Apparatus and method for improving uniformity in batch processing of semiconductor wafers

A chemical vapor deposition method for semiconductor wafers, comprising:

• placing a batch of semiconductor wafers in a reaction vessel;
• feeding into the reaction vessel one or more reactant gases formulated to undergo a film forming chemical reaction at the surface of the wafers;
• exhausting unused reactants and/or reaction by-products from the reaction vessel;
• cycling the pressure in the reaction vessel between a higher pressure and a lower pressure;
• and
• the higher pressure is in the range of 100 millitorr to 500 millitorr.

A chemical vapor deposition method for semiconductor wafers, comprising:

• placing a batch of semiconductor wafers in a reaction vessel;
• feeding into the reaction vessel one or more reactant gases formulated to undergo a film forming chemical reaction at the surface of the wafers;
• exhausting unused reactants and/or reaction by-products from the reaction vessel;
• cycling the pressure in the reaction vessel between a higher pressure and a lower pressure;
• maintaining the higher pressure for a first period of time and the lower pressure for a second period of time during each cycle;
• and
• the second period of time is in the range of 5 milliseconds to 200 milliseconds.

A method for plasma etching semiconductor wafers, comprising:

• placing a batch of semiconductor wafers in a reaction vessel;
• generating a plasma containing reactants for etching surfaces of the wafers;
• surrounding the wafers with the plasma;
• exhausting unused reactants and/or reaction by-products from the reaction vessel;
• and
• cycling the pressure in the reaction vessel between a higher pressure in the range of 500 millitorr to 1500 millitorr and a lower pressure in the range of 200 millitorr to 400 millitorr.

A chemical vapor deposition method for semiconductor wafers, comprising:

• placing a batch of semiconductor wafers in a reaction vessel;
• feeding into the reaction vessel one or more reactant gases formulated to undergo a film forming chemical reaction at the surface of the wafers;
• exhausting unused reactant reactants and/or reaction by-products from the reaction vessel;
• and
• cycling the pressure in the reaction vessel between a higher pressure in the range of 100 millitorr to 500 millitorr and a lower pressure in the range of 50 millitorr to 500 millitorr.