Method for making a semiconductor device with self-aligned inner spacers
A method for making a semiconductor device, including: a) making, on a substrate, a stack comprising a first semiconductor portion able to form an active zone and arranged between two second portions of a material able to be selectively etched relative to the semiconductor of the first portion, b) making, on a part of the stack, outer spacers and a dummy gate, c) etching the second portions such that remaining parts are arranged under the dummy gate, d) partially oxidizing the remaining parts from the outer faces, forming inner spacers, e) removing the dummy gate and non-oxidized parts of the remaining parts arranged under the dummy gate, f) making a gate between the outer spacers and between the inner spacers and covering the channel.
1. A method for making a semiconductor device, including at least:
a) making, on a substrate, a stack comprising at least one first semiconductor portion arranged between at least two second portions of at least one material able to be selectively etched relative to the semiconductor of the first portion, the first portion being able to form at least one active zone of the semiconductor device,
b) making, on a part of the stack, outer spacers and at least one dummy gate arranged between the outer spacers,
c) etching the second portions such that remaining parts of the second portions are arranged at least under the dummy gate,
d) partially oxidising the remaining parts of the second portions from outer faces of the remaining parts of the second portions which are revealed by etching the second portions, forming inner spacers,
e) removing the dummy gate and the non-oxidised parts of the remaining parts of the second portions arranged at least under the dummy gate,
f) making a gate between the outer spacers and between the inner spacers, covering the channel and able to be electrically insulated from source and drain regions by the outer spacers and the inner spacers.
2. The method according to claim 1 , wherein:
step c) of etching is implemented such that the remaining parts of the second portions are also arranged under the outer spacers,
the inner spacers are arranged at least partially under the outer spacers.
3. The method according to claim 1 , further including, between steps d) and e), making the source and drain regions by epitaxially growing a semiconductor from at least parts of the first semiconductor portion.
4. The method according to claim 1 , wherein implementing step c) also etches the first semiconductor portion such that a remaining part of the first semiconductor portion arranged at least under the dummy gate is preserved.
5. The method according to claim 1 , wherein:
step b) is implemented such that at least two dummy gates are made on the stack, each of the dummy gates being arranged between outer spacers,
step c) is implemented such that at least part of the first semiconductor portion located between both dummy gates is not etched.
6. The method according to claim 1 , wherein:
the method further includes, between steps b) and c), implementing a deposition of a protective material covering parts of the stack which are not covered with the dummy gate and with the outer spacers, and then removing the outer spacers, named first outer spacers,
implementing step c) also etches parts of the first semiconductor portion previously arranged under the first outer spacers,
implementing step d) also makes a partial oxidation of the second remaining parts of the second portions covered with the protective material from outer faces of the second remaining parts of the second portions revealed by etching the second portions,
and further including, between steps d) and e), implementing the following steps:
epitaxially growing a semiconductor at least between a first part of the first semiconductor portion arranged under the dummy gate and second parts of the first semiconductor portion which are arranged under the protective material, forming source and drain extension regions, and then
making second outer spacers at least on the source and drain extension regions, and then
removing the protective material and the second remaining parts of the second portions, and then
making the source and drain regions by epitaxially growing a semiconductor from at least the second parts of the first semiconductor portion.
7. The method according to claim 6 , further including, between the step of removing the protective material and the step of making the source and drain regions, a step of removing at least part of oxidised portions from the second portions covered with the protective material.
8. The method according to claim 1 , wherein the step d) of oxidising also makes a partial oxidation of the first semiconductor portion, the method further including, between steps d) and e), implementing an etching of oxidised parts of the first semiconductor portion.
9. The method according to claim 1 , wherein the material of the second portions is able to be oxidised more quickly than the semiconductor of the first portion.
10. The method according to claim 9 , wherein the semiconductor of the first portion is silicon or SiGe, and the material of the second portions is SiGe including a germanium proportion higher than that of the semiconductor of the first portion.
11. The method according to claim 3 , wherein the semiconductor of the source and drain regions is compressive stressed SiGe when the semiconductor device corresponds to a P-type transistor.
12. The method according to claim 1 , wherein the stack includes several first semiconductor portions each forming a nanowire arranged between two second portions.
13. The method according to claim 1 , wherein the semiconductor device includes at least one GAA-FET transistor.