No coat backside wafer grinding process
AssigneeDelco Electronics Corporation
InventorsMichael R. Earl, Russell A. Detterich, Robert A. Yancey
Life of this patent
Estimating the term…
Abstract
A silicon wafer grinding apparatus for grinding a backside surface of a semiconductor wafer that includes integrated circuit chips patterned on a frontside surface of the wafer. The apparatus includes a plurality of chuck tables that secure a plurality of wafers to be ground. Each chuck table includes a cushioned rubber pad secured to the table and an interface with the frontside surface of the wafer. An organic acid cooling fluid is utilized during the grinding procedure to prevent silicon particles and residue from being adhered to the metal bond pads of the integrated circuit chips.
Claims19
An apparatus for grinding a backside surface of an integrated circuit wafer, said apparatus comprising:
- a grind chuck table, said grind chuck table including a plurality of holes, said grind chuck table further including a cushion pad secured to a surface of the grind chuck table, said cushion pad including a plurality of holes that are aligned with and in vacuum communication with the holes in the grind chuck table, said grind chuck table further including vacuum means for applying vacuum suction through the plurality of holes in the grind chuck table and the cushion pad so as to secure the wafer to the grind chuck table such that a frontside surface of the wafer is positioned against the cushion pad and a backside surface of the wafer is exposed to be grinded, said cushion pad providing cushioning that is effective to prevent damage to integrated circuits on the wafer during a grinding process;
- and
- means for providing a cooling fluid to the grind chuck table, said cooling fluid preventing residue released from the wafer during the grinding process from adhering to the wafer.
An apparatus for grinding a backside surface of integrated circuit silicon wafers, said apparatus comprising:
- a plurality of grind chuck tables, each of the grind chuck tables including a plurality of holes, each of the grind chuck tables further including a rubber cushion pad secured to a surface of the grind chuck tables, each rubber cushion pad including a plurality of holes that are aligned with and in vacuum communication with the holes in the grind chuck table, each of the grind chuck tables further including vacuum means for applying vacuum suction through the plurality of holes in the grind chuck table and the cushion pad so as to secure the silicon wafers to the cushion pads such that a frontside surface of the wafers is positioned against the cushion pad and a backside surface of the wafers are exposed to be grinded, said cushion pad providing cushioning that is effective to prevent damage to integrated circuits on the wafer during a grinding process;
- and
- means for providing a cooling fluid to the grind chuck tables, said means for providing the cooling fluid including at least one pH sensor for sensing the pH of the cooling fluid, said cooling fluid being a mixture of a citric acid and deionized water, wherein the citric acid prevents residue released from the wafer during the grinding process from adhering to metal bond pads of the wafer.
An apparatus for providing cooling fluid to a grinding machine that grinds an integrated circuit wafer, said apparatus comprising:
- a source of organic acid;
- a source of deionized water;
- mixing means for mixing the organic acid with the deionized water in a predetermined mixture so as to provide a cooling fluid having a predetermined pH;
- a first pH sensor, said first pH sensor providing a signal indicative of the pH level of the cooling fluid mixture;
- a pH controller responsive to the pH level signal from the first pH sensor, said pH controller controlling a flow of the organic acid so as to control the pH level of the mixture of the cooling fluid;
- a second pH sensor, said second pH sensor also sensing the pH level of the mixture and providing a signal indicative of the pH level of the mixture;
- a pH analyzer responsive to the pH level signal from the second pH sensor;
- a plurality of alarm switches, said pH analyzer providing a signal to the plurality of alarm switches if the pH level of the mixture is outside a predetermined range;
- and
- means for directing the cooling fluid to the integrated circuit wafer.
A method of grinding a backside surface of a wafer where a frontside surface of the wafer includes a plurality of defined integrated circuit chips, said method comprising the steps of:
- providing a grind chuck table, said step of providing a grind chuck table including the step of securing a cushioned pad to a grind surface of the grind chuck table, said step of providing a grind chuck table further including the step of providing a plurality of holes through the grind chuck table and the cushion pad where the holes in the grind chuck table and the holes in the cushion pad are aligned and are in a fluid communication with a vacuum source;
- securing the wafer to the grind chuck table such that the frontside surface of the wafer is positioned against the cushioned pad and the backside surface of the silicon wafer is exposed for grinding, said step of securing the wafer to the grind chuck table including using the vacuum source to provide suction against the front side surface of the wafer through the plurality of holes in the grind chuck table and the cushion pad, said cushion pad providing cushioning that is effective to prevent damage to integrated circuits on the wafer during a grinding process;
- moving the grind chuck table relative to a grinding surface so as to remove portions of the wafer;
- and
- cooling the grind chuck table and grinding surface with a cooling solution.
Dependencies are inferred from the claim text.