Shadow projection mask for ion implantation and ion beam lithography

US4448865A · kind A · utility

Assignee

• International Business Machines Corporation · US

Inventors

• Harald Bohlen · Eppelheim, DE
• Johann Greschner · Neckartenzlingen, DE
• Peter Nehmiz · Stuttgart, DE

Key dates

• Filing date: Oct 12, 1982
• Grant date: May 15, 1984
• Expiry date: Oct 12, 2002

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01L21/266
• WIPO field: Semiconductors
• WIPO sector: Electrical engineering

Abstract

A projection mask comprises a thin P.sup.+ -doped silicon layer with through holes adapted to the mask pattern, a grid supporting this layer having silicon ribs. On at least on its side facing away from the grid, the layer has a layer, which is at least as thick as to prevent the implanting of ions in the silicon layer. At least the mask surface exposed to ion irradiation is electrically and thermally conductive, and mechanically resistant. The coating of the silicon frame of the mask is such that it does not cause any mask deformation caused by temperature and/or through inherent tensions of the coating. Preferred absorbing materials are gold, silver, platinum, tungsten, and tantalum, and mechanically resistant materials are preferably carbon, molybdenum, titanium, tungsten, and tantalum. In operation, the mask with grid is placed onto the substrate to be irradiated, and subsequently blanket-illuminated with an ion beam, or scanned line-by-line until each point on the mask has been covered by the beam path.