JPH09257612A - Force sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a minute high sensible sensor for a micro-manipulator by integrally forming a grip part, a detection part, a base part and a wiring part on the semiconductor substrate on a thin board. SOLUTION: A force sensor comprises a base part 1, a rear high rigidity region 2, a sensing region 3, a front high rigidity region 4 and a grip part 5 and is formed of silicon. The region 3 detects stress applied to the grip part 5, and the base part supports the region 3 and the grip part 5. Pieces of wiring 9-15 are connected to the region 3, and extend up to the base part 1. These can be integrally formed, no process of gage sticking or the like is needed and minuteness is made easy by lithography technique because semiconductor production technique can be applied. Thus, a minute sensor suitable for a micro- manipulator used for the hand ring of a minute object can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a force sensor, and more particularly to a force sensor used for a micromanipulator used for handling micro parts, cells and the like.

[0002]

2. Description of the Related Art With the progress of micromachine technology in recent years, a micromanipulator capable of highly precise position control for the purpose of handling minute parts and manipulating cells has been developed. As such a micromanipulator, for example, the IEEE International Conference on
The robots disclosed in Robot and Automation, 1995, pp1674-1679 can be mentioned. See Figure 38 for this.
Shown in The pair of thin glass needles 141 are driven by the piezoelectric element 142. By precisely controlling the displacement of the piezoelectric element 142, delicate handling such as cell manipulation is performed using the glass needle 141 like chopsticks.

In a manipulation system using such a micromanipulator, it is particularly desirable to construct a control system that detects and feeds back minute stress when handling minute parts or cells having weak mechanical strength. In industrial robot manipulators that handle relatively large-sized components and the like, strain gauges are generally used for such force feedback sensors. In particular, a semiconductor strain gauge using the piezoresistive effect has high measurement sensitivity and is suitable for measuring minute stress. For mounting such a strain sensor, it is common to fix a gauge to an elastic member by a method such as adhesion, as disclosed in, for example, Japanese Patent Application Laid-Open No. 7-311107.

[0004]

However, when this method is applied to a micromanipulator, it is necessary to manufacture a microstructure having extremely small rigidity and fix a highly sensitive strain sensor to the microstructure. Therefore, stable and highly accurate stress measurement is difficult because of the problem of assembling.

The present invention has been made in consideration of the above circumstances, and an object thereof is to provide a highly sensitive and minute force sensor applicable to a micromanipulator.

[0006]

[Means for Solving the Problems]

Claim 1: A gripping part, a detecting part for detecting a stress applied to the gripping part, a base part for supporting the gripping part and the detecting part, and a detector connected to the detecting part and extending to the base part. A force sensor having a wiring portion, wherein the grip portion, the detection portion, the base portion and the wiring portion are integrally formed on a thin semiconductor substrate.

(Structure) All the embodiments are applicable. For example, in the first embodiment, the grip portion 5 in FIGS. 1 and 2, the sensing region 3 serving as a detection portion that detects the stress applied thereto, the base portion 1 that supports the grip portion and the detection portion, and the detection portion are connected. Wirings 9 to 11 provided to extend to the base
The wiring part is made up of, and the grip part, the detection part, and the wiring part are integrally formed.

(Operation / Effect) Since the gripping portion, the detecting portion and the base portion are integrally formed and the wiring portion for transmitting the sensing signal of the detecting portion to the base portion is integrally formed, the assembling process becomes unnecessary, A micro force sensor suitable for a micro manipulator used for handling a micro object can be obtained.

According to a second aspect of the present invention, a thin conductive semiconductor substrate having a surface of one conductivity type, a detection portion formed on the semiconductor substrate for detecting stress applied to the semiconductor substrate, and formed on the semiconductor substrate, In a force sensor having a base portion that supports a detection portion and a wiring portion that is connected to the detection portion and that is formed on the semiconductor substrate so as to extend to the base portion, the detection portions are orthogonal to each other. A force sensor comprising at least three detection means provided at different portions on the semiconductor substrate so as to detect stress in three directions.

(Structure) Embodiments 3, 4, and 5 are applicable.

(Operation / Effect) A micro force sensor capable of separately measuring the directional component of stress is obtained by having three detecting means which generate different output signals depending on the direction of applied stress. To be

A third aspect of the present invention is a thin-film semiconductor substrate having one conductivity type surface, and a flexible portion formed on the semiconductor substrate.
Two detecting portions formed on the semiconductor substrate with the flexible portion interposed therebetween to detect stress applied to the semiconductor substrate; and two detecting portions formed on the semiconductor substrate with the flexible portion interposed therebetween, In a force sensor including two bases that support a portion and a wiring portion that is formed on the semiconductor substrate and the flexible portion and electrically connects the two detection portions, the flexible portion is A force sensor in which the two detectors are arranged to face each other by being curved.

(Structure) Embodiment 5 corresponds.

(Operation / Effect) Multi-axial stress sensing is made possible by the strain sensing elements formed in the thin plate-shaped semiconductor regions serving as the detecting portions arranged opposite to each other, and the wiring of these sensing elements is flexible. The electrodes can be arranged on one surface because they are connected by the flexible thin film wiring layer, which is a flexible portion.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIGS. 1, 2 and 3
Reference is made to (A) and (B). Here, FIG. 1 is a plan view, FIG. 2 is a cross-sectional view taken along line XX of FIG. 1, and FIG. 3A is a plan view of a sensing element which is one configuration of the force sensor of FIG.
FIG. 3B is a sectional view taken along the line XX of FIG. The force sensor according to the first embodiment is applied to a micromanipulator and is used by replacing it with the glass needle 141 in FIG. The force sensor includes a base 1, a rear high-rigidity region 2, a sensing region 3, a front high-rigidity region 4, and a grip 5. Both are made of silicon, and the surface portion 2a of the rear high rigidity region 2 and the sensing region 3
The conductivity type of the surface portion 3a, the surface portion 4a of the front high rigidity region 4, and the surface portion 5a of the grip portion 5 are all N type.

A strain sensing element 6 is formed on the surface portion (N-type region) 3a, and a temperature compensation element 7 is formed on the region 2a. These elements 6 and 7 are PNP-type bipolar transistors of the same form. An insulating film 8 made of a silicon nitride film is formed on the surface of the silicon, and a contact hole (not shown) is formed in the insulating film 8.
Is open. The emitter wiring 9 and the base wiring 1 of the sensing element 6 connected through this contact hole
0, a collector wiring 11, and a substrate wiring 12 extend to the base portion 1 and are connected to each other through a contact hole (not shown) that also opens in the insulating film 8, and an emitter wiring 13 and a base wiring of the temperature compensation element 7. 14, collector wiring 15, and substrate wiring 12 (common to the sensing element) extend to the base.

Each of these wirings has an electrode pad on the base 1. A polyimide film 16 serving as an upper insulating film is formed on the wiring, and an opening 17 is formed in the pad portion of the polyimide film. The thickness of each region of such a force sensor is optimized depending on the range of gripping force to be detected, the required accuracy, the ease of manufacturing, etc., but one example is the rear high rigidity region 2 and the front region. 4 in high rigidity region 4
0 μm, sensing area 3 and gripping portion 5 are 10 μm
About 300 μm at the base 1.

Next, the form of the sensing element 6 will be described in detail with reference to FIG.

A P-type diffusion layer 18 serving as a collector region is formed on the surface of the N-type region 3a of the sensing region 3, an N-type diffusion layer 19 serving as a base region is formed therein, and an emitter region and an emitter region are formed therein. The P-type high-concentration diffusion layer 20 is formed. The impurity concentration of each diffusion layer is optimized depending on the detection sensitivity required as described later. As an example, the P-type high-concentration diffusion layer 20 serving as the emitter is 1 × 1.
0 ²⁰ / cm ³ , 3 × 10 ¹⁸ in N-type diffusion layer 19 serving as a base
/ Cm ³ , 3 × 10 ¹⁷ / in the P-type diffusion layer 18 serving as a collector
cm ³ . Further, in order to obtain ohmic contact in the region of the contact hole 24 of each wiring, the high-concentration N-type diffusion layer 21 with respect to the base region, the high-concentration P-type diffusion layer 22 with respect to the collector region, and the substrate region. High concentration N type diffusion layer
23 are formed respectively. Since the temperature compensating element 7 has the same form, the description thereof will be omitted.

Each wire of the sensing element 6 and the temperature compensating element 7 is connected to an external detection circuit by a lead wire connected to the opening 17 of the electrode pad at the base. When stress is applied to the grip portion 5, a slight strain is also generated on the surface of the sensing region 3, and the lattice constant of silicon in this region changes.
This affects the band structure of the junction, changes the base current, and greatly modulates the collector current. Even in the rear high-rigidity region 2, surface strain occurs due to the application of stress to the grip portion 5, but the amount is very small compared to the sensing region because the thickness is significantly different. Therefore, the amount of distortion in the temperature-compensated sensing region can be obtained by comparing the output modulations of the sensing element 6 and the temperature compensation element 7. As shown in FIG. 1, if the width of the rear high-rigidity region 2 in which the temperature compensating element 7 is formed is larger than that of the sensing region 3, the influence of distortion of the temperature compensating element 7 can be further reduced, which is particularly preferable. . Since the relationship between the stress of the grip portion 5 and the strain amount of the sensing region 3 is determined by the entire structure including the integrated grip portion, the stress of the grip portion 5 can be calculated by measuring the strain amount. .

In the first embodiment, since the grip portion 5 and the sensing area 3 can be integrally formed, and the area for detecting the stress (sensing portion 3) is integrated with the sensing element 6, the conventional structure can be realized. Since it does not require an assembly process such as attaching a strain gauge, it is suitable for miniaturization. In addition, since semiconductor manufacturing technology can be applied to manufacturing, the sensing element 6 and the grip portion 5 themselves can be formed to be extremely small by photolithography technology.

Further, by using the bipolar transistor as the sensing element 6, the current modulation due to the change of the band structure due to the strain can be amplified, so that the sensitivity is significantly higher than that of the conventional semiconductor strain gauge utilizing the piezoresistive effect. Can be converted. Furthermore, since the temperature compensating element 7 can be integrally and closely arranged, the accuracy of temperature compensation can be improved, and as a result, the accuracy of stress measurement can be improved. As described above, according to the first embodiment, it is possible to obtain a force sensor having a small size, high accuracy, and an integrated sensing function and gripping function.

Next, a method of manufacturing the force sensor of the first embodiment will be described with reference to FIGS. In addition,
Regarding the notation method of the diffusion layer, the solid line is used when a PN junction is formed with respect to the region (substrate or other diffusion layer) where the diffusion layer is formed, and the broken line is the region where the diffusion layer is formed ( It is used when a diffusion layer of the same conductivity type as that of the substrate or another diffusion layer) is formed, that is, when a PN junction is not formed although there is a difference in concentration. This notation is the same after the description of the second embodiment.

In addition, in the numbering of the drawings, parts having the same form or function are classified by adding the alphabetical suffix with the same number. In this case, however, the alphabetical suffix is omitted. Indicates the subscript part of all alphabets of the number.
This notation is the same for the second and subsequent embodiments.

(1). First, as shown in FIG. 10, the plane orientation is <100>, the substrate concentration is 2 × 10 ¹⁴ / cm ³ , and the thickness is 3
A silicon nitride film is formed on the back surface of a P-type silicon substrate 31 having a thickness of 00 μm by CVD, and the silicon nitride film is patterned by a photolithography technique used in usual semiconductor manufacturing to obtain silicon nitride film patterns 32a and 32b. Here, the silicon nitride film pattern 32a corresponds to the base region of FIG. 1, and the silicon nitride film pattern 32b corresponds to the frame portion during electrochemical etching described later. Although only one force sensor with a grip is shown here, it is needless to say that a large number of force sensors with a grip can be formed on one silicon substrate because this force sensor with a grip is small. .

(2). Next, as shown in FIG. 11, deep N-type diffusion layers 33a and 33b and deep P-type diffusion layers 34a and 34b are formed on the surface of the silicon substrate 31. Here, the diffusion layer 33
Reference characters a, 33b, 34a, and 34b are respectively formed in regions corresponding to the rear high-rigidity region 2, the sensing region 3, the front high-rigidity region 4, and the grip 5 in FIG. However, the deep P-type diffusion layers 34a and 34b are formed wider than the regions finally formed as the sensing region and the grip portion. The impurity concentration of each of these diffusion layers is 1-2 × 1 on the surface.
It is about 0 ¹⁶ / cm ³ . The junction depth of the N-type diffusion layers 33a and 33b is about 25 μm, and the impurities of the P-type diffusion layer are also diffused to the same depth. The steps of forming these diffusion layers include
Photolithography, ion implantation and thermal diffusion used in normal semiconductor manufacturing are applied.

(3). Next, as shown in FIG. 12, an N-type diffusion layer 35 having a junction depth of 6 μm and a surface concentration of 3 to 6 × 10 ¹⁶ / cm ³ is formed. This is formed in a part of the rear high-rigidity region 2, a sensing region 3, a part of the front high-rigidity region 4, and a region corresponding to the grip 5. Next, FIG.
As shown in FIG. 3, the guard ring 36 including the sensing element 6, the temperature compensating element 7, and the high-concentration P-type diffusion layer is formed. Although details of the sensing element 6 and the temperature compensating element 7 are omitted here, as shown in FIG. 3, a P-type collector region formed in the N-type region (here, the N-type diffusion layer 35 corresponds). , An N-type base region, a high-concentration P-type emitter region, and a high-concentration diffusion layer formed in a portion corresponding to a contact region of a base-emitter wiring. Normal semiconductor manufacturing techniques can be applied to these as well. The guard ring 36 is formed in a region corresponding to the outer circumference of the final force sensor with a grip.
It is preferable that the diffusion layer serving as the guard ring 36 is formed at the same time as the emitter regions of the sensing element 6 and the temperature compensating element 7 from the viewpoint of simplifying the manufacturing process.

(4). Next, as shown in FIG.
After forming an insulating film 37 of a low stress silicon nitride film of 00 nm and forming a contact hole (not shown) at a predetermined position of the insulating film 37, the wirings 9, 10, 11, 12, 13, 14 shown in FIG. ， 15
To form Subsequently, as shown in FIG. 15, a polyimide film 38 is formed on the surface by spin coating, and the wiring 9,
Openings 17 are formed in the electrode pad portions of 10, 11, 12, 13, 14, and 15. Furthermore, as shown in FIG. 16, the silicon nitride film 32a on the back surface side is immersed by immersing it in a strong alkaline etchant while the front surface side is mechanically sealed and protected.
The silicon substrate in the area without 32b is etched from the back surface. At this time, a bias is applied using the N-type diffusion layers 33a, 33b, and 35 as anodes and a strong alkaline etchant as a cathode. This is done by applying a positive bias to the wiring 12. This etching is performed by N type diffusion layers 33a, 33b,
In the region where there is no 35, the silicon nitride film 37 proceeds until it is exposed on the back surface side, but in the region where the N-type diffusion layers 33a, 33b and 35 exist, the N-type diffusion layer 33 is formed by electrochemical etching.
a, 33b, 35 and PN of P-type substrate 31 or P-type diffusion layer 34
It stops near the end of the depletion layer on the P-type side of the junction.

In this etching, in the region where the P-type diffusion layer is present (corresponding to the sensing region 3 and the grip portion 5 in FIG. 1), the impurity concentration of the P-type region of the junction is high, so that the same bias is applied. The spread of the depletion layer to the P-type side is suppressed, and the thickness of the remaining P-type regions 3b and 5b is reduced. On the other hand, in the region where the P-type diffusion layer does not exist (corresponding to the rear high-rigidity region 2 and the front high-rigidity region 4 in FIG. 1), the same bias is applied because the P-type region near the junction has a low impurity concentration. Even in such a case, the depletion layer spreads largely to the P-type side, and the thickness of the remaining P-type regions 2b and 4b becomes large.

That is, it is desirable that the sensing region is thin in order to enhance the measurement sensitivity, and thick in the rear high rigidity region where the temperature compensating element is formed in order to reduce the influence of strain. Since the junction depth of the N-type diffusion layer 35 in 3 is small and the depletion layer can be prevented from expanding in this region during electrochemical etching, the overall thickness can be made very thin. On the other hand, the junction depth of the N-type diffusion layer 33a in the rear high-rigidity region 2 is large, and the depletion layer spreads at the time of electrochemical etching in this region is large. You can
Further, the lateral expansion of the depletion layer during electrochemical etching is suppressed by the guard ring 36, which is a high-concentration P-type region, so that in the lateral direction, the shape of the remaining portion is almost the same as that of the N-type diffusion layer. Corresponds to the joint. That is, the silicon in the region shown by the broken line in the top view of FIG. 16 remains.

(5). Next, as shown in FIG. 17, RIE (R) in the mixed gas atmosphere of CF ₄ and O ₂ from the back side is performed.
The silicon nitride film 37 in the region where the silicon is removed by eactive ion etching is removed, and the remaining silicon portion is cut out by the laser ablation of the polyimide film 38 along the shape shown by the broken line in FIG.
A force sensor with a grip as shown in is obtained.

According to the method of manufacturing the force sensor of the first embodiment, the thickness of the region left by electrochemical etching is set so that the junction depth of the N-type diffusion layer and the P-type region side when biasing the PN junction are applied. It is possible to control in a wide range by controlling the spread of the depletion layer at. The shape controllability of the method of leaving thin silicon by this electrochemical etching is defined by the controllability of the impurity concentration distribution and the potential distribution at the time of bias, but the controllability of ion implantation, photolithography and thermal diffusion is controlled by semiconductor manufacturing technology. It is used and has extremely high controllability. Therefore, as compared with the conventional machining, the microstructure can be manufactured with extremely reproducibility even in the size of about 10 μm. Moreover, since the force sensor with the grip portion itself is small, mass production is possible by batch processing, and the manufacturing cost can be reduced.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIGS. 4 (A) and 4 (B). Here, FIG.
FIG. 4A is a plan view of the force sensor according to the second embodiment, particularly a wiring region, and FIG. 4B is a cross-sectional view taken along line XX of FIG. In the second embodiment, the sensing element 6 and the temperature compensating element 7 of the first embodiment are replaced with PNP type bipolar transistors by piezoresistive elements.
The surface concentration is 3 × in the N-type region 3a on the surface of the sensing region.
P-type diffusion layer 41 with a junction depth of 10 ¹⁷ / cm ³ and 0.8 μm
Is formed, and high-concentration P-type diffusion layers 42 for making ohmic contact with the wiring are formed at both ends thereof. Further, an N-type high-concentration diffusion layer 43 is formed near the P-type diffusion layer 41.

The high-concentration diffusion layers 42 and 43 are formed in the N-type region 3
It is connected to the wirings 45, 46 and 47 through a contact hole 44 opened in the insulating film 8 of the silicon nitride film on the upper part of a.
The wirings 45, 46, 47 extend to the electrode pads at the base, as in the first embodiment. Sensing is performed by measuring the resistance value of the P-type diffusion layer 41 using the wirings 45 and 46. The wiring 47 is for stabilizing the potential of the N-type region 3a, and thereby suppresses the potential fluctuation of the substrate. Further, the wiring 47 is also used as an electrode for applying a bias during the electrochemical etching in the first embodiment. As in the case of the first embodiment, the same form as in FIG. 4 is applied to the temperature compensation element.

The force sensor of the second embodiment is a simple piezoresistive element, and is inferior to the first embodiment using the PNP type bipolar transistor in terms of sensitivity, but it requires a small number of wirings. Since the external detection circuit can be simplified because the manufacturing process is simple and the output is linear, it is more preferable in applications where a very high detection sensitivity is not required. In the second embodiment, the piezoresistive element of diffusion resistance is used for the force sensor, but PN
A method using a junction diode and a method using an NPN bipolar transistor are also possible. The optimum form of the force sensor is selected according to the required measurement sensitivity and measurement range of stress.

(Embodiment 3) A force sensor according to Embodiment 3 of the present invention will be described with reference to FIGS. 5 (A) and 5 (B).
Here, FIG. 5A is a plan view of the force sensor according to the third embodiment, particularly a wiring region, and FIG. 5B is a plan view of FIG. 5A.
It is sectional drawing which follows the X-ray. In the third embodiment, the sensing element and the temperature compensation element of the first embodiment are replaced with three Schottky diodes having different current paths. The sensing region 3 in FIG. 1 includes a P-type region 3b and an N-type region 3b.
In the third embodiment, the surface of the N-type region is the N-type epitaxial layer 51 selectively formed in the region where the sensing element is formed by the epitaxial growth method. The buried diffusion layer 52 is formed in a predetermined area. The impurity concentration of the P type buried diffusion layer 52 is about 5 × 10 ¹⁸ / cm ³ . The surface of the epitaxial layer 51 has a surface impurity concentration of 5 × 10 ¹⁸
/ Cm ³ of P-type diffusion layers 53a, 53b and 53c and a high-concentration N-type diffusion layer 54a of surface concentration of about 1 × 10 ²⁰ / cm ³ ,
54b and 54c are formed, and the P-type diffusion layer 53a and the N-type high concentration diffusion layer 54a, the P-type diffusion layer 53b and the N-type high concentration diffusion layer 54b and P are formed.
The Schottky diodes 60, 61 and 62 are constituted by the type buried diffusion layer 52 and the N type high concentration diffusion layer 54c, respectively.

As can be seen from the figure, the junction surfaces of these three Schottky diodes 55, 56 and 57 are orthogonal to each other. The P-type high-concentration diffusion layers 58a, 58b, and 58c arranged in each Schottky diode are for making ohmic contact with the wiring. The P-type diffusion layer 53c includes the P-type buried diffusion layer 52 and the P-type high concentration diffusion layer 58c.
It is for reducing the resistance between them. The insulating film 8 made of a silicon nitride film is formed on the epitaxial layer 51, and the wiring 63 of the Schottky diodes 60, 61, 62 is formed through the contact hole 59 opened in the insulating film 8. The wiring 63 is formed by the polyimide film 16 as in the first embodiment.
And extends to the area of the base 2 in FIG. Although not specifically shown, Schottky diodes 60, 61, 62
A temperature compensating element having the same structure as the above is formed in the rear high rigidity region 2 in FIG.

When stress is applied to the grip portion 5 in FIG. 1, strains in different directions are generated in the sensing region 3 depending on the direction of the stress. Embodiment 1,
In No. 2, the surface strain is measured by one sensor. This is not a problem for work in which the direction of stress is limited to some extent, but when performing complicated work by operating the micromanipulator in a master / slave environment, the stress components in each direction of the gripping part should be separated. Therefore, it is particularly desirable to have a configuration in which feedback is provided to the master manipulator. On the other hand, in the method of the third embodiment, the directional components of the strain in the sensing region 3 can be separated by comparing the output modulations of three Schottky diodes having mutually orthogonal junction surfaces. As a result, it is possible to construct an environment for realizing complicated and sophisticated work by the micromanipulator, such as separating the stress applied to the gripping portion in each direction and feeding it back to the master manipulator.

Further, in the third embodiment, since the current flowing through the junction surface of the Schottky diode is used for sensing, higher detection sensitivity can be obtained as compared with the method of changing the direction of the diffusion resistance and using the piezoresistive effect. To be Furthermore, in the method of the third embodiment, since the three sensing elements are integrally formed on the grip portion, it is not necessary to assemble the force sensor, which is suitable for downsizing. The manufacturing method described in the first embodiment can be basically applied as it is. Furthermore, in the third embodiment, the force sensor in which the grip portion is integrally formed is shown, but the grip portion may be formed separately and assembled by a method such as adhesion.

(Embodiment 4) A force sensor according to Embodiment 4 of the present invention will be described with reference to FIGS. 6 and 7A and 7B. Here, FIG. 6 is a plan view of the force sensor according to the fourth embodiment, FIG. 7A is a cross-sectional view taken along the line XX of FIG. 6, and FIG. 7B is a line YY of FIG. FIG. FIG. 6 shows a force sensor with a triaxial grip. This includes a base 71, a rear high rigidity region 72, sensing regions 73a to 73c, a front high rigidity region 74, and a grip 75.
Both are made of silicon. The sensing area 73 is divided by a slit 76 into three parts, a first sensing area 73a, a second sensing area 73b, and a third sensing area 73c. In addition, the second sensing area 73
In b, a portion corresponding to a thickness of about half of the whole is removed from the surface side. Therefore, the second sensing area 73b is
The thickness is about half the thickness of the first sensing region 73a and the third sensing region 73c.

A recess 77 is provided at the center of the surface of the rear high rigidity region 72, and the depth from the surface is equal to that of the second sensing region 73b. Sensing area 73a, 73
The strain sensing elements 78a, 78b, 78 are provided on the surfaces of b, 73c.
c are respectively formed, and temperature compensation elements 79a and 79c are formed on both sides of the depression 77 on the surface of the rear high rigidity region 72.
Temperature compensation elements 79b are formed on the respective 77. These strain sensing elements 78a to 78c and temperature compensation element 79
All of a to 79c are PNP type bipolar transistors of the same form, and the structure is the same as that shown in FIG.
An electronic circuit 80 is formed on the base 71. Wirings 82 are formed on the surface of the silicon nitride film 81, and the strain sensing elements 78a to 78c and the temperature compensating element are formed through contact holes (not shown) formed in the silicon nitride film 81.
79a-79c and the electronic circuit 80 are electrically connected by wiring (not shown). Further on top of that is a polyimide film 83
And a pad opening 84 for connection with an external lead is formed in the base 71. The electronic circuit 80
To the external lead wire extends to the pad opening 84.

In this figure, the wiring 82 is omitted except for the portion of the pad opening 84 in order to avoid complication, but the strain sensing elements 78a to 78c and the temperature compensating elements 79a to 79c are not shown. Each terminal is connected to the electronic circuit 80, and the required number of wires from the electronic circuit 80 are connected to the pad opening 84.
It extends to the part of. Strain sensing elements 78a to 78c and temperature compensation elements 79a to 79c are connected to the electronic circuit 80 by wiring 82, and flip-flop circuits and output signals for driving these elements (PNP type bipolar transistors) in a time division manner. A bridge circuit for detection and an external controller for feedback control of the micromanipulator include an A / D converter and a signal transmission circuit for transmitting the state of stress of the grip portion. With the function of this circuit, energy supply and signal transmission between the force sensor with the grip and the external controller can be realized with relatively few wires.

When stress is applied to the grip portion 75 in the positive direction of the X-axis shown in the plan view of FIG. 6, compressive strain is applied to the strain sensing element 78a, and stress is applied to the strain sensing element 78a.
Tensile strain is generated for c and almost no strain is generated for the strain sensing element 78b, which is substantially on the neutral plane of the curve. When stress is applied in the positive Z-axis direction,
Equal compression strains are generated in the strain sensing elements 78a to 78c. When stress is applied in the positive direction of the Y-axis (not shown, vertically downward on the paper surface), the strain sensing elements 78a and 78c generate equal tensile strain due to surface strain, and are present almost on the neutral line. Almost no strain occurs in the strain sensing element 78b that operates. That is, the joint surface of the strain sensing element 78b has the strain sensing elements 78a, 78c.
It is possible to obtain different current modulation by being arranged deeper and closer to the neutral surface of the curve when distortion is applied in the Y-axis direction.

As described above, according to the fourth embodiment, the grip portion
Since the output modulations of the three strain sensing elements 78a to 78c differ depending on the direction of the stress applied to 75, the stress in each direction can be calculated separately by comparing these. In addition, slits 76 are provided in the sensing areas 73a to 73c.
Is provided, the strain generated in the strain sensing elements 78a and 78c when stress is applied in the X-axis direction can be increased, and thus the sensitivity to the stress in the X-axis direction can be increased. In addition, the written X, Y,
Note that the direction of each axis of Z corresponds to FIG. The temperature compensating element 79b is provided in the recess 77 in order to make the impurity concentration distribution of the element completely the same as that of the strain sensing element 78b. Temperature compensation element 79a, 79c
Are the same element, one of them can be omitted.

As described above, according to the fourth embodiment, it is possible to obtain a highly sensitive three-axis force sensor which integrates micro arms (grasping parts) for handling micro parts and cells. Further, in the fourth embodiment, because of the mechanical structure, the three sensing elements having the same shape can obtain different output modulation depending on the direction,
The sensor element has a high degree of freedom in structure, and the measurement range and measurement sensitivity can be optimized according to the application. Also,
In the fourth embodiment, the force sensor in which the grip portion 75 is integrally formed is shown, but the grip portion may be omitted and formed, and a separate grip portion may be attached by a method such as bonding. Although this method has a limit to miniaturization, the shape of the gripping part can be set relatively freely, and the end effector that does some work as well as simple gripping operation can be attached, so the gripping target It is preferable when it is relatively large.

Next, a method of manufacturing the force sensor with the grip portion of the fourth embodiment will be described with reference to FIGS.

(1). First, as shown in FIG. 18, the plane orientation is <100>, the substrate concentration is 2 × 10 ¹⁴ / cm ³ , and the thickness is 3
A silicon nitride film is formed on the back surface of a P-type silicon substrate 91 having a thickness of 00 μm by CVD, and the silicon nitride film is patterned by a photolithography technique used in usual semiconductor manufacturing to form silicon nitride film patterns 92a and 92b.
Here, the silicon nitride film pattern 92a corresponds to the base portion 71 of the force sensor with the grip portion shown in FIGS. 6 and 7, and the silicon nitride film pattern 92b corresponds to a frame portion during electrochemical etching described later. Although only one force sensor with a grip is illustrated here, it is needless to say that a large number of force sensors can be formed on one silicon substrate because the force sensor is small.

(2). Next, as shown in FIG. 19, deep N-type diffusion layers 93a and 93b and a deep P-type diffusion layer 94 are formed on the surface of the silicon substrate 91. Here, the diffusion layers 93a, 94, 93
b are formed in the regions corresponding to the rear high rigidity region 72, the sensing region 73, and the front high rigidity region 74 in FIGS. However, the deep P-type diffusion layer 94 is formed wider than the region finally formed as the sensing region 73. The impurity concentration of each of these diffusion layers is about 1 to 2 × 10 ¹⁶ / cm ^{3 on the} surface. N-type diffusion layer 93a,
The junction depth of 93b is about 25 μm, and the impurities in the P-type diffusion layer are also diffused to the same depth. Photolithography, ion implantation, and thermal diffusion used in ordinary semiconductor manufacturing are applied to the formation process of these diffusion layers.

(3). Next, as shown in FIG.
7 in which the strain sensing element 78b is formed and the depression 77 where the temperature compensation element 79b is formed
The area corresponding to is TMA using the silicon oxide film as a mask
Recessed by etching to a depth of 15 μm with an aqueous solution of H (tetramethylammonium hydroxide)
95a, 95b are formed. After the etching, the silicon oxide film of the mask is removed with an aqueous solution of hydrofluoric acid.

(4). Next, referring to FIG. 21, FIG.
As shown in (B), the junction depth is 6 μm and the surface concentration is 3 to 6
An N-type diffusion layer 96 of about × 10 ¹⁴ / cm ³ is formed. 22 (A) is a sectional view taken along the line XX of FIG. 21, FIG.
FIG. 22 is a sectional view taken along the line YY of FIG. This is shown in Figs.
It is formed in a part of the rear high rigidity region 72, the sensing region 73, a part of the front high rigidity region 74, and a region corresponding to the grip portion 75. However, the diffusion layer 96 is not formed in the portion (the area surrounded by the rectangle 97) corresponding to the slit 76 in FIGS.

(5). Next, FIG. 23, FIG.
As shown in (B), the sensing elements 78a to 78c and the temperature compensation elements 79a to 79c are formed similarly to the first embodiment.
24 (A) is a sectional view taken along line XX of FIG.
FIG. 24B is a sectional view taken along the line YY of FIG. Here, the electronic circuit 80 is also formed. A usual semiconductor manufacturing technique is applied to these formations. In addition, a guard ring 98a made of a P-type high-concentration diffusion layer that matches the outer circumference of the force sensor with a gripping portion of FIGS. 6 and 7 and a P-type high-concentration diffusion layer 98b in a region corresponding to the slit 76 of FIGS. It is also formed.

(6). Next, FIG. 25, FIG.
As shown in (B), an insulating film 8 made of a silicon nitride film
1, a contact hole (not shown), a wiring pattern 84, a polyimide film 83, and a pad opening 84 are sequentially formed. In addition,
FIG. 26 (A) is a sectional view taken along line XX of FIG. 25, and FIG. 26 (B) is a view.
It is sectional drawing which follows the YY line of 25. However, like FIG. 6 and FIG. 7, the notation of the wiring 82 in the portion other than the pad opening 84 is omitted.

(7). Next, FIG. 27, FIG. 28 (A),
As shown in (B), by immersing in a strong alkaline etchant in a state where the front surface side is mechanically sealed and protected, the silicon substrate in the area without the silicon nitride films 92a and 92b on the back surface side is removed from the back surface. Etching. Note that the figure
28 (A) is a sectional view taken along line XX of FIG. 27, and FIG. 28 (B) is FIG.
FIG. 3 is a cross-sectional view taken along line YY of FIG. At this time, the N-type diffusion layer 9
A bias is applied with 3, 96 as the anode and a strong alkaline etchant as the cathode. This is done by arranging the electrode pad of a specific wiring so as to be connected to the N-type diffusion layer 96 and applying a positive bias to it.

(8). This etching is performed by the N-type diffusion layer 93 or
In the region where 96 does not exist, the silicon nitride film 81 proceeds until it is exposed on the back surface side, but in the region where the N-type diffusion layer 93 or 96 exists, the N-type diffusion layer 93 or 96 and the P-type substrate 91 or It stops near the end of the depletion layer on the P-type side of the PN junction of the P-type diffusion layer 94. In this etching, in the region where the P-type diffusion layer is present (corresponding to the sensing region 73 in FIGS. 6 and 7), the impurity concentration of the P-type region of the junction is high, so even if the same bias is applied, The expansion of the depletion layer is suppressed, and the thickness of the remaining P-type region 73 'is reduced.

(9). On the other hand, in the region where the P-type diffusion layer does not exist (corresponding to the rear high-rigidity region 72, the front high-rigidity region 74 and the grip 75 in FIGS. 6 and 7), the impurity concentration of the P-type region of the joint is low, so Even if the same bias is applied, the depletion layer spreads greatly to the P-type side, and the remaining P-type region 72 ',
The thickness of 74 'and 75' is larger than that of the P-type region 73 '. Here, since the thickness of the gripping portion 75 in FIGS. 6 and 7 is thicker than the sensing area 73, the thickness of the sensing area is larger than that in the case where the thickness of the gripping portion and the sensing area are equal as in the first embodiment. Since distortion can be increased, it is preferable in terms of high sensitivity.

(10). In addition, as described with reference to FIGS. 6 and 7, in the sensing region 73b thinned due to the shape of the recess due to etching, the diffusion layer is formed so that the thickness thereof is almost half that of the sensing regions 73a and 73b. The impurity concentration distribution and the bias condition for electrochemical etching are set. Furthermore, the lateral expansion of the depletion layer during electrochemical etching is a high concentration P-type region, which is a guard ring.
Since it is suppressed by 98a, the shape of the remaining portion in the lateral direction substantially corresponds to the junction of the N-type diffusion layer. Furthermore,
Since the lateral expansion of the depletion layer is suppressed by the high-concentration P-type region 98b formed in the portion corresponding to the slit 76, the silicon in this region is completely removed.

(11). Next, FIG. 29, FIG. 30 (A),
As shown in (B), RIE (Reactive Ion Etching) in a mixed gas atmosphere of CF ₄ and O ₂ from the back surface side.
Silicon nitride film in the region where silicon is removed by
81 is removed, and the polyimide film is cut out by laser ablation along the remaining silicon to manufacture a three-axis force sensor with a grip as shown in FIGS. Note that FIG. 30 (A) is a sectional view taken along the line XX of FIG.
30 (B) is a sectional view taken along the line YY of FIG.

(Fifth Embodiment) A force sensor according to a fifth embodiment of the present invention will be described with reference to FIGS. 8 (A) to 8 (C) and FIG. 9. 8A is a plan view of the force sensor of the fifth embodiment, FIG. 8B is a sectional view taken along line XX of FIG. 8A, and FIG.
FIG. 8C is a front view of FIG. 8 and 9 show a triaxial force sensor having an integrally formed grip portion.
A front side base portion 112 including a first front side base portion 102 and a second front side base portion 105 from which the grip portion 101 extends, and a rear side base portion including a root side first rear side base portion 103 and a second rear side base portion 106. 11
3 is supported by four silicon columns 104a, 104b, 104c, 104d. Here, the first front base 102 and the first
It is formed by bonding the bottom surfaces of the rear base 103 to each other. Strain sensing elements 107a-107d are provided on the four silicon columns 104a-104d, respectively.
An electronic circuit 108 is formed on the rear base 103. Here, the strain sensing element is of the same kind as the PNP type bipolar transistor shown in FIG.

First rear base 103 and silicon column 10
Wiring layers 109a covered with a flexible thin film made of a polyimide film are provided on the second rear base 106 and the silicon pillars 4a and 104b.
A wiring layer 109b covered with a flexible thin film made of a polyimide film is formed on 104c and 104d. Silicon stanchions 104
The terminals of the sensing elements 107a and 107b formed on a and 104b are connected to the wiring layer 109a and to the electronic circuit 108 formed on the first rear side base 103. On the other hand, sensing elements 107c and 107d formed on the silicon columns 104c and 104d.
Are connected to the wiring layer 109b and are connected to the second rear base 10
6 to the wiring layer 109b via the wiring layer 109c
To the electronic circuit 108. Here, the wiring layer 109c is for bending and connecting the wiring layers 109a and 109b, and the wiring layers 109a, 109b, and 109c are integrally formed.

The electronic circuit 108 includes a strain sensing element 10
A flip-flop circuit for driving 7a to 107d (PNP type bipolar transistor) in a time-division manner, a temperature compensation circuit, a bridge circuit for detecting an output signal, and an external controller for feeding back a micromanipulator. A for transmitting the state of stress
The / D converter and the signal transmission circuit are included. With the function of this circuit, energy supply and signal transmission between the force sensor with the grip portion and the external controller can be realized with relatively few wires. Further, each terminal of the electronic circuit 108 for external connection is connected to the electrode pad 110 by the wiring in the wiring layer 109a.

As described above, in the fifth embodiment, the base portion is supported by the four thin columns, and the stress applied to the gripping portion is separately measured according to the direction by the strain sensing element formed integrally with the columns. be able to. By feeding back the stress thus measured to the master manipulator, a good micromanipulation environment for manipulating minute parts and cells can be constructed. Further, in the fourth embodiment, the structural difference causes a large difference in sensitivity between the X direction and the Y direction in FIGS. 6 and 7, but in the fifth embodiment, the direction dependency of the measurement sensitivity is relatively small.
More suitable for delicate work. The force sensor according to the fifth embodiment has a grip part integrally formed.
It is also possible to apply a thin glass needle or the like to the tip by a method such as adhesion without forming the above, and apply it to the micromanipulator as shown in FIG.

Next, a method of manufacturing the force sensor with the grip portion of the fifth embodiment will be described with reference to FIGS.

(1). First, as shown in FIGS. 31A and 31B, the plane orientation is <100> and the substrate concentration is 4 × 10 ¹⁵ /
A silicon nitride film is formed on the back surface of a P-type silicon substrate 121 having a cm ³ and a thickness of 300 μm by CVD, and the silicon nitride film is patterned by a photolithography technique used in ordinary semiconductor manufacturing to form silicon nitride film patterns 122a, 12a.
2b, 122c and 122d are formed. Note that FIG. 31 (A) is a plan view,
FIG. 31 (B) is a sectional view taken along line XX of FIG. 31 (A).

(2). Next, as shown in FIGS. 32A and 32B, the junction depth is 6 μm, and the surface concentration is 3 to 6 × 10 ¹⁶ / c.
m ³ of about N-type diffusion layer 123a, 123b, 123c, 123d, 123e,
Forming 123f. 32 (A) is a plan view and FIG. 32 (B) is a sectional view taken along line XX of FIG. 32 (A). Here, the diffusion layers 123a to 123f are the silicon pillars 104b and 104a of FIG.
It corresponds to 104c, 104d, 105 and 106, respectively. Subsequently, the strain sensing elements 107a, 107b, 107c, 107d and the electronic circuit 108 are formed. At this time, the guard ring region 124 made of the high concentration P-type diffusion layer is also formed.

(3). Next, FIG. 33, FIG. 34 (A),
As shown in (B), an insulating film (not shown) made of a silicon nitride film and a lower polyimide film 125 are sequentially formed on the surface of the silicon substrate 121, and then wirings 126a, 126b, 126c are formed. Note that FIG. 34 (A) is a cross-sectional view taken along line XX of FIG.
FIG. 34B is a sectional view taken along the line YY of FIG. The wirings 126a to 126c connect the strain sensing elements 107a to 107d to the electronic circuit 108 via an insulating film made of a silicon nitride film and a contact hole (not shown) opened in the lower polyimide film 125, and the electronic circuit 108 is connected. And electrode pad 110
Connected to. Here, the insulating film (not shown) made of a silicon nitride film, the lower layer polyimide film 125, the wiring 126, the upper layer polyimide film 127, and the pad opening 128 correspond to the wiring layers 109a to 109c in FIG.

In FIG. 33 and FIG. 34, in order to prevent the drawing from being complicated, the guard ring 124 is omitted and the wiring 12 is omitted.
Regarding 6, one of the wirings 126a connecting the strain sensing element 107b and the electronic circuit 108 and one of the wiring connecting the strain sensing element 107c and the electronic circuit 108
Although only the wiring 126c for connecting the electronic circuit 108 and one of the electrode pads 110 is shown in FIG. 126b, the necessary number of fine wiring patterns are actually formed by the photolithography technique of the semiconductor.

(4). Next, FIG. 35, FIG. 36 (A),
As shown in (B) and (C), the silicon nitride film pattern 122a on the back surface side is formed by immersing it in a strong alkaline etchant in a state where the front surface side is protected by being mechanically sealed.
Etch the backside of the silicon substrate in areas where ~ 122d is not present. Note that FIG. 36 (A) is a cross-sectional view taken along the line XX of FIG.
36 (B) is a sectional view taken along the line YY of FIG. 35, and FIG. 36 (C) is a view.
It is sectional drawing which follows the ZZ line of 35. At this time, the N-type diffusion layer
A bias is applied using 123 as an anode and an etchant of TMAH (tetramethylammonium hydroxide) as a cathode. This is done by arranging a specific electrode pad so as to be connected to the N-type diffusion layer 123 and applying a positive bias thereto. This etching is N
In the region where the N-type diffusion layer 123 is not formed, the process proceeds until an insulating film (not shown) made of a silicon nitride film on the front surface side is exposed on the back surface side. The P type diffusion layer 123 and the P type substrate 121 P
It stops near the end of the depletion layer on the P-type side of the N junction. Further, the lateral expansion of the depletion layer during electrochemical etching is suppressed by the guard ring 124 (see FIG. 32), which is a high-concentration P-type region, so that in the lateral direction, the shape of the remaining portion is almost the same. It corresponds to the junction of the N-type diffusion layer.

The shape of the grip portion 101 during this etching will be described with reference to FIG. Here, in the etching from the back surface side, the silicon nitride film 122a on the back surface serves as a mask. With the progress of etching, the etching surface
The process proceeds from (a) to (b) and (c) until the silicon nitride film (not shown) on the surface side is exposed. TMAH here
Due to the plane orientation dependence of the etching rate of, the grip portion 101 having a triangular cross section is finally obtained.

Next, as shown in FIG. 37, C from the back surface
RIE (Reactive) in a mixed gas atmosphere of F ₄ and O _2.
After removing the silicon nitride film exposed in the region where the silicon is removed by Ion Etching), the polyimide films 125 and 127 are cut by laser ablation into the shape shown by the thick broken line. Here, a region corresponding to the wiring layer 109c in FIG. 9 is a flexible polyimide film having a wiring layer inside. After this, the silicon in the region where the silicon nitride film 122b was formed, the region corresponding to the N-type diffusion layer 123e remaining by the electrochemical etching and the region where the silicon nitride film 122c was formed, and the silicon in the region where the silicon nitride film 122c was formed. The back surface of the substrate 121 and the region corresponding to the N-type diffusion layer 123f remaining by the electrochemical etching are bonded by a method such as bonding to obtain the force sensor with a grip portion shown in FIGS. 8 and 9.

As described above, in the manufacturing method according to the fifth embodiment, the force sensor with the triaxial grip portion is formed monolithically, and can be obtained by simple assembly. In addition, even though it has a three-dimensional structure, all electrode pads are 1
Since it is formed on one surface, it is easy to connect a lead wire to an external device. In addition, since semiconductor manufacturing technology is applied not only to element formation and electronic circuits, but also to structure formation,
A small and highly workable force sensor can be produced at low cost by batch processing.

Although the description has been given based on the embodiment, the present specification includes the following inventions.

1. A grip portion, a detection portion that detects a stress applied to the grip portion, a base portion that supports the grip portion and the detection portion, and a wiring portion that is connected to the detection portion and that extends to the base portion. In the force sensor equipped with
A force sensor, wherein the grip portion, the detection portion, the base portion, and the wiring portion are integrally formed on a thin semiconductor substrate.

(Structure) All the embodiments are applicable. For example, in the first embodiment, the grip portion 5 in FIGS. 1 and 2, the sensing region 3 serving as a detection portion that detects the stress applied thereto, the base portion 1 that supports the grip portion and the detection portion, and the detection portion are connected. And a wiring portion composed of wirings 9 to 11 extending to the base portion, and a grip portion, a detection portion, and a wiring portion are integrally formed.

(Operation / Effect) Since the grip portion, the detecting portion and the base portion are integrally formed, and the wiring portion for transmitting the sensing signal of the detecting portion to the base portion is integrally formed, the assembling process becomes unnecessary, A micro force sensor suitable for a micro manipulator used for handling a micro object can be obtained.

2. The detection unit is composed of a first region (P-type diffusion layer 18) of one conductivity type formed in the semiconductor substrate, and another conductivity type formed in the first region and different from the first region. A second region (N-type diffusion layer 19) and a third region formed in the second region and having the same one conductivity type as the first region.
1. The area (P-type diffusion layer 20) and the wiring part is composed of a plurality of wirings independently connected to the respective areas of the first to third areas. The force sensor described.

(Structure) This corresponds to the first embodiment.

(Action / Effect) Distortion in the sensing area
By measuring the current modulation between the PN junctions in the sensor first to third regions, the stress can be detected with high accuracy.

3. The detection unit is provided in a stress-strain conversion (sensing) region that converts a stress applied to the gripping unit into a strain, and in the stress-strain conversion (sensing) region, converts the strain into an electric signal and outputs the electric signal. 1. The above-mentioned 1. characterized in that it comprises a distortion detector. The force sensor described.

(Structure) This corresponds to the first embodiment.

(Operation / Effect) Since the strain sensing element (strain detecting portion) is integrally formed in the stress-strain conversion (sensing) region which is made thin, the stress-strain conversion (sensing) region can be miniaturized, which is high. Measurement sensitivity can be obtained.

4. The semiconductor substrate includes high-rigidity regions having rigidity higher than that of the detection unit at both ends of the detection unit. The force sensor described.

(Structure) This corresponds to the first embodiment. A front high-rigidity region and a rear high-rigidity region are integrally connected in front of and behind the sensing region (detection unit) in which the strain sensing element 6 is formed.

(Operation / Effect) Since the rigidity of the region where the sensing element 6 is formed is smaller than the rigidity of both end portions adjacent to each other, the strain of the detection portion when stress is applied to the gripping portion becomes large, so that the measurement accuracy is high. Is improved. Further, since the distance between the sensing element and the grip portion is increased, the influence of the temperature change accompanying the grip operation is reduced, and the temperature drift of the sensing element is reduced.

5. A thin conductive semiconductor substrate having a surface of one conductivity type, a detection portion formed on the semiconductor substrate for detecting stress applied to the semiconductor substrate, and a base portion formed on the semiconductor substrate and supporting the detection portion. A force sensor including a wiring portion connected to the detection portion and formed on the semiconductor substrate so as to extend to the base portion,
The force sensor, wherein the detection unit includes at least three detection means provided at different portions on the semiconductor substrate so as to detect stress in three directions orthogonal to each other.

(Structure) Embodiments 3 to 5 are applicable.

(Operation / Effect) A micro force sensor capable of separating and measuring the directional component of stress is obtained by having three detecting means which generate different output signals depending on the direction of applied stress. To be

6. 4. Each of the three detection means is composed of a junction surface of three PN junctions formed on the semiconductor substrate. The force sensor described.

(Structure) Embodiments 3 to 5 are applicable.

(Operation / Effect) When a bending stress or a compressive stress is applied to the sensing region, the change in the current flowing through the PN junction due to the strain varies depending on the junction surface. Therefore, by comparing these current modulations, the stress The directionality can be measured.

7. 5. The PN junction joining surface of at least one of the three detecting means is provided at a portion different from the PN junction joining surface of the other detecting means. The force sensor described.

(Structure) Embodiments 3 and 4 are applicable.

(Operation / Effect) When bending stress or compressive stress is applied to the sensing region, different current modulation is obtained depending on the depth of the joint surface, so that the directionality of the stress can be detected.

8. The semiconductor substrate is provided with a recessed region,
7. At least one of the three detecting means is provided in the recessed area. The force sensor described.

(Structure) This corresponds to the fourth embodiment.

(Operation / Effect) Since the recess is provided in a part of the sensing region, it is possible to obtain PN junctions having different junction surfaces with diffusion layers having the same junction depth.

9. A bonding surface of the three PN junctions has a first bonding surface having a direction parallel to the main surface of the semiconductor substrate, and a second bonding surface having a second direction orthogonal to the first bonding surface. And a third joint surface having a third direction orthogonal to the first and second joint surfaces. The force sensor described.

(Structure) The third embodiment is applicable.

(Operation / Effect) When a bending stress or a compressive stress is applied to the sensing area, the change in the current flowing through the PN junction due to the strain varies depending on the joint surfaces, so that the three joint surfaces orthogonal to each other are The directionality of stress can be measured by comparing the current modulation.

10. 4. The detection section includes a grip section provided along a direction extending from the base section toward the detection section so as to detect stress when gripping an object. The force sensor described.

(Structure) Embodiments 3 and 4 are applicable.

(Action / Effect) Since the grip portion is integrally provided with the force sensor capable of measuring the directions of stress separately, the grip portion is equipped with a compact and highly accurate multi-axis stress sensor. The force sensor of is obtained.

11. 4. The semiconductor substrate is provided with slits in a direction extending from the base portion toward the detection portion, and the three detection means are provided so as to be spatially separated from each other by the slits. The force sensor described.

(Structure) This corresponds to the fourth embodiment.

(Operation / Effect) Since the slit is provided, the strain when the stress is applied to the grip portion can be increased, so that the stress measurement sensitivity is improved.

12. The detection unit is provided in a stress-strain conversion (sensing) region that converts a stress applied to the gripping unit into a strain, and in the stress-strain conversion (sensing) region, converts the strain into an electric signal and outputs the electric signal. 5. A distortion detecting unit. The force sensor described.

(Structure) Embodiments 3 and 4 are applicable. Taking Embodiment 4 as an example, the stress strain conversion (sensing) region
Strain detectors (sensing elements) 78 on 73a, 73b, 73c
a, 78b, and 78c are formed respectively.

(Action / Effect) Stress converting stress into strain By integrally forming a detecting portion for sensing in the stress-strain converting region, it becomes possible to miniaturize the converting region, resulting in conversion of low rigidity. Since the area is obtained, it becomes possible to measure minute stress.

13. 4. The semiconductor substrate is provided with high-rigidity regions having higher rigidity than the detection unit at both ends of the detection unit. The force sensor described.

(Structure) This corresponds to the fourth embodiment.

(Operation / Effect) Detection Unit (Sensing Element)
Since the rigidity of the region in which is formed is smaller than the rigidity of both end portions adjacent to each other, the distortion of the detection portion when stress is applied to the gripping portion is increased, and therefore the measurement accuracy is improved. Further, since the distance between the detection unit and the gripping unit becomes large, the influence of temperature change due to the gripping operation is reduced, and the temperature drift of the detection unit is reduced.

14. (Structure) A thin-film semiconductor substrate having one conductivity type surface, a flexible portion formed on the semiconductor substrate, and the flexible substrate formed on the semiconductor substrate with the flexible portion interposed therebetween. Two detection parts for detecting the stress applied, two base parts formed on the semiconductor substrate with the flexible part sandwiched therebetween and supporting the detection part, and formed on the semiconductor substrate and the flexible part. In the force sensor including the wiring portion electrically connecting the two detection portions, the two detection portions are arranged to face each other by bending the flexible portion. sensor.

(Structure) This corresponds to the fifth embodiment.

(Operation / Effect) Multi-axial stress sensing is enabled by the strain sensing elements formed in the thin plate-shaped semiconductor regions serving as the detection sections which are arranged facing each other, and the wiring of these sensing elements is flexible. The electrodes can be placed on one side because they are connected by flexible flexible thin film wiring layers.

15. At least one of the two detectors is provided with a grip provided along a direction extending from the base toward the detector so as to detect stress when gripping an object. 14. The above-mentioned 14.
The force sensor described.

(Structure) The fifth embodiment is applicable.

(Operation / Effect) Since the force sensor capable of separating and measuring the directions of stress is integrally provided with the grip portion, the grip portion is provided with a compact and highly accurate multi-axis stress sensor. The force sensor of is obtained.

16. A slit is provided on the semiconductor substrate in a direction extending from the base portion toward the detection unit, and the two detection units include at least two detection means spatially separated from each other by the slit. 14. The force sensor described.

(Structure) This corresponds to the fifth embodiment.

(Operation / Effect) Since the slits are provided, the strain when the stress is applied to the pressure sensitive portion can be increased, so that the stress measurement sensitivity is improved.

17. The detection unit is provided in a stress-strain conversion (sensing) region that converts a stress applied to the gripping unit into a strain, and in the stress-strain conversion (sensing) region, converts the strain into an electric signal and outputs the electric signal. 14. The above-mentioned 14. characterized in that it comprises a distortion detector. The force sensor described.

(Structure) The fifth embodiment is applicable. Stress-strain conversion (sensing) area (silicon column) 104a, 104
Distortion detectors (sensing elements) 107a, 1 on b, 104c, 104d
07b, 107c and 107d are formed respectively.

(Operation / Effect) Stress converting stress into strain By integrally forming a sensing portion for sensing in the strain converting region, it becomes possible to miniaturize the converting region, resulting in conversion of low rigidity. Since the area is obtained, it becomes possible to measure minute stress.

18. 14. The semiconductor substrate is provided with high-rigidity regions having rigidity higher than that of the detection unit at both ends of the detection unit. The force sensor described.

(Operation / Effect) Detection Unit (Sensing Element)
Since the rigidity of the region in which is formed is smaller than the rigidity of both end portions adjacent to each other, the distortion of the detection portion when stress is applied to the gripping portion is increased, and therefore the measurement accuracy is improved. Further, since the distance between the detection unit and the gripping unit becomes large, the influence of temperature change due to the gripping operation is reduced, and the temperature drift of the detection unit is reduced.

19. 1. A control unit, which is connected to the detection unit via the wiring unit and is provided with an electronic circuit such as a signal amplification circuit or a switching circuit, or a temperature compensation element, is provided in the base portion or the high rigidity region. ~ 1
8. The force sensor described.

(Structure) The forms of Embodiments 4 and 5 are applicable. Taking the fourth embodiment as an example, an electronic circuit 80 is formed on the base 71.

(Operation / Effect) By the function of this circuit,
Energy supply and signal transmission between the force sensor with the grip and the external controller can be realized with relatively few wires. In addition, since a bridge circuit and amplifier can be placed close to the sensor, it is possible to perform stress measurement with high noise resistance.

20. A step of forming a diffusion layer of one conductivity type on the surface of a semiconductor substrate of another conductivity type, and etching with an alkaline solution from the back surface side while the surface of the semiconductor substrate is protected, and at this time, diffusion of the one conductivity type 1. The layer is used as an anode, and the diffusion layer is left as a thin plate-shaped semiconductor region having one conductivity type or a gripping portion by electrochemical etching using the alkaline solution as a cathode. ~ 19. The force sensor described.

(Structure) This corresponds to the manufacturing method of the first, fourth, and fifth embodiments.

(Function / Effect) The thickness of the region left by the electrochemical etching is determined by the junction depth of the N-type diffusion layer and P
By controlling the spread of the depletion layer on the P-type region side when the bias of the N-junction is applied, the thickness of the remaining silicon can be controlled in a wide range. The shape controllability of the method of leaving thin silicon by this electrochemical etching is defined by the controllability of the impurity concentration distribution and the potential distribution when a bias is applied, but the controllability of ion implantation, photolithography and thermal diffusion is the semiconductor manufacturing technology. The controllability is extremely high. Therefore, the microstructure can be manufactured with extremely high reproducibility as compared with the conventional machining. Moreover, since the force sensor itself with the grip portion is small, mass production is possible by batch processing, and the manufacturing cost can be reduced.

21. A step of forming a diffusion layer having a deep junction depth of one conductivity type and a diffusion layer having a shallow junction depth of one conductivity type on the surface of a semiconductor substrate of another conductivity type; Etching from the back surface side with an alkaline solution, in which case the diffusion layer of one conductivity type is used as an anode and the alkaline solution is used as a cathode to leave a region of the diffusion layer having a shallow junction depth, which is left unetched. Is a semiconductor of a thin plate type having one conductivity type on the surface, and a diffusion layer having a deep junction depth is left to serve as the base portion, a highly rigid region, or a grip portion. ~ 19. A method for manufacturing the force sensor described.

(Structure) This corresponds to the manufacturing method of the first, fourth, and fifth embodiments.

(Action / Effect) It is desirable to obtain a large strain due to stress. It is desirable that the junction depth of the diffusion layer in the sensing region is made shallow so that the strain is not significantly received. By increasing the junction depth of the layers, the thickness left for electrochemical etching is controlled. In this method, the controllability of the thickness and the planar shape is defined by the controllability of the impurity concentration distribution and the potential distribution when a bias is applied, but the controllability of ion implantation, photolithography and thermal diffusion is used in semiconductor manufacturing technology. The controllability is extremely high. Therefore, the microstructure can be manufactured with extremely high reproducibility as compared with the conventional machining.

22. A step of providing a diffusion layer having a higher concentration than that of the other conductive type substrate on a predetermined area of the surface of the other conductive type semiconductor substrate; Forming a diffusion layer of one conductivity type having a concentration higher than that of the diffusion layer having a higher concentration, and etching with an alkaline solution from the back surface side while protecting the surface of the semiconductor substrate, and at this time, the diffusion layer of one conductivity type Is used as an anode, and a region of the diffusion layer of the first conductivity type is left by electrochemical etching using the alkaline solution as a cathode to form a region in which a diffusion layer having a higher concentration than that of the other conductivity type substrate is formed. 1. A semiconductor having a different thickness is left in a non-existing region. ~ 19. A method for manufacturing the force sensor described.

(Structure) Examples 1, 4, and 5 are applicable. In the fourth embodiment, the concentration on the P-type side in the vicinity of the junction of the N-type diffusion layer 96 corresponding to the sensing region is the same as that of the N-type diffusion layer 96 in the region corresponding to the grip portion because of the P-type diffusion layer 94. It is higher than the concentration on the P-type side near the junction. Therefore, the width of the depletion layer at the time of electrochemical etching is different, and as a result, the remaining regions having different thicknesses are obtained.

(Operation / Effect) The remaining film thickness is controlled by changing the impurity concentration in the vicinity of the P-type PN junction during the electrochemical etching. By this method, it is possible to obtain the difference in thickness between the sensing region and the base or the region where high rigidity is required.

23. 20. ~twenty two. In the method for manufacturing a force sensor or a gripping device according to the above item 1, a high-concentration diffusion layer of another conductivity type is formed on the outer peripheral portion of the diffusion layer of one conductivity type to be left. ~ 19. A method for manufacturing the force sensor described.

(Structure) This corresponds to the manufacturing method of Embodiments 1, 4, and 5. In the first embodiment, the N-type diffusion layer 105 and
A high-concentration P-type guard ring region 106 is formed on the outer peripheral portion of 104.

(Operation / Effect) When a region of the N-type diffusion layer is left by electrochemical etching, a high-concentration P-type diffusion layer is arranged in the outer peripheral portion to suppress the expansion of the depletion layer of the PN junction. This improves the shape accuracy of the remaining region.

24. Between a region serving as a base portion on which the wiring connected to the first sensing region extends and a region serving as a base portion on which the wiring connected to the second sensing region extends, on a semiconductor substrate of another conductivity type. A step of forming a flexible thin film provided with an opening for connecting to a wiring in each region, and a step of forming a wiring for electrically connecting each region on the flexible thin film And removing the semiconductor substrate between a region serving as a base portion on which the wiring connected to the first sensing region extends and a region serving as a base portion extending on the wiring connected to the second sensing region. A step, and a region serving as a base on which the wiring connected to the first sensing region extends,
14. The method according to the above 14, characterized in that the method further comprises a step of joining the areas, which are the bases, in which the wirings connected to the second sensing area extend, to each other on the back surfaces. ~ 18. A method for manufacturing the force sensor described.

(Structure) The manufacturing method of Embodiment 5 is applicable. On the P-type semiconductor substrate, the wiring extending on the N-type diffusion layers 123a and 123b to the region corresponding to the first rear side base 103 and the wiring extending on the N-type diffusion layers 123c and 123d to the region 123e. And a region other than the region where the N-type diffusion layers 123a to 123f are formed and the region which is the base, for forming the flexible wiring thin film including the polyimide films 125 and 127 and the wirings 126a and 126b. Of removing the substrate by electrochemical etching, the region corresponding to the base 103 and the N-type diffusion layer
There is a step of joining the back surfaces of the regions corresponding to 123e.

(Operation / Effect) The triaxial force sensor with the grip portion is monolithically formed and can be obtained by simple assembly. In addition, since all the electrode pads are formed on one surface despite having a three-dimensional structure, it is easy to connect lead wires to an external device. Further, since the semiconductor manufacturing technique is applied not only to the element formation and the electronic circuit but also to the structure formation, a force sensor with a gripping portion which is minute and has high workability can be produced at low cost by batch processing.

[0144]

As described in detail above, according to the present invention, it is possible to apply a high-sensitivity and small-scale application to a micromanipulator without fixing a high-sensitivity strain sensor to a microstructure having a small rigidity as in the prior art. A force sensor can be provided.

[Brief description of drawings]

FIG. 1 is a plan view of a force sensor according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line XX of FIG. 1;

3A and 3B are explanatory views of a sensing element which is one configuration of the force sensor of FIG. 1, FIG. 3A is a plan view, and FIG. 3B is a cross section taken along line XX of FIG. 3A. Fig.

FIG. 4 is an explanatory view of a force sensor according to a second embodiment of the present invention, FIG. 4 (A) is a plan view of a wiring region of the force sensor, and FIG. 4 (B) is a plan view of FIG. 4 (A). Sectional drawing which follows the XX line.

5A and 5B are explanatory views of a force sensor according to a third embodiment of the present invention. FIG. 5A is a plan view of a wiring region of the force sensor, and FIG. 5B is a plan view of FIG. 5A. Sectional drawing which follows the XX line.

FIG. 6 is a plan view of a force sensor according to a fourth embodiment of the present invention.

7A is a sectional view taken along line XX of FIG. 6, and FIG. 7B is a sectional view taken along line YY of FIG.

8A and 8B are explanatory views of a force sensor according to a fifth embodiment of the present invention, FIG. 8A is a plan view of the force sensor, and FIG.
Is a cross-sectional view taken along line XX in FIG. 8A, and FIG. 8C is a front view of the force sensor.

9 is a perspective view of the force sensor of FIG.

FIG. 10 is a process drawing of the method of manufacturing the force sensor according to the first embodiment of the present invention, and is an explanatory view until a silicon nitride film pattern is formed on the back surface of the substrate, FIG.
FIG. 10B is a cross-sectional view taken along line XX of FIG.

FIG. 11 is a process chart of the method for manufacturing the force sensor according to the first embodiment of the present invention, and is an explanatory view until a deep diffusion layer is formed on the substrate surface, FIG. 11 (A) is a plan view, and FIG. (B)
Is a cross-sectional view taken along line XX of FIG.

FIG. 12 is a process chart of the method of manufacturing the force sensor according to the first embodiment of the present invention, and is an explanatory view until a diffusion layer shallower than the diffusion layer of FIG. 11 is formed on the substrate surface. 12A is a plan view, and FIG. 12B is a cross-sectional view taken along line XX of FIG. 12A.

FIG. 13 is a process chart of the method for manufacturing the force sensor according to the first embodiment of the present invention, and is an explanatory view until a sensing element, a temperature compensation element, and a high-concentration diffusion layer are formed on the substrate surface. 13A is a plan view and FIG. 13B is FIG.
Sectional drawing which follows the XX line of (A).

FIG. 14 is a process diagram of the method of manufacturing the force sensor according to the first embodiment of the present invention, and is an explanatory diagram up to forming contact holes and wirings on the surface of the substrate, FIG. 14B is a cross-sectional view taken along the line XX of FIG.

FIG. 15 is a process drawing of the method of manufacturing the force sensor according to the first embodiment of the present invention, which is an explanatory view until an opening for an electrode pad is formed on the substrate surface, and FIG. 15B is a cross-sectional view taken along line XX of FIG. 15A.

FIG. 16 is a process diagram of the method of manufacturing the force sensor according to the first embodiment of the present invention and is an explanatory diagram up to etching the back surface side of the substrate, FIG. 16 (A) being a plan view and FIG. 16 (B). 16A is a cross-sectional view taken along line XX of FIG.

FIG. 17 is a final step diagram of the method for manufacturing the force sensor according to the first embodiment of the present invention, FIG. 17 (A) is a plan view, and FIG.
17B is a cross-sectional view taken along line XX of FIG.

FIG. 18 is a process drawing of the method of manufacturing the force sensor according to the fourth embodiment of the present invention, and is an explanatory view until a silicon nitride film pattern is formed on the back surface of the substrate, FIG.
18B is a cross-sectional view taken along line XX of FIG.

FIG. 19 is a process chart of the method of manufacturing the force sensor according to the fourth embodiment of the present invention, and is an explanatory view until a deep diffusion layer is formed on the substrate surface, FIG. 19 (A) is a plan view, and FIG. (B)
Is a cross-sectional view taken along line XX of FIG.

FIG. 20 is a process chart of the method for manufacturing the force sensor according to the fourth embodiment of the present invention, and is an explanatory diagram up to forming a depression in a region where one sensing element and one temperature compensation element are provided on the substrate surface. , FIG. 20 (A) is a plan view, and FIG. 20 (B).
20A is a cross-sectional view taken along line XX of FIG.

FIG. 21 is a process drawing of the method of manufacturing the force sensor according to the fourth embodiment of the present invention, and is a plan view showing a process for forming an N-type diffusion layer on the substrate surface.

22A is a cross-sectional view taken along line XX of FIG. 21A, and FIG. 22B is a cross-sectional view taken along line YY of FIG.

FIG. 23 is a process view of the method of manufacturing the force sensor according to the fourth embodiment of the present invention, and is a plan view of forming a sensing element, a temperature compensation element, an electronic circuit, and a high-concentration diffusion layer on the surface of the substrate.

24A is a sectional view taken along line XX of FIG. 23, and FIG. 24B is a sectional view taken along line YY of FIG.

FIG. 25 is a process view of the method of manufacturing the force sensor according to the fourth embodiment of the present invention, and is a plan view of forming an insulating film, a contact hole, a wiring pattern, a polyimide film, and a pad opening on the substrate surface.

26A is a sectional view taken along line XX of FIG. 25, and FIG. 26B is a sectional view taken along line YY of FIG. 25.

FIG. 27 is a process view of the method of manufacturing the force sensor according to the fourth embodiment of the present invention, and is a plan view until the back surface of the substrate is etched.

28A is a sectional view taken along line XX of FIG. 27, and FIG. 28B is a sectional view taken along line YY of FIG. 27.

FIG. 29 is a plan view showing the final step of the method for manufacturing the force sensor according to Example 4 of the present invention.

30A is a sectional view taken along line XX of FIG. 29, and FIG. 30B is a sectional view taken along line YY of FIG. 29.

FIG. 31 is a process chart of the method of manufacturing the force sensor according to the fifth embodiment of the present invention, and is an explanatory view until a silicon nitride film pattern is formed on the back surface of the substrate, FIG. 31 (A) is a plan view,
31B is a cross-sectional view taken along line XX of FIG.

FIG. 32 is a process chart of the method of manufacturing the force sensor according to the fifth embodiment of the present invention, which is an explanatory diagram for forming a deep diffusion layer and a high-concentration diffusion layer on the substrate surface, and FIG. A plan view and FIG. 32B are cross-sectional views taken along line XX of FIG.

FIG. 33 is a process view of the method of manufacturing the force sensor according to the fifth embodiment of the present invention, and is a plan view of forming a wiring connecting the strain sensing element and the electronic circuit on the surface of the substrate.

34A is a sectional view taken along line XX of FIG. 33, and FIG. 34B is a sectional view taken along line YY of FIG.

FIG. 35 is a process view of the method of manufacturing the force sensor according to the fifth embodiment of the present invention, and is a plan view of the back surface side of the substrate until it is etched.

36A is a sectional view taken along line XX of FIG. 35, FIG. 36B is a sectional view taken along line YY of FIG. 35, and FIG. 36C is Z of FIG. -A sectional view taken along the line Z.

FIG. 37 is a plan view showing the final step of the method of manufacturing the force sensor according to Example 5 of the invention.

FIG. 38 is an explanatory diagram of a conventional micromanipulator.

[Explanation of symbols]

1, 71, 102, 103 ... Base part, 2, 72, 106 ... Rear high rigidity region, 3, 73a to 73c ... Sensing region, 4, 74, 105 ... Front high rigidity region, 5, 75, 101 ... Gripping part , 6, 78a to 78c, 107a to 107d ... Strain sensing element, 7, 79a to 79c ... Temperature compensation element, 9, 10, 11, 12, 13, 14, 15, 45, 46, 47 ... Wiring, 17 ... Opening Section, 18, 34a, 34b, 41, 42, 94 ... P-type diffusion layer, 19, 33a, 33b, 35, 93a, 93b, 96, 123a to 123d ... N
Type diffusion layer, 20, 48a to 48c, 98a, 98b ... P type high concentration diffusion layer, 31 ... Silicon substrate, 36, 124 ... Guard ring, 43 ... N type high concentration diffusion layer, 44, 49 ... Contact hole , 50, 51, 52 ... Schottky diode, 76 ... Slit, 77, 95a, 95b ... Dimple, 80, 108 ... Electronic circuit.

Claims (3)

[Claims] 1. A grip portion, a detection portion for detecting a stress applied to the grip portion, a base portion for supporting the grip portion and the detection portion, and a base portion connected to the detection portion and extending to the base portion. In the force sensor having the wiring portion, the grip portion, the detecting portion, the base portion and the wiring portion are integrally formed on a thin semiconductor substrate. 2. A semiconductor substrate having a thin plate-like surface of one conductivity type, a detection unit formed on the semiconductor substrate for detecting stress applied to the semiconductor substrate, and the detection unit formed on the semiconductor substrate. In a force sensor including a base portion that supports, and a wiring portion that is connected to the detection portion and that is formed on the semiconductor substrate so as to extend to the base portion,
The force sensor, wherein the detection unit includes at least three detection means provided at different portions on the semiconductor substrate so as to detect stress in three directions orthogonal to each other. 3. A semiconductor substrate in the form of a thin plate having a surface of one conductivity type, a flexible portion formed on the semiconductor substrate, and a semiconductor substrate formed on the semiconductor substrate with the flexible portion interposed therebetween. Two detectors for detecting stress applied on the two, two bases formed on the semiconductor substrate with the flexible portion interposed therebetween to support the detector, the semiconductor substrate and the flexible portion. In the force sensor having a wiring part that electrically connects the two detection parts to each other, the two detection parts are arranged to face each other by bending the flexible part. Force sensor to do.