JP2001057436A - Hermetically sealed package and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a low profile package by bonding the upper surface of a first recessed substrate having an electrode on the bottom directly to the bottom face of a second substrate being covered from above and pressing a device element thereby deforming a protrusion electrode on the element electrode and pressing the substrate electrode. SOLUTION: First and second substrates 3, 6 are cleaned in order to provide a substrate electrode 4 on the inner bottom of a recess for direct bonding. A device element 1 having a protrusion electrode 5 on an element electrode 2 is then face-down inserted into the first substrate 3. The protrusion electrode 5 is formed of a metallic material on the element electrode 2 by plating and the second substrate 6 to be sealed is set from above while being pressed. Consequently, the protrusion electrode 5 is collapsed and the upper surface of the first substrate 3 can touch the bottom face of the second substrate 6. Subsequently, the interface at a joint being heat treated while being pressed is bonded at atomic level. Since resilient repelling force of the protrusion electrode 5 is present, the element electrode 2 and the substrate electrode 4 are sustained in bonded state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hermetically sealed package for a device requiring hermetic sealing and a method for manufacturing the same.

[0002]

2. Description of the Related Art SAW devices, infrared sensors, etc.
The characteristics change when an object touches the surface of the element or when the gas to be hermetically sealed changes. In an SAW device, when an object adheres to an electrode on the element surface, the resonance frequency changes depending on its mass. In addition, the output of the infrared sensor varies depending on the thermal conductivity of the gas to be hermetically sealed, and the reliability deteriorates due to moisture in the atmosphere. Therefore, these device elements require a hermetically sealed package which is required to prevent the surface of the element from touching other than the gas to be hermetically sealed. CA as conventional hermetic sealing package
There are N-sealed packages and ceramic packages.

FIG. 4 shows a conventional CAN sealed package. A device element 50 such as a SAW device or an infrared sensor element is attached on the stem 54 with a die bonding resin 57 which is an organic resin. The SAW device or the like has a comb-shaped electrode provided on a piezoelectric single crystal such as quartz or LiTaO ₃ , and the infrared sensor has a pyroelectric body provided with an electrode. A wire bonding method is used to connect the wires 56, and the element electrodes and the pins 55 for taking out the electrodes are connected by thin wires of Al or Au. As the element electrode 51, an electrode capable of wire bonding is used. For example, Al, Au, Pt, or a laminated electrode thereof. The CAN 58 and the stem 54 are welded by applying a high voltage to the joint. In an infrared sensor or the like, silicon 59 is bonded on CAN 58 so as to transmit infrared light. At this time, silicon 59 and CAN 58
Are bonded with solder 60, glass frit, or the like so as to maintain airtightness. Sealing gas 5 sealed in CAN 58
3 is filled with a chemically stable gas such as nitrogen. In addition, an inert gas such as xenon or krypton having low thermal conductivity may be sealed in order to improve sensitivity.

[0004]

The conventional CAN sealed package and ceramic package have a problem that a space for wire bonding is required, so that the height and the size cannot be reduced.

An object of the present invention is to solve these problems and to provide a hermetically sealed package having a small size and a low profile and a method of manufacturing the same.

[0006]

In order to achieve the above object, the present invention comprises a device element having a protruding electrode on an element electrode and an electrode on a bottom portion for taking out a substrate electrode coinciding with the element electrode to the outside. A concave first substrate;
A second substrate for inserting the device element so that the protruding electrode and the substrate electrode are aligned with the recessed portion of the substrate, and covering the device from above, and an upper surface of the first substrate and a second substrate The device element is pressurized by the bonding force by directly bonding the device element and the projecting electrode on the element electrode is deformed through the device element, thereby pressing the projecting electrode against the substrate electrode, and The electrodes are electrically and mechanically joined.

According to the present invention, a compact, low-profile, highly reliable hermetically sealed package can be constructed without using wire bonding or an organic resin, and a low-cost hermetically sealed package can be formed by batch processing of works. Is possible.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention has a device element having a protruding electrode on an element electrode and an electrode on a bottom portion for taking out a substrate electrode coincident with the element electrode to the outside. A first substrate having a concave shape, and a second substrate for inserting the device element into the concave portion of the first substrate so as to match the projecting electrode and the substrate electrode, and covering the device element from above. , An upper surface of the first substrate and a second
By directly bonding the bottom surface of the substrate to the device element and pressurizing the device element by the bonding force to deform the projecting electrode on the element electrode via the device element, the projecting electrode is applied to the substrate electrode. Pressurized to electrically and mechanically join the element electrode and the substrate electrode,
When using a hermetic sealing package for elements such as SAW devices, wire bonding and organic resin are not used, so a compact, low-profile, highly reliable hermetic sealing package can be constructed, and a large number of substrates are used. In addition, since the workpieces can be batch-processed by directly joining them together, there is an effect that a low-cost hermetically sealed package can be formed.

According to a second aspect of the present invention, the first substrate having a substrate electrode at the bottom of the concave recess portion and the flat second substrate are cleaned to activate the surface, and the first substrate is activated. A device element having a protruding electrode on a device electrode is inserted into the recessed portion of the device so that the protruding electrode and the substrate electrode match, and the bottom of the inserted device element is higher than the uppermost surface of the first substrate. And the depth of the depression of the first substrate is set in advance so that the height from the top surface of the first substrate to the bottom of the device element is lower than that of the protruding electrode. Is pressed from above and below so that the uppermost surface of the second substrate and the lower surface of the second substrate coincide with each other to deform the protruding electrodes, thereby electrically and mechanically joining the element electrodes and the substrate electrodes. Heating with pressure,
The uppermost surface of the first substrate is directly joined to the lower surface of the second substrate by raising the temperature. Since no wire bonding or organic resin is used, a small, low-profile, highly reliable hermetic sealing package is used. Can be configured. In addition, since the work batch processing can be performed, there is an effect that a low-cost hermetically sealed package can be configured.

According to a third aspect of the present invention, the device element of the second aspect is an infrared sensor element, an oxide film is formed on a silicon substrate, and a substrate electrode is formed on the oxide film.
An oxide film on the silicon substrate in a region through which the infrared light passes is removed so that the infrared light reaches the infrared light receiving portion of the infrared sensor element through the silicon substrate, and the silicon substrate and the frame-shaped substrate are removed. The concave first substrate is formed by bonding with a glass sealing material or the like. The hermetic sealing packaging of the infrared sensor element that requires an infrared transmission window, that is, a silicon window, is small and low-profile. In addition, it is possible to effectively utilize silicon, which is a highly reliable infrared transmission window, by using a semiconductor device, and has an effect of being inexpensive.

According to a fourth aspect of the present invention, after the uppermost surface of the first substrate and the lower surface of the second substrate are matched with each other, a first flat substrate is formed on the rear surface of the first substrate. A rubber material is provided, a flat second rubber material is provided on the upper surface of the second substrate, and a second rubber material is sandwiched between the first rubber material and the second rubber material.
Two rigid bodies are installed, and the two rigid bodies are pressed from above and below to deform the protruding electrodes, thereby electrically and mechanically joining the element electrode and the substrate electrode. The upper surface of the first substrate and the lower surface of the second substrate are directly joined by increasing the temperature. Even with a large number of large-sized substrates, the undulations and thickness variations of the substrates are absorbed by the rubber material. Since a uniform pressure can be applied to each element, there is no need to polish the substrate to a uniform thickness, and an airtight package capable of batch processing of workpieces with an inexpensive substrate can be configured. Having.

According to a fifth aspect of the present invention, a metal thin film is formed on either the uppermost surface of the first substrate or the rear surface of the second substrate. Instead of directly bonding the bottom surface of the substrate 2, anodic bonding is performed, and the problem of poor bonding that occurs when cleaning during the direct bonding process is inadequate is because sufficient bonding strength can be obtained with anodic bonding It has the effect of being improved.

Embodiment 1 Hereinafter, a method for manufacturing a hermetically sealed package according to Embodiment 1 of the present invention will be described with reference to the drawings.

FIG. 1 is a view for explaining a method of manufacturing a hermetically sealed package according to an embodiment of the present invention.

First, as shown in FIG. 1A, the first substrate 3 and the second substrate 6 are cleaned for direct bonding. The first substrate 3 has a concave shape, and a substrate electrode 4 is provided on the inner bottom of the concave shape. The first substrate 3 is formed by bonding a flat substrate having a substrate electrode 4 and a frame-shaped substrate with sealing glass or the like. The substrate electrode 4 is formed by a method such as vacuum evaporation or a method such as printing or baking. At this time, the substrate electrode 4 and the glass-bonded portion must be made of a material having a dense structure so that airtight leakage does not occur later. The material of the first substrate 3 is an insulative substrate that can be directly bonded, such as glass, quartz, or quartz.

Next, as shown in FIG. 1B, the device element 1 having the projecting electrode 5 on the element electrode 2 is inserted face down into the first substrate 3. The device element 1 is an element requiring hermetic sealing such as various sensors and SAW devices. These device elements 1 are hermetically sealed packages that are required to prevent the surface of the element from touching other than the gas that is hermetically sealed. The protruding electrode 5 is formed of a material such as metal on the element electrode by plating or the like.

Next, as shown in FIG. 1C, a second substrate 6 to be sealed is placed while being pressed from above. At this time, the depth of the recessed first substrate 3 where the device element 1 is inserted is set to be deeper than the element thickness and shallower than the height from the bottom surface of the element to the protruding electrode 5. In other words, the projection electrode 5 is crushed and deformed by pressing, so that the upper surface of the first substrate 3 and the bottom surface of the second substrate 6 can be in contact with each other. Since the first substrate 3 and the second substrate 6 have been cleaned and their surfaces have been activated in advance, they are joined by a hydrogen bonding force. In this state, the bonding interface has a weak bonding force. However, the bonding interface is bonded at an atomic level by performing heat treatment while applying pressure. Even if the pressurization is subsequently released, the direct bonding interface maintains good bonding, and a repulsive force due to the elastic force of the protruding electrode 5 exists.
Can maintain an electrical and mechanical coupling force with the substrate electrode 4 via the protruding electrode 5. In order to alleviate the stress due to the difference in the coefficient of thermal expansion during the heat treatment, the first substrate 3 is desirably made of the same material as the substrate of the device element 1 to be inserted or a material having a similar coefficient of thermal expansion. In order to maintain the coupling force between the electrodes due to the elastic force, the protruding electrode 5 is preferably made of a soft and elastic metal such as Au. Also, Au bump electrodes and the like can be formed by applying a method such as wire bonding. However, when a large number of bump electrodes are arranged and used in batch processing, the total load applied to deform the bump electrodes 5 becomes large. The smaller the diameter is, the better.

As described above, since air-tight packaging is performed without using wire bonding or an organic resin, a compact, low-profile, highly reliable hermetic sealing package can be constructed. In addition, after a large number of substrates are directly bonded together in a lump, they can be divided into individual pieces. That is, by performing the batch processing of the workpieces, the number of processes can be reduced as compared with the case where the workpieces are processed individually, so that a hermetically sealed package that is inexpensive and easy to manufacture can be realized.

If the first substrate and the second substrate are made of a glass material, a good and highly reliable hermetic seal can be formed at a low cost. This is because, although the glass material has an amorphous structure, the diffusion of OH groups easily diffuses into the bulk, so that good direct bonding can be performed at a very low temperature.
Inexpensive because the glass substrate has very good surface flatness without polishing. Since the thermal expansion coefficient of the glass material greatly changes depending on the composition therein, a material suitable for the thermal expansion coefficient of each device element can be selected.

In the above method for manufacturing a hermetically sealed package, it is preferable that the upper surface of the concave first substrate
Manufacturing a hermetically sealed package characterized in that a metal thin film is formed on one of the back surfaces of the substrates and anodically bonded instead of directly bonding the upper surface of the first substrate and the bottom surface of the second substrate. As a method, a similar hermetically sealed package can be formed. According to this method, although the number of steps for forming a metal thin film increases, the problem of poor bonding that occurs when cleaning during the direct bonding step is insufficient is insufficient even with insufficient cleaning due to electrochemical action in anodic bonding. There is an effect that joining strength can be obtained.

(Embodiment 2) FIG. 2 is a sectional view of a hermetically sealed package according to a second embodiment of the present invention.
31 is an infrared sensor element, 32 is an element electrode, 33 is a glass frame, 34 is a substrate electrode, 35 is a protruding electrode, and 36 is a second
, 37 is an infrared receiving section, 38 is an insulating film, and 39 is a silicon substrate. An infrared sensor is one of the sensors requiring a hermetically sealed package. This is because the sensitivity of the infrared sensor depends on the thermal conductivity of the sealing gas and the sensitivity also changes with humidity. When the hermetically sealed package of this infrared sensor is shown in Embodiment 1, it must have a substrate configuration as shown in FIG. First, an insulating film 38 is formed on a silicon substrate 39. As the insulating film 38, a film such as a silicon oxide film or silicon nitride is easily formed. Next, the insulating film 38 is removed only in the infrared transmission region so as to transmit infrared light. The insulating film 38 is removed by a photolithography and etching method generally used in a semiconductor process or the like. Then, the substrate electrode 34 is formed on the insulating film 38. The substrate electrode 34 is formed by a method such as vacuum evaporation or a method such as printing or baking. After that, the glass frame 33 is attached to the silicon substrate. This attachment is performed using a glass sealing material or the like. Thus, the first substrate described in Embodiment 1 is formed. Subsequent steps are the same as the steps described in the first embodiment.

As described above, the hermetically sealed packaging of the infrared sensor element 31 requiring an infrared transmission window, ie, a silicon window, can be realized with a small size, a low profile, and high reliability. Moreover, since an expensive silicon substrate, which is an infrared transmission window, can be used in a very small area, there are effects such as low cost.

(Embodiment 3) FIG. 3 is a sectional view of a hermetically sealed package according to Embodiment 3 of the present invention. 41 is a device element, 42 is a protruding electrode, 43 is a substrate electrode, 44 is a first substrate, 45 is a second substrate, 46
Is a first rubber material, 47 is a second rubber material, and 48 is a rigid body. In the method described in the first or second embodiment, when a case is considered in which a large number of substrates are directly joined together at once, the substrate area is increased. Then
Due to undulation or thickness variation of the substrate, the pressure to be applied may not be uniformly applied to each device element. If pressure is not uniformly applied to each device element, FIG.
As shown in (1), a gap is generated in the direct bonding portion, so that a bonding failure occurs. Therefore, as shown in FIG. 3B, after the uppermost surface of the first substrate 44 and the lower surface of the second substrate 45 are matched, a flat first rubber material is formed on the rear surface of the first substrate 44. 46
Is installed, a flat second rubber member 47 is installed on the upper surface of the second substrate 45, and two rigid bodies are installed so as to sandwich the first rubber member 46 and the second rubber member 47 therebetween. By pressing this rigid body, pressure is uniformly applied to each device element. The rubber material is preferably a heat-resistant polyimide or Teflon.

[0024]

According to the above invention, when packaging various sensor elements and SAW devices in a hermetically sealed manner, since no wire bonding or organic resin is used, a small size, low profile and high reliability are achieved. Airtightly sealed package can be configured. In addition, after a large number of substrates are directly bonded together in a lump, they can be divided into individual pieces. That is, by performing the batch processing of the workpieces, the number of processes can be reduced as compared with the case where the workpieces are processed individually, so that a hermetically sealed package that is inexpensive and easy to manufacture can be realized.

[Brief description of the drawings]

FIG. 1 illustrates a method for manufacturing a hermetically sealed package according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a hermetically sealed package according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of a hermetically sealed package according to a third embodiment of the present invention.

FIG. 4 is a cross-sectional view of a conventional CAN sealed package.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 device element 2 element electrode 3 first substrate 4 substrate electrode 5 protruding electrode 6 second substrate

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takeshi Masutani 1006 Kazuma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. F term (reference) 5F044 KK01 LL15 QQ01 5F088 BA15 BA16 BA18 BA20 BB10 FA09 JA01 JA05 JA09 LA01

Claims (5)

[Claims] 1. A device element having a protruding electrode on an element electrode, a concave first substrate having an electrode on a bottom portion for taking out a substrate electrode coincident with the element electrode, A second substrate for inserting the device element into the recessed portion so as to match the projecting electrode and the substrate electrode, and covering the device element from above; a top surface of the first substrate and a second substrate By directly bonding the bottom surface and pressing the device element by the bonding force and deforming the projecting electrode on the element electrode through the device element, the projecting electrode is pressed against the substrate electrode, A hermetically sealed package in which the device electrode and the substrate electrode are electrically and mechanically joined. 2. A first substrate having a substrate electrode at the bottom of a concave recess and a flat second substrate are cleaned to activate the surface, and a device electrode is provided on the recess of the first substrate. A device element having a protruding electrode is inserted so that the protruding electrode and the substrate electrode coincide with each other, and the bottom of the inserted device element is higher than the uppermost surface of the first substrate and the first substrate The depth of the depression of the first substrate is set in advance so that the height from the uppermost surface of the device element to the bottom of the device element is lower than that of the projecting electrode, and the uppermost surface of the first substrate is Pressing from above and below so as to match the lower surface of the substrate to deform the protruding electrode to electrically and mechanically join the element electrode and the substrate electrode, and to heat and raise the temperature while pressing. By the first
A method for manufacturing a hermetically sealed package in which the uppermost surface of the substrate is directly joined to the lower surface of the second substrate. 3. The device element is an infrared sensor element,
Forming an oxide film on a silicon substrate, forming a substrate electrode on the oxide film, so that infrared rays reach the infrared light receiving portion of the infrared sensor element through the silicon substrate,
Forming a concave first substrate by removing an oxide film on the silicon substrate in a region through which infrared light passes, and forming the silicon substrate and a frame-shaped substrate by bonding with a glass sealing material or the like; Item 3. A method for manufacturing a hermetically sealed package according to Item 2. 4. When the uppermost surface of the first substrate and the lower surface of the second substrate coincide with each other, a first rubber material having a flat plate shape is provided on the rear surface of the first substrate, and the upper surface of the second substrate is provided. A second rubber material having a flat plate shape is installed on the second rubber material, and two rigid bodies are further provided so as to sandwich the first rubber material and the second rubber material. The element electrode and the substrate electrode are electrically and mechanically joined by being deformed, and the rigid body is heated and heated while being pressed, so that the uppermost surface of the first substrate and the lower surface of the second substrate are directly contacted. The method for manufacturing a hermetically sealed package according to claim 2, wherein the package is joined. 5. Instead of forming a metal thin film on either the top surface of the first substrate or the back surface of the second substrate and directly joining the top surface of the first substrate and the bottom surface of the second substrate, 3. The method for manufacturing a hermetically sealed package according to claim 2, wherein anodic bonding is performed.