JP3405179B2 - Method for forming metallized layer of pedestal for semiconductor pressure sensor and method for manufacturing metallizing jig - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a metallized layer of a semiconductor pressure sensor pedestal formed by joining a semiconductor pressure sensor chip having a diaphragm and a pedestal, and a method for manufacturing a metallizing jig. is there.

[0002]

2. Description of the Related Art Generally, a semiconductor pressure sensor measures a pressure in a low pressure region, and as shown in FIG. 7, a semiconductor pressure sensor having a diaphragm 11 formed in a thin shape by forming a recess. Chip 1 is glass pedestal 2
To the center by anodic bonding, etc.
PPS or PBT with metal pipe 4 such as 2 alloy
Etc. are installed in the plastic package 3. The aluminum pad on the surface of the semiconductor pressure sensor chip 1 and the lead 5 are connected by a wire 6 made of gold or aluminum. In addition, 7
Is a lid of the plastic package 3, 12 is a strain gauge resistor formed on the semiconductor pressure sensor chip 1, and 13 is an overcoat for protecting the surface of the semiconductor pressure sensor chip 1. As the material of the glass pedestal 2,
For example, Pyrex glass (made by Corning, product number # 7
740) is used.

A through hole 21 for applying pressure to the diaphragm 11 of the semiconductor pressure sensor chip 1 is formed in the center of the glass pedestal 2, and the glass pedestal 2 has this through hole 2
1 and the through hole 41 of the metal pipe 4 are arranged to face each other and are joined to the metal pipe 4. In order to bond the glass pedestal 2 and the metal pipe 4, the metallization layer 8 is formed on the surface of the glass pedestal 2 which is not bonded to the semiconductor pressure sensor chip 1.
Is formed.

To form the metallized layer 8 on the glass pedestal 2, first, as shown in FIG. 8A, the surface on which the metallized layer 8 is to be formed is roughened, and then, as shown in FIG. 8B. As shown in FIG. 3, the glass pedestal 2 is placed in close contact with the flat plate 10, and the metallized layer 8 is formed on the surface roughened by sputtering or vapor deposition. Examples of the metallized layer 8 include Cr (lowermost layer) / Ni / Au (uppermost layer), Ti
(Bottom layer) / Ni / Au (top layer), Ti (bottom layer) /
Examples include Pt / Au (uppermost layer). After that, FIG.
As shown in (c), the glass pedestal 2 is attached to the flat plate 10
Remove from.

Then, the metal pipe 4 and the glass pedestal 2 are joined by a solder (tin, tin-antimony alloy, lead, tin-lead alloy, gold-silicon alloy, tin-silver alloy, etc.) 9 via the metallized layer 8. To be done. A of the uppermost layer of the metallized layer 8
Solder 9 can be applied to the surface of u.

[0006]

However, according to the method of forming the metallized layer 8 on the glass pedestal 2 as described above, the surface of the glass pedestal 2 which is in contact with the flat plate 10 is not metallized. However, the metal particles adhere to the inner wall of the through hole 21 and the metallized layer 8 is formed.

When the metallized layer 8 is formed on the inner wall of the through hole 21, as shown in FIG. 9, when the glass pedestal 2 and the semiconductor pressure sensor chip 1 are anodically bonded, a high temperature (about 300 to 400 ° C.) is obtained. ), High bias (about 50
Since 0 V to 800 V) is applied, between the portion of the bonding surface of the semiconductor pressure sensor chip 1 with the glass pedestal 2 near the through hole 21 and the metallization layer 8 formed on the upper end of the inner wall of the through hole 21. However, there is a problem in that the semiconductor pressure sensor chip 1 is destroyed due to discharge.

In order to solve such a problem, there is a method of filling the through hole 21 of the glass pedestal 2 with the wax 20 when forming the metallized layer 8 as shown in FIG. That is, as shown in FIG. 10A, the surface on which the metallization layer 8 is to be formed is roughened, and the glass pedestal 2 is placed in close contact with the flat plate 10 as shown in FIG. 10B. At this stage, the through hole 21 is filled with the wax 20. The wax 20 used is one that melts with heat of about 100 ° C. to 150 ° C., but the type of the wax 20 may be appropriately changed depending on the temperature applied when the metallized layer 8 is formed. The method of filling the wax 20 into the through hole 21 is performed, for example, by discharging the wax from the needle tip using a dispenser or the like. Thereafter, as shown in FIG. 10C, the metallized layer 8 is formed on the surface roughened by sputtering or vapor deposition. After the metallized layer 8 is formed, as shown in FIG. 10D, the glass pedestal 2 is removed from the flat plate 10 and the glass pedestal 2 is heated to melt the wax 20 filled in the through holes 21. And remove. By doing so, the metallized layer 8 is prevented from being formed in the through hole 21.

However, in this case, the through hole 21
An extra step of filling the wax 20 into the inside increases, resulting in an increase in cost. Further, when the wax is scattered on the surface of the glass pedestal 2 other than inside the through hole 21, the metallized layer 8 is formed on the wax, and the adhesive force of the metallized layer 8 to the surface of the glass pedestal 2 is increased. descend.
Further, after the metallized layer 8 is formed, the wax 20 filled in the through holes 21 is melted and removed. When the residue of the wax 20 wraps around on the surface of the glass pedestal 2 that is bonded to the semiconductor pressure sensor chip 1. Therefore, the bonding quality between the glass pedestal 2 and the semiconductor pressure sensor chip 1 is significantly affected. That is, voids (voids) are generated without joining, and the joining strength is reduced. Cleaning with a molten organic solvent (acetone, isopropyl alcohol, etc.) may be considered to remove the residue of the wax 20, but the number of cleaning steps increases and quality control such as confirmation of the residue level after cleaning is difficult. In particular, when the wax 20 is opaque, there is a problem that the visual inspection cannot be performed and the cleaning property cannot be evaluated.

The present invention has been made in view of the above points, and an object thereof is that a metallized layer is not formed on the inner wall of the through hole of the pedestal, the number of steps is not increased, and the bonding reliability is improved. It is to provide a method of forming a metallized layer of a pedestal for a semiconductor pressure sensor and a method of manufacturing a metallizing jig having good properties.

[0011]

The invention according to claim 1 is
It has a semiconductor pressure sensor chip having a diaphragm formed thin by forming a recess, and a pedestal in which a through hole for introducing pressure to the diaphragm is formed and which is joined to the semiconductor pressure sensor chip. A method of forming a metallization layer on the surface of the pedestal of the semiconductor pressure sensor that is not joined to the semiconductor pressure sensor chip, the method being larger than the opening shape on the surface side of the through hole on which the metallization layer of the pedestal is formed. A metallizing jig comprising a disk-shaped member having a shape and a thin wire member for fixing the disk-shaped member so as to be arranged corresponding to the arrangement of the through holes of the pedestal, While installed so as to close the opening of the through hole, form the metallization layer by sputtering or vapor deposition from the surface side on which the metallization layer is formed. It is characterized in.

According to a second aspect of the invention, in the first aspect of the invention, the thin wire member is formed in a loop shape.

The invention according to claim 3 is the method for manufacturing a metallizing jig according to claim 2, wherein a metal plate is attached to one surface of the resin substrate, and the metal plate is etched to obtain the metal plate. The disk-shaped members are formed at substantially equal intervals, and then the adjacent disk-shaped members are connected by a loop-shaped thin wire member,
Next, the resin substrate is peeled off.

According to a fourth aspect of the present invention, there is provided a method for manufacturing the metallizing jig according to the second aspect, in which the metal thin wires are arranged in a grid pattern at substantially equal intervals, and the intersections of the metal thin wires are welded. While connecting, crush the welded part into a flat plate,
Next, the metal thin wire is deformed into a loop by a mold.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An example of an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a process drawing showing a method for forming a metallized layer of a semiconductor pressure sensor pedestal according to an example of an embodiment of the present invention. First, as shown in FIG. 1A, a disk-shaped glass pedestal 2 (diameter of about 100 mm to 1
The through-hole 21 is formed in 50 mm and a thickness of about 0.5 mm to 3 mm) by an ultrasonic processing method or the like. Through hole 2
The size of 1 is about 0.6 mm to 1.5 mm in diameter.
Surface roughening is performed on one surface of the glass pedestal 2. That is, one surface of the glass pedestal 2 is polished with a coarse grindstone or is sprayed with a sandblast method to roughen the surface so that metal is easily attached when forming a metallized layer described later. deep.

Next, as shown in FIG. 1B, the glass pedestal 2 is placed on the flat plate 10 with the roughened surface facing upward. Then, as shown in FIG. 2, a disk-shaped member 31 having a shape slightly larger than the shape of the opening of the through hole 21 on the roughened surface of the glass pedestal 2 (the surface forming the metallized layer of the pedestal), A metallizing jig 30 including a thin metal wire 32 as a thin wire member for fixing the disk member 31 so as to be arranged corresponding to the arrangement of the through holes 21 of the pedestal 2 is provided. Is installed so as to close the opening of the through hole 21. Here, the metal wire 32 is formed in a loop shape. Further, as the disk-shaped member 31, for example, copper or a material obtained by plating the surface of copper with nickel or gold is used. Its thickness is about 50 μm to 200 μm, and its shape is slightly larger than the shape of the opening of the through hole 21, and is about 0.
It is circular with a diameter of 7 to 1.5 mm.

In this state, as shown in FIG. 1C, the metallized layer 8 is formed on the roughened surface side of the glass pedestal 2 by sputtering or vapor deposition. In the case of sputtering, a pressure of 10 ^-2 Torr to 10 ^-4 Torr is applied around the target (a plate used as the material of the metallized layer 8) and a few hundred V is applied between the substrate and the vacuum container (ground) and the target.
A voltage of several KV is applied to generate plasma. Ions in the plasma bounce off the atoms on the target surface and adhere to the substrate (glass) to form a film. By changing the target by this method, a plurality of metal layers are laminated to form the metallized layer 8. An example of the metallized layer 8 is Cr (bottom layer) / N
Examples include i / Au (uppermost layer), Ti (lowermost layer) / Ni / Au (uppermost layer), Ti (lowermost layer) / Pt / Au (uppermost layer). Note that the sputtering is performed from the direction of the surface on which the metallized layer is formed (the surface on which the surface is roughened). At this time, the metal wire 32 fixing the plurality of disc-shaped members 31
Is composed of a thin member and is formed in a loop shape, so that the metallized layer 8 is not uneven due to the shielding of the metal wire 32. Thereafter, as shown in FIG. 1D, the metallizing jig 30 is removed.

As described above, in the glass pedestal 2 having the metallized layer 8 formed thereon, the surface on which the metallized layer 8 is formed is joined to the metal pipe 4 via the solder 9 as shown in FIG. The surface is bonded to the semiconductor pressure sensor chip 1 by anodic bonding. As the conditions for anodic bonding, heating to about 400 ° C. in a vacuum atmosphere and applying a DC voltage of about 500 V to 800 V so that the semiconductor pressure sensor chip 1 side becomes a positive electrode causes atomic bonding by electrostatic attraction. Of.

According to the present embodiment, the inner wall 22 of the through hole 21 of the glass pedestal 2 is formed with the metallized layer because the through hole 21 is closed by the disk-shaped member 31 during the process of forming the metallized layer 8. It is not formed and is formed only on the joint surface with the metal pipe 4. Therefore, when the glass pedestal 2 and the semiconductor pressure sensor chip 1 are anodically bonded, the semiconductor pressure sensor chip 1 is not destroyed by discharge, and an extra step such as filling with wax is not added. In addition, the reliability of joining the glass pedestal 2 to the semiconductor pressure sensor chip 1 and the metal pipe 4 is also improved.

FIG. 4 is a process drawing showing an example of a method of manufacturing the metallizing jig 30. First, as shown in FIG. 4A, a copper foil is attached to a resin substrate 40 made of phenol or the like, the copper foil is etched with ferric chloride or the like, and circular patterns (discs) arranged at substantially equal intervals are formed. Shaped member) 31 is formed. Next, as shown in FIG. 4B, a pattern (disc-shaped member)
Wires (metal wires) 32 made of copper, aluminum, gold or the like are connected between the wires 31 by wire bonding. Wire (metal wire) 3
The diameter of 2 is about 50 μm to 300 μm. Next, as shown in FIG. 4C, the resin substrate 40 is dissolved in a solvent such as trichlene, acetone or the like and peeled off. Here, the circular pattern (disk member) 31 and the wire (metal wire) 3
The connection of 2 may be performed by a method of connecting a long wire (metal wire) 32 to a pattern (disc-shaped member) 31 by welding 33, as shown in FIG. 5, other than wire bonding.

FIG. 6 is a process chart showing another example of the method for manufacturing the metallizing jig 30. First, as shown in FIG. 6 (a), a plurality of metal wires (metal wires) 32 are arranged in a grid pattern at predetermined intervals, and as shown in FIG. 6 (b),
The disc-shaped member 31 is formed by welding the intersections and crushing the intersections to form a flat plate. Next, as shown in FIG. 6C, the wire (metal wire) 32 is fitted into the lower die 51 having a convex portion in contact with the wire (metal wire) 32, and the wire (metal wire) 32 is abutted. The upper mold 52 having a concave contact portion is pressed down from above. afterwards,
When the lower mold 51 and the upper mold 52 are removed, a wire (metal wire)
The metallizing jig 30 having the loop shape 32 is completed. Here, the disk-shaped members 31 are arranged at a predetermined pitch.

According to the method of manufacturing the metallizing jig 30 described above, the metallizing jig 30 used in the method of forming the metallized layer of the semiconductor pressure sensor pedestal of the present invention can be easily manufactured.

[0023]

As described above, according to the first aspect of the present invention, a semiconductor pressure sensor chip having a diaphragm formed thin by forming a recess, and a pressure for introducing pressure to the diaphragm. A through hole is formed,
A method of forming a metallization layer on a surface of a pedestal of a semiconductor pressure sensor having a pedestal joined to the semiconductor pressure sensor chip, the pedestal of the through hole being a surface of the pedestal that is not joined to the semiconductor pressure sensor chip. A disk-shaped member having a shape larger than the shape of the opening on the surface side on which the metallized layer is formed, and a thin wire member for fixing the disk-shaped member so as to be arranged corresponding to the arrangement of the through holes of the pedestal. Since the metallizing jig consisting of the disk-shaped member is installed so as to close the opening of the through hole, the metallized layer is formed by sputtering or vapor deposition from the surface side on which the metallized layer is formed. A metallized layer is not formed on the inner wall of the through hole of the pedestal, and the number of steps does not increase. I was able to today.

According to the invention of claim 2, in the invention of claim 1, since the thin wire member is formed in a loop shape, a more uniform metallized layer can be formed.

According to a third aspect of the present invention, there is provided the method for manufacturing the metallizing jig according to the second aspect, wherein a metal plate is attached to one surface of the resin substrate and the metal plate is etched. , The disk-shaped members are formed at substantially equal intervals, then adjacent disk-shaped members are connected by a loop-shaped thin wire member, and then the resin substrate is peeled off. The metallizing jig used in the item 2 can be easily manufactured.

According to a fourth aspect of the present invention, there is provided the method of manufacturing the metallizing jig according to the second aspect, wherein the fine metal wires are arranged in a grid pattern at substantially equal intervals, and the intersections of the fine metal wires are arranged. The metallizing jig used in claim 2 can be easily used because the metal thin wires are connected to each other by welding, the welded portion is crushed into a flat plate shape, and then the metal thin wire is deformed into a loop by a mold. Can be manufactured.

[Brief description of drawings]

FIG. 1 is a process drawing showing a method for forming a metallized layer of a semiconductor pressure sensor pedestal according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a metallizing jig 30 according to the above.

FIG. 3 is a schematic view showing a state in which the pedestal according to the above is joined to a semiconductor pressure sensor chip and a metal pipe.

FIG. 4 is a process drawing showing an example of a method for manufacturing a metallizing jig 30 according to the present invention.

FIG. 5 is a schematic view showing an example of a method of connecting the metal wire and the disc-shaped member according to the above.

FIG. 6 is a process drawing showing another example of the method for manufacturing the metallizing jig 30 according to the present invention.

FIG. 7 is a schematic configuration diagram of a semiconductor pressure sensor.

FIG. 8 is a process chart showing a method for forming a metallized layer of a pedestal for a semiconductor pressure sensor according to a conventional example.

FIG. 9 is a schematic view showing a state in which the pedestal according to the above is joined to the semiconductor pressure sensor chip and the metal pipe.

FIG. 10 is a process chart showing a method for forming a metallized layer of a pedestal for a semiconductor pressure sensor according to another conventional example.

[Explanation of symbols]

1 Semiconductor pressure sensor chip 2 glass pedestal 3 plastic packages 4 metal pipes 5 leads 6 wires 7 lid 8 Metallized layer 9 solder 10 Flat plate 11 diaphragm 12 Strain gauge resistance 13 overcoat 20 wax 21 through holes 22 Inner wall 30 Metallizing jig 31 Disc-shaped member 32 metal wire 40 resin substrate 51 Lower mold 52 Upper mold

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Claims (4)

(57) [Claims] 1. A semiconductor pressure sensor chip having a diaphragm formed thin by forming a recess and a through hole for introducing pressure to the diaphragm are formed and bonded to the semiconductor pressure sensor chip. A method of forming a metallized layer on the surface of the semiconductor pressure sensor having a pedestal on the side of the pedestal that is not joined to the semiconductor pressure sensor chip, wherein the surface side on which the metallized layer of the pedestal of the through hole is formed A metallizing jig comprising a disc-shaped member having a shape larger than the opening shape and a fine wire-shaped member for fixing the disc-shaped member so as to be arranged corresponding to the arrangement of the through holes of the pedestal, A metallization layer is formed by sputtering or vapor deposition from the side on which the metallization layer is formed, with the disk-shaped member installed so as to close the opening of the through hole. A method of forming a metallized layer of a pedestal for a semiconductor pressure sensor, characterized in that. 2. The method for forming a metallized layer of a semiconductor pressure sensor pedestal according to claim 1, wherein the thin linear member is formed in a loop shape. 3. The method for manufacturing a metallizing jig according to claim 2, wherein a metal plate is attached to one surface of the resin substrate, and the metal plate is etched to form the disc-shaped member substantially. Manufacture of a metallizing jig, characterized in that it is formed at equal intervals, and then adjacent disc-shaped members are connected by loop-shaped thin wire members, and then the resin substrate is peeled off. Method. 4. The method for manufacturing a metallizing jig according to claim 2, wherein the metal thin wires are arranged in a grid pattern at substantially equal intervals, the intersections of the metal thin wires are connected by welding, and the welding is performed. A method for manufacturing a metallizing jig, characterized in that the portion is crushed into a flat plate shape, and then the metal thin wire is deformed into a loop by a mold.