Dry etching method

A dry etching method to form a window having a bottom in a silicon oxide layer comprising the steps of:

• providing a silicon substrate having a silicon oxide layer;
• forming a mask pattern on the silicon oxide layer with a maximum width opening of 1 .mu.m;
• placing the silicon substrate into a reactive chamber having an etching gas introducing means;
• introducing a gas mixture of fluorocarbon gas and hydrogen gas;
• dissociating the gas mixture to produce CF.sub.x (x:
• 0.ltoreq.x.ltoreq.2) polymers;
• etching the silicon oxide layer selectively to the silicon substrate according to the mask pattern;
• and
• suppressing a formation of the polymers at the bottom of the silicon oxide layer.

A dry etching method by a plasma etching comprising the steps of:

• providing a silicon material having a silicon oxide layer thereon;
• forming a mask pattern on the silicon oxide layer with a maximum width opening of 1 .mu.m;
• placing the material into a reactive chamber having an etching gas introducing means;
• introducing fluorocarbon gas and hydrogen gas;
• generating a plasma within the reactive chamber to plasma etch the silicon oxide layer selectively to the silicon material according to the mask pattern such that, as a ratio of the hydrogen gas to the fluorocarbon gas is increased beyond a ratio wherein an etching depth of the silicon oxide rapidly decreases, a ratio of the etching depth of the silicon oxide to an opening width is within 10%.

A dry etching method to form a window having a bottom in a silicon oxide layer comprising the steps of:

• providing a silicon substrate having a silicon oxide layer;
• forming a mask pattern on the silicon oxide layer with a maximum width opening of 1 .mu.m;
• placing the silicon substrate into a reactive chamber having an etching gas introducing means;
• introducing a gas compound containing carbon, fluorine and hydrogen;
• dissociating the gas compound to produce CF.sub.x (x:
• 0.ltoreq.x.ltoreq.2) polymers;
• etching the silicon oxide layer selectively to the silicon substrate according to the mask pattern;
• and
• suppressing a formation of the polymers at the bottom of the silicon oxide layer.