MXPA96006277A - Memo micromechanic sensor - Google Patents

Abstract

The present invention relates to a micromechanical memory sensor that includes a closing member assembly mechanically by detecting a threshold value of a variable condition (ambient temperature, acceleration, pressure). The mechanical seal is detected by the circuit of a reading mechanism. The sensor further includes a reset mechanism such as a thermal resistor, test mass or electrostatic combing unit for electrically opening the closure member assembly where the sensor is closed in a purely mechanical way in its operating states and is electrically restored. for repeated use

Description

MICROMECANIC MEMORY SENSOR BACKGROUND OF THE INVENTION This invention relates to a micromechanical memory sensor. More particularly, the invention focuses on a micromechanical device that serves as a sensor or mechanical memory link whose activation is triggered by a change in conditions such as temperature, acceleration and / or pressure. The contents of the memory link can be conveniently detected at any time after activation of the hooking. The device can be repassed electronically in such a way that it can be conveniently reused. While the invention is especially focused on the technique of micromechanical memory sensors and will therefore be described with specific reference to the, it will be appreciated that the invention can also be applied in other fields and applications. Micromechanical memory sensors are used or have a potential use to detect several different conditions or variables. These variables or conditions include temperature, acceleration, pressure, out. ... etc., For example, a micromechanical memory sensor adaptable for use to detect extremes of fully mechanical temperature and electronically repositionable would be of use in applications in which the field test is carried out on products and there is no energy supplies in the field. However, micromechanical temperature sensors of this type are not known. Conventional electronic temperature sensors require a power supply when temperatures are monitored. However, in the majority of cases in which the extreme temperature at which a product has been exposed is the information that is desired, field temperature monitoring is not possible with conventional techniques since it is not always possible you have an energy supply. S has also presented a bi-stable fast-acting microaccessor having a power supply, or battery. H. Matobo T. Ishikawa, C. Ki, P. Muller, A Bisfcable Snapping Microact i vator, I.E.E.E., January 1994, pages 45-50. The actuator includes a flexible overhang that buckles when a temperature e is detected: current-induced trem. While this device is unleashed by a temperature change, ie, resistive dissipation, an acceptable operation is achieved only by the use of excitation voltages and current pulses applied in a particular sequence of events. This microactuator is not only mechanically operated.

As a further example, certain chromechanical memory sensors adapted for use as latching accelerometers are known and provide an inexpensive way to detect accelerates moderate to high ions by the use of a micromechanical memory sensor. An engagement accelerometer is a switch that engages if accelerated by a predetermined acceleration in a particular direction and remains engaged after the suspension of acceleration. The primary advantage of latching accelerometers compared to conventional acceleration sensor devices is that latching accelerometers do not require complicated electronic devices for detection. The detected acceleration can be read long after the acceleration event. Acceleration couplings operate without a power supply and can operate at levels g which range from only a few g to several thousand e g and to detect * the duration during which they are scheduled to be selected. U.S. Patent No. 4,891,255 to Ciarlo presents an acceleration latch employing bulk chromachining of (110) oriented silicon wafers to make two cantilever beams having test marks, or plates, used therein inter alia.) 3 oquea n in an acceleration threshold. The F1RURAS 21 <a) and (b) show such a coupling accelerometer. Cantilever beams C are typically several millimeters long. The fabrication of the cantilevered beams C and the test masses P is relatively complicated, since the corner and micro-chipped silicon offset of the wafers (110) is used. Bulk micromachining (110) is not easily compatible with IC processing. The cantilever beams C of the Ciarlo patent must "undergo long deviations before engaging in their test masses C. Furthermore, since the horizontal cantilever beam C must force the deflection of the vertical cantilever C, which involves e3 sliding of the two large surfaces, the frictional force between the two test masses C may be important and may result in uncertainty in the acceleration detected. In addition, cantilever beams C can not be separated again and therefore can not be separated - "*" "reposition loriarse." Another important disadvantage of Ciarlo's patent attachment is the complicated reading scheme that must to be used. Since cantilever beams C are made by etching on a silicon wafer, the two cantilevered beams C can not be ctronically activated, which makes a simple continuity test between the two cantilevered beams C impossible. schemes of The reading of the Ciar3o patent uses either capacitive techniques or optical techniques. In any of these schemes the wafer of the accelerometer must be sandwiched between two other wafers containing capacitive plates or diodes that emit light to detect the position of the cantilevers. This makes the manufacturing process more complicated and expensive. Likewise, the mi qui nado in bulk results in large devices. A direct implementation of the Ciarlo patent latching mechanism employing superficial romaqui n ic is possible1 and can solve the problem of coupling detection. However, the device would still present other problems related to the excessive length of the C-beams with the test masses P fixed at the ends thereof and could not be restored. SUMMARY OF THE INVENTION An object of the present invention is to provide an icromechanical memory sensor comprising a latch detecting a change in a variable or a condition. A further object of the present invention is the provision of a micromechanical memory sensor capable of merely mechanically engaging in response to the detection of a threshold value of a condition or variable. Another object of the present invention is the provision of a ROM memory sensor comprising a memory link, the content of which can be detected at any time after coupling. Another object of the present invention is the provision of a micromechanical memory sensor that can be re-cloned. In one aspect of the present invention, the micromechanical memory sensor registers temperature extremes beyond a preset value without the use of electrical power. That is, the sensor is only mechanically induced. Ad idily, the sensor can reposition clonars, is small and economical. In a further aspect of the present invention, the micromechanical memory sensor records the acceleration extremes experienced beyond a preset value without the use of electrical energy. The sensor is only mechanically induced. Adhere, the sensor can reposition itself, it is small and economical. In a further aspect of the present invention, the ic or eponic memory sensor registers pressure extremes e. pepmentaclos me »=. beyond a pre-established value without the use of electrical energy. The sensor is only mechanically induced. Ad i c canvas, the sensor can be repositioned, it is small and economical. Additional advantages as well as scope of application of the present invention will be apparent from the detailed description presented below. It will be understood, however, that the detailed description and the specific examples, while indicating preferred embodiments of the invention, are provided only by way of illustration, since numerous changes and odification within the spirit and scope of the present invention will be apparent to the experts in the field. DESCRIPTION OF THE DRAWINGS The present invention exists in the construction, arrangement and combination of the various parts of the device, so that the objects contemplated are achieved in the manner explained more fully below, as specified in the claims and how is illustrated in the accompanying drawings in which: FIGURES l (a) -id) are a diagrammatic representation of the engagement procedure of an exemplary embodiment of the present invention; The Fissures 2 a) - (d > are a diagrammatic representation of the repositioning procedure of the modality of the FIGURES 1 a) - (d); FIGURE 3 is a side sectional view of an icomechanical memory sensor of the present invention; FIGURES 4 < a) - < p) show the manufacturing stages of the rector of FIGURE 3; FIGURE 5 is a sectional view of an alternative embodiment of the sensor of FIGURE 3; FIGURE 6 is a sectional view of an alternative embodiment of the sensor of FIGURE 3; FIGURE 7 is a sectional view of an alternative embodiment of the sensor of the present invention; FIGURES 8a) -ip) show the manufacturing steps of the sensor of FIGURE 7; FIGURE 9 is a sectional view of an alternative embodiment of the sensor of FIGURE 7; FIGURE 10 is a sectional view of an alternative embodiment of the FIGURE 7; FIGURES ll a) -ic) are top views of an additional embodiment of the micromechanical memory sensor of the present invention for detecting acceleration; FIGURES 12 < "a) ~ () show the steps of manufacturing the sensor of FIGS. 1 to 1) using microphore surface of polysilicon; FIGS. 13a) -ic) show the steps of fabrication of the sensor of FIGS. c) using nickel surface micromache 1; FIGURE 14 or a top view of a further embodiment of the micromechanical memory sensor of the present invention for detecting acceleration in one direction; FIGURE 15 is a top view of a further embodiment of the sensor; micromechanical memory of the present invention to detect acceleration in two directions; FIGURE 16 is a top view of a further embodiment of the micromechanical memory sensor of the present invention for detecting acceleration; FIGURE 17 is a top view of a further embodiment of the micromechanical memory sensor of the present invention for detecting acceleration; FIGURES 18 (a) -ib) are stylized representations of a latching direction in the plane and a latching direction off the plane, respectively; FIGURE 19 is a top view of a further embodiment of the micromechanical memory sensor of the present invention for detecting off-plane acceleration; FIGURE 20 is a top view of the micromechanical memory sensor of FIGURE 19 incorporating a reset mechanism; and, FIGURES 21 a) -ib) show an acceleration latch of the prior art of a disengaged state and an engaged state, respectively. DETAILED DESCRIPTION OF THE PREFERRED MODALITIES L3 present invention focuses on a micromechanical memory sensor having several potential uses including, in one aspect of the invention, the detection of extreme temperatures to which the sensor is exposed, in a further aspect of the invention. present intention, the detection of acceleration ends to which the sensor is subjected, in a further aspect of the present invention, the detection of pressure extremes to which the sensor is subjected. The sensor comprises a catch triggered by the detection of a predetermined or predetermined threshold in a selected condition, that is, temperature, acceleration, pre-ion ... etc. Referring now more specifically to the drawings in which the preferred embodiments of the present invention are shown for illustrative purposes only and not to limit said invention, FIGS. 1- (d) illustrate a main concept of the present invention. Specifically, a sensor link L includes a detection mechanism S which detects an external or variable force F and mechanically engages under the reset mechanism P when the force S exceeds a predetermined extreme value for which the L coupling is located calibrated. While the S and P mechanisms are generally shown in the form of beams arranged lengthwise on the same axis, it is observed that other suitable types of mechanisms and arrangements for this can be used and the preferred ones are, they will describe next. In addition, the force F imposed on the mechanism S may be the result of a change in temperature, change in acceleration, change in pressure, or the like. In the same way, the actual movement of the mechanism S may result from the use of principles involving the bimetallic effect, mass movement, diaphragm characteristics and the like. Notably, the hitch is achieved in a completely mechanical way. That is, no power supply is required to detect the extremes. This characteristic is especially useful when it is desired to obtain information regarding extreme conditions to which products, prototypes, or other devices are exposed during field or test use. Typically, energy supplies are not readily available during field or test use. For example, when testing tires and it is important to detect a temperature extreme at which the tested tires are exposed, placing the power supply on the tire to achieve it during use is impractical. Accordingly, a sensor of the present invention is useful. According to the present invention, once an extreme condition has been detected and the sensor has been latched, as shown in FIGURE id), the sensor remains latched. This feature provides a memory of the extreme condition detected. Additionally, the present invention includes reading mechanisms, or test holes, in which it is determined whether the sensor is engaged. A convenient reading scheme, ie, conductivity test or similar, eliminates the need for visual inspection and complicated electronic reading devices. If vain sensors are manufactured on a substrate, a simple multiplexer circuit is used to selectively determine if the sensors are hooked. An illustration of the advantages of a simple reading scheme is found in the field tests of products where the sensor can be read conveniently either in the field either in the test laboratory, subsequent to the test or to use. As shown in FIGURES 2 <a) - (d), the present micromechanical memory sensor can be repositioned. The resetting mechanism R is preferably driven to induce the detection mechanism S to disengage. In the illustrated method, the mechanism P is induced to bend to the extent that the mechanism S tends to disengage from the mechanism P to return to its original position. The mechanism P may be microactively thermally ibially) piezoelectric, or electrostatic.

The replacement capacity allows the sensor to be reused. However, the structure of the sensor according to the present invention is simple and inexpensive. Accordingly, it is recognized that the sensor can also be detected with or without the included resetting characteristic. In the FIGURES l (a) -2id > , an embodiment and a general concept of the present invention are illustrated. The description that follows presents specific examples of the present invention. First, several predominantly bulk micro-machined modalities will be described (FIGURES 3-10). Afterwards, modalities will be presented in which predominantly superficial micromachining is concerned. FIGURES 11 (a) -20). Referring now to FIGURE 3, a preferred embodiment for detecting temperature, the micromechanical memory sensor 10 consists of a reset beam 20, test holes 21, detection beam 3. and support structure 40 and 50. The beams 20 and 30 are both placed along the same longitudinal axis. However, the beam 30 is more flexible than the beam 20. In addition, the beams 20 and 3 are spliced to the extent that the 3rd detection beam 30 is in opposite relation to a first surface 25 of a part 26 of p + silicon of the replacement beam 70. The replacement beam 20 includes a metal layer 22. The metal layer 22 is preferably gold. However, any metal compatible with the manufacturing process is adequate. The replacement beam 20 further includes a resistor 24 for the heating of the isilicon and the part 26 for p + silicon. The metal layer 22, the heating resistor 24, and the p-silicon part 26 are respectively divided into two layers 28 and 29 of silicon nitride (SÍ3N4). In beam 20, part 26 p + silicon extends beyond the terminal end of metal layer 22, heating resistor 24, and layers 28 and 29 of silicon nitride (IS3N4). The extension of part 26 of p + silicon has a first surface 25, as indicated above, and a second surface 27. / "The detection beam 30 includes a metallic layer 32. As in the case of the metallic layer 22, the metal layer 32 is preferably gold but could be of any suitable substance compatible with the manufacturing process. The detection beam 30 further includes a layer 34 of type n polysilicon and layers 38 and 39 of nitride splitting. silicon IS? 3N4). The test holes 21 are connected to the part 26 in the beam 20 and to the rafter 32 in the 3rd beam 30. These test specimens are of any known type compatible with conductive tests, as will be observed by the experts in the field. m teria. The support structures 40 and 50 are formed of silicon substrate and have portions 60 comprising layers of silicon pitride 62, 66 and silicon 64. Those skilled in the art will note that, while the silicon substrate is preferred for convenience, Alternative materials having similar properties may be employed without departing from the scope of the present invention. Further, in operation, the sensor 10 of FIGURE 3 employs the bimetallic effect resulting from the metallic layers 22 and 32 and the silicon layers 24 and 34, respectively, having different thermal expansion coefficients. As illustrated in FIGURE 3, both beams 20 and 30 are bimetallic. Therefore, beams 2 and 30 bend when a temperature change occurs. More specifically, with reference generally to the FIGS. Lía) -id) where the mechanism P corresponds to the v ga 20 and the mechanism S corresponds to the beam 30, when the ambient temperature increases, both beams 20, 30 begin to bend . Since the detection beam 30 is more flexible than the replacement beam 20, as a result of different geometric dimensions such as length, thickness and width, it bends to a greater extent than the beam 20. In the process, the beam of detection 30 comes into contact with 1 a replacement beam 20. Accordingly, an additional bending moment is induced in the resetting 20 due to the 3a force supplied by the contact with the detection beam 30 as shown in FIGURE Kb). As the ambient temperature rises above a preestablished temperature, the horizontal deviations of the beams 20, 30 exceed their initial splice. This causes the detection beam 30 to slide off of the replacement beam 20, as shown in FIGURE 1 (c). Since the detection beam 30 is more flexible than the replacement beam 20, it will have a greater vertical deflection than the beam 20 after sliding, as shown in FIGURE 1e). Final, as the room temperature returns to room temperature, beams 20, 30 will return to their original places without any vertical deviation. However, the detection beam 30 will be hooked under the replacement beam 20 in a hooking arrangement, as illustrated in FIGURE 1 d), and will engage the replacement beam 2. Accordingly, sensor 30 has recorded the fact that the temperature end for which it was designed to detect has been exceeded. The temperature sensor is made the point at which the detection beam ZO slides from the replacement beam 20. It is recognized that a temperature ramp of r & amp;At a moment of bending in the respective beams 20, 30, which results in a vertical deviation, the vertical deviation results in turn in a horizontal deviation since the length of the beam will remain essentially constant during the increase in temperature, cough The effects of thermal expansion on the length of the beam are minimal compared to the horizontal deviation caused by vertical deflection. A simple conductivity test can be performed to determine if the beams 20, 30 are engaged. The 5 test holes, or the reading mechanisms, 21 shown in FIGURE 3, are placed on the sensor at a convenient location. As indicated above, if single sensors are fabricated on a single substrate, then a simple multiplexer circuit is employed to selectively detect if the sensors are engaged. Specifically, if the detection beam 30 is hooked under the replacement beam 20, the metal layer 32 of the detection beam 30 is in contact with the p-silicon part 26 of the replacement beam 20 which results in a hooked circuit. This contact is ohmic and, consequently, will result in a power difference of the amount of current flowing. The ohmic contact is stopped by manipulating the test holes 21 or c i rcu i the multiple! d or related. However, if the detection beam 30 is not hooked under the replacement beam 2 < "But only touch it, as would happen in the case of a slight increase in temperature from the ambient temperature that is lower than the pre-established value, a circuit would result open. The poly silicone layer 34 of the beam 30 touches the surface 25 of the p-silicon part 26. The respective test holes 21 are therefore separated by a non-conductive path. As a result, a user will easily distinguish between the two types of contact by manipulation of the test parts, or related circuit, and, therefore, will easily detect if an engagement has occurred. It will be observed by those skilled in the art that, if the sensor 10 of Figure 3 is in the state illustrated in FIGURE 1), a p > The conductivity test will indicate in the same way that we are in the presence of an open circuit. The detection of such an open circuit represents the fact that no temperature end has been detected and that the sensor 10 is not latched. As described above, the sensor 10 engages FIG. 1 (d)) when the ambient temperature exceeds a predetermined value. Se-1 has recognized that the ability to reposition the sensor 10 is an advantage. However, it can be easily seen that the sensor 1 < "< Memop ffromechamc can be designed to be disposable and, therefore, not replace the canvas." The replenishment scheme will be specified below with general reference to FIGURES 2a) - (d) where the mechanism R corresponds to the beam 20 and the mechanism S correspond to the beam 30. As illustrated above, a heating resistor 24 is placed on the replacement beam 20. When an electric current is induced which passes through the heating resistor 24, the ca3sr The generated heat from the heating resistor 24 has little effect on the detection beam 30 since the thermal conductivity between the replacement beam 2 and 3a detection beam 30 is minimal. If, however, the thermal conductivity will cause any malfunctioning of the replacement scheme as mentioned above, the replacement beam 20 will therefore tend to double vertically. and therefore will create a bending moment on the 3rd detection beam 30, as shown in FIGURE 2 ib). Fistually, the energy dissipated by the heating resistor 24 will be sufficiently large such that the horizontal deviation of the two beams 2, 30 will be greater than its initial splice. This will cause the repositioning beam 20 to be e sliced in the detection beam as shown in e < > FIGLIRA 2í). The beam will detect or return you. p v consequent to its original position since no heat dissipates in it. Once the current of the heating resistor 24 is in open circuit as a result of the loss of contact with the detection beam 30, the reset beam 20 will no longer experience any temperature increase. Therefore, the reset beam 20 will be bent towards its original position, as shown in FIGURE 2 id), the sensor 10 returning in its entirety in its original position. The replacement has been described using the bimetallic effect. However, an alternate thermal arrangement or an arrangement using p lezolectronic material and electrodes could also be used. In addition, electrostatic replenishment can be achieved by using an adaptive array from that described in relation to FIGURE 20. While the memory sensor has been described to detect high extremes, it is recognized that low extremes can also be detected. More specifically, in an alternative embodiment, the sensor is pre-engaged in such a way that the detection beam 30 is hooked onto the reset 20, shown in FIGS. 2 a). As the temperature drops, the beam 30 deflects upward and tends to slide off beam 20. When it was reached. At an extreme temperature, the beams are fully disengaged. A simple conductivity test can then be performed to detect if the sensor is unhooked. Referring now to FIGS. 4 a) - (p), where reference numbers are increased by 200 and refer to similar elements, the manufacture of the device FIG. 3 starts with a two-sided polished silicon wafer (100) having a thin film 262 of silicon nitride on the upper and lower surfaces (FIGURE 4)). The silicon nanometer 262 is then etched using photolithography techniques and etched by chemical attacks with reactive ions (FIGURE 4 (b)). A layer 211 of silicon dioxide, engraved, and then used as a mask for p + diffusion 226 (FIGURES 4 (c) - (e) >) is then applied.; After p + diffusion, the silicon dioxide is removed - * "> (FIGURE 4f)) and deposited after silicon dioxide 219 which is recorded in parts 229 and 239 FIGURES 4 (g) - (h)). A layer of silicon dioxide 217 is then applied where the silicon nitride FIGURE 4 (?)) Was red. Sr deposits and then adds polysilicon 244 (FIGURE 4 (j)). Then, a layer of silicon nitride 248 is deposited (FIGURE 4t <)).

Both silicon nitride and polysilicon are etched to form parts 224, 228, 234, and 238 and oxidation is performed for isolation purposes (FIGURES 4il) - (m)). Then the metal layer (for example, Cr / Au) is metallized by ionic trio etched in 1.2 parts? \ 232 íFIGUPA 2 (n)). Bulk chemical etching from the back side and release of the sacrificial silicon dioxide layer are then carried out. (FIGURE 4 (o) ~ íp)). Note that the portions 260 comprising the layers of silicon nitride and silicon are formed as a result of the procedure.

Referring now to FIGURE 5, an additional alternative mode of the memory sensor for detecting acceleration extremes is shown. The sensor is virtually identical to the sensor 10 of FIGURE 3, both in its construction and manufacture, except that a test mass 52 is fabricated at the bottom of the detection beam 30, as will be seen by experts in the art. The matter. The acceleration ends in the vertical direction are detected, not by manipulation of the bimetallic effect as in the modality described in relation to FIGURE 3, but by the manipulation of mass ment and inertia. When the acceleration is increased, the ment of the test mass 52 in a predetermined direction causes the bending of the beam 30 and, consequently, the engagement under the beam 20 when an end is detected. In a manner similar to the mode of FIGURE 3, a simple conductivity test is carried out using the test holes 21 to determine whether the sensor is engaged and the heating resistor 24, 3 ternally, other techniques. electrostatic or thermal energies) is used to reposition the device. FIGURE 6 illustrates a micromechanical sensor similar in construction and fabrication to those presented in FIGURES 3 and 5, except that such a sensor detects the pressure. Specifically, the detection beam 30 and a replacement beam 20 are placed in a diaphragm 54 constructed of silicon p + similar to part 26 in FIGURE 3. The pressure in the vertical direction causes the diaphragm to bend or press downwardly. the beam 30 that is hooked under the beam 20 upon sensing a predetermined pressure end. As will be appreciated by those skilled in the art, a simple conductivity test can be performed using the test holes 21 to determine the engagement and the device can be thermally, bimetallically, piezoelectrically, or electrostatically repoused. In addition, the pressure in an opposite vertical direction can be detected if the sensor is initially engaged. FIGURE 7 illustrates a further embodiment of the present invention. As in the case of all the figures, similar numbers correspond to similar structural elements even when the specific compositions of the outer layers may vary. As shown, the sensor 10 of > FIGURE 7 is similar to the sensor of FIGURE 3 except that part 26 of p + silicon is not included and does not extend beyond the remaining capias of beam 20. Instead, it is c & a junction of the beams 20 and 30 in the sensor 10 by means of the 3 metallic extension 36 of the beam 30. In addition, the parts 60 vary in composition compared to the embodiment of FIGURE 3, the layer of S? 02 37 is placed between the supports 40, 50 and the beams 20, 30 respectively, and the part 23 is placed on the lower terminal surface of the beam 20. The part 23 is useful for reading purposes as will be described below.

It will be noted that the sensors 10 of FIGURES 3 and 7 have only subtle differences in their operation between them due to differences in configuration. For example, the sensor 10 of FIGURE 3 includes a first surface 25 that is in contact with beam 3a as the temperature increases, and a second surface 27 under which the beam 30 is intimately engaged. On the other hand, the sensor 10 of FIGURE 7 includes an extension 36 that engages below the 3rd beam 2 and comes into contact with the part 23 upon detection of a temperature threshold. To determine the engagement, test holes 21 are used. perform a simple conductivity test. In this embodiment, the test holes 21 are connected to metal wires 22 and 32. SJ is in the engaged condition, extension 3 makes contact with the part 23 and a hooked circuit is obtained, a conductive path extending to through layer 24. If it is not latched, an open circuit is obtained. * • The sensor is repositioned in the device of FIGURE 3 as described in relation to FIGURE 2, using a heating resistor 24 (or alternatively, other thermal, p ezoelectric, or electrostatic techniques). Ad ic l ically, extreme low temperatures are detected if the sensor is initially blocked. Referring now to FIGURES S (a) -ig), where the reference numbers have been increased by popr 400 and refer to similar elements, the manufacture of the device in FIGURE 7 starts with a silicon-oriented (100) polished wafer two sides with thin films of silicon dioxide 437 and silicon mtride 449 (FIGURE Bia)). The first step consists of etching the silicon nitride on the front to form parts 429 and 139 using etching techniques with reactive ions and photolithography (FIGURE 8 (b)). Then polysilicon 424, 423, 434 and silicon nitride 428, 438 are deposited and engraved on the front and on the back (FIGURE 8c)). A photolithography step is then carried out to leave a sacrificial layer 417 of photosensitive protective substance.

(FIGURE 8 (d) The metallic layers 422, 432 and 436 are then metallized by means of sputtering and recorded ÍFIGUPA 8 (e)). Note that after the etching of the metal, all the photosensitive protective substance 437 is removed. Etching by bulk etching and release by removal of the silicon dioxide layer are then performed (FIGURES 8 (f) - (g) >) Note that the parts 460 are formed in the manufacturing process: FIGURES 9 and 10 represent alternative embodiments of the sensor 10 of FIGURE 7 and illustrate a similar throttle and snag engagement as in FIGURES 5 and 6, In the same way, its operation is substantially similar to that described in relation to these figures The manufacturing process related to the embodiments of FIGURES 9 and 10 is similar to the procedure described in relation to FIGURES 8 (a) -íg), co or may be observed by experts in the field. In fact, to obtain the sensor of the FTGUPA 9, the same procedure is used except for the formation of the mass 52. During the manufacture of the device in FIGURES 3, 5, 6, 7, 9 and 30, efforts are induced residuals in thin films. Fetus efforts are released after the step of liberation step. As a result, the beams will bend upwards if the residual stress is tension and down if the residual stress is compression. This residual stress is used to adapt the sensitivity of the device. For example, if the beams show an initial deviation in the downward direction, for a small equal increase in temperature (or acceleration or pressure), it would have a greater horizontal point deviation than if the beams were flat. That is, a higher stress on the beam results in an increased initial deviation. Therefore, the effort can be used to increase the sensitivity. FIGURE 11 (a) shows a global view of another preferred embodiment of the micromechanical memory sensor, that is, an accelerator latch 100, manufactured using micromachining the surface. While the structural configuration of the hook 300 differs virtually from the engagement of FIGS. 3, 5, 6, 7, 9 and 10, the basic concepts described in relation to FIGURES l (a) -2 (d) apply equally. That is, the sensor is mechanically latched when an end of some external force is detected, suitably tested to be latched using a simple conductivity test, and electrical reset. As shown, the acceleration latch 100 comprises u? V. rectangular plate or test ground, 101, formed of silicon or nickel 3 supported by 4 bent beams 102, The bent beams 302 help to release the stress in the catch 100. When the plate 101 is subjected to an acceleration, the extended part 103, or male hitch member, of the plate 101 pushes towards the two fan-shaped structures 104a and 104b and respectively pushes the two cantilevers 105a and 105b away from each other as illustrated in FIGURE 11 ib). The combination of the structures 104a-b and 105a-b acts as a female engagement member corresponding to the male engagement member 103. The fan-shaped ends 104a and 104b have a profile to provide only a line l contact with the part e . laid 103 to minimize friction by sliding. If the acceleration exceeds a certain threshold value, the extended part 103 and consequently the plate 303 are hooked on the fan-shaped ends 104a and 104b of the old cantilevers 105a and 105b and remain latched, as shown in FIG. 11 (FIG. c) The acceleration catch 100 detects accelerations within the range of several hundred g to several thousands of g and has bent beams 102 of a length of 200 to 400 μ, a plate 101 of 200 to 4 0 μm side and cantilevers 3 Sa and] 05b of 10 20 t? long. These inventions result in an acceleration latch 100 of less than one square millimeter in size. In the case of smaller g, the lengths of the overhangs 105a and 105b can be increased as well as the plate mass can be increased by the middle of the eccentricity without metal electrodes, for example nickel on a plate of polysilicon. icio. To detect larger iva we thousands) you can increase the rigidity of cantilevers 105a and 105b. The duration of contact required for engagement between the extended portion 103 and the fan-shaped structures 104 may be increased so that the device 100 is not sensitive to shocks of shorter durations. It can also be achieved by causing the extended portion 103 of the plate 101 to travel a greater distance before starting to push the fan-shaped structures 104a and 104b near the end of the cantilevers 105a and 305b. By controlling this different feature, accelerations can be detected that range from a few g to several thousand g. The coupling can be verified by the electrical continuity test between the attenuators 106 and l7a-d which serve as test holes and reading mechanisms. This is possible since the overhangs 105a-b and plate 1 are initially electrically insulated. This is a simple procedure in comparison with the capacitive or optical detection. The coupling 100 of FIGURE 11 (a) - (c) and FIGURES 14-20 described below) is constructed of a silicon-based material. Those skilled in the art will recognize the convenience of using such material in the preferred techniques of my romaquinado. The device in FIGURE 11 (a) (and FIGURES 34-20 described below) are constructed by the use of surface icromachining of silicon wafers (100), a procedure compatible with IC procedure techniques. The mechanical components of the sensor 100 are made 5 by etching a layer of polysilicon of desired thickness (typically 2-5 microns). The polysilicon layer is deposited on a sacrificial oxide layer of desired thickness that is deposited on the silicon wafer. Only one step of engraving is enough. Other materials, such as nickel, for example, can also be used instead of polyester. Specifically, with reference to FIGS. 12 (a) -c1) and 13a) - (c), the micromachine accelerating latches may be surface-mounted using surface micromachining procedures of either polysilicon or nickel. As for FIGURES I2 (a) - (c), the technique of micromachined polyphonic super fi cial 3 with a silicon wafer with films denvadas de d? Ó <;? d silicon 81? and pol i silicon 82 (FIGURE 12a)). Polysilicon < "> is then etched using etching techniques by reactive ions and photolithography (FIGURE I2IB).) The acceleration link 100 which includes a test mass is then released into hydrochloric acid, leaving suspended plates 301 and associated beams Now, with reference to FIGS. 13 (a) - (c), the nickel surface micro-machining technique starts with a silicon wafer with silicon dioxide and polysilicon 940 films (FIG. FIGURE 13 a) After a photolithography step, the deposit of a photosensitive protective substance 930 is applied and nickel is applied (FIGURE 13 (b)). The photosensitive protective substance is then removed and the sacrificial polysilicon layer is removed. in a piara acid, engrave silicon (for example, potassium hydroxide), leaving suspended plates 101 and associated beams (Fig. 3). In a further embodiment, as shown in FIG. 1RA, sensor 100 is immune to stresses. elera ions in directions other than a selected address of interest. The lOSa-d seals prevent the plate from moving in other directions than in the 3rd direction of detection. E3 silicon substrate and retainer 1 9 prevent the displacement of the plate 301 of the t-axis perpendicular to the plane, or surface, of the plate 103. The retainer 109 requires of the romaqui nado its r fa lial e l-polisi licio for s «? manufactures ion. In addition, the _-ensor 3"_, modJ fi in a additional mode to detect the ions in two directions * - as shown in FIGURE 15. The sensor 100 in FIGURE 15 is one identical configuration to sensor 300 of FIGURE ll (a) -cyc) but for the inclusion of an additional latching mechanism comprising components 103 '-106' to allow bipolar engagement 1. It will be noted that the components 103'-106 'operate in a manner identical to the components previously illustrated 103-106. The engagement arrangement illustrated in FIGURE 36 represents a further embodiment of the invention. As shown, the gate 101 is the resilient cantilever 113 until the cantilever 111 passes over the projection 110 to engage upon detecting a predetermined acceleration. FIGURE 17 shows another embodiment of a hooking accelerometer in accordance with the present invention. As shown, two plates, or test masses, 120 and 140 are employed to avoid any frictional contact between the molten part, or member of male engagement, 325 of plate 120 and fan-shaped end 130 of cantilever 135. Plate 140 is employed to pull fan-shaped end 130 away from it when both plates 120 and 140 are subject to redeemed acceleration. The natural frequencies of the two understood plates 120 and 140 are chosen such that the engagement is performed without the extended portion 325 d of the plate 12 < "Pushing against the fan-shaped fan 13. The acceleration couplings described in FIGURES 11 (a) -17 are flat engagement devices, ie, the hooking is performed in the plane of the silicon wafer. and the test mass 103, as shown in FIGURE 18). The out-of-plane acceleration latches engage perpendicular to the silicon wafer and the test mass 101, as shown in FIGURE 18 (b > Vanos di positivos, including both plane type devices out of plane, can be included in the same plate to detect acceleration in the X, Y and Z. However, bulk microto socks (110), as for example the aforementioned Ciarlo device, can incorporate only the acceleration detection (in plane in the X and Y direction) on the same platelet. An off plane coupling 100 similar to the hooks in the plane is shown in FIGURE 19. More specifically, the coupling overhang 150 splices the test mass 101, which consists of the first layer of poly silicon and / or a layer metal, as shown. When the test mass 101 is subjected to an acceleration in the out-of-plane direction, perpendicular to the surface of the test mass 101, a test is generated in the coupling cantilever 350, which is anchored on the substrate, causing its deviation in the direction out of plane. This deflection of the tip 155 of the vertical cantilever will also result in a horizontal / plane deviation. Once the deviation in the plane is greater than the splice, the vortex v ga 150 is capped from the test mass 101 and latched below. The out-of-plane hitch is conveniently manufactured using micromachining techniques of the 1-palisilicon surface. In addition, when the existing bulk shaker jacking (110) of FIGURE 21 can not be repositioned, which means that it can not be disengaged and reused, a reset mechanism, as will be described with reference to FIG. 20, is conveniently micronized. icionally in the micromaqu acceleration hitch. on the surface of the present invention. It will be noted that this similar reset mechanism can be incorporated in the same manner in the devices for hooking in the plane. It will also be noted that alternative replacement schemes incorporating thermal, bimetallic and piezoelectric principles will be readily apparent to those skilled in the art upon reading the present. FIGURE 20 shows a top view of an out-of-plane engagement acceleration sensor in accordance with the present invention incorporating a reset mechanism 170. The reset mechanism 17 comprises an electrostatic comb drive 175 as shown in FIGURE 20. 20. To reposition the slider 100, the electrostatic comb action 175 is increased. A potential difference is found in the electrostatic comb actuator 175 to allow the test mass 303 to be moved away from the hooked cantilever 150. This remoteness is relatively easily achieved. When the test mass 101 moves away from the cantilever 150 at a distance greater than the splice distance, the cantilevered cantilever 150 can be disengaged and consequently repositioned to its original position in such a way that the sensor can be used again. Additionally, they can manufacture g-second devices using the surface micromachined accelerometers described here. A g-second device is different from a conventional accelerometer in the mechanism in that it responds to a combination of the magnitude of acceleration and the temporal duration in which the acceleration is maintained. An alternative way to consider this device is as a speed hitch since the device responds efficiently to the area ba or the acceleration / time curve. A viscous equalization is used to achieve this catheter. By properly selecting the dimensions of the positive through modeling and the effective use of viscous damping, it is possible to achieve g-second requirements for temporary addresses of these vain tens of seconds. Any of the sensors described in connection with this invention in Figures 1-20 are useful as a single micromechanical sensor and when other sensors are used in combination with openings, they can be employed as a detection system. More particularly, two modes of operation according to the present invention can be achieved: Boolean mode and quasi-continuous mode. The mode of operation of Boale, using a sensor 10, answers the real question / f lso: '. the pre-established end was exceeded7. On the other hand, the almost continuous mode of operation, which employs several sensors, indicates the range of extremes to which the system was exposed. detection, not only and a single end is exceeded. A system used in the almost continuous mode indicates the real extremes to which the system was exposed by using a set of sensors 10 that achieve the Boolean function individually, as described above. To each device in the set I detect to a drent end in specific increments. For example, 4 Boolean-type sensors that detect extremes of increments of 10ßCC100 °C, 110ßC, 120 °C, and 130 °C can be used. If the maximum extreme temperature at which it was exposed, this set was 125 ° C, then the sensors of J, 130 ° C and 12 ° C will indicate that its; The temperature drop has been exceeded. However, the sensor 130QC will not indicate the temperature extreme 125 ° C, therefore, the quasi-continuous micromechanical memory sensor system will indicate that an exposed extreme temperature between 120 ° has occurred. > C and 130 ° C. Further examples in terms of acceleration and pressure will not be specifically described. However, those skilled in the art will note that the quasi-continuous corresponding systems for acceleration and pressure are readily apparent upon reading the present. A further significant advantage of the present invention is that not only can single sensors be fabricated in a single substrate, but typical sensor openings can be fabricated in a single substrate. Accordingly, for example, a temperature sensor, acceleration sensor and pressure sensor can be fabricated on the same substrate to produce a multi-purpose device. The practical application of the present invention extends beyond the detection technology described. The invention can also be used as an electrical switch in certain applications. The foregoing description merely provides a presentation of particular embodiments of the invention and is not intended to limit said invention. As such, the invention is not limited to the modalities described above. It is recognized that one skilled in the art could devise alternative modalities that fall within the scope of the present invention.

Claims (31)

1. 58 CLAIMS 1. A micromechanical sensor that compensates: an induced mechanical coupling when detecting a threshold value of a variable condition; a reading mechanism for detecting whether the hitch member is engaged; and a resetting mechanism that electrically disengages the latching member so that the mechanically latched sensor is electrically repositioned for rep >use; et? do.
2. 2. The sensor of claim 1, wherein the variable condition is the ambient temperature.
3. 3. The rei indication sensor 1, where the variable condition is acceleration.
4. 4. The sensor of claim 3, wherein the variable condition is the pressure, 5, a romechanical memory sensor i comprising: a hooking member that is mechanically engaged upon detecting an e; temperature range predetermined; and a reading mechanism that facilitates the detection of whether the engaging member is engaged. 6. A micromechanical memory sensor comprising: a latching member that is mechanically engaged upon sensing a predetermined pressure end; and a reading mechanism that facilitates the detection of whether the latching member is engaged, 7. A micromechanical memory sensor comprising: a latching member that is mechanically engaged upon sensing a predetermined acceleration end; a reading mechanism that facilitates the detection of whether the engagement member is engaged; and a resetting mechanism that electrically disengages the latching member where the mechanically engaged sensor is only electrically repositioned for repeated use. 8. A micromechanical memory sensor comprising: a first beam supported at a first end by a substrate and having a second end; and a second beam supported at a first end by a substrate and having a second beam having a greater flexibility than the first beam, the first beam and the second beam being placed in a first arrangement of such an; the second beam engages a first surface of the first beam in the second e; of the first beam, an increase in ambient temperature that facilitates a first deflection in the first beam and a second deflection, greater than the first deflection, in the second beam in accordance with the difference in flexibility between the first beam and the beam. second beam, and, a decrease in the ambient temperature which facilitates the movement of the first beam and of the second beam towards a second arrangement, the second beam is engaged on a second surface of the first beam in the second arrangement in such a way that The second beam is hooked on the first beam. The sensor of claim 8, wherein the first beam comprises a heating resistor which, when an electric current is applied, facilitates a third deflection in the beam beam, the third deflection is greater than the first deflection, to disengage the beam. second surface from the second beam to cause the 3rd electric current to cease and cause the first beam and the second beam to return to the first array. 10. A mymechanical memory sensor comprising: a first beam formed of a first material having a first thermal coefficient of epansion and a second material having a second thermal coefficient of expansion, the second coefficient being different from the ppmer coefficient, the The first material and the second material are placed in layers having a terminal end and formed in a substrate, the substrate extending beyond the terminus; and a second beam having a greater flexibility of the first beam placed in a first arrangement in such a way, that the second beam opposes a first surface of the substrate, the second beam is formed of the first material and the second material, an increase in ambient temperature facilitates a first deflection in the first beam and a second deflection, greater than the first deflection, in the second beam in accordance with the difference between the first coefficient and the second coefficient and the flexibility of the first beam and the second beam, and a decrease in ambient temperature which facilitates the movement of the first beam and the second beam towards a second array, the second beam engaging a second substrate surface in the second array in such a way that the second beam Beam is hooked on the first beam. 11. The sensor of claim 10, wherein the first beam comprises a heating resistor which, when an electric current is applied, facilitates a third deflection of the first beam, the third deflection being greater than the first deflection, to disengage. Second surface from the second beam to cause the electric current to stop and cause the first beam and the second beam to return to their first array. 12. An icromechanical memory sensor comprising: a first beam having a first length placed along a length of 1 in, the first beam being formed of a first material having a first thermal coefficient of expansion and a second material having a second thermal coefficient of expansion, the second coefficient being different from the first coefficient, the first material and the second material are placed in layers having a terminal end and formed in a substrate, the substrate extending beyond the terminal end; and a second beam having a second length greater than the first length placed along the longitudinal axis such that in a first arrangement the second beam engages a first surface of the substrate, the second beam being formed from the first material and of the second material, an increase of the ambient temperature that facilitates a first deviation in the first v ga and in the second deflection, greater than the first deflection, in the second beam in accordance with the difference between the first coefficient and the second coefficient in the first beam and in the second beam 3c.ng of the first beam and the second beam, a decrease in the ambient temperature which facilitates the movement of the first beam and of the second beam towards a second arrangement, the second beam engaging on a second surface of the substrate in the second arrangement such that 13 second beam is engaged in the first beam, and an electrical power supply a to the second material of the first beam that facilitates a third deflection of the first beam, the third deflection being greater than the first deflection, to disengage the second surface of the second beam to cause suspension of the electric current and cause the first beam and second beam return to the first array. 13, A micromechanical system of detection comprising: several icromechanical memory sensors, each sensor comprising: a first beam having a first length placed along a longitudinal axis, the first beam is. formed of a first material that has? n first thermal coefficient: a of expansion and a second material that has a second thermal coefficient of expansion, the second coefficient is different from the first coefficient, the first material and the second material are placed in layers that have a terminal end and which are formed in a substrate, the substrate extends beyond the end 1 end; and a second beam having a second length greater than the first length placed along the longitudinal axis such that, in a first arrangement, the second beam opposes a first surface of the substrate, the second beam is formed from the first material and the second material, an increase in ambient temperature to a predetermined temperature that facilitates a first deflection of the first beam and a second deflection, greater than the first deflection, in the second beam in accordance with the difference between the first coefficient and the second coefficient and between the 3rd first length and the second length of the first beam and the second beam, the predetermined temperature is different for each sensor, and a decrease in the ambient temperature that facilitates the movement of the first beam and the second beam beam towards a second array, the second beam engaging on a second surface of the substrate in the second array in such a way that the second beam is hooked on the first v. The system of claim 13, wherein the first beam of each sensor comprises a heating resistor which, when a supplied electrical current is applied, facilitates a third deflection in the first beam, the third deflection being greater than the first deflection , to disengage the second surface from the second beam to cause the suspension of the electric current and cause the first beam and the second beam to return to the first array. 15. A micromechanical memory sensor comprising; a first beam supported at a first end and having a second free end; a second beam supported at a first end and having a second free end, the second end of the second beam splices the second end of the first beam, and the second end of the second beam has a test mass extending from thence in a first direction, the movement of the test mass in the first direction caused by an acceleration to which the sensor is subjected doubles the second beam to engage under the first beam if a predetermined level of acceleration is reached; a reading mechanism to detect if the sensor is stuck; and a resetting device for electrically disengaging the first beam and the second beam. 16. A my memory romecam sensor comprising: a rectangular plate having four corners and sides; a male engaging member extending from a first side of the plate; bent beams, each connected to one end of one of the four corners to support the plate and at a second end to electric dimming; a female engaging member in relation opposite to the male engaging member; the acceleration of the plate in a first direction towards the female engagement member causes a deflection of the bent beams to facilitate the movement of the male engagement member towards the female engagement member and the subsequent engagement thereof to allow the movement of the member of the coupling member. engaging male in the first direction and preventing movement of the male engaging member in a second direction opposite the first direction. The sensor of claim 16 further comprising a first detent opposed to a second side of the plate, a second detent opposed to a third side of the plate, and a third detent opposed to a fourth side of the plate to allow the movement of the plate only in the first 18. The sensor of claim 16, wherein the female latching member comprises a second rectangular plate having an extension corresponding to the male engaging member, the second p 3 here and the extension being deviated to accelerate in the first direction. . The sensor of claim 16 further comprising: a second male engaging member extending from a second parallel side of the plate; a second female engaging member in opposed relation to the second male engaging member; the acceleration of the plate in the second direction towards the second female engagement member causing a second deflection of the bent beam to facilitate movement of the second male engagement member towards the second female engagement member and the subsequent engagement thereof to allow movement of the second male engaging member in the second direction and preventing movement of the male engaging member in the first direction. 20. The sensor of claim 16 further comprising a reset mechanism. 21. The sensor of claim 20, wherein the reset mechanism comprises a rhematic tooth comb. 22. The sensor of claim 17 further comprising an electrical repositioning mechanism. 23. The sensor of claim 18 further comprising an electrical reset mechanism. 24. The sensor of claim 19 further comprising an electrical reset mechanism. 25. A micromechanical memory sensor comprising: a rectangular plate having four corners and sides; bent beams, each connected to one end of one of the four corners to support the plate and at a second end to electrical attenuators; a projection that extends from one side of the plac; a resilient cantilever perpendicular to the side aligned with the projection, a first end of the cantilever splices a first side of the projection and is positioned at a predetermined distance from the projection in the first di rece ion; the acceleration of the plate in a first direction perpendicular to the cantilever that causes a deflection of the bent beams to facilitate e3 movement of the projection in the first direction to engage and deflect the cantilever in such a way that the cantilever engages a second side of the projection to allow movement in the first direction and prevent movement in a second direction opposite to the first direction. 26, The sensor of claim 25 further comprising a repositioning mechanism. 27. A micromechanical sensor comprising: a rectangular plate having four corners, sides, a first surface, and a second surface; bent beams, each at one end of one of the four corners to support the plate and at a second end to electrical attenuators; a cantilever having one end, the cantilever is positioned perpendicular relative to a first side of the plate and the splice end of the plate such that the cantilever opposes the first surface; the acceleration of the plate in a first direction perpendicular to the surfaces of the plate causes a deflection of the bent beams to facilitate the movement of the plate in the first direction to engage and deflect the cantilever in such a way that the cantilever engages the second surface of the plate. 28. The sensor of claim 27 further comprising a reset mechanism. 29. The re-indication sensor 27, wherein the reset mechanism comprises a foot switch actuator. 3C *. A micromechanical memory sensor comprising: a diaphragm; a first saw in the diaphragm; a second beam in the diaphragm that joins the first beam, a depression of the diaphragm caused by a pressure to which the sensor is subjected, which induces a relative movement between the first beam and the second beam in such a way that the second beam the first beam is hooked if a predetermined level of pressure is reached; and a reading mechanism to detect if the sensor ß is stuck. 31. The sensor of claim 30 further comprising a reset mechanism for electrically disengaging the first beam and the second beam.