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Characterizing Weak Spots in Dielectric Layers

IP.com Disclosure Number: IPCOM000121644D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Euen, W: AUTHOR [+4]

Abstract

For assessing the quality of dielectric layers, so-called monitor wafers are processed along with the product. These wafers are removed from the product after completion of the respective process step (oxidation, CVD) and are reworked (depositing Al, removing SiO2 from the back of the wafer, Al annealing) prior to measuring the quality of the grown/deposited layer.

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Characterizing Weak Spots in Dielectric Layers

      For assessing the quality of dielectric layers, so-called
monitor wafers are processed along with the product.  These wafers
are removed from the product after completion of the respective
process step (oxidation, CVD) and are reworked (depositing Al,
removing SiO2 from the back of the wafer, Al annealing) prior to
measuring the quality of the grown/deposited layer.

      The breakdown voltage (BDV) of the dielectric, which is
subsequently measured, reflects the product quality.

      BDV data of the node dielectric in 1M DRAMs showed, however,
that the monitor information is not indicative of the reliability of
a product (node defects after burn-in). The dielectric obviously
includes weak spots which the monitor concept, previously used
worldwide, failed to detect.

      The method proposed in this article is capable of detecting
such weak spots in the dielectric.

      The wafer is characterized in several process steps which are
described below.
      1.   Post oxidation treatment (activating weak spots)
         After oxidation, surface treatment (using, for example, DHF
(diluted hydrofluoric acid), BHF (buffered hydrofluoric acid), or
Huang A,B) reveals weak spots (structural defects, contamination) in
the oxide.  The duration of this treatment is preferably such that
the amount of oxide removed does not exceed 5 AE.
           Thus, activation does not significantly...