JP2004246053A - Optical shutter and solid image element, and manufacturing methods therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide solid image element using an optical shutter whose shutter mechanism is made small-sized and long in life and which is capable of fast shutter operation. <P>SOLUTION: The optical shutter comprises at least 1st and 2nd refractive index material parts 3 and 4 and electrodes 2 and 5 for applying a voltage to the 2nd refractive index material part 4; and border surfaces between the 1st and 2nd refractive index material parts 3 and 4 are formed of mutually opposite slopes 6, those 1st and 2nd refractive index material parts 3 and 4 are stacked, and the 2nd refractive index material part 4 is made of a material having electrooptic effect. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical shutter, a solid-state imaging device, and a manufacturing method thereof.
[0002]
[Prior art]
2. Description of the Related Art In various solid-state imaging devices (CCDs) used for video cameras, digital cameras, and the like, a mechanical shutter (mechanical shutter) is provided as a mechanism for controlling incident light in order to improve imaging characteristics.
For example, in a frame transfer (FT) transfer type solid-state imaging device capable of forming a light receiving region relatively wide, in particular, during the charge transfer, light leaks into the transfer unit, causing unnecessary charge signals in the image signal. It is necessary to use a mechanical shutter in order to avoid so-called smearing phenomenon (for example, see Patent Document 1).
[0003]
Further, not only CCDs of various transfer systems, but also CMOS sensors and the like, the light-shielding characteristics of the mechanical shutter are important in order to improve the problem of an afterimage caused by a difference in photoelectric conversion time for each pixel.
[0004]
However, when a mechanical shutter is used, it is difficult to reduce the space occupied by both the CCD, which is the light receiving detection unit, and the mechanical shutter, and it is difficult to reduce the size of products such as video cameras.
Another problem is that it is difficult to prolong the life of the shutter and, consequently, the life of the product due to wear of components constituting the mechanical shutter.
Further, in the case of a mechanical shutter using the operation principle of mechanically rotating components, it is difficult to increase the speed of the shutter operation to a certain speed or more, and it is difficult to improve the imaging characteristics.
[0005]
On the other hand, an optical shutter capable of performing a high-speed reaction using an electro-optical material has been reported (for example, see Non-Patent Document 1).
[0006]
As a configuration of this optical shutter, PLZT (PbZrO) is used as an electro-optical material.₃And PbTiO₃(A material in which La is added to a solid solution of the above), and the composition ratio is particularly [Pb_1-xLa_x] [(Zr_yTi_1-y)_{1-x / 4}] O₃A material having x / y / z = 9/65/35, that is, PLZT containing La 9 mol%, Zr 65 mol%, and Ti 35 mol% is listed as a material having a large electro-optic effect.
By attaching an electrode to this PLZT and sandwiching it between orthogonal polarizers, a high-speed response optical shutter can be configured. For example, flash protection glasses, printers in which optical shutters are arranged in a line, and the like have been proposed. (For example, see Non-Patent Document 1).
[0007]
These conventional optical shutters using PLZT have various advantages such as no wear of parts such as a mechanical shutter and high-speed response. However, because of the operating principle, it is necessary to use an orthogonal polarizing plate, and the amount of light transmitted through the optical shutter is significantly limited. No examples have been applied in the past.
[0008]
[Patent Document 1]
JP 2001-148809 A
[Non-patent document 1]
K. Murano, “Transparent Ceramics PLZT”, Solid State Physics, Agne Technology Center, 1986, Vol. 2, No. 9, p. 65-71
[0009]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described problems of the mechanical shutter, and has been made to provide an optical shutter capable of shortening the size and extending the life of the shutter mechanism and performing a high-speed shutter operation, and a solid-state imaging device using the optical shutter. Aim.
[0010]
[Means for Solving the Problems]
The present invention comprises at least a first and a second refractive index material portion and an electrode for applying a voltage to the second refractive index material portion, and defines a boundary surface between the first and second refractive index material portions, The first and second refractive index material portions are laminated by forming slopes facing each other, and the second refractive index material portion is formed of a material having an electro-optic effect.
[0011]
The solid-state imaging device according to the present invention is provided with the optical shutter having the above-described configuration at least above the light receiving unit.
Further, in the solid-state imaging device according to the present invention, in the frame transfer type transfer system having the above-described configuration, one of the electrodes for applying a voltage to the first and second refractive index material portions is connected to the electrode of the vertical transfer register. The configuration is also used.
[0012]
Further, in the method for manufacturing an optical shutter according to the present invention, a step of forming an electrode on a base material, a step of forming a first refractive index material layer on the first electrode, Then, a step of applying a photosensitive layer and pressing a light-transmitting mold having a shape with opposed slopes against the surface of the photosensitive layer, and irradiating light to cure the photosensitive layer, followed by anisotropic A step of performing etching of the photosensitive layer and the first refractive index material layer by dry etching to form a first refractive index material portion having opposing inclined surfaces; and forming an electric current on the first refractive index material layer. Forming a second refractive index material portion by applying a second refractive index material layer made of a material having an optical effect so as to fill the slope of the first refractive index material layer formed by etching; Forming an electrode on the second refractive index layer.
[0013]
Furthermore, a method for manufacturing a solid-state imaging device according to the present invention is to form a solid-state imaging device on a light receiving portion of a solid-state imaging device having an optical shutter having the above-described configuration.
[0014]
As described above, in the present invention, the optical shutter is constituted by the first refractive index material portion and the second refractive index material portion, and the boundary surface is constituted by opposing inclined surfaces. Further, by forming the second refractive index material portion from an electro-optic material, the incident light can be efficiently emitted by a change in the refractive index by applying a voltage to the second refractive index material portion, which is an electro-optic material, and Light can be shielded or transmitted with a fast response speed. This will be described below.
[0015]
In the optical shutter according to the above-described configuration of the present invention, when light is incident from above the second refractive index material portion, whether the incident light is reflected by the slope that is the boundary surface between the first and second refractive index material portions. Alternatively, the light enters the first refractive index material portion at a predetermined angle.
Here, when light enters from a material having a relatively large refractive index to a material having a relatively small refractive index, the critical angle θc of total reflection at the interface is determined by the refraction of the first and second refractive index materials. Rate n₁And n₂Then
θc = sin^-1(N₂/ N₁)
(Where n₁> N₂).
[0016]
Therefore, in the above-mentioned optical shutter, the voltage applied to the second refractive index material portion is controlled, and the refractive index is changed to control the critical angle of total reflection, that is, the refractive index is reduced by applying a voltage. In the case of a material, for example, the critical angle of total reflection is made relatively small by increasing the refractive index by applying no voltage, or the critical angle of total reflection is made relatively large by reducing the refractive index by applying a voltage. Is controlled to determine whether the angle of incidence of light at the interface between the first and second refractive index material portions exceeds the critical angle θc or falls within the critical angle θc. Can be controlled.
[0017]
For example, the refractive index is controlled so that the incident light is totally reflected at the boundary surface, and the totally reflected light substantially exceeds the critical angle of the total reflection also on the other slope facing the slope. By being configured to be incident at an angle and totally reflected also on this surface, light can be substantially totally reflected outside the optical shutter without being incident on the first refractive index material portion. it can.
Similarly, when the refractive index is controlled so that the incident angle of light is within the critical angle of total reflection, the light can be incident on the first refractive index material portion.
[0018]
Similarly, when an electro-optic material whose refractive index increases by applying a voltage is used, the amount of incident light at the boundary surface can be controlled by controlling the critical angle θc by adjusting the applied voltage.
Since such an optical shutter according to the present invention uses a material having an electro-optical effect, the optical shutter is excellent in response speed, does not have a problem of abrasion unlike a mechanical shutter, and can realize a small optical shutter.
[0019]
In particular, when the optical shutter according to the configuration of the present invention is provided on the light receiving portion of the solid-state imaging device, it is possible to provide a small-sized solid-state imaging device having a light-shielding mechanism with excellent response speed.
In a solid-state imaging device, normally, incident light passes through a stop of a lens, and thus the incident angle is limited to a value depending on the aperture ratio of the stop. Therefore, as will be described in detail in a later embodiment, by controlling the refractive index of the second refractive index material portion, the light in the range of the incident angle limited by the aperture ratio is totally reflected or transmitted. By doing so, it is possible to provide a solid-state imaging device that can be particularly reduced in size as compared with a conventional mechanical shutter, has no risk of component deterioration, and has a longer life. In particular, by using an electro-optic material such as PLZT, it is possible to provide a solid-state imaging device having a light-shielding mechanism with excellent response speed.
As a result, it is possible to improve the imaging characteristics by reducing the size and extending the life of the solid-state imaging device, and furthermore, by performing high-speed light shielding.
[0020]
According to the above-described method for manufacturing an optical shutter according to the present invention, the first refractive index material portion can be easily formed by pressing the light-transmitting mold, photosensitive curing, and anisotropic etching. The first refractive index material portion can be formed, and thereafter, the material constituting the second refractive index material portion is applied by ordinary sputtering, or the material is melted and applied by spin coating or the like. By such a method, it is possible to easily and reliably manufacture the optical shutter according to the present invention in which the first and second refractive index material portions each having the inclined surfaces whose boundary surfaces are opposed to each other are laminated.
[0021]
Further, by forming an optical shutter on the light receiving portion of the solid-state imaging device using this method of manufacturing an optical shutter, a light-shielding mechanism that is simple, reliable, small, has a high response speed, and can avoid a shortened life is provided. A solid-state imaging device having the same can be manufactured.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments, and it goes without saying that various modifications and changes are possible. Absent.
[0023]
(1) First embodiment
In this example, an example of an optical shutter according to the present invention will be described.
FIG. 1 is a schematic perspective view showing a schematic configuration of an example of an optical shutter. In FIG. 1, an optical shutter 10 according to the present invention includes first and second refractive index material portions 3 and 4, and electrodes 2 and 5 for applying a voltage to the second refractive index material portion 4. Then, a boundary surface between the first and second refractive index material portions 3 and 4 is an inclined surface 6 facing each other, and the first and second refractive index material portions 3 and 4 are laminated.
The second refractive index material portion 5 is made of an electro-optical material such as PLZT and has a refractive index larger than that of the first refractive index material portion 3.
The electrodes 2 and 5 are made of a light-transmitting conductive material, for example, ITO.
[0024]
Further, in FIG. 1, a dashed line a indicates a reference axis on which the incident light is incident, and a main incident direction of the incident light is a direction along the reference axis as indicated by an arrow L. Specifically, for example, in an image pickup apparatus or the like, the reference axis is substantially parallel to the optical axis of a condenser lens provided above the optical shutter. In this case, the incident light enters the optical shutter from the reference axis along the optical axis at an incident angle limited by the aperture stop.
[0025]
In this example, the electrode 2 is formed along a reference plane 7 orthogonal to the reference axis a, and each slope 6 is formed such that the angle α between the reference plane 7 and the slope 6 is substantially equal to each other. The slope 6 extends in one direction along the reference plane, and in a cross section orthogonal to the extending direction, the first and second refractive index material portions 3 and 4 each have an isosceles triangle shape. In this configuration, a plurality of triangular prisms are arranged side by side.
[0026]
An example of a reflection mode of incident light in such a configuration will be described with reference to FIG. 2, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted. The broken line b indicates the normal direction of one slope 6A of the slopes 6 facing each other. The angle θc indicates a critical angle of total reflection determined by the refractive indices of the first and second refractive index material portions 3 and 4, and a boundary line thereof is indicated by a solid line c.
[0027]
For example, the first refractive index material portion 3 is made of SiO.₂When the second refractive index material portion 4 is made of PLZT containing La 9 mol%, Zr 65 mol%, and Ti 35 mol%, SiO 2₂Has a refractive index of 1.46, and the refractive index of PLZT having the above-described composition is about 2.5 when no voltage is applied, as described in Patent Document 1 described above. The critical angle θc of reflection is 35.7 °.
That is, light incident at an angle exceeding 35.7 ° from the normal direction of the slope 6A indicated by the broken line b can be totally reflected.
[0028]
Here, in the light condensing system of the light incident on the optical shutter, for example, when the F value is 2.8, the incident angle is about ± 10 ° with respect to the reference axis a. Arrows d1 and d2 indicate light in the incident angle range where the incident angle is ± 10 ° on the paper surface of FIG. Assuming that the angle α between the slope 6A and the reference plane is 45 °, the angle between the reference axis a and the solid line c, which is the boundary of the critical angle of total reflection, is 9.3 °. That is, in the cross section along FIG. 2, the light indicated by the arrow d <b> 1 shifted from the reference axis direction to the lower side of the slope 6 </ b> A in the inclination direction leaks by about 0.7 °, but actually, it leaks. This incident light spreads at a solid angle, while the slope 6 is a plane extending in a direction perpendicular to the paper surface of FIG. 2. Light can be reliably reflected.
[0029]
In this example, the first refractive index material portion is made of SiO.₂However, when a light transmissive material having a lower refractive index is used as the first refractive index material part, the critical angle of total reflection can be made smaller. Needless to say, such partial leakage can be avoided. Similarly, even when the angle of incidence can be limited by adjusting the light-collecting system, the leakage of light can be avoided or suppressed in the same manner, and light can be blocked more reliably.
[0030]
On the other hand, the light once reflected on the slope 6A is reflected on the other slope 6B opposite to the slope 6A. If the angle of the inclined surface 6B from the normal direction (indicated by the broken line d) is larger than the critical angle of total reflection, the surface 6B is also totally reflected.
In this case, the angle formed by the slopes 6A and 6B with the reference plane is α, the angle of the incident light indicated by the arrow d2 from the reference axis is β, and this light is reflected by the slope 6A to the opposite slope 6B. Let γ be the angle of incidence of the incident light (indicated by arrow d3)
γ = 3α + β-90 °
Becomes
Here, when the inclination angle α of the inclined surfaces 6A and 6B is 45 °, the F-number of the condenser lens is 2.8, and the incident angle β is 10 ° using the above-described refractive index material, the incident angle γ Is 55 °. In other words, even at the time of this reflection, most of the light can be reflected in the cross section along the paper surface of FIG.
[0031]
Next, a case where light is transmitted will be described. FIG. 3 is a diagram showing, as an example, the applied voltage dependence of the refractive index of PLZT with the above composition. Here, when obtaining FIG. 3, the Kerr constant R is set to 1 × 10^-15m²/ V²Assuming that the refractive index of the PLZT when no voltage is applied is n = 2.5 and the film thickness t is 1 μm, the refractive index change Δn was calculated from the following equation.
Δn = − (1 / 2t²) ・ N³・ R ・ V²
[0032]
FIG. 3 shows that when a voltage of, for example, 11 V is applied to the PLZT having a thickness of 1 μm, the refractive index decreases by about 0.95. At this time, when the critical angle at which total reflection occurs is calculated, it is about 70 °. Here, most of the light based on the above-described conditions of the refractive index material and the incident angle is transmitted to the lower portion of the optical shutter without being reflected at the interface between the first, second, and refractive index material portions.
Therefore, according to the configuration of the present invention, it is possible to provide a small optical shutter having high-speed response compared to the related art.
[0033]
In the above-described example, the slope which is the boundary between the first and second refractive index material portions 3 and 4 is configured to have substantially the same angle with respect to the reference plane, and the angle α is set to 45 °. However, when each slope has substantially the same inclination angle, there is an advantage that the design becomes easy. Further, the incident angle range, the critical angle of total reflection, and the like are adjusted as needed by an apparatus using an optical shutter, and a favorable range of the inclination angle cannot be specified unconditionally. When the angle is in the range of 50 ° to 50 °, light reflected on one surface is reflected on a slope facing the same under substantially the same conditions, and good reflection characteristics can be obtained.
For example, in the case of the refractive index material and the incident angle range described above, when the inclination angle α is set to 40 °, the leakage is suppressed to a maximum of 5.7 °, and when the inclination angle α is set to 50 °, the leakage is suppressed to a maximum of 15.7 °. be able to. As described above, in order to suppress the occurrence of light leakage to some extent, it is understood that the inclination angle α is desirably set to approximately 45 °.
[0034]
Further, in the above-described example, the electro-optic material whose refractive index decreases by applying a voltage is used as the material of the second refractive index material portion 4. Even when an optical material is used, it is needless to say that the same effect can be obtained by adjusting the applied voltage and controlling the critical angle.
1 and 2, the optical shutter 10 is formed on a substrate 1 made of, for example, a light-transmitting material. Without being limited to the structure, the optical shutter 10 can be formed on an optical device having various structures for controlling incident light through a light-transmitting insulating layer or the like, or an existing specific pattern can be formed. The optical shutter 10 can also be configured by using the wiring structure as the electrode 2 and forming the first and second refractive index material portions 3 and 4 and the electrode 5 thereon.
[0035]
Further, in the above-described example, the electrode 2 has a single-layer structure, but the lower electrode 2 is orthogonal to the paper surface of FIG. 1 if it is shaped to apply a voltage to the second refractive index material portion 4. Various pattern shapes, such as a stripe pattern extending in the direction, can also be used.
[0036]
Next, each example of the solid-state imaging device using the optical shutter according to the present invention for controlling the incident light to the solid-state imaging device will be described.
(2) Second embodiment
FIG. 4 shows an example in which the present invention is applied to a frame transfer transfer type CCD (FT-CCD type solid-state imaging device). This FT-CCD type solid-state imaging device has a light receiving area 16 and a storage area 17 which are separated from each other and photoelectrically converted in the light receiving area 16 by a vertical transfer register 18 as shown in FIG. The stored charge signal is quickly transferred to the storage region 17, and the stored charge signal is sequentially transferred from the storage region 17 to the horizontal transfer register 19. 21 indicates an amplifier.
[0037]
In such an FT-CCD type solid-state imaging device 20, as shown in FIG. 4, for example, first and second transfer electrodes 13 and 14, which are made of a light-transmitting conductive material such as ITO, are formed on the light receiving portion 12. , Extending in a direction orthogonal to the transfer direction of the vertical transfer register.
[0038]
In this example, a case is shown in which the first transfer electrode 13 of the first and second transfer electrodes 13 and 14 is also used as the lower electrode of the optical shutter 10. That is, the optical shutter 10 in the present embodiment covers the first and second transfer electrodes 13 and 14 so as to cover the first and second refractive index material portions 3 and 3 having an isosceles triangular cross section. 4 is formed thereon, and an electrode 5 for applying a voltage is formed on the second refractive index material section 4. In particular, among the abutting portions corresponding to the so-called triangular prism ridges where the slopes 6 of the first and second refractive index material portions 3 and 4 abut, the abutting portion 15 on the light receiving unit 12 side is the first abutting portion. It is formed so as to be in contact with the transfer electrode 13. The first and second refractive index material parts 3 and 4 are made of SiO 2, respectively, as in the first embodiment.₂Alternatively, PLZT or the like having the above composition ratio can be used. Further, the angle of the slope 6 with respect to the reference plane of the boundary surface between the first and second refractive index material portions 3 and 4 can be set to approximately 45 ° as in the above-described example. The electrode 5 is made of a light-transmitting conductive material such as ITO.
[0039]
By appropriately selecting the voltage to be applied to the first and second transfer electrodes and the electrode 5 on the second refractive index material section 4, the light is reflected or transmitted by the optical shutter 10 to receive light. When an optical signal is received in the unit 12, the light is transmitted, and in the signal transfer operation, light is blocked by an optical shutter to perform light reception and transfer in which noise generation due to light leakage is suppressed. it can. This will be described below.
[0040]
FIGS. 6A and 6B schematically show how the potential inside the substrate changes due to voltage application to the transfer electrodes 13 and 14 during light reception and transfer of the FT-CCD type solid-state imaging device described in FIG. FIG.
[0041]
First, at the time of light reception, as shown in FIG. 6A, 10 V and 5 V are applied to the first and second transfer electrodes 13 and 14, respectively. On the other hand, a voltage of -1 V is applied to the electrode 5 on the second refractive index material section 4. At this time, the applied voltage to the second refractive index material section 4 is 11 V, and as described in detail in the first embodiment, the incident light is converted into the critical angle of total reflection caused by the difference in the refractive index. Therefore, the light passes through the optical shutter 10 and enters the light receiving unit 12.
The light receiving portion 12 is made of, for example, n-type Si, and a portion under the transfer electrodes 13 and 14 is partially provided with, for example, a p-type impurity diffusion region 22 as shown in FIG. As shown by e, the signal charge 26 is accumulated below the first electrode 13.
[0042]
On the other hand, at the time of transfer, as shown in FIG. 6B, voltages of 5 V and 10 V are alternately applied to the first and second transfer electrodes 13 and 14, respectively, and the potential under the transfer electrodes is indicated by solid lines f and g. , And the charges are transferred rightward on the paper surface of FIG. 6 as indicated by the arrow t.
At this time, by applying a constant voltage of 7.5 V to the electrode 5 on the second refractive index material 4, a slight voltage of about 2.5 V is subtracted to the second refractive index material 4. As can be seen from FIG. 3, the refractive index change amount is about 0.05 °, and the critical angle of total reflection is about 36.6 °. Therefore, a difference of only about 0.9 ° occurs as compared with the case where no voltage is applied, and almost light can be totally reflected and shielded.
[0043]
Since the solid-state imaging device having such a configuration does not require a mechanical shutter, the size of a device incorporating the device can be significantly reduced. In addition, when the mechanical shutter is not provided, it is possible to avoid a reduction in the life due to deterioration of the mechanical parts. Furthermore, when using PLZT, it is possible to provide a small-sized solid-state imaging device having a light blocking function with excellent response speed.
Particularly, in the above-described example, since the optical shutter is provided by also using the transfer electrode as the lower electrode, it is advantageous in reducing the number of manufacturing steps and in reducing the size and thickness of the device.
[0044]
In the above-described embodiment, the case where the first and second transfer electrodes 13 and 14 are provided on the light receiving section in the FT-CCD type solid-state imaging device has been described. The present invention is not limited to this, and various modifications and changes can be made, for example, when three or more transfer electrodes are provided. Needless to say, the same effect can be obtained in this case.
[0045]
(3) Third embodiment
Next, a case where the present invention is applied to a CCD solid-state imaging device (IT-CCD solid-state imaging device) of an interline transfer transfer system will be described.
FIG. 7 is a schematic configuration diagram of an example of the IT-CCD type solid-state imaging device 25. In FIG. 7, reference numerals 18 and 19 denote a vertical transfer register and a horizontal transfer register, 23 denotes each light receiving section, and 24 denotes a read gate section. 21 is an amplifier. The signal charge received by each light receiving unit 23 is transferred to the vertical transfer register 18 via the read gate unit 24, further transferred to the horizontal transfer register 19, and read as a charge signal.
[0046]
FIG. 8 shows an example of a cross-sectional configuration on an AA line of an example of such an IT-CCD type solid-state imaging device 25. In FIG. 8, 51 is a substrate made of Si or the like, 52 is a first p-type well, 53 is a second p-type well, 54 is an n-type impurity region, 55 is a channel stop region, 56 is an insulating layer, 57 is an electrode, 58 and Reference numeral 59 denotes n-type and p-type impurity regions, which constitute the light receiving unit 23. In a region other than the light receiving section 23, a light shielding film 61 made of Al or the like is formed via an insulating layer 60. And for example SiO₂The color filter 63 and the on-chip lens 64 are formed by flattening with an insulating layer 62 made of the same.
[0047]
In this example, an electrode 2 made of a light-transmitting conductive material such as ITO,₂The first and second refractive index material portions 3 and 4 are provided. The first and second refractive index material portions 3 and 4 are provided with an electrode 5 made of ITO or the like. The cross section is formed as a triangular prism having an isosceles triangular cross section so that the opposite slopes have an angle of, for example, approximately 45 ° from a reference plane orthogonal to the light incident reference axis.
[0048]
With such a configuration, when no voltage is applied between the electrodes 2 and 5, almost all incident light is reflected, and when a voltage of about 11 V is applied, most of the light is transmitted and light is transmitted to the light receiving portion 23. Can be provided in the IT-CCD type solid-state imaging device.
[0049]
In the solid-state imaging device having such a configuration of the present invention, it is possible to provide a solid-state imaging device having a light-shielding function with excellent response speed, in which the size of the device can be reduced as compared with the case where a mechanical shutter is provided. it can. Further, when the mechanical shutter is not provided, it is possible to prevent the life from being shortened due to damage to mechanical parts and the like.
[0050]
In the above-described example, the case where the optical shutter is provided on the color filter and the on-chip lens has been described. However, the color filter and the on-chip lens may be provided on the other optical shutter, Various modifications and changes are possible, such as a configuration in which another mechanism such as a waveguide section on the light receiving section can be provided.
Furthermore, in this case, the direction in which the slopes 6 of the first and second refractive index material portions 3 and 4 extend does not have to be parallel to the direction in which the vertical transfer register extends, but extends along the horizontal transfer register. It may be extended in the direction or oblique to each register. The on-chip lens shape can be variously modified, for example, a concave lens shape in an insulating layer.
[0051]
(4) Fourth embodiment
Next, a case where the present invention is applied to a CMOS sensor type solid-state imaging device will be described with reference to FIG. In FIG. 9, reference numeral 71 denotes a base, 72 denotes an element isolation region, 73 denotes a light receiving portion, 74 denotes an insulating layer, and 75 denotes a transfer gate for transferring charges photoelectrically converted by the light receiving portion. Then, an insulating layer 76 is adhered thereon, and a first wiring layer 78 is provided thereon, for example, extending in the X scanning direction. Reference numeral 77 denotes a first conductive plug for connecting the first wiring layer 78. Then, a second wiring layer 81 extending in, for example, the Y-scanning direction is similarly provided via the intermediate insulating layer 79 on this. Reference numeral 80 denotes a second conductive plug for connecting the second wiring layer. An insulating layer 82 is provided on the wiring layer 81, and its surface is planarized.
[0052]
In this example, the electrode 2 made of a light-transmitting conductive material, such as ITO,₂A first refractive index material portion 3 made of a material such as PLZT, a second refractive index material portion 4 made of a material such as PLZT, and an electrode 5 made of ITO or the like are provided. Also in this example, the first and second refractive index material portions 3 and 4 can be provided as triangular prisms having an isosceles triangular cross section. It is formed so as to be substantially equal to, for example, 45 ° with respect to a reference plane orthogonal to the axis.
[0053]
Also in this case, almost no light is totally reflected when no voltage is applied to the second refractive index material portion 3, and light is transmitted when a voltage of about 11 V is applied. Can be configured.
Further, in the CMOS sensor type solid-state imaging device according to the above-described configuration of the present invention, similarly to the above-described embodiments, the light-shielding mechanism which is smaller in size than the case where the mechanical shutter is provided and which has an excellent response speed. Can be configured. Further, since the mechanical shutter is not provided, it is possible to prevent the life from being shortened.
[0054]
(5) Fifth embodiment
Next, an example of a method for manufacturing an optical shutter according to the present invention will be described with reference to the process charts of FIGS. In this example, a case where an optical shutter is formed on the base material 1 will be described. However, the present invention is not limited to the base material 1, and in the FT-CCD type solid-state imaging device, the first and second transfer electrodes may be formed. An electrode 2 can be formed on the electrode 2 so as to cover the surface of the electrode 2. Similarly, an optical shutter can be formed on the electrode 2. It is needless to say that the optical shutter can be formed on the optical shutter similarly.
[0055]
First, as shown in FIG. 10A, an electrode 2 made of light-transmissive ITO or the like is entirely coated on a base material 1 made of, for example, light-transmissive PC. On top of this, SiO₂Then, a first refractive index material layer 3a made of, for example, is entirely applied, and a photosensitive layer 91 such as a photoresist is entirely applied thereon. Then, for example, a light-transmitting mold 92 having a surface shape in which triangular prisms having an isosceles cross section are arranged side by side is brought, and is pressed onto the photosensitive layer 91 as shown by an arrow h.
[0056]
As shown in FIG. 10B, opposing slopes 93 are formed on the surface of the photosensitive layer 91 by pressing of a light transmitting mold. By adjusting the shape of the light-transmitting mold 92 and the pressing direction thereof, the angle of the inclined surface 93 can be adjusted with respect to a reference plane orthogonal to the reference axis direction of the incident light. Can be formed.
[0057]
The photosensitive layer 91 is irradiated with light and cured, and then, as shown in FIG. 10C, by anisotropic dry etching such as RIE (reactive ion etching), as shown by an arrow i, Etching is performed in a direction perpendicular to the laminating direction. At this time, the etching proceeds while maintaining the surface shape of the photosensitive layer 91, and a slope having the same slope angle as the slope 93 formed on the surface of the photosensitive layer 91 is formed in the first refractive index material portion 3a. The first refractive index material portion 3 having the slopes facing each other can be formed.
[0058]
Next, a second refractive index material portion made of PLZT or the like is formed thereon by sputtering or spin coating so as to embed the slope 6, and is further formed thereon by ITO or the like. The optical shutter having the configuration of the present invention can be manufactured by depositing the electrode 5 formed by a sputtering method or the like.
[0059]
According to such a manufacturing method, by using a light-transmitting mold, an inexpensive and simple optical shutter in which opposing inclined surfaces having a desired inclination angle are provided at a boundary surface, and a solid-state imaging device using the same. Can be manufactured.
[0060]
Note that the present invention is not limited to the examples described in the above embodiments, and the first and second refractive index material portions may have a plurality of first pyramid-shaped first refractive index material portions, for example. The second refractive index material portion is arranged side by side in the vertical transfer direction and the horizontal transfer direction, and the second refractive index material portion is applied so as to cover the vertical transfer direction and the horizontal transfer direction. Is possible.
[0061]
Further, when the present invention is applied to a solid-state imaging device, it goes without saying that the present invention is not limited to the above-described second to fourth embodiments, but can be applied to various other solid-state imaging devices.
[0062]
【The invention's effect】
As described above, according to the present invention, since an optical shutter using an electro-optical material is configured, it is possible to provide a small optical shutter having excellent response speed and a solid-state imaging device using the same. In particular, when the mechanical shutter is not provided, it is possible to prevent the life from being shortened due to the deterioration of the component or the like.
[0063]
Further, in the present invention, when the slope, which is the boundary surface between the first and second refractive index material portions, is configured so that the slope angle is substantially equal to the reference plane, the design is facilitated and most of the incident light is reduced. A configuration in which total reflection or transmission is ensured can be achieved.
Further, when the angle between the opposed slopes of the first and second refractive index material portions and the reference surface is set to be about 40 ° or more and about 50 ° or less, a shutter that suppresses leakage of incident light is configured. Can be.
[0064]
Further, according to the method for manufacturing an optical shutter and the method for manufacturing a solid-state image sensor according to the present invention, the optical shutter and the solid-state image sensor according to the present invention can be easily manufactured.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an example of an optical shutter.
FIG. 2 is an explanatory diagram of a light reflection mode of an optical shutter.
FIG. 3 is a diagram showing the applied voltage dependence of the amount of change in the refractive index of PLZT.
FIG. 4 is a schematic configuration diagram of an example of a solid-state imaging device.
FIG. 5 is a schematic configuration diagram of an example of a solid-state imaging device.
FIG. 6A is an explanatory diagram of a potential at the time of receiving light of an example of a solid-state imaging device. B is an explanatory diagram of the potential at the time of transfer of an example of the solid-state imaging device.
FIG. 7 is a schematic configuration diagram of an example of a solid-state imaging device.
FIG. 8 is a schematic configuration diagram of an example of a solid-state imaging device.
FIG. 9 is a schematic configuration diagram of an example of a solid-state imaging device.
FIG. 10A is a manufacturing process diagram of the optical shutter.
B is a manufacturing process diagram of the optical shutter.
C is a manufacturing process diagram of the optical shutter.
D is a manufacturing process diagram of the optical shutter.
[Explanation of symbols]
Reference Signs List 1 base material, 2 electrodes, 3 first refractive index material section, 4 second refractive index material section, 5 electrodes, 6 slopes, 6A slope, 6B slope, 7 reference plane, 10 optical shutter, 11 base, 12 light reception Unit, 13 first transfer electrode, 14 second transfer electrode, 15 abutment unit, 18 vertical transfer register, 19 horizontal transfer register, 20 FT transfer type solid-state imaging device, 22 impurity diffusion region, 23 light receiving unit, 24 reading Gate part, 25 IT transfer type solid-state imaging device, 26 signal charge, 51 base, 52 first p-type well, 53 second p-type well, 54 n-type impurity region, 55 channel stop region, 56 insulating layer, 57 electrode, 58 p -Type impurity region, 59 n-type impurity region, 60 insulating layer, 61 light shielding film, 62 insulating layer, 63 color filter, 64 on-chip lens, 65 insulating layer , 71 base, 72 element isolation region, 73 light receiving section, 74 insulating layer, 75 transfer gate, 76 insulating layer, 77 first conductive plug, 78 first wiring layer, 79 intermediate insulating layer, 80 second conductive plug , 81 second wiring layer, 82 insulating layer, 91 photosensitive layer, 92 type

Claims (9)

At least a first and a second refractive index material portion, and an electrode for applying a voltage to the second refractive index material portion;
A boundary surface between the first and second refractive index material portions is formed by opposed slopes, and the first and second refractive index material portions are laminated,
The optical shutter, wherein the second refractive index material portion is made of a material having an electro-optic effect. The slope, which is a boundary surface between the first and second refractive index material portions, is formed such that an angle formed between the reference surface orthogonal to a reference axis in a light incident direction and the slope is substantially equal. Item 2. The optical shutter according to item 1. 3. The optical shutter according to claim 2, wherein an angle formed between the inclined surface of the first and second refractive index material portions and the reference surface is in a range of 40 to 50 degrees. An optical shutter is provided at least above the light receiving section,
The optical shutter includes at least first and second refractive index material portions and an electrode that applies a voltage to the second refractive index material portion,
A boundary surface between the first and second refractive index material portions is formed by opposed slopes, and the first and second refractive index material portions are stacked,
The solid-state imaging device according to claim 1, wherein the second refractive index material portion is made of a material having an electro-optic effect. The slope, which is a boundary surface between the first and second refractive index material portions, is formed such that an angle formed between the reference surface orthogonal to a reference axis in a light incident direction and the slope is substantially equal. Item 5. A solid-state imaging device according to item 4. The solid-state imaging device according to claim 5, wherein an angle formed between the slope and the reference surface of the first and second refractive index material portions is set to be equal to or greater than 40 ° and equal to or less than 50 °. Frame transfer type transfer method,
5. The solid-state imaging device according to claim 4, wherein one of electrodes for applying a voltage to the first and second refractive index material portions is also used as an electrode of a vertical transfer register. Forming one of the electrodes;
Forming a first refractive index material layer on the electrode;
Depositing a photosensitive layer on the first refractive index material layer;
A light transmissive mold having a shape provided with opposed slopes is pressed against the surface of the photosensitive layer, and the photosensitive layer is cured by irradiating light, and then the photosensitive layer and the photosensitive layer are anisotropically dry-etched. Etching the first refractive index material layer to form a first refractive index material portion having opposing slopes;
A second refractive index material layer made of a material having an electro-optical effect is coated on the first refractive index material layer so as to bury the slope of the first refractive index material layer formed by the etching. Forming a second refractive index material portion by attaching
Forming the other electrode on the second refractive index layer. A method for manufacturing a solid-state imaging device having an optical shutter,
Forming at least one electrode on the light receiving section,
Forming a first refractive index material layer on the electrode;
Depositing a first photosensitive layer on the first refractive index material layer;
A light transmissive mold having a shape provided with opposed slopes is pressed against the surface of the photosensitive layer, and the photosensitive layer is cured by irradiating light, and then the photosensitive layer and the photosensitive layer are anisotropically dry-etched. Etching the first refractive index material layer to form a first refractive index material portion having opposing slopes;
A second refractive index material layer made of a material having an electro-optical effect is coated on the first refractive index material layer so as to bury the slope of the first refractive index material layer formed by the etching. Forming a second refractive index material portion by attaching
Forming the other electrode on the second refractive index layer.

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