CN102610620B - Optical sensor and imaging device inside optical sensor - Google Patents

Abstract

The invention relates to an optical sensor and an imaging device inside thereof, belonging to the field of optical sensors. The imaging device is composed of a plurality of imaging structures located on the imaging array, the imaging structure includes a reference unit and at least one imaging unit, the reference unit and the imaging unit have the same structure, and the reference unit and the imaging unit are adjacently arranged and located in the imaging array In the same column or row, the fill factor of the imaging structure is greater than or equal to 50%. The imaging device inside the optical sensor of the present invention eliminates the influence of common mode noise on the reading result by slightly increasing the area of the imaging device; since the imaging unit and the reference unit in the same group of devices are relatively close, the impact of process deviation on them is roughly the same , and the reading results adopt their differential mode information, so the influence of process deviation on the reading results can be eliminated.

Description

An optical sensor and its internal imaging device

technical field

The present invention relates to a sensor and its internal imaging device, in particular to an optical sensor and its internal imaging device, belonging to the field of optical sensors.

Background technique

Optical sensor technology has been widely used in modern technology, national defense, industry and agriculture. It mainly uses a photosensitive element to convert the detected light wave signal into a corresponding electrical signal for identification and processing by the subsequent signal processing system.

Figure 1(a) shows a schematic diagram of the structure of a single imaging device inside the optical sensor. Each imaging device includes control gate (Control Gate) CG, floating gate (Floating Gate) FG, source S, drain D and P-type doped substrate B, and substrate B and floating gate FG, and An oxide layer is used for isolation between the floating gate FG and the control gate CG.

Figure 1(b) shows the schematic diagram of the first imaging operation for a single imaging device. When the imaging device receives light radiation, electron and hole pairs will be generated in its substrate, and the number of electron and hole pairs is directly proportional to the intensity of light radiation. At this time, if the source S, the drain D and the substrate B of the imaging device are connected to the reference potential Vref, and the control gate CG of the imaging device is connected to the level of VP relative to the reference potential, the substrate surface of the imaging device will be Electron accumulation will occur. Under the action of the vertical electric field, some electrons will undergo FN (Fowler-Nordheim) tunneling and reach the floating gate FG, and the number of electrons undergoing FN tunneling is proportional to the number of electrons on the substrate surface. It is also proportional to the intensity of light radiation. Therefore, according to the above principles, the light wave signal can be converted into an electrical signal and stored in the floating gate FG of the imaging device.

Figure 1(c) shows another schematic diagram of the imaging operation for a single imaging device. Similar to the first imaging operation, when the imaging device is irradiated by light waves, the number of charges generated on the substrate surface is proportional to the intensity of light wave radiation. At this time, the control gate CG of the imaging device is connected to the level of VPG relative to the reference potential, the drain D is connected to the level of VPD relative to the reference potential, and the source S and the substrate B are connected to the reference potential Vref. Electron accumulation will occur on the surface of the device substrate, and these charges will move from the source S to the drain D under the action of the lateral electric field, and become hot electrons near the drain D, and these hot electrons collide near the drain D Ionization generates new pairs of electrons and holes, and some electrons will pass through the oxide layer and enter the floating gate FG of the imaging device under the action of the vertical electric field. This imaging method is channel hot electron injection (CHE, Channel -Hot-Electronic) imaging. The electrons entering the floating gate FG are also proportional to the intensity of the light wave radiation.

FIG. 2 is a schematic diagram of an operation for reading internal information of an imaging device. Apply a reference potential Vref to the source S and substrate B of the imaging device, apply a level of VRD relative to the reference potential to its drain, and apply a level of VR relative to the reference potential to its control gate CG , then a current Ids will be generated between the drain D and the source S of the imaging device, and the magnitude of this current is proportional to the threshold voltage VT of the imaging device, and the threshold voltage VT of the imaging device is proportional to the floating gate FG of the imaging device Proportional to the number of electrons, so the reading current Ids obtained by this method can reflect the electrical information stored inside the imaging device.

Fig. 3 shows a simple schematic flow chart of imaging and reading the internal imaging device of the optical sensor. Before each imaging of the optical sensor, the imaging device will be reset and then imaged. When the imaging information needs to be processed, the stored information can be obtained by reading the drain current Ids of the imaging device, and then the signal can be amplified for subsequent signal processing.

In traditional imaging devices, there are roughly two reading methods. One is that the imaging unit array and the reference unit are arranged as two independent modules, and the reading results are read by the imaging unit with light and the reference unit without light imaging. Take the difference of the results; the other one does not use the reference cell array, by first reading the result of the imaging unit in the absence of light imaging, and then reading the result of the imaging unit in the light imaging, through the peripheral circuit Get the difference between the two results. In the first way, because the distance between the imaging unit array and the reference unit array is relatively large, the device performance caused by the process deviation is greatly affected; while the second way needs to increase the complexity of the peripheral circuit.

Contents of the invention

The present invention aims at the above-mentioned shortcomings of the traditional imaging device, and provides an optical sensor and an imaging device therein. 

The technical solution of the present invention to solve the above-mentioned technical problems is as follows: an imaging device inside an optical sensor is composed of a plurality of imaging structures located on an imaging array, and the imaging structure includes a reference unit and at least one imaging unit, and the reference unit and The imaging units have the same structure, the reference unit and the imaging unit are adjacently arranged and located in the same column or row in the imaging array, the reference unit does not participate in exposure programming, and the imaging unit participates in exposure programming, and the reference unit The purpose is to help provide accurate initial threshold voltage information. Since the physical distance on the chip is very close, the two units have the same initial threshold voltage after the entire chip is erased, and then only the imaging unit is exposed. In programming, the reference unit does not perform any operations, and the fill factor of the imaging structure is greater than or equal to 50%.

On the basis of the above technical solutions, the present invention can also be improved as follows.

Further, both the reference unit and the imaging unit include a silicon substrate, a source, a drain, a floating gate and a control gate, the source and the drain are respectively located at two ends of the silicon substrate, and the control gate Located above the floating gate, the floating gate is located above the silicon substrate, the silicon substrate located between the source and the drain is separated from the floating gate by an insulating layer, and the floating gate is separated by an insulating layer layer is isolated from the control gate.

Further, the imaging structure includes a reference unit, a first imaging unit and a second imaging unit, the reference unit is located between the first imaging unit and the second imaging unit, and the first imaging unit and the second imaging unit are opposite The reference units are distributed symmetrically, and the reference units, the first imaging unit and the second imaging unit are located in the same row or column in the imaging array.

Further, it also includes at least one third imaging unit and/or at least one fourth imaging unit, the third imaging unit and the first imaging unit are adjacently arranged and located in the same row or column in the imaging array, and the fourth The imaging unit and the second imaging unit are adjacently arranged in the same row or column in the imaging array.

Further, the imaging structure includes a reference unit, a first imaging unit, a second imaging unit and a third imaging unit, the reference unit is located between the first imaging unit and the second imaging unit, the first imaging unit and The second imaging unit is symmetrically distributed with respect to the reference unit, the reference unit, the first imaging unit and the second imaging unit are located in the same row in the imaging array, and the third imaging unit and the reference unit are adjacently arranged and located in the imaging array or the reference unit, the first imaging unit and the second imaging unit are located in the same column in the imaging array, and the third imaging unit and the reference unit are arranged adjacently and located in the same row in the imaging array.

Further, the imaging structure includes a reference unit, a first imaging unit, a second imaging unit, a third imaging unit and a fourth imaging unit, the reference unit is located between the first imaging unit and the second imaging unit, the The first imaging unit and the second imaging unit are symmetrically distributed with respect to the reference unit, and at the same time, the reference unit is located between the third imaging unit and the fourth imaging unit, and the third imaging unit and the fourth imaging unit are relative to the reference The units are distributed symmetrically, the reference unit, the first imaging unit and the second imaging unit are located in the same row in the imaging array, and the reference unit, the third imaging unit and the fourth imaging unit are located in the same column in the imaging array; or The reference unit, the first imaging unit and the second imaging unit are located in the same column of the imaging array, and the reference unit, the third imaging unit and the fourth imaging unit are located in the same row of the imaging array.

Further, it also includes at least one fifth imaging unit and/or at least one sixth imaging unit and/or at least one seventh imaging unit and/or at least one eighth imaging unit, the fifth imaging unit is similar to the first imaging unit adjacently arranged and located in the same row or column in the imaging array, the sixth imaging unit and the second imaging unit are adjacently arranged in the same row or column in the imaging array, the seventh imaging unit and the third imaging unit The adjacent arrangement is located in the same row or the same column in the imaging array, and the adjacent arrangement of the eighth imaging unit and the fourth imaging unit is located in the same row or the same column in the imaging array.

Further, the imaging structure includes a reference unit, a first imaging unit, a second imaging unit, a third imaging unit, a fourth imaging unit, a fifth imaging unit, a sixth imaging unit, a seventh imaging unit and an eighth imaging unit , the reference unit, the first imaging unit, the second imaging unit, the third imaging unit, the fourth imaging unit, the fifth imaging unit, the sixth imaging unit, the seventh imaging unit and the eighth imaging unit are located on the imaging array and A rectangular structure with three rows and three columns is formed, and the reference unit is located at the center of the second row and the second column of the rectangular structure.

The present invention also provides a technical solution for solving the above-mentioned technical problems as follows: an optical sensor with the above-mentioned imaging device.

The beneficial effect of the present invention is that: the imaging device inside the optical sensor of the present invention does not increase the complexity of the peripheral information reading circuit, and by slightly increasing the area of the imaging device, the final reading result of the light wave radiation information is read with light The differential mode signal between the information of the imaging device when it is irradiated and the imaging information of the imaging device when there is no light radiation, thereby eliminating the influence of common mode noise on the reading results; since the imaging unit and the reference unit in the same group of devices are relatively close, The impact of process deviation on them is roughly the same, and the reading results use their differential mode information, so the influence of process deviation on the reading results can be eliminated; the light wave radiation information obtained by using this imaging device structure and imaging and reading methods is closer to The true situation.

Description of drawings

Figure 1 is a structural diagram of a single imaging device in an optical sensor and a schematic diagram of two corresponding imaging principles;

Fig. 2 is a schematic diagram of reading information stored in the imaging device in the optical sensor;

Fig. 3 is a simple imaging device imaging and reading operation flow chart;

Fig. 4 is a simplified schematic diagram of device arrangement in the first preferred embodiment of the present invention;

Fig. 5 is a simplified schematic diagram of device arrangement in the second preferred embodiment of the present invention;

6 is a simplified schematic diagram of device arrangement in a third preferred embodiment of the present invention;

7 is a simplified schematic diagram of device arrangement in a fourth preferred embodiment of the present invention;

Fig. 8 is a simplified schematic diagram of device arrangement in the fifth preferred embodiment of the present invention;

Fig. 9 is a simplified schematic diagram of device arrangement in other embodiments of the present invention.

Detailed ways

The principles and features of the present invention are described below in conjunction with the accompanying drawings, and the examples given are only used to explain the present invention, and are not intended to limit the scope of the present invention.

Fig. 4(a) is one of the schematic diagrams of the device structure in which each group of imaging structures includes two units according to the first preferred embodiment of the present invention. In this embodiment, the two units included in each group are distributed on the same row, where C0 is the reference unit, and C1 is the imaging unit. The reference unit C0 and the imaging unit C1 have exactly the same structure and present a symmetrical distribution, so their positions can be exchanged with each other. Fig. 4(b) shows the second schematic diagram of the device structure in which each group of imaging structures includes two units in the first preferred embodiment of the present invention. In this embodiment, the two units included in each group are distributed on the same column, wherein C0 is the reference unit, and C1 is the imaging unit. The reference unit C0 and the imaging unit C1 have exactly the same structure and present a symmetrical distribution, so their positions can be exchanged with each other. It can be seen from the figure that the fill factors of the two device structures in this embodiment are about 50%. And all the devices inside the optical sensor are composed of several groups arranged in this way.

Fig. 5(a) is one of the simplified schematic diagrams of device arrangement in which each group of imaging structures includes three units according to the second preferred embodiment of the present invention. In this embodiment, the three units contained in each group are distributed on the same row, in which the white square in the middle is the reference unit C0, the squares with oblique lines on both sides are the first imaging unit C1 and the second imaging unit C2 respectively, and the reference unit C0, The first imaging unit C1 and the second imaging unit C2 adopt exactly the same design, and since the positions of the first imaging unit C1 and the second imaging unit C2 are distributed symmetrically with respect to the reference unit C0, their positions can be exchanged. FIG. 5( b ) is the second simplified schematic diagram of device arrangement in which each group of imaging structures includes three units according to the second preferred embodiment of the present invention. In this embodiment, which units are contained in each group are distributed on the same column, where the white square in the middle is the reference unit C0, the squares with upper and lower slashes are the first imaging unit C1 and the second imaging unit C2, and the reference unit C0, The first imaging unit C1 and the second imaging unit C2 adopt exactly the same design, and since the positions of the first imaging unit C1 and the second imaging unit C2 are distributed symmetrically with respect to the reference unit C0, their positions can be exchanged. It can be seen from the figure that the filling factor of the two device structures in this embodiment is about 66.7%, and the overall area of the device can be reduced compared with the first embodiment. And all the devices inside the optical sensor are composed of several groups arranged in this way.

Fig. 6(a) shows one of the simplified diagrams of device arrangement in which each group of imaging structures includes four units in the third preferred embodiment of the present invention. The four units included in each group in this embodiment are the reference unit C0, the first imaging unit C1, the second imaging unit C2 and the third imaging unit C3. The first imaging unit C1, the second imaging unit C2 and the reference unit C0 are distributed on the same row and located on both sides of the reference unit, while the third imaging unit C3 and the reference unit C0 are located on the same column and above the reference unit . Since the first imaging unit C1, the second imaging unit C2, and the third imaging unit C3 have exactly the same structure, their positions can be located in four adjacent positions in the same row or in the same column as the reference unit C0 Arbitrary three positions, resulting in a simplified diagram of the arrangement and distribution of the other three devices of the four units in this embodiment, as shown in Figure 6(b), Figure 6(c), and Figure 6(d), and the first imaging unit The positions of C1 , the second imaging unit C2 and the third imaging unit C3 in this embodiment can be interchanged. It can be seen from the figure that the filling factor of the two device structures in this embodiment is about 75%, and the overall area of the device can be reduced compared with the second embodiment. And all the devices inside the optical sensor are composed of several groups arranged in this way.

FIG. 7 is a simplified diagram of device arrangement in which each group of imaging structures includes five units according to the fourth preferred embodiment of the present invention. In this embodiment, the five units included in each group are the reference unit C0, the first imaging unit C1, the second imaging unit C2, the third imaging unit C3 and the fourth imaging unit C4. The reference unit C0 is located in the center of this group of devices, the first imaging unit C1 and the second imaging unit C2 are located in the same row as the imaging unit C0, and are distributed on both sides of the imaging unit C0, the third imaging unit C3 and the fourth The imaging unit C4 is located in the same column as the reference unit C0, and is distributed on both sides of the imaging unit C0. Since the device structures of the first imaging unit C1 , the second imaging unit C2 , the third imaging unit C3 and the fourth imaging unit C4 are completely the same, their positions in the figure can be interchanged. It can be seen from the figure that the filling factor of the two device structures in this embodiment is about 80%, and the overall area of the device can be reduced compared with the third embodiment. And all the devices inside the optical sensor are composed of several groups arranged in this way.

FIG. 8 is a simplified diagram of device arrangement of each group of imaging structures including nine units C0, C1, C2, C3, C4, C5, C6, C7 and C8 according to the fifth preferred embodiment of the present invention. Nine devices in this group of devices present an array of three rows and three columns, among which the unit located in the center, the second row and the second column is used as the reference unit C0, and the remaining eight units are used as the imaging unit. Since the device structures of the eight imaging units are exactly the same, their positions in the figure can be interchanged. It can be seen from the figure that the fill factor of the two device structures of this embodiment is about 88.9%, and the overall area of the device can be reduced compared with the fourth embodiment. And all the devices inside the optical sensor are composed of several groups arranged in this way.

FIG. 9 is a simplified schematic diagram of the arrangement of each group of imaging structures in the other four preferred embodiments. The white squares represent imaging units, and the other diagonal squares represent imaging units. Without loss of generality, the device arrangements in these embodiments have the features stated in claim 1 .

It can be understood that the unit graphics (quadrilateral or hexagonal) in Figures 1 to 9 are only used to represent the imaging unit or the reference unit, not the actual shape of the imaging unit and the reference unit. To represent the relative position of the imaging unit and the reference unit, what shape to use to represent the imaging unit or the reference unit has no practical significance, but for the overall beauty of the graphics, there are many possibilities for the arrangement of the imaging unit and the reference unit. No more examples here, but "the imaging device is composed of a plurality of imaging structures located on the imaging array, the imaging structure includes a reference unit and at least one imaging unit, the reference unit and the imaging unit The structure is the same, the reference unit is used to provide an accurate value of the initial threshold voltage of the imaging device, the reference unit and the imaging unit are adjacently arranged and located in the same column or row in the imaging array, and the filling factor of the imaging structure is greater than or Equal to 50%" feature imaging devices are within the protection scope of the present invention.

To sum up, the present invention can effectively eliminate the influence of noise and process deviation on the imaging information by slightly increasing the area of the imaging unit without increasing the complexity of the peripheral circuit, so that the final imaging information is more realistic Condition.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (3)

1. the image device of an optical pickocff inside, it is characterized in that, described image device is made up of multiple imaging arrangements that are positioned on imaging array, described imaging arrangement comprises a reference unit and at least one image-generating unit, the structure of described reference unit and image-generating unit is identical, described reference unit is for providing the exact value of image device initial threshold voltage, the adjacent arrangement of described reference unit and image-generating unit and be arranged in same row or same a line of imaging array, the fill factor, curve factor of described imaging arrangement is greater than or equal to 50%, described imaging arrangement comprises a reference unit, the first image-generating unit, the second image-generating unit, the 3rd image-generating unit, the 4th image-generating unit, at least one the 5th image-generating unit and/or at least one the 6th image-generating unit and/or at least one the 7th image-generating unit and/or at least one the 8th image-generating unit, described reference unit is between the first image-generating unit and the second image-generating unit, described the first image-generating unit and the second image-generating unit are symmetric with respect to reference unit, simultaneously, described reference unit is between the 3rd image-generating unit and the 4th image-generating unit, described the 3rd image-generating unit and the 4th image-generating unit are symmetric with respect to reference unit, described reference unit, the first image-generating unit and the second image-generating unit are arranged in same a line of imaging array, described reference unit, the 3rd image-generating unit and the 4th image-generating unit are arranged in the same row of imaging array, or described reference unit, the first image-generating unit and the second image-generating unit are arranged in the same row of imaging array, described reference unit, the 3rd image-generating unit and the 4th image-generating unit are arranged in same a line of imaging array, described the 5th image-generating unit arrangement adjacent with the first image-generating unit and be arranged in same a line or the same row of imaging array, the arrangement adjacent with the second image-generating unit of described the 6th image-generating unit is arranged in same a line or the same row of imaging array, described the 7th image-generating unit and the adjacent arrangement of the 3rd image-generating unit are arranged in same a line or the same row of imaging array, and described the 8th image-generating unit and the adjacent arrangement of the 4th image-generating unit are arranged in same a line or the same row of imaging array.

2. the image device of optical pickocff according to claim 1 inside, it is characterized in that, described reference unit and image-generating unit include silicon substrate, source electrode, drain electrode, floating grid and control grid, described source electrode and drain electrode lay respectively at the two ends of silicon substrate, described control grid is positioned at the top of floating grid, described floating grid is positioned at the top of silicon substrate, silicon substrate between described source electrode and drain electrode is isolated by insulating barrier and floating grid, and described floating grid is isolated by insulating barrier and control grid.

One kind have as arbitrary in claim 1 or 2 as described in the optical pickocff of image device.