Electrically isolated collimator and method

A method of sputter deposition of a thin film on a semiconductor wafer in an evacuable chamber, the method comprising:

• mounting a sputter target in the chamber;
• mounting the wafer in the chamber opposite said target;
• interposing a collimator between the target and the wafer, and mounting the collimator within the chamber in an electrically isolated manner so the collimator takes on a floating electrical potential within the chamber during plasma operations in which the chamber is evacuated;
• creating a vacuum in the chamber;
• and
• generating a plasma within the chamber to cause the sputter deposition of a thin film of target material on the wafer.

An apparatus for sputter deposition of a material on a semiconductor wafer, the apparatus comprising:

• a chamber adapted for creation of a vacuum therein and provided with a supply of an ionizable gas;
• a target of said material disposed in said chamber;
• a semiconductor wafer support disposed in said chamber spaced from said target;
• and
• a collimator interposed between said target and said wafer support and mounted within said chamber in an electrically isolated manner such that said collimator takes on a floating electrical potential within said chamber during plasma operations performed therein at vacuum.

An apparatus for sputter deposition of a material on a semiconductor wafer, the apparatus comprising:

• a grounded chamber adapted for creation of a vacuum therein and provided with a supply of an ionizable gas;
• a negatively-biased target of said material disposed in said chamber;
• a negatively-biased semiconductor wafer support disposed in said chamber spaced from said target;
• and
• a collimator interposed between said target and said wafer support and mounted within said chamber in an electrically isolated manner such that said collimator takes on a floating electrical potential within said chamber during plasma operations performed therein at vacuum.

An apparatus for sputter deposition of a material on a semiconductor wafer, the apparatus comprising:

• a chamber adapted for creation of a vacuum therein, having at least a portion thereof at a first potential and provided with a supply of an ionizable gas;
• a target of said material at a second, different potential disposed in said chamber;
• a semiconductor wafer support disposed in said chamber spaced from said target;
• and
• a collimator electrically isolated from said chamber and from bias sources external to said chamber during plasma operations performed therein and interposed between said target and said wafer support.

A method for sputter deposition of a material on a semiconductor wafer, the method comprising:

• providing an evacuable chamber, at least a portion of which is at a first potential;
• providing a semiconductor wafer in the chamber;
• providing a source of said material for said deposition spaced from said wafer in said chamber;
• sputtering said material with a gas plasma resident in said chamber;
• providing a collimating apparatus within said chamber and collimating trajectories of sputtered material particles to features on the surface of said wafer with said collimating apparatus to form a film of said material on said wafer;
• and
• electrically isolating said collimating apparatus from said first potential and from bias sources external to said chamber during plasma operations performed within said chamber at vacuum.

A method for sputter deposition of a material on a semiconductor wafer including high aspect-ratio features on the surface thereof, the method comprising:

• providing an evacuable chamber having at least a portion thereof at a first potential;
• providing a wafer including said high aspect-ratio features within said chamber at a second potential different from said first potential;
• providing a source of said material for said deposition spaced from said wafer in said chamber;
• sputtering said material with a gas plasma resident in said chamber;
• providing a collimating apparatus within said chamber and collimating trajectories of sputtered material particles to features on the surface of said wafer with said collimating apparatus to form a film of said material on said wafer;
• electrically isolating said collimating apparatus from said first potential and from bias sources external to said chamber during plasma operations performed within said chamber at vacuum;
• and
• substantially reducing pinch off of said material proximate entry regions to said high aspect ratio features with said second potential.

A method for sputter deposition of a material on a semiconductor wafer including recesses in the surface thereof, comprising:

• providing a semiconductor wafer in an evacuable chamber;
• providing a source of said material for said deposition spaced from said wafer in said chamber;
• sputtering said material with a gas plasma resident in said chamber;
• maintaining said gas plasma at a floating electrical potential;
• providing a collimating apparatus within said chamber and collimating trajectories of sputtered material particles to features on the surface of said wafer with said collimating apparatus at a potential associated with said floating electrical potential of said gas plasma to form a film of said material on said wafer and within said recesses;
• and
• electrically isolating said collimating apparatus from said chamber and from bias sources external to said chamber during plasma operations performed within said chamber at vacuum.

A method for sputter deposition of a target material on a semiconductor wafer, the method comprising:

• providing the target material and the wafer spaced apart from one another in a sputter deposition chamber;
• providing a collimator between the target material and the wafer in the chamber;
• electrically isolating the collimator from the chamber and any bias sources external to the chamber during plasma operations under vacuum within the chamber;
• evacuating the chamber;
• inducing a voltage differential between the chamber and the target material to generate a plasma within the chamber;
• bombarding the target material with ions from the plasma to dislodge material particles therefrom;
• collimating trajectories of the dislodged material particles to features on the wafer with the collimator to form a film of the target material on the wafer;
• operating the collimator at a floating electrical potential during sputter deposition so the plasma has more energy than if the collimator were operated at ground potential and so the plasma freely flows through the collimator;
• operating the chamber at a reduced pressure as a consequence of the collimator being operated at a floating electrical potential and the plasma thereby having relatively more energy;
• and
• biasing the wafer with a negative rf-voltage to substantially enhance the presence of the free-flowing plasma near the wafer and thereby reduce pinch-off of features on the wafer.

A method for sputter deposition of a target material on a semiconductor wafer, the method comprising:

• providing the target material and the wafer spaced apart from one another in a sputter deposition chamber;
• generating a plasma within the chamber;
• bombarding the target material with ions from the plasma to dislodge material particles therefrom;
• at a floating electrical potential of the plasma, collimating trajectories of the dislodged material particles to features on the wafer to form a film of the target material on the wafer;
• and
• operating the chamber at a pressure that is less than a pressure the chamber would be operated at if trajectories of the dislodged material were collimated at an electrical potential of the chamber.

A method for sputter deposition of a target material on a semiconductor wafer, the method comprising:

• providing the target material and the wafer spaced apart from one another in a sputter deposition chamber;
• generating a plasma within the chamber;
• bombarding the target material with ions from the plasma to dislodge material particles therefrom;
• at a floating electrical potential of the plasma, collimating trajectories of the dislodged material particles to features on the wafer to form a film of the target material on the wafer;
• and
• biasing the wafer to substantially enhance the presence of the plasma near the wafer.