CCD English full name: Charge Coupled Device. These two kinds of photosensitive devices are similar to the semiconductor integrated circuits we use everyday, integrating thousands to tens of thousands of phototransistors on a silicon wafer. These phototransistors are divided into three columns and are covered with red, green and blue color filters respectively. Implement color scanning. The phototransistor can generate current when it is exposed to light, and is amplified and output.
The performance of this kind of photosensitive device has been greatly improved in recent years, and the performance of its high-end products has approached the low-grade photomultiplier tube, but since thousands of photoelectric triodes are in close proximity (micron level), and the insulation between the triodes depends on the semiconductor PN Insulation from the junction. The isolation resistance is small. Therefore, there is a significant current leakage between the phototransistors, which causes the signals of the photo-sensing units to interfere with each other and reduce the actual clarity of the scanner.
In order to improve this situation, it is now possible to use silicon oxide isolation technology, that is, to replace the semiconductor monocrystalline silicon between the individual phototransistors with SiO2 (silicon dioxide) during device processing, since SiO2 is very good. The insulation material almost eliminates the electrical leakage between the phototransistors. Therefore, in the case of the same performance indicators of the two scanners, the actual resolution of the scanner using the silicon oxide isolation CCD will have a qualitative leap.
However, the production cost of this technology product is several times higher than the production cost of the semiconductor isolation technology product. Therefore, it can currently only be used in professional-grade scanners of more than 5,000 yuan. Almost all home and office scanners currently on the market use semiconductor-isolated CCDs, and performance cannot be compromised.
The performance of this kind of photosensitive device has been greatly improved in recent years, and the performance of its high-end products has approached the low-grade photomultiplier tube, but since thousands of photoelectric triodes are in close proximity (micron level), and the insulation between the triodes depends on the semiconductor PN Insulation from the junction. The isolation resistance is small. Therefore, there is a significant current leakage between the phototransistors, which causes the signals of the photo-sensing units to interfere with each other and reduce the actual clarity of the scanner.
In order to improve this situation, it is now possible to use silicon oxide isolation technology, that is, to replace the semiconductor monocrystalline silicon between the individual phototransistors with SiO2 (silicon dioxide) during device processing, since SiO2 is very good. The insulation material almost eliminates the electrical leakage between the phototransistors. Therefore, in the case of the same performance indicators of the two scanners, the actual resolution of the scanner using the silicon oxide isolation CCD will have a qualitative leap.
However, the production cost of this technology product is several times higher than the production cost of the semiconductor isolation technology product. Therefore, it can currently only be used in professional-grade scanners of more than 5,000 yuan. Almost all home and office scanners currently on the market use semiconductor-isolated CCDs, and performance cannot be compromised.
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