Embodiments of the invention include an accelerometer system. The system includes an accelerometer sensor comprising first and second electrode configurations and an inertial mass between the first and second electrode configurations. In one example, the accelerometer sensor being fabricated as symmetrically arranged about each of three orthogonal mid-planes. The system also includes an accelerometer controller configured to apply control signals to each of the first and second electrode configurations to provide respective forces to maintain the inertial mass at a null position between the first and second electrode configurations. The accelerometer controller can measure a first pickoff signal and a second pickoff signal associated with the respective first and second electrode configurations. The first and second pickoff signals can be indicative of a displacement of the inertial mass relative to the null position. The accelerometer controller can calculate an acceleration based on the first and second pickoff signals.

A method for closed loop operation of a capacitive accelerometer includes applying a first drive signal V.sub.1 to a first fixed capacitive electrode and a second drive signal V.sub.2 to a second fixed capacitive electrode the first and second drive signals each having a periodic waveform varying in amplitude between zero and a maximum value V.sub.ref and sensing a displacement of the proof mass and applying pulse width modulation to the first and second drive signals with a constant frequency f.sub.mod and a variable mark/space ratio. The method also includes applying a voltage offset V.sub.ref/2 to the proof mass and applying the pulse width modulation such that the first and second drive signals have a waveform that varies so that when either one of the first and second drive signals is at V.sub.ref or zero the other drive voltage is at V.sub.ref/2.

A moisture detector includes a sensor chip and a moisture determining unit. The sensor chip includes a humidity detector having a detection surface on which to measure humidity, and also includes a heater heating the detection surface, and the moisture determining unit is configured to, after causing the heater to start heating, determine whether moisture is present on the detection surface based on a difference in changes in the humidity measured by the humidity detector.

An example system comprising: a microelectromechanical system (MEMS) vibrating beam accelerometer (VBA) comprising: a proof mass; and a first resonator mechanically coupled to the proof mass; a first electrode configured to apply a force to the proof mass.

Micromechanical device comprising: a semiconductor body; a movable structure configured to oscillate relative to the semiconductor body along an oscillation direction; and an elastic assembly with an elastic constant, coupled to the movable structure and to the semiconductor body and configured to deform along the oscillation direction to allow the oscillation of the movable structure as a function of an acceleration applied to the micromechanical device. The movable structure and the semiconductor body comprise a control structure for the capacitive control of the oscillation of the movable structure: when the control structure is electrically controlled in a first state the micromechanical device is in a first operating mode wherein a total elastic constant of the micromechanical device has a first value, and when it is electrically controlled in a second state the micromechanical device is in a second operating mode wherein the total elastic constant has a second value lower than, or equal to, the first value.

Described herein are accelerometers, apparatus and systems incorporating accelerometers, and techniques for electrostatically adjusting a stiffness of a spring system in an accelerometer. Embodiments featuring resonant and/or quasi-static accelerometers are described. In certain embodiments, an accelerometer is a microelectromechanical systems (MEMS) device including a proof mass, an anchor, a spring attached to the proof mass, a sense electrode, and a tuning electrode. The spring and the proof mass form a spring system suspended from the anchor. The sense electrode is configured to generate a signal indicating movement of the proof mass based on application of a first signal. The tuning electrode is configured to receive an electrostatic tuning signal, the electrostatic tuning signal being separate from the first signal and providing a negative contribution to an overall stiffness of the spring system. The electrostatic tuning signal can be used to adjust the stiffness based on a measured acceleration.

In a MEMS electrostatic capacitor type acceleration sensor, the manufacturing costs of MEMS elements are reduced, and at the same time, the variations of the electrical and mechanical characteristics of the MEMS elements are reduced. A detection circuit generates a voltage signal corresponding to the product of a difference between the two capacitance values of a pair of MEMS capacitors and a servo signal. A modulation circuit outputs a signal corresponding to the difference between the capacitance values using the servo signal. The control circuit outputs the servo signal on the basis of a signal corresponding to the difference between the capacitance values.

A method includes holding a mask using an electrostatic chuck. The mask includes a substrate having a first bump and a second bump separated from the first bump and a patterned layer. The first bump and the second bump face the electrostatic chuck. The substrate is between the patterned layer and the electrostatic chuck. The first bump and the second bump are spaced apart from the patterned layer. The first bump and the second bump are ring strips in a top view, and the first bump has a rectangular cross section and the second bump has a triangular cross section. The method further includes generating extreme ultraviolet (EUV) radiation using an EUV light source; and directing the EUV radiation toward the mask, such that the EUV radiation is reflected by the mask.

A mask includes a substrate, a light-reflecting structure, a patterned layer, and a plurality of bumps. The substrate has a first surface and a second surface. The light-reflecting structure is located on the first surface of the substrate. The patterned layer is located on the light-reflecting structure. The bumps are located on the second surface of the substrate. The bumps define a plurality of voids therebetween and protrude in a direction away from the second surface of the substrate.

The invention discloses a MEMS sensor detection device and a MEMS sensor system, wherein the MEMS sensor detection device comprises: a readout circuit used for analog signal processing of the output signal of the MEMS sensor to generate detection voltage; a cancellation voltage generation circuit used for generating a gravity cancellation voltage according to the detection voltage, wherein the gravity cancellation voltage and the gravity acceleration are in a positive proportional relationship; a selection circuit used for selecting the detection voltage output in a feedback phase and selecting the gravity cancellation voltage output in a gravity cancellation phase, wherein in one detection period, the feedback phase is located after the gravity cancellation phase; and a feedback circuit used for generating a feedback voltage according to the output voltage of the selection circuit, wherein the feedback voltage is in a positive proportional relationship with the output voltage of the selection circuit. The MEMS sensor detection device and the MEMS sensor system disclosed by the invention can cancel the influence of gravity acceleration and improve the sensitivity of the MEMS sensor system.