Semiconductor structure with insulated through silicon via
View Patent ↗Techniques described herein generally relate to laminated semiconductor structures. In some examples, method of forming a polyimide film are described. An example method may include forming a through hole in a laminated semiconductor structure that includes multiple stacked semiconductor layers. An inner wall of the laminated semiconductor structure can define the through hole. The inner wall can be exposed to a solution including a salt of polyamic acid and/or a polyamic acid that can be precipitated on the inner wall. The precipitated polyamic acid on the inner wall can be transformed into a polyimide film substantially coating the inner wall.
1. A method of forming a polyimide film in a through hole, the method comprising:
forming a through hole in a laminated semiconductor structure that includes multiple stacked semiconductor layers, wherein an inner wall of the laminated semiconductor structure defines the through hole and the through hole penetrates through the laminated semiconductor structure and through the multiple stacked semiconductor layers;
exposing the inner wall to a solution that includes a salt of polyamic acid;
precipitating polyamic acid on the inner wall; and
transforming the precipitated polyamic acid on the inner wall into a polyimide film that substantially coats the inner wall.
2. The method of claim 1 , wherein the precipitated polyamic acid is transformed into a polyimide film in response to heating and dehydrating the laminated semiconductor structure that includes the precipitated polyamic acid.
3. The method of claim 1 , further comprising forming a conductive element on the polyimide film, wherein the polyimide film substantially electrically insulates the conductive element from the multiple stacked semiconductor layers of the laminated semiconductor structure.
4. The method of claim 1 , further comprising:
masking electrical contact areas of the inner wall that are within the through hole with a mask prior to exposing the inner wall to the solution to prevent precipitation of polyamic acid on the electrical contact areas; and
removing the mask within the through hole from the inner wall prior to forming the conductive element on the polyimide film to permit the subsequently formed conductive element to directly contact the electrical contact areas that are exposed by removing the mask.
5. The method of claim 1 , wherein forming a through hole in the laminated semiconductor structure includes drilling through the multiple stacked semiconductor layers of the laminated semiconductor structure using a laser to form the inner wall that defines the through hole.
6. The method of claim 5 , further comprising removing desmears from the inner wall.
7. The method of claim 1 , further comprising:
forming a second through hole that penetrates through a first semiconductor layer subsequently laminated together with one or more other semiconductor layers to form the laminated semiconductor structure, wherein an inner wall of the first semiconductor layer defines the second through hole;
exposing the inner wall of the first semiconductor layer to a solution that includes a salt of polyamic acid;
precipitating polyamic acid on the inner wall of the first semiconductor layer; and
transforming the precipitated polyamic acid on the inner wall of the first semiconductor layer into a polyimide film that substantially coats the inner wall of the first semiconductor layer.
8. A method of forming a polyimide film in a through hole, the method comprising:
forming a through hole in a laminated semiconductor structure that includes multiple stacked semiconductor layers, wherein an inner wall of the laminated semiconductor structure defines the through hole and the through hole penetrates through the laminated semiconductor structure and through the multiple stacked semiconductor layers;
exposing the inner wall to a solution that includes a salt of polyamic acid;
passing an electric current through the solution;
decomposing the solution using the electric current;
precipitating polyamic acid on the inner wall; and
transforming the precipitated polyamic acid on the inner wall into a polyimide film that substantially coats the inner wall.
9. The method of claim 8 , wherein the precipitated polyamic acid is transformed into a polyimide film in response to heating and dehydrating the laminated semiconductor structure that includes the precipitated polyamic acid.
10. The method of claim 8 , further comprising forming a conductive element on the polyimide film, wherein the polyimide film substantially electrically insulates the conductive element from the multiple stacked semiconductor layers of the laminated semiconductor structure.
11. A method of forming a polyimide film in a through hole, the method comprising:
forming a through hole in a laminated semiconductor structure that includes multiple stacked semiconductor layers, wherein an inner wall of the laminated semiconductor structure defines the through hole and the through hole penetrates through the laminated semiconductor structure and through the multiple stacked semiconductor layers;
depositing an insulative film on the inner wall within the through hole;
exposing the laminated semiconductor structure to a solution that includes a salt of polyamic acid after the insulative film is deposited on the inner wall;
precipitating polyamic acid on the insulative film; and
transforming the precipitated polyamic acid on the inner wall into a polyimide film that substantially coats the inner wall.
12. The method of claim 11 , wherein the insulative film comprises silicon dioxide (SiO 2 ) or titanium nitride (TiN).
13. The method of claim 11 , wherein the precipitated polyamic acid is transformed into a polyimide film in response to heating and dehydrating the laminated semiconductor structure that includes the precipitated polyamic acid.
14. The method of claim 11 , further comprising, prior to precipitating polyamic acid on the inner wall, passing an electric current through the solution to decompose the solution.
15. A laminated semiconductor structure comprising:
a plurality of stacked semiconductor layers with integrated circuits formed thereon, wherein the plurality of stacked semiconductor layers include a through hole that penetrates the plurality of stacked semiconductor layers;
an electrical contact area located within the through hole about a first portion of an inner wall of the laminated semiconductor structure that defines the through hole;
a polyimide film within the through hole that substantially coats the inner wall about a second portion of the inner wall, wherein the second portion is different from the first portion and the first and second portions are both located within the through hole; and
a conductive element that fills a portion of the through hole and that is in electrical contact with the electrical contact area within the through hole and that is electrically insulated from the second portion of the inner wall by the polyimide film.
16. The laminated semiconductor structure of claim 15 , wherein a thickness of the polyimide film is in a range from about 5 to about 10 micrometers.
17. The laminated semiconductor structure of claim 15 , wherein an electric permittivity of the polyimide film is in a range from about 3.0 to about 3.55 farads per meter.
18. The laminated semiconductor structure of claim 15 , wherein a dissipation factor of the polyimide film is about 0.0025%.
19. The laminated semiconductor structure of claim 15 , wherein the plurality of stacked semiconductor layers include a first layer that includes a second through hole defined by an inner wall of the first layer, and wherein the laminated semiconductor structure further comprises:
a first electrical contact area located about a first portion of the inner wall of the first layer and electrically coupled to an integrated circuit on a first side of the first layer;
a second electrical contact area located about a second portion of the inner wall of the first layer and electrically coupled to an integrated circuit on a second side of the first layer;
a polyimide film that substantially coats the inner wall of the first layer about a third portion of the inner wall of the first layer, wherein the third portion of the inner wall of the first layer is different from the first and second portions of the inner wall of the first layer; and
a conductive element that fills a portion of the second through hole in electrical contact with the first and second electrical contact areas of the inner wall of the first layer.
20. A method of forming a polyimide film in a through hole of a stacked semiconductor structure, the method comprising:
drilling through multiple stacked semiconductor layers of a laminated semiconductor structure to form a through hole, wherein each of the multiple stacked semiconductor layers includes one or more integrated circuits formed on one or both sides of each of the multiple stacked semiconductor layers;
masking electrical contact areas included on an inner wall of the laminated semiconductor structure that defines the through hole with a mask, wherein the electrical contact areas are located within the through hole;
exposing, over a predetermined time interval, the laminated semiconductor structure to a solution that comprises a salt of polyamic acid;
during exposure of the laminated semiconductor structure to the solution, passing an electric current through the solution to decompose the solution such that polyamic acid is precipitated out of the solution onto unmasked areas of the inner wall that are within the through hole to form a precipitated structure;
terminating, after completion of the predetermined time interval, exposure of the precipitated structure to the solution;
after terminating exposure of the precipitated structure to the solution, heating and dehydrating the precipitated structure to alter the precipitated polyamic acid on the unmasked areas of the inner wall into a polyimide film that substantially coats the unmasked areas of the inner wall that are within the through hole;
removing the mask from within the through hole to expose the electrical contact areas of the inner wall that are within the through hole; and
depositing a conductive element within the through hole such that the conductive element is electrically coupled to the electrical contact areas of the inner wall within the through hole and is electrically insulated from other portions of the inner wall by the polyimide film.
21. The method of claim 20 , wherein the salt of polyamic acid comprises a salt of an amine derivative.
22. The method of claim 21 , wherein the amine derivative comprises one or more of diethylamine, triethylamine, diphenylamine, or trialkylamine.
23. The method of claim 20 , wherein a solvent used to form the solution comprises one or more of methyl ethyl ketone, N-methyl-2 pyrolidone, aromatic hydrocarbon, Ethyl Cellosolve, Diisopropyl ether, ethyl acetate, chloroform, dimethyl sulfoxide, or dimethylformamide.
24. The method of claim 23 , further comprising, prior to exposing the inner wall to the solution, selecting a solvent concentration based on a desired viscosity of the solution.