Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Reexamination Certificate
2000-09-25
2001-04-24
Le, Que T. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
C250S208100, C438S029000
Reexamination Certificate
active
06222180
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to electro optical devices with a reduced filter thinning on the edge or outer pixels and a method for reducing the thinning of filter layers on the pixel photosites dosest to the edge of an electro optical device such as a photosensitive chip, as would be used, for example, in a full-color digital copier or scanner.
BACKGROUND OF THE INVENTION
Image sensors for scanning document images, such as charge coupled devices (CCDs), typically have a row or linear array of photosites together with suitable supporting circuitry integrated onto a semiconductor chip. Usually, a sensor is used to scan line by line across the width of a document with the document being moved or stepped lengthwise in synchronism therewith. A typical architecture for such a sensor array is given, for example, in U.S. Pat. No. 5,153,421.
In a full-pagewidth image scanner, there is provided a linear array of photosensors which extends the full width of an original document, such as eleven inches. When the original document moves past the linear array, each of the photosensors converts reflected light from the original image into electrical signals. The motion of the original image perpendicular to the linear array causes a sequence of signals to be output from each photosensor, which can be converted into digital data.
A currently preferred design for creating such a long linear array of photosensors is to provide a set of relatively small semiconductor chips, each semiconductor chip defining thereon a linear array of photosensors along with ancillary circuit devices. These chips are assembled end-to-end to form a single linear array of photosensors as disclosed in U.S. Pat. No. 5,473,513. However, there are also single chip applications in which a single chip having a linear array may be used for sensing images and converting those images into electrical signals to be output from each photosensor. These electrical signals can be converted into digital data.
With the gradual introduction of color-capable products into the office equipment market, it has become desirable to provide scanning systems which are capable of converting light from full-color images into separate trains of image signals, each train representing one primary color. In order to obtain the separate signals relating to color separations in a full-color image, one technique is to provide on a semiconductor chip multiple parallel linear arrays of photosensors, each of the parallel arrays being sensitive to one primary color. Typically, this arrangement can be achieved by providing multiple linear arrays of photosensors which are physically identical except for a translucent primary-color overlay over the photosensitive areas, or “photosites,” for that linear array. In other words, the linear array which is supposed to be sensitive to red light only will have a translucent red layer placed on the photosites thereof, and such would be the case for a blue-sensitive array and a green-sensitive array. As the chip is exposed to an original full-color image, only those portions of the image, which correspond to particular primary colors, will reach those photosensors assigned to the primary color. These chips can also be assembled end to end to form a full width array comprising a multiple parallel linear arrays of photosites.
The most common substances for providing these translucent filter layers over the photosites is polyimide or acrylic. For example, polyimide is typically applied in liquid form to a batch of photosensor chips while the chips are still in undiced, wafer form. After the polyimide liquid is applied to the wafer, the wafer is centrifuged to provide an even layer of a particular polyimide. In order to obtain the polyimide having the desired primary-color-filtering properties, it is well known to dope the polyimide with either a pigment or dye of the desired color, and these dopants are readily commercially available. When it is desired to place different kinds of color filters on a single chip, a typical technique is to first apply an even layer of polyimide over the entire main surface of the chip (while the chip is still part of the wafer) and then remove the unnecessary parts of the filter by photo-etching or another well known technique. Typically, the entire filter layer placed over the chip is removed except for those areas over the desired set of photosites. Acrylic is applied to the wafer in a similar manner.
SUMMARY OF THE INVENTION
According to a first embodiment of the present invention, a semiconductor device includes a main surface including a plurality of photosites and bonding pads defined in the main surface, wherein the photosites include inner photosites and outer photosites. A dear layer is deposited over the main surface exclusive of the bonding pads and outer photosites. A first primary color filter layer is deposited over at least first inner photosite and first outer photosite, the first primary color filter transmitting a first primary color. A second primary color filter layer is deposited over at least a second inner photosite and a second outer photosite, wherein the second primary color filter layer transmits a second primary color. A third primary color filter layer is deposited over at least a third inner photosite and a third outer photosite, wherein the third primary color layer transmits a third primary color. The clear layer and filter layers are preferably polyimide or acrylic.
According to a second embodiment, a semiconductor chip includes a main surface including a plurality of photosites and bonding pads defined in the main surface, wherein the photosites include inner photosites and outer photosites. A first clear layer is deposited over the main surface exclusive of the bonding pads, and a second clear layer is deposited over the main surface exclusive of the bonding pads and outer photosites. A first primary color filter layer is deposited over at least first inner photosite and first outer photosite. The first primary color filter transmits a primary color. A second primary color filter layer is deposited over at least a second inner photosite and a second outer photosite, wherein the second primary color filter layer transmits a second primary color. A third primary color filter layer is deposited over at least a third inner photosite and a third outer photosite, wherein the third primary color layer transmits a third primary color. The clear layer, the second clear layer and the filter layers are preferably polyimide or acrylic
The semiconductor devices of the first embodiment may be placed in a digital copier, which includes a raster input scanner scanning documents to generate digital image signals, the raster input scanner including a plurality of generally rectangular chips, which are assembled end to end on a substrate forming a full width array of multiple parallel linear arrays of photosites. Each chip includes a main surface including bonding pads and the photosites defined in the main surface, wherein the photosites include inner photosites and outer photosites, a clear layer deposited over the main surface exclusive of the bonding pads and outer photosites, and a first primary color filter layer deposited over at least first inner photosite and first outer photosite, the first primary color filter transmitting a primary color.
The semiconductor devices of the second embodiment may be placed in a digital copier including a raster input scanner scanning documents to generate digital image signals, the raster input scanner including a plurality of generally rectangular chips, which are assembled end to end on a substrate forming a full width array of multiple parallel linear arrays of photosites. Each chip includes a main surface including bonding pads and the photosites defined in the main surface, wherein the photosites include inner photosites and outer photosites, a clear layer deposited over the main surface exclusive of the bonding pads, a second clear layer deposited over the main surface exclusive of the bonding pads and
Grimsley Thomas
Jedlicka Josef E.
Ormond Brian T.
Daebeler Paul F.
Le Que T.
Luu Thanh X.
Ryan Andrew D.
Xerox Corporation
LandOfFree
Electro optical devices with reduced filter thinning on the... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electro optical devices with reduced filter thinning on the..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electro optical devices with reduced filter thinning on the... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2466248