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Reduced number of masks for IC device with stacked contact levels

  • US 8,598,032 B2
  • Filed: 03/16/2011
  • Issued: 12/03/2013
  • Est. Priority Date: 01/19/2011
  • Status: Active Grant
First Claim
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1. A method, for use with a three-dimensional stacked IC device having a stack of contact levels at an interconnect region, for creating interconnect contact regions aligned with and exposing landing areas at the contact levels, the method comprising:

  • using a set of N etch masks for creating up to and including 2N levels of interconnect contact regions at the stack of the contact levels, each mask comprising mask and etch regions, N being an integer equal to at least 2, x being a sequence number for the masks so that for one mask x=1, for another mask x=2, and so forth through x=N;

    removing at least a portion of any upper layer overlying the stack of the contact levels at the interconnect region;

    etching the interconnect region N times using said masks in a chosen order to create contact openings extending from a surface layer to each contact level, the contact openings being aligned with and providing access to the landing areas at each of the 2N contact levels; and

    the etching step comprising etching through 2x−

    1
    contact levels for each mask of sequence number x;

    whereby electrical conductors can be formed through the contact openings to contact the landing areas at the contact levels.

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