Browse Prior Art Database

Novel RIE Back Planarization

IP.com Disclosure Number: IPCOM000108238D
Original Publication Date: 1992-May-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Ng, H: AUTHOR [+3]

Abstract

A process for planarizing polymer dielectrics over integrated circuit device topography while providing an etch stop for subsequent contact hole Reactive Ion Etching (RIE) is described. The process is shown schematically in Fig. 1 and begins with deposition of a conformal oxide and polymer layer (polyimide) over the device topography. Following this, low molecular weight polystyrene is spun applied on the wafer and reflowed to planarize the structure. This structure is then subjected to O2 RIE to etch back the structure and planarize the polyimide. The fact that both materials being etched back are polymeric minimizes the control necessary to perform this step. Subsequent lithographic patterning and RIE provide contact holes with a conformal etch stop (the SiO2) to the polymer O2 RIE.

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Novel RIE Back Planarization

       A process for planarizing polymer dielectrics over
integrated circuit device topography while providing an etch stop for
subsequent contact hole Reactive Ion Etching (RIE) is described.  The
process is shown schematically in Fig. 1 and begins with deposition
of a conformal oxide and polymer layer (polyimide) over the device
topography.  Following this, low molecular weight polystyrene is spun
applied on the wafer and reflowed to planarize the structure.  This
structure is then subjected to O2 RIE to etch back the structure and
planarize the polyimide.  The fact that both materials being etched
back are polymeric minimizes the control necessary to perform this
step.  Subsequent lithographic patterning and RIE provide contact
holes with a conformal etch stop (the SiO2) to the polymer O2 RIE.
Further RIE in CF4 removes the SiO2 and exposes the underlying
junctions.  CVD tungsten deposition and etch back to form contact
hole "plug" completes the process.

      In a variation on this process, the polymer can now be removed.
Conformal oxide deposition and an additional etch back step to expose
the tungsten "plugs" will result in the structure shown in Fig. 2.