Single-chip radio structure with piezoelectric crystal device integrated on monolithic integrated circuit and method of fabricating the same

• US 6,285,866 B1
• Filed: 06/21/1999
• Issued: 09/04/2001
• Est. Priority Date: 10/30/1998
• Status: Expired due to Fees

• Current Assignee: Korea Advanced Institute of Science and Technology
• Original Assignee: Korea Advanced Institute of Science and Technology
• Inventors: Eo, Yun Seong, Lee, Kwyro, Hyun, Seokbong
• Primary Examiner(s): Urban, Edward F.
• Application Number:
  US09/336,297
• Time in Patent Office: 806 Days
• Field of Search: 455/318, 455/334, 455/316, 455/321, 455/323, 455/333, 29/253.5, 292/16, 294/27
• US Class Current: 455/318
• CPC Class Codes: H03B 5/326 the resonator being an acoustic wave device, e.g. SAW or BAW device
• CPC Class Codes: H04B 1/0003 Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain digital baseband systems H04L25/00; digital modulation/demodulation H04L27/00; CDMA H04B1/707; TDMA H04B7/2643; image transmission H04N5/00
• CPC Class Codes: H04B 1/28 the receiver comprising at least one semiconductor device having three or more electrodes
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

A single-chip radio structure with a piezoelectric crystal device integrated on a monolithic integrated circuit and a method of fabricating the same. A thin or thick piezoelectric crystal wafer is bonded on a silicon substrate and adjusted in thickness by mechanical grinding and polishing processes. Then, a surface acoustic wave resonator and other passive devices such as a filter, inductor, etc. are formed on the piezoelectric crystal wafer by a standard lithography process. Therefore, a high-precision oscillator and various passive devices can be included in a monolithic integrated circuit to implement a single-chip radio structure. This single-chip radio structure has the effect of reducing the volume and weight of the entire receiver while maintaining excellent performances provided by passive devices on a crystal substrate, such as frequency stability, frequency linearity and low power consumption, etc., as they are.

Claims

1. A method of fabricating a single-chip radio structure with a piezoelectric crystal device integrated on a monolithic integrated circuit, comprising the steps of:

(a) bonding a metal layer selected from the group consisting of aluminum and gold on an area of a silicon substrate on which a piezoelectric crystal wafer is to be laid;

(b) coating an epoxy bonding layer on said metal layer by a spin coating process;

(c) bonding said piezoelectric crystal wafer on said epoxy bonding layer;

(d) adjusting a thickness of said piezoelectric crystal wafer by mechanical grinding and polishing;

(e) forming a surface acoustic wave resonator on the piezoelectric crystal wafer by using photolithography and etching a part of said piezoelectric crystal wafer with a solvent; and

(f) connecting the resonator with an oscillator circuit on said silicon substrate by a metal wire layer.