Quartz-based MEMS resonators and methods of fabricating same

A method of fabricating a resonator comprising:

• providing a first quartz substrate;
• thinning the first quartz substrate to a desired thickness;
• forming a metallic etch stop on a portion of a first major surface of the first quartz substrate;
• adhesively attaching the first major surface of the first quartz substrate with the metallic etch stop formed thereon to a second quartz substrate using a temporary adhesive, wherein the temporary adhesive covers substantially all of an exposed surface of the first major surface of the first quartz substrate and all of the metallic etch stop formed thereon;
• etching a via though the first quartz substrate to the etch stop;
• forming a metal electrode on a second major surface of the first quartz substrate, the metal electrode penetrating the via in the first quartz substrate to make ohmic contact with the metallic etch stop;
• bonding the metal electrode formed on the second major surface of the first quartz substrate to a pad formed on a substrate bearing oscillator drive circuitry to form a bond there between;
• and
• dissolving the temporary adhesive to thereby release the second quartz substrate from the substrate bearing oscillator drive circuitry and a portion of the first quartz substrate bonded thereto via the bond formed between the metal electrode formed on the second major surface of the first quartz substrate to and the pad formed on the substrate bearing oscillator drive circuitry.

A method of fabricating a resonator comprising:

• providing a first quartz substrate;
• thinning the first quartz substrate to a desired thickness;
• forming a metallic etch stop on a portion of a first major surface of the first quartz substrate;
• adhesively attaching the first major surface of the first quartz substrate and the metallic etch stop formed thereon to a second quartz substrate using a temporary adhesive, the temporary adhesive covering substantially all of an exposed surface of the first major surface of the first quartz substrate and all of the metallic etch stop formed thereon;
• after adhesively attaching the first major surface of the first quartz substrate and the metallic etch stop formed thereon to the second quartz substrate, simultaneously etching a first via though the first quartz substrate to the etch stop and a second via though the first quartz substrate to the temporary adhesive;
• forming a metal electrode on a second major surface of the first quartz substrate, the metal electrode penetrating the via in the first quartz substrate to make ohmic contact with the metallic etch stop;
• bonding the metal electrode formed on the second major surface of the first quartz substrate to a pad formed on a substrate bearing oscillator drive circuitry to form a bond there between;
• and
• dissolving the temporary adhesive to thereby release the second quartz substrate from the substrate bearing oscillator drive circuitry and a portion of the first quartz substrate bonded thereto via the bond formed between the metal electrode formed on the second major surface of the first quartz substrate to and the pad formed on the substrate bearing oscillator drive circuitry.