Semiconductor device, semiconductor laser, their manufacturing methods and etching methods

A semiconductor laser comprising:

• a substrate;
• a first cladding layer of a first conduction type made of a nitride semiconductor of a first conduction type on said substrate;
• a current blocking layer formed on said first cladding layer of the first conduction type and having a stripe-shaped opening which partly exposes said first cladding layer of the first conduction type, said current blocking layer having a first layer of a nitride semiconductor formed adjacent to said first cladding layer of the first conduction type and a second layer of a nitride semiconductor formed on said first layer, said first layer being made of a material more likely etched than said second layer and said first cladding layer of the first conduction type;
• a second cladding layer of the first conduction type made of a nitride semiconductor of the first conduction type lying in and above said opening and on said current blocking layer so as to bury said stripe-shaped opening;
• and
• an active layer formed on said second cladding layer of the first conduction type.

A semiconductor laser manufacturing method comprising:

• forming a nitride semiconductor layer by a crystal growth for crystallographically growing a nitride semiconductor on a substrate;
• selectively etching said nitride semiconductor to form a stripe-shaped opening;
• forming a buried layer by crystallographically growing a nitride semiconductor containing at least two kinds of group III elements in and above said opening and on said nitride semiconductor layer;
• and
• for forming an active layer of a nitride semiconductor on said buried layer.

A semiconductor laser manufacturing method comprising:

• sequentially forming on a substrate an etching stop layer of a first conduction type nitride semiconductor, an etching layer of a nitride semiconductor and an etching mask layer of a second conduction type nitride semiconductor, said nitride semiconductor of said etching layer being more likely etched than those of said etching mask layer and said etching stop layer;
• partly etching said etching mask layer to form a stripe-shaped first opening to expose a part of said etching layer in said first opening;
• heating said etching layer in a mixed atmosphere containing hydrogen and at least one of nitrogen, ammonium, helium, argon, xenon and neon, or a mixed atmosphere of nitrogen and ammonium, or a hydrogen atmosphere to etch said etching layer exposed in said first opening and thereby form a stripe-shaped second opening to expose a part of said etching stop layer;
• burying said first opening and said second opening with a buried layer of a first conduction type nitride semiconductor;
• and
• forming an active layer on said buried layer.