JPH0562829B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device, and particularly to a semiconductor device used as a tactile sensor 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, robots currently in practical use are able to lift or carry objects of a certain shape, size, or weight, or perform tasks such as processing or assembly according to a certain program. It can only be done by holding it.

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 receive information from the sensors for control. 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]

There are various tactile sensors that have been reported so far, such as those using pressure-sensitive conductive rubber, those using microswitches, and those using carbon fiber (Automation Technology, Vol. 14, No. 6,
37-42 and 61-70). These tactile sensors have the disadvantage that they are too large, have poor linearity and 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 it is difficult to attach the sensors to the movable parts of the robot's fingers or hands. In this case, reliability is poor.

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 increases. On the other hand, if the film thickness is increased in order to avoid this, there is a drawback that the sensitivity becomes extremely poor.

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

[Means for solving problems]

The present invention is characterized by a cantilever beam formed from a portion of the semiconductor substrate, which is provided by forming a U-shaped through hole in the semiconductor substrate; at least one diffused layer resistor provided in the supporting part of the beam and on the beam to form a bridge circuit or a half bridge circuit; A semiconductor device for a tactile sensor includes a projection provided on a beam, and is attached to a pedestal having a recess so that the through hole and the beam are located on the recess of the pedestal.

[Effect]

In the semiconductor device of the present invention, a protrusion is formed near the free end of a cantilever provided on a semiconductor substrate, and force applied to the element surface is converted into deformation of the beam via the protrusion. This is a semiconductor tactile sensor based on the principle of the so-called piezoresistance effect, which converts electrically as a resistance change of a resistance element formed near the fixed end of the sensor.

〔Example〕

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

1A to 1D are a plan view and a cross-sectional view for explaining the manufacturing method of the first embodiment of the present invention,
FIG. 1a is a plan view of the semiconductor device in an intermediate process, FIG. 1b is a sectional view taken along line A-A', FIG.
is a sectional view taken along line B-B'.

First, as shown in FIGS. 1a and 1b, a diffusion layer resistor 11 with a width of 10 μm and a length of 100 μm,
12 is formed as a resistor for a half bridge circuit. Then, the surface is covered with an oxide film 14. Next, the oxide film 14 is selectively removed in a U-shape to open a window 15.

Next, as shown in FIG. 1c and d, the oxide film 14
Using as a mask, the silicon substrate 10 is etched with a 90° C. hydrazine solution to form a through hole 16 that penetrates to the bottom surface.

In this embodiment, since the silicon substrate 10 with the (110) plane orientation is etched with hydrazine, which is an anisotropic etching solution, the pattern accuracy of the through hole 16 is determined by the accuracy of the mask of the oxide film 14, that is, the accuracy of the window 15. determined and etched away vertically. This forms a cantilever beam 17. Next, aluminum interconnections 18, 18' are formed, and a protective oxide film is formed on the surface (not shown). The aluminum wiring 18 connects two resistors 11 and 12 in series,
The aluminum wiring 18' is connected to both ends of two resistors connected in series. This constitutes a half bridge circuit. In other words, half the circuit of a normal bridge circuit is constructed. A voltage is applied to both ends of the resistor through the aluminum wiring 18', and the midpoint potential is measured as an output value at the aluminum wiring 18.

Next, the protrusion 1 which is the most important part of the present invention
form 9. This protrusion 19 may be pasted with glass or silicone if the beam 17 has a size of 1 mm or more; however, as in this embodiment, the beam 17 is
For small dimensions such as 100 μm width and 500 μm length, film resist is used. In this example, a film resist was applied to a thickness of 100 μm and exposed to light to form protrusions 19.

FIGS. 2a and 2b are a plan view and a sectional view taken along the line C-C' of a pedestal related to the present invention on which the semiconductor device shown in FIGS. 1c and d can be mounted.

The pedestal 20 has an opening 21 in the center, and this opening 2
1 is a through hole 16 of a semiconductor device shown in FIGS. 1c and d.
The semiconductor device is attached to the surface of the pedestal so that the beams 17 and 17 are positioned. After pasting, the surface is covered with silicone rubber to protect it.

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 17, and the vertical axis shows the amount of potential change at the midpoint of the half bridge. There is a very good linear relationship between the load and the electrical output V.
Reproducibility is also good.

FIGS. 4a and 4b are plan views of examples of the pedestal of the present invention mounted on the semiconductor devices shown in FIGS. 1c and d, and D-
It is a sectional view D′.

The pedestal 40 has a recess 41 and is attached so that the through hole 16 and beam 17 of the semiconductor device shown in FIGS. 1c and d are located in the recess 41. 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 17, the tip of the beam 17 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 the beam from breaking.

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

In this embodiment, the back surface of the beam 17 is slightly etched so that the back surface 52 of the beam 17 is slightly higher than the back surface 51 of the silicon substrate 10. With this shape, a flat plate pedestal can also be used, and even in this case, even if a force exceeding the allowable value is applied, the beam 17 will stop in contact with the flat plate pedestal, so the beam 17 can be prevented from being destroyed. It will be done.

In the above two examples, the dimensions of the beam are 100μm wide,
A beam with a width of 10 μm and a length of 500 μm is placed on top of this beam.
Although a 100 μm resistor was fabricated, the size is not limited to this. Furthermore, although a film resist is used as the protrusion, the material and formation method are not limited thereto either. In addition, the output voltage is determined by two resistors 11,
12, we formed four resistors and connected them to form a normal bridge circuit, with one set of diagonal points connected to input terminals and the other set of diagonal points connected to input terminals. It is also possible to configure a bridge circuit having the output terminal as the output terminal. With this bridge circuit, a correlation similar to that shown in FIG. 3 can be obtained.

〔Effect of the invention〕

As explained in detail above, the present invention has a structure in which the load is concentrated on the protrusion provided near the free end of the beam, so the manufacturing process is greatly simplified compared to the conventional method, and the accuracy is high. This has the effect that a semiconductor device for a tactile sensor can be obtained.

[Brief explanation of the drawing]

1A to 1D are a plan view and a cross-sectional view for explaining the manufacturing method of the first embodiment of the present invention,
FIG. 1a is a plan view of the semiconductor device in an intermediate process, FIG. 1b is a sectional view taken along line A-A', and FIG.
B' sectional view, FIGS. 2a and 2b are a plan view and a sectional view of a pedestal related to the present invention that can mount the semiconductor device shown in FIGS. 1c and d, and FIG. A characteristic diagram showing the relationship between the applied load and the electrical output in the example of FIG. , FIG. 5 is a cross-sectional view of a second embodiment of the invention. 10...Silicon substrate, 11, 12...Diffused layer resistance, 14...Oxide film, 15...Window, 16...Through hole, 17...Beam, 18...Aluminum wiring,
19...Protrusion, 20...Pedestal, 21...Opening hole,
40... Pedestal, 41... Recessed portion, 51... Back side of substrate, 52... Back side of beam.

Claims (1)

[Claims] 1. A cantilever beam consisting of a portion of the semiconductor substrate provided by forming a U-shaped through hole in the semiconductor substrate, and at least one cantilever beam provided on the beam and in a portion close to the support portion of the beam. a diffused layer resistor that is provided near the free end of the beam and that forms a bridge circuit or a half-bridge circuit, and a diffused layer resistor that is provided in the support portion of the beam and is provided on the beam; What is claimed is: 1. A semiconductor device for a tactile sensor, wherein the semiconductor device is attached to a pedestal having a recess so that the through hole and the beam are positioned above the recess of the pedestal.