METHOD FOR FORMING A SELF-ALIGNED ISOLATION TRENCH

专利名称：METHOD FOR FORMING A SELF-ALIGNED

ISOLATION TRENCH

发明人：FERNANDO GONZALEZ,DAVID

CHAPEK,RANDHIR P.S. THAKUR

申请号：US09392034申请日：19990908

公开号：US20010046753A1公开日：20011129

摘要：The present invention relates to a method for forming an isolation trenchstructure in a semiconductor substrate without causing deleterious topographicaldepressions in the upper surface thereof which cause current and charge leakage to anadjacent active area. The inventive method forms a pad oxide upon a semiconductorsubstrate, and then forms a nitride layer on the pad oxide. The nitride layer is patternedwith a mask and etched to expose a portion of the pad oxide layer and to protect anactive area in the semiconductor substrate that remains covered with the nitride layer. Asecond dielectric layer is formed substantially conformably over the pad oxide layer andthe remaining portions of the first dielectric layer. A spacer etch is then carried out toform a spacer from the second dielectric layer. The spacer is in contact with the remainingportion of the first dielectric layer. An isolation trench etch follows the spacer etch. Anoptional thermal oxidation of the surfaces in the isolation trench may be performed,which may optionally be followed by doping of the bottom of the isolation trench tofurther isolate neighboring active regions on either side of the isolation trench. Aconformal layer is formed substantially conformably over the spacer, over the remaining

portions of the first dielectric layer, and substantially filling the isolation trench.Planarization of the conformal layer follows, either by CMP or by etchback or by acombination thereof. An isolation trench filled with a structure results. The resultingstructure has a flange and shaft, the cross section of which has a nail shape in crosssection.

申请人：GONZALEZ FERNANDO,CHAPEK DAVID,THAKUR RANDHIR P.S.

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