fill layer 114 is shown to be partially filling trench 110 with a void remaining within trench 110 and the accumulated fill material narrowing the opening of trench 110 at the top indicated at 116 following the partial deposition of fill layer 114 e g by a process such as cvd a method of etching the partially deposited fill layer 114 to enhance access to the trench opening 116 and enable complete filling of trench 110 without unacceptable voids is provided it should be understood that material deposited by cvd or other semiconductor fabrication process may form miniscule or inconsequential voids within the material as used herein the phrase u201c unacceptable voids u201d refers to voids that result in a completed structure being rendered defective faulty or otherwise unacceptable due to a void in the material in one embodiment the opening of a trench feature and the upper sidewall of the trench feature are etched while the fill material at the bottom of the trench is protected from etching to enable complete filling of the trench feature in subsequent deposition of fill material fig3 b shows etching of the partially deposited fill layer 110 in accordance with one embodiment of the present invention substrate 100 is inverted and immersed in an etchant 118 suitable etchants are selected depending on the material to be etched any desired selectivity to barrier liner and substrate material and other known considerations and include diluted hf h 2 o 2 h 3 po 4 or mixture of hcl and hno 3 other suitable etchants are readily available and known to those skilled in the art in one embodiment the inverted substrate 100 is positioned in etchant 118 so that partially deposited fill layer 114 is in contact with etchant 118 the contact.