RU2333569C1 - Photoreceiving cell with vertical colour separation - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention refers to computer vision facilities and can be used in multispectral photodetector arrays, in particular for transformation of colour images of advanced format and high pixel density to electric signals in photo and video cameras. According to invention, photoreceiving cell with vertical colour separation is made as follows. Electrical reading circuit is connected to near-surface region of first conductivity type, while regime reading voltage is supplied to it. Charges of first polarity current carriers accumulated within exposure are formed to be carried to reading circuit from under areas of first conductivity type in areas of the second conductivity type located between all areas of first conductivity type. Vertical channel is formed through corresponding selection within channel areas, with concentration of barrier and base areas, and also their thickness, providing potential wells in areas of first conductivity type for first polarity current carriers of sufficient dimension to collect and store charges first polarity current photocarriers without interference. Note that reading circuit is designed so that it supplies regime reading voltage time-consistently to near-surface region of first conductivity type relative to reference areas at rate multiple to number of potential well representing a reading source, and respectively sufficient for successive charge flow from one potential well to another and to reading circuit from the first, second, third etc potential wells comprising the first, second, third etc areas of first conductivity type.

EFFECT: smaller cell area.

4 dwg

Description

The invention relates to computer vision technology and can be used in multispectral matrix photodetectors, in particular for converting color images of high format and high pixel density into electrical signals in cameras and video cameras.

Known photodetector cells with vertical color separation (See US patents: 5,965,875 “Color separation in the cells of the photodetector using a three-layer structure”, 6,632,701 B2 “Detectors with a vertical color filter and a matrix of them”).

Both sources describe the arrangement of a cell formed on a semiconductor pod containing three semiconductor pn junctions located one above the other, sensitive in different spectral ranges of light, for example, blue, green, and red.

Closest to the claimed invention is the device described in US patent 6,727,521 B2 "Detectors with a vertical color filter and a matrix of them."

The specified device contains a photodetector cell with a vertical color separation, formed on a semiconductor substrate, containing three or more semiconductor regions of the first type of conductivity located one above the other with the configuration necessary for collecting current carriers of the first polarity separated from each other by semiconductor base regions of the second type of conductivity, with the configuration necessary for collecting and removing current carriers of opposite polarity, connected to each other and generally electrode, forming pn junctions with regions of the first type of conductivity with different spectral sensitivities, and providing electrical isolation of the regions of the first type of conductivity from each other and from the base regions, barrier regions located in the base regions under the regions of the first type of conductivity, an electrical reading circuit which, under the control of coordinate sampling signals, feeds mode voltages to the first type of conductivity region and reads the photo signals from each of them.

However, the known devices have a drawback: the cell area is large, since it has isolated leads from all areas of the first type of conductivity to the surface contacts and the corresponding number of readout circuits.

The technical result of the present invention is to reduce the area of the cell.

The specified result is achieved due to the fact that in the known device of the photodetector cell it is proposed:

- connect the electrical circuit under the control of coordinate sampling signals to the near-surface region of the first type of conductivity and supply the read mode voltage to it,

- to form for transfer into the reading circuit accumulated during the exposure of the charge carriers of the first polarity from the lower regions of the first conductivity type in the regions of the second conductivity type located between all areas of the first conductivity type, the vertical channel by appropriate selection in the areas belonging to the channel, the concentration of the barrier and base regions, as well as their thickness, which ensures the presence in the regions of the first type of conductivity of potential wells for current carriers of the first polarity, full-time value for collecting and storing the charges of photocarriers of current of the first polarity without interference,

- moreover, the readout circuit should be implemented in such a way that it ensures that the read-through mode voltage of the readout voltage relative to the base regions is sequentially in time to the near-surface region of the first type of conductivity by a multiple of the number of the potential well from which it reads and, accordingly, is sufficient for the charge to flow sequentially from one potential pits to another and to the reading circuit from the first, second, third, etc. potential holes belonging to the first, second, third, etc. areas of the first type of conductivity.

The above technical result is achieved by the combination of the above new features of the invention.

The decrease in the cell area is achieved due to the fact that it has only one contact to the near-surface region of the first type of conductivity (not counting the common contact of the base layers for all cells) and a corresponding reduction in the number of readout circuits to one.

The list of graphic materials illustrating a device that implements the claimed invention:

Figure 1 illustrates a known device (prototype).

Figure 2 illustrates the proposed device.

Figure 3a shows the potential relief in the structure for potential wells completely filled with carriers (curve 1), for completely empty wells (curve 2), for various combinations of filled (including partially) and empty holes (curves 3-8).

Fig. 3b shows a potential relief in the structure that allows charges to flow into the readout circuit from the first potential well at a voltage on the surface electrode V _D = 1.6 V (curve 1), from the second through the first at V _D = 3.2 V (curve 2) , from the third through the second and first at V _D = 4.8 V (curve 3).

Figure 4 shows the read voltage applied to the surface electrode V _D for reading charges from three potential wells and recovering them.

A photodetector cell with vertical color separation (see Fig. 2) consists of three or more semiconductor regions of the first type of conductivity located above each other (1, 2, 3) with the configuration necessary for collecting current carriers of the first polarity separated from each other by semiconductor the base regions (4) of the second type of conductivity, with the configuration necessary for collecting and removing current carriers of opposite polarity, connected to each other and a common electrode, forming with regions of the first type of conductivity there are pn junctions with different spectral sensitivities, and providing electrical isolation of the regions of the first conductivity type from each other and from the base regions, barrier regions (5, 6, 7) located in the base regions under the regions of the first conductivity type, the readout circuit ( 8) which, under the control of coordinate sampling signals, makes a connection with the near-surface region (1) of the first type of conductivity and the supply of readout voltage to it, a vertical channel (9) formed in the regions of the second type of conductivity range (4), located between all regions of the first type of conductivity (1, 2, 3), by appropriate selection in the areas belonging to the channel, the concentration of barrier (5, 6, 7) and base (10, 11) areas, as well as their thickness, ensuring the presence in the regions of the first type of conductivity of potential wells for current carriers of the first polarity, sufficient for collecting and storing the charges of photocarriers of current of the first polarity without interference, and the reading circuit (8) is designed in such a way that it delivers sequentially time to the near-surface region (1) of the first type of conductivity of read sensing voltages relative to the base regions (4) by a multiple of the number of the potential well from which it reads and, accordingly, sufficient for the charge to flow sequentially from one potential well to another and into the readout circuit from first, second, third, etc. potential wells belonging to the first (1), second (2), third (3), etc. areas of the first type of conductivity.

The characteristics shown in FIG. 3 and FIG. 4 were calculated for a structure having a channel size of 1 × 1 μm ² , a distance between regions (1, 2, 3) of 0.6 μm with a concentration of base regions in the channel (10, 11) of the second type of conductivity (p-type) 10 ¹⁵ cm ^-3 (substrate), the thickness of the barrier (5, 6, 7) regions of 0.3 μm with a concentration of the second type of conductivity (p-type) 3 10 ¹⁶ cm ^-3 , their location is exactly in the middle between regions (1) - (2), (2) - (3) and below region (3) on the penetration boundary of the red component of light. The vertical structure of the cell, in addition to the channel, in accordance with the present invention has a zone of insulating base regions (4) of the second type of conductivity (p-type) with a concentration of 2 · 10 ¹⁷ cm ^-3 and barrier (5, 6, 7) regions (p- type) with a concentration of 3 · 10 ¹⁶ cm ^-3 . The width of this zone is 0.3 μm. Concentrations in all areas of the structure except the substrate have a Gaussian distribution. The cell step together with the transistor of the sampling circuit with the sizes of regions (1, 2, 3) not exceeding the channel limits does not exceed 2 μm with a gate length of 0.25 μm.

The cell works as follows:

The readout circuit (8) during connection connects sequentially in time (see Fig. 4) to the near-surface region (1) of the first type of conductivity, the readout operating voltages relative to the base regions (4) by a multiple of the number of the potential well from which it reads, and, accordingly, sufficient for the successive transfer of charge from one potential well to another and into the reading circuit from the first, second, third, etc. potential wells belonging to the first (1), second (2), third (3), etc. areas of the first type of conductivity. After the charge is transferred from the last (in Fig. 2, the third region) potential well and the read voltage is removed, the second and third potential wells are restored (see Fig. 3, curve 4). Then, the first potential well is restored by applying to the region (1) the corresponding read voltage (see Fig. 3, curve 2). After this, the connection of the readout circuit with region (1) is opened and all potential wells are pre-installed and go into the accumulation phase of photocarriers created by light, each in the zone limited by the barrier regions.

The present description of the invention, including the composition and operation of the device, including the proposed version of its execution, involves its further possible improvement by specialists and does not contain any restrictions in terms of implementation. All claims are formulated solely in the claims.

Claims (1)

A vertical color-separation photodetector cell formed on a semiconductor substrate containing three or more semiconductor regions of the first type of conductivity located one above the other with the configuration necessary for collecting current carriers of the first polarity separated from each other by semiconductor base regions of the second type of conductivity, with the configuration necessary for collecting and removing current carriers of opposite polarity, connected to each other and a common electrode, forming with by regions of the first type of conductivity, pn junctions with different spectral sensitivities, and providing electrical isolation of the regions of the first type of conductivity from each other and from the base regions, barrier regions located in the base regions under the regions of the first type of conductivity, an electrical readout circuit controlled by coordinate signals sampling the supply to the region of the first type of conductivity of the operating voltage and the reading of the photo signals from each of them, characterized in that the electrical circuit with washing is connected to the near-surface region of the first type of conductivity and delivers a read mode voltage to it, and for transfer to the reading circuit accumulated during the exposure of the charges of current carriers of the first polarity from the lower regions of the first type of conductivity in areas of the second type of conductivity located between all areas of the first type conductivity, a vertical channel is formed by appropriate selection in the areas belonging to the channel, the concentration of the barrier and base areas, and t their thickness, which ensures that in the regions of the first type of conductivity potential wells for current carriers of the first polarity are of sufficient size to collect and store charges of photocarriers of current of the first polarity without interference, the readout circuit is designed in such a way that it delivers the first time series to the surface region of the first such as the conductivity of the read mode voltages relative to the base areas by a multiple of the number of the potential well from which it reads set, and accordingly sufficient for sequential charge transfer from one potential well to another, and a reading circuit of the first, second, third, etc. potential holes belonging to the first, second, third, etc. areas of the first type of conductivity.

Images