 is bonded using an ultraviolet curing resin, the adhesive 10 inevitably adheres to the color filter 1.
1 and covers the pad portion 5.

Therefore, if the adhesive 10' is cured by irradiating ultraviolet rays from the direction of arrow A, the adhesive 10' that protrudes onto the pad portion 5 will be cured, making it impossible to perform wire bonding in a later step.

One method is to remove the protruding adhesive 10'.
However, if an organic solvent or the like is used, the solvent will penetrate into the adhesive 10 of the adhesive layer, and the adhesive 1 on the top surface of the pad portion 5 will be removed.
It is not possible to effectively remove only 0'.

Another method is to cover the top surface of the pad portion 5 with a light shearing film or the like during ultraviolet curing, and then wash and remove only the sheared portion in an uncured state with an organic solvent. However, this method is also very troublesome because the alignment accuracy of the shear film needs to be ± several hundred microns and the light wraps around.

In view of the above-described drawbacks of the adhesive method using ultraviolet curing resin, the object of the present invention is to reduce the amount of adhesive 1 sandwiched between the color filter 11 and the picture element part 2.
The objective is to provide a method in which only 0 is cured and the portion that leaks out from the color filter 11 is not cured by ultraviolet rays.

Originally, ultraviolet curing adhesives (for example, thiol-ene adhesives) contain radical initiators such as benzophenone, thioxanthone, and benzanthrone as photocuring initiators, and the curing speed is influenced by the concentration of this radical initiator. 〔Product name,
Norland Company No A-61, WR Grace Company RCP-
611u] (acrylate type, etc.), when they come in contact with oxygen, the radicals rapidly disappear and hardening does not proceed.

For example, the curing mechanism is shown as follows.

Curing initiation Initiator hν --- →R・ Chain reaction R・+CH ₂ =CHR′→RCH ₂ −CHR′・ RCH ₂ CHR′+nCH ₂ =CHR′ →R(CH ₂ CHR′) _o CH ₂ CHR′・Reaction end point 2R (CH ₂ CHR') _o CH ₂ CHR'・Poymer R (CH ₂ CHR') _o CH ₂ CHR'・+R・ →R (CH ₂ CHR') _o CH ₂ CHR'R In the above initiation reaction For example, if the initiator is benzophenone and the atmosphere contains oxygen, it will disappear as follows.

In other words, it can be seen that the radicals once formed by light are rapidly annihilated and curing does not proceed.

Therefore, by using an ultraviolet curing adhesive whose curing starts with a radical initiator and performing the adhesion in an atmosphere containing oxygen gas, the adhesive 10' that has come into contact with oxygen, that is, the adhesive 10' that protrudes from the color filter 11, can be removed. Color filter 11 suppresses hardening
Since the portion of the adhesive 10 sandwiched between the picture element portions 2 does not come into contact with the atmosphere, curing proceeds quickly. Therefore, after the adhesive 10 in the portion sandwiched between the color filter 11 and the picture element portion 2 is cured, the uncured adhesive 10' can be selectively removed by cleaning with an organic solvent or the like.

Here, in detail, even in the adhesive 10' that protrudes, oxygen does not diffuse sufficiently into the interior, so it is thought that curing progresses to some extent, but in reality, the color filter 11 and the pixel 2
The thickness of the adhesive 10 sandwiched between the two is about 10 μm, which is much thinner than the thickness of the adhesive 10' that protrudes, which is about several microns. 1
It was possible to find conditions for curing the adhesive 10 sandwiched between the color filter 11 and the picture element portion 2 without curing the inside of the color filter 11.

For example, No. in an atmosphere containing about 20% oxygen.
Using A-61, illuminance 58m with high pressure mercury lamp
By irradiating at WS/cm ² for about 30 seconds, when the thickness of the adhesive 10 sandwiched between the color filter 11 and the picture element is about 10 μm, the protruding adhesive 10' can be selectively removed by simply cleaning it with an organic solvent. I was able to remove it.

In this case, a thermosetting initiator is added to the UV-curable adhesive, for example, 1 to 3% of benzopinacol, a radical initiator, or its derivatives are added to No A-61 to give it UV-curing and thermosetting properties. By using an ultraviolet/thermosetting adhesive, even if there is an ultraviolet shielding area within the color filter, the uncured portion can be heated and cured in a later process, greatly improving reliability. Furthermore, even if a radical thermosetting initiator is added to an ultraviolet curing adhesive, the same effect as described above can be obtained in an oxygen-containing atmosphere, and the effect of suppressing the curing of the extruding adhesive is the same. Even under the same ultraviolet irradiation conditions as above, the protruding adhesive could be sufficiently removed with an organic solvent such as trichlene.

As described above, when a color filter is bonded to a solid-state image sensor using the method of the present invention,
Only the adhesive sandwiched between the color filter and solid-state image sensor can be cured;
Excess adhesive covering the external electrode connection pads of the solid-state imaging device can be easily removed by washing with an organic solvent. Therefore, the subsequent wire bonding process is
This makes it extremely easy to assemble the color solid-state image sensor, and can significantly reduce the assembly cost of the color solid-state image sensor.

[Brief explanation of the drawing]

Figure 1 is a top view of a colored solid-state image sensor to which a color filter used in the method of the present invention is adhered;
The figure is a sectional view of the color solid-state image pickup device taken along the line XX' in FIG. DESCRIPTION OF SYMBOLS 1... P-type base substrate, 2... Picture element part, 8... Photoconductive film, 9... Transparent electrode, 10... Adhesive sandwiched, 10'... Adhesive protruding, 11... Color filter.

Claims (1)

[Claims] 1. In the process of bonding the filter onto the solid-state image sensor, an ultraviolet/thermosetting resin containing a radical type thermosetting initiator and a radical type photocuring initiator is used as the adhesive, and while irradiating ultraviolet rays in an oxygen-containing atmosphere. A method for manufacturing a solid-state image sensor, which comprises performing primary curing and removing protruding resin, and then heating and curing the uncured resin to perform bonding.