Mesa-oxide isolation and mesa-oxide guard ring isolation methods on compound semiconductor devices and circuits

A mesa-oxide guard ring isolation method comprises steps of:

• epitaxy:
• placing a wafer in a metalorganic chemical vapor deposition (MOCVD) system or a molecular beam epitaxy (MBE) system to grow an epitaxial layer on a surface of the wafer,
• spinning the first photo-resist:
• spinning the first photo-resist on an upper surface of the epitaxial layer,
• exposing and developing at the first time:
• exposing the wafer under a light to print electric circuit pattern on a masking and soaking the wafer in a developing solution to solve and remove the photosensitive resin,
• etching at the first time:
• a portion of the epitaxial layer is removed,
• growing a thin oxide layer:
• growing a thin oxide layer on the area of the epitaxial layer without photoresist by soaking the wafer in a chemical solution,
• removing photo-resist at the first time:
• the photoresist which is not exposed to the light is removed to form a mesa on the upper surface of the wafer,
• spinning the second photo-resist:
• spinning the second photo-resist on an upper surface of the epitaxial layer,
• exposing and developing at the second time:
• exposing the wafer under a light to print electric circuit pattern on a masking and soaking the wafer in a developing solution to solve and remove the photosensitive resin,
• etching at the second time:
• a portion of the thin oxide layer is removed,
• removing photo-resist at the second time:
• the photoresist which is not exposed to the light is removed to form a mesa on the upper surface of the wafer and to form an oxide ring on the surrounding of the mesa,
• metalization:
• depositing metal connections on the mesa and the wafer.