Micro-electro-mechanical (MEMS) Fabry-Perot Interferometer, Apparatus And Method For Manufacturing The Same

Abstract

A micro-electro-mechanical (MEMS) Fabry-Perot interferometer (100), comprising a transparent substrate (110); the first metal mirror structure (120) is located on the transparent substrate (110) and comprises a first metal layer (121) and first supporting layers (122-123); a second metal mirror structure (130), taking into account the transparent substrate (110), located on opposite sides of the first metal mirror structure (120), above the first metal mirror structure (120), the second metal mirror structure (130) comprising a second metal layer (131) and a second support layer (132-133), wherein the first support layer (122-123) and the second support layer (132-133) are parallel and comprise at least one of alumina or titanium dioxide; a Fabry-Perot cavity (140) located between the first support layer (122-123) and the second support layer (132-133), where the Fabry-Perot cavity (140) is formed by providing an insulating layer (141) on the first mirror structure (120) and at least partially removing the insulating layer (141) after providing the second mirror structure (130); an electrode (150-151) for providing an electrical contact to the first metal layer (121) and the second metal layer (131).

Description

[0001] Related Applications Citations

[0002] This application is a divisional application of the invention patent application with international application number PCT / FI2018 / 050520, international application date June 29, 2018, date of entry into the Chinese national phase December 27, 2019, Chinese national application number 201880043636.0, and invention name “Microelectromechanical (MEMS) Fabry-Perot interferometer, its manufacturing device and method”. Technical Field

[0003] The present application generally relates to a semiconductor device. Specifically, but not exclusively, the present application relates to a Fabry-Perot interferometer (FPI), a method for producing a Fabry-Perot interferometer (FPI), and an apparatus. More specifically, the present application relates to an electrically tunable Fabry-Perot interferometer (FPI) produced using micro-electromechanical (MEMS) technology. Background Art

[0004] This section illustrates useful background information without claiming that any of the techniques described herein represent prior art.

[0005] For example, Fabry-Perot interferometers (FPI) are often used as optical filters and spectral sensors.Fabry-Perot interferometers (FPI) are based on parallel mirrors, where a (Fabry-Perot) cavity is formed into the gap between the mirrors.

[0006] The passband wavelength of a Fabry-Perot interferometer (FPI) can be controlled by adjusting the distance between the mirrors (ie, the width of the gap). Tuning is usually done electronically.

[0007] Micro-electromechanical technology can be used to produce electrically tunable Fabry-Perot interferometers (FPI). Prior art structures of micro-electromechanical interferometers typically include silicon layers, wherein the conducting layer and the reflective layer are doped. The movable mirror is provided by removing a sacrificial silicon dioxide layer, which has initially been formed between the two mirror layers. The position of the movable mirror is controlled by applying voltages to electrodes included in the mirror structure.

[0008] Micro-electromechanical production techniques allow for mass production of interferometers.However, there are some disadvantages associated with prior art solutions for producing interferometers and interferometer components.

[0009] Known solutions utilize silvered mirrors within Fabry-Perot interferometers (FPIs). Furthermore, due to the removable release mirror, the cutting, packaging and transportation of the interferometers require special handling. The release mirror is sensitive to environmental stresses such as physical pressure, temperature or humidity changes, contamination, etc.

[0010] Since interferometers are relatively expensive to produce, it is not possible to use them in cost-critical mass-production applications.

[0011] Another disadvantage of the known solutions is that gaps cannot be provided for short distances between mirrors. This is because the wet etching process to provide narrow gaps is difficult. In addition, when producing Fabry-Perot interferometers (FPI) for visible and ultraviolet light, the optical layers need to be very thin. The thin films are usually discontinuous and include pinholes. Such films are easily damaged during wet etching. Therefore, the prior art is not suitable for producing electrically tunable Fabry-Perot interferometers (FPI) for short wavelengths such as the visible and ultraviolet range.

[0012] It is an object of the present invention to provide a method and an apparatus which alleviate the above mentioned problems of the prior art for example. Summary of the invention

[0013] Various aspects of examples of the invention are set out in the claims.

[0014] According to a first exemplary aspect of the present invention, there is provided a micro-electromechanical (MEMS) Fabry-Perot interferometer comprising:

[0015] Transparent substrate;

[0016] A first metal mirror structure, which is located on the transparent substrate and includes a first metal layer and a first support layer;

[0017] a second metal mirror structure, the second metal mirror structure being located on an opposite side of the first metal mirror structure with respect to the transparent substrate, above the first metal mirror structure, the second metal mirror structure comprising a second metal layer and a second supporting layer, wherein the first supporting layer and the second supporting layer are parallel and comprise at least one of aluminum oxide or titanium dioxide;

[0018] a Fabry-Perot cavity located between the first supporting layer and the second supporting layer, wherein the Fabry-Perot cavity is formed by providing an insulating layer on the first mirror structure and at least partially removing the insulating layer after providing the second mirror structure; and

[0019] Electrodes for providing electrical contact to the first metal layer and the second metal layer.

[0020] In an embodiment, the micro-electromechanical (MEMS) Fabry-Perot interferometer further comprises:

[0021] a first aluminum oxide layer disposed below the transparent substrate; and

[0022] A second aluminum oxide layer is disposed above the transparent substrate, wherein the second aluminum oxide layer is a part of the first supporting layer of the first metal mirror structure.

[0023] In an embodiment, the micro-electromechanical (MEMS) Fabry-Perot interferometer further comprises:

[0024] A lower insulating layer is disposed below the first aluminum oxide layer, wherein the lower insulating layer comprises tetraethyl orthosilicate.

[0025] In an embodiment, the first metal layer of the first metal mirror structure is arranged over the second aluminum oxide layer.

[0026] In an embodiment, the micro-electromechanical (MEMS) Fabry-Perot interferometer further comprises:

[0027] A third aluminum oxide layer is arranged above the first metal layer, wherein the third aluminum oxide layer is part of the first supporting layer of the first metal mirror structure.

[0028] In an embodiment, the micro-electromechanical (MEMS) Fabry-Perot interferometer further comprises:

[0029] A first electrical contact is arranged to be connected to the first metal layer (121), wherein a portion of the third aluminum oxide layer between the first electrical contact and the first metal layer is removed by wet etching.

[0030] In an embodiment, the micro-electromechanical (MEMS) Fabry-Perot interferometer further comprises:

[0031] An insulating layer is disposed over the third aluminum oxide layer, wherein the insulating layer comprises tetraethyl orthosilicate.

[0032] In an embodiment, the micro-electromechanical (MEMS) Fabry-Perot interferometer further comprises:

[0033] A fourth aluminum oxide layer is arranged above the insulating layer, wherein the fourth aluminum oxide layer is part of the second supporting layer of the second metal mirror structure.

[0034] In an embodiment, the second metal layer of the second metal mirror structure is arranged over the fourth aluminum oxide layer.

[0035] In an embodiment, the micro-electromechanical (MEMS) Fabry-Perot interferometer further comprises:

[0036] A fifth aluminum oxide layer is arranged above the second metal layer, wherein the fifth aluminum oxide layer is part of the second supporting layer of the second metal mirror structure.

[0037] In an embodiment, the micro-electromechanical (MEMS) Fabry-Perot interferometer further comprises:

[0038] A second electrical contact is arranged to be connected to the second metal layer, wherein a portion of the fifth aluminum oxide layer between the second electrical contact and the second metal layer is removed by wet etching.

[0039] In an embodiment, the second metal mirror structure comprises a through hole for removing at least a portion of the insulating layer to provide a tunable Fabry-Perot cavity between the first metal mirror structure and the second metal mirror structure.

[0040] In an embodiment, the transparent substrate includes fused silica glass or fused quartz glass; the aluminum oxide includes Al2O3; and the titanium dioxide includes TiO2.

[0041] In an embodiment, the at least one layer comprises an atomic layer deposition (ALD) grown aluminum oxide layer or a plasma enhanced chemical vapor deposition (PECVD) layer.

[0042] According to a second exemplary aspect of the present invention, there is provided a semiconductor device including the Fabry-Perot interferometer of the first aspect.

[0043] According to a third exemplary aspect of the present invention, there is provided a method for manufacturing a micro-electromechanical (MEMS) Fabry-Perot interferometer, the method comprising:

[0044] providing a transparent substrate;

[0045] Depositing a first metal mirror structure on a transparent substrate, the first metal mirror structure comprising a first metal layer and a first support layer;

[0046] considering the transparent substrate, depositing a second metal mirror structure over the first metal mirror structure on an opposite side of the first metal mirror structure, the second metal mirror structure comprising a second metal layer and a second supporting layer, wherein the first supporting layer and the second supporting layer are parallel and comprise at least one of aluminum oxide or titanium dioxide;

[0047] forming a Fabry-Perot cavity between the first supporting layer and the second supporting layer, whereby the cavity is formed by providing an insulating layer on the first metallic mirror structure and at least partially removing the insulating layer after providing the second metallic mirror structure; and

[0048] Electrodes are formed to provide electrical contact with the first metal layer and the second metal layer.

[0049] Different non-binding example aspects and embodiments of the present invention have been described above. The preceding embodiments are only used to explain selected aspects or steps that can be utilized in the implementation of the present invention. Some embodiments may be presented with reference only to certain exemplary aspects of the present invention. It should be appreciated that the corresponding embodiments may also be applied to other example aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] For a more complete understanding of example embodiments of the present invention, reference is now made to the following description taken in conjunction with the accompanying drawings, in which

[0051] Figure 1A schematic diagram of a micro-electromechanical system (MEMS) Fabry-Perot interferometer according to an embodiment of the present invention is illustrated;

[0052] Figure 2 Another schematic diagram of a micro-electromechanical system (MEMS) Fabry-Perot interferometer according to an embodiment of the present invention is illustrated;

[0053] Figure 3 illustrates exemplary production process stages of an electrically tunable Fabry-Perot interferometer (FPI) according to an embodiment of the present invention;

[0054] Figure 4 A flowchart illustrating a method according to an embodiment of the present invention; and

[0055] Figure 5 Another schematic diagram of a device including a micro-electromechanical system (MEMS) Fabry-Perot interferometer according to an embodiment of the present invention is illustrated. DETAILED DESCRIPTION

[0056] In an embodiment, a micro-electromechanical (MEMS) Fabry-Perot interferometer is disclosed. For example, the micro-electromechanical (MEMS) Fabry-Perot interferometer technology can also be used in an integrated platform with a multi-chip module technology with hybrid integrated active circuits.

[0057] Micro-electromechanical (MEMS) Fabry-Perot interferometer technology can be fabricated to any transparent substrate suitable for thin film processing in a clean room. Fused silica or quartz are commonly used for MEMS applications due to their excellent properties.

[0058] Fused quartz and fused silica are amorphous forms of quartz. Fused quartz is made by purifying and melting natural crystalline quartz (usually natural quartz sand). Fused quartz is a purer version of fused quartz, which is made from various silicon gases. Silica, chemically known as SiO2, is "pure" glass. All other commercial glasses are SiO2 with other dopants added to lower the melting temperature and modify the optical, thermal and mechanical characteristics.

[0059] A transparent substrate of fused quartz or fused silica has many advantages. This substrate has an extremely low coefficient of expansion, making it more impact resistant than any other refractory material. It has better transmission characteristics than any standard glass: 220 nanometers to 3 microns for standard semiconductor grade fused quartz, and 175 nanometers to 3 microns for many types of fused silica. It has the highest temperature characteristics of any glass. It can withstand temperatures of 900°C to 1100°C continuously, depending on the size and shape of the part, and can be used at temperatures up to 1400°C for short periods of time. It has a very low dielectric constant and has the lowest loss tangent of almost all known materials. It has a very low thermal conductivity and can be melted, bent, fused, stretched, welded into tube and rod form, ground and polished. It is harder than most glasses, can be made into any shape and relatively large sizes, has excellent resistance to non-fluorinated acids, solvents and plasmas, and is excellent for containing many high purity chemicals, but is still less expensive than sapphire for large parts.

[0060] By referring to the accompanying drawings Figures 1 to 5 The present invention and its possible advantages can be understood.In this document, the same reference numerals represent the same components or steps.

[0061] Figure 1 A schematic diagram of a micro-electromechanical (MEMS) Fabry-Perot interferometer 100 according to an embodiment of the present invention is illustrated.

[0062] The semiconductor device may include a micro-electromechanical (MEMS) Fabry-Perot interferometer 100 and other elements such as a die (not shown) that may be coupled on top of or below the micro-electromechanical (MEMS) Fabry-Perot interferometer 100. Further, a circuit board (not shown) may be coupled on top of or below the micro-electromechanical (MEMS) Fabry-Perot interferometer 100. Solder balls may be used for coupling.

[0063] The semiconductor device may further include an integrated passive device (IPD), which in some implementations may include a capacitor (e.g., a decoupling capacitor), a resistor, or an inductor. For example, the integrated passive device (IPD) may be arranged on a first surface (e.g., a top surface) or a second surface of the semiconductor device.

[0064] The micro-electromechanical (MEMS) Fabry-Perot interferometer 100 includes a transparent substrate 110, a first metal mirror structure 120, a second metal mirror structure 130, a Fabry-Perot cavity 140, and electrodes 150-151.

[0065] The first metal mirror structure 120 is disposed on the transparent substrate 110 and includes a first metal layer 121 and first support layers 122 - 123 .

[0066] Considering the transparent substrate 110 ( Figure 1 The second metal mirror structure 130 is arranged on the opposite side of the first metal mirror structure 120, and above the first metal mirror structure 120 ( Figure 1 ), the second metal mirror structure 130 includes a second metal layer 131 and second supporting layers 132-133, wherein the first supporting layers 122-123 and the second supporting layers 132-133 are substantially parallel and include at least one of aluminum oxide or titanium dioxide.

[0067] A Fabry-Perot cavity 140 is generated between the first supporting layers 122-123 and the second supporting layers 132-133, whereby the Fabry-Perot cavity 140 is formed by providing an insulating layer 141 on the first mirror structure 120 and at least partially removing the insulating layer 141 after providing the second mirror structure 130. By forming such a cavity 140, the second metallic mirror structure 130 is movable towards the first metallic mirror structure 120 by electrostatic actuation provided by the drive electrodes.

[0068] At least two electrodes 150 - 151 are arranged for providing electrical contact with the first metal layer 121 and the second metal layer 131 .

[0069] The first aluminum oxide layer 111 may be arranged below the transparent substrate 110 , and the second aluminum oxide layer 122 is arranged above the transparent substrate 110 , wherein the second aluminum oxide layer 122 is part of the first supporting layer 122 - 123 of the first metal mirror structure 120 .

[0070] A lower insulating layer 112 may be disposed under the first aluminum oxide layer 111 , wherein the lower insulating layer 112 includes tetraethyl orthosilicate (TEOS).

[0071] In an embodiment, the at least one insulating layer 112 , 141 may include silicon dioxide, for example made of tetraethyl orthosilicate (TEOS).

[0072] The first metal layer 121 of the first metal mirror structure 120 may be disposed over the second aluminum oxide layer 122 .

[0073] The third aluminum oxide layer 123 may be arranged over the first metal layer 121 , wherein the third aluminum oxide layer 123 is part of the first supporting layer 122 - 123 of the first metal mirror structure 120 .

[0074] The first electrical contact 150 may be arranged in connection with the first metal layer 121, wherein a portion of the third aluminum oxide layer 123 between the first electrical contact 150 and the first metal layer 121 is removed, for example, by wet etching. For example, dry etching may also be used when the selectivity is sufficient.

[0075] An insulating layer 141 may be disposed over the third aluminum oxide layer 123 , wherein the insulating layer 141 includes tetraethyl orthosilicate (TEOS).

[0076] A fourth aluminum oxide layer 132 may be arranged over the insulating layer 140 , wherein the fourth aluminum oxide layer 132 is part of the second supporting layer 132 - 133 of the second metal mirror structure 130 .

[0077] The second metal layer 131 of the second metal mirror structure 130 may be disposed over the fourth aluminum oxide layer 132 .

[0078] A fifth aluminum oxide layer 133 may be arranged over the second metal layer 131 , wherein the fifth aluminum oxide layer 133 is part of the second supporting layer 132 - 133 of the second metal mirror structure 130 .

[0079] The second electrical contact 151 may be arranged to be connected to the second metal layer 131 , wherein a portion of the fifth aluminum oxide layer 133 between the second electrical contact 151 and the second metal layer 131 is removed, for example by wet etching.

[0080] The second metal mirror structure 130 includes a through hole 134 for removing at least a portion of the insulating layer 141 to provide a Fabry-Perot cavity 140 between the first metal mirror structure 120 and the second metal mirror structure 130 .

[0081] In an embodiment, the Fabry-Perot cavity 140 is processed by removing the sacrificial oxide layer (a portion of the insulating layer 141) with HF vapor. Hydrofluoric acid (HF) is an ideal etchant for the type of silicon oxide used in micromachining because it can provide a fast etch rate and has a high selectivity to silicon. HF etching can be used to remove sacrificial oxide layers in MEMS manufacturing.

[0082] In an embodiment, the transparent substrate 110 includes, for example, fused quartz glass or fused silica glass, the aluminum oxide includes Al 2 O 3 , and the titanium dioxide includes TiO 2 .

[0083] At least one of the support layers 122 - 123 , 132 - 133 comprises an Al 2 O 3 or TiO 2 coated Fabry-Perot interferometer (FPI) mirror.

[0084] For example, ALD (atomic layer deposition) can be used to deposit the Al2O3 coating.

[0085] Al 2 O 3 may also be used as a protective layer for the metal layers 121 , 131 in the manufacturing process, for example, to resist wet etching.

[0086] In an embodiment, the first metal layer 121 and the second metal layer 131 may be patterned into certain shapes and / or regions, and such shapes / regions may form electrostatic actuation of at least one of the mirror structures 120 , 130 .

[0087] In an embodiment, the first metal mirror structure 120 comprises at least one groove 124 to divide the first metal layer 121 into several areas where actuation / driving electrodes may be formed. By connecting such electrodes to certain DC or AC signals, the second mirror structure 130 may be pulled towards the first mirror structure 120 .

[0088] In an embodiment, the mirror function is provided by the metal layers 121, 131. Further, it is an object to provide a suspended metal mirror structure 130 which, when combined with the bottom metal layer 121 and the associated metal mirror structure 120, forms a tunable Fabry-Perot interferometer 100. The aluminum oxide layer may be arranged to support one or more metal layers of one or more such structures.

[0089] In embodiments, first metal layer 121 may be etched into certain shapes and / or regions, and grooves 124 may be formed.

[0090] In embodiments, the first and second layers 131 may be etched into certain shapes and / or a plurality of regions, and grooves and / or through holes 134 may be formed.

[0091] Figure 2 Another schematic diagram of a micro-electromechanical (MEMS) Fabry-Perot interferometer 100 according to an embodiment of the present invention is illustrated.

[0092] In an embodiment, the micro-electromechanical (MEMS) Fabry-Perot interferometer 100 further includes electrical control of at least one of the metal mirror structures 120, 130. At least one of the metal mirror structures 120, 130 can be used as a beam structure (e.g., the second metal mirror structure 130), both ends of which are fixed to the fixed element of the micro-electromechanical (MEMS) Fabry-Perot interferometer 100.

[0093] In an embodiment, the micro-electromechanical (MEMS) Fabry-Perot interferometer 100 may further include at least one lower driving electrode 210, which is disposed below the beam structure (e.g., the second metal mirror structure 130); and at least one upper driving electrode 211, which is disposed on the lower surface of the beam structure (e.g., the second metal mirror structure 130) facing the substrate 110. Therefore, when a potential difference is arranged between the upper driving electrode 211 and the lower driving electrode 210, the beam structure (e.g., the second metal mirror structure 130) is attracted to the substrate 110 by electrostatic attraction, so that the distance between the metal mirror structures 120 and 130 is changed, and the characteristics of the micro-electromechanical (MEMS) Fabry-Perot interferometer 100 are adjusted based on the control signals for the electrodes 210 and 211.

[0094] In an embodiment, the driving electrodes 210 , 211 may be integrated with the metal layers 121 , 131 of the metal mirror structures 120 , 130 , respectively, to provide a bias voltage for the potential difference.

[0095] Furthermore, a Fabry-Perot cavity 140 (air gap) exists between the metal mirror structures 120 , 130 and between the electrodes 210 , 211 .

[0096] In an embodiment, when a bias voltage (on the drive electrode or the metal layer) is applied, at least one electrode may be thermally expanded and displaced in the direction of the cavity 140 .

[0097] In an embodiment, when a bias voltage is applied, the second bias electrode 131, 211 may be positively charged, resulting in the accumulation of positive (+) charges, and the first bias electrode 121, 210 may be negatively charged, resulting in the accumulation of (-) charges. At the same time, the charge on the cavity 140 may be maintained at 0, regardless of the application of the bias voltage. However, in reality, charge accumulation often occurs on the cavity 140. Therefore, the charge detected on the insulator in 140 is not always 0.

[0098] In an embodiment, the metal mirror structures 120, 130 may be movable relative to each other in alternative ways. For example, the bottom metal layer 121 of the metal mirror structure 120 may be patterned (grooves 124) to form an electrode region (the portion between the grooves 124), which may be used together with the patterned upper mirror electrode 131 region for electrostatic actuation of the upper mirror structure 130 in DC or AC mode.

[0099] Figure 3 Shown are exemplary production process stages of an electrically tunable Fabry-Perot interferometer (FPI) according to an embodiment of the present invention.

[0100] In stage 310, a transparent substrate 110 (such as a quartz substrate) is provided, and the upper and lower surfaces of the transparent substrate 110 are coated with aluminum oxide (such as Al2O3) to provide a first aluminum oxide layer 111 arranged below the transparent substrate 110 and a second aluminum oxide layer 122 arranged above the transparent substrate 110.

[0101] The thickness of the layers 111, 122 is typically one quarter or half of the operating wavelength of the radiation within the material of the layer of interest. In this case, the thickness of the layers 111, 122 may be, for example, 20 nm. For example, these layers 111, 122 may be deposited on the substrate 110 by an ALD (atomic layer deposition) process. The temperature of the ALD process may be, for example, 100-300° C. However, since an insulating polymer layer (for the FPI cavity) has not yet been provided at this stage, alternative processes using higher temperatures may also be used.

[0102] In phase 320, a lower insulating layer 112 is disposed below the first aluminum oxide layer 111, wherein the lower insulating layer 112 includes tetraethyl orthosilicate (TEOS). For example, the lower insulating layer 112 can be deposited using ALD. The thickness of the lower insulating layer 112 can be, for example, 50 nm. Further, a first metal layer 121 is disposed on top of the second aluminum oxide layer 122. The first metal layer 121 can include, for example, Ag (silver). For example, the first metal layer 121 can be formed by sputtering or evaporation using a suitable metal such as Ag. The first metal layer 121 forms an electrode of the mirror of the FPI 100. The first metal layer 121 can be patterned and wet etched to remove metal from a desired location 321 outside the pattern. For example, the first metal layer 121 can be etched into certain shapes and / or multiple regions, and a groove 124 can be formed.

[0103] In phase 330, a third aluminum oxide layer 123 is arranged above the first metal layer 121, wherein the third aluminum oxide layer 123 is part of the first supporting layer 122-123 of the first metal mirror structure 120. For example, the layer 123 can be deposited by an ALD (atomic layer deposition) process. For example, the thickness of the layer 123 can be 20 nm.

[0104] An insulating layer 331 is disposed over the third aluminum oxide layer 123, wherein the insulating layer 331 includes tetraethyl orthosilicate (TEOS). For example, the insulating layer 331 may be deposited using ALD. The thickness of the insulating layer 331 may be, for example, 50 nm.

[0105] Furthermore, the first electrical contact 150 is arranged to be connected to the first metal layer 121 , wherein a portion of the third aluminum oxide layer 123 (and the insulating layer 331 ) between the first electrical contact 150 and the first metal layer 121 is removed, for example, by wet etching.

[0106] In phase 340, an insulating layer 141 is arranged over the third aluminum oxide layer 123 (and the insulating layer 331), wherein the insulating layer 141 comprises, for example, tetraethyl orthosilicate (TEOS). For example, the insulating layer 141 may be deposited by an ALD (atomic layer deposition) process. For example, the thickness of the layer 141 may be 1450 nm.

[0107] Furthermore, the insulating layer 141 may be etched over the first electrical contact 150 using oxide etching (eg, STSAOE (Advanced Oxide Etching)).

[0108] In phase 350, a fourth aluminum oxide layer 132 is arranged over the insulating layer 141. For example, the fourth aluminum oxide layer 132 may be deposited by an ALD (atomic layer deposition) process. For example, the thickness of the layer 132 may be 70 nm.

[0109] Furthermore, the second metal layer 131 is arranged over the fourth aluminum oxide layer 132 and the fifth aluminum oxide layer 133 is arranged over the second metal layer 131 , wherein the fourth aluminum oxide layer 132 and the fifth aluminum oxide layer 133 are part of the second supporting layer 132 - 133 of the second metal mirror structure 130 .

[0110] For example, the second metal layer 131 may include Ag (silver). For example, the second metal layer 131 may be formed by sputtering or evaporation using a suitable metal such as Ag. The second metal layer 131 forms an electrode of a mirror of the FPI 100. The second metal layer 131 may be patterned and wet etched to remove metal from a desired location outside the pattern.

[0111] For example, the fourth aluminum oxide layer and the fifth aluminum oxide layer 132-133 can be deposited by an ALD (atomic layer deposition) process. For example, the thickness of each layer 132, 133 can be 70nm. Another insulating layer 351 can be arranged above the fifth aluminum oxide layer 133, wherein the other insulating layer, for example, includes tetraethyl orthosilicate (TEOS). For example, the other insulating layer 351 can be deposited by an ALD (atomic layer deposition) process. For example, the thickness of the other insulating layer 351 can be 50nm.

[0112] Furthermore, a second electrical contact 151 is arranged in connection with the second metal layer 131 , wherein a portion of the fifth aluminum oxide layer 133 (and the further insulating layer 351 ) between the second electrical contact 151 and the second metal layer 131 is removed, for example by wet etching.

[0113] For example, the second electrical contact 151 may be coated with aluminum with a thickness of 500 nm.

[0114] In phase 360, the second metal mirror structure 130 is processed to provide a through hole 134 for removing at least a portion of the insulating layer 141 to provide a Fabry-Perot cavity 140 between the first metal mirror structure 120 and the second metal mirror structure 130. Patterning and etching can be used to provide through holes 134 in the second metal mirror structure 130. These holes are used to remove a portion of the insulating layer 141. Further, the insulating layer 141 and the second supporting layers 132-133 can be etched using oxide etching (e.g., STS AOE (Advanced Oxide Etch) above the first electrical contact 150). Plasma etching can and is used to process the through hole 134 leading to the second metal mirror structure 130.

[0115] Furthermore, backside photolithography and wet etching are also performed, and the front side is protected by a photoresist (PR). A portion of the lower insulating layer 112 is removed, and a metal layer element 361 (e.g., aluminum) is arranged below the lower insulating layer 112. By removing a portion of the lower insulating layer 112, a hole is provided. For example, the hole can be used to pass light to the FPI 100.

[0116] In an embodiment, for example, deposition of at least one layer may be utilized using a PECVD silane process / oxidation.

[0117] In an embodiment, the at least one barrier layer may be formed as a metal layer element extending on a surface of the at least one metal layer.

[0118] The barrier layer may include low pressure chemical vapor deposition nitride (LPCVD SiN) or plasma enhanced chemical vapor deposition nitride (PECVD SiN).

[0119] At least one insulating layer of the semiconductor device may include a plasma enhanced chemical vapor deposition (PECVD) layer, such as tetraethyl orthosilicate (TEOS).

[0120] Figure 4 A flow chart of a method according to an embodiment of the present invention is shown.

[0121] A method for fabricating a microelectromechanical (MEMS) Fabry-Perot interferometer begins at step 410 .

[0122] In step 420, a transparent substrate is provided. This step may include, for example, bringing the substrate into a reaction space of a typical reactor tool (eg, a tool suitable for performing an ALD type process).

[0123] In step 430 , a first metal mirror structure is deposited on a transparent substrate, the first metal mirror structure comprising a first metal layer and a first support layer.

[0124] In step 440, considering the transparent substrate, a second metal mirror structure is deposited over the first metal mirror structure on an opposite side of the first metal mirror structure, the second metal mirror structure comprising a second metal layer and a second supporting layer, wherein the first supporting layer and the second supporting layer are parallel and comprise at least one of aluminum oxide or titanium dioxide.

[0125] In step 450 , a Fabry-Perot cavity is formed between a first supporting layer and a second supporting layer, whereby the cavity is formed by providing an insulating layer on the first metallic mirror structure and at least partially removing the insulating layer after providing the second metallic mirror structure.

[0126] In step 460, electrodes are formed for providing electrical contact to the first metal layer and the second metal layer.

[0127] In step 470, the method ends.

[0128] The method steps described above may be performed in an order different from that presented and may be performed in Figure 4 Perform other steps between the steps.

[0129] In an embodiment, a passivation layer including aluminum oxide may be formed on the surface of the substrate to protect from influence caused by chemical interaction between the passivation layer and the conductive electrode by making a barrier layer therebetween.

[0130] A barrier layer comprising titanium and oxygen, tantalum and oxygen, zirconium and oxygen, hafnium and oxygen, or any combination of these, or any combination of these with aluminum and oxygen, on the passivation layer can be deposited by: exposing the passivation layer to alternating and repeated surface reactions of two or more different precursors in a reaction space, wherein at least one of the precursors is a precursor of oxygen; and forming a conductive electrode on the barrier layer deposited on the passivation layer by making a layer comprising aluminum paste on the barrier layer.

[0131] Subsequently, the reaction space can be pumped to a pressure suitable for forming a passivation layer including aluminum oxide. The reaction space can be pumped to a suitable pressure using, for example, a mechanical vacuum pump, or, in the case of an atmospheric pressure ALD system and / or process, a gas flow can be provided to protect the deposition area from atmospheric influences. The substrate can also be heated to a temperature suitable for forming a passivation layer by the method used. The substrate can be introduced into the reaction space by, for example, an airtight load lock system or only by a loading port. The substrate can be heated by, for example, a resistive heating element that also heats the entire reaction space.

[0132] After the substrate and reaction space have reached the target temperature and other conditions suitable for deposition, the silicon surface can be adjusted so that the passivating deposit can be deposited substantially directly on the surface. Such adjustment of the surface on which the passivation layer is to be deposited can include chemically purifying the surface of the film from impurities and / or oxidation. In particular, it is beneficial to remove oxides when the silicon surface has been introduced into the reaction space via an oxidizing environment (for example, when the exposed surface is transferred from one deposition tool to another deposition tool). In view of this specification, the details of the process of removing impurities and / or oxides from the surface of the silicon film are obvious to the technician. In some embodiments of the present invention, the adjustment can be performed ex situ, that is, outside a tool suitable for an ALD type process.

[0133] After conditioning the substrate, one can begin exposing the deposition surface alternately to different precursor chemistries to form a passivation layer (comprising, for example, aluminum oxide) directly on the silicon substrate. Each exposure of the deposition surface to a precursor results in the formation of additional deposits on the deposition surface due to the adsorption reaction of the corresponding precursor to the deposition surface.

[0134] A typical reactor suitable for ALD type deposition includes a system for introducing a carrier gas (such as nitrogen or argon) into the reaction space so that the reaction space can be purged from excess chemicals and reaction byproducts before the next precursor chemical is introduced into the reaction space. This feature, together with the controlled dosage of vaporized precursors, enables the substrate surface to be exposed to the precursors alternately without significant mixing of different precursors in the reaction space or other parts of the reactor. In practice, the flow of carrier gas is usually passed continuously through the reaction space throughout the deposition process, and only the various precursors are introduced alternately into the reaction space together with the carrier gas.

[0135] The thickness of the passivation layer on the substrate can be controlled by the number of times the deposition surface is exposed to different precursors. The thickness of the passivation layer is increased until a target thickness is reached, after which at least one insulator layer is deposited.

[0136] In one embodiment of the invention, the deposition of the insulating layer is carried out in the same deposition tool in an ALD type process immediately after the deposition of the passivation layer is finished. In this case, the deposition of the insulator layer can be started simply by changing the precursor chemistry from the chemistry used to deposit the passivation layer to the chemistry suitable for depositing the insulator layer.

[0137] In an embodiment, a semiconductor device includes a bond wire package including a microelectromechanical (MEMS) Fabry-Perot interferometer stacked on a die. The die may be arranged on a lead frame. The lead frame may be a pin grid array (PGA) package, a quad flat no-lead (QFN) package, or other packages. The lead frame may include a first pad and may be mounted on a PCB. An intermediate layer may be arranged between the microelectromechanical (MEMS) Fabry-Perot interferometer and the die, and the microelectromechanical (MEMS) Fabry-Perot interferometer is connected to the die. The microelectromechanical (MEMS) Fabry-Perot interferometer, the die, and the intermediate layer may replace the microelectromechanical (MEMS) Fabry-Perot interferometer and the die.

[0138] In an embodiment, the metallization layer may include passive devices, portions of passive devices, and / or interconnect devices (eg, couplers, jumpers, traces, etc.).

[0139] A microelectromechanical (MEMS) Fabry-Perot interferometer may include an insulating layer or a second substrate and a metallization layer. The insulating layer or the second substrate is disposed between the metallization layers. The insulating layer or the second substrate may include a through hole. The through hole may be a through glass via (TGV) or a through silicon via (TSV).

[0140] The additional pad may be provided on a micro-electromechanical (MEMS) Fabry-Perot interferometer. The pad may be connected to the first pad via a bonding wire. The pad may, for example, be connected to a metallization layer and / or a passive device in the metallization layer.

[0141] As disclosed, the microelectromechanical (MEMS) Fabry-Perot interferometer (FPI) 100 chip can cover a larger wavelength range than the dielectric mirror MEMS-FPI. Typically, the dielectric mirror MEMS-FPI can be tuned within a wavelength range of ±10...15% around the design wavelength. Outside the operating wavelength range, the dielectric mirror MEMS-FPI has a high transmittance. However, the metal mirror of the microelectromechanical (MEMS) Fabry-Perot interferometer (FPI) 100 only transmits the spectral band of the FPI air gap 140 corresponding to the constructive interference. This is why, for example, it can be used in a wide spectral range hyperspectral imager based on an RGB type image sensor.

[0142] Figure 5 Another schematic diagram of a device 500 including a micro-electromechanical system (MEMS) Fabry-Perot interferometer (FPI) 100 according to an embodiment of the present invention is illustrated.

[0143] Apparatus 500 may include, for example, a hyperspectral imager.

[0144] In an embodiment, the hyperspectral imager 500 includes a micro-electromechanical (MEMS) Fabry-Perot interferometer (FPI) 100, as shown. The micro-electromechanical (MEMS) Fabry-Perot interferometer (FPI) 100 is arranged on a support plate 710, for example, including a hole for light. See, for example Figures 1 to 3 , used to generate holes.

[0145] In an embodiment, a micro-electromechanical system (MEMS) Fabry-Perot interferometer (FPI) chip 100 is placed between two wafer-level optical lenses 720-730. The first lens 720 (wafer-level imaging lens) collimates the light entering the FPI 100, while the second lens 730 (wafer-level focusing lens) focuses the target image onto the image sensor 740. Thus, a very compact hyperspectral imager 500 within a cubic centimeter size can be constructed.

[0146] Without in any way limiting the scope, interpretation, or application of the claims appearing below, a technical effect of one or more of the example embodiments disclosed herein is an improved performance of a microelectromechanical (MEMS) Fabry-Perot interferometer. Another technical effect of one or more of the example embodiments disclosed herein is an improved fabrication process of a microelectromechanical (MEMS) Fabry-Perot interferometer. Another technical effect of one or more of the example embodiments disclosed herein is a reliable and compact semiconductor device is provided. Yet another technical effect of one or more of the example embodiments disclosed herein is a limited size of a microelectromechanical (MEMS) Fabry-Perot interferometer with a wide variety of operating wavelengths.

[0147] Although various aspects of the invention are set out in the independent claims, further aspects of the invention comprise other combinations of features from the described embodiments and / or the dependent claims with features of the independent claims, not just these combinations explicitly listed in the claims.

[0148] It should also be noted herein that although exemplary embodiments of the present invention are described above, these descriptions should not be construed in a limiting sense. On the contrary, several variations and modifications may be made without departing from the scope of the present invention as defined in the appended claims.

Claims

1. A microelectromechanical (MEMS) Fabry-Perot interferometer (100), comprising: Transparent substrate (110); A first metal mirror structure (120), located on the transparent substrate (110), comprising a first metal layer (121) and a first supporting layer (122-123); a second metal mirror structure (130), wherein the second metal mirror structure (130) is located on an opposite side of the first metal mirror structure (120) with respect to the transparent substrate (110), above the first metal mirror structure (120), the second metal mirror structure (130) comprising a second metal layer (131) and a second supporting layer (132-133), wherein the first supporting layer (122-123) and the second supporting layer (132-133) are parallel and comprise at least one of aluminum oxide or titanium dioxide; a Fabry-Perot cavity (140) between the first supporting layer (122-123) and the second supporting layer (132-133), whereby the Fabry-Perot cavity (140) is formed by providing an insulating layer (141) on the first mirror structure (120) and at least partially removing the insulating layer (141) after providing the second mirror structure (130); as well as Electrodes (150-151) are used to provide electrical contact with the first metal layer (121) and the second metal layer (131).

2. The microelectromechanical (MEMS) Fabry-Perot interferometer (100) according to claim 1, further comprising: A first aluminum oxide layer (111) is arranged below the transparent substrate (110); as well as A second aluminum oxide layer (122) is arranged above the transparent substrate (110), wherein the second aluminum oxide layer (122) is a part of the first supporting layer (122-123) of the first metal mirror structure (120).

3. The microelectromechanical (MEMS) Fabry-Perot interferometer (100) according to claim 2, further comprising: A lower insulating layer (112) is disposed below the first aluminum oxide layer (111), wherein the lower insulating layer (112) comprises tetraethyl orthosilicate.

4. The microelectromechanical (MEMS) Fabry-Perot interferometer (100) according to claim 2 or 3, wherein the first metal layer (121) of the first metal mirror structure (120) is arranged above the second aluminum oxide layer (122).

5. The microelectromechanical (MEMS) Fabry-Perot interferometer (100) according to claim 4, further comprising: A third aluminum oxide layer (123) is arranged above the first metal layer (121), wherein the third aluminum oxide layer (123) is a part of the first supporting layer (122-123) of the first metal mirror structure (120).

6. The microelectromechanical (MEMS) Fabry-Perot interferometer (100) according to claim 5, further comprising: A first electrical contact (150) is arranged to be connected to the first metal layer (121), wherein a portion of the third aluminum oxide layer (123) between the first electrical contact (150) and the first metal layer (121) is removed by wet etching.

7. The microelectromechanical (MEMS) Fabry-Perot interferometer (100) according to claim 5 or 6, further comprising: The insulating layer (141) is arranged above the third aluminum oxide layer (123), wherein the insulating layer (141) comprises tetraethyl orthosilicate.

8. The microelectromechanical (MEMS) Fabry-Perot interferometer (100) according to claim 7, further comprising: A fourth aluminum oxide layer (132) is arranged above the insulating layer (141), wherein the fourth aluminum oxide layer (132) is a part of the second supporting layer (132-133) of the second metal mirror structure (130).

9. The microelectromechanical (MEMS) Fabry-Perot interferometer (100) according to claim 8, wherein the second metal layer (131) of the second metal mirror structure (130) is arranged above the fourth aluminum oxide layer (132).

10. The microelectromechanical (MEMS) Fabry-Perot interferometer (100) according to claim 9, further comprising: A fifth aluminum oxide layer (133) is arranged above the second metal layer (131), wherein the fifth aluminum oxide layer (133) is a part of the second supporting layer (132-133) of the second metal mirror structure (130).

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