Plasma immersion ion implantation process

A process for implanting ions into a semiconductor wafer, the process comprising:

• supporting the semiconductor wafer on a first electrode in a chamber;
• injecting a gas into the chamber, the gas comprising dopants to be implanted into the semiconductor wafer;
• and
• providing first voltage pulses to the first electrode, the first voltage pulses being direct current (DC) voltage pulses less than 10 kV in magnitude that ionize the gas to create a non-continuous plasma at a surface of the semiconductor wafer and accelerate and implant ions from the non-continuous plasma into the surface, the first voltage pulses being of sufficiently short duration so as not to contribute to formation of particles that deposit on the surface.

A process for implanting ions into a semiconductor wafer, said process comprising steps of:

• supporting said semiconductor wafer on a first electrode in a chamber, said first electrode being electrically connected to a first pulsed voltage source;
• providing first voltage pulses to said first electrode, said first voltage pulses being less than 10 kV in magnitude and that induce formation of a non-continuous plasma at a surface of said semiconductor wafer and accelerate ions from said non-continuous plasma into said semiconductor wafer surface, said first voltage pulses being of sufficiently short duration so as not to contribute to formation of particles which deposit on said semiconductor wafer surface;
• and
• providing a flow of neutralizing electrons to said semiconductor wafer surface to neutralize charge built up thereon, thereby avoiding surface charge induced damage, said step of providing the flow of neutralizing electrons comprising steps of:
• providing a cold cathode electron source in said chamber, said source being electrically connected to a second pulsed voltage source;
• and
• pulsing said cold cathode electron source with second voltage pulses, said second voltage pulses being timed to said first voltage pulses.

A process for implanting ions into a semiconductor wafer having a surface, said process comprising steps of:

• supporting said semiconductor wafer on a first electrode in a chamber having an ionizable gas therein, said first electrode being electrically connected to a voltage source;
• sequentially providing a plurality of first voltage pulses to said first electrode, each of said first voltage pulses being less than 10 kV in magnitude and creating within a vicinity of said semiconductor wafer surface a plasma having ions, and after producing said plasma having ions, each said first voltage pulse accelerating said ions into said semiconductor wafer surface;
• removing all plasma inducing electric fields after each said first voltage pulse so that said plasma is extinguished between said first voltage pulses;
• providing a cold cathode electron source in said chamber, said cathode electron source being electrically connected to a second pulsed voltage source;
• and
• sequentially providing a plurality of second voltage pulses to said cold cathode electron source to provide a pulsed flow of electrons to said semiconductor wafer surface which neutralizes charge built up on said surface of said semiconductor wafer, said second voltage pulses being timed with said first voltage pulses.

A method of treating a workpiece comprising steps of:

• inserting the workpiece into an interior of a treatment chamber and supporting the workpiece on a conductive workpiece support such that a treatment surface of the workpiece faces a treatment region in the interior of the treatment chamber, the treatment chamber having a conductive wall portion that bounds the interior of the treatment chamber;
• injecting a treatment material comprising neutrally uncharged gas molecules into the treatment chamber such that the gas molecules occupy the treatment region;
• and
• repeatedly relatively biasing the conductive workpiece support and the conductive wall portion of the treatment chamber by applying D.C. voltage pulses less than 10 KV in magnitude to ionize the gas molecules injected into the treatment chamber and to accelerate and implant resulting charged particles into the workpiece.

An apparatus for treating a workpiece comprising:

• a treatment chamber defining a chamber interior and having a conductive wall portion that bounds the chamber interior;
• a conductive workpiece support for supporting the workpiece in the chamber interior of the treatment chamber;
• an injector for injecting a treatment material comprising gas molecules into the treatment chamber such that the gas molecules occupy a treatment region proximal to the workpiece supported by the conductive workpiece support;
• and
• control circuitry for repeatedly relatively biasing the conductive workpiece support and the conductive wall portion of the treatment chamber, the control circuitry comprising a voltage source for providing a sequence of D.C. voltage pulses less than 10 KV in magnitude that both ionize the gas molecules injected into the treatment chamber and accelerate and implant resulting charged particles into the workpiece.