Abstract:
A substrate preparation system includes a proximity head configured to be positioned near a surface of the substrate to deliver a solution to the surface of the substrate. The proximity head includes a plurality of inlets for delivering the solution and a plurality of outlets for removing a portion of the solution from the surface of the substrate. The surface of the substrate maintains a remaining portion of the solution as a coherent film after the proximity head is scanned over the surface of the substrate. The coherent film is configured to be cured. The remaining portion of the solution acts on the surface of the substrate and binds particulates present on the surface of the substrate as the coherent film cures.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This is application is related to co-pending U.S. patent application Ser. No. 10/261,839, entitled “Method and Apparatus for Drying Semiconductor Wafer Surfaces Using a Plurality of Inlets and Outlets Held in Close Proximity to the Wafer Surfaces” filed on Sep. 30, 2002. This patent application is hereby incorporated by reference. 
   BACKGROUND 
   The present invention pertains to preparation of substrates, and more particularly, to apparatus and methods for preparing a surface of a substrate. 
   In the fabrication of semiconductors, it is well known that there is a need to prepare the surface of a substrate during the fabrication process. For example, surface preparation of a substrate may include removing any unwanted material from the surface of the substrate. Unwanted material on the surface of a substrate can cause undesirable effects to the fabricated semiconductor, which can result in a defective integrated circuit (IC). Accordingly, it is desirable to prepare the surface of a substrate to remove any unwanted material from the surface at different stages of the fabrication process. 
   SUMMARY 
   Broadly speaking, the present invention provides systems and methods for preparing surfaces of substrates, e.g., semiconductor wafers. Of course, other substrates, such as those used in the hard drive industry may also make use to the teachings described herein. More particularly, embodiments of the present invention provide apparatus and methods to prepare the processing surface of substrates. 
   In one embodiment, a substrate preparation system includes a proximity head configured to be positioned near a surface of the substrate to deliver a solution to the surface of the substrate. The proximity head includes a plurality of inlets for delivering the solution and a plurality of outlets for removing a portion of the solution from the surface of the substrate. The surface of the substrate maintains a remaining portion of the solution as a coherent film after the proximity head is scanned over the surface of the substrate. The coherent film is configured to be cured. The remaining portion of the solution acts on the surface of the substrate and binds particulates that are present on the surface of the substrate as the coherent film cures. 
   In another embodiment, a method for preparing a surface of a substrate is provided. The method includes generating a meniscus for applying a solution to the surface of the substrate. The meniscus is traversed over the surface of the substrate to define a coherent film. The coherent film is defined by the solution and the coherent film is configured to act on the surface of the substrate and bind particulates that are present on the surface of the substrate. 
   Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of examples the principles of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be readily understood by the following detail description in conjunction with the accompanying drawings, and like reference numerals designating like structural elements. 
       FIG. 1  is a diagram of a top view of a substrate and a proximity head, in accordance with one embodiment of the present invention. 
       FIG. 2  is a diagram of a side view of a substrate and a proximity head, in accordance with one embodiment of the present invention. 
       FIG. 3  is a diagram of a bottom view of a proximity head, in accordance with one embodiment of the present invention. 
       FIG. 4  is a diagram of another side view of a substrate and a proximity head, in accordance with one embodiment of the present invention. 
       FIG. 5  is a diagram of yet another side view of a substrate and a proximity head, in accordance with one embodiment of the present invention. 
       FIG. 6A  is a diagram of a substrate and a coherent film on a surface of the substrate, in accordance with one embodiment of the present invention. 
       FIG. 6B  is a diagram of a close-up view of a substrate and a coherent film on a surface of the substrate, in accordance with one embodiment of the present invention. 
       FIG. 6C  is a diagram of another close-up view of a substrate and a coherent film on a surface of the substrate, in accordance with one embodiment of the present invention. 
       FIG. 7  is a diagram of yet another close-up view of a substrate and a coherent film on a surface of the substrate, in accordance with one embodiment of the present invention. 
       FIG. 8  is a diagram of a close-up view of a substrate and a proximity head, in accordance with one embodiment of the present invention. 
       FIG. 9  is a diagram of a substrate, a proximity head, and a light source, in accordance with one embodiment of the present invention. 
       FIG. 10  is a diagram of a substrate, a proximity head, and a heat source, in accordance with one embodiment of the present invention. 
       FIG. 11  is a diagram of a substrate and a proximity head, in accordance with one embodiment of the present invention. 
       FIG. 12  is a diagram of a substrate and two proximity heads, in accordance with one embodiment of the present invention. 
       FIG. 13A  is a diagram of substrate with a residue film and particles on a surface of the substrate, in accordance with one embodiment of the present invention. 
       FIG. 13B  is a diagram of a substrate and a coherent film on a surface of the substrate, in accordance with one embodiment of the present invention. 
       FIG. 13C  is a diagram of a substrate and compounds on a surface of the substrate, in accordance with one embodiment of the present invention. 
       FIG. 14  is a flow chart detailing a surface preparation process, in accordance with one embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
   The present invention, as illustrated by the following embodiments, provides systems and methods for preparing surfaces of substrates, and in particular semiconductor wafers. More specifically, embodiments of the present invention provide apparatus and methods to treat surfaces of substrates and remove particulates that are present on the surfaces of substrates. As should be appreciated, the present invention can be implemented in numerous ways, including systems or methods. In some instances, well known process operations and components have not been described in detail in order to avoid obscuring the embodiments of the present invention. 
     FIG. 1  is a diagram of a top view of a substrate and a proximity head in accordance with one embodiment of the present invention. As illustrated in  FIG. 1 , substrate  102  is scanned beneath the proximity head  104  at a velocity V 1 . Although in  FIG. 1  the proximity head  104  is illustrated as being stationary, in other embodiments of the present invention, the proximity head  104  may not be stationary. For example, the proximity head  104  may be scanned over the substrate  102  at a velocity V 2 , while the substrate  102  is stationary. In a further embodiment of the present invention, both the substrate  102  and the proximity head  104  may be in motion (e.g., the substrate  102  is scanned in one direction at a velocity V 1 , while the proximity head may be scanned in another direction at a velocity V 2 ). 
   The examples provided herein define a proximity head  104  which is placed over a single side of the substrate  102 . However, the embodiments can be modified so that both sides of the substrate  102  are prepared at the same time, where one proximity head prepares a first side of the substrate  102  and another proximity head prepares a second side of the substrate  102 . The preparation of the first and second sides can be completed at the same time or at different times. For simplicity, however, the teachings of the invention will concentrate on the treatment of one side of the substrate  102 . 
     FIG. 2  is a diagram of a side view of the substrate  102  and proximity head  104  in accordance with one embodiment of the present invention. As shown in  FIG. 2 , substrate  102  is scanned under the proximity head  104  at a velocity V 1 . The proximity head  104  delivers a solution to the surface of the substrate  102  as the substrate  102  is scanned underneath the proximity head  104 . As will be discussed in detail, the solution is delivered from the proximity head  104  to the surface of the substrate  102  by way of a meniscus  202 . The meniscus  202  is maintained between the proximity head  104  and the surface of the substrate  102 . A remaining portion of the solution is maintained on the surface of the substrate  102  as a coherent film  204  after the substrate  102  is scanned underneath the proximity head  104 . In another embodiment of the present invention, the proximity head  104  is scanned over the substrate  102  as the coherent film  204  is maintained on the surface of the substrate  102 . The coherent film  204  is configured to be cured on the surface of the substrate  102 . The cured coherent film  204 , can be said to have at least partially solidify (e.g., coagulate/cross link/gel) into the coherent film. 
     FIG. 3  shows section A-A of  FIG. 2 , which is a diagram of a bottom view of the proximity head  104  in accordance with one embodiment of the present invention. The bottom view of proximity head  104  shows a plurality of inlet ports  302  and a plurality of outlet ports  304 . As will be discussed in more detail, the plurality of inlet ports  302  deliver a solution to the surface of substrate  102 , and the plurality of outlet ports  304  remove a portion of the solution from the surface of the substrate  102 . The combination of having the solution being delivered from the plurality of inlet ports  302  and a portion of the solution being removed by the plurality of outlet ports  304  maintains a meniscus between the proximity head  104  and the substrate  102 . A remaining portion of the solution is maintained on the surface of the substrate  102  as a coherent film  204  (i.e., the portion of the solution remains on the surface after the proximity head  104  passes by). The coherent film  204  is configured to be cured on the surface of the substrate  102 . 
     FIG. 4  is a diagram of another side view of the substrate  102  and proximity head  104  in accordance with one embodiment of the present invention. As shown in  FIG. 4 , substrate  102  is scanned beneath proximity head  104  at a velocity V 1 , while proximity head  104  may be stationary or in motion. For example, the proximity head  104  may be scanned over the substrate  102  at a velocity V 2 , while at the same time, substrate  102  may be scanned beneath proximity bar  104  at a velocity V 1 . The plurality of inlet ports  302  deliver a solution on to the surface of substrate  102 , and a plurality of outlet ports  304  remove a portion of the solution that is being delivered to the surface of substrate  102 . The combination of having the solution being delivered from the plurality of inlet ports  302  and a portion of the solution being removed by the plurality of outlet ports  304  maintains a meniscus between the proximity head  104  and the substrate  102 . A remaining portion of the solution forms a coherent film  204  on the surface of the substrate  102 . The coherent film  204  is configured to be cured on the surface of the substrate  102 . Although not shown, the inlet ports  302  and outlet ports  304  are connected to conduits that deliver and remove the fluids. The conduits are connected to facilities of a substrate preparation building, such as a process clean room. In another embodiment, the system is not connected to building facilities, but alternative chemicals and fluids are loaded directly into the machine via a carboy or other portable apparatus. 
     FIG. 5  is a diagram of a yet another side view of substrate  102  and proximity head  104  in accordance with another embodiment of the present invention. Proximity head  104  is scanned over substrate  102  with meniscus  202  maintained between the proximity head  104  and substrate  102 . The meniscus  202  delivers a solution to the surface of substrate  102 . The solution may include an acid component, for example, hydrofluoric acid (HF). Alternatively, the solution may include a base. One purpose of the solution is to treat the surface of the substrate  102 . For example, surface treatment of the substrate  102  includes dissolving a residue film of material on the surface of the substrate  102 . The residue film of material on the surface of the substrate  102  may be an oxide film. Another purpose of the solution includes binding particles on the surface of the substrate  102  to the coherent film  204  that is maintained on the surface of the substrate  102 . 
   In addition, the solution may include chelating agents, for example, TMAH, acetic acid, citric acid, etc. Furthermore, the solution may also include cleaning components, for example, SC1, SC2, etc. Further still, the solution may also include cleaning solvents or semi-aqueous solvents, for example, EKC265, ST22, Deer Kleen, etc. As discussed previously, the substrate  102  maintains a remaining portion of the solution on its surface to form a coherent film  204 . The coherent film  204  is configured to be cured on the surface of substrate  102 . As the coherent film  204  is cured on the surface of the substrate  102 , any particles on the surface of the substrate  102  are securely bound to the cured coherent film  204 . 
     FIG. 6A  is a diagram of the substrate  102  and the coherent film  204  in accordance with one embodiment of the present invention. As shown in  FIG. 6A , coherent film  204  covers the entire surface of the substrate  102 . The coherent film  204  is formed by the application of a solution on the surface of substrate  102  by a proximity head  104 . The proximity head  104  may have a length that is greater than the diameter of substrate  102 , such that the entire surface of the substrate  104  may be covered by the coherent film  204  by one scan or pass of either the proximity head  104  over the substrate  102  or the substrate  102  beneath the proximity head  104 . 
     FIG. 6B  is a diagram of a close-up view of the substrate  102  and coherent film  204  on a surface of the substrate  102  in accordance with one embodiment of the present invention. The coherent film  204  has incorporated particles  602  found on the surface of substrate  102 . As shown in the figure, the particles  602  are incorporated into the coherent film  204 . 
     FIG. 6C  is a diagram of another close-up view of the substrate  102  and coherent film  204  in accordance with one embodiment of the present invention. This close-up view shows that the coherent film  204  has incorporated particles  602  and interacted with a residue film  604  on the substrate surface  102 . The interaction between the coherent film  204  and the residue film  604  may cause the residue film  604  to dissolve. In another embodiment of the present invention, the interaction between the solution defining the coherent film  204  and the residue film  604  may cause the residue film  604  to be bound to the coherent film  204 . The residue film  604  may be an oxide film that has formed over the surface of substrate  102 , e.g., silicon dioxide. Other residue films may include copper and copper alloys, aluminum and aluminum alloys, silicon nitride, bare silicon, silicon dioxide, low k dielectric films, high k dielectric films, organic films, inorganic films, mixtures of films (i.e. dual damascene structures of patterned SiO2 over copper), implanted films, and the like. 
   The coherent film  204  is configured to be cured on the surface of the substrate  102 . As the coherent film  204  is cured, particles  602  on the surface of the substrate are bound in the cured coherent film  204 . In addition, the undissolved residue film  604  is also bound in the cured coherent film  204 . The cured coherent film  204  may be removed as a cured film of material. By removing the cured coherent film  204 , the particles  602  and residue film  604  or the dissolved components of the residue film  604  are also removed from the surface of the substrate  102  as the cured coherent film  604  is removed. Thus, after the removal of the coherent film  204 , the surface of the substrate is free of particles  602  and the residue film  604  or the dissolved components of the residue film  604 . 
     FIG. 7  is a diagram of another close-up view of the substrate  102  and coherent film  204  in accordance with one embodiment of the present invention.  FIG. 7  shows that the solution forming the coherent film  204  has interacted with the residue film  604 , and the residue film  604  was dissolved. In addition, the coherent film  204  has bound particles  602 . As the coherent film is cured, particles  602  are securely bound within the coherent film  602 . As shown in  FIG. 7 , the coherent film  204  is being removed from the surface of the substrate  102 . The cured coherent film  204  may be removed from the surface of the substrate  102  by any appropriate method. The cured coherent film  204  may be removed mechanically, e.g., the cured coherent film  204  may be mechanically peeled from the surface of substrate  102 . 
   In another embodiment of the present invention, the residue film  604  may not be dissolved by the solution forming the coherent film  204 . Instead, the residue film  604  is incorporate in to the coherent film  204 . After the coherent film  204  is cured, the residue film  604  is securely bound in the cured coherent film  204 . The bound reside film  604  is removed from the surface of the substrate  102  as part of the cured coherent film  204  as the cured coherent film  204  is removed. 
     FIG. 8  shows a close-up side view of substrate  102 , proximity head  104 , and meniscus  202  in accordance with one embodiment of the present invention. The meniscus  202  delivers a solution to a surface of the substrate  102 . As shown in  FIG. 8 , substrate  102  is scanned beneath the proximity head  104 . A plurality of inlet ports  302  deliver a solution to the surface of the substrate  102 , and a plurality of outlet ports  304  remove a portion of the solution. The combination of having the solution being delivered from the plurality of inlet ports  302  and a portion of the solution being removed by the plurality of outlet ports  304  maintains a meniscus between the proximity head  104  and the substrate  102 . A remaining portion of the solution forms a coherent film  204  on the surface of the substrate  102 . 
   In one embodiment of the present invention, the plurality of inlet ports  302  deliver a pre-mixed solution on to the surface of the substrate  102 . The pre-mixed solution contains all the necessary components to interact with a residue film  604  and/or bind particles  602  on the surface of the substrate  102  to the coherent film  204 . 
   In one embodiment of the present invention, the pre-mixed solution may interact with the residue film  604  by dissolving it. In addition, the pre-mixed solution may interact with the particles  602  by binding the particles  602  within the coherent film  204 . In another embodiment of the present invention, the pre-mixed solution may interact with the residue film  604  by incorporating the residue film  604  to the coherent film  204 . As the coherent film  204  is cured, the residue film  604  and particles  602  are bound to the cured coherent film  204 . The residue film  604  and particles  602  are removed as the cured coherent film  204  is removed from the surface of the substrate  102 . 
   In another embodiment of the present invention, the plurality of inlet ports  302  deliver a first sub-solution and a second sub-solution to be mixed on the surface of the substrate  102  to define the solution. As illustrated in  FIG. 8 , inlet ports  302  deliver a first sub-solution  802  and a second sub-solution  804 . The first sub-solution  802  and second sub-solution  804  are mixed on the surface of the substrate  102  to define or form the solution, which is maintained on the surface of the substrate  102  as a coherent film  204 . The first sub-solution  802  may contain a cleaning solution capable of treating a residue film  604  on the surface of the substrate  102 . The second sub-solution  804  may contain a chelating agent that is capable of binding particles  602  to the coherent film  204 . The solution of the coherent film  204  treats the residue film  604  by either dissolving it or incorporating it to the coherent film  204 . As the coherent film  204  is cured and removed, the residue film  604  or the dissolved components of the residue film  604  and particles  602  are also removed from the surface of substrate  102 . 
     FIG. 9  shows a substrate  102 , proximity head  104 , and light source  904  in accordance with one embodiment of the present invention. The light source  904  is coupled to the proximity head  104 . The light source  904  is configured to cure the coherent film  204 . As shown in  FIG. 9 , the proximity head  104  is scanned across the surface of the substrate  102 . The proximity head  104  delivers a solution to form the coherent film  204  on the surface of the substrate  102  by means of a meniscus  202 . The light source  904  is capable of providing any suitable form of light in a sufficient quantity for curing the coherent film  204 . The light source  904  may provide ultra-violet light, infrared light or any suitable form of light that is capable of curing the coherent film  204 . The coherent film  204  is exposure to the light provided by the light source  904 . The coherent film  204  is cured to form a cured coherent film  902 . The cured coherent film  902  can be removed from the surface of the substrate  102  by any suitable mechanical means, e.g., the cured coherent film  902  may be mechanically peeled from the surface of the substrate  102 . 
   In another embodiment of the present invention, the light source  904  may be coupled or incorporated in another part or component of a process chamber for curing the coherent film  204 . 
     FIG. 10  shows a substrate  102 , proximity head  104  and heat source  1002  in accordance with one embodiment of the present invention. The heat source  1002  is configured to cure coherent film  204 . As shown in  FIG. 10 , the proximity head  104  is scanned across the surface of the substrate  102 . The proximity head  104  delivers a solution to form a coherent film  204  on the surface of the substrate  102  by means of a meniscus  202 . The heat source  1002  is coupled to the proximity head  104 . The heat source  1002  is capable of providing a sufficient amount of heat for curing the coherent film  204 . The coherent film  204  is cured to form a cured coherent film  902 . 
   In another embodiment of the present invention, the heat source  1002  may be incorporated in a substrate support to heat and cure the coherent film  204 . In yet another embodiment of the present invention, heat source  1002  may be coupled or incorporated in other parts or components of a process chamber for curing the coherent film  204 . 
     FIG. 11  shows a proximity head  104 ′ scanning over a substrate  102  in accordance with one embodiment of the present invention. Proximity head  104 ′ delivers a first solution by means of a first meniscus  202  on to the surface of a substrate  102  forming a first coherent film  204 . The first coherent film  204  treats the surface of the substrate  102 . Treatment by the first coherent film  204  includes dissolving any residue film of material on the surface of the substrate  102 . In addition, treatment by the first coherent film  204  also includes incorporating particles and any residue film of material that is not dissolved into the coherent film  204 . Furthermore, the solution of the first coherent film may also treat the surface of the substrate  102 , such that the treated surface of the substrate  102  may become hydrophobic or hydrophilic. The proximity head  104 ′ delivers a second solution by means of a second meniscus  1102 . The second solution from meniscus  1102  mixes with the solution of the first coherent film  204  to form a cured coherent film  1104 . The cured coherent film  1104  binds particulates or particles and any residue film of material that is not dissolve to the cured coherent film  1104 . The cured coherent film  1104  is removed by any suitable technique. For example, the cured coherent film  1104  may be removed by any suitable mechanical methods, such as peeling. Particles and residue material on the surface of the substrate  102  may be removed by removing the cured coherent film  1104  from the surface of the substrate  102 . 
     FIG. 12  shows a side view of a substrate  102  and two proximity bars  104  in accordance with one embodiment of the present invention. A first proximity head  104  delivers a first solution by way of a first meniscus  202  on the surface of the substrate  102  to form a coherent film  204 . A second proximity head  104  delivers a second solution by way of a second meniscus  202  on the surface of the substrate  102 . The second solution is mixed with the first solution on the surface of the substrate  102  to form a cured coherent film  1104 . 
     FIG. 13A  shows a residue film  604  and particles  602  on the surface of a substrate  102 . In  FIG. 13A , each particle  602  is shown as having a particular zeta potential, e.g., electrical charge, such as a positive charge or a negative charge. A particle  602  may be attracted to the substrate  102  if the zeta potential of the particle  602  has a opposite potential to that of the substrate  102 . Accordingly, some of the particles  602  are attracted to the substrate  102 . To facilitate the removal of the particles  602  from the surface of the substrate  102 , it would be desirable to have a more negative zeta potential of the particles  602 . 
     FIG. 13B  shows a coherent film  204  being maintained by the substrate  102  according to one embodiment of the present invention. The solution forming the coherent film  204  reacts with the particles  602 . The reaction affects the zeta potential of the particles  602 , such that the particles  602  that were attracted to the substrate  102  are no longer attracted to the substrate  102 . In addition, the solution of the coherent film  204  may also react and dissolve the residue film  604 . 
   In another embodiment of the present invention, the solution of the coherent film  204  may not dissolve the residue film  604 . Instead, the residue film  604  is bound to the coherent film  204 . As the coherent film  204  is removed from the surface of the substrate  102 , the residue film  604  is also removed from the surface of the substrate  102 . 
     FIG. 13C  shows that the coherent film  204  being dissolved and components of the coherent film being bound with particles  602  to form compounds  1302  in accordance with one embodiment of the present invention. In this embodiment, the coherent film  204  may be dissolved by any number of methods, for example, the coherent film  204  may be dissolve by being exposed to a dissolving agent. As the coherent film  204  is dissolved, compounds  1302  are left on the surface of substrate  102 . Compounds  1302  are composed of one or more particles  602  that have reacted with the solution of the coherent film  204 . Since compounds  1302  have a negative zeta potential, they are not attracted to the substrate  102 , and they can be easily removed from the surface of the substrate  102  by any suitable method e.g., spin rinse, etc. After the compounds  1302  are removed, the surface of the substrate  102  is free from residue material and particles. The prepared surface of the substrate  102  as treated by the methods discussed is ready for a next step in the fabrication process (e.g., forming integrated circuits). 
     FIG. 14  is a flow chart detailing a surface preparation process for a substrate in accordance with one embodiment of the present invention. The surface preparation process for a substrate begins by generating a meniscus using a solution in operation  1401 . The meniscus is formed for applying the solution to a surface of the substrate. In operation  1402 , the meniscus is traversed over the surface of the substrate to define a coherent film. The coherent film is maintained on the surface of the substrate. The coherent film is configured to act on the surface of the substrate. The coherent film may dissolve any residue material on the surface of the substrate. In addition, the coherent film may bind particulates that are present on the surface of the substrate. In operation  1403 , the coherent film is cured. In one embodiment, the coherent film may be cured by light, e.g., ultraviolet light, infrared light, etc., that is provide by a suitable light source. In another embodiment, the coherent film may be cured by heat. In operation  1404 , the coherent film may be removed by any suitable means. For example, the coherent film may be removed mechanically, such as the coherent film may be mechanically peeled from the surface of the substrate. 
   Although a few embodiments of the present invention have been described in detail herein, it should be understood, by those of ordinary skill, that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details provided therein, but may be modified and practiced within the scope of the appended claims.