Cover components and encapsulation

Abstract

The glass cover member (4) comprises: a plate-shaped frame portion (7) and a dome-shaped protrusion (8) protruding from the frame portion (7). The protrusion (8) has an inner surface (8a) and an outer surface (8b). The protrusion (8) comprises: a top (13) and a base portion (11) integrally formed with the frame portion (7). An anti-reflective film (10a) is formed on the inner surface (8a) of the protrusion (8). The value (Ta1 / Ta3) obtained by dividing the thickness (Ta1) of the anti-reflective film (10a) formed on the base (11) of the protrusion (8) by the thickness (Ta1 / Ta3) of the anti-reflective film (10a) formed on the top (13) of the protrusion (8) is 0.75 or more and less than 1.

Description

Cover member and package The present invention relates to a cover member for a package and a package having the cover member. For example, Patent Document 1 discloses a package including: a substrate (substrate) for mounting a light-emitting element (LED element), a dome-shaped cover member (light-transmitting cover) fixed to the substrate so as to cover the light-emitting element, and an adhesive for bonding the substrate and the cover member. In this package, by forming the cover member into a dome shape, a space for accommodating the light-emitting element is ensured between the cover member and the substrate. [Prior Art Documents] [Patent Documents] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-66169 [Problems to be Solved by the Invention] Regarding packages using the above-mentioned dome-shaped cover members, research and development for further improving performance are underway. An object of the present invention is to improve the light extraction efficiency of a cover member used in a package containing a light-emitting element. [Technical Means for Solving the Problem] (1) The present invention was developed to solve the above problems and provides a cover member, which is a glass cover member used in a package containing a light-emitting element, and is characterized in that it includes: a plate-shaped frame portion and a dome-shaped protruding portion protruding from the frame portion. The protruding portion has an inner surface and an outer surface. The protruding portion includes: a top portion and a base portion integrated with the frame portion. An antireflection film is formed on the inner surface of the protruding portion. The value obtained by dividing the thickness of the antireflection film formed on the base portion of the protruding portion by the thickness of the antireflection film formed on the top portion of the protruding portion is 0.75 or more and less than 1. According to this configuration, an antireflection film is formed on the inner surface of the protruding portion of the cover member, and the protruding portion allows light emitted from the light-emitting element to penetrate efficiently. Thereby, the light extraction efficiency of the cover member used in the package can be increased as much as possible. The smaller the thickness of the antireflection film, the lower the antireflection effect. Therefore, by setting the value obtained by dividing the thickness of the antireflection film formed on the base portion of the protruding portion by the thickness of the antireflection film formed on the top portion of the protruding portion to be 0.75 or more and less than 1, the thickness of the antireflection film on the base portion of the protruding portion can be made as close as possible to the thickness of the antireflection film on the top portion of the protruding portion. Therefore, there is no portion where the thickness of the antireflection film is extremely thin on the protruding portion of the cover member. Thereby, the light extraction efficiency of the cover member can be improved. (2) In the cover member described in (1) above, the thickness of the top portion of the protruding portion is thinner than the thickness of the base portion of the protruding portion. According to this configuration, the thickness of the top in the protruding portion of the cover member is thinner than that of the base portion, which can improve the transmittance of the protruding portion. In addition, since the thickness of the base portion of the protruding portion is thicker than that of the top, the strength of the base portion can be made higher than that of the top. Therefore, it is possible to achieve both improved light extraction efficiency and ensured strength of the cover member. (3) In the cover member described in the above (1) or (2), the frame portion has: a first main surface connected to the inner surface of the protruding portion, and a second main surface connected to the outer surface of the protruding portion, and the antireflection film is formed on the first main surface of the frame portion. According to this configuration, the antireflection film formed on the first main surface of the frame portion has the function of relaxing the stress acting on the joint portion when the frame portion is joined to the substrate, so that the cover member can be joined to the substrate of the package without being damaged. (4) In the cover member described in the above (3), a metal layer is formed on the side of the antireflection film formed on the first main surface of the frame portion opposite to the first main surface side. According to this configuration, when forming the bonding material on the cover member, by using this metal layer, the bonding material and the metal layer are well compatible, and as a result, the cover member and the substrate of the package can be properly joined. (5) In the cover member described in any one of the above (1) to (4), the antireflection film includes a hafnium oxide film. If the antireflection film is a hafnium oxide film, when the frame portion is joined to the substrate, the function of relaxing the stress acting on the joint portion can be significantly improved. Therefore, the cover member can be joined to the substrate of the package without being damaged. (6) In the cover member described in any one of the above (1) to (5), a second antireflection film is formed on the outer surface of the protruding portion. According to this configuration, the light extraction efficiency of the cover member can be further improved. (7) In the cover member described in the above (6), the thickness of the second antireflection film formed on the top is thicker than the thickness of the second antireflection film formed on the base portion. (8) In the cover member described in any one of the above (1) to (7), the protruding portion protrudes from the frame portion at a predetermined protruding angle, and the protruding angle of the protruding portion is 10° to 80°. When the protrusion and the sputtering device face each other and particles are sputtered from the sputtering device toward the inner surface of the protrusion to form an antireflection film, an antireflection film with a designed film thickness can be formed on the top of the protrusion. However, if the protrusion angle exceeds 80°, the amount of particles deposited on the base decreases, and it becomes difficult to form an antireflection film with a designed film thickness. In contrast, as long as the protrusion angle is 80° or less, the components of the antireflection film can be efficiently formed even at the base of the protrusion. In this way, an antireflection film with a sufficient thickness can be formed, so that the light extraction efficiency of the protrusion can be improved. Also, if the protrusion angle is less than 10°, it becomes inappropriate from the viewpoint of the accommodation space for encapsulating the light-emitting element. (9) In the lid member described in any one of the above (1) to (8), the protrusion has: an opening formed on the inner surface side, and the ratio (L / H) of the opening length L of the opening to the protrusion height H of the protrusion is 1.2 to 8. When the protrusion and the sputtering device face each other and particles are sputtered from the sputtering device toward the inner surface of the protrusion to form an antireflection film, an antireflection film with a designed film thickness can be formed on the top of the protrusion. However, if the ratio (L / H) is less than 1.2, the amount of particles deposited on the base decreases, and it becomes difficult to form an antireflection film with a designed film thickness. In contrast, as long as the ratio (L / H) is 1.2 or more, the components of the antireflection film can be efficiently formed even at the base of the protrusion. In this way, an antireflection film with a sufficient thickness can be formed, so that the light extraction efficiency of the protrusion can be improved. Also, if the ratio (L / H) exceeds 8, it becomes inappropriate from the viewpoint of the accommodation space for encapsulating the light-emitting element. (10) In the lid member described in the above (9), the opening is formed in a quadrangular shape. (11) In the lid member described in any one of the above (1) to (10), the inner surface has: a first curved surface connected to the first main surface of the frame portion and protruding toward the inside of the protrusion, a second curved surface protruding toward the outside of the protrusion, and an inflection point located between the first curved surface and the second curved surface. According to this configuration, the shape of the lid member becomes smooth, and it can have impact resistance against the outside. Also, in the case of a lid member having such an inflection point, since the light extraction efficiency of the protrusion may decrease, by prescribing the above-mentioned protrusion angle and the ratio (L / H) of the opening length L of the opening to the protrusion height H of the protrusion, the light extraction efficiency of the protrusion can be improved. (12) The present invention was developed to solve the above problems, and provides a package including: a light-emitting element, a substrate supporting the light-emitting element, and a lid member described in any one of the above (1) to (11). According to this configuration, an antireflection film is formed on the inner surface of the protruding portion of the lid member, and the protruding portion allows the light emitted from the light-emitting element to penetrate with good efficiency. Thereby, the light extraction efficiency of the package can be increased as much as possible. The smaller the thickness of the antireflection film, the lower the antireflection effect. Then, the value obtained by dividing the thickness of the antireflection film formed on the base of the protruding portion by the thickness of the antireflection film formed on the top of the protruding portion is set to be 0.75 or more and less than 1, so that the thickness of the antireflection film at the base of the protruding portion can be made as close as possible to the thickness of the antireflection film at the top of the protruding portion. Therefore, there is no portion where the thickness of the antireflection film is extremely thin in the protruding portion of the lid member. Thereby, the light extraction efficiency of the package can be increased. [Effect of the Invention] According to the present invention, the light extraction efficiency of the lid member used in the package containing the light-emitting element can be increased. Hereinafter, a mode for implementing the present invention will be described with reference to the drawings. FIGS. 1 to 20 show an embodiment of the lid member and the package of the present invention. As shown in FIGS. 1 and 2, the package 1 includes: a substrate 2, a light-emitting element 3 supported by the substrate 2, a lid member 4 covering the substrate 2 and the light-emitting element 3, and a sealing portion 5 that hermetically joins the substrate 2 and the lid member 4. FIGS. 3 and 4 show the substrate 2 before being joined to the lid member 4. The substrate 2 has: a first main surface 2a that supports the light-emitting element 3, a second main surface 2b located on the opposite side of the first main surface 2a, and a metal layer 6 formed on the first main surface 2a. Examples of the material of the substrate 2 include ceramics such as aluminum nitride, alumina, silicon carbide, and silicon nitride, glass ceramics obtained by mixing and sintering these ceramics and glass powder, alloys such as Fe-Ni-Co alloy, Cu-W alloy, and Kovar (registered trademark), etc. As shown in FIG. 4, the metal layer 6 has a frame shape surrounding the light-emitting element 3. The metal layer 6 is formed in a rectangular shape, but is not limited to this shape. The metal layer 6 may be formed in a circular shape so as to surround the light-emitting element 3, for example. The metal layer 6 includes a total of three layers, namely a base layer, an intermediate layer, and a surface layer, in order from the first main surface 2a side. Examples of the metal for the base layer include Cr, Ta, W, Ti, Mo, Ni, Pt, etc. Examples of the metal for the intermediate layer include Ni, Pt, Pd, etc. Examples of the metal for the surface layer include Au, Sn, Ag, Ni, Pt, etc. The metal for the metal layer 6 can be a single metal or an alloy. Examples of the method of forming the metal layer 6 on the first main surface 2a of the substrate 2 include film-forming methods such as sputtering method, vacuum evaporation method, vacuum evaporation method using ion assistance or ion plating, and CVD method. The light-emitting element 3 is fixed on the first main surface 2a of the substrate 2. In the present embodiment, the package 1 using an LED for ultraviolet irradiation is illustrated as the light-emitting element 3, but the light-emitting element 3 of the present invention is not limited to the present embodiment, and an infrared LED or a visible light LED can be adopted. Figs. 5 to 7 show the cover member 4 before being joined to the substrate 2. The cover member 4 is manufactured by forming a part of plate glass. The glass used for the cover member 4 is preferably alkali-free glass, borosilicate glass, aluminosilicate glass, quartz glass, or crystallized glass. If it is alkali-free glass, borosilicate glass, or aluminosilicate glass, high transmittance and high workability during molding can be achieved at the same time. If it is quartz glass, the workability during molding can be maintained, and it has a significantly high transmittance in the ultraviolet region. If it is crystallized glass, high transmittance and high fracture strength can be achieved at the same time. When the glass is borosilicate glass, aluminosilicate glass, or alkali-free glass, as the glass composition, in terms of mass%, it preferably contains SiO 2 : 50 to 75%, Al 2 O 3 : 1 to 25%, B 2 O 3 : 0 to 30%, Li 2 O + Na 2 O + K 2 O: 0 to 20%, MgO + CaO + SrO + BaO: 0 to 20%. As long as the composition of the glass is within the above composition range, it belongs to these glass systems. In the case of crystallized glass, low thermal expansion crystallized glass is preferred. As the glass composition, in terms of mass%, it contains SiO 2 : 60 to 80%, Al 2 O 3 : 3 to 30%, Li 2 O + Na 2 O + K 2O: 1 to 20%, MgO + CaO + SrO + BaO: 5 to 20%, and β - quartz solid solution or β - spodumene precipitates in the form of crystals from inside the glass. The low thermal expansion here means that in the temperature range of 30 to 300 °C, the value of the thermal expansion coefficient is - 10×10 -7 / °C to 20×10 -7 / °C. As shown in FIGS. 2 and 5, the cover member 4 includes: a plate - shaped frame portion 7, a dome - shaped protruding portion 8 protruding from the frame portion 7, a connecting portion 9 for connecting the frame portion 7 and the protruding portion 8, a first antireflection film 10a, and a second antireflection film 10b. The frame portion 7 has a certain thickness, for example, but is not limited to this aspect. The thickness of the frame portion 7 is, for example, 0.2 mm to 2 mm. The frame portion 7 has: a first main surface 7a and a second main surface 7b located on the opposite side of the first main surface 7a. The surface roughness (arithmetic mean roughness) Ra of the first main surface 7a is preferably 1 nm or less, more preferably 0.5 nm or less, and even more preferably 0.3 nm or less. The surface roughness Ra of the second main surface 7b is preferably 1 nm or less, more preferably 0.5 nm or less, and even more preferably 0.3 nm or less. The protruding portion 8 is used to form a receiving space for the light - emitting element 3 together with the first main surface 2a of the substrate 2. The protruding portion 8 is formed at the central position of the frame portion 7, but is not limited to this aspect. The protruding portion 8 has: an inner surface 8a formed as a concave - shaped curved surface, an outer surface 8b formed as a convex - shaped curved surface, and an opening 8c formed on the inner surface 8a side. The protruding portion 8 further includes a base portion 11, an intermediate portion 12, and a top portion 13. The base portion 11 is integrally formed with the connecting portion 9. The intermediate portion 12 is located between the base portion 11 and the top portion 13. The base portion 11 of the protruding portion 8 is defined as follows. As shown in FIG. 2, draw a normal line (hereinafter referred to as the "first line") L1 of the top portion 13, and further draw a straight line (hereinafter referred to as the "second line") L2 along the second main surface 7b of the frame portion 7. Divide the portion of the protruding portion 8 from the intersection point P2 of the first line L1 and the inner surface 8a of the protruding portion 8 to the intersection point P3 of the second line L2 and the inner surface 8a of the protruding portion 8 into four equal parts in a sectional view. That is, draw straight lines L3 - L5 (hereinafter referred to as: the third line L3, the fourth line L4, and the fifth line L5) from the intersection point P1 of the first line L1 and the second line L2 in such a way as to divide the portion of the protruding portion 8 from the intersection point P2 to the intersection point P3 into four equal parts. The portions divided by the respective straight lines L3 - L5 are respectively referred to as the first portion, the second portion, the third portion, and the fourth portion from the intersection point P2 toward the intersection point P1. The base portion 11 is the boundary portion between the first part and the second part. That is, the base portion 11 is the portion where the third line L3 intersects the protruding portion 8. The portion where the third line L3 intersects the inner surface 8a of the protruding portion 8 is referred to as the first base portion 11a, and the portion where the third line L3 intersects the outer surface 8b of the protruding portion 8 is referred to as the second base portion 11b. As shown in FIG. 5, when a straight line (hereinafter referred to as the "sixth line") L6 forming an angle of 60° with the second line L2 is drawn from the intersection point P1 of the first line L1 and the second line L2, the middle portion 12 is the portion where the sixth line L6 intersects the protruding portion 8. Hereinafter, the distance from the intersection point P2 between the first line L1 and the inner surface 8a of the protruding portion 8 to the above intersection point P1 is referred to as the protruding height of the protruding portion 8, and is represented by the symbol H. The protruding height H of the protruding portion 8 is, for example, 0.5 mm to 80 mm. The outer diameter D of the protruding portion 8 is the diameter of the set circle of the points located at the second base portion 11b, for example, 2 mm to 150 mm. As shown in FIG. 5, the thickness of the protruding portion 8 gradually becomes thinner from the base portion 11 toward the top portion 13. Therefore, the thickness Tmin of the top portion 13 is thinner than the thickness (the distance between the first base portion 11a and the second base portion 11b) Tmax of the base portion 11. The thickness Tmax of the base portion 11 is, for example, 0.19 mm to 1.9 mm. The thickness Tmin of the top portion 13 is, for example, 0.15 mm to 1.0 mm. The ratio (Tmin / Tmax) of the thickness Tmax of the base portion 11 to the thickness Tmin of the top portion 13 is preferably 0.08 to 0.9, more preferably 0.1 to 0.8, and even more preferably 0.2 to 0.5. As shown in FIG. 5, the protruding portion 8 protrudes from the frame portion 7 at a predetermined protruding angle θ. The protruding angle θ is defined as follows. A straight line (hereinafter referred to as the "seventh line") L7 parallel to the second line L2 is drawn from the point P4 at the height position of half (H / 2) of the protruding height H located on the first line L1, and the intersection point of the seventh line L7 and the inner surface 8a of the protruding portion 8 is referred to as P5. A straight line (hereinafter referred to as the "eighth line") L8 passing through the intersection point P3 and the intersection point P5 is drawn, and the angle (acute angle) formed by the eighth line L8 and the ninth line L9 drawn along the first main surface 7a of the frame portion 7 is referred to as the protruding angle θ. In the present embodiment, the protruding angle θ is preferably 10° to 80°, more preferably 20° to 70°, and even more preferably 20° or more and less than 40°. The inner surface 8a and the outer surface 8b of the protruding portion 8 are configured as continuous curved surfaces from the base portion 11 to the top portion 13. The surface roughness Ra of the inner surface 8a is preferably 1 nm or less, more preferably 0.5 nm or less, and even more preferably 0.3 nm or less. The surface roughness Ra of the outer surface 8b is preferably 1 nm or less, more preferably 0.5 nm or less, and even more preferably 0.3 nm or less. The opening 8c of the protrusion 8 is used to insert the light-emitting element 3 provided on the base body 2 into the inside of the protrusion 8 when the lid member 4 is fixed to the base body 2. As shown in FIG. 7, the opening 8c of the protrusion 8 is formed in a circular shape, but is not limited to this shape. The opening length L of the opening 8c (the diameter of the opening 8c in the present embodiment) is, for example, 1.5 mm to 80 mm. The ratio (L / H) of the opening length L of the opening 8c to the protruding height H of the protrusion 8 is preferably 1.2 or more, 1.6 or more, 2.1 or more, and preferably 8 or less, 5 or less, 3 or less. As shown in FIGS. 2 and 5, the connecting portion 9 has a bent shape for connecting the base portion 11 and the frame portion 7. The connecting portion 9 has: a first curved surface 9a that connects the first main surface 7a of the frame portion 7 and the inner surface 8a of the protrusion 8, and a second curved surface 9b that connects the outer surface 8b of the protrusion 8 and the second main surface 7b of the frame portion 7. The radius of curvature of the first curved surface 9a is larger than the radius of curvature of the second curved surface 9b. The radius of curvature of the first curved surface 9a is preferably 0.5 mm or more, 1 mm or more, and preferably 5 mm or less, 4 mm or less. The radius of curvature of the second curved surface 9b is preferably 0.5 mm or more, 1 mm or more, and preferably 5 mm or less, 4 mm or less. The surface roughness Ra of the first curved surface 9a is preferably 1.0 nm or less, more preferably 0.5 nm or less, and still more preferably 0.3 nm or less. The surface roughness Ra of the second curved surface 9b is preferably 1 nm or less, more preferably 0.5 nm or less, and still more preferably 0.3 nm or less. The first antireflection film 10a is formed on the inner surface 8a of the protrusion 8 and the first main surface 7a of the frame portion 7. The first antireflection film 10a has, for example, a multilayer film structure, and the multilayer film structure alternately contains a silicon oxide film (SiO 2 ) as the first film and a hafnium oxide film (HfO 2 ) as the second film. As shown in FIG. 6, a portion (hereinafter referred to as the "antireflection portion") 10a1 of the first antireflection film 10a formed on the inner surface 8a of the protrusion 8 is configured such that the film thickness gradually becomes thinner as it goes from the top 13 of the protrusion 8 toward the base 11. That is, in the antireflection portion 10a1, the thickness Ta3 of the portion formed at the top 13 is the thickest, and the thickness Ta1 of the portion formed at the base 11 is thinner than the thickness Ta3 of the portion formed at the top 13. The thickness Ta1 (refer to FIG. 6) of the first antireflection film 10a located at the base 11 of the protrusion 8 is preferably 0.12 μm to 0.64 μm. The thickness Ta2 of the first antireflection film 10a located at the middle part 12 of the protrusion 8 is preferably 0.14 μm to 0.72 μm. The thickness Ta3 of the first antireflection film 10a located at the top 13 of the protrusion 8 is preferably 0.15 μm to 0.8 μm. The value (Ta1 / Ta3) obtained by dividing the thickness Ta1 of the first antireflection film 10a formed at the base 11 of the protrusion 8 by the thickness Ta3 of the first antireflection film 10a formed at the top 13 of the protrusion 8 is preferably 0.75 or more and less than 1, more preferably 0.85 to 0.95. The antireflection effect of the first antireflection film 10a decreases as the thickness deviates more from the design value. Thus, by setting the value (Ta1 / Ta3) obtained by dividing the thickness Ta1 of the first antireflection film 10a formed at the base 11 of the protrusion 8 by the thickness Ta3 of the first antireflection film 10a formed at the top 13 of the protrusion 8 to be 0.75 or more and less than 1, the thickness Ta1 of the first antireflection film 10a formed at the base 11 of the protrusion 8 can be made as close as possible to the thickness Ta3 of the first antireflection film 10a formed at the top 13 of the protrusion 8. Therefore, there is no part in the protrusion 8 of the cover member 4 where the thickness of the first antireflection film 10a is extremely thin. In this way, the light extraction efficiency of the cover member 4 can be improved. The part (hereinafter referred to as "buffer part") 10a2 of the first antireflection film 10a formed on the first main surface 7a of the frame part 7 has a certain film thickness. In addition to the function of preventing ultraviolet reflection, the buffer part 10a2 also has the function of relaxing the stress acting on the frame part 7 when the cover member 4 is joined to the substrate 2. The second antireflection film 10b is formed on the outer surface 8b of the protrusion 8 and the second main surface 7b of the frame part 7. The second antireflection film 10b has, for example, a multilayer film structure, and this multilayer film structure alternately contains a silicon oxide film (SiO 2 ) as the first film and a hafnium oxide film (HfO 2 ) as the second film. The part (hereinafter referred to as "antireflection part") 10b1 of the second antireflection film 10b formed on the outer surface 8b of the protrusion 8 is configured such that its film thickness gradually becomes thinner as it goes from the top 13 towards the base 11. That is, in the antireflection part 10b1, the thickness Tb3 of the part formed at the top 13 is the thickest, and the thickness Tb1 of the part formed at the base 11 is thinner than the thickness Tb3 of the part formed at the top 13. The thickness Tb1 of the second antireflection film 10b located at the base 11 of the protrusion 8 is preferably 0.12 μm to 0.64 μm. The thickness Tb2 of the second antireflection film 10b located at the middle part 12 of the protrusion 8 is preferably 0.14 μm to 0.72 μm. The thickness Tb3 of the second antireflection film 10b located at the top 13 of the protrusion 8 is preferably 0.15 μm to 0.8 μm. The value (Tb1 / Tb3) obtained by dividing the thickness Tb1 of the second antireflection film 10b formed at the base 11 of the protrusion 8 by the thickness Tb3 of the second antireflection film 10b formed at the top 13 of the protrusion 8 is preferably 0.75 or more and less than 1, more preferably 0.85 to 0.95. The smaller the thickness of the second antireflection film 10b, the lower the antireflection effect. Thus, by setting the value (Tb1 / Tb3) obtained by dividing the thickness Tb1 of the second antireflection film 10b formed at the base 11 of the protrusion 8 by the thickness Tb3 of the second antireflection film 10b formed at the top 13 of the protrusion 8 to be 0.75 or more and less than 1, the thickness Tb1 of the second antireflection film 19b at the base 11 of the protrusion 8 can be made as close as possible to the thickness of the second antireflection film Tb3 at the top 13 of the protrusion 8. Therefore, there is no part with an extremely thin thickness of the second antireflection film 10b in the protrusion 8 of the cover member 4. In this way, the light extraction efficiency of the cover member 4 can be improved. Also, when the light extraction efficiency is sufficient, it is not necessary to form the second antireflection film 10b. However, when using glass with weak weather resistance such as borosilicate glass as the cover member, the cover member 4 may be deteriorated due to the external environment, resulting in a reduction in the light extraction efficiency. In this case, instead of forming the second antireflection film 10b on the cover member 4, SiO 2 film or Al 2 O 3 film can be formed as a film with weather resistance. Also, SiO 2 film or Al 2 O 3 film can be formed as a film with weather resistance in the form of being laminated on the second antireflection film 10b. As shown in FIGS. 2, 5, and 7, a metal layer 14 and a joint portion 15 are formed in the buffer portion 10a2 of the first antireflection film 10a. The Young's modulus of the buffer portion 10a2 is preferably 250 GPa or less, more preferably 200 GPa or less, still more preferably 150 GPa or less, and particularly preferably 100 GPa or less. By defining the upper limit in this way, the buffering property of the buffer portion 10a2 can be improved, and the effect of relaxing the stress generated by the difference in the thermal expansion coefficients of the joint portion 15 and the cover member 4 (frame portion 7) can be obtained. Also, the thermal expansion coefficient of the frame portion 7 is smaller than that of the joint portion 15. Also, the thermal expansion coefficient of the frame portion 7 is smaller than that of the substrate 2. The thickness of the buffer portion 10a2 is preferably 0.1 μm or more and 0.2 μm or more, and more preferably 1 μm or less and 0.8 μm or less. By defining the lower limit in this way, the buffering property of the buffer portion 10a2 can be further improved, and the effect of relaxing the stress generated by the difference in the thermal expansion coefficients of the joint portion 15 and the cover member 4 (frame portion 7) can be obtained. Also, by defining the upper limit in this way, the manufacturing cost of the buffer portion 10a2 can be reduced. As shown in FIGS. 5 and 7, the metal layer 14 is formed to overlap the buffer portion 10a2. The metal layer 14 is formed on the surface of the buffer portion 10a2 opposite to the surface in contact with the first main surface 7a of the frame portion 7. As shown in FIG. 7, the metal layer 14 has a rectangular frame shape corresponding to the shape of the metal layer 6 of the substrate 2. The shape of the metal layer 14 is not limited to this embodiment. The metal layer 14 may also have various other frame shapes such as a circular shape. The metal layer 14 includes a base layer, an intermediate layer, and a surface layer in this order from the buffer portion 10a2 side. Examples of the metal for the base layer include Cr, Ta, W, Ti, Mo, Ni, Pt, etc. When Cr is used for the base layer, the Young's modulus of the base layer is preferably 279 GPa or less. Examples of the metal for the intermediate layer include Ni, Pt, Pd, etc. Examples of the metal for the surface layer include Au, Sn, Ag, Ni, Pt, etc. The metal for the metal layer 14 may be a single metal or an alloy. As shown in FIGS. 5 and 7, the joint portion 15 is formed in a layered manner so as to overlap the metal layer 14. As shown in FIG. 5, the joint portion 15 contacts the portion of the metal layer 14 opposite to the portion in contact with the buffer portion 10a2. As shown in FIG. 7, the joint portion 15 has a rectangular frame shape corresponding to the shapes of the buffer portion 10a2 and the metal layer 14. The shape of the joint portion 15 is not limited to this embodiment and may also be various other frame shapes such as a circular shape. The joint portion 15 is composed of a metal-based joining material. As the metal-based joining material, commercially available soldering materials and brazing materials can be used. Examples of the metal-based joining material include an Au-Sn alloy, a Pb-Sn alloy, an Au-Ge alloy, a Sn-Ni alloy, etc. Also, by making the width of the joint portion 15 narrower than the width of the buffer portion 10a2, the influence of the stress generated by the difference in the thermal expansion coefficients of the joint portion 15 and the lid member 4 can be reduced. In the present embodiment, the case of using an Au-Sn alloy as the metal-based joining material will be described. The sealing portion 5 is formed by integrally joining the metal layer 6 of the base body 2 and the metal layer 14 of the lid member 4 using the joint portion 15. Next, a method for manufacturing the package 1 will be described. This method includes: a preparation process of preparing the base body 2 and the lid member 4, and a joining process of joining the base body 2 and the lid member 4. In the preparation process, after forming the metal layer 6 on the first main surface 2a of the base body 2, the light-emitting element 3 is mounted on the first main surface 2a. Also in the preparation process, after forming the lid member 4 by forming the protruding portion 8 on the plate glass, the first antireflection film 10a is formed on the lid member 4. Then, the metal layer 14 and the joint portion 15 are formed on the buffer portion 10a2 of the first antireflection film 10a. Also, the second antireflection film 10b can be formed on the lid member 4 to further improve the light extraction efficiency. Hereinafter, the process for manufacturing the lid member 4 will be described with reference to FIGS. 8 to 10. This process includes: a forming process, a film-forming process. FIG. 8 shows the forming device used in the forming process. The forming device 16 includes: a support table 17 for supporting the plate glass GS, a shielding member 18 stacked on the plate glass GS supported by the support table 17, and a heat source 19 for causing a part of the plate glass GS to thermally deform in order to form the protruding portion 8 of the lid member 4. Moreover, the forming device 16 includes: a pressing member 20 for pressing the support table 17 and the shielding member 18 in a direction approaching each other, and an external force generating device 21 for applying an external force to a part of the plate glass GS. The support table 17 includes: a support portion 17a for supporting the plate glass GS, and a space portion 17b having an opening surrounded by the supported portion 17a and allowing thermal deformation of a part of the plate glass GS. The support portion 17a of the support table 17 has: a support surface for supporting the main surface of the plate glass GS. In the present embodiment, the opening of the support table 17 has a circular opening edge E1, but may have an opening edge having a shape such as a triangular shape, a quadrangular shape, etc., a polygonal shape, an elliptical shape, etc. The space portion 17b of the support table 17 may be formed by a through hole or may be formed by a recess having an inner bottom. The space portion 17b of the support table 17 is configured to be able to form the entire protruding portion 8 of the lid member 4 in a non-contact state. Examples of the material constituting the support table 17 include metal, ceramic, etc. It is not limited to the above configuration. In order to form the lid member 4 with good shape accuracy, a receiving jig for receiving the plate glass GS may be provided in the space portion 17b. The receiving jig is made of metal or ceramic. As described above, it is preferable to form the entire protruding portion 8 of the lid member 4 in a non-contact state. By improving the quality of the surface of the receiving jig in contact with the plate glass GS (reducing surface roughness and surface undulations), even when using the receiving jig, the lid member 4 can be formed with good accuracy. As shown in FIG. 8, the shielding member 18 has a through hole 18a. Although the inner peripheral edge E2 of the through hole 18a of the shielding member 18 in this embodiment has a circular shape, it may also have an inner peripheral edge of a shape such as a triangular shape, a quadrangular shape, etc., a polygonal shape, an elliptical shape, etc. The support table 17 and the shielding member 18 are configured such that at least a part of the inner peripheral edge E2 of the through hole 18a of the shielding member 18 is disposed more inward than the opening edge E1 of the support table 17. Specifically, the support table 17 and the shielding member 18 are configured such that the entire inner peripheral edge E2 of the through hole 18a of the shielding member 18 is disposed more inward than the opening edge E1 of the support table 17. When the opening area of the opening of the support table 17 is set to 100%, the cross-sectional area of the through hole 18a of the shielding member 18 is preferably 95% or less, more preferably 80% or less. At least a part of the inner peripheral edge E2 of the through hole 18a of the shielding member 18 is preferably disposed more than 1 mm inward from the opening edge E1 of the support table 17, and more preferably disposed more than 3 mm inward. The shielding member 18 is preferably made of a material having a thermal conductivity of 1 [W / (m･K)] or less at 600 °C. As the material constituting the shielding member 18, for example, ceramic is suitable. The thickness of the shielding member 18 is preferably 1 mm or more. The shielding member 18 of this embodiment has an outer shape that covers the entire outer periphery of the plate glass GS. The heat source 19 is arranged to heat the plate glass GS from the side of the shielding member 18. The heat source 19 in this embodiment is a burner that sprays a flame FL toward the plate glass GS. By using a burner, the plate glass GS can be softened relatively quickly. Also, the heating method of the heat source 19 can be, for example, resistance heating, laser heating. Also, the heat source 19 can be constituted by combining heat sources of different heating methods. The pressing member 20 presses the shielding member 18 toward the support table 17, for example. As the pressing mechanism for pressing the pressing member 20, a fluid cylinder, a linear actuator, etc. can be cited, for example. Also, the pressing member 20 can also be configured to press the support table 17 against the fixed shielding member 18. As the external force generating device 21, an exhaust device can be used, for example. The exhaust device discharges the gas existing in the space portion 17b of the support table 17, making the inside of the space portion 17b of the support table 17 negative pressure. Thereby, a part of the plate glass GS is attracted toward the space portion 17b of the support table 17, and the thermal deformation of a part of the plate glass GS can be promoted. As the exhaust device, for example, a pump using a Venturi mechanism is suitable. Also, the external force generating device 21 is not limited to the exhaust device, and it can also be a high-pressure gas generating device that jets high-pressure gas from the shielding member 18 side toward a part of the plate glass GS. Thereby, a part of the plate glass GS is pressurized toward the space portion 17b of the support table 17, and the thermal deformation of a part of the plate glass GS can be promoted. Also, a pump and a high-pressure gas generating device can be used in combination to promote the thermal deformation of a part of the plate glass GS. As shown in FIGS. 8 and 9, in the forming process, first, the shielding member 18 is overlapped and arranged on the plate glass GS supported by the support table 17. In this case, the support table 17 and the shielding member 18 are configured such that at least a part of the inner peripheral edge E2 of the through hole 18a of the shielding member 18 is arranged more inside than the opening edge E1 of the support table 17. Then, the pressing member 20 presses the support table 17 and the shielding member 18 so as to be in contact with each other. Thereby, the positional deviation of the plate glass GS sandwiched between the support table 17 and the shielding member 18 can be suppressed. Next, in the forming process, the plate glass GS is heated from the shielding member 18 side by the heat source 19. Thereby, thermal deformation occurs in a part of the plate glass GS, and the protruding portion 8 is formed. In the above-mentioned forming process, the opening edge E1 of the support table 17 can be covered with the shielding member 18. Thereby, the connecting portion 9 of the cover member 4 can be formed by the thermal deformation of the plate glass GS along the inner peripheral edge E2 of the through hole 18a of the shielding member 18. That is, the connecting portion 9 of the cover member 4 is formed so as not to contact the support table 17. The cover member 4 having the frame portion 7, the protruding portion 8, and the connecting portion 9 is formed by this forming process. Also, in the method of forming the protruding portion 8 of the cover member 4 (manufacturing method of the cover member 4), in addition to the above, the following method can also be adopted, that is, the plate glass GS is placed on a metal or ceramic mold having a concave portion, and the plate glass GS is hot-pressed using a metal or ceramic mold having a convex portion that fits into the aforementioned concave portion. The heating temperature of this hot pressing is preferably above the yield point of the plate glass GS, and more preferably above the softening point of the plate glass GS. When the forming process is completed, the film forming process is carried out. FIG. 10 shows a film forming apparatus used in the film forming process. In the present embodiment, as the film forming apparatus, a sputtering apparatus such as a magnetron sputtering apparatus is exemplified, but the present invention is not limited to this configuration, and a film forming apparatus for performing other physical vapor deposition methods such as vacuum evaporation may also be used. The film forming apparatus 22 includes: a vacuum chamber 23, and targets 24a, 24b for sputtering particles of a film forming material that becomes the antireflection films 10a, 10b. The vacuum chamber 23 houses the targets 24a, 24b inside thereof. The internal space of the vacuum chamber 23 is set to a predetermined degree of vacuum by a vacuum pump. An inert gas such as argon can be supplied into the vacuum chamber 23. The targets 24a, 24b include: a first target 24a for forming the first antireflection film 10a on the cover member 4, and a second target 24b for forming the second antireflection film 10b on the cover member 4. In addition to these targets 24a, 24b, a target (not shown) for forming the metal layer 14 is also disposed in the vacuum chamber 23. The first target 24a and the second target 24b are for forming the first film (SiO 2 ) and the second film (HfO 2 ) of the first antireflection film 10a and the second antireflection film 10b, and include a plurality of targets. As shown in FIG. 10, in the film forming process, the cover member 4 is housed in the vacuum chamber 23. Then, the particles sputtered from the first target 24a are attached to the inner surface 8a of the protruding portion 8 and the first main surface 7a of the frame portion 7 of the cover member 4, thereby forming the first antireflection film 10a. Similarly, the particles sputtered from the second target 24b are attached to the outer surface 8b of the protruding portion 8 and the second main surface 7b of the frame portion 7 of the cover member 4, thereby forming the second antireflection film 10b. The amount of particles attached to the protruding portion 8 of the cover member 4 is the largest at the position of the top portion 13 and gradually decreases toward the base portion 11. Thus, the difference in the amount of particles attached to the protruding portion 8 is due to the influence of the protruding angle θ of the protruding portion 8. After the antireflection films 10a, 10b are formed on the cover member 4, the metal layer 14 is formed so as to overlap with the buffer portion 10a2 of the first antireflection film 10a. The particles sputtered from the target (not shown) for forming the metal layer 14 are attached to the buffer portion 10a2 by the above-described film forming apparatus 22, thereby forming the metal layer 14. The metal layer 14 is formed in a frame shape by allowing the particles to be attached to the buffer portion 10a2 through a shielding member. Next, a joint portion 15 is formed so as to overlap with the metal layer 14. The joint portion 15 is formed, for example, by a process of applying a paste-like metal-based joint material so as to overlap with the metal layer 14 (coating process). Specific examples of the coating process include: a printing method (screen printing method) using a mask, a coating method using a dispenser, and the like. The joint portion 15 is not limited to the above method. For example, a formed body of a metal-based joint material previously formed into a predetermined frame shape may be arranged so as to overlap with the metal layer 14 on the first main surface 7a of the frame portion 7. When the metal-based joint material for the joint portion 15 is applied to the first main surface 7a of the frame portion 7, a heat treatment process for fixing the metal-based joint material to the metal layer 14 on the first main surface 7a is performed. The heat treatment process includes a heating process and a cooling process. In the heating process, the cover member 4 can be heated using a heating device such as a reflow oven to melt the metal-based joint material. The heating process is, for example, implemented in a state where nitrogen gas is filled in the furnace. In the heating process, the cover member 4 is heated to a temperature of 300 °C or higher. In the cooling process, the metal-based joint material in a molten state on the first main surface 7a of the frame portion 7 is cooled and solidified. The cooling process is preferably slow-cooled at a cooling rate of 50 °C / min. In the cooling process, stress is generated in the cover member 4 due to the difference in the thermal expansion coefficients of the frame portion 7 and the joint portion 15, and the buffer portion 10a2 of the first antireflection film 10a can relieve this stress. As shown in FIG. 11, in the joining process, the cover member 4 manufactured through the preparation process is overlapped with the substrate 2. Specifically, the first main surface 7a of the frame portion 7 of the cover member 4 is opposed to the substrate 2, and the joint portion 15 is brought into contact with the metal layer 6 formed on the first main surface 2a of the substrate 2. Next, as shown in FIG. 12, a pressing member 25 is placed on the frame portion 7 of the cover member 4. The pressing member 25 has: a weight 25a and a support member 25b for supporting the weight 25a. For example, metal or ceramic ones are used as the weight 25a and the support member 25b. The support member 25b has: a first support portion 25b1 for supporting the weight 25a and a second support portion 25b2 for supporting the first support portion 25b1. The first support portion 25b1 has: a support surface (upper surface) for placing the weight 25a. The second support portion 25b2 includes a plurality of rod-shaped members. The second support portion 25b2 protrudes downward from the lower surface of the first support portion 25b1. The second support portion 25b2 has a contact portion 25b3 that contacts the frame portion 7 of the cover member 4. The contact portion 25b3 is formed in a tip shape. The contact portion 25b3 contacts the second main surface 7b of the frame portion 7 through the second antireflection film 10b. The pressing member 25 presses the cover member 4 in a self-supporting state on the cover member 4 by bringing the contact portions 25b3 of the plurality of second support portions 25b2 into contact with the frame portion 7. By pressing the cover member 4 with the pressing member 25, the joint portion 15 formed on the frame portion 7 of the cover member 4 and the metal layer 6 formed on the first main surface 2a of the substrate 2 can be brought into close contact. Then, the metal layer 6 and the joint portion 15 are heated in a crimped state (heating step). Thereby, the metal-based joint material of the joint portion 15 is brought into a molten state. Also in this heating step, since the tip-shaped contact portion 25b3 of the second support portion 25b2 contacts the frame portion 7 of the cover member 4, the contact area between the contact portion 25b3 and the frame portion 7 can be minimized. Thereby, the heat transfer from the frame portion 7 to the second support portion 25b2 of the pressing member 25 can be suppressed to a minimum. Then, the molten metal-based joint material is cooled and solidified (cooling step). In the cooling step, stress is generated in the frame portion 7 due to the difference in the coefficient of thermal expansion between the substrate 2 and the frame portion 7 of the cover member 4. In this case, the buffer portion 10a2 of the first antireflection film 10a deforms to relieve the stress. Thereby, damage to the frame portion 7 can be reduced. When the cooling step is completed, the sealing portion 5 is formed by joining the metal layer 6 of the substrate 2 and the metal layer 14 of the cover member 4 into one body using the joint portion 15. Through the above processing, the package 1 with ensured airtightness is completed. FIG. 13 shows an example of the glass substrate for manufacturing the cover member 4. The glass substrate G includes a frame portion 7, a plurality of protruding portions 8 protruding from the frame portion 7, and antireflection films 10a and 10b. Each protruding portion 8 has the same configuration as the protruding portion 8 of the cover member 4 described above. Each protruding portion 8 is formed by causing thermal deformation at a plurality of locations on a large plate glass GS using the forming device 16 described above. By cutting the glass substrate G along the cutting line CL, a plurality of cover members having the protruding portion 8, the frame portion 7, and the antireflection films 10a and 10b can be efficiently manufactured. Also, the metal layer 14 and the joint portion 15 may be formed on the first antireflection film 10a. FIG. 14 shows another example of the cover member. In this example, the cover member 4 includes a frame portion 7, a plurality of protruding portions 8 protruding from the frame portion 7, antireflection films 10a and 10b, a metal layer 14, and a joint portion 15. Each component of the cover member 4 has the same configuration as the cover member 4 in the above (FIG. 5). When a plurality of light-emitting elements 3 are placed on the substrate 2, the cover member 4 can individually seal each light-emitting element 3 by the plurality of protruding portions 8. FIG. 15 shows another example of the lid member. In this example, the inner surface 8a of the lid member 4 has: a first curved surface 8a1 and a second curved surface 8a2 with different radii of curvature, and a boundary portion 8a3 located between the first curved surface 8a1 and the second curved surface 8a2. The radius of curvature of the first curved surface 8a1 formed on the base 11 side of the protrusion 8 is smaller than the radius of curvature of the second curved surface 8a2 formed on the top 13 side of the protrusion 8. The outer surface 8b of the lid member 4 has: a first curved surface 8b1 and a second curved surface 8b2 with different radii of curvature, and a boundary portion 8b3 located between the first curved surface 8b1 and the second curved surface 8b2. The radius of curvature of the first curved surface 8b1 formed on the base 11 side of the protrusion 8 is smaller than the radius of curvature of the second curved surface 8b2 formed on the top 13 side of the protrusion 8. FIGS. 16 and 17 show top views of another example of the lid member. In this example, the lid member 4 has: a plurality of protrusions 8 arranged in multiple rows and columns, antireflection films 10a, 10b (the illustration of the first antireflection film 10a is omitted), a metal layer 14 (the illustration is omitted), and a joint portion 15 (the illustration is omitted). The lid member 4 shown in FIG. 16 has: a plurality of protrusions 8 that are circular in top view. On the other hand, the lid member 4 shown in FIG. 17 has: a plurality of protrusions 8 that are quadrangular in top view. Also, regarding the lid member 4 having a plurality of protrusions 8 arranged in multiple rows and columns, a scribe line can be formed on the smooth surface between adjacent protrusions 8 and the lid member 4 can be cut along the scribe line, or it can be cut by blade dicing or laser ablation to obtain a plurality of lid members, and lid members of any shape can also be obtained. FIG. 18 shows a bottom view of another example of the lid member. In this example, the lid member 4 is the same as the example shown in FIG. 17 and has protrusions 8 that are quadrangular in top view. According to this configuration, the opening 8c of the protrusion 8 is configured to be quadrangular (e.g., square). When the opening 8c is configured to be square, the opening length L corresponds to the length of one side of the square. When the opening 8c is configured to be rectangular, the opening length L corresponds to the length of the long side of the rectangle. FIG. 19 shows another example of the manufacturing method of the lid member (the preparation process in the manufacturing method of the package). This example shows the process of forming the joint portion 15 on the glass substrate G on which the antireflection films 10a, 10b and the metal layer 14 are formed. Specifically, it illustrates the case where the glass substrate G is fixed to the support device 26 when forming the joint portion 15 by screen printing. The support device 26 includes: a support plate 27 for supporting the glass substrate G, and a suction table 29 for supporting the support plate 27. The support plate 27 is configured to be detachable from the suction table 29. The support plate 27 has an opening 28 into which the protruding portion 8 and the connecting portion 9 of the glass substrate G can be inserted. The support plate 27 inserts the protruding portion 8 and the connecting portion 9 into the opening 28 with the protruding portion 8 of the glass substrate G facing downward, and can support only the frame portion 7 of the glass substrate G without contacting the protruding portion 8 and the connecting portion 9. The suction table 29 includes a support portion 30 for supporting the support plate 27 and a suction port 31 for fixing the glass substrate G to the support plate 27. The support portion 30 has a support surface 30a for supporting the peripheral portion of the support plate 27. The suction table 29 has a space portion 29a between the support plate 27 supported by the support portion 30 and the suction port 31. The suction port 31 is connected to a suction device (exhaust device) such as a pump (not shown). The suction table 29 discharges the gas present in the space portion 29a from the suction port 31 in a state where the support plate 27 on which the glass substrate G is placed is supported by the support portion 30, thereby making the space portion 29a negative pressure. Thus, the glass substrate G is attracted toward the space portion 29a through the opening 28 of the support plate 27 and is thereby fixed to the support plate 27. Then, a paste-like metal-based bonding material for the bonding portion 15 is applied in a manner overlapping the metal layer 14 of the glass substrate G by screen printing. By supporting the glass substrate G by the support device 26 as described above, the bonding portion 15 can be formed with good accuracy. FIG. 20 shows another example of the package. The package 1 in this example includes a substrate 2 on which a plurality of light-emitting elements 3 are mounted and a lid member 4 illustrated in FIG. 14. The lid member 4 individually seals each light-emitting element 3 mounted on the substrate 2 by a plurality of protruding portions 8 and sealing portions 5. According to the package 1 of the present embodiment described above, by forming antireflection films 10a and 10b on the inner surface 8a and the outer surface 8b of the protruding portion 8 of the lid member 4, the light emitted from the light-emitting element 3 can penetrate through the protruding portion 8 with good efficiency. Thereby, the light extraction efficiency of the package 1 using the lid member 4 can be increased as much as possible. In the lid member 4, the value (Ta1 / Ta3) obtained by dividing the thickness Ta1 of the first antireflection film 10a formed at the base portion 11 of the protruding portion 8 by the thickness Ta3 of the first antireflection film 10a formed at the top portion 13 of the protruding portion 8 is set to 0.75 or more and less than 1, whereby the light extraction efficiency can be improved. Furthermore, the present invention is not limited to the configuration of the above-described embodiment, nor is it limited to the above-described effects. The present invention can be variously modified without departing from the gist of the present invention. In the above-described embodiment, although the cover member 4 and the glass substrate G having the first antireflection film 10a and the second antireflection film 10b are shown, the present invention is not limited to this configuration. The cover member 4 and the glass substrate G of the present invention may also have only the first antireflection film 10a. In the cover member 4 illustrated in the above-described embodiment, although the protruding portion 8 is configured such that the thickness of the top portion 13 is thinner than the thickness of the base portion 11, the present invention is not limited to this configuration. The present invention can also be applied to a cover member 4 having a protruding portion 8 with a constant thickness from the base portion 11 to the top portion 13. FIG. 21 shows another example of the cover member. In this example, the inner surface 8a of the cover member 4 has a first curved surface 8a1 that bulges inward toward the protruding portion 8, a second curved surface 8a2 that bulges outward toward the protruding portion 8, and an inflection point 8a3 located between the first curved surface 8a1 and the second curved surface 8a2. The first curved surface 8a1 is formed at a position closer to the base portion 11 of the protruding portion 8 than the second curved surface 8a2. The center of curvature of the first curved surface 8a1 is located outside the protruding portion 8. The second curved surface 8a2 is formed at a position closer to the top portion 13 than the first curved surface 8a1. The center of curvature of the second curved surface 8a2 is located inside the protruding portion 8. The outer surface 8b of the cover member 4 has a first curved surface 8b1 that bulges inward toward the protruding portion 8, a second curved surface 8b2 that bulges outward toward the protruding portion 8, and an inflection point 8b3 located between the first curved surface 8b1 and the second curved surface 8b2. The first curved surface 8b1 is formed at a position closer to the base portion 11 of the protruding portion 8 than the second curved surface 8b2. The center of curvature of the first curved surface 8b1 is located outside the protruding portion 8. The second curved surface 8b2 is formed at a position closer to the top portion 13 of the protruding portion 8 than the first curved surface 8b1. The center of curvature of the second curved surface 8b2 is located inside the protruding portion 8. The inflection point 8a3 and the inflection point 8b3 are provided above (on the top portion 13 side) the second main surface 7b of the frame portion 7. Each of the inflection points 8a3 and 8b3 of the inner surface 8a and the outer surface 8b can be formed on the cover member 4 by the forming device and the forming method shown in FIGS. 8 and 9. When the protruding portion 8 having the inflection points 8a3 and 8b3 is provided as in the cover member 4 of this example, by setting the protruding angle θ to 10° to 80°, the light extraction efficiency of the cover member 4 can be improved. The protruding angle θ is more preferably 20° to 70°, and even more preferably 20° or more and less than 40°. In this example, the definition of the protruding angle θ is different from that of the embodiment shown in FIG. 5. In this example, the protruding angle θ is the angle (acute angle) formed between the tangent line L8 of the inflection point 8a3 and the first main surface 7a of the frame portion 7. Specifically, the angle (acute angle) formed between the tangent line L8 of the inflection point 8a3 and the ninth line L9 drawn along the first main surface 7a of the frame portion 7 is defined as the protruding angle θ. In this example, the opening length L and the protruding height H of the opening portion 8c are the same as those of the embodiment shown in FIG. 5. In this example, the antireflection films (10a, 10b) are not necessarily essential components, but it is preferable to provide the antireflection films (10a, 10b). The preferred forms of the materials and thicknesses of the antireflection films (10a, 10b) are the same as those of the embodiment shown in FIG. 5. In this example, the preferred forms of the thicknesses (the thickness of the base portion 11 and the thickness of the top portion 13) and the outer diameters of the protruding portion 8 are the same as those of the embodiment shown in FIG. 5. FIGS. 22 to 26 show other examples of the package body and the lid member. In this example, the shape of the lid member is different from that of the above-described embodiment. As shown in FIGS. 22 to 24, the top portion 13 of the lid member 4 in this example is configured to be flat. By forming the flat top portion 13 on the lid member 4 in this way, antireflection films 10a, 10b having a uniform thickness can be formed on the inner surface 8a and the outer surface 8b of the lid member 4 related to the top portion 13. Further, by forming the flat top portion 13 on the lid member 4, the distance D1 between the top portion 13 and the light-emitting element 3 can be minimized as much as possible. In addition, the light emitted from the light-emitting element 3 can be made to be more easily incident perpendicularly on the flat top portion 13. Therefore, the light extraction efficiency of the lid member 4 can be significantly improved. Next, a manufacturing method of the package body 1 (a manufacturing method of the lid member 4) in this example will be described. In this method, the preparation process in the manufacturing method of the package body 1 is different from the examples shown in FIGS. 8 and 9. As shown in FIG. 25, the forming device 16 includes: a support table 17, a shielding member 18, a heating source 19, a pressing member 20, an external force generating device 21, and a forming die (receiving jig) 32. The configurations of the support table 17, the shielding member 18, the heating source 19, the pressing member 20, and the external force generating device 21 are the same as those exemplified in FIG. 8. The forming die 32 is disposed in the space portion 17b of the support table 17. The forming die 32 has a forming surface 32a for forming a part of the plate glass GS softened by heating. The forming surface 32a is configured to be a flat surface. The surface roughness (arithmetic mean roughness) Ra of the forming surface 32a is, for example, 0.1 nm to 10 nm. As shown in FIG. 26, in the forming process, the shielding member 18 is overlapped and disposed on the plate glass GS supported by the support table 17. In this case, at least a part of the inner peripheral edge E2 of the through hole 18a of the shielding member 18 is disposed more inward than the opening edge E1 of the support table 17. Then, the pressing member 20 presses the support table 17 and the shielding member 18 in a direction approaching each other. Next, the plate glass GS is heated from the side of the shielding member 18 by the heat source 19. Thereby, thermal deformation is generated in a part of the plate glass GS. At this time, a part of the deformed plate glass GS comes into contact with the forming surface 32a of the forming die 32. Thus, a part of the plate glass GS is formed into a flat shape. The cover member 4 having the frame portion 7, the protruding portion 8 including the flat top portion 13, and the connecting portion 9 is formed by this forming process. By performing the film forming process and the bonding process illustrated in FIGS. 10 to 12 on the cover member 4, the package 1 can be manufactured. [Embodiment] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments. The inventors of the present case conducted an experiment to measure the light extraction efficiency based on the cover member in order to confirm the effects of the present invention. In this experiment, cover members (specimen Nos. 1 to 8) of an embodiment and a comparative example having an antireflection film on the inner surface of the protruding portion were prepared, and the light extraction efficiency was measured for each example. For each specimen, a cover member having the shape shown in FIG. 21 was made. Regarding the light extraction efficiency, the energy EN1 of the light (wavelength 265 nm) emitted from the light emitting element without passing through the cover member was measured, and the energy EN2 in the case where the light (wavelength 265 nm) emitted from the light emitting element passed through the cover member was measured, and the light extraction efficiency was calculated from the ratio of the two energies (EN2 / EN1). The test conditions and measurement results are shown in Table 1. In Table 1, based on the light extraction efficiency (EN2 / EN1) of the comparative example of specimen No. 7, in the embodiment, those with a light extraction efficiency of 1.1 times or more of the reference were judged as good "○", and those less than 1.1 times were judged as poor "×". As shown in Table 1, it can be found that when the value (Ta1 / Ta3) obtained by dividing the thickness Ta1 of the first antireflection film formed at the base of the protruding portion by the thickness Ta3 of the first antireflection film formed at the top of the protruding portion is 0.75 or more and less than 1 (specimen Nos. 1 to 6), the light extraction efficiency can be improved. 1: Package body 2: Substrate 3: Light-emitting element 4: Cover member 7: Frame portion 7a: First main surface of the frame portion 7b: Second main surface of the frame portion 8: Protrusion 8a: Inner surface of the protrusion 8a1: First curved surface of the inner surface of the protrusion 8a2: Second curved surface of the inner surface of the protrusion 8a3: Inflection point of the inner surface of the protrusion 8b: Outer surface of the protrusion 8c: Opening of the protrusion 10a: First antireflection film 10b: Second antireflection film 11: Base portion 13: Top portion 14: Metal layer Ta1: Thickness of the first antireflection film of the base portion of the protrusion Ta3: Thickness of the first antireflection film of the top portion of the protrusion Tb1: Thickness of the second antireflection film of the base portion of the protrusion Tb3: Thickness of the second antireflection film of the top portion of the protrusion Tmin: Thickness of the top portion of the protrusion Tmax: Thickness of the base portion of the protrusion θ: Protrusion angle [FIG. 1] is a perspective view of the package body. [FIG. 2] is a cross-sectional view of the package body. [FIG. 3] is a cross-sectional view of the substrate. [FIG. 4] is a top view of the substrate. [FIG. 5] is a cross-sectional view of the cover member. [FIG. 6] is a cross-sectional view of the main part of the cover member. [FIG. 7] is a bottom view of the cover member. [FIG. 8] is a cross-sectional view showing a preparation process of the manufacturing method of the package body. [FIG. 9] is a cross-sectional view showing a preparation process of the manufacturing method of the package body. [FIG. 10] is a cross-sectional view showing a film-forming process of the manufacturing method of the package body. [FIG. 11] is a cross-sectional view showing a bonding process of the manufacturing method of the package body. [FIG. 12] is a cross-sectional view showing a bonding process of the manufacturing method of the package body. [FIG. 13] is a cross-sectional view of the glass substrate for manufacturing the cover member for the package body. [FIG. 14] is a cross-sectional view showing another example of the cover member. [FIG. 15] is a cross-sectional view showing another example of the cover member. [FIG. 16] is a top view showing another example of the cover member. [FIG. 17] is a top view showing another example of the cover member. [FIG. 18] is a bottom view showing another example of the cover member. [FIG. 19] is a cross-sectional view showing another example of the preparation process of the manufacturing method of the package body. [FIG. 20] is a cross-sectional view showing another example of the package body. [FIG. 21] is a cross-sectional view showing another example of the cover member. [FIG. 22] is a cross-sectional view showing another example of the package body. [FIG. 23] is a cross-sectional view of the cover member. [FIG. 24] is a cross-sectional view of the cover member. [FIG. 25] is a cross-sectional view showing a preparation process of the manufacturing method of the package body. [FIG. 26] is a cross-sectional view showing a preparation process of the manufacturing method of the package body. 4: Cover member 7: Frame portion 7a: First main surface of the frame portion 7b: Second main surface of the frame portion 8: Protrusion 8a: Inner surface of the protrusion 8b: Outer surface of the protrusion 8c: Opening of the protrusion 9: Connecting part 10a1, 10b1: Anti-reflection part 11: Base part 11a: First base part 11b: Second base part 12: Intermediate part 13: Top part Ta1: Thickness of the first anti-reflection film of the base part of the protrusion Ta2: Thickness of the first anti-reflection film of the intermediate part of the protrusion Ta3: Thickness of the first anti-reflection film of the top part of the protrusion Tb1: Thickness of the second anti-reflection film of the base part of the protrusion Tb2: Thickness of the first anti-reflection film of the intermediate part of the protrusion Tb3: Thickness of the second anti-reflection film of the top part of the protrusion L1: Straight line (first line) L2: Straight line (second line) L3: Straight line (third line) L6: Straight line (sixth line) P1, P2, P3: Intersection points

Claims

1. A cover member, a glass cover member used in an encapsulation containing a light-emitting element, characterized in that it comprises: a plate-shaped frame portion and a dome-shaped protrusion protruding from the frame portion, the protrusion having an inner surface and an outer surface, the protrusion having: a top and a base integrally formed with the frame portion, an anti-reflective film being formed on the inner surface of the protrusion, and the value obtained by dividing the thickness of the anti-reflective film formed on the base by the thickness of the anti-reflective film formed on the top being 0.75 or more and less than 1.

2. As in claim 1, the cover component, wherein, The thickness of the aforementioned protrusion at the top is thinner than the thickness of the aforementioned protrusion at the base.

3. As in claim 1 or 2, the cover component, wherein, The aforementioned frame portion has: a first main surface connected to the aforementioned inner surface of the aforementioned protrusion, and a second main surface connected to the aforementioned outer surface of the aforementioned protrusion, wherein the aforementioned anti-reflective film is formed on the aforementioned first main surface of the aforementioned frame portion.

4. As in claim 3, the cover component, wherein, A metal layer is formed on the side of the antireflective film that is opposite to the side of the first main surface formed on the aforementioned frame portion.

5. As in claim 1 or 2, the cover component, wherein, The aforementioned antireflective film includes a hafnium oxide film.

6. The cover component as requested in item 1 or 2, wherein, A second anti-reflective film is formed on the outer surface prior to the aforementioned protrusion.

7. As in claim 6, the cover component, wherein, The thickness of the second antireflective film formed on the aforementioned top is greater than the thickness of the second antireflective film formed on the aforementioned base.

8. The cover component as requested in item 1 or 2, wherein, The aforementioned protrusion protrudes from the aforementioned frame portion at a predetermined protrusion angle, which is 10° to 80°.

9. The cover component as requested in item 1 or 2, wherein, The aforementioned protrusion has an opening formed on the aforementioned inner surface side, wherein the ratio (L / H) of the opening length L of the aforementioned opening to the protrusion height H of the aforementioned protrusion is 1.2 to 8.

10. As in claim 9, the cover component, wherein, The aforementioned opening is configured as a four-cornered shape.

11. The cover component as requested in item 1 or 2, wherein, The aforementioned frame portion has: a first main surface connected to the aforementioned inner surface of the aforementioned protrusion, and a second main surface connected to the aforementioned outer surface of the aforementioned protrusion. The aforementioned inner surface has: a first curved surface connected to the aforementioned first main surface of the aforementioned frame portion and protruding toward the inner side of the aforementioned protrusion, a second curved surface protruding toward the outer side of the aforementioned protrusion, and a recurved point located between the aforementioned first curved surface and the aforementioned second curved surface.

12. An encapsulation comprising: a light-emitting element, a substrate supporting the light-emitting element, and a cover member as claimed in claim 1 or 2.

Images