TWI401975B - Fabrication method of polymer-based vibrating membrane for capacitance micromachined ultrasonic transducers - Google Patents

Description

Capacitive ultrasonic transducer with polymer-based oscillating film manufacturing method

The invention relates to an ultrasonic transducer, in particular to a method for manufacturing a capacitive ultrasonic transducer with a polymer-based oscillating film.

Ultrasonic waves refer to sound waves whose vibration frequency exceeds the range that can be heard by the human ear. The high-frequency characteristics make them widely used in military, medical, industrial and other fields, and are often used for detection purposes. Ultrasonic detection technology is mainly achieved by using an ultrasonic transducer (Ultrasonic Transducer), which uses the transmission and reception of sound waves to measure physical quantities such as position and velocity.

Conventional ultrasonic transducers are mostly piezoelectric ultrasonic transducers, but due to their limited sensing environment, they have gradually been replaced by capacitive ultrasonic transducers. Capacitive ultrasonic transducers mainly use a fixed electrode and an electrode with a oscillating film to form a capacitive structure. When an AC voltage is applied, the high-frequency vibration of the film can be driven to generate ultrasonic waves.

In the method of manufacturing a polymer-based capacitive ultrasonic transducer according to the Patent Publication No. 1260940 of the Republic of China, a method for manufacturing a capacitive ultrasonic transducer in a single program is proposed, which can greatly reduce the micromachining process. Time, and improve the processing temperature, high residual stress, and process characteristics of the conventional capacitive ultrasonic transducer manufacturing method is difficult to grasp and high cost.

However, such a process method must first form a metal sacrificial layer in the manufacturing process, and then remove the metal sacrificial layer by wet etching to form a vibrating cavity, and provide a hole through which the etching liquid flows, but it is not easy to seal the hole and serve as an electrode. The conductive layer is easily oxidized by water vapor, so the use environment is still limited by the atmospheric state, and cannot be extended to the underwater environment, so that the process method still needs to further solve the problem.

It can be seen from the above description that although the prior art has a method for manufacturing a capacitive ultrasonic transducer in a single program, there is a problem in that the etching hole is not easily sealed after the cavity structure is formed through the sacrificial layer, so that the etching hole is not easy to be sealed. The range of use of molecular-based capacitive ultrasonic transducers is limited.

In view of the above, the main object of the present invention is to provide a method for fabricating a capacitive ultrasonic transducer having a polymer-based oscillating film, which comprises a film bonding method for fabricating a vibrating film of an ultrasonic transducer without etching. Holes, so there is no problem that the etching holes are not easy to seal, so that the application range of the polymer-based capacitive ultrasonic transducer can be extended to the underwater environment.

In order to achieve the above object, the technical means adopted by the present invention mainly comprises the method for manufacturing the capacitive ultrasonic transducer having the polymer-based oscillating film, comprising a plurality of processes: a polymer-based film production process, comprising the steps of: Providing a transparent substrate; coating a polymer material layer on the transparent substrate; and continuously maintaining the polymer material layer in an adhesive state by temperature control; and a support base manufacturing process comprising the steps of: providing a substrate; a conductive layer is disposed on the substrate; and a support base is formed on the lower conductive layer; and a transducer manufacturing process includes the steps of: pressing the polymer material layer and the support seat together; curing the chain a polymer material layer and a support; removing the transparent substrate; and forming an upper conductive layer on the polymer material layer.

Through the above-mentioned several processes, the fabrication of the capacitive ultrasonic transducer can be completed. Since the manufacturing method separately forms the polymer-based film and the support base, and then combines the two to form a cavity structure by the pressure-bonding method, It is necessary to make an etched hole, and naturally there is no problem that the etched hole is difficult to seal.

Referring to the first figure, the manufacturing method of the capacitive ultrasonic transducer with the polymer-based oscillating film of the present invention comprises a polymer-based film production process (1), a support base production process (2), and a The transducer production process (3) and the like are several processes, wherein the polymer-based film production process (1) and the support base production process (2) are independently performed without any order limitation.

Regarding the polymer-based film production process (1), as shown in the second figure, the production process includes the following steps: providing a transparent substrate (10) (100), which can be selected from transparent A glass, a silicone resin, a resin, a plastic, a polyester, a photoresist, and a polymer material are alternatively prepared; a polymer material layer (11) (101) is coated on the transparent substrate (10), The polymer material layer (11) has a thickness of 10 μm or less. In the present embodiment, the polymer material layer (11) is a photosensitive polymer material layer, which can be a SU-8 photoresist; and the temperature control continues. The polymer material layer (11) is brought into an adhesive state (102), wherein it is preferable to control the temperature of the polymer material layer (11) to be between 60 degrees Celsius and 100 degrees Celsius, and the glass transition temperature is not reached. The solvent of the polymer material layer (11) is volatilized under the conditions.

Regarding the support manufacturing process (2), please refer to the third and fourth figures at the same time, the production process includes the following steps: providing a substrate (20) (200), in the embodiment, the substrate ( 20) may be made of at least one material selected from the group consisting of glass, silicone, resin, plastic, polyester, photoresist, polymer material, etc.; forming a conductive layer on the substrate (20) 21) (201), the lower conductive layer (21) is made of a conductive material selected from the group consisting of gold, copper, aluminum, platinum, silver, indium tin oxide, etc.; and the lower conductive layer (21) A support base (22) (202) is formed thereon, and the support base (22) can be formed by a photosensitive polymer material coating lithography process, polymer coating embossing, or screen printing. Regarding the transducer manufacturing process (3), and referring to the fifth to seventh figures, the manufacturing process includes the following steps: pressing the polymer material layer (11) and the support base (22) together ( 300); curing the polymer layer (11) and the support base (22) (301), in this embodiment, the ultraviolet light exposure method, the heating baking method or the two methods are used together to solidify the chain. a polymer material layer (11) and a support base (22); removing the transparent substrate (10) (302); forming an upper conductive layer (30) (303) on the polymer material layer (11), this embodiment The upper conductive layer is formed by one of a method selected from the group consisting of: Screen Printing, Ink-Jet Printer, Lift-Off, or lithography etching. 30), and the upper conductive layer (30) may be made of one of conductive materials selected from the group consisting of gold, copper, aluminum, platinum, silver, indium tin oxide, and the like.

After the polymer material layer (11) is adhered to the support base (22), it can be used as a polymer-based vibration film of a capacitive ultrasonic transducer. After the conductive layer (30) is completed, the capacitive type can be completed. The production of ultrasonic transducers.

Since the manufacturing method separately forms the polymer-based film and the support base, and then combines the two to form a cavity structure by adhesive bonding, it is not necessary to make an etched hole, and naturally there is no problem that the etched hole is not easy to be sealed. The capacitive ultrasonic transducer with the polymer-based oscillating film of the invention can extend the use range to the underwater environment.

(10). . . Transparent substrate

(11). . . Polymer layer

(20). . . Substrate

(twenty one). . . Lower conductive layer

(twenty two). . . Support base

(30). . . Upper conductive layer

First Figure: A flow chart of a preferred embodiment of the present invention.

The second figure is a schematic diagram of the stage product of the polymer-based film production process of the present invention.

Third to fourth figures are schematic views showing the manufacturing process of the support of the present invention.

Fifth to seventh figures are schematic views showing the flow of the transducer manufacturing process of the present invention.

Claims (10)

A method for manufacturing a capacitive ultrasonic transducer with a polymer-based oscillating film, comprising: a polymer-based film manufacturing process, comprising: providing a transparent substrate; coating a polymer on the transparent substrate a material layer; and controlling the temperature of the polymer material layer to be between 60 and 100 degrees Celsius to continuously maintain the polymer material layer in an adhesive state; and a support base manufacturing process, comprising: providing a substrate; a conductive layer is formed thereon; and a support base is formed on the lower conductive layer; and a transducer manufacturing process includes: pressing the polymer material layer and the support base together; and solidifying the polymer layer And a support base; removing the transparent substrate; and forming an upper conductive layer on the polymer material layer. The method for manufacturing a capacitive ultrasonic transducer with a polymer-based oscillating film according to the first aspect of the patent application, wherein in the step of solidifying the polymer layer and the support base, the ultraviolet light exposure method is adopted. The heating baking method or the above two methods are used together to solidify and link the polymer material layer and the support base. The method for fabricating a capacitive ultrasonic transducer having a polymer-based oscillating film according to the second aspect of the invention, wherein the transparent substrate is coated with a polymer material layer on the transparent substrate, The polymer material can be a SU-8 photoresist. The method for fabricating a capacitive ultrasonic transducer having a polymer-based oscillating film according to claim 3, wherein the step of controlling the temperature of the polymer material layer in an adherent state is controlled by the temperature control The temperature of the molecular material layer is between 60 and 100 degrees Celsius. The method for fabricating a capacitive ultrasonic transducer having a polymer-based oscillating film according to any one of claims 1 to 4, wherein the step of forming a support on the lower conductive layer is selected from the group consisting of The photosensitive polymer material is coated with a lithography process, a polymer coating embossing or a frame printing method to form a support on the lower conductive layer. The method for fabricating a capacitive ultrasonic transducer having a polymer-based oscillating film according to any one of claims 1 to 4, wherein the step of forming an upper conductive layer on the polymer material layer is The upper conductive layer is formed by one of a method selected from the group consisting of a frame printing, an ink jet, a photoresist peeling method, or a photolithography etching technique. The method for fabricating a capacitive ultrasonic transducer having a polymer-based oscillating film according to claim 1, wherein the substrate is selected from the group consisting of glass, silicone, resin, plastic, polyester, photoresist, and high Made of at least one of a group consisting of molecular materials and the like. The method for fabricating a capacitive ultrasonic transducer having a polymer-based oscillating film according to claim 7, wherein the transparent substrate is selected from the group consisting of glass, silicone, resin, plastic, polyester, and photoresist. At least one of a group consisting of a polymer material and the like is made of a material. The method for fabricating a capacitive ultrasonic transducer having a polymer-based oscillating film according to claim 7 or 8, wherein the upper conductive layer is oxidized by a metal selected from the group consisting of gold, copper, aluminum, platinum, silver, and indium tin. One of the conductive materials such as materials is made. The method for fabricating a capacitive ultrasonic transducer having a polymer-based oscillating film according to claim 7 or 8, wherein the lower conductive layer is oxidized by a metal selected from the group consisting of gold, copper, aluminum, platinum, silver, and indium tin. One of the conductive materials such as materials is made.