JP2014086552A - Solid state image sensor and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easy-to-manufacture solid state image sensor producing homogeneous image data, and to provide a manufacturing method for solid state image sensor.SOLUTION: A solid state image sensor 1 includes a substrate 11, a plurality of photoelectric conversion parts 12 formed in the substrate 11 and generating charges by performing photoelectric conversion of incident light, a first light shielding film 15 formed above the substrate 11 and shielding the light impinging on the photoelectric conversion part, and a second light shielding film 17 formed above the first light shielding film 15 and shielding the light impinging on the photoelectric conversion part 12. Furthermore, the solid state image sensor 1 is provided with a first area 30 through which light enters the photoelectric conversion part 12, a second area 50 which is shielded when the photoelectric conversion part 12 is covered with the second light shielding film 17, and a third area 90 located between the first area 30 and second area 50, and shielded when the photoelectric conversion part 12 is covered with the first light shielding film 15.

Description

  The present invention relates to a solid-state imaging device represented by a CCD (Charge Coupled Device) image sensor, a CMOS (Complementary Metal Oxide Semiconductor) image sensor, and the like, and a method of manufacturing the solid-state imaging device.

  In recent years, solid-state imaging devices have been mounted not only on digital still cameras and digital video cameras but also on various electronic devices such as mobile phones and personal computers. The solid-state imaging device includes a plurality of photoelectric conversion units (for example, photodiodes), and generates charges by photoelectrically converting incident light. Then, the solid-state imaging device generates pixel data by accumulating, reading, amplifying, and the like, and further processing the pixel data to generate image data.

  The solid-state imaging device can include not only a photoelectric conversion unit that generates charges that are the basis of pixel data, but also a photoelectric conversion unit for detecting charges generated by noise such as dark current (see, for example, Patent Document 1). .

  An example of such a solid-state imaging device will be described with reference to the drawings. FIG. 7 is a plan view showing the entire structure of a conventional solid-state imaging device. 8 and 9 are cross-sectional views showing a conventional method for manufacturing a solid-state imaging device. 8 and 9 show a cross section perpendicular to the plane shown in FIG. 7 to 9 is a CCD image sensor.

  First, the overall structure of the solid-state imaging device 1 will be described with reference to FIG. As shown in FIG. 7, the solid-state imaging device 100 includes an effective pixel region 130 including a photoelectric conversion unit that generates a charge that is a basis of pixel data, and a noise detector provided on the outer peripheral side of the effective pixel region 130. An optical black (hereinafter referred to as OB) region 150 including a photoelectric conversion portion and a peripheral region 170 provided on the outer peripheral side of the OB region 150 and formed with various circuits such as a driver for controlling charge reading.

  A method for manufacturing the solid-state imaging device 1 will be described with reference to FIGS. First, as shown in FIG. 8A, a plurality of photoelectric conversion units 112 are formed inside the substrate 111. Next, a gate insulating film 113 is formed on the upper surface of the substrate 111. Next, the gate electrode 114 is formed on the upper surface of the gate insulating film 113 and at a position adjacent to the portion directly above the photoelectric conversion portion 112. Next, the first light shielding film 115 is formed over the entire surface so as to fill up the gate insulating film 113 and the gate electrode 114.

  Next, as illustrated in FIG. 8B, a photoresist R <b> 10 is formed on the upper surface of the first light shielding film 115, avoiding the portion directly above the photoelectric conversion unit 112. Then, by selectively etching a portion of the first light shielding film 115 where the photoresist R10 is not formed on the upper surface, the first light shielding film 115 having an opening immediately above the photoelectric conversion unit 112 is formed. Then, after this step, the structure shown in FIG. 8C is obtained by removing the photoresist R10.

  Next, as illustrated in FIG. 9A, an interlayer insulating film 116 is formed over the entire surface so as to fill up the gate insulating film 113 and the first light shielding film 115. Next, a second light shielding film 117 is formed over the entire surface of the interlayer insulating film 116.

  Next, as illustrated in FIG. 9B, a photoresist R <b> 20 is formed on the upper surface of the second light shielding film 117, avoiding the OB region 150. Then, by selectively etching the portion of the second light shielding film 117 where the photoresist R20 is not formed on the upper surface, the thickness of the second light shielding film 117 is partially reduced. After this step, the structure shown in FIG. 9C is obtained by removing the photoresist R20.

  Next, as illustrated in FIG. 9D, a photoresist R <b> 30 is formed on the upper surface of the second light shielding film 117 while avoiding the effective pixel region 130. Then, the second light shielding film 117 is partially removed by selectively etching a portion of the second light shielding film 117 where the photoresist R30 is not formed on the upper surface. Then, after this process, the structure shown in FIG. 9E is obtained by removing the photoresist R30.

  Further, by forming an optical member such as a color filter or an on-chip lens with respect to the structure shown in FIG. 9E, the solid-state imaging device 100 can be obtained.

  Incidentally, in the solid-state imaging device proposed in Patent Document 1, unlike the solid-state imaging device 100 described above, a second light-shielding film having a uniform thickness is formed in the OB region. However, when such a structure is adopted, a steep step in the second light shielding film is formed at the boundary between the effective pixel region and the OB region. Then, under the influence of the step, the optical member formed on the OB region side in the effective pixel region is tilted or varies due to the difference in size of the optical member from the others, so that uniform image data is obtained. It may not be obtained.

  Therefore, in the above-described solid-state imaging device 100, as shown in FIGS. 9C to 9E, by adopting a structure in which the second light shielding film 117 in the OB region 150 is partially thinned, While blocking the light incident on the photoelectric conversion unit 112, the step of the second light shielding film 117 is relaxed.

JP 2001-144280 A

  However, in the above-described solid-state imaging device 100, the second light shielding film 117 needs to be partially thinned. Therefore, it is necessary to separately add a process of forming the photoresist R20 and etching the second light shielding film 117, which causes a problem that the manufacturing process becomes complicated.

  Further, as shown in FIGS. 9D and 9E, in the above-described solid-state imaging device 100, the second light shielding film in the effective pixel region 130 is surely removed in order to reliably remove the second light shielding film 117 in the effective pixel region 130. Etching is performed not only to 117 but also to a part of the second light-shielding film 117 in the OB region 150 where the film thickness is already small. In this case, when the etching proceeds excessively in the OB region 150 and the interlayer insulating film 116 that is the base of the second light shielding film 117 is etched (part indicated by an arrow A in FIG. 9E), for example, This is a problem because a failure such as the destruction of the gate electrode 114 may occur.

  Therefore, an object of the present invention is to provide a solid-state imaging device that can obtain uniform image data and can be easily manufactured, and a method for manufacturing the solid-state imaging device.

  In order to achieve the above object, the present invention provides a substrate, a plurality of photoelectric conversion portions that are formed inside the substrate and photoelectrically convert incident light, and are formed above the substrate. A first light-blocking film that blocks light incident on the photoelectric conversion unit; and a second light-blocking film that is formed above the first light-blocking film and blocks light incident on the photoelectric conversion unit, and the photoelectric conversion unit However, the first region where light is incident because it is not covered by the first light shielding film and the second light shielding film, and the photoelectric conversion unit are not covered by the first light shielding film and are covered by the second light shielding film. Between the first region and the second region, and the photoelectric conversion unit is not covered by the second light shielding film and is covered by the first light shielding film. And a third region that is shielded from light. To provide a solid-state imaging device according to claim Rukoto.

  Furthermore, in the solid-state imaging device having the above characteristics, interlayer insulation formed over the entire surface so as to fill up the upper side of the first light shielding film and the upper side of the photoelectric conversion unit not covered with the first light shielding film. A film, and an intra-layer lens that is formed immediately above the photoelectric conversion unit in the first region and condenses incident light on the photoelectric conversion unit, and further includes the second light-shielding film and the layer A lens may be formed on the upper surface of the interlayer insulating film.

  Furthermore, in the solid-state imaging device having the above characteristics, interlayer insulation formed over the entire surface so as to fill up the upper side of the first light shielding film and the upper side of the photoelectric conversion unit not covered with the first light shielding film. A planarizing film formed entirely to fill up the interlayer insulating film and the second light shielding film, and an upper surface of the planarizing film directly above the photoelectric conversion portion in the first region A color filter that selectively transmits light of a predetermined wavelength, and an upper surface of the color filter that is directly above the photoelectric conversion unit in the first region, and collects incident light to collect the light. And an on-chip lens that transmits the color filter.

  In the present invention, a first light-shielding film that blocks light incident on the photoelectric conversion unit is formed above a substrate on which a plurality of photoelectric conversion units that generate charges by photoelectrically converting incident light are formed. A first light-shielding film forming step, and a second light-shielding film forming step for forming a second light-shielding film that shields light incident on the photoelectric conversion unit above the first light-shielding film. The photoelectric conversion unit is not covered with the first light-shielding film and the second light-shielding film by the film formation step and the second light-shielding film formation step, and the photoelectric conversion unit A second region that is not covered by the first light-shielding film and is shielded by being covered by the second light-shielding film, and the photoelectric conversion unit is located between the first region and the second region, Before being covered by the second light shielding film To provide a manufacturing method of a solid-state imaging device characterized by providing a third region is shielded by being covered with the first light shielding film.

  Furthermore, in the method for manufacturing a solid-state imaging device having the above characteristics, in the first light shielding film forming step, after the first light shielding film is formed over the entire surface, the photoelectric conversion units in the first region and the second region are formed. The first light shielding film in a part or all of the portion directly above each is removed at the same time, and in the second light shielding film forming step, after forming the second light shielding film entirely, It is preferable to remove the second light shielding film in the third region at the same time.

  Furthermore, in the method for manufacturing a solid-state imaging element having the above characteristics, the first light shielding film is covered between the first light shielding film forming step and the second light shielding film forming step, and the first light shielding film. An interlayer insulating film forming step for forming an interlayer insulating film over the entire surface so as to completely fill the upper portion of the photoelectric conversion portion, and after the second light shielding film forming step, above the interlayer insulating film, A lens material film forming step for forming a lens material film over the entire surface of the second light-shielding film formed on the interlayer insulating film to fill the surface, and the lens material film is processed so as to be incident. An intra-layer lens forming step of forming an intra-layer lens for condensing light on the photoelectric conversion unit on the upper surface of the interlayer insulating film that is directly above the photoelectric conversion unit in the first region; Also good.

  Furthermore, in the method for manufacturing a solid-state imaging element having the above characteristics, the first light shielding film is covered between the first light shielding film forming step and the second light shielding film forming step, and the first light shielding film. An interlayer insulating film forming step for completely forming an interlayer insulating film so as to fill the upper portion of the photoelectric conversion portion that has not been filled; and the interlayer insulating film and the second light shielding after the second light shielding film forming step. A flattening film forming step of forming a flattening film over the entire surface so as to fill the upper part of the film; and after the flattening film forming step, the flattening film of the first region directly above the photoelectric conversion unit A color filter forming step for forming a color filter that selectively transmits light of a predetermined wavelength on the upper surface; and light incident on the upper surface of the color filter that is directly above the photoelectric conversion unit in the first region And the on-chip lens forming step of condensing to form an on-chip lens that transmits the color filter may further comprise a.

  According to the solid-state imaging device having the above characteristics and the method for manufacturing the solid-state imaging device, the first region where light is incident on the photoelectric conversion unit, and the second region where light is incident on the photoelectric conversion unit by the second light shielding film, Thus, a solid-state imaging device provided with a third region in which light incidence to the photoelectric conversion unit is blocked by the first light shielding film instead of the second light shielding film is obtained. In this solid-state imaging device, the effect of the step of the second light shielding film formed in the second region can be reduced in the third region between the first region and the second region. Can be suppressed. Therefore, the solid-state image sensor can obtain uniform image data by suppressing the inclination of the optical member formed on the second region side in the first region and the size of the optical member from being significantly different from others. It is possible to generate.

  Furthermore, this solid-state imaging device can be obtained by only partially removing the first light shielding film in the first region and the second region and removing the second light shielding film in the first region and the third region. In other words, the solid-state imaging device can be manufactured without performing any special process only by adjusting the position where the first light shielding film is removed and the position where the second light shielding film is removed. It is. Therefore, this solid-state imaging device can be easily manufactured.

The top view shown about the example of whole structure of the solid-state image sensor which concerns on embodiment of this invention. Sectional drawing shown about the example of a manufacturing method of the solid-state image sensor which concerns on embodiment of this invention. Sectional drawing shown about the example of a manufacturing method of the solid-state image sensor which concerns on embodiment of this invention. Sectional drawing shown about the structural example of the solid-state image sensor which concerns on embodiment of this invention. Sectional drawing shown about the example of a manufacturing method of the solid-state image sensor which concerns on another embodiment of this invention. Sectional drawing shown about the structural example of the solid-state image sensor which concerns on another embodiment of this invention. The top view shown about the whole structure of the conventional solid-state image sensor. Sectional drawing shown about the manufacturing method of the conventional solid-state image sensor. Sectional drawing shown about the manufacturing method of the conventional solid-state image sensor.

  Hereinafter, a CCD image sensor will be exemplified and described as a solid-state imaging device according to an embodiment of the present invention.

  First, an example of the overall structure of a solid-state imaging device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing an example of the overall structure of a solid-state imaging device according to an embodiment of the present invention.

  As shown in FIG. 1, the solid-state imaging device 1 according to the embodiment of the present invention includes an effective pixel region 30 (first region) including a photoelectric conversion unit that generates charges that are the basis of pixel data, and an effective pixel region 30. An invalid pixel region 90 (third region) that is provided on the outer peripheral side and includes a predetermined photoelectric conversion unit, and an OB region 50 (first region) that is provided on the outer peripheral side of the invalid pixel region 90 and includes a photoelectric conversion unit for detecting noise. 2 region) and a peripheral region 70 provided on the outer peripheral side of the OB region 50 and formed with various circuits such as a driver for controlling charge reading.

  The charge generated by the photoelectric conversion unit in the effective pixel region 30 becomes pixel data by being accumulated, read, amplified, and the like. On the other hand, since the photoelectric conversion unit in the invalid pixel region 90 and the photoelectric conversion unit in the OB region 50 are shielded from light as described later, pixel data that directly indicates the charge generated by these photoelectric conversion units is not generated. .

  However, the charge generated by the photoelectric conversion unit in the OB region 50 is used as a noise component such as dark current when generating pixel data from the charge generated by the photoelectric conversion unit in the effective pixel region 30. . Specifically, for example, pixel data is generated using the difference between the signals obtained from the charges generated by the photoelectric conversion units in the effective pixel region 30 and the OB region 50.

  The charge generated by the photoelectric conversion unit in the invalid pixel region 90 may be discarded or generated by the photoelectric conversion unit in the effective pixel region 30 in the same manner as the charge generated by the photoelectric conversion unit in the OB region 50. You may utilize when producing | generating pixel data from an electric charge.

  Further, the invalid pixel region 90 does not necessarily need to surround the entire outer periphery of the effective pixel region 30, and a part thereof may be interrupted. Similarly, a part of the OB region 50 and the peripheral region 70 may be interrupted. However, in the solid-state imaging device 1, it is assumed that there is a portion where the invalid pixel region 90 is provided between the effective pixel region 30 and the OB region 50.

  Next, a method for manufacturing a solid-state imaging device according to an embodiment of the present invention will be described with reference to the drawings. 2 and 3 are cross-sectional views illustrating an example of a method for manufacturing a solid-state imaging device according to an embodiment of the present invention. 2 and 3 show a cross section perpendicular to the plane shown in FIG.

  First, as shown in FIG. 2A, a plurality of photoelectric conversion units 12 are formed inside the substrate 11. Next, a gate insulating film 13 is formed on the upper surface of the substrate 11. Next, the gate electrode 14 is formed at a position adjacent to the upper surface of the gate insulating film 13 and directly above the photoelectric conversion unit 12. Next, the first light shielding film 15 is formed over the entire surface so as to fill up the gate insulating film 13 and the gate electrode 14. For example, the first light shielding film 15 is formed so as to cover the upper surface and the side surface of the gate electrode 14 in order to prevent noise from being generated when incident light is reflected by the gate electrode 14.

  The photoelectric conversion unit 12 is a region made of a semiconductor having a conductivity type different from that of the substrate 11 and is formed by adding impurities to the substrate 11 using a method such as ion implantation. For example, when the substrate 11 is made of silicon, it becomes p-type by adding boron or the like, and becomes n-type by adding phosphorus or arsenic.

  For example, when the substrate 11 is made of a p-type semiconductor (or has a p-type well), the photoelectric conversion unit 12 is made of an n-type region and accumulates electrons generated by photoelectric conversion. For example, when the substrate 11 is made of an n-type semiconductor (or has an n-type well), the photoelectric conversion unit 12 is made of a p-type region and accumulates holes generated by photoelectric conversion. Strictly speaking, the photoelectric conversion unit 12 and the region around the substrate 11 constitute a photodiode. Therefore, for example, when the photoelectric conversion unit 12 is n-type, not only the internally generated electrons are accumulated, but also the internally generated holes are discharged to the area around the substrate 11 and Acquire and accumulate the electrons generated in the region. Further, for example, when the photoelectric conversion unit 12 is p-type, not only the holes generated inside are accumulated, but also the electrons generated inside are discharged to the area around the substrate 11 and the area around the substrate 11. Acquire and accumulate the holes generated in.

  The gate insulating film 13 is made of silicon oxide obtained by thermal oxidation of the substrate 11 made of silicon, for example. The gate electrode 14 is made of, for example, polysilicon, and the first light shielding film 15 is made of, for example, metal. For example, the gate electrode 14 is formed by forming a film of the material forming the gate electrode 14 on the gate insulating film 13 and then forming a photoresist only on the upper surface of the portion where the gate electrode 14 is to be formed. It can be formed by etching.

  When a predetermined voltage is applied to the gate electrode 14, the photoelectric conversion unit 12 adjacent to the transfer region in the substrate 11 immediately below the gate electrode 14 in a predetermined direction (for example, left direction in the drawing) of the transfer region. The electric charge accumulated in is read out. In order to prevent charges from being read out in a direction opposite to the predetermined direction (for example, the right direction in the figure), a region having the same conductivity type as the substrate 11 and having a higher impurity concentration than the substrate 11 is designated as a transfer region. And the photoelectric conversion unit 12 adjacent in the opposite direction.

  Next, as shown in FIG. 2B, a part (center part) immediately above each of the photoelectric conversion units 12 in the effective pixel region 30 and a part directly above each of the photoelectric conversion units 12 in the OB region 50. A photoresist R <b> 1 is formed on the upper surface of the first light-shielding film 15 while avoiding the (center portion). Therefore, a photoresist R <b> 1 is formed on the upper surface of the first light shielding film 15 immediately above each of the photoelectric conversion units 12 in the invalid pixel region 90. Note that a photoresist R1 may be appropriately formed on the upper surface of the first light shielding film 15 in the peripheral region 70 according to, for example, a circuit to be formed.

  Next, a portion of the first light shielding film 15 where the photoresist R1 is not formed on the upper surface is removed by etching. Thereby, a part (center part) immediately above each of the photoelectric conversion units 12 in the effective pixel region 30 and a part (center part) immediately above each of the photoelectric conversion units 12 in the OB region 50 of the first light shielding film 15. ) And are removed and opened. However, the portions of the first light shielding film 15 that are directly above the photoelectric conversion units 12 in the invalid pixel region 90 are not removed and are not opened. Note that the first light shielding film 15 may be opened by removing all the portions immediately above the photoelectric conversion units 12 in the effective pixel region 30 and all the portions immediately above the photoelectric conversion units 12 in the OB region 50. Good. After this step, the photoresist R1 is removed to obtain the structure shown in FIG. 2C (from the step of forming the first light shielding film 15 in FIG. 2A to FIG. 2C). The process until the structure shown is obtained corresponds to the first light shielding film forming step).

  Next, as shown in FIG. 3A, an interlayer insulating film 16 is formed over the entire surface so as to fill up the gate insulating film 13 and the first light shielding film 15 (interlayer insulating film forming step). Next, a second light shielding film 17 is formed on the entire upper surface of the interlayer insulating film 16. The interlayer insulating film 16 is made of, for example, silicon oxide, and the second light shielding film 17 is made of, for example, metal.

  Next, as shown in FIG. 3B, a photoresist R <b> 2 is formed on the upper surface of the second light shielding film 17, avoiding the effective pixel region 30 and the invalid pixel region 90. Therefore, a photoresist R2 is formed on the upper surfaces of the second light shielding films 17 in the OB region 50 and the peripheral region 70.

  Next, the portion of the second light shielding film 17 where the photoresist R2 is not formed on the upper surface is removed by etching. Thereby, the second light shielding film 17 in the effective pixel region 30 and the invalid pixel region 90 is removed. However, the second light shielding film 17 in the OB region 50 and the peripheral region 70 remains without being removed. After this step, the photoresist R2 is removed to obtain the structure shown in FIG. 3C (from the step of forming the second light-shielding film 17 in FIG. 3A to FIG. 3C). The process until the structure shown is obtained corresponds to the second light shielding film formation step).

  The structure shown in FIG. 3C obtained by the above steps is different between the effective pixel region 30, the OB region 50, and the invalid pixel region 90. Specifically, the effective pixel region 30 has a structure in which light is incident because the photoelectric conversion unit 12 is not covered by the first light shielding film 15 and the second light shielding film 17. On the other hand, the OB region 50 has a structure in which the photoelectric conversion unit 12 is not covered with the first light shielding film 15 but is covered with the second light shielding film 17 so as to be shielded from light. The invalid pixel region 90 is not covered by the second light shielding film 17 but is covered by the first light shielding film 15 so as to be shielded from light.

  An example of the structure of a solid-state imaging device completed by providing an optical member or the like to the structure shown in FIG. 3C will be described with reference to the drawings. FIG. 4 is a cross-sectional view showing an example of the structure of the solid-state imaging device according to the embodiment of the present invention. FIG. 4 shows the same cross section as FIG. 2 and FIG.

  As shown in FIG. 4, in addition to the structure shown in FIG. 3C, the solid-state imaging device 1 is a flat surface that is entirely formed so as to fill up the interlayer insulating film 16 and the second light shielding film 17. A color filter 19 formed on the upper surface of the planarizing film 18 immediately above the photoelectric conversion unit 12 in the effective pixel region 30, and a color filter 19 directly above the photoelectric conversion unit 12 in the effective pixel region 30. And an on-chip lens 20 formed on the upper surface.

  The planarizing film 18 is made of, for example, silicon oxide or resin. The color filter 19 is made of, for example, a photosensitive resin containing a pigment, and selectively transmits light of a predetermined color (wavelength). The on-chip lens 20 is made of, for example, photosensitive resin, collects incident light, and transmits the light through the color filter 19. For example, the color filter 19 is formed by applying a photosensitive resin to the entire upper surface of the planarizing film 18 and then partially exposing it to light to make it photosensitive. Similarly, for example, the on-chip lens 20 is formed by applying a photosensitive resin to the entire upper surface of the color filter 19 and then partially irradiating it with light to expose it.

  Pixels including the charge storage region 12 and the color filter 19 and the on-chip lens 20 positioned immediately above the charge storage region 12 are arranged in a matrix along the substrate 11, for example. Specifically, for example, the pixels are arranged in a Bayer array when paying attention to the color transmitted through the color filter 19.

  In the solid-state imaging device 1, incident light is collected by the on-chip lens 20 and passes through the color filter 19. At this time, the color filter 19 selectively transmits light of a predetermined color (wavelength). The light transmitted through the color filter 19 is transmitted through the planarization film 18, the interlayer insulating film 16, and the gate insulating film 13 and enters the substrate 11. Then, light incident on the substrate 11 is photoelectrically converted by the photoelectric conversion unit 12 (and the surrounding region of the substrate 11), and a predetermined type of charge (electrons or holes) is accumulated in the photoelectric conversion unit 12.

  When a predetermined voltage is applied to the gate electrode 14 at a predetermined timing, the charge accumulated in the photoelectric conversion unit 12 is read out to the transfer region, and further, the charge is transferred (transfer in the vertical direction on the paper surface). Are performed sequentially. Then, a signal corresponding to the light incident on the photoelectric conversion unit 12 is obtained by amplifying the potential due to the charge transferred to the final stage.

  Similarly, charge is stored and transferred in the OB region 50 where no light is incident. However, the signal obtained by this operation indicates a noise component such as dark current. The solid-state imaging device 1 uses the difference between the signal based on the charge obtained from the photoelectric conversion unit 12 in the effective pixel region 30 and the signal based on the charge obtained from the photoelectric conversion unit 12 in the OB region 50. , Generate pixel data.

  In the solid-state imaging device 1, it is preferable that the planarizing film 18 has a small film thickness from the viewpoint of preventing color mixing and a decrease in sensitivity. However, if the thickness of the planarizing film 18 is reduced, it becomes difficult to sufficiently relax the step due to the provision of the second light shielding film 17 as shown in FIG.

  It is conceivable to solve this problem by shielding the photoelectric conversion unit 12 in the OB region 50 using the first light shielding film 15. However, in order to accurately detect a noise component similar to the noise component generated in the photoelectric conversion unit 12 in the effective pixel region 30 in the photoelectric conversion unit 12 in the OB region 50, the photoelectric conversion unit 12 in the OB region 50. It is necessary to make the structure around the same as the structure around the photoelectric conversion unit 12 in the effective pixel region 30. That is, in the OB region 50, like the effective pixel region 30, it is necessary to open the first light shielding film 15 immediately above the photoelectric conversion unit 12. Therefore, the light shielding of the photoelectric conversion unit 12 in the OB region 50 needs to be performed by the second light shielding film 17 provided at a position away from the photoelectric conversion unit 12.

  Therefore, in the solid-state imaging device 1, between the effective pixel region 30 where light is incident on the photoelectric conversion unit 12 and the OB region 50 where light is incident on the photoelectric conversion unit 12 by the second light shielding film 17, An invalid pixel region 90 is provided in which the first light shielding film 13, not the second light shielding film 17, blocks light from entering the photoelectric conversion unit 12. The solid-state imaging device 1 reduces the influence of the step of the second light-shielding film 17 formed in the OB area 50 in the invalid pixel area 90 between the effective pixel area 30 and the OB area 50, so that the influence is effective pixels. Suppressing reaching the region 30 is suppressed.

  Specifically, for example, the solid-state imaging device 1 causes the level difference of the planarization film 18 caused by providing the second light shielding film 17 to appear mainly in the invalid pixel region 90. Thereby, it is suppressed that a level | step difference arises in the planarization film | membrane 18 in the effective pixel area | region 30 (refer FIG. 4).

  Therefore, in the solid-state imaging device 1, an optical member (color filter 19, on-chip lens 20 or the like) formed on the OB region 50 side of the effective pixel region 30 is inclined, or the size of the optical member is greatly different from others. By suppressing this, it is possible to generate homogeneous image data.

  Further, the solid-state imaging device 1 only partially removes the first light shielding film 15 in the effective pixel region 30 and the OB region 50 and only removes the second light shielding film 17 in the effective pixel region 30 and the invalid pixel region 90. can get. That is, the solid-state imaging device 1 is manufactured without performing any special process only by adjusting the position where the first light shielding film 15 is removed and the position where the second light shielding film 17 is removed. Is possible. Therefore, the solid-state imaging device 1 can be easily manufactured.

  In the solid-state imaging device 1, the first light-shielding film 15 is formed immediately above the photoelectric conversion unit 12 in the invalid pixel region 90. Therefore, for example, when strong light is incident on the solid-state imaging device 1, it is possible to prevent light from leaking from the invalid pixel region 90 to the OB region 50.

  4 exemplifies the case where optical members such as the color filter 19 and the on-chip lens 20 are formed only in the effective pixel region 30, but the optical member is also formed in the invalid pixel region 90 and the OB region 50. May be. However, in the ineffective pixel region 90, it is expected that the optical member is formed to be inclined or may vary due to the size of the optical member being significantly different from the others. Therefore, the optical member formed in the invalid pixel region 90 may adversely affect the photoelectric conversion unit 12 in the effective pixel region 30 and the photoelectric conversion unit 12 in the OB region 50 (for example, light incident on the invalid pixel region 90 may be It is preferable to allow the formation of the optical member in the ineffective pixel region 90 only when there is no effective pixel region 30 or OB region 50).

<Deformation, etc.>
[1] The solid-state imaging device 1 shown in FIG. 4 includes only the on-chip lens 20, but may include an in-layer lens in addition to (or instead of) this. A method for forming this intra-layer lens will be described with reference to the drawings. FIG. 5 is a cross-sectional view illustrating an example of a method for manufacturing a solid-state imaging device according to another embodiment of the present invention. FIG. 5 shows a cross section similar to FIGS. FIG. 5 illustrates the case where the interlayer insulating film 16 is planarized in order to form the intralayer lens. However, the interlayer insulating film 16 does not have to be planarized unless particularly necessary.

  As shown in FIG. 5A, the second light-shielding film 17 is formed on the upper surface of the interlayer insulating film 16 in the OB region 50, as in the above-described method for manufacturing the solid-state imaging device 1 (see FIG. 3C). To do. Next, as shown in FIG. 5B, a lens material film 21 is formed so as to fill up the interlayer insulating film 16 and the second light shielding film 17.

  The lens material film 21 is the same as the planarization film 18 in the solid-state imaging device 1 described above in that the lens material film 21 is formed to fill up the interlayer insulating film 16 and the second light shielding film 17 (see FIG. 4). Therefore, the lens material film 21 also has a step in the invalid pixel region 90, but is flat in the effective pixel region 30 and has a uniform film thickness.

  The lens material film 21 is made of, for example, a photosensitive resin. For example, if the lens material film 21 is a negative type, the position where the intralayer lens in the effective pixel region 30 is to be formed is exposed and the unexposed portion is removed. Further, for example, if the lens material film 21 is a positive type, it is exposed except for the position where the intralayer lens in the effective pixel region 30 is to be formed, and the exposed portion is removed. By this step, the structure shown in FIG. 5C is obtained.

  Then, as shown in FIG. 5D, the inner lens 21A is formed by heating or exposing the remaining lens material film 21 to a shape that acts as a lens. Specifically, for example, as shown in FIG. 5D, an inner lens 21A is formed in which the interlayer insulating film 16 side is flat and the opposite side is convex. For example, when the interlayer insulating film 16 is not flattened, an intralayer lens having a convex shape on the interlayer insulating film 16 side may be formed.

  In the intra-layer lens 21A formed in this way, since the film thickness of the lens material film 21 in the effective pixel region 30 is uniform, the variation in height can be reduced. Specifically, for example, variation in the height of the in-layer lens 21A can be suppressed to 300 nm or less, so that sufficiently homogeneous image data can be generated.

  An example of the structure of a solid-state imaging device completed by providing an optical member or the like to the structure shown in FIG. 5D will be described with reference to the drawings. FIG. 6 is a cross-sectional view showing a structural example of a solid-state imaging device according to another embodiment of the present invention. FIG. 6 shows a cross section similar to FIG.

  A solid-state imaging device 1a illustrated in FIG. 6 includes a planarization film 18, a color filter 19, and an on-chip lens 20 in the same manner as the solid-state imaging device 1 illustrated in FIG. In addition, the manufacturing method of the planarization film | membrane 18, the color filter 19, and the on-chip lens 20 is the same as that of the solid-state image sensor 1 shown in FIG. However, the planarization film 18 in the solid-state imaging device 1a is formed so as to fill up the interlayer insulating film 16 on which the inner lens 21A is formed.

  In the solid-state imaging device 1a shown in FIG. 6 as well, the optical members (color filter 19, on-chip lens 20 and the like) formed on the OB region 50 side of the effective pixel region 30 are inclined as in the solid-state imaging device 1 shown in FIG. In addition, it is possible to generate homogeneous image data by suppressing the size of the optical member from being significantly different from the others.

  [2] Each of the gate insulating film 13, the gate electrode 14, the first light shielding film 15, the interlayer insulating film 16, the second light shielding film 17, the planarizing film 18, the color filter 19, the on-chip lens 20, the lens material film 21, and the like. This film may be a single-layer film or a multi-layer film. Further, any film may be added between the interlayer insulating film 16 and the second light shielding film 17 and the planarizing film 18 or between the second light shielding film 17 and the lens material film 21.

  [3] Although a CCD image sensor has been described as an example of the solid-state image sensor 1, the present invention can also be applied to other solid-state image sensors such as a CMOS image sensor.

  The present invention can be suitably used for a solid-state imaging device including a light-shielded photoelectric conversion unit.

DESCRIPTION OF SYMBOLS 1, 1a: Solid-state image sensor 11: Substrate 12: Photoelectric conversion part 13: Gate insulating film 14: Gate electrode 15: 1st light shielding film 16: Interlayer insulating film 17: 2nd light shielding film 18: Flattening film 19: Color filter 20: On-chip lens 21: Lens material film 21A: In-layer lens 30: Effective pixel region (first region)
50: OB area (second area)
70: peripheral area 90: invalid pixel area (third area)

Claims (7)

A substrate,
A plurality of photoelectric conversion units that generate charges by photoelectrically converting incident light formed inside the substrate; and
A first light shielding film that is formed above the substrate and blocks light incident on the photoelectric conversion unit;
A second light-shielding film that is formed above the first light-shielding film and shields light incident on the photoelectric conversion unit,
A first region where light is incident because the photoelectric conversion unit is not covered by the first light-shielding film and the second light-shielding film;
A second region that is shielded by being covered by the second light shielding film without being covered by the first light shielding film,
A third region that is located between the first region and the second region, and the photoelectric conversion unit is not covered by the second light shielding film and is shielded by the first light shielding film;
A solid-state imaging device, wherein: An interlayer insulating film formed over the entire surface so as to fill the upper portion of the first light shielding film and the upper portion of the photoelectric conversion portion not covered by the first light shielding film;
An intralayer lens that is formed immediately above the photoelectric conversion unit in the first region and collects incident light on the photoelectric conversion unit;
The solid-state imaging device according to claim 1, wherein the second light shielding film and the inner lens are formed on an upper surface of the interlayer insulating film. An interlayer insulating film formed over the entire surface so as to fill the upper portion of the first light shielding film and the upper portion of the photoelectric conversion portion not covered by the first light shielding film;
A planarization film formed entirely to fill up the interlayer insulating film and the second light shielding film;
A color filter that is formed on an upper surface of the planarizing film directly above the photoelectric conversion unit in the first region and selectively transmits light of a predetermined wavelength;
An on-chip lens that is formed on an upper surface of the color filter that is directly above the photoelectric conversion unit in the first region, and that collects incident light and transmits the color filter;
The solid-state imaging device according to claim 1, further comprising: Forming a first light-shielding film that forms a first light-shielding film that blocks light incident on the photoelectric conversion unit above a substrate on which a plurality of photoelectric conversion units that generate charges by photoelectrically converting incident light are formed. Steps,
A second light shielding film forming step for forming a second light shielding film for shielding light incident on the photoelectric conversion unit above the first light shielding film;
By the first light shielding film forming step and the second light shielding film forming step,
A first region where light is incident because the photoelectric conversion unit is not covered by the first light-shielding film and the second light-shielding film;
A second region that is shielded by being covered by the second light shielding film without being covered by the first light shielding film,
A third region that is located between the first region and the second region, and the photoelectric conversion unit is not covered by the second light shielding film and is shielded by the first light shielding film;
A method for manufacturing a solid-state imaging device, comprising: providing a solid-state imaging device. In the first light-shielding film forming step, after the first light-shielding film is formed over the entire surface, the part of the first region and the second region that are part or all of the photoelectric conversion unit immediately above each of the first region and the second region. Removing the first light-shielding film simultaneously;
5. The method according to claim 4, wherein, in the second light shielding film forming step, after the second light shielding film is formed over the entire surface, the second light shielding film in the first region and the third region is simultaneously removed. The manufacturing method of the solid-state image sensor of description. Between the first light-shielding film forming step and the second light-shielding film forming step, the upper part of the first light-shielding film and the upper part of the photoelectric conversion unit not covered by the first light-shielding film are filled. An interlayer insulating film forming step for forming an interlayer insulating film over the entire surface,
After the second light shielding film formation step, a lens material film is formed over the entire surface so as to fill up the interlayer insulating film and the second light shielding film formed on the upper surface of the interlayer insulating film. A lens material film forming step;
By processing the lens material film, an in-layer lens that collects incident light on the photoelectric conversion unit is formed on the upper surface of the interlayer insulating film that is directly above the photoelectric conversion unit in the first region. An intra-layer lens forming step,
The method for manufacturing a solid-state imaging device according to claim 4, further comprising: Between the first light-shielding film forming step and the second light-shielding film forming step, the upper part of the first light-shielding film and the upper part of the photoelectric conversion unit not covered by the first light-shielding film are filled. An interlayer insulating film forming step for forming an interlayer insulating film over the entire surface,
After the second light shielding film formation step, a planarization film formation step of forming a planarization film on the entire surface so as to fill up the interlayer insulating film and the second light shielding film;
A color filter forming step of forming a color filter that selectively transmits light of a predetermined wavelength on the upper surface of the flattening film immediately above the photoelectric conversion unit in the first region after the flattening film forming step; ,
An on-chip lens forming step of forming an on-chip lens that collects incident light and transmits the color filter on an upper surface of the color filter that is directly above the photoelectric conversion unit in the first region;
The solid-state imaging device manufacturing method according to claim 4, further comprising:

Images