A CCD and its control method for suppressing horizontal area charge signal backflow to vertical area

Abstract

The present invention discloses a CCD for suppressing the backflow of charge signals in the horizontal region to the vertical region and a control method thereof. The CCD comprises a vertical region having a vertical region receiving phase, a horizontal region formed on a side of the vertical region adjacent to the vertical region receiving phase and capable of unidirectionally receiving the charge signals of the vertical region receiving phase, and a blocking barrier structure formed on a side of the horizontal region adjacent to the vertical region and blocking the charge signals in the horizontal region from flowing back to the vertical region, thereby preventing the charge signals transferred to the horizontal region from flowing back to the vertical region across the blocking barrier structure, thereby achieving high-quality imaging of the CCD.

Description

Technical Field

[0001] The present invention relates to the technical field of image sensors, and in particular to a CCD and a control method thereof for suppressing the backflow of charge signals in a horizontal region to a vertical region. Background Art

[0002] When the incident light shines on the vertical area of ​​the CCD, a charge signal will be generated in the vertical area. The charge signal is transferred to the horizontal area under the action of the vertical area driving pulse voltage of the peripheral circuit. The charge signal entering the horizontal area enters the output amplifier under the action of the horizontal area driving pulse voltage of the peripheral circuit. The charge signal is converted into a voltage signal and finally sampled and read out by the peripheral circuit.

[0003] like Figure 1 As shown in FIG. 1 , a schematic diagram of the structure of the vertical transfer region 101 and the horizontal transfer region 102 of the existing CCD is shown. A first channel resistor 103 is formed between the vertical transfer region 101 and the horizontal transfer region 102. A gap is formed on the first channel resistor 103 at a position corresponding to the horizontal connecting phase to form a charge transfer channel 104. The charge transfer channel 104, the vertical connecting phase, and the horizontal connecting phase have uniformly distributed doping concentrations (e.g., Figure 2 As shown), under the driving voltage of the peripheral circuit, the potential formed by the charge transfer channel 104, the vertical connecting phase and the horizontal connecting phase is as follows Figure 3 As shown, the potential of the vertical transfer phase is higher than that of the horizontal transfer phase, so that the charge signal entering the horizontal transfer area will flow back into the vertical transfer area during the transfer. The appearance is that the dark lines in the vertical transfer area adjacent to the horizontal transfer area will light up, that is, there are charge signals, and the closer the vertical transfer area is to the horizontal transfer area, the more charge signals are collected, which in turn affects the high-quality imaging of the CCD. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a CCD and a control method thereof for suppressing the horizontal area charge signal from flowing back to the vertical area, so as to solve the problem in the prior art that the charge signal in the horizontal area taking over phase flows back to the vertical area taking over phase when the horizontal area taking over phase and the vertical area taking over phase are directly connected.

[0005] To achieve the above-mentioned purpose, the first aspect of the present invention provides a CCD that suppresses the horizontal region charge signal from flowing back to the vertical region, including a vertical region having a vertical region taking-over phase and a horizontal region formed on the side of the vertical region adjacent to the vertical region taking-over phase and capable of unidirectionally receiving the vertical region taking-over phase charge signal and a blocking barrier structure formed on the side of the horizontal region adjacent to the vertical region and blocking the horizontal region charge signal from flowing back to the vertical region.

[0006] Furthermore, the vertical region includes several vertical region transfer phases arranged in sequence along the first direction, and the vertical region transfer phase located at the end of the first direction forms the vertical region receiving phase. The charge signal is transferred to the horizontal region in sequence along the first direction through the vertical region transfer phase and the vertical region receiving phase and through the blocking barrier structure.

[0007] Furthermore, the horizontal region includes a plurality of horizontal transfer structures arranged in sequence along a second direction perpendicular to the first direction, and the blocking barrier structure is correspondingly formed on a side of each horizontal transfer structure adjacent to the vertical region transfer phase. The charge signal is transferred to each horizontal transfer structure through the blocking barrier structure and is transferred and read out in sequence along the second direction.

[0008] Furthermore, the horizontal transfer structure includes a horizontal area receiving phase and at least one horizontal area transfer phase formed along the second direction next to the horizontal area receiving phase. The upper end of the horizontal area receiving phase protrudes toward the vertical area receiving phase so that the horizontal area receiving phase has a receiving portion that is higher than the horizontal area transfer phase, and the blocking barrier structure is formed in the receiving portion.

[0009] Furthermore, the blocking barrier structure includes blocking barriers formed in a one-to-one correspondence within the receiving portion.

[0010] Furthermore, the blocking barrier is formed by performing at least one doping injection in the receiving portion, and the doping concentration of the blocking barrier is lower than the doping concentration of the area outside the receiving portion on the vertical region receiving phase and the horizontal region receiving phase.

[0011] Furthermore, the doping concentration of the blocking barrier is 1e15cm -3 ~1e16cm -3 .

[0012] Furthermore, it also includes a trench resistance structure formed between the vertical area and the horizontal area; the upper end of the horizontal area transfer phase is lower than the receiving portion to form a trench resistance area beside the receiving portion, and the trench resistance structure includes trench resistances formed one-to-one in the trench resistance area.

[0013] A second aspect of the present invention provides a control method for suppressing the backflow of charge signals from the horizontal region to the CCD in the vertical region, comprising the CCD for suppressing the backflow of charge signals from the horizontal region to the vertical region as described above and a driving circuit for generating a driving voltage, comprising the following steps:

[0014] Controlling the driving circuit to generate a first driving voltage and a second driving voltage to act on the vertical region and the horizontal region respectively, so that the potential of the vertical region receiving phase is lower than the potential of the blocking barrier and the potential of the horizontal region receiving phase is higher than the potential of the blocking barrier, and the charge signal of the vertical region receiving phase is vertically transferred downward across the blocking barrier to the horizontal region receiving phase;

[0015] The second driving voltage continuously acts on the horizontal area, and the charge signal transferred to the receiving phase of the horizontal area continues to transfer along the second direction in the horizontal area under the action of the second driving voltage. At the same time, the driving circuit is controlled to generate a third driving voltage to act on the vertical area, so that the potential of the receiving phase of the vertical area is higher than the potential of the blocking barrier, thereby suppressing the backflow of the charge signal in the receiving phase of the horizontal area.

[0016] The present invention forms a region with a doping concentration lower than that of the vertical region receiving phase and the horizontal region receiving phase at the corresponding position of the horizontal region receiving phase by doping, so that a concentration difference is formed between the region and the vertical region receiving phase and the horizontal region receiving phase. When a driving voltage is applied to the vertical region and the horizontal region, an electric potential difference can be formed between the vertical region receiving phase and the horizontal region receiving phase, thereby forming a blocking potential barrier, which inhibits the charge signal that has entered the horizontal region from crossing the blocking potential barrier and flowing back to the vertical region, so as to avoid the dark rows of the vertical region adjacent to the horizontal region from lighting up due to the collection of charge signals, thereby improving the imaging quality of the CCD. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the vertical transfer region and the horizontal transfer region of the CCD structure in the prior art.

[0018] Figure 2 for Figure 1 Doping concentration distribution diagram of the vertical connecting phase and the horizontal connecting phase in the AA direction.

[0019] Figure 3 for Figure 1 The potential distribution diagram of the vertical transfer phase and the horizontal transfer phase in the AA direction when the charge signal is transferred along the horizontal transfer region.

[0020] Figure 4 Schematic diagram of the structure of a CCD for suppressing the backflow of charge signals in the horizontal region to the vertical region according to embodiment 1 of the present invention.

[0021] Figure 5 for Figure 4 Schematic diagram of the structure of the medium-level transfer structure.

[0022] Figure 6 for Figure 4 Doping concentration distribution diagram of the vertical region receiving phase, blocking barrier and horizontal region receiving phase in the BB direction.

[0023] Figure 7 for Figure 4 The potential distribution diagram of the vertical region receiving phase, blocking potential barrier and horizontal region receiving phase in the BB direction when the charge signal is transferred from the vertical region receiving phase to the horizontal region receiving phase.

[0024] Figure 8 for Figure 4The potential distribution diagram of the vertical region receiving phase, blocking potential barrier and horizontal region receiving phase in the BB direction when the charge signal is transferred along the horizontal transfer region.

[0025] The meanings of the reference numerals in the accompanying drawings are:

[0026] Vertical transfer region 101, horizontal transfer region 102, first channel resistance 103, charge transfer channel 104;

[0027] Vertical region 2, vertical region transfer phase 21, vertical region receiving phase 22, horizontal region 3, horizontal transfer structure 3a, horizontal region transfer phase 31, horizontal region receiving phase 32, receiving portion 32a, blocking barrier 41, and channel resistance 51. DETAILED DESCRIPTION

[0028] The following is further described in detail through specific implementation methods:

[0029] Example 1

[0030] like Figure 4 and Figure 5 FIG. 1 is a schematic diagram of a CCD structure for suppressing the backflow of charge signals from the horizontal region 3 to the vertical region 2 according to this embodiment. This embodiment includes a vertical region 2 and a horizontal region 3 arranged sequentially, a blocking barrier structure formed on the horizontal region 3 corresponding to one side of the vertical region 2, and a trench resistance structure formed on the vertical region 2 and the horizontal region 3 and corresponding to the side of the blocking barrier structure. Under the control of a driving circuit, the charge signal is transferred within the vertical region 2 along a first direction and unidirectionally across the blocking barrier structure to the horizontal region 3. Subsequently, under the control of the driving circuit, the charge signal entering the horizontal region 3 is transferred within the horizontal region 3 along a second direction perpendicular to the first direction and read out by a subsequent amplification circuit. The trench resistance structure is used to block the charge signal from the vertical region 2, so that the charge signal from the vertical region 2 can only be transferred downward to the horizontal region 3 through the blocking barrier structure. At the same time, due to the presence of the blocking barrier structure, the charge signal that has entered the horizontal region 3 will be blocked on one side of the horizontal region 3 and will not flow back to the vertical region 2, thereby achieving the purpose of suppressing the backflow of the charge signal. In this embodiment, the first direction is a direction in which the charge signal is vertically transferred within the CCD, and the second direction is a direction in which the charge signal is horizontally transferred within the CCD.

[0031] The vertical region 2 includes a plurality of vertical region transfer phases 21 arranged sequentially along a first direction. The vertical region transfer phases 21 are configured to sequentially transfer charge signals along the first direction. Among the plurality of vertical region transfer phases 21, the vertical region transfer phase 21 located at the end of the first direction is adjacent to the horizontal region 3 to form a vertical region receiving phase 22. The vertical region receiving phase 22 is configured to sequentially transfer the charge signals transferred from the vertical region transfer phase 21 to the horizontal region 3 via a blocking barrier structure.

[0032] The horizontal region 3 includes a plurality of horizontal transfer structures 3a formed sequentially along the second direction below the vertical region receiving phase 22. The horizontal transfer structures 3a are used to receive the charge signal transferred from the vertical region 2 and sequentially transfer the received charge signal along the second direction to the subsequent amplification circuit under the drive of a corresponding driving voltage. The horizontal transfer structure 3a includes a horizontal region receiving phase 32 and at least one horizontal region transfer phase 31 formed along the second direction beside the horizontal region receiving phase 32 (including a first side along the second direction and a second side along the second direction). The horizontal region receiving phase 32 is used to receive the charge signal transferred from the vertical region 2 under the drive of a corresponding driving voltage. The horizontal region transfer phase 31 is used to sequentially transfer the charge signal received by the horizontal region receiving phase 32 along the second direction to the next horizontal transfer structure 3a under the drive of the corresponding driving voltage, and then output it through the subsequent amplification circuit. In this embodiment, the horizontal transfer structure 3a is a three-phase transfer structure, including a horizontal area receiving phase 32 and a first horizontal area transfer phase 31 and a second horizontal area transfer phase 31 respectively arranged on both sides of the horizontal area receiving phase 32.

[0033] In this embodiment, the upper end of the horizontal region receiving phase 32 protrudes toward the vertical region receiving phase 22 so that the horizontal region receiving phase 32 has a receiving portion 32a that is higher than the horizontal region transfer phase 31, and the receiving portion 32a is used to provide an impurity-doped region for forming a blocking barrier structure, and the receiving portion 32a is connected to the vertical region receiving phase 22 so that the formed blocking barrier structure can contact the vertical region receiving phase 22 and thus receive the charge signal; the upper end of the horizontal region transfer phase 31 is lower than the upper end of the horizontal region transfer phase 31 (that is, lower than the receiving portion 32a) to form a trench resistance 51 region next to the receiving portion 32a, and the trench resistance 51 region is used to provide a trench resistance structure.

[0034] The blocking barrier structure includes blocking barriers 41 formed in a one-to-one correspondence within the receiving portion 32a. The blocking barriers 41 are formed by performing at least one doping injection on the receiving portion 32a. The doping concentration of the blocking barriers 41 is lower than the doping concentration of the vertical receiving phase 22 and the horizontal receiving phase 32 corresponding to the area outside the receiving portion 32a (the doping concentration distribution of the vertical receiving phase 22, the blocking barriers 41 and the horizontal receiving phase 32 is shown in FIG. Figure 6As shown in FIG, a doping concentration difference is formed between the connecting portion 32a (i.e., the region where the blocking potential barrier 41 is formed) and the vertical region connecting phase 22 and the horizontal region connecting phase 32. Then, under the driving voltage of the peripheral driving circuit, an electric potential difference is formed between the connecting portion 32a and the vertical region connecting phase 22 and the horizontal region connecting phase 32, thereby forming the blocking potential barrier 41 to inhibit the charge signal that has entered the horizontal region connecting phase 32 from flowing back to the vertical region connecting phase 22. In this embodiment, the doping concentration of the blocking potential barrier 41 is 1e15cm -3 ~1e16cm -3 .

[0035] The trench resistance structure includes trench resistances 51 formed one-to-one in the trench resistance 51 area, which are used to block the charge signal from the vertical area receiving phase 22, so that the charge signal from the vertical area receiving phase 22 can only be transferred downward to the horizontal area receiving phase 32 through the corresponding blocking barrier 41.

[0036] When this embodiment is working, first, the control driving circuit generates a first driving voltage and a second driving voltage to act on the vertical area 2 and the horizontal area 3 respectively, so that the potential of the vertical area receiving phase 22 is lower than the potential of the blocking barrier 41 and the potential of the horizontal area receiving phase 32 is higher than the potential of the blocking barrier 41 (the potential distribution is shown in FIG. Figure 7 As shown), at this time, the charge signal of the vertical area transfer phase 21 is sequentially transferred downward to the vertical area receiving phase 22 under the action of the first driving voltage and transferred to the horizontal area receiving phase 32 across the blocking barrier 41. Then, the second driving voltage is continuously applied to the horizontal area 3, and the charge signal transferred to the horizontal area receiving phase 32 continues to transfer along the second direction within the horizontal area 3 under the action of the second driving voltage. Finally, the control driving circuit generates a third driving voltage applied to the vertical area 2, so that the potential of the vertical area receiving phase 22 is higher than the potential of the blocking barrier 41 (the potential distribution is shown in FIG. Figure 8 As shown), the charge signal backflow in the horizontal region receiving phase 32 is suppressed.

[0037] The present embodiment provides a CCD that suppresses the charge signal of the horizontal region 3 from flowing back to the vertical region 2. The CCD forms a region with a concentration lower than that of the vertical region taking over phase 22 and the horizontal region taking over phase 32 in the upper end of the horizontal region taking over phase 32 by doping, so as to form a concentration difference between the region and the vertical region taking over phase 22 and the horizontal region taking over phase 32. Under the action of the driving voltage, an electric potential difference can be formed between the vertical region taking over phase 22 and the horizontal region taking over phase 32, thereby forming a blocking barrier 41, which suppresses the charge signal that has entered the horizontal region 3 from crossing the blocking barrier 41 and flowing back to the vertical region 2, so as to avoid the dark rows of the vertical region 2 adjacent to the horizontal region 3 from lighting up due to the collection of charge signals, thereby improving the imaging quality of the CCD.

[0038] Example 2

[0039] A control method for a CCD that suppresses charge signals from the horizontal region 3 from flowing back to the vertical region 2 in this embodiment is used to control the CCD of embodiment 1 to suppress charge signals from the horizontal region 3 from flowing back to the vertical region 2. This embodiment includes a CCD that suppresses charge signals from the horizontal region 3 from flowing back to the vertical region 2, having the same or similar structure and function as embodiment 1, and a drive circuit for generating a drive voltage. Specifically, this embodiment includes the following steps:

[0040] S201: Controlling the driving circuit to generate a first driving voltage and a second driving voltage to act on the vertical region 2 and the horizontal region 3, respectively, so that the charge signal is transferred downward from the vertical region 2 across the blocking barrier 41 to the horizontal region 3. Specifically, when the first driving voltage and the second driving voltage are respectively applied to the vertical region transfer phase 21 and the horizontal region 3 driving phase, the potential of the vertical region receiving phase 22 is lower than the potential of the blocking barrier 41, while the potential of the horizontal region receiving phase 32 is higher than the potential of the blocking barrier 41. Under the action of the first driving voltage, the charge signal is sequentially transferred downward along a first direction within the vertical region transfer phase 21 to the vertical region receiving phase 22, and then continues vertically downward across the blocking barrier 41 to be transferred to the horizontal region receiving phase 32.

[0041] S202: When the charge signal is transferred to the horizontal region receiving phase 32, under the continued application of the second driving voltage, the charge signal is sequentially transferred from the horizontal region receiving phase 32 to the horizontal region transfer phase 31 along the second direction, and then continues to transfer along the second direction to the next horizontal region transfer phase 31 until it is read out by the subsequent amplification circuit. Simultaneously, the control driving circuit generates a third driving voltage to apply to the vertical region 2, causing the potential of the vertical region receiving phase 22 to be higher than the potential of the blocking barrier 41, thereby suppressing the charge signal in the horizontal region receiving phase 32 from flowing back into the vertical region receiving phase 22, thereby achieving high-quality imaging of the CCD.

[0042] The control method of the CCD of this embodiment for suppressing the charge signal of the horizontal area 3 from flowing back to the vertical area 2 applies corresponding driving voltages to the vertical area 2 and the horizontal area 3 so that the charge signal in the vertical area 2 is transferred to the horizontal area 3 in sequence along a first direction. Due to the existence of the potential difference, the charge signal that has been transferred to the horizontal area 3 will not flow back to the vertical area 2, so as to avoid the dark lines of the vertical area 2 adjacent to the horizontal area 3 from lighting up due to the collection of charge signals, thereby improving the imaging quality of the CCD.

Claims

1. A CCD for suppressing the backflow of charge signals from the horizontal region to the vertical region, comprising a vertical region having a vertical region receiving phase, characterized in that: The device further comprises a horizontal region formed on a side of the vertical region adjacent to the vertical region receiving phase and capable of unidirectionally receiving the charge signal of the vertical region receiving phase, and a blocking barrier structure formed on a side of the horizontal region adjacent to the vertical region and blocking the charge signal of the horizontal region from flowing back to the vertical region; The horizontal region includes a plurality of horizontal transfer structures sequentially arranged along a second direction perpendicular to the first direction; the horizontal transfer structure includes a horizontal region receiving phase and at least one horizontal region transfer phase formed along the second direction adjacent to the horizontal region receiving phase, the upper end of the horizontal region receiving phase protruding toward the vertical region receiving phase so that the horizontal region receiving phase has a receiving portion higher than the horizontal region transfer phase, the blocking barrier structure is formed in the receiving portion; the blocking barrier structure includes blocking barriers formed one-to-one in the receiving portion; The blocking barrier is formed by performing at least one doping injection in the receiving portion, and the doping concentration of the blocking barrier is lower than the doping concentration of the region outside the receiving portion on the vertical region receiving phase and the horizontal region receiving phase.

2. The CCD for suppressing the backflow of charge signals from the horizontal region to the vertical region according to claim 1, characterized in that: The vertical region includes several vertical region transfer phases arranged in sequence along the first direction. The vertical region transfer phase located at the end of the first direction forms the vertical region receiving phase. The charge signal is transferred to the horizontal region in sequence along the first direction through the vertical region transfer phase and the vertical region receiving phase and through the blocking barrier structure.

3. The CCD for suppressing the backflow of charge signals from the horizontal region to the vertical region according to claim 2, characterized in that: The blocking barrier structure is correspondingly formed on a side of each horizontal transfer structure adjacent to the vertical region transfer phase. The charge signal is transferred to each horizontal transfer structure through the blocking barrier structure and sequentially transferred and read out along the second direction.

4. The CCD for suppressing the backflow of charge signals from the horizontal region to the vertical region according to claim 1, characterized in that: The doping concentration of the blocking barrier is 1e15cm -3 ~1e16cm -3 .

5. The CCD for suppressing the backflow of charge signals from the horizontal region to the vertical region according to claim 1, characterized in that: It also includes a trench resistance structure formed between the vertical area and the horizontal area; the upper end of the horizontal area transfer phase is lower than the receiving portion to form a trench resistance area beside the receiving portion, and the trench resistance structure includes trench resistances formed one-to-one in the trench resistance area.

6. A control method for a CCD for suppressing the backflow of charge signals from the horizontal region to the vertical region, comprising the CCD for suppressing the backflow of charge signals from the horizontal region to the vertical region according to any one of claims 1 to 5 and a driving circuit for generating a driving voltage, wherein: The following steps are involved: Controlling the driving circuit to generate a first driving voltage and a second driving voltage to act on the vertical region and the horizontal region respectively, so that the potential of the vertical region receiving phase is lower than the potential of the blocking barrier and the potential of the horizontal region receiving phase is higher than the potential of the blocking barrier, and the charge signal of the vertical region receiving phase is vertically transferred downward across the blocking barrier to the horizontal region receiving phase; The second driving voltage continuously acts on the horizontal area, and the charge signal transferred to the receiving phase of the horizontal area continues to transfer along the second direction in the horizontal area under the action of the second driving voltage. At the same time, the driving circuit is controlled to generate a third driving voltage to act on the vertical area, so that the potential of the receiving phase of the vertical area is higher than the potential of the blocking barrier, thereby suppressing the backflow of the charge signal in the receiving phase of the horizontal area.

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