Method and apparatus for ultrasonic wet etching of silicon
AssigneeMicron Technology, Inc.
InventorsDavid R. Hembree, Salman Akram
Life of this patent
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Abstract
Methods of forming substantially defect-free silicon structures at the submicron level by enhancing microscopic etchant concentration uniformity and reducing hydrogen bubble adhesion. Etchant mixtures are subjected to the application of ultrasonic waves. The ultrasonic waves promote cavitation that mixes the etchant mixture on a microscopic level, and also assists in promoting bubble detachment. Wetting agents are added to the etchant mixture to enhance the hydrophilicity of the silicon surfaces and thereby reduce bubble adhesion. Apparatus to carry out the method of forming silicon structures are also disclosed.
Claims27
A method of etching to form a silicon structure comprising:
- providing a silicon substrate;
- etching said substrate in an etchant mixture, wherein said mixture includes an etchant and a wetting agent;
- and
- simultaneously applying ultrasonic waves to the etchant mixture during at least a portion of said etching.
A method of forming a silicon structure having a substantially defect-free surface comprising:
- providing a silicon substrate;
- etching said substrate in an etchant mixture, wherein said solution includes an alkaline etchant and a wetting agent;
- and
- applying ultrasonic waves with a frequency of about 20 to 40 kiloHertz to the etchant mixture.
A method of forming a silicon contact test structure comprising:
- providing a silicon substrate;
- etching said substrate in an etchant mixture, wherein said mixture includes an etchant and a wetting agent;
- applying ultrasonic waves to the etchant mixture;
- and forming a silicon contact test structure on said substrate;
- and
- forming a silicon contact test structure on said substrate.
A method of forming silicon structures by wet etching comprising:
- providing a silicon wafer;
- providing an etching apparatus, wherein said apparatus comprises a polypropylene tank for holding an etchant mixture, a holder for containing the silicon wafer, and at least one ultrasonic transducer capable of producing frequencies in the range of about 20 to 40 kiloHertz in the mixture;
- holding the silicon wafer in the holder and immersing the silicon wafer in the etchant mixture, wherein said etchant mixture comprises an alkaline etchant and a wetting agent;
- and
- applying ultrasonic waves to the etchant mixture.
A method of etching to form a silicon contact test structure, comprising the steps of:
- providing a silicon substrate;
- forming a silicon contact test structure on said substrate by exposing said substrate to an etchant mixture, wherein said mixture includes an alkaline etchant and a wetting agent;
- and
- simultaneously applying ultrasonic waves at a frequency of about 20 to 40 kiloHertz to the etchant mixture during at least a portion of said etching.
Dependencies are inferred from the claim text.