JPS62128568A - pressure sensitive transistor - Google Patents

Abstract

PURPOSE:To provide a pressure sensing transistor which has a high sensitivity and good reproducibility and utilizes an anisotropic stress effect by a method wherein a recessed part is formed in one of the surface of a semiconductor substrate and an emitter-base junction is formed in parallel to the recessed part surface and a pressure unit which touches the surface of the substrate except the recessed part is provided. CONSTITUTION:When a pressure unit 5 is contacted with the top surface of a substrate 1 in which a P-type base layer 3 and an N-type emitter layer 4 are formed in parallel to the surface of a groove 2 and a pressure is applied to the direction given by an arrow 6, in addition to a stress component vertical to the substrate surface, stress components vertical to both sides of the junction planes are induced near the bottom 7 of a V-shape emitter-base junction and the stress applied to this part of the emitter-base junction becomes substantially larger than the stress applied to the other parts so that a large variation in a collector current induced by an anisotropic stress effect can be obtained.

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

The present invention relates to a pressure-sensitive transistor that utilizes the fact that collector current decreases when stress is applied to the emitter-base junction.

[Prior art and its problems]

Pressure-sensitive transistors include those that apply a uniform force to the surface of the transistor chip that has an emitter-base junction parallel to the surface by using the -axial stress effect, and those that apply a uniform force to the surface of the transistor chip that has an emitter-base junction parallel to the surface, and those that apply a uniform force to the surface of the transistor chip that uses the anisotropic stress effect. Some use pressure needles to apply concentrated stress to one point on the surface. However, the 3-voltage transistor that uses the axial stress effect has the disadvantage of low sensitivity, while the one that uses the anisotropic stress effect has high sensitivity, but it is difficult to determine whether the pressure point is on the junction or not. Sensitivity varies depending on the method, and reproducibility is low.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned drawbacks and provide a pressure-sensitive transistor with high sensitivity and excellent reproducibility, which utilizes the anisotropic stress effect while applying a uniform force to the surface of the transistor chip. do.

[Key points of the invention]

According to the present invention, a semiconductor substrate of a pressure-sensitive transistor has a recess on one side, an emitter-base junction is formed parallel to the recessed surface, and a pressure body is provided in contact with the one surface of the substrate except for the recessed part. By providing this, the above object is achieved because a concentrated stress is applied to the bottom of the depression and a change in the collector current occurs due to the anisotropic stress effect.

[Embodiments of the invention]

1 to 4 show several embodiments of the present invention, and common parts in each figure are given the same reference numerals. Figure 1 shows an example in which a V-shaped groove 2 is formed in a semiconductor substrate 1 of a transistor chip.
A shaped emitter layer 4 is formed parallel to the plane of the groove 2. When the pressurizing body 5 is brought into contact with the upper surface of this W+ffl and pressure is applied as shown by the arrow 6, there will be a A vertical stress is generated and the emitter in this area
The stress applied to the base junction becomes significantly larger than that to other parts, causing a large change in collector current due to anisotropic stress effects. In the embodiment shown in FIG. 2, a conical hole 68 is drilled in the substrate l, and an emitter-base junction is formed parallel to the inner surface of the hole, as shown in FIG. 2 fbl. In this case, stress is concentrated at the conical top of the hole 8, so a strong stress effect occurs at that one point, but since the area ratio of that part to the entire emitter-base junction is small, the overall sensitivity is as shown in Figure 1. smaller than the case. However, the strength of the chip is greater than the embodiment of FIG. In the embodiment according to FIGS. 3 and 4, the groove 2 or hole 8 has a U-shaped cross section. In this case, the stress concentration effect will be weaker and the sensitivity will be correspondingly lower than in the embodiments of FIGS. 1 and 2 with V-shaped cross sections, but the strength of the chip will be higher than with the corresponding V-shaped cross sections. Effects of the Invention The present invention forms a recess from one side of a semiconductor substrate and makes the emitter-base junction parallel to the inner surface of the recess, thereby concentrating stress on the bottom of the junction and producing a highly sensitive pressure-sensitive transistor. get. In addition, like a pressure-sensitive transistor that utilizes the uniaxial stress effect of a semiconductor substrate, even if pressure is applied uniformly to one surface, stress is generated at a fixed position of the emitter-base junction, resulting in good reproducibility and Since there is no need to set up a pressure needle, there is no damage to the substrate surface, which is extremely effective in improving the characteristics of pressure-sensitive transistors.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention, where fat is a perspective view of a transistor chip, (bl is a sectional view when pressurized, FIG. 2 is another embodiment, and (al is a perspective view of a transistor chip). , (b) are cross-sectional views, and FIGS. 3 and 4 are perspective views of transistor chips of further different embodiments. l: semiconductor substrate; 2: conductor; 3: base layer; 4: emitter layer; 5: Pressure body, 8: hole. Figure 1 (b) 8 shaku 8~- Figure 2

Claims (1)

[Claims] 1) A pressure sensitive device characterized in that a semiconductor substrate has a recess on one side, an emitter-base junction is formed parallel to the recessed surface, and a pressure body is provided that contacts the one surface of the substrate except for the recessed part. transistor.