JPH0562827B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tactile sensor, and more particularly to a tactile sensor made of semiconductor and used in a robot's hand or the like.

[Conventional technology]

In recent years, inexpensive and high-performance microcomputers have become widespread, and by using them, automation or robotization is progressing in various industrial fields. However, the robots currently in practical use are
It is only possible to lift or carry an object of a certain shape, size, or weight, or to process or assemble an object according to a certain program.

On the other hand, due to the diversification of consumer groups, there is a strong trend towards high-mix, low-volume production, and FMS (Flexible
The development of automation technology called "Manufacturing System" is being called for. In this trend of automation, it is necessary to equip robots or automatic machines with various sensors that replace human sense organs, and to take in information for control from the sensors. Among such sensors, sensors are equipped on the fingers or hands of robots, and can recognize the shape of an object by directly touching it, or judge the hardness of the object from the sense of pressure, or detect small parts. There is a recognized need for tactile sensors to measure forces from objects during assembly operations.

[Problem that the invention seeks to solve]

Various tactile sensors have been reported so far, including those using pressure-sensitive conductive rubber, those using microswitches, and those using carbon fiber (Automatic Technology Vol. 14, No. 6, p. 37 -
42 and 61-70). These tactile sensors have the disadvantage that they are too large, have poor linearity or repeatability, or can only detect on-off information. In addition, when measuring pressure distribution, it is necessary to arrange single pressure sensors in an array, but this requires an extremely large number of wires for signal processing, and when attached to the movable parts of the robot's fingers and hands. , less reliable.

Another possible method is to directly or indirectly press the diaphragm portion of a semiconductor pressure sensor using the piezoresistive effect. The method of using a semiconductor pressure sensor is an excellent method because it has excellent sensitivity and linearity, and the signal processing section can be integrated, but it is difficult to control the thickness of the diaphragm at a constant level. When arrayed, the variation becomes larger. On the other hand, if the film thickness is increased to avoid this, there is a drawback that the sensitivity becomes extremely poor.

Furthermore, when implementing a semiconductor tactile sensor, it is also necessary to draw out bonding wires to connect the chip and external circuits. In the case of a tactile sensor, since an external object touches the element surface, it is possible that the bonding wire may be cut. Therefore, it is necessary to take measures to prevent such accidents from occurring.

An object of the present invention is to provide a tactile sensor that eliminates the above-mentioned drawbacks.

[Means for solving problems]

The present invention is characterized by: a beam supported at both ends consisting of a portion of the silicon substrate between first and second through holes formed in the silicon substrate; and a support portion consisting of a portion of the silicon substrate supporting both ends of the beam. , a diffusion layer resistor formed near the both ends of the beam, and a diffusion layer resistance formed near the both ends of the support part forming a bridge circuit together with the diffusion layer resistance formed on the beam; A tactile sensor constitutes a semiconductor pressure sensor including a third through hole formed in a beam made of a portion of a silicon substrate, and a round ball placed on the third through hole.

〔Example〕

Next, embodiments of the present invention will be described using the drawings.

1A to 1E are a plan view and a cross-sectional view for explaining the manufacturing method of the first embodiment of the present invention,
Figure 1a is a plan view of the tactile sensor in an intermediate process, Figure 1b is a sectional view taken along line A-A', Figure 1c is a sectional view of the tactile sensor after beam formation, and Figure 1d is after the final process. The top view of the tactile sensor in Figure 1e is its B.
-B' sectional view.

First, as shown in FIGS. 1a and 1b, the crystal plane 11
By diffusing boron into the n-type silicon substrate 10 of
Diffusion layer resistance 11, 12, 1 with a length of 10 μm and a length of 100 μm
3 and 14 are formed to serve as resistors for a bridge circuit. Then, the surface is covered with an oxide film 15, and the oxide film 1
Two parallel windows 1 separated by selectively removing 5
6, 16' and a rectangular window 17 is opened therebetween.
The windows 16 and 16' have a width of 500 μm and a length of 1.5 mm, and the window 17 has a side of 350 μm.

Next, as shown in FIG. 1c, using the oxide film 15 as a mask, the silicon substrate 10 is etched with a 90° C. hydrazine solution to form a through hole 1 that penetrates to the bottom surface.
Open 8, 18' and 19.

In this embodiment, since the silicon substrate 10 with the (110) plane orientation is etched with hydrazine, which is an anisotropic etching solution, the through holes 18, 18',
The pattern accuracy of the oxide film 19 is determined by the accuracy of the mask of the oxide film 15, that is, the windows 16, 16', 17, and is vertically etched away. As a result, a beam 20 supported at both ends is formed.

Next, as shown in FIGS. 1d and 1e, aluminum wiring 21 is formed and its surface is covered with a protective oxide film 15'. The aluminum wiring 21 has four resistors 11
14 are connected in series and in a ring, and the four resistors form a bridge circuit. One set of diagonal points are used as input terminals, and the other set of diagonal points are used as output terminals.

Next, a round ball, which is the most important part of the invention, is installed in the through hole 19. 0.5mm diameter as a round sphere
Using the saphire sphere 22, this saphire sphere 2
2 is placed on the through hole 19, and the entire surface is covered with silicone rubber 23 by a potting method.

FIGS. 2a and 2b are a plan view and a sectional view taken along the line C-C' of the first example of the pedestal on which the tactile sensor shown in FIGS. 1d and 1e is mounted.

The pedestal 25 has an opening 26 in the center, and this opening 2
6 is the through hole 1 of the tactile sensor shown in Fig. 1 d and e.
A tactile sensor is attached to the surface of the pedestal so that 8, 18' and the beam 20 are located.

FIG. 3 is a characteristic diagram showing the relationship between applied load and electrical output in the first embodiment.

The horizontal axis shows the load applied to the beam 20, and the vertical axis shows the output voltage at both ends of the bridge. There is a very good linear relationship between the load and the output voltage V, and the reproducibility is also good.

Figures 4a and 4b are plan views of the second example of the pedestal on which the tactile sensor shown in Figures 1d and e are mounted, and D-
It is a sectional view D′.

The pedestal 40 has a recess 41, and in this recess 41,
Through holes 18, 1 of the tactile sensor shown in FIGS. 1d and 1e.
8' and the beam 20 are attached.
Since this pedestal 40 has a bottom surface in the recess 41, even if a load exceeding the allowable value is applied to the beam 20, the center part of the beam 20 will come into contact with the bottom of the recess 41 and stop, so that the beam will not deflect more than a certain amount. This can prevent damage to the beams.

FIG. 5 is a sectional view of a second embodiment of the invention.

In this embodiment, the back surface of the beam 20 is slightly etched so that the back surface 52 of the beam 20 is slightly higher than the back surface 51 of the silicon substrate 10. With this shape, a flat plate pedestal can be used, and even if a force exceeding an allowable value is applied, the beam 20 stops in contact with the flat plate pedestal, so the beam 20 can be prevented from being destroyed.

In the above two examples, the dimensions of the beam are 500μm wide,
The length is 1.5mm, and the width is 10μm and the length is 100μm on top of this beam.
Although a diffusion layer resistor of 200 mm was fabricated, the dimensions are not limited to this. Further, although sapphire spheres were used as the protrusions, the material and forming method are not limited thereto either.

[Effect of idea]

As explained in detail above, the present invention is configured so that the load is concentrated on the ball provided at the center of the beam, and the ball is higher than the substrate surface, so even if an object touches it, the bonding line remains intact. This has the effect that there is no breakage accident, the manufacturing process is greatly simplified compared to the conventional method, and a tactile sensor with good precision and less failure can be obtained.

[Brief explanation of the drawing]

1A to 1E are a plan view and a cross-sectional view for explaining the manufacturing method of the first embodiment of the present invention,
Figure 1a is a plan view of the tactile sensor in an intermediate process, Figure 1b is a sectional view taken along line A-A', Figure 1c is a sectional view of the tactile sensor after beam formation, and Figure 1d is after the final process. The top view of the tactile sensor in Figure 1e is its B.
-B' sectional view, Figures 2a and b are a plan view and sectional view of the first example of the pedestal on which the tactile sensor shown in Figures 1c and d are mounted, and Figure 3 is the application of the first embodiment. Characteristic diagram showing the relationship between load and electrical output, Figure 4 a, b
1c and d are a plan view and a sectional view of a second example of the pedestal on which the tactile sensor is mounted, and FIG. 5 is a sectional view of the second embodiment of the present invention. 10... Silicon substrate, 11, 12, 13, 1
4... Diffusion layer resistance, 15... Oxide film, 15'...
Protective oxide film, 16, 16', 17...window, 18,
18', 19...through hole, 21...aluminum wiring, 22...sapphire bulb, 23...silicon rubber, 25...pedestal, 26...opening, 40...pedestal, 41...recess, 51... ...Back side of the board, 52...
...The back side of the beam.

Claims (1)

[Claims] 1 a beam supported at both ends consisting of a portion of the silicon substrate between the first and second through holes formed in the silicon substrate; a support portion consisting of a portion of the silicon substrate supporting both ends of the beam; Diffused layer resistors formed near both ends of the supporting portion, which constitute a bridge circuit together with the diffused layer resistors formed on the beam, and a portion of the silicon substrate What is claimed is: 1. A tactile sensor comprising a semiconductor pressure sensor including a third through hole formed in a beam, and a round ball placed on the third through hole.