Patent Number: 6,309,975

Title: Methods of making implanted structures

Abstract: Methods are disclosed for forming shaped structures of silicon-containingmaterial with ion implantation and an etching process which is selectiveto silicon-containing material implanted to a certain concentration ofions or with an etching process which is selective to relativelyunimplanted silicon-containing material. In general, the methods initiallyinvolve providing a layer of silicon-containing material such aspolysilicon or epitaxial silicon on a semiconductor substrate. The layerof silicon-containing material is then masked, and ions are implanted intoexposed portions of the layer of silicon-containing material. The mask isremoved, and the aforementioned selective etching process is conducted toresult in one of an implanted and a relatively unimplanted portion of thelayer of silicon-containing material being etched away and the other leftstanding to form a shaped structure of silicon-containing material. Onepreferred selective etching process uses an etchant solution comprising aselected weight percentage of tetramethyl ammonium hydroxide in deionizedwater. The etchant solution etches relatively unimplantedsilicon-containing material implanted up to 60 times faster than it etchessilicon-containing material implanted to beyond a threshold concentrationof ions. The various methods are used to form raised shaped structures,shaped openings, polysilicon plugs, capacitor storage nodes, surround-gatetransistors, free-standing walls, interconnect lines, trench capacitors,and trench isolation regions.

Inventors: Wu; Zhiqiang (Meridian, ID), Li; Li (Meridian, ID), Figura; Thomas A. (Boise, ID), Parekh; Kunal R. (Boise, ID), Pan; Pai-Hung (Boise, ID), Reinberg; Alan R. (Boise, ID), Ma; Kin F. (Boise, ID)

Assignee:

International Classification:

Expiration Date: 10/32013