Optical biosensor and manufacturing method thereof

Abstract

An optical biosensor according to one embodiment of the present invention comprises: a first semiconductor substrate including a first cavity and a second cavity; a first glass window which seals the first cavity and is inserted into the upper part of the first cavity; a second glass window which seals the second cavity and is inserted into the upper part of the second cavity; a bonding substrate bonded to the first semiconductor substrate; a light-emitting element disposed on one surface of the bonding substrate and accommodated in the first cavity; and a light-receiving element disposed on one surface of the bonding substrate and accommodated in the second cavity.

Description

Photobiosensor and its manufacturing method

[0001] The present invention relates to a photoplethysmography (PPG) sensor and an infrared body temperature sensor, and more particularly, to a package for a photobiosensor and a method for manufacturing the same.

[0002] As interest in exercise and health grows in the wake of COVID-19, the market for wearable devices with healthcare features is rapidly growing. In particular, PPG sensors and infrared temperature sensors are expected to see growth annually as biomarkers for disease diagnosis. To reduce the weight and thickness of wearable devices, the development and application of technologies that integrate multiple types of sensors into a single device is essential.

[0003] As the incidence of adult diseases rises, demand is growing for technologies that measure biosignals to help people manage their health in daily life and respond quickly to emergencies. Consequently, there is a growing need to develop technologies to implement modules that incorporate sensors that function as biomarkers, such as blood flow sensors and infrared sensors, into wearable devices like smartwatches and earphones.

[0004] PPG sensors optically detect light reflected or transmitted from tissues and blood, allowing them to observe changes in blood flow and provide important information such as heart rate, blood pressure, respiration, and blood oxygen saturation. Infrared sensors can detect human body temperature. PPG and infrared sensors can be integrated into wearable devices.

[0005] The technical problem to be solved by the present invention is to provide a photoplethysmography (PPG) sensor that increases light scattering or light diffusion of a light-emitting element housed in a cavity by using a nanostructure formed in an etching process of forming a cavity by etching a silicon substrate to expose a glass window filling a hole of the silicon substrate, and increases light collection efficiency by inserting a lens or the like into a glass window of a light-receiving element.

[0006] The technical problem to be solved by the present invention is to provide a photoplethysmography (PPG) sensor that prevents interference between a light-emitting element and a light-receiving element by using a silicon barrier formed by etching a silicon substrate.

[0007] The technical problem to be solved by the present invention is to provide an infrared sensor having improved performance of the infrared sensor through vacuum hermetic sealing of a silicon substrate having a silicon barrier and a bonding substrate.

[0008] The technical problem to be solved by the present invention is to provide a semiconductor packaging substrate that integrally comprises a glass window for transmitting visible light and a silicon window for transmitting mid-infrared light.

[0009] The technical problem to be solved by the present invention is to provide an optical front end package of a highly integrated optical biosensor capable of measuring heart rate, blood oxygen concentration, etc. by including a silicon partition between a light-emitting element and a light-receiving element constituting a PPG sensor, and measuring body temperature by detecting mid-infrared rays passing through a silicon window.

[0010] The technical problem to be solved by the present invention is to provide a PPG sensor in which a light-scattering nanostructure for irradiating a wide skin area with an LED light source of a PPG sensor is applied to a glass window for a light-emitting element, and a functional structure such as a polarizer is applied to the glass window for a light-receiving element to improve the signal-to-noise ratio for reflected light incident on the light-receiving element.

[0011] The technical problem to be solved by the present invention is to provide an ultra-thin, lightweight composite sensor module at the wafer level that can utilize existing semiconductor processes.

[0012] An optical biosensor according to one embodiment of the present invention comprises: a first semiconductor substrate including a first cavity and a second cavity; a first glass window sealing the first cavity and inserted into an upper portion of the first cavity; a second glass window sealing the second cavity and inserted into an upper portion of the second cavity; a bonding substrate bonded to the first semiconductor substrate; a light-emitting element disposed on one surface of the bonding substrate and accommodated in the first cavity; and a light-receiving element disposed on one surface of the bonding substrate and accommodated in the second cavity.

[0013] In one embodiment of the present invention, the bonding substrate is a substrate including a through via, the light emitting element can be electrically connected through the through via, and the light receiving element can be electrically connected through the through via.

[0014] In one embodiment of the present invention, the lower surface of the first glass window includes a roughened nanostructure, and the nanostructure can scatter light.

[0015] In one embodiment of the present invention, the lower surface of the second glass window is roughened and then coated with a visible light anti-reflection coating, and the upper surface of the first glass window and the upper surface of the second glass window may be flush with the upper surface of the first semiconductor substrate.

[0016] In one embodiment of the present invention, a polarizer may be further included on the upper surface of at least one of the first glass window and the second glass window.

[0017] In one embodiment of the present invention, a metalens or Fresnel lens may be further included formed on the upper surface of at least one of the first glass window and the second glass window.

[0018] In one embodiment of the present invention, the first glass window and at least one of the first glass windows may further include a visible light anti-reflective coating layer disposed on the first glass window.

[0019] In one embodiment of the present invention, the bonding substrate may further include an infrared sensor disposed on one surface thereof; and a third cavity recessed in a lower surface of the first semiconductor substrate and accommodating the infrared sensor.

[0020] In one embodiment of the present invention, a mid-infrared anti-reflection coating layer may be further formed on the upper surface of the third cavity and the upper surface of the first semiconductor substrate corresponding to the third cavity.

[0021] In one embodiment of the present invention, a getter may be further included that is placed in the third cavity and maintains a vacuum state.

[0022] In one embodiment of the present invention, a metalens or Fresnel lens of the mid-infrared band formed on the upper surface of the third cavity may be further included.

[0023] In one embodiment of the present invention, the thickness of the first glass window and the second glass window may be 100 um to 300 um, the depth of the first cavity and the second cavity may be 300 um to 500 um, and the partition between the first cavity and the second cavity may be 100 um to 300 um.

[0024] A method for manufacturing an optical biosensor according to one embodiment of the present invention comprises: forming a first hole and a second hole by anisotropically etching a first semiconductor substrate; laminating a glass substrate on the first semiconductor substrate having the first hole and the second hole formed thereon and thermally reflowing the glass substrate to fill the first hole and the second hole with the glass substrate to form a first glass window and a second glass window, respectively; exposing one surface of the first semiconductor substrate through a chemical mechanical polishing process; anisotropically etching the other surface of the first semiconductor substrate to expose the first glass window and the second glass window to form a first cavity and a second cavity, respectively; and bonding a bonding substrate having a light-emitting element accommodated in the first cavity and a light-receiving element accommodated in the second cavity mounted thereon to the other surface of the first semiconductor substrate.

[0025] In one embodiment of the present invention, the step of forming a first cavity and a second cavity by exposing the first glass window and the second glass window by anisotropically etching the other surface of the first semiconductor substrate can form a roughened nanostructure on the exposed surfaces of the first glass window and the second glass window by a BOSCH etching process that alternates etching and passivation.

[0026] In one embodiment of the present invention, the method may further include one of: forming a metal grid polarizer on at least one flat surface among the first glass window and the first glass window; forming a metalens on at least one flat surface among the first glass window and the first glass window; and forming a Fresnel lens on at least one flat surface among the first glass window and the first glass window.

[0027] In one embodiment of the present invention, the step of forming a visible light anti-reflective coating on at least one exposed upper surface of the first glass window and the first glass window may be further included.

[0028] In one embodiment of the present invention, the step of forming a first cavity and a second cavity by exposing the first glass window and the second glass window by anisotropically etching the other surface of the first semiconductor substrate may further form a third cavity spaced apart from the first cavity and the second cavity by anisotropically etching the other surface of the first semiconductor substrate.

[0029] In one embodiment of the present invention, the method may further include forming a mid-infrared anti-reflection coating layer on the lower surface of the third cavity; and forming a mid-infrared anti-reflection coating layer on the upper surface of the first semiconductor substrate corresponding to the third cavity.

[0030] In one embodiment of the present invention, at least one of the steps of forming a mid-infrared anti-reflection coating layer on the lower surface of the third cavity; the step of forming a metalens on the upper surface of the first semiconductor substrate corresponding to the third cavity; and the step of forming a Fresnel lens may be further included.

[0031] In one embodiment of the present invention, the step of bonding the other surface of the first semiconductor substrate and the bonding substrate on which the light-emitting element accommodated in the first cavity and the light-receiving element accommodated in the second cavity are mounted may bond the other surface of the first semiconductor substrate and the bonding substrate on which the light-emitting element accommodated in the first cavity, the light-receiving element accommodated in the second cavity, and the infrared sensor accommodated in the third cavity are mounted.

[0032] In one embodiment of the present invention, a photobio sensor can improve the signal-to-noise ratio (SNR) of a PPG sensor by applying various nanostructures such as a light scatterer, an anti-reflection film, and a polarizer to a semiconductor substrate.

[0033] In one embodiment of the present invention, the optical biosensor can be configured to integrate two or more types of optical sensors (visible light receiving sensor, infrared light receiving sensor) using different wavelengths into a single package, thereby providing a glass window for the visible light receiving sensor and a silicon window for the infrared light receiving sensor, thereby providing light weight and thinness.

[0034] In one embodiment of the present invention, the photobio sensor utilizes existing semiconductor process technology, so it can provide cost reduction and process simplification without requiring additional processes.

[0035] In one embodiment of the present invention, the photobio sensor can mount two or more types of photo sensors, such as a PPG sensor and an infrared sensor, into one, and thus can play a very important role in making a wearable device for monitoring biosignals light, thin, short, and small.

[0036] In one embodiment of the present invention, a photobiosensor includes a nanostructure formed on a glass window, wherein the nanostructure acts as a light scatterer for light emitted from a light-emitting element, enabling uniform irradiation of light onto a skin surface, and the nanostructure can act as an anti-reflection film for reflected light reaching a light-receiving element.

[0037] In one embodiment of the present invention, the photobio sensor can increase energy efficiency by securing the SNR of the PPG signal through integration of polarizers.

[0038] In one embodiment of the present invention, the photobiosensor can provide a high-efficiency optical window of the photosensor.

[0039] In one embodiment of the present invention, the optical biosensor can be configured to package multiple types of optical biosensors into a single package, and separate the wavelength bands of incident light into optical sensors operating in different wavelength bands using different optical windows.

[0040] In one embodiment of the present invention, the photobio sensor can form two types of optical windows, including a silicon window with a partition wall and a glass window, to solve the problem of not being able to mount sensors with different wavelength bands together.

[0041] In one embodiment of the present invention, the photobiosensor includes an optical window to increase the light efficiency of the light receiving portion, and a nanostructure (optical diffuser) formed during a dry etching process of forming the optical window helps light scattering.

[0042] In one embodiment of the present invention, the photobio sensor includes a meta lens, a Fresnel lens, and a polarizer to increase the light efficiency of the light receiving portion, and the meta lens, Fresnel lens, and polarizer can increase the light collection rate.

[0043] In one embodiment of the invention, the photobiosensor includes a silicone baffle to prevent interference, and the performance of the infrared temperature sensor can be maximized through vacuum-tight sealing (hermetic sealing).

[0044] FIG. 1 is a conceptual diagram illustrating an optical biosensor according to one embodiment of the present invention.

[0045] Fig. 2a is a cross-sectional view showing the photobio sensor of Fig. 1.

[0046] Figure 2b is a plan view showing the photobio sensor of Figure 2a.

[0047] FIGS. 3A to 3J are cross-sectional views showing a method for manufacturing an optical biosensor according to one embodiment of the present invention.

[0048] PPG sensors and infrared temperature sensors function as biomarkers, providing extensive information about the physiological state of the human body. According to one embodiment of the present invention, a photobiosensor provides technology for integrating a PPG sensor and an infrared sensor into a single package.

[0049] The present invention can be applied to embedding a multifunctional optical biosensor in a wearable device. Accordingly, it is expected to be applicable not only to wearable devices but also to simplifying medical measurement equipment in the future.

[0050] The present invention may include a nanostructure that performs a light scattering or optical diffuser function based on a conventional semiconductor process. The present invention can minimize optical interference by forming a silicon barrier between a light-emitting element and a light-receiving element based on a semiconductor process.

[0051] The present invention can be applied to an optical biosensor package for measuring biosignals in wearable devices such as smartwatches. The optical biosensor's manufacturing process is based on existing semiconductor processing technology, and the packaging is simplified. The present invention enables the implementation of an ultra-thin, lightweight, wafer-level composite sensor module.

[0052] The present invention can be applied to an optical biosensor that utilizes different wavelength bands, as it includes a glass window and a silicon window in a package. The present invention can apply an anti-reflection film to minimize reflection of light reaching the light scatterer and light receiving unit required for the light source, and it is possible to form a polarizer on the surface of the glass window using a semiconductor process. Accordingly, the signal-to-noise ratio (SNR) of the PPG sensor can be improved.

[0053] The present invention comprises a glass window and a silicon window. A PPG sensor utilizing the visible and near-infrared bands transmits light through the glass window, while an infrared temperature sensor utilizing the mid-infrared band transmits light through the silicon window. The glass window and silicon window can be formed as a single unit through a semiconductor process, thereby enabling mass production.

[0054] The package structure of the present invention includes a glass window that transmits visible light and a silicon window that transmits mid-infrared light. The glass window that transmits visible light and the partition formed on the silicon semiconductor substrate can minimize interference between the light source and the photodetector of a PPG sensor. Functional structures such as nanostructures, anti-reflective coatings, and lenses that perform various functions are formed on the upper and lower surfaces of the glass window, thereby improving the performance of the PPG sensor. Furthermore, the functional structures such as nanostructures, anti-reflective coatings, and lenses can be stably formed using existing semiconductor processes.

[0055] In addition, in the package structure of the present invention, the first semiconductor substrate and the bonding substrate on which the infrared sensor is mounted can maximize the performance of the temperature sensor through hermetic sealing.

[0056] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosure is thorough and complete and to sufficiently convey the spirit of the present invention to those skilled in the art. In the drawings, components are exaggerated for clarity. Parts denoted by the same reference numerals throughout the specification represent the same components.

[0057] FIG. 1 is a conceptual diagram illustrating an optical biosensor according to one embodiment of the present invention.

[0058] Fig. 2a is a cross-sectional view showing the photobio sensor of Fig. 1.

[0059] Figure 2b is a plan view showing the photobio sensor of Figure 2a.

[0060] Referring to FIGS. 1, 2a, and 2b, the photobio sensor (200) may include a PPG sensor (201) and an infrared sensor unit (202). The photobio sensor (200) may include: a first semiconductor substrate (110) including a first cavity (117a) and a second cavity (117b); a first glass window (114a) that seals the first cavity (117a) and is inserted into an upper portion of the first cavity (117a); a second glass window (114b) that seals the second cavity (117b) and is inserted into an upper portion of the second cavity (117b); a bonding substrate (120) that is bonded to the first semiconductor substrate (110); a light-emitting element (132) that is disposed on one surface of the bonding substrate (120) and is accommodated in the first cavity (117a); and a light-receiving element (134) disposed on one surface of the bonding substrate (120) and accommodated in the second cavity (117b).

[0061] The PPG sensor (201) includes a light-emitting element (132) and a light-receiving element (134), and may include a light-emitting element (132) that emits light and a light-receiving element (134) that detects light emitted from the light-emitting element and reflected from the skin. The light-emitting element (132) may be integrated in one or more to emit light in the visible to near-infrared range, and may be, for example, a green LED, a red LED, or a near-infrared LED. The light emitted from the light-emitting element (132) changes in reflectance or transmittance according to changes in blood vessel volume in the skin of the human body, and the light-receiving element (134) can detect changes in the reflectance or transmittance. In order to prevent the light emitted from the light-emitting element (132) from directly incident on the light-receiving element (134), a partition wall (101) and cavities (117a, 117b) are provided. The above-mentioned partition wall (101) can be formed by etching the first semiconductor substrate (110). When the first semiconductor substrate (110) is a silicon substrate, the wavelength of the visible light to near-infrared band of the light-emitting element (132) disposed in the first cavity (117a) (e.g., green, red, near-infrared wavelength) may be absorbed or reflected by the partition wall (101) formed by the first semiconductor substrate and may not directly interfere with the light-receiving element (134) disposed in the second cavity (117b).

[0062] In addition, the first glass window (114a) is arranged on the upper surface of the first cavity (117a), and the green wavelength of the light emitting element (132) can transmit through the first glass window (114a). The first glass window (114a) may be made of a material that is transparent to visible light. Meanwhile, the green wavelength transmitted through the first glass window (117a) may include a nanostructure (115) for uniform irradiation over a wide area. The nanostructure (115) may be a roughened surface or a nanopillar structure to scatter or diffuse light. The nanostructure (115) may depend on the material of the first glass window (114a). It is interpreted that the first glass window (114a) collides with ions during the etching process, causing a deviation on the surface, and when this is repeated, the nanostructure (115) is formed by the surface roughness. According to a modified embodiment of the present invention, the first glass window can be changed to another material that is transparent to visible light (e.g., transparent plastic, transparent film).

[0063] The light receiving element (132) can detect light reflected from the skin or light transmitted through the skin. The light receiving element (132) may be a silicon photodiode. The light receiving element (132) is disposed in the second cavity (117b), and the light reflected from the skin can reach the light receiving element (134) by transmitting a second glass window (114b) disposed on an upper surface of the second cavity (117b). Meanwhile, the second glass window (114b) may include a nanostructure similar to the first glass window (114a). However, the nanostructure of the second glass window may be covered with an anti-reflection coating layer (116) to reduce reflection of incident light. The anti-reflection coating layer (116) uses an anti-reflection (AR) coating having a multilayer thin film structure to prevent surface reflection. Multilayer antireflection coatings utilize interference effects to reduce surface reflectance. These multilayer antireflection coatings have a laminated structure (e.g., 2 to 27 layers) with different refractive indices.

[0064] The infrared sensor (136) is a sensor that detects infrared rays emitted from the human body, and may be a thermal sensor such as a microbolometer or a thermopile, or a quantum sensor. The infrared sensor (136) is disposed in the third cavity (117c), and the third cavity (117c) may be sealed in a vacuum state to increase the sensitivity of the infrared sensor (136). In addition, a getter (246) may be disposed to maintain the vacuum of the third cavity (117c). The getter (246) may adsorb impurities to maintain the vacuum. The third cavity (117c) is maintained in a vacuum state to improve the sensitivity of the infrared sensor or prevent external heat from being transferred to the infrared sensor (136). The infrared sensor (136) may be disposed on one surface of the bonding substrate (120). The third cavity (117c) accommodates the infrared sensor (136) and can be sunken into the lower surface of the first semiconductor substrate (110).

[0065] The upper surface of the third cavity (117c) may be covered by the first semiconductor substrate (110). That is, the first semiconductor substrate (110) may function as an optical window (214) that transmits infrared rays. For example, when the first semiconductor substrate is a silicon substrate, mid-infrared wavelengths radiated from the human body may not be absorbed by the first semiconductor substrate but may pass through the first semiconductor substrate (110) and reach the infrared sensor (136).

[0066] According to the present invention, the light receiving element (134) and the infrared sensor (136) that operate at different wavelengths can have windows made of different materials to transmit light of a desired wavelength. That is, wavelengths in the visible light band cannot transmit through the infrared optical window (214) formed of the first semiconductor substrate and are absorbed, so that the infrared sensor (136) can only absorb mid-infrared rays radiated by the human body. Meanwhile, infrared rays radiated from the human body transmit through the second glass window (114b), but the light receiving element (134) may be a silicon photodiode that does not operate in the mid-infrared region.

[0067] The infrared sensor (136), the light emitting element (132), and the light receiving element (134) may be mounted on a bonding substrate (120). The bonding substrate (120) may be bonded to the first semiconductor substrate (110) to seal the third cavity (117c) in a vacuum state. The bonding substrate (120) may be a printed circuit board, a semiconductor substrate, a glass substrate, a ceramic substrate, or an opaque plastic substrate. The bonding substrate (120) includes a via (131) penetrating the bonding substrate, and the via (131) may provide an electrical connection to the infrared sensor (136), the light emitting element (132), and the light receiving element (134). The bonding substrate (120) may be attached to a separate printed circuit board and connected to a driving circuit and a control circuit. The bonding method of the above bonding substrate (120) and the first semiconductor substrate (110) may use anodic bonding of glass and silicon, a bonding method using an adhesive, or eutectic bonding. In order to seal the third cavity (117c) in a vacuum state, the bonding substrate (120) may be a silicon semiconductor substrate, and the via (131) may be a through silicon via (TSV).

[0068] The first semiconductor substrate (110) may be a silicon substrate. The first semiconductor substrate (110) may absorb a wavelength band (e.g., a green wavelength band) of the light-emitting element (132). The first semiconductor substrate (110) may function as a partition wall (101) that suppresses optical interference between the light-emitting element and the light-receiving element. The first cavity (117a) and the second cavity (117b) may be separated by the partition wall (101). The thickness of the partition wall (101) may be about 200 μm. The thickness of the first semiconductor substrate (110) may be about 600 μm. The depth of the first cavity (117a) may be about 400 μm. The shape of the first cavity (117a) may be a square.

[0069] The lower surface of the first glass window (114a) includes a roughened nanostructure (115), and the nanostructure (115) can scatter or diffuse light. The lower surface of the second glass window (114b) can be roughened and then subjected to a visible light anti-reflection coating (116). The upper surface of the first glass window (114a) and the upper surface of the second glass window (114b) can be flush with the upper surface of the first semiconductor substrate (110). The first glass window (114a) and the second glass window (114b) can include metal impurities so as to form nanostructures during an etching process. Glass thermal reflow can be heat-treated so that the glass fills the groove formed in the first semiconductor substrate (110). The glass thermal reflow can be performed at 700 degrees Celsius or higher for several tens of minutes or more.

[0070] The bonding substrate (120) may be made of a material that does not allow external light to pass through to the second cavity (117b). Preferably, the bonding substrate (120) may be a silicon semiconductor substrate. The bonding substrate (120) may be made of a material that can maintain sealing properties. The bonding substrate (120) may have a rigidity and thickness that are not bent by the vacuum pressure of the third cavity (117c). Preferably, the thickness of the bonding substrate (120) may be on the order of 100 μm when made of silicon.

[0071] The bonding substrate (120) may be an organic substrate or an inorganic substrate. The bonding substrate (120) may be a glass substrate, a ceramic substrate, a polyimide substrate, a PCB, or a semiconductor substrate. When bonding the bonding substrate (120) and the first semiconductor substrate (110), an adhesive such as solder or epoxy may be used. When the bonding substrate (120) is a glass substrate, anodic bonding may be used. In the case of anodic bonding, a thermocompression temperature of 300 degrees Celsius or higher and a force of 1500 N (for an 8-inch wafer) or higher may be applied. When solder is used, the thermocompression temperature may be around 250-350 degrees Celsius. When an adhesive is used, the curing process may be performed at 200 degrees Celsius or lower.

[0072] The light-emitting element (132) may be one or more green LEDs, red LEDs, or near-infrared LEDs that emit visible light. One or more light-emitting elements (132) may be electrically connected by wiring or wire bonding formed on the bonding substrate (120).

[0073] The light-receiving element (134) may be a photodiode that responds to visible light. Specifically, the light-receiving element (134) may be a silicon photodiode. The light-receiving element (134) may be electrically connected by wiring or wire bonding formed on the bonding substrate (120).

[0074] The above bonding substrate (120) is a semiconductor substrate including a through-silicon via, and the light-emitting element (132) can be electrically connected through the through-silicon via (131) of the bonding substrate (120). The light-receiving element (134) can be electrically connected through the through-silicon via of the bonding substrate.

[0075] The functional structure (120) may be placed on the upper surface of the first glass window (114a) or the second glass window (114b). The functional structure (120) may be a polarizer (121), a metalens (122), or a Fresnel lens (123).

[0076] A polarizer (121) may be placed on the upper surface of the first glass window (114a) or the second glass window (114b). The polarizer may be a wire grid polarizer.

[0077] A metalens (122) or Fresnel lens (123) may be formed on the upper surface of the first glass window (114a) or the second glass window (114b). The metalens may function as a lens using a nanostructure. The Fresnel lens may be a lens composed of concentric grooves.

[0078] The visible light anti-reflective coating layer (142) can be placed on the upper surface of the first glass window (114a) or the second glass window (114b).

[0079] The mid-infrared anti-reflection coating layer (242, 243) may be formed on the upper surface of the third cavity (117c) and the upper surface (or infrared optical window) of the first semiconductor substrate (110) corresponding to the third cavity. According to a modified embodiment of the present invention, a metalens or Fresnel lens of the mid-infrared band may be formed on the upper surface of the third cavity (117c).

[0080] The thickness of the first glass window (114a) and the second glass window (114b) may be 100 um to 300 um, the depth of the first cavity (117a) and the second cavity (117b) may be 300 um to 500 um, and the partition wall (101) between the first cavity and the second cavity may be 100 um to 300 um.

[0081] The above infrared sensor (202) may further include a reference infrared sensor. The reference infrared sensor may be a sensor that blocks infrared rays. The reference infrared sensor may compensate for operating characteristics according to changes in operating temperature.

[0082] FIGS. 3A to 3J are cross-sectional views showing a method for manufacturing an optical biosensor according to one embodiment of the present invention.

[0083] Referring to FIGS. 3a to 3j, a method for manufacturing an optical biosensor includes: a step of forming a first hole (119a) and a second hole (119b) by anisotropically etching a first semiconductor substrate (110); a step of stacking a glass substrate (114) on the first semiconductor substrate (110) on which the first hole (119a) and the second hole (119b) are formed, and thermally reflowing the glass substrate (114) to fill the first hole (119a) and the second hole (119b) with the glass substrate (114) to form a first glass window (114a) and a second glass window (114b), respectively; a step of exposing one surface of the first semiconductor substrate (110) through a chemical mechanical polishing process of the glass substrate (114); The method includes a step of forming a first cavity (117a) and a second cavity (117b) by exposing the first glass window (114a) and the second glass window (114b) by anisotropically etching the other surface of the first semiconductor substrate (110), and a step of bonding a bonding substrate (120) on which a light-emitting element (132) accommodated in the first cavity (117a) and a light-receiving element (134) accommodated in the second cavity (117b) are mounted, to the other surface of the first semiconductor substrate (110).

[0084] Referring to FIGS. 3a and 3b, a first semiconductor substrate (110) is anisotropically etched to form a first hole (119a) and a second hole (119b). The formation of the first hole (119a) and the second hole (119b) can be formed by a photolithography process and an anisotropic etching process.

[0085] Referring to FIGS. 3c and 3d, a glass substrate (114) is laminated on the first semiconductor substrate (110) in which the first hole (119a) and the second hole (119b) are formed, and thermal reflow is performed to fill the first hole (119a) and the second hole (119b) with the glass substrate (114), thereby forming a first glass window (114a) and a second glass window (114b), respectively. The glass substrate (114) may include metal impurities. The temperature of the thermal reflow may be 850 degrees Celsius for 10 hours.

[0086] Referring to FIG. 3e, one surface of the first semiconductor substrate (110) is exposed through a chemical mechanical polishing process of the glass substrate (114).

[0087] Referring to FIG. 3f, the other surface of the first semiconductor substrate (110) is anisotropically etched to expose the first glass window (114a) and the second glass window (114a), thereby forming a first cavity (117a) and a second cavity (117b), respectively. The anisotropic etching can form a roughened nanostructure (115) on the exposed surfaces of the first glass window and the second glass window by a BOSCH etching process that alternates silicon etching and passivation.

[0088] In the step of forming the first cavity (117a) and the second cavity (117b), respectively, the other surface of the first semiconductor substrate (110) may be anisotropically etched to form a third cavity (117c) spaced apart from the first cavity (117a) and the second cavity (117b).

[0089] Referring to FIG. 3g, a mid-infrared anti-reflection coating layer (243) can be formed on the lower surface of the third cavity. The mid-infrared anti-reflection coating layer can be formed by depositing a dielectric multilayer thin film while the third cavity (117c) is open by a first shadow mask (250).

[0090] Referring to FIG. 3h, a visible light anti-reflection coating can be formed on the exposed upper surface of the first glass window. The visible light anti-reflection coating can be formed by depositing a dielectric multilayer thin film while the second cavity (117b) is open by a second shadow mask (252).

[0091] Referring to FIG. 3i, a mid-infrared anti-reflection coating layer (242) can be formed on the upper surface of the first semiconductor substrate (110) corresponding to the third cavity (117c). The anti-reflection coating layer (242) can be formed using a lift-off technique or a shadow mask technique.

[0092] A functional structure (120) can be formed on the flat surface of the second glass window (114b). The functional structure (120) can be a metal grid polarizer, a metalens, or a Fresnel lens.

[0093] The metal grid polarizer can be formed by depositing a conductor and then patterning it. The metalens can be formed by depositing a metalens material (e.g., silicon) on the first semiconductor substrate and then patterning it. The Fresnel lens can be manufactured through a patterning process on a glass substrate, formed by depositing a Fresnel lens material and then patterning it, or formed Fresnel lenses can be bonded using an adhesive or the like.

[0094] Referring to FIG. 3j, the other surface of the first semiconductor substrate (110) and the bonding substrate (120) on which the light-emitting element (132) accommodated in the first cavity (117a) and the light-receiving element (134) accommodated in the second cavity (117b) are mounted are bonded. Alternatively, the other surface of the first semiconductor substrate (110) and the bonding substrate (120) on which the light-emitting element (132) accommodated in the first cavity (117a), the light-receiving element (134) accommodated in the second cavity (117b), and the infrared sensor (136) accommodated in the third cavity (117c) are mounted may be bonded.

[0095] The bonding method can be anodic bonding, adhesive or solder.

[0096] Although the present invention has been illustrated and described above with respect to specific preferred embodiments, the present invention is not limited to these embodiments, and includes various forms of embodiments that can be implemented by a person having ordinary skill in the art to which the invention pertains without departing from the technical spirit of the present invention claimed in the patent claims.

Claims

1. A first semiconductor substrate including a first cavity and a second cavity; A first glass window sealing the first cavity and inserted into the upper portion of the first cavity; A second glass window that seals the second cavity and is inserted into the upper portion of the second cavity; A bonding substrate bonded to the first semiconductor substrate; A light emitting element disposed on one surface of the bonding substrate and accommodated in the first cavity; and An optical biosensor characterized by comprising a light-receiving element disposed on one surface of the bonding substrate and accommodated in the second cavity.

2. In paragraph 1, The above bonding substrate is a substrate including a through via, The above light emitting element is electrically connected through the above through via, An optical biosensor characterized in that the above light-receiving element is electrically connected through the above throughvia.

3. In paragraph 1, An optical biosensor characterized in that the lower surface of the first glass window includes a roughened nanostructure, and the nanostructure scatters light.

4. In paragraph 3, The lower surface of the second glass window is roughened and then coated with a visible light anti-reflective coating, An optical biosensor characterized in that the upper surface of the first glass window and the upper surface of the second glass window are coplanar with the upper surface of the first semiconductor substrate.

5. In paragraph 1, An optical biosensor further comprising a polarizer disposed on the upper surface of at least one of the first glass window and the second glass window.

6. In paragraph 1, An optical biosensor further comprising a metalens or Fresnel lens formed on the upper surface of at least one of the first glass window and the second glass window.

7. In paragraph 1, An optical biosensor further comprising a visible light anti-reflective coating layer disposed on at least one of the first glass window and the first glass window.

8. In paragraph 1, An infrared sensor disposed on one surface of the above bonding substrate; and An optical biosensor characterized in that it further comprises a third cavity that accommodates the infrared sensor and is sunken in the lower surface of the first semiconductor substrate.

9. In paragraph 8, An optical biosensor further characterized by comprising a mid-infrared anti-reflection coating layer formed on the upper surface of the third cavity and the upper surface of the first semiconductor substrate corresponding to the third cavity.

10. In paragraph 8, An optical biosensor further characterized by including a getter arranged in the third cavity to maintain a vacuum state.

11. In paragraph 8, An optical biosensor further characterized by including a mid-infrared band metalens or Fresnel lens formed on the upper surface of the third cavity.

12. In paragraph 1, The thickness of the first glass window and the second glass window is 100 um to 300 um, The depth of the first cavity and the second cavity is 300 um to 500 um, An optical biosensor characterized in that the partition between the first cavity and the second cavity is 100 um to 300 um.

13. A step of forming a first hole and a second hole by anisotropically etching a first semiconductor substrate; A step of laminating a glass substrate on the first semiconductor substrate having the first hole and the second hole formed thereon and thermally reflowing the glass substrate to fill the first hole and the second hole with the glass substrate to form a first glass window and a second glass window, respectively; A step of exposing one surface of the first semiconductor substrate through a chemical and mechanical polishing process of the glass substrate; A step of anisotropically etching the other surface of the first semiconductor substrate to expose the first glass window and the second glass window to form a first cavity and a second cavity, respectively; and A method for manufacturing an optical biosensor, comprising the step of bonding a bonding substrate having a light-emitting element accommodated in the first cavity and a light-receiving element accommodated in the second cavity mounted thereon to the other surface of the first semiconductor substrate.

14. In paragraph 13, A method for manufacturing an optical biosensor, characterized in that the step of forming a first cavity and a second cavity by exposing the first glass window and the second glass window by anisotropically etching the other surface of the first semiconductor substrate is performed by forming a roughened nanostructure on the exposed surfaces of the first glass window and the second glass window by a BOSCH etching process that alternates etching and passivation.

15. In paragraph 13, A step of forming a metal grid polarizer on at least one flat surface of the first glass window and the first glass window; A step of forming a metalens on at least one flat surface among the first glass window and the first glass window; and A method for manufacturing an optical biosensor, characterized in that it further comprises one of the steps of forming a Fresnel lens on at least one flat surface among the first glass window and the first glass window.

16. In paragraph 13, A method for manufacturing an optical biosensor, characterized in that it further comprises the step of forming a visible light anti-reflective coating on at least one exposed upper surface of the first glass window and the first glass window.

17. In paragraph 13, A method for manufacturing an optical biosensor, characterized in that the step of forming a first cavity and a second cavity by exposing the first glass window and the second glass window by anisotropically etching the other surface of the first semiconductor substrate further forms a third cavity spaced apart from the first cavity and the second cavity by anisotropically etching the other surface of the first semiconductor substrate.

18. In paragraph 17, A step of forming a mid-infrared anti-reflection coating layer on the lower surface of the third cavity; and A method for manufacturing an optical biosensor, characterized in that it further comprises a step of forming a mid-infrared anti-reflection coating layer formed on the upper surface of the first semiconductor substrate corresponding to the third cavity.

19. In paragraph 17, A step of forming a mid-infrared anti-reflection coating layer on the lower surface of the third cavity; and A step of forming a metalens on the upper surface of the first semiconductor substrate corresponding to the third cavity; and A method for manufacturing an optical biosensor, characterized in that it further comprises at least one step of forming a Fresnel lens.

20. In paragraph 17, The step of bonding a bonding substrate on which a light-emitting element accommodated in the first cavity and a light-receiving element accommodated in the second cavity are mounted on the other surface of the first semiconductor substrate is A method for manufacturing an optical biosensor, characterized by bonding the bonding substrate, on which a light-emitting element accommodated in the first cavity, a light-receiving element accommodated in the second cavity, and an infrared sensor accommodated in the third cavity are mounted, with the other surface of the first semiconductor substrate.

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