Method for reducing or eliminating de-lamination of semiconductor wafer film layers during a chemical mechanical planarization process
View Patent ↗A method for preventing de-lamination of semiconductor wafer film stacks during a linear belt-type chemical mechanical planarization (CMP) process is provided. The method implements a pulsed polishing head rotation during a CMP process to maintain a slurry distribution across the width of a belt pad. The slurry distribution is maintained in a manner that prevents de-lamination of a wafer film having weak adhesion characteristics. Thus, the pulsed polishing head rotation implemented by the method reduces de-lamination of low-K material film layers during the CMP process.
1. A method for operating a linear-type chemical mechanical planarization (CMP) system, comprising:
moving a belt pad having a coverage of a slurry in a linear direction;
affixing a wafer to a polishing head;
rotating a polishing head and the wafer affixed thereto in a first direction about an axis extending through a centerpoint of the polishing head and perpendicular to an angular direction of rotation of the polishing head;
applying the rotating wafer to the moving belt pad, application of the rotating wafer to the moving belt pad causing a dry wake region to form on a portion of the belt pad having traversed below the rotating wafer; and
controlling the dry wake region to maintain a uniform time-averaged slurry distribution across the belt pad.
2. A method for operating a linear-type CMP system as recited in claim 1 , wherein the slurry flows through longitudinal grooves and cross-grooves to cover the belt pad.
3. A method for operating a linear-type CMP system as recited in claim 1 , wherein the uniform time-averaged slurry distribution across the belt pad includes a uniform time-averaged slurry volume across the belt pad, a uniform time-averaged slurry chemistry across the belt pad, and a uniform time-averaged slurry thermal load across the belt pad.
4. A method for operating a linear-type CMP system as recited in claim 1 , wherein controlling the dry wake region includes,
(a) rotating the polishing head and wafer in the first direction for a particular duration,
(b) following operation (a), rotating the polishing head and wafer in a second direction for the particular duration, and
(c) repeating operations (a) and (b).
5. A method for operating a linear-type CMP system as recited in claim 4 , wherein the wafer remains applied to the moving belt pad when changing the polishing head and wafer direction of rotation.
6. A method for operating a linear-type CMP system as recited in claim 1 , wherein controlling the dry wake region includes,
(a) rotating the polishing head and wafer in the first direction through a particular angular distance,
(b) following operation (a), rotating the polishing head and wafer in a second direction through the particular angular distance, and
(c) repeating operations (a) and (b).
7. A method for operating a linear-type CMP system as recited in claim 6 , wherein the wafer remains applied to the moving belt pad when changing the polishing head and wafer direction of rotation.