JP2009027132A - Solid-state imaging device and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state imaging device of high image quality which has a high sensitivity and is capable of coping with finer pixels for increasing the number of pixels and of operating at a high speed, and a method for manufacturing the same. <P>SOLUTION: The solid-state imaging device is provided with a plurality of photoelectric conversion portions 1 arranged in a matrix on a substrate, vertical transfer channels 2 arranged between vertical columns of the photoelectric conversion portions 1, a plurality of vertical transfer electrodes 11 for transferring charges of the photoelectric conversion portions 1 to the vertical transfer channels 2, a light-shielding film 13 that is laminated on the vertical transfer electrodes 11 via a first insulating film and has a plurality of window portions defining light-receiving portions of the photoelectric conversion portions 1, and shunt wiring 14 that is arranged in regions overlapping the vertical transfer channels and is insulated from the light-shielding film 13 by a second insulating film. A driving pulse according to a drive phase of each of the vertical transfer electrodes 11 is supplied from the shunt wiring 14. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device, and more particularly to a solid-state imaging device that applies a driving pulse to a vertical transfer electrode via a shunt wiring and a manufacturing method thereof, and relates to a shape of a light shielding film and a connection method between the shunt wiring and the vertical transfer electrode. Is.

  In recent years, the demand for solid-state imaging devices is expanding as imaging devices for digital still cameras and digital video cameras. In addition, it is required to add a camera function to a mobile terminal device represented by a mobile phone, and the demand for solid-state imaging devices is increasing. As the demand for solid-state imaging devices increases, the demand for higher image quality has also increased. In order to improve the image quality of a solid-state imaging device, it is necessary to both increase the number of pixels and increase the sensitivity to increase the S / N ratio.

  In order to increase the number of pixels in a solid-state imaging device, it is necessary to increase the operating speed of the solid-state imaging device. In order to increase the operation speed in a CCD (Charge Coupled Device) type solid-state imaging device, it is necessary to transfer signal charges from the imaging unit to the charge storage unit at high speed.

  In order to increase the charge transfer speed, it has been proposed to connect the corresponding vertical transfer electrodes in common with a shunt wiring that also serves as a light shielding film, in order to reduce the influence of the electrical resistance value of the vertical transfer electrodes. ing. Here, an aluminum film suitable for use as a shunt wiring also serving as a light shielding film is often formed on a planarization film because it is difficult to form the aluminum film on a stepped portion. On the other hand, when a light shielding film is formed on the planarizing film, it is necessary to prevent the occurrence of smear due to obliquely incident light that cannot be shielded. For this reason, in addition to the shunt wiring that also serves as a light shielding film made of an aluminum film, a technique is disclosed in which another light shielding film made of a refractory metal such as tungsten is formed so as to cover the side wall portion of the vertical transfer electrode. (Patent Document 1).

  FIG. 12 is an enlarged view of the planar configuration of the imaging unit of this conventional solid-state imaging device. 13 is an enlarged cross-sectional view of a portion where a shunt wiring also serving as a light-shielding film in a conventional solid-state imaging device is formed. FIG. 13A is a a-a portion of FIG. 12, and FIG. Shows the cross-sectional structure of the bb portion of FIG.

  As shown in FIGS. 12 and 13, the imaging unit of the conventional solid-state imaging device is adjacent to the plurality of photoelectric conversion units 101 formed in a matrix on the semiconductor substrate 122 in the row direction, that is, the left-right direction in FIG. 12. A plurality of vertical transfer channels 102 formed so as to extend in the column direction, that is, the vertical direction in FIG.

  A pair of vertical transfer electrodes 111A and 111B extending in the row direction are formed so as to sandwich the photoelectric conversion unit 101 from the column direction. The vertical transfer electrodes 111A and 111B have downward and upward protruding portions in FIG. 12, respectively, in the portion between the vertical columns of the photoelectric conversion portion, that is, the region where the vertical transfer channel 102 is formed. Are overlapped via an insulating film (not shown).

  One light-shielding film 113A is formed so as to cover the protruding portion of the vertical transfer electrodes 111A and 111B in the vicinity of the end of the left side portion in FIG. 12 and the side wall portion, and the protruding portion of the vertical transfer electrodes 111A and 111B. The other light shielding film 113B is formed so as to cover the vicinity of the end portion of the right side portion and the side wall portion in FIG. Note that a first insulating film 115 is formed between the vertical transfer electrode 111 and the light shielding film 113.

  A shunt wiring 114 also serving as a light shielding film is formed on the light shielding film 113 so as to cover the vertical transfer channel 102 via the second insulating film 116. The shunt wirings 114 also serving as light shielding films are connected to the corresponding vertical transfer electrodes 111 and the contact portions 121, respectively. The contact portion 121 is made of the same metal material as the shunt wiring 114 that also serves as a light shielding film, and is formed simultaneously with the shunt wiring 114 by sputtering.

  In the example shown in FIG. 12, the vertical transfer electrode 111B disposed on the lower side of the photoelectric conversion unit 101 on the upper center side in the figure is connected to the shunt wiring 114 that also serves as a light shielding film on the right side in the figure. A vertical transfer electrode 111A disposed on the upper side of the lower photoelectric conversion unit 101 is connected to a shunt wiring 114 also serving as a light shielding film on the left side in the drawing. Note that a drive pulse for transferring charges obtained by performing photoelectric conversion is directly applied to the vertical transfer electrode 111.

In such a conventional solid-state imaging device, the shunt wiring 114 also serving as a light-shielding film is electrically connected to the corresponding vertical transfer electrode 111 by the contact portion 121. Therefore, the shunt wiring serves as a pulse transmission line. By contributing to lowering the resistance of the vertical transfer electrode, the signal charge is propagated particularly in the central portion of the solid-state imaging device as compared with the case where the drive pulse for photoelectric conversion and charge transport is applied using only the vertical transfer electrode 111. Delay can be suppressed. Thereby, a solid-state imaging device that operates at high speed can be realized.
JP-A-5-243537

  However, although the above-described conventional solid-state imaging device enables high-speed operation, the contact portion formed at the same time as the light-shielding film 113 and the shunt wiring 114 that also serves as the light-shielding film as the pixels are miniaturized. There arises a problem with the breakdown voltage with respect to 121.

  That is, the electric withstand voltage between the light shielding film 113 and the contact portion 121 is defined by the interval between these two metal members, and the portion with the smallest interval becomes a problem. For example, as shown in FIG. 13B, when the intervals on the right side and the left side of the drawing are t1 and t2, respectively, in the case of FIG. 13B, since t1 <t2, the left side of the vertical transfer electrode 111 The distance between the one light-shielding film 113 </ b> A and the contact part 121 is a problem.

  Here, as described above, since the contact portion 121 is manufactured by the sputtering method or the like simultaneously with the shunt wiring 114 that also serves as a light shielding film, the accuracy of the formation position is constant due to variations in the manufacturing process. There is a limit. However, if an attempt is made to secure a design dimension that can absorb variations in the manufacturing process, the area of the light receiving portion is reduced, resulting in a decrease in effective sensitivity and a decrease in S / N. Further, in order to secure the light receiving area, the pixel size must be increased, and the pixels cannot be miniaturized, which is contrary to the demand for higher pixels required for solid-state imaging devices.

  Furthermore, although the conventional solid-state imaging device reduces the electrical resistance value by joining the vertical transfer electrode with the shunt wiring, the signal for charge transfer is applied from the vertical transfer electrode. The path through which the charge transfer signal passes through the vertical transfer electrode cannot be shortened, and sufficient high-speed operation cannot be ensured.

  The present invention solves the above-mentioned conventional problems, and obtains a high-quality solid-state imaging device capable of high-speed operation that can cope with pixel miniaturization with high sensitivity and high pixels, and a method for manufacturing the same. With the goal.

  In order to solve the above-described problem, a solid-state imaging device of the present invention includes a plurality of photoelectric conversion units arranged in a matrix on a substrate, a vertical transfer channel arranged between vertical columns of the photoelectric conversion units, A plurality of vertical transfer electrodes for transferring the charge of the photoelectric conversion unit to the vertical transfer channel, and a plurality of light receiving units of the photoelectric conversion unit stacked on the vertical transfer electrode via a first insulating film A light shielding film having a window portion, and a shunt wiring disposed in a region overlapping with the vertical transfer channel, wherein the light shielding film is insulated by a second insulating film, and each driving phase of the vertical transfer electrode The drive pulse corresponding to is supplied from the shunt wiring.

  In addition, the method for manufacturing a solid-state imaging device according to the present invention includes a plurality of photoelectric conversion units arranged in a matrix on a substrate, vertical transfer channels arranged between vertical columns of the photoelectric conversion units, and a horizontal direction. A plurality of window portions that define a vertical transfer electrode connected to the plurality of photoelectric conversion units arranged in a row and a light receiving unit of the photoelectric conversion unit stacked on the vertical transfer electrode via a first insulating film. A solid-state imaging device including: a light-shielding film having a shunt wiring disposed in a region overlapping with the vertical transfer channel, wherein the light-shielding film is insulated by a second insulating film; Forming an opening having a predetermined shape in a region overlapping the vertical transfer channel by etching the second insulating film, the light shielding film, and the first insulating film after forming an insulating film; Forming an insulating film; Forming a sidewall in the opening by performing anisotropic etching on the edge film; and forming the shunt wiring together with a leg portion extending in a thickness direction of the edge film; And a step of connecting the vertical transfer electrode.

  According to the solid-state imaging device and the manufacturing method thereof according to the present invention, the drive pulse is applied to the vertical transfer electrode from the shunt wiring formed on the light-shielding film that defines the light-receiving unit of the photoelectric conversion unit. The influence of electrical resistance on the drive signal pulse can be greatly reduced. In addition, since the shunt wiring is formed on the second insulating film, electrical interference between the shunt wiring and another metal thin film can be suppressed, and the margin in the manufacturing process of the light shielding film and the shunt wiring is minimized. It becomes possible to do. As a result, it is possible to obtain a high-quality solid-state imaging device capable of high-speed operation that is highly sensitive and can cope with pixel miniaturization for increasing the number of pixels.

  In the above-described solid-state imaging device of the present invention, the vertical transfer electrode is connected to the plurality of photoelectric conversion units arranged in the horizontal direction, and the shunt wiring and the vertical transfer electrode are integrated with the shunt wiring and have a thickness thereof. It is preferable to be connected by legs extending in the vertical direction.

  By doing so, the connection between the shunt wiring and the vertical transfer electrode can be easily and reliably realized.

  Further, the light shielding film is also formed in a region overlapping with the shunt wiring except for a connection opening through which the leg penetrates, and the connection opening is a circle, an ellipse, or a rectangle. It is preferable that it is any one shape of these.

  By doing so, it is possible to effectively prevent undesired leakage of external light incident on the photoelectric conversion unit.

  Furthermore, it is preferable that the said leg part is located in the center of the said connection part opening.

  By doing so, it is possible to reliably prevent electrical interference between the shunt wiring and the light shielding film.

  Furthermore, the light shielding film is divided for each vertical column of the photoelectric conversion unit by a slit unit formed in a region overlapping with the vertical transfer channel, and is continuously formed along the arrangement direction of the shunt wiring. It is preferable that the leg portion enters the slit portion.

  By doing in this way, film | membrane peeling of a shunt wiring can be prevented.

  Moreover, it is preferable that a sidewall is formed on a side surface of the connection portion opening of the light shielding film or a longitudinal side surface of the slit portion.

  By doing in this way, a leg part integral with shunt wiring can be easily formed in a predetermined place.

  Moreover, it is preferable that a stopper layer laminated on the vertical transfer electrode is provided in a region other than a connection portion between the shunt wiring and the vertical transfer electrode on the bottom surface of the slit portion.

  By doing so, it is possible to easily and surely prevent undesired connection between the shunt wiring and the vertical transfer electrode that do not correspond to each other.

  Further, it is preferable that an antireflection film made of the same material as that of the stopper layer is formed on the light receiving portion, and that the vertical transfer electrode has a single layer structure.

  In the method for manufacturing a solid-state imaging device according to the present invention, the opening is in any one shape of a circle, an ellipse, and a rectangle, and the opening is in the direction in which the vertical transfer channel is formed. It is preferable that it is the slit shape extended in this. Furthermore, it is preferable that the first insulating film is a multilayer film in which a silicon nitride film is laminated on a silicon oxide film.

  Hereinafter, embodiments of the solid-state imaging device of the present invention will be described with reference to the drawings.

(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view illustrating a main configuration of an imaging unit in the solid-state imaging device according to the first embodiment of the present invention. 2A is a schematic diagram showing a cross-sectional configuration taken along the line AA in FIG. 1, and FIG. 2B is a schematic diagram showing a cross-sectional configuration of the portion similarly shown as the BB line in FIG. FIG.

  As shown in FIGS. 1 and 2, in the imaging unit of the solid-state imaging device according to the present embodiment, photoelectric conversion units 1 made of photodiodes are formed in a matrix on a semiconductor substrate 22. That is, a vertical transfer channel 2 that is an impurity diffusion layer is formed in a portion between the photoelectric conversion units 1 arranged in the left-right direction.

  On the surface oxide film 12 formed on the surface of the semiconductor substrate 22, the vertical transfer electrode 11 made of polysilicon for transferring the electric charge obtained in the photoelectric conversion unit 1 to the vertical transfer channel 2 is arranged horizontally in the photoelectric conversion unit 1. It is formed in a portion between rows, that is, a portion between the photoelectric conversion units 1 arranged in the vertical direction. The vertical transfer electrode 11 is connected to a plurality of photoelectric conversion units.

  In the present embodiment, the vertical transfer electrode 11 includes a first vertical transfer electrode 11A formed on the upper horizontal parallel portion of the corresponding photoelectric conversion unit 1 in FIG. 1 and a lower side of the corresponding photoelectric conversion unit 1 in FIG. And the second vertical transfer electrode 11 </ b> B formed in the horizontal parallel portion are provided side by side so as to sandwich the photoelectric conversion unit 1. In addition, in the vertical column portion of the photoelectric conversion unit 1 of the vertical transfer electrode 11, the first vertical transfer electrode 11A corresponds to the photoelectric conversion unit 1 positioned on the lower side in FIG. 1 and the second vertical transfer electrode 11B. Are formed with projecting portions projecting so as to wrap the corresponding photoelectric conversion portions 1 located on the upper side in FIG. Note that the vertical transfer channel 2 and the vertical transfer electrode 11 form a vertical transfer register that reads out the charges of the photoelectric conversion unit 1 and transfers them in the vertical column direction. Of course, the overlapping portion of the first vertical transfer electrode 11A and the second vertical transfer electrode 11B is interposed with an insulating layer therebetween, and the two vertical transfer electrodes are not electrically connected to each other.

  A light shielding film 13 made of tungsten (W) is formed on the first insulating film 15 formed on the vertical transfer electrode 11. In the solid-state imaging device according to the present embodiment, even in a region where a shunt wiring 14 described later is formed, other than the connection opening 17 through which the leg 21 for connecting the shunt wiring 14 and the vertical transfer electrode 11 passes. The light shielding film 13 is formed in the portion. Moreover, the window part 3 which is opening of a predetermined shape is formed in the part corresponding to each photoelectric conversion part 1 of the light shielding film 13. That is, in the solid-state imaging device according to the present embodiment, the light shielding film 13 is formed so as to cover almost the entire imaging region where the photoelectric conversion unit 1 of the solid-state imaging device is formed, except for the window portion. In addition, the window part 3 of the light shielding film 13 defines the light receiving part of the photoelectric conversion part 1.

  A second insulating film 16 is formed on the light shielding film 13 and overlaps with the vertical transfer channel 2 on the second insulating film 16, that is, a portion corresponding to a vertical column portion of the photoelectric conversion unit 1. A shunt wiring 14 made of tungsten (W) is formed. The shunt lines 14 are connected to the corresponding vertical transfer electrodes 11 and supply drive pulses to the vertical transfer electrodes 11.

  For example, in the solid-state imaging device shown in FIG. 1, the shunt wiring 14 on the right side in the drawing is a connection portion with the second vertical transfer electrode 11 </ b> B located on the lower side of the photoelectric conversion unit 1 shown at the upper center in the drawing. The legs 21 are connected. Further, the shunt wiring 14 on the left side in the figure is connected to the first vertical transfer electrode 11A located on the upper side in the figure of the photoelectric conversion unit 1 shown on the lower center side in the figure by the leg part 21 which is a connection part. Yes. In this way, different shunt lines are connected to different vertical transfer electrodes 11, and the vertical transfer electrode 11 is driven by applying a vertical drive pulse to the vertical transfer electrode 11 through the shunt line 14, and the charge from the photoelectric conversion unit 1. Read and transfer of charges in the column direction. Note that the set of connections between the shunt wiring 14 and the inter-vertical transfer electrode 11 varies depending on the driving phase of the solid-state imaging device. For example, in the case of four-phase driving, four adjacent shunt lines are connected to different vertical transfer electrodes.

  An upper interlayer insulating film, a color filter, an on-chip lens, and the like are further formed on the shunt wiring 14, but since it has the same configuration as that of a normal solid-state imaging device, the description and illustration thereof will be given here. Omitted. Note that the width direction of the shunt wiring 14, that is, the dimension in the row direction of the solid-state imaging device is the same as or smaller than the dimension of the light shielding film 13 formed between the vertical columns of the photoelectric conversion unit 1. The light entering the light receiving portion is not blocked by the wiring 14.

  Next, a connection portion between the shunt wiring 14 and the vertical transfer electrode 11 will be described.

  As shown in FIGS. 1 and 2B, a connection portion opening 17 having a substantially square shape is formed in the light shielding film 13 at the connection portion between the shunt wiring 14 and the vertical transfer electrode 11B. Leg portions 21 are provided so as to penetrate the shunt wiring 14 and extend in the thickness direction of the shunt wiring, that is, in the vertical direction of FIG. As is clear from FIG. 2B, the leg portion 21 penetrates through the first insulating film 15 and the second insulating film 16 and contacts the second vertical transfer electrode 11B. Electrical continuity with the wiring 14 is intended.

  Here, in order to prevent the leg portion 21 and the light shielding film 13 from being brought into contact with each other, it is preferable that the leg portion 21 is positioned at the center of the connection portion opening 17 of the light shielding film 13. . The second insulating film 16 is formed in the conductive portion opening 17 of the light shielding film 13. However, if the distance between the leg portion 21 and the light shielding film 13 is too close, the second insulating film 16 is present. There is a risk of electrical continuity between the two. Since this electrical continuity occurs at the portion where the distance between the light shielding film 13 and the leg portion 21 is the narrowest, the distance between the leg portion 21 and the light shielding film 13 is determined by positioning the leg portion 21 at the center of the connection opening 17. This is because the interval in the portion where the minimum value can be made the maximum value.

  Considering a specific operation situation of the solid-state imaging device according to the present embodiment, the light shielding film 13 is grounded to GND (0 V), and the leg portion 21 of the shunt wiring 14 is connected to the vertical transfer electrode. As a pulse for vertical transfer, High: 0 V, Low: −6 V, and 12 V applied at the time of reading are applied. Therefore, the withstand voltage required between the light shielding film 13 and the leg portion 21 is 12 V or more. Here, if the breakdown voltage of the second insulating film 16 is 2 MV / cm, it can be seen that the film thickness, that is, the distance between the light shielding film 13 and the leg 21 needs to be 60 nm or more.

  As described above, in order to secure the space between the light shielding film 13 and the leg portion 21, it is preferable to position the leg portion 21 at the center of the connection opening 17 of the light shielding film 13. It is effective to form sidewalls inside the 13 connection openings 17. Therefore, hereinafter, a method of forming a sidewall on the inner wall portion of the connection opening 17 of the light shielding film 13 and forming the shunt wiring 14 and the leg 21 integrally after forming the sidewall will be described with reference to FIG. 3 and FIG. In the following description, specific numerical values such as the film thickness of the light shielding film 13 and the insulating film that affects the insulation between the shunt wiring 14 and the leg portion 21 will be exemplified.

  3 and 4 are cross-sectional configuration diagrams illustrating a method of manufacturing a solid-state imaging device according to the present invention. 3 (a) and 3 (c), FIG. 4 (a), FIG. 4 (c), and FIG. 4 (e) are connected portions between the shunt wiring 14 and the second vertical transfer electrode 11B. The cross-sectional structure of the AA line part in FIG. 1 which is a part which is not is shown. 3 (b) and 3 (d), FIG. 4 (b), FIG. 4 (d), and FIG. 4 (f) are connected portions between the shunt wiring 14 and the second vertical transfer electrode 11B. The cross-sectional structure of the BB line part in FIG. 1 in which the leg part 21 is formed is shown.

  In the state of FIG. 3A and FIG. 3B, up to the second insulating film 16 has already been formed. That is, a photoelectric conversion unit (not shown) is formed on the semiconductor substrate 22 and a vertical transfer channel 2 is formed between vertical columns of the photoelectric conversion unit, and the vertical transfer electrode 11 ( 11B) is formed in a predetermined pattern, and the first insulating film 15, the light shielding film 13 in which the window 3 is formed, and the second insulating film 16 are formed. In the present embodiment, the thickness of the second insulating film 16 is 100 nm.

  Then, as shown in FIGS. 3A and 3B, a resist film 23 is formed on the second insulating film 16, and the resist film 23 is formed as shown in FIG. 3B. Further, as a connection portion between the shunt wiring 14 and the vertical transfer electrode 11, a portion where the connection portion opening 17 of the light shielding film 13 is formed later is patterned and removed. In the present embodiment, the size of the extracted pattern of the resist film 23 is, for example, 300 nm square. For this reason, this patterning can be easily performed by using an exposure mask by a commonly used photolithography method.

  Next, as shown in FIGS. 3C and 3D, by using the resist film 23 as a mask, the second interlayer insulating film 16, the light shielding film 13, and the first interlayer insulating film are used. An opening is formed in the film 15.

  Thereafter, as shown in FIGS. 4A and 4B, the resist film 23 is removed. Here, the opening formed in the light shielding film 13 becomes the connection portion opening 17 of the light shielding film 13.

  Next, as shown in FIGS. 4C and 4D, a third insulating film 18 made of a silicon oxide film is formed. In the present embodiment, the thickness of the third insulating film 18 is 100 nm.

  Then, by performing anisotropic etching on the third insulating film 18, as shown in FIGS. 4E and 4F, the portion of the light shielding film 13 where the connection opening 17 is formed is formed. Sidewalls 19 are formed on the inner wall and the inner wall of the second insulating film 16 that surrounds the light receiving portion.

  Then, as shown in FIG. 4 (f), a shunt wiring 14 is formed by forming a tungsten (W) film by sputtering or a combination of sputtering and CVD and processing it to a desired width.

  At this time, in the portion of the connection opening 17 formed in the light shielding film 13, the side wall 19 is formed on the side wall portion of the portion where the second insulating film 16, the light shielding film 13, and the first insulating film 15 are laminated. Is formed. The thickness of the side wall 19 is slightly smaller than the thickness of the third insulating film of 100 nm, but the minimum thickness of 60 nm or more discussed above can be sufficiently secured. The side wall 19 makes it easy for the tungsten film to enter because the shape of the overall opening is a hollow with the upper part widened. The size of the opening after the side wall 19 is formed is the size obtained by subtracting two film thicknesses of the side wall 19 having a film thickness of less than 100 nm from the size of the blank pattern formed in the resist film. Thus, at least a size of 100 nm square or more can be secured. For this reason, the leg 21 formed simultaneously with the shunt wiring 14 can easily reach the vertical wiring electrode 11. Therefore, the connection between the shunt wiring 14 and the vertical transfer electrode 11 can be reliably performed, and the occurrence of a problem that a contact resistance is generated between the shunt wiring 14 and the light shielding film 13 can be reliably avoided. Although the thickness of the second insulating film 16 becomes thinner than the initial 100 nm due to overetching when forming the sidewalls 19, the film thickness etched by this overetching is controlled to 40 nm or less. It is easy. For this reason, even if over-etching at the time of forming the sidewalls 19 is taken into consideration, the thickness of the second insulating film 16 can be secured to 60 nm or more, so that the breakdown voltage between the light-shielding film 13 and the shunt wiring 14 can be secured. There is no problem.

  As described above, by forming the sidewalls 19, the electrical insulation between the light shielding film 13 and the leg portions 21 formed simultaneously with the shunt wiring 14 can be achieved by separating the light shielding film 13 and the leg portions 21. That is, it is determined by the thickness of the sidewall 19 formed by etching the third insulating film 18. Since the thickness of the sidewall 19 formed in the connection opening 17 can be adjusted by controlling the thickness of the third insulating film 18, it is possible to ensure the necessary thickness without being affected by the lithography processing accuracy. it can. Further, it is not necessary to consider a margin for alignment of the connection portion between the shunt wiring 14 and the vertical transfer electrode 11, and the size of the light receiving portion can be sufficiently increased. Can be improved.

  Furthermore, in general, in wiring processing, if there is a step, an etching remaining in the step portion is likely to occur. However, by forming the sidewall 19 as shown as the manufacturing method of the solid-state imaging device of the present embodiment, Therefore, the uneven level difference is alleviated. For this reason, it is possible to eliminate the need for excessive addition of etching to prevent processing residue. As a result, etching damage caused by excessive etching is alleviated. Therefore, as shown in the present embodiment, the sidewall 19 is also formed on the inner wall of the second insulating film 16 around the light receiving portion, thereby receiving light. An effect of reducing image quality defects such as occurrence of white flaws in the portion can be obtained.

  The second insulating film 16 has a two-layer structure in which a silicon nitride film is stacked on the silicon oxide film, thereby forming the sidewall 19 using the third insulating film 18 that is a silicon oxide film. In this case, the silicon nitride film is preferable because it can be used as an etching stopper for anisotropic etching.

  Moreover, as shown in FIG. 1, the connection part opening 17 in this embodiment was made into the substantially square shape, However, it is not restricted to this, As shown to Fig.5 (a), rectangular shape containing a rectangle, In addition, it goes without saying that an ellipse or oval shape shown in FIG. 5B or a circular shape shown in FIG. In particular, when the opening shape of the connection opening 17 has a longitudinal direction and a short direction, such as a rectangle shown in FIG. 5A, an ellipse shown in FIG. 5B, or an oval shape, It is preferable that the longitudinal direction of the connection opening 17 is substantially parallel to the direction in which the vertical transfer electrodes 11A or 11B to be connected are formed. Thus, by aligning the longitudinal direction of the connection opening 17 with the direction in which the vertical transfer electrode 11 is formed, a margin when forming the connection opening 17 can be increased, and an undesired short circuit is less likely to occur. Reliability can be improved. In addition, since the area of the connection portion between the shunt wiring 14 and the vertical transfer electrode 11 is increased and the electrical resistance is lowered, the effect of increasing the speed of the solid-state imaging device is exhibited.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 6 is a plan view illustrating the main configuration of the imaging unit in the solid-state imaging device according to the second embodiment of the present invention. 7A is a schematic diagram showing a cross-sectional configuration taken along the line CC of FIG. 6, and FIG. 7B is a schematic diagram showing a cross-sectional configuration of a portion similarly shown as a DD line in FIG. FIG. The solid-state imaging device according to the second embodiment of the present invention shown in FIGS. 6 and 7 is basically the same as the solid-state imaging device according to the first embodiment shown in FIGS. The same. Therefore, common parts are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIGS. 6 and 7, in the solid-state imaging device of the present embodiment, a slit portion 24 is formed along the formation direction of the vertical transfer channel 2 in the light shielding film 13 on the vertical transfer channel 2. Further, a leg portion 21 that is integral with the shunt wiring 14 and extends in the thickness direction thereof is formed continuously in the length direction of the shunt wiring 14, that is, the formation direction of the shunt wiring 14 (vertical direction in FIG. 6). Thus, the leg 21 enters the slit 24 of the shielding film 13.

  Further, a stopper layer 20 made of a nitride film is formed on the vertical transfer electrode 11 corresponding to the bottom of the slit portion 24 of the shielding film 13 except for the connection portion between the shunt wiring 14 and the vertical transfer electrode 11. . By appropriately setting the film thickness of the stopper layer 20 in relation to the amount of over-etching when the sidewall 19 is formed, the electrical insulating layer between the leg 21 of the shunt wiring 14 and the vertical transfer electrode 11 is set. Can play a role. For this reason, in the portion other than the connection portion between the shunt wiring 14 and the vertical transfer electrode 11 where the stopper layer 20 is formed, electrical conduction between the two can be prevented. In general, the selection ratio between the third insulating layer 18 that is an oxide film and the stopper layer 20 that is a nitride film can be 10 or more. As described in the first embodiment, since the overetching amount when forming the sidewall 19 is set to 40 nm or less, the film thickness of the stopper layer 20 when the sidewall 19 is formed is set to 4 nm or less. Can do. Therefore, if the initial film thickness of the stopper layer 20 is 50 nm, a film thickness of 40 nm or more can be ensured even if overetching is performed. Here, since the breakdown voltage of the nitride film is 1.5 times or more than the breakdown voltage of the oxide film, the 40 nm nitride film corresponds to the 60 nm oxide film, and the above-described minimum necessary film thickness is ensured. Because it becomes.

  For this reason, even if the leg portion 21 integrated with the shunt wiring 14 is shaped to enter the slit portion 24 formed in the light shielding film 13, the shunt wiring 14 and the vertical transfer electrode 11 are intended at the connection portion. Since only electrically connected ones are electrically connected to each other, each drive phase is transferred from the shunt wiring 14 to a predetermined vertical transfer electrode as in the solid-state imaging device shown in the first embodiment. It is possible to adopt a structure in which a drive pulse corresponding to is applied. As a result, the charge can be read from the photoelectric conversion unit 1 without being affected by the magnitude of the electric resistance of the vertical transfer electrode 11.

  In the solid-state imaging device according to the present embodiment, the leg portion 21 integral with the shunt wiring 14 is formed over the entire length direction of the shunt wiring 14. For this reason, when considering the shunt wiring 14 as a whole including the leg portion 21, it is the same as increasing the film thickness of the shunt wiring 14, and the resistance value of the shunt wiring 14 can be lowered. Therefore, the loss of the drive pulse applied to the vertical transfer electrode 11 as appropriate can be significantly suppressed, and the power consumption of the solid-state imaging device can be reduced. Further, by utilizing the small resistance value of the shunt wiring 14, higher speed driving can be realized.

  Furthermore, since the leg portion 21 integral with the shunt wiring 14 has a shape to bite into the slit portion 24 formed in the light shielding film 13, an effect of preventing the film separation of the shunt wiring 14 can be obtained.

  In the solid-state imaging device according to the present embodiment, the leg portion 21 and the light shielding film 13 are arranged in the width direction perpendicular to the length direction of the slit portion 24, that is, in the horizontal direction in FIGS. 7 (a) and 7 (b). Only the direction will be close. For this reason, in order to avoid contact between the two, it is important that the leg portion 21 is positioned at the center in the width direction of the slit portion 24. As described above, in order to avoid contact between the leg portion 21 integral with the shunt wiring 14 and the light shielding film 13, the side wall is formed on the side surface in the longitudinal direction of the slit portion 24 in the solid-state imaging device according to the present embodiment. It can be said that it is more preferable.

  Hereinafter, the manufacturing method of the solid-state imaging device according to the present embodiment will be described with reference to FIGS. 8 and FIG. 9 are the same as FIG. 3 and FIG. 4 used for description of the first embodiment, and FIG. 8A and FIG. 8C, FIG. 9A and FIG. And FIG. 9E is a portion where the stopper layer 20 is formed in a portion that is not a connection portion between the shunt wiring 14 and the second vertical transfer electrode 11B, and is a portion of the CC line portion in FIG. A cross-sectional structure is shown. 8 (b) and 8 (d), FIG. 9 (b), FIG. 9 (d), and FIG. 9 (f) are connection portions between the shunt wiring 14 and the second vertical transfer electrode 11B. FIG. 7 shows a cross-sectional configuration of the DD line portion in FIG. 6, which is a portion where the stopper layer 20 is not formed.

  In the state of FIG. 8A and FIG. 8B, up to the second insulating film 16 has already been formed. That is, a photoelectric conversion unit (not shown) is formed in the semiconductor substrate 22 and a vertical transfer channel 2 is formed between vertical columns of the photoelectric conversion unit, and patterned vertical transfer is performed via the surface oxide film 12 thereon. The electrode 11, the first insulating film 15, the light shielding film 13, and the second insulating film 16 are sequentially stacked.

  8A and 8B, a resist film 23 is formed on the second insulating film 16, and this resist film 23 is formed in the direction in which the vertical transfer channel 2 is formed. A portion to be a slit portion 24 to be formed later in the light shielding film 13 is patterned and removed. As described above, in the solid-state imaging device according to the present embodiment, since the slit portion 24 is continuously formed, not only FIG. 8B showing the cross-sectional shape of the connection portion between the shunt wiring and the vertical transfer electrode. 8A, the resist film 23 is also removed with the same width.

  It should be noted that the portion other than the connection portion between the shunt wiring and the vertical transfer electrode shown in FIG. A stopper layer 20 is formed on the vertical transfer electrode 11 in advance so as to have a wide width. By forming the stopper 20 so as to cover the entire vertical transfer electrode 11 having no connection portion, a larger margin for misalignment can be ensured.

  Next, as shown in FIGS. 8C and 8D, by using this resist film 23 as a mask, the second interlayer insulating film 16, the light shielding film 13, and the first interlayer insulating film are used. A slit-like opening is formed in the film 15. Although the opening is formed by etching, since the stopper layer 20 serving as an etching stopper is formed in the portion of FIG. 8C, the etching is stopped and no opening is formed in the stopper layer 20.

  Thereafter, as shown in FIGS. 9A and 9B, the resist film 23 is removed. Here, the opening formed in the light shielding film 13 becomes the slit portion 24 of the light shielding film 13.

  Next, as shown in FIGS. 9C and 9D, a third insulating film 18 made of a silicon oxide film is formed.

  Then, the third insulating film 18 is subjected to anisotropic etching, and as shown in FIGS. 9 (e) and 9 (f), the inner side of the side wall corresponding to the side surface in the longitudinal direction of the slit portion 24 of the light shielding film 13 is formed. A side wall 19 is formed on the inner wall portion of the second insulating film 16 in the portion and the portion surrounding the light receiving portion. At this time, as described above, the etching rate of the third insulating layer 18 that is an oxide film is set to be larger than the etching rate of the stopper layer 20 that is a nitride film, so that the side wall 19 is formed. The stopper layer 20 can be left as it is at the bottom of the slit portion 24.

  Then, as shown in FIG. 9F, a tungsten (W) film is formed by sputtering or a combination of sputtering and CVD, and is processed into a desired width to be insulated to form a shunt wiring 14. At this time, since the side wall 19 is formed, the shape of the slit portion 24 is a hollow shape in which the upper portion is widened. Therefore, the leg portion 21 formed simultaneously with the shunt wiring 14 is filled with a tungsten film. It becomes easy and reaches the bottom part of the slit part 24 easily. Therefore, in the connection portion shown in FIG. 9F, the shunt wiring 14 and the vertical transfer electrode 11 can be reliably connected. Further, in the portion shown in FIG. 9E, the leg portion 21 reliably reaches the stopper film 20 that also serves as an insulating film for the shunt wiring 14 and the vertical transfer electrode 11. As a result, it is possible to effectively prevent the adverse effect caused by the contact resistance between the shunt wiring 14 and the vertical transfer electrode 11, and the leg portion 21 enters the slit portion 24. Therefore, the effect of preventing the film peeling of the shunt wiring 14 caused by the above can be surely obtained.

  In this embodiment as well, as described in the first embodiment, the film thicknesses of the second insulating film 16 and the third insulating film 18 are set to 100 nm, and the width of the opening of the slit is set. The insulation between the shunt wiring 14 and the leg 21 and the vertical transfer electrode 11 or the light-shielding film 13 is sufficiently achieved by setting the thickness to 300 nm and appropriately controlling the amount of overetching when the sidewall 19 is formed. Can be kept in.

  Further, the effect of reducing image quality defects such as white scratches in the light receiving portion due to the relief of the stepped portion obtained by forming the sidewall portion 19, and the legs integrated with the light shielding film 13 and the shunt wiring 14. The effect of being able to reliably obtain insulation between the two obtained by correctly defining the distance from the unit 21 can be obtained in the same manner as the solid-state imaging device according to the first embodiment.

  As shown in FIG. 6, in this embodiment, the cross-sectional shape of the leg portion 21 is substantially square, and the shape of the region where the stopper layer 20 is not formed is also substantially square. However, the shape is not limited to this. Needless to say. In the first embodiment, as a variation of the shape of the connection portion opening 17, a rectangular shape, an oval shape, an oval shape, or a circular shape is shown using FIG. 5, but the cross section of the leg portion 21 in this embodiment is shown. The shape and the shape of the region where the stopper layer 20 is not formed can also be the various shapes shown in FIG. In addition, the shape of the region where the leg portion 21 and the stopper layer 20 are not formed is a rectangle or an oval shape, and the longitudinal direction is aligned with the direction in which the vertical transfer electrode 11 is formed, thereby improving reliability and solid-state imaging. The point that the speed of the apparatus can be increased is the same as in the first embodiment.

  As described above, the solid-state imaging device according to the present embodiment can obtain the same effect as when the thickness of the shunt wiring 14 is increased, so that the effective resistance value of the shunt wiring 14 can be lowered. Therefore, by using the solid-state imaging device according to the present embodiment, it is possible to realize a high-quality still camera and video camera that can be driven at high speed or can operate with low power consumption. Since the cross-sectional area of the shunt wiring 14 is increased as described above, the width of the shunt wiring 14 can be reduced while maintaining the resistance value. Therefore, when the drive frequency is not increased, the image pickup pixel size can be further reduced.

  Next, application examples of the solid-state imaging device according to the present embodiment will be described with reference to FIGS. 10 and 11. FIG. 10 is a plan view illustrating a main configuration of an application example of the solid-state imaging device according to the present embodiment. 11A is a schematic diagram showing a cross-sectional configuration taken along the line EE of FIG. 10, and FIG. 11B is a schematic diagram showing a cross-sectional configuration of a portion similarly shown as the FF line in FIG. FIG. The application example of the solid-state imaging device according to the present embodiment shown in FIGS. 10 and 11 is the same as the solid-state imaging device according to the second embodiment shown in FIGS. is there. Therefore, common parts are denoted by the same reference numerals and description thereof is omitted.

  In the application example shown in FIGS. 10 and 11, in the solid-state imaging device according to the second embodiment, when the third insulating film 18 is formed of a silicon oxide film, a silicon nitride film is selected as the stopper layer 20. Is the case. As shown in FIGS. 10 and 11, not only the vertical transfer electrode 11 corresponding to the bottom of the slit portion 24 of the light shielding film 13 but also the photoelectric conversion portion 1 of the semiconductor substrate 22 is formed on the stopper layer 20. It is characterized by being formed on the surface oxide film 12 at the position.

  Since the refractive index of the silicon nitride film is about n = 2, the refractive index of the photoelectric conversion part in the case of a silicon substrate of about n = 5 and the surface oxide film 12 of about n = 1.5 are used. Since it has a value between the refractive index at the interface, it can function as an antireflection film. For this reason, it is possible to obtain a solid-state imaging device having an antireflection film and having a higher sensitivity, which is shown as an application example, by slightly changing the mask pattern for forming the stopper layer 20.

  As described above, the solid-state imaging device and the manufacturing method thereof according to the present invention have been described with reference to the embodiments. However, the present invention is not limited to those described in the embodiments.

  For example, in each of the above embodiments, the first vertical transfer electrode 11A and the second vertical transfer electrode 11B are illustrated and described as being overlapped with each other. However, this may be a single layer structure that does not overlap. . Even in such a case, it is possible to promote the miniaturization of the imaging pixels in the vertical direction of the solid-state imaging device, that is, in the column direction of the photoelectric conversion unit, without losing any particular effect of the present invention.

  According to the solid-state imaging device and the method for manufacturing the same according to the present invention, it is possible to realize a high-quality solid-state imaging device having high imaging sensitivity and capable of high-speed signal processing, and a solid-state imaging device, particularly a CCD solid-state imaging device. It is useful for digital cameras and video cameras.

It is a top view which shows the structure of the imaging part of the solid-state imaging device concerning the 1st Embodiment of this invention. It is a schematic diagram which shows the cross-sectional structure of the imaging part of the solid-state imaging device concerning the 1st Embodiment of this invention, (a) is a cross-sectional structure in the AA line of FIG. 1, (b) is B of FIG. The cross-sectional structure in the -B line is shown. It is a section lineblock diagram showing a manufacturing method of a solid imaging device concerning a 1st embodiment of the present invention. It is a figure which shows the state after FIG. 3 with the cross-sectional block diagram which shows the manufacturing method of the solid-state imaging device concerning the 1st Embodiment of this invention. It is a figure which shows the shape of the connection part opening of the solid-state imaging device concerning the 1st Embodiment of this invention. It is a top view which shows the structure of the imaging part of the solid-state imaging device concerning the 2nd Embodiment of this invention. It is a schematic diagram which shows the cross-sectional structure of the imaging part of the solid-state imaging device concerning the 2nd Embodiment of this invention, (a) is a cross-sectional structure in CC line of FIG. 6, (b) is D of FIG. The cross-sectional structure in the -D line is shown. It is a cross-sectional block diagram which shows the manufacturing method of the solid-state imaging device concerning the 2nd Embodiment of this invention. FIG. 9 is a cross-sectional configuration diagram illustrating a method for manufacturing a solid-state imaging device according to a second embodiment of the present invention, illustrating a state after FIG. It is a top view which shows the structure of the imaging part of the solid-state imaging device concerning the application example of the 2nd Embodiment of this invention. It is a schematic diagram which shows the cross-sectional structure of the imaging part of the solid-state imaging device concerning the application example of the 2nd Embodiment of this invention, (a) is a cross-sectional structure in the EE line | wire of FIG. 10, (b) is a figure. The cross-sectional structure in the FF line of 10 is shown. It is a top view which shows the structure of the imaging part of the conventional solid-state imaging device. It is a schematic diagram which shows the cross-sectional structure of the imaging part of the conventional solid-state imaging device, (a) shows the cross-sectional structure in the aa line of FIG. 12, (b) shows the cross-sectional structure in the bb line of FIG. .

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoelectric conversion part 2 Vertical transfer channel 3 Window part 11 Vertical transfer electrode 11A 1st vertical transfer electrode 11B 2nd vertical transfer electrode 12 Surface oxide film 13 Light shielding film 14 Shunt wiring 15 1st insulating film 16 2nd insulating film 17 Connection part opening 18 Third insulating film 19 Side wall 20 Stopper layer 21 Leg part 22 Semiconductor substrate 23 Resist film 24 Slit part 101 Photoelectric conversion part 102 Vertical transfer channel 111 Vertical transfer electrode 113 Light shielding film 114 Shunt wiring 115 First insulation Film 116 Second insulating film 121 Contact portion 122 Semiconductor substrate

Claims (15)

A plurality of photoelectric conversion units arranged in a matrix on the substrate;
A vertical transfer channel disposed between vertical columns of the photoelectric conversion unit;
A plurality of vertical transfer electrodes for transferring charges of the photoelectric conversion unit to the vertical transfer channel;
A light-shielding film having a plurality of windows defining a light-receiving part of the photoelectric conversion part, which is laminated on the vertical transfer electrode via a first insulating film;
A light-shielding film disposed in a region overlapping with the vertical transfer channel and a shunt wiring insulated by a second insulating film;
A solid-state imaging device, wherein a driving pulse corresponding to each driving phase of the vertical transfer electrode is supplied from the shunt wiring. The vertical transfer electrode is connected to a plurality of the photoelectric conversion units arranged in a horizontal direction,
The solid-state imaging device according to claim 1, wherein the shunt wiring and the vertical transfer electrode are connected to each other by a leg portion that is integral with the shunt wiring and extends in a thickness direction thereof.   The solid-state imaging device according to claim 2, wherein the light shielding film is also formed in a region overlapping with the shunt wiring except for a connection portion opening through which the leg portion passes.   The solid-state imaging device according to claim 3, wherein the connection portion opening has any one shape of a circle, an ellipse, and a rectangle.   The solid-state imaging device according to claim 3 or 4, wherein the leg portion is located at a center of the connection portion opening.   6. The solid-state imaging device according to claim 3, wherein a sidewall is formed on a side surface of the connection portion opening of the light shielding film.   The light shielding film is divided for each vertical column of the photoelectric conversion unit by a slit unit formed in a region overlapping with the vertical transfer channel, and is continuously formed along the arrangement direction of the shunt wiring. The solid-state imaging device according to claim 2, wherein the solid-state imaging device enters the slit portion.   The solid-state imaging device according to claim 7, wherein a sidewall is formed on a side surface in the longitudinal direction of the slit portion of the light shielding film.   9. The stopper layer according to claim 7, further comprising a stopper layer laminated on the vertical transfer electrode in a region other than a connection portion between the shunt wiring and the vertical transfer electrode on the bottom surface of the slit portion. Solid-state imaging device.   The solid-state imaging device according to claim 9, wherein an antireflection film made of the same material as the stopper layer is formed on the light receiving portion.   The solid-state imaging device according to claim 1, wherein the vertical transfer electrode has a single-layer structure. Connected to a plurality of photoelectric conversion units arranged in a matrix on the substrate, a vertical transfer channel arranged between vertical columns of the photoelectric conversion units, and a plurality of the photoelectric conversion units arranged in a horizontal direction. A vertical transfer electrode, a light-shielding film having a plurality of windows defining a light-receiving portion of the photoelectric conversion portion stacked on the vertical transfer electrode via a first insulating film, and a region overlapping the vertical transfer channel The method for manufacturing a solid-state imaging device having the light shielding film disposed and the shunt wiring insulated by the second insulating film,
Etching the second insulating film, the light shielding film, and the first insulating film after forming the second insulating film to form an opening having a predetermined shape in a region overlapping with the vertical transfer channel; ,
Forming a third insulating film, subjecting the third insulating film to anisotropic etching to form a sidewall in the opening; and
Forming the shunt wiring with a leg portion extending in a thickness direction of the shunt wiring and connecting the shunt wiring and the vertical transfer electrode by the leg portion. .   The method for manufacturing a solid-state imaging device according to claim 12, wherein the opening has one of a circular shape, an elliptical shape, and a rectangular shape.   The method of manufacturing a solid-state imaging device according to claim 12, wherein the opening has a slit shape extending in a formation direction of the vertical transfer channel.   The method of manufacturing a solid-state imaging device according to claim 12, wherein the first insulating film is a multilayer film in which a silicon nitride film is stacked on a silicon oxide film.

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