PATENT DOCUMENT

Publication Number: US-9382614-B2
Application Number: US-201414479207-A
Country: US
Kind Code: B2

Title: Defect reduction in meta-mode sputter coatings

Abstract:
Sputter deposition systems and methods for depositing film coatings on one or more substrates are disclosed. The systems and methods are used to prevent or reduce an amount of defects within a deposited film. The methods involve removing defect-related particles that are formed during a deposition process from certain regions of the sputter deposition system and preventing the defect-related particles from detrimentally affecting the quality of the deposited film. In particular embodiments, methods involve creating a flow of gas from a deposition region to a particle collection region the sputter deposition system such that the defect-related particles are entrained within the flow of gas and away from the deposition region. In particular embodiments, the sputter deposition system is a meta-mode sputter deposition system.

Claims:
What is claimed is: 
     
       1. A sputter deposition apparatus configured to deposit a film on a substrate, the sputter deposition apparatus comprising:
 a deposition region configured to accommodate the substrate during a deposition process, the deposition region including a sputter target positioned with respect to the substrate such that a sputter gas directed at the sputter target causes ejection of sputter material from the sputter target, wherein a first portion of the sputter material forms the film on the substrate and a second portion of the sputter material forms defect-related particles; and 
 an impeller configured to remove at least a portion of the defect-related particles from the deposition region by creating a flow of defect-related particles toward a particle collection region of the sputter deposition apparatus during the deposition process. 
 
     
     
       2. The sputter deposition apparatus of  claim 1 , wherein the impeller prevents at least the portion of the defect-related particles in the particle collection region from re-entering the deposition region during the deposition process. 
     
     
       3. The sputter deposition apparatus of  claim 1 , wherein the sputter deposition apparatus is configured to deposit a metal oxide film or a silicon oxide film on the substrate. 
     
     
       4. The sputter deposition apparatus of  claim 1 , wherein the sputter deposition apparatus includes at least one vacuum pump arranged to provide a pressure differential. 
     
     
       5. The sputter deposition apparatus of  claim 1 , wherein the impeller is positioned within the deposition region of the sputter deposition apparatus. 
     
     
       6. The sputter deposition apparatus of  claim 1 , wherein the sputter deposition apparatus comprises a meta-mode sputter apparatus, wherein the impeller comprises at least one blade coupled with a rotating drum that supports the substrate. 
     
     
       7. The sputter deposition apparatus of  claim 1 , wherein the sputter deposition apparatus includes a conduit portion, wherein at least part of the conduit portion has a funnel shape that guides the defect-related particles toward the particle collection region. 
     
     
       8. The sputter deposition apparatus of  claim 1 , wherein the particle collection region is configured to be separated from the deposition region between deposition processes. 
     
     
       9. The sputter deposition apparatus of  claim 1 , wherein the sputter deposition apparatus comprises a meta-mode sputter apparatus, wherein the deposition region comprises:
 a sputter area where the material is sputtered onto the substrate forming a deposited material on the substrate, and 
 a reactive gas area where the deposited material chemically reacts with a reactive gas forming the film. 
 
     
     
       10. The sputter deposition apparatus of  claim 1 , wherein the deposition region is configured to accommodate a plurality of substrates during the deposition process. 
     
     
       11. A method of depositing a film on a substrate, the method comprising:
 directing a sputter gas to a sputter target positioned in a deposition region of a sputter deposition apparatus such that sputter material is ejected from the sputter target, wherein a first portion of sputter material forms the film on a surface of the substrate and a second portion of the sputter material forms defect-related particles; and 
 removing at least a portion of the defect-related particles from the deposition region by rotating an impeller, thereby creating a flow of gas toward a particle collection region of the sputter deposition apparatus such that the at least a portion of the defect-related particles are entrained in the flow of gas and collected at the particle collection region. 
 
     
     
       12. The method of  claim 11 , wherein the at least a portion of the defect-related particles are prevented from re-entering the deposition region during a deposition process. 
     
     
       13. The method of  claim 11 , wherein the defect-related particles collected in the particle collection region are prevented from re-entering the deposition region during a deposition process. 
     
     
       14. The method of  claim 11 , wherein creating the flow of gas comprises creating a pressure differential between the deposition region and the particle collection region. 
     
     
       15. The method of  claim 11 , wherein the deposition region has a first average pressure and the particle collection region has a second average pressure lower than the first average pressure. 
     
     
       16. The method of  claim 11 , wherein the impeller includes at least one blade. 
     
     
       17. The method of  claim 11 , wherein the flow of gas from the deposition region toward the particle collection region prevents the defect-related particles collected at the particle collection region from re-entering the deposition region during a deposition process. 
     
     
       18. The method of  claim 16 , wherein the sputter deposition apparatus is a meta-mode sputter apparatus, wherein the at least one blade is coupled with a rotating drum that supports the substrate. 
     
     
       19. The method of  claim 11 , wherein the flow of gas toward the particle collection region is associated with reducing a uniformity of the film formed on the surface of the substrate, the method further comprising:
 prior to directing the sputter gas to the sputter target, masking a portion of sputter target and/or the substrate compensating for the flow of gas such that the film has a substantially uniform thickness. 
 
     
     
       20. A meta-mode sputter deposition apparatus configured to deposit a film on a substrate, the meta-mode sputter deposition apparatus comprising:
 a deposition region configured to accommodate the substrate during a deposition process, the deposition region including:
 a sputter area having a sputter target positioned with respect to the substrate such that a sputter gas directed at the sputter target causes a first portion of sputter material from the sputter target to deposit onto the substrate and a second portion of sputter material from the sputter target to form defect-related particles, and 
 a reactive gas area configured to expose the first portion of sputter material deposited on the substrate to a reactive gas forming the film; and 
 
 a particle removal system configured to remove at least a portion of the defect-related particles from the deposition region by creating a flow of defect-related particles toward a particle collection region of the meta-mode sputter deposition apparatus during the deposition process, wherein at least one impeller at least partially creates the flow of defect-related particles.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/US14/54297 with an international filing date of Sep. 5, 2014, entitled “DEFECT REDUCTION IN META-MODE SPUTTER COATINGS”, which is incorporated herein by reference in its entirety. 
    
    
     FIELD 
     This disclosure relates generally to sputter deposition systems and methods. In particular embodiments, meta-mode sputter deposition systems and methods designed for reducing defects are described. 
     BACKGROUND 
     Sputter deposition generally involves directing a sputtering gas at a sputter target such that material from the sputter target is ejected onto a substrate as a thin film. One variation of sputter deposition involves use of a meta-mode sputtering system. In meta-mode sputter deposition, material is sputtered onto the substrate in one part of the sputter deposition chamber and then the sputtered-on material is exposed to a reactive gas in another part of the sputter deposition chamber. Meta-mode sputtering systems are typically used to from metal oxides or silicon oxide films on substrates. 
     One of the problems with meta-mode sputtering systems, as well as sputter deposition systems in general, is that internal chamber walls can become coated with sputtered material. This sputtered material can build up and flake off of the chamber walls as defect-related particles during a deposition process. These defect-related particles can then end up co-depositing with the sputtered-on material onto the substrate and reducing the quality of the resultant film. In a product manufacturing process, this can detrimentally affect quality control and lead to poor production throughput. In some cases it can be difficult to suppress the occurrence of particle defects simply by varying standard process parameters. 
     SUMMARY 
     This paper describes various embodiments that relate to sputter deposition systems and methods. In particular embodiments, meta-mode sputter systems and methods are described. The systems and methods described are used to deposit defect-free films on substrates. In particular embodiments, the systems and methods can be used to deposit metal oxide, aluminum oxide, ceramic and other types of films. 
     According to one embodiment, a sputter deposition apparatus configured to deposit a film on a substrate is described. The sputter deposition apparatus includes a deposition region configured to accommodate the substrate during a deposition process. The deposition region includes a sputter target positioned with respect to the substrate such that a sputter gas directed at the sputter target causes ejection of sputter material from the sputter target. A first portion of the sputter material forms the film on the substrate and a second portion of the sputter material forms defect-related particles. The sputter deposition apparatus also includes a particle removal system configured to remove at least a portion of the defect-related particles from the deposition region by creating a flow of defect-related particles toward a particle collection region of the sputter deposition apparatus during a deposition process. 
     According to another embodiment, a method of depositing a film on a substrate is described. The method includes directing a sputter gas to a sputter target positioned in a deposition region of a sputter deposition apparatus such that sputter material is ejected from the sputter target. A first portion of sputter material forms the film on a surface of the substrate and a second portion of the sputter material forms defect-related particles. The method also includes removing at least a portion of the defect-related particles from the deposition region by creating a flow of gas toward a particle collection region of the sputter deposition apparatus such that the at least a portion of defect-related particles are entrained in the flow of gas and collected at the particle collection region preventing the defect-related particles from forming defects in the deposited film. 
     According to a further embodiment, a meta-mode sputter apparatus configured to deposit a film on a substrate is described. The meta-mode sputter apparatus includes a deposition region configured to accommodate the substrate during a deposition process. The deposition region includes a sputter area having a sputter target positioned with respect to the substrate such that a sputter gas directed at the sputter target causes a first portion of sputter material from the sputter target to deposit onto the substrate and a second portion of sputter material from the sputter target to form defect-related particles. The deposition region also includes a reactive gas area configured to expose the first portion of sputter material deposited on the substrate to a reactive gas forming the film. The meta-mode sputter apparatus further includes a particle removal system configured to remove at least a portion of the defect-related particles from the deposition region by creating a flow of defect-related particles toward a particle collection region of the sputter deposition apparatus during a deposition process. 
     These and other embodiments will be described in detail below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG. 1  shows a schematic view of a meta-mode sputter deposition system configured for sputter depositing a thin film. 
         FIG. 2  shows a schematic view of a meta-mode sputter deposition system having a particle collection region and conduit portion for removing and containing defect-related particles from a deposition region of the meta-mode sputter deposition system. 
         FIG. 3  shows a schematic view of a meta-mode sputter deposition system having a particle collection region, conduit portion and vacuum system for removing and containing defect-related particles from a deposition region of the meta-mode sputter deposition system. 
         FIG. 4  shows a schematic view of a meta-mode sputter deposition system having a particle collection region, conduit portion and impellor for removing and containing defect-related particles from a deposition region of the meta-mode sputter deposition system. 
         FIG. 5  shows a perspective view of a drum with blades from the meta-mode sputter deposition of  FIG. 4 . 
         FIG. 6  shows a schematic view of a meta-mode sputter deposition system having a particle collection region, conduit portion, vacuum system and impellor for removing and containing defect-related particles from a deposition region of the meta-mode sputter deposition system. 
         FIG. 7  shows a flowchart indicating a high-level process for sputter depositing a film on a substrate using methods described herein. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, they are intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     The following disclosure relates to sputter deposition systems and improved methods for depositing films on substrates. In particular, methods described herein can be used to reduce defect-related particles within sputtered-on films. Embodiments described herein relate to modifying and/or adding structural features to a sputter deposition system that reduce the amount defect-related particles from becoming deposited with a desired sputtering material, reducing the occurrence of defects within the resultant deposited film. The structural modifications can remove and isolate defect-related particles away from a deposition region of the sputter deposition system such that the defect-related particles do not interfere with the deposition process. In some embodiments, the structural modifications allow for a flow of gas to be created that drive the defect-related particles to a particle collection region of the sputter deposition system. The defect-related particles can be collected in the particle collection region and cleaned from the particle collection region between deposition processes. 
     In particular embodiments, a meta-mode sputtering system is described. In meta-mode sputtering systems, the deposition process occurs in two or more processes. For example, a material can be sputtered on a substrate in one region of a meta-mode sputtering system. The sputtered-on material can then be exposed to a reactive gas in another region of the meta-mode sputtering system. The reactive gas can chemically reacts with the sputtered-on material and forms a film containing the desirable final material. Meta-mode sputtering systems are commonly used to deposit metal oxide or ceramic (e.g., silicon dioxide) films. Embodiments described herein can be used to modify meta-mode sputtering systems to reduce the amount of defects in the final film. 
     Methods described herein are well suited for providing thin films used in the manufacture of portions of electronic devices and electronic device accessories, such as those manufactured by Apple Inc., based in Cupertino, Calif. For example, the methods described herein can be used in the manufacture of electronic displays and/or touch screens for electronic devices and accessories. In particular embodiments, the methods described can be used to form dielectric and/or optical layers or coatings as part of electronic devices. 
     These and other embodiments are discussed below with reference to  FIGS. 1-7 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these Figures is for explanatory purposes only and should not be construed as limiting. 
     As described above, methods described herein can be used to reduce defects and improve film quality of thin films produced using sputter deposition systems. In some embodiments, the sputter deposition systems are meta-mode deposition systems. Note that the methods can be adapted for use in any suitable sputter deposition system and are not limited to meta-mode sputter systems. 
       FIG. 1  shows sputter deposition system  100  configured for sputter depositing a thin film. Sputter deposition system  100  is a meta-mode sputter system that includes chamber  102 , sputter target  104 , plasma source  108 , drum  110  and vacuum system  112 . Vacuum system  112  is configured to apply a vacuum within chamber  102  and includes roughing vacuum pump  114  and high vacuum pump  116 . Drum  110  is configured to support substrates  106  and is configured to rotate about axis  120  such that substrates  106  can be rotated between sputter area  122  and reactive gas area  124  of sputter deposition system  100 . Sputter area  122  and reactive gas area  124  can collectively be referred to as a deposition region  126  of sputter deposition system  100 . 
     During a deposition process, a sputter gas (not shown) is directed to sputter target  104  such that material from sputter target  104  is ejected from sputter target and sputtered onto substrates  106  in sputter area  122 . The sputter gas can be any type of suitable reactive gas and can be directed to sputter target  104  at any suitable pressure, as dictated by particular application requirements. In some embodiments, the sputter gas includes ionic species. Sputter target  104  can be made of any suitable sputtering material, including a metal and/or silicon. In some embodiments, sputter target  104  includes an oxidizable material such as one or more oxidizable metal and/or silicon materials. 
     Drum  110  rotates about axis  120  such that substrates  106  are translated from sputter area  122  to reactive gas area  124  of sputter deposition system  100 . Plasma source  108  produces plasma and/or otherwise reactive gas within reactive gas area  124  such that substrates  106  positioned within reactive gas area  124  are exposed to plasma and/or reactive gas. The sputtered-on material on substrates  106  chemically reacts with the reactive gas producing a film having the desired final material. The plasma and/or reactive gas can include any suitable reactive chemical species. For example, the plasma and/or reactive gas can include ions, radicles and/or molecules. In some embodiments, the plasma and/or reactive gas include oxidative species such as reactive species of oxygen, such as oxygen ions, radicles and/or molecules. For example, if the desired material is a metal oxide material, metal material sputtered-on at sputter area  122  can react with an oxidative a plasma and/or reactive gas at reactive gas area  124  forming a metal oxide film on substrates  106 . Similarly, if the desired material is a silicon oxide material (e.g., silicon dioxide), silicon material sputtered-on at sputter area  122  can react with an oxidative reactive gas at reactive gas area  124  forming a silicon oxide film on substrates  106 . In some cases, the plasma and/or reactive gas can include one or more non-reactive gases as a carrier. In some embodiments, the plasma and/or reactive gas is further activated using radiation, such as microwave radiation. 
     Once the film having a desired material is formed. In some embodiments, drum  110  is rotated further such that substrates  106  once again enter sputter area  122  and another layer of material is sputtered on the already-formed layer of film. Drum  110  can then be rotated further such that the additional sputtered-on material is reacted with the plasma and/or reactive gas at reactive gas area  124 . In this way, a deposition process can include forming a film in one or more layering processes. The thickness of the final film can be partially controlled by the number of rotations of drum  110  and an exposure time of substrates  106  during the deposition process. 
     During a sputter deposition process, material from sputter target  104  can not only be sputtered onto substrates  106  but can also be sputtered onto other surfaces within chamber  102  and be scattered throughout an internal volume of chamber  102 . For example, portions of material can be sputtered onto internal surfaces of chamber  102  and various shields within chamber  102 , especially within sputter area  122 . This sputtered-on material on internal surfaces of chamber  102  can eventually flake or peel off these internal surfaces in the form of defect-related particles  118  that can become stirred up into and float within the plasma and/or gases within deposition region  126 . In addition, portions of material can be sputtered onto surfaces of drum  110 . Other portions of sputter material can remain in aerosol form and float within the plasma and/or gases within different portions of chamber  102 . In some chamber configurations, gravity pulls larger defect-related particles  118  to bottom surfaces of chamber  102 , where the defect-related particles  118  can then be swooped-up again within the flow of plasma and/or gases and into different portions of chamber  102 . 
     The make-up of defect-related particles  118  will depend upon the material of sputter target  104  and the chemical species within the reactive gas. For example, silicon oxide deposition where the sputter target  104  contains silicon and the reactive gas contains oxygen can produce defect-related particles  118  made of silicon and/or silicon oxide materials. Similarly, metal oxide deposition where sputter target  104  contains a metal material and the reactive gas contains oxygen can produce defect-related particles  118  made of metal and/or metal oxide materials. The size of defect-related particles  118  can vary. In some cases, the average size of defect-related particles  118  ranges from about a few micrometers to about a few hundred micrometers in diameter or width. 
     Defect-related particles  118  are associated with an amount of defects within film formed on substrates  106  that can degrade the quality of the final film. For example, defect-related particles  118  can become co-deposited with material sputtered onto substrates  106  at sputter area  122 . Defect-related particles  118  can also cause “pin hole” defects within the deposited film. Alternatively or additionally, defect-related particles  118  can interfere with the chemical reactions taking place within reactive gas area  124 . As described above, the meta-mode sputter system  100  includes drum  110  that rotates about axis  120 . The rotating action of drum  102  can create turbulence within chamber  102  and further stir up any defect-related particles  118  increasing the amount of defect-related particles  118  floating within chamber  110  and exacerbating the defect problems. If defect-related particles  118  are made of dielectric material (e.g., silicon oxide and metal oxide materials), defect-related particles  118  can cause arcing within chamber  102  during a deposition process, making the deposition process difficult to control and to provide consistent results. 
     To ameliorate these defect-related particle issues, in some embodiments, sputter area  122  can be separated from reactive gas area  124  using, for example baffles (not shown) that physically isolate sputter area  122  from reactive gas area  124 . However, this may not prevent sputter material from building up on and flaking off of surfaces within sputter area  122  in the form of defect-related particles  118 . Therefore, other methods can be used to modify sputter deposition system  100  to remove defect-related particles from sputter area  122  and/or reactive gas area  124  during deposition processes. 
       FIG. 2  shows sputter deposition system  200 , which includes modifications that can reduce the occurrence of defects related to defect-related particles. Sputter deposition system  200  includes chamber  202 , sputter target  204 , plasma source  208 , drum  210  and vacuum system  212 . Chamber  202  includes deposition region  226  where the deposited film is formed. Vacuum system  212  is configured to apply a vacuum within chamber  202 , including deposition region  226 . In some embodiments, vacuum system  212  includes roughing vacuum pump  214  and high vacuum pump  216 . Sputter deposition system  200  is a meta-mode sputter system where deposition region  226  includes sputter area  222  and reactive gas area  224 . Drum  210  supports substrates  206  and rotates about axis  220  such that substrates  206  can be rotated between sputter area  222  and reactive gas area  224 . It should be noted that the modifications provided herein can be used in any suitable sputter deposition process and are not limited to meta-mode sputter systems. In addition, any number of substrates  206  can be used, including one or more substrates  206 . 
     During a deposition process, a sputter gas (not shown) is directed to sputter target  204  such that material from sputter target  204  is ejected from sputter target  204  and sputtered onto substrates  206  in sputter area  222 . In some embodiments, about 1-3 monolayers of sputtered-on material (e.g., 1-3 monolayers of metal or silicon) are sputtered onto substrates  206 , corresponding to about 3-10 angstroms thickness. Drum  210  rotates substrates  206  to reactive gas area  224  where plasma source  208  produces plasma and/or other form of reactive gas within reactive gas area  224 . The sputtered-on material on substrates  206  is exposed to and chemically reacts with the plasma and/or reactive gas producing a film on substrates  206  having the desired film material. In some embodiments, drum  210  is rotated further such that substrates  206  once again enter sputter area  222  and another layer of material is sputtered on the already-formed layer of film. Drum  210  can then be rotated further such that the additional sputtered-on material reacts with the plasma and/or reactive gas at reactive gas area  224 . Drum  210  can continue to rotate so that substrates  206  can undergo deposition for any suitable deposition time, as dictated by particular application requirements. 
     As described above, material from sputter target  204  can be sputtered onto surfaces within chamber  202  and be scattered throughout an internal volume of chamber  202 . This material can flake off in the form of defect-related particles  218  and cause defects within the films deposited on substrates  206 . To remove defect-related particles  218  from deposition region  226 , sputter deposition system  200  includes particle collection region  228  that is configured to contain defect-related particles  218 . According to some embodiments, particle collection region  228  is positioned such that defect-related particles  218  fall toward particle collection region  228  due to the force of gravity. For example, particle collection region  228  can be positioned at a bottom portion of chamber  202  such that the force of gravity creates a flow of defect-related particles  218  away from deposition region  226  toward particle collection region  228 . According to some embodiments, sputter deposition system  200  includes conduit portion  230 , which provides access to particle collection region  228 . As shown, conduit portion  230  can have a narrower diameter than deposition region  226 . In some embodiments, funnel shaped portion  232  of conduit portion  230  has a funnel shape that can guide the defect-related particles  218  toward particle collection region  228 . For example, defect-related particles  218  can slide down walls of funnel-shaped portion  232  and into particle collection region  228 . In some embodiments, substantially all of conduit portion  230  has a funnel shape. Particle collection region  228  can be cleaned of defect-related particles  218  between one or more deposition process. In some embodiments, particle collection region  228  is configured for easy separation from deposition region  226  between deposition processes for cleaning. For example, particle collection region  228  can be a separable chamber that is attached to chamber  202  with a gasket seal. 
       FIG. 3  shows sputter deposition system  300 , which includes alternative/additional features that can reduce the occurrence of defects in a deposited film. Similar to systems  100  and  200 , sputter deposition system  300  includes chamber  302 , sputter target  304 , plasma source  308 , drum  310  and vacuum system  312  (including roughing vacuum pump  314  and high vacuum pump  316 ). Deposition region  326  of sputter deposition system  300  includes sputter area  322  and reactive gas area  324 . Similar to system  200 , sputter deposition system  300  includes particle collection region  328  and conduit portion  330  having funnel shaped portion  331  that can direct defect-related particles  318  toward particle collection region  328 . Note, however, that in some embodiments sputter deposition system  300  does not have a conduit portion  330  with funnel shaped portion  331 . For example, bottom portion of chamber  302  can have a flat or planar shape, similar to chamber  102  of system  100 . 
     Sputter deposition system  300  includes vacuum system  332 , which is configured proximate particle collection region  328  such that a pressure differential is formed between deposition region  326  and particle collection region  328 . In particular, vacuum system  332  can pump out and apply more vacuum to particle collection region  328 , and/or regions proximate to particle collection region  328  such as conduit portion  330 , compared to deposition region  326 . That is, the pressure within particle collection region  328  and surrounding areas such as conduit portion  330  will be lower than the pressure within deposition region  326 . Per Bernoulli&#39;s principle, the decreased pressure at and/or near particle collection region  328  causes gas, with defect-related particles  318  entrained therein, to accelerate toward particle collection region  328 . This can create or increase an already existing flow of defect-related particles  318  away from deposition region  326  toward particle collection region  328 . Vacuum  332  can include any suitable mechanism for creating a vacuum, including one or more vacuum pumps. In some embodiments, vacuum system  332  includes roughing pump  334  and high vacuum pump  336 . 
       FIG. 4  shows sputter deposition system  400 , which includes alternative/additional features that can reduce the occurrence of defects in a deposited film. Similar to systems  100 ,  200  and  300 , sputter deposition system  400  includes chamber  402 , sputter target  404 , plasma source  408 , drum  410  and vacuum system  412  (including roughing vacuum pump  414  and high vacuum pump  416 ). Deposition region  426  of sputter deposition system  400  includes sputter area  422  and reactive gas area  424 . Similar to systems  200  and  300  sputter deposition system  400  includes particle collection region  428  and conduit portion  430  having funnel shaped portion  431  that can direct defect-related particles  418  to particle collection region  428 . Note that in some embodiments sputter deposition system  400  does not have conduit portion  430  with funnel shaped portion  431 . For example, bottom portion of chamber  402  can have a flat or planar shape, similar to chamber  102  of system  100 . 
     Sputter deposition system  400  also includes an impeller that creates or adds to the flow or downdraft of gas and defect related particles  418  toward particle collection region  428 . In particular, one or more blades  438  are coupled to drum  410 , which rotates in order to move substrates  406  between sputter area  422  and reactive gas area  424  during a deposition process. In this way, blades  438  will rotate in accordance with the rotation of drum  410 , acting as an impeller or fan that creates or adds to the flow of gas from deposition region  426  toward particle collection region  428 . Defect-related particles  418  can become entrained in this flow of gas and become contained within particle collection region  428 . Blades  438  can be attached to any suitable portion of drum  410 . For example, blades  438  can be attached to a bottom portion of drum  410  proximate particle collection region  428 , such as shown in  FIG. 4 . In some embodiments, blades  438  are attached to a different portion of drum  410 . In other embodiments, one or more separate impellers or fans (not shown) are positioned within deposition region  426  that provide a flow of gas with defect-related particles  418  toward particle collection region  428 . 
       FIG. 5  shows a perspective view of drum  410  having blades  438  attached thereto. Blades  438  can be added on as extensions to panels  502 , which are rigid structures arranged within drum  410  to provide structural support to drum  410 . That is, panels  502  can be arranged within drum  410  to provide and maintain a shape to drum  410 , and as such can be referred to collectively as a skeletal structure for drum  410 . Blades  438  can be integral extensions of panels  502  or can be added to panels  502  as separate extension pieces. Blades  438  can have any suitable shape and have any suitable length/width, depending on design choice and process requirements. In some embodiments, blades  438  are shaped and sized to maximize unidirectional flow toward particle collection region  428 . For example, blades  438  can each have a curved shape or substantially planar shape. Blades  438  can be coplanar with each corresponding panel or blades  438  can be set at angles relative to blades  438 . In the embodiment shown in  FIG. 5 , drum  410  includes five blades  438 . It should be understood, however, that any suitable number of blades  438  can be used. In some cases, the number of blades  438  will depend upon the number of panels  502  of drum  410 . In some cases, the number of blades  438  will depend upon the resultant flow efficiency. In some embodiments, only one blade  438  is used. 
       FIG. 6  shows sputter deposition system  600 , which includes a combination of aspects of sputter deposition systems  100 ,  200 ,  300  and  400  described above. Similar to systems  100 ,  200 ,  300  and  400 , sputter deposition system  600  includes chamber  602 , sputter target  604 , plasma source  608 , drum  610  (configured to rotate about axis  620 ) and vacuum system  612  (including roughing pump  614  and high vacuum pump  616 ). Deposition region  626  includes sputter area  622  and reactive gas area  624 . Sputter deposition system  600  includes a combination of features that together can create a flow of gas and defect-related particles  618  away from deposition region  626  during a deposition process. In particular, sputter deposition system  600  includes particle collection region  628 , conduit portion  630  (with funnel shaped portion  631 ), vacuum system  632  (including roughing pump  634  and high vacuum pump  636 ) and blades  638 . In some cases, the combination of these different features provides optimal removal of defect-related particles  618  from deposition region  626  and the fewest amounts of particle-related defects on substrates  606   a - 606   c.    
     Note that while the addition of one or more of conduit portion  630  (with funnel shaped portion  631 ), vacuum system  632  and blades  638  can create a flow of gas that drives defect-related particles  618  to particle collection region  628 , in some cases, this same flow of gas can change the working conditions during a sputter deposition process. For example, the flow of gas away from sputter area  622  can cause less sputter material to be present for sputtering onto substrates  606   a - 606   c . In particular, less sputter material may be sputtered onto substrates  606   c  compared to substrates  606   a  and  606   b  since substrates  606   c  are closer to particle collection region  628  compared to substrates  606   a  and  606   b . In addition, the flow of gas away from reactive gas area  624  can pull away more of the reactive gas for reacting with the material sputtered onto substrates  606   a - 606   c . In particular, less reactive gas may be available for reacting with material sputtered onto substrates  606   c  compared to substrates  606   a  and  606   b . Thus, the flow of gas that pulls defect-related particles  618  away from deposition region  626  can cause non-uniform deposition and/or reaction at substrates  606   a - 606   c , and in particular, less deposition and/or reaction at substrates  606   c  compared to substrates  606   a  and  606   b . This can result in substrates  606   c  having a thinner film than the film formed on substrates  606   a  and  606   b.    
     To compensate for the potential non-uniform deposition and/or reaction, in some cases it may be beneficial to change the process parameters during a deposition process. For example, more or less sputter material (by way of an amount of sputter gas) and/or reactive gas than normally used can be introduced. The amount of sputter material and/or reactive gas can be tuned to compensate for a corresponding amount of non-uniform deposition and/or reaction. Alternatively or in addition to changing the amount of sputter material and/or reactive gas, portions of sputter target  604  and/or substrates  606   a - 606   c  can be masked during a deposition process. For example, a mask (not shown) can be placed on portion  604   a  of sputter target  604  to lessen the amount of material sputtered onto substrates  606   a  and  606   b  to approximate the relatively lesser amount of material sputtered onto substrates  606   c . In this way, the process conditions can be tuned such that the film formed on substrates  606   c  have a thickness that is substantially the same as a thickness of the film formed on substrates  606   a  and  606   b . Similar modifications can be implemented in embodiments where only one substrate is used to assure that the resultant film has a substantially uniform thickness across a surface of the substrate. 
       FIG. 7  shows flowchart  700 , which indicates a high-level process for sputter depositing a film on a substrate using methods described herein. The sputter deposition process can be performed using any suitable sputter deposition system, including a meta-mode sputter deposition system. At  702 , a sputter material is sputtered from a sputter target such that a first portion of the sputter material forms a film on the substrate and a second portion of the sputter material forms defect-related particles. If the sputter deposition system is a meta-mode sputter deposition system, the first portion the sputter material sputters onto the substrate in a sputter area and reacts with a reactive gas in a reactive gas area of the meta-mode sputter deposition system. The working pressure during the sputter deposition process will depend upon any of a number of variables. Typical working pressures within the sputter deposition region using a meta-mode sputter system ranges within about a few millitorr (mtorr). The thickness of the deposited film will depend on process conditions and a desired final thickness. 
     The second portion of the sputter material forms defect-related particles by first sputtering onto internal surfaces within the deposition chamber other than the substrate, then by flaking off these internal surfaces in the form of defect-related particles. The make-up of the defect-related particles will depend on the sputter material and the reactive gas(es). In some embodiments, the defect-related particles include a dielectric material, such as a metal oxide and/or a silicon oxide. 
     At  704 , the defect-related particles are removed from the deposition region to a particle collection region of the sputter deposition system. In some embodiments, the particle collection region is positioned such that the force of gravity pulls the defect-related particles to the particle collection region, such as below the deposition region. In some embodiments, the sputter deposition system includes a conduit portion, at least a portion of which has a funnel-shape that allows the defect-related particles to slide down into the particle collection region. 
     According to some embodiments, the sputter deposition system includes one or more vacuum systems that create pressure differential between the deposition region and the particle collection region of the sputter deposition system. In particular, the vacuum system(s) create less pressure at and near the particle collection region compared to the deposition region, which forces gas and the defect-related particles to accelerate toward the particle collection region. According to some embodiments, the sputter deposition system includes one or more internal impellers (or fans). The impellers have one or more blades that rotate during a deposition process and create a flow (e.g., downdraft) of gas and defect-related particles toward the particle collection region. In some embodiments, the impeller is formed adding one or more blades to a rotating drum of a meta-mode sputter deposition system. The rotating drum supports and rotates one or more substrates from the sputter area to the reactive gas area during a deposition process. The attached one or more blades rotate with the drum creating the flow or downdraft. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not target to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Metadata:
Filing Date: 20140905
Publication Date: 20160705
Grant Date: 20160705
Priority Date: 20140905
Inventors: ZHONG JOHN Z.
KANG SUNGGU
BAE WOOKYUNG
Assignee: APPLE INC
CPC Classifications: [{"code": "H01J37/32449", "inventive": true, "first": true, "tree": "[]"}, {"code": "C23C14/5873", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01J37/3488", "inventive": true, "first": false, "tree": "[]"}, {"code": "C23C14/5846", "inventive": true, "first": false, "tree": "[]"}, {"code": "C23C14/564", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01J37/3488", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01J37/32853", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01J37/3476", "inventive": true, "first": false, "tree": "[]"}, {"code": "C23C14/5846", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01J37/32871", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01J37/32449", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01J37/3476", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01J37/32853", "inventive": true, "first": false, "tree": "[]"}, {"code": "C23C14/564", "inventive": true, "first": false, "tree": "[]"}, {"code": "C23C14/5873", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01J37/32871", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 55436986