Silicon-doped titanium wetting layer for aluminum plug
First Claim
1. A method of fabricating a metal plug in a semiconductor workpiece, comprising the sequential steps of:
- providing a semiconductor workpiece which includes a first conductor or semiconductor layer and a dielectric layer overlying the first layer, whereinthe dielectric layer has an exposed outer surface, andthe dielectric layer includes a hole having a bottom at the first layer and having a side wall extending from the first layer to an aperture at the exposed outer surface;
depositing a silicon-doped titanium layer having a concentration of silicon no greater than 20% by weight, wherein the silicon-doped titanium layer is deposited so as to cover the side wall of the hole; and
depositing said metal over the silicon-doped titanium layer;
wherein the step of depositing said metal is initiated while the side wall of the hole remains covered by said silicon-doped titanium layer having an atomic molar ratio of titanium to silicon greater than 1;
2.
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Accused Products
Abstract
A process for fabricating metal plugs, such as aluminum plugs, in a semiconductor workpiece. The invention is suitable for filling narrow, high aspect ratio holes, and the invention minimizes the formation of TiAl3 or other products of interdiffusion between the plug and the wetting layer. First, an optional barrier layer is created by covering the bottom of a hole with a film containing titanium nitride doped with silicon. Second, a wetting layer is created by covering the side walls of a hole with a film containing titanium doped with silicon, in a Ti:Si molar ratio greater than 1:2. Preferably, the wetting layer is created by sputter deposition using a titanium sputtering target containing 0.1% to 20% wt silicon, most preferably 5% to 10% wt silicon. Third, the hole is filled by depositing a material consisting primarily of aluminum. The hole preferably is filled by sputter deposition using an aluminum sputtering target, optionally containing dopants such as copper. To facilitate filling the hole without voids, the aluminum sputter deposition preferably is performed "warm", i.e., with the workpiece at a temperature below the melting point of aluminum but high enough to promote reflow of the deposited material. The silicon atoms in the wetting layer inhibit the titanium from reacting with the aluminum, and the wetting layer facilitates filling the hole with the aluminum material without leaving unfilled voids.
80 Citations
13 Claims
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1. A method of fabricating a metal plug in a semiconductor workpiece, comprising the sequential steps of:
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providing a semiconductor workpiece which includes a first conductor or semiconductor layer and a dielectric layer overlying the first layer, wherein the dielectric layer has an exposed outer surface, and the dielectric layer includes a hole having a bottom at the first layer and having a side wall extending from the first layer to an aperture at the exposed outer surface; depositing a silicon-doped titanium layer having a concentration of silicon no greater than 20% by weight, wherein the silicon-doped titanium layer is deposited so as to cover the side wall of the hole; and depositing said metal over the silicon-doped titanium layer; wherein the step of depositing said metal is initiated while the side wall of the hole remains covered by said silicon-doped titanium layer having an atomic molar ratio of titanium to silicon greater than 1;
2. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification