Anisotropic conductive film with carbon-based conductive regions having void space and related semiconductor device assemblies and methods
An anisotropic conductive film (ACF) is formed with an ordered array of discrete regions that include a conductive carbon-based material. The discrete regions, which may be formed at small pitch, are embedded in at least one adhesive dielectric material. The ACF may be used to mechanically and electrically interconnect conductive elements of initially-separate semiconductor dice in semiconductor device assemblies. Methods of forming the ACF include forming a precursor structure with the conductive carbon-based material and then joining the precursor structure to a separately-formed structure that includes adhesive dielectric material to be included in the ACF. Sacrificial materials of the precursor structure may be removed and additional adhesive dielectric material formed to embed the discrete regions with the conductive carbon-based material in the adhesive dielectric material of the ACF.
1. An anisotropic conductive film, comprising:
a pattern of discrete regions within a substantially continuous region of at least one adhesive dielectric material, each one of the discrete regions of the pattern being mutually laterally spaced from other discrete regions by at least one predetermined pitch, the discrete regions comprising a conductive carbon-based material,
the discrete regions extending partially through the at least one adhesive dielectric material and the at least one adhesive dielectric material above and below the discrete regions,
at least some of the discrete regions each defining a void space within the conductive carbon-based material, and
the void space extending into the conductive carbon-based material from a surface of the conductive carbon-based material.
2. The anisotropic conductive film of claim 1 , further comprising at least one seed material on sidewalls of the conductive carbon-based material of the at least some of the discrete regions.
3. The anisotropic conductive film of claim 1 , wherein the conductive carbon-based material of the at least some of the discrete regions is directly adjacent the at least one adhesive dielectric material.
4. The anisotropic conductive film of claim 1 , further comprising at least one seed material substantially on only sidewalls of the conductive carbon-based material of the at least some of the discrete regions.
5. The anisotropic conductive film of claim 1 , further comprising at least one seed material another surface of the conductive carbon-based material of the at least some of the discrete regions, the another surface being opposite the surface from which the void space extends.
6. The anisotropic conductive film of claim 1 , wherein a dimension from the surface of the conductive carbon-based material to an opposing surface of the conductive carbon-based material is less than about 0.4 μm.
7. The anisotropic conductive film of claim 1 , wherein the at least one predetermined pitch is less than about 2 μm.
8. The anisotropic conductive film of claim 1 , wherein the conductive carbon-based material consists substantially of graphene.
9. A semiconductor device assembly, comprising:
a semiconductor die comprising conductive structures spaced along a surface of the semiconductor die;
an additional semiconductor die comprising additional conductive structures spaced along a surface of the additional semiconductor die; and
an anisotropic conductive film interposed between the semiconductor die and the additional semiconductor die, the anisotropic conductive film comprising:
a pattern of discrete regions within a substantially continuous region of at least one adhesive dielectric material, each one of the discrete regions of the pattern being mutually laterally spaced from other discrete regions by at least one predetermined pitch, the discrete regions comprising a conductive carbon-based material, the discrete regions extending partially through the adhesive dielectric material, and the adhesive dielectric material above and below the discrete regions, and
at least some of the discrete regions individually defining a void space within the conductive carbon-based material, the void space extending into the conductive carbon-based material from a surface of the conductive carbon-based material.
10. The semiconductor device assembly of claim 9 , further comprising a seed material lining outer vertical sidewalls of the conductive carbon-based material.
11. The semiconductor device assembly of claim 9 , wherein the surface from which the void space extends into the conductive carbon-based material is one of an upper surface and a lower surface of the conductive carbon-based material.
12. The semiconductor device assembly of claim 11 , further comprising a seed material lining another one of the upper surface and the lower surface of the conductive carbon-based material.
13. The semiconductor device assembly of claim 9 , wherein some of the discrete conductive-regions are not in physical contact with any of the conductive structures of the semiconductor die and are not in physical contact with any of the additional conductive structures of the additional semiconductor die.
14. The semiconductor device assembly of claim 9 , wherein the conductive carbon-based material of the at least some of the discrete regions is spaced from the adhesive dielectric material by a seed material.
15. The semiconductor device assembly of claim 9 , further comprising a seed material directly between:
at least one of the conductive structures of the semiconductor die; and
the conductive carbon-based material of the at least some of the discrete conductive regions.
16. The semiconductor device assembly of claim 9 , wherein the at least some of the discrete conductive-regions consist substantially of the conductive carbon-based material defining the void space therein.
17. A method for forming an anisotropic conductive film structure, the method comprising:
forming a precursor structure, comprising:
forming a dielectric material on a sacrificial base material;
defining discrete openings in the dielectric, material, the discrete openings being mutually laterally spaced by at least one predetermined pitch;
forming a seed material in the discrete openings, and conformally forming a conductive carbon-based material on the seed material, in at least some of the discrete openings, the conductive carbon-based material defining a void space;
forming an additional structure comprising an adhesive dielectric material on an additional base material;
joining the precursor structure, on a surface thereof opposite the sacrificial base material, to the additional structure;
removing the sacrificial base material;
removing the dielectric material to form additional openings; and
forming additional adhesive dielectric material in the additional openings to electrically insulate discrete regions comprising the conductive carbon-based material and the seed material, the discrete regions extending partially through the additional adhesive dielectric material and the adhesive dielectric material or the additional adhesive dielectric material above and below the discrete regions, at least some of the discrete regions each defining the void space within the conductive carbon-based material, the void space extending into the conductive carbon-based material from a surface of the conductive carbon-based material.
18. The method of claim 17 , wherein:
forming the discrete openings in the dielectric material comprises exposing portions of a surface of the sacrificial base material; and
forming the seed material in the discrete openings comprises conformally forming the seed material on the portions of the surface of the sacrificial base material and on sidewalls of the dielectric material.
19. The method of claim 17 , further comprising, before forming the additional adhesive dielectric material in the additional openings, removing at least a portion of the seed material.
20. The method of claim 17 , further comprising, after removing the sacrificial base material, removing the seed material from above a horizontal surface of the conductive carbon-based material, the horizontal surface being opposite the surface from which the void space extends into the carbon-based material.
21. An anisotropic conductive film, comprising:
a pattern of discrete regions within a substantially continuous region of at least one adhesive dielectric material, each one of the discrete regions of the pattern being mutually laterally spaced from other discrete regions by at least one predetermined pitch, the discrete regions comprising a conductive carbon-based material,
at least some of the discrete regions each defining a void space within the conductive carbon-based material, and
the void space partially extending into the conductive carbon-based material from a surface of the conductive carbon-based material.