TWI682190B - Optical element - Google Patents

Abstract

An optical element including a light shading portion having high adhesion with transparent substrate and extremely low reflectivity at the surface thereof is provided. The optical element for an image device equipped with a solid image element inside comprises: a transparent substrate having an incident surface and an emitting surface on its face and back surfaces, wherein a light enters the incident surface toward the solid image element, and the light entering the incident surface passes through and emits from the emitting surface toward the solid image element; a light shading film formed in a frame shape on at least one surface of the incident surface and the emitting surface and blocking a portion of the light; an anti-reflection film covering the light shading film and an opening portion of the light shading film; a light transmitting portion and a light shading portion, the light transmitting portion restraining the light entering the region at the opening portion of the light shading film from reflecting while letting it transmit, and the light shading portion restraining the light entering the region of the light shading film from reflecting while blocking it.

Description

Optical element

The invention relates to an optical element, which is an optical element arranged in front of a solid photographic element, in particular, it is installed in front of a package that houses the solid photographic element, protects the solid photographic element and is used as a protective glass for a light-transmitting window, for solids Optical components such as near-infrared cut filters for the visibility correction of photographic elements.

In recent years, photographic elements with solid-state photographic elements such as CCD and CMOS have been used in mobile phones and portable information terminal equipment. Such an imaging element includes a ceramic and resin bucket-shaped package that houses a solid imaging element, and a cover glass that is fixed to the peripheral portion of the package by an ultraviolet curing adhesive and seals the solid imaging element.

In addition, in general, since the solid-state imaging element has spectral sensitivity from the near-ultraviolet region to the near-infrared region, it has a near-infrared cut-off filter that blocks the near-infrared portion of incident light and corrects it so as to be close to human visibility. Photographic elements are also for practical use. In order to reduce the size of the entire photographic module, a cover glass that combines the functions of a cover glass and a near-infrared cut filter has also been proposed (for example, Patent Document 1).

The near-infrared cut filter described in Patent Document 1 has: a plate Transparent substrate (for example, infrared absorption glass), an ultraviolet/infrared light reflection film composed of a dielectric multilayer film formed on one side of the transparent substrate, and an anti-reflection film formed on the other side of the transparent substrate.

In addition, if such a near-infrared cut filter and other optical components are arranged in front of the solid-state imaging element (that is, in the optical path), light reflected on the side surface of the near-infrared cut filter, etc. enters the solid-state imaging element for imaging. This causes problems such as reflected light spots and ghosting. Therefore, in the near-infrared cut filter described in Patent Document 1, it is proposed to further form a frame-shaped light-shielding layer (light-shielding film) on the ultraviolet/infrared light reflecting film ), a measure to cut off the optical path of light that causes ghosting or the like.

Existing technical literature Patent Literature

Patent Document 1: Japanese Patent Application Publication No. 2013-068688

Thus, according to the near-infrared cut filter described in Patent Document 1, the near-infrared portion of the incident light can be cut, and the optical path of light that causes ghosts or the like can be blocked.

However, since the light-shielding film of the near-infrared cut filter described in Patent Document 1 is formed by coating a photocurable resin on an ultraviolet/infrared light reflecting film and vapor-depositing a black metal such as Cr, it is in close contact with a transparent substrate The sex is not strong, there is a problem of peeling off due to the environment used.

In addition, if a black metal such as Cr is deposited to form a light-shielding film, then An extremely thin light-shielding film can be formed, but on the other hand, the reflection at the light-shielding film cannot be suppressed, and the light reflected by the light-shielding film becomes ghost light, and there is a problem of deterioration in image quality.

The present invention was carried out in consideration of such a problem, and an object of the present invention is to provide an optical element including a light-shielding portion having a light-shielding film with high adhesion to a transparent substrate and having an extremely low reflectance.

In order to achieve the above object, the optical element of the present invention is an optical element used in an imaging device incorporating a solid-state imaging element, and is characterized in that it includes an incident surface having light incident toward the solid-state imaging element on the front and back surfaces and incident on the incident surface The transparent substrate on which the light of the surface passes and exits toward the solid-state imaging element is formed on at least one of the entrance surface and the exit surface into a frame-shaped light-shielding film that covers part of the light to cover the light-shielding film and the light shield An anti-reflection film formed as an opening of the film; a light-transmitting portion that allows reflection of light entering the area of the opening of the light-shielding film to be reflected while suppressing light entering the area of the light-shielding film A light-shielding portion that reflects and blocks light while blocking it.

According to such a configuration, since the light-shielding film is directly formed on the transparent substrate, the adhesion of the light-shielding film is extremely high. In addition, since the light-shielding film is covered with the anti-reflection film, the reflectance at the light-shielding portion is extremely low.

In addition, the light-shielding film is preferably formed of a thin film containing at least Cr. In addition, in this case, the light-shielding film preferably includes a first thin film formed of Cr, a second thin film formed of Cr ₂ O ₃ and formed between the first thin film and the transparent substrate, and formed of Cr ₂ O ₃ The third thin film formed between the first thin film and the anti-reflection film. In addition, in this case, the third thin film is preferably connected to the anti-reflection film, and the film thickness is 55 to 63 nm.

In addition, it is preferable that the area of the light-transmitting portion is larger than the area of the light-receiving surface of the solid-state imaging element.

In addition, the optical element is preferably a cover glass mounted on the front of the package that houses the solid-state imaging element.

In addition, the transparent substrate is preferably near-infrared absorbing glass that absorbs light of a wavelength in the near-infrared region. Further, in this case, preferably the near infrared absorbing glass is a fluorophosphate glass containing Cu ^2+-based or phosphate-based glass containing Cu ²⁺ constituted. According to such a configuration, the spectroscopic sensitivity of the solid-state imaging element can be corrected so as to be close to human visibility.

In addition, the light-shielding film can be formed by etching. In addition, in this case, it is preferable to provide an etching stopper functioning as an etching stopper between the light-shielding film and the transparent substrate. According to such a configuration, the etching barrier layer is formed on the transparent substrate. Therefore, when the light-shielding portion is formed by a patterning technique using an etchant formed by photolithography, screen printing, or the like, the etching barrier layer prevents etching, and the transparent substrate The surface will not be etched by the etching solution. Therefore, the surface of the transparent substrate is not roughened, it is possible to prevent the light incident on the surface of the transparent substrate from being scattered, and it is possible to obtain an image with high resolution from the solid-state imaging element. In addition, since the etching can be reliably prevented through the etching barrier layer, the entire optical element can be immersed in the etching liquid for a relatively long time, and a light-shielding portion with no etching residue and uniform edges can be formed.

In addition, the etching barrier layer is preferably formed of a thin film of SiO ₂ , Al ₂ O ₃ or ZrO ₂ .

In addition, when the reference wavelength of light is λ , it is preferable that the optical film thickness of the etching stop layer is approximately λ /2. According to such a configuration, the etching barrier layer does not affect the performance of the anti-reflection film, and the film design of the anti-reflection film becomes easy.

In addition, the physical film thickness of the etching barrier layer may be 0.3 to 200.0 ppm relative to the plate thickness of the transparent substrate. According to such a configuration, it is possible to suppress the warpage of the transparent substrate due to the film stress of the etching barrier layer.

In addition, it is preferable that the thickness of the transparent substrate is 0.1 to 1.0 mm, and the physical film thickness of the etching stop layer is 0.3 to 20.0 nm.

As described above, according to the present invention, an optical element including a light-shielding portion having a light-shielding film with high adhesion to a transparent substrate and having a very low reflectance is realized.

1‧‧‧Solid photography equipment

100, 100A‧‧‧protective glass

101‧‧‧Glass substrate

101a‧‧‧incidence surface

101b‧‧‧Ejection surface

103、106‧‧‧Etching barrier

105, 107‧‧‧ shading film

105a, 105c‧‧‧Cr ₂ O ₃ film

105b‧‧‧Cr film

110、120‧‧‧Anti-reflective film

110a‧‧‧Al ₂ O ₃ film

110b‧‧‧ZrO ₂ film

110c‧‧‧MgF ₂ film

200‧‧‧Solid photographic element

300‧‧‧Packing

S‧‧‧Shade

T‧‧‧Transparent

FIG. 1 is an explanatory diagram of the configuration of cover glass according to the first embodiment of the present invention.

FIG. 2 is a longitudinal cross-sectional view illustrating the configuration of a solid-state imaging device equipped with cover glass according to the first embodiment of the present invention.

FIG. 3 is a graph showing the wavelength characteristics of the reflectance of the light shielding portion of the cover glass according to the first embodiment of the present invention.

FIG. 4 is a flowchart showing a method of manufacturing cover glass according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a modification of the cover glass according to the first embodiment of the present invention.

FIG. 6 is a diagram showing a modification of the cover glass according to the first embodiment of the present invention.

FIG. 7 is a diagram showing a modification of the cover glass according to the first embodiment of the present invention.

FIG. 8 is an explanatory diagram of the configuration of the cover glass according to the second embodiment of the present invention.

FIG. 9 is a flowchart showing a method of manufacturing cover glass according to a second embodiment of the present invention.

Fig. 10 is a diagram showing a modification of the cover glass according to the second embodiment of the present invention.

FIG. 11 is a diagram showing a modification of the cover glass according to the second embodiment of the present invention.

FIG. 12 is a diagram showing a modification of the cover glass according to the second embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that in the figures, the same or corresponding parts bear the same symbols, and descriptions are not repeated.

(First embodiment)

FIG. 1 is an explanatory diagram of the configuration of cover glass 100 (optical element) according to the first embodiment of the present invention, FIG. 1(a) is a plan view of cover glass 100, and FIG. 1(b) is a longitudinal cross-sectional view FIG. 1(c) is an explanatory diagram of the film configuration of the light-shielding film 105 and the anti-reflection film 110 formed on the cover glass 100. another In addition, FIG. 2 is a longitudinal cross-sectional view illustrating the configuration of the solid-state imaging device 1 in which the opening of the package 300 of the solid-state imaging element 200 is sealed by the cover glass 100 of the present embodiment. The cover glass 100 of the present embodiment is mounted on the front surface (ie, opening) of the package 300 that houses the solid-state imaging element 200 (FIG. 2 ), protects the solid-state imaging element 200, and is used as an optical element for a light-transmitting window.

As shown in FIG. 1, the cover glass 100 of the present embodiment has a rectangular plate-like appearance, and is composed of a glass substrate 101 (transparent substrate), a frame-shaped light-shielding film 105 formed on the glass substrate 101, and a light-shielding film 105 The anti-reflection film 110 is formed as an opening of the light-shielding film 105. It should be noted that in this embodiment, when the cover glass 100 is attached to the package 300 on the side of the glass substrate 101 on which the light shielding film 105 and the anti-reflection film 110 are formed (the upper surface in the first (b) figure) side Becomes the incident surface 101a on which light toward the solid-state imaging element 200 enters, and the other surface of the glass substrate 101 (the lower surface in the first (b) diagram) side becomes the exit surface 101b on which light incident on the incident surface 101a exits. In addition, the size of the cover glass 100 is suitably set according to the size of the package 300 to which the cover glass 100 is mounted, and is set to 6 mm (horizontal)×5 mm (vertical) in this embodiment.

Glass substrate 101 of the present embodiment is an infrared absorbing glass containing Cu ²⁺ (Cu ²⁺ containing fluorophosphate-based glass or phosphate glass containing Cu ²⁺ is). In general, fluorophosphate-based glass has excellent weather resistance, and by adding Cu ^{2+ to the} glass, it can absorb near infrared rays while maintaining high transmittance in the visible light region. Therefore, if the glass substrate 101 is arranged in the optical path of the incident light incident on the solid-state imaging element 200, it functions as a low-pass filter and is corrected so that the spectral sensitivity of the solid-state imaging element 200 approaches human visibility. . The fluorophosphate-based glass used in the glass substrate 101 of the present embodiment can use a known glass composition, but it is particularly preferable to contain Li ⁺ and alkaline earth metal ions (eg, Ca ²⁺ , Ba ^2+, etc.) , The composition of rare earth element ions (Y ³⁺ , La ^3+, etc.). In addition, the thickness of the glass substrate 101 of the present embodiment is not particularly limited, and from the viewpoint of achieving compactness and weight reduction, it is preferably in the range of 0.1 to 1.0 mm.

The light-shielding film 105 is a multilayer film of Cr (chromium) and Cr ₂ O ₃ (chromium oxide) vapor-deposited on the glass substrate 101 (hereinafter, the multilayer film of Cr and Cr ₂ O ₃ is also referred to as “Cr multilayer film”) It has a function of blocking part of the incident light incident on the incident surface 101a, and removing unnecessary light that causes ghosts and the like. The light-shielding film 105 is formed in a frame shape along the outside of the glass substrate 101 when the glass substrate 101 is viewed from above. It should be noted that the light-shielding film 105 (ie, Cr multilayer film) of the present embodiment is designed to efficiently block at least incident light with a wavelength of 420 to 680 nm. As shown in FIG. 1(c), the optical film thickness is approximately λ/ 4 (λ is the reference wavelength: 520 nm) Cr ₂ O ₃ thin film 105a, optical film thickness approximately λ/2 Cr film 105b, optical film thickness approximately λ/4 (physical film thickness: 55~63nm) Cr ₂ O ₃ The thin film 105c is sequentially stacked on the glass substrate 101, and the photolithography method after transmission is formed by patterning only the light-shielding film 105 (details will be described later).

The anti-reflection film 110 is an optical film formed so as to cover the light shielding film 105 and the opening of the light shielding film 105, and has a wavelength of 420 to 680 nm that suppresses the incidence surface 101a entering the glass substrate 101 through the opening of the light shielding film 105 The function of reflecting the incident light and suppressing the reflection of the incident light having a wavelength of 420 to 680 nm that enters the light-shielding film 105. As shown in FIG. 1(c), the anti-reflection film 110 of the present embodiment is composed of an Al ₂ O ₃ thin film 110a with an optical film thickness of approximately λ/4, a ZrO ₂ thin film 110b with an optical film thickness of approximately λ/2, and an optical film thickness A MgF ₂ thin film 110c of approximately λ/4 is formed, and each thin film is formed by sequentially stacking by a sputtering method, a vacuum evaporation method, or the like. Thus, if the Al ₂ O ₃ thin film 110 a, the ZrO ₂ thin film 110 b, and the MgF ₂ thin film 110 _c are sequentially formed on the light shielding film 105, the reflected light from the interface of each thin film and the light shielding film 105 (specifically, the Cr thin film 105 b The reflected light of the Cr ₂ O ₃ thin film 105c) interferes and cancels each other, so the reflection of the incident light is suppressed. In addition, if the Al ₂ O ₃ thin film 110a, the ZrO ₂ thin film 110b, and the MgF ₂ thin film 110c are sequentially formed at the opening of the light shielding film 105, the reflected light from the interface of each thin film and the reflection from the incident surface 101a of the glass substrate 101 The light interferes and cancels each other, so the reflection of the incident light is suppressed.

If the anti-reflection film 110 is formed so as to cover the light-shielding film 105 and the opening of the light-shielding film 105, as shown in FIG. 1, in the region of the opening of the light-shielding film 105, an incident light is transmitted while suppressing reflection. In the light-transmitting portion T, a light-shielding portion S is formed in the region of the light-shielding film 105 to block incident light while suppressing reflection. If the anti-reflection film 110 is provided on the cover glass 100, the reflection in the light-transmitting portion T is suppressed, so the light introduction efficiency in the solid-state imaging element 200 increases. In addition, since the reflection at the light shielding portion S is suppressed, the occurrence of ghost light due to the reflected light is also suppressed.

Thus, the anti-reflection film 110 of the present embodiment has both the function of suppressing the reflection of incident light having a wavelength of 420-680 nm incident on the translucent portion T and the function of suppressing the reflection of incident light having a wavelength of 420-680 nm incident on the light-shielding portion S Function, but because the refractive index of the glass substrate 101 and the refractive index of the light-shielding film 105 are different, it is only a simple combination of the optimized anti-reflection film 110 and the light-shielding film 105, and it is difficult to realize both functions at the same time. In this embodiment, by optimizing the film thickness of the Cr ₂ O ₃ thin film 105c as the uppermost layer of the light-shielding film 105 (that is, the layer that is in contact with the anti-reflection film 110) in conjunction with the anti-reflection film 110, both functions are realized simultaneously .

FIG. 3 is a simulation result showing the wavelength characteristic of the reflectance R of the light shielding portion S of the present embodiment. The uppermost layer of the light shielding film 105, that is, the film thickness t (physical film thickness) of the Cr ₂ O ₃ thin film 105c is 48 to It is changed within the range of 69 nm, and the wavelength characteristic of the reflectance R at each film thickness t is also given. In addition, in FIG. 3, the horizontal axis represents wavelength (nm), and the vertical axis represents reflectance R (%).

As shown in FIG. 3, the wavelength characteristic of the reflectance R of the light-shielding portion S is different from the film thickness t of the Cr ₂ O ₃ thin film 105c as the uppermost layer of the light-shielding film 105, and the reflectance R at each film thickness t shows low The wavelength range (wavelength range below 520 nm) and the high wavelength range (wavelength range above 570 nm) tend to become higher. In addition, it can be seen that the wavelength characteristic is that the reflectance R is higher in the low wavelength region and lower in the high wavelength region, and higher in the high wavelength region is lower in the low wavelength region. Here, the curve of the ideal wavelength characteristic of the reflectance R of the light shielding portion S is preferably flat in the wavelength range of 420 to 680 nm, and the average value is low. The inventors of the present invention obtained the average reflectance Rm, the standard deviation σ, and the slope s of the regression line of the reflectance R in the wavelength range of 420 to 680 nm, and evaluated them to determine the most suitable for this embodiment. The thickness t of the Cr ₂ O ₃ thin film 105c.

Table 1 gives the wave of reflectance R at each film thickness t in Fig. 3 For the long characteristics, the results of the average reflectance Rm, standard deviation σ, and the slope s of the regression line and the results of evaluating these three parameters were obtained at a wavelength of 420 to 680 nm.

The average reflectance Rm is a parameter for evaluating the average characteristic of the reflectance R in the wavelength range of 420 to 680 nm, and the smaller the value, the more preferable. In addition, the standard deviation σ is a parameter for evaluating the difference in reflectance R in the wavelength range of 420 to 680 nm, and the smaller the value, the more preferable. In addition, the slope s of the regression line is a parameter for evaluating the flatness of the reflectance R in the wavelength range of 420 to 680 nm, and the smaller the absolute value, the more preferable. As the evaluation in this embodiment, it is preferable to perform evaluation based on an average reflectance Rm of 2% or less, a standard deviation σ of 1.5 or less, and a slope s of a regression line of ±0.015 or less (indicated by the "○" mark in Table 1) It is more preferable to evaluate based on an average reflectance Rm of 1.5% or less, a standard deviation σ of 1.2 or less, and a slope s of the regression line of ±0.01 or less (indicated by the "◎" symbol in Table 1). From this result, it can be seen that the film thickness t of the Cr ₂ O ₃ thin film 105c most suitable for this embodiment is 55 to 63 nm, and more preferably 56 to 61 nm.

Therefore, in this embodiment, the film thickness t of the Cr ₂ O ₃ thin film 105 _c as the uppermost layer of the light-shielding film 105 is set to 55 to 63 nm, which is optimized for the anti-reflection film 110.

As shown in FIG. 2, the protective glass 100 is used for plugging and storing CCD (Charge-Coupled Device), CMOS (Complementary Metal Oxide) (Semiconductor) and other solid-state imaging elements 200 are attached to the opening of the bucket package 300, and are fixed by an adhesive (not shown). If the cover glass 100 is mounted on the package 300, it is placed in the optical path of the incident light incident on the solid-state imaging element 200. However, as described above, the light shielding portion S is formed on the cover glass 100. Unnecessary light is incident on the imaging element 200, and ghosting and reflected light spots do not occur. It should be noted that the sizes of the light-transmitting portion T and the light-shielding portion S are appropriately determined according to the optical elements such as lenses disposed outside the solid-state imaging device 1, the size of the solid-state imaging element 200, and the size of the cover glass 100, but according to The light of the portion T is received on the light-receiving surface of the solid-state imaging element 200 such that at least the area of the light-transmitting portion T is larger than the area of the light-receiving surface of the solid-state imaging element 200.

Next, the manufacturing method of the cover glass 100 of this embodiment is demonstrated. FIG. 4 is a flowchart showing the method of manufacturing the cover glass 100 according to this embodiment. FIG. 4(a) is a flowchart showing the manufacturing process of the cover glass 100, FIG. 4(b) is an enlarged plan view of the cover glass 100 corresponding to each manufacturing process, and FIG. 4(c) is a plan corresponding to each manufacturing process An enlarged cross-sectional view of the cover glass 100 in the manufacturing process. In addition, in order to make it easy to understand, in FIG. 4 (b), each component is shaded, and in FIG. 4 (c), each component is highlighted.

(Molding of glass substrate)

In the molding process of the glass substrate, a glass plate composed of glass having desired optical characteristics is prepared, and the glass plate is cut by a known cutting method so that the outer dimensions are substantially the same as the final shape (that is, the shape of the cover glass 100) Break. The cutting method includes the method of cutting off the cutting line through the diamond cutter, through Cutting method for cutting. In addition, as the glass plate used in this process, the glass plate processed by rough grinding|polishing etc. can be processed to the plate thickness dimension which is close to the final shape. After the glass plate is cut, washing is performed to obtain a glass substrate 101.

(Formation of Cr multilayer film)

Next, in the formation process of the Cr multilayer film, on the incident surface 101a of the glass substrate 101, an optical film thickness of approximately λ/4 (for example, physical Film thickness: 58.8 nm) Cr ₂ O ₃ thin film 105a, optical film thickness approximately λ/2 (for example, physical film thickness: 91.6 nm) Cr film 105b, optical film thickness approximately λ/4 (physical film thickness: 55-63 nm ) Cr ₂ O ₃ thin film 105a. Specifically, the Cr ₂ O ₃ thin film 105a is formed while introducing oxygen, then the Cr thin film 105b is formed while introducing oxygen, and then the Cr ₂ O ₃ thin film 105c is formed while introducing oxygen.

(Resist coating/baking)

In the resist coating/baking process, a photoresist is coated on the surface of the Cr multilayer film and baked for a predetermined time. As long as the photoresist changes its solubility under the action of light in the ultraviolet wavelength range or infrared wavelength range, the material is not particularly limited. In addition, as the coating method of the photoresist, a well-known spin coating method, dip coating method, or the like can be applied.

(Exposure/Resist Development)

In the exposure/resist development process, first, the photoresist is irradiated with light through a photomask patterning the light-shielding film 105. Then, using a developing solution corresponding to the photoresist, the photoresist is developed to form a resist corresponding to the pattern of the light-shielding film 105.

(Patterned)

In the patterning process, the glass substrate 101 is immersed in a Cr etchant to etch the Cr multilayer film where no resist is formed. In addition, as a Cr etching liquid, for example, a mixed solution of cerium nitrate salt: 10 to 20%, perchloric acid: 5 to 10%, and water: 70 to 85% is used.

(Resist stripping)

In the resist stripping process, the resist is immersed in a resist stripper such as alcohol to strip the resist. Thus, the light-shielding film 105 is formed on the glass substrate 101. Thus, the light-shielding film 105 of the present embodiment is formed through so-called photolithography.

(Formation of anti-reflection film)

In the formation process of the anti-reflection film, an Al ₂ O ₃ thin film having an optical film thickness of approximately λ/4 (for example, physical film thickness: 78.8 nm) is sequentially formed on the light-shielding film 105 by a sputtering method, a vacuum evaporation method, or the like 110a, a ZrO ₂ thin film 110b with an optical film thickness of approximately λ/2 (for example, physical film thickness: 124.9 nm), and an MgF ₂ thin film 110c with an optical film thickness of approximately λ/4 (for example, physical film thickness: 93.4 nm) to form an anti-reflection film 110. Thus, the cover glass 100 of this embodiment is completed.

As described above, according to the method of manufacturing the cover glass 100 of the present embodiment, the light-shielding film 105 is directly formed on the glass substrate 100. Therefore, the adhesion of the light-shielding film 105 is higher than the conventional configuration (that is, the structure in which the light-shielding film 105 is formed on the ultraviolet/infrared light reflection film). In addition, since the anti-reflection film 110 having a predetermined thickness is formed on the light-shielding film 105 (that is, the light-shielding film 105 is covered with the anti-reflection film 110), the reflectance of light in the light-shielding portion S is extremely low.

The above is the description of the first embodiment of the present invention, but the present invention is not limited to the configuration of the above-described embodiment, and various modifications can be made within the scope of the technical idea. For example, in the present embodiment, the glass substrate 101 is an infrared absorbing glass containing Cu ²⁺ (Cu ²⁺ containing fluorophosphate-based glass or phosphate glass containing Cu ^2+), and may be from the visible wavelength The area transparent material is selected, for example, borosilicate glass, crystal, polyester resin, polyolefin resin, acrylic resin, etc. can be used.

In the present embodiment, the case where the light-shielding film 105 is a Cr multilayer film formed by a sputtering method, a vacuum evaporation method, or the like has been described, but it is not limited to such a configuration. As the light-shielding film 105, in addition to Cr, metal materials such as Ta (tantalum), Mo (molybdenum), Ni (nickel), Ti (titanium), Cu (copper), and Al (aluminum) can be used. It should be noted that even when a metal material other than Cr is used, as long as it is in the present embodiment, the average reflectance Rm, the standard deviation σ, and the regression line from the reflectance R in the wavelength range of 420 to 680 nm From the viewpoint of the slope s, the thickness of the dielectric thin film of the uppermost layer of the light-shielding film 105 may be determined.

In addition, the case where the light-shielding film 105 of the present embodiment is a three-layer Cr multilayer film formed of a Cr ₂ O ₃ thin film 105a, a Cr thin film 105b, and a Cr ₂ O ₃ thin film 105c, but it is not limited to a three-layer structure, It may be composed of more layers, for example, a dielectric layer formed by alternately laminating Cr ₂ O ₃ thin film 105c into a plurality of extremely thin (eg 2 nm) Cr ₂ O ₃ thin films and a plurality of extremely thin (eg 1 nm) Cr thin films Wait. In addition, in this case, as long as the average reflectance Rm of the reflectance R in the wavelength range of 420 to 680 nm, the standard deviation σ, and the slope s of the regression line are evaluated, the best value of the light-shielding film 105 can be obtained The film thickness of each layer of the upper dielectric layer group can realize the function of suppressing the reflection of the incident light incident on the light-transmitting portion T and the function of suppressing the reflection of the incident light incident on the light-shielding portion S as in the present embodiment.

In addition, the case where the Cr ₂ O ₃ thin film 105c of the light-shielding film 105 of the present embodiment is a single-layer thin film formed while introducing oxygen is described, but it is not limited to such a configuration, and for example, the amount of lamination oxygen introduced may be different Of multiple CrOx thin films (x is any ratio from 0 to 10). In order to further improve the wavelength characteristics of the reflectance, a thin film into which nitrogen is introduced may be used, or a structure in which a plurality of CrOxNy thin films (an arbitrary ratio of x and y of 0 to 10) with different amounts of oxygen and nitrogen introduced may be laminated.

In the present embodiment, the cover glass 100 that seals the package 300 of the solid-state imaging element 200 has been described as an example. However, the present invention can also be applied to the removal of near infrared rays from the light incident on the solid-state imaging element 200. A near-infrared cut filter or an optical low-pass filter that removes light containing high spatial frequencies from the light incident on the solid-state imaging element 200. In addition, when applying to a near-infrared cut filter, the glass substrate 101 similar to this embodiment can be used, and its thickness is preferably in the range of 0.1 to 1.0 mm. In addition, when it is applied to an optical low-pass filter, it is sufficient to use a glass substrate 101 made of crystal or borosilicate glass, and the thickness is preferably in the range of 0.1 to 3.0 mm.

In addition, the case where the light-shielding film 105 and the anti-reflection film 110 of the present embodiment are formed on the incident surface 101a side of the glass substrate 101 has been described. However, there are many returned lights from the solid-state imaging element 200 and the package 300, and the glass substrate 101's When the reflected light at the exit surface 101b causes ghosting or reflected light spots, as shown in FIG. 5, an anti-reflection film 120 similar to the anti-reflection film 110 may be formed on the exit surface 101b side of the glass substrate 101. In addition, compared to the reflected light on the incident surface 101a side of the glass substrate 101, the reflected light at the exit surface 101b of the glass substrate 101 may cause ghosting and reflected light spots as shown in FIG. 6 A light-shielding film 107 and an anti-reflection film 120 are formed on the exit surface 101b side of the glass substrate 101. As shown in FIG. 7, the light-shielding film 105 and the anti-reflection film 110 may be formed on the incident surface 101 a side of the glass substrate 101, and the light-shielding film 107 and the anti-reflection film 120 may be formed on the emission surface 101 b side of the glass substrate 101. .

In addition, in the manufacturing method of the cover glass 100 of the present embodiment, one cover glass 100 is manufactured from one glass base material 101, but it is not limited to such a configuration, for example, a large-sized glass base material may be used, A plurality of cover glasses 100 are assembled on the glass substrate to manufacture. According to such a configuration, even the small cover glass 100 is easy to handle and can be manufactured with high productivity.

In addition, in the manufacturing method of the cover glass 100 of the present embodiment, a resist corresponding to the pattern of the light-shielding film 105 is formed by a resist coating/baking/exposure/resist development process (ie, photolithography) , But not necessarily limited to such a method. For example, instead of the resist coating/baking/exposure/resist development process, a resist corresponding to the pattern of the light-shielding film 105 may be formed through printing techniques such as screen printing.

(Second embodiment)

Fig. 8 is a cover glass according to a second embodiment of the present invention A longitudinal cross-sectional view of the structure of 100A. As shown in FIG. 8, the cover glass 100A of the present embodiment is different from the cover glass 100 according to the first embodiment of the present invention in that it includes an etching barrier layer 103 between the glass substrate 101 and the light-shielding film 105.

As described above, the light-shielding film 105 of the cover glass 100 according to the first embodiment of the present invention is patterned by photolithography. However, in the patterning process, when the Cr multilayer film is etched, depending on the etching conditions, it may cause The entrance surface 101a of the glass substrate 101 is etched and roughened. Therefore, in order to prevent this problem from happening, the cover glass 100A of the present embodiment includes an etching barrier layer 103 between the glass substrate 101 and the light-shielding film 105. The etching barrier layer 103 covers the entire incident surface 101a of the glass substrate 101. In another embodiment, the etch stop layer 103 covers the entirety of at least one of the incident surface 101a and the exit surface 101b of the glass substrate 101.

The etching stopper layer 103 of the present embodiment is a thin film of SiO ₂ having translucency, and is formed on the incident surface 101a of the glass substrate 101 by a sputtering method, a vacuum evaporation method, or the like, as described later. Note that film as an etching stopper layer 103, preferably at least in the visible wavelength range of light transmission rate (i.e., transparent) as a material, for example SiO ₂ can be used instead of Al ₂ O ₃ or ZrO _2. In addition, the film thickness of the etch stop layer 103 can be freely set within a range that functions as an etch stop, so as not to affect the performance of the anti-reflection film 110 formed on the cover glass 100A, in this embodiment, it is set to be approximately The optical film thickness of λ /2.

FIG. 9 is a flowchart showing a method of manufacturing cover glass 100A according to the present embodiment. Similar to FIG. 4, FIG. 9(a) is a flowchart showing the manufacturing process of the cover glass 100A, and FIG. 9(b) is corresponding to each manufacturing process Fig. 9(c) is an enlarged cross-sectional view of the cover glass 100A corresponding to each manufacturing process. It should be noted that, as in FIG. 4, for ease of understanding, in FIG. 9 (b ), each component is shaded, and in FIG. 9 (c ), each component is highlighted.

As shown in FIG. 9, the manufacturing method of cover glass 100A according to this embodiment has a SiO ₂ thin film multilayer film forming process between the glass substrate forming process and the Cr multilayer film forming process, which is different from the first embodiment. The method of manufacturing the cover glass 100 according to the method (that is, the method of manufacturing shown in FIG. 4) is different.

In the formation process of the SiO ₂ thin film, on the incident surface 101a of the glass substrate 101 obtained in the forming process of the glass substrate, a SiO ₂ thin film with an optical film thickness of approximately λ /2 is formed by a sputtering method, a vacuum evaporation method, or the like (Ie, etching barrier layer 103). It should be noted that in this embodiment, the reference wavelength λ is 520 nm and the refractive index of SiO ₂ is 1.45. As a design value, a SiO ₂ thin film with a physical film thickness of about 179 nm is formed. However, in the actual manufacturing process, ± There is a difference in the memory in the tolerance range of about 10%, forming a SiO ₂ film of 179 nm±10%.

Then, a Cr multilayer film is formed on the SiO ₂ thin film (ie, the etch stop layer 103) by the same process as shown in FIG. 4, and the light-shielding film 105 is patterned by etching (ie, a patterning process), and The anti-reflection film 110 is formed so as to cover the light-shielding film 105 and the opening of the light-shielding film 105.

It should be noted that if the glass substrate 101 is immersed in the Cr etching solution during the patterning process, as the etching progresses, the Cr multilayer film in the portion where no resist is formed elutes into the etching solution, but because In this embodiment, in An etching barrier layer 103 is formed on the lower side of the Cr multilayer film (that is, between the Cr multilayer film and the glass substrate 101), so that the etching is blocked so that the incident surface 101a of the glass substrate 101 is not etched by the etching solution. Therefore, in this embodiment, the incident surface 101a of the glass substrate 101 is not roughened, and the light incident on the incident surface 101a of the glass substrate 101 is not scattered but is introduced into the glass substrate 101, and from The exit surface 101b exits. In addition, according to the configuration of the present embodiment, since the etching can be reliably prevented by the etching barrier layer 103, the entire glass substrate 101 can be immersed in the etching liquid for a relatively long time, and the etching residue and edges of the Cr-free multilayer film can be formed整整的光影膜105。 105.

The above is the description of the second embodiment of the present invention, but like the first embodiment, the present invention is not limited to the configuration of the above-described embodiment, and various modifications can be made within the scope of the technical idea.

For example, the case where the optical film thickness of the etching barrier layer 103 of the present embodiment is approximately λ /2 has been described, but any film thickness may be applied as long as it functions as an etching barrier. However, in the case of forming the etching stopper layer 103, there is generally a manufacturing difference (error) of about ±10%. Therefore, from the viewpoint of compression manufacturing errors, it is preferable that the film thickness of the etching stopper layer 103 be as thin as possible. In addition, if the thickness of the etch stop layer 103 is thick, there is a concern that the film stress causes the glass substrate 101 to warp, causing damage to the glass substrate 101, and a defect rate in a subsequent process (for example, an anti-reflection film forming process) Rise. Therefore, from the viewpoint of relaxing the film stress, the thickness of the etching stopper layer 103 is preferably thin, and the physical thickness of the glass substrate 101 is preferably 0.3 to 200.0 ppm. More specifically, for example, it is preferable to form an etching stopper layer 103 with a physical film thickness of 0.3 to 20.0 nm with respect to a glass substrate 101 with a plate thickness of 0.1 to 1.0 mm, and more preferably to glass with a plate thickness of 0.1 to 0.3 mm. On the substrate 101, an etching stopper layer 103 with a physical film thickness of 1.0 to 10.0 nm (that is, 3.3 to 100.0 ppm) is formed. In addition, when the thickness of the etching stopper layer 103 is approximately λ /2 and is relatively thin, it is preferable to correspond to this, and the Al ₂ O ₃ thin film 110 a and the ZrO ₂ thin film 110 b as constituent elements of the anti-reflection film 110 are preferably used. And each thickness of the MgF ₂ thin film 110c is optimized. In this case, as in the cover glass 100 according to the first embodiment, as long as the anti-reflection film 110 is incorporated, the uppermost layer of the light-shielding film 105 (ie, The thickness of the Cr ₂ O ₃ thin film 105c of the layer that is in contact with the anti-reflection film 110 is optimized to have both the function of suppressing the reflection of incident light with a wavelength of 420-680 nm and the incidence The light-shielding portion S may have a function of reflecting incident light having a wavelength of 420 to 680 nm.

In addition, the case where the etching stop layer 103, the light-shielding film 105, and the anti-reflection film 110 of the present embodiment are formed on the incident surface 101a side of the glass substrate 101 has been described. When reflected light from the exit surface 101b of the glass substrate 101 causes ghosting or reflected light spots, as shown in FIG. 10, an anti-reflection film 120 similar to the anti-reflection film 110 may be formed on the glass substrate 101 The exit surface 101b side. In addition, compared to the reflected light on the incident surface 101a side of the glass substrate 101, when the reflected light on the exit surface 101b of the glass substrate 101 causes ghosting and reflected light spots, as shown in FIG. 11, On the exit surface 101b side of the glass substrate 101, an etching stopper 106, a light-shielding film 107, and an anti-reflection film 120 are formed. In addition, as shown in Figure 12, the glass substrate An etching barrier layer 103, a light-shielding film 105, and an anti-reflection film 110 are formed on the incident surface 101a side of 101, and an etching barrier layer 106, a light-shielding film 107, and an anti-reflection film 120 are formed on the exit surface 101b side of the glass substrate 101.

It should be noted that all points of the embodiments disclosed this time should be considered as examples and not limitative. The scope of the present invention is given not by the above description but by the claims, and is intended to include all modifications equivalent in meaning and scope to the claims.

1‧‧‧Solid photography equipment

100‧‧‧Protective glass

101‧‧‧Glass substrate

101a‧‧‧incidence surface

101b‧‧‧Ejection surface

105‧‧‧shading film

110‧‧‧Anti-reflection film

200‧‧‧Solid photographic element

300‧‧‧Packing

S‧‧‧Shade

T‧‧‧Transparent

Claims (17)

An optical element used in a photographic device incorporating a solid photographic element, comprising: a transparent substrate, having an incident surface on the front and back faces of a light incident toward the solid photographic element and the transmission of the light incident on the incident surface An exit surface exiting toward the solid-state imaging element; a light-shielding film is formed into a frame shape on at least one of the entrance surface and the exit surface by etching, and shields a part of the light; an etching barrier layer Formed between the light-shielding film and the transparent substrate as a barrier to the etching, the etching barrier layer covering the entire at least one of the incident surface and the exit surface; an anti-reflection film to cover the A light-shielding film and an opening portion of the light-shielding film; and a light-transmitting portion and a light-shielding portion, the light-transmitting portion suppresses the reflection of the light incident on the area of the opening portion of the light-shielding film while allowing the light to enter The light to the region of the opening of the light-shielding film is transmitted, and the light-shielding unit blocks the light incident to the region of the light-shielding film while suppressing the reflection of the light incident to the region of the light-shielding film. The optical element according to item 1 of the patent application range, wherein the light-shielding film is formed of a thin film containing at least Cr. The optical element as described in item 2 of the patent application range, wherein the light-shielding film includes: a first film formed of Cr, formed of Cr ₂ O ₃ , and formed between the first film and the transparent substrate A second film, and a third film formed of Cr ₂ O ₃ and formed between the first film and the anti-reflection film. The optical element as described in item 3 of the patent application range, wherein the third film is connected to the anti-reflection film, and the film thickness of the third film is 55 to 63 nm. The optical element according to item 1 of the patent application range, wherein the anti-reflection film is formed by sequentially stacking Al ₂ O ₃ , ZrO ₂ , and MgF ₂ . The optical element as described in item 2 of the patent application range, wherein the anti-reflection film is formed by sequentially stacking Al ₂ O ₃ , ZrO ₂ , and MgF ₂ . The optical element according to item 3 of the patent application range, wherein the anti-reflection film is formed by sequentially stacking Al ₂ O ₃ , ZrO ₂ , and MgF ₂ . The optical element as described in item 4 of the patent application range, wherein the anti-reflection film is formed by sequentially stacking Al ₂ O ₃ , ZrO ₂ , and MgF ₂ . The optical element according to any one of claims 1 to 8, wherein the area of the light-transmitting portion is larger than the area of the light-receiving surface of the solid-state imaging element. The optical element according to any one of items 1 to 8 of the patent application range, wherein the optical element is a cover glass installed in front of a package that houses the solid-state imaging element. The optical element according to any one of claims 1 to 8, wherein the transparent substrate is a near-infrared absorbing glass that absorbs light of a wavelength in the near-infrared region. The application of the optical element 11 patentable scope of the item, wherein the near infrared absorbing glass is a fluorophosphate-based glass or glass-containing phosphate-containing Cu ²⁺ Cu ²⁺ constituted. The optical element as described in item 1 of the patent application range, wherein the etching barrier layer is formed of a thin film of SiO ₂ , Al ₂ O _3, or ZrO ₂ . The optical element as defined in claim 1 item range, wherein, when referring to the wavelength of light is [lambda], the optical thickness of the etch stop layer is λ / 2. The optical element as defined in claim 13 item range, wherein, when referring to the wavelength of light is [lambda], the optical thickness of the etch stop layer is λ / 2. The optical element as described in item 1 of the patent application range, wherein the physical film thickness of the etching barrier layer is 0.3 to 200.0 ppm relative to the plate thickness of the transparent substrate. The optical element as described in item 1 of the patent application range, wherein the plate thickness of the transparent substrate is 0.1 to 1.0 mm, and the physical film thickness of the etching barrier layer is 0.3 to 20.0 nm.

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