SUSS (1063342), страница 4
Текст из файла (страница 4)
As shown, the coating layer 140 is nowmore uniform throughout the surface of wafer 130.[0033] Figures 3 is not according to the present invention. It helps, however, to the understanding of theclaimed invention. It illustrates an spin coating system510152025303540455055610180 that may be used in conjunction with the closed bowlspin coating system described above. As shown, bowl102 and lid 101 are preferably assembled within a catchcup 182. Catch cup 182 may include a splash ring 183that is used to block particulates generated out of drainholes 125 from exiting catch cup 182. Catch cup 182also includes a drain hole 190 that is well suited to channel chemicals out of catch cup 182 and into a drain manifold (not shown).
An exhaust manifold 188 may also beprovided to assist in the removal of air borne particulates. A HEPA filter (not shown) may also be positionedabove spin coating system 180 to capture any particulates that may escape catch cup 182. In the embodimentshown, a plenum 192 is coupled to bowl 102 to providea channel 194 used for applying the aforementioned solvent chemicals to the solvent injector holes 121. In addition, plenum 192 provides a surface for receiving theexhaust manifold 188.
Of course, any number of wellknown exhaust manifolds 188 may be implemented aswell.[0034] According to the present invention for a closedsemiconductor process bowl that reduces particulategeneration and provides improved spin coat uniformitiesis disclosed. Although the present invention is particularly well suited for the application of photoresist materials, other chemicals, such as, spin-on-glass (SOG)and spin-on-dielectrics (SODs) may also find the application processes described herein particularly advantageous for achieving improved coating uniformities andreducing particulates. Furthermore, the various embodiments of the present invention may be implemented inany form, and may find particular use in the applicationof both high viscosity and lower viscosity materials.[0035] Any dissolved coating material and excess solvent that is produced during a spin coating process ispreferably captured in a concave region located at aninterior edge of the bowl, while the spin coating processis in progress.
Once spin coating is complete (e.g., thespinning bowl comes to a substantial halt), the captivedissolved coating material and excess solvent are allowed to flow out of the spinning bowl through drainholes that are located on the lower surface of the bowl.That is, while the bowl is spinning, the centrifugal forceacts to holds the dissolved coating material in the concave region. However, once the centrifugal forces diminish, the liquid will be allowed to flow out of the closedbowl system. It should be appreciated that substantiallyall particulates are advantageously contained within theclosed bowl system during the spin coat operation,thereby reducing backside contamination problems aswell as environmental contamination.[0036] In accordance with a further embodiment of thepresent invention, the back side and sometimes top sideedge bead removal (EBR) process steps enable thegeneration of substantially uniform coatings within acontrolled environment that reduces particulate generation.
Furthermore, the EBR process steps advantageously assist in automatically rinsing the bowl after11EP 1 015 136 B1each coating operation. Of course, maintaining the bowlclean during a spin coating session is particularly important to reduce the possibility of contaminating currentwafers with particulates of previous spin coating sessions.[0037] Figure 4A is an exploded view of a closed semiconductor process bowl 200 including a bowl 202 anda lid 201, and Figure 4B is an assembled view in accordance with the present invention. In this embodiment, thelid 201 preferably has a circular shape with an upperbeveled surface 210, a lower flat surface 214, and a hollow internal region 211 that is accessible through a topopening 213.
Preferably, the bowl 202 is integrally connected to a motor driven axial shaft 235 that includes anaxially located vacuum chamber 218 extending alongthe length of the axial shaft 235 and terminating in a vacuum orifice 219. Vacuum orifice 219 is preferably centrally located within bowl 202 for securing wafers to asupport surface 204.[0038] As shown in Figure 4B, support surface 204 ofbowl 202 is well suited to hold a wafer 230 during spincoating operations. In a preferred embodiment, the substrate is a silicon wafer used in the fabrication of semiconductor integrated circuits. However, it should be appreciated that the various embodiments of the presentinvention may be equally applicable to other technologies where precision chemical (i.e., photoresist, spinon-glass (SOG), spin-on-dielectrics (SODs), compactdisc recordable (CDR) dye chemicals, mask plates, liquid crystal display panels, multi-chip carriers, etc.) spincoating is desirable.
In this embodiment, a support ring226 defines the outer diameter of support surface 204.In this example, lid 201 will preferably have a circularrecessed groove 212 defined in the lower flat surface214. Circular recessed groove 212 is preferably configured to mate with a circular protruded lip 224 that is located around the outer portion of bowl 202. Further, aseparation of between about 1 mm and about 10 mm ispreferably defined between the lower flat surface 214 oflid 201 and the top surface of wafer 230, and more preferably, the separation is between about 1.5 mm andabout 3, and most preferably about 2.[0039] As mentioned above, bowl 202 preferably includes a cavity 250 for holding any dissolved coatingmaterial and excess solvent during the spin coatingprocess. Therefore, while bowl 202 and lid 201 are spinning, the centrifugal forces will hold the excess liquid incavity 250, and when the forces diminish, the liquid willpreferably flow out through a plurality of drain holes 225.Preferably, between about 8 and about 16 drain holes225 are defined along the floor of bowl 202 to enablethe applied chemicals to exit after a spin coating application.[0040] Referring to Figure 4B, bowl 202 also includesa plurality of solvent injection holes 221 that have a firstend located within a solvent injector ring 223 (at a radialdistance r1 from the center of bowl 202), and a secondend located approximately at the mid-line of a solvent510152025303540455055712ejector ring 227 (at a radial distance r2 from the centerof bowl 202).
Generally, radial distance r1 is less thanradial distance r2, therefore solvent injection hole 221forms an angled conduit (e.g., between about a 30 and50 degrees) through bowl 202 connecting solvent injector ring 223 and solvent ejector ring 227.[0041] Bowl 202 also includes a circular extension260 that extends from the outer region of bowl 202 toreduce the possibility of particulate contamination.
Aswill be described in greater detail below with referenceto Figure 6B, circular extension 260 forms a labyrinthwith a stationary catch cup splash ring to prevent substantially all generated particulates from exiting the system and contaminating the spin coated chemicals.[0042] To ensure that lid 201 remains secured to bowl202, a locking shaft 261 is placed near the lower surface214 of lid 201. By way of example, locking shaft 261 conforms to the shape of the top opening 213 of lid 201,thereby accessing hollow internal region 211. Once inserted into hollow internal region 211, locking shaft 261is rotated approximately 120° in either direction. In thismanner, locking shaft 261 is firmly affixed near the lowersurface 214 of lid 201 to ensure that lid 201 does notdetach during a spin coating process.[0043] Additionally, a plurality of locking pins 122/222shown in Figures 4A and 2B are arranged about the topportion of the walls of bowl 202 to assist in securing lid201 during processing.
Generally, locking pins 122/222are configured to mate with suitable recessed pin holeslocated on the underside of lid 201. In another embodiment, lid 201 may include magnetic latches (not shown)for securing lid 201 to bowl 202. Generally, the magneticlatches may be composed of a plurality of attractingmagnet pads that are well balanced along the top portion of the walls of bowl 202 and along the underside ofthe lid 201. In this manner, the magnet pads of the bowl202 and the lid 201 are not required to mate in the samefixed orientation each time the lid 201 is applied to thebowl 202. As an advantage, a more rapid sealing of bowl202 may be performed which, in some cases, may prevent premature drying of the chemicals that applied tothe wafer 230.[0044] Figure 4C is a magnified cross sectional viewof Figure 4B having the plurality of drain holes 225spaced a distance "y" from the outer edge of bowl 202(excluding circular extension 260).
In this manner, theplurality of drain holes 225 (being between about 1 and3 mm in diameter) lie under wafer 230 to ensure thatcavity 250 will hold the excess solvent and dissolvedphotoresist during a spin coating operation. For this reason, cavity 250 is preferably large enough to accommodate a volume of between about 10 cubic centimetersand about 20 cubic centimeters.[0045] Figure 5A is a more magnified view of cavity250 holding solvent fluids provided through solvent injection holes 221 and dissolved chemicals that spreadoff of the wafer 230 in accordance with one embodimentof the present invention.
As described above, while bowl13EP 1 015 136 B1202 is spinning during a spin coating process, the centrifugal force will ensure that the excess chemicals willbe contained in cavity 250 during the spin coating process. Therefore, when a chemical, such as, photoresistis applied over a top surface 232 of wafer 230, a photoresist beading 254 will unfortunately occur at the edgeof wafer 230.[0046] To eliminate beading 254, a solvent 241 is applied from under bowl 202 against injection ring 223,through injection holes 221, and onto the back side ofwafer 230. Once the solvent 241 is applied to an undersurface 231 of wafer 230, the solvent material spreadsin an outward manner due to the centrifugal forces ofthe spinning motion of bowl 202.
When the solvent 241reaches the edge of wafer 230, the solvent bead 251 isbelieved to interact with a beading 254 of a chemicalcoating 240. When solvent 241 comes in contact withbeading 254, the beading 254 will begin to dissolve andfall into cavity 250. As an advantage, substantially all ofthe excess fluids are captured in cavity 250 during a spincoating operation, and substantially all uncontrolled solvents and coating chemicals are prevented from exitingbowl 202 where undesirable particulates may be generated.[0047] Figure 5B is a cross sectional view of thechemical coating 240 applied in a substantially uniformmanner to the entire top surface of wafer 230 in accordance with one embodiment of the present invention.
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