SUSS (1063342), страница 2
Текст из файла (страница 2)
The method furtherincludes encapsulating the substrate in the bowl, andspinning the encapsulated bowl to cause the appliedchemical to be spin coated over the surface of the wafer.Further, the method includes injecting a solvent to anunderside edge of the wafer to remove an excess chemical beading from the edge of the wafer, and collectingthe solvent and the excess chemical beading that flowsoff of the substrate in the fluid retaining cavity while theencapsulated bowl is spinning. Further, the method includes draining the excess chemical beading and thesolvent that is collected in the fluid retaining cavity whenthe encapsulated bowl nears a non-spinning state.[0015] An advantage of the present invention is that202530354the lid is configured to enclose the wafer and seal outthe environment above the wafer surface during a spincoating process.
The plurality of injection holes definedin the floor of the spinning bowl are well suited for applying a solvent to the underside of the wafer to rinsethe edge of the wafer to prevent edge beading of theapplied chemicals (e.g., photoresist, SOG, and otherspun on dielectrics). Generally, the solvent that is applied to the underside of the wafer is driven into the spinning bowl by the centrifugal forces produced when thebowl is spinning.
Accordingly, the applied solvent mayalso be used to clean the inside of the bowl after eachspin coating operation to reduce chemical build up,which may cause yield reducing defects.[0016] Furthermore, the fluid retaining cavity according to the present invention in the bowl is well suited tohold any excess chemicals that are spin coated over thewafer as well as any solvent material that may be applied to the underside of the wafer. Preferably, substantially all fluids are retained within the cavity while thebowl is spinning, and when the bowl comes to a stop,the fluids may drain out through drain holes defined inthe floor of the bowl. As an additional advantage, by capturing the fluids within the cavity during a spin coatingoperation, substantially less yield reducing particulatesare produced.
In a further embodiment, an extension ofthe bowl is well suited to form a labyrinth with a splashring of a catch cup, and thereby substantially further reduce the possibility of air borne particulates outside tothe bowl/catch cup system.[0017] Other aspects and advantages of the inventionwill become apparent from the following detailed description, taken in conjunction with the accompanyingdrawings, illustrating by way of example the principlesof the invention.BRIEF DESCRIPTION OF THE DRAWINGS4045[0018] The present invention will be readily understood by the following detailed description in conjunctionwith the accompanying drawings.Figure 1 not according to the present invention is across-sectional view of a substrate spin coated in aconventional open bowl arrangement.Figure 2A not according to the present invention isan exploded view of a rotatable bowl and a lid.50553Figure 2B not according to the present invention isa top view of a rotatable bowl.Figure 2C not according to the present invention isa cross-sectional view showing the rotatable bowlcontaining a wafer and a locking shaft for mechanically applying and removing the lid to the rotatablebowl.5EP 1 015 136 B1Figure 2D not according to the present invention isa top view of the lid used.Figures 2E not according to the present inventionis an enlarged side view of a portion of a rotatablebowl having a fluid drain hole.5Figure 2F not according to the present invention isa diagrammatic cross-sectional view of a wafer during a typical spin coat cycle.10Figure 2G not according to the present invention isa cross sectional view of a wafer having a substantially uniform coating layer after a spin coating procedure.15Figures 3 not according to the present invention illustrates an exemplary spin coating system including a catch cup.20Figure 4A is an exploded view of a rotatable bowland a lid in accordance with the present invention.Figure 4B is a side cross sectional view of the rotatable bowl of Figure 4A in accordance with thepresent invention.Figures 4C is an enlarged side view the rotatablebowl of Figure 4B illustrating a cavity for holding fluids during a wafer spin coating operation in accordance with the present invention.Figure 5A is a cross sectional view of the appliedcoating fluid captured in the cavity during the spincoating operation in according with the present invention.Figure 5B is a cross sectional view of the appliedcoating after a solvent back rinse operation is performed in accordance with the present invention.25303540Figures 6A is an exemplary spin coating system including a catch cup and splash rings in accordancewith the present invention.45Figures 6B is a magnified cross sectional view of alabyrinth formed by an extension of the rotatablebowl and a splash ring of the catch cup of Figure 6Ain accordance with the present invention.50DETAILED DESCRIPTION OF THE PREFERREDEMBODIMENTS[0019] An invention for a closed semiconductor process bowl that provides improved spin coat uniformity isdisclosed.
Although the present invention is particularlywell suited for the application of photoresist materials,other chemicals such as spin-on-glass (SOG) may also5546find the application process well suited to improve coating uniformity. The various embodiments of the presentinvention may be implemented in any form, and may findparticular use in the application of both high viscosityand lower viscosity materials to the surface of a planarwafer. In the following description, numerous specificdetails are set forth in order to provide a thorough understanding of the present invention.
It will be obvious,however, to one skilled in the art, that the present invention may be practiced without some or all of these specific details. In other instances, well known process operations have not been described in detail in order notto unnecessarily obscure the present invention.[0020] In accordance with the present invention, aclosed process bowl is disclosed where chemicals arespin coated over a substrate during a fabrication process. In a preferred embodiment, the substrate is a waferthat may be used to make semiconductor devices.
Generally, the wafer is placed on a rotatable bowl that is rigidly affixed to a motor driven shaft. During the coatingprocess, a chemical such as photoresist is applied tothe surface of the wafer before a lid is secured to therotatable bowl having curved walls. The spinning of thebowl causes the chemical to spread over the surface ofthe wafer.[0021] To combat the aforementioned edge beadingproblems, a solvent is preferably injected on the backside (i.e., back side rinse) of the spinning wafer near itsouter diameter after the photoresist has spread over thesurface of the wafer. Preferably, the solvent is injectedthrough a plurality of solvent injector holes that extendfrom an outer surface of the rotatable bowl to an interiorregion of the rotatable bowl.
When applied, the solventis forced into the rotatable bowl by the centrifugal forceproduced by the spinning action. In one embodiment,the applied solvent acts to substantially reduce beadingat the outer regions of the wafer. Further, the appliedsolvent also acts to reduce particle contamination to theunder surface of the wafer.[0022] Preferably, the bowl containing the coated wafer is spun while the solvent is applied to the surface ofthe wafer to complete the top side rinse. Any solventchemicals that spin off of the surface of the wafer whilethe bowl is spinning are therefore allowed to exit thebowl through the aforementioned drain holes that arepositioned below the surface height of the wafer whenthe bowl comes to rest.
The back side rinse and top siderinse operations have the advantageous effect of cleaning the inner regions of the bowl of excess photoresistin addition to providing superior edge bead removal ina controlled environment.[0023] Figure 2A is not according to the present invention. It helps, however, to the understanding of theclaimed invention. It shows an exploded view of a closedsemiconductor process system 100 including a bowl102 and a lid 101. The lid 101 preferably has a circularshape having an upper beveled surface 110, a lower flatsurface 114, and a hollow internal region 111 that is ac-7EP 1 015 136 B1cessible through a top opening 113. In accordance withthe present embodiment, the bowl 102 is integrally connected to a motor driven axial shaft 135.
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