Patent Publication Number: US-2023151489-A1

Title: Deposition Apparatus and Method

Description:
PRIORITY CLAIM AND CROSS-REFERENCE 
     This application claims the benefit of U.S. Provisional Application No. 63/278,581, filed on Nov. 12, 2021, which application is hereby incorporated herein by reference. 
    
    
     BACKGROUND 
     Semiconductor devices are used in a variety of electronic applications, such as, for example, personal computers, cell phones, digital cameras, and other electronic equipment. Semiconductor devices are typically fabricated by sequentially depositing insulating or dielectric layers, conductive layers, and semiconductor layers of material over a semiconductor substrate, and patterning the various material layers using lithography to form circuit components and elements thereon. 
     The semiconductor industry continues to improve the integration density of various electronic components (e.g., transistors, diodes, resistors, capacitors, etc.) by continual reductions in minimum feature size, which allow more components to be integrated into a given area. However, as the minimum features sizes are reduced, additional problems arise that should be addressed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. 
         FIGS.  1 A and  1 B  illustrate cross-sectional views of a deposition system in accordance with some embodiments. 
         FIG.  2    illustrates a cross-sectional view of a substrate in accordance with some embodiments. 
         FIG.  3    is a flow diagram illustrating a deposition method in accordance with some embodiments. 
         FIG.  4    is a flow diagram illustrating a deposition method in accordance with some embodiments. 
         FIG.  5    illustrates a cross-sectional view of a deposition system in accordance with some embodiments. 
         FIGS.  6 A- 6 C  illustrate three-dimensional and cross-sectional views of a deposition system in accordance with some embodiments. 
         FIG.  7    is a flow diagram illustrating a deposition method in accordance with some embodiments. 
         FIG.  8    is a flow diagram illustrating a deposition method in accordance with some embodiments. 
         FIG.  9    illustrates a cross-sectional view of a deposition system in accordance with some embodiments. 
         FIG.  10    is a flow diagram illustrating a deposition method in accordance with some embodiments. 
         FIG.  11    is a flow diagram illustrating a deposition method in accordance with some embodiments. 
         FIG.  12    illustrates a cross-sectional view of a deposition system in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. 
     Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly. 
     Embodiments will be described with respect to a specific context, namely, a deposition apparatus and method. In some embodiments, a deposition apparatus comprises one or more electromagnetic (EM) radiation sources, such as an ultraviolet (UV) source or a laser source, that dissociate, heat and/or excite precursor material within a chamber of the deposition apparatus. In some embodiments, one or more EM radiation sources are used to burn cluster defects formed in a layer deposited over a substrate and reduce defect levels within the deposited layer. Various embodiments discussed herein allow for depositing void-free and seam free layers with reduced impurity and defect levels, and providing additional parameters (such as, for example, EM radiation intensity and/or wavelength) for tuning the deposition process (for example, tuning a composition of the deposited layer). 
       FIGS.  1 A and  1 B  illustrate a deposition system  100  in accordance with some embodiments.  FIG.  1 A  illustrates a cross-sectional view in accordance with some embodiments.  FIG.  1 B  illustrates a detailed view of a region  129  of the deposition system  100  (see  FIG.  1 A ) in accordance with some embodiments. The deposition system  100  may be utilized to deposit a deposited layer  201  over a substrate  200 , which may be, for example, a semiconductor structure, a wafer, a device, a package, another structure, or the like. 
     As described below in greater detail, the deposition system  100  may perform a deposition process, such that thermal energy, plasma energy, and/or EM radiation energy (such as UV or laser energy) provide deposition energy during the deposition process. In some embodiments when the deposition process uses the thermal energy as the deposition energy, the deposition process performs a thermal deposition process, such as, for example, atomic layer deposition (ALD), chemical vapor deposition (CVD), or the like. In some embodiments when the deposition process uses the plasma energy as the deposition energy, the deposition process performs a plasma assisted deposition process, such as, for example, plasma enhanced ALD (PEALD), plasma enhanced CVD (PECVD), or the like. In some embodiments when the deposition process uses the plasma energy and the EM radiation energy (such as UV or laser energy) as the deposition energy, the deposition process performs a plasma and laser assisted deposition (PLAD) process, such as, for example, plasma and laser enhanced ALD, plasma and laser enhanced CVD, or the like. 
     The deposition system  100  comprises a chamber  101  and an inlet  103  configured to accept and deliver a desired precursor material into the chamber  101  and to a showerhead  105 . The showerhead  105  may be utilized to disperse the chosen precursor material(s) into the chamber  101  and may be designed to evenly disperse the precursor material in order to minimize undesired process conditions that may arise from uneven dispersal. In an embodiment, the showerhead  105  may have a circular design with openings dispersed evenly around the showerhead  105  to allow for the dispersal of the desired precursor material into the chamber  101 . 
     However, as one of ordinary skill in the art will recognize, the introduction of precursor materials to the chamber  101  through a single showerhead  105  or through a single point of introduction as described above is intended to be illustrative only and is not intended to be limiting to the embodiments. Any number of separate and independent showerheads and/or other openings to introduce precursor materials into the chamber  101  may be utilized. All such combinations of showerheads and other points of introduction are fully intended to be included within the scope of the embodiments. 
     The chamber  101  may receive the desired precursor materials and expose the substrate  200  to the precursor materials, and the chamber  101  may be any desired shape that may be suitable for dispersing the precursor materials and contacting the precursor materials with the substrate  200 . In the embodiment illustrated in  FIG.  1 A , the chamber  101  has a cylindrical sidewall and a bottom. However, the chamber  101  is not limited to a cylindrical shape, and any other suitable shape, such as a hollow square tube, an octagonal shape, or the like, may be utilized. Furthermore, the chamber  101  may be made of material that is inert to the various process materials. As such, while the chamber  101  may be made of any suitable material that can withstand the chemistries and pressures involved in the deposition process, in some embodiments, the chamber  101  may be made of steel, stainless steel, nickel, aluminum, alloys of these, combinations of these, or like. 
     Within the chamber  101 , the substrate  200  may be placed on a mounting platform  107  in order to position and control the substrate  200  during the deposition processes. The mounting platform  107  may include heating mechanisms  109  in order to heat the substrate  200  during the deposition processes. The heating mechanisms  109  may be resistive heating elements or the like. The mounting platform  107  may be also referred to as a pedestal or a chuck. In the illustrated embodiment, the mounting platform  107  has a same diameter as the showerhead  105 . 
     In some embodiments, a precursor material may be ignited into a plasma  135  in order to assist in the deposition process. The plasma  135  comprises dissociated components (such as electrically charged and/or neutral components) of the precursor material. In such embodiment, the mounting platform  107  may additionally comprise a first electrode  111 . The first electrode  111  may be grounded or biased by a desired voltage source (not shown). By being electrically biased, the first electrode  111  is used to provide a bias to the incoming precursor material as well as assist to ignite the precursor material into a plasma. Additionally, the first electrode  111  is also utilized to maintain the precursor plasma during the deposition process by maintaining the bias. 
     In some embodiments, the showerhead  105  may also be or comprise (or otherwise incorporate) a second electrode  113  coupled to a power source  115 . The power source  115  is utilized to provide power to the second electrode  113  in order to ignite the plasma  135  during introduction of the precursor material. The power source  115  may be a low frequency (LF) power source (operating at frequencies between about 100 kHz to about 400 kHz), a radio frequency (RF) power source (operating at frequencies of about 13.56 MHz, about 27.12 MHz, about 60 MHz, or about 80 MHz), a microwave (MW) power source (operating at a frequency of about 2.45 GHz), or the like. In some embodiments, the power source  115  may provide a power between about 10 W and 3000 W. 
     However, while the deposition system  100  is descried above as an in situ capacitively coupled plasma (CCP) system, embodiments are not intended to be limited to the in situ CCP system. Rather, any suitable in situ or remote plasma systems, such as inductively coupled plasma systems, magnetically enhanced reactive ion etching, electron cyclotron resonance systems, or the like, may be utilized. All such systems are fully intended to be included within the scope of the embodiments. 
     Furthermore, while a single mounting platform  107  is illustrated in  FIG.  1 A , any number of mounting platforms may additionally be included within the chamber  101 . Additionally, the chamber  101  and the mounting platform  107  may be part of a cluster tool system (not shown). The cluster tool system may be used in conjunction with an automated handling system in order to position and place the substrate  200  into the chamber  101  prior to the deposition processes, position, hold the substrate  200  during the deposition processes, and remove the substrate  200  from the chamber  101  after the deposition processes. 
     The chamber  101  may also have an exhaust outlet  117  for exhaust gases to exit the chamber  101 . A vacuum pump (not shown) may be connected to the exhaust outlet  117  of the chamber  101  in order to help evacuate the exhaust gases. The vacuum pump may also be utilized to reduce and control the pressure within the chamber  101  to a desired pressure and may also be utilized to evacuate precursor materials from the chamber  101  in preparation for the introduction of the next precursor material. 
     In some embodiments, the deposition system  100  comprises one or more electromagnetic (EM) radiation sources  119  that are coupled to the chamber  101 . The EM radiation sources  119  may be ultraviolet (UV) or laser systems, such as an F 2  system (operating at 157 nm wavelength), an ArF system (operating at 193 nm wavelength), a Nd:YAG system (operating at 213 nm, 266 nm, 355 nm, or 532 nm wavelengths), a He—Ag system (operating at 224.3 nm wavelength), a KCl system (operating at 222 nm wavelength), a KrF system (operating at 248 nm wavelength), a XeCl system (operating at 308 nm wavelength), a He—Cd system (operating at 325 nm wavelength), an N 2  system (operating at 337.1 nm wavelength), a XeF system (operating at 351 nm wavelength), a He—Cd system (operating at 441.6 nm wavelength), or the like. In some embodiments, an EM radiation  121  (indicated by arrows in  FIG.  1 A ) generated by the EM radiation sources  119  propagate in the chamber  101  between the showerhead  105  and the mounting platform  107 . The EM radiation  121  further dissociates, heats or excites the precursor material. In some embodiments, the EM radiation sources  119  is chosen based on the precursor material, such that the EM radiation  121  from the EM radiation sources  119  is able to dissociate, heat or excite the precursor material. In the illustrated embodiment, the deposition system  100  comprises two EM radiation sources  119 . In other embodiments, the deposition system  100  may comprise one or more than two EM radiation sources  119 . In some embodiments, energy of the EM radiation sources  119  may be in a range from about 1 eV to about 20 eV. 
     In some embodiments, the EM radiation  121  from each of the EM radiation sources  119  enters the chamber  101  through a respective window  123  in the chamber  101 . The material for the windows  123  are chosen to provide good vacuum isolation to the chamber  101  as well as be transparent to the EM radiation  121 . In some embodiments, the windows  123  are made of quartz, glass, a combination thereof, or the like. 
     In some embodiments, the chamber  101  comprises inlets  125  near respective windows  123 . Each of the inlets  125  is configured to accept a desired gas  131  (indicated by dashed arrows in  FIG.  1 B ) and form a gas curtain  133  in front of the respective window  123 . The gas  131  may comprise an inert gas such as He gas, Ne gas, Ar gas, a combination thereof, or the like. In some embodiments, the gas curtains  133  are used to protect the windows  123 , such that the material deposited over the substrate  200  is not also deposited on the windows  123 . Accordingly, lifetime of the windows  123  is increased and reduction of the intensity of the EM radiation  121  is avoided. In some embodiments, each of the inlets  125  comprises a valve  127  that is used to control a flow rate of the gas  131 . 
       FIG.  2    illustrates a cross-sectional view of a substrate  200  in accordance with some embodiments. In some embodiments, the substrate  200  may be a wafer-level structure. In other embodiments, the substrate  200  may be a die-level structure. In some embodiments, the substrate  200  comprises a semiconductor substrate  203 , such as silicon, doped or undoped, or an active layer of a semiconductor-on-insulator (SOI) substrate. The semiconductor substrate  203  may include other semiconductor materials, such as germanium; a compound semiconductor including silicon carbide, gallium arsenic, gallium phosphide, indium phosphide, indium arsenide, and/or indium antimonide; an alloy semiconductor including SiGe, GaAsP, AlInAs, AlGaAs, GaInAs, GaInP, and/or GaInAsP; or combinations thereof. Other substrates, such as multi-layered or gradient substrates, may also be used. The semiconductor substrate  203  has an active surface (e.g., the surface facing upwards in  FIG.  2   ), sometimes called a front side, and an inactive surface (e.g., the surface facing downwards in  FIG.  2   ), sometimes called a backside. 
     Devices (represented by a transistor)  205  may be formed at the front surface of the semiconductor substrate  203 . The devices  205  may be active devices (e.g., transistors, diodes, etc.), capacitors, resistors, inductors, the like, or combinations thereof. An inter-layer dielectric (ILD)  207  is over the front surface of the semiconductor substrate  203 . The ILD  207  surrounds and may cover the devices  205 . The ILD  207  may include one or more dielectric layers formed of materials such as Phospho-Silicate Glass (PSG), Boro-Silicate Glass (BSG), Boron-Doped Phospho-Silicate Glass (BPSG), undoped Silicate Glass (USG), or the like, and may be formed using spin coating, lamination, ALD, CVD, or the like. 
     Conductive plugs  209  extend through the ILD  207  to electrically and physically couple to the devices  205 . For example, when the devices  205  are transistors, the conductive plugs  209  may couple to the gates and source/drain regions of the transistors. The conductive plugs  209  may be formed of tungsten, cobalt, nickel, copper, silver, gold, aluminum, the like, or combinations thereof. 
     An interconnect structure  211  is over the ILD  207  and the conductive plugs  209 . The interconnect structure  211  interconnects the devices  205  to form an integrated circuit. The interconnect structure  211  may be formed by, for example, metallization patterns  211 B in inter-metal dielectrics (IMDs)  211 A on the ILD  207 . The IMDs  211 A may be formed using similar material and methods as the ILD  207 . The metallization patterns  211 B may be formed of tungsten, cobalt, nickel, copper, silver, gold, aluminum, the like, or combinations thereof. The metallization patterns  211 B include metal lines and vias within the IMDs  211 A. In some embodiments, the interconnect structure  211  may be formed of alternating layers of dielectric (e.g., low-k dielectric material) and conductive (e.g., copper) materials with vias interconnecting the layers of the conductive material and may be formed through any suitable process (such as deposition, damascene, dual damascene, or the like). The metallization patterns  211 B of the interconnect structure  211  are electrically coupled to the devices  205  by the conductive plugs  209 . 
     The substrate  200  further includes pads  213 , such as aluminum pads, to which external connections are made. The pads  213  are on the active side of the semiconductor substrate  203 , such as in and/or on the interconnect structure  211 . An insulating layer  215  is on the interconnect structure  211 , such that the pads  213  are embedded in the insulating layer  215 . The insulating layer  215  may also be referred to as a passivation layer. In some embodiments, the insulating layer  215  may comprise one or more layers of silicon oxide, silicon nitride, silicon oxynitride, the like, or combinations thereof, and may be formed using ALD, CVD, or the like. In some embodiments, the pads  213  and the insulating layer  215  may be formed by forming and patterning a conductive material over the interconnect structure  211  to form the pads  213 , forming the insulating layer  215  over the interconnect structure  211  and the pads  213 , and patterning the insulating layer  215  to form opening in the insulating layer  215  exposing the pads  213 . 
     In some embodiments, under-bump metallizations (UBMs)  217  are formed over the pads  213 . The UBMs  217  extend through the openings in the insulating layer  215  and are physically and electrically coupled to respective pads  213 . The UBMs  217  may be formed of one or more layers of suitable conductive materials. In some embodiments, the UBMs  217  include three layers of conductive materials, such as a layer of titanium, a layer of copper, and a layer of nickel. Other arrangements of materials and layers, such as an arrangement of chrome/chrome-copper alloy/copper/gold, an arrangement of titanium/titanium tungsten/copper, or an arrangement of copper/nickel/gold, may be utilized for the formation of the UBMs  217 . Any suitable materials or layers of material that may be used for the UBMs  217  are fully intended to be included within the scope of the current application. 
     After forming the UBMs  217 , conductive connectors  219  are formed on the UBMs  217 . The conductive connectors  219  may be ball grid array (BGA) connectors, solder balls, metal pillars, controlled collapse chip connection (C4) bumps, micro bumps, electroless nickel-electroless palladium-immersion gold technique (ENEPIG) formed bumps, or the like. The conductive connectors  219  may include a conductive material such as solder, copper, aluminum, gold, nickel, silver, palladium, tin, the like, or a combination thereof. In some embodiments, the conductive connectors  219  are formed by initially forming a layer of solder through evaporation, electroplating, printing, solder transfer, ball placement, or the like. Once a layer of solder has been formed on the structure, a reflow may be performed in order to shape the material into the desired bump shapes. In another embodiment, the conductive connectors  219  comprise metal pillars (such as a copper pillar) formed by a sputtering, printing, electro plating, electroless plating, CVD, or the like. The metal pillars may be solder free and have substantially vertical sidewalls. In some embodiments, a metal cap layer is formed on the top of the metal pillars. The metal cap layer may include nickel, tin, tin-lead, gold, silver, palladium, indium, nickel-palladium-gold, nickel-gold, the like, or a combination thereof and may be formed by a plating process. 
     Referring further to  FIG.  2   , the deposition system  100  (see  FIGS.  1 A and  1 B ) may be used to deposit various layers over the semiconductor substrate  203  during the formation of the substrate  200 . For example, insulating layers (such as, for example, the ILD  207 , IMDs  211 A, or the insulating layer  215 ), mask layers (such as, for example, mask layers used while forming the devices  205  or the metallization patterns  211 B), dummy gate layers (such as, for example, dummy gate layers used while forming the devices  205 ), or the like may be deposited using the deposition system  100 . 
       FIG.  3    is a flow diagram illustrating a deposition method  300  in accordance with some embodiments. In some embodiments, the deposition method  300  is performed by the deposition system  100  (see  FIGS.  1 A and  1 B ). In the illustrated embodiment, the deposition method  300  is a plasma and laser assisted deposition (PLAD) process. The deposition method  300  may be integrated into an ALD process, or a CVD process. 
     Referring to  FIGS.  1 A,  1 B, and  3   , in some embodiments, the deposition method  300  starts with step  301 , when the substrate  200  is loaded into the chamber  101  of the deposition system  100 . The substrate  200  is placed on the mounting platform  107 . 
     In step  303 , a precursor material is introduced into the chamber  101  using the inlet  103 . In some embodiments, the showerhead  105  is utilized to disperse the precursor material into the chamber  101 . In some embodiments, a flow rate of the precursor material is between about 5 sccm and about 5 slm. In some embodiments when the deposited layer  201  comprises amorphous silicon (a-Si), the precursor material comprises a gas such as SiH 4 , Si 2 H 6 , SiCl 2 H 2 , SiCl 4 , Si 2 Cl 6 , or the like. In some embodiments when the deposited layer  201  comprises amorphous carbon (a-C), the precursor material comprises a gas mixture including CH 4  and Ar, a gas mixture including CH 4  and H 2 , a gas mixture including C 2 H 4  and Ar, a gas mixture including C 2 H 4  and H 2 , a gas mixture including C 2 H 2  and Ar, a gas mixture including C 2 H 2  and H 2 , or the like. 
     In step  305 , gas curtains  133  are generated in front of one or more EM radiation sources  119 . In some embodiments, an inert gas  131  (such as He gas, Ne gas, Ar gas, a combination thereof, or the like) is introduced into the chamber  101  through inlets  125  to generate the gas curtains  133 . The gas curtains  133  protect respective windows  123  from the deposition process performed by the deposition system  100 . Accordingly, lifetime of the windows  123  is increased and reduction of the intensity of the EM radiation  121  from the EM radiation sources  119  is avoided. In some embodiments, a flow rate of the gas  131  is between about 5 sccm and about 20 slm. 
     In step  307 , a plasma  135  is generated in the chamber  101  of the deposition system  100  from the precursor material. In some embodiments, the power source  115  is used to energize the second electrode  113  and ignites the plasma  135  in a gap between the showerhead  105  and the mounting platform  107 . In some embodiments, the precursor material is decomposed into various components, such as charged components (electrons, positive ions and/or negative ions) and neutral components (neutral radicals and/or un-decomposed neutral molecules/atoms). In some embodiments, the plasma ignition process may not precisely control the precursor material decomposition process, which may affect a quality of the deposited layer. The power source  115  may provide a power between about 10 W to about 3000 W. The power source  115  may be operated at a frequency between about 100 kHz to about 400 kHz, 13.56 MHz, 27.12 MHz, 60 MHz, 80 MHz or 2.45 GHz. 
     In step  309 , the plasma  135  is subjected to the EM radiation  121  from the EM radiation sources  119 . In some embodiments, the EM radiation  121  further decomposes the precursor material into various components. The EM radiation  121  allows a precise control of a precursor decomposition reaction by precisely controlling a wavelength (or, equivalently, energy) of the EM radiation  121 . Accordingly, the EM radiation sources  119  may be chosen based on the desired precursor decomposition reaction. In some embodiments when the deposited layer  201  is an a-Si layer, the precursor material SiH 4  may be decomposed into different components based on the wavelength (or, equivalently, the energy) of the EM radiation  121 . In some embodiments when 306.13 nm wavelength (or, equivalently, 4.5 eV energy) EM radiation sources  119  are used to generate the EM radiation  121 , the precursor material SiH 4  is decomposed according to the following decomposition reaction 
       SiH 4 →SiH 3   + +H +   +e   − .
 
     In some embodiments when 130.92 nm wavelength (or, equivalently, 9.47 eV energy) EM radiation sources  119  is used to generate the EM radiation  121 , the precursor material SiH 4  is decomposed according to the following decomposition reaction 
       SiH 4 →SiH 2   + +2H + +2 e   − .
 
     In some embodiments when 117.74 nm wavelength (or, equivalently, 10.53 eV energy) EM radiation sources  119  is used to generate the EM radiation  121 , the precursor material SiH 4  is decomposed according to the following decomposition reaction 
       SiH 4 →Si + +4H + +4 e   − .
 
     In some embodiments, by precisely controlling the precursor decomposition reaction, composition of the deposited layer  201  may be precisely controlled. In some embodiments when the deposited layer  201  is an a-Si layer, hydrogen (H) content in the a-Si layer may be precisely controlled. In some embodiments, a substantially pure a-Si layer may be deposited by using the 117.74 nm wavelength (or, equivalently, 10.53 eV energy) EM radiation sources  119 . In some embodiments, a-Si layer having a silicon to hydrogen ratio (Si:H) of about 1:2 may be deposited by using the 130.92 nm wavelength (or, equivalently, 9.47 eV energy) EM radiation sources  119 . 
     In some embodiments when the deposited layer  201  is an a-C layer, hydrogen (H) content in the a-C layer may be precisely controlled. In some embodiments, the hydrogen (H) content may be controlled from about 0 at % to about 80 at %. In some embodiments when the deposited layer  201  is an a-C layer, bonding type and ratio may be precisely controlled within the a-C layer. In some embodiments when the EM radiation sources  119  are not used and the plasma  135  provides the deposition energy, the a-C layer comprises more sp2 bonds than sp3 bonds. By using the EM radiation sources  119 , the content of the sp3 bonds may be increased up to 100%, when the structure of the a-C layer is similar to diamond. 
     In step  311 , a layer (such as the deposited layer  201 ) is deposited over the substrate  200 . In some embodiments, decomposed precursor components react with each other to form the deposited layer  201  over the substrate  200 . In some embodiments, the deposition method  300  is performed at a temperature between about 50° C. and 400° C. In some embodiments, the heating mechanisms  109  of the mounting platform  107  are used to heat the substrate  200  to a desired temperature. 
       FIG.  4    is a flow diagram illustrating a deposition method  400  in accordance with some embodiments. In some embodiments, the deposition method  400  is performed by the deposition system  100  (see  FIGS.  1 A and  1 B ). In some embodiments, the deposition method  400  is similar to the deposition method  300  (see  FIG.  3   ), with the distinction that the plasma generation process described above in step  307  is omitted. In the illustrated embodiment, the deposition energy is provided by thermal energy and the EM radiation energy. The deposition method  400  may be integrated into an ALD process, or a CVD process. 
     Referring to  FIGS.  1 A,  1 B, and  4   , in some embodiments, the deposition method  400  starts with step  401 , when the substrate  200  is loaded into the chamber  101  of the deposition system  100 . The substrate  200  is placed on the mounting platform  107 . 
     In step  403 , a precursor material is introduced into the chamber  101  using the inlet  103 . In some embodiments, the showerhead  105  is utilized to disperse the precursor material into the chamber  101 . In some embodiments, step  403  is similar to step  303  described above with reference to  FIG.  3   , and the description is not repeated herein. 
     In step  405 , gas curtains  133  are generated in front of one or more EM radiation sources  119 . In some embodiments, step  405  is similar to step  305  described above with reference to  FIG.  3   , and the description is not repeated herein. In some embodiments, the gas curtains  133  are used to protect the windows  123 , such that the material deposited over the substrate  200  is not also deposited on the windows  123 . Accordingly, lifetime of the windows  123  is increased and reduction of the intensity of the EM radiation  121  is avoided. 
     In step  407 , the precursor material is subjected to the EM radiation  121  from the one or more EM radiation sources  119 . In some embodiments, step  407  is similar to step  309  described above with reference to  FIG.  3   , and the description is not repeated herein. 
     In step  409 , a layer (such as the deposited layer  201 ) is deposited over the substrate  200 . In some embodiments, step  409  is similar to step  311  described above with reference to  FIG.  3   , and the description is not repeated herein. 
       FIG.  5    illustrate a cross-sectional view of a deposition system  500  in accordance with some embodiments. The deposition system  500  is similar to the deposition system  100  (see  FIG.  1 A ), with like features being labeled by like numerical references, and descriptions of the like features are not repeated herein. In distinction with the deposition system  100 , the deposition system  500  comprises a single EM radiation source  119 . In some embodiments, the deposition methods  300  (see  FIG.  3   ) and  400  (see  FIG.  4   ) may be performed using the deposition system  500 . 
       FIGS.  6 A- 6 C  illustrate a deposition system  600  in accordance with some embodiments.  FIG.  6 A  illustrates a three-dimensional view.  FIG.  6 B  illustrates a cross-sectional view along a section AA′ in  FIG.  6 A .  FIG.  6 C  illustrates detailed view of a region  607  of the deposition system  600  shown in  FIG.  6 A . The deposition system  600  is similar to the deposition system  100  (see  FIG.  1 A ), with like features being labeled by like numerical references, and descriptions of the like features are not repeated herein. In the illustrated embodiment, the mounting platform  107  has a greater diameter than the showerhead  105 . In distinction with the deposition system  100 , the deposition system  600  comprises EM radiation sources  601  instead of the EM radiation sources  119 . 
     In some embodiments, the EM radiation sources  601  may be UV or laser systems, such as an F 2  system (operating at 157 nm wavelength), an ArF system (operating at 193 nm wavelength), a Nd:YAG system (operating at 213 nm, 266 nm, 355 nm, or 532 nm wavelengths), a He—Ag system (operating at 224.3 nm wavelength), a KCl system (operating at 222 nm wavelength), a KrF system (operating at 248 nm wavelength), a XeCl system (operating at 308 nm wavelength), a He—Cd system (operating at 325 nm wavelength), an N 2  system (operating at 337.1 nm wavelength), a XeF system (operating at 351 nm wavelength), a He—Cd system (operating at 441.6 nm wavelength), or the like. 
     In some embodiments, the EM radiation sources  601  are placed such that a EM radiation  609  (indicated by arrows in  FIG.  6 B ) generated by each of the EM radiation sources  601  propagates toward a respective portion of an edge of the mounting platform  107  (or, equivalently, a respective portion of an edge of the substrate  200  when the substrate  200  is placed on the mounting platform  107 ). In some embodiments, the EM radiation sources  601  are placed along the edge of the mounting platform  107  (or, equivalently, the edge of the substrate  200  when the substrate  200  is placed on the mounting platform  107 ) in a plan view and have a uniform spacing S 1 . The spacing S 1  may be between about 200 mm and about 50 mm. In some embodiments, the deposition system  600  comprises an even number of the EM radiation sources  601 . In some embodiments when the mounting platform  107  has a circular shape in a plan view, the EM radiation sources  601  are grouped into pairs, such that EM radiation sources  601  in each of the pairs are placed over the mounting platform  107  (or, equivalently, over the substrate  200  when the substrate  200  is placed on the mounting platform  107 ) in diametrically opposite points in the plan view. In the illustrated embodiment, the deposition system  600  comprises eight EM radiation sources  601 . In some embodiments, the eight EM radiation sources  601  may be placed in one and a half o&#39;clock position, three o&#39;clock position, four and a half o&#39;clock position, six o&#39;clock position, seven and a half o&#39;clock position, nine o&#39;clock position, ten and a half o&#39;clock position, and twelve o&#39;clock position, respectively. In some embodiments, the EM radiation  609  generated by each of the EM radiation sources  601  illuminates a respective portion of the edge of the substrate  200 . In some embodiments, each of the EM radiation sources  601  is directly over a respective portion of the edge of the substrate  200 . In some embodiments, each of the EM radiation sources  601  overlaps with the edge of the mounting platform  107  (or, equivalently, the edge of the substrate  200 ) in a plan view. In some embodiments, by placing plurality of EM radiation sources  601  having uniform spacing over the mounting platform  107 , the edge of the substrate  200  is uniformly illuminated by the EM radiation sources  601 . 
     In some embodiments, the EM radiation  609  from each of the EM radiation sources  601  enters the chamber  101  through respective windows  603  in the chamber  101 . The material for the windows  603  are chosen to provide good vacuum isolation to the chamber  101  as well as be transparent to the EM radiation  609 . In some embodiments, the windows  603  are made of quartz, glass, a combination thereof, or the like. As described below in greater detail, the EM radiation  609  from each of the EM radiation sources  601  is used to remove cluster defects  615  formed in the deposited layer  201  at the edge of the substrate  200 . In some embodiments, the EM radiation  609  of each of the EM radiation sources  601  is aligned with a respective portion of the edge of the substrate  200  and burns the cluster defects  615 . 
     In some embodiments, the chamber  101  comprises inlets  605  near respective windows  603 . Each of the inlets  605  is configured to accept a desired gas  611  (indicated by dashed arrows in  FIG.  6 C ) and forms a gas curtain  613  in front of the respective window  603 . The gas  611  may comprise an inert gas such as He gas, Ne gas, Ar gas, a combination thereof, or the like. In some embodiments, the gas curtains  613  are used to protect the windows  603 , such that the material deposited over the substrate  200  is not also deposited on the windows  603 . Accordingly, lifetime of the windows  603  is increased and reduction of the intensity of the EM radiation  609  is avoided. 
       FIG.  7    is a flow diagram illustrating a deposition method  700  in accordance with some embodiments. In some embodiments, the deposition method  700  is performed by the deposition system  600  (see  FIGS.  6 A- 6 C ). The deposition method  700  may be integrated into an ALD process, or a CVD process. 
     Referring to  FIGS.  6 A- 6 C and  7   , in some embodiments, the deposition method  700  starts with step  701 , when the substrate  200  is loaded into the chamber  101  of the deposition system  600 . The substrate  200  is placed on the mounting platform  107 . 
     In step  703 , a precursor material is introduced into the chamber  101  using the inlet  103 . In some embodiments, the showerhead  105  is to disperse the precursor material into the chamber  101 . In some embodiments, step  703  is similar to step  303  described above with reference to  FIG.  3   , and the description is not repeated herein. 
     In step  705 , gas curtains  613  are generated in front of the EM radiation sources  601 . In some embodiments, an inert gas  611  (such as He gas, Ne gas, Ar gas, a combination thereof, or the like) is introduced into the chamber  101  through the inlets  605  to generate the gas curtains  613 . The gas curtains  613  protect respective windows  603  from the deposition process performed by the deposition system  600 . Accordingly, lifetime of the windows  603  is increased and reduction of the intensity of the EM radiation  609  from the EM radiation sources  601  is avoided. In some embodiments, a flow rate of the gas  611  is between about 5 sccm and about 20 slm. 
     In step  707 , a plasma  135  is generated in the chamber  101  of the deposition system  600  from the precursor material. In some embodiments, step  707  is similar to step  307  described above with reference to  FIG.  3   , and the description is not repeated herein. In some embodiments, the plasma  135  comprises decomposed precursor components. 
     In step  709 , a layer (such as the deposited layer  201 ) is deposited over the substrate  200 . In some embodiments, decomposed precursor components react with each other to form the deposited layer  201  over the substrate  200 . In some embodiments, the deposition method  700  is performed at a temperature between about 50° C. and 400° C. In some embodiments, the heating mechanisms  109  of the mounting platform  107  are used to heat the substrate  200  to a desired temperature. 
     In step  711 , the EM radiation  609  from the EM radiation sources  601  is used to burn cluster defects  615  formed in the deposited layer  201  at the edge of the substrate  200 . In some embodiments when the deposited layer  201  is an a-Si layer, the cluster defects  615  may comprise hydrogen-doped a-Si (a-Si:H). In some embodiments, the EM radiation sources  601  may be high energy sources having energies greater than about 10 eV. In some embodiments, the EM radiation  609  of each of the EM radiation sources  601  illuminates a respective portion of the edge of the substrate  200  and burns the cluster defects  615 . In some embodiments, each of the EM radiation sources  601  is directly over a respective portion of the edge of the substrate  200 . In some embodiments, each of the EM radiation sources  601  overlaps with the edge of the mounting platform  107  (or, equivalently, the edge of the substrate  200 ) in a plan view. 
       FIG.  8    is a flow diagram illustrating a deposition method  800  in accordance with some embodiments. In some embodiments, the deposition method  800  is performed by the deposition system  600  (see  FIGS.  6 A- 6 C ). In some embodiments, the deposition method  800  is similar to the deposition method  700  (see  FIG.  7   ), with the distinction that the plasma generation process described in step  707  is omitted. The deposition method  800  may be integrated into an ALD process, or a CVD process. 
     Referring to  FIGS.  6 A- 6 C and  8   , in some embodiments, the deposition method  800  starts with step  801 , when the substrate  200  is loaded into the chamber  101  of the deposition system  100 . The substrate  200  is placed on the mounting platform  107 . 
     In step  803 , a precursor material is introduced into the chamber  101  using the inlet  103 . In some embodiments, the showerhead  105  is utilized to disperse the precursor material into the chamber  101 . In some embodiments, step  803  is similar to step  303  described above with reference to  FIG.  3   , and the description is not repeated herein. 
     In step  805 , gas curtains  613  are generated in front of the EM radiation sources  601 . In some embodiments, step  805  is similar to step  705  described above with reference to  FIG.  7   , and the description is not repeated herein. 
     In step  807 , a layer (such as the deposited layer  201 ) is deposited over the substrate  200 . In some embodiments, the precursor material forms the deposited layer  201  over the substrate  200 . In some embodiments, the deposition method  800  is performed at a temperature between about 50° C. and 400° C. In some embodiments, the heating mechanisms  109  of the mounting platform  107  are used to heat the substrate  200  to a desired temperature. 
     In step  809 , the EM radiation  609  from the EM radiation sources  601  is used to burn cluster defects  615  formed in the deposited layer  201  at the edge of the substrate  200 . In some embodiments, step  809  is similar to step  711  described above with reference to  FIG.  7   , and the description is not repeated herein. 
       FIG.  9    illustrates a cross-sectional view of a deposition system  900  in accordance with some embodiments. The deposition system  900  is similar to the deposition system  100  (see  FIG.  1 A ), with like features being labeled by like numerical references, and descriptions of the like features are not repeated herein. The deposition system  900 , in addition to the EM radiation sources  119 , comprises EM radiation sources  601  as described above with  FIGS.  6 A- 6 C , and the description is not repeated herein. 
       FIG.  10    is a flow diagram illustrating a deposition method  1000  in accordance with some embodiments. In some embodiments, the deposition method  1000  is performed by the deposition system  900  (see  FIG.  9   ). The deposition method  1000  may be integrated into an ALD process, or a CVD process. 
     Referring to  FIGS.  9  and  10   , in some embodiments, the deposition method  1000  starts with step  1001 , when the substrate  200  is loaded into the chamber  101  of the deposition system  900 . The substrate  200  is placed on the mounting platform  107 . 
     In step  1003 , a precursor material is introduced into the chamber  101  using the inlet  103 . In some embodiments, the showerhead  105  is utilized to disperse the precursor material into the chamber  101 . In some embodiments, step  1003  is similar to step  303  described above with reference to  FIG.  3   , and the description is not repeated herein. 
     In step  1005 , gas curtains  133  (see  FIG.  1 B ) are generated in front of the EM radiation sources  119 , and gas curtains  613  (see  FIG.  6 C ) are generated in front of the EM radiation sources  601 . In some embodiments, an inert gas  131  (such as He gas, Ne gas, Ar gas, a combination thereof, or the like) is introduced into the chamber  101  through the inlets  125  to generate the gas curtains  133  (see  FIG.  1 B ). The gas curtains  133  protect respective windows  123  from the deposition process performed by the deposition system  900 . Accordingly, lifetime of the windows  123  is increased and reduction of the intensity of the EM radiation  121  from the EM radiation sources  119  is avoided. In some embodiments, a flow rate of the gas  131  is between about 5 sccm and about 20 slm. 
     In some embodiments, an inert gas  611  (such as He gas, Ne gas, Ar gas, a combination thereof, or the like) is introduced into the chamber  101  through the inlets  605  to generate the gas curtains  613  (see  FIG.  6 C ). The gas curtains  613  protect respective windows  603  from the deposition process performed by the deposition system  900 . Accordingly, lifetime of the windows  603  is increased and reduction of the intensity of the EM radiation  609  from the EM radiation sources  601  is avoided. In some embodiments, a flow rate of the gas  611  is between about 5 sccm and about 20 slm. 
     In step  1007 , a plasma  135  is generated in the chamber  101  of the deposition system  900  from the precursor material. In some embodiments, step  1007  is similar to step  307  described above with reference to  FIG.  3   , and the description is not repeated herein. 
     In step  1009 , the plasma  135  is subjected to the EM radiation  121  from the EM radiation sources  119 . In some embodiments, the EM radiation  121  further decomposes the precursor material into various components. In some embodiments, step  1009  is similar to step  309  described above with reference to  FIG.  3   , and the description is not repeated herein. 
     In step  1011 , a layer (such as the deposited layer  201 ) is deposited over the substrate  200 . In some embodiments, decomposed precursor components react with each other to form the deposited layer  201  over the substrate  200 . In some embodiments, the deposition method  1000  is performed at a temperature between about 50° C. and 400° C. In some embodiments, the heating mechanisms  109  of the mounting platform  107  are used to heat the substrate  200  to a desired temperature. 
     In step  1013 , the EM radiation  609  from the EM radiation sources  601  is used to burn cluster defects  615  form in the deposited layer  201  at the edge of the substrate  200 . In some embodiments, step  1013  is similar to step  711  described above with reference to  FIG.  7   , and the description is not repeated herein. 
       FIG.  11    is a flow diagram illustrating a deposition method  1100  in accordance with some embodiments. In some embodiments, the deposition method  1100  is performed by the deposition system  900  (see  FIG.  9   ). In some embodiments, the deposition method  1100  is similar to the deposition method  1000  (see  FIG.  10   ), with the distinction that the plasma generation process described in step  1007  is omitted. The deposition method  1100  may be integrated into an ALD process, or a CVD process. 
     Referring to  FIGS.  9  and  11   , in some embodiments, the deposition method  1100  starts with step  1001 , when the substrate  200  is loaded into the chamber  101  of the deposition system  900 . The substrate  200  is placed on the mounting platform  107 . 
     In step  1103 , a precursor material is introduced into the chamber  101  using the inlet  103 . In some embodiments, the showerhead  105  is utilized to disperse the precursor material into the chamber  101 . In some embodiments, step  1103  is similar to step  303  described above with reference to  FIG.  3   , and the description is not repeated herein. 
     In step  1105 , gas curtains  133  (see  FIG.  1 B ) are generated in front of the EM radiation sources  119 , and gas curtains  613  (see  FIG.  6 C ) are generated in front of EM radiation sources  601 . In some embodiments, step  1105  is similar to step  1005  described above with reference to  FIG.  10   , and the description is not repeated herein. 
     In step  1107 , the precursor material is subjected to the EM radiation  121  from the EM radiation sources  119 . In some embodiments, the EM radiation  121  decomposes the precursor material into various components. In some embodiments, step  1107  is similar to step  309  described above with reference to  FIG.  3   , and the description is not repeated herein. 
     In step  1109 , a layer (such as the deposited layer  201 ) is deposited over the substrate  200 . In some embodiments, decomposed precursor components react with each other to form the deposited layer  201  over the substrate  200 . In some embodiments, the deposition method  1100  is performed at a temperature between about 50° C. and 400° C. In some embodiments, the heating mechanisms  109  of the mounting platform  107  are used to heat the substrate  200  to a desired temperature. 
     In step  1111 , the EM radiation  609  from the EM radiation sources  601  is used to burn cluster defects  615  form in the deposited layer  201  at the edge of the substrate  200 . In some embodiments, step  1111  is similar to step  711  described above with reference to  FIG.  7   , and the description is not repeated herein. 
       FIG.  12    illustrate a cross-sectional view of a deposition system  1200  in accordance with some embodiments. The deposition system  1200  is similar to the deposition system  900  (see  FIG.  9   ), with like features being labeled by like numerical references, and descriptions of the like features are not repeated herein. In distinction with the deposition system  900 , the deposition system  1200  comprises a single EM radiation source  119 . In some embodiments, the deposition methods  1000  and  1100  may be performed using the deposition system  1200 . 
     Embodiments may achieve advantages. Various embodiments discussed herein allow for depositing void-free and seam free layers with reduced impurity and defect levels, and providing additional parameters (such as, for example, EM radiation intensity and/or wavelength) for tuning the deposition process (for example, tuning a composition of the deposited layer). 
     In accordance with an embodiment, a method includes placing a substrate over a platform in a chamber of a deposition system. A precursor material is introduced into the chamber. A first gas curtain is generated in front of a first electromagnetic (EM) radiation source coupled to the chamber. A plasma is generated from the precursor material in the chamber, wherein the plasma comprises dissociated components of the precursor material. The plasma is subjected to a first EM radiation from the first EM radiation source. The first EM radiation further dissociates the precursor material. A layer is deposited over the substrate. The layer includes a reaction product of the dissociated components of the precursor material. In an embodiment, generating the first gas curtain in front of the first EM radiation source includes flowing an inert gas into the chamber in front of the first EM radiation source. In an embodiment, the first EM radiation source is an ultraviolet (UV) source or a laser source. In an embodiment, the method further includes generating a second gas curtain in front of a second EM radiation source coupled to the chamber. In an embodiment, the method further includes burning, using a second EM radiation from the second EM radiation source, cluster defects in the layer at an edge of the substrate, where the second EM radiation source is directly over the edge of the substrate. In an embodiment, the method further includes adjusting a temperature of the substrate to a desired temperature. In an embodiment, the first EM radiation enters into the chamber through a window, the window including a material transparent to the first EM radiation. In an embodiment, the precursor material includes SiH 4 , Si 2 H 6 , SiCl 2 H 2 , SiCl 4 , or Si 2 Cl 6 , and the layer includes amorphous silicon (a-Si). 
     In accordance with another embodiment, a method includes placing a substrate over a platform in a chamber of a deposition system. A precursor material is flown into the chamber. A first gas curtain is generated in front of a first electromagnetic (EM) radiation source coupled to the chamber. A plasma is generated from the precursor material in the chamber. The plasma includes dissociated components of the precursor material. A layer is deposited over the substrate. The layer includes a reaction product of the dissociated components of the precursor material. The layer includes cluster defects at an edge of the substrate. Using a first EM radiation from the first EM radiation source, the cluster defects are removed from the layer. In an embodiment, generating the first gas curtain in front of the first EM radiation source includes flowing an inert gas into the chamber in front of the first EM radiation source. In an embodiment, the first EM radiation source is an ultraviolet (UV) source or a laser source. In an embodiment, the method further includes generating a second gas curtain in front of a second EM radiation source coupled to the chamber. In an embodiment, the method further includes, before depositing the layer over the substrate, subjecting the plasma to a second EM radiation from the second EM radiation source, where the second EM radiation further dissociates the precursor material. In an embodiment, the first EM radiation burns the cluster defects. In an embodiment, first EM radiation source overlaps with an edge of the platform in a plan view. 
     In accordance with yet another embodiment, a system includes a chamber, a side of the chamber having a first window; a platform in the chamber, the platform including a first electrode; a showerhead over the platform in the chamber, the showerhead including a second electrode; a plasma power source coupled to the second electrode; and a first electromagnetic (EM) radiation source attached to the side of the chamber. A first EM radiation generated by the first EM source enters into the chamber through the first window and propagates between the platform and the showerhead. In an embodiment, the system further includes second EM radiation sources attached to a top of the chamber, second EM radiations generated by the second EM sources entering into the chamber through second windows in the top of the chamber. In an embodiment, the second EM radiation sources are placed along an edge of the platform in a plan view. In an embodiment, the second EM radiation sources have a uniform spacing. In an embodiment, the first EM radiation source is an ultraviolet (UV) source or a laser source. 
     The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.