Methods of forming doped regions in semiconductor substrates
Some embodiments include methods of forming one or more doped regions in a semiconductor substrate. Plasma doping may be used to form a first dopant to a first depth within the substrate. The first dopant may then be impacted with a second dopant to knock the first dopant to a second depth within the substrate. In some embodiments the first dopant is p-type (such as boron) and the second dopant is neutral type (such as germanium). In some embodiments the second dopant is heavier than the first dopant.
1. A method of forming a doped region in a semiconductor substrate comprising:
plasma doping of the substrate to form a first dopant to a first depth within the substrate; wherein the plasma doping forms a deposit across an upper surface of the substrate; wherein the first dopant comprises boron;
impacting the first dopant with germanium to knock some of the first dopant out of the deposit and into the substrate while using the deposit as a screen to protect the underlying substrate from any penetration by the germanium; wherein the impacting comprises ion beamline implanting of the germanium utilizing an energy and dose of the germanium which keeps all of the germanium in the deposit; and
cleaning the substrate; the cleaning removing the deposit and all of the germanium to leave a doped region comprising the first dopant and none of the germanium.
2. The method of claim 1 wherein the plasma doping utilizes B 2 H 6 .
3. A method of forming a doped region in a semiconductor substrate comprising:
plasma doping of the substrate to form a first dopant to a first depth within the substrate; wherein the plasma doping forms a deposit across an upper surface of the substrate;
ion bombarding a second dopant into the substrate without a plasma to knock first dopant out of the deposit and into the substrate; the first dopant comprising a first primary element and the second dopant comprising a second primary element different from the first primary element, and heavier than the first primary element; wherein the first primary element is p-type, and wherein the second primary element is neutral-type;
using the deposit as a screen to protect the underlying substrate from any penetration by the second dopant; the ion bombarding being conducted under conditions which keep all of the second dopant in the deposit; and
cleaning the substrate; the cleaning removing the deposit and all of the second dopant to leave a doped region comprising the first dopant and none of the second dopant;
wherein the first primary element is boron, and wherein the second primary element is germanium.
4. The method of claim 3 wherein the plasma doping utilizes B 2 H 6 .
5. A method of forming a doped region in a semiconductor substrate comprising:
plasma doping of the substrate with a boron-containing material to form boron dopant to a first depth within a monocrystalline silicon substrate; wherein the plasma doping forms a deposit across an upper surface of the substrate;
ion bombarding a neutral-type dopant into the substrate without a plasma to knock boron dopant out of the deposit and into the monocrystalline silicon substrate; the neutral-type dopant being heavier than boron;
using the deposit as a screen to protect the underlying monocrystalline silicon substrate from any penetration by the neutral-type dopant; the ion bombarding being conducted under conditions which keep all of the neutral-type dopant in the deposit; and
cleaning the substrate; the cleaning removing the deposit and the neutral-type dopant to leave a doped region comprising the boron dopant and none of the neutral-type dopant;
wherein the neutral-type dopant is germanium.
6. The method of claim 5 wherein the boron-containing material is B 2 H 6 .