Method for integrating image sensors with optical components

Details Method for integrating image sensors with optical components Method for integrating image sensors with optical components

2001-10-16

2004-01-20

Aftergut, Jeff H. (Department: 1733)

Adhesive bonding and miscellaneous chemical manufacture

Methods

Surface bonding and/or assembly therefor

C156S300000, C156S308200, C438S070000, C438S458000

Reexamination Certificate

active

06679964

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to a method for integrating an image sensor with optical components, and more particularly to a wafer level integrating method for bonding un-sliced wafers having image sensors, wafer-sized substrates and optical components thereon.
BACKGROUND OF THE INVENTION
With the advent of the multimedia age and rapid development of the 3C (computer, communication and consumer) industries, there is an increasing demand for various electro-optical devices utilizing image sensors, such as digital cameras, digital video devices, and scanners. An image sensor is used to convert an optical image focused on the sensor into electronic signals. The image sensor typically includes an array of light detecting elements for producing a signal corresponding to the intensity of light impinging on the element so as to be used to display a corresponding image on a monitor or to provide information about the optical image.
The image sensors are generally classified into two categories, i.e. CCD (charge coupled device) image sensors and CMOS (complementary metal oxide semiconductor) image sensors. CCD image sensors have been developed over 30 years and much earlier than CMOS image sensors. Currently, most electro-optical devices use CCD image sensors, primarily due to their mature fabrication techniques and applications. However, CMOS image sensors have undergone rapid development in the recent years because they can integrate the peripheral controlling circuits so as to reduce the complexity and size of the electro-optical devices as well as the electric power consumption.
FIG. 1
is an exploded sectional view of a conventional image-sensing device
100
. The image-sensing device
100
comprises a image sensor
110
, a color filter
120
and a transparent plate
130
. The image sensor
110
includes a two-dimensional array of light sensor cells, such as CCD or CMOS. The color filter
120
, such as a trichroic filter, including R, G and B color filters (
122
,
124
and
126
) is provided at the light-incident side of the image sensor
110
. The transparent plate
130
, for example, formed of glass is provided at the light-incident side of the color filter
120
.
FIG. 2
is a schematic drawing of a prior art packaged image sensor. The bonding and packaging procedures of an image-sensing device are as follows. First, an image sensor
200
is bonded to a carrier
210
, wire bonds
220
are electrically connected between the image sensor
200
and the carrier
210
and outside electrical leads
230
are connected to the terminals of the carrier
210
. The image sensor
200
are precision optically aligned to the color filter
240
by using targets lithographically reproduced on both the image sensor
200
and the color filter
240
. An optical coupling composition
250
is uniformly spread on the top of the image sensor
200
. The color filter
240
is positioned over the image sensor
200
and disposed onto it so that the optical coupling composition
250
can be uniformly spread beneath the color filter
240
. The color filter
240
and the image sensor
200
are optically aligned with each other by way of alignment targets, and then the image sensor
200
/color filter
240
assembly is checked for debris or bubble entrapment. A conventional UV curable adhesive at each end of the color filter
240
is used for stacking the color filter
240
in place. Lastly, a transparent plate
260
is bonded onto the carrier
210
to protect the assembly from contaminants of foreign particles and moisture.
The conventional bonding and packaging procedures of the image sensor are based on a single die; that is, each die must be diced from a semiconductor wafer for further bonding and packaging processes. Since all bonding and packaging processes are based on chip scale, the precision requirement is very important and the procedure is very complicated. Moreover, the above-mentioned processes of bonding and packaging should be implemented in a very clean environment since foreign matter and moisture present within the space
270
will degrade the sensing quality. Therefore, manufacturing an image sensor through the conventional processes is subject to several disadvantages, for example, complex and heavy processes, low product yield, long manufacture cycling time and significant cost.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a wafer level integrating method for bonding un-sliced wafers having image sensors and a wafer-sized substrate including optical components thereon, comprising the steps of: bonding a wafer-sized substrate including the optical components thereon to a zeroth order light reflective substrate through an adhesive to form a composite substrate; and bonding the composite substrate to an un-sliced wafer including image sensors thereon to form a resultant wafer for further packaging processes.
Additional advantages, objects and features of the present invention will become more apparent from the description which follows.


REFERENCES:
patent: 4523102 (1985-06-01), Kazufumi et al.
patent: 6429036 (2002-08-01), Nixon et al.
patent: 6577342 (2003-06-01), Wester
patent: 2002/0135825 (2002-09-01), Lee et al.

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