Composite dielectric gate photosensitive detection unit and detector

Abstract

The utility model discloses a composite dielectric gate photosensitive detection unit and a detector, each unit comprises a composite dielectric gate photosensitive capacitor and a composite dielectric gate MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor), and the composite dielectric gate photosensitive capacitor and the composite dielectric gate MOSFET are formed above the same P-type semiconductor substrate. An active region of a P-type semiconductor substrate of the composite dielectric gate MOSFET adopts an L-shaped or U-shaped structure, the direction of an electric field between a source and a drain is arc-shaped, electron accelerated motion is restrained, channel hot electron injection is not easy to occur in electric field distribution, and the structure of the L-shaped or U-shaped active region enables the composite dielectric gate photosensitive detector to work at a higher drain terminal voltage, so that the reliability of the composite dielectric gate photosensitive detector is improved. And the working current of the photosensitive detector is larger under the same gate voltage, so that the readout noise of the photosensitive detector is further reduced. The P-type semiconductor substrate active region of the composite dielectric gate MOSFET adopts an annular structure, so that the layout in two dimensions of a two-dimensional plane is realized, the equivalent gate length of the composite dielectric gate MOSFET is increased, the channel area of a transistor is increased, and the random telegraph noise is reduced.

Description

Technical Field

[0001] The utility model relates to the field of imaging devices, in particular to a composite dielectric grating photosensitive detection unit and a detector. Background Art

[0002] The solid-state imaging sensor market is booming and experiencing exponential growth due to the demand in digital and video cameras, mobile imaging, surveillance and biometrics. Traditionally, CCD is the dominant imaging technology. However, with the rapid development of CMOS technology, CMOS image sensor (CIS) technology has been widely used in many fields, such as PC cameras, mobile phones, high-end digital cameras, etc. In addition, with the iterative optimization of technology, it can be comparable to CCD in some performance aspects, and it has become a substitute for CCD. However, the common CMOS-APS consists of a photodiode and a readout selection transistor, usually with four or five transistors. As the pixel size decreases, it is difficult for CIS to maintain a large full well charge (the maximum amount of detection signal that each pixel can accommodate) to obtain a large signal-to-noise ratio, which makes it difficult to ensure image quality. At the same time, the size of other transistors in the pixel is also subject to great constraints. On the one hand, the actual preparation process will increase the non-uniformity of doping. On the other hand, the effective channel area of ​​the transistor will decrease, that is, the gate oxide capacitance (the capacitance formed by the oxide layer between the gate and the channel) will decrease. These will increase the influence of a single carrier in the channel when the transistor is working, thereby increasing the noise of the transistor, especially random telegraph noise (RTN).

[0003] Patent CN115732523A proposes a back-illuminated photosensitive array based on a composite dielectric gate and an imaging device thereof, which can reduce the pixel size while ensuring a high full well capacity of the pixel, and can achieve full isolation between pixels to reduce the impact of crosstalk. However, it also faces the problem of increased random telegraph noise caused by the reduction in transistor size, which restricts the further improvement of the signal-to-noise ratio of the image sensor.

[0004] Since the size of random telegraph noise satisfies RTN∝T ox / (W·L), so thinning the effective thickness of the transistor gate oxide and increasing the effective area of ​​the channel can suppress the noise. However, due to the influence of pixel size, the gate length of the composite dielectric gate MOSFET must be smaller than the pixel size in the gate length direction. Therefore, the scheme of reducing noise by increasing the length of the gate in a single direction of the MOSFET is subject to certain constraints. At the same time, due to the floating gate structure of the composite dielectric gate MOSFET, when the drain voltage is high, the channel hot electron injection effect is prone to occur, which limits the drain operating voltage of the composite dielectric gate MOSFET. Under the same gate voltage, the drain current of the composite dielectric gate is small, and the influence of current noise fluctuation is large. Utility Model Content

[0005] The purpose of this section is to summarize some aspects of the embodiments of the utility model and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract of the specification and the name of the utility model of this application to avoid blurring the purpose of this section, the abstract of the specification and the name of the utility model, and such simplifications or omissions cannot be used to limit the scope of the utility model.

[0006] In view of the above problems and / or the problems existing in the prior art, the present utility model is proposed.

[0007] Therefore, the technical problem to be solved by the utility model is to propose a layout format that effectively reduces the readout noise of the composite dielectric gate photosensitive detector, increase the effective length of the composite dielectric gate reading gate through a specially designed active area structure, break through the limitation of the pixel size on the gate length in a single direction, and realize the increase of the channel area of ​​the composite dielectric gate MOSFET and reduce the readout noise.

[0008] In order to solve the above technical problems, the utility model provides the following technical solutions: a composite dielectric grating photosensitive detection unit, including an array layout based on a composite dielectric grating photosensitive detector, the array is composed of four pixels, each pixel includes a composite dielectric grating photosensitive capacitor and a composite dielectric gate MOSFET, and the composite dielectric gate photosensitive capacitor and the composite dielectric gate MOSFET are formed on the same P-type semiconductor substrate. The active area of ​​the P-type semiconductor substrate of the composite dielectric gate MOSFET adopts an L-shaped structure or a U-shaped structure to achieve layout in two dimensions of a two-dimensional plane. The composite dielectric gate photosensitive capacitor and the composite dielectric gate MOSFET share a composite dielectric gate, and the composite dielectric gate includes a bottom dielectric layer, a floating gate, a top dielectric layer and a control gate from bottom to top.

[0009] As a preferred solution of the composite dielectric grating photosensitive detection unit of the utility model, the photosensitive capacitor can be a MOS capacitor, that is, a metal-oxide-semiconductor capacitor.

[0010] As a preferred solution of the composite dielectric gate photosensitive detection unit of the utility model, the composite dielectric gate photosensitive capacitor and the composite dielectric gate MOSFET share the composite dielectric gate;

[0011] The composite dielectric gate includes a bottom dielectric layer, a floating gate, a top dielectric layer and a control gate from bottom to top.

[0012] As a preferred solution of the composite dielectric gate photosensitive detection unit of the utility model, a second isolation structure is provided between the composite dielectric gate photosensitive capacitor and the composite dielectric gate MOSFET.

[0013] As a preferred solution of the composite dielectric grating photosensitive detection unit of the utility model, when a plurality of composite dielectric grating photosensitive detection units are arranged, a first isolation structure is provided between adjacent units;

[0014] The first isolation structure penetrates the P-type semiconductor substrate.

[0015] As a preferred solution of the composite dielectric grating photosensitive detection unit of the utility model, the first isolation structure includes a first isolation structure dielectric layer and a first isolation structure gate, and the first isolation structure dielectric layer wraps the first isolation structure gate.

[0016] As a preferred solution of the composite dielectric grating photosensitive detection unit of the utility model, a conductive layer is provided under the P-type semiconductor substrate for transmitting the substrate voltage.

[0017] As a preferred solution of the composite dielectric grating photosensitive detection unit of the utility model, the conductive layer 500 is doped P-type single crystal silicon or polycrystalline silicon, or is intrinsic single crystal silicon or polycrystalline silicon.

[0018] As a preferred solution of the composite dielectric grating photosensitive detection unit of the utility model, wherein: a high dielectric constant layer is arranged below the conductive layer;

[0019] The high dielectric constant layer has the property of forming hole accumulation on the lower surface of the conductive layer.

[0020] The beneficial effects of the utility model are as follows: for the rectangular active area structure, the direction of the electric field between the source and the drain points directly from the drain end to the source end, and there is no obstruction when the electrons move toward the drain end. However, for the L-shaped and U-shaped active area structures, the direction of the electric field between the source and the drain is arc-shaped, and the accelerated motion of the electrons is subject to certain constraints. Therefore, the structure of the L-shaped active area allows the composite dielectric gate photodetector to operate at a larger drain voltage, and the photodetector works more effectively under the same gate voltage. According to noise theory, the larger the operating current of the composite dielectric gate reading MOSFET, the smaller the proportion of current noise fluctuation, which will further reduce the readout noise of the photodetector.

[0021] Since the independent composite dielectric grating photosensitive detection unit cannot exert its imaging effect.

[0022] Therefore, the technical problem to be solved by the present invention is to combine independent composite dielectric grating photosensitive detection units into a photosensitive sensing entity device.

[0023] In order to solve the above technical problems, the utility model also provides the following technical solutions: comprising a plurality of composite dielectric grating photosensitive detection units, the composite dielectric grating photosensitive detection units arranged according to the above rules are further regularly arranged to form a photosensitive detector entity.

[0024] Beneficial effects of the utility model: the photosensitive detection unit with optimized effect is actually used on the sensing component to act as a detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the following briefly introduces the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0026] Figure 1 This is a schematic diagram of the structure of the photosensitive detection unit in patent CN115732523A;

[0027] Figure 2 A schematic diagram of an L-shaped structure and a U-shaped structure of a composite dielectric grating photosensitive detection unit according to an embodiment of the utility model;

[0028] Figure 3 It is a structural schematic diagram of the photosensitive detection unit array state in patent CN115732523A;

[0029] Figure 4 A schematic diagram of an L-shaped structure array state structure of a composite dielectric grating photosensitive detection unit according to an embodiment of the present utility model;

[0030] Figure 5 An embodiment of the present invention is described Figure 2 Middle edge X 1 -X 1 'Direction cross-sectional stacking structure diagram;

[0031] Figure 6 An embodiment of the present invention is described Figure 2 Middle edge X 2 -X 2 'Direction cross-sectional stacking structure diagram;

[0032] Figure 7 An embodiment of the present invention is described Figure 2 Middle edge Y 1 -Y 1 'Direction cross-sectional stacking structure diagram;

[0033] Figure 8 An embodiment of the present invention is described Figure 2 Middle edge Y 2 -Y 2 'Direction cross-sectional stacking structure diagram;

[0034] Fig. 9 A schematic diagram of a U-shaped structure array state structure of a composite dielectric grating photosensitive detection unit according to an embodiment of the present utility model;

[0035] Fig.10 An embodiment of the present invention is described Fig. 9 Middle edge X 3 -X 3 'Direction cross-sectional stacking structure diagram;

[0036] Fig.11 An embodiment of the present invention is described Figure 2 Middle edge X 4 -X 4 'Direction cross-sectional stacking structure diagram;

[0037] Fig.12 An embodiment of the present invention is described Figure 2 Middle edge Y 3 -Y 3 'Direction cross-sectional stacking structure diagram;

[0038] Fig.13 An embodiment of the present invention is described Figure 2 Middle edge Y 4 -Y 4 'Direction cross-sectional stacking structure diagram; DETAILED DESCRIPTION

[0039] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0040] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0041] Secondly, the present invention is described in detail with reference to the schematic diagram. When describing the embodiments of the present invention, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general proportion, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0042] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0043] Example 1

[0044] Reference Figures 1 to 13 This embodiment provides a composite dielectric grating photosensitive detection unit and the corresponding prior art, namely, a 2×2 array layout structure diagram of a representative photosensitive detector of a composite dielectric grating structure in patent CN115732523A and an improved L-shaped composite dielectric grating photosensitive detection unit array state. Figure 1 The portion framed by the midpoint dashed line is the smallest composite dielectric grating photosensitive detector unit. A plurality of repeated, smallest composite dielectric grating photosensitive detector units are periodically prepared on the substrate according to the set layout design. Each unit includes a composite dielectric grating photosensitive capacitor A for sensing light and a composite dielectric gate MOSFET B for reading. The composite dielectric gate photosensitive capacitor A and the composite dielectric gate MOSFET B are formed on the same P-type semiconductor substrate 100.

[0045] That is to say, the active area of ​​the P-type semiconductor substrate 100 is divided into two parts, A and B, A is the P-type active area of ​​the composite dielectric gate photosensitive capacitor, and B is the P-type active area of ​​the composite dielectric gate MOSFET;

[0046] refer to Figure 1 The prior art part of the composite dielectric grating photosensitive detection unit, wherein the structure B adopts a rectangular structure, and the width of the structure is W T , length L T , the read noise satisfies N S ∝T ox / (W T ·L T ), it can be seen that the length L T The larger the value, the smaller the read noise, but the length L T It will be limited by the size of the photosensitive detector unit, that is, the size will not exceed the size of the photosensitive detector unit, and it is only adjustable in a single dimension of the two-dimensional plane.

[0047] Further, a technical solution is provided to make the active area of ​​the P-type semiconductor substrate 100 of the composite dielectric gate MOSFET into an L-shaped or U-shaped structure, and to integrate and adjust the active area functionally and structurally to meet the requirements of L T Under the condition of limited size of photosensitive detector unit, multi-dimensional length extension is made based on the existing rectangular structure, such as Figure 2 The basic structural state of the L-type and U-type composite dielectric grating photosensitive detection units are shown.

[0048] Example 2

[0049] Reference Figures 1 to 8 , which is the second embodiment of the present invention, and this embodiment is based on the previous embodiment, and is different from the previous embodiment in that: the 2×2 array layout structure of the representative photosensitive detector of the composite dielectric grating structure of the present invention is as follows Figure 2 As shown, the part selected by the dotted line in the figure is the smallest composite dielectric grating photosensitive detector unit, and the repeating unit includes but is not limited to the following layout: P-type semiconductor substrate 100 active area, control gate 201, first isolation structure 400, second isolation structure 300;

[0050] The active area of ​​the P-type semiconductor substrate 100 is divided into two parts, A and B. A is the P-type active area of ​​the composite dielectric gate photosensitive capacitor, and B is the P-type active area of ​​the composite dielectric gate MOSFET. The structure of B adopts an L-shaped structure, and the width of the structure is W. T , the length of the two dimensions is L T1 and L T2 , at this time, the equivalent gate length L of the composite dielectric gate MOSFET ET for In the two-dimensional plane, both dimensions follow L T1 and L T2 It changes and is adjustable.

[0051] According to noise theory calculation, the ratio of the noise magnitude of the composite dielectric gate MOSFET in the L-shaped structure active area disclosed in the utility model to the composite dielectric gate in the rectangular structure active area is:

[0052]

[0053] For example, considering (but not limited to) the 1.4um pixel size commonly used in the prior art, assuming that the width of the first isolation structure is 100nm, and the size of the source and drain of the composite dielectric gate MOSFET is 100nm, then the gate length L of the composite dielectric gate MOSFET in the active area of ​​the rectangular structure is TIn the extreme case, it is 1100nm. In the extreme case, the equivalent gate length of the L-shaped composite dielectric gate MOSFET is 2300nm when inserted into the above formula, that is, the noise of the composite dielectric gate MOSFET in the L-shaped active area can be reduced by 2 times compared with the composite dielectric gate noise in the rectangular active area. At the same time, for the composite dielectric gate photosensitive detector unit in the L-shaped active area, although the area of ​​the composite dielectric gate photosensitive capacitor used to collect photoelectrons is reduced, the full well capacity index has not been reduced, and is basically the same as the full well capacity of the composite dielectric gate photosensitive detector unit in the rectangular active area. Therefore, considering the readout noise and full well capacity indicators comprehensively, the composite dielectric gate photosensitive detector unit in the L-shaped active area has a better dynamic range indicator. Compared with the composite dielectric gate photosensitive detector unit in the rectangular active area, the former can be improved by 20lg2 dB, that is, about 6dB.

[0054] Example 3

[0055] Reference Figures 1 to 5 , which is the third embodiment of the present utility model, is based on the previous embodiment, and is different from the previous embodiment in that: Figure 5 For photosensitive detectors in X 1 -X' 1 The cross section includes two photosensitive detection unit structures, which are bilaterally symmetrical. The composite dielectric gate photosensitive capacitor A and the composite dielectric gate MOSFET B of the photosensitive detection unit are formed on the same P-type semiconductor substrate 100, and the functional areas of the two are separated by a second isolation structure 300;

[0056] The composite dielectric gate photosensitive capacitor A and the composite dielectric gate MOSFET B share a composite dielectric gate structure, the composite dielectric gate 200, whose structure from bottom to top includes a bottom dielectric layer 204, a floating gate 203, a top dielectric layer 202 and a control gate 201. When a plurality of photosensitive detection units are arranged, a first isolation structure 400 penetrating the P-type semiconductor substrate 101 is provided between adjacent detection units along the substrate depth direction to separate the active regions of the P-type semiconductor substrate 100 of adjacent photosensitive detection units; the first isolation structure 400 includes a first isolation structure dielectric layer 401 and a first isolation structure gate 402, and the first isolation structure gate 402 is wrapped by the first isolation structure dielectric layer 401.

[0057] A lightly doped P-type single crystal silicon or polycrystalline silicon epitaxial layer is formed on the lower surface of the P-type semiconductor substrate 100 as a conductive layer 500. The photosensitive detection unit structure realizes the transmission of the substrate voltage through the conductive layer 500, and the first isolation structure gate 402 and the conductive layer 500 are electrically isolated by the first isolation structure dielectric layer 401. A high dielectric constant layer 600 is arranged below the conductive layer 500, and the high dielectric constant layer 600 will form hole accumulation on the upper surface of the conductive layer 500, which also helps to transmit the substrate voltage.

[0058] Example 4

[0059] Reference Figures 1 to 6 , which is the fourth embodiment of the present utility model, is based on the previous embodiment, and is different from the previous embodiment in that:

[0060] Figure 6 For photosensitive detectors in X 2 -X' 2 The cross section only includes the composite dielectric gate MOSFET structure B of two photosensitive detection units, which is symmetrical on both sides. The composite dielectric gate MOSFET structure B is formed on the same P-type semiconductor substrate 100, and the two are separated by the first isolation structure 400 to achieve functional area separation; the first isolation structure 400 includes a first isolation structure dielectric layer 401 and a first isolation structure gate 402, the first isolation structure dielectric layer 401 is adjacent to the source (or drain) N-type doping region of the composite dielectric gate MOSFET, and the first isolation structure gate 402 is wrapped by the first isolation structure dielectric layer 401.

[0061] The composite dielectric gate 200 includes a common bottom dielectric layer 204, a floating gate 203, a top dielectric layer 202 and a control gate 201 from bottom to top. A lightly doped P-type single crystal silicon or polycrystalline silicon epitaxial layer is formed on the lower surface of the P-type semiconductor substrate 100 as a conductive layer 500. The photosensitive detection unit structure realizes the transmission of substrate voltage through the conductive layer 500, and the first isolation structure gate 402 and the conductive layer 500 are electrically isolated by the first isolation structure dielectric layer 401. A high dielectric constant layer 600 is arranged below the conductive layer 500, and the high dielectric constant layer 600 will form hole accumulation on the upper surface of the conductive layer 500, which also helps to transmit the substrate voltage.

[0062] Example 5

[0063] Reference Figures 1 to 7 , which is the fifth embodiment of the utility model, is based on the previous embodiment, and is different from the previous embodiment in that:

[0064] Figure 7 For photosensitive detectors in Y 1 -Y' 1 The cross section includes two photosensitive detection unit structures, which are symmetrical. The composite dielectric gate photosensitive capacitor A and the composite dielectric gate MOSFET B of the photosensitive detection unit are formed on the same P-type semiconductor substrate 100. The functional regions of the two are separated by a second isolation structure 300. For the composite dielectric gate MOSFET, only the source (or drain) N-type doping region thereof is shown in the figure.

[0065] The composite dielectric gate 200 includes a bottom dielectric layer 204, a floating gate 203, a top dielectric layer 202 and a control gate 201 from bottom to top. When a plurality of photosensitive detection units are arranged, a first isolation structure penetrating the P-type semiconductor substrate 101 is provided between adjacent detection units along the substrate depth direction to separate the active regions of the P-type semiconductor substrate 100 of adjacent photosensitive detection units; the first isolation structure 400 includes a first isolation structure dielectric layer 401 and a first isolation structure gate 402, and the first isolation structure gate 402 is wrapped by the first isolation structure dielectric layer 401.

[0066] A lightly doped P-type single crystal silicon or polycrystalline silicon epitaxial layer is formed on the lower surface of the P-type semiconductor substrate 100 as a conductive layer 500. The photosensitive detection unit structure realizes the transmission of the substrate voltage through the conductive layer 500, and the first isolation structure gate 402 and the conductive layer 500 are electrically isolated by the first isolation structure dielectric layer 401. A high dielectric constant layer 600 is arranged below the conductive layer 500, and the high dielectric constant layer 600 will form hole accumulation on the upper surface of the conductive layer 500, which also helps to transmit the substrate voltage.

[0067] Example 6

[0068] Reference Figures 1 to 8 , which is the sixth embodiment of the present utility model, is based on the previous embodiment, and is different from the previous embodiment in that:

[0069] Figure 8 For photosensitive detectors in Y 2 -Y' 2 The cross section only includes a composite dielectric gate MOSFET structure B of two photosensitive detection units, which are symmetrical on the left and right. The composite dielectric gate MOSFET structure B is formed on the same P-type semiconductor substrate 100, and the two are separated from each other by a first isolation structure 400. The first isolation structure 400 includes a first isolation structure dielectric layer 401 and a first isolation structure gate 402. The first isolation structure dielectric layer 401 is adjacent to the drain (or source) N-type doped region of the composite dielectric gate MOSFET, and the first isolation structure gate 402 is wrapped by the first isolation structure dielectric layer 401.

[0070] The composite dielectric gate 200 includes a common bottom dielectric layer 204, a floating gate 203, a top dielectric layer 202 and a control gate 201 from bottom to top. A lightly doped P-type single crystal silicon or polycrystalline silicon epitaxial layer is formed on the lower surface of the P-type semiconductor substrate 100 as a conductive layer 500. The photosensitive detection unit structure realizes the transmission of substrate voltage through the conductive layer 500, and the first isolation structure gate 402 and the conductive layer 500 are electrically isolated by the first isolation structure dielectric layer 401. A high dielectric constant layer 600 is arranged below the conductive layer 500, and the high dielectric constant layer 600 will form hole accumulation on the upper surface of the conductive layer 500, which also helps to transmit the substrate voltage.

[0071] The conductive layer 500 is doped P-type single crystal silicon or polycrystalline silicon, or intrinsic single crystal silicon or polycrystalline silicon.

[0072] The high dielectric constant layer 600 has a property of forming holes to accumulate on the lower surface of the conductive layer 500 .

[0073] Example 7

[0074] Reference Figures 1 to 9 , which is the seventh embodiment of the utility model, and this embodiment is based on the previous embodiment, and the difference from the previous embodiment is: further, on the basis of all the above embodiments, the 2×2 array layout structure of the representative photosensitive detector of the composite dielectric grating 200 of the present patent is as follows Figure 7 As shown, the part selected by the dotted line in the figure is the smallest composite dielectric gate photosensitive detector unit, and the repeated unit includes but is not limited to the following layout: P-type semiconductor substrate 100 active area, control gate 201, first isolation structure 400, second isolation structure 300, wherein the P-type semiconductor substrate 100 active area is divided into two parts A and B, A is the P-type active area of ​​the composite dielectric gate photosensitive capacitor, B is the P-type active area of ​​the composite dielectric gate MOSFET, and the structure of B adopts a U-shaped structure, and the width of the structure is W T , the length of the two dimensions is L T1 and L T2 , at this time, the equivalent gate length L of the composite dielectric gate MOSFET ET for In the two-dimensional plane, both dimensions follow L T1 and L T2 It changes and is adjustable.

[0075] According to noise theory calculation, the ratio of the noise size of the composite dielectric gate MOSFET in the U-shaped active area to the composite dielectric gate in the rectangular active area is:

[0076]

[0077] Considering but not limited to the pixel size of 1.4um, assuming that the width of the first isolation structure 400 is 100nm, the size of the source and drain of the composite dielectric gate MOSFET is 100nm, and the width of the active area is 100nm, the gate length L of the composite dielectric gate MOSFET in the active area of ​​the rectangular structure is T In the extreme case, it is 1100nm, and the equivalent gate length of the U-shaped composite dielectric gate MOSFET is 3600nm in the extreme case, that is, the noise of the composite dielectric gate MOSFET in the U-shaped active area can be reduced by 3.27 times compared with the composite dielectric gate noise in the rectangular active area. At the same time, for the composite dielectric gate photosensitive detector unit in the U-shaped active area, although the area of ​​the composite dielectric gate photosensitive capacitor used to collect photoelectrons is reduced, the full well capacity index has not been reduced, and is basically the same as the full well capacity of the composite dielectric gate photosensitive detector unit in the rectangular active area. Therefore, considering the readout noise and full well capacity indicators comprehensively, the composite dielectric gate photosensitive detector unit in the U-shaped active area has a better dynamic range indicator. Compared with the composite dielectric gate photosensitive detector unit in the rectangular active area, the former can be improved by 20lg3.27dB, that is, about 10dB.

[0078] Example 8

[0079] Reference Figures 1 to 10 , which is the eighth embodiment of the present utility model, is based on the previous embodiment, and is different from the previous embodiment in that:

[0080] Fig.10 For photosensitive detectors in X 3 -X' 3 The cross section includes two photosensitive detection unit structures, which are bilaterally symmetrical. The composite dielectric gate photosensitive capacitor A and the composite dielectric gate MOSFET of the photosensitive detection unit are formed on the same P-type semiconductor substrate 100, and the functional areas of the two are separated by the second isolation junction 9;

[0081] The composite dielectric gate photosensitive capacitor A and the composite dielectric gate MOSFETB share the composite dielectric gate 200, which includes a bottom dielectric layer 204, a floating gate 203, a top dielectric layer 202 and a control gate 201 from bottom to top. When multiple photosensitive detection units are arranged, a first isolation structure 400 penetrating the P-type semiconductor substrate 100 is provided between adjacent detection units along the substrate depth direction to separate the active areas of the P-type semiconductor substrate 100 of adjacent photosensitive detection units; the first isolation structure 400 includes a first isolation structure dielectric layer 401 and a first isolation structure gate 402, and the first isolation structure gate 402 is wrapped by the first isolation structure dielectric layer 401. The first isolation structure dielectric layer 401 is adjacent to the source (or drain) N-type doping region and the drain (or source) N-type doping region of the composite dielectric gate MOSFET. The second isolation structure 300 is adjacent to the source (or drain) N-type doping region and the drain (or source) N-type doping region of the composite dielectric gate MOSFET.

[0082] A lightly doped P-type single crystal silicon or polycrystalline silicon epitaxial layer is formed on the lower surface of the P-type semiconductor substrate 100 as a conductive layer 500. The photosensitive detection unit structure realizes the transmission of the substrate voltage through the conductive layer 500, and the first isolation structure gate 402 and the conductive layer 500 are electrically isolated by the first isolation structure dielectric layer 401. A high dielectric constant layer 600 is arranged below the conductive layer 500, and the high dielectric constant layer 600 will form hole accumulation on the upper surface of the conductive layer 500, which also helps to transmit the substrate voltage.

[0083] Example 9

[0084] Reference Figures 1 to 11 , which is the ninth embodiment of the present utility model, is based on the previous embodiment, and is different from the previous embodiment in that: Fig.11 For photosensitive detectors in X 4 -X' 4 The cross section only includes the composite dielectric gate photosensitive capacitor A and the composite dielectric gate MOSFET of the two photosensitive detection units, which share the composite dielectric gate 200, and are symmetrical. The composite dielectric gate photosensitive capacitor A and the composite dielectric gate MOSFET share the composite dielectric gate 200 formed on the same P-type semiconductor substrate 100, and the two are completely separated by the first isolation structure 400; the first isolation structure 400 includes a first isolation structure 400 dielectric layer 401 and a first isolation structure 400 gate, and the first isolation structure gate 402 is wrapped by the first isolation structure dielectric layer 401.

[0085] The composite dielectric gate 200 includes a common bottom dielectric layer 204, a floating gate 203, a top dielectric layer 202 and a control gate 201 from bottom to top. A lightly doped P-type single crystal silicon or polycrystalline silicon epitaxial layer is formed on the lower surface of the P-type semiconductor substrate 100 as a conductive layer 500. The photosensitive detection unit structure realizes the transmission of substrate voltage through the conductive layer 500, and the first isolation structure gate 402 and the conductive layer 500 are electrically isolated by the first isolation structure dielectric layer 401. A high dielectric constant layer 600 is arranged below the conductive layer 500, and the high dielectric constant layer 600 will form hole accumulation on the upper surface of the conductive layer 500, which also helps to transmit the substrate voltage.

[0086] Example 10

[0087] Reference Figures 1 to 12 , which is the tenth embodiment of the present utility model, is based on the previous embodiment, and is different from the previous embodiment in that: Fig.12 For photosensitive detectors in Y 3 -Y' 3 The cross section includes two photosensitive detection unit structures, which are symmetrical on the left and right. The composite dielectric gate photosensitive capacitor A and the composite dielectric gate MOSFETB of the photosensitive detection unit are formed on the same P-type semiconductor substrate 100, and the functional areas of the two are separated by a second isolation structure 300.

[0088] The composite dielectric gate MOSFET structure includes, from bottom to top, a bottom dielectric layer 204, a floating gate 203, a top dielectric layer 202, and a control gate 201. When a plurality of photosensitive detection units are arranged, a first isolation structure 400 penetrating the P-type semiconductor substrate 100 is provided between adjacent detection units along the substrate depth direction to separate the active regions of the P-type semiconductor substrate 100 of adjacent photosensitive detection units; the first isolation structure 400 includes a first isolation structure dielectric layer 401 and a first isolation structure gate 402, and the first isolation structure gate 402 is wrapped by the first isolation structure dielectric layer 401.

[0089] A lightly doped P-type single crystal silicon or polycrystalline silicon epitaxial layer is formed on the lower surface of the P-type semiconductor substrate 100 as a conductive layer 500. The photosensitive detection unit structure realizes the transmission of the substrate voltage through the conductive layer 500, and the first isolation structure gate 402 and the conductive layer 500 are electrically isolated by the first isolation structure dielectric layer 401. A high dielectric constant layer 600 is arranged below the conductive layer 500, and the high dielectric constant layer 600 will form hole accumulation on the upper surface of the conductive layer 500, which also helps to transmit the substrate voltage.

[0090] Embodiment 11

[0091] Reference Figures 1 to 13, which is the eleventh embodiment of the present utility model, is based on the previous embodiment, and is different from the previous embodiment in that: Fig.13 For photosensitive detectors in Y 4 -Y' 4 The cross section only includes a composite dielectric gate MOSFET structure of two photosensitive detection units, which is symmetrical on the left and right. The composite dielectric gate MOSFET structure 13 is formed on the same P-type semiconductor substrate 100, and the two are completely separated by a first isolation structure 400; the first isolation structure 400 includes a first isolation structure dielectric layer 401 and a first isolation structure gate 402, and the first isolation structure dielectric layer 401 is adjacent to the drain (or source) N-type doped region of the composite dielectric gate MOSFET.

[0092] The composite dielectric gate 200 includes a common bottom dielectric layer 204, a floating gate 203, a top dielectric layer 202 and a control gate 201 from bottom to top. A lightly doped P-type single crystal silicon or polycrystalline silicon epitaxial layer is formed on the lower surface of the P-type semiconductor substrate 100 as a conductive layer 500. The photosensitive detection unit structure realizes the transmission of substrate voltage through the conductive layer 500, and the first isolation structure gate 402 and the conductive layer 500 are electrically isolated by the first isolation structure dielectric layer 401. A high dielectric constant layer 600 is arranged below the conductive layer 500. The high dielectric constant layer 308 will form hole accumulation on the upper surface of the conductive layer 500, which also helps to transmit the substrate voltage.

[0093] Example 12

[0094] Reference Figures 1 to 13 , which is the twelfth embodiment of the present utility model, is based on the previous embodiment, and is different from the previous embodiment in that except Figure 7 The bottom dielectric layers in other figures are all made of silicon dioxide, silicon nitride or other high dielectric constant dielectrics;

[0095] The top dielectric layer can adopt the following structures:

[0096] Silica monolayer structure;

[0097] Double-layer structure of silicon dioxide and silicon nitride;

[0098] Three-layer structure of silicon dioxide, silicon nitride and silicon dioxide;

[0099] Three-layer structure of silicon dioxide, aluminum oxide and silicon dioxide;

[0100] Furthermore, the dielectric layer has a thickness of less than 10 nanometers, and the floating gate and the control gate 201 are made of N-type doped polysilicon;

[0101] Furthermore, the dielectric layer of the first isolation structure 400 and the second isolation structure 300 are made of silicon dioxide, silicon nitride or other high dielectric constant dielectrics with a thickness of 5 to 10 nm;

[0102] The gate of the first isolation structure 400 is made of N-type doped polysilicon, and the conductive layer 500 is made of lightly doped P-type single crystal silicon epitaxial layer or polysilicon epitaxial layer, with a thickness of about 10 to 100 nm;

[0103] The high dielectric constant material may have a structure of one or more combinations of aluminum oxide, tantalum oxide, hafnium oxide, hafnium silicon oxide, hafnium aluminum oxide, or hafnium tantalum oxide.

[0104] Embodiment 13

[0105] Reference Figures 1 to 13 , which is the second embodiment of the utility model, provides a composite dielectric grating photosensitive detector, which includes an array composed of multiple composite dielectric grating photosensitive detection units in special states described in any of the above embodiments. The entity formed by arranging them in a uniform and equidistant manner is an actual product component used for sensing detection, and the full effect of the complete technical solution can be exerted based on the existing technology.

[0106] The improvement of the rectangular active area structure into an L-shaped and U-shaped active area structure proposed in the technical solution is not an obvious new configuration, because this will bring new problems and even challenges to the relevant product preparation process. When adopting the new configuration, in order to make the electric field distribution in the composite dielectric gate MOSFET channel uniform, avoid the peak electric field, and cause the phenomenon of electron avalanche in the local channel, it is necessary to reasonably control the bending area of ​​the L-shaped and U-shaped active area structures in a fine-tuning manner during the layout design and actual process manufacturing process, so that the corners present an arc with a certain curvature, and improve the right-angle morphology in the layout. At the same time, after forming a more complex active area structure, it is necessary to further control the consistency of process etching and doping more finely to reduce the inconsistency of the electrical characteristics of the composite dielectric gate MOSFET caused by process fluctuations. Those skilled in the art can refer to the disclosure of the utility model, make reasonable efforts, and complete these process changes without creative labor.

[0107] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and ratio of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), installation arrangements, use of materials, color, directional changes, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present utility model. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure of performing the function described herein, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the present invention is not limited to a specific embodiment, but extends to various modifications that still fall within the scope of the appended claims.

[0108] Additionally, in order to provide a concise description of example embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0109] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0110] It should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. A composite dielectric grating photosensitive detection unit, characterized in that: Each of the units comprises a composite dielectric gate photosensitive capacitor (A) for sensing light and a composite dielectric gate MOSFET (B) for reading, wherein the composite dielectric gate photosensitive capacitor (A) and the composite dielectric gate MOSFET (B) are formed on the same P-type semiconductor substrate (100); The active area of ​​the P-type semiconductor substrate (100) of the composite dielectric gate MOSFET is in an L-shaped or U-shaped structure.

2. The composite dielectric grating photosensitive detection unit according to claim 1, characterized in that: The composite dielectric gate photosensitive capacitor (A) and the composite dielectric gate MOSFET (B) share a composite dielectric gate (200); The composite dielectric gate (200) comprises, from bottom to top, a bottom dielectric layer (204), a floating gate (203), a top dielectric layer (202) and a control gate (201).

3. The composite dielectric grating photosensitive detection unit according to claim 1, characterized in that: A second isolation structure (300) is provided between the composite dielectric gate photosensitive capacitor (A) and the composite dielectric gate MOSFET (B).

4. The composite dielectric grating photosensitive detection unit according to claim 1, characterized in that: When a plurality of the composite dielectric grating photosensitive detection units are arranged, a first isolation structure (400) is provided between adjacent units; The first isolation structure penetrates the P-type semiconductor substrate (100) to form a through-type substrate (101).

5. The composite dielectric grating photosensitive detection unit according to claim 4, characterized in that: The first isolation structure (400) comprises a first isolation structure dielectric layer (401) and a first isolation structure gate (402), wherein the first isolation structure dielectric layer (401) wraps the first isolation structure gate (402).

6. The composite dielectric grating photosensitive detection unit according to claim 1, characterized in that: A conductive layer (500) is provided below the P-type semiconductor substrate (100) for transmitting substrate voltage.

7. The composite dielectric grating photosensitive detection unit according to claim 6, characterized in that: The conductive layer (500) is doped P-type single crystal silicon or polycrystalline silicon, or intrinsic single crystal silicon or polycrystalline silicon.

8. The composite dielectric grating photosensitive detection unit according to claim 6 or 7, characterized in that: Disposing a high dielectric constant layer (600) below the conductive layer (500); The high dielectric constant layer (600) has the property of forming hole accumulation on the upper surface of the conductive layer (500).

9. A composite dielectric grating photosensitive detector, characterized in that: It comprises a plurality of composite dielectric grating photosensitive detection units as described in any one of claims 1 to 8, wherein the regularly arranged composite dielectric grating photosensitive detection units are regularly arranged.

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