JP7452354B2 - Optical member and its manufacturing method - Google Patents

Description

The present invention relates to an optical member and a method for manufacturing the same.

Conventionally, various optical members such as prisms and optical filters have been used in optical devices. In an optical device, stray light may occur due to unintended reflection of light within the housing. In order to prevent stray light from entering the optical member, the optical member may be provided with a light shielding film.

Patent Document 1 discloses an example of an optical filter member having a light shielding film. In this optical filter member, a light shielding film is formed in the peripheral area on the upper surface of the base. Metals and metal oxides are used for the light shielding film. The upper surface of the base and the light shielding film are covered with an optical multilayer film.

Japanese Patent Application Publication No. 2014-170182

However, in the optical filter member as described in Patent Document 1, there is a problem that not only the light shielding property of the light shielding film is high, but also the reflectance of the light shielding film is high. Therefore, the light shielding film reflects the incident light, and the light is further reflected within the casing of the optical device, which may cause stray light to occur. In recent years, as optical devices have become smaller and optical members have become closer together, the problem of stray light has become more prominent.

On the other hand, resins with excellent light-shielding properties are sometimes used for the light-shielding film. However, when applying a resin, it is difficult to sufficiently improve the positional accuracy compared to when forming a metal film or metal oxide film using a sputtering method, a photolithography method, or the like. Therefore, it is difficult to sufficiently increase productivity.

An object of the present invention is to provide an optical member that has excellent light shielding properties in a desired region, low reflectance, and high productivity, and a method for manufacturing the same.

The optical member according to the present invention includes a member main body, an optical film provided on the member main body,
, the optical film has a light-shielding film made of M _x O _y N _z which is an oxynitride, and an anti-reflection film laminated on the light-shielding film, and the light-shielding film is closer to the member body than the anti-reflection film. The light shielding film is located on the side, and is characterized by y>z.

It is preferable that M in M _x O _y N _z in the light shielding film is one of Ti, Cr, Ta, Zr, Si, and Al.

When x of M _x O _y N _z in the light shielding film is 1, it is preferable that y is 0.5 or more and 1.5 or less, and z is 0.05 or more and 0.3 or less.

It is preferable that the antireflection film is a first antireflection film, and further includes a second antireflection film located between the light shielding film and the member body.

A method for manufacturing the above-mentioned optical member, comprising the steps of directly or indirectly stacking an oxide film on the member body, and nitriding the oxide film to produce M _x O _y N which is an oxynitride. The method is characterized by comprising the steps of forming a light-shielding film made of _Z and laminating an anti-reflection film on the light-shielding film.

The oxide film is preferably made of any one of titanium oxide, chromium oxide, tantalum oxide, zirconium oxide, silicon oxide, and aluminum oxide.

The anti-reflective film is a first anti-reflective film, further comprising the step of laminating a second anti-reflective film on the member body, and in the step of laminating an oxide film, an oxide film is formed on the second anti-reflective film. It is preferable to laminate the membranes.

According to the present invention, it is possible to provide an optical member that has excellent light blocking properties in a desired region, low reflectance, and high productivity, and a method for manufacturing the same.

FIG. 1 is a schematic cross-sectional view of an optical member according to a first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing the vicinity of an optical film of the optical member according to the first embodiment of the present invention. FIG. 3 is a diagram showing the relationship between the transmittance and reflectance of an optical film and wavelength in the first embodiment of the present invention. It is a figure showing the result of the heat cycle test of the optical film in the 1st embodiment of the present invention. (a) to (d) are schematic cross-sectional views for explaining a method of manufacturing an optical member according to a second embodiment of the present invention. (a) to (c) are schematic cross-sectional views for explaining an example of the step of forming an optical film in the method for manufacturing an optical member according to the second embodiment of the present invention. (a) is a diagram showing the vicinity of the peak of Ti element in the XPS analysis results of the light shielding film in the first embodiment of the present invention, and (b) is a diagram showing the vicinity of the peak of O element. , (c) are diagrams showing the vicinity of the peak of N element.

Preferred embodiments will be described below. However, the following embodiments are merely illustrative, and the present invention is not limited to the following embodiments. Further, in each drawing, members having substantially the same function may be referred to by the same reference numerals.

(Optical member)
(First embodiment)
FIG. 1 is a schematic cross-sectional view of an optical member according to a first embodiment of the present invention. Optical member 1 is a beam splitter. Note that the beam splitter is just one example, and the optical member of the present invention may be a member other than the beam splitter.

As shown in FIG. 1, the optical member 1 includes a member main body 2 and an optical film 3. The member main body 2 includes a first prism 4A, a second prism 4B, and a light-transmitting member 4C. A first prism 4A and a second prism 4B are joined to a light-transmitting member 4C. The member main body 2 has a substantially rectangular parallelepiped shape. The member main body 2 has a top surface, a bottom surface, and a plurality of side surfaces. The plurality of side surfaces are connected to the top surface and the side surfaces. The plurality of side surfaces include a first side surface 2a, a second side surface 2b, a third side surface 2c, and a fourth side surface 2d. The first side surface 2a and the third side surface 2c face each other. The second side surface 2b and the fourth side surface 2d face each other.

FIG. 2 is a schematic cross-sectional view showing the vicinity of the optical film of the optical member according to the first embodiment of the present invention. The optical film 3 is provided on the first side surface 2a of the member main body 2. The optical film 3 includes a light shielding film 5 and a first antireflection film 6. A second antireflection film 8 is laminated on the member body 2, and a light shielding film 5 is laminated on the member body 2 with the second antireflection film 8 interposed therebetween. A first antireflection film 6 is laminated on the light shielding film 5.

In this embodiment, the light shielding film 5 is made of titanium oxynitride. Note that the material of the light-shielding film 5 is not limited to the above, and may be made of M _x O _y N _z , which is an oxynitride, and y>z. Note that the material of the light shielding film 5 is preferably made of metal oxynitride. M in M _x O _y N _z is preferably one of Ti, Cr, Ta, Zr, Si, and Al.

The first antireflection film 6 is made of a laminated film. Specifically, in the first antireflection film 6, a high refractive index film 6a, a low refractive index film 6b, and a high refractive index film 6c are laminated in this order. Note that the number of layers of high refractive index films and the number of layers of low refractive index films in the first antireflection film 6 are not particularly limited.

In this embodiment, the high refractive index film 6a and the high refractive index film 6c in the first antireflection film 6 are made of TiO ₂ . The low refractive index film 6b in the first antireflection film 6 is made of SiO ₂ . However, the materials for the high refractive index film and the low refractive index film are not limited to the above. For example, MgF ₂ or the like may be used as the low refractive index film. As the high refractive index film, for example, Ta ₂ O ₅ , ZrO ₂ or HfO ₂ or the like may be used.

Returning to FIG. 1, the first prism 4A and the second prism 4B have a triangular prism shape. On the other hand, the light-transmitting member 4C has a quadrangular prism shape. The first prism 4A, the second prism 4B, and the light-transmitting member 4C each have a top surface, a bottom surface, and a plurality of side surfaces. The top and bottom surfaces of the first prism 4A and the second prism 4B have a substantially right isosceles triangular shape. The top and bottom surfaces of the light-transmitting member 4C have a substantially parallelogram shape.

The first side surface 2a of the member main body 2 is constituted by the side surface of the second prism 4B and the side surface of the light-transmitting member 4C. The second side surface 2b is constituted by the side surface of the first prism 4A. The third side surface 2c is constituted by the side surface of the first prism 4A and the side surface of the light-transmitting member 4C. The fourth side surface 2d is constituted by the side surface of the second prism 4B. A second antireflection film 8 is provided on the first side surface 2a, the second side surface 2b, the third side surface 2c, and the fourth side surface 2d. The optical film 3 is indirectly provided on the member main body 2 via the second antireflection film 8. However, the second antireflection film 8 does not necessarily need to be provided.

Note that the second antireflection film 8 is made of a laminated film. Specifically, in the second antireflection film 8, a high refractive index film 8a, a low refractive index film 8b, a high refractive index film 8c, and a low refractive index film 8d are laminated in this order. The number of layers of high refractive index films and the number of layers of low refractive index films in the second antireflection film 8 are not particularly limited.

In this embodiment, the high refractive index film 8a and the high refractive index film 8c in the second antireflection film 8 are made of TiO ₂ . The low refractive index film 8b and the low refractive index film 8d in the second antireflection film 8 are made of SiO ₂ . However, the materials for the high refractive index film and the low refractive index film are not limited to the above. For example, MgF ₂ or the like may be used as the low refractive index film. As the high refractive index film, for example, Ta ₂ O ₅ , ZrO ₂ or HfO ₂ may be used.

A first transmittance adjusting film 9A is provided between the first prism 4A and the light-transmitting member 4C. Similarly, a second transmittance adjustment film 9B is provided between the second prism 4B and the light-transmitting member 4C. The first transmittance adjusting film 9A and the second transmittance adjusting film 9B transmit some light and reflect other light. In this embodiment, the first transmittance adjusting film 9A and the second transmittance adjusting film 9B are semi-light transmitting films and have a transmittance of 50%. However, the transmittance of the first transmittance adjusting film 9A and the second transmittance adjusting film 9B is not limited to 50%.

The optical member 1 of this embodiment is a beam splitter. The optical member 1 has an entrance section 1a, a first output section 1b, a second output section 1c, and a third output section 1d. The incidence section 1a is located on the first side surface 2a. Specifically, the incident portion 1a is located at the portion of the light-transmitting member 4C on the first side surface 2a. The first emission section 1b and the second emission section 1c are located on the third side surface 2c. Specifically, the first emission part 1b is located at the first prism 4A on the third side surface 2c. The second emission part 1c is located in the portion of the light-transmitting member 4C on the third side surface 2c. The third emission section 1d is located on the fourth side surface 2d.

Note that, as described above, the optical film 3 is provided on the first side surface 2a of the member main body 2. Specifically, the optical film 3 is provided continuously on the second prism 4B portion and the light-transmitting member 4C portion on the first side surface 2a. The optical film 3 is provided so as not to obstruct the incident light A.

A part of the incident light A that has entered from the incident section 1a is transmitted through the first transmittance adjustment film 9A, and is emitted from the first output section 1b as output light C1. The other part of the incident light A is reflected by the first transmittance adjusting film 9A and becomes reflected light B. A portion of the reflected light B is reflected by the second transmittance adjustment film 9B and is emitted from the second emitting portion 1c as emitted light C2. The other part of the reflected light B passes through the second transmittance adjustment film 9B and is emitted from the third emitting portion 1d as emitted light C3.

The characteristics of this embodiment are that the optical film 3 has a light shielding film 5 and a first antireflection film 6, the light shielding film 5 is composed of M _x O _y N _z , and y>z; The reason is that the light shielding film 5 is located closer to the member main body 2 than the first antireflection film 6. Since the optical film 3 has the light shielding film 5, the portion where the optical film 3 is provided has excellent light shielding properties. Furthermore, since the light-shielding film 5 is made of oxynitride, the reflectance can be made much lower than when the light-shielding film 5 is made of an oxide such as a metal oxide or a metal. In addition, since the light shielding film 5 is located closer to the member main body 2 than the first antireflection film 6, the reflectance of the optical film 3 as a whole can be further lowered. Therefore, it is possible to suppress the occurrence of stray light. Note that when the light shielding film 5 is made of metal, the incident light is reflected on the light shielding film 5. Further, when the light shielding film 5 is made of a metal oxide, it becomes difficult to obtain the effect of lowering the reflectance in the first antireflection film 6.

In this embodiment, the optical film 3 can be formed using a sputtering method, a vapor deposition method, or the like. Therefore, the accuracy of the forming position can be more easily improved than when forming a light shielding film made of resin. Therefore, the defective rate due to positional accuracy can be easily reduced. Therefore, productivity can be increased.

Details of the optical characteristics of the optical film 3 in this embodiment will be shown below. Specifically, the transmittance and reflectance of the optical film 3 are shown. Note that the reflectance shows examples when the incident angle is 12° and when the incident angle is 30°. Furthermore, the results of a heat cycle test are also shown. In the heat cycle test, 500 cycles were performed, each cycle consisting of increasing and decreasing the temperature by cooling to -55° and heating to 125°. The optical properties were measured and compared before the temperature was raised and lowered and after the temperature was raised and lowered for 500 cycles.

FIG. 3 is a diagram showing the relationship between the transmittance and reflectance of the optical film and the wavelength in the first embodiment. FIG. 4 is a diagram showing the results of a heat cycle test of the optical film in the first embodiment. Note that FIGS. 3 and 4 show examples of the optical film 3 used for light of approximately 1500 nm or more and 1650 nm or less.

As shown in FIG. 3, it can be seen that the transmittance of the optical film 3 is less than 1% from 1500 nm to 1650 nm. It can be seen that the reflectance of the optical film 3 is less than 1% in the range of 1500 nm to 1650 nm both when the incident angle is 12° and when the incident angle is 30°. Thus, it can be seen that the optical film 3 has excellent light shielding properties and has a low reflectance. Therefore, the optical member 1 of the first embodiment has excellent light shielding properties and low reflectance in the desired region, that is, the region where the optical film 3 is provided.

As shown in FIG. 4, it can be seen that there is almost no change in the transmittance and reflectance of the optical film 3 before and after repeatedly increasing and decreasing the temperature. In this way, in this embodiment, the reliability of the optical film 3 can also be improved.

The number of layers of the first antireflection film 6 is preferably one or more, more preferably three or more. In this case, the reflectance of the optical film 3 can be suitably lowered. The number of layers of the first antireflection film 6 is preferably nine layers or less, more preferably five layers or less. In this case, the film stress of the first antireflection film 6 can be suitably reduced, and the first antireflection film 6 is difficult to peel off.

The film closest to the light shielding film 5 of the first antireflection film 6 is preferably a high refractive index film. In this case, the difference in refractive index at the interface between the light shielding film 5 and the first antireflection film 6 can be reduced. Thereby, the light incident on the optical film 3 is difficult to be reflected at the interface between the first antireflection film 6 and the light shielding film 5. Further, it is preferable that the film of the second antireflection film 8 closest to the light shielding film 5 is a low refractive index film. In this case, the difference in refractive index becomes large at the interface between the light shielding film 5 and the second antireflection film 8, and light is more likely to be reflected at the interface between the light shielding film 5 and the second antireflection film 8. This makes it even more difficult for light to enter the member main body 2 in the portion where the light shielding film 5 is provided. Further, since the light shielding film 5 has a low transmittance, the light reflected at the interface between the light shielding film 5 and the second antireflection film 8 is substantially blocked by the light shielding film 5.

As optical devices become more compact, the problems of stray light become more prominent because the components are brought closer to each other. The optical member 1 of this embodiment can suppress the generation of stray light, and is therefore particularly suitable for use in small optical devices.

The optical member according to the present invention is not limited to a beam splitter, and may be, for example, a prism or a lens. The member main body of the optical member may be, for example, a prism, a lens, a glass substrate, or the like.

(Production method)
(Second embodiment)
Hereinafter, a method for manufacturing an optical member as a second embodiment of the present invention will be described. Note that the second embodiment is an example of a method for manufacturing the optical member 1 described above.

FIGS. 5(a) to 5(d) are schematic cross-sectional views for explaining a method for manufacturing an optical member according to a second embodiment of the present invention. 6(a) to 6(c) are schematic cross-sectional views for explaining an example of the step of forming an optical film in the method for manufacturing an optical member according to the second embodiment of the present invention.

As shown in FIGS. 5(a) to 5(c), a first prism base material 14A, a second prism base material 14B, and a light-transmitting member base material 14C are prepared. As shown in FIG. 5(a), the first prism base material 14A has a bonding surface 16a. The bonding surface 16a is a surface of the first prism base material 14A that is bonded to the light-transmitting member base material 14C. A first transmittance adjustment film 9A is formed on the bonding surface 16a of the first prism base material 14A. Further, a second anti-reflection film 8 is formed on the first prism base material 14A other than the bonding surface 16a.

The first transmittance adjusting film 9A can be formed by laminating appropriate metal films or dielectric films using, for example, a sputtering method or a vacuum evaporation method. The second antireflection film 8 can be formed by alternately stacking low refractive index films and high refractive index films using, for example, a sputtering method or a vacuum evaporation method. Note that the order in which the first transmittance adjustment film 9A and the second antireflection film 8 are formed is not particularly limited.

Similarly, as shown in FIG. 5(b), the second prism base material 14B has a bonding surface 16b. A second transmittance adjusting film 9B is formed on the bonding surface 16b of the second prism base material 14B. Further, a second anti-reflection film 8 is formed on a surface of the second prism base material 14B other than the bonding surface 16b. In this embodiment, the second prism base material 14B, the second transmittance adjustment film 9B, and the second antireflection film 8 are the first prism base material 14A shown in FIG. 5(a), The structure is similar to that of the first transmittance adjusting film 9A and the second antireflection film 8. In this case, by dividing the first prism base material 14A on which the first transmittance adjusting film 9A and the second antireflection film 8 are formed, the second transmittance adjusting film 9B and the second A second prism base material 14B on which the antireflection film 8 is formed may also be obtained.

As shown in FIG. 5(c), the light-transmitting member base material 14C has a bonding surface 16c and a bonding surface 16d. The bonding surface 16c is a surface of the light-transmitting member base material 14C that is bonded to the first prism base material 14A. The bonding surface 16d is a surface of the light-transmitting member base material 14C that is bonded to the second prism base material 14B. A second antireflection film 8 is formed on surfaces other than the bonding surface 16c and the bonding surface 16d of the base material 14C for a transparent member. Note that the first transmittance adjusting film 9A may be provided on the bonding surface 16c of the light-transmitting member base material 14C. The second transmittance adjusting film 9B may be provided on the bonding surface 16d of the light-transmitting member base material 14C.

Next, as shown in FIG. 5(d), the bonding surface 16a of the first prism base material 14A and the bonding surface 16c of the light-transmitting member base material 14C are bonded together. The bonding surface 16b of the second prism base material 14B and the bonding surface 16d of the light-transmitting member base material 14C are bonded together. Thereby, the main body base material 12 is obtained. An appropriate adhesive or the like may be used to join the first prism base material 14A and the second prism base material 14B to the light-transmitting member base material 14C. Note that the second antireflection film 8 may be formed after joining the first prism base material 14A, the second prism base material 14B, and the light-transmitting member base material 14C. However, the second antireflection film 8 does not necessarily need to be formed.

The main body base material 12 has a side surface 12a. The side surface 12a corresponds to the first side surface 2a of the member main body 2 shown in FIG. As shown in FIG. 6(a), a second antireflection film 8 is formed on the side surface 12a. The second antireflection film 8 can be formed by alternately stacking low refractive index films and high refractive index films using, for example, a sputtering method or a vacuum evaporation method.

Next, a metal oxide film 15 is formed on the second antireflection film 8 as an oxide film in the present invention. In this embodiment, the metal oxide film 15 is made of titanium oxide. However, the material of the oxide film in the present invention is not limited to the above. The oxide film may be made of, for example, any one of chromium oxide, tantalum oxide, zirconium oxide, silicon oxide, and aluminum oxide. The metal oxide film 15 can be formed using, for example, a sputtering method or a vacuum evaporation method. The same applies when the oxide film is formed of silicon oxide or the like.

Next, the metal oxide film 15 is nitrided. Thereby, a light shielding film 5 is obtained as shown in FIG. 6(b). In this embodiment, the light shielding film 5 is made of titanium oxynitride. However, as described above, the light shielding film 5 may be made of an oxynitride other than titanium oxynitride. Next, as shown in FIG. 6(c), a first antireflection film 6 is laminated on the light shielding film 5. The first antireflection film 6 can be formed, for example, by alternately stacking low refractive index films and high refractive index films using a sputtering method, a vacuum evaporation method, or the like. Next, a plurality of optical members 1 are obtained by cutting the main body base material 12.

Here, the present inventor discovered a problem that when oxidizing and nitriding a metal or the like at the same time, the optical properties of the light shielding film are not stable. This is because the optical characteristics vary greatly depending on the variation in the proportion of nitrogen element in the light shielding film. Furthermore, the present inventor found that when oxidizing and nitriding a metal or the like at the same time, it is not possible to stably satisfy y>z in M _x O _y N _z as an oxynitride. As a result, variations in the optical properties of the light-shielding film tend to increase. Therefore, the reflectance of the light shielding film may not be made sufficiently low, and as a result, it becomes difficult to suppress stray light. Furthermore, in order to lower the reflectance of the optical film as a whole, it is necessary to measure the optical properties such as the refractive index of the light shielding film and prepare a first antireflection film that matches the optical properties. In this way, it becomes difficult to increase productivity.

In contrast, in this embodiment, the metal oxide film 15 is nitrided after the metal oxide film 15 is formed. Thereby, in M _x O _y N _z as an oxynitride, y>z can be stably satisfied. In this case, even if the ratio of nitrogen element in the oxynitride varies, the change in optical properties will be small. Therefore, the reflectance of the light shielding film 5 can be stably lowered. Further, since the variation in the optical properties of the light shielding film 5 is small, there is no need to change the configuration of the first antireflection film 6 in accordance with the variation in the optical properties of the light shielding film 5. Therefore, productivity can be effectively increased.

The results of analysis by XPS (X-ray Photoelectron Spectroscopy) of the light shielding film 5 in the optical film 3 of the first embodiment, which was produced by the method of the second embodiment, will be shown below.

FIG. 7(a) is a diagram showing the vicinity of the peak of the Ti element in the XPS analysis results of the light shielding film in the first embodiment, and FIG. 7(b) is a diagram showing the vicinity of the peak of the O element. 7(c) is a diagram showing the vicinity of the peak of N element. As shown in FIGS. 7(a) to 7(c), it can be seen that the peak of nitrogen element (N element) is lower than the peak of titanium element (Ti element) and the peak of oxygen element (O element). Therefore, it can be seen that y>z in Ti _x O _y N _z .

When x of M _x O _y N _z in the light shielding film 5 is 1, y is preferably 0.5 or more and 1.5 or less, more preferably 0.8 or more and 1.3 or less. preferable. z is preferably 0.05 or more and 0.3 or less, more preferably 0.1 or more and 0.15 or less. In particular, when z is within the above range, even if there are variations in the proportion of nitrogen element in the composition of the light shielding film 5, variations in the optical properties in the optical film 3 can be further reduced, and optical The reflectance of the film 3 can be lowered even more reliably.

1... Optical member 1a... Incident part 1b to 1d... First to third output part 2... Member main body 2a to 2d... First to fourth side surface 3... Optical film 4A, 4B... First, second prism 4C...Transparent member 5...Light shielding film 6...First antireflection film 6a...High refractive index film 6b...Low refractive index film 6c...High refractive index film 8...Second antireflection film 8a...High refractive index film 8b ...Low refractive index film 8c...High refractive index film 8d...Low refractive index film 9A, 9B...First, second transmittance adjustment film 12...Main body material 12a...Side surfaces 14A, 14B...First, second Prism base material 14C... Transparent member base material 15... Metal oxide films 16a to 16d... Bonding surface

Claims (6)

The member body,
an optical film provided on the member main body;
Equipped with
The optical film has a light shielding film made of M _x O _y N _z which is an oxynitride, and an antireflection film laminated on the light shielding film,
The light shielding film is located closer to the member body than the antireflection film,
In the light shielding film, y>z ,
An optical member, wherein M in M _x O _y N _z in the light shielding film is any one of Ti, Cr, Ta, and Zr . The member body,
an optical film provided on the member main body;
Equipped with
M in which the optical film is an oxynitride _x O _y N _z and an antireflection film laminated on the light shielding film,
The light shielding film is located closer to the member body than the antireflection film,
In the light shielding film, y>z,
The anti-reflection film is a first anti-reflection film,
An optical member further comprising a second antireflection film located between the light shielding film and the member main body. 1 or 2, wherein when x of M _x O _y N _z in the light shielding film is 1, y is 0.5 or more and 1.5 or less, and z is 0.05 or more and 0.3 or less. 2. The optical member according to 2. A method for manufacturing the optical member according to any one of claims 1 to 3 , comprising:
Laminating an oxide film directly or indirectly on the member body;
forming the light shielding film made of _MxOyNz , which is an oxynitride _, by nitriding _the oxide film;
laminating the antireflection film on the light shielding film;
A method for manufacturing an optical member, comprising: 5. The method for manufacturing an optical member according to claim 4 , wherein the oxide film is made of any one of titanium oxide, chromium oxide, tantalum oxide, zirconium oxide, silicon oxide, and aluminum oxide. The anti-reflection film is a first anti-reflection film,
further comprising the step of laminating a second antireflection film on the member main body,
6. The method for manufacturing an optical member according to claim 4 , wherein in the step of laminating the oxide film, the oxide film is laminated on the second antireflection film.

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