Plasma deposition

An apparatus for depositing a group III metal nitride film on a substrate, the apparatus comprising:

• (a) a plasma generator to generate a nitrogen plasma from a nitrogen source;
• (b) a reaction chamber in which to react a reagent comprising a group III metal with a reactive nitrogen species derived from the nitrogen plasma so as to deposit a group III metal nitride on the substrate;
• (c) a plasma inlet to facilitate the passage of nitrogen plasma from the plasma generator into the reaction chamber;
• and
• (d) a baffle having one or more flow channels for passage of the nitrogen plasma, the baffle located between the plasma inlet and the substrate and the baffle comprising a plurality of distribution members located above a blocking member, each distribution member defining an aperture and being spaced from adjacent distribution members and the blocking member,
• wherein the baffle prevents a straight line of passage for nitrogen plasma between the plasma inlet and the substrate.

A plasma baffle comprising:

• (a) a first distribution member defining an entry aperture;
• (b) a blocking member;
• and
• (c) one or more connecting members disposed circumferentially and extending between the first distribution member and the blocking member to space the first distribution member and the blocking member apart;
• wherein the space between the first distribution member and the blocking member defines a plasma flow channel.

A process for depositing a group III metal nitride film on a substrate the process comprising the steps of:

• (a) producing a nitrogen plasma using a plasma generator and a nitrogen source;
• (b) introducing the nitrogen plasma into a reaction chamber via a plasma inlet;
• (c) passing the nitrogen plasma through a baffle having one or more flow channels for passage of the nitrogen plasma, the baffle located between the plasma inlet and the substrate and comprising a plurality of distribution members located above a blocking member, each distribution member defining an aperture and being spaced from adjacent distribution members and the blocking member to thereby prevent a straight line of passage for nitrogen plasma between the plasma inlet and the substrate;
• and
• (d) injecting a reagent comprising a group III metal into the reaction chamber at a point between the baffle and the substrate,
• to thereby deposit the group III metal nitride film on the substrate.