Integrated circuit packages including a high thermal conductivity material in 3 dimensional die stacks

A microelectronic assembly, comprising:

• a first die having a surface;
• second dies having a first surface and an opposing second surface, the first surfaces of the second dies electrically coupled to the surface of the first die;
• a first material, on the surface of the first die, around and between the second dies, the first material having a non-planar surface and including silicon and nitrogen, silicon and oxygen, or silicon, nitrogen, and carbon;
• a second material on the non-planar surface of the first material and the second surfaces of the second dies, the second material including titanium, titanium and nitrogen, tantalum, tantalum and nitrogen, ruthenium, or tungsten;
• a third material on the second material, the third material including one or more of copper, aluminum, aluminum and nitrogen, diamond, silicon and carbon, boron and nitrogen, and boron and arsenic;
• a fourth material on the third material, the fourth material including one or more of titanium, tantalum, gold, ruthenium, silver, aluminum and nitrogen, silicon and oxygen, silicon and nitrogen, and silicon, carbon, and nitrogen;
• and
• a substrate on the fourth material, wherein a material of the substrate includes silicon.

A microelectronic assembly, comprising:

• a first layer including a first die;
• a second layer, on the first layer, including two or more second dies and a dielectric material around and between the two or more second dies, wherein the first die is electrically coupled to the two or more second dies by interconnects having a pitch of less than 10 microns between adjacent interconnects, and wherein a surface of the dielectric material has an inconsistent topography;
• a third layer, on the second layer, including a high thermal conductivity material on the two or more second dies and on at least a portion of the dielectric material between the two or more second dies, and wherein a thickness of the high thermal conductivity material on the two or more second dies is between 1 micron and 2 microns;
• and
• a substrate on the third layer.