Wafer chuck including self-sealing vacuum seal assemblies and methods for operating the same

A semiconductor processing apparatus, comprising:

• a wafer chuck configured to hold a wafer on a top surface thereof;
• a plurality of lift-pin holes that vertically extend through a chuck body of the wafer chuck;
• a plurality of lift pins located in the plurality of lift-pin holes;
• and
• vacuum seal assembly laterally surrounding a bottom portion of a lift pin among the plurality of lift pins, wherein the vacuum seal assembly comprises:
• a confinement matrix structure including a vertically-extending opening aligned to an overlying lift-pin hole among the plurality of lift-pin holes and an annular cavity connected to, and laterally surrounding, the vertically-extending opening, the confinement matrix structure comprising a contoured cap structure providing a first annular sloped sliding surface and a contoured base structure providing a second annular sloped sliding surface and a base opening through which the lift pin vertically extends, the contoured base structure being affixed to the contoured cap structure by at least one fastening element;
• and
• a set of ring segments located at least partly within the annular cavity and configured to form a contiguous structure annulus in a sealing state and to form multiple disjoined structures in a non-sealing state, the contiguous annulus laterally surrounding and contacting the lift pin;
• wherein a positive pressure differential between a volume underlying the vacuum seal assembly and the overlying lift-pin hole induces an upward gas flow through the vertically-extending opening that drives the set of ring segments from the non-sealing state into the sealing state;
• and
• wherein each ring segment includes an upper tapered sliding surface having a first taper angle α1 with respect to a vertical direction and a lower tapered sliding surface having a second taper angle α2 with respect to the vertical direction.

A method of operating a semiconductor processing apparatus, the method comprising:

• providing a semiconductor processing apparatus comprising a wafer chuck configured to hold a wafer on a top surface thereof, wherein a plurality of lift-pin holes vertically extends through a chuck body of the wafer chuck, a plurality of lift pins are located in the plurality of lift-pin holes, and a vacuum seal assembly laterally surrounds a bottom portion of a first lift pin among the plurality of lift pins and includes a confinement matrix structure having a vertically-extending opening aligned to an overlying lift-pin hole and an annular cavity laterally surrounding the vertically-extending opening and a set of ring segments located at least partly within the annular cavity;
• disposing a wafer on the top surface of the wafer chuck;
• pulling the wafer toward the top surface of the wafer chuck by providing a vacuum suction on a backside of the wafer;
• and
• forming, in the vacuum seal assembly, a vacuum seal around the first lift pin by inducing, with a positive pressure differential between a volume underlying the vacuum seal assembly and the overlying lift-pin hole, an upward gas flow through the vertically-extending opening that drives the set of ring segments from a non-sealing state in which the ring segments are mutually spaced apart and out of contact with the first lift pin into a sealing state in which the ring segments assemble into a contiguous annulus that laterally surrounds and contacts the first lift pin.