JP2002277338A - Manufacturing method of pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a pressure sensor capable of executing easily alignment between the center position of a film part of a diaphragm and a pressure introduction port and a pressure discharge port, and improving pressure measurement accuracy. SOLUTION: This method comprises a coating formation process for forming a coating 45 on the peripheral surface of the diaphragm 40 having a movable electrode and displaced relatively, a long cylindrical part extension process for extending a long cylindrical part 47 in the displacement direction of the diaphragm 40 from the coating 45 formed in the coating formation process, an electrode formation process for forming electrodes 50, 60 arranged on the position where the tip of the long cylindrical part 47 is projected on the outside surface or from the outside surface to the outside on at least one side of the diaphragm 40, and a removal process for removing the coating 45 and the long cylindrical part 47 by a chemical solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of manufacturing a capacitance type pressure sensor.

[0002]

2. Description of the Related Art Conventionally, as a pressure sensor of this type, for example, there is one as shown in FIG.
No. 09).

The pressure sensor 10 is a capacitance type pressure sensor that detects pressure as a change in capacitance, and includes an elastically deformable diaphragm 11 and a diaphragm 1.
1 is anodically bonded to the thick part 12 around the lower glass 1
3 and 14, a predetermined gap is formed between the diaphragm 11 and the upper and lower glasses 13 and 14.
That is, the diaphragm 11 has upper and lower glasses 13, 1
4 and are spaced apart from each other and are anodicly bonded to the upper and lower glasses 13 and 14 via the thick portion 12.

The diaphragm 11 is made of conductive silicon (Si), and the diaphragm 11 itself forms one electrode.

The upper glass 13 has a central electrode 15 on a surface 13A facing the diaphragm 11 and a central electrode 1
5 is provided. An anodic bonding electrode 17 used for anodic bonding is provided on the upper surface 13B of the upper glass 13.
Reference numeral 7 denotes a shape substantially corresponding to the edge of the diaphragm 11.

The lower glass 14 has a pressure inlet 18 provided at a substantially central position, and pressure is applied from the pressure inlet 18.

In such a pressure sensor 10, when pressure is applied to the pressure inlet 18, the diaphragm 11 is elastically deformed to be curved, and the diaphragm 11 and the upper glass 13 are deformed.
The distance between the center electrode 16 and the peripheral electrode 17 changes, and the capacitance changes in accordance with the distance, thereby performing pressure measurement. The pressure sensor 10 is a so-called gauge pressure (differential pressure with respect to the atmospheric pressure when the atmospheric pressure is set to zero), and a gap between the diaphragm 11 and the upper glass 13 is formed by a central electrode 17 and a peripheral electrode 18. It is open to the atmosphere through the through holes 19 and 20.

[0008]

By the way, the conventional pressure sensor 10 is manufactured by joining the upper and lower glasses 13 and 14 by anodic bonding while the diaphragm 11 is sandwiched from above and below.

In such a method of manufacturing the pressure sensor, when the upper and lower glasses 13 and 14 are anodic-bonded to the diaphragm 11, the diaphragm 11 and the upper and lower glasses 13 and 1 are joined together.
In some cases, a bonding error may occur relative to the diaphragm 4. For this reason, the pressure introduction port 18 of the lower glass 14 and the through hole 19 of the center electrode 17 of the upper glass 13 may be aligned with the center position of the film portion of the diaphragm 11. It is difficult.

Further, due to the displacement of the pressure introducing port 18 and the through hole 19 at the time of manufacturing the upper and lower glasses 13 and 14 and the displacement of the membrane at the time of manufacturing the diaphragm 11, these are not anodic bonded. In addition, the center position of the film portion of the diaphragm 11 is largely displaced from the pressure introduction port 18 of the lower glass 14 and the through hole 19 of the upper glass 13.

Thus, the center position of the membrane portion of the diaphragm 11, the pressure inlet 18 of the lower glass 14, and the upper glass 1
There is a problem that an error occurs between the introduced pressure and the measured pressure due to the positional deviation from the through hole 19 of No. 3 and the pressure measurement accuracy is deteriorated.

Therefore, the present invention makes it possible to manufacture a capacitance type pressure sensor having a double-sided structure without using anodic bonding. In addition, the center position of the membrane of the diaphragm, the pressure inlet and the pressure outlet, and the like can be obtained. It is an object of the present invention to provide a method for manufacturing a pressure sensor that can easily perform the alignment of the pressure sensor and improve the pressure measurement accuracy.

[0013]

In order to achieve the above object, the present invention is directed to a film forming step of forming a film on an outer peripheral surface of a diaphragm which has a movable electrode and is relatively displaced, and a method of forming the film. A rod-shaped part extending step of extending a rod-shaped part in the direction of displacement of the diaphragm from the coating formed by the step, and at least one side of the diaphragm, the tip of the rod-shaped part is on the outer surface or from the outer surface. And a removing step of removing the coating and the rod-shaped portion with a chemical solution.

According to the first aspect of the present invention, since the anodic bonding is not required, the problem of the bonding accuracy between the diaphragm and the electrode can be solved.

By removing the coating formed on the diaphragm and the rod-like portion extending from the coating in the direction of displacement of the diaphragm with a chemical solution, a gap is formed between the diaphragm and the electrode, and a pressure inlet is formed in the electrode. It is formed.

As a result, the gap and the pressure introduction port can be easily formed, and the pressure introduction port can be easily formed at the center position of the diaphragm. A sensor can be obtained.

According to a second aspect of the present invention, there is provided the method of manufacturing a pressure sensor according to the first aspect, wherein a concave portion is formed in a portion of the coating formed in the coating forming step where the rod portion extends. It is characterized by:

According to the second aspect of the present invention, the pressure introduction port can be formed more accurately in accordance with the center position of the diaphragm.

According to a third aspect of the present invention, there is provided the pressure sensor manufacturing method according to the first or second aspect, wherein the electrode is made of chromium, and the chemical is made of hydrofluoric acid.

According to the third aspect of the present invention, since chromium is a metal which is not etched by hydrofluoric acid, it is possible to form a suitable electrode in a pressure sensor manufactured using a wire bonding technique. it can.

According to a fourth aspect of the present invention, there is provided a pressure sensor manufacturing method according to any one of the first to third aspects,
The coating and the rod are formed of aluminum or gold.

In the invention according to the fourth aspect of the present invention, since the coating and the rod-shaped portion are made of aluminum or gold, the wire bonding connection can be easily performed and the etching can be easily performed with hydrofluoric acid. The gap and the pressure inlet can be easily formed.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a method for manufacturing a pressure sensor according to the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a pressure sensor 30 according to an embodiment of the present invention.

The pressure sensor 30 is a capacitance type pressure sensor which detects pressure as a change in capacitance, has a movable electrode, and is joined to a diaphragm 40 which is relatively displaced and a support portion 41 of the diaphragm 40 above and below. Upper electrode 50
And the lower electrode 60, and the diaphragm 40
A predetermined gap 70 is formed between the film portion 42 and the upper electrode 50 and the lower electrode 60.

The diaphragm 40 is made of conductive silicon (Si), and the film portion 42 serves as a movable electrode as a whole. The electrode body 51 of the upper electrode 50 and the electrode body 61 of the lower electrode 60 are made of chromium (Cr).

The electrode body 51 of the upper electrode 50 is formed in the direction of displacement with respect to the film part 42 of the diaphragm 40.
Pressure introduction port 52 is provided toward the center position of
Pressure is applied from the pressure inlet 52.

A notch 53 is formed at one end of the electrode body 51, and the support 41 of the diaphragm 40 located in the notch 53 is connected to a capacitance measuring circuit (not shown). A connection portion 43 is provided.

The electrode body 61 of the lower electrode 60 is provided with a pressure outlet 62 facing the pressure inlet 52 of the upper electrode 51, and the pressure outlet 62 is open to the atmosphere.

In such a pressure sensor 30, when pressure is applied to the pressure inlet 52, the membrane portion 42 of the diaphragm 40 is relatively displaced in the cavity 70 so as to be curved, and the electrode main body 61 of the upper electrode 60. And the capacitance changes in accordance with the distance. Diaphragm 4
The pressure is measured by an electrostatic capacitance measuring circuit (not shown) connected to the connection section 43 of No. 0.

Next, FIGS. 2A to 2D and FIG.
With reference to (a) to FIG. 3 (c), FIG. 4 (a) to FIG. 4 (c) and FIG. 5, a method of manufacturing the pressure sensor 30 of the present embodiment will be described step by step.

First, in a first step, as shown in FIG. 2A, a single crystal silicon wafer having a natural oxide film is etched to form a diaphragm 40.

In the second step, as shown in FIG.
After removing the natural oxide film of the diaphragm 40 formed in the first step, the entire surface of the diaphragm 40 is oxidized to form an insulating film (oxide film) 44. After that, diaphragm 4
In addition, the insulating film (oxide film) 44 of the film portion 42 of the “0” is removed by etching or the like, and the supporting portion 41 of the diaphragm 40 is removed.
The notch 53 is formed by partially removing the insulating film (oxide film) 44 at one end of the substrate by etching or the like.

In the third step, as shown in FIG. 2C, aluminum (Al) is formed in the film portion 42 from which the insulating film (oxide film) 44 has been removed in the second step and the cutout portion 53 of the support portion 41. Alternatively, an aluminum film or a gold film (film) 45 is formed by metal deposition or plating of gold (Au).

Then, as shown in FIG. 5, the film portion 42 of the diaphragm 40 on which the aluminum or gold film 45 is formed.
A concave portion 46 is formed at the center position of the substrate by dicing or metal etching. The concave portion 46 is provided with a rod-shaped portion 4 described later.
9 is a wire marking made of aluminum or gold when 9 is extended to the film part 42.

In the fourth step, as shown in FIG.
The back surface 40B side of the diaphragm 40 is protected by a resist 80, and the concave portion 46 formed in the film portion 42 in the third step is formed.
Then, a wire made of aluminum or gold is erected perpendicularly to the film part 42 to form a rod, and the rod part 47 is extended to the film part 42 by wire bonding.

The wire bonding technique is generally a technique for connecting an IC chip and an IC package with an aluminum wire or a gold wire. In the present embodiment, a wire made of aluminum or gold is set up vertically to form a bar. Have applied.

The fifth step is an electrode forming step, as shown in FIG.
As shown in (a), with the back surface 40B side of the diaphragm 40 protected by the resist 80, the top end of the rod-shaped portion 47 formed in the fourth step is placed on the upper surface 40A of the diaphragm 40 from the outer surface or from the outer surface. An upper electrode 50 is formed at an outer position. The upper electrode 50 is formed by depositing chromium (Cr) or the like that is not etched by hydrofluoric acid (chemical solution) by metal deposition or plating.

In the sixth step, as shown in FIG.
The upper surface of the upper electrode 50 made of chromium (Cr) formed in the fifth step is subjected to CMP until the rod-shaped portion 47 can be observed.
(Chemical Mechanical Poli
(shing) processing to perform flattening.

The CMP technique has been conventionally used in the final mirror polishing step of a Si substrate. During mechanical polishing, a chiller in which inorganic fine particles such as silica are dispersed is dropped on a polishing part to obtain a mechanical effect. This is a technique for flattening by chemical action.

Thus, the upper surface 40A of the diaphragm 40
When the process of forming the upper electrode 50 is completed, FIG.
As shown in (c), the resist 80 provided for protecting the back surface 40B of the diaphragm 40 is removed.

Next, the diaphragm 40 is turned over,
As shown in FIG. 4A, the rod-shaped portion 47 is formed by performing the processes of the seventh to ninth steps similar to the above-described fourth to sixth steps with the back surface 40B of the diaphragm 40 facing upward. The lower electrode 60 is formed. In this case, the upper electrode 50 plays the role of a resist.

In the tenth step, as shown in FIG. 4B, the support portion 41 in the notch portion 53 formed in the second step is dug out by dicing or dry etching to form a capacitance measuring circuit. The connection part 43 connected to the not shown (not shown) is formed. At this time, some chromium (Cr) is left on the surface to prevent etching by hydrofluoric acid.

The eleventh step is the final step, and as shown in FIG. 1 and FIG.
This is a removal step for removing. In the eleventh step, the coating 45 made of aluminum or gold formed on the film part 42 of the diaphragm 40 in the third step described above and the aluminum or gold extended on the film part 42 in the fourth and seventh steps are used. The rod-shaped portion 47 is removed by etching using hydrofluoric acid (chemical solution).

The film portion 42 of the diaphragm 40 and the upper electrode 50 are formed by the portion of the film portion 42 from which the coating 45 has been removed.
A gap 70 is formed between the lower electrode 60 and the lower electrode 60, and the pressure introduction port 52 is formed by a portion of the upper electrode 50 from which the rod 47 is removed. An outlet 62 is formed.

Thus, a capacitance type pressure sensor 30 having a double-sided structure can be obtained.

In the method of manufacturing the pressure sensor according to the present embodiment, since the anodic bonding is not required, the problem of the bonding accuracy between the diaphragm 40 and the upper and lower electrodes 50 and 60 can be solved.

Since the pressure inlet 52 of the upper electrode 50 and the pressure outlet 62 of the lower electrode 60 are formed by wire bonding, the pressure inlet 52 is easily and reliably aligned with the center position of the membrane portion 42 of the diaphragm 40. And the problem of misalignment is eliminated.

Further, the gap 70 between the film portion 42 of the diaphragm 40 and the upper electrode 50 and the lower electrode 60 can be easily formed.

As a result, according to the pressure sensor manufacturing method of the present embodiment, it is possible to obtain the pressure sensor 30 with high pressure measurement accuracy.

Further, since the pressure inlet 52 and the pressure outlet 62 are formed using aluminum or gold wire by wire bonding, for example, the pressure inlet 52 is bent 90 degrees by utilizing the bending characteristics of the wire. The degree of freedom of the structure is increased, for example, the structure can be made.

Further, since the upper and lower glasses of the conventional pressure sensor are not required, it can be manufactured at low cost.

The technique using wire bonding used in the present embodiment can be applied to a transducer, a circuit process, and the like in addition to the pressure sensor 30.
For example, optical waveguides, mold molding, brain wave detection, and the like can be considered.

Further, in the pressure sensor 30 of the present embodiment,
Although the diaphragm 40 has a double-sided structure sandwiched between the upper electrode 50 and the lower electrode 60, the upper electrode 50 may be omitted depending on the usage.

[0055]

As described above, the first aspect of the present invention does not require anodic bonding, so that the problem of the accuracy of bonding between the diaphragm and the electrode can be solved.

By removing the coating formed on the diaphragm and the rod-like portion extending from the coating in the direction of displacement of the diaphragm with a chemical solution, a gap is formed between the diaphragm and the electrode, and a pressure inlet is formed in the electrode. Is formed, the gap and the pressure introduction port can be easily formed, and the pressure introduction port can be easily formed at the center position of the diaphragm.

As a result, the pressure measurement accuracy of the pressure sensor can be improved.

According to the second aspect of the present invention, the pressure introduction port can be formed more accurately in accordance with the center position of the diaphragm.

According to the third aspect of the present invention, since chromium is gold which is not etched with hydrofluoric acid, a suitable electrode can be formed in a pressure sensor manufactured using a wire bonding technique.

According to the fourth aspect of the present invention, since the film and the rod-shaped portion are formed of aluminum or gold, the wire bonding connection can be facilitated and the etching can be easily performed with hydrofluoric acid. The inlet can be easily formed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a pressure sensor according to an embodiment of the present invention.

FIGS. 2A to 2D are cross-sectional views illustrating a method for manufacturing the pressure sensor shown in FIG. FIG. 2 (a)
FIG. 4 is an explanatory view of a first step. FIG. 2B is an explanatory diagram of the second step. FIG. 2C is an explanatory diagram of the third step. FIG. 2D is an explanatory diagram of the fourth step.

3A to 3C are cross-sectional views illustrating a method for manufacturing the pressure sensor shown in FIG. FIG. 3 (a)
Is an explanatory diagram of the fifth step. FIG. 3B is an explanatory diagram of the sixth step. FIG. 3C is an explanatory diagram of the step of removing the resist.

FIGS. 4A to 4C are cross-sectional views illustrating a method for manufacturing the pressure sensor shown in FIG. FIG. 4 (a)
FIG. 9 is an explanatory view showing a state in which processing from a seventh step to a ninth step similar to processing from the fourth step to the sixth step has been performed. FIG. 4B is an explanatory diagram of the tenth step. FIG.
(C) is an explanatory view of an eleventh step.

FIG. 5 is an explanatory view of a wire bonding marking in a third step.

FIG. 6 is an exploded perspective view showing a conventional pressure sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 30 ... Pressure sensor 40 ... Diaphragm 45 ... Coating 46 ... Recess 47 ... Bar-shaped part 50 ... Upper electrode (electrode) 60 ... Lower electrode (electrode)

Claims (4)

[Claims] 1. A film forming step of forming a film on an outer peripheral surface of a diaphragm having a movable electrode and being relatively displaced, and a rod-shaped portion extending from the film formed in the film forming step in a direction of displacement of the diaphragm. A rod-shaped part extending process to
An electrode forming step of forming an electrode on at least one side of the diaphragm, the electrode being disposed at a position where the tip of the rod-shaped portion protrudes outward from the outer surface or from the outer surface; and removing the coating and the rod-shaped portion with a chemical solution. A method of manufacturing a pressure sensor. 2. The method for manufacturing a pressure sensor according to claim 1, wherein a concave portion is formed in a portion of the coating formed in the coating forming step where the bar-shaped portion extends. Manufacturing method of pressure sensor. 3. The method for manufacturing a pressure sensor according to claim 1, wherein the electrode is made of chromium, and the chemical is made of hydrofluoric acid. 4. The method for manufacturing a pressure sensor according to claim 1, wherein the coating and the rod are formed of aluminum or gold. Manufacturing method of sensor.