Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B81—MICROSTRUCTURAL TECHNOLOGY
  • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
  • B81B3/00—Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
  • B81B3/0018—Structures acting upon the moving or flexible element for transforming energy into mechanical movement or vice versa, i.e. actuators, sensors, generators
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L1/00—Measuring force or stress, in general
  • G01L1/005—Measuring force or stress, in general by electrical means and not provided for in G01L1/06 - G01L1/22
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B81—MICROSTRUCTURAL TECHNOLOGY
  • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
  • B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
  • B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
  • B81C1/00023—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems without movable or flexible elements
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L1/00—Measuring force or stress, in general
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L7/00—Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements
  • G01L7/02—Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements in the form of elastically-deformable gauges
  • G01L7/08—Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements in the form of elastically-deformable gauges of the flexible-diaphragm type
  • G01L7/082—Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements in the form of elastically-deformable gauges of the flexible-diaphragm type construction or mounting of diaphragms
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
  • G01L9/0041—Transmitting or indicating the displacement of flexible diaphragms
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
  • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
  • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
  • G01P15/12—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by alteration of electrical resistance

Definitions

• Microelectromechanical sensor for measuring a force and corresponding method
• the invention relates to a microelectromechanical sensor for measuring a force, a pressure or the like, to a corresponding method and to a corresponding production method.
• Microelectromechanical systems now have a great economic
• microelectromechanical sensors which are used as acceleration and pressure sensors, especially in the consumer and automotive sectors.
• Such pressure sensors are based on essentially the same functional principle:
• a pressure difference leads to a deformation of a membrane in the pressure sensor. This deformation of the membrane, which is proportional to the pressure difference, is measured.
• two corresponding methods for the evaluation are already known:
• the membrane is designed such that a capacitance changes due to the membrane deformation.
• the corresponding capacity change is detected and the pressure difference or the corresponding pressure is then calculated on the basis of this capacity change.
• the second method of evaluation is based on the so-called piezoresistive effect.
• On or in the corresponding membrane piezoresistors are arranged.
• a voltage is then applied to the piezoresistors.
• One Pressure sensor based on the piezoresistive effect has become known for example from DE 10 2008 033 592 A1.
• the microelectromechanical sensor for measuring a force, a pressure or the like defined in claim 1 comprises a substrate with a measuring element, wherein the measuring element comprises at least two electrically conductive regions, wherein at least one of the electrically conductive regions is at least partially connected to the substrate, and at least a change region, wherein the change region is at least partially disposed between the electrically conductive regions, wherein the change region is formed in an unloaded state substantially electrically insulating and is formed in the loaded state substantially electrically conductive.
• microelectromechanical sensor according to at least one of claims 1 to 6 comprises the steps
• the method defined in claim 8 for producing a microelectromechanical sensor comprises the steps
• microelectromechanical sensor defined in claim 1 the method defined in claim 6 and the method for producing a microelectromechanical sensor defined in claim 8 have the advantage that a
• Microelectromechanical sensor can be produced inexpensively, at the same time is less susceptible to interference and can be used in a wider temperature range. In addition, the microelectromechanical sensor or the corresponding method has a higher accuracy.
• Change range a thickness of less than 25 nanometers, in particular less than 10 nanometers, preferably less than 5 nanometers in the unloaded state.
• Sensitivity of the microelectromechanical sensor is correspondingly high while high accuracy. If the thickness of the alternating region decreases as a result of an indirectly acting force, the tunnel barrier becomes smaller and the probability of tunneling through electrons increases; the tunneling current through the alternating range increases in particular exponentially.
• microelectromechanical sensor can be provided with an electrically insulating layer in a simple and cost-effective manner.
• this includes
• Measuring element a plurality of alternately arranged electrically conductive areas and alternating areas.
• the advantage here is that it further increases the sensitivity and accuracy of the microelectromechanical sensor, for example if several of the regions are arranged one above the other in such a way.
• the microelectromechanical sensor comprises a membrane which has in each case one measuring element on at least two, in particular four, adjacent sides. The advantage here is that the sensitivity and accuracy of the microelectromechanical sensor can be increased even further, for example, the measured values of the respective measuring elements can be used to average a force or pressure measurement.
• the determination of the force, the pressure or the like takes place on the basis of a monotonous, in particular exponential, course of the electrical variable.
• FIG. 1 is a schematic diagram of an operation of a microelectromechanical sensor according to a first embodiment
• FIG. 2 is a schematic diagram of a microelectromechanical sensor according to a second embodiment of the present invention
• FIG. 3 shows a schematic representation of a microelectromechanical sensor according to a third embodiment of the present invention
• FIG. 4 shows a schematic representation of a microelectromechanical sensor according to a fourth embodiment of the present invention
• Fig. 5 steps of a method for producing a microelectromechanical sensor according to the first embodiment of the present invention
• Fig. 6 steps of a method according to the first embodiment.
• FIG. 1 shows a schematic diagram of the operation of a microelectromechanical sensor according to a first embodiment.
• reference numeral 1 denotes a measuring element of a microelectromechanical sensor.
• the measuring element 1 comprises a lower electrically conductive region 2a and an upper electrically conductive region 2b with a substantially rectangular cross-section. Between the two electrically conductive regions 2a, 2b is a
• Changing region 3 is arranged, which also has a substantially rectangular cross-section.
• the thickness D of the alternating region 3 is measured in accordance with FIG. 1 in the vertical direction.
• the lower electrically conductive region 2 a and the upper electrically conductive region 2 b are connected to a voltage source 5, as well as to an ammeter 4 for a tunnel current 4 through the electrically conductive regions 2 a, 2 b and the changeover region 3
• Reduced thickness D of the change region 3 the tunnel current 4 flowing between the conductive regions 2a, 2b increases exponentially according to the curve V of Fig. 1 b.
• the tunnel current 4 is thus plotted over the thickness D of the alternating region 3.
• V is exponential
• the scales of the abscissa and the ordinate are linear.
• the tunnel current according to FIG. 1 b has the size 0.67, whereas it has a thickness D of 6
• Nanometers has the value 0, 1.
• the tunnel current 4 is provided with any unit.
• FIG. 2 shows a schematic diagram of a microelectromechanical sensor according to a second embodiment of the present invention.
• FIG. 2 a shows a measuring element 1 of a microelectromechanical sensor, this essentially corresponds to FIG Structure of the measuring element 1 according to FIG. 1a.
• a substrate 7 on which the electrically conductive region 2 a is arranged.
• a substantially T-shaped force stamp 6 is arranged on the electrically conductive region 2b.
• the power punch 6 is not acted upon by a force.
• Changing region 3 can now flow through the voltage applied to the electrically conductive regions 2a, 2b, a larger tunneling current 4 through the alternating region 3 located between the electrically conductive regions 2a, 2b.
• Tunnel current 4 can then be determined acting on the force stamp 6 force F.
• FIG. 3 shows a schematic representation of a microelectromechanical sensor according to a third embodiment of the present invention.
• FIG. 3 a shows a measuring element 1 of a microelectromechanical sensor.
• the structure of the measuring element 1 corresponds substantially again to the corresponding structure according to FIGS. 1 and 2.
• the lower first electrically conductive region 2 a is opposite to the alternating region 3 and the second electrically conductive region 2 b according to FIG. 3a arranged offset in the horizontal direction to the right.
• the first electrically conductive region 2 a is connected to a substrate 7.
• the substrate 7 further includes a bendable portion 7a in which a neutral fiber 7b is disposed.
• the change region 3 is at least partially connected to the substrate 7 on its left side, whereas the first electrically conductive region 2a is connected to the substrate 7 on the right side.
• the first electrically conductive region 2 a and the second electrically conductive region 2 b are connected to a voltage source 5 and to a measuring device M for the tunneling current 4.
• a pressure above the electrically conductive portion 2b is equal to a pressure p 2 below the bendable portion 7a.
• the bendable region 7a can be
• the electrically conductive regions 2a, 2b and the change region 3 are arranged horizontally and parallel to one another.
• the measuring device M for the tunneling current 4 measures a certain size of one by the electrically conductive regions 2a, 2b as well as through the alternating region 3 flowing tunnel current 4th
• the pressure p 1 above the electrically conductive region 2 b is now greater than the pressure p 2 below the bendable region 7 a of the substrate 7 and thus also below the electrically conductive region 2 a . Accordingly, the bendable region 7a, the neutral fiber 7b, the electrically conductive regions 2a, 2b and the alternating region 3 according to FIG. 3b are bent downwards. As a result of the higher pressure p 1 on the upper side of the electrically conductive region 2 b, the electrically conductive regions 2 a, 2 b as well as the alternating region 3 undergo compression in the substantially horizontal plane of the membrane or bendable region 7 a. Based on these
• the electrically conductive regions 2a, 2b and the alternating region 3 are stretched in the direction perpendicular thereto.
• the thickness D of the change region 3 increases and as a result the tunnel current 4 decreases. In this way, the pressure or the pressure difference can be determined.
• FIG. 4 shows a schematic representation of a microelectromechanical sensor according to a fourth embodiment of the present invention.
• the microelectromechanical sensor has four measuring elements 1 a, 1 b, 1 c, 1 d.
• Measuring elements 1 a, 1 b, 1 c, 1 d correspond in construction respectively to the measuring element 1 of Fig. 1.
• the arrangement of the four measuring elements 1 a, 1 b, 1 c, 1 d is as follows: In Fig. 4a is on the left and A part 7 ', 7 "of a substrate 7 is shown on the right-hand side, and a gap 8 is arranged between the two parts 7', 7" of the substrate 7.
• the measuring element 1b is now arranged on the left-hand part of the substrate 7 ', the first electrically conductive region 2a being arranged on the left-hand part 7' of the substrate.
• the measuring element 1c is arranged on the right-hand part 7 "of the substrate 7.
• the respective lower conductive electrical regions 2a of the measuring elements 1b, 1c are designed to be larger than the respective ones in terms of their horizontal extent
• the measuring elements 1 b, 1 c extend partially into the gap 8 inside.
• a membrane 9 is arranged, which is connected to the electrically conductive regions 2b of the measuring elements 1 b, 1 c.
• the membrane 9 in this case has a bendable region 9a and comprises in its interior a neutral fiber 9b.
• Membrane 9 extends completely from left to right, ie from the left part 7 'to the right part 7 "of the substrate 7. At the respective left and right End regions of the membrane 9 on its upper side are now the other two
• Measuring elements 1 a, 1 d arranged.
• the first electrically conductive regions 2 a of the measuring elements 1 a, 1 d are connected to the membrane 9.
• the measuring elements 1 a, 1 d extend in turn partially into the gap 8 between the two parts 7 ', 7 "of the substrate 7.
• the horizontal extent of the measuring elements 1 a, 1 d each smaller than the horizontal extent of the measuring elements 1 b
• the membrane 9 is likewise arranged such that it is only partially connected to the second electrically conductive regions 2b of the measuring elements 1b, 1c.
• the corresponding pressure situation according to FIG. 3b is shown in FIG the pressure above the diaphragm 9 is greater than the pressure below the diaphragm 9.
• the diaphragm 9 is pressed downwards by the pressure difference as shown in Fig. 4a are respective voltages 5 correspondingly applied to the respective measuring elements 1a, ab, 1c, 1d applied as shown in Fig. 1, a decrease in the tunneling current 4 in the measuring elements 1 a, 1 d is measured, whereas the tunneling current 4 in the
• Measuring elements 1 b, 1 c increases compared respectively with the flowing through the measuring elements 1 a, 1 b, 1 c, 1 d tunnel currents 4 at undeflected membrane 9, or if there is no pressure difference between the top and bottom of the membrane 9.
• Fig. 4b is an interconnection of the measuring elements 1a, 1 b, 1 c, 1 d in the form of a
• Fig. 5 shows steps of a method for producing a microelectromechanical
• the first electrical region 2a is formed by a silicon wafer 2a, on which a native oxide layer 10 is arranged, and this native oxide layer 10 is now removed in the next step according to FIG. 5b, for example by means of hydrofluoric acid, in accordance with FIG Fig. 5b only the silicon wafer 2a remains.
• an ultrathin layer of silicon dioxide is used as the changeover region 3 on this silicon wafer 2 a applied (step ⁇ ), for example by thermal oxidation.
• T 2 according to FIG.
• a further electrically conductive layer 2 b of silicon is then applied, for example by means of a chemical vapor deposition process of a silicon-containing base material and in a further step T 3 of the layer stacks 2 a, 3, 2 b applied to a substrate 7.
• FIG. 6 shows steps of a method according to the first embodiment.
• FIG. 6 shows a flow diagram of a method for measuring a pressure, a force or the like:
• a first step S 1 an electrical quantity is measured.
• a further step S 2 the changing region is deformed due to a force, a pressure or the like.
• the electrical variable is measured in the loaded state.
• the force, the pressure or the like is determined on the basis of the measured electrical variable.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Computer Hardware Design (AREA)
• Measuring Fluid Pressure (AREA)
• Pressure Sensors (AREA)

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• 2010
  • 2010-11-03 DE DE102010043277A patent/DE102010043277A1/de not_active Withdrawn
• 2011
  • 2011-09-21 US US13/882,767 patent/US9021898B2/en not_active Expired - Fee Related
  • 2011-09-21 WO PCT/EP2011/066393 patent/WO2012059266A1/de active Application Filing
  • 2011-09-21 EP EP11769813.4A patent/EP2635884A1/de not_active Withdrawn
  • 2011-09-21 CN CN2011800528712A patent/CN103180705A/zh active Pending

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