Submicron particle removal using liquid nitrogen

Claim 1

A method of removing particles from a surface of a semiconductor wafer which is to be cleaned, comprising the steps of: introducing a cryogenic liquid which is nontoxic to the environment onto said surface such that said cryogenic liquid begins to evaporate to form a vapor layer above said surface; sheeting or rolling said cryogenic liquid across said surface and ensuring that not all of said cryogenic liquid evaporates prior to reaching a boundary of said surface; removing said particles, such that said sheeting or rolling of said cryogenic liquid occurs above said vapor layer wherein momentum from motion of said cryogenic liquid and surface tension between said cryogenic liquid and said particles dislodge particles that are exposed above said vapor layer by having said particles adhere to or engulfed by said cryogenic liquid as said cryogenic liquid transitions across said surface to remove said particles from said surface.

Claim 2

A method of removing particles from a surface of a semiconductor wafer which is to be cleaned, comprising the steps of: introducing a cryogenic liquid which is nontoxic to the environment onto said surface such that said cryogenic liquid begins to evaporate to form a vapor layer above said surface; sheeting or rolling said cryogenic liquid across said surface and ensuring that not all of said cryogenic liquid evaporates prior to reaching a boundary of said surface; removing said particles, such that said sheeting or rolling of said cryogenic liquid occurs above said vapor layer wherein momentum from motion of said cryogenic liquid and surface tension between said cryogenic liquid and said particles dislodge particles that are exposed above said vapor layer by having said particles adhere to or engulfed by said cryogenic liquid as said cryogenic liquid transitions across said surface to remove said particles from said surface.

Claim 7

A method of removing submicron particles from a surface of a semiconductor wafer which is to be cleaned by utilizing a nontoxic cryogenic liquid which can be vented to the atmosphere, comprising the steps of: introducing a continuous stream of ultra-pure liquid nitrogen (LN 2 ) onto said wafer surface such that said LN 2 begins to evaporate to form a vapor layer above said wafer surface; sheeting or rolling said LN 2 across said wafer surface and ensuring that not all of said LN 2 evaporates prior to reaching an edge of said wafer; removing said particles, such that said sheeting or rolling of said LN 2 occurs above said vapor layer wherein momentum from motion of said LN 2 and surface tension between said LN 2 and said particles dislodge particles that are exposed above said vapor layer by having said particles adhere to or engulfed by said LN 2 as said LN 2 transitions across said wafer surface and off of said edge to remove said particles from said wafer surface.

Claim 8

A method of removing submicron particles from a surface of a semiconductor wafer which is to be cleaned by utilizing a nontoxic cryogenic liquid which can be vented to the atmosphere, comprising the steps of: introducing a continuous stream of ultra-pure liquid nitrogen (LN 2 ) onto said wafer surface such that said LN 2 begins to evaporate to form a vapor layer above said wafer surface; sheeting or rolling said LN 2 across said wafer surface and ensuring that not all of said LN 2 evaporates prior to reaching an edge of said wafer; removing said particles, such that said sheeting or rolling of said LN 2 occurs above said vapor layer wherein momentum from motion of said LN 2 and surface tension between said LN 2 and said particles dislodge particles that are exposed above said vapor layer by having said particles adhere to or engulfed by said LN 2 as said LN 2 transitions across said wafer surface and off of said edge to remove said particles from said wafer surface.