JP2011035436A - Method of manufacturing vacuum package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a vacuum package to achieve high vacuum without generating poor sealing nor malfunction. <P>SOLUTION: The method of manufacturing the vacuum package includes a step of setting a package with a through-hole formed thereon in a vacuum chamber with a transmitting window, a step of decompressing inside the vacuum chamber, a step of placing sealing material in the through-hole, and a step of sealing the through-hole by irradiation of a laser onto the sealing material through the transmittance window from outside the vacuum chamber. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a package in which functional elements (for example, infrared detection elements, piezoelectric elements, vibration elements, etc.) are vacuum-sealed.

  In functional devices such as an infrared sensor, a pressure sensor, and an acceleration sensor, it is necessary to vacuum-seal each functional element in order to improve its performance.

  Taking an infrared sensor as an example, generally, an infrared detection element has a quantum type and a thermal type, and the thermal type is a method for detecting a relative amount of heat. For this reason, the thermal type is inferior to the quantum type, but can be made uncooled, and the manufacturing cost can be reduced by simplifying the structure. In this thermal infrared sensor, the infrared light transmitted through the window is absorbed by the light receiving portion of the detection element, and a resistance change accompanying a temperature change caused thereby is detected as a signal. Therefore, in the nighttime security monitoring camera and the infrared sensor used for the thermography for indexing and displaying the temperature distribution, it is necessary to thermally insulate the light receiving portion in order to detect the signal with high sensitivity. Such thermal insulation can be obtained, for example, by floating the light receiving part in the air or by disposing the infrared detection element itself in the vacuum vessel.

  FIG. 24 is a schematic cross-sectional view for explaining the infrared detection vacuum package described in Patent Document 1. For example, in the vacuum package for infrared detection described in Patent Document 1, a substrate 901 having a light receiving portion 902 formed on a substrate 901 and one or more through holes 911 are provided, and the front surface of the light receiving portion 902 of the substrate 901 is provided. An infrared transmission window 904 disposed with a gap 903 therebetween is formed, and the substrate 901 and the transmission window 904 are fixed by adhering each other in an airtight manner on an adhesive surface that completely surrounds the light receiving portion 902. In addition, after the gap 903 between the substrate 901 and the transmission window 904 is evacuated by exhausting from the through hole 911, the through hole 911 of the transmission window 904 is hermetically sealed with the sealing material 912.

  In addition, for example, Patent Document 2 and Patent Document 3 describe a sealing technique in a vacuum package in which a functional element is sealed.

  In the package for a piezoelectric device described in Patent Document 2, a frame-shaped substrate is stacked on a bottom substrate serving as a bottom, so that an internal space for accommodating a piezoelectric vibrating piece is formed inside the frame-shaped substrate. And a package for a piezoelectric device in which a bottom substrate is provided with a through-hole that communicates the internal space with the outside and melts the sealing material to seal the hole, and the bottom substrate is formed from a single substrate. The through-hole has an inner circumference larger than the outer shape of the sealing material before melting, and has an inner circumference smaller than the outer shape of the sealing material before melting inside the larger inner circumference. Moreover, the metal coating part with good wettability and a sealing material is provided in the internal peripheral surface of the through-hole.

  FIG. 25 is a schematic cross-sectional view for explaining the sealed package structure of the element described in Patent Document 3, and FIG. 26 is a partial schematic cross-sectional view of the hole shown in FIG. In the sealed package structure of an element described in Patent Literature 3, an element forming substrate body 922, a lid substrate body 923 bonded to the upper side of the element forming substrate body 922, an element forming substrate body 922, and a lid substrate body. An element 921 accommodated in a space 925 surrounded by the 923, a hole 926 extending from the opening on the surface of the lid substrate body 923 to the surface of the element forming substrate body 922, and an element forming substrate body surrounded by the hole 926 A small-diameter opening 930a having a smaller diameter than the hole 926 is formed in the surface region of 922, and the communication hole 929 that communicates with the space 925 from the small-diameter opening 930a and the small-diameter opening 930a of the communication hole 929 are closed. Seal joint strengthening that increases the joint strength between the sealing member 931 that seals the accommodation space of the element 921 and the sealing member 931 formed at the upper end edge 930b of the small-diameter opening of the communication hole 929. And a 933, the said holes 926 constricted portion 932 diameter is hourglass until reaching the surface of the element forming substrate body 922 from the opening portion is formed. In this sealed package structure, first, the sealed package structure of the element in which the space 925 is not sealed is placed in a vacuum device, and the space 925 is evacuated through the communication hole 929 and the hole 926. Subsequently, the sealing member 931 placed on the constricted portion 932 is heated and melted while being evacuated, and the degassing of the sealing member 931 is continued, and the heating of the sealing member 931 is further continued. The molten sealing member 931 is dropped from 932 toward the small-diameter opening 930 a of the communication hole 929, the small-diameter opening 930 a of the communication hole 929 is closed by the sealing member 931, and the accommodation space 925 of the element 921 is sealed. Yes.

Japanese Patent Laid-Open No. 11-326037 JP 2004-266663 A Japanese Patent Laid-Open No. 11-340348

  27 to 29 are schematic sectional views of through-hole portions for explaining the problems to be solved by the present invention. 27 (a) and 28 (a) show a state before sealing in which the sealing material is placed in the through hole, and FIGS. 27 (b) and 28 (b) show that the sealing material is melted. The state after sealing is shown.

  In the sealing technique as described in Patent Document 1, the opening of the through hole is sealed with a sealing material such as solder without sealing the inside of the through hole (between the inner walls). In this case, for example, as shown in FIG. 27A, a sealing material pad (metal coating) 942 is formed around the opening of the through hole 943, and the sealing material (for example, solder ball) 944 is formed in the through hole 943. Is placed to dissolve the sealing material 944. However, in such a form, as shown in FIG. 27B, the sealing material 944 flows so as to avoid the opening of the through-hole 943 or falls through the through-hole 943, and thus the through-hole There is a tendency that 943 cannot be completely sealed. In particular, when the opening diameter of the through hole 943 is wide, a sealing failure is likely to occur.

  In the sealing technique as described in Patent Document 2, the inside of the through hole is completely closed with a sealing material. In this case, for example, as shown in FIG. 28, a sealing material pad (metal coating) 952 is formed on the entire inner wall of the through hole 953. However, in such a form, as shown in FIG. 28B, the sealing material 954 may protrude from the through hole 953 due to its surface tension. Then, in the structure in which the package is thinned, since the distance between the through hole 953 and the functional element (for example, infrared light receiving element) is short, the protruding sealing material 954a reaches the functional element and the metal wiring (for example, wire bonding). As a result, a malfunction (for example, imaging failure) or a short circuit is caused. In particular, when lead-free solder is used for the sealing material 954, since a needle-like whisker due to Sn is likely to occur, even if the solder and the wire are not in direct contact with each other at an early stage, the whisker that grows with time is the cause. This increases the risk of short circuiting. Therefore, in the form as shown in FIG. 28, it is necessary to secure a sufficient distance between the sealing material 954 and the functional element or metal wiring, but this makes it impossible to reduce the thickness of the package.

  In the sealing technique as described in Patent Document 3, since the sealing material is finally dropped from the constricted portion, the inside of the through hole (between the inner walls) cannot be sealed with the sealing material. Therefore, the sealing technique described in Patent Document 3 cannot be applied to the through hole of the package having the form shown in FIG.

  Further, when a through hole having a taper as shown in FIGS. 27 to 29 is formed, a portion having an angle of 90 degrees or less is formed on the substrate on which the through hole is formed (for example, FIGS. 27 to 29). 29 corners 945, 955). Such right or sharp corners have a risk of cracking due to thermal stress accompanying expansion / contraction of the sealing material during sealing or product use. In particular, materials such as silicon and germanium, which are often used for infrared transmission windows, light receiving element substrates, spacers, and the like, are very fragile materials. Therefore, when a through hole having an acute angle portion is formed in such a material, cracks are caused. There is a high risk of sealing failure.

  Further, in the infrared sensor, a general infrared transmission window has a thickness of about 0.5 mm to 1.0 mm. For example, as shown in FIGS. When forming a through hole 943 having a tapered shape, it is necessary to open a through hole 943 having a size that is somewhat larger than the package capacity in order to ensure sufficient conductance in order to evacuate the through hole 943. That is, since evacuation depends on the minimum area of the through hole 943, it is necessary to form the through hole 943 so that the minimum area S1 of the first opening 941a formed on one surface is sufficiently large. There is. However, when the minimum area S1 is increased, the maximum area S2 of the second opening 941b formed on the other surface inevitably increases due to the tapered shape of the through hole 943. As a result, there is a problem that the package size must be increased.

  Next, a method for calculating the conductance of the through hole will be described. For example, consider a simple vacuum package in which a through hole having a diameter D and a length L is connected to a container having dimensions X × Y × Z as shown in FIG. 30 as one model. When the mean free path of gas molecules is λ, a pressure region satisfying λ << D is called a viscous flow region, and its conductance is known to depend on pressure. The conductance Cp in this viscous flow region is expressed by Equation 1, where p is the average pressure at both ends of the through hole. At this time, the gas sealed in the package is air at 20 ° C. The unit of p is Torr, L, and D is cm.

[Equation 1]
Cp = 182 × (D ⁴ / L) × p (l / s)

  On the other hand, the pressure region satisfying λ >> D is called a molecular flow region, and the conductance Ck in this molecular flow region is expressed by the following equation (2). Also in this case, the gas enclosed in the package is 20 ° C. air. The unit of L and D is cm.

[Equation 2]
Ck = 12.1 × (D ³ / L) (l / s)

  Here, when the air is room temperature and the pressure is p (Torr), the mean free path λ is expressed by the following approximate expression.

[Equation 3]
λ (mm) ≈5 × 10 ⁻² / p

Here, if Equation 3 is used and the diameter D of the through hole is 0.1 mm, a viscous flow region of about λ / D <0.01 is about 50 Torr or more, and λ / D> 10. The molecular flow region can be calculated to be about 0.05 Torr or less. In the region of 0.05 Torr to 50 Torr (6.67 Pa to 6665 Pa), the intermediate region satisfies 0.01 <λ / D <10. Since the degree of vacuum required for a vacuum sealed package such as an infrared sensor is normally 10 ⁻² Torr to 10 ⁻⁶ Torr (133.3 × 10 ⁻² Pa to 133.3 × 10 ⁻⁶ Pa), It is necessary that sufficient conductance is ensured up to the region.

When the conductance Cp of the viscous flow region in the through hole with D of 0.1 mm and L of 1 mm is calculated from Equation 1, the value is 18 × p (mm ³ / s), and the conductance Ck of the molecular flow region is From Equation 2, it is calculated as 121 (mm ³ / s). If the capacity of the vacuum package is 14 mm × 14 mm × 1.4 mm and the volume is 274 mm ³ , it can be assumed that a vacuum can be drawn even considering the conductance of the molecular flow region.

  However, this result is based on the assumption that the diameter of the through hole is 0.1 mm, and Ck decreases in proportion to the cube of the diameter of the through hole. Therefore, if the diameter of the through hole is smaller than 0.1 mm, high vacuum It becomes difficult to realize the package. That is, for example, in order to realize a high vacuum package in an infrared sensor, the diameter of the first opening 941a in FIG. 29 needs to be at least 0.1 mm, for example, in order to obtain sufficient conductance. The diameter of the opening 941b must be larger than 0.1 mm. In other words, if the maximum area S2 of the second opening 941b is made smaller than that, the minimum area S1 of the first opening 941a becomes too small and sufficient evacuation cannot be performed. That is, in order to realize a high vacuum and small package, it is necessary to form a through hole having a sufficiently large conductance while having a small surface opening area.

  An object of the present invention is to provide a manufacturing method of a vacuum package that realizes a high vacuum without causing sealing failure and functional failure.

  According to the first aspect of the present invention, a step of setting a package in which a through hole is formed in a vacuum chamber having a transmission window, a step of reducing the pressure in the vacuum chamber, and a step of arranging a sealing material in the through hole And a step of irradiating the sealing material with a laser from the outside of the vacuum chamber through the transmission window to seal the through hole.

  According to a preferred form of the first aspect, the method for manufacturing a vacuum package further includes a step of disposing a sealing material in the through hole before decompressing the inside of the vacuum chamber.

  According to the present invention, even when a bonding material is used for the vacuum package, only the sealing material set in the through hole can be locally heated by the laser device. When the melting point of the bonding material is equal to or lower than the melting point of the bonding material, not only can the bonding material be dissolved but only the sealing material of the through hole can be melted and vacuum-sealed. Even when the melting point is higher than the melting point, if the conditions are optimized, it is possible to seal by dissolving only the sealing material of the through hole.

1 is a schematic cross-sectional view of a vacuum package according to a first embodiment of the present invention. The expanded schematic sectional drawing of the through-hole part of FIG. The expanded schematic sectional drawing which shows the state after sealing a through-hole with sealing material. The schematic plan view which shows an example of the surface shape of a through-hole. The schematic plan view and schematic sectional drawing which show an example of the surface shape of a through-hole. The schematic plan view which shows the example of the surface shape of a through-hole. The schematic fragmentary sectional view of the through-hole part in 2nd Embodiment of this invention. The schematic fragmentary sectional view of the through-hole part in 3rd Embodiment of this invention. The schematic fragmentary sectional view of the through-hole part in 4th Embodiment of this invention. The schematic fragmentary sectional view of the through-hole part in 5th Embodiment of this invention. The schematic fragmentary sectional view of the through-hole part in 6th Embodiment of this invention. The schematic fragmentary sectional view of the through-hole part in 7th Embodiment of this invention. The schematic sectional drawing of the vacuum package which concerns on 8th Embodiment of this invention. The schematic sectional drawing of the vacuum package which concerns on 9th Embodiment of this invention. The schematic sectional drawing of the vacuum package which concerns on 10th Embodiment of this invention. Schematic sectional view of a vacuum package according to an eleventh embodiment of the present invention. The schematic sectional drawing of the vacuum package which concerns on 12th Embodiment of this invention. The schematic sectional drawing of the vacuum package which concerns on 12th Embodiment of this invention. The schematic sectional drawing of the vacuum package which concerns on 12th Embodiment of this invention. The schematic process drawing for demonstrating the formation method of the through-hole in the vacuum package of this invention based on 13th Embodiment of this invention. The schematic sectional drawing for demonstrating the method of vacuum-sealing a vacuum package based on 14th Embodiment of this invention. The schematic sectional drawing for demonstrating the method of vacuum-sealing a vacuum package based on 15th Embodiment of this invention. The schematic sectional drawing for demonstrating the method of vacuum-sealing a vacuum package based on 16th Embodiment of this invention. FIG. 6 is a schematic cross-sectional view for explaining an infrared detection vacuum package described in Patent Document 1. FIG. 5 is a schematic cross-sectional view for explaining a sealed package structure of an element described in Patent Document 3. The partial schematic sectional drawing of the hole part shown in FIG. The schematic sectional drawing of the through-hole part for demonstrating the subject which this invention tends to solve. The schematic sectional drawing of the through-hole part for demonstrating the subject which this invention tends to solve. The schematic sectional drawing of the through-hole part for demonstrating the subject which this invention tends to solve. The schematic perspective view for demonstrating the calculation method of the conductance of a through-hole.

  Hereinafter, the vacuum package of the present invention will be described by taking as an example a vacuum package according to an infrared sensor in which an infrared light receiving element is vacuum-sealed as a functional element.

A vacuum package according to the first embodiment of the present invention will be described. FIG. 1 is a schematic cross-sectional view of a vacuum package according to the first embodiment of the present invention. The vacuum package 100 includes an infrared light receiving element 1 that detects infrared light, a light receiving element substrate 3 on which the infrared light receiving element 1 is mounted, an infrared transmission window 12 that transmits infrared light so that the infrared light receiving element 1 can receive light, and a light receiving element substrate. 3 and a spacer 9 that forms a predetermined gap between the infrared transmission window 12 and the infrared transmission window 12. The infrared light receiving element 1 is fixed on the light receiving element substrate 3 through the bonding material 2, and the chamber 6 that accommodates the infrared light receiving element 1 is covered with a spacer 9, an infrared transmission window 12, and the like on its side surface and upper surface. Formed on the infrared light receiving element 1. The inside of the chamber 6 is depressurized from the atmospheric pressure, and is preferably depressurized to 133.3 × 10 ⁻² Pa to 133.3 × 10 ⁻⁶ Pa.

  The infrared transmitting window 12 is formed with at least one through hole 13 used for degassing the chamber 6. FIG. 2 shows an enlarged schematic cross-sectional view of the through-hole 13 portion (illustration of the sealing material 15 is omitted). FIG. 3 shows an enlarged schematic cross-sectional view showing a state after the through hole 13 is sealed with the sealing material 15. The through-hole 13 has, on its inner wall, a first tapered surface 12b whose opening area (width or diameter in the drawing) decreases from the outer surface 12a facing outward of the chamber 6 toward the inner side of the chamber 6, and A second tapered surface 12c whose opening area (width or diameter in the drawing) decreases from the inner surface 12d facing inward toward the chamber 6 outward. Then, the first tapered surface 12b and the second tapered surface 12c are continuously formed, so that the opening area of the through hole 13 (in the drawing, the width) is formed at the boundary between the first tapered surface 12b and the second tapered surface 12c. A constricted portion 13a having the most reduced diameter is formed.

  Here, in a cross section (FIGS. 2 and 3) perpendicular to the infrared transmitting window 12 along the through hole 13, the first angle α of the first corner formed by the outer surface 12a and the first tapered surface 12b, and Since the second angle β of the second corner formed by the first tapered surface 12b and the second tapered surface 12c is in contact with the sealing material 15 (via the pad 14), both become obtuse angles. To form. Preferably, the first angle α, the second angle β, and the third angle γ of the third corner formed by the second tapered surface 12c and the inner surface 12d are all formed to be obtuse. More preferably, the first angle α, the second angle β, and the third angle γ are set to 100 ° to 160 °. Thereby, all the 1st-3rd corner | angular parts of the infrared transmission window 12 which form the through-hole 13 become obtuse angles, and generation | occurrence | production of the defect in each corner | angular part can be suppressed.

  The through hole 13 shown in FIGS. 1 and 2 forms a first taper surface 12b and a second taper surface 12c so as to be line symmetric with respect to a center line passing through the through hole 13. That is, the center line of the through hole in the first tapered surface 12b and the center line of the through hole in the second tapered surface 12c coincide. Thereby, the line connecting the minimum width (minimum diameter) of the constricted portion 13a is parallel to the infrared transmission window 12 (the outer surface 12a or the inner surface 12d). Further, the through hole 13 is formed by digging from both sides of the infrared transmitting window 12 at the same depth so that the constricted portion 13a is at the center of the thickness of the infrared transmitting window 12. That is, the depth d1 of the first taper surface 12b formed from the outer surface 12a side and the depth d2 of the second taper surface 12c formed from the inner surface 12d side are formed to be the same.

  The through hole 13 having the tapered surfaces 12b and 12c can be formed by, for example, an etching method. In particular, if anisotropic etching is used, through holes having various tapered shapes can be formed in addition to the forms shown in FIGS. Taking this embodiment as an example, for example, when Si is used as the infrared transmission window 12, the outer surface 12a is a (100) plane, and anisotropic etching is performed from both sides of the infrared transmission window 12, the second corner portion is The bisection angle bisector β / 2 can be 54.7 ° (ie β = 109.4 °).

  The opening shape of the through hole 13 (or the cross-sectional shape along the surface direction of the infrared transmitting window 12) on the surface of the infrared transmitting window 12 (plan view of the outer surface 12a or the inner surface 12d) may be various forms (for example, circular). Can do. At this time, the surface shape of the through hole 13 is such that the chamber 6 can be deaerated between the surface opening or inner wall of the through hole 13 and the sealing material 15 when the sealing material 15 before sealing is placed. A shape that can form such a gap is preferable. For example, when the shape of the sealing material 15 before sealing (before melting) is spherical, if the opening shape of the through hole 13 is an opening shape other than a circle, the sealing material 15 is set in the through hole 13. The inside of the chamber 6 can be depressurized (vacuum) from the gap between the through hole 13 and the sealing material 15.

  FIG. 4 is a schematic plan view showing an example of the surface shape of the through hole 13. The opening shape of the through-hole 13 shown in FIG. 4 is a square. At this time, the through hole 13 has a shape in which two square frustums are connected to each other with surfaces having a small area. When, for example, a spherical solder ball is used as the sealing material 15 (dotted line) at the time of vacuum sealing, the solder ball 15 is set in the through-hole 13 before degassing the chamber 6 and is evacuated in that state. The air in the chamber 6 can be extracted from the four corners (arrow portions) of the through hole 13 that is not closed by 15.

  In FIG. 5, the schematic plan view and schematic sectional drawing which show another example of the surface shape of the through-hole 13 are shown. FIG. 5A is a schematic plan view showing an example of the surface shape of the through-hole 13, and FIG. 5B is a schematic cross-sectional view taken along the line Vb-Vb in FIG. The opening of the through hole 13 in FIG. 5 has an elliptical shape. For this reason, when a spherical solder ball (dotted line) is set in the through-hole 13 as the sealing material 15 before melting, the short axis direction of the elliptical shape is blocked by the solder ball 15, but the long axis direction (arrow part) A gap is formed between the solder balls 15 at both ends, and air in the chamber 6 can be extracted from the gap. In addition, as shown in FIG. 5B, the first tapered surface 12b and the second tapered surface 12c may be curved.

  Moreover, the planar projection shape of the through-hole 13 is not limited to a circle, a square, or an ellipse, and various shapes can be employed. For example, as shown in FIG. 6, a cross (FIG. 6A), a parallelogram, (FIG. 6B), a triangle (FIG. 6C), a polygon (for example, a hexagon) (FIG. 6). (D)), a rectangle (FIG. 6E), a flower shape (FIG. 6F), and the like can be applied.

  For example, anisotropic etching, isotropic etching, dry etching, drill, sandblaster, ultrasonic machining, wire discharge, or the like can be used as a method of creating the through hole 13 in the present invention.

  In addition, when the chamber 6 is deaerated after the sealing material 15 is placed in the through hole 13 in advance, the opening partially closed by the sealing material 15 rather than the opening area of the constricted portion that becomes the minimum opening. In some cases, the area of is smaller. The size relationship between the two areas depends on the shape of the through-hole (dimension, taper angle, opening shape) and the shape of the sealing material (dimension, three-dimensional shape). Consider a smaller opening area.

  In the vacuum package according to the present embodiment shown in FIGS. 1 to 3, on the first tapered surface 12b on the through hole 13 of the infrared transmission window 12, and on at least a part of the outer surface 12a continuous with the first tapered surface 12b. A pad 14 is formed. The pad 14 is not formed on the second tapered surface 12c and the inner surface 12d. As the material of the pad 14, a material having higher wettability than the infrared transmission window 12 with respect to the sealing material 15 is used. For example, Ni, NiP, Au, Cu, Ag, Fe, Co, Pd, Ti, Cr, Pt, an alloy containing them as a main component, or the like can be used as the pad 14. Thereby, the sealing material 15 is reliably arranged in the through hole 13 so as to be placed on the pad 14, that is, the first tapered surface 12 b even in a molten state, and the constricted portion 13 a having the smallest opening area. The through hole 13 can be sealed with the portion. On the other hand, since the sealing material 15 does not seal the through hole 13 in the second tapered surface 12b portion, the sealing material 15 does not protrude into the chamber 6 from the inner surface 12d. Thereby, the sealing material 15 seals the chamber 6 with good airtightness and does not come into contact with the infrared light receiving element 1, the bonding wire 5, or the like in the chamber 6.

  Next, details of the vacuum package 100 for an infrared sensor according to the first embodiment shown in FIG. 1 will be described below.

  An electrode pad 4 is formed on the light receiving element substrate 3, and the electrode pad 4 is drawn out from the chamber 6 to the outside of the chamber 6 along the light receiving element substrate 3. The electrode pad 16 of the infrared light receiving element 1 is electrically connected to the electrode pad 4 by a bonding wire 5. Thereby, the signal detected by the infrared light receiving element 1 can be sent to the outside of the chamber 6 through the electrode pad 4.

The light receiving element substrate 3 is formed of a material capable of maintaining the inside of the chamber 6 in a high vacuum. As a material of the light receiving element substrate 3, for example, a semiconductor material such as Si or Ge, a metal such as Ni, Fe, Co, Cr, Ti, Au, Ag, Cu, Al, Pd, or Pt, or a main component thereof is used. Alloy materials, or glass or ceramic materials such as SiO ₂ and Al ₂ O ₃ can be used.

  A pad 8 a is formed on the electrode pad 4 so as to surround the infrared light receiving element 1 with an insulating layer 7 interposed therebetween. A spacer 9 is bonded onto the pad 8a by a bonding material 10a. The spacer 9 surrounds the infrared light receiving element 1 and secures a predetermined gap for disposing the infrared light receiving element 1 and the like between the light receiving element substrate 3 and the infrared transmitting window 12. Further, the pad 8 a of the infrared transmission window 12 is bonded onto the spacer 9 by the bonding material 10 b, and the infrared transmission window 12 is disposed so as to cover the infrared light receiving element 1 and form the chamber 6. Bonding of each element is performed so as to increase the airtightness of the chamber 6.

As the insulating layer 7, for example, a material such as ceramics or glass such as SiO ₂ , SiON, or SiN can be used.

The material of the spacer 9 is not particularly limited, but it is required that the gas is not easily released when the chamber 6 is evacuated. Examples of the material of the spacer 9 include a semiconductor material such as Si and Ge, a metal such as Ni, Fe, Co, Cr, Ti, Au, Ag, Cu, Al, Pd, and Pt, and an alloy material containing them as a main component. Alternatively, glass or ceramic materials such as SiO ₂ and Al ₂ O ₃ can be used.

As the bonding materials 10a and 10b, Au, solder, or the like can be used. In the case of connection with Au, Au is formed in advance on the spacer 9 and the pads 8a and 8b of the light receiving element substrate 3 or the infrared transmission window 12, and connected by thermocompression bonding, ultrasonic bonding, surface activation bonding, or the like. To do. On the other hand, when connecting with solder, Ni, NiP, Au, Cu, which prevent the solder from spreading or promote the solder wetting in advance on the spacer 9 and the pads 8a and 8b of the light receiving element substrate 3 or the infrared transmitting window 12 are provided. Ag, Fe, Co, Pd, Ti, Cr, Pt, and alloys containing them as main components are formed, and solder is supplied between them to heat and melt in a reflow furnace or hot plate. Connect with. Note that solder may be previously formed on the surfaces of the pads 8a and 8b by plating, sputtering, vapor deposition, or the like, and then connected. When the bonding materials 10a and 10b are solder, the material is mainly a low melting point metal such as Sn, Pb, SnPb, SnAg, SnCu, SnAgCu, SnIn, SnZn, SnBi, SnZnBi, Bi, In, InAg. It is desirable that the material is a component. In addition, a substrate material such as Si / Si, SiO ₂ / SiO ₂ , or Si / glass may be directly bonded by anodic bonding or the like without using the bonding materials 10a and 10b.

The infrared transmission film 12 has antireflection films 11 a and 11 b on both sides of the infrared light receiving element 1. The infrared transmission window 12 is formed of a material that can transmit infrared rays. Examples of the material for the infrared transmission window include Si, Ge, ZnS, ZnSe, Al ₂ O ₃ , SiO ₂ and the like, and alkali halides such as LiF, NaCl, KBr, CsI, CaF ₂ , BaF ₂ , and MgF _2. Materials such as materials, alkaline earth halide materials, chalcogenite glasses mainly containing Ge, As, Se, Te, Sb, and the like can be used.

  Examples of the sealing material 15 that seals the through-hole 13 of the infrared transmission film 12 include Sn, Pb, SnPb, SnAg, SnCu, SnAgCu, SnIn, SnZn, SnBi, SnZnBi, Bi, In, InAg, and the like. A material mainly composed of a melting point metal can be used.

  According to the present embodiment, since the corners forming the through holes 13 have an obtuse shape, the occurrence of defects such as cracks can be prevented when the sealing material 15 is joined or when the product is used. In particular, even if the base material forming the through hole 13 is easily broken silicon or glass, the generation of cracks in the through hole 13 can be suppressed. Further, a pad 14 is formed at the joint portion of the sealing material 15 to prevent airtight defects. Thereby, a highly airtight vacuum package can be obtained.

  Further, the sealing material 15 is received by the constricted portion 13a, and the pad 14 is not formed on the second tapered surface 12c on the infrared light receiving element 1 side, thereby preventing the sealing material 15 from protruding into the chamber 6. Yes. Thereby, it is possible to prevent malfunctions and occurrence of short circuits.

  Furthermore, since the through holes 13 are formed with the tapered surfaces 12b and 12c symmetrically from both surfaces of the infrared transmitting window 12, the opening area of the substrate surface is larger than that of the through holes having only one direction of the tapered surface. A large conductance can be obtained. That is, the through hole 13 having a large conductance advantageous for evacuation of the chamber 6 can be formed without increasing the opening of the substrate surface. As a result, the vacuum package can be downsized while maintaining the performance level.

  Next, vacuum packages according to second to seventh embodiments of the present invention will be described. 2nd Embodiment-7th Embodiment differs in the form of the through-hole in the cross section along the thickness direction of an infrared rays transmission window, respectively. Forms other than the through-hole portion in the second to seventh embodiments are the same as those in the first embodiment.

  FIG. 7 shows a schematic partial cross-sectional view of the through hole portion in the second embodiment of the present invention. FIG. 7A is a schematic cross-sectional view of a through hole showing a state before sealing, and FIG. 7B is a schematic cross-sectional view of the through hole showing a state where the through hole is sealed with a sealing material. is there. In the first embodiment shown in FIG. 2, the depth of the first taper surface from the outer surface side of the infrared transmission window is the same as the depth of the second taper surface from the inner surface. The depth d1 of the first tapered surface 22b from the outer surface 22a of the transmission window 22 is deeper than the depth d2 of the second tapered surface 22c from the inner surface 22d. Thereby, the constricted portion 23a of the through hole 23 is formed on the inner surface 22d side rather than the outer surface 22a side, and the opening of the through hole 23 on the outer surface 22a surface is larger than the opening of the through hole 23 on the inner surface 22d surface. . The pad 24 is formed on the first tapered surface 22 b and the outer surface 22 a, and the sealing material 25 seals the through hole 23 so as to cover the pad 24. According to this embodiment, the sealing material 25 can be stably set in the through hole 23 at the time of sealing.

  FIG. 8 shows a schematic partial cross-sectional view of the through hole portion in the third embodiment of the present invention. FIG. 8A is a schematic cross-sectional view of the through hole showing a state before sealing, and FIG. 8B is a schematic cross-sectional view of the through hole showing a state where the through hole is sealed with a sealing material. is there. In the second embodiment, the first taper surface is deeper than the second taper surface, but in the third embodiment, the depth d2 of the second taper surface 32c from the inner surface 32d of the infrared transmission window 32. This is deeper than the depth d1 of the first tapered surface 32b from the outer surface 32a. Thereby, the constricted portion 33a of the through hole 33 is formed on the outer surface 32a side rather than the inner surface 32d side, and the opening of the through hole 33 on the surface of the inner surface 32d is larger than the opening of the through hole 33 on the surface of the outer surface 32a. . The pad 34 is formed on the first tapered surface 32 b and the outer surface 32 a, and the sealing material 35 seals the through hole 33 so as to cover the pad 34. According to this embodiment, even when the sealing material 35 (for example, solder) flows easily during heating, the sealing material 35 can be made difficult to protrude into the chamber.

  FIG. 9 shows a schematic partial cross-sectional view of the through hole portion in the fourth embodiment of the present invention. FIG. 9A is a schematic cross-sectional view of the through hole showing a state before sealing, and FIG. 9B is a schematic cross-sectional view of the through hole showing a state where the through hole is sealed with a sealing material. is there. In the first to third embodiments, the center line of the through hole portion on the outer surface side that forms the first tapered surface and the through hole portion on the inner surface side that forms the second tapered surface is the same. In the fourth embodiment, the center lines of the through hole 43 portion on the outer surface 42a side forming the first tapered surface 42b and the through hole 43 portion on the inner surface 42d side forming the second tapered surface 42c are shifted (d1 and d2). (See arrow on). For this reason, the line (neck portion 43 a) connecting the corners of the inner wall of the through hole 43 is not parallel to the plane extending direction of the infrared transmission window 42. Also in this embodiment, the pad 44 is formed on the first tapered surface 42 b, and the sealing material 45 seals the through hole 43 at least on the pad 44. According to this embodiment, since the through-hole 43 penetrates in an oblique direction with respect to the surface of the infrared transmission window 42 as a whole, the sealing material 45 is less likely to flow downward due to gravity during heating.

  FIG. 10 shows a schematic partial cross-sectional view of the through hole portion in the fifth embodiment of the present invention. FIG. 10A is a schematic cross-sectional view of a through hole showing a state before sealing, and FIG. 10B is a schematic cross-sectional view of the through hole showing a state where the through hole is sealed with a sealing material. is there. In the first to fourth embodiments, the first tapered surface and the second tapered surface are formed continuously, but in the fifth embodiment, the first tapered surface 52b and the second tapered surface 52c are In the meantime, an inner peripheral surface 52e perpendicular to the infrared transmission window 52 is formed. The pad 54 is formed on the first tapered surface 52 b and the outer surface 52 a, and the sealing material 55 seals the through hole 53 so as to cover the pad 54. The through hole 53 in the present embodiment can be formed, for example, by further etching the through hole of the first embodiment.

  FIG. 11 shows a schematic partial cross-sectional view of the through hole portion in the sixth embodiment of the present invention. FIG. 11A is a schematic cross-sectional view of the through hole showing a state before sealing, and FIG. 11B is a schematic cross-sectional view of the through hole showing a state where the through hole is sealed with a sealing material. is there. In the present embodiment, the taper angles of the first tapered surface 62b and the second tapered surface 62c are not unified. For example, in the cross-sectional view of FIG. 11, the through hole 63 is such that the left taper angle α1 and the right taper angle α2 of the first taper surface 62b are different. The same applies to the second tapered surface 62c. Such a through-hole 63 can be formed, for example, by using Si as the infrared transmission window 62 and performing anisotropic etching with the outer surface 62a as the (411) plane.

  FIG. 12 shows a schematic partial cross-sectional view of the through hole portion in the seventh embodiment of the present invention. 12A is a schematic cross-sectional view of the through hole showing a state before sealing, and FIG. 12B is a schematic cross-sectional view of the through hole showing a state where the through hole is sealed with a sealing material. is there. In the present embodiment, the first tapered surface 72b and the second tapered surface 72c are not continuous, and the first tapered surface 72b and the second tapered surface 72c are formed by further etching the through hole of the sixth embodiment. An inner peripheral surface 72e is further formed between the two.

  Also in the second embodiment to the seventh embodiment, as described in the first embodiment, the corners forming the through holes (the corners facing the through holes) are obtuse. The pad is formed on the first tapered surface and the outer surface on the outer surface side, and is not formed on the second tapered surface and the inner surface.

  The through holes in the first to seventh embodiments use isotropic etching or dry etching in addition to anisotropic etching, or combine isotropic etching, dry etching, and anisotropic etching. You can also The taper shapes shown in the first to seventh embodiments are merely examples, and the present invention is not limited to these, and through holes having various shapes of tapers can be formed by using substrates and etching methods having various surface orientations. Can be formed.

  Next, vacuum packages according to eighth to eleventh embodiments of the present invention will be described. The eighth embodiment to the eleventh embodiment are different from the first embodiment shown in FIG. 1 in the locations where the through holes are formed and the forms of the chambers.

  A vacuum package according to the eighth embodiment of the present invention will be described. FIG. 13 is a schematic sectional view of a vacuum package according to the eighth embodiment of the present invention. In the first embodiment, the through hole is formed in the infrared transmission window. However, in the vacuum package 200 according to the eighth embodiment, the through hole 213 is formed in the light receiving element substrate 203. Other than that, the vacuum package 200 is the same as the vacuum package according to the first embodiment. Moreover, as the through-hole 213, various forms as described in the first to seventh embodiments can be applied.

  A vacuum package according to a ninth embodiment of the present invention will be described. FIG. 14 is a schematic cross-sectional view of a vacuum package according to the ninth embodiment of the present invention. In the vacuum package 300 according to the ninth embodiment, the through hole 313 is formed in the spacer 309. At least a part of the spacer 309 is formed wide in the same direction as the extending direction of the surface of the infrared transmission film 312 (or the light receiving element substrate 303), and the wide part is exposed to the outside of the infrared transmission film 312. The through hole 313 is formed in the wide part exposed to the outside along the same direction as the thickness direction of the infrared transmission film 312 (perpendicular to the extending direction of the surface). In addition, the pad 308 a and the insulating layer 307 are formed large in accordance with the shape of the spacer 309. Other aspects of the vacuum package 300 are the same as those of the vacuum package according to the first embodiment. Moreover, as the through-hole 313, various forms as described in the first to seventh embodiments can be applied.

  A vacuum package according to a tenth embodiment of the present invention will be described. FIG. 15 is a schematic sectional view of a vacuum package according to the tenth embodiment of the present invention. In the vacuum package 400 according to the tenth embodiment, the through hole 413 is formed in the spacer 409 as in the ninth embodiment. However, in the present embodiment, the spacer 409 extends so as to widen the space (height) of the chamber 406 (the interval between the light receiving element substrate 403 and the infrared transmission window 412), and the through hole 413 is formed on the spacer 409. From the side, it is formed along the same direction (perpendicular to the thickness direction) as the extending direction of the infrared transmission film 412 surface. About another form, it is the same as that of the vacuum package which concerns on 1st Embodiment. Moreover, as the through-hole 413, various forms as described in the first to seventh embodiments can be applied.

  A vacuum package according to the eleventh embodiment of the present invention will be described. FIG. 16 is a schematic cross-sectional view of a vacuum package according to the eleventh embodiment of the present invention. In the first embodiment and the eighth embodiment to the tenth embodiment, the infrared light receiving element is connected to the light receiving element substrate via a bonding material, and the light receiving element substrate forms a part of the chamber. In the vacuum package 500 according to the embodiment, the infrared light receiving element 501 itself forms a part of the chamber 506 without using the light receiving element substrate. Therefore, the electrode pad 504 and the insulating layer 507 are formed on the infrared light receiving element 501. In FIG. 16, the through hole 513 is formed in the infrared transmission window 512, but can also be formed in the spacer 509. About another form, it is the same as that of the vacuum package which concerns on 1st Embodiment. Moreover, as the through-hole 513, various forms as described in the first to seventh embodiments can be applied. According to this embodiment, as compared with the first embodiment and the like, not only electrical connection such as wire bonding becomes unnecessary, but also the vacuum package can be made thinner.

  The first embodiment and the eighth to eleventh embodiments can also be combined. That is, in each embodiment, the through hole is formed in any one of the infrared transmission film, the spacer, and the light receiving element substrate, but the infrared transmission film, the spacer, and the light receiving element substrate are combined in each embodiment. It is also possible to form through holes in a plurality of them.

  Next, a vacuum package according to a twelfth embodiment of the present invention will be described. 17 to 19 are schematic cross-sectional views of a vacuum package according to a twelfth embodiment of the present invention. The vacuum package 600 shown in FIGS. 17 to 19 is the same as the vacuum package according to the first embodiment, except that the chamber 6 has a getter 18 for making the chamber 6 into a high vacuum. It is a point. The getter 18 is provided on the infrared transmission window 12 in the form shown in FIG. 17, is provided on the light receiving element substrate 3 (insulating film 17) in the form shown in FIG. 18, and is on the spacer 9 in the form shown in FIG. Is provided. Or the arrangement | positioning location of the getter 18 can also combine the form shown in FIGS. The getter 18 can be formed of a Zr-based material, a Ti-based material, or an alloy containing them, and the inside of the chamber 6 can be made into a high vacuum by being activated after hermetically sealing the package. Although the vacuum package 600 according to the twelfth embodiment has been described based on the vacuum package according to the first embodiment, it is needless to say that the vacuum package 600 according to the second embodiment to the eleventh embodiment can be applied.

Next, as a thirteenth embodiment of the present invention, a method for forming a through hole in the vacuum package of the present invention will be described. FIG. 20 is a schematic process diagram for explaining a method of forming a through hole in an infrared transmission window, taking the vacuum package according to the first embodiment as an example. First, antireflection films 11a and 11b are formed at predetermined positions with respect to the infrared transmission window 12 (FIG. 20A). Next, a mask or an alkali resistant resist 19 made of SiO ₂ , SiN, SiON, metal, or the like is formed in a portion where the through hole 13 is not formed (FIG. 20B). Next, anisotropic etching using KOH, TMAH (tetramethylammonium hydroxysite), hydrazine, EPW (ethylenediamine-pyrocatechol-water), or the like is performed on both surfaces 12a and 12d of the infrared transmission window 12, respectively. A through-hole 13 having a tapered surface 12b and a second tapered surface 12c is formed (FIG. 20C). Note that isotropic etching may be used to form the through hole 13. Next, the sealing material connecting pad 14 is formed on the first tapered surface 12b and a part of the outer surface 12a continuous with the first tapered surface 12b by sputtering, vapor deposition, plating, or the like (FIG. 20D). Finally, a pad 8b for connecting to the spacer is formed by sputtering, vapor deposition, plating, or the like (FIG. 20E).

  Here, the first embodiment has been described as an example. However, even in the case of the through holes according to the second to seventh embodiments, the etching conditions such as the etching depth and direction can be changed as appropriate. Through holes can be formed by the same method as shown in FIG. Further, in the eighth to eleventh embodiments in which the through hole is formed in the light receiving element substrate or the spacer, the through hole can be formed by the same method as the forming method shown in FIG. In the case where the substrate for forming the through hole is not silicon but a metal or the like, the through hole can be formed by using a photoresist as a mask material and using an acid or an alkali as an etching solution.

  Next, as a fourteenth embodiment to a fifteenth embodiment of the present invention, a method for vacuum-sealing the vacuum package of the present invention will be described. FIG. 21 shows a schematic cross-sectional view for explaining the vacuum sealing method according to the fourteenth embodiment, and FIG. 22 shows a schematic cross-sectional view for explaining the vacuum sealing method according to the fifteenth embodiment. As a vacuum package for vacuum sealing, the vacuum package according to the first embodiment is taken as an example.

In the fourteenth embodiment, first, the package 100 in which the through hole is formed is set on the stage 82 of the vacuum chamber 81. Next, the inside of the vacuum package 81 is evacuated by making the inside of the vacuum chamber 81 high vacuum. For example, in the case of an infrared sensor, the ultimate vacuum is preferably 10 ⁻² Torr or less in order to obtain the minimum performance. In order to maintain the stability of the device for a long period of time, it is desirable to further increase the degree of vacuum. Next, in this state, a sealing material (for example, solder) 15 is set in the through hole of the package 100. Alternatively, as described in the first embodiment, before the vacuum chamber 81 is evacuated, the sealing material 15 may be disposed in the through hole in the atmosphere in advance. Next, the laser beam is irradiated from the outside of the vacuum chamber 81 toward the sealing material 15 through the transmission window 83 of the vacuum chamber 81. As a result, the sealing material 15 is melted and seals the through hole.

  In the fourteenth embodiment shown in FIG. 21, the laser device 84 is installed outside the vacuum chamber 81, but in the fifteenth embodiment shown in FIG. 22, the laser device 84 is installed in the vacuum chamber 81. . In this case, since the sealing material 15 can be directly heated, the transmission window can be omitted. Others are the same as those in the fourteenth embodiment.

  In the method shown in FIGS. 21 and 22, even when the light receiving element substrate / spacer and the spacer / infrared transmitting window are connected by a bonding material such as solder, only the sealing material 15 set in the through hole is used. Since it can be locally heated by the laser device 84, when the melting point of the sealing material 15 for the through hole is equal to or lower than the melting point of the bonding material, only the sealing material for the through hole is dissolved without dissolving the bonding material. Not only can it be melted and vacuum sealed, but even when the melting point of the sealing material 15 is higher than the melting point of the bonding material, if the conditions are optimized, only the sealing material 15 for the through-hole is dissolved. It is also possible to seal. As the laser device 84, a YAG laser is suitable, but any laser capable of heating solder such as a ruby laser, a carbon dioxide gas laser, an excimer laser, a liquid laser, a semiconductor laser, and a free electron laser can be used. Can be used.

  Next, as a sixteenth embodiment of the present invention, a method for vacuum-sealing the vacuum package of the present invention will be described. FIG. 23 is a schematic cross-sectional view for explaining the vacuum sealing method according to the sixteenth embodiment. In the fourteenth and fifteenth embodiments, the sealing material is melted using a laser. In the sixteenth embodiment, the sealing material is melted by heating the entire package. For example, the sealing material 15 can be melted by heating the stage 82 after evacuating the vacuum chamber 81 as in the fourteenth or fifteenth embodiment. When the light receiving element substrate / spacer and the spacer / infrared transmitting window are connected with a bonding material such as solder, the sealing material 15 set in the through hole is used so as not to melt the bonding material. The melting point of is preferably lower than the melting point of the bonding material.

  21 to 23 show the vacuum package according to the first embodiment, but the fourteenth embodiment to the sixteenth embodiment can also be applied to the vacuum packages according to the second to twelfth embodiments. Needless to say.

  Examples of the vacuum package of the present invention will be described. The manufactured vacuum package is a vacuum package used for an infrared sensor as shown in FIG. 1, and has an infrared light receiving element as a functional element. The through hole was formed in the infrared transmission window as in the first embodiment.

First, a silicon substrate with an antireflection film, which is an infrared transmitting window with a size of 16.2 mm × 16.2 mm and a thickness of 0.8 mm, is anisotropic by KOH from both sides of the silicon substrate using SiO ₂ as a mask. Etching was performed to form through holes. As shown in FIG. 2 according to the first embodiment, the formed through hole has the same depth as the first tapered surface and the second tapered surface so that there is a constricted portion at the center in the depth direction. It is a through-hole which becomes symmetrical with respect to the center line. The opening shape of the substrate surface of the through hole was a square, the length of one side was 0.726 mm, and the area was 0.527 mm ² . The sizes of the corners forming the through-holes were α = 15.3 °, β = 109.4 °, and γ = 15.3 °, expressed as α, β, and γ in FIG. . That is, all corners forming the through holes are obtuse. As a result, the size of the constricted portion, which is the narrowest opening area of the through hole, was 0.16 mm on one side and 0.0256 mm ^{2 on} the opening area.

  Next, a Ti / Al layer was formed by sputtering on the surface on the outer surface side (opposite the chamber) of the infrared transmission window and the first tapered surface of the through hole continuous with the surface. The thickness of Ti was 0.1 μm, and Al was 1 μm. Further, Ti / Al was similarly formed on the inner surface side (chamber side) of the infrared transmission window as a pad for connecting to the spacer. The Ti / Al pad was formed so as to surround the infrared light receiving element, and the width thereof was about 1 mm. Thereafter, 3 μm of NiP and 0.05 μm of Au were formed on Ti / Al by electroless plating. Thereafter, the silicon substrate was diced into individual pieces.

  Next, another silicon substrate having a thickness of 1 mm was etched from both sides, so that a spacer having a through hole for enclosing an infrared light receiving element having a size of about 13.8 mm × 13.8 mm was produced in the center. Thereafter, Ti / Al electrode pads having a width of 1 mm were formed on both sides of the spacer surface so as to surround the infrared light receiving element, and NiP of 3 μm and Au of 0.05 μm were formed on the spacer surface by electroless plating. Thereafter, this silicon substrate was diced to 16.2 mm × 16.2 mm.

Next, wiring connecting the inside and outside of the chamber as an electrode pad on the first layer to a silicon substrate as a light receiving element substrate having a size of 18 mm × 18 mm × 0.625 mm, and a width of 1 mm for connecting to the spacer on the second layer The pad was formed. A SiO ₂ insulating layer was formed between the first layer wiring and the second layer pad. The wiring pads were Ti 0.1 μm and Al 1 μm. On top of this, 3 μm of NiP and 0.4 μm of Au were formed by electroless plating. Next, the infrared light receiving element was fixed on the light receiving element substrate with a bonding material, and the electrode pad of the infrared light receiving element substrate and the electrode pad formed on the light receiving element substrate were electrically connected by an Al wire having a diameter of 30 μm.

  Next, a SnAgCu lead-free solder preform material having an outer periphery of 16 mm × 16 mm, a thickness of 200 μm and a width of 1 mm as a bonding material for bonding the spacer, the infrared transmission window, and the light receiving element substrate. Was sandwiched between the infrared transmission window / spacer interface and the spacer / light receiving element substrate interface, and these components were collectively subjected to reflow to melt the solder preform material and bonded together.

Next, after a SnAgCu solder ball having a diameter of 0.6 mm was placed as a sealing material on the through hole of the infrared transmission window, the manufactured component was held in a vacuum chamber of 10 ⁻⁶ Torr. A glass window is formed in the vacuum chamber, and the solder ball is irradiated with an Nd-YAG laser having a wavelength of 1.06 μm (can be a second harmonic of 0.53 μm) from the outside through the glass window. Was melted by heating to seal the through hole. A vacuum package was manufactured by the method as described above.

Therefore, the molecular flow conductance was calculated for the through hole according to the present example. In the present embodiment, the opening area (0.515 mm ² ) of the portion closed by the solder ball is larger than the opening area (0.0256 mm ² ) of the constricted portion that is the smallest opening. Conductance was calculated based on the opening area. The minimum opening area (neck portion) of the through hole according to this example is 0.0256 mm ² , which corresponds to a cylindrical through hole having a diameter of 0.18 mm. Therefore, when the conductance Cp of the viscous flow region in the through hole of D = 0.18 mm and L = 0.8 mm is calculated from the above equation 1, the value is 239 × p (mm ³ / s), and the molecular flow region The conductance Ck is 882 (mm ³ / s) from the above formula 2. Since the capacity of the cavity in the vacuum package is 14 mm × 14 mm × 1.4 mm = 274 mm ³ , it can be seen that, according to the present invention, evacuation can be performed in a short time even in consideration of conductance.

[Comparative Example 1]
A through hole having only a tapered surface in one direction as shown in FIGS. 27 to 29 by performing anisotropic etching only from one side of the infrared transmission window having the same chip thickness of 0.8 mm as in Example 1. Formed. The planar shape of the through hole was a square as in Example 1, and the size of the through hole was 0.16 mm for the narrowest opening area (opening area on one surface) and 0.0256 mm ² for the opening area. That is, the minimum opening area of the through hole was made to be the same as the minimum opening area of the through hole in the through hole according to Example 1. Moreover, one corner | angular part (angle (delta) shown in FIGS. 27-29) which forms a through-hole became 54.7 degrees. As a result, in Comparative Example 1, when a through hole having the same minimum opening area as in Example 1 was formed, the opening having the largest opening area was 1.293 mm on a side and 1.672 mm ^{2 on} the opening area.

[Comparative Example 2]
Similar to Comparative Example 1, an attempt was made to form a through hole having the same maximum opening area as the maximum opening area of the through hole according to Example 1, but the same chip thickness (0.8 mm) and taper angle (54 .7 °), a through hole could not be physically formed.

  Table 1 comparing the through holes in Example 1 and the through holes in Comparative Example 1 and Comparative Example 2 is shown below.

  In Example 1 and Comparative Example 1, through-holes having the same minimum opening area were formed so that the molecular flow conductances were the same. As a result, according to the present invention, the area of the opening (maximum opening area) formed on the surface of the substrate (infrared transmitting window) could be less than 1/3 of the maximum opening area of Comparative Example 1. That is, according to the through hole of the present invention, the vacuum package can be made smaller.

  In the present invention, the second corner portion facing the through hole is 109.5 °, whereas in Comparative Example 1, the corner portion facing the through hole is 54.7. Such acute corners are more susceptible to cracking than the obtuse corners of the present invention, which may reduce the airtightness of the vacuum package. However, according to the present invention, the occurrence of cracks in the through hole portion can be further suppressed.

Furthermore, in Comparative Example 1, when the pad is formed only on the substrate surface as shown in FIGS. 27 and 29 and the pad is not formed on the inner wall of the through hole, the solder has a maximum opening area of 1.672 mm ² . The part must be sealed, and leakage may occur due to incomplete sealing. However, according to the present invention, since the can I seal the portion having the minimum opening area of 0.0256mm ² is about 1.5% of the maximum opening area of comparison example 1, the risk of incomplete sealing large Can be reduced.

  On the other hand, in Comparative Example 1, as shown in FIG. 28, when a pad is formed on the entire inner wall of the through hole, the minimum opening area that must be sealed in Example 1 and Comparative Example 1 is the same. However, in Comparative Example 1, the solder spreads over the entire through hole, and the portion of the minimum opening area of the through hole is formed on the inner surface facing the chamber, so that the solder protrudes into the chamber or the whisker enters the chamber. There is a risk. However, according to the present invention, the pad is formed only on the first tapered surface, and the constricted portion having the minimum opening area is located 0.4 mm away from the inner surface facing the chamber. Can greatly reduce the risk of entering.

  In this specification, there is a place where “Torr” is used as a unit of pressure for convenience, but “Torr” can be converted to SI unit at 1 Torr = 133.3 Pa.

  Although this invention was demonstrated based on the said embodiment, it cannot be overemphasized that a various change, a deformation | transformation, improvement, etc. are included in the scope of the present invention, without being limited to the said embodiment. Further, various combinations, substitutions or selections of the disclosed elements are possible within the scope of the present invention.

  Further problems, objects, and developments of the present invention will become apparent from the entire disclosure of the present invention including the claims.

  According to a preferred form of the first aspect, the vacuum package includes a functional element sealed in the chamber whose pressure is reduced from the atmospheric pressure, and a member that forms at least a part of the chamber. The member has at least one through hole for degassing the inside of the chamber. In a cross section perpendicular to the member along the through hole, the corner of the member forming the through hole is an obtuse angle, and the through hole is sealed. Sealed with a stop material.

  According to the preferable form of the first aspect, the inner wall of the through hole is formed with a first tapered surface that reduces the opening area of the through hole from the outer surface side of the chamber toward the inner surface side, and from the inner surface side of the chamber toward the outer surface side. And a second taper surface that reduces the opening area of the through hole, and the first taper surface is formed on the outer surface side of the chamber with respect to the second taper surface.

  According to the preferable form of the first aspect, the pad having higher wettability than the member with respect to the sealing material is formed only on the first tapered surface of the inner wall of the through hole.

  According to the preferable form of the first viewpoint, the first tapered surface and the second tapered surface are formed continuously.

  According to the preferable form of the first aspect, the sealing material does not protrude from the through hole into the chamber.

  According to a preferred form of the first aspect, the functional element is an infrared light receiving element, and the chamber is configured so that the infrared light receiving element can receive at least a light receiving element substrate on which the infrared light receiving element is mounted and infrared light from outside the chamber. And a member that forms a predetermined gap between the light receiving element substrate and the infrared transmitting window, and the member that forms the through hole includes a light receiving element substrate, an infrared transmitting window, and an infrared transmitting window. At least one of the spacers.

  According to a preferred form of the first aspect, the method for manufacturing a vacuum package is a method for manufacturing a vacuum package in which a functional element is sealed in a chamber whose pressure is reduced from atmospheric pressure, and at least a part of the chamber is formed. A cylindrical first taper surface with a reduced opening area is formed from one surface of the member, and a cylindrical second taper surface with a reduced opening area is formed from the other surface of the member. Thus, a functional element is accommodated by degassing from the through-hole forming step of forming a through-hole for degassing the inside of the chamber having at least the first tapered surface and the second tapered surface on the inner wall. A degassing step of reducing the pressure in the chamber and a sealing step of sealing the through hole with a sealing material. In the through hole forming step, the through hole penetrates in a cross section perpendicular to the member along the through hole. Shape a hole Corners of the members is formed to be an obtuse angle.

  According to the preferable form of the first aspect, the wettability of the sealing material to the sealing material is higher than that of the member on the first tapered surface disposed outside the second tapered surface after the through hole forming step. A pad forming step for forming a high-quality pad, and in the sealing step, the sealing material placed on the pad of the first taper surface or the opening of the through hole formed on one surface of the member is melted By doing so, the through hole is sealed.

  According to the preferred form of the first aspect, in the deaeration step, the sealing material is applied to the pad of the first taper surface or the opening of the through hole formed in one surface of the member before the pressure reduction in the chamber. The chamber is depressurized from the gap formed between the sealing material and the through hole, and the inside of the chamber is depressurized, and then the sealing material is melted to seal the through hole.

  According to the preferred form of the first aspect, after the pressure in the chamber is reduced in the sealing step, the sealing material is applied on the pad of the first tapered surface or the opening of the through hole formed on one surface of the member. The through hole is sealed by mounting and melting the sealing material.

  According to a preferred form of the first aspect, the vacuum package includes a functional element sealed in the chamber whose pressure is reduced from the atmospheric pressure, and a member that forms at least a part of the chamber. The member has at least one through hole for degassing the inside of the chamber. In the cross section perpendicular to the member along the through hole, the corner of the member forming the through hole is an obtuse angle. The through hole is sealed with a sealing material. The inner wall of the through hole has a first tapered surface that reduces the opening area of the through hole from the outer surface side to the inner surface side of the chamber, and a second taper that reduces the opening area of the through hole from the inner surface side to the outer surface side of the chamber. And a tapered surface. The first tapered surface is formed closer to the outer surface of the chamber than the second tapered surface. The depth of the through hole in the second tapered surface portion is equal to or greater than the depth of the through hole in the first tapered surface portion.

  According to a preferred form of the first aspect, the vacuum package includes a functional element sealed in the chamber whose pressure is reduced from the atmospheric pressure, and a member that forms at least a part of the chamber. The member has at least one through hole for degassing the inside of the chamber. In the cross section perpendicular to the member along the through hole, the corner of the member forming the through hole is an obtuse angle. The through hole is sealed with a sealing material. The inner wall of the through hole has a first tapered surface that reduces the opening area of the through hole from the outer surface side to the inner surface side of the chamber, and a second taper that reduces the opening area of the through hole from the inner surface side to the outer surface side of the chamber. And a tapered surface. The first tapered surface is formed closer to the outer surface of the chamber than the second tapered surface. In the cross section passing through the through hole, the center line of the through hole in the first tapered surface portion does not coincide with the center line of the through hole in the second tapered surface portion.

  According to a preferred form of the first aspect, the vacuum package includes a functional element sealed in the chamber whose pressure is reduced from the atmospheric pressure, and a member that forms at least a part of the chamber. The member has at least one through hole for degassing the inside of the chamber. In the cross section perpendicular to the member along the through hole, the corner of the member forming the through hole is an obtuse angle. The through hole is sealed with a sealing material. The inner wall of the through hole has a first tapered surface that reduces the opening area of the through hole from the outer surface side to the inner surface side of the chamber, and a second taper that reduces the opening area of the through hole from the inner surface side to the outer surface side of the chamber. And a tapered surface. The first tapered surface is formed closer to the outer surface of the chamber than the second tapered surface. In the cross section passing through the through hole, one taper angle and the other taper angle of the first taper surface are different, and one taper angle and the other taper angle of the second taper surface are different.

  According to the preferable form of the first viewpoint, the first tapered surface and the second tapered surface are formed continuously.

  According to a preferred form of the first aspect, the vacuum package includes a functional element sealed in the chamber whose pressure is reduced from the atmospheric pressure, and a member that forms at least a part of the chamber. The member has at least one through hole for degassing the inside of the chamber. In the cross section perpendicular to the member along the through hole, the corner of the member forming the through hole is an obtuse angle. The through hole is sealed with a sealing material. The inner wall of the through hole has a first tapered surface that reduces the opening area of the through hole from the outer surface side to the inner surface side of the chamber, and a second taper that reduces the opening area of the through hole from the inner surface side to the outer surface side of the chamber. And a tapered surface. The first tapered surface is formed closer to the outer surface of the chamber than the second tapered surface. The first taper surface and the second taper surface are not continuous.

  According to a preferred form of the first aspect, the vacuum package includes a functional element sealed in the chamber whose pressure is reduced from the atmospheric pressure, and a member that forms at least a part of the chamber. The member has at least one through hole for degassing the inside of the chamber. In the cross section perpendicular to the member along the through hole, the corner of the member forming the through hole is an obtuse angle. The through hole is sealed with a sealing material. The inner wall of the through hole has a first tapered surface that reduces the opening area of the through hole from the outer surface side to the inner surface side of the chamber, and a second taper that reduces the opening area of the through hole from the inner surface side to the outer surface side of the chamber. And a tapered surface. The first tapered surface is formed closer to the outer surface of the chamber than the second tapered surface. The first taper surface and the second taper surface are not continuous. In the cross section passing through the through hole, one taper angle and the other taper angle of the first taper surface are different, and one taper angle and the other taper angle of the second taper surface are different.

  According to the preferred form of the first aspect, the planar shape of the through hole is a circle, an ellipse, a cross, or a polygon.

  According to the preferable form of the first aspect, the pad having higher wettability than the member with respect to the sealing material is formed on the first tapered surface of the inner wall of the through hole.

  According to the preferable form of the first aspect, the sealing material does not protrude from the through hole into the chamber.

  According to a preferred embodiment of the first aspect, the functional element is an infrared light receiving element. The chamber includes at least a light receiving element substrate on which the infrared light receiving element is mounted, an infrared transmitting window that transmits infrared light so that the infrared light receiving element can receive infrared light from outside the chamber, and a space between the light receiving element substrate and the infrared transmitting window. And a spacer for forming a predetermined gap. The member that forms the through hole is at least one of the light receiving element substrate, the infrared transmission window, and the spacer.

  According to the vacuum package and the manufacturing method thereof, the constricted portion having the minimum area is formed in the middle of the through hole, so that the through hole having a large conductance can be formed without requiring a large opening area. As a result, the vacuum package can be reduced in size, and the vacuum package can be highly vacuumed and vacuumed for a short time.

  Moreover, according to the said vacuum package and its manufacturing method, since the corner | angular part of a through-hole part is an obtuse-angle shape, even if it uses a fragile member, generation | occurrence | production of the crack in the corner | angular part of a through-hole part can be suppressed. . Thereby, the airtightness of a vacuum package can be improved.

  Furthermore, according to the vacuum package and the manufacturing method thereof, the sealing material or whisker can penetrate into the chamber by forming the sealing material pad only on the first tapered surface of the inner wall of the through hole. Can be prevented. Thereby, a malfunction and an electrical short can be prevented. Also, the through hole can be sealed at the minimum opening area. Thereby, generation | occurrence | production of the sealing defect can be prevented.

  In the above embodiment, the vacuum package related to the infrared sensor using the infrared light receiving element as the functional element has been described. However, the functional element of the present invention is not limited to the infrared light receiving element, and a vacuum such as a piezoelectric element or a vibration element is used. Various functional elements that require sealing can be applied to the present invention. That is, it goes without saying that the vacuum package of the present invention can be applied to a pressure sensor and an acceleration sensor in addition to the infrared sensor.

100, 200, 300, 400, 500, 600 Vacuum package 1, 201, 301, 401, 501 Functional element (infrared light receiving element)
2, 202, 302, 402, 502 Bonding material 3, 203, 303, 403, 503 Light receiving element substrate 4, 204, 304, 404, 504 Electrode pads 5, 205, 305, 405, 505 Bonding wires 6, 206, 306 , 406, 506 Chamber 7, 207, 307, 407, 507 Insulating layer 8a, 8b, 208a, 208b, 308a, 308b, 408a, 408b, 508a, 508b, pad 9, 209, 309, 409, 509 Spacer 10a, 10b , 210a, 210b, 310a, 310b, 410a, 410b, 510a, 510b Bonding materials 11a, 11b, 211a, 211b, 311a, 311b, 411a, 411b, 511a, 511b, antireflection films 12, 22, 32, 42, 52 62, 72, 212 , 312, 412, 512 Infrared transmitting windows 12 a, 22 a, 32 a, 42 a, 52 a, 62 a, 72 a, 203 a, 309 a, 409 a, 512 a External surface 12 b, 22 b, 32 b, 42 b, 52 b, 62 b, 72 b, 203 b, 309 b, 409 b 512b First tapered surface 12c, 22c, 32c, 42c, 52c, 62c, 72c, 203c, 309c, 409c, 512c Second tapered surface 12d, 22d, 32d, 42d, 52d, 62d, 72d, 203d, 309d, 409d 512d Inner surfaces 52e, 72e Inner peripheral surfaces 13, 23, 33, 43, 53, 63, 73, 2, 3, 4, 5 Through holes 13a, 23a, 33a, 43a, 53a, 63a, 73a, 2, 3, 4,5 Constriction 14, 24, 34, 44, 54, 64, 74, 213, 313 413, 513 Pad 15, 25, 35, 45, 55, 65, 75, 215, 315, 415, 515 Sealing material 16, 216, 316, 416, 516 Electrode pad 17, 217, 317, 417, 517 Insulating layer 18 Getter 19 Resist 81 Vacuum chamber 82 Stage 83 Transmission window 84 Laser device 901 Substrate 902 Light receiving portion 903 Air gap 904 Infrared transmission window 905 Solder 906 Metallized layer 907 Wiring 908 Silicon oxide protective film 909 Pad 910 Antireflection film 911 Through hole 912 Sealing Material (Vacuum sealing solder)
913 Vacuum sealing metallized layer 921 Element 922 Element forming substrate body 923 Lid substrate body 924 Cavity 925 Space 926 Hole 927 Through hole 928 Electrode pattern 929 Communication hole 930a Small diameter opening 930b Small diameter opening upper edge 931 Sealing member 932 Constriction portion 933 Sealing bonding reinforcing film 941, 951 Member 941a First opening 941b Second opening 942, 952 Sealing material pads 943, 953 Through hole 944, 954 Sealing material 954a Projecting sealing material 945, 955 Corner

Claims (2)

Setting a package in which a through hole is formed in a vacuum chamber having a transmission window;
Reducing the pressure in the vacuum chamber;
Arranging a sealing material in the through hole;
Irradiating the sealing material with a laser from outside the vacuum chamber through the transmission window, and sealing the through hole;
The manufacturing method of the vacuum package characterized by including.   2. The method of manufacturing a vacuum package according to claim 1, further comprising a step of arranging the sealing material in the through hole before decompressing the inside of the vacuum chamber.

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