JP3144314B2 - Semiconductor pressure sensor and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor pressure sensor having improved overpressure resistance and a method of manufacturing the same.

[0002]

2. Description of the Related Art FIG. 13 is an explanatory view of a main part of a conventional example generally used in the prior art.
No. 4027.

In FIG. 1, reference numeral 1 denotes a silicon substrate.
Reference numeral 2 denotes a void space provided on the silicon substrate 1 and forming the measurement diaphragm 3 on the silicon substrate 1.

[0004] Reference numeral 4 denotes a communication hole for communicating the gap chamber 2 with the outside. Reference numeral 5 denotes a thin film for closing the communication hole 4. Thin film 5
For example, polysilicon or the like formed by a low pressure CVD method is used.

[0005] The atmosphere pressure at the time of forming the polysilicon by the low pressure CVD method is sealed in the space 2.
Since the pressure is about 0.2 Torr, the degree of vacuum is sufficient as the reference pressure of the absolute pressure sensor.

Reference numeral 6 denotes a distortion detection sensor provided on the measurement diaphragm 3. The distortion detection sensor 6 includes, for example,
A piezoresistive strain gauge or a vibrating strain gauge with fixed beams at both ends is used.

In the above configuration, when the measurement pressure Pm is applied, the measurement diaphragm 3 bends in proportion to the difference between the pressure in the gap chamber 2 (substantially vacuum), and strain is applied to the strain detection sensor 6. By measuring this strain, the measured pressure Pm is detected.

[0008]

However, in such an apparatus, when an overpressure is applied, the measurement diaphragm 3 is directly backed up by the gap chamber 2 and has an advantage that no extra overpressure protection is required. Stress concentration occurs in the peripheral edge portion 3 of 3. The present invention solves this problem.

It is an object of the present invention to provide a semiconductor pressure sensor with improved overpressure resistance and a method of manufacturing the same.

[0010]

In order to achieve the above object, the present invention provides a semiconductor pressure sensor for receiving a measurement pressure, comprising: a silicon substrate; a measurement device provided on the silicon substrate and formed by epitaxial growth. A sealed cavity having a predetermined narrow gap that forms a diaphragm and provides a backup against excessive pressure application to the diaphragm, and a measurement diaphragm provided on a surface of the cavity that backs up the measurement diaphragm, and the measurement diaphragm is applied with an excessive pressure. A back-up part formed in a concave shape as a whole so that stress concentration does not occur at the peripheral edge of the measurement diaphragm when the measurement diaphragm is displaced, and a strain detecting element built in the measurement diaphragm. A semiconductor pressure sensor according to the present invention is constituted. (2) A method of manufacturing a semiconductor pressure sensor for receiving a measurement pressure, the method including the following steps. (A) A resist application step of applying a resist to a predetermined portion of a silicon substrate. (B) a first ion implantation step of forming a first silicon oxide layer on the silicon substrate by implanting oxygen ions from a first predetermined portion of the silicon substrate where the resist is not applied, by jumping over a portion corresponding to the measurement diaphragm; . (C) enlarging the coated surface of the resist and implanting oxygen ions into the silicon substrate from a second predetermined location reduced from the first predetermined location by jumping over the first silicon oxide layer; A second ion implantation step of forming a silicon dioxide layer on the silicon substrate. (D) enlarging the coated surface of the resist, and implanting oxygen ions into the silicon substrate from a third predetermined location reduced from the second predetermined location by jumping over the second silicon oxide layer; A third ion implantation step of forming a silicon trioxide layer on the silicon substrate; (E) A gauge forming step of injecting predetermined ions into a portion corresponding to the measurement diaphragm to form a strain detecting element. (F) a lead forming step of injecting predetermined ions into a portion corresponding to the measurement diaphragm and forming a lead having a first end connected to the strain detecting element at a fourth predetermined location; (G) forming a communication hole from the surface of the silicon substrate to the first silicon oxide layer; (H) The first and the first holes are selectively etched from the communication holes.
A selective etching step for removing the second and third silicon oxide layers; (I) forming a silicon oxide film on the surface of the silicon substrate by sputtering to close the communication hole and form an insulating film on the surface of the silicon substrate;
Insulating film forming step. (J) After sputtering the electrode material on the surface of the silicon substrate,
An electrode forming step of forming an electrode on the other end of the lead by photolithography. It was adopted.

[0011]

In the above arrangement, when the measurement pressure is applied, the measurement diaphragm bends in proportion to the difference between the measurement pressure and the pressure in the gap chamber, and the strain is applied to the strain detection sensor. The measured pressure is detected.

When an excessive pressure is applied to the measurement diaphragm, the measurement diaphragm is backed up by the backup unit. Hereinafter, a detailed description will be given based on embodiments.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory diagram of a main part configuration of an embodiment of the present invention. 11 is a silicon substrate. 12
Is a void chamber provided on the silicon substrate 11 and forming the measurement diaphragm 13 on the silicon substrate 11.

Reference numeral 121 is provided on a surface of the cavity chamber 12 for backing up the measurement diaphragm 13, so that when the measurement diaphragm 13 is displaced by application of an excessive pressure, stress is not concentrated on the peripheral portion 131 of the measurement diaphragm 13. Is a backup portion formed in a concave shape and formed in a step shape.

Reference numeral 14 denotes a communication hole for communicating the gap chamber 22 with the outside. Reference numeral 15 denotes an insulating film that covers the communication hole 14 and is provided on the surface of the silicon substrate 11. In this case, silicon oxide is used.

Reference numeral 16 denotes a distortion detection sensor provided on the measurement diaphragm 13. As the strain detection sensor 16, for example, a piezoresistive strain gauge, a vibrating strain gauge with fixed beams at both ends, or the like is used. Reference numeral 17 denotes a lead having one end connected to the strain detection sensor 16. 18 is the lead 17
Is an electrode connected to the other end.

In the above configuration, when the measurement pressure Pm is applied, the measurement diaphragm 13 bends in proportion to the difference between the pressure in the gap chamber 12 (substantially vacuum), and strain is applied to the strain detection sensor 16. By measuring this distortion,
The measured pressure Pm is detected. Thus, when an excessive pressure is applied to the measurement diaphragm 13, the measurement diaphragm 13 is backed up by the backup unit 121 as shown in FIG.

As a result, the measurement diaphragm 13 is provided on the surface of the gap chamber 12 which backs up the measurement diaphragm 13, and when the measurement diaphragm 13 is displaced by the application of excessive pressure, stress concentration is not generated on the peripheral edge 131 of the measurement diaphragm 13. Since the backup portion 121 is formed in a concave shape and is formed in a step shape, stress concentration on the peripheral portion 131 of the measurement diaphragm is alleviated even when an excessive pressure is applied, and the overpressure characteristic is improved. An improved semiconductor pressure sensor is obtained.

Such an apparatus is manufactured as shown in FIGS. (A) FIG. 3 shows a resist coating step. Silicon substrate 1
01 is coated with a resist 102.

(B) FIG. 4 shows a first ion implantation step.
First predetermined location 103 where resist 102 is not applied
Then, oxygen ions O ⁺ are implanted into the silicon substrate 101 by jumping over the measurement diaphragm corresponding portion 104,
A first silicon oxide layer 105 is formed on a silicon substrate 101. Such an ion implantation method can be easily implemented by controlling the voltage at the time of implantation.

(C) FIG. 5 shows a second ion implantation step.
The coating surface of the resist 102 is enlarged, and the first predetermined location 10
The oxygen ions O ⁺ are supplied to the silicon substrate 101 from the second predetermined portion 106 reduced from
5 is ion-implanted over the second silicon oxide layer 10
7 is formed on the silicon substrate 101.

(D) FIG. 6 shows a third ion implantation step.
The application surface of the resist 102 is enlarged, and the second predetermined location 10
6, oxygen ions O ⁺ are supplied to the silicon substrate 101 from the third predetermined portion 108 which is smaller than the second silicon oxide layer 10.
7 is implanted, and the third silicon oxide layer 10 is implanted.
9 is formed on the silicon substrate 101.

(E) FIG. 7 shows a gauge forming step. P ⁺ ions are implanted into the measurement diaphragm corresponding portion 104 to form the strain detection element 111. (F) FIG. 8 shows a lead forming step. P ⁺ ions are implanted into the measurement diaphragm corresponding portion 104, and a lead 11 having one end connected to the strain detecting element 111 is provided at a fourth predetermined location.
Form 2

(G) FIG. 9 shows a communication hole forming step. From the surface of the silicon substrate 101, the first silicon oxide layer 105
Is formed. (H) FIG. 10 shows a selective etching step. Communication hole 11
3, the first, second, and third silicon oxide layers 105, 107, and 109 are removed by selective etching.

(I) FIG. 11 shows a step of closing a communication hole and forming an insulating film. A silicon oxide film 114 is formed on the surface of the silicon substrate 101 by sputtering to close the communication hole 113 and form an insulating film on the surface of the silicon substrate 101.

(J) FIG. 12 shows an electrode forming step. An electrode material, in this case, aluminum is applied to the silicon substrate 101.
The electrode 115 is formed on the other end of the lead 112 by photolithography after sputtering on the surface of the lead.

In the above-described embodiment, the space 1
Although it has been described that 2 is a vacuum, when used as a gauge pressure sensor, it goes without saying that the gap chamber 12 may be set to the atmospheric pressure.

[0028]

As described above, according to the first aspect of the present invention, when the measuring diaphragm is displaced by the application of an excessive pressure, the measuring diaphragm is provided on the surface of the gap chamber for backing up the measuring diaphragm. Since the back-up part is formed in a concave shape as a whole so that stress concentration does not occur at the peripheral part, and the backup part is formed in a stepped shape, stress concentrates on the peripheral part of the measurement diaphragm even when excessive pressure is applied. Therefore, a semiconductor pressure sensor having improved overpressure characteristics can be obtained.

According to the second aspect of the present invention, there is provided a method of manufacturing a semiconductor pressure sensor capable of realizing a semiconductor pressure sensor with improved overpressure characteristics.

Therefore, according to the present invention, it is possible to realize a semiconductor pressure sensor with improved overpressure resistance and a method of manufacturing the same.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a configuration of an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of FIG. 1;

FIG. 3 is an explanatory view of a resist coating step in FIG. 1;

FIG. 4 is an explanatory view of a first ion implantation step of FIG. 1;

FIG. 5 is an explanatory view of a second ion implantation step of FIG. 1;

FIG. 6 is an explanatory view of a third ion implantation step of FIG. 1;

FIG. 7 is an explanatory view of a gauge forming step of FIG. 1;

FIG. 8 is an explanatory view of a lead forming step of FIG. 1;

FIG. 9 is an explanatory view of a communication hole forming step of FIG. 1;

FIG. 10 is an explanatory diagram of a selective etching step in FIG. 1;

FIG. 11 is an explanatory view of a step of closing a communication hole and forming an insulating film in FIG. 1;

FIG. 12 is an explanatory view of an electrode forming step of FIG. 1;

FIG. 13 is an explanatory diagram of a configuration of a conventional example generally used in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Silicon substrate 12 Gap room 121 Backup part 13 Measurement diaphragm 131 Peripheral part 14 Communication hole 15 Insulating film 16 Strain detection sensor 17 Lead 18 Electrode 101 Silicon substrate 102 Resist 103 First predetermined place 104 Measurement diaphragm corresponding portion 105 First silicon oxide layer 106 second predetermined location 107 second silicon oxide layer 108 third predetermined location 109 third silicon oxide layer 111 strain detection element 112 lead 113 communication hole 114 silicon oxide layer 115 electrode

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-155774 (JP, A) JP-A-58-52882 (JP, A) JP-A-7-49281 (JP, A) 229860 (JP, A) JP-A-6-221945 (JP, A) JP-A-4-2066663 (JP, A) JP-A-58-180927 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01L 9/04 H01L 29/84

Claims (2)

(57) [Claims] 1. A semiconductor pressure sensor for receiving a measurement pressure, comprising: a silicon substrate; a predetermined diaphragm provided on the silicon substrate; and a measurement diaphragm formed by epitaxial growth and serving as a backup for applying an excessive pressure to the diaphragm. And a closed space having a gap, and provided on a surface of the gap chamber for backing up the measurement diaphragm so that stress concentration does not occur at the peripheral edge of the measurement diaphragm when the measurement diaphragm is displaced by application of excessive pressure. A semiconductor pressure sensor, comprising: a backup part formed in a concave shape as a whole and formed stepwise; and a strain detecting element built in the measurement diaphragm. 2. A method of manufacturing a semiconductor pressure sensor for receiving a measurement pressure, the method comprising the following steps. (A) A resist application step of applying a resist to a predetermined portion of a silicon substrate. (B) a first ion implantation step of forming a first silicon oxide layer on the silicon substrate by implanting oxygen ions from a first predetermined portion of the silicon substrate where the resist is not applied, by jumping over a portion corresponding to the measurement diaphragm; . (C) enlarging the coated surface of the resist and implanting oxygen ions into the silicon substrate from a second predetermined location reduced from the first predetermined location by jumping over the first silicon oxide layer; A second ion implantation step of forming a silicon dioxide layer on the silicon substrate. (D) enlarging the coated surface of the resist, and implanting oxygen ions into the silicon substrate from a third predetermined location reduced from the second predetermined location by jumping over the second silicon oxide layer; A third ion implantation step of forming a silicon trioxide layer on the silicon substrate; (E) A gauge forming step of injecting predetermined ions into a portion corresponding to the measurement diaphragm to form a strain detecting element. (F) a lead forming step of injecting predetermined ions into a portion corresponding to the measurement diaphragm and forming a lead having a first end connected to the strain detecting element at a fourth predetermined location; (G) forming a communication hole from the surface of the silicon substrate to the first silicon oxide layer; (H) The first and the first holes are selectively etched from the communication holes.
A selective etching step for removing the second and third silicon oxide layers; (I) forming a silicon oxide film on the surface of the silicon substrate by sputtering to close the communication hole and form an insulating film on the surface of the silicon substrate;
Insulating film forming step. (J) After sputtering the electrode material on the surface of the silicon substrate,
An electrode forming step of forming an electrode on the other end of the lead by photolithography.