Method of plasma etching thin films of difficult to dry etch materials

A method for plasma etching a layer of at least one of Platinum, Iridium, Gold, Copper, a refractory element and a transition element comprising the steps of:

• forming a hard mask on the layer for providing an etch pattern on the layer, the layer being formed on a wafer;
• providing a plasma etch chamber including a wafer electrode at an initial temperature of less than about 100 degrees Celsius;
• securing the wafer to the wafer electrode with a clamping force of substantially zero;
• bombarding the wafer with charged particles from a plasma generated in the plasma etch chamber to impart thermal energy to the wafer;
• reducing loss of the thermal energy from the wafer to the wafer electrode and wafer surroundings including substantially eliminating backside cooling of the wafer electrode;
• providing a reactive gas flow comprising a halogen to react with material to form etch products;
• and
• applying bias power to the wafer electrode to impart bombardment energy to the charged particles incident on the wafer from the plasma such that a temperature higher than the initial temperature is generated on a surface of the wafer wherein the wafer electrode is maintained at about the initial temperature of less than about 100 degrees Celsius, the temperature having a value sufficient to make the etch products volatile to react with the reactive gas flow wherein a combination of the steps of reducing loss of the thermal energy and applying bias power increases volatility of the etch products to improve an etch rate of the material.

A method for patterning platinum electrodes for stacked capacitors for dynamic random access memory chips comprising the steps of:

• providing a wafer having a layer of Platinum formed thereon;
• patterning a hard mask on the layer of Platinum;
• securing the wafer to a wafer electrode with a clamping force of substantially zero in a plasma etch chamber, the wafer electrode being at an initial temperature of less than about 100 degrees Celsius;
• bombarding the wafer with charged particles from a plasma generated in a plasma etch chamber to impart thermal energy to the wafer;
• reducing loss of the thermal energy from the wafer to the wafer electrode and wafer surroundings including substantially eliminating backside cooling of the wafer electrode;
• providing a reactive gas flow including halogen to react to form etch products of the Platinum and to etch the Platinum in accordance with the hard mask;
• and
• applying bias power to the wafer electrode to impart bombardment energy to the charged particles incident on the wafer from the plasma wherein a combination of the steps of reducing the thermal energy and applying bias power generates a temperature of greater than about 200 degrees Celsius on a surface of the wafer wherein the wafer electrode is maintained about the initial temperature of about less than 100 degrees Celsius.