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Saw filter having planar barrier layer and method of making

a filter and barrier layer technology, applied in the field of surface acoustic wave filter devices, can solve the problems of high electromagnetic coupling (high bandwidth), insufficient tcf, and difficulty in controlling the thickness of buried electrodes

Inactive Publication Date: 2013-06-27
GLOBALFOUNDRIES INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The patent describes a surface acoustic wave (SAW) filter and methods for making it. The filter includes a piezoelectric substrate, a planar barrier layer, and at least one metal conductor. The metal conductor is formed in a trench in the planar barrier layer and is useful for creating a high-quality acoustic wave filter with improved performance. The method involves depositing layers of membrane and metal on the substrate, and then polishing the metal layer to create the conductor. This approach results in a more efficient and effective filter that can be used in various applications.

Problems solved by technology

Surface acoustic wave (SAW) filters are frequently used for radio frequency (RF) filtering in devices such as wireless communication systems, due to small chip size and low insertion loss.
Buried metal SAW filters have been used, and have demonstrated high electromagnetic coupling (high bandwidth), but may not provide a satisfactory TCF.
Other challenges of buried metal SAW filters include damage to the piezoelectric substrate during polishing or etching steps of fabrication, and difficulty controlling thickness of buried electrodes, which in turn affects the signal frequency transmitted by the SAW filter.

Method used

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  • Saw filter having planar barrier layer and method of making
  • Saw filter having planar barrier layer and method of making
  • Saw filter having planar barrier layer and method of making

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Embodiment Construction

[0017]As noted above, FIGS. 1-25 show various embodiments of a SAW filter 100, and processes for making the same.

[0018]Referring to the drawings, FIGS. 1-4 depict one embodiment of SAW filter 100 and a process for making the same. As shown in FIG. 1, a piezoelectric substrate 110 is provided, which may comprise lithium niobate (LiNbO3), among other piezoelectric substrates. A planar barrier layer 120 is provided above piezoelectric substrate 110. In various embodiments, planar barrier layer 120 may be SiO2, and may have a thickness of about 100 nm. Planar barrier layer 120 may be patterned using, e.g., lithography and etching, to form at least one trench 125 in planar barrier layer 120.

[0019]As shown in FIG. 2, metal layer 130 is deposited above planar barrier layer 120 and piezoelectric substrate 110. In an embodiment, metal layer 130 may be copper (Cu), and may be deposited by, e.g., physical vapor deposition (PVD). In FIG. 3, metal layer 130 may be polished using, e.g., chemical ...

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Abstract

Disclosed herein is a surface acoustic wave (SAW) filter and method of making the same. The SAW filter includes a piezoelectric substrate; a planar barrier layer disposed above the piezoelectric substrate, and at least one conductor buried in the piezoelectric substrate and the planar barrier layer.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a divisional of currently pending U.S. patent application Ser. No. 13 / 183,977 filed on Jul. 15, 2011. The application identified above is incorporated herein by reference in its entirety for all that it contains in order to provide continuity of disclosure.FIELD OF THE INVENTION[0002]This disclosure relates generally to surface acoustic wave (SAW) filters, and more particularly to SAW filter devices and a method of making the same, including a planar barrier layer.BACKGROUND[0003]Surface acoustic wave (SAW) filters are frequently used for radio frequency (RF) filtering in devices such as wireless communication systems, due to small chip size and low insertion loss. The performance of a SAW filter depends on the characteristics of the SAW propagated in a piezoelectric substrate. SAW filters having low temperature coefficients of frequency (TCF) result in greater temperature independence at frequencies near the center of...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H01L41/33H01L41/332H10N30/082H10N30/08H10N30/80
CPCY10T29/42H01L41/33H03H3/08H01L41/332H03H9/14538H03H3/10H03H9/02834H03H9/14541
Inventor ADKISSON, JAMES W.CANDRA, PANGLIJENDUNBAR, THOMAS J.GAMBINO, JEFFREY P.JAFFE, MARK D.STAMPER, ANTHONY K.WOLF, RANDY L.
Owner GLOBALFOUNDRIES INC