Etch apparatus

In a process using a hot phosphoric acid etchant ( 12 ) to etch silicon nitride on a semiconductor wafer ( 15 ) submerged in a tank ( 11 ) of the etchant ( 12 ), a recirculating path is established for the etchant ( 12 ). A porous filter ( 35 ) is coated with silicon nitride and installed in the rec...

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Bibliographische Detailangaben
Hauptverfasser:	WARREN RONALD A, BALLANTINE ARNE W, ESTES SCOTT A, FISCH EMILY E, MILO GARY
Format:	Patent
Sprache:	eng
Schlagworte:	APPARATUS FOR APPLYING LIQUIDS OR OTHER FLUENT MATERIALS TOSURFACES, IN GENERAL APPLYING LIQUIDS OR OTHER FLUENT MATERIALS TO SURFACES, IN GENERAL BASIC ELECTRIC ELEMENTS ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR ELECTRICITY GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS PERFORMING OPERATIONS SEMICONDUCTOR DEVICES SPRAYING OR ATOMISING IN GENERAL TECHNICAL SUBJECTS COVERED BY FORMER USPC TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ARTCOLLECTIONS [XRACs] AND DIGESTS TRANSPORTING
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Beschreibung
Zusammenfassung:	In a process using a hot phosphoric acid etchant ( 12 ) to etch silicon nitride on a semiconductor wafer ( 15 ) submerged in a tank ( 11 ) of the etchant ( 12 ), a recirculating path is established for the etchant ( 12 ). A porous filter ( 35 ) is coated with silicon nitride and installed in the recirculating path. As the etchant ( 12 ) in the recirculating path flows through the porous filter ( 35 ), the silicon nitride on the porous filter ( 35 ) dissolves into the etchant ( 12 ). In the tank ( 11 ), the silicon nitride dissolved in the etchant ( 12 ) significantly suppresses the etch of silicon dioxide on the semiconductor wafer ( 15 ), thereby enhancing the etch selectivity of the process. Monitoring and maintaining the concentration of the silicon nitride in the etchant ( 12 ) stabilizes the etch selectivity of the process.