SAW Device Fabrication flow

1A. IDT electrode process by sputtering and etching

1A-1. IDT electrode deposition

Metal (Al, Mo, W) sputtering, piezoelectric LT and LN are used for the substrate. The film thickness uniformity of this electrode is also important.

Introduction of Sputtering system

1A-2. IDT electrode etching

SAW is an abbreviation for surface acoustic wave, and the frequency is determined by the Pitch of the IDT (comb tooth) electrode, so it is defined by Lithography and processing.

The lift-off method has been used as a conventional technique for forming electrode patterns, but the dry etching method is required for fine processes where the distance between electrodes is 1 μm or less.

(The relationship between frequency and IDT Pitch is approximately 1um width at 0.8GHz, 0.4um width at 2.5GHz, 0.18um width at 5.0GHz)

Process technology for SAW device

1A-3. Removing Resist

Supports residue removal after lift-off with ashing

Introduction of Ashing system

1B. IDT electrode process with liftoff evaporation

1B-1. IDT electrode evaporation

The film quality is Al, Cu. Achieves long-distance TS and improves film thickness uniformity.

Process technology for SAW device

1B-2. 

Removing Resist

Supports residue removal after lift-off with ashing

Introduction of Ashing system

2. TC film

SiO2 deposition by sputtering

3. Adjusting film thickness

Half etching of SiO2

Process technology for SAW device

4. Making film smoother

Trimming by ion milling

Process technology for SAW device

5. Contact hole

6. Contact electrode

Metal deposition by liftoff evaporation and removing resist

7. Forming encapsulation film

SiN sputtering

8. Adjusting film thickness

Half etching of SiN

9. Making film smoother

Trimming by ion milling

10. Making contact hole

Etching SiN

11. Stripping resist and resdue