JPH0897438A - Semiconductor sensor and its manufacture - Google Patents

Abstract

PURPOSE: To realize perfect hermetic sealing by forming a recessed part to become a hermetic part on the substrate main surface so as to join two sheets of substrates and burying a clearance part to be formed in a clearance between the hermetic part and a metal wiring and that between the metal wiring and the substrate with a metal film for being sealed. CONSTITUTION: A contact region 4b is formed by thermal diffusion of boron in an n-type silicon substrate 6. Next, a resistance region 4a to become a resistant layer is formed by ion implantation of boron or the like. Next, a diaphragm to become a pressure-sensitive part is processed by anisotropic etching for becomming thin. Next, an Al film is formed in a position coming in contact with the contact region 4b for being processed into a desired form. A recessed part to become a reference chamber 2 is formed in advance in a glass plate 7. The silicon substrate 6, on which the metal wiring 5, the resistance region 4a, the contact region 4b and the diaphragm 3 are formed, and the glass plate 7 are anode-joined. A clearance on the side part X of the glass plate 7 and the metal. wiring 5 is sealed by vapor deposition of a metallic film 8 by a focused ion beam.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor sensor and a method of manufacturing the same, and more particularly to a semiconductor sensor which realizes a hermetically sealing structure of a metal wiring forming portion in the field of micromachining and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in various semiconductor sensors such as a pressure sensor, for example, a hermetically sealed state is maintained from the inside which is bonded and sealed by, for example, a silicon substrate and a glass plate. It may be necessary to take out the electrical wiring as it is. In such a case, FIG.
~ It is described in Baifukan "Micromachining and Micromechatronics" that the method shown in Fig. 7 is adopted. That is, the silicon substrate 11 and the glass plate 1
2 is a method of forming an airtightly sealed portion 13 and connecting a metal wiring 15 to a diffusion layer 14 which is a wiring inside thereof to take out electric energy to the outside.

However, in the wiring structure as described above, when the diffusion layer 14 to be a wiring is formed on the surface layer of the silicon substrate 11, a slight step (Z in FIG. 6) is formed on the surface of the silicon substrate 11.
When the metal wiring 15 is connected to this wiring and the glass plate 12 is placed thereon, there is a problem that a gap is generated. On the other hand, FIG.
And the method as shown in FIG. 9 is further described in Baifukan "Micromachining and Micromechatronics". That is, after the glass plate 22 is anodically bonded onto the silicon substrate 21 and hermetically sealed, a hole penetrating the glass plate 22 to the silicon substrate 21 is formed on the diffusion layer 23 formed on the silicon substrate 21. Then, a metal film 24 is formed on the entire side surface and bottom surface of this hole to connect the diffusion layer 23 and the metal film 24. Then, a conductive material 25 such as solder or a conductive epoxy resin is further embedded in this hole, and a lead wire 26 is inserted to take out an electric wiring.

By adopting such a method, contact with the outside from the edge portion of the diffusion layer 24 is eliminated, and the problem of leakage of hermetic sealing by the silicon substrate 21 and the glass plate 22 can be solved. it can. But with the above method,
There is a problem that a step of forming a through hole in the glass plate 22 on the side where the electric wiring is taken out is required, and the manufacturing process becomes complicated.

Further, since the through hole usually has a height corresponding to the thickness of the glass plate used, for example, a height of 100 to 500 μm, the metal film 24 is continuously formed on the entire inner surface of the through hole without a gap. There is a need to. However, there is a problem in that a step break may occur at a corner portion at the bottom of the through hole, and a highly difficult process is required to prevent such a step break.

Further, since the electric wiring can be taken out only above the glass plate 22 and the electric wiring can be taken out in only one direction, there is a problem that the structure of the sensor is restricted. The present invention is intended to solve the above problems,
It is intended to provide a semiconductor sensor in which the direction of taking out the electric wiring is not limited, and a complete hermetic sealing is realized, and a manufacturing method thereof.

[0007]

According to the present invention, at least one substrate is made of a semiconductor, and a recess is formed in the main surface of at least one substrate, and the two substrates are joined together. There is provided a semiconductor sensor including an airtight portion, a metal wiring sandwiched between the substrates and taken out from the airtight portion, and a metal film filling a gap portion formed between the metal wiring and the substrate.

Further, according to the manufacturing method of the present invention, (i) at least one substrate is made of a semiconductor, and metal wiring is provided on any one of the two substrates having a recess on the main surface of at least one substrate. And (ii) joining the other substrate to the surface of the substrate on which the metal wiring is formed, and (iii) using a focused ion beam in the gap formed between the two substrates and the metal wiring. A method for manufacturing a semiconductor sensor is provided, in which a metal film is partially vapor-deposited to hermetically seal a recess formed in the substrate.

The semiconductor sensor in the present invention has an airtight portion such as a pressure sensor and a flow sensor, and also has a wiring layer which is drawn out from the airtight portion, so that the sensing can be performed in an airtight space. There is no particular limitation as long as it can be performed. As the substrate used in the present invention, it is preferable that at least one of the two substrates is a semiconductor substrate, and if one is a semiconductor substrate, the other substrate is not particularly limited. , A plastic substrate or the like can be used. Further, both of the two substrates may be semiconductor substrates. Further, it is necessary that a recess is formed on the surface of either one of the two substrates. In such a case, by joining the other substrate to the surface of one substrate, the airtightness can be improved. Parts will be configured. However, the airtight portion may be configured by using another substrate.

In the present invention, metal wiring is formed on any of the above substrates. The metal wiring is a metal wiring taken out from the airtight portion, and is connected to, for example, an impurity diffusion layer formed on the semiconductor substrate inside the airtight portion. This metal wiring can be deposited by a known method such as a vapor deposition method and a sputtering method, and can be patterned into a desired shape by a photolithography process, an etching method and the like. Examples of the material for the metal wiring include Al, Au, Cu, Si, N
b, Ti, Ge, Co, Ni, Ag, Ga or the like can be used. The film thickness at that time can be appropriately adjusted depending on the size of the semiconductor sensor to be formed, etc., but when used as a pressure sensor, for example, 1000 to 2000
Å is preferable.

Furthermore, the metal wiring is taken out to the outside from an airtight portion formed by joining at least two substrates, and is sandwiched between the two substrates. At that time, a gap corresponding to the film thickness of the metal wiring is generated between the two substrates and the metal wiring, particularly in the vicinity of the side surface of the metal wiring. In the present invention, this gap is a metal film. It is buried by. The material of this metal film is, for example, Al, Au, Cu, Si, Nb, Ti, as in the case of the metal wiring.
Ge, Co, Ni, Ag, Ga or the like can be used. This metal film is preferably formed by a focused ion beam (FIB) film formation method. The FIB may be a general FIB assisted deposition that supplies a gas to be a metal film, or an F using a liquid metal ion source.
IB direct vapor deposition (Japanese Patent Laid-Open No. 5-299716) may be used. The FIB conditions and the like can be appropriately adjusted depending on the substrate to be used, the thickness of the metal wiring, etc., as long as they are of a size and thickness that completely cover the gap between the substrate and the metal wiring, For example, the beam size is 10μ in diameter
m, the film forming rate is preferably about 200Å / sec, and the film forming time is preferably about 10 seconds.

[0012]

According to the semiconductor sensor of the present invention, it is possible to obtain a semiconductor sensor in which the gap between the substrate and the metal wiring caused by the unevenness of the metal wiring is completely covered. Further, according to the method for manufacturing a semiconductor sensor of the present invention, only the gap between the substrate and the metal wiring, which is a problem, is efficiently covered by the FIB.

[0013]

Embodiments of the semiconductor sensor of the present invention will be described with reference to the drawings. 1 to 4 are diagrams showing a main part of the pressure sensor 1. One of the pressure sensors 1 is a reference pressure chamber 2
This is a method in which the deformation amount of the diaphragm 3 facing (for example, vacuum) and to which the measurement pressure is applied to the other side is extracted as a change in the resistance value of the resistance layer formed in the periphery. Such a pressure sensor 1 includes a silicon substrate 6 on which a resistance region 4a to be a resistance layer in advance, a metal wiring 5 connected to a contact region 4b continuously formed on the resistance region 4a, and a diaphragm 3 are formed, A glass plate 7 (for example, SD-2 manufactured by HOYA Co., Ltd.) in which a concave portion serving as the reference pressure chamber 2 is formed is anodically bonded. 3 and FIG.
As shown in FIG. 4 in which X inside is enlarged, a metal film 8 is formed between the silicon substrate 6 and the glass plate 7 that sandwich the metal wiring 5 and near the side of the metal wiring 5.

A method of manufacturing the pressure sensor thus configured will be described below. First, boron is thermally diffused in the n-type silicon substrate 6 to form the contact region 4b. continue,
Ion such as boron at energy of 50 KeV 1 × 10
^By implanting ¹³ ions / cm ^{2 and} performing activation annealing, a resistance region 4a to be a resistance layer is formed. Then
The diaphragm, which will be the pressure-sensitive portion, is processed by anisotropic etching to a thinness of about several μm to several tens of μm.

After that, for example, an Al film is formed as a metal wiring 5 on the silicon substrate 6 at a position to be connected to the contact region 4b by vacuum vapor deposition to have a film thickness of about 2000 Å and processed into a desired shape. Then, the glass substrate 7 and the silicon substrate 6 on which the metal wiring 5, the resistance region 4a, the contact region 4b, and the diaphragm 3 are formed are anodically bonded. At this time, the glass plate 7 is joined while bending while reflecting the unevenness of the metal wiring 5 of the silicon substrate 6, and as shown in FIGS. 1 and 3, the side portion X of the metal wiring 5 is formed.
There is a gap in.

Next, as shown in FIG. 4, a metal film 8 is vapor-deposited by FIB in this gap. F at this time
The film formation rate in IB is, for example, about 200 Å / sec with a beam size of 10 μm in diameter. Since the thickness of the metal wiring is usually several thousand Å, in the above case it is 2,000
The gap in the X part is about 2000 Å. That is, FI
The area of the gap is much smaller than the beam size of B, and the film thickness of the metal film 8 for filling the gap is about 200.
Since 0Å is sufficient, the film formation time required to coat one gap is about 10 seconds. Incidentally. The deposition of the metal film in the gap may be continuously performed so as to fill the left and right gaps.

In the pressure sensor hermetically sealed by the silicon substrate and the glass plate as in the above embodiment, the metal wiring is taken out between the silicon substrate and the glass plate, and the metal film is formed near the side of the metal wiring. Since it is formed, the gap between the silicon substrate and the glass plate, which is formed in the vicinity of the metal wiring side portion, can be completely filled with the metal film, and a pressure sensor that is completely hermetically sealed can be obtained. . Further, by appropriately selecting the formation position of the diffusion layer, the formation position of the metal wiring, etc., for example, if the metal wiring is formed on the glass side and the glass is larger than the silicon substrate, the extraction of the metal wiring is limited to one direction. Instead, it can be taken out in any direction.

[0018]

According to the semiconductor sensor of the present invention, the gap portion between the substrate and the metal wiring caused by the unevenness of the metal wiring can be completely covered, and the airtight wiring of the semiconductor sensor or the like can be realized. Become. Further, by adopting such an airtight wiring method, the direction of taking out the metal wiring is not limited, and when designing the semiconductor sensor, there is no restriction by the position of the metal wiring, and a semiconductor sensor of any shape can be obtained You can

Further, according to the method of manufacturing a semiconductor sensor of the present invention, since the FIB is utilized, only the gap between the substrate and the metal wiring, which is a problem, can be concentrated and the film can be formed efficiently. It is possible to manufacture a semiconductor sensor having a completely airtight structure. Further, since it is possible to form a film even on a structure having a step, such as after the substrates are joined together,
A semiconductor sensor having an airtight structure can be efficiently manufactured.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a metal wiring portion of a pressure sensor which is an embodiment of a semiconductor sensor of the present invention.

FIG. 2 is a sectional view taken along the line AA ′ of FIG.

3 is a sectional view taken along line BB ′ of FIG.

FIG. 4 is a schematic enlarged view of a portion X in FIG.

FIG. 5 is a schematic plan view showing a metal wiring portion of a conventional pressure sensor.

6 is a cross-sectional view taken along the line AA ′ of FIG.

7 is a cross-sectional view taken along the line BB ′ of FIG.

FIG. 8 is a schematic plan view showing a metal wiring portion of another conventional pressure sensor.

9 is a cross-sectional view taken along the line AA ′ of FIG.

[Explanation of symbols]

 1 Pressure Sensor (Semiconductor Sensor) 2 Reference Pressure Chamber (Airtight Section) 3 Diaphragm 4a Resistance Region 4b Contact Region 5 Metal Wiring 6 Silicon Substrate (Substrate) 7 Glass Plate (Substrate) 8 Metal Film

Claims (2)

[Claims] 1. An airtight portion in which at least one substrate is made of a semiconductor, a concave portion is formed on a main surface of at least one substrate, and the two substrates are joined to each other.
A semiconductor sensor comprising: a metal wire sandwiched between the substrate and taken out from the airtight portion; and a metal film filling a gap formed between the metal wire and the substrate. 2. (i) At least one substrate is made of a semiconductor, and metal wiring is formed on one of the two substrates having a concave portion on the main surface of at least one substrate, (ii) The other substrate is joined to the surface of the substrate on which the metal wiring is formed, and (iii) a metal film is partially formed by a focused ion beam in the gap formed between the two substrates and the metal wiring. Then, the recess formed in the substrate is hermetically sealed, and the method for manufacturing a semiconductor sensor.