Flexible capacitive micromachined ultrasonic transducer array with increased effective capacitance

A technology of capacitive micromachining and ultrasonic transducers, applied in piezoelectric devices/electrostrictive devices, circuits, electrical components, etc.

Active Publication Date: 2012-06-13
THE HONG KONG POLYTECHNIC UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, when the DC bias is increased above a certain voltage, the electrostatic

Method used

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  • Flexible capacitive micromachined ultrasonic transducer array with increased effective capacitance
  • Flexible capacitive micromachined ultrasonic transducer array with increased effective capacitance
  • Flexible capacitive micromachined ultrasonic transducer array with increased effective capacitance

Examples

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Example Embodiment

[0053] Reference Figure 8 to 10 , A capacitive micromachined ultrasonic transducer (CMUT) 200 with a bottom electrode 240 in a concave shape is shown. The recessed air chamber 230 is defined by the recess of the bottom electrode 240. Go to Figure 8 , The top electrode 210 covers 100% of the area 260 of the membrane 220 above the air chamber 230. Therefore, the effective capacitance of CMUT 200 can be significantly higher than figure 1 The effective capacitance of the conventional CMUT (which has the top electrode 110 covering only 25% of the film area 120).

[0054] Go to Picture 9 When a direct current (DC) bias is applied, the entire area 260 of the membrane 220 above the air chamber 230 is considered to generate an effective capacitance. The concave portion of the bottom electrode 240 basically matches the deflection of the film 220 when a DC bias is applied.

[0055] If the bottom electrode 240 defines a concave shape or a curved profile, when the membrane 220 flexes, th...

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Abstract

A Capacitive Micromachined Ultrasonic Transducer (CMUT) (200) comprises a membrane (220) operatively connected to a top electrode (210) and a bottom electrode having a concave void (230). When a Direct Current (DC) bias voltage is applied, the membrane (220) is deflected towards the bottom electrode so that a peripheral edge region of the membrane (220) is closer to the bottom electrode and an electrostatic force proximal to the peripheral edge region of the membrane (220) is increased.

Description

technical field [0001] The present invention relates to an improved capacitive micromachined ultrasonic transducer (CMUT) and a method for manufacturing the CMUT. Background technique [0002] Figure 1 to Figure 3 The conventional operating principle of a capacitive micromachined ultrasound transducer (CMUT) 100 with a flat bottom electrode 140 is shown. [0003] refer to figure 1 , the CMUT 100 is similar to a parallel plate capacitor with a top electrode 110 on a dielectric film 120 isolated from a bottom electrode 140 by a vacuum or air chamber 130 . The bottom electrode 140 is generally formed on a flat conductive substrate. The top electrode 110 and the bottom electrode 140 may be made of a conductive material such as a conductive silicon substrate. The thin film 120 is made of or coated with a conductive material. When actuated by electrostatic force using an alternating voltage, the membrane 120 can vibrate like an eardrum to generate ultrasound. Thus, the CMUT...

Claims

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Application Information

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IPC IPC(8): H01L41/08H01L21/02
CPCB06B1/0292
Inventor 郑庆祥钞晨
Owner THE HONG KONG POLYTECHNIC UNIV
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