Apparatus and method for measuring static charge on wafers, disks, substrates, masks, and flat panel displays
AssigneeIon Systems, Inc.
InventorsJohn E. Menear, Lawrence B. Levit
Life of this patent
Estimating the term…
Abstract
Apparatus and method and system for measuring and controlling electrostatic charge on objects such as semiconductor substrates include a cassette having an inner structure with supporting slots and electrically conductive regions, and having isolated conductive outer walls for supporting objects in the slots, and include a charge monitor connected to the conductive regions and the conductive walls for sensing charge applicable to one or more objects carrying static charge positioned within the cassette. Charge neutralization is controlled in response to sensed charge attaining a selected level.
Claims29
Apparatus for monitoring electrostatic charge, comprising:
- a housing including space therein for supporting a number of objects, one or more of which may carry electrostatic charge;
- a conductive structure within the housing adjacent the number of objects supported within the housing;
- a conductive layer outside of the housing electrically insulated from the conductive structure within the housing;
- and
- a charge meter connected to the conductive structure within the housing and to the conductive layer outside of the housing for monitoring electrostatic charge on the number of objects supported within the housing.
A method for sensing electrostatic charge on an object that is transferred with respect to a housing, the method comprising:
- establishing near the object within the housing a conductive structure that is electrically isolated;
- transferring relative to the housing an object that may carry electrostatic charge thereon;
- and
- monitoring charge on the conductive structure at least during transfer of the object relative to the housing.
A system for handling a population of objects that may carry electrostatic charge, the system comprising:
- a housing for supporting therein a number of the objects from the population thereof, the housing including a conductive structure near the number of objects insulated from ground;
- transfer apparatus for selectively transferring the number of objects relative to the housing;
- and
- a monitor in electrical communication with the conductive structure for monitoring charge appearing on the conductive structure at least during transfer of an object relative to the housing.
Apparatus for containing a plurality of wafers, one or more of which may carry electrostatic charge, the apparatus comprising:
- a housing having side supports including a plurality of slots disposed in oppositely-aligned pairs for containing a wafer in each such pair of slots within the housing;
- a conductive surface at least in selected slots for electrically communicating with a wafer disposed therein;
- and
- an electrical connection to the conductive surface in at least one slot of each of the pair of slots in the housing in electrical isolation from other paths of electrical conduction.
Apparatus for containing a plurality of substrates, one or more of which may carry electrostatic charge, the apparatus comprising:
- a housing of insulative material having side supports including a plurality of slots disposed in oppositely-aligned pairs for containing a substrate in each such pair of slots within the housing;
- conductive layers disposed in said housing on opposite sides of slots for containing a substrate to form electrically isolated isopotential surfaces near to and spaced away from a substrate positioned in a pair of the slots within the housing;
- and
- electrical connections to the conductive layers for sensing electrostatic charge on a substrate positioned between the conductive layers.
Dependencies are inferred from the claim text.