Method for forming L-shaped spacers with precise width control

A method of fabrication of L-shaped spacers in a semiconductor device, comprising the steps of:

• a) providing a gate structure over a substrate;
• b) forming a firs dielectric layer over said gate structure and said substrate;
• said first dielectric layer formed using an atomic layer deposition process;
• said first dielectric layer formed by an atomic layer deposition process using tetraisocyanatesilane and water, and said first dielectric layer comprised of oxide;
• said first dielectric layer has a thickness of between about 50 and 200 Å;
• said first dielectric layer formed at a temperature between about 200 and 400° C.;
• c) forming a second dielectric layer over said first dielectric layer;
• said second dielectric layer formed using an atomic layer deposition process;
• d) forming a third dielectric layer over said second dielectric layer;
• said third dielectric layer formed using an atomic layer deposition process;
• e) etching said third dielectric layer to form a disposable spacer on said second dielectric layer,
• f) anisotropically etching said second dielectric layer and said first dielectric layer using said disposable spacer as a mask to form a top and a bottom L-shaped spacer, and
• g) removing said disposable spacer.

A method of fabrication of L-shaped spacers in a semiconductor device, comprising the steps of:

• a) providing a gate structure over a substrate;
• b) forming a first dielectric layer over said gate structure and said substrate;
• said first dielectric layer formed using an atomic layer deposition process;
• c) forming a second dielectric layer over said first dielectric layer;
• said second dielectric layer formed using an atomic layer deposition process;
• said second dielectric layer is formed by an atomic layer deposition (ALD) process using trimethyaluminum (TMA) and ozone and water and said second dielectric layer comprised of aluminum oxide, said second dielectric layer formed at a temperature between 400 and 450° C.;
• d) forming a third dielectric layer over said second dielectric layer;
• said third dielectric layer formed using an atomic layer deposition process;
• e) etching said third dielectric layer to form a disposable spacer on said second dielectric layer;
• f) anisotropicly etching said second dielectric layer and said first dielectric layer using said disposable spacer as a mask to form a top and a bottom L-shaped spacer, and
• g) removing said disposable spacer.

A method of fabrication of L-shaped spacers in a semiconductor device, comprising the steps of:

• a) providing a gate structure over a substrate;
• b) forming a first dielectric layer over said gate structure and said substrate;
• said first dielectric layer formed using an atomic layer deposition process;
• c) forming a second dielectric layer over said first dielectric layer;
• said second dielectric layer formed using an atomic layer deposition process;
• d) forming a third dielectric layer over said second dielectric layer, said third dielectric layer formed using an atomic layer deposition process;
• said third dielectric layer formed by an atomic layer deposition process using tetraisocyanatesilane and water;
• said third dielectric layer comprised of oxide, said third dielectric layer formed at a temperature between 200 and 400° C.;
• e) etching said third dielectric layer to form a disposable spacer on said second dielectric layer;
• f) anisotropically etching said second dielectric layer and said first dielectric layer using said disposable spacer as a mask to form a top and a bottom L-shaped spacer;
• and
• g) removing said disposable spacer.