Wafter carrier for chemical vapor deposition systems

A wafer carrier for use in a system for growing epitaxial layers on one or more wafers by chemical vapor deposition (CVD), the wafer carrier comprising:

• a body formed symmetrically about a central axis, and including a generally planar top surface that is situated perpendicularly to the central axis;
• a plurality of wafer retention pockets recessed in the body from the top surface, each of the wafer retention pockets including:
• a floor surface generally parallel to the top surface;
• and
• a peripheral wall surface surrounding the floor surface and defining a periphery of that wafer retention pocket,
• wherein each wafer retention pocket has a pocket center situated along a corresponding wafer carrier radial axis that is perpendicular to the central axis;
• and
• in each of the wafer retention pockets, a set of bumpers is positioned primarily at a distal portion of the wafer retention pocket opposite the central axis so as to maintain a gap of at least a predefined size between the peripheral wall surface at the distal portion and an edge of a wafer to be placed in the wafer retention pocket;
• wherein each of the bumpers in each of the wafer retention pockets includes an interface surface that faces inward towards the pocket center and is adapted to contact the corresponding peripheral edge of a wafer during operation of the system for growing epitaxial layers, the interface surface including an inwardly sloping portion having a top end that protrudes inward further than a bottom end of the interface surface;
• and
• wherein the interface surface of each of the bumpers includes a contact portion that is positioned to be a sole contact surface against the peripheral edge of the wafer during operation such that a centripetal force applied to the wafer has substantially only a horizontal component.

A method for forming a wafer carrier for use in a system for growing epitaxial layers on one or more wafers by chemical vapor deposition (CVD), the method comprising:

• forming a wafer carrier body that is symmetric about a central axis, and forming a generally planar top surface in the body that is situated perpendicularly to the central axis;
• forming a plurality of wafer retention pockets recessed in the body from the top surface, including:
• forming a floor surface generally parallel to the top surface;
• and
• forming a peripheral wall surface surrounding the floor surface and defining a periphery of that wafer retention pocket,
• such that each wafer retention pocket has a pocket center situated along a corresponding wafer carrier radial axis that is perpendicular to the central axis;
• and
• in each of the wafer retention pockets, arranging a set of bumpers positioned primarily at a distal portion of the wafer retention pocket opposite the central axis so as to maintain a gap of at least a predefined size between the peripheral wall surface at the distal portion and an edge of a wafer to be placed in the wafer retention pocket such that the bumpers of each set of bumpers have a variety of dimensional configurations so that the predefined size of the gap at various bumper positions is different.

A method for forming a wafer carrier for use in a system for growing epitaxial layers on one or more wafers by chemical vapor deposition (CVD), the method comprising:

• forming a wafer carrier body symmetrically about a central axis, and forming a generally planar top surface in the body that is situated perpendicularly to the central axis;
• forming a plurality of wafer retention pockets recessed in the body from the top surface, each of the wafer retention pockets including:
• a floor surface generally parallel to the top surface;
• and
• a peripheral wall surface surrounding the floor surface and defining a periphery of that wafer retention pocket,
• such that each wafer retention pocket has a pocket center situated along a corresponding wafer carrier radial axis that is perpendicular to the central axis;
• and
• in each of the wafer retention pockets, arranging a set of bumpers positioned primarily at a distal portion of the wafer retention pocket opposite the central axis so as to maintain a gap of at least a predefined size between the peripheral wall surface at the distal portion and an edge of a wafer to be placed in the wafer retention pocket;
• such that each of the bumpers in each of the wafer retention pockets includes an interface surface that faces inward towards the pocket center and is adapted to contact the corresponding peripheral edge of a wafer during operation of the system for growing epitaxial layers, the interface surface including an inwardly sloping portion having a top end that protrudes inward further than a bottom end of the interface surface;
• and
• such that the interface surface of each of the bumpers includes a contact portion that is positioned to be a sole contact surface against the peripheral edge of the wafer during operation such that a centripetal force applied to the wafer has substantially only a horizontal component.

Apparatus for growing epitaxial layers on one or more wafers by chemical vapor deposition (CVD), comprising:

• a reaction chamber;
• a rotatable spindle having an upper end disposed inside the reaction chamber;
• a wafer carrier for transporting and providing a support for the one or more wafers, the wafer carrier being centrally and detachably mounted on the upper end of the spindle and being in contact therewith at least in the course of a CVD process;
• and
• a radiant heating element disposed under the wafer carrier for heating thereof;
• wherein the wafer carrier comprises:
• a body formed symmetrically about a central axis, and including a generally planar top surface that is situated perpendicularly to the central axis;
• a plurality of wafer retention pockets recessed in the body from the top surface, each of the wafer retention pockets including:
• a floor surface generally parallel to the top surface;
• and
• a peripheral wall surface surrounding the floor surface and defining a periphery of that wafer retention pocket,
• wherein each wafer retention pocket has a pocket center situated along a corresponding wafer carrier radial axis that is perpendicular to the central axis;
• and
• in each of the wafer retention pockets, a set of bumpers is positioned primarily at a distal portion of the wafer retention pocket opposite the central axis so as to maintain a gap of at least a predefined size between the peripheral wall surface at the distal portion and an edge of a wafer to be placed in the wafer retention pocket;
• wherein the bumpers of each set of bumpers have a variety of dimensional configurations such that the predefined size of the gap at various bumper positions is different.

Apparatus for growing epitaxial layers on one or more wafers by chemical vapor deposition (CVD), comprising:

• a reaction chamber;
• a rotatable spindle having an upper end disposed inside the reaction chamber;
• a wafer carrier for transporting and providing a support for the one or more wafers, the wafer carrier being centrally and detachably mounted on the upper end of the spindle and being in contact therewith at least in the course of a CVD process;
• and
• a radiant heating element disposed under the wafer carrier for heating thereof;
• wherein the wafer carrier comprises:
• a body formed symmetrically about a central axis, and including a generally planar top surface that is situated perpendicularly to the central axis;
• a plurality of wafer retention pockets recessed in the body from the top surface, each of the wafer retention pockets including:
• a floor surface generally parallel to the top surface;
• and
• a peripheral wall surface surrounding the floor surface and defining a periphery of that wafer retention pocket,
• wherein each wafer retention pocket has a pocket center situated along a corresponding wafer carrier radial axis that is perpendicular to the central axis;
• and
• in each of the wafer retention pockets, a set of bumpers is positioned primarily at a distal portion of the wafer retention pocket opposite the central axis so as to maintain a gap of at least a predefined size between the peripheral wall surface at the distal portion and an edge of a wafer to be placed in the wafer retention pocket;
• wherein each of the bumpers in each of the wafer retention pockets includes an interface surface that faces inward towards the pocket center and is adapted to contact the corresponding peripheral edge of a wafer during operation of the system for growing epitaxial layers, the interface surface including an inwardly sloping portion having a top end that protrudes inward further than a bottom end of the interface surface;
• and
• wherein the interface surface of each of the bumpers includes a contact portion that is positioned to be a sole contact surface against the peripheral edge of the wafer during operation such that a centripetal force applied to the wafer has substantially only a horizontal component.