Method and structure for forming FinFET CMOS with dual doped STI regions
View Patent ↗A method of making a semiconductor device includes forming a first fin of a first transistor in a substrate; forming a second fin of a second transistor in the substrate; disposing a first doped oxide layer including a first dopant onto the first fin and the second fin, the first dopant being an n-type dopant or a p-type dopant; disposing a mask over the first fin and removing the first doped oxide layer from the second fin; removing the mask and disposing a second doped oxide layer onto the first doped oxide layer over the first doped oxide layer covering the first fin and directly onto the second fin, the second doped oxide layer including an n-type dopant or a p-type dopant that is different than the first dopant; and annealing to drive in the first dopant into a portion of the first fin and the second dopant into a portion of the second fin.
1. A semiconductor device, comprising:
a first transistor comprising a first fin patterned in a substrate, the first fin comprising a first doped region comprising a first dopant, the first dopant being an n-type dopant or a p-type dopant;
a first doped oxide spacer disposed along a portion of a sidewall of the first fin adjacent to the first doped region and comprising the first dopant;
a second doped oxide spacer disposed over the first doped oxide spacer and comprising a second dopant, the second dopant being different than the first dopant;
a second transistor comprising a second fin patterned in the substrate, the second fin comprising a second doped region comprising the second dopant; and
a third doped oxide spacer disposed along a portion of a sidewall of the second fin adjacent to the second doped region of the second fin and comprising the second dopant.
2. The semiconductor device of claim 1 , wherein the n-type dopant is phosphorus, and the p-type dopant is boron.
3. The semiconductor device of claim 1 , further comprising a doped substrate region between the first fin, the second fin, or both the first and second fins, and the substrate.
4. The semiconductor device of claim 1 , further comprising an undoped oxide between the first fin and the second fin.
5. The semiconductor device of claim 1 , wherein the first and second doped oxide spacers form a bilayer spacer along a first portion of the sidewall of the first fin, and the second doped oxide spacer is disposed directly onto a second portion of the sidewall of the first fin.
6. A semiconductor device, comprising:
a first transistor comprising a first fin patterned in a substrate, the first fin having a top surface and a sidewall and comprising a first doped region comprising a first dopant, the first dopant being an n-type dopant or a p-type dopant;
a first doped oxide spacer disposed directly on a portion of the sidewall of the first fin and adjacent to the first doped region of the first fin, the first doped oxide spacer also comprising the first dopant;
a second doped oxide spacer disposed over the first doped oxide spacer, the second doped oxide spacer comprising a second dopant, the second dopant being different than the first dopant;
a second transistor comprising a second fin patterned in the substrate, the second fin having a top surface and a sidewall and comprising a second doped region comprising the second dopant; and
a third doped oxide spacer disposed directly on a portion of the sidewall of the second fin, the third doped oxide spacer being adjacent to the second doped region of the second fin and comprising the second dopant;
wherein the second doped oxide spacer of the first fin and the third doped oxide spacer of the second fin comprise the same doped oxide material and dopant.
7. The semiconductor device of claim 6 , wherein the first doped oxide is a p-doped oxide, and the second doped oxide is an n-doped oxide.
8. The semiconductor device of claim 7 , wherein the first doped oxide spacer and the second doped oxide spacer form a bilayer spacer on the sidewall of the first fin, and the third doped oxide spacer forms a single layer spacer on the sidewall of the second fin.
9. The semiconductor device of claim 8 , wherein the third doped oxide spacer of the second fin is thicker than the second doped oxide spacer of the first fin.