High aspect ratio low resistivity lines/vias by surface diffusion
AssigneeInternational Business Machines Corporation
InventorsRajiv Vasant Joshi, Manu Jamnadas Tejwani, Kris Venkatraman Srikrishnan
Life of this patent
Estimating the term…
Abstract
A method of filling high aspect ratio vias and lines on the upper surface of a substrate prevents voids from being formed therein. The method comprises the steps of filling the lines and vias by surface diffusion at room temperature and at a pressure of 1 Torr. Step coverage of the fill material and sputtering parameters are chosen to satisfy a predetermined relationship. The upper surface of the substrate comprises regions of exposed aluminum, aluminum-copper or copper alloys. After filling the vias and lines, the exposed aluminum, aluminum-copper or copper alloys are reacted with a gas containing germanium to form a germanium alloy over the upper surface of the substrate.
Claims2
A method of filling at least one of high aspect ratio vias and lines, said high aspect ratio being greater than or equal to four, on a substrate having an upper surface and for preventing voids being formed in said one of high aspect ratio vias and lines, said method comprising the step of:
- filling said one of high aspect ratio vias and lines by surface diffusion at room temperature and at a pressure of less than 1 Torr with a sputtered material, step coverage of said material and sputtering parameters satisfying a predetermined relationship comprising:
- SC=K.multidot.M.sub.P.sup.-a .multidot.M.sub.W.sup.-a .multidot.P.sup.-b .multidot.A.sub.R.sup.-c .multidot..theta..sup.-d .multidot.T.sup.e
- where
- SC is the step coverage of the material;
- M.sub.P is the melting point of the material;
- M.sub.W is the atomic weight of the material;
- A.sub.R is the aspect ratio of said vias and lines;
- P is operating pressure (mT);
- T is substrate temperature (.degree. C.);
- .theta. is ARCTAN (D1-D2/2H);
- K is a material dependent constant;
- a is 0.2;
- b is in a range 0.25-0.51
- c is in a range 0.21-0.27
- d less than or equal to 0.1;
- e is in a range 0.6-0.7;
- K is in a range 3-5;
- D1 comprises a diameter of a sputtering target of the material;
- D2 comprises a diameter of substrate;
- and
- H is a distance between said sputtering target and said substrate,
- said upper surface having regions containing a group consisting of at least one of exposed aluminum, aluminum-copper and copper alloys and
- reacting said at least one of aluminum, aluminum-copper and copper alloys with a gas containing germanium to form a germanium alloy on said upper surface.
Dependencies are inferred from the claim text.