JP3472865B2 - Manufacturing method of gas rate sensor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of a gas rate sensor by a micromachining process for electrically detecting a deflection state of a gas flow according to an angular velocity acting on a sensor body. About the method. [0002] Generally, in a gas rate sensor,
A gas is ejected from a nozzle hole in the sensor main body to a heat sensor composed of thermosensitive resistance elements provided on the left and right sides of the gas passage by a pump, and a gas flow flowing in the gas passage due to an external angular velocity motion is applied. When deflected in the left-right direction, an electric signal corresponding to the change state of the resistance value generated in the heat sensor is taken out, and the direction and magnitude of the angular velocity acting on the sensor body at that time are detected. . Conventionally, as this type of gas rate sensor,
There has been developed an ultra-small sensor body including a nozzle hole, a gas passage, and a heat sensor provided in the gas passage formed by micromachining a semiconductor substrate using an IC manufacturing technique (Japanese Patent Application Laid-Open No. HEI 5-1993). -2
027). As shown in FIGS. 4 to 6, the gas rate sensor includes a gas rectifying groove 31, a nozzle small groove 40, a gas passage groove 51, and a sensor bridge 6 as shown in FIGS. The lower substrate 1 ′ formed by micromachining and the upper substrate 2 ′ formed by etching the semiconductor substrate with the gas rectifying groove 32 and the gas passage groove 52 are combined with the respective grooves 31. The rectifying chamber (groove 3) for rectifying the gas supplied from a pump (not shown) is formed by superposing the 32 and 51 and 52 so as to abut each other and bonding them together.
1, 32), a nozzle hole 4 and a gas passage 5 are formed. The sensor bridge 6 is arranged so as to cover the gas passage 5. In the figure, 10 is a rectifying wall, 11 is a gas inlet, and 12 is a gas outlet. A pair of left and right heat sensors 71 and 72 are formed on the upper surface of the sensor bridge 6 by a thin film pattern. In the figure, 9 is each electrode of the heat sensors 71 and 72. However, in such a gas rate sensor formed by micromachining a semiconductor substrate, the processing accuracy of the sensor bridge on the gas passage is directly linked to the angular velocity detection accuracy of the gas rate sensor. It has become something. As a conventional means for reducing the cost in mass production, it is conceivable to reduce the chip size of the semiconductor substrate to increase the number of chips to be obtained per wafer. In principle, the performance is degraded, and the chip size cannot be easily reduced. [0008] The problem to be solved is that, when the upper substrate and the lower substrate are formed using a semiconductor substrate, the chip size of the semiconductor substrate increases and the chip size per wafer increases. And the cost is high. Further, in mass production, when a lower substrate is obtained by dicing a semiconductor substrate on which a plurality of required micro-machining processes are continuously performed, a sensor bridge portion having a fine structure is easily broken at the time of dicing. That is. According to the present invention, when manufacturing a sensor body of a gas rate sensor by micromachining, the size of a semiconductor chip used can be reduced while maintaining high processing accuracy of a sensor bridge portion. In addition, in order to be able to manufacture the sensor main body with good workability, the sensor main body is manufactured by joining a flow path portion including a nozzle hole and a gas passage and a sensor portion including a sensor bridge related to the gas passage. After that, the lower substrate in which a plurality of sensor bridges spanning the groove by micromachining processing of the semiconductor substrate, and the upper substrate in which a plurality of grooves are arranged,
The sensor part is formed by dicing the bonded parts so that the grooves of both substrates are aligned, and only the lower substrate of the sensor part, where processing accuracy is particularly required, is formed by micromachining processing of the semiconductor substrate However, the other components can be formed into a molded body of another material such as ceramic. FIGS. 1 and 2 show a sensor body of a gas rate sensor manufactured according to the present invention. Here, the deflection state of the gas flow ejected from the nozzle hole in the sensor body into the gas passage when the angular velocity acts is electrically detected as a change in the thermal resistance of the sensor bridge in the gas passage. In the gas rate sensor, a sensor main body is manufactured by joining a flow path portion 1 including a nozzle hole and a gas passage and a sensor portion 2 including a sensor bridge over the gas passage. The flow path portion 1 includes a gas rectifying groove 3
1, a lower base 1A provided with a small groove 40 for nozzle and a groove 51 for gas passage, and an upper substrate 1B provided with a groove 32 for gas rectification and a groove 52 for gas passage, respectively. By superimposing the grooves 31 and 32 and 51 and 52 so as to abut each other and bonding them together, a rectifying chamber (a chamber formed by the grooves 31 and 32), a nozzle hole 4 and a gas passage 5 are formed. Has become. The lower substrate 1A and the upper substrate 1B are formed by molding a ceramic material, a metal material, or a synthetic resin material. The flow path portion 1 is not limited to the joint structure between the lower substrate 1A and the upper base 1B, but may have an integral punching structure. As the sensor portion 2, the lower substrate 2 formed so that the sensor bridge 6 extends over the gas passage groove 51 by micromachining processing of a semiconductor substrate.
A and the upper substrate 2B in which the gas passage grooves 52 are formed by etching of a semiconductor substrate or a molded body of ceramic or the like are overlapped so that the grooves 51 and 52 are brought into contact with each other. Gas passage 5
The sensor bridge 6 is formed so as to cover the sensor bridge 6. As the lower substrate 2A, for example, a silicon nitride film serving as a bridge 8 is provided on a silicon substrate, and a pair of left and right heat sensors 7 made of platinum are formed on the silicon nitride film.
After patterning 1, 72, it is formed by etching the silicon substrate in a predetermined manner. The electrode portions 9 of the heat sensors 71 and 72 in the sensor bridge 6 are integrally formed on the lower substrate 2A in a pattern. In the gas rectifying groove 31 of the lower substrate 1A, a rectifying wall 10 for diverting and rectifying the gas sent into the rectifying chamber is integrally formed. The upper substrate 1B is provided with a gas inlet 11 for sending gas into the rectification chamber by a pump (not shown). The sensor portion 2 is provided with an outlet 12 for gas flowing through the gas passage 5. According to the sensor body of the gas rate sensor manufactured in this manner, the processing accuracy of the sensor bridge 6 on the gas passage 5 is ensured by the micromachining of the semiconductor substrate, and the rectifying chamber and the nozzle hole 4 are secured. Substrate 1 and lower substrate 2 for forming gas passage 5
Can be formed into a molded body such as a ceramic material other than a semiconductor. Therefore, when the sensor body is manufactured by micromachining, the size of the semiconductor chip to be used can be minimized while the detection accuracy of the angular velocity is sufficiently increased, and the number of chips obtained per wafer is greatly increased. Increase. Further, the manufacturing process becomes easy. In the method of manufacturing such a gas rate sensor, particularly in the present invention, in mass production, as shown in FIG. 3, a groove 51 for a gas passage and a groove 51 for the gas passage are formed by micromachining a semiconductor (silicon) substrate. A plurality of gas bridge grooves 52 are formed on the lower substrate 21 (FIG. 3A) in which a plurality of sensor bridges 6 extending over the grooves 51 are arranged in series.
Are mounted on the upper substrate 22 in which the grooves 51 and 5 of both substrates are arranged.
Then, the two sensor parts 2 are separated from each other by dicing using a diamond cutter or a laser cutter (FIG. 3C). I have. Therefore, according to the present invention, a plurality of semiconductor substrates (the lower base 21) in which a plurality of gas passage grooves 51 and sensor bridges 6 spanning the grooves 51 are arranged in series by micromachining. In the dicing, since the upper substrate 22 is covered with dicing, the microstructured sensor bridge 6 is protected by the upper substrate 2 and is surely broken by the water pressure at the time of dicing. Can be prevented. As described above, in the method of manufacturing a gas rate sensor according to the present invention, when manufacturing the sensor body of the gas rate sensor by micromachining, the flow path portion including the nozzle hole and the gas passage is required. A lower substrate in which a plurality of sensor bridges spanning a groove are formed by micromachining a semiconductor substrate, after the sensor body is manufactured by joining a sensor portion including a sensor bridge over a gas passage, The sensor part is formed by dicing the upper substrate with a plurality of grooves arranged side by side so that the grooves of both substrates are attached to each other, so that the processing accuracy of the sensor bridge part is kept high. While reducing the size of the semiconductor chip used and making the sensor body workable. It has the advantage that it can be manufactured well.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view showing a sensor main body of a gas rate sensor manufactured according to the present invention. FIG. 2 is a perspective view showing a state in which a flow path part and a sensor part in a sensor main body of a gas rate sensor manufactured by the present invention are separated. FIG. 3 is a diagram showing a manufacturing process of a sensor part according to the present invention. FIG. 4 is a plan view of a lower semiconductor substrate of a conventional gas rate sensor. FIG. 5 is a plan view of an upper semiconductor substrate of a conventional gas rate sensor. FIG. 6 is a front sectional view of a nozzle hole portion of a conventional gas rate sensor. [Description of Signs] 1 flow path portion 2 sensor portion 4 nozzle hole 5 gas passage 6 sensor bridge 71 heat sensor 72 heat sensor 8 bridge 21 lower substrate 22 upper substrate

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01P 9/00 G01C 19/00

Claims (1)

(57) [Claim 1] The state of deflection of a gas flow ejected from a nozzle hole in a sensor body into a gas passage when an angular velocity is applied is determined by a heat-sensitive resistance in a sensor bridge applied to the gas passage. In a method of manufacturing a gas rate sensor that electrically detects as a change in the sensor body, a sensor main body is manufactured by joining a flow path portion including a nozzle hole and a gas passage and a sensor portion including a sensor bridge related to the gas passage. Then, the lower substrate with multiple sensor bridges spanning the groove and the upper substrate with multiple grooves are bonded together by micromachining the semiconductor substrate so that the grooves on both substrates meet. Manufacturing method of a gas rate sensor, characterized in that a sensor portion is formed by dicing the product. .