Smooth SiConi etch for silicon-containing films

A method of etching a silicon-containing layer on a surface of a substrate in a substrate processing region of a substrate processing chamber, wherein the method reduces a difference in etch-rate between a densely patterned area and a sparsely patterned area, the method comprising:

• flowing a fluorine-containing precursor and a hydrogen-containing precursor into a first remote plasma region fluidly coupled to the substrate processing region while forming a plasma in the first plasma region to produce plasma effluents, wherein a flow rate of the fluorine-containing precursor and a flow rate of the hydrogen-containing precursor result in a hydrogen-to-fluorine atomic flow ratio of less than 1:2;
• etching the silicon-containing layer in the densely patterned area and the sparsely patterned area by flowing the plasma effluents into the substrate processing region while forming solid by-products on the surface of the substrate;
• and
• sublimating the solid by-products by increasing a temperature of the substrate above a sublimation temperature of the solid by-products.

A method of etching a silicon-containing layer on a surface of a substrate in a substrate processing region of a substrate processing chamber, the method comprising:

• flowing a fluorine-containing precursor and a hydrogen-containing precursor into a first remote plasma region fluidly coupled to the substrate processing region while forming a train of plasma pulses in the first plasma region to produce plasma effluents, wherein a flow rate of the fluorine-containing precursor and a flow rate of the hydrogen-containing precursor result in a hydrogen-to-fluorine atomic flow ratio of less than 1:2;
• etching the silicon-containing layer by flowing the plasma effluents into the substrate processing region while forming solid by-products on the surface of the substrate;
• and
• sublimating the solid by-products by increasing a temperature of the substrate above a sublimation temperature of the solid by-products.