JP7635626B2 - Device and manufacturing method thereof - Google Patents

Description

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

MEMS elements manufactured using MEMS (Micro Electro Mechanical Systems) technology, such as MEMS microphones, are known. MEMS elements using glass substrates are also known. MEMS elements are manufactured using a photolithography process.

In one example of a MEMS element, a MEMS structure is placed on the front surface of a glass substrate, and a glass hole is formed on the back surface of the glass substrate. When manufacturing such a MEMS element, the positional relationship between the MEMS structure and the glass hole is very important, as it affects the operating characteristics of the MEMS element.

To form the glass holes, a mask for forming the glass holes must be formed on the back surface of the glass substrate in accordance with the position of the MEMS structure. In this case, a non-transparent film that can withstand glass etching is used as the mask for forming the glass holes.

However, when patterning a non-transparent film, if the non-transparent film is formed on the back surface of the glass substrate, the entire surface is shielded from light, making it impossible to detect the alignment mark on the front surface. In this case, it is impossible to align the pattern on the front surface with the pattern on the back surface.

JP 2019-201263 A

The present invention provides an element that can improve operating characteristics and a method for manufacturing the same.

According to a first aspect of the present invention, a method for manufacturing an element is provided, which includes the steps of forming a first alignment mark made of a non-transparent material on the front surface of a substrate made of glass, forming a transparent film on the back surface of the substrate, performing alignment from the back surface of the substrate using the first alignment mark and forming a first resist pattern on the transparent film, etching the transparent film using the first resist pattern as a mask to form a second alignment mark, forming a first protective film made of a non-transparent material on the second alignment mark, performing alignment from the back surface of the substrate using the second alignment mark and the first protective film on the second alignment mark, forming a second resist pattern on the first protective film, and etching the first protective film using the second resist pattern as a mask.

According to a second aspect of the present invention, there is provided a method for manufacturing an element according to the first aspect, further comprising, after the step of etching the first protective film, a step of forming a structure on the front surface of the substrate, and a step of etching the substrate using the first protective film as a mask.

According to a third aspect of the present invention, there is provided a method for manufacturing an element according to the second aspect, further comprising a step of forming a second protective film made of a non-transparent material on the front surface of the substrate simultaneously with the first alignment mark, and the structure is formed on the second protective film.

According to a fourth aspect of the present invention, there is provided a method for manufacturing an element according to the second or third aspect, in which the structure is a MEMS structure.

According to a fifth aspect of the present invention, there is provided a method for manufacturing an element according to any one of the first to fourth aspects, in which the second alignment mark is positioned at a different position from the first alignment mark in a plan view.

According to a sixth aspect of the present invention, there is provided a method for manufacturing an element according to any one of the first to fifth aspects, in which the transparent film is made of ITO (indium tin oxide).

According to a seventh aspect of the present invention, there is provided a method for manufacturing an element according to any one of the first to sixth aspects, in which the first protective film is made of chromium (Cr) or an alloy containing chromium (Cr).

According to an eighth aspect of the present invention, there is provided an element comprising a substrate having a front surface and a back surface, an opening extending from the front surface to the back surface, and made of glass; a structure provided on the front surface so as to cover the opening; a first alignment mark provided on the front surface of the substrate and made of a non-transparent material; and a second alignment mark provided on the back surface of the substrate and made of a transparent material, wherein the second alignment mark is disposed at a different position from the first alignment mark in a plan view.

According to a ninth aspect of the present invention, there is provided an element according to the eighth aspect, further comprising a first protective film disposed on the second alignment mark and made of a non-transparent material.

According to a tenth aspect of the present invention, there is provided an element according to the eighth or ninth aspect, further comprising a second protective film provided between the substrate and the structure and made of a non-transparent material.

According to an eleventh aspect of the present invention, there is provided an element according to any one of the eighth to tenth aspects, in which the structure is a MEMS structure.

According to a twelfth aspect of the present invention, there is provided an element according to any one of the eighth to eleventh aspects, in which the second alignment mark is made of ITO (indium tin oxide).

According to a thirteenth aspect of the present invention, there is provided an element according to the ninth aspect, in which the first protective film is made of chromium (Cr) or an alloy containing chromium (Cr).

The present invention provides an element capable of improving operating characteristics and a method for manufacturing the same.

FIG. 1 is a cross-sectional view of a MEMS element according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the MEMS structure shown in FIG. 3A to 3C are cross-sectional views illustrating the manufacturing process of the MEMS element. 4A to 4C are cross-sectional views for explaining the manufacturing process of the MEMS element. 5A to 5C are cross-sectional views for explaining the manufacturing process of the MEMS element. 6A to 6C are cross-sectional views for explaining the manufacturing process of the MEMS element. 7A to 7C are cross-sectional views illustrating the manufacturing process of the MEMS element. 8A to 8C are cross-sectional views for explaining the manufacturing process of the MEMS element. 9A to 9C are cross-sectional views for explaining the manufacturing process of the MEMS element. 10A to 10C are cross-sectional views illustrating the manufacturing process of the MEMS element. 11A to 11C are cross-sectional views illustrating the manufacturing process of the MEMS element. 12A to 12C are cross-sectional views illustrating the manufacturing process of the MEMS element. 13A to 13C are cross-sectional views illustrating the manufacturing process of the MEMS element. 14A to 14C are cross-sectional views illustrating the manufacturing process of the MEMS element. 15A to 15C are cross-sectional views illustrating the manufacturing process of the MEMS element. 16A to 16C are cross-sectional views illustrating the manufacturing process of the MEMS element. 17A to 17C are cross-sectional views illustrating the manufacturing process of the MEMS element. 18A to 18C are cross-sectional views illustrating the manufacturing process of the MEMS element. 19A to 19C are cross-sectional views illustrating the manufacturing process of the MEMS element. 20A to 20C are cross-sectional views illustrating the manufacturing process of the MEMS element. 21A to 21C are cross-sectional views illustrating the manufacturing process of the MEMS element. 22A to 22C are cross-sectional views illustrating the manufacturing process of the MEMS element. 23A to 23C are cross-sectional views illustrating the manufacturing process of the MEMS element.

The following describes the embodiments with reference to the drawings. However, the drawings are schematic or conceptual, and the dimensions and ratios of each drawing are not necessarily the same as those in reality. Furthermore, even when the same parts are shown in different drawings, the dimensional relationships and ratios between the drawings may be different. In particular, the following embodiments are examples of devices and methods for embodying the technical concept of the present invention, and the shape, structure, arrangement, etc. of the components do not specify the technical concept of the present invention. In the following description, elements having the same function and configuration are given the same reference numerals, and duplicate descriptions will be omitted.

1 is a cross-sectional view of a MEMS element 1 according to an embodiment of the present invention. In this embodiment, the MEMS element 1 is a MEMS microphone.

The MEMS element 1 comprises a glass substrate 2, an alignment mark 3 on the front surface side, an alignment mark 4 on the back surface side, and a MEMS structure 5.

The glass substrate 2 has a front surface 2-1 and a back surface 2-2 arranged opposite each other. The glass substrate 2 has an element region AR1 in which the MEMS structure 5 is formed, and a peripheral region AR2 adjacent to the element region AR1.

The MEMS structure 5 is provided on the front surface 2-1 of the glass substrate 2 and in the element region AR1. The specific configuration of the MEMS structure 5 will be described later.

An opening (through hole) 2A that penetrates the glass substrate 2 is provided in the element region AR1 of the glass substrate 2. The opening 2A is disposed below the MEMS structure 5 and exposes a portion of the MEMS structure 5.

An alignment mark 3 is provided on the front surface 2-1 of the glass substrate 2 and in the peripheral area AR2. An alignment mark 4 is provided on the back surface 2-2 of the glass substrate 2 and in the peripheral area AR2.

One of the manufacturing processes for devices having multiple layers (including MEMS elements) is the photolithography process using a manufacturing device (specifically, an exposure device). Alignment marks are used to form multiple layers of the element using the manufacturing device, and are used by the manufacturing device to align the layers when forming them. The alignment marks have a predetermined shape (pattern) that can be recognized by the manufacturing device. In the photolithography process, an exposure device detects the alignment mark formed on the substrate, and the substrate and photomask are aligned using the alignment mark, and the resist is patterned using the photomask.

Alignment mark 4 is positioned at a different position from alignment mark 3 when viewed in a plan view. Plan view refers to the state when the object is viewed from the front surface of the glass substrate.

In FIG. 1, alignment mark 3 and alignment mark 4 are each shown simplified as a pattern of three squares. In reality, alignment mark 3 and alignment mark 4 have patterns whose positions and orientations can be recognized by a manufacturing device.

The alignment mark 4 includes a pattern that can be recognized by the manufacturing equipment from the back surface of the glass substrate 2. The alignment mark 3 includes a first pattern that can be recognized by the manufacturing equipment from the front surface of the glass substrate 2, and a second pattern that can be recognized by the manufacturing equipment from the back surface of the glass substrate 2 through the transparent glass substrate 2 and multiple transparent layers. In other words, the alignment mark 3 includes a first pattern that can be recognized from the front surface, and a second pattern that is a vertically inverted (or horizontally inverted) version of the first pattern.

This allows the manufacturing device to detect the alignment mark 3 by irradiating light from the back surface of the glass substrate 2. The manufacturing device can also use the alignment mark 3 to perform alignment and pattern a layer on the back surface of the glass substrate 2.

(Configuration of MEMS structure 5)
FIG. 2 is a cross-sectional view of the MEMS structure 5 shown in FIG.

An opening 2A is provided in the glass substrate 2, penetrating the glass substrate 2. The planar shape of the opening 2A is, for example, a circle.

A protective film 10 is provided on the glass substrate 2, surrounding the opening 2A. The protective film 10 is used to protect the MEMS structure 5 when the glass substrate 2 is wet-etched.

The MEMS structure 5 is positioned so as to cover the opening 2A formed in the glass substrate 2.

A membrane 20 is provided on the protective film 10 and the glass substrate 2 so as to cover the opening 2A. The membrane 20 is also called a diaphragm, and is a film that vibrates due to sound pressure. The planar shape of the membrane 20 is, for example, a circle. The size of the membrane 20 is larger than the size of the opening 2A. The membrane 20 is configured by sequentially stacking an insulating layer 20A, a conductive layer 20B, and an insulating layer 20C. The conductive layer 20B functions as an electrode (vibrating electrode) of the membrane 20. The conductive layer 20B is configured of a metal, for example, molybdenum (Mo) or an alloy containing molybdenum. The insulating layer 20A and the insulating layer 20C are configured of, for example, silicon nitride (SiN).

The membrane 20 has at least one through hole 21. The through hole 21 penetrates the membrane 20. The planar shape of the through hole 21 is, for example, a circle. If the opening 2A is completely blocked by the membrane 20, a pressure difference may occur between the upper and lower sides of the membrane 20. In order to reduce such a pressure difference, the membrane 20 has the through hole 21. Note that the membrane 20 may have multiple through holes.

A terminal 22 is provided at one end of the membrane 20. The terminal 22 is electrically connected to the conductive layer 20B. In other words, the terminal 22 is configured by drawing out the conductive layer 20B in an arbitrary direction.

A backplate 24 is provided above the membrane 20 via a cavity 23. The planar shape of the backplate 24 is, for example, a circle. The backplate 24 is configured by sequentially stacking a conductive layer 24A and an insulating layer 24B. The conductive layer 24A functions as an electrode (fixed electrode) of the backplate 24. The conductive layer 24A is configured of a metal, such as molybdenum (Mo) or an alloy containing molybdenum. The insulating layer 24B is configured of, for example, silicon nitride (SiN).

The aforementioned cavity 23 is provided between the membrane 20 and the back plate 24. The cavity 23 is surrounded by an insulating layer 24B.

The back plate 24 has a plurality of through holes (sound holes) 25. The through holes 25 penetrate the back plate 24. The planar shape of the through holes 25 is, for example, a circle. The plurality of through holes 25 are uniformly arranged over the entire surface of the back plate 24. The plurality of through holes 25 have the function of passing sound waves applied from the side of the back plate 24 opposite the membrane 20 to the cavity 23.

A terminal 26 is provided at one end of the back plate 24. The terminal 26 is electrically connected to the conductive layer 24A. That is, the terminal 26 is configured by drawing out the conductive layer 24A in an arbitrary direction. The terminal 26 is exposed from the insulating layer 24B.

When sound reaches the MEMS structure 5, the sound passes through the multiple through holes 25 in the back plate 24, and sound pressure is applied to the membrane 20. This causes the membrane 20 to vibrate, changing the distance between the vibrating electrode of the membrane 20 and the fixed electrode of the back plate 24. When the distance between the vibrating electrode and the fixed electrode changes, the electrostatic capacitance between the vibrating electrode and the fixed electrode changes. Therefore, by applying a DC voltage between the vibrating electrode and the fixed electrode and extracting the change in electrostatic capacitance as an electrical signal, the sound pressure can be detected as an electrical signal.

[2] Manufacturing Method of the MEMS Element 1 Next, a manufacturing method of the MEMS element 1 will be described with reference to the drawings.

As shown in FIG. 3, a glass substrate 2 is prepared. There are no particular limitations on the material of the glass substrate 2, and any type of glass can be used. For example, the glass substrate 2 can be made of alkali-free glass or alumino-silicate glass. The alkali-free glass is glass that contains, for example, 0.1% by mass or less of alkali components such as sodium and potassium.

The glass substrate 2 has a front surface 2-1 and a back surface 2-2. The front surface 2-1 is the surface on which the MEMS structure 5 is formed. The back surface 2-2 is the surface opposite the front surface 2-1, and is the surface on which the openings are formed. In the drawings explaining the manufacturing method, the glass substrate 2 is shown with the back surface 2-2 facing up.

Next, a protective film material is formed on the front surface 2-1 of the glass substrate 2, and this protective film material is patterned to form the protective film 10 and the alignment mark 3. The protective film 10 is formed in the element region AR1 where the MEMS structure 5 is formed, and the alignment mark 3 is formed in the peripheral region AR2 adjacent to the element region AR1.

The protective film 10 has the function of protecting the MEMS structure 5 when the glass substrate 2 is wet etched from the back surface 2-2. The protective film 10 is made of a material that is resistant (etching resistance) to the glass etching solution, such as chromium (Cr) or an alloy containing chromium (Cr). The alignment mark 3 is made of the same material as the protective film 10. The protective film 10 and the alignment mark 3 are made of a non-transparent material.

Next, as shown in FIG. 4, a transparent film 4A is formed on the back surface 2-2 of the glass substrate 2. The transparent film 4A is made of a material that can transmit the alignment light emitted from the manufacturing device. For example, ITO (indium tin oxide) is used as the transparent film 4A. Alternatively, a transparent insulating film (for example, silicon nitride (SiN)) may be used as the transparent film 4A.

Next, as shown in FIG. 5, a transparent resist layer 11A is formed on the transparent film 4A. The resist layer 11A is composed of, for example, a positive photoresist.

Next, as shown in FIG. 6, a manufacturing device (specifically, an exposure device) is used to detect the alignment mark 3 from the back surface 2-2 of the glass substrate 2. Specifically, a light source provided in the manufacturing device emits alignment light, and the reflected light is detected by a camera. Because the transparent film 4A provided on the back surface 2-2 of the glass substrate 2 is made of a transparent material, it is possible to detect the alignment mark 3 provided on the front surface 2-1 of the glass substrate 2. Then, using the detected alignment mark 3, the manufacturing device aligns the exposure photomask with the glass substrate 2 (alignment).

Next, as shown in FIG. 7, the resist layer 11A is exposed to light using a photomask (not shown) to partially expose the resist layer 11A. At this time, the exposure process is performed so that the exposure light is irradiated onto areas other than the pattern of the alignment mark 4 on the back surface side.

Next, as shown in FIG. 8, the resist layer 11A is developed and the exposed (solubilized) portions are removed. This forms a resist layer (resist pattern) 11 to which the pattern of the photomask is transferred. The resist pattern 11 covers the area where the alignment mark 4 is to be formed.

Next, as shown in FIG. 9, the transparent film 4A is wet-etched using the resist pattern 11 as a mask. Then, as shown in FIG. 10, the resist pattern 11 is removed.

As a result, alignment mark 4 is formed on the back surface 2-2 of the glass substrate 2. Alignment mark 4 is provided in the peripheral region AR2, and is positioned at a different position from alignment mark 3 in a plan view (when viewed from the front or back surface of the glass substrate). Furthermore, alignment mark 4 is formed in a pattern that can be recognized by the manufacturing device from the back surface. Part of alignment mark 3 includes a pattern that is a vertically inverted (or horizontally inverted) version of alignment mark 4.

Next, as shown in FIG. 11, a protective film 12 is formed on the back surface 2-2 of the glass substrate 2 and on the alignment mark 4. The protective film 12 is made of a material that is resistant to the glass etching solution, and is made of the same material as the protective film 10 and alignment mark 3 described above. The protective film 10 on the alignment mark 4 has projections and recesses corresponding to the pattern of the alignment mark 4. The projections and recesses of the protective film 10 essentially function as an alignment mark.

Next, as shown in FIG. 12, a transparent resist layer 13A is formed on the protective film 12. The resist layer 13A is composed of, for example, a positive photoresist.

Next, as shown in FIG. 13, the manufacturing device detects the alignment mark 4 from the back surface 2-2 side of the glass substrate 2. Specifically, the unevenness of the protective film 12 formed on the alignment mark 4 is recognized as an alignment mark by the manufacturing device. Then, the detected alignment mark 4 is used by the manufacturing device to align the exposure photomask with the glass substrate 2.

Next, as shown in FIG. 14, the resist layer 13A is exposed to light using a photomask (not shown) to partially expose the resist layer 13A. At this time, the exposure process is performed so that the exposure light is irradiated onto the opening area when etching the glass substrate 2.

Next, as shown in FIG. 15, the resist layer 13 is developed and the exposed (solubilized) parts are removed. This forms a resist layer (resist pattern) 13 to which the pattern of the photomask is transferred. The resist pattern 13 exposes the areas of the protective film 12 that will be openings when the glass substrate 2 is etched.

Next, as shown in FIG. 16, the protective film 12 is wet etched using the resist pattern 13 as a mask.

Next, as shown in FIG. 17, the resist pattern 13 is removed. This forms a protective film 12 having openings for etching the glass substrate 2. Here, the patterning of the protective film 12 is performed using an alignment mark 4 aligned with the alignment mark 3 on the front surface. This allows the openings in the protective film 12 to be formed in more accurate positions to match the structures on the front surface.

Next, as shown in FIG. 18, a MEMS structure 5 is formed on the front surface 2-1 of the glass substrate 2 in the element region AR1. The multiple layers that make up the MEMS structure 5 are formed using the alignment marks 3. The MEMS structure 5 can be formed using a known manufacturing method.

Next, as shown in FIG. 19, a protective layer 14 is formed on the front surface 2-1 of the glass substrate 2 so as to cover the MEMS structure 5. The protective layer 14 is made of, for example, liquid photoresist. Next, a protective layer 15 is formed on the protective layer 14. The protective layer 15 is made of a non-photosensitive resin that is resistant to hydrofluoric acid. By covering the MEMS structure 5 with the two protective layers 14 and 15, the MEMS structure 5 can be more reliably protected when the glass substrate 2 is wet etched.

Next, a resist layer 16 is formed on the protective film 12, and this resist layer 16 is patterned. Then, a resist layer (resist pattern) 16 having the same shape as the protective film 12 is formed. The resist pattern 16 is patterned using the alignment mark 4.

Next, as shown in FIG. 20, the glass substrate 2 is wet-etched using the protective film 12 and the resist pattern 16 as a mask. A solution containing hydrofluoric acid (hydrofluoric acid) is used as a glass etchant. As a result, an opening 2A is formed in the glass substrate 2. The opening 2A penetrates the glass substrate 2 and exposes the protective film 10. The planar shape of the opening 2A is, for example, a circle. The MEMS structure 5 is protected by the protective film 10.

Next, as shown in FIG. 21, the resist pattern 16 on the back surface 2-2 side of the glass substrate 2 is removed. Next, the protective film 12 provided on the back surface 2-2 of the glass substrate 2 is wet etched, and the protective film 10 exposed by the opening 2A is wet etched. As a result, a part of the sacrificial layer 17 is exposed from the opening provided in the membrane.

Next, as shown in FIG. 22, the protective layers 14 and 15 provided on the front surface 2-1 of the glass substrate 2 are removed.

Next, as shown in FIG. 23, the sacrificial layer 17 is wet etched to form a cavity 23 between the membrane and the back plate. In this manner, the MEMS element 1 is formed.

[3] Effects of the embodiment In this embodiment, a transparent film is used as the material for forming the alignment mark 4 on the back surface, so that the alignment mark 3 on the front surface can be detected by passing through the transparent film from the back surface side. The alignment mark 4 on the back surface is aligned with the alignment mark 3 on the front surface and patterned. A protective film 12 made of a non-transparent material is formed on the alignment mark 4. The manufacturing device can detect unevenness on the alignment mark 4. A mask (protective film 12) used when etching the glass substrate 2 from the back surface side is aligned with the alignment mark 4 on the back surface and patterned. Then, a MEMS structure 5 is formed on the front surface of the glass substrate 2, and an opening 2A is formed on the back surface of the glass substrate 2 using the protective film 12 as a mask.

Therefore, according to this embodiment, the opening 2A of the glass substrate 2 can be formed in a more accurate position in accordance with the MEMS structure 5. This allows the positional relationship (relative position) between the MEMS structure 5 and the opening 2A to be set more appropriately. This allows the operating characteristics of the MEMS element 1 to be improved.

In the above embodiment, a MEMS element (e.g., a MEMS microphone) is used as an example. However, the present invention is not limited to this, and the present embodiment can be applied to an element in which layers are formed on the front and back surfaces of the glass substrate 2.

The above embodiment can also be applied to transparent substrates other than glass.

In the above embodiment, a microphone (also called an acoustic transducer) has been described as an example of a MEMS element, but the present invention is not limited to this. The MEMS structure 5 according to this embodiment can be applied to various elements having a MEMS mechanism, such as an acceleration sensor, a gyro sensor, a tilt sensor, and a pressure sensor.

The present invention is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the gist of the invention. The embodiments may also be implemented in appropriate combination, in which case the combined effects can be obtained. Furthermore, the above-described embodiments include various inventions, and various inventions can be extracted by combinations selected from the multiple constituent elements disclosed. For example, if the problem can be solved and an effect can be obtained even if some constituent elements are deleted from all the constituent elements shown in the embodiments, the configuration from which these constituent elements are deleted can be extracted as an invention.

1...MEMS element, 2...glass substrate, 2-1...front surface, 2-2...back surface, 2A...opening, 3...alignment mark, 4...alignment mark, 4A...transparent film, 5...MEMS structure, 10...protective film, 11...resist pattern, 12...protective film, 13...resist pattern, 14...protective layer, 15...protective layer, 16...resist pattern, 17...sacrificial layer, 20...membrane, 20A...insulating layer, 20B...conductive layer, 20C...insulating layer, 21...through hole, 22...terminal, 23...cavity, 24...back plate, 24A...conductive layer, 24B...insulating layer, 25...through hole, 26...terminal, AR1...element region, AR2...peripheral region.

Claims (13)

forming a first alignment mark made of a non-transparent material on a front surface of a substrate made of glass;
forming a transparent film on a rear surface of the substrate;
performing alignment from the back surface of the substrate using the first alignment mark, and forming a first resist pattern on the transparent film;
forming a second alignment mark by etching the transparent film using the first resist pattern as a mask;
forming a first protective film made of a non-transparent material on the second alignment mark;
performing alignment from the back surface of the substrate using the second alignment mark and the first protective film on the second alignment mark, and forming a second resist pattern on the first protective film;
Etching the first protective film using the second resist pattern as a mask;
A method for manufacturing an element comprising the steps of: forming a structure on the front surface of the substrate after the step of etching the first protective film;
Etching the substrate using the first protective film as a mask;
The method for manufacturing an element according to claim 1 , further comprising: The method further includes forming a second protective film made of a non-transparent material on the front surface of the substrate simultaneously with the first alignment mark,
The method for manufacturing an element according to claim 2 , wherein the structure is formed on the second protective film. The method for manufacturing an element according to claim 2 or 3, wherein the structure is a MEMS structure. The method for manufacturing an element according to claim 1 , wherein the second alignment mark is arranged at a position different from that of the first alignment mark in a plan view. The method for manufacturing an element according to claim 1 , wherein the transparent film is made of ITO (indium tin oxide). The method for manufacturing an element according to claim 1 , wherein the first protective film is made of chromium (Cr) or an alloy containing chromium (Cr). A substrate having a front surface and a back surface, an opening extending from the front surface to the back surface, and made of glass;
A structure provided on the front surface so as to cover the opening;
a first alignment mark provided on the front surface of the substrate and made of a non-transparent material;
a second alignment mark provided on the rear surface of the substrate and made of a transparent material;
Equipped with
The element, wherein the second alignment mark is disposed at a position different from that of the first alignment mark in a plan view. The element according to claim 8 , further comprising a first protective film disposed on the second alignment mark and made of a non-transparent material. The element according to claim 8 or 9, further comprising a second protective film made of a non-transparent material and provided between the substrate and the structure. 11. A device according to any one of claims 8 to 10, wherein the structure is a MEMS structure. 12. The element according to claim 8, wherein the second alignment mark is made of ITO (indium tin oxide). The element according to claim 9 , wherein the first protective film is made of chromium (Cr) or an alloy containing chromium (Cr).