1. A process for making a high iron content ferric chloride solution, comprising:
oxidizing a hydrochloric acid and iron containing pickling liquor to form a ferric chloride solution having an iron content of about 15 weight percent or less;
evaporating water and free hydrochloric acid from the ferric chloride solution to increase the iron content to about 23 to 26 weight percent; and
reconstituting the ferric chloride solution having the iron content of about 23 to 26 weight percent by diluting the ferric chloride solution having the iron content of about 23 to 26 weight percent to a desired iron content with water.
2. The process of claim 1, further comprising reconstituting the ferric chloride solution having the iron content of about 23 to 26 weight percent by diluting the ferric chloride solution having the iron content of about 23 to 26 weight percent to a desired iron content with water and hydrochloric acid.
3. The process of claim 1 wherein the iron containing pickling liquor comprises Fe2+ and Fe3+ ions; and oxidizing the iron containing pickling liquor is effective to oxidize the Fe2+ ions to the Fe3+ ions.
4. The process of claim 1, wherein evaporating the water and the free hydrochloric acid comprises evaporating the ferric chloride solution.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A semiconductor device comprising:
a semiconductor substrate;
a first insulating film that is formed over the semiconductor substrate;
a capacitor that is formed over the first insulating film and is formed by sequentially stacking a lower electrode, a capacitor dielectric film, and an upper electrode;
a second insulating film that is formed over the capacitor and has a hole including the entire region of the upper electrode in plan view; and
a conductor plug that is formed in the hole and contains tungsten.
2. The semiconductor device according to claim 1,
wherein the center of gravity of the hole and the center of gravity of the upper electrode coincide with each other in plan view.
3. The semiconductor device according to claim 1,
wherein the shape of the hole is similar to the shape of the upper electrode in plan view.
4. The semiconductor device according to claim 1,
wherein the hole is larger than a lower surface of the upper electrode in plan view.
5. The semiconductor device according to claim 1,
wherein the conductor plug includes a tungsten film having a recess in an upper surface of the tungsten film, and a copper wiring is formed in the recess.
6. The semiconductor device according to claim 5, further comprising:
a third insulating film that is formed over the second insulating film and has a wiring groove on the hole, the wiring groove being continuous to the recess,
wherein the copper wiring is formed in the recess and the wiring groove.
7. The semiconductor device according to claim 6,
wherein the wiring groove has a width larger than a width of the recess.
8. The semiconductor device according to claim 1, further comprising:
an opening that is formed in the first insulating film under the capacitor and includes the entire region of the lower electrode in plan view, and
a conductor that contains tungsten and is embedded in the fast opening.
9. The semiconductor device according to claim 8, further comprising:
an element isolation insulating film that is formed in the semiconductor substrate,
wherein the opening is formed on the element isolation insulating film.
10. The semiconductor device according to claim 8, further comprising:
an antioxidation insulating film that is formed over the conductor and the first insulating film and suppresses oxidation of the conductor, and,
wherein the capacitor is formed on the antioxidation insulating film.
11. The semiconductor device according to claim 1, further comprising:
an impurity diffusion region that is formed in the semiconductor substrate;
a contact plug that is embedded in the first insulating film over the impurity diffusion region and is electrically connected to the impurity diffusion region;
an interlayer insulating film that is formed over the first insulating film and has an opening on the contact plug, the opening including the entire region of the lower electrode in plan view; and
a conductor that is embedded in the opening, the conductor containing tungsten and being electrically connected to the contact plug and the lower electrode of the capacitor which is formed on the conductor.
12. The semiconductor device according to claim 11, further comprising:
a conductive film that is formed on the conductor so to fill the opening,
wherein the conductor is formed up to a halfway position of the opening in a depth direction, and
the capacitor is formed on the conductive film.
13. The semiconductor device according to claim 12,
wherein the conductive film has a first upper surface right under the capacitor, a side face that is connected to the first upper surface and is flush with a side face of the lower electrode, and a second upper surface connected to the side face and extending in a parallel to a surface of the substrate.
14. The semiconductor device according to claim 1,
wherein a plurality of the capacitors and a plurality of the conductor plugs are provided, and
a radioactive ray coming toward the capacitor dielectric film right under the upper electrode of one of the capacitors is blocked by the conductor plug on the other capacitor.
15. The semiconductor device according to claim 14,
wherein among radiation that is incident on the capacitor dielectric film without being blocked by the conductor plug on the other capacitor, the radiation having the maximum incident angle has a tangent of the incident angle, the tangent being equal to a value (a\u2212d)(2(b\u2212e)), where a represents a distance between lower surfaces of the upper electrodes of adjacent capacitors, b represents a distance between the lower surface of the upper electrode and an upper surface of the conductor plug, d represents a distance between lower surfaces of adjacent conductor plugs, and e represents a distance between the upper surface and the lower surface of the conductor plug.
16. The semiconductor device according to claim 15,
wherein the tangent is represented by (c+d)(2e) where c represents a distance between the upper surfaces of the adjacent conductor plugs.
17. The semiconductor device according to claim 1,
wherein another conductor plug containing tungsten is provided in the second insulating film on a side of the capacitor, and
radiation coming toward the capacitor dielectric film right under the upper electrode is blocked by the another conductor plug.
18. The semiconductor device according to claim 1, further comprising:
a blocking body formed above the second insulating film and containing tungsten,
wherein radiation coming toward the capacitor dielectric film right under the upper electrode is blocked by the blocking body.
19. The semiconductor device according to claim 1,
wherein the semiconductor substrate has a cell region where a plurality of the capacitors are formed, and
a conductor ring containing tungsten, the conductor ring having a height at least reaching the upper surface of the second insulating film and surrounding the cell region in plan view, is provided on the semiconductor substrate.
20. A method for producing a semiconductor device comprising:
forming a first insulating film on a semiconductor substrate;
forming, on the first insulating film, a capacitor by sequentially stacking a lower electrode, a capacitor dielectric film, and an upper electrode;
forming a second insulating film that covers the capacitor;
forming a hole in the second insulating film by pattering the second insulating film, the hole including the entire region of the upper electrode in plan view; and
forming, in the hole, a conductor plug that is electrically connected to the upper electrode and that contains tungsten.