JP2008299248A - Multilayer interference filter and solid-state image pickup apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer interference filter which has excellent optical characteristics regardless of the cell size and can be manufactured in high yield and at a low cost and to provide a solid-state image pickup apparatus. <P>SOLUTION: The multilayer interference filter 16 is composed of: a plurality of titanium-tantalum dioxide layers 161, 163, 166, 168, 171, 173; a plurality of silicon dioxide layers 162, 167, 172; and a plurality of spacer layers 164, 165, 169, 170. The solid-state image pickup apparatus 10 is composed of zones A, B, C comprising the respective multilayer interference filters 16 having the layer constitutions different from one another and the film thicknesses different from one another. The amount of the tantalum to be doped is set to satisfy the inequality: 0<x≤0.1 in the compositional formula: Ti<SB>(1-x)</SB>Ta<SB>x</SB>O<SB>2</SB>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a multilayer interference filter and a solid-state imaging device, and particularly to a composition of a dielectric material constituting a layer.

In recent years, solid-state imaging devices are widely used as imaging devices such as digital still cameras and digital movie cameras. In the solid-state imaging device, an optical filter that selectively transmits only a component having a predetermined wavelength from incident visible light is used for color separation. As one type of optical filter, for example, a so-called interference filter is proposed in which a silicon dioxide (SiO ₂ ) layer and a titanium dioxide (TiO ₂ ) layer are alternately stacked to use the light interference effect (patent). Reference 1).

As an optical filter, an interference filter having a structure in which both sides in the thickness direction of a spacer layer (SiO ₂ ) having an optical film thickness other than λ / 4 is sandwiched between two λ / 4 multilayer films has been proposed (patent). References 2, 3). Here, each of the two λ / 4 multilayer films is composed of a plurality of dielectric layers (SiO ₂ , TiO ₂ ). In such an interference filter, the interference filter proposed in Patent Document 1 has a highly accurate wavelength selection function even if the film thickness accuracy of each film is not strictly ensured. Specifically, as shown in FIG. 9, the interference filter has a structure in which TiO ₂ layers 903, 906, 908, 911, and 913 and an SiO ₂ layer are stacked in a predetermined order. And in the area | region D, the difference in transmission wavelength is provided between the area | region E by the spacer layer 910 being inserted.

As shown in FIG. 9, in the interference filters proposed in Patent Documents 2 and 3, the wavelength to be transmitted is defined by the number of intervening spacer layers 910 and the like. Therefore, in the formation of the interference filter, the spacer layer 910 is removed from a partial region (region E in FIG. 9) based on the wavelength to be transmitted. In the step of removing the spacer layer 910, wet etching is performed by dry etching in order to secure an etching selection ratio between SiO ₂ and TiO ₂ which are the constituent materials of the spacer layer 910 and the TiO ₂ layer disposed below the spacer layer 910. Used together.
JP 2000-180621 A International Publication WO / 2005/069376 JP 2007-0119143 A

However, the interference filters proposed in Patent Documents 2 and 3 may cause a problem of deterioration of optical characteristics due to wet etching in the manufacturing process. That is, when the spacer layer 910 is removed using wet etching, the etching solution soaks into the grain boundary of the TiO ₂ layer 908 disposed under the spacer layer 910, which is further disposed below. Part of the SiO ₂ layer 907 is eroded (see F portion in FIG. 10). When the SiO ₂ layer 907 is undesirably eroded along with the removal of the spacer layer 910, the optical distance at that portion (the distance defined by the product of the film thickness and the refractive index of the constituent film) varies. As a result, the optical characteristics deteriorate.

Conventionally, the arrangement of the plurality of spacer layers 910 is changed to avoid repeated wet etching in the same region in order to suppress undesired lower layer erosion in the removal of the spacer layer 910. Although measures are also taken, such measures cannot be adopted when further miniaturization of the cell is attempted.
The present invention has been made to solve the above-described problems, and has a multi-layer interference filter that has excellent optical characteristics regardless of cell size, and can be manufactured at a high yield and low cost. And it aims at providing a solid-state imaging device.

In order to achieve the above object, the present invention adopts the following configuration.
(1) In the multilayer interference filter according to the present invention, a plurality of layers are stacked, and the area of the in-plane thickness is thinner than the others. The plurality of layers are composed of at least two types of layers having different refractive indexes. In a region where the thickness is thinner than the others, Ti _{(1-x) is used} as one of the layers. A layer made of a material represented by the composition formula of A _x O ₂ is included.

In the composition formula of the material constituting the one type of layer, A is at least one element selected from the group consisting of Ta (tantalum), Nb (niobium), Zr (zirconium), and W (tungsten). It is characterized by.
(2) The multilayer interference filter according to the present invention is characterized in that “x” in the composition formula satisfies a relationship of 0 <x ≦ 0.1.

(3) The multilayer interference filter according to the present invention is characterized in that a layer made of a material represented by a composition formula of Ti _(1-x) A _x O ₂ is formed in an amorphous state.
(4) The multilayer interference filter according to the present invention is characterized in that a layer made of SiO ₂ is included in the at least two types of layers.
(5) A solid-state imaging device according to the present invention includes the multilayer interference filter according to any one of (1) to (4) as a color filter.

As described in (1) above, the multilayer interference filter according to the present invention includes a layer made of a material represented by the composition formula of Ti _(1-x) A _x O _{2 in} a region where the film thickness is thinner than the others. It is. And it has the characteristics that A in a composition formula is at least 1 sort (s) of element selected from the group which consists of Ta, Nb, Zr, and W. That is, the multilayer interference filter according to the present invention includes a layer formed by doping TiO ₂ with at least one element selected from the group consisting of Ta, Nb, Zr and W instead of the conventional TiO ₂ layer. Thereby, in the multilayer interference filter according to the present invention, the particle size in the layer doped with the one kind of element can be made larger than that of TiO ₂ .

Therefore, the multilayer interference filter according to the present invention, compared with the case where the layer formed from larger particles of particle size than TiO _2, it is possible to reduce the grain boundary of the distribution density, employing a TiO ₂ layer Thus, it is possible to reduce the amount of the etchant penetrating during wet etching during the formation process. Moreover, in the configuration of the multilayer interference filter according to the present invention, the amount of the etchant penetrating can be reduced regardless of the size of the pixel cell.

Therefore, the multilayer interference filter according to the present invention has excellent optical characteristics regardless of the cell size, and can be manufactured with high yield and low cost. The reason why at least one element selected from the group consisting of Ta, Nb, Zr and W is employed as the doping element for TiO ₂ is that it has a higher melting point than Ti. In particular, when Ta is used, the refractive index of the oxide of Ta is “2.3”, which is close to the refractive index “2.45” of TiO ₂ , so that the reduction of the refractive index in the layer can be suppressed. It is also excellent from the viewpoint of being able to do it.

In the multilayer interference filter according to the present invention, as described in (2) above, satisfying the relationship of 0 <x ≦ 0.1 in the composition formula can suppress a decrease in refractive index. More desirable.
In the multilayer interference filter according to the present invention, it is desirable that the layer made of the material represented by the composition formula of Ti _(1-x) A _x O ₂ is formed in an amorphous state. This is because by making the amorphous state with little optical anisotropy, a uniform refractive index in the layer can be achieved.

  In addition, since the solid-state imaging device according to the present invention includes the multilayer interference filter according to the present invention as an optical filter, the solid-state imaging device has excellent color separation characteristics, and from the viewpoint of cost and further miniaturization of the cell size. Excellent from.

The best mode for carrying out the present invention will be described below with reference to the drawings. In addition, about embodiment used below, it is an example for demonstrating the structural feature of this invention, an effect | action, and an effect in an easy-to-understand manner, and this invention is limited to this except for the part made into the summary. is not.
1. Configuration of Camera 1 A camera 1 according to the present embodiment will be described with reference to FIG.

  As shown in FIG. 1A, the camera 1 includes a solid-state imaging device 10, a lens 20, a color signal synthesis unit 30, a video signal creation unit 40, a drive unit 50, and the like. The light incident on the camera 1 is condensed on the pixel area of the solid-state imaging area 10 by the lens 20. In the solid-state imaging device 10, a color signal corresponding to the amount of incident light is generated and output to the color signal synthesis unit 30 for each corner imaging pixel. The solid-state imaging device 10 and the color signal synthesis unit 30 are driven according to a drive signal from the drive unit 50.

The color signal synthesis unit 30 performs color shading on the input color signal and outputs the color signal to the video signal creation unit 40. The video signal creation unit 40 creates a color video signal from the color signal subjected to color shading.
2. Configuration of Solid-State Imaging Device 10 As shown in FIG. 1B, the solid-state imaging device 10 has a configuration in which a plurality of pixels 101 and circuit units 102 to 10 are formed using a semiconductor substrate 11 as a common base. Have The plurality of pixels 101 are arranged in a matrix and constitute a pixel region.

Both the vertical shift register and the horizontal shift register 103 are dynamic circuits, and sequentially drive the plurality of pixels 101 based on a drive signal (voltage signal, timing signal) from the drive circuit 105.
The pixel signal output from each pixel 101 is amplified by the output amplifier 104 and output to the color signal synthesis unit 30 (see FIG. 1A).

3. Configuration of Pixel Region in Solid-State Imaging Device 10 Next, the configuration of the pixel region in the solid-state imaging device 1 will be described with reference to FIG.
As shown in FIG. 2A, in the pixel region of the solid-state imaging device 10, a p-type semiconductor layer 12 is stacked on an n-type semiconductor substrate 11, and an interlayer insulating film 14 is further stacked thereon. Yes. From the boundary between the p-type semiconductor layer 12 and the interlayer insulating film 14, a plurality of photodiodes 13 are formed in a state of being spaced apart from each other downward in the thickness direction (Z-axis direction) of the p-type semiconductor layer 12. The photodiodes 13 are two-dimensionally arranged, for example, in a matrix form in a direction along the main surface of the semiconductor substrate 11 (a direction orthogonal to the Z axis).

A light shielding film 15 is formed in a portion corresponding to between the adjacent photodiodes 13 in the interlayer insulating film 14. The light shielding film 15 is made of, for example, a metal material such as aluminum (Al) or tungsten (W). Further, a multilayer interference filter 16 and a planarizing film 18 are sequentially laminated on the interlayer insulating film 14, and a microlens 19 is formed on the interlayer insulating film 14 corresponding to each photodiode 13. The planarization film 18 is made of a transparent material such as silicon dioxide (SiO ₂ ), for example.

The multilayer interference filter 16 has a different thickness for each of the regions A, B, and C, thereby defining a transmission band.
4). Configuration of Multilayer Interference Filter 16 The multilayer interference filter 16 has a stacked configuration of a λ / 4 multilayer film and a spacer layer. The configuration will be described with reference to FIG.

  As shown in FIG. 2B, in the region A of the multilayer interference filter 16, a plurality of titanium tantalum dioxide layers 161, 163, 166, 168, 171, 173, a plurality of silicon dioxide layers 162, 167, 172, , And a plurality of spacer layers 164, 165, 169, 170 made of silicon dioxide layers, whereby each of the spacer layers 164, 165, 169, 170 is sandwiched between λ / 4 multilayer films, It has become. In the region C, the spacer layers 164, 165, 169, and 170 do not exist. Specifically, in the region C, a λ / 4 multilayer film composed of titanium tantalum dioxide layers 161 and 163 and a silicon dioxide layer 162, and similarly composed of titanium tantalum dioxide layers 166 and 168 and a silicon dioxide layer 167. The λ / 4 multilayer film, the λ / 4 multilayer film composed of titanium tantalum dioxide layers 171 and 173 and the silicon dioxide layer 172 are sequentially laminated.

In the region B, the spacer layer is formed of silicon dioxide layers 165 and 170. With such a configuration, the multilayer interference filter 16 transmits light in the green, blue, and red bands by changing the thickness of the spacer layer for each of the regions A, B, and C.
In general, when a multilayer interference filter is composed of only a λ / 4 multilayer film, the multilayer interference filter reflects light in a wide band having a wavelength λ as a central wavelength. However, when adopting a configuration in which the spacer layer is sandwiched between λ / 4 multilayer films as in the multilayer interference filter 16 according to the present embodiment, the spacer is reflected while reflecting light in a wide band having the wavelength λ as the central wavelength. Light can be transmitted in a narrow band having a wavelength corresponding to the thickness of the layers 164, 165, 169, and 170 as a central wavelength.

Therefore, in the multilayer interference filter 16 of the solid-state imaging device 10 according to the present embodiment, different transmission characteristics can be realized by making the film thicknesses of the spacer layers 164, 165, 169, and 170 different.
5. Method for Forming Multilayer Interference Filter 16 Next, a method for forming the multilayer interference filter 16 according to the present embodiment will be described with reference to FIGS.

  As shown in FIG. 3A, a titanium tantalum dioxide layer 161, a silicon dioxide layer 162, and a titanium tantalum dioxide layer 163 are sequentially laminated on the surface of the interlayer insulating film 14 using a sputtering apparatus. These three layers 161 to 163 constitute a λ / 4 multilayer film. Further, a silicon dioxide preparation layer 1640 is laminated on the upper surface of the titanium tantalum dioxide layer 163 using a sputtering apparatus (step a).

  As shown in FIG. 3B, a mask 501 is formed on the region A on the surface of the silicon dioxide preparatory layer 1640 formed as described above (step b). Thereafter, a silicon dioxide preparatory layer in the region (regions B and C in FIG. 2B) is removed by dry etching using a tetrafluoromethane-based etching gas and wet etching using buffered hydrofluoric acid. 1640 is removed (step c). After etching, as shown in FIG. 3C, the silicon dioxide layer 164 remains only on the titanium tantalum dioxide layer 163 in the region A.

  Next, as shown in FIG. 3D, a spacer preparation layer 1650 made of silicon dioxide as a constituent material is formed on each surface of the silicon dioxide layer 164 and the titanium tantalum dioxide layer 163 (step d). Thereafter, as shown in FIG. 4A, a mask 502 is formed on the surface of the spacer preparation layer 1650 in the regions A and B (step e). In this state, as in the above (step c), the region (region C) excluding the regions A and B is subjected to dry etching using a tetrafluoromethane-based etching gas and wet etching using buffered hydrofluoric acid. The spacer preparation layer 1650 is removed (step f). Thereafter, when the mask 502 is removed, the spacer layer 165 is formed only in the regions A and B as shown in FIG. Hereinafter, the spacer layer 165 is referred to as a “first spacer layer 165” for convenience.

  Next, as shown in FIG. 4C, a sputtering apparatus is used for each surface of the first spacer layer 165 in the regions A and B and the titanium tantalum dioxide layer 163 in the region C, and the titanium tantalum dioxide layer 166, A silicon dioxide layer 167 and a titanium tantalum dioxide layer 168 are sequentially stacked. A λ / 4 multilayer film is formed by these three layers 166 to 168. Further, a silicon dioxide preparation layer 1690 is laminated on the surface of the titanium tantalum dioxide layer 168 using a sputtering apparatus, and a mask 503 is further laminated in the region A (step g).

  After execution of the above (step g), dry etching using a tetrafluoromethane-based etching gas and wet etching using buffered hydrofluoric acid are performed to leave the silicon dioxide layer 169 only in the region A. Further, as shown in FIG. 4C, after removing the mask 503, a spacer preparation layer 1700 containing silicon dioxide as a constituent material is formed over the entire surface (step h).

Next, as shown in FIG. 5A, a mask 504 is formed on the surface of the spacer preparation layer 1700 in the regions A and B (step i). In this state, dry etching using a tetrafluoromethane-based etching gas and wet etching using buffered hydrofluoric acid are performed to remove the mask 504 (step j). By performing this process, the spacer layer 170 is formed only in the regions A and B as shown in FIG. Note that the spacer layer 170 is described as a “second spacer layer 170” in relation to the upper first spacer layer 165. As shown in FIG. 5C, the second spacer layer in the regions A and B is shown. A titanium tantalum dioxide layer 171, a silicon dioxide layer 172, and a titanium tantalum dioxide layer 173 are sequentially laminated on each surface of the titanium tantalum dioxide layer 168 in 170 and the region C. These three layers 171 to 173 also constitute a λ / 4 multilayer film.

In the above, the composition formula of titanium tantalum dioxide in the titanium tantalum dioxide layers 161, 163, 166, 168, 171, 173 is represented by Ti _(1-x) Ta _x O ₂ . In the composition formula, the relationship 0 <x ≦ 0.1 is satisfied.
The masks 501 to 504 are formed in the above manufacturing process by, for example, applying a resist agent, performing pre-exposure baking (pre-baking), and performing exposure with an exposure apparatus such as a stepper, and developing resist and final baking (post-baking). ) Can be employed.

The titanium tantalum dioxide layers 161, 163, 166, 168, 171, 173, and the silicon dioxide layers 162, 164, 167, 169, 172 each have an amorphous structure.
As described above, the multilayer interference filter 16 is formed.
6). Film formation of titanium tantalum dioxide layers 161, 163, 166, 168, 171, 173 and silicon dioxide layers 162, 164, 167, 169, 172 As described above, in the solid-state imaging device 10 according to the present embodiment, multiple layers Each of the titanium tantalum dioxide layers 161, 163, 166, 168, 171, 173 and the silicon dioxide layers 162, 164, 167, 169, 172 in the interference filter 16 has an amorphous structure. This is realized by adopting the film forming method as described above.

In the film forming process in this embodiment, a reactive magnetron DC sputtering method is employed in which generation of plasma and acceleration of ions are performed together using a DC sputtering apparatus. In the case of forming the titanium tantalum dioxide layers 161, 163, 166, 168, 171, and 173, for example, the following conditions can be used.
・ Atmosphere in the sputtering chamber; oxygen atmosphere ・ Applied voltage; DC voltage with a pulse frequency of 1 to 100 [Hz] (for example, 50 [Hz]) ・ Target; Titanium tantalum alloy target ・ Oxygen; 10 to 20 [sccm] ( For example, 15 [sccm])
Argon; 25-50 [sccm] (for example, 35 [sccm])
-Pressure; 0.1-0.8 [Pa] (for example, 0.4 [Pa])
-Power; 3-12 [kW] (for example, 9 [kW])
Note that, as described above, the reactive magnetron sputtering method can also be employed in the formation of the silicon dioxide layers 162, 164, 167, 169, and 172, and the film formation conditions can be set as appropriate.

7). Advantage (1) Advantage by adopting titanium tantalum dioxide layers 161, 163, 166, 168, 171, 173 as components of multilayer interference filter 16 Multilayer interference filter 16 of solid-state imaging device 10 according to the present embodiment Then, instead of the conventional titanium dioxide layer, titanium tantalum dioxide layers 161, 163, 166, 168, 171 and 173 are adopted as one of the components. By adopting such a configuration, in the multilayer interference filter 16, the particle size of each constituent particle in the titanium tantalum dioxide layer can be made larger than that of the titanium dioxide layer.

  Therefore, the multilayer interference filter 16 of the solid-state imaging device 10 according to the present embodiment has a layer having titanium tantalum nioxide having a particle size larger than that of titanium dioxide as a constituent particle. The distribution density can be reduced. The grain boundary distribution density is reduced by etching the spacer preparation layers 1650 and 1700 in which the titanium tantalum dioxide layers 163 and 168 substantially function as etching stoppers (step f and step j). The amount of penetration can be reduced.

As shown in FIG. 6, it can be seen that in the present embodiment employing the titanium tantalum dioxide layers 161, 163, 166, 168, 171, and 173, there is almost no penetration of the etchant during wet etching. In particular, the difference is clear in comparison with the conventional case shown in FIG. 10 employing a titanium dioxide layer.
Therefore, the solid-state imaging device 10 having the multilayer interference filter 16 has excellent optical characteristics regardless of the size of each pixel 101, and can be manufactured with high yield and low cost. In this embodiment, tantalum (Ta) is employed as a doping element for titanium dioxide, but in addition to this, niobium (Nb), zirconium (Zr), tungsten (W), etc. can be employed. Furthermore, the effect can be obtained by doping them in a composite manner.

  An element that is desirably doped with respect to titanium oxide is required to have an atomic weight larger than Ti and a high melting point. When considering that the refractive index of titanium oxide is “2.45”, the refractive index of the oxide of tantalum (Ta) is “2.3”, which suppresses the decrease in the refractive index in the layer. From the viewpoint of being able to do so, it is the most excellent as a doping element.

(2) Superiority by making Ta doping amount in the above range In the titanium tantalum dioxide layers 161, 163, 166, 168, 171, and 173 of the multilayer interference filter 16 according to the present embodiment, <X ≦ 0.1 is set to satisfy the relationship. By defining the numerical value range in this way, there is an advantage that a decrease in refractive index in each layer 161, 163, 166, 168, 171, 173 can be suppressed. FIG. 7 and FIG. 8 show the relationship between the Ta doping amount, the particle size, and the refractive index.

As shown in FIG. 7, it can be seen that the particle size becomes very large when Ta is doped even a little. On the other hand, as shown in FIG. 8, the refractive index of the oxide of Ta is 0.15 points smaller than the refractive index of titanium dioxide, so that the refractive index decreases as the Ta doping amount increases. The refractive index when x = 0.1 is “2.4”.
It can be said that it is desirable to comprehensively judge both results shown in FIG. 7 and FIG. 8 and to set so as to satisfy the relationship of 0 <x ≦ 0.1 in the composition formula.

(3) Advantage by Adopting Reactive Magnetron DC Sputtering Method As described above, the reactive magnetron DC sputtering method is adopted in the film formation according to the present embodiment. Thus, in this embodiment mode, reaction products (non-conductive oxides) generated on the target surface during film formation can be removed at the falling edge of the pulse, ensuring film formation uniformity. In addition, it is possible to suppress erosion and to suppress particles peeled off from the target surface, so that the yield can be improved.

  Regarding film formation uniformity, for example, when a substrate having a diameter of 200 [mm] is used, the in-plane uniformity of film thickness and refractive index can be set to ± 1.5 [%] or less. Specifically, a film having an amorphous structure (amorphous film) with little extinction effect in the low wavelength region of the blue region can be formed on the entire surface of the substrate. When the amorphous titanium tantalum dioxide layers 161, 163, 166, 168, 171, and 173 are formed as in the manufacturing method according to the present embodiment, the in-plane uniformity of the film thickness is ± 1. It can be set to 0 [%]. The in-plane uniformity of the refractive index can be set to ± 0.3 [%].

Further, in the solid-state imaging device 10 including the multilayer interference filter 16 in which the uniformity of the film thickness and the refractive index is ensured, the conventional solid-state imaging device having the multilayer interference filter formed by film formation using the vapor deposition method. , The sensitivity can be doubled and the number of white scratches can be reduced to 1/3.
Further, in the film formation method according to the present embodiment, since a pulsed DC voltage is applied, film formation is intermittently performed in accordance with the pulse waveform of the applied DC voltage, which occurs during film formation. In-film stress can be reduced. Thus, in the film forming method according to the present embodiment, damage to the photodiode 13 and the like when forming the multilayer interference filter 16 can be reduced.

Note that in this embodiment, when the titanium tantalum dioxide layers 161, 163, 166, 168, 171, and 173 are formed using the DC sputtering method, two targets of a titanium target and a tantalum target are used. It is also possible to use a co-sputtering film forming method.
In the above embodiment, the DC sputtering method is adopted. However, it is also possible to use a high frequency (RF) sputtering method in which plasma generation and ion acceleration are performed together using a high frequency AC power source. Even when the RF sputtering method is used to form the films 161 to 173 constituting the multilayer interference filter 16 as described above, the in-plane thickness and refractive index are the same as when the DC sputtering method is used. The uniformity can be improved, and erosion and particles can be effectively suppressed. In addition, when the RF sputtering method is used for film formation, the film stress in the formed multilayer interference filter 16 can be reduced.

  In the case of employing the RF sputtering method, as in the case of employing the DC sputtering method described above, for example, multilayer interference formed with high in-plane uniformity even on a substrate having a diameter of 200 mm or more. The solid-state imaging device 10 including the filter 16 can be manufactured with a high yield. Note that when a layer is formed using an RF sputtering method, a reaction product (non-conductive material) generated on the target surface during sputtering film formation can be removed when a reverse bias is applied. In addition to ensuring uniformity, it is possible to suppress target erosion and particles.

Further, when the titanium tantalum dioxide layers 161, 163, 166, 168, 171, and 173 are formed by RF sputtering, a ceramic target of titanium tantalum dioxide can be used as a target.
(Other matters)
In the above-described embodiment, the MOS solid-state imaging device 10 is used as an example, but it is naturally possible to adopt it for a CCD solid-state imaging device. The multilayer interference filter according to the present invention is not limited to a solid-state imaging device, and can be applied as an optical filter for various devices.

In the above embodiment, an example of the film forming conditions is shown, but the present invention is not limited to these conditions.
In FIG. 1B, the form in which the 4 × 4 pixels 101 are formed in the pixel region in the solid-state imaging device 10 is schematically illustrated. However, the number of pixels 101 formed in the actual solid-state imaging device 10 is schematically illustrated. Is more.

  The present invention is an effective technique for manufacturing a solid-state imaging device including a multilayer interference filter having excellent optical characteristics with high yield and low cost.

(A) is a block diagram showing the configuration of the camera 1 according to the embodiment, and (b) is a block diagram showing the configuration of the solid-state imaging device 10. (A) is sectional drawing which shows the structure of the pixel 101 part of the solid-state imaging device 10, (b) is sectional drawing which shows the structure of the multilayer interference filter 16 in it. FIG. 6 is a process cross-sectional view illustrating a manufacturing process of the multilayer interference filter 16. FIG. 6 is a process cross-sectional view illustrating a manufacturing process of the multilayer interference filter 16. FIG. 6 is a process cross-sectional view illustrating a manufacturing process of the multilayer interference filter 16. 4 is a TEM photograph showing a cross section of a titanium tantalum dioxide layer 168 in the multilayer interference filter 16. It is a characteristic view which shows the relationship between the doping amount ratio of tantalum and the grain size in the titanium tantalum dioxide layer. It is a characteristic view which shows the relationship between the doping amount ratio of tantalum in a titanium tantalum dioxide layer, and a refractive index. It is a TEM photograph which shows the partial cross section of the multilayer interference filter which concerns on a prior art. It is a TEM photograph which shows the cross section of the titanium dioxide layer 904 in the multilayer interference filter which concerns on a prior art.

Explanation of symbols

1. Camera 10. Solid-state imaging device 11. Semiconductor substrate 12. p-type semiconductor layer 13. Photodiode 14. Interlayer insulating film 15. Light shielding film 16. Multilayer interference filter 18. Planarization film 19. Microlens 20. Lens 30. Color signal synthesis unit 40. Video signal creation unit 50. Drive unit 101. Pixel 102. Vertical shift register 103. Horizontal shift register 104. Output amplifier 105. Drive circuits 161, 163, 166, 168, 171, 173. Titanium dioxide tantalum layers 162, 167, 172. Silicon dioxide layers 164, 165, 169, 170. Spacer layers 501, 502, 503, 504. mask

Claims (5)

A multi-layer interference filter in which a plurality of layers are stacked and has a region whose thickness is thinner than the others in the plane,
The plurality of layers are composed of at least two types of layers having different refractive indexes.
In the thin region, one of the at least two layers is made of a material represented by a composition formula of Ti _(1-x) A _x O ₂ ,
A in the composition formula is at least one element selected from the group consisting of Ta, Nb, Zr and W. A multilayer interference filter, wherein: The multilayer interference filter according to claim 1, wherein the composition formula satisfies a relationship of 0 <x ≦ 0.1. The multilayer interference filter according to claim 1, wherein the layer made of a material represented by the composition formula of Ti _(1-x) A _x O ₂ is formed in an amorphous state. The multilayer interference filter according to any one of claims 1 to 3, wherein a layer made of SiO ₂ is included in the at least two types of layers. A solid-state imaging device comprising the multilayer interference filter according to claim 1 as a color filter.