Method For Implementing Low Dose Implant In A Plasma System

A method of performing low dose implantation of a workpiece disposed in a process chamber, comprising:

• creating a plasma in said process chamber;
• operating a RF power supply in a pulsed plasma mode after said plasma is created to reduce a concentration of ions in said plasma, wherein, in said pulsed plasma mode, said RF power supply repeatedly generates at least a first RF power level and a second lower RF power level, causing said plasma to vary in ion concentration as a function of time;
• waiting a time period;
• and
• implanting ions into said workpiece after said time period by applying a first negative bias voltage to said workpiece when said second lower RF power level is generated and applying a second bias voltage, less negative than said first negative bias voltage, to said workpiece when said first RF power level is generated.

A method of performing low dose implantation of a workpiece disposed in a process chamber, wherein said process chamber comprises a top cover with coils disposed thereon, comprising:

• creating a plasma in said process chamber by applying a RF power to said coils;
• waiting a first time period for conditions within said process chamber to stabilize after creating said plasma;
• applying, after said first time period, in an alternating manner, a first RF power to said coils and a second RF power, less than said first RF power, to said coils, causing said plasma to vary in ion concentration as a function of time;
• waiting a second time period for conditions within said process chamber to stabilize after said applying;
• and
• implanting ions into said workpiece after said second time period by pulsing a negative bias voltage to said workpiece, wherein a temporal relationship exists between said negative bias voltage pulsed to said workpiece and said RF power applied to said coils so that a more negative bias voltage is applied to said workpiece when said second RF power is applied to said coils.