Browse Prior Art Database

Multiple Level Integrated Circuit Rework Using Chemical Mechanical Polish and Reactive Ion Etch

IP.com Disclosure Number: IPCOM000108754D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 126K

Publishing Venue

IBM

Related People

Cruz, JL: AUTHOR [+6]

Abstract

A method of reworking defects in the advanced stages of integrated circuit processing has been developed. The method employs the use of chemical mechanical polishing (CMP) and reactive ion etch (RIE) to remove both oxide and metal layers.

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Multiple Level Integrated Circuit Rework Using Chemical Mechanical Polish and Reactive Ion Etch

       A method of reworking defects in the advanced stages of
integrated circuit processing has been developed.  The method employs
the use of chemical mechanical polishing (CMP) and reactive ion etch
(RIE) to remove both oxide and metal layers.

      Reworking metal lines before oxide deposition can be done by
two methods.  Remove the bulk of the metal using the RIE tool
followed by a metal chemical mechanical polish to reach and preserve
the underlying planarized oxide.  The metal can also be totally
removed with the polish tool, if desired.

      To rework a via level, the oxide is etched in an RIE, followed
by a chemical mechanical polish to remove the studs.

      To rework metal lines after oxide deposition, the bulk oxide is
etched in an RIE to a level of 1500 angstroms above the base of the
metal.  This is followed by bulk metal removal with the RIE tool.  To
remove any remaining metal and planarize the surface, a stud chemical
mechanical polish is added.

      Any combination of the above procedures will address any Back
End of Line (BEOL) defect.

      In the processing of today's advanced integrated circuits
(ICs), linewidth dimensions have progressed down to .5 u.  With these
tight dimensions, defects from contamination or misprocessing cause
the IC to become non-functional.  Scrapping these wafers due to
defects creates a very costly situation not only from raw materials
but from the labor intensive requirements to build a working IC as
well.  Obviously, the cost of each wafer in progress becomes higher
as the IC progresses towards completion, which we call the Back End
of Line.

      In the past, when wafers in the BEOL were found to have defects
that were beyond the normal rework routine of the step, the wafers
were scrapped.  Many different rework routines including wet chemical
etch backs and reactive ion etch were tried but none resolved the
problem to the point where the end result was a working integrated
circuit.

      A new rework procedure was required for the BEOL levels that
could remove the defects without causing damage to the underlying
structures.  Wet chemicals such as sulfuric or hydrofluoric acid are
good at removing certain types of particles or defects but also cause
irreparable damage to the sub-structure.  Reactive ion etching can be
more selective than wet etches but typically results in an over-etch
situation to completely remove the defect.

      There are typically two types of defect-related problems.  One
is the sin...