JP5768073B2 - Solid-state image sensor manufacturing method and solid-state image sensor - Google Patents

Description

  The present invention relates to a solid-state imaging device and a manufacturing method thereof.

  As described in Patent Documents 1 to 7, generally, when a semiconductor device having a surface area larger than one exposure area in an exposure apparatus is formed on a semiconductor substrate, a photo on the semiconductor substrate is formed. Divided exposure is performed on the resist. That is, the photoresist is divided into a plurality of exposure areas, and an exposure process is performed on each of the plurality of exposure areas.

JP-A-6-124869 JP-A-11-220116 JP-A-9-298155 Japanese Patent Application Laid-Open No. 9-190962 JP-A-5-62874 JP 2003-5346 A JP-A-5-6849

  In the split exposure process, the mask pattern used to expose one exposure area and the other exposure area are exposed in two adjacent exposure areas in the photoresist, depending on the positioning accuracy of the photomask with respect to the photoresist. In some cases, a positional deviation may occur between the mask pattern and the mask pattern used. As a result, in the photoresist after patterning, the resist pattern may be misaligned between two adjacent exposure regions. Therefore, depending on the position of the boundary line of the divided exposure, where the resist pattern is misaligned, the characteristics of the semiconductor device may be greatly deteriorated, and how to set the position of the boundary line is important. It is a serious problem. In particular, in a solid-state imaging device including a plurality of pixel portions, the plurality of pixel portions are arranged as densely as possible for miniaturization of the element, and thus the positional deviation of the resist pattern gives the characteristics of the pixel portion. The influence is very great, and how to set the position of the boundary line of the divided exposure is very important.

  On the other hand, when a solid-state imaging device is manufactured by using a divided exposure process, the resist pattern may be formed between two adjacent exposure regions in the photoresist due to a mask pattern design error or an exposure condition setting error. Dimensions may vary. As a result, in the semiconductor chip, the dimension of the formed element may be different between the two regions sandwiching the boundary line of the divided exposure. In the photoresist, even in the same exposure area, the resist pattern near the boundary line with another exposure area and the resist pattern near the center far from the boundary line have different dimensions. Sometimes. As a result, in the semiconductor chip, the element size in the vicinity of the boundary line of the exposure region may differ from the element dimension in a position away from the boundary line.

  As described above, the dimensions of the resist pattern and the element may change based on the boundary line of the divided exposure. When performing the dimension inspection of the resist pattern or the element dimension, the boundary line in the divided exposure process is used. It is necessary to know the position where is set.

  Accordingly, the present invention has been made in view of the above-described problems, and a first object thereof is to provide a divided exposure technique capable of suppressing deterioration in performance of a solid-state imaging device.

  A second object is to provide a technique capable of easily grasping the position of the exposure boundary line in the divided exposure process.

  In the method for manufacturing a solid-state imaging device according to one embodiment of the present invention, first, a semiconductor substrate is prepared. Then, a photoresist is formed on the semiconductor substrate via a protective film. Next, the photoresist is exposed using a photomask. At this time, the photoresist is divided and exposed. That is, the photoresist is divided into a plurality of exposure areas, and an exposure process is individually performed for each of the plurality of exposure areas. When the photoresist is divided and exposed, the boundary line is located at least on the region where the active region in which the pixel portion is formed is defined in the semiconductor substrate. Next, the exposed photoresist is developed, and the photoresist is patterned. Thereafter, the protective film exposed from the patterned photoresist is removed, and then the photoresist is removed. Next, the semiconductor substrate exposed from the protective film is oxidized to form an element isolation structure on the semiconductor substrate. Thus, an active region in which the pixel portion is formed is defined in the semiconductor substrate by the element isolation structure.

  A solid-state imaging device according to an embodiment of the present invention includes a semiconductor substrate in which an active region is partitioned by an element isolation structure, and a pixel portion formed in the active region. The active region has a plurality of partial active regions each having a plurality of impurity regions. The plurality of partial active regions include partial active regions having a shape shifted in one direction when viewed from the top so that a step is formed at the peripheral edge when viewed from the top.

  According to the method for manufacturing a solid-state imaging device of one embodiment of the present invention, when a photoresist used for partitioning an active region where a pixel portion is formed on a semiconductor substrate is divided and exposed, the boundary line is Since the active region is located at least on the region where the active region is defined in the semiconductor substrate, the element is compared with the case where the boundary line is located only on the region where the element isolation structure is formed on the semiconductor substrate. The part in which the dimensional change in the separation structure occurs can be reduced. When the dimensional change occurs in the element isolation structure, the electrical insulation between the elements deteriorates. Therefore, the performance deterioration of the solid-state imaging element can be suppressed by reducing the portion where the dimensional change occurs in the element isolation structure.

  Further, according to the solid-state imaging device of one embodiment of the present invention, the active region in which the pixel portion is formed has a shape shifted in one direction on the top view so that a step is formed at the periphery on the top view. Since the partial active region is included, when the active region is partitioned on the semiconductor substrate, the step is detected when the photoresist is divided and exposed with the step position of the partial active region as a boundary. Thus, the position of the boundary line of the divided exposure can be easily grasped.

It is a figure which shows the structure of the solid-state image sensor which concerns on embodiment of this invention. It is a figure which shows the circuit structure of the pixel part which concerns on embodiment of this invention. It is a top view which shows the structure of the pixel part which concerns on embodiment of this invention. It is a top view which shows the structure of the pixel part which concerns on embodiment of this invention. It is sectional drawing which shows the structure of the pixel part which concerns on embodiment of this invention. It is a flowchart which shows the manufacturing method of the solid-state image sensor which concerns on embodiment of this invention. It is a figure which shows the division | segmentation exposure process in embodiment of this invention. It is a flowchart which shows the manufacturing method of the element isolation structure which concerns on embodiment of this invention. It is a top view which shows the manufacturing process of the element isolation structure which concerns on embodiment of this invention. It is a top view which shows the manufacturing process of the element isolation structure which concerns on embodiment of this invention. It is a top view which shows the manufacturing process of the element isolation structure which concerns on embodiment of this invention. It is a flowchart which shows the manufacturing method of the gate structure which concerns on embodiment of this invention. It is a top view which shows the manufacturing process of the gate structure which concerns on embodiment of this invention. It is a top view which shows the manufacturing process of the gate structure which concerns on embodiment of this invention. It is a top view which shows the manufacturing process of the gate structure which concerns on embodiment of this invention. It is a top view which shows the manufacturing process of the gate structure which concerns on embodiment of this invention. It is a flowchart which shows the manufacturing method of the impurity region which concerns on embodiment of this invention. It is a top view which shows the manufacturing process of the impurity region which concerns on embodiment of this invention. It is a top view which shows the manufacturing process of the impurity region which concerns on embodiment of this invention. It is a top view which shows the manufacturing process of the impurity region which concerns on embodiment of this invention. It is a flowchart which shows the manufacturing method of the contact plug and via plug which concern on embodiment of this invention. It is a top view which shows the manufacturing process of the contact plug which concerns on embodiment of this invention. It is a flowchart which shows the manufacturing method of the wiring which concerns on embodiment of this invention. It is a top view which shows the manufacturing process of the wiring which concerns on embodiment of this invention. It is a top view which shows the manufacturing process of the wiring which concerns on embodiment of this invention. It is a top view which shows the manufacturing process of the wiring which concerns on embodiment of this invention. It is a top view which shows a mode that the variation | change_quantity of the surface area of a partial active region changes with the position of the boundary line of division | segmentation exposure. It is a top view for demonstrating that a yield falls by the change of the position of the boundary line of division | segmentation exposure. It is a top view which shows the modification of the manufacturing process of the impurity region which concerns on embodiment of this invention.

  FIG. 1 is a diagram showing a configuration of a solid-state imaging device according to an embodiment of the present invention. The solid-state imaging device according to the present embodiment is a CMOS image sensor, and as shown in FIG. 1, a pixel array unit 1, readout circuits 2 and 3, an output circuit 4, a row selection circuit 5, And a control circuit 6.

  In the pixel array unit 1, a plurality of pixel units 10 are arranged in a matrix. In the drawing, the X-axis direction indicates the row direction in which the pixel portions 10 are arranged, and the Y-axis direction perpendicular to the X-axis direction indicates the column direction in which the pixel portions 10 are arranged. Each of the plurality of pixel units 10 generates a signal corresponding to the intensity of the irradiated light. The row selection circuit 5 selects a plurality of pixel units 10 in units of rows. The pixel unit 10 selected by the row selection circuit 5 outputs the generated signal to an output line OL described later. The readout circuits 2 and 3 are arranged to face each other in the Y-axis direction so as to sandwich the pixel array unit 1 therebetween. Each of the readout circuits 2 and 3 reads out a signal output from the pixel unit 10 to the output line OL and outputs the signal to the output circuit 4. The readout circuit 2 reads out the signal of the half pixel unit 10 on the readout circuit 2 side among the plurality of pixel units 10, and the readout circuit 3 receives the signal of the remaining half pixel unit 10 on the readout circuit 3 side. read out. The output circuit 4 outputs the signal of the pixel unit 10 read by the readout circuits 2 and 3 to the outside of the solid-state imaging device. The control circuit 6 comprehensively manages the operation of the entire solid-state image sensor and controls the operation of other components of the solid-state image sensor.

  FIG. 2 is a diagram illustrating a circuit configuration of each pixel unit 10. As shown in FIG. 2, the pixel unit 10 includes a photodiode PD that performs photoelectric conversion, a transfer transistor TX that transfers charges generated in the photodiode PD, and a floating diffusion that stores charges transferred from the transfer transistor TX. FD, amplification transistor AMI for amplifying the potential of floating diffusion FD, and selection for selecting whether or not to output the potential amplified by amplification transistor AMI to output line OL connected to one of read circuits 2 and 3 A transistor SEL and a reset transistor RST that initializes the cathode of the photodiode PD and the potential of the floating diffusion FD to a predetermined potential are provided. Each of the transfer transistor TX, the reset transistor RST, the amplification transistor AMI, and the selection transistor SEL is, for example, an NMOS transistor.

  A ground potential GND, which is a negative power supply potential, is applied to the anode of the photodiode PD, and its cathode is connected to the source of the transfer transistor TX. The floating diffusion FD is connected to the drain of the transfer transistor TX, the source of the reset transistor RST, and the gate of the amplification transistor AMI. The positive power supply potential VCC is applied to the drain of the reset transistor RST and the drain of the amplification transistor AMI. The source of the amplification transistor AMI is connected to the drain of the selection transistor SEL. The source of the selection transistor SEL is connected to the output line OL connected to one of the read circuits 2 and 3 described above.

  Next, the operation of the pixel unit 10 will be described. First, a predetermined potential is applied to the gates of the transfer transistor TX and the reset transistor RST, and both the transfer transistor TX and the reset transistor RST are turned on. Then, the charge remaining in the photodiode PD and the charge accumulated in the floating diffusion FD flow toward the positive power supply potential VCC, and the charges in the photodiode PD and the floating diffusion FD are initialized. Thereafter, the reset transistor RST is turned off.

  Next, incident light is applied to the PN junction of the photodiode PD, and photoelectric conversion occurs in the photodiode PD. As a result, charges are generated in the photodiode PD. All of this charge is transferred to the floating diffusion FD by the transfer transistor TX. The floating diffusion FD accumulates the transferred charges. As a result, the potential of the floating diffusion FD changes.

  Next, when the selection transistor SEL is turned on, the changed potential of the floating diffusion FD is amplified by the amplification transistor AMI, and then output to the output line OL. Then, one of the read circuits 2 and 3 reads the potential of the output line OL.

  3 and 4 are top views showing the structure of the pixel unit 10. FIG. 5 is a view showing a cross-sectional structure taken along line AA in FIG. In FIG. 3, only the gate electrode 20 and the contact plug 40 are shown for the structure above the active region AR for convenience of explanation.

As shown in FIGS. 3 to 5, a P ⁻ type well region 2 is formed in the upper surface of the N type semiconductor substrate 1. An element isolation structure 3 that partitions the active region AR in the semiconductor substrate 1 is formed on the well region 2. The plurality of pixel portions 10 are formed in the active region AR. The element isolation structure 3 is made of, for example, a silicon oxide film.

In the upper surface of the well region 2, a P ⁺ -type impurity region 17 to which a ground potential GND is applied, an N ⁻ -type impurity region 11, an N ⁺ -type impurity region 12, and source / drain regions 13 to 16 are They are formed apart from each other. Each of the source / drain regions 13 to 16 is an N ⁺ type impurity region.

The N ⁻ -type impurity region 11 functions as the cathode of the photodiode PD and the source of the transfer transistor TX. The well region 2 forming a PN junction with the N ⁻ type impurity region 11 functions as an anode of the photodiode PD. The N ⁺ -type impurity region 12 functions as the floating diffusion FD and the drain of the transfer transistor TX. The source / drain region 13 functions as a source of the reset transistor RST. The source / drain region 14 functions as the drain of the reset transistor RST and the drain of the amplification transistor AMI. The source / drain region 15 functions as the source of the amplification transistor AMI and the drain of the selection transistor SEL. The source / drain region 16 functions as the source of the selection transistor SEL.

On the well region 2 between the N ⁻ -type impurity region 11 and the N ⁺ -type impurity region 12, the gate electrode 20 of the transfer transistor TX is formed via the gate insulating film 21. A gate electrode 20 of the reset transistor RST is formed on the well region 2 between the source / drain regions 13 and 14 via a gate insulating film 21. A gate electrode 20 of the amplification transistor AMI is formed on the well region 2 between the source / drain regions 14 and 15 via a gate insulating film 21. A gate electrode 20 of the select transistor SEL is formed on the well region 2 between the source / drain regions 15 and 16 via a gate insulating film 21. The gate electrode 20 is made of, for example, polysilicon, and the gate insulating film 21 is made of, for example, a silicon oxide film.

Thus, the active region AR in which the pixel portion 10 is formed includes the partial active region AR1 in which the N ⁻ -type impurity region 11 is formed, the partial active region AR2 in which the N ⁺ -type impurity region 12 is formed, It has partial active regions AR3 to AR6 in which drain regions 13 to 16 are respectively formed, and a partial active region AR7 in which a P ⁺ -type impurity region 17 is formed. In a top view, the region composed of the partial active regions AR1 and AR2 and the partial active region AR7 are separated by the element isolation structure 3, and the region composed of the partial active regions AR1 and AR2 and the partial active regions AR3 to AR6 are separated from each other. The region consisting of the partial active region AR7 and the region composed of the partial active regions AR3 to AR6 are separated from each other by the element isolation structure 3. The partial active region AR7, the partial active region AR1, and the partial active region AR2 are arranged in this order along the X-axis direction. The partial active regions AR3 to AR6 are arranged in this order along the X-axis direction. The partial active region AR1 and the region composed of the partial active regions AR4 to AR6 are arranged side by side along the Y-axis direction, and the partial active region AR2 and the partial active region AR3 are arranged along the Y-axis direction. Is arranged in.

  As shown in FIG. 3, the shape of the partial active region AR <b> 1 in the top view is a substantially rectangular shape and extends along the X-axis direction. Then, a part of the partial active regions AR1 arranged in the Y-axis direction among the plurality of partial active regions AR1, that is, each of the partial active regions AR1 in a certain column has two long sides facing each other in the Y-axis direction when viewed from above. Approximately half of each of the partial active regions AR2 is slightly shifted in the direction of the arrow on the Y axis. Therefore, a step 90 is generated on each of the two long sides.

  Also, among the plurality of partial active regions AR5, the partial active region AR1 having the step 90 and the partial active region AR5 aligned in the Y-axis direction, that is, the upper surface of the partial active region AR5 belonging to the same column as the partial active region AR1 having the step 90 The visual shape is a quadrilateral having two sides facing each other in the X-axis direction and two sides facing each other in the Y-axis direction, and each of the two sides facing each other in the Y-axis direction side of the partial active region AR4 Is substantially shifted in the direction of the arrow on the Y axis. Therefore, a step 91 is formed on each of the two sides facing each other in the Y-axis direction.

  As described above, the partial active region AR1 belonging to a certain column has a shape shifted in the Y-axis direction in the top view so that a step 90 is formed at the peripheral edge in the top view. The partial active regions AR5 adjacent in the axial direction have a shape shifted in the Y-axis direction in the top view so that a step 91 is formed at the periphery in the top view. As will be described later, these stepped portions 90 and 91 form exposure boundary lines in partial exposure regions AR1 and AR5 in the semiconductor substrate 1 in the divided exposure process when the active region AR is partitioned into the semiconductor substrate 1. This happens because it is placed on the area.

  Of the plurality of partial active regions AR5, the partial active regions AR5 other than the partial active region AR5 having the step 91 have a substantially rectangular shape when viewed from above. Each of the partial active regions AR3, AR4, and AR6 has a substantially rectangular shape when viewed from above, and the partial active region AR7 has a generally rectangular shape that extends along the Y-axis direction when viewed from above. .

  As shown in FIG. 5, an interlayer insulating film 30 is formed on the semiconductor substrate 1 so as to cover the gate insulating film 21 and the gate electrode 20. A plurality of contact plugs 40 penetrating in the thickness direction are formed in the interlayer insulating film 30. One ends of the plurality of contact plugs 40 are in contact with the partial active regions AR2 to AR4, AR6, and AR7, respectively. On the interlayer insulating film 30, a plurality of lower wirings 50 are formed in contact with the plurality of contact plugs 40. An interlayer insulating film 60 is formed on the interlayer insulating film 30 so as to cover the plurality of wirings 50. In the interlayer insulating film 60, a via plug (not shown) penetrating in the thickness direction is formed. The via plug is in contact with a part of the plurality of wirings 50. An upper wiring 80 that contacts the via plug is formed on the interlayer insulating film 60. Each of the interlayer insulating films 30 and 60 is, for example, a silicon oxide film. Each of the contact plug 40, the via plug, and the wirings 50 and 80 is made of, for example, metal.

  As shown in FIG. 4, the upper-layer wiring 80 has a lattice shape when viewed from above, and the partial regions 60a on the plurality of partial active regions AR1 arranged in a matrix in the interlayer insulating film 60 are wirings. Exposed from 80. The wiring 80 has a shape shifted in the Y-axis direction when viewed from above so that a step 92 is formed on the side surface. In the wiring 80, in the partial region 80a aligned in the Y-axis direction with the partial region 60a on the partial active region AR1 having the step 90, approximately half of each side surface facing in the Y-axis direction is slightly shifted in the Y-axis direction. A step 92 is formed on each of both side surfaces of the partial region 80a. As will be described later, this step 92 also occurs because the exposure boundary line is arranged on the partial active regions AR1 and AR5 in the divided exposure process when forming the wiring 80.

  Next, a method for manufacturing the solid-state imaging device according to the present embodiment will be described. FIG. 6 is a flowchart showing a method for manufacturing a solid-state imaging device according to the present embodiment. Below, it demonstrates centering around the manufacturing method of the pixel part 10. FIG.

  As shown in FIG. 6, in step s1, a semiconductor substrate 1 as a semiconductor chip is prepared, and in step s2, a well region 2 is formed in the upper surface of the semiconductor substrate 1.

  Next, in step s 3, the element isolation structure 3 is formed on the well region 2, and the active region AR in which the plurality of pixel portions 10 are formed is partitioned on the semiconductor substrate 1. At this time, the active region in which the readout circuits 2 and 3 and the output circuit 4 are formed is also divided into the semiconductor substrate 1.

  Next, in step s4, a gate structure including the gate insulating film 21 and the gate electrode 20 is formed for various MOS transistors such as the transfer transistor TX, the reset transistor RST, the amplification transistor AMI, and the selection transistor SEL.

Next, in step s5, various elements such as an N ⁻ type impurity region 11, an N ⁺ type impurity region 12, source / drain regions 13 to 16 and a P ⁺ type impurity region 17 are formed in the upper surface of the well region 2 in the active region AR. Impurity regions are formed.

  Next, in step s6, the interlayer insulating film 30 is formed on the semiconductor substrate 1, and in step s7, the contact plug 40 is formed in the interlayer insulating film 30. In step s 8, the lower wiring 50 is formed on the interlayer insulating film 30.

  Next, in step s9, an interlayer insulating film 60 is formed on the interlayer insulating film 30, and in step s10, a via plug is formed in the interlayer insulating film 60. In step s11, an upper wiring 80 is formed on the interlayer insulating film 60.

  In the above-described steps s3 to s5, a photoresist is formed on the semiconductor substrate 1, and an exposure process is performed on the photoresist. One exposure area in the exposure apparatus used in the manufacturing method according to the present embodiment is smaller than the surface area of the solid-state imaging device formed on the semiconductor substrate 1. Therefore, in the present embodiment, as shown in FIG. 7, the photoresist 95 formed on the semiconductor substrate 1 is divided into a plurality of exposure regions ER, for example, three exposure regions ER, and the three exposure regions. An exposure process is individually performed for each ER. Therefore, in the present embodiment, there are two boundary lines DL of the exposure region ER. In this embodiment, by appropriately setting the position of the boundary line DL of the divided exposure, the positional deviation of the two types of mask patterns respectively used when exposing two adjacent exposure regions ER is performed. The resulting deterioration in performance of the solid-state imaging device is suppressed. 7 indicates a region in the semiconductor substrate 1 where the pixel array unit 1 is formed.

  FIG. 8 is a flowchart showing in detail the process of forming the element isolation structure 3 in step s3. FIG. 8 shows a flow when the element isolation structure 3 made of a silicon oxide film is formed by a LOCOS (local oxidation of silicon) method. The element isolation structure 3 may be formed by an STI (shallow trench isolation) method. As shown in FIG. 8, first, in step s301, a protective film 99 having a laminated structure of a silicon oxide film and a silicon nitride film is formed on the semiconductor substrate 1. In step s302, a photoresist 100 is formed on the protective film 99.

Next, in step s303, the photoresist 100 is exposed using a photomask on which a predetermined mask pattern is formed. At this time, divided exposure is performed on the photoresist 100. FIG. 9 is a diagram showing a state of the divided exposure process in step s303. As shown in FIG. 9, the boundary line DL of the divided exposure in the photoresist 100 is located at least on the region PAR where the active region AR is formed in the semiconductor substrate 1. Specifically, the boundary line DL is formed by the N ⁻ type impurity regions 11 and the source / drain regions 15 of the plurality of pixel portions 10 belonging to a certain column in the region PAR in which the active region AR is formed in the semiconductor substrate 1. It extends linearly along the Y-axis direction on the area to be processed.

  As described above, in the present embodiment, the photoresist 100 is divided into three exposure regions ER. Then, an exposure process is individually performed for each of the three exposure regions ER. The mask pattern used at this time is individually prepared for each of the three exposure regions ER. That is, three types of mask patterns are used in the exposure process in step s303.

  When step s303 is executed, in step s304, the exposed photoresist 100 is developed, and the photoresist 100 is patterned. FIG. 10 is a top view showing the photoresist 100 after patterning. As shown in FIG. 10, the patterned photoresist 100 has a shape in which the resist pattern is shifted in the Y-axis direction between the two adjacent exposure regions ER with respect to the boundary line DL. This is because a positional shift in the Y-axis direction has occurred between two types of mask patterns used when exposing two adjacent exposure regions ER in the photoresist 100, respectively. As a result, a step 101 is formed on the side surface of the photoresist 100 with the boundary line DL of the divided exposure as a boundary.

  Next, in step s305, using the photoresist 100 as a mask, the protective film 99 exposed from the photoresist 100 is removed by etching, and then in step s306, the photoresist 100 used for the mask is removed. In step s307, an oxidation process is performed on the obtained structure. At this time, the portion of the upper surface of the semiconductor substrate 1 where the protective film 99 is formed is not oxidized, and only the portion exposed from the protective film 99 is oxidized. As a result, the element isolation structure 3 that partitions the active region AR is formed in the semiconductor substrate 1. Thereafter, in step s308, the protective film 99 used for the mask is removed.

FIG. 11 is a top view showing a structure obtained after execution of step s308. As shown in FIG. 11, in the active region AR, in the partial active region AR <b> 1 where the N ⁻ -type impurity regions 11 of the plurality of pixel units 10 in a certain column are formed, the step 101 formed on the side surface of the photoresist 100. Accordingly, a step 90 is formed on the periphery in the top view. Further, in the active region AR, in the partial active region AR5 where the source / drain regions 15 of the plurality of pixel portions 10 in a certain column are formed, according to the step 101 formed on the side surface of the photoresist 100, as viewed from above. A step 91 is formed on the periphery of the substrate.

  FIG. 12 is a flowchart showing in detail the process of forming the gate structure in step s4. As shown in FIG. 12, first, in step s401, an insulating film to be the gate insulating film 21 is formed on the semiconductor substrate 1, and then in step s402, the conductive film 210 to be the gate electrode 20 is formed on the insulating film. Form.

Next, in step s403, a photoresist 200 is formed on the conductive film 210. In step s404, the photoresist 200 is exposed using a photomask on which a predetermined mask pattern is formed. At this time, a divided exposure process is performed on the photoresist 200. FIG. 13 is a diagram showing a state of the divided exposure process in step s404. As shown in FIG. 13, the boundary line DL of the divided exposure in the photoresist 200 is set at the same position as the boundary line DL of the divided exposure in step s303 described above. That is, in step s404, the boundary line DL is located in the active region AR on a region where the N ⁻ -type impurity regions 11 and the source / drain regions 15 of the plurality of pixel portions 10 in a certain column are formed. In step s404, as in step s303, the photoresist 200 is divided into three exposure areas ER, and an exposure process is performed on each of the three exposure areas ER.

  Next, in step s405, the exposed photoresist 200 is developed, and the photoresist 200 is patterned. FIG. 14 is a top view showing the photoresist 200 after patterning. As shown in FIG. 14, a photoresist 200 having a shape corresponding to the shape of the gate insulating film 21 and the gate electrode 20 is formed on the conductive film 210.

  Next, in step s406, dimension inspection of the resist pattern formed in step s405 is performed. FIG. 15 is a diagram for explaining the dimensional inspection. Here, in this embodiment, since the divided exposure process is performed on the photoresist, the exposure process for one exposure area ER and the exposure process for the other exposure area ER are not performed at the same time. A mask pattern is used. For this reason, due to exposure condition setting errors, mask pattern design errors, etc., in the patterned photoresist, the resist pattern dimensions that should be the same between the two adjacent exposure regions ER are different. There is. As a result, in the semiconductor substrate 1, the element dimensions may differ between the two regions sandwiching the boundary line DL therebetween. For example, when the dimensions of the gate electrode 20 are different between the two regions, the charge transfer capability of the transfer transistor TX and the data reading speed with respect to the pixel unit 10 are different between the two regions. . Furthermore, the coupling capacitance with respect to the gate electrode 20 in the floating diffusion FD is different between the two regions, and as a result, the pixel characteristics are different, resulting in degradation of image quality. Therefore, in the separately exposed photoresist, it is very important to manage the dimensions of the resist patterns in the two adjacent exposure regions ER.

  Therefore, in step s406, as shown in FIG. 15, in the patterned photoresist 200, a resist pattern at a predetermined location 251 in one of the two exposure areas ER sandwiching the boundary line DL therebetween. And the dimension of the resist pattern at a predetermined location 252 in the other exposure area ER are compared, and the two measured dimensions are compared. In step s406, the dimension of the resist pattern corresponding to the shape of the gate electrode 20 is measured in each of two adjacent exposure regions ER. In this embodiment, since there are two boundary lines DL, a resist pattern dimension inspection is performed for each of two exposure regions ER sandwiching one boundary line DL between the two boundary lines DL. The resist pattern is dimensionally inspected for each of the two exposure regions ER sandwiching the other boundary line DL. The predetermined locations 250 and 251 are set as close as possible to the boundary line DL.

  In addition, since the light irradiation condition is not uniform even within one exposure region ER in the photoresist 200, the size of the resist pattern may vary within one exposure region ER of the patterned photoresist 200. . In particular, when an exposure area ER is exposed, the other exposure area ER adjacent to the exposure area ER is covered with a light-shielding film. Therefore, in the exposure area ER, the central portion and the portion close to the boundary line DL The resist patterns that should originally have the same shape may differ greatly.

  Therefore, in step s406, in each exposure region ER of the patterned photoresist 200, the dimensions of the resist pattern at the central predetermined location 250 and the resist pattern at the predetermined location 251 near the boundary line DL are measured. Compare the two measured dimensions. In the present embodiment, since the photoresist 200 is divided into three exposure regions ER, the resist pattern dimension inspection is performed for each of the three exposure regions ER.

  The dimension measurement of the resist pattern in step s406 is performed using, for example, a scanning electron microscope (SEM). At this time, it is necessary to grasp the position of the boundary line DL of the divided exposure in order to specify the predetermined locations 250 to 252 which are measurement locations of the resist pattern. In the present embodiment, the position of the boundary line DL is grasped by detecting the steps 90 and 91 formed in the active region AR using a scanning electron microscope. In the active region AR according to the present embodiment, the steps 90 and 91 are formed according to the position of the boundary line DL of the divided exposure. Therefore, by detecting the steps 90 and 91, the position of the boundary line DL is determined. Easy to grasp. On the active region AR, an insulating film to be the gate insulating film 21 and a conductive film 210 to be the gate electrode 20 are formed. However, since these films are relatively thin, a step of the active region AR is detected using a scanning electron microscope. 90 and 91 can be detected. In order to detect the steps 90 and 91 with a scanning electron microscope, the height of the steps 90 and 91 is preferably 0.03 μm or more. Further, if the steps 90 and 91 are high, the performance of the solid-state imaging device may be deteriorated. Therefore, the height of the steps 90 and 91 is desirably 0.3 μm or less.

  Next, in step s407, based on the result of the dimensional comparison of the resist pattern in step s406, it is determined whether or not the dimensional inspection of the resist pattern formed on the photoresist 200 is acceptable. That is, it is determined whether the patterned photoresist 200 is as designed.

  If it is determined in step s407 that the resist pattern dimension inspection is acceptable, in step s408, using the photoresist 200 as a mask, the conductive film 210 exposed from the photoresist 200 is etched and removed. The lower insulating film is removed by etching. Thereafter, in step s409, the photoresist 200 used for the mask is removed. As a result, as shown in FIG. 16, the transfer transistor TX, the reset transistor RST, the amplification transistor AMI, the gate electrode 20 of the selection transistor SEL, and the gate insulating film 21 are formed.

  Next, in step s410, dimension inspection of the completed gate electrode 20 is performed. As described above, on the semiconductor substrate 1, the dimensions of the gate electrode 20 that should originally be the same may be different between the two regions sandwiching the boundary line DL. Therefore, in step s410, in the region where the gate electrode 20 is formed on the semiconductor substrate 1, one of the two partial regions respectively corresponding to the two exposure regions ER sandwiching the boundary line DL therebetween. The dimension of the gate electrode 20 and the dimension of the gate electrode 20 in the other partial region are measured, and the two measured dimensions are compared. In the present embodiment, since there are two boundary lines DL, two partial areas corresponding respectively to two exposure areas ER sandwiching one boundary line DL between the two boundary lines DL. The dimension inspection of the gate electrode 20 is performed for each, and the dimension inspection of the gate electrode 20 is performed for each of the two partial regions respectively corresponding to the two exposure regions ER sandwiching the other boundary line DL.

  In addition, even within one exposure region ER of the photoresist 200, the resist pattern that should originally have the same shape may greatly differ between the central portion and the portion close to the boundary line DL. As for the region where the gate electrode 20 is formed, in the partial region corresponding to one exposure region ER, the size of the gate electrode 20 that should originally be the same in the central portion and the portion close to the boundary line DL is the same. May be different. Accordingly, in step s410, in the partial region corresponding to one exposure region ER in the region where the gate electrode 20 is formed on the semiconductor substrate 1, the dimension of the gate electrode 20 at the central portion and the boundary line DL The dimension with the gate electrode 20 at a location close to is measured, and the two measured dimensions are compared. In the present embodiment, since the photoresist 200 is divided into three exposure regions ER, three photoresist regions ER corresponding to the three exposure regions ER in the region where the gate electrode 20 is formed on the semiconductor substrate 1 are provided. Such a dimension inspection of the gate electrode 20 is performed for each of the partial regions.

  Then, based on the result of the dimension comparison of the gate electrode 20, it is determined whether or not to continue the subsequent manufacturing process. If the dimensional variation of the gate electrode 20 is large, the manufacturing of the solid-state imaging device is finished, and if it is small, the subsequent manufacturing process is continuously executed. In addition, the result of the dimension comparison in step s410 is considered when determining the exposure conditions for manufacturing the solid-state imaging device of the next lot. That is, when manufacturing the solid-state imaging device of the next lot, the exposure conditions are adjusted so that the dimensional variation of the gate electrode 20 is reduced.

  On the other hand, if it is determined in step s407 that the resist pattern dimension inspection has failed, the patterned photoresist 200 is removed in step s411, and a new photoresist 200 is obtained in step s412. Is formed on the conductive film 210. In step s413, the exposure condition for the new photoresist 200 is adjusted based on the result of the resist pattern dimension comparison in step s406. In step s413, for example, the exposure amount is adjusted so that the dimensional variation of the resist pattern is reduced. Thereafter, step s404 is executed again under the adjusted exposure conditions, and the same processing is executed thereafter.

FIG. 17 is a flowchart showing in detail the process of forming various impurity regions in step s5. Below, the process of forming the N ⁻ type impurity region 11 will be representatively described.

As shown in FIG. 17, first, in step s <b> 501, a photoresist 300 is formed on the semiconductor substrate 1. Next, in step s502, the photoresist 300 is exposed using a photomask on which a predetermined mask pattern is formed. At this time, a divided exposure process is performed on the photoresist 300. FIG. 18 is a diagram showing a state of the divided exposure process in step s502. As shown in FIG. 18, the division exposure boundary line DL in the photoresist 300 is set at the same position as the division exposure boundary line DL in steps s303 and s404 described above. That is, in step s502, the boundary line DL is located in the active region AR on a region where the N ⁻ type impurity region 11 and the source / drain region 15 of the plurality of pixel portions 10 in a certain column are formed. In step s502, as in steps s303 and s404, the photoresist 300 is divided into three exposure regions ER, and an exposure process is performed on each of the three exposure regions ER.

  Next, in step s503, the exposed photoresist 300 is developed, and the photoresist 300 is patterned. FIG. 19 is a top view showing the photoresist 300 after patterning. As shown in FIG. 19, a photoresist 300 having an opening 300 a that exposes a partial active region AR <b> 1 is formed on the semiconductor substrate 1.

  Next, in step s504, the resist pattern formed in step s503 is inspected in the same manner as in step s406 described above. Here, in order to confirm whether or not the exposed area of the partial active region AR1 is appropriate, the dimension of the opening 300a formed in the photoresist 300 is measured. At this time, the position of the boundary line DL is grasped by detecting the steps 90 and 91 formed in the active region AR as in step s406.

Next, in step s505, it is determined whether or not the dimension inspection of the resist pattern formed on the photoresist 300 is acceptable based on the result of the dimension comparison of the resist pattern in step s504. If it is determined in step s505 that the resist pattern dimension inspection is acceptable, in step s506, for example, an ion implantation method is performed on the partial active region AR1 exposed from the photoresist 300 using the photoresist 300 as a mask. N-type impurities are introduced. Thereafter, in step s507, the photoresist 300 used for the mask is removed. Thereby, as shown in FIG. 20, an N ⁻ type impurity region 11 is formed in the partial active region AR1 of the active region AR.

  On the other hand, if it is determined in step s505 that the resist pattern dimension inspection has failed, in step s508, the patterned photoresist 300 is removed, and in step s509, the photoresist 300 is newly added to the semiconductor substrate. 1 is formed. In step s510, the exposure condition for the newly formed photoresist 300 is adjusted based on the result of the dimension comparison of the resist pattern in step s505. In step s510, for example, the exposure amount is adjusted. Thereafter, step s502 is executed again under the adjusted exposure conditions, and the same processing is executed thereafter.

When forming the N ⁺ type impurity region 12, the source / drain regions 13 to 16 and the P ⁺ type impurity region 17, the same processing is performed.

  FIG. 21 is a flowchart showing in detail the process of forming the contact plug 40 in step s7 and the process of forming the via plug in step s10. Since the contact plug 40 and the via plug are formed by the same method, a process for forming the contact plug 40 will be described below as a representative.

  As shown in FIG. 21, first, in step s701, a photoresist 400 is formed on the interlayer insulating film 30 formed in step s6. Next, in step s702, the photoresist 400 is exposed using a photomask on which a predetermined mask pattern is formed. At this time, a divided exposure process is performed on the photoresist 400. FIG. 22 is a diagram showing a state of the divided exposure process in step s702. As shown in FIG. 22, the boundary line DL for divided exposure in the photoresist 400 is set at the same position as the boundary line DL for divided exposure in the above-described steps s303, s404, and s502. In step s702, similar to steps s303, s404, and s502, the photoresist 400 is divided into three exposure areas ER, and an exposure process is performed on each of the three exposure areas ER.

Next, in step s703, the exposed photoresist 400 is developed, and the photoresist 400 is patterned. In step s704, using the photoresist 400 as a mask, the interlayer insulating film 30 exposed from the photoresist 400 is removed by etching. Thereafter, in step s705, the photoresist 400 used for the mask is removed. As a result, a plurality of contact holes exposing the N ⁺ -type impurity regions 12 and the like are formed in the interlayer insulating film 30. When a via plug is formed in the interlayer insulating film 60, a via hole exposing the wiring 50 is formed in the interlayer insulating film 60.

  Next, in step s706, a conductive film filling each contact hole in the interlayer insulating film 30 is formed. As a result, a plurality of contact plugs 40 are formed in the interlayer insulating film 30. When forming a via plug in the interlayer insulating film 60, the conductive film is filled in the via hole formed in the interlayer insulating film 60.

  FIG. 23 is a flowchart showing in detail the process of forming the lower wiring 50 in step s8 and the process of forming the upper wiring 80 in step s11. Since the wirings 50 and 80 are formed by the same method, the process of forming the wiring 80 will be described below as a representative.

  As shown in FIG. 23, first, in step s801, a conductive film 510 to be the wiring 80 is formed on the interlayer insulating film 60, and then in step s802, a photoresist 500 is formed on the conductive film 510.

  Next, in step s803, the photoresist 500 is exposed using a photomask on which a predetermined mask pattern is formed. At this time, a divided exposure process is performed on the photoresist 500. FIG. 24 is a diagram showing the state of the divided exposure process in step s803. As shown in FIG. 24, the boundary line DL for divided exposure in the photoresist 500 is set at the same position as the boundary line DL in the above-described steps s303, s404, s502, and s702. In step s803, as in steps s303, s404, s502, and s702, the photoresist 500 is divided into three exposure regions ER, and an exposure process is performed on each of the three exposure regions ER.

Next, in step s804, the exposed photoresist 500 is developed, and the photoresist 500 is patterned. FIG. 25 is a top view showing the photoresist 500 after patterning. As shown in FIG. 25, a photoresist 500 is formed on the conductive film 510 so as to expose the upper portion of the N ⁻ -type impurity region 11 in the conductive film 510.

  Here, the patterned photoresist 500 has a shape in which the resist pattern is shifted in the Y-axis direction between the two adjacent exposure regions ER with respect to the boundary line DL. This is because a positional shift in the Y-axis direction has occurred between two types of mask patterns used when exposing two adjacent exposure regions ER in the photoresist 500. As a result, a step 501 occurs on the inner side surface of the photoresist 500 with the boundary line DL of the divided exposure as a boundary.

  Next, in step s805, using the photoresist 500 as a mask, the conductive film 510 exposed from the photoresist 500 is removed by etching. Thereafter, in step s806, the photoresist 500 used for the mask is removed. As a result, as shown in FIG. 26, the wiring 80 is formed on the interlayer insulating film 60. A step 92 is formed on the inner side surface of the grid-like wiring 80 in accordance with the step 501 formed in the photoresist 500.

  As described above, in the method for manufacturing a solid-state imaging device according to the present embodiment, when the photoresist 100 used for partitioning the active region AR on the semiconductor substrate 1 is divided and exposed, the boundary line DL is At least on the region PAR where the active region AR is defined in the semiconductor substrate 1.

  On the other hand, when the boundary line DL of the divided exposure is located only on the region where the element isolation structure 3 is formed in the semiconductor substrate 1, two exposure regions ER sandwiching the boundary line DL are exposed. In this case, the size of the element isolation structure 3 formed below the boundary line DL may be smaller than the original due to the positional deviation between the two types of mask patterns used at the time. For this reason, sufficient electrical insulation between the elements due to the element isolation structure 3 is not ensured, which may cause performance deterioration or malfunction of the solid-state imaging element. In recent years, the number of pixels required in a solid-state imaging device has increased, and accordingly, a plurality of pixel portions 10 are densely arranged, so that the dimensions of the element isolation structure 3 are also becoming smaller. Therefore, the problem of performance deterioration of the solid-state imaging device due to the dimensional change of the element isolation structure 3 has become very remarkable. In particular, when the boundary line DL is disposed only on the region where the element isolation structure 3 existing between the adjacent pixel portions 10 is formed, the interval between the pixel portions 10 maintains the original size. This is not possible, and crosstalk between the pixel units 10 becomes a serious problem, and the imaging performance of the solid-state imaging device is greatly deteriorated.

  In the present embodiment, the boundary line DL between two exposure regions ER adjacent to each other in the photoresist 100 is not limited to the region where the element isolation structure 3 is formed in the semiconductor substrate 1 but the active region AR in the semiconductor substrate 1. Since it is also located on the region to be formed, if a positional shift occurs between the two types of mask patterns used when exposing the two exposure regions ER, the dimensional change of the element isolation structure 3 It is possible to reduce the portion where the occurrence occurs. As a result, it is possible to suppress performance deterioration of the solid-state imaging device. From another point of view, since the allowable mask pattern positional deviation amount can be increased, it is possible to improve the manufacturing throughput and increase the manufacturing margin.

Further, in the present embodiment, the boundary line DL when the photoresist 100 is divided and exposed is, in particular, an N ⁻ type that is a constituent element of the photodiode PD in the region PAR in which the active region AR is formed in the semiconductor substrate 1. It is located on a region where impurity region 11 is formed, that is, a region where partial active region AR1 is formed. Among the active regions AR, the surface area of the partial active region AR1 where the N ⁻ -type impurity region 11 is formed can be made larger than that of the other partial active regions. Even when the dimensions change, the changes do not significantly affect the performance of the solid-state imaging device. Therefore, it is possible to further suppress the performance deterioration of the solid-state imaging device.

In the present embodiment, the boundary line DL when the photoresist 100 is dividedly exposed is the N ⁺ type impurity region 12 that functions as the floating diffusion FD in the region PAR in which the active region AR is formed in the semiconductor substrate 1. Therefore, even if the mask pattern is displaced, the dimension of the partial active region AR5 does not change. Therefore, the dimensional change of the N ⁺ type impurity region 12 can be suppressed. When a dimensional change occurs in the N ⁺ -type impurity region 12, the charge storage capacity in the floating diffusion FD changes, so that the characteristics of the pixel corresponding to the pixel unit 10 having the N ⁺ -type impurity region 12 change. There is. This leads to degradation of image quality. In this embodiment, since the dimensional change of the N ⁺ -type impurity region 12 due to the displacement of the mask pattern can be suppressed, it is possible to suppress the deterioration of the image quality.

  In the present embodiment, steps 90 and 91 are formed on the periphery of the active region AR in a top view according to the position of the boundary line DL. Therefore, by detecting the steps 90 and 91, the boundary is detected. The position of the line DL can be easily grasped. Therefore, the dimension measurement of the resist pattern based on the boundary line DL and the dimension measurement of the forming element can be easily performed, and the dimension measurement result can be easily fed back to the exposure conditions.

  Furthermore, in the present embodiment, a step 92 is formed on the side surface of the wiring 80 in accordance with the position of the boundary line DL. Therefore, the position of the boundary line DL can be easily grasped by detecting the step 92. be able to.

  Further, the boundary line DL in the divided exposure processing when the active region AR is partitioned on the semiconductor substrate 1 is, as shown in FIG. 9, the Y-axis on the region where the partial active region AR1 is formed on the semiconductor substrate 1. Extends along the direction. That is, the boundary line DL extends along the short direction of the region on the region where the partial active region AR1 is formed in the semiconductor substrate 1.

  On the other hand, the boundary line DL in the divided exposure process when the active region AR is partitioned on the semiconductor substrate 1 is along the X-axis direction on the region where the partial active region AR1 is formed on the semiconductor substrate 1. In other words, when extending along the longitudinal direction of the region, the length of the boundary line DL crossing the region is long when viewed from the top. The amount of variation in the surface area of the partial active region AR1 increases. FIG. 27 shows the state. Region 700 in FIG. 27 is partially active when boundary line DL extends along the short direction of the region where partial active region AR1 is formed in semiconductor substrate 1 as in the present embodiment. The fluctuation amount of the surface area of the area AR1 is shown. A region 701 in FIG. 27 shows the amount of change in the surface area of the partial active region AR1 when the boundary line DL extends along the longitudinal direction of the region where the partial active region AR1 is formed in the semiconductor substrate 1. ing.

As described above, when the boundary line DL in the divided exposure process when the active region AR is partitioned on the semiconductor substrate 1 extends in the longitudinal direction of the region where the partial active region AR1 is formed on the semiconductor substrate 1. The amount of change in the surface area of the partial active region AR1 due to the displacement of the mask pattern increases. Since the N ⁻ type impurity region 11 of the photodiode PD is formed in the partial active region AR1, when the surface area of the partial active region AR1 varies, the surface area of the N ⁻ type impurity region 11 varies, and the photodiode PD The sensitivity of photoelectric conversion varies. As a result, image quality is degraded. Therefore, as in the present embodiment, the boundary line DL in the divided exposure processing when the active region AR is partitioned on the semiconductor substrate 1 is the short direction of the region where the partial active region AR1 is formed on the semiconductor substrate 1 As a result, the variation of the surface area of the partial active region AR1 can be suppressed, and the deterioration of the image quality can be suppressed.

  In the present embodiment, the boundary line DL in the divided exposure process when the active region AR is partitioned on the semiconductor substrate 1 is a partial active region that contacts the contact plug 40 among the plurality of partial active regions AR1 to AR7. AR2 to AR4, AR6, and AR7 are not located on the region formed in the semiconductor substrate 1.

  On the other hand, when the boundary line DL is located on a region where the partial active region AR2 in contact with the contact plug 40 is formed in the semiconductor substrate 1, for example, the mask pattern is displaced in the divided exposure. As a result, a step similar to the step 91 of the partial active region AR5 is generated at the peripheral edge of the partial active region AR2, and the distance between the element isolation structure 3 around the partial active region AR2 and the contact plug 40 is reduced. Leakage current between 40 and well region 2 may increase.

  In the present embodiment, when a mask pattern misalignment occurs at the time of divided exposure, a step is generated at the peripheral edges of the partial active regions AR1 and AR5 that do not come into contact with the contact plug 40, resulting in the mask pattern misalignment. An increase in leakage current between the contact plug 40 and the well region 2 can be suppressed.

  In general, in the manufacturing process of a semiconductor device, when a structure formed in a subsequent process is aligned with a structure formed in a previous process, the alignment accuracy of both structures is increased and the apparatus is increased. In order to reduce the size of the photomask, the mask pattern of the photomask used in the previous process is designed based on the mask pattern of the photomask used in the subsequent process. For example, since the gate electrode 20 formed in the subsequent process is aligned with the active region AR formed in the previous process, the mask pattern of the photomask used when forming the gate electrode 20 Is designed based on a mask pattern of a photomask used when the active region AR is partitioned into the semiconductor substrate 1. Since the contact plug 40 is aligned with the gate electrode 20, the mask pattern of the photomask used when forming the contact plug 40 is a photomask used when forming the gate electrode 20. Designed based on the mask pattern. Since the lower layer wiring 50 is aligned with the contact plug 40, the mask pattern of the photomask used when forming the wiring 50 is a photomask used when forming the contact plug 40. Designed based on the mask pattern. Since the via plug is aligned with the wiring 50, the mask pattern of the photomask used when forming the via plug is based on the mask pattern of the photomask used when forming the wiring 50. Designed. Since the upper-layer wiring 80 is aligned with the via plug, the mask pattern of the photomask used when forming the wiring 80 is the same as the mask pattern of the photomask used when forming the via plug. Designed based on.

  In this way, in the two processes for forming the two structures aligned with each other, it is preferable that the position of the boundary line DL of the divided exposure is set to be the same. For example, as in the present embodiment, it is preferable that the boundary line DL for division exposure when the active region AR is partitioned into the semiconductor substrate 1 and when the gate electrode 20 is formed is set at the same position.

  On the other hand, in the two processes for forming the two structures that are aligned with each other, when the boundary line DL of the divided exposure is set to a different position, the alignment accuracy deteriorates due to the displacement of the mask pattern. As a result, the yield may decrease. For example, as shown in FIG. 28, the boundary line DLA, which is the boundary line DL when forming the gate electrode 20, is set on the partial active region AR5, and the boundary line DLB, which is the boundary line DL when forming the contact plug 40 However, a case is considered in which the partial active region AR4 is set on a region on the partial active region AR3 side (right side in the drawing) with respect to the region where the contact plug 40 in contact therewith is formed. In this case, when the gate electrode 20 is formed, the mask pattern for exposing the exposure region ER closer to the partial active region AR4 (right side in the drawing) than the boundary line DLA is the arrow direction of the X axis (right side in the drawing). The mask pattern for exposing the exposure region ER on the side of the partial active region AR5 (left side in the drawing) from the boundary line DLB when the contact plug 40 is formed is opposite to the X-axis arrow. When the position is shifted in the direction (left direction in the figure), the gate electrode 20 of the amplification transistor AMI and the contact plug 40 on the partial active region AR4 may be closer than the allowable interval, resulting in a decrease in yield. is there.

  As in the present embodiment, in the two processes for forming two structures that are aligned with each other, the position of the boundary line DL of the divided exposure is set to be the same, so that the alignment accuracy can be improved. As a result, the yield can be improved.

It is desirable that the boundary line DL in the divided exposure process when forming the N ⁻ type impurity region 11 on the semiconductor substrate 1 is not located on the partial active region AR1, as shown in FIG. When the boundary line DL when forming the N ⁻ -type impurity region 11 is positioned on the partial active region AR1, the shape of the opening 300a of the photoresist 300 described above is caused by the displacement of the mask pattern at the time of divided exposure. As a result, the shape of the N ⁻ -type impurity region 11 changes. As a result, the sensitivity of photoelectric conversion in the photodiode PD may change greatly, and the image quality deteriorates. Therefore, as shown in FIG. 29, by not arranging the boundary line DL when forming the N ⁻ -type impurity region 11 on the partial active region AR1, the shape change of the N ⁻ -type impurity region 11 is suppressed, Degradation of image quality can be suppressed.

As shown in FIG. 29, the boundary line DL when forming the N ⁻ -type impurity region 11, the N ⁺ -type impurity region 12, the source / drain regions 13 to 16 and the P ⁺ -type impurity region 17 is always It is desirable that the active region AR is located only on the partial active region AR7. In this case, the position of the boundary line DL when forming various impurity regions is constant, and the design of the photomask becomes easy. Further, when the N ⁻ -type impurity region 11 is formed, the boundary line DL is not located on the partial active region AR1, so that deterioration in image quality can be suppressed. When forming the P ⁺ -type impurity region 17, the boundary line DL is disposed on the partial active region AR 7, so that the shape of the P ⁺ -type impurity region 17 changes due to the displacement of the mask pattern at the time of divided exposure. However, since the P ⁺ -type impurity region 17 is an impurity region to which the ground potential GND, which is a negative power supply potential, is applied, the characteristics of the pixel portion 10 are not affected even if the shape of the P ⁺ -type impurity region 17 changes. It does n’t change that much.

  Further, if the present invention is regarded as an invention relating to a solid-state imaging device, in the solid-state imaging device, the active region AR in which the pixel portion 10 is formed has a partial active region AR1 having steps 90 and 91 on the periphery in a top view. , AR5, the steps 90, 91 of the partial active regions AR1, AR5 with respect to the photoresist 100 used when the active region AR is defined on the semiconductor substrate 1 as in the present embodiment. When the divided exposure is performed with the position of as a boundary, by detecting the steps 90 and 91, the position of the boundary line DL for the divided exposure can be easily grasped.

  Furthermore, since the step 92 is also formed on the side surface of the wiring 80, when the exposure is performed with the position of the step 92 as a boundary when the wiring 80 is formed, the step 92 is detected. Thus, the position of the boundary line DL for divided exposure can be easily grasped.

  Further, since the contact plug 40 is not in contact with the partial active regions AR1 and AR5 in which the steps 90 and 91 are formed on the periphery, the increase in leakage current between the contact plug 40 and the well region 2 is increased. Can be suppressed.

1 semiconductor substrate, 3 the element isolation structure, 11 N ^- -type impurity regions, 12 ^{N +} -type impurity region, 13-16 source and drain regions, 17 ^{P +} -type impurity region, 40 contact plugs 80 wires, 90～92,101 , 501 step, 95, 100, 200, 300, 400, 500 photoresist, 510 conductive film, AMI amplification transistor, AR active region, AR1 to AR7 partial active region, DL boundary line, ER exposure region, GND ground potential, PAR Region, SEL selection transistor.

Claims (5)

A method of manufacturing a solid-state imaging device,
(A) preparing a substrate;
(B) forming a first photoresist on the substrate;
(C) exposing the first photoresist;
(D) after the step (c), developing the first photoresist and patterning the first photoresist;
(E) using the first photoresist patterned in the step (d), an element isolation structure including an insulating film that divides an active region in which a pixel portion of the solid-state imaging element is formed on the substrate. A step of forming on the substrate,
The step (c)
(C-1) exposing a first region of the first photoresist;
(C-2) exposing the second region adjacent to the first region in the first photoresist after the step (c-1),
The boundary line between the first and second regions in the step (c) is located at least on a region where the active region is partitioned in the substrate,
In the element isolation structure made of the insulating film in the step (e), a step is formed with the boundary line as a boundary.
The pixel portion includes a photodiode having a first impurity region, and a floating diffusion for accumulating charges generated in the photodiode by photoelectric conversion ,
The boundary line in said step (c) is less and positioned on a region where the photodiode is formed even before Symbol substrate, and not located in a region where the floating diffusion is formed in the substrate,
(F) after the step (e), forming a second photoresist on the substrate;
(G) exposing the second photoresist;
(H) developing the second photoresist and patterning the second photoresist;
(I) Impurities are introduced into the first partial active region in which the first impurity region is formed, which is exposed from the second photoresist patterned in the step (h), and the first partial activity Forming the first impurity region in a region,
The step (g)
(G-1) exposing the first region of the second photoresist;
(G-2) exposing a second region adjacent to the first region in the second photoresist,
The solid-state imaging device manufacturing method, wherein a boundary line between the first and second regions in the step (g) is located at least on the active region and is not located on the first partial active region. It is a manufacturing method of the solid-state image sensing device according to claim 1,
The pixel portion further includes a second impurity region to which a ground potential that is one power supply potential of the pixel portion is applied,
The active region further includes a second partial active region in which the second impurity region is formed,
(J) after the step (e), forming a third photoresist on the substrate;
(K) exposing the third photoresist;
(L) developing the third photoresist and patterning the third photoresist;
(M) introducing impurities into the second partial active region exposed from the third photoresist patterned in the step (l) to form the second impurity region in the second partial active region And further comprising
The step (k)
(K-1) exposing a first region of the third photoresist;
(K-2) exposing a second region adjacent to the first region in the third photoresist,
The boundary line in the step (g) and the boundary line of the first and second regions in the step (k) are set at the same position, and at least located on the second partial active region. And the manufacturing method of the solid-state image sensor which is not located on the said 1st partial active region. A method of manufacturing a solid-state imaging device,
(A) preparing a substrate;
(B) forming a first photoresist on the substrate;
(C) exposing the first photoresist;
(D) after the step (c), developing the first photoresist and patterning the first photoresist;
(E) using the first photoresist patterned in the step (d), an element isolation structure including an insulating film that divides an active region in which a pixel portion of the solid-state imaging element is formed on the substrate. A step of forming on the substrate,
The step (c)
(C-1) exposing a first region of the first photoresist;
(C-2) exposing the second region adjacent to the first region in the first photoresist after the step (c-1),
The boundary line between the first and second regions in the step (c) is located at least on a region where the active region is partitioned in the substrate,
In the element isolation structure made of the insulating film in the step (e), a step is formed with the boundary line as a boundary.
The active region includes a plurality of partial active regions each formed with a plurality of impurity regions,
The pixel portion is
A photodiode;
Floating diffusion for accumulating charges generated in the photodiode by photoelectric conversion;
A first MOS transistor for amplifying the potential of the floating diffusion;
A second MOS transistor for initializing the potential of the cathode of the photodiode and the floating diffusion;
With
(F) after the step (e), forming the plurality of impurity regions;
(G) after the step (f), forming a contact plug in contact with a part of the partial active regions formed in the plurality of partial active regions where the drains of the first and second MOS transistors are formed; Further comprising
The manufacturing method of a solid-state imaging device, wherein the boundary line in the step (c) is not located on a region where the partial active region is formed on the substrate. It is a manufacturing method of the solid-state image sensing device according to claim 3,
The pixel unit further includes a third MOS transistor that selects whether to output the potential amplified by the first MOS transistor to an output line ,
The plurality of impurity regions include source / drain regions shared by the first and third MOS transistors and not in contact with the contact plugs,
The boundary line in the step (c) is a solid in which at least a partial active region in which the source / drain region is formed among the plurality of partial active regions is located on a region formed in the substrate. Manufacturing method of imaging device. A substrate in which an active region in which a pixel portion is formed is partitioned by an element isolation structure made of an insulating film;
A photodiode formed in the pixel portion,
The photodiode has a shape shifted in one direction on the top view so that a step due to divided exposure occurs at the periphery on the top view,
The active region includes a plurality of partial active regions each formed with a plurality of impurity regions,
The plurality of partial active regions include partial active regions having a shape shifted in one direction on the top view so that a step due to divided exposure occurs at the periphery on the top view,
A solid-state imaging device in which a contact plug is not in contact with a partial active region having a shape shifted in one direction.

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