An active thermal interposer (ATI) device for use in testing integrated circuit device under test (DUT) having thermal isolation structures. The ATI device includes a formation having a first surface and a second surface, wherein the first surface is operable to be disposed adjacent to a cold plate, and a plurality of heating zones defined across a second surface of the formation, the plurality of heating zones operable to be controlled by a thermal controller to selectively heat and maintain respective temperatures thereof, the plurality of heating zones operable to heat a plurality of areas of the DUT when the second surface of the formation is disposed adjacent to an interface surface of the DUT during testing of the DUT. The ATI device includes a plurality of thermal resistance structures configured to resist thermal conductance between the plurality of heating zones.