JPH0446462B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a ring-shaped pressure-sensitive structure made of a semiconductor of one conductivity type, and a plurality of resistive elements of opposite conductivity type on a surface that forms an angle with the pressure receiving surface of the ring-shaped pressure-sensitive structure. When a pressure surface is applied to a bridge circuit consisting of a resistor element, which is fixed to a support on the side facing the pressure-receiving surface, the force is applied in three directions by the output voltage generated by the resistance change of the resistor element. The present invention relates to a method for manufacturing a small pressure sensor suitable for detecting a component, particularly for detecting a planar distribution of a load.

[Prior art and its problems]

It is desirable for a robot hand that handles various objects to grasp the object with an appropriate force depending on the object being handled. For this purpose, it is necessary to accurately detect the three-directional components of the grip force and to know its planar distribution. In order to meet this demand, a small pressure sensor as shown in FIG. 1 has been proposed. In Figure 1,
Made of N-type silicon single crystal, for example, outer diameter 3 mm,
When a plurality of P-type resistance element regions 4 are formed on a surface 3 perpendicular to the pressure-receiving surface 2 of a ring-shaped pressure-sensitive structure 1 with an inner diameter of 1 mm and a thickness of 0.3 mm, and a force is applied to the pressure-receiving surface 2,
Based on the change in the resistance value of this resistance element, the Fx, Fy, and Fz3 components of the applied force are detected from the output voltage of the bridge circuit made up of the resistance element. In order to maintain a stable posture when a pressure-receiving surface force is applied, the pressure-sensitive structure 1 must be fixed on a support with a base surface 5 facing the pressure-receiving surface 2 to receive the force applied to the pressure-receiving surface. Must be. In order to detect the planar distribution of force, a plurality of pressure sensitive structures are arranged closely together on a support to form an array.

Such a pressure-sensitive structure 1 is manufactured by forming a pattern using an integrated circuit manufacturing technique from a silicon plate having a thickness of 0.5 mm, forming a resistance element region by a diffusion process, and performing wiring, etc. In this case, it is desirable for mass production to form a large number of pressure-sensitive structures on one silicon plate and separate them.

[Purpose of the invention]

In response to such demands, the present invention aims to provide a method for manufacturing a pressure sensor that is advantageous for mass production and does not leave any negative impact on the characteristics.

[Key points of the invention]

According to the present invention, when manufacturing a plurality of pressure-sensitive structures from one semiconductor board, after forming the resistive element area and wiring, masks are provided on both surfaces of the semiconductor board to cover each ring part. A part of the thickness is removed by etching, and then a mask is provided on both surfaces of the semiconductor board to cover the ring part and the connection part between the ring parts, and the parts other than the hole in the center of the ring and the connection part between each pressure-sensitive structure part are provided. The above objective is achieved by etching away the pressure-sensitive components and finally cutting through the center of the connection to separate the pressure-sensitive components.

[Embodiments of the invention]

2A to 2D sequentially show the steps of an embodiment of the present invention. For example, a resistance element region 7, which is a P-type diffusion region, and wiring (not shown) are formed on an N-type silicon single crystal plate 6 with a thickness of 300 μm. has been done. Although only a portion of one pressure-sensitive structure is not shown in the figure,
A large number of such parts are formed on one silicon plate 6 at the same time. On this silicon plate 6, as shown in FIG.
An etching mask 8 is applied as shown in FIG. This mask 8 can be created by photolithography using a photomask having a pattern of black portions 21 and transparent portions 22 as shown in FIG. 3a. Next, as shown in FIG. 2b, a portion of the thickness of the silicon plate 6 is etched. The etching depth should be approximately 50 μm on one side. The ring portion 9 of each pressure-sensitive structure remains the same thickness as the silicon plate 6. Subsequently, the silicon plate 6 is covered with another mask 10 using the photomask shown in FIG. 3B (FIG. 2C).
This mask 10 covers not only the ring part 9 but also the part 11 connecting the ring parts. Subsequently, etching is carried out again, and as shown in FIG. 2d, the hole 12 in the center of the ring part passes through, and the portion between each ring part 9 is removed except for the connecting part 11. If the center of this thinned connecting portion 11 is separated by dicing, a structure having protrusions 11 on four sides as shown in FIG. 4 is obtained. If one of the protrusions 11 of this structure is removed to form a pressure receiving surface, and the protrusion 11 on the opposite side is inserted into the recess of the support plate, for example, the pressure-sensitive structure can be attached to the support plate. A pressure sensor is created that is tightly coupled to the

〔Effect of the invention〕

The present invention removes by etching the hole in the center of a ring of a plurality of pressure-sensitive structures formed on one semiconductor board and the unnecessary parts between the structures, and leaves a connection part between the structure parts, and at the connection part. Each pressure sensitive structure is separated by cutting. This manufacturing method has the following advantages.

(1) Since the ring-shaped pressure-sensitive structure part connected by the connecting body is formed from a single semiconductor board, there is no need to drill holes in the separated state, making it suitable for mass production.

(2) Since the semiconductor board is processed by etching other than cutting the connecting parts, no strained layer remains that would affect the sensitivity of the sensor.

(3) Precise processing machines are not required as the fine holes in the center of the ring are not machined, and conventional dicing machines can be used to cut the connecting parts because the connecting parts are thin, reducing equipment costs. be done. That is, the present invention allows a highly reliable, compact pressure sensor to be produced at a low cost, so that it can be extremely effectively used in the robotics industry and other fields.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the basic structure of a pressure-sensitive structure of a pressure sensor, Fig. 2 is a cross-sectional view of main parts sequentially showing the steps of an embodiment of the present invention, and Fig. 3 is the same as shown in Fig. 2. FIG. 4 is a plan view showing a photomask for photoetching used in the process, and a perspective view showing one of the pressure-sensitive structures after separation. 6... Silicon single crystal plate, 7... Resistance element region, 8, 10... Etching mask, 9... Ring portion, 11... Connecting portion, 12... Hole.

Claims (1)

[Claims] 1. A ring-shaped pressure-sensitive structure made of a semiconductor of one conductivity type is provided with a plurality of resistive element regions of opposite conductivity type on a surface forming an angle with the pressure-receiving surface, and is fixed to a support on the side facing the pressure-receiving surface, A method for manufacturing a sensor that detects three-directional components of an applied force from an output voltage caused by a change in resistance of a resistance element when a pressure-receiving surface is applied to a bridge circuit composed of a resistance element, the method comprising: After forming the resistance element regions and wiring of a plurality of pressure-sensitive structures on the semiconductor board, a mask covering each ring portion is provided on both surfaces of the semiconductor board, a part of the thickness of the semiconductor board is removed by etching, and then each ring is etched. A mask covering the ring part and the connection part between each ring part is provided on both surfaces of the semiconductor board, and the parts other than the hole in the center of the ring and the connection part between each pressure-sensitive structure part are removed by etching, and finally the connection part is removed. A method of manufacturing a pressure sensor, comprising: cutting the center of the pressure sensor to separate each pressure-sensitive structure.