JP2010087441A - Solid-state imaging device and method of manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state imaging device having a waveguide formed by embedding the inside of a waveguide opening with an optically-transparent material without producing a void, and thereby improving a light condensation characteristic; and a method of manufacturing the same. <P>SOLUTION: This solid-state imaging device 1A includes: a semiconductor substrate 3 provided with a light reception part 5; an insulation layer 13 having a waveguide opening 15 at a position above the light reception part 5 and formed on the semiconductor substrate 3; an optically-transparent base layer 17 formed on the inner wall of the waveguide opening 15 by a reforming treatment of an exposed surface of the insulation layer 13; an optically-transparent embedding layer 19 embedding the inside of the waveguide opening 15 through the optically-transparent base layer 17; and an on-chip lens 23 arranged above the waveguide opening 15. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device and a method for manufacturing the solid-state imaging device, and more particularly to a solid-state imaging device in which a waveguide is provided on a light receiving portion and a manufacturing method therefor.

  In recent years, in a solid-state imaging device, pixel miniaturization has progressed due to an increase in the number of imaging pixels. Along with this, miniaturization of the photoelectric conversion portion has progressed, and it has become difficult to maintain high sensitivity. As one of countermeasures, a configuration in which a waveguide is provided in the wiring layer on the light receiving portion has been proposed. That is, as shown in FIG. 8, a laminated wiring structure in which a plurality of layers of wiring 103 is insulated by an interlayer insulating film 104 is provided on a semiconductor substrate 102 provided with a light receiving portion 101 in each pixel. On the interlayer insulating film 104, an on-chip lens 106 is provided via a color filter 105 or the like at a position corresponding to the light receiving unit 101. Therefore, by providing a waveguide opening 107 in a portion of the interlayer insulating film 104 corresponding to the light receiving portion 101 and embedding it with the light transmissive embedding layer 108, the light collected by the on-chip lens 106 can be efficiently collected. It is set as the structure made to inject into.

  In the configuration as described above, a light-transmitting underlayer 109 made of silicon nitride or the like having a high refractive index is formed on the inner wall of the waveguide opening 107 by a CVD method, a sputtering method, or the like. A configuration has been proposed in which the inside 107 is filled with a light-transmitting buried layer 108. Thereby, the light condensing property with respect to the light receiving part 101 can be improved by utilizing the refractive index difference between the light transmissive underlayer 109 and the light transmissive buried layer 108 (see Patent Documents 1 and 2 below). In such a configuration, the light-transmitting underlayer 109 is made of a material having low water permeability such as silicon nitride, thereby preventing moisture from entering the interlayer insulating film 104 from the waveguide opening 107. There is also an effect of improving reliability.

Japanese Patent Laying-Open No. 2003-282851 (see paragraphs 15 and 22 and FIG. 1) Japanese Patent Laying-Open No. 2006-222366 (see paragraphs 19, 20, and 55)

  However, in the structure of the solid-state imaging device provided with the above-described waveguide, when the pixel is further miniaturized and the aspect of the waveguide opening is increased, the embedding property of the light-transmitting material in the waveguide opening is It's getting harder. For this reason, as shown in FIG. 8, when the light-transmitting underlayer 109 is formed on the inner wall of the waveguide opening 107 by CVD or sputtering, the upper layer portion in the waveguide opening 107 is formed by the light-transmitting underlayer 109. It is narrowed into an overhang. As a result, the embedding characteristic in the waveguide opening 107 by the light transmissive embedding layer 108 is deteriorated, and the void B may be generated. The generation of the void B not only deteriorates the light condensing property to the light receiving unit 101 through the waveguide opening 107 but also causes the wiring 103 to deteriorate due to moisture confined in the void B.

  Therefore, the present invention provides a solid-state imaging device that has a waveguide in which the inside of the waveguide opening is embedded with a light-transmitting material without generation of voids, and thereby can improve the light collection characteristics. An object of the present invention is to provide a method for manufacturing the solid-state imaging device.

  In order to achieve such an object, in the solid-state imaging device of the present invention, an insulating layer is provided on a substrate provided with a light receiving portion. A waveguide opening is provided at a position on the light receiving portion in the insulating layer, and a light transmissive buried layer is provided on the inner wall of the waveguide opening via a light transmissive underlayer. An on-chip lens is provided above the waveguide opening. In particular, the light-transmitting underlayer is characterized by being a layer formed by modifying the exposed surface of the insulating layer including the inner wall of the waveguide opening.

  The present invention is also a method for manufacturing such a solid-state imaging device, and is characterized by the following procedure. First, an insulating layer is formed on a substrate provided with a light receiving portion, and a waveguide opening is formed at a position on the light receiving portion in the insulating layer. Next, the exposed surface of the insulating layer is modified to form a light-transmitting underlayer that covers the exposed surface of the insulating layer including the inner wall of the waveguide opening. Thereafter, a light-transmitting buried layer is formed to fill the waveguide opening through the light-transmitting underlayer, and then an on-chip lens is formed above the waveguide opening.

  According to the above, by forming the light-transmitting underlayer of the light-transmitting embedded layer that embeds the inside of the waveguide opening by the modification treatment of the inner wall of the waveguide opening, the film thickness of the light-transmitting underlayer is guided. It becomes almost uniform on the inner wall of the waveguide opening. For this reason, the diameter of the upper portion of the waveguide opening is not particularly narrowed by the light-transmitting underlayer, and an overhanging shape is not caused. The light provided in the waveguide opening via this light-transmitting underlayer The embedding characteristics of the transmissive embedding layer can be maintained.

  As described above, according to the present invention, since the embedding property in the waveguide opening through the light-transmitting underlayer is maintained, the inside of the waveguide opening is embedded with the light-transmitting material without generation of voids. It becomes possible to provide a waveguide. Thereby, in the solid-state imaging device provided with the waveguide, it is possible to improve the light condensing characteristic to the light receiving unit via the waveguide.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The description will be given in the following order.
1. First Embodiment (Example of leaving a light-transmitting buried layer on an insulating film)
2. Second Embodiment (Example of removing a light-transmitting buried layer on an insulating film)
3. Third embodiment (example in which the bottom of the waveguide opening is a base insulating film)

<First Embodiment>
FIG. 1 is a cross-sectional view of a main part for one pixel in the solid-state imaging device according to the first embodiment. The configuration of the solid-state imaging device 1A shown in this figure will be described in the order of manufacturing steps based on the sectional process diagrams of FIGS.

  First, as shown in FIG. 2A, a light receiving portion 5 constituted by an impurity diffusion layer is formed on a surface layer of a semiconductor substrate 3 made of single crystal silicon or the like. The light receiving portion 5 is provided in each pixel region separated by element separation (not shown). Each light receiving portion 5 may be formed as a diode composed of, for example, a P-type diffusion layer and an N-type diffusion layer on the surface side, and the surface may be covered with a hole accumulation layer made of a P-type diffusion layer.

  Although not shown here, in each pixel region, in addition to the light receiving portion 5, a floating diffusion composed of an impurity diffusion layer is formed, and a transfer gate, a reset gate, an amplifier are formed on the semiconductor substrate 3. Gates and the like are formed as necessary.

On the semiconductor substrate 3 as described above, a base insulating film 7 made of, for example, silicon nitride is formed. Next, an interlayer insulating film 9 is formed on the base insulating film 7, a groove pattern is formed on the surface side of the interlayer insulating film 9, and a wiring 11 in which a conductive material is embedded is formed. At this time, a silicon-based material film is preferably used for the interlayer insulating film 9, and has a dielectric constant lower than that of silicon oxide (SiO ₂ ), silicon oxide such as carbon-containing silicon oxide (SiOC) or polyariden (PAr). A so-called low dielectric constant film may be used. By forming the interlayer insulating film 9 with a low dielectric constant material, an improvement in conversion efficiency of the solid-state imaging device is expected. The wiring 11 is laid out so as not to be disposed above the light receiving portion 5, and necessary portions are connected between the upper and lower wirings 11 by connection holes (not shown) formed in the interlayer insulating film 9. I will do it.

  Thereafter, for example, the formation of the interlayer insulating film 9 and the formation of the wiring 11 in the groove pattern are repeated, and the interlayer insulating film 9 is finally formed to form a multilayer wiring structure. The multilayer wiring structure may be formed by repeatedly forming the wiring 11 and forming the interlayer insulating film 9 covering the wiring 11, and the wiring 11 is not limited to being a buried wiring. .

  As described above, the insulating layer 13 including the base insulating film 7 and a plurality of layers of interlayer insulating films 9 formed thereon is formed on the semiconductor substrate 3 provided with the light receiving portion 5. This insulating layer 13 is provided with a buried wiring 11 between the interlayer insulating films 9.

  Next, as shown in FIG. 2B, a waveguide opening 15 is formed in a pattern at a position corresponding to the upper portion of the light receiving portion 5 in the insulating layer 13. The waveguide opening 15 has a planar shape that opens widely only at the upper part of the light receiving portion 5, and is formed in a concave shape that has a depth with the lowermost interlayer insulating film 9 as a bottom surface and does not penetrate the insulating layer 13. . The waveguide opening 15 is formed so that the wiring 11 is not exposed on the inner wall.

  Such pattern formation of the waveguide opening 15 is performed by dry etching using a resist mask or an inorganic mask, for example.

  Next, as shown in FIG. 2 (3), a light-transmitting underlayer 17 is formed on the exposed surface of the insulating layer 13 including the inner wall of the waveguide opening 15. Here, the exposed surface of the insulating layer 13 is modified to form the light-transmitting underlayer 17 on the exposed surface of the insulating layer 13 including the inner wall of the waveguide opening 15.

  As such modification treatment, oxidation treatment or nitridation treatment of the exposed surface of the insulating layer 13 is performed, and the oxidation treatment or nitridation treatment may be oxynitridation treatment. Thereby, the light-transmitting underlayer 17 made of an oxide film, a nitride film, or an oxynitride film of a material constituting the interlayer insulating film 9 is formed in a state in which the exposed surface of the insulating layer 13 including the inner wall of the waveguide opening 15 is covered. It is formed.

  For example, when the interlayer insulating film 9 constituting the exposed surface of the insulating layer 13 is a silicon-based material film, a light-transmitting underlayer 17 made of a silicon oxide-based material is formed by performing an oxidation process as a modification process. Is done. Further, by performing nitriding as a modification process, the light-transmitting underlayer 17 made of a silicon nitride material is formed. Further, by performing an oxynitriding process as a modification process, a light-transmitting underlayer 17 made of a silicon oxynitride material is formed.

  In particular, the light-transmitting underlayer 17 is preferably a silicon nitride material film formed by nitriding or a silicon oxynitride material film formed by oxynitriding.

  These films have a low water permeability (permeability) and a high refractive index composition. For this reason, the light that has entered the waveguide opening 15 can be confined in the waveguide opening 15, and moisture entering from the waveguide opening 15 can be blocked from entering the insulating layer 13. 17 is suitable. In particular, when the interlayer insulating film 9 constituting the insulating layer 13 is made of a low dielectric constant material film such as carbon-containing silicon oxide (SiOC) or polyariden (PAr) for the purpose of improving the conversion efficiency, A low dielectric constant material has a low film density. For this reason, moisture that has entered from the waveguide opening 15 may deteriorate the wiring 11, but by using a silicon nitride-based material film or a silicon oxynitride-based material film as the light-transmitting underlayer 17, Such moisture intrusion can be blocked, and element reliability can be expected to improve.

  The oxidation treatment, nitriding treatment, or oxynitriding treatment for the modification treatment as described above is preferably performed by applying a so-called plasma treatment in which the treatment surface of the insulating layer 13 is exposed to oxygen plasma or nitrogen plasma. As a result, a modification process is performed in which the exposed surface of the insulating layer 13 including the inner wall of the waveguide opening 15 is oxidized or nitrided to a depth of several nm.

For example, the processing conditions for performing the plasma nitriding process using a CVD apparatus as the reforming process are as follows.
Gas and flow rate: Nitrogen gas (N ₂ ) = 300 sccm,
: Helium gas (He) = 3000 sccm,
Processing atmosphere pressure: 10 mTorr,
Source power: 100W,
Substrate temperature: 300 ° C.
Processing time: 30 seconds.

  The apparatus used for the modification treatment is not limited to a CVD apparatus as long as it can generate plasma, but may be an etching apparatus or an ashing apparatus.

  Next, as shown in FIG. 3A, a light transmissive buried layer 19 is formed to fill the waveguide opening 15 with the light transmissive underlayer 17 interposed therebetween. The light-transmitting buried layer 19 is made of a material having a high light transmittance such as an acrylic or fluorine-based polymer, an organosilicon polymer siloxane, or polyaridene (PAr). As a result, a waveguide in which the light-transmitting buried layer 19 is embedded in the waveguide opening 15 via the light-transmitting base layer 17 having water resistance is formed on the light receiving unit 3.

  Thereafter, as shown in FIG. 3B, a color filter layer 21 is formed on the light transmissive buried layer 19.

  After the above, as shown in FIG. 1, the on-chip lens 23 is formed at a position above the waveguide opening 15 to complete the solid-state imaging device 1A.

  In the solid-state imaging device 1A configured as described above, the light receiving portion 5 is provided on the surface side of the semiconductor substrate 3, and the insulating layer 13 is provided so as to cover the light receiving portion 5, and the light receiving portion in the insulating layer 13 is provided. 5 is provided with a waveguide opening 15 at a position above it. A light transmissive buried layer 19 is buried in the waveguide opening 15 via a light transmissive underlayer 17. Here, the light-transmitting underlayer 17 is characterized in that it is formed by subjecting the exposed surface of the insulating layer 13 to a modification treatment such as nitriding or oxidation. In addition, a color filter layer 21 is provided on the insulating layer 13 provided with the waveguide opening 15, and an on-chip lens 23 is provided above the waveguide opening 15 at a position above the waveguide opening 15. Thereby, the light condensed by the on-chip lens 23 is configured to efficiently enter the light receiving unit 5.

  The detailed description of each member constituting the solid-state imaging device 1A is as described in the manufacturing process described above.

  In the solid-state imaging device 1 </ b> A having such a configuration, as described above, the light-transmitting base layer 17 that is the base of the light-transmitting embedded layer 19 that fills the waveguide opening 15 is formed on the inner wall of the waveguide opening 15. It is formed by performing a modification process. Therefore, the light-transmitting underlayer 17 is formed with a substantially uniform film thickness on the inner wall of the waveguide opening. Therefore, the diameter of the upper portion of the waveguide opening 15 is not narrowed by the light-transmitting underlayer 17 so that an overhang shape is formed, and the inside of the waveguide opening 15 is embedded through the light-transmitting underlayer 17. The embedding margin of the light transmissive embedding layer 19 is expanded. Thereby, the embedding characteristic of the light transmissive embedding layer 19 can be maintained.

  As a result, it is possible to provide a waveguide in which the inside of the waveguide opening 15 is filled with the light transmissive material layer 19 without generation of voids. Thereby, in the solid-state imaging device 1A, it is possible to improve the light condensing characteristic to the light receiving unit 5 through the waveguide.

<Second Embodiment>
FIG. 4 is a cross-sectional view of a main part for one pixel in the solid-state imaging device according to the second embodiment. The solid-state imaging device 1B shown in this figure is different from the solid-state imaging device 1A of the first embodiment described with reference to FIG. 1 in that a light-transmitting buried layer 19 is provided only in the waveguide opening 15, Is covered with the protective film 30. The other configurations are the same. Hereinafter, the configuration of the solid-state imaging device 1 </ b> B will be described in the order of manufacturing steps based on the cross-sectional process diagrams of FIGS. 2 and 5.

  First, the same steps as described with reference to FIG. 2 in the first embodiment are performed. That is, as shown in FIG. 2A, a base insulating film 7 made of, for example, silicon nitride is formed on a semiconductor substrate 3 on which the light receiving portion 5 is formed, and an interlayer insulating film 9 and wirings 11 are formed thereon. A multilayer wiring structure is formed. Then, an insulating layer 13 composed of the base insulating film 7 and a plurality of interlayer insulating films 9 formed in a laminated manner on the base insulating film 7 is formed.

  Next, as shown in FIG. 2 (2), a waveguide opening 15 is formed in a pattern at a position corresponding to the upper portion of the light receiving portion 5 in the insulating layer 13, and further, as shown in FIG. 2 (3). A light-transmitting underlayer 17 is formed on the exposed surface of the insulating layer 13 including the inner wall of the opening 15. At this time, the light-transmitting underlayer 17 is formed on the exposed surface of the insulating layer 13 including the inner wall of the waveguide opening 15 by performing a modification process such as nitriding or oxidation on the exposed surface of the insulating layer 13. The characteristic part to perform is the same as that of 1st Embodiment.

  In the next step, as shown in FIG. 5 (1), a light-transmitting buried layer 19 that fills the waveguide opening 15 through the light-transmitting underlayer 17 is formed. This step is the same as that described with reference to FIG. 3A in the first embodiment, whereby the light-transmitting buried layer 19 passes through the light-transmitting base layer 17 having water resistance. The light receiving portion 5 is formed with a waveguide in which the waveguide opening 15 is embedded.

  After the above, as shown in FIG. 5 (2), a step of removing the light transmissive buried layer 19 on the insulating layer 13 while leaving the light transmissive buried layer 19 only in the waveguide opening 15 is performed. This is a process characteristic of the second embodiment. Here, for example, the light-transmitting embedded layer 19 is etched back using the light-transmitting underlayer 17 as a stopper, or the light-transmitting embedded layer 19 is polished and removed by a chemical mechanical polishing (CMP) method.

For example, the processing conditions for etching back the light transmissive buried layer 19 made of polyaridene are as follows.
Etching equipment: Parallel plate type,
Processing temperature: Normal temperature,
Etching gas and flow rate ratio: nitrogen gas (N ₂ ): hydrogen gas (H ₂ ) = 1: 2,
Etching atmosphere pressure: 50 mTorr,
Upper RF power: 1000 W
Lower RF power: 200W
Processing time: 5 minutes.

  After the above, as shown in FIG. 5 (3), a protective film 30 is formed on the light transmissive buried layer 19 and the insulating layer 13 filling the waveguide opening 15. The protective film 30 is not particularly limited as long as it is a light-transmitting insulating film having a passivation ability such as a silicon nitride film, and may be a single layer structure or a laminated structure, and further different material films. The laminated film may be used. In particular, the protective film 30 is preferably a thin film in order to reduce the distance between the on-chip lens to be formed later and the light receiving unit 5. This is because as the distance between the on-chip lens and the light receiving unit 5 is shorter, the number of times of loss such as stray light is reduced, so that the light collecting performance is improved. However, in order not to deteriorate the element reliability, the film is formed with an appropriate film thickness t on the assumption that the film thickness is a minimum film thickness that satisfies the passivation function.

  Next, the color filter layer 21 is formed on the protective film 30.

  After the above, as shown in FIG. 4, the on-chip lens 23 is formed at a position above the waveguide opening 15 to complete the solid-state imaging device 1B.

  In the solid-state imaging device 1B configured as described above, the light receiving unit 5 is provided on the surface side of the semiconductor substrate 3 and the insulating layer 13 is provided so as to cover the same, as in the first embodiment. The waveguide opening 15 is provided at a position on the light receiving portion 5 of the insulating layer 13. In the waveguide opening 15, a light-transmitting buried layer is formed through a light-transmitting underlayer 17 formed by subjecting the exposed surface of the insulating layer 13 to a modification process such as a nitriding process or an oxidizing process. It is characteristic that the layer 19 is embedded. A protective film 30 and a color filter layer 21 are provided on the insulating layer 13 provided with the waveguide opening 15, and an on-chip lens 23 is provided above the waveguide opening 15 at a position above the waveguide opening 15. It has been. Thereby, the light condensed by the on-chip lens 23 is configured to efficiently enter the light receiving unit 5. In particular, the second embodiment is characterized in that the light-transmitting buried layer 19 on the insulating layer 13 is removed.

  The detailed description of each member constituting the solid-state imaging device 1B is as described in the manufacturing process described above.

  In the solid-state imaging device 1B having such a configuration, as in the first embodiment, the light-transmitting base layer 17 serving as the base of the light-transmitting embedded layer 19 provided in the waveguide opening 15 is provided in the waveguide opening 15. It is formed by subjecting the inner wall to a modification treatment. For this reason, similarly to the solid-state imaging device of the first embodiment, it is possible to provide a waveguide in which the inside of the waveguide opening 15 is embedded with the light-transmitting embedded layer 19 without generation of voids. It is possible to improve the condensing characteristic to the light receiving unit 5.

  In particular, in the second embodiment, since the light-transmitting buried layer 19 on the insulating layer 13 is removed, the distance between the on-chip lens 23 and the light receiving unit 5 is increased by the protective film 30 whose film thickness is controlled. It can be adjusted with good controllability. Thereby, it is possible to further improve the condensing characteristic with respect to the light receiving unit 5.

  Further, the light-transmitting buried layer 19 is completely sealed by the light-transmitting underlayer 17 and the protective film 30 having low water permeability, and the movement of moisture accumulated in the light-transmitting buried layer 19 is blocked. I can do things. Thereby, it is possible to enhance the effect of suppressing the deterioration of the wiring around the waveguide.

<Third Embodiment>
FIG. 6 is a cross-sectional view of a main part for one pixel in the solid-state imaging device according to the third embodiment. The solid-state imaging device 1C shown in this figure is different from the solid-state imaging device 1A of the first embodiment described with reference to FIG. 1 in that the waveguide opening 15 ′ has the base insulating film 7 as a bottom surface. In addition, as a result, the composition of the light-transmitting underlayer 17 ′ covering the inner wall of the waveguide opening 15 ′ is different between the side wall and the bottom of the waveguide opening 15 ′. Other configurations are the same as those in the first embodiment. Hereinafter, the configuration of the solid-state imaging device 1 </ b> C will be described in the order of the manufacturing process based on the cross-sectional process diagram of FIG. 7.

First, the process shown in FIG. 7A is performed in the same manner as described with reference to FIG. 2A in the first embodiment. Thereby, a base insulating film 7 made of, for example, silicon nitride is formed on the semiconductor substrate 3 on which the light receiving portion 5 is formed, and a multilayer wiring structure made up of the interlayer insulating film 9 and the wiring 11 is formed thereon. Then, an insulating layer 13 composed of the base insulating film 7 and a plurality of interlayer insulating films 9 formed in a laminated manner on the base insulating film 7 is formed. At this time, a silicon-based material film is preferably used as the interlayer insulating film 9, and a so-called low dielectric constant film having a dielectric constant lower than that of silicon oxide such as silicon oxide (SiOC) other than silicon oxide (SiO ₂ ). It is preferable to be the same as in the first embodiment.

  Next, as shown in FIG. 7B, a waveguide opening 15 ′ is formed in a pattern at a position corresponding to the upper portion of the light receiving portion 5 in the insulating layer 13. At this time, it is characteristic that a waveguide opening 15 ′ reaching the base insulating film 7 is formed, and pattern etching of the interlayer insulating film 9 using the base insulating film 7 as a stopper is performed. As a result, a concave waveguide opening 15 ′ having a bottom surface made of the base insulating film 7 and a side wall made of the interlayer insulating film 9 is formed in the insulating layer 13.

  Next, as shown in FIG. 7 (3), a light-transmitting underlayer 17 ′ is formed on the exposed surface of the insulating layer 13 including the inner wall of the waveguide opening 15 ′. Here, the exposed surface of the insulating layer 13 is modified to form a light-transmitting underlayer 17 ′ on the exposed surface of the insulating layer 13 including the inner wall of the waveguide opening 15. In this modification process, as described with reference to FIG. 2C in the first embodiment, oxidation treatment, nitridation treatment, or oxynitridation treatment is performed. In particular, the treatment surface of the insulating layer 13 is treated with oxygen. A so-called plasma treatment, which is exposed to plasma or nitrogen plasma, is applied.

  By the modification process as described above, a light-transmitting underlayer 17 ′ having a different composition is formed in a portion covering the side wall of the waveguide opening 15 ′ and a portion covering the bottom surface of the waveguide opening 15 ′. That is, the portion covering the side wall of the waveguide opening 15 ′ becomes a nitride film or an oxide film of the material constituting the interlayer insulating film 9. On the other hand, the portion covering the bottom surface of the waveguide opening 15 ′ becomes a nitride film or an oxide film of the material constituting the base insulating film 7.

  Specifically, the case where the interlayer insulating film 9 is a low dielectric constant film made of carbon-containing silicon oxide (SiOC) and the base insulating film 7 is a silicon nitride film is exemplified. In this case, by performing an oxidation process as a modification process, the light-transmitting underlayer 17 ′ becomes an oxygen-rich carbon-containing silicon oxide (SiOC) film covering the side wall of the waveguide opening 15 ′, and the waveguide opening The portion covering the bottom surface of 15 'becomes a silicon oxynitride film. Further, by performing nitriding as a modification process, the light-transmitting underlayer 17 ′ has a carbon-containing silicon oxynitride material film covering the side wall of the waveguide opening 15 ′, and the bottom surface of the waveguide opening 15 ′. The portion covering the silicon nitride film becomes more nitrided than the base insulating film 7. Further, by performing an oxynitriding process as a modification process, the light-transmitting underlayer 17 ′ has a carbon-containing silicon oxynitride material film that covers the side wall of the waveguide opening 15 ′, and the bottom surface of the waveguide opening 15 ′. A portion covering the silicon oxide film becomes a silicon oxynitride film.

  Among these, the modification process for forming the light-transmitting underlayer 17 ′ is preferably an oxidation process. Thereby, in particular, the bottom surface of the waveguide opening 15 ′ is an acid whose refractive index gradually decreases as the oxygen content gradually increases from the base insulating film 7 made of silicon nitride toward the waveguide opening 15 ′ side. It is covered with a light-transmitting underlayer 17 ′ made of silicon nitride. For this reason, it is possible to suppress light reflection on the bottom surface of the light-transmitting underlayer 17 '.

  On the other hand, the side wall of the waveguide opening 15 'has an oxygen-rich carbon-containing silicon oxide (SiOC) in which the oxygen content gradually increases and the refractive index increases from the interlayer insulating film 9 toward the waveguide opening 15'. Can be covered with a light-transmitting undercoat layer 17 ′.

  In the subsequent steps, as described with reference to FIG. 3A in the first embodiment, the light transmissive buried layer 19 is formed to fill the waveguide opening 15 ′ through the light transmissive underlayer 17 ′. A film is formed. The light-transmitting buried layer 19 is made of a material having a high light transmittance such as an acrylic or fluorine-based polymer, an organosilicon polymer siloxane, or polyariden (PAr). As a result, a waveguide is formed on the light receiving portion 3 by embedding the light transmissive buried layer 19 in the waveguide opening 15 ′ via the light transmissive underlayer 17 ′.

  Thereafter, in the same manner as described with reference to FIG. 3B, the color filter layer 21 is formed on the light-transmitting buried layer 19, and the on-chip lens 23 is placed above the waveguide opening 15 ′. Then, the solid-state imaging device 1C shown in FIG. 7 is completed.

  Even in the solid-state imaging device 1C having such a configuration, as in the first embodiment, the light-transmitting base layer 17 ′ serving as the base of the light-transmitting buried layer 19 provided in the waveguide opening 15 ′ It is formed by subjecting the inner wall of the waveguide opening 15 to a modification process. For this reason, similarly to the solid-state imaging device of the first embodiment, it is possible to provide a waveguide in which the inside of the waveguide opening 15 is embedded with the light transmissive material layer 19 without generation of voids. It is possible to improve the condensing characteristic to the light receiving unit 5.

  In particular, in the third embodiment, the waveguide opening 15 ′ has the base insulating film 7 as the bottom surface. Thereby, the composition of the light-transmitting underlayer 17 ′ differs between the portion covering the side wall of the waveguide opening 15 ′ and the portion covering the bottom surface. Therefore, the light-transmitting underlayer 17 ′ having a high refractive index on the side wall of the waveguide opening 15 ′ and a low refractive index on the bottom surface of the waveguide opening 15 ′ can be formed. Therefore, light is confined in the waveguide opening 15 ′ on the side wall of the waveguide opening 15 ′ using the difference in refractive index with the light-transmitting buried layer 19, and light is transmitted on the bottom surface of the light-transmitting base layer 17 ′. It is possible to prevent the reflection and improve the light collecting characteristics with respect to the light receiving unit 5.

  The third embodiment described above can be combined with the second embodiment. In this case, the light transmissive buried layer 19 shown in FIG. 6 is provided only in the waveguide opening 15 ′ and removed on the insulating layer 13. Then, the color filter layer 21 may be provided above the light-transmitting buried layer 19 and the insulating layer recess 13 in the waveguide opening 15 ′ via a passivation protective film. With such a configuration, the effects of the second embodiment can also be obtained.

It is principal part sectional drawing of the solid-state imaging device of 1st Embodiment. FIG. 6 is a cross-sectional process diagram (part 1) illustrating the method for manufacturing the solid-state imaging device according to the first embodiment; FIG. 6 is a cross-sectional process diagram (part 2) illustrating the method for manufacturing the solid-state imaging device according to the first embodiment; It is principal part sectional drawing of the solid-state imaging device of 2nd Embodiment. It is sectional process drawing explaining the principal part of the manufacturing method of the solid-state imaging device of 2nd Embodiment. It is principal part sectional drawing of the solid-state imaging device of 3rd Embodiment. It is sectional process drawing explaining the principal part of the manufacturing method of the solid-state imaging device of 3rd Embodiment. It is sectional drawing of the conventional solid-state imaging device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1A, 1B, 1C ... Solid-state imaging device, 3 ... Semiconductor substrate, 5 ... Light-receiving part, 7 ... Base insulating film, 9 ... Interlayer insulating film, 13 ... Embedded wiring, 13 ... Insulating layer, 15, 15 '... Waveguide opening , 17, 17 '... light transmissive underlayer, 19 ... light transmissive buried layer, 21 ... color filter layer, 23 ... on-chip lens, 30 ... protective film

Claims (19)

A substrate provided with a light receiving portion;
An insulating layer provided on the substrate with a waveguide opening at a position on the light receiving unit;
A light-transmitting underlayer formed on the inner wall of the waveguide opening by modification of the exposed surface of the insulating layer;
A light-transmitting embedded layer that embeds the waveguide opening via the light-transmitting underlayer;
A solid-state imaging device comprising: an on-chip lens provided above the waveguide opening. The solid-state imaging device according to claim 1, wherein the light-transmitting underlayer is an oxide film or a nitride film. The solid-state imaging device according to claim 1, wherein the insulating layer and the light-transmitting underlayer are silicon-based material films. The solid-state imaging device according to claim 1, wherein the waveguide opening is formed in a concave shape having a bottom made of the insulating layer. The insulating layer comprises a lowermost base insulating film and an interlayer insulating film made of a material different from the base insulating film,
The solid-state imaging device according to claim 1, wherein the waveguide opening has the base insulating film as a bottom surface. The solid-state imaging device according to claim 5, wherein the light-transmitting underlayer has a different composition between a portion covering the bottom of the waveguide opening and a portion covering the side wall. The solid-state imaging device according to claim 1, wherein the light-transmitting buried layer is provided only in the waveguide opening. The solid-state imaging device according to claim 7, wherein a protective film is provided above the light-transmitting buried layer and the insulating layer filling the waveguide opening. The solid-state imaging device according to claim 1, wherein the insulating layer includes a plurality of layers, and wiring is provided between the layers. Forming an insulating layer on a substrate provided with a light receiving portion;
Forming a waveguide opening at a position on the light receiving portion in the insulating layer;
Forming a light-transmitting underlayer covering the inner wall of the waveguide opening by modifying the exposed surface of the insulating layer;
Forming a light-transmitting buried layer that fills the waveguide opening through the light-transmitting underlayer;
And a step of forming an on-chip lens above the waveguide opening. The method for manufacturing a solid-state imaging device according to claim 10, wherein in the step of forming the light-transmitting underlayer, oxidation treatment or nitridation treatment is performed. The method for manufacturing a solid-state imaging device according to claim 10, wherein the light-transmitting underlayer is formed by plasma processing. The method for manufacturing a solid-state imaging device according to claim 10, wherein a silicon-based material film is formed as the light-transmitting underlayer by forming a silicon-based material film as the insulating layer. The method for manufacturing a solid-state imaging device according to claim 10, wherein in the step of forming the waveguide opening, a concave waveguide opening having a bottom portion made of the insulating layer is formed. In the step of forming the insulating layer, as the insulating layer, a base insulating film and an interlayer insulating film made of a material different from the base insulating film are formed in this order,
The method for manufacturing a solid-state imaging device according to claim 10, wherein in the step of forming the waveguide opening, the interlayer insulating film is pattern-etched using the base insulating film as a bottom surface. 16. The step of forming the light-transmitting underlayer forms a light-transmitting underlayer having a different composition between a portion covering the bottom of the waveguide opening and a portion covering the side wall by the modification process. Manufacturing method of solid-state imaging device. In the step of forming the light transmissive buried layer, a light transmissive buried layer is formed on the insulating layer in a state where the waveguide opening is buried, and then left on the insulating layer only in the waveguide opening. The method for manufacturing a solid-state imaging device according to claim 10, wherein the light-transmitting embedded layer is removed. After the step of forming the light-transmitting embedded layer and before the step of forming the on-chip lens, a protective film is formed on the light-transmitting embedded layer and the insulating layer embedded in the waveguide opening. The method of manufacturing a solid-state imaging device according to claim 17. The method for manufacturing a solid-state imaging device according to claim 10, wherein in the step of forming the insulating layer, an insulating layer having a laminated structure is formed and a wiring is formed between the layers.

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