METHOD FOR MANUFACTURING FILM BULK ACOUSTIC RESONANCE DEVICE HAVING SPECIFIC RESONANT FREQUENCY

A method for manufacturing a film bulk acoustic resonance device is disclosed. The proposed method, wherein the device has a specific resonant frequency, includes: providing a substrate having a recess, wherein the recess has a height; configuring a first piezoelectric material layer on the substrate, and causing the recess to form an air gap; configuring a lower electrode on the first piezoelectric material layer; when the height is in a first range, causing a resonant frequency of the film bulk acoustic resonance device versus the height to have a first slope; when the height is in a second range, causing the resonant frequency versus the height to have a second slope; and causing the first slope to be smaller than the second slope.

CROSS-REFERENCE TO RELATED APPLICATION

The application claims the benefit of Taiwan Patent Application No. 109136755, filed on Oct. 22, 2020, at the Taiwan Intellectual Property Office, the disclosures of which are incorporated herein in their entirety by reference.

TECHNICAL FIELD

The present disclosure is related to a semiconductor technique applied to a MEMS. Particularly, the present disclosure is applied to a MEMS used in a sensor and an energy-related device.

BACKGROUND

The existing sensor technologies include pure mechanical sensors, CMOS sensors, MEMS sensors etc. However, the sensitivities of the above-mentioned sensors cannot fulfill requirements for detection of VOC gases of human beings such as via a portable device, e.g., a mobile phone. But, a film bulk acoustic resonance (FBAR) device having PZT can do this.

How to improve the existing FBAR technologies to let them have a better efficiency and/or a simpler structure, or a lower manufacturing cost is worthy of further research and improvement.

Keeping the drawbacks of the prior art in mind, and through the use of robust and persistent experiments and research, the applicant has finally conceived of a method for manufacturing a film bulk acoustic resonance device having a specific resonant frequency.

SUMMARY

It is an objective of the present invention to provide a method for manufacturing a film bulk acoustic resonance device having a specific resonant frequency, comprising: providing a substrate having a recess having a height; configuring a first piezoelectric material layer on the substrate, and causing the recess to form an air gap; configuring a lower electrode on the first piezoelectric material layer; causing the specific resonant frequency versus the height to have a first slope when the height is in a first range; causing the specific resonant frequency versus the height to have a second slope when the height is in a second range; and causing the first slope to be smaller than the second slope. FBAR devices respectively having air gaps with various depths (heights) and manufactured via that method will respectively generate various resonant frequencies. Multiple FBAR devices having various heights of the air gaps can be used to simultaneously detect various VOC gases via multi-frequency control, and the same wafer can include a plurality of FBAR devices respectively having various heights of the air gaps to decrease the manufacturing costs.

In accordance with the first aspect of the present invention, a method for manufacturing a film bulk acoustic resonance device having a specific resonant frequency comprises: providing a substrate having a recess, wherein the recess has a height; configuring a first piezoelectric material layer on the substrate; causing the recess to form an air gap; configuring a lower electrode on the first piezoelectric material layer; obtaining a functional relation of a resonant frequency of the film bulk acoustic resonance device versus the height, wherein when the height is in a first range, the functional relation is defined by a first slope, when the height is in a second range, the functional relation is defined by a second slope, and the second slope is larger than the first slope; and depending on a specific height of the recess which corresponds to the specific resonant frequency, selecting the specific height to manufacture the film bulk acoustic resonance device.

In accordance with the second aspect of the present disclosure, a method for manufacturing a film bulk acoustic resonance device having a specific resonant frequency comprises: providing a substrate having a recess having a height; configuring a first piezoelectric material layer on the substrate, and causing the recess to form an air gap; configuring a lower electrode on the first piezoelectric material layer; causing the specific resonant frequency versus the height to have a first slope when the height is in a first range; causing the specific resonant frequency versus the height to have a second slope when the height is in a second range; and causing the first slope to be smaller than the second slope.

DETAILED DESCRIPTION

FIG. 1is a cross-section diagram of a FBAR device according to the preferred embodiment of the present disclosure. InFIG. 1, a FBAR device1includes a substrate10, a first insulating layer12, a second insulating layer13, a first piezoelectric material layer14, a lower electrode15, a second piezoelectric material layer (it is a piezoelectric material film)16and an upper electrode17, wherein the first insulating layer12is configured on the substrate10, the second insulating layer13is configured on the first insulating layer12, the first piezoelectric material layer14is configured on the second insulating layer13, the lower electrode15is configured on the first piezoelectric material layer14, the second piezoelectric material layer16is configured on the lower electrode15, and the upper electrode17is configured on the second piezoelectric material layer16. In addition, there is an air gap11between the first insulating layer12and the substrate10, and the air gap is vacuumized to exhibit a vacuum state.

As shown inFIG. 1, the substrate10includes a silicon (Si), the first insulating layer12includes a silicon nitride (SiN), the second insulating layer13includes a silicon dioxide (SiO2), the upper electrode17and the lower electrode15include Mo, the first piezoelectric material layer14and the second piezoelectric material layer16include aluminum nitride (AlN) or lead zirconium titanate (PZT).

InFIG. 1, a depth (height) of the air gap11is e.g., 1 μm (the first preferred embodiment), 3 μm (the second preferred embodiment), or 5 μm (the third preferred embodiment). Thicknesses of the first insulating layer12, the second insulating layer13, the first piezoelectric material layer14, the upper electrode17and the lower electrode15are all 0.2 μm, and a thickness of the second piezoelectric material layer16is 1 μm.

As shown inFIG. 1, the substrate10, the first insulating layer12, the second insulating layer13, the first piezoelectric material layer14, the lower electrode15and the second piezoelectric material layer16form a first cylinder, a first diameter of the first cylinder is, e.g., 200 μm, the air gap11forms a second cylinder, a second diameter of the second cylinder is, e.g., 140 μm, the upper electrode17forms a third cylinder, and a third diameter of the third cylinder is, e.g., 100 μm.

FIG. 2is a wave diagram of an air gap depth of a FBAR device versus a resonant frequency of the FBAR device according to the preferred embodiment of the present disclosure.

As shown inFIG. 2, when the depth of the air gap11increases from 1 μm to 3 μm, a first increased difference value of a resonant frequency of the FBAR1is about 24 KHz, and when the depth of the air gap11increases from 1 μm to 5 μm, a second increased difference value of the resonant frequency of the FBAR1is about 418 KHz. That is to say, it can be seen inFIG. 2, when the depth of the air gap11is engaged in a linear change (e.g., the depth of the air gap11increases from 1 μm to 3 μm, or increases from 1 μm to 5 μm), the resonant frequency of the FBAR1presents a non-linear change (e.g., when the depth of the air gap11increases from 1 μm to 3 μm, the first increased difference value of the resonant frequency of the FBAR1is about 24 KHz, or when the depth of the air gap11increases from 1 μm to 5 μm, the second increased difference value of the resonant frequency of the FBAR1is about 418 KHz).

A method for manufacturing a film bulk acoustic resonance device1having a specific resonant frequency is proposed according to the fourth preferred embodiment of the present disclosure, and the method comprises: providing a substrate10having a recess11, wherein the recess11has a height; configuring a first piezoelectric material layer14on the substrate10, and causing the recess11to form an air gap11; configuring a lower electrode15on the first piezoelectric material layer14; causing the specific resonant frequency versus the height to have a first slope when the height is in a first range; causing the specific resonant frequency versus the height to have a second slope when the height is in a second range; and causing the first slope to be smaller than the second slope.

The above-mentioned method proposed according to the fourth preferred embodiment of the present disclosure further includes: depending on a specific height of the recess11which corresponds to the specific resonant frequency, selecting the specific height to manufacture the film bulk acoustic resonance device1, wherein when a first thickness of the air gap11increases from 1 μm to 3 μm, the first increased difference value of the resonant frequency of the FBAR1is about 24 KHz, and when a second thickness of the air gap11increases from 1 μm to 5 μm, the second increased difference value of the resonant frequency of the FBAR1is about 0.418 GHz.

A method for manufacturing a film bulk acoustic resonance device1having a specific resonant frequency is proposed according to the fifth preferred embodiment of the present disclosure, and the method comprises: providing a substrate10having a recess11, wherein the recess11has a height; configuring a first piezoelectric material layer14on the substrate10; causing the recess11to form an air gap11; configuring a lower electrode15on the first piezoelectric material layer14to commonly form a resonant frequency determining structure (10+14+15) of the FBAR device with the substrate10and the first piezoelectric material layer14; causing a resonant frequency of the film bulk acoustic resonance device1versus the height to form a functional relation, wherein when the height is in a first range, the functional relation is defined by a first slope, when the height is in a second range, the functional relation is defined by a second slope, and the second slope is larger than the first slope; and depending on a specific height of the recess11which corresponds to the specific resonant frequency, selecting the specific height to manufacture the film bulk acoustic resonance device1.

In conclusion, the present disclosure provides a method for manufacturing a film bulk acoustic resonance device having a specific resonant frequency, comprising: providing a substrate having a recess having a height; configuring a first piezoelectric material layer on the substrate, and causing the recess to form an air gap; configuring a lower electrode on the first piezoelectric material layer; causing the specific resonant frequency versus the height to have a first slope when the height is in a first range; causing the specific resonant frequency versus the height to have a second slope when the height is in a second range; and causing the first slope to be smaller than the second slope. FBAR devices respectively having air gaps with various depths (heights) and manufactured via that method will respectively generate various resonant frequencies. Multiple FBAR devices having various heights of the air gaps can be used to simultaneously detect various VOC gases via multi-frequency control, and the same wafer can include a plurality of FBAR devices respectively having various heights of the air gaps to decrease the manufacturing costs, which is both non-obvious and novel.

While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention need not be limited to the disclosed embodiments. Therefore, it is intended to cover various modifications and similar configurations included within the spirit and scope of the appended claims, which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.