Synthetic quartz glass cavity part, synthetic quartz glass cavity cover, optical device package and manufacturing method

Abstract

The present invention relates to a synthetic quartz glass cavity, a synthetic quartz glass cavity cover, an optical device package and a manufacturing method. Specifically, a synthetic quartz glass cavity (1) is connected to a substrate (6) on which an optical device (7) is mounted so that the device can be accommodated in the cavity. The cavity (1) is defined by an inner surface consisting of a top surface (2a) and a side surface (3a) opposite to the device (7). The top surface (2a) is a mirror surface and the side surface (3a) is a rough surface.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This nonprovisional application claims priority under 35 USC §119(a) to Patent Application No. 2018-137374 filed in Japan on July 23, 2018, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The invention relates to a synthetic quartz glass cavity, a synthetic quartz glass cavity cover, an optical device package and methods for producing the same. Background Art

[0004] Some mercury vapor lamps are banned from use. Since then, UV-LEDs, which are capable of emitting light of short wavelengths (especially in the UV region), have been considered an attractive alternative. Because arbitrary wavelengths can be extracted from LEDs, LEDs have been developed that are capable of emitting light with wavelengths for specific applications. For example, it is known that a wavelength of 265nm in the UV region is effective for sterilization. UV-LEDs that are capable of emitting light at a wavelength of 265nm have been developed for sterilization applications. Even if there is a stable supply of optical devices (UV-LEDs) with 265nm, it is difficult to use the optical devices without packaging. It is desirable to package the optical device so that light extraction from the UV-LED can be more efficient.

[0005] For electronic devices using surface mounted small packages, many components must have a hollow cavity structure. In recent years, transparent synthetic quartz glass packaging has been required from the perspective of heat resistance. Similarly, many light receiving devices, such as flame sensors for detecting deep UV light, have a hollow cavity structure.

[0006] When encapsulating optical devices such as light emitting devices (usually LEDs) and light receiving devices and micro-electromechanical systems (MEMS) devices, window components or molding materials are necessary. Adhesives used to connect window components include organic adhesives such as adhesives based on epoxy resins and acrylic resins and glass frits. An exemplary molding material is silicone resin.

[0007] For example, Patent Document 1 discloses a method for manufacturing a package having a hollow cavity structure for use in oscillators, gyroscopes, and accelerometers. The concave portion of the cavity is formed by photolithography, etching, or pressing. A glass component having a hollow cavity structure is connected to a pair of glass components by an anodic connection.

[0008] Patent Document 2 describes forming a cavity structure by protective film etching.

[0009] Citation List

[0010] Patent Document 1: JP-A 2010-186945

[0011] Patent Document 2: WO 2015 / 152244

[0012] Invention Disclosure

[0013] Patent Document 1 has some problems. Because the cavity structure is formed by etching, there is a tendency for the opening of the cavity to be circular, so it is difficult to accurately control the dimensional accuracy. The wet etching method fails to penetrate deep recesses. The dry etching method successfully drills deep recesses, but increases machining time and cost. Although anodic bonding is proposed as a bonding method, this method is not adopted in bonding synthetic quartz glass, which is an amorphous high-purity SiO2 material that does not contain metal impurities.

[0014] In Patent Document 2, a cavity structure is formed by mask etching. Similar to Patent Document 1, dimensional accuracy and recess depth are limited, and this technique is less commonly used.

[0015] The present invention aims to provide a synthetic quartz glass cavity, a synthetic quartz glass cavity cover, or an optical device package, which allows an optical device to exert its performance in a short wavelength region, especially in a wavelength region of up to 300 nm, and requires a hollow structure to exert its performance in a stable manner for a long time. Another object is to provide a method for manufacturing a synthetic quartz glass cavity, a synthetic quartz glass cavity cover, or an optical device package, which can be manufactured with precise dimensions and solves the stress problem between different materials during the connection process.

[0016] The inventors have found that the above objects are achieved by the synthetic quartz glass cavity member defined herein; the synthetic quartz glass cavity member has improved heat resistance and UV resistance; and a synthetic quartz glass cavity cover and an optical device package are manufactured using the synthetic quartz glass cavity member.

[0017] In one aspect, the present invention provides a synthetic quartz glass cavity adapted to be connected to a substrate on which an optical device is mounted so that the device can be accommodated in the cavity, the cavity having an inner surface consisting of a surface portion opposite to an active surface of the device and a remaining surface portion, the opposite surface portion being a mirror surface and the remaining surface portion being a rough surface.

[0018] Preferably, the cross section of the cavity is in an inverted concave shape, having a top wall, a side wall and a bottom opening, the inner surface of the top wall is a mirror surface and the inner surface of the side wall is a rough surface.

[0019] Preferably, the top wall of the cavity has an outer surface that is a mirror surface.

[0020] Preferably, the width or diameter of the bottom opening of the cavity and the width or diameter of the inner surface of the top wall are in a ratio of 0.8:1.0-1.2:1.0.

[0021] Preferably, the rough surface of the cavity has a surface roughness (Ra) of 0.1-0.5 μm.

[0022] In another aspect, the present invention provides a cavity cover, which comprises the synthetic quartz glass cavity member and an adhesive layer formed on a portion of the cavity member to connect the substrate.

[0023] Preferably, the adhesive layer of the cavity cover is in B-stage.

[0024] Preferably, the adhesive layer of the cavity cover is a resin-based adhesive layer containing epoxy resin or silicone resin or a metal-based adhesive layer containing metal or a mixture thereof.

[0025] The metal in the adhesive layer is selected from the group consisting of gold, silver, copper, palladium, indium, tin and bismuth.

[0026] In another aspect, the present invention provides an optical device package, which comprises the cavity cover and a substrate on which a light emitting or receiving device is mounted.

[0027] In another aspect, the present invention provides a method for producing a synthetic quartz glass cavity, comprising the following steps:

[0028] drilling the first synthetic quartz glass substrate at a plurality of locations to form a plurality of through holes,

[0029] placing a second synthetic quartz glass substrate on the first synthetic quartz glass substrate to form a laminate, the second synthetic quartz glass substrate having a mirror surface opposite to the perforated synthetic quartz glass substrate, and

[0030] The laminate is cut into a plurality of separate synthetic quartz glass cavity pieces at locations between adjacent through holes.

[0031] Preferably, the drilling step is sandblasting or grinding by a machining center.

[0032] In yet another aspect, the present invention provides a method for manufacturing a cavity cover, comprising the steps of:

[0033] The synthetic quartz glass cavity is manufactured by the method according to claim 11 or 12, and

[0034] A resin or metal-based paste is applied to the lower end of the side wall of the cavity to form a resin or metal-based adhesive layer.

[0035] Preferably, the adhesive layer is a metal-based adhesive layer, and the method further comprises the step of heating the metal-based paste to form a B-stage metal-based adhesive layer.

[0036] In another aspect, the present invention provides a method for manufacturing an optical device package, comprising the steps of:

[0037] The cavity cover is manufactured by the above method, and

[0038] The cavity cover is connected at the adhesive layer to the substrate on which the light emitting or receiving device is mounted so that the device can be accommodated in the cavity.

[0039] Advantageous Effects of the Invention

[0040] The present invention solves the problems of degradation and fracture of glass containing resin or metal impurities used in the cavity parts of the prior art by short wavelength light, and deformation and collapse of the cavity structure due to heat released from the light emitting device, thereby solving the accompanying problem of long-term reliability. The synthetic quartz glass cavity cover can be used as an optical device packaging component requiring heat resistance and UV resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 FIG. 1 is a plan view of a synthetic quartz glass cavity in one embodiment of the present invention.

[0042] Figure 2 is along Figure 1 Cross-sectional view taken along the midline II-II.

[0043] Figure 3 is a cross-sectional view of a synthetic quartz glass cavity cover in another embodiment of the present invention.

[0044] Figure 4 is a cross-sectional view of an optical device package using a synthetic quartz glass cavity cover in other embodiments of the present invention. DETAILED DESCRIPTION

[0045] In the following description, the same reference numerals in the several views shown in the drawings represent the same or corresponding parts. The terms "top", "bottom", etc. are used only for convenience of description and are not limited to any one position or spatial orientation. An optical device having an active surface encompasses a light emitting device having a light emitting surface and a light receiving device having a light receiving surface. Therefore, the active surface refers to the light emitting or receiving surface of the light emitting or receiving device.

[0046] Synthetic quartz glass cavity

[0047] One embodiment of the present invention is a synthetic quartz glass cavity suitable for being connected to a substrate on which an optical device is mounted so that the device can be accommodated in the cavity. The cavity has an inner surface consisting of a surface portion opposite to an active surface of the optical device and a remaining surface portion, the opposite surface portion being a mirror surface and the remaining surface portion being a rough surface.

[0048] Figure 1 and 2 An exemplary synthetic quartz glass cavity 1 is illustrated. Figure 1 is a plan view of the cavity 1, and Figure 2 It is taken from Figure 1 The cross-sectional view of the line II-II in FIG. The cavity 1 has an inverted recess or rectangular box shape in cross section and has a top wall 2, a side wall 3 and a bottom opening 4. The top wall 2 and the side wall 3 are formed of synthetic quartz glass.

[0049] like Figure 2 As best shown in FIG. 1 , the inner surface of the cavity 1 is composed of a surface portion (i.e., the inner surface 2a of the top wall 2) opposite to the active surface of the optical device and a remaining surface portion (i.e., the inner surface 3a of the side wall 3), the opposite surface portion 2a being a mirror surface and the remaining surface portion 3a being a rough surface. Since the surface portion 2a opposite to the active surface of the optical device is a surface that transmits light, the surface portion 2a is a mirror surface in order to improve the light extraction efficiency. From the same point of view, the outer surface 2b of the top wall 2 is preferably also a mirror surface. The remaining surface portion of the inner surface of the cavity except the inner surface of the top wall (i.e., the inner surface 3a of the side wall 3) is a rough surface so that light cannot escape from any surface portion except the surface opposite to the active surface of the optical device, i.e., the inner surface 3a can act as a pseudo-reflector for internal reflection. Without particular limitation, the outer surface 3b of the side wall 3 can be a rough surface or a mirror surface.

[0050] From the viewpoint of improving the extraction efficiency of light from the opposite surface, the rough surface of the cavity wall preferably has a surface roughness (Ra) of 0.1-0.5 μm, more preferably 0.1-0.4 μm, and the mirror surface of the cavity preferably has a surface roughness (Ra) of 0.05-0.4 nm, more preferably 0.05-0.2 nm. It should be noted that the surface roughness (Ra) is measured by a surface roughness measuring instrument such as Surfcom480A (Tokyo Seimitsu Co., Ltd.).

[0051] Assuming that the opening 4 of the cavity 1 providing the entrance for accommodating the optical device has a width or diameter w1, and the inner surface 2a of the top wall 2 of the cavity that transmits light has a width or diameter w2, from the viewpoint of light transmission and extraction efficiency, the ratio of w1:w2 is preferably in the range of 0.8:1.0-1.2:1.0 (or 0.8:1.0-1.0:1.2), and more preferably 0.9:1-1.2:1.0 (or 0.9:1-1.0:1.2).

[0052] As long as the range of ratio w1:w2 is met, the cavity 1 can be a columnar shape with a closed top and a cross-sectional concave shape (or a rectangular box shape) with a bottom opening. A shape that gives a smaller ratio of the width or diameter w1 of the cavity opening to the width or diameter w2 of the inner surface of the top wall is preferred.

[0053] Synthetic quartz glass cavity cover

[0054] Figure 3 In another embodiment of the present invention, a synthetic quartz glass cavity cover 10 is described. The cover 10 is composed of the synthetic quartz glass cavity 1 defined above and an adhesive layer 5 formed on the lower end 3c of the side wall 3 of the cavity. For example, the cavity cover 10 is connected at its adhesive layer 5 to a substrate 6 on which an optical device 7 is mounted to construct an optical device package, wherein the optical device is accommodated in the cavity. An optical device package having a hermetic seal (usually a metal seal) in the form of an adhesive layer 5 is constructed.

[0055] The adhesive layer may be a resin-based adhesive layer containing epoxy resin or silicone resin or a metal-based adhesive layer containing metal or a metal mixture.

[0056] The resin-based adhesive layer is formed of a paste containing a resin and has a network or three-dimensional structure, and can be connected to various materials including a synthetic quartz glass substrate, a ceramic substrate, and a metal substrate.

[0057] The metal-based adhesive layer is formed from a paste containing a metal, preferably selected from the group consisting of gold, silver, copper, palladium, indium, tin and bismuth and mixtures thereof, more preferably one or more of silver, tin, copper and bismuth. The metal alloy is formed by sintering the metal paste.

[0058] The resin or metal-based paste may contain a dispersion medium, which is preferably an organic solvent. As the organic solvent, cycloalkanes with large steric hindrance and low polarity and long-chain alkyl alcohols having 8 to 12 carbon atoms are preferred from the viewpoint of dissolving the resin or preventing the metal particles from being integrated together in the metal paste. The preferred content of the dispersion medium in the resin paste is at least 10% by weight and at most 40% by weight. The preferred content of the dispersion medium in the metal paste is at least 3% by weight, more preferably at least 5% by weight and at most 20% by weight, more preferably at most 15% by weight.

[0059] Synthetic quartz glass is an amorphous material of SiO2. If the quartz glass is connected to the substrate by an adhesive layer of a single metal particle with an ordered crystal structure, the adhesion at the interface between the substrate and the glass is poor. This means that when an adhesive layer of a single metal particle is used as a sealant, it is less water-resistant or less stable to external impacts, thereby causing the rupture of the optical device package. It is believed that the metal paste used to form the metal-based adhesive layer is metal-based, but does not have a crystal structure, so that the disordered atomic arrangement at the nanometer level is flexibly connected to the synthetic quartz glass surface. This establishes a strong connection between the synthetic quartz glass and the adhesive layer, providing water resistance and external impact resistance. Therefore, it is preferred that the metal particles in the metal paste used to form the metal-based adhesive layer exist as nanoparticles. Specifically, the metal particles should preferably have a primary particle size of at least 5nm, more preferably at least 10nm and at most 80nm, more preferably at most 60nm, and even more preferably at most 40nm, as measured by a dynamic light scattering method. The primary particle size of the metal particles can be measured by the same method as the metal particles in the metal paste for forming a metal film or a metal compound film, for example, by a particle size analyzer ELSZ-2000ZS or a light scattering spectrophotometer DLS-8000 series (Otsuka Electronics Co., Ltd.).

[0060] The thickness of the adhesive layer can be set to be suitable for a specific type of optical device package and is not particularly limited. Preferably, the adhesive layer has a thickness of at least 10 μm, more preferably at least 20 μm and at most 70 μm, more preferably at most 60 μm, even more preferably at most 50 μm, as measured by a microscope such as VHX-6000 (Keyence Corp.).

[0061] Considering the connection process in which pressure is often applied when the cavity cover is aligned and connected to the substrate, the width of the adhesive layer is preferably smaller than the width of the lower end of the side wall of the cavity piece, particularly 80 to 95%, more particularly 85 to 95%, and even more particularly 90 to 95% of the width of the lower end of the side wall of the cavity piece.

[0062] In one embodiment, a resin or metal-based paste forming an adhesive layer is applied to the lower end of the side wall of the cavity immediately before the cavity is connected to the substrate. In another embodiment, an adhesive layer is pre-formed on the lower end of the side wall of the cavity to construct the cavity cover. In either embodiment, the resin or metal-based paste on the lower end of the side wall of the cavity is preferably heated to the B stage, that is, heated to a degree that the paste cannot flow away.

[0063] Method for producing a synthetic quartz glass cavity

[0064] A further embodiment of the present invention is a method for producing a synthetic quartz glass cavity, comprising the following steps:

[0065] drilling the synthetic quartz glass substrate at a plurality of locations to form a plurality of through holes,

[0066] placing another synthetic quartz glass substrate on the perforated synthetic quartz glass substrate to form a laminate, the other synthetic quartz glass substrate having a mirror surface opposite to the perforated synthetic quartz glass substrate, and

[0067] The laminate is cut into a plurality of separate synthetic quartz glass cavity pieces at locations between adjacent through holes.

[0068] Glass substrate

[0069] The initial and other synthetic quartz glass substrates are not particularly limited in shape. For example, a circular synthetic quartz glass substrate having a diameter of 4-8 inches (101.6-203.2 mm) or a rectangular synthetic quartz glass substrate having a side of 4-6 inches (101.6-152.4 mm) can be used. In view of misalignment and strength when two substrates are connected to form a laminate, the initial or other synthetic quartz glass substrate preferably has a surface roughness (Ra) of 0.05-1.0 nm, more preferably 0.05-0.5 nm. The thickness of the initial or other synthetic quartz glass substrate is preferably equal to the desired depth of the cavity.

[0070] drilling

[0071] The step of drilling the starting synthetic quartz glass substrate at a plurality of locations to form a plurality of through holes may be by sandblasting or by using a machining center.

[0072] The sandblasting process is, for example, by using a device having a nozzle that moves horizontally in the X and Y directions across the surface of the starting glass substrate, and injecting abrasive grains to the substrate surface together with an air jet to form a plurality of through holes in the substrate at a plurality of locations. The abrasive grains are preferably aluminum oxide or silicon carbide, but are not limited thereto. The abrasive grains used for sandblasting preferably have a size of #600 to #3000 (or an average grain size of 30-6 μm).

[0073] Specifically, the drilling process may be a process of sandblasting the front surface or the rear surface of the starting substrate, or a process of sandblasting both the front surface and the rear surface of the starting substrate, while gradually changing the size of the abrasive grains and the sandblasting pressure. The process of sandblasting both the front surface and the rear surface of the starting substrate is preferably for the purpose of minimizing or eliminating the difference in opening width or diameter between the front surface and the rear surface of the starting substrate due to the taper of the through hole.

[0074] In the sandblasting process, a film mask having a drilling pattern corresponding to 90-95% of the desired opening width or diameter of the through hole is attached to the surface of the starting substrate (to be perforated) using an adhesive. The material of the film mask is not particularly limited, as long as no residue is left on the substrate at the end of sandblasting. Brittle materials such as ceramics and glass are preferred. The adhesive used herein is generally selected from brittle, easily broken or low-elastic adhesives, such as silica-based adhesives, ceramic adhesives and cement.

[0075] The starting substrate is sandblasted through the film mask, thereby immediately grinding the areas of the substrate not covered by the film mask until through-holes are formed.

[0076] After the through hole is formed, if the ratio of the width or diameter of the through hole on the front surface to the width or diameter of the through hole on the rear surface is outside a predetermined range (w1:w2 ratio of the cavity), appropriate correction is performed by etching to minimize the difference in opening width or diameter between the front surface and the rear surface of the glass substrate caused by the taper.

[0077] The (ground) inner surface of the through hole drilled by sandblasting is a rough surface with a surface roughness (Ra) of preferably 0.1-0.5 μm, more preferably 0.1-0.3 μm. At this point, the moving direction, moving speed and pneumatic pressure of the sandblasting nozzle can be adjusted by a computer control system so that the ground surface can be changed into a rough surface with a predetermined roughness. Specifically, because the pneumatic pressure is interrelated with the abrasive grains and the nozzle-substrate distance, the pneumatic pressure is not set to a fixed value and is adjusted according to the removal rate and the grinding depth. For example, when green silicon carbide (GC) or white aluminum oxide (alundum) (WA) is used as an abrasive grain, the pneumatic pressure is preferably 0.15-0.30 MPa.

[0078] In another embodiment where the drilling step uses a machining center, the process of machining both the front and back surfaces of the glass substrate is preferably for the purpose of minimizing the difference in opening width or diameter between the front and back surfaces of the glass substrate due to the taper of the through hole.

[0079] The machining step uses a machining center or a numerically controlled drill equipped with a diamond grinding wheel, and rotates and moves the diamond grinding wheel under such machining conditions that cracking, cracking or falling off of the machined surface of the glass substrate is not caused, thereby drilling a through hole having a predetermined size or depth. Specifically, the machining is performed by using a grinding wheel having electroplated or metal-bonded diamond or CBN abrasive grains, and rotating the grinding wheel at a shaft speed of preferably 100-60000 rpm, more preferably 1000-40000 rpm and a grinding rate of preferably 1-10000 mm / min, more preferably 10-1000 mm / min.

[0080] Lamination of synthetic quartz glass substrates

[0081] The drilling step is followed by a step of connecting the second synthetic quartz glass substrate and the first synthetic quartz glass substrate having the plurality of through holes to form a laminate.

[0082] From the viewpoint of deflection of the glass substrate, the second glass substrate to be connected to the first glass substrate has preferably the same size as the first glass substrate and preferably a thickness of at least 0.2 mm, more preferably at least 0.3 mm. The upper limit of the thickness of the second glass substrate is not critical and from the viewpoint of light extraction efficiency, it is preferably at most 0.6 mm.

[0083] The surface of the second glass substrate connected to the first glass substrate is a mirror surface at least in the area corresponding to the through hole in the glass substrate of the drilled hole. Preferably, the surface of the second glass substrate connected to the first glass substrate is a mirror surface. The mirror surface preferably has a surface roughness (Ra) of at most 0.3 nm, more preferably at most 0.2 mm and at least 0.05 nm. Most preferably, both the front surface and the back surface of the second glass substrate are mirror surfaces.

[0084] The step of connecting the first glass substrate to the second glass substrate may include placing the two glass substrates in alignment (if the two glass substrates have the same size) and connecting them together. Although no load needs to be applied to the glass substrates, a light load of about 50 gf or less may be applied to prevent misalignment of the connection.

[0085] Once the second (undrilled) glass substrate is placed on the first (drilled) glass substrate having through holes, the laminate is placed in a furnace where it is preferably heated at 1000-1200° C. for 2-4 hours to firmly join the two glass substrates together.

[0086] After joining, if necessary, the second (undrilled) glass substrate may be polished on one surface until the final glass cavity top wall thickness reaches the desired value.

[0087] Segmentation

[0088] The lamination step is followed by a step of cutting the laminate into a plurality of individual synthetic quartz glass cavities.

[0089] The laminate or the connected glass substrates are cut into a plurality of discrete cavities (ie, divided) at locations between adjacent through holes by, for example, a dicing saw. Preferably, the laminate is cut into a plurality of 1-5 mm square components.

[0090] Considering the subsequent step of forming the adhesive layer, it is preferred to send the diced laminate to the subsequent step while keeping the dicing tape attached to the second (undrilled) glass substrate, ie, the top wall outer surface of the glass cavity.

[0091] Method for manufacturing a cavity cover

[0092] Yet another embodiment of the present invention is a method for manufacturing a cavity cover, including the step of forming an adhesive layer on a lower end of a side wall of a cavity member.

[0093] The adhesive layer may be a resin or metal-based adhesive layer. The resin or metal-based adhesive layer may be formed by providing a paste containing a resin and a dispersion medium or a paste containing at least one element selected from gold, silver, copper, palladium, indium, tin and bismuth and a dispersion medium, and applying the paste to the lower end of the side wall of the cavity by dispersion, screen printing, stamping or inkjet printing. When it is desired to form the adhesive layer with high precision in a single step, a screen printing technique that can apply the adhesive paste in one pass is preferred.

[0094] The resin or metal-based paste forming the adhesive layer is as described above, and the thickness and width of the adhesive layer are also as described above.

[0095] The metal-based paste can be converted to the B stage by heating at a temperature lower than the curing temperature. From the viewpoint of heat resistance of the device to be sealed in the cavity, the metal-based paste forming the adhesive layer is preferably cured at a temperature of 100-350°C, more preferably 100-300°C, and even more preferably 150-300°C.

[0096] The synthetic quartz glass cavity cover thus obtained can be used to seal various optical devices. In particular, when synthetic quartz glass that transmits light with a wavelength of 280 nm or less in a stable manner is used as a cavity member, the cavity cover can be used with an optical device capable of emitting or receiving UV-C light (wavelength 240-300 nm) or DUV light (wavelength 170-240 nm).

[0097] Optical device packaging and manufacturing

[0098] Another embodiment of the present invention is an optical device package comprising a cavity cover (2, 3, 5) and a substrate 6 having an optical device 7 mounted thereon, such as Figure 4 The cavity cover is arranged on the substrate 6 and connected thereto via the adhesive layer 5 so that the device 7 is accommodated in the cavity.

[0099] The optical device is selected from a light emitting device such as UV-LED, KrF excimer laser and ArF excimer laser, and a light receiving device such as a flame sensor.

[0100] The substrate on which the optical device is mounted is generally selected from an alumina-based ceramic substrate, an aluminum nitride-based ceramic substrate and a copper plate. Also included are the aforementioned substrates having a metal layer of gold, silver, platinum or chromium or a metal compound layer of chromium nitride, titanium oxide, etc. on their surfaces. Respectively, when a reflective material is coated on the inner surface of the side wall of the cavity, the coating can act as a mirror.

[0101] An optical device package is manufactured by placing a cavity cover on a substrate having an optical device mounted thereon, aligning them, contacting an adhesive layer with the substrate, and attaching the cavity cover to the substrate to construct a package accommodating the optical device in a cavity.

[0102] Preferably, if necessary, the cavity cover and the substrate on which the optical device is mounted are heated in a stacked state. From the viewpoint of heat resistance of the optical device, the temperature of the heat treatment or the curing temperature is preferably 150-330° C., and the time of the heat treatment is preferably 1-60 minutes, more preferably 1-30 minutes. Also preferably, pressure is applied simultaneously. The atmosphere used for connecting or heating the connecting portion is an air atmosphere or an inert gas atmosphere such as nitrogen. When the cavity cover has an adhesive layer of a metal-based paste in the B stage, heating causes the metal-based adhesive layer to be compressed so that the metal particles therein are tightly connected, thereby establishing a more airtight seal.

[0103] Example

[0104] Examples of the invention are given below by way of illustration and not by way of limitation.

[0105] Example 1

[0106] A synthetic quartz glass wafer or substrate (diameter 101.6 mm, thickness 0.4 mm) having a front surface and a rear surface (Ra = 0.3 nm) that are mirror surfaces is provided as a first substrate. A film mask having a pattern including a 0.8 mm square aperture is attached to the front surface of the glass substrate. The glass substrate is drilled on the entire surface of the glass substrate by sandblasting to form a through hole. For sandblasting, abrasive grains WA#1200 (Showa Denko KK) are sprayed at a pneumatic pressure of 0.22 MPa.

[0107] At the end of the sandblasting, the through-hole had a square opening of 0.82 mm in width on the front surface of the substrate and a square opening of 0.81 mm in width on the rear surface of the substrate (w1:w2=1.0:1.0).

[0108] Another synthetic quartz glass substrate (diameter 101.6 mm, thickness 0.3 mm) having front and rear surfaces that were mirror surfaces (Ra = 0.13 nm) was connected to the first substrate having a plurality of through holes, and the two glass substrates were connected together by keeping them in an electric furnace at 1100° C. for 2 hours.

[0109] The glass substrate laminate was cut into a plurality of 1.2 mm square parts (synthetic quartz glass cavity parts) at positions between the through holes by a dicing saw.

[0110] A silicone resin adhesive (KER-3000-M2, Shin-Etsu Chemical Co., Ltd.) was applied to the lower end of the side wall of the cavity using a dispenser to form a linear coating having a width of 250 μm and a thickness of 15-20 μm, thereby obtaining a synthetic quartz glass cavity cover.

[0111] A cavity cover was provided on the alumina-based ceramic substrate on which the flame sensor was mounted, temporarily connected under a load of 150 gf / package, and heat-connected in a drying furnace at 200° C. for 1 hour, thereby completing a light receiving flame sensor package.

[0112] The light receiving flame sensor package was placed near a flame emitting light in the UV region. It was confirmed that the sensor functioned properly by capturing light from the flame through the synthetic quartz glass, and no peeling of the adhesive layer due to stress of the glass cavity or the alumina-based ceramic substrate was observed anywhere. The package showed satisfactory performance.

[0113] Example 2

[0114] A synthetic quartz glass wafer or substrate (diameter 152.4 mm, thickness 0.3 mm) having a front surface (Ra = 0.25 nm) that is a mirror surface is provided as a first substrate. Using a machining center, the glass substrate is drilled over the entire surface of the glass substrate. The machining center is equipped with a diamond grinding wheel, which operates at an axis speed of 20,000 rpm and a grinding rate of 50 mm / min. In this way, a plurality of through holes are formed in the glass substrate. The openings on the front and rear surfaces of the glass substrate both have a diameter of 2.52 mm.

[0115] Another synthetic quartz glass substrate (diameter 152.4 mm, thickness 0.3 mm) having front and rear surfaces that were mirror surfaces (Ra = 0.13 nm) was connected to the first substrate having a plurality of through holes, and the two glass substrates were connected together by keeping in an electric furnace at 1050° C. for 4 hours.

[0116] The unperforated glass substrate (forming the top wall) was polished (single-side grinding) on ​​its outer surface until the top wall of the cavity reached a thickness of 0.2 mm.

[0117] The glass substrate laminate was cut into a plurality of 3.5 mm square parts (synthetic quartz glass cavity parts) at positions between the through holes using a dicing saw.

[0118] A metallic glass or alloy (glass transition temperature 300° C.) consisting of 30 wt.% silver, 30 wt.% tin, 25 wt.% bismuth and 15 wt.% copper was coated on the lower end of the side wall of each cavity by screen printing to form a linear coating having a width of 240 μm and a thickness of 15-20 μm, and heated at 100° C. for 25 minutes to obtain a synthetic quartz glass cavity cover having a B-stage metallic glass layer.

[0119] On the gold-plated aluminum nitride substrate, a UV-LED chip capable of emitting light at a wavelength of 285 nm was mounted. The cavity cover and the substrate were connected, and the chip was accommodated in the cavity by heating at 250°C for 10 minutes and applying a load of 1 kgf / package, thereby completing the optical device package.

[0120] The UV-LED chip was activated to emit light having a wavelength of 285 nm for more than 5000 hours. No peeling of the adhesive layer due to stress of the glass cavity or the aluminum nitride substrate was observed anywhere, and no damage to the adhesive layer by the short-wavelength 285 nm light was observed. The short-wavelength optical device package showed satisfactory performance.

[0121] Japanese Patent Application No. 2018-137374 is incorporated herein by reference.

[0122] While some preferred embodiments have been described, numerous modifications and variations are possible in light of the above teachings. It should therefore be appreciated that the invention may be practiced in other ways than as described without departing from the scope of the appended claims.

Claims

1. A synthetic quartz glass cavity, which is suitable for being connected to a substrate on which an optical device is mounted, so that the device can be accommodated in the cavity, The cavity has an inner surface consisting of a surface portion opposite to the active surface of the device and a remaining surface portion, the opposite surface portion being a mirror surface and the remaining surface portion being a rough surface, The mirror surface is used to improve the light extraction efficiency, and the rough surface is used to reflect the light in the cavity.

2. The cavity according to claim 1, having a cross-section in an inverted concave shape, having a top wall, a side wall and a bottom opening, the inner surface of the top wall being a mirror surface and the inner surface of the side wall being a rough surface.

3. The cavity according to claim 2, wherein the top wall has an outer surface that is a mirror surface.

4. The cavity according to claim 2 or 3, wherein the width or diameter of the bottom opening and the width or diameter of the inner surface of the top wall are in a ratio of 0.8:1.0 to 1.2:1.

0. 5 . The cavity according to claim 1 , wherein the rough surface has a surface roughness (Ra) of 0.1-0.5 μm.

6. A cavity cover comprising the synthetic quartz glass cavity member according to any one of claims 1 to 5 and an adhesive layer formed on a portion of the cavity member to connect the substrate. The cavity cover of claim 6 , wherein the adhesive layer is in a B-stage.

8. The cavity cover according to claim 6 or 7, wherein the adhesive layer is a resin-based adhesive layer containing epoxy resin or silicone resin or a metal-based adhesive layer containing metal or a mixture thereof.

9. The cavity cover of claim 8, wherein the metal is selected from the group consisting of gold, silver, copper, palladium, indium, tin and bismuth.

10. An optical device package comprising the cavity cover according to any one of claims 6 to 9 and a substrate on which a light emitting device is mounted.

11. A method for manufacturing a synthetic quartz glass cavity, comprising the following steps: drilling the first synthetic quartz glass substrate at a plurality of locations to form a plurality of through holes, placing a second synthetic quartz glass substrate on the first synthetic quartz glass substrate to form a laminate, the second synthetic quartz glass substrate having a mirror surface opposite to the perforated synthetic quartz glass substrate, and The laminate is cut into a plurality of separate synthetic quartz glass cavity pieces at locations between adjacent through holes.

12. The method according to claim 11, wherein the drilling step is sandblasting or grinding by a machining center.

13. A method for manufacturing a cavity cover, comprising the steps of: The synthetic quartz glass cavity is manufactured by the method according to claim 11 or 12, and A resin or metal-based paste is applied to the lower end of the side wall of the cavity to form a resin or metal-based adhesive layer.

14. The method of claim 13, wherein the adhesive layer is a metal-based adhesive layer, the method further comprising the step of heating the metal-based paste to form a B-stage metal-based adhesive layer.

15. A method for manufacturing an optical device package, comprising the steps of: A cavity cover is manufactured by the method of claim 13 or 14, and The cavity cover is connected at its adhesive layer to the substrate on which the light emitting or receiving device is mounted so that the device can be accommodated in the cavity cover.

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