Method for using heated substrates for process chemistry control
A method of controlling doping of a substrate, the method comprising: providing the substrate in a process chamber of a doping system; performing a doping process to impart a target dose on a surface of the substrate using a abruptness depth control technique; and controlling selected operating variables of plasma doping in order to meet doping objectives.
1. A method of controlling doping of a substrate, the method comprising:
providing the substrate in a process chamber of a doping system;
performing a doping process to impart a target dose on a surface of the substrate using an abruptness depth control technique that includes exposing the substrate to at least one of (i) a plasma at one or more predetermined temperatures, (ii) one or more predetermined source powers including at least one of a first source power and a second source power, (iii) one or more predetermined concentrations of dopant radicals, and (iv) one or more predetermined bias powers including at least one of a first bias power and a second bias power; and
controlling selected operating variables of plasma doping in order to meet doping objectives;
wherein performing the doping process further comprises:
exposing the substrate to light ion plasma, wherein the exposure to the light ion plasma is performed at the second source power and the second bias power; and
exposing the substrate to a surface wave plasma, wherein the exposure to the surface wave plasma is performed at the first source power and the first bias power;
wherein the second source power is less than the first source power, and the second bias power is less than the first bias power.
2. The method of claim 1 wherein the doping objectives include a target damage density, target amorphization depth, and target transition abruptness.
3. The method of claim 2 wherein:
the one or more predetermined temperatures includes at least one of a first temperature is in a range from 30° C. to 1,000° C., a second temperature is in a range from 30° C. to 1,000° C., a third temperature is in a range from 30° C. to 1000° C.;
the one or more source powers includes at least one of a first source power in a range from 1,000 to 10,000 W and a second source power is in a range from 1,000 to 10,000 W;
the one or more predetermined concentration of dopant radicals includes at least one of a first concentration of dopant radicals in a range of 10 18 cm−3 to 10 22 cm−3 and a second concentration of dopant radicals in a range of 10 18 cm−3 to 10 22 cm−3; and
the predetermined bias power is in a range from zero to 500 W.
4. The method of claim 3 ,
wherein the exposure to the light ion plasma is performed at the second temperature, a second pressure, and the second concentration of dopant radicals; and
wherein the exposing the substrate to the surface wave plasma is performed at the first temperature, a first pressure, and the first concentration of dopant radicals.
5. The method of claim 4 wherein:
a combination of exposing the substrate to light ion plasma at the second temperature, exposing the substrate to surface wave plasma at the first temperature, and exposing the substrate to surface wave plasma at the first temperature is iterated until the doping objectives are reached.
6. The method of claim 3 further comprises:
performing an oxidizing clean process on the substrate;
performing an annealing process on the substrate; and
controlling selected operating variables of the oxidizing clean process and the annealing process in order to meet doping objectives;
wherein the annealing process further comprises performing a first anneal process or a first anneal process followed by a second anneal process.
7. The method of claim 6 wherein:
performing a pre-amorphization process configured to impart a deep dose on a surface of the substrate by facilitating diffusion of radicals with low enough current so that the surface of the substrate is not sputtered prior to performing the doping process to impart the target dose on the surface of the substrate using the abruptness depth control technique.
8. The method of claim 7 wherein a source power of the doping system is an inductively coupled plasma (ICP), an electron-cyclotron resonance (ECR), or a very high frequency (VHF) capacitively coupled plasma (CCP).
9. The method of claim 7 wherein annealing of the substrate comprises application of heat to the substrate using an electrically self-biased heated electrostatic chuck, microwave radiation exposure, light emitting diodes or flash lamps.
10. The method of claim 7 wherein heating of the substrate is pulsed and a rate of drop of current and radical flux generated for the doping system depend on the pulsing rate and duty cycle.
11. The method of claim 7 wherein the heated electrostatic chuck is operated at a temperature above a sublimation or decomposition temperature of a material in a saturation layer of the substrate.
12. The method of claim 7 wherein controlling the temperature and additives to the saturation layer of the substrate for a high dose conformal low damage doping process.
13. The method of claim 7 wherein the doping process includes selective removal of a surface layer that further comprises:
amorphization of a surface of a layer of the substrate;
infusing radicals into the process chamber which render the layer volatile when heated; and
removing the layer in a flash heating step using a substrate heater or a flash lamp.
14. The method of claim 7 wherein the oxidizing clean process comprises removing a subsequent layer of the substrate with a wet clean.
15. The method of claim 4 wherein the light ion plasma comprises helium or argon ions and the doping radicals comprises P, As, or B derived from PH3, AsH3, and BH3 respectively.
16. The method of claim 7 wherein operating variables of the plasma doping system include pressure in the process chamber, ion flux, damage density, penetration depth, sputter rate, density of the substrate, amorphization depth, ion energy, and/or temperature of the substrate.
17. The method of claim 1 , wherein the light ion plasma is configured to impart the target dose at a deeper penetration depth into the surface of the substrate than the surface wave plasma.