Patent Publication Number: US-2004040660-A1

Title: High pressure processing chamber for multiple semiconductor substrates

Description:
FIELD OF THE INVENTION  
       [0001] This invention relates to the field of high pressure processing chambers for semiconductor substrates. More particularly, this invention relates to the field of high pressure processing chambers for semiconductor substrates where a high pressure processing chamber provides processing capability for simultaneous processing of multiple semiconductor substrates.  
       BACKGROUND OF THE INVENTION  
       [0002] Recently, interest has developed in supercritical processing for semiconductor substrates for such processes as photoresist removal, rinse agent drying, and photoresist development. The supercritical processing is a high pressure processing where pressure and temperature are at or above a critical pressure and a critical temperature. Above the critical temperature and the critical pressure, there is no liquid or gas phase. Instead, there is a supercritical phase.  
       [0003] A typical semiconductor substrate is a semiconductor wafer. The semiconductor wafer has a thin cross-section and a large diameter. Currently, semiconductor wafers have diameters up to 300 mm. Because of a capital outlay for both semiconductor development and for semiconductor processing equipment, semiconductor processing must be efficient, reliable, and economical.  
       [0004] Thus, a supercritical processing system intended for semiconductor processing of multiple semiconductor substrates must have a high pressure processing chamber which is efficient, reliable, and economical.  
       [0005] What is needed is a high pressure processing chamber for processing multiple semiconductor substrates which is efficient, reliable, and economical.  
       SUMMARY OF THE INVENTION  
       [0006] The present invention is a high pressure processing chamber for processing multiple semiconductor substrates. The high pressure processing chamber comprises a chamber housing, a cassette, and a chamber closure. The cassette is removably coupled to the chamber housing. The cassette is configured to accommodate at least two semiconductor substrates. The chamber closure is coupled to the chamber housing. The chamber closure is configured such that in operation the chamber closure seals with the chamber housing to provide an enclosure for high pressure processing of the semiconductor substrates. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0007]FIG. 1 illustrates the preferred high pressure processing chamber and a lifting mechanism of the present invention.  
     [0008]FIGS. 2A and 2B illustrate a locking ring of the present invention.  
     [0009]FIG. 3 further illustrates the preferred high pressure processing chamber of the present invention.  
     [0010]FIG. 4 illustrates the preferred cassette of the present invention.  
     [0011]FIGS. 5A and 5B illustrate a chamber housing, first and second cassettes, and a  15 ′ robot of the present invention.  
     [0012]FIGS. 6A and 6B illustrate an injection nozzle arrangement and a fluid outlet arrangement of the present invention.  
     [0013]FIG. 7 illustrates a supercritical processing system of the present invention.  
     [0014]FIG. 8 illustrates a first alternative high pressure processing chamber of the present invention.  
     [0015]FIG. 9 illustrates a first alternative cassette of the present invention.  
     [0016]FIG. 10 illustrates a second alternative cassette of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0017] Preferably, the preferred high pressure processing chamber of the present invention simultaneously processes multiple semiconductor substrates. Preferably, the semiconductor substrates comprise semiconductor wafers. Alternatively, the semiconductor substrates comprise other semiconductor substrates such as semiconductor pucks. Further alternatively, the semiconductor substrates comprise trays with each tray capable of holding multiple semiconductor devices.  
     [0018] Preferably, the preferred high pressure processing chamber of the present invention provides a supercritical processing environment. More preferably, the preferred high pressure processing chamber provides a supercritical CO 2  processing environment. Preferably, the supercritical CO 2  processing environment comprises a drying environment for drying developed photoresist which has been rinsed but not dried. Alternatively, the supercritical CO 2  processing environment comprises an alternative drying environment for other semiconductor drying processes such as drying MEMS devices. Alternatively, the supercritical CO 2  processing environment comprises a photoresist development environment. Further alternatively, the supercritical CO 2  processing environment comprises a semiconductor cleaning environment, for example, for a photoresist and residue cleaning or for a CMP (chemical mechanical planarization) residue cleaning.  
     [0019] A high pressure processing chamber assembly of the present invention is illustrated in FIG. 1. The high pressure processing chamber assembly  10  comprises the preferred high pressure processing chamber  12  and a lid lifting mechanism  14 . The preferred high pressure processing chamber  12  comprises a chamber housing  16 , a chamber lid  18 , a locking ring  20 , a preferred cassette  22 , and a first o-ring seal  26 . Preferably, the chamber housing  16  and the chamber lid  18  comprise stainless steel. Preferably, the locking ring  20  comprises high tensile strength steel. Preferably, the preferred cassette  22  comprises stainless steel. Alternatively, the preferred cassette  22  comprises a corrosion resistant metal. Further alternatively, the preferred cassette  22  comprises a corrosion resistant polymer material.  
     [0020] The lid lifting mechanism  14  couples to the chamber lid  18 . The locking ring  20  couples to the chamber housing  16 . When the preferred high pressure processing chamber  12  is closed, the locking ring  20  couples the chamber housing  16  to the chamber lid  18  to form a processing enclosure  24 . The preferred cassette  22  couples to an interior of the chamber housing  16 .  
     [0021] In use, the locking ring  20  locks the chamber lid  18  to the chamber housing  16 . The locking ring  20  also maintains a sealing force between the chamber lid  18  and the chamber housing  16  to preclude high pressure fluid within the processing enclosure  24  from leaking past the first o-ring seal  26 . When the locking ring  20  is disengaged from the chamber lid  18 , the lid lifting mechanism  14  raises the lid  18  and swings the lid  18  away from the chamber housing  16 .  
     [0022] The locking ring  20  of the present invention is further illustrated in FIGS. 2A and 2B. The locking ring  20  comprises a broken thread and a lip  21 . The broken thread comprises mating surfaces  23 , which mate to corresponding features on the chamber housing  16  (FIG. 1).  
     [0023] The high pressure processing chamber  10  is further illustrated in FIG. 3. In operation, the preferred cassette  22  preferably holds semiconductor wafers  28 . A robot (not shown) preferably loads the preferred cassette  22  into the chamber housing  16  and retracts. The lid lifting mechanism  14  (FIG. 1) then lowers the chamber lid  18  onto the chamber housing  16 . Following this, the locking ring  20  locks and seals the chamber lid  18  to the chamber housing  16 . Subsequently, the semiconductor wafers are preferably processed in the supercritical environment. Next, the lid lifting mechanism  14  raises the chamber lid  18 . Finally, the robot removes the preferred cassette  22  from the chamber housing  16 .  
     [0024] The preferred cassette  22  of the present invention is further illustrated in FIG. 4.  
     [0025] The preferred cassette  22  comprises a cassette frame  30  and a retaining bar  32 . The cassette frame  30  comprises wafer holding slots  34 , and lifting features  36 . Preferably, the retaining bar  32  is coupled to the cassette frame  30  via a hinge  38 . Preferably, in use, the semiconductor wafers  28  (one shown with dashes lines) are loaded into the preferred cassette  22 . More preferably, the semiconductor wafers are loaded into the preferred cassette  22  by a transfer of the semiconductor wafers  28  from a FOUP (front opening unified pod) to preferred cassette  22 . Once the semiconductor wafers  28  are loaded into the preferred cassette  22 , the retaining bar  32  is preferably snapped into a retaining slot  40  in the cassette frame  30 .  
     [0026] An automated processing arrangement of the present invention is illustrated in FIGS. 5A and 5B. The automated processing arrangement  41  comprises the chamber housing  16 , the robot  42 , and first and second cassettes,  44  and  46 . The robot  42  comprises a robot base  48 , a vertical motion unit  49 , a robot arm  50 , and a forked cassette interface  52 . The robot base  48  provides a rotation movement A for the robot arm  50 . The vertical motion unit  49  provides a vertical movement B for the robot arm  50 . Prior to processing, the first and second cassettes,  44  and  46 , are loaded with the semiconductor wafers  28 . In operation, the robot arm  50  extends the forked cassette interface  52  through the lifting features  36  of the first cassette  44 , lifts the first cassette  44 , moves the first cassette  44  to a position above the chamber housing  16 , lowers the first cassette into the chamber housing  16 , and retracts the forked cassette interface  52 . Following this, the semiconductor wafers  28  in the first cassette  44  are processed. Next, the robot  42  extends the forked cassette interface  52  through the lifting features  36  of the first cassette  44  and removes the first cassette  44  from the chamber housing  16 . Subsequently, the robot  42  handles the second cassette  46  holding more of the semiconductor wafers  28  in a similar fashion to the handling of the first cassette  44 .  
     [0027] An injection nozzle arrangement and a fluid outlet arrangement of the present invention is illustrated in FIGS. 6A and 6B. Preferably, the injection nozzle arrangement  54  and fluid outlet arrangement  56  are located within the chamber housing  16 .  
     [0028] Alternatively, the injection nozzle arrangement  54  forms part of the preferred cassette  22  (FIG. 4). Further alternatively, the fluid outlet arrangement  56  forms part of the preferred cassette  22  (FIG. 4). The injection nozzle arrangement  54  comprises a reservoir  58  and injection nozzles  60 . The fluid outlet arrangement  56  comprises fluid outlets  62  and a drain  64 . In operation, the injection nozzle arrangement  54  and the fluid outlet arrangement  56  work in conjunction to provide a processing fluid flow  66  across the semiconductor wafers  28 .  
     [0029] A supercritical processing system of the present invention is illustrated in FIG. 7. The supercritical processing system  200  includes the preferred high pressure processing chamber  12 , a pressure chamber heater  204 , a carbon dioxide supply arrangement  206 , a circulation loop  208 , a circulation pump  210 , a chemical agent and rinse agent supply arrangement  212 , a separating vessel  214 , a liquid/solid waste collection vessel  217 , and a liquefying/purifying arrangement  219 . The carbon dioxide supply arrangement  206  includes a carbon dioxide supply vessel  216 , a carbon dioxide pump  218 , and a carbon dioxide heater  220 . The chemical agent and rinse agent supply arrangement  212  includes a chemical supply vessel  222 , a rinse agent supply vessel  224 , and first and second high pressure injection pumps,  226  and  228 .  
     [0030] The carbon dioxide supply vessel  216  is coupled to the high pressure processing chamber  12  via the carbon dioxide pump  218  and carbon dioxide piping  230 . The carbon dioxide piping  230  includes the carbon dioxide heater  220  located between the carbon dioxide pump  218  and the high pressure processing chamber  12 . The pressure chamber heater  204  is coupled to the high pressure processing chamber  12 . The circulation pump  210  is located on the circulation loop  208 . The circulation loop  208  couples to the high pressure processing chamber  12  at a circulation inlet  232  and at a circulation outlet  234 . The chemical supply vessel  222  is coupled to the circulation loop  208  via a chemical supply line  236 . The rinse agent supply vessel  224  is coupled to the circulation loop  208  via a rinse agent supply line  238 . The separating vessel  214  is coupled to the high pressure processing chamber  12  via exhaust gas piping  240 . The liquid/solid waste collection vessel  217  is coupled to the separating vessel  214 .  
     [0031] The separating vessel  214  is preferably coupled to the liquefying/purifying arrangement  219  via return gas piping  241 . The liquefying/purifying arrangement  219  is preferably coupled to the carbon dioxide supply vessel  216  via liquid carbon dioxide piping  243 . Alternatively, an off-site location houses the liquefying/purifying arrangement  219 , which receives exhaust gas in gas collection vessels and returns liquid carbon dioxide in liquid carbon dioxide vessels.  
     [0032] The pressure chamber heater  204  heats the high pressure processing chamber  12 . Preferably, the pressure chamber heater  204  is a heating blanket. Alternatively, the pressure chamber heater is some other type of heater.  
     [0033] Preferably, first and second filters,  221  and  223 , are coupled to the circulation loop  208 . Preferably, the first filter  221  comprises a fine filter. More preferably, the first filter  221  comprises the fine filter configured to filter 0.05 μm and larger particles. Preferably, the second filter  223  comprises a coarse filter. More preferably, the second filter  223  comprises the coarse filter configured to filter 2-3 μm and larger particles. Preferably, a third filter  225  couples the carbon dioxide supply vessel  216  to the carbon dioxide pump  218 . Preferably, the third filter  225  comprises the fine filter. More preferably, the third filter  225  comprises the fine filter configured to filter the 0.05 μm and larger particles.  
     [0034] It will be readily apparent to one skilled in the art that the supercritical processing system  200  includes valving, control electronics, and utility hookups which are typical of supercritical fluid processing systems.  
     [0035] A first alternative high pressure processing chamber of the present invention is illustrated in FIG. 8. The first alternative high pressure processing chamber  12 A comprises an alternative chamber housing  16 A, an alternative chamber lid  18 A, and bolts  66 . In the first alternative high pressure chamber, the bolts  66  replace the locking ring  20  (FIG. 3) of the preferred high pressure processing chamber  12 .  
     [0036] A second alternative high pressure processing chamber of the present invention comprises the preferred high pressure processing chamber  12  oriented so that an axis of the preferred high pressure processing chamber  12  is horizontal. Thus, in the second alternative high pressure processing chamber, the chamber lid  18  becomes a chamber door.  
     [0037] A first alternative cassette of the present invention is illustrated in FIG. 9. The first alternative cassette  80  comprises an alternative cassette frame  82  and an alternative retaining bar  84 . In the first alternative cassette, the alternative retaining bar  84  couples to the alternative cassette frame  82  at first and second holes,  86  and  88 . Preferably, the alternative retaining bar  84  comprises a threaded region  90  which threads into the second hole  88 .  
     [0038] A second alternative cassette of the present invention is illustrated in FIG. 10. The second alternative cassette  100  comprises a wafer holding section  102  and a wafer retaining section  104 . The wafer holding section  102  holds the wafers. The wafer retaining section  104  includes a half hinge  106  and a protrusion  108 . The wafer holding section  102  comprises a hinge mating region  110  and a protrusion mating feature  112 . In operation, the wafer holding section  102  and the wafer retaining section are separate. The wafers  28  are loaded into the wafer retaining section  102 , preferably from the FOUP. Then, the half hinge  106  of the wafer retaining section  104  is coupled to the hinge mating region  110  of the wafer holding section  102 . Finally, the protrusion  108  of the wafer retaining section  104  is snapped into the protrusion mating feature  112  of the wafer holding section  102 .  
     [0039] It will be readily apparent to one skilled in the art that other various modifications may be made to the preferred embodiment without departing from the spirit and scope of the invention as defined by the appended claims.