Supercritical fluid cleaning process for precision surfaces
First Claim
1. A supercritical fluid cleaning process for cleaning precision surfaces comprising the steps:
- (a) selecting process materials comprising a process gas which is convertible at a critical point of temperature and pressure to a supercritical fluid for said cleaning process, (b) selecting supercritical fluid operating parameters for said process gas including a supercritical temperature, a lower supercritical pressure, and a higher supercritical pressure, said higher supercritical pressure being preferably at least twice said lower supercritical pressure, (c) loading, closing and sealing at least one substrate with a said precision surface in a pressure vessel, said vessel being connected to a source of said process gas and a source of said supercritical fluid and having at least one port for exhausting byproducts of said process, said vessel configured with means for heating the interior thereof and having independent means for isolating said vessel from inflow of said process materials and outflow of said byproducts, (d) purging and pressurizing said vessel with process gas and supercritical fluid to said higher supercritical pressure while heating said interior to said supercritical temperature so as to displace all other gases with supercritical fluid without entering a liquid phase condition, (e) soaking said wafer at said higher supercritical pressure for a predetermined soak period, (f) agitating said substrate by rapidly decompressing said vessel to said lower supercritical pressure and flushing said vessel with said supercritical fluid for a predetermined period of time, then rapidly elevating said vessel to said higher supercritical pressure, (g) rinsing said substrate at said higher supercritical pressure, (h) drying said substrate with supercritical fluid and process gas by maintaining said vessel at supercritical temperature when decreasing vessel pressure to ambient, and (i) opening said vessel and unloading said substrate.
1 Assignment
0 Petitions
Accused Products
Abstract
A dry process for the cleaning of precision surfaces such as of semiconductor wafers, by using process materials such as carbon dioxide and useful additives such as cosolvents and surfactants, where the process materials are applied exclusively in gaseous and supercritical states. Soak and agitation steps are applied to the wafer, including a rapid decompression of the process chamber after a soak period at higher supercritical pressure, to mechanically weaken break up the polymers and other materials sought to be removed, combined with a supercritical fluid flush to carry away the loose debris.
-
Citations
27 Claims
-
1. A supercritical fluid cleaning process for cleaning precision surfaces comprising the steps:
-
(a) selecting process materials comprising a process gas which is convertible at a critical point of temperature and pressure to a supercritical fluid for said cleaning process, (b) selecting supercritical fluid operating parameters for said process gas including a supercritical temperature, a lower supercritical pressure, and a higher supercritical pressure, said higher supercritical pressure being preferably at least twice said lower supercritical pressure, (c) loading, closing and sealing at least one substrate with a said precision surface in a pressure vessel, said vessel being connected to a source of said process gas and a source of said supercritical fluid and having at least one port for exhausting byproducts of said process, said vessel configured with means for heating the interior thereof and having independent means for isolating said vessel from inflow of said process materials and outflow of said byproducts, (d) purging and pressurizing said vessel with process gas and supercritical fluid to said higher supercritical pressure while heating said interior to said supercritical temperature so as to displace all other gases with supercritical fluid without entering a liquid phase condition, (e) soaking said wafer at said higher supercritical pressure for a predetermined soak period, (f) agitating said substrate by rapidly decompressing said vessel to said lower supercritical pressure and flushing said vessel with said supercritical fluid for a predetermined period of time, then rapidly elevating said vessel to said higher supercritical pressure, (g) rinsing said substrate at said higher supercritical pressure, (h) drying said substrate with supercritical fluid and process gas by maintaining said vessel at supercritical temperature when decreasing vessel pressure to ambient, and (i) opening said vessel and unloading said substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16, 17, 18, 19, 20, 21, 22, 23, 25, 26, 27)
-
-
14. A supercritical fluid cleaning process for cleaning precision surfaces comprising the steps:
-
(a) selecting process materials comprising carbon dioxide as a process gas which is convertible at a critical point of temperature and pressure to a supercritical fluid for said cleaning process, and additives soluble in said process gas, (b) selecting supercritical fluid operating parameters for said process gas including a supercritical temperature, a lower supercritical pressure, and a higher supercritical pressure, said higher supercritical pressure being preferably at least twice said lower supercritical pressure, (c) loading, closing and sealing at least one substrate with a said precision surface in a pressure vessel, said vessel being connected to a source of said process gas and a source of said supercritical fluid and a source of supercritical fluid mixture comprising said supercritical fluid and said additives, and having at least one port for exhausting byproducts of said process, said vessel configured with upper and lower heat exchanger platens for heating the interior thereof and having independent means for isolating said vessel from inflow of said process materials and outflow of said byproducts, (d) purging and pressurizing said vessel with process gas and supercritical fluid to said higher supercritical pressure while heating said interior to said supercritical temperature so as to displace all other gases with supercritical fluid without entering a liquid phase condition, (e) filling said vessel with said supercritical fluid mixture so as to replace said supercritical fluid, (f) soaking said wafer at said higher supercritical pressure for a predetermined soak period, (g) agitating said substrate by rapidly decompressing said vessel to said lower supercritical pressure and flushing said vessel with said supercritical fluid for a predetermined period of time, then rapidly elevating said vessel to said higher supercritical pressure, (h) rinsing said substrate with said supercritical fluid at said higher supercritical pressure, (i) drying said substrate with supercritical fluid and process gas by maintaining said vessel at supercritical temperature when decreasing vessel pressure to ambient without entering a liquid phase condition, (j) opening said vessel and unloading said substrate.
-
-
24. A supercritical fluid cleaning process for cleaning precision surfaces comprising the steps:
-
(a) selecting process materials comprising carbon dioxide as a process gas which is convertible at a critical point of temperature and pressure to a supercritical fluid for said cleaning process, and additives soluble in said process gas, (b) selecting supercritical fluid operating parameters for said process gas including a supercritical temperature, a lower supercritical pressure, and a higher supercritical pressure, said higher supercritical pressure being preferably at least twice said lower supercritical pressure, (c) loading, closing and sealing at least one substrate with a said precision surface in a pressure vessel, said vessel being connected to a source of said process gas and a source of said supercritical fluid and a source of supercritical fluid mixture comprising said supercritical fluid and said additives, and having at least one port for exhausting byproducts of said process, said vessel configured as an inverted vessel with an underside vertically operated lid upon which said substrate is mounted for said processing, said vessel further comprising a divergent inflow channel and a convergent outflow channel, said vessel configured with upper and lower heat exchanger platens for heating the interior thereof and having independent means for isolating said vessel from inflow of said process materials and outflow of said byproducts, (d) purging and pressurizing said vessel with process gas and supercritical fluid to said higher supercritical pressure while heating said interior to said supercritical temperature so as to displace all other gases with supercritical fluid without entering a liquid phase condition, (e) filling said vessel with said supercritical fluid mixture so as to replace said supercritical fluid, (f) soaking said wafer at said higher supercritical pressure for a predetermined soak period, (g) agitating said substrate by rapidly decompressing said vessel to said lower supercritical pressure and flushing said vessel with said supercritical fluid for a predetermined period of time, then elevating said vessel to said higher supercritical pressure, (h) rinsing said substrate with said supercritical fluid at said higher supercritical pressure, (i) drying said substrate with supercritical fluid and process gas by maintaining said vessel at supercritical temperature when decreasing vessel pressure to ambient without entering a liquid phase condition, (j) opening said vessel and unloading said substrate.
-
Specification