JPH10281908A - Semiconductor pressure sensor and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure sensor excellent in heat resistance and durability and in reliability by forming a joining metal film on one face of a glass pedestal except an outer peripheral edge part as a joining surface, and joining the metal film to a metal pedestal with soft solder. SOLUTION: One face of a glass wafer 7 is selected as a joining surface, and a joining metal film 4 adhering to a soft solder 6 is formed on the face except an outer peripheral edge part. A pressure sensitive diaphragm 1a is formed in a silicon wafer 8, which is anodic-joined to the other face of the glass wafer 7. The joined body composed of the glass wafer 7 and the silicon wafer 8 is cut into small pieces having each pressure sensitive diaphragm 1a. A part of each small piece of silicon wafer 8 is selected as a silicon element 1 to form a pressure sensitive tip 3 having a part of the glass wafer 7 as a glass pedestal 2. The joining surface of the pressure sensitive tip 3 is joined to a metal pedestal 5 with a soft solder 6. This method prevents stress caused by the hardening of the soft solder 6 from transmitting to the side of the glass pedestal 2 to make the occurrence of breakage difficult.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly reliable semiconductor pressure sensor having good heat resistance and durability, and a method of manufacturing the same.

[0002]

2. Description of the Related Art As a conventional semiconductor pressure sensor, FIG.
Can be exemplified. This semiconductor pressure sensor is disclosed in Japanese Patent Publication No. 6-76938, in which (A) is a cross-sectional view of the semiconductor pressure sensor, and (B) and (C) show the state during the manufacturing process. FIG.

As shown in FIG. 1A, in this semiconductor pressure sensor, a silicon element 1 having a pressure-sensitive diaphragm 1a and a glass pedestal 2 are joined to form a pressure-sensitive chip 3. Then, on one surface of the glass pedestal 2 of the pressure-sensitive chip 3, a bonding metal film 4 composed of a three-layer metal film adhered to a soft solder is formed to serve as a bonding surface to the metal pedestal 2. It is formed by joining to the metal pedestal 5 with soft solder.

A through-hole 2a is formed in the glass pedestal 2, and this through-hole 2a is formed so as to communicate with the pressure introducing hole 5a of the metal pedestal 5 so that pressure is introduced into the pressure-sensitive diaphragm 1a. I have.

In the pressure-sensitive chip 3 of such a semiconductor pressure sensor, as shown in FIG. 1B, a large number of through holes 2a are formed in a glass wafer 7, and a bonding metal film 4 is formed on one entire surface. Then, as shown in FIG. 3C, the glass wafer 7 and the silicon wafer 8 on which the pressure-sensitive diaphragm 1a is formed are joined by anodic bonding so that the positions of the pressure-sensitive diaphragm 1a and the through-hole 2a match. doing. Then, the bonded body of the glass wafer 7 and the silicon wafer 8 is cut into individual small pieces having the pressure-sensitive diaphragm 1a and the through holes 2a to form the pressure-sensitive chips 3.

The through-hole 2a of the glass wafer 7 is processed by an ultrasonic horn or the like, and cut into individual small pieces to form the pressure-sensitive chip 3 by using a dicing saw or the like. I have.

[0007]

However, in the above-described conventional example, since processing is performed by an ultrasonic horn or a dicing saw, a large number of cut surfaces of the glass pedestal 2 and an inner surface of the through hole 2a are formed. Fine scratches are formed as microcracks. As a result, the pressure-sensitive chip 3
In the joining of the glass pedestal 2 and the metal pedestal 5 due to the thermal stress at the time of joining caused by the difference in linear expansion coefficient between the soft solder used as the joining material and the glass pedestal 5, In the vicinity, the glass pedestal 2 which is a brittle material is easily broken starting from the microcracks. Therefore, there are limitations such as that a high-strength material cannot be used as a joining material or that only a material having a linear expansion coefficient similar to that of the glass pedestal 2 can be used.
It is difficult to enhance the reliability of joining between the metal base 5 and the metal pedestal 5.

The present invention has been made in view of the above points, and has as its object to reduce stress on the glass pedestal when joining the glass pedestal and the metal pedestal, and to provide excellent heat resistance and durability. It is an object of the present invention to provide a highly reliable semiconductor pressure sensor and a method for manufacturing the same.

[0009]

According to a first aspect of the present invention, there is provided a pressure sensitive diaphragm for a silicon device.
1a, the silicon element 1 and the glass pedestal 2 are joined to form a pressure-sensitive chip 3, and a bonding metal film 4 adhered to a soft solder 6 on one surface of the glass pedestal 2 in the pressure-sensitive chip 3. Is formed as a bonding surface to the metal pedestal 5, and the bonding surface is bonded to the metal pedestal 5 by the soft solder 6. It is characterized by being formed.

In such a semiconductor pressure sensor, when the soft solder 6 is joined, a stress applied to the side surface of the glass pedestal 2 from the joint with the metal pedestal 5 is generated due to the hardening of the soft solder 6. However, since the joining metal film 4 does not exist on the outer peripheral edge of the joining surface and the soft solder 6 does not adhere, the stress due to the hardening of the soft solder 6 is reduced, and the glass base 2
Is less likely to be damaged.

According to a second aspect of the present invention, a pressure-sensitive diaphragm 1a is formed in a silicon element 1, and a through hole 2a is formed in a glass pedestal 2.
Is formed, the pressure-sensitive diaphragm 1a is aligned with the position of the through-hole 2a, and the silicon element 1 and the glass pedestal 2 are joined to form a pressure-sensitive chip 3, and the through-hole in the pressure-sensitive chip 3 is formed.
The surface of the glass pedestal 2 where 2a is open is defined as a bonding surface,
In a semiconductor pressure sensor in which the pressure introducing hole 5a and the through hole 2a are communicated with the metal pedestal 5 having the pressure introducing hole 5a and the joining surface is joined to the metal pedestal 5 by the soft solder 6, The bonding metal film 4 is formed at least in a portion excluding the peripheral portion of the through hole 2a.

In such a semiconductor pressure sensor, when the soft solder 6 is joined, a stress applied to the inner surface of the through hole 2 a of the glass pedestal 2 from the joint with the metal pedestal 5 is generated due to the hardening of the soft solder 6. ing. However, since the soft solder 6 does not adhere to at least the periphery of the through hole 2a on the joining surface, the stress due to the hardening of the soft solder 6 is reduced, and the glass pedestal 2 is hardly damaged.

According to a third aspect of the present invention, in the second aspect, the soft solder 6 is made of a gold-based solder material, and the soft solder 6 is excellent in corrosion resistance and heat resistance. Improves the reliability of the joint.

According to a fourth aspect of the present invention, in the second aspect of the present invention, the diameter of the pressure introducing hole 5a is formed to be smaller than the diameter of the through hole 2a. Is held by the metal pedestal 5 having a larger area than the glass pedestal 2, the stress applied to the surface of the through hole 2a of the glass pedestal 2 is reduced, and the glass pedestal 2 is hardly damaged.

[0015] The invention according to claim 5 provides the following 1) to 5).
In the method of manufacturing a semiconductor pressure sensor, the bonding metal film 4 is formed on a portion of the glass pedestal 2 other than the outer peripheral edge of the bonding surface to the metal pedestal 5. It is constituted as. 1) A step of forming one surface of a glass wafer 7 as a bonding surface and forming a bonding metal film 4 adhered to a soft solder 6 on this bonding surface 2) A step of forming a plurality of pressure-sensitive diaphragms 1a on a silicon wafer 8 3) Anodically bonding the silicon wafer 8 to the surface of the glass wafer 7 opposite to the surface on which the bonding metal film 4 is formed. 4) The bonded body of the glass wafer 7 and the silicon wafer 8 is subjected to individual pressure-sensitive diaphragms. Step of cutting into small pieces having 1a and forming the pressure-sensitive chips 3 using the silicon wafer 8 of the small pieces as the silicon elements 1 and the glass wafer 8 as the glass pedestal 2 5) Joining the pressure-sensitive chips 3 Step of bonding surface to metal pedestal 5 with soft solder 6 According to such a method of manufacturing a semiconductor pressure sensor, the bonding metal film 4 is limited to a portion excluding the outer peripheral edge of the bonding surface. , Stress transmitted to the side of the glass base 2 with the curing of the soft solder 6 are reduced, it is less likely to damage the glass base 2.

[0016] The invention according to claim 6 provides the following 1) to 5).
Forming the bonding metal film 4 on a portion of the glass pedestal 2 except for the peripheral portion of the through hole 2a on the bonding surface to the metal pedestal 5 in the method for manufacturing a semiconductor pressure sensor. The feature is constituted. 1) One surface of the glass wafer 7 is used as a bonding surface and a through hole
2a) Step of forming bonding metal film 4 to be bonded to soft solder 6) 2) Step of arranging and forming a plurality of pressure-sensitive diaphragms 1a on silicon wafer 8) 3) Bonding metal film 4 of glass wafer 7 is formed Step of anodically bonding the silicon wafer 8 by aligning the pressure-sensitive diaphragm 1a with the position of the through hole 2 on the surface opposite to the surface opposite to the contact surface 4) The bonded body of the glass wafer 7 and the silicon wafer 8 is individually Step of cutting into small pieces having a pressure diaphragm 1a and a through-hole 2a, and forming the pressure-sensitive chips 3 having the silicon wafer 8 as a silicon element 1 and the glass wafer 7 as a glass pedestal 2 in the small piece 5). Step of joining the bonding surface of the pressure-sensitive chip 3 to the metal pedestal 5 having the pressure introduction hole 5a by connecting the through hole 2a and the pressure introduction hole 5a and joining them with the soft solder 6. According to By limiting the bonding metal film 4 in the portion except the through hole 2a periphery of the joint surface, the through-hole of the glass base 2 with the curing of the soft solder 6
The stress transmitted to the inner surface 2a is reduced, and the glass pedestal 2 is hardly damaged.

According to a seventh aspect of the present invention, in the invention of the sixth aspect, the bonding metal film 4 is formed on a portion of the glass pedestal 2 other than the outer peripheral edge of the bonding surface to the metal pedestal 5 and the peripheral edge of the through hole 2a. Since the soft solder 6 is hardened, the stress transmitted to the side surface of the glass pedestal 2 and the inner surface of the through-hole 2a is reduced, so that the glass pedestal 2 is hardly damaged.

[0018] The invention according to claim 8 is the invention according to claims 5 to 7.
In the invention described in any one of the above, since the outer shape of the bonding metal film 4 is formed to be substantially circular, the stress applied to the glass pedestal 2 does not concentrate on corners and the like, Since it is uniform, the glass pedestal 2 is not easily damaged.

The invention according to claim 9 is the invention according to claim 6 or 7.
In the invention according to any one of the above, since the surface of the glass wafer 7 in which the through-hole 2a is formed is etched using a hydrofluoric acid-based solution, the surface of the glass wafer 7 is smoothed, The microcracks on the surface that are the starting points of the destruction have been removed.

[0020] The invention described in claim 10 is the invention according to claims 5 to 9.
In the invention according to any one of the above, the multi-layer structure is formed by using the outermost metal film as the bonding metal film 4, so that the lower layer of the uppermost metal film is formed on the entire surface. It is only necessary to do so, so that a multilayer film is easily formed.

According to an eleventh aspect of the present invention, in the invention according to the tenth aspect, the multilayer film has a three-layer structure of a lowermost layer, an intermediate layer, and a surface layer, and the lowermost layer is formed of titanium or chromium, and the intermediate layer is formed of platinum, nickel, or nickel. Since the palladium and the surface layer are formed of gold, the lowermost layer is in close contact with the glass pedestal 2 and has a high bonding strength, and the barrier effect of the intermediate layer is high. Is prevented from deteriorating the performance of the bonding metal film 4.

According to a twelfth aspect of the present invention, in the tenth aspect of the present invention, a multilayer film is formed on the entire surface, and at least the outer peripheral portion of the bonding surface or the peripheral portion of the through hole 2a in the outermost metal film is formed by using an ion beam. Unlike the wet method such as etching, it is not necessary to use a film for film formation and there is no wet etching process, so it is easy to maintain the cleanliness of the metal film surface. ing.

According to a thirteenth aspect of the present invention, in the tenth aspect of the present invention, after oxidizing the outer peripheral edge of the bonding surface or the peripheral edge of the through hole 2a in the metal film immediately below the outermost metal film,
The feature is that the outermost metal film is formed, so that there is no unevenness on the bonding surface.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings.

One semiconductor pressure sensor according to this embodiment will be described below with reference to FIGS.

FIG. 1 is a cross-sectional view showing an example of components constituting a semiconductor pressure sensor according to the present embodiment, in which a pressure-sensitive chip 3 is joined to a metal pedestal 5. FIG. 2 or FIG. 3 is a cross-sectional view showing a semiconductor pressure sensor formed using the above components.

As shown in FIG. 1, the components constituting this semiconductor pressure sensor include a silicon element 1 and a pressure-sensitive diaphragm.
1a, the silicon element 1 and the glass pedestal 2 are joined to form a pressure-sensitive chip 3, and a bonding metal film 4 adhered to a soft solder 6 on one surface of the glass pedestal 2 in the pressure-sensitive chip 3. Is formed as a joining surface to the metal pedestal 5, and this joining surface is joined to the metal pedestal 5 by the soft solder 6.

As the metal pedestal 5, an alloy such as Kovar or 42 alloy is used. As a material of the glass pedestal 2, a material having a linear expansion coefficient similar to that of the silicon element 1, for example, borosilicate glass or the like is used.

The pressure-sensitive chip 3 is joined to the metal pedestal 5 using a surface opposite to the silicon chip 1 as a joining surface, and using, for example, solder as the soft solder 6. The bonding metal film 4 is formed in a portion excluding the outer peripheral edge. In other words, the bonding metal film 4 is formed so as to adhere well to the soft solder 6 and to strongly adhere to the glass pedestal 2. Since there is no bonding metal film 4, the structure is such that solder does not adhere.

FIG. 2 shows a completed state of one semiconductor pressure sensor. That is, the signal extraction pin 9 is electrically connected by wire bonding or the like to the component where the pressure-sensitive chip 3 and the metal pedestal 5 are joined as described above, and the cover 10 with the pressure introducing hole is pressure-sensitive. It is formed so as to cover the chip 3.

In the semiconductor pressure sensor shown in FIG. 3, a liquid is sealed in the cover 10, and the pressure is detected through the liquid.

One semiconductor pressure sensor according to this embodiment will be described below with reference to FIGS.

FIG. 4 is a cross-sectional view showing an example of a part of the semiconductor pressure sensor, which is different from the above-described parts, in a state where the pressure-sensitive chip 3 is joined to the metal pedestal 5. FIG.
Alternatively, FIG. 6 is a cross-sectional view showing a semiconductor pressure sensor in which the metal pedestal 5 in the above-described component is formed to have a different shape.

As shown in FIG. 4, in this part, as shown in FIG.
Unlike the glass pedestal, a through-hole 2a is formed in the glass pedestal 2. The pressure-sensitive diaphragm 1a is formed through the through-hole 2a so as to guide the pressure to be detected from the through-hole 2a to the pressure-sensitive diaphragm 1a.
2a, the silicon element 1 and the glass pedestal 2
To form a pressure-sensitive chip 3. And
In this part, the joining metal film 4 is formed except for the peripheral portion of the through hole 2a on the joining surface.
Are joined to each other by a soft solder 6 with the center of the pressure introducing hole 5a and the center of the through hole 2a substantially matching each other.

In the semiconductor pressure sensor shown in FIG. 5, the opening of the pipe is formed as a metal pedestal 5, and the metal pedestal 5 and the signal extraction pin 9 are attached to a base portion 11 made of a sealing material such as a synthetic resin. The base part is formed integrally
The cover 10 is attached to 11.

In the semiconductor pressure sensor shown in FIG. 6, the base 11 is formed as a container having an upper opening.
The same metal base 5 of a pipe shape is protruded from the bottom, and the signal extraction pin 9 is protruded in the horizontal direction. A flat cover 10 is attached to the opening above the base 11.

The above-described semiconductor pressure sensor has a structure in which the bonding metal film 4 is not provided on the outer peripheral edge of the bonding surface of the glass pedestal 2 or the peripheral edge of the through hole 2a, and the soft solder 6 does not adhere to this portion. I have. Therefore, the stress generated due to the hardening of the soft solder 6 is caused by the outer peripheral portion of the glass pedestal 2 or the through hole 2a.
It is hard to reach the inner wall. Therefore, damage originating from microcracks existing in the glass pedestal 2 is unlikely to occur, and a highly reliable semiconductor pressure sensor having improved durability and heat resistance is provided. That is, the outer shape of the glass pedestal 2 and the through-hole 2a are formed by mechanical processing such as a dicing saw or an ultrasonic horn, and micro cracks are formed by such mechanical processing. For this reason, the mechanical strength of the glass pedestal 2 is reduced. Then, by the joining process using the soft solder 6, a stress is generated in the joining portion, and the stress is liable to be in a state where the stress is present and the strength is weaker. It ’s hard to get to where you are,
It has high strength and excellent reliability such as corrosion resistance and heat resistance.

As shown in FIG. 7, it is more preferable that the diameter of the pressure introducing hole 5a is smaller than the diameter of the through hole 2a.
According to such a structure, the metal pedestal 5 is bonded to the soft solder 6 with an area larger than the glass pedestal 2. For this reason, the metal pedestal 5 holds the heat shrinkage of the soft solder 6 more than the glass pedestal 2, the stress applied to the surface of the through hole 2a of the glass pedestal 2 is reduced, and the glass pedestal 2 is hardly damaged. Reliability such as durability and heat resistance is improved.

As the soft solder 6, Au-20Sn, Au-12G
e, It is also preferable to use a gold-based solder material such as Au-3Si, and such a solder material has high corrosion resistance and heat resistance, and can further improve the corrosion resistance and heat resistance of the joint.

One method of manufacturing the semiconductor pressure sensor according to this embodiment will be described below with reference to FIGS.

FIGS. 8 to 10 show different manufacturing methods, and FIGS. 8A to 8E show the state of the product in each step.

The manufacturing method shown in FIG. 8 will be described below. In this manufacturing method, a semiconductor pressure sensor is manufactured by performing the following steps 1) to 5).
Is characterized in that the bonding metal film 4 is formed on a portion other than the outer peripheral edge of the bonding surface to the metal pedestal 5. 1) A step of forming one surface of a glass wafer 7 as a bonding surface and forming a bonding metal film 4 adhered to a soft solder 6 on the bonding surface 2) A step of forming a pressure-sensitive diaphragm 1a on a silicon wafer 8 3) Glass Step of anodically bonding the silicon wafer 8 to the surface of the wafer 7 opposite to the surface on which the bonding metal film 4 is formed 4) The bonded body of the glass wafer 7 and the silicon wafer 8 is provided with individual pressure-sensitive diaphragms 1a. Step of cutting into small pieces and forming the pressure-sensitive chips 3 with the silicon wafer 8 portions of the small pieces as the silicon elements 1 and the glass wafer 8 portions with the glass pedestals 5) The bonding surface of the pressure-sensitive chips 3 is made of metal Step of bonding to the pedestal 5 with the soft solder 6 As shown in (B) or (C), as the silicon wafer 7, a semiconductor single crystal wafer or the like is used. From the blind hole is formed by etching to form a plurality of diaphragms. Then, a diffusion strain gauge is formed on the surface of the diaphragm opposite to the bottomed hole to form the pressure-sensitive diaphragm 1a. In the process of forming such a diffusion strain gauge, the insulating layer formed by oxidizing the entire surface of the silicon wafer 7 is used as a selection mask, and a window, which is opened only at a desired position by photoetching, is partially formed of, for example, boron. Impurities are thermally diffused.

As the glass wafer 8, a material having a similar linear expansion coefficient to the silicon wafer 7, for example, a borosilicate glass wafer or the like is used, and a multilayer film having the bonding metal film 4 on the outermost surface on one surface thereof is used. As a film, Ti from the glass side
Three metal films of / Pt / Au, Ti / Ni / Au, Ti / Pd / Au, Cr / Pt / Au, Cr / Ni / Au or Cr / Pd / Au are formed. Note that these metal species are indicated by element symbols. This multilayer film
As shown in (A), many are formed in a substantially square shape and arranged in a matrix. In this case, the interval between the multilayer films is
It is formed at the same pitch as the pressure-sensitive diaphragm 1a formed on the silicon wafer 7 and with a gap of about 0.4 mm.

The thickness of each metal film is 500 for gold.
5,000 Angstroms and 2000 Angstroms for other metals. Further, in order to form an array in a matrix as described above, after forming a three-layer metal film on the entire surface, a photoresist film is adhered, and a photoresist pattern is formed by exposure and development. It is preferable to selectively remove unnecessary portions by etching the respective metal films. At this time, only the outermost gold film may be removed. This is because the etching of only the outermost layer is easier than the etching of three types of metal films having different etch rates. The outermost metal film is the bonding metal film 4 having adhesiveness to the soft solder 6. The photoresist film is removed after the etching.

As shown in (B), after the formation of the multilayer film, the bottomed hole of the silicon wafer 7 is formed so that the bottomed hole of the silicon wafer 7 and the center of the multilayer film of the glass wafer coincide with each other. And the surface of the glass wafer 8 on which the multilayer film is not formed is bonded by anodic bonding.

Thereafter, as shown in FIG. 4C, the silicon wafer 1 is cut at the center of the gap between the multilayer films by a dicing saw thinner than the gap between the multilayer films formed on the glass wafer 8. Then, the pressure-sensitive chip 3 having the glass wafer 7 as the glass pedestal 2 is formed.

Further, as shown in (D), the pressure-sensitive chip 3 is made into a soft solder 6 and joined to the metal pedestal 5 using a solder such as a tin-based solder or a gold-based solder. Sn-0 ~ 1 for tin solder
0.5Sb, Sn-0-5Ag, etc. Au-20Sn or the like can be used as the gold-based solder. These solders do not contain flux and are joined by heating in a nitrogen or reducing atmosphere.

Thereafter, as shown in (E), the silicon element 1 and the signal extraction pin 9 are electrically connected by wire bonding or the like, and the wire bonding portion of the silicon element 1 is sealed with silicon gel. The semiconductor pressure sensor is completed by fitting the cover 10.

The manufacturing method shown in FIG. 9 will be described below. In this manufacturing method, the semiconductor pressure sensor is manufactured by performing the following steps 1) to 5). In particular, the semiconductor pressure sensor is bonded to a portion of the glass pedestal 2 excluding the periphery of the through hole 2a on the bonding surface to the metal pedestal 5. It is characterized by forming a metal film 4 for use. 1) One surface of the glass wafer 7 is used as a bonding surface and a through hole
Step of forming bonding metal film 4 bonded to 2a and soft solder 6 2) Step of forming pressure sensitive diaphragm 1a on silicon wafer 8 3) Surface of glass wafer 7 on which bonding metal film 4 is formed Step of anodically bonding the silicon wafer 8 with the position of the pressure-sensitive diaphragm 1a and the position of the through-hole 2a substantially coincident with each other on the surface opposite to the surface of the glass wafer 7 and the silicon wafer 8 Step of cutting into small pieces having a pressure diaphragm 1a and a through-hole 2a, and forming the pressure-sensitive chips 3 having the silicon wafer 8 as a silicon element 1 and the glass wafer 7 as a glass pedestal 2 in the small piece 5). A step of joining the bonding surface of the pressure-sensitive chip 3 to the metal pedestal 5 having the pressure introducing hole 5a by connecting the through-hole 2a and the pressure introducing hole 5a to the metal pedestal 5 with the soft solder 6; So, the above figure Unlike the method shown in FIG. 8, a through hole 2a is formed in a glass wafer
And a through hole is formed in the metal pedestal 5 having the pressure introducing hole 5a.
The pressure-sensitive chip 3 is joined to the metal pedestal 5 by making the 2a communicate with the pressure introducing hole 5a. Therefore, in the semiconductor pressure sensor manufactured as described above, the pressure to be detected reaches the pressure-sensitive diaphragm 1a of the pressure-sensitive chip 1 from the pressure introducing hole 5a via the through hole 2a.

The bonding metal film 4 is formed so as not to remain at least 0.1 mm in the vicinity of the through hole 2a.

The through hole 2a is formed by ultrasonic processing. In this case, the through hole 2a
May be before or after the bonding metal film 4 is formed.

In the manufacturing method shown in this figure, the metal pedestal 5 is formed as an opening of a pipe as shown in FIG.
The passage of the pipe is formed as a pressure introducing hole 5a, and the metal pedestal 5 and the signal extraction pin 9 are integrally formed on a base portion 11 made of a sealing material such as a synthetic resin to form a projection.
The cover 10 is attached to 11.

The manufacturing method shown in FIG. 10 will be described below. In this manufacturing method, in the manufacturing method of FIG.
Through hole in the surface of the glass pedestal 2 joined to the metal pedestal 5
The bonding metal film 4 is formed not only at the peripheral edge of the 2a but also at the portion excluding the outer peripheral edge of the bonding surface.

According to the above-described manufacturing method, the bonding metal film 4 is formed in a simple step limited to the portion of the glass pedestal 2 other than the outer peripheral edge of the bonding surface or the peripheral edge of the through hole 2a. The stress that occurs with the hardening of the solder 6 and is transmitted to the side surface of the glass pedestal 2 is reduced. Therefore, the glass pedestal 2 is hardly damaged, and a semiconductor pressure sensor with improved reliability such as durability and heat resistance can be easily manufactured.

In each of the above-described manufacturing methods, the outer shape of the bonding metal film 4 is formed in a substantially rectangular shape.
It is also preferable that the glass pedestal 2 is formed in a substantially circular shape. In this case, the stress applied to the glass pedestal 2 is uniform without being concentrated on corners and the like, so that the glass pedestal 2 is hardly damaged, and durability, heat resistance, etc. A semiconductor pressure sensor with further improved reliability can be manufactured.

It is also a preferable method to form the bonding metal film 4 after the surface of the glass wafer 7 having the through holes 2a formed thereon is etched using a hydrofluoric acid-based solution. In this case, the surface of the glass wafer 7 is smoothed, and microcracks on the surface serving as a starting point of destruction are removed, so that the glass pedestal 2 is hardly damaged from this point, and reliability such as heat resistance is further improved. The semiconductor pressure sensor thus manufactured can be manufactured.

A multilayer film is formed on the entire surface, and the outermost edge of the bonding surface or the edge of the through hole 2a is removed by an ion beam using the outermost surface layer of the multilayer film as the bonding metal film 4. Is also good. In this case, unlike a wet method such as etching, a film for film formation is not required, and since there is no wet etching step, the surface can be easily kept clean and a bonding metal film 4 having stable adhesive strength can be formed. can do.

As shown in FIGS. 11 to 13, forming a multilayer film including the bonding metal film 4 is also a preferable manufacturing method.

In these figures, different glass wafers 7 each having a multilayer film formed thereon are shown as plan views in FIG.
(B) shows a sectional view.

As shown in these figures, the multilayer film is formed in a three-layer structure of a lowermost layer 4c, an intermediate layer 4b, and a surface layer 4a, and the lowermost layer 4c is made of titanium or chromium.
The intermediate layer 4b is formed of platinum, nickel or palladium, and the surface layer 4a which is the bonding metal film 4 is formed of gold. According to the layer structure of such a metal type, the lowermost layer 4c strongly adheres to the glass pedestal 2 and the intermediate layer 4b serves as a good barrier. This is preferable because the performance of the metal film 4 for use is prevented from deteriorating.

Of the three layers, the surface layer 4a, which is the outermost metal film, is formed so as to be limited to the outer peripheral portion of the bonding surface or the portion other than the peripheral portion of the through hole 2a. , Because the lower layer of the multi-layer structure is only formed on the entire surface,
A multilayer film can be easily formed.

More specifically, FIG. 11 shows a case where the through hole 2a is not formed in the glass wafer 7, and the metal film of the surface layer 4a is removed by limiting it to the outer peripheral portion of the bonding surface. It is formed in the state where it was set. 12 or 13 is a case where the through-hole 2a is formed, the removal range is limited to the peripheral portion of the through-hole 2a in FIG. 12, and FIG. It is limited to the periphery of the through hole 2a.

As shown in FIG. 14 (A) or (B), it is also a preferable method to form at least the outer shape of the metal film of the surface layer 4a into a substantially circular shape. (A)
3B shows a case where the through hole 2a is not formed in the glass wafer 7, and FIG. 4B shows a case where the through hole 2a is formed. In these cases, the stress applied to the glass pedestal 2 is uniform without being concentrated on the corners as in the case of a rectangular shape, so that the glass pedestal 2 is hardly damaged, and heat resistance and durability are improved. , A semiconductor pressure sensor with improved characteristics can be manufactured.

Further, at least the metal film of the surface layer 4a may be removed by irradiating with an ion beam and scanning, so that the surface of the bonding metal film 4 is kept clean and adhered to the soft solder 6. Powerful bonding can be performed.

As shown in FIGS. 15 to 17, forming a base layer serving as a base of the outermost metal film is also a preferable manufacturing method.

These figures show different glass wafers 7 on which an underlayer serving as a base of the outermost metal film is formed.
(A) is a plan view and (B) is a cross-sectional view.

As shown in these figures, in this manufacturing method, the outer peripheral edge of the bonding surface or the peripheral edge of the through hole 2a on the surface of the metal film immediately below the outermost metal layer of the bonding metal film 4 is oxidized. After that, a gold film is formed as the outermost metal film. In this case, the gold film is formed on the entire surface, and the bonding surface has no irregularities.

More specifically, titanium or chromium is formed as the lowermost layer 4c from the glass wafer 7 side,
Nickel or palladium is deposited as 4b. The thickness of the metal film of the lowermost layer 4c or the intermediate layer 4b is about 2000 Å.

After the entire surface of the metal film of the intermediate layer 4b is oxidized to form an oxide film 12, a photoresist film is adhered, a photoresist pattern is formed by exposure and development, and the oxide film 12 is selected by etching. Then, after removing the photoresist film, a gold film serving as the surface layer 4a is formed.

In these figures, FIG. 15 shows a glass wafer 7 having no through hole 2a. In this case, the oxide film 12 is removed by etching in a substantially square shape, but may be removed in a circular shape. . FIG. 16 shows a glass wafer 7 having a through hole 2a formed therein.
The oxide film 12 is left only on the peripheral edge of the through hole 2a on the bonding surface. FIG. 17 shows a glass wafer 7 in which a through-hole 2a is similarly formed.
Although the oxide film 12 is left on the periphery with a substantially circular outer shape,
Oxide film 12 may be left in a substantially square or rectangular shape.

When the pressure-sensitive chip 3 formed by using the glass wafer 7 formed as described above is joined to the metal pedestal 5 with solder such as tin-based solder or gold-based solder, the outermost surface is required at the time of joining. The gold film is melted in the solder, and the portion where the oxide film 12 exists on the surface of the underlayer repels the solder (dewetting), thereby preventing the solder from adhering to the bonding surface. On the other hand, in the portion where the oxide film 12 is not present, the solder adheres and the metal pedestal 4
And the pressure-sensitive chip 3 is formed.

[0072]

According to the first aspect of the present invention, since there is no bonding metal film on the outer peripheral edge of the joining surface of the glass pedestal, the structure is such that soft solder does not adhere to the outer peripheral edge. For this reason, the stress generated due to the hardening of the soft solder is less likely to be transmitted to the side surface of the glass pedestal, and breakage starting from microcracks existing on the side surface of the glass pedestal is less likely to occur. Therefore, a highly reliable semiconductor pressure sensor having improved durability and heat resistance is provided.

According to the second aspect of the present invention, since there is no bonding metal film at least at the peripheral edge of the through hole on the bonding surface of the glass pedestal, the structure is such that soft solder does not adhere to the peripheral edge of the through hole. For this reason, the stress generated due to the hardening of the soft solder is less likely to be transmitted to the inner wall surface of the through hole of the glass pedestal, and the damage starting from the micro crack existing on the inner wall surface of the through hole of the glass pedestal is less likely to occur. I have. Therefore, a highly reliable semiconductor pressure sensor having improved durability and heat resistance is provided.

According to the third aspect of the present invention, since a gold-based solder material is used as the soft solder, the corrosion resistance and the heat resistance of the joining portion due to the soft solder are improved.

According to the fourth aspect of the present invention, the thermal shrinkage of the soft solder is largely held by the metal pedestal bonded in a larger area than the glass pedestal, so that the stress applied to the through hole surface of the glass pedestal is reduced. Therefore, the glass pedestal is hardly damaged, and the reliability such as durability and heat resistance is improved.

According to the fifth aspect of the present invention, by a simple process of forming the bonding metal film limited to a portion other than the outer peripheral portion of the bonding surface, the metal film is generated along with the hardening of the soft solder and is formed on the side surface of the glass pedestal. The transmitted stress is reduced. Therefore, it is difficult to break the glass pedestal, durability,
A semiconductor pressure sensor having improved reliability such as heat resistance can be easily manufactured.

According to the sixth aspect of the present invention, by limiting the joining metal film to at least the portion of the joining surface other than the peripheral edge of the through hole, the metal film is generated along with the hardening of the soft solder and is transmitted to the inner surface of the through hole of the glass pedestal. Stress is reduced. Therefore, the glass pedestal is hardly damaged, and the reliability such as durability and heat resistance is improved.

According to the seventh aspect of the present invention, the stress transmitted to the side surface of the glass pedestal and the inner surface of the through hole is reduced with the hardening of the soft solder. Therefore, the glass pedestal is less likely to be damaged, and the reliability such as durability and heat resistance is improved.

According to the eighth aspect of the invention, the outer shape of the bonding metal film has no corners, and the stress applied to the glass pedestal does not concentrate on the corners and the like, and is uniform. Therefore, it is difficult to damage the glass pedestal.

According to the ninth aspect of the present invention, the surface of the glass wafer is smoothed by the surface etching using the hydrofluoric acid solution, and the microcracks on the surface which is the starting point of the destruction are removed. Therefore, the glass pedestal is hardly damaged, and the reliability such as durability and heat resistance is improved.

According to the tenth aspect of the present invention, only the outermost surface metal film is processed, and the lower layer of the multilayer structure is merely formed on the entire surface, so that the step of forming the bonding metal film can be easily performed. Has become. According to the eleventh aspect of the present invention, since the bonding metal film has a three-layer structure of an appropriate metal type, it is possible to prevent a problem such as diffusion at the time of anodic bonding and to prevent the performance of the bonding metal film from deteriorating. Have been. Accordingly, it is possible to manufacture a semiconductor pressure sensor having high bonding reliability between the glass pedestal and the silicon element.

In the twelfth aspect of the present invention, since an ion beam is used, unlike a wet method such as etching, a film for film formation is not required, and the removal of an unnecessary portion of the metal film on the outermost surface is facilitated. ing. Further, since there is no wet etching step, the surface of the bonding metal film can be easily kept clean, and the bonding reliability is improved.

According to the thirteenth aspect of the present invention, the oxide layer exists in the gap between the metal films on the outermost surface, so that the bonding surface has no irregularities.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of components constituting a semiconductor pressure sensor according to an embodiment of the present invention.

FIG. 2 is a sectional view showing an example of the semiconductor pressure sensor according to the first embodiment.

FIG. 3 is a sectional view showing a different example of the semiconductor pressure sensor according to the first embodiment;

FIG. 4 is a cross-sectional view showing a different example of components constituting the semiconductor pressure sensor according to the first embodiment.

FIG. 5 is a sectional view showing an example of the semiconductor pressure sensor according to the first embodiment.

FIG. 6 is a sectional view showing a different example of the semiconductor pressure sensor according to the first embodiment.

FIG. 7 is a cross-sectional view showing still another example of components constituting the semiconductor pressure sensor of the above.

FIG. 8 is an explanatory view showing a method of manufacturing the semiconductor pressure sensor according to the first embodiment, wherein (A) to (E) show states of products in respective steps.

FIGS. 9A to 9E are explanatory views showing a method for manufacturing the semiconductor pressure sensor according to the first embodiment, and show states of products in respective steps in FIGS.

FIGS. 10A to 10E are explanatory diagrams illustrating a method for manufacturing the semiconductor pressure sensor according to the first embodiment, and show states of products in respective steps. FIGS.

FIG. 11 illustrates a method of manufacturing a semiconductor pressure sensor according to the first embodiment.
(A) is a plan view, and (B) is a cross-sectional view.

FIG. 12 illustrates a method of manufacturing a semiconductor pressure sensor according to the first embodiment.
(A) is a plan view, and (B) is a cross-sectional view.

FIG. 13 illustrates a method of manufacturing a semiconductor pressure sensor according to the first embodiment.
(A) is a plan view, and (B) is a cross-sectional view.

FIG. 14 is a plan view showing an example of a glass wafer on which a bonding metal film is formed in one step in the method for manufacturing a semiconductor pressure sensor, and FIG. 14A or FIG.

FIG. 15 illustrates a method of manufacturing a semiconductor pressure sensor according to the first embodiment.
(A) is a plan view, and (B) is a cross-sectional view.

FIG. 16 illustrates a method of manufacturing a semiconductor pressure sensor according to the first embodiment.
(A) is a plan view, and (B) is a cross-sectional view.

FIG. 17 shows a method of manufacturing a semiconductor pressure sensor according to the first embodiment.
(A) is a plan view, and (B) is a cross-sectional view.

18A and 18B show a method of manufacturing a semiconductor pressure sensor according to a conventional example, and FIG. 18A is a cross-sectional view of the semiconductor pressure sensor;
(B) and (C) are cross-sectional views showing states during the manufacturing process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silicon element 1a Pressure sensitive diaphragm 2 Glass pedestal 2a Through hole 3 Pressure sensitive chip 4 Bonding metal film 4a Surface layer 4b Intermediate layer 4c Lowermost layer 5 Metal pedestal 5a Pressure introduction hole 6 Soft solder 7 Silicon wafer 8 Glass wafer 9 Signal extraction Pin 10 Cover 11 Base 12 Oxide film

Claims (13)

[Claims] 1. A pressure-sensitive diaphragm is formed on a silicon element, the silicon element is bonded to a glass pedestal to form a pressure-sensitive chip, and the pressure-sensitive chip is softly bonded to one surface of the glass pedestal. Forming a metal film for use as a bonding surface to a metal pedestal, and bonding the bonding surface to the metal pedestal with a soft solder to form a bonding metal film on a portion of the bonding surface excluding an outer peripheral portion. A semiconductor pressure sensor characterized by comprising: 2. A pressure-sensitive chip by forming a pressure-sensitive diaphragm in a silicon element, forming a through hole in a glass pedestal, aligning the pressure-sensitive diaphragm with the position of the through-hole, and joining the silicon element and the glass pedestal. Forming a surface of the glass pedestal where the through-hole in the pressure-sensitive chip is open as a bonding surface, and connecting the pressure-introducing hole and the through-hole to a metal pedestal having a pressure-introducing hole; A semiconductor pressure sensor in which a bonding metal film is formed on at least a portion of a bonding surface except a peripheral portion of a through hole in a semiconductor pressure sensor which is bonded to a metal pedestal with a soft solder. 3. The semiconductor pressure sensor according to claim 2, wherein the soft solder is made of a gold-based solder material. 4. The semiconductor pressure sensor according to claim 2, wherein the diameter of the pressure introducing hole is smaller than the diameter of the through hole. 5. A method for manufacturing a semiconductor pressure sensor, which is manufactured through the following steps 1) to 5): bonding to a portion other than an outer peripheral portion of a bonding surface of a glass pedestal to a metal pedestal. A method for manufacturing a semiconductor pressure sensor, comprising forming a metal film for use. 1) a step of forming one surface of a glass wafer as a bonding surface, and forming a bonding metal film that adheres to the bonding surface with a soft solder 2) a step of arranging and forming a plurality of pressure-sensitive diaphragms on a silicon wafer 3) a step of forming a glass wafer Step of anodically bonding the silicon wafer to the surface opposite to the surface on which the bonding metal film is formed. 4) The bonded body of the glass wafer and the silicon wafer is converted into small pieces having individual pressure-sensitive diaphragms and bonding metal films. Step of cutting and forming a pressure-sensitive chip using the silicon wafer portion of the small piece as a silicon element and the glass wafer portion as a glass pedestal 5) Step of bonding the bonding surface of the pressure-sensitive chip to a metal pedestal with a soft solder 6. A method of manufacturing a semiconductor pressure sensor, which is manufactured through the following steps 1) to 5): a method of manufacturing a semiconductor pressure sensor, the method including: A method for manufacturing a semiconductor pressure sensor, comprising forming a bonding metal film. 1) A step of forming one surface of a glass wafer as a bonding surface and forming a through hole and a bonding metal film bonded to a soft solder 2) A step of arranging and forming a plurality of pressure-sensitive diaphragms on a silicon wafer 3) A step of forming a glass wafer Anodically bonding the silicon wafer by aligning the pressure-sensitive diaphragm with the position of the through-hole on the surface opposite to the surface on which the bonding metal film is formed. 4) The bonded body of the glass wafer and the silicon wafer is individually Cutting into small pieces having a pressure-sensitive diaphragm and through-holes, and forming a pressure-sensitive chip using the silicon wafer portion of the small piece as a silicon element and the glass wafer portion as a glass pedestal. A step of joining a joining surface to a metal pedestal having a pressure introduction hole, communicating the through hole and the pressure introduction hole, and joining the metal pedestal with a soft solder. 7. The method of manufacturing a semiconductor pressure sensor according to claim 6, wherein a bonding metal film is formed on a portion of the glass pedestal other than an outer peripheral portion and a through-hole peripheral portion of a bonding surface to the metal pedestal. . 8. The method for manufacturing a semiconductor pressure sensor according to claim 5, wherein the outer shape of the bonding metal film is formed in a substantially circular shape. 9. The method for manufacturing a semiconductor pressure sensor according to claim 6, wherein the surface of the glass wafer having the through-hole formed therein is etched using a hydrofluoric acid-based solution. 10. The method for manufacturing a semiconductor pressure sensor according to claim 5, wherein a multilayer film is formed using the outermost metal film as a bonding metal film. 11. The multi-layered film has a three-layer structure of a lowermost layer, an intermediate layer and a surface layer, wherein the lowermost layer is formed of titanium or chromium, the intermediate layer is formed of platinum, nickel or palladium, and the surface layer is formed of gold. 11. The method for manufacturing a semiconductor pressure sensor according to claim 10, wherein 12. The semiconductor according to claim 10, wherein a multilayer film is formed on the entire surface, and at least an outer peripheral portion of a bonding surface or a peripheral portion of a through hole in the outermost metal film is removed by using an ion beam. Manufacturing method of pressure sensor. 13. After oxidizing an outer peripheral portion or a through-hole peripheral portion of the bonding surface in the metal film immediately below the outermost metal film,
11. The method for manufacturing a semiconductor pressure sensor according to claim 10, wherein a metal film on the outermost surface is formed.