Abstract:
A deposition apparatus is disclosed for depositing a layer on a substrate such as a semiconductor wafer. The deposition apparatus may include a process chamber, and a susceptor in the process chamber with the susceptor being configured to receive a substrate for depositing a thin layer thereon. The deposition apparatus may also include a showerhead on a side of the process chamber with the showerhead being configured to receive reaction gases and to introduce the reaction gases into the process chamber. The showerhead may include a heating element therein for heating reaction gases prior to introducing the reaction gases into the reaction chamber. Related methods are also discussed.

Description:
RELATED APPLICATIONS  
         [0001]    This application claims the benefit of priority from Korean Patent Application No. 2002-41952 field Jul. 18, 2002, the disclosure of which is hereby incorporated herein in its entirety by reference.  
         FIELD OF THE INVENTION  
         [0002]    The present invention relates to the manufacture of semiconductor devices and more particularly to depositing layers on substrates.  
         BACKGROUND OF THE INVENTION  
         [0003]    In general, when manufacturing semiconductor devices, a layer to be used as a dielectric or conductive material of the device can be formed on the surface of a substrate, such as a semiconductor wafer, by diffusing a gaseous chemical (vapor) onto the wafer, thereby facilitating a chemical reaction in which the layer is formed. Chemical vapor deposition processes available for forming such a dielectric or conductive layer can be classified as chemical vapor deposition (CVD) or atomic layer deposition (ALD). Chemical vapor deposition processes can be further classified as atmosphere pressure chemical vapor deposition (APCVD), low pressure chemical vapor deposition (LPCVD) or plasma enhanced chemical vapor deposition (PECVD).  
           [0004]    Because low pressure chemical vapor deposition generally proceeds in a process chamber at relatively high temperatures, a layer formed on the wafer may have high thermal stress and cracks thereon may easily occur.  
           [0005]    Though plasma enhanced chemical vapor deposition may proceed in a process chamber at relatively low temperatures, a plasma generator may be provided relatively distant from the process chamber, so that a layout of the apparatus may be complicated. In addition, because radicals generated in a plasma generator may be carried through a long pipe and supplied to the process chamber, radicals may recombine during transfer. Similar problems may also occur in atomic layer deposition.  
         SUMMARY OF THE INVENTION  
         [0006]    According to embodiments of the present invention, a deposition system may be provided for depositing a thin layer on a substrate such as a semiconductor wafer. This deposition system may include a process chamber, and a susceptor in the process chamber with the susceptor being configured to receive a substrate for depositing a thin layer thereon. The deposition system may also include a showerhead on a side of the process chamber with the showerhead being configured to receive reaction gases and to introduce the reaction gases into the process chamber. The showerhead may also include a heating element therein for heating reaction gases prior to introducing the reaction gases into the reaction chamber. The showerhead can also be configured to spray the reaction gases into the process chamber in parallel with a substrate received on the susceptor.  
           [0007]    In addition, the showerhead may include a housing, at least one inlet port through which the reaction gases are received into the showerhead, and a spray plate adjacent the process chamber through which reaction gases are introduced into the process chamber. Moreover, the heating element may include a heating wire in the housing between the inlet port and the spray plate. More particularly, the heating wire comprises a catalytic material such as tungsten, and the heating wire may be a coiled wire. The housing can also include first and second terminals therein with the first and second ends of the heating wire being respectively connected to the first and second terminals, and each of the first and second terminals may include an elastic connecting portion to which the heating wire is connected. The housing can also include insulators that electrically insulate the terminals from conductive portions of the housing.  
           [0008]    In addition, the showerhead can include a cooling portion configured to cool an outer portion of the housing, and the cooling portion may include a duct on an outer portion of the housing with the duct being configured to provide circulation of a cooling fluid therethrough. The showerhead can include a plurality of plenums therein such that each plenum receives at least one respective reaction gas and such that reaction gases from the plenums are introduced into the process chamber without prior mixing of the reaction gases between plenums within the showerhead. A first of the plenums may include a heating element therein configured to heat gases passing through the first plenum, and a second of the plenums can be free of a heating element. The first plenum with the heating element may also include an extended portion such that the first plenum extends further from the process chamber than the second plenum with the heating element being located in the extended portion of the first plenum. A duct may also be included on the extended portion of the first plenum wherein the duct is configured to provide circulation of a cooling fluid therethrough.  
           [0009]    The susceptor can be configured to receive a substrate for depositing a thin layer thereon through atomic layer deposition and/or chemical vapor deposition. A boat can also be included in the process chamber with the boat supporting the first susceptor and at least a second susceptor with each susceptor being configured to receive at least one substrate for deposition of a thin layer thereon.  
           [0010]    According to additional embodiments of the present invention, a method of depositing a thin layer on a substrate may include receiving a reaction gas in a showerhead adjacent a process chamber, and heating the reaction gas in the showerhead. After heating the reaction gas in the showerhead, the heated reaction gas may be introduced into the process chamber for deposition of the thin layer on the substrate in the process chamber. Moreover, the heated reaction gas can be introduced into the process chamber parallel to the substrate. Heating the reaction gas may include heating the reaction gas with a heating wire, and the heating wire may comprise a catalytic material such as tungsten.  
           [0011]    More particularly, receiving a reaction gas in a showerhead may include receiving a first reaction gas in a first plenum of the showerhead, heating the reaction gas may include heating the first reaction gas in the first plenum, and introducing the heated reaction gas may include introducing the first heated reaction gas into the process chamber. In addition, a second reaction gas may be received in a second plenum of the showerhead, and the second reaction gas may be introduced into the process chamber for deposition of the thin layer on the substrate without heating the second reaction gas prior to introduction into the process chamber. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a side view illustrating a deposition system according to embodiments of the present invention.  
         [0013]    [0013]FIG. 2 is a top view of the deposition system of FIG. 1.  
         [0014]    [0014]FIG. 3 is a sectional view of the deposition system of FIG. 1.  
         [0015]    [0015]FIG. 4 is a perspective view illustrating a showerhead according to embodiments of the present invention.  
         [0016]    [0016]FIG. 5 is a sectional view taken along line I-I of FIG. 4.  
         [0017]    [0017]FIG. 6 is a perspective view illustrating a shower head according to additional embodiments of the present invention.  
         [0018]    [0018]FIG. 7 is a sectional view taken along line II-II of FIG. 6.  
         [0019]    [0019]FIG. 8 is a perspective view illustrating a showerhead according to yet additional embodiments of the present invention.  
         [0020]    [0020]FIG. 9 and FIG. 10 are sectional views taken along line III-III and line IV-IV of FIG. 8.  
         [0021]    [0021]FIG. 11 is a perspective view illustrating a showerhead according to still additional embodiments of the present invention.  
         [0022]    [0022]FIG. 12 is a sectional view taken along line V-V of FIG. 11.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0023]    The present invention now will be described more fully with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concept of the invention to those skilled in the art. In the drawings, the sizes of elements are exaggerated for clarity. It will also be understood that when an element is referred to as being “coupled” or “connected” to another element, it can be directly coupled or connected to the other element, or intervening elements may also be present. When an element is referred to as being “directly coupled” or “directly connected” to another element, no intervening elements are present. It is also noted that like reference numerals may be used to designate identical or corresponding parts throughout the several views.  
         [0024]    [0024]FIGS. 1, 2, and  3  are respectively side, top, and sectional views illustrating a deposition system according to embodiments of the present invention. The system includes a process chamber  100 , a boat  170 , a showerhead  200 , and an exhaust  300 .  
         [0025]    The process chamber  100  has four wide main-sidewalls  142  and four narrow sub-sidewalls  144 . Radiant heat sources  130  are located on the exterior of the process chamber  100 . The process chamber  100  is kept at a moderate temperature by heat transferred from the radiant heat sources  130 , so that gases that are supplied to the process chamber  100  can be adsorbed on substrates (such as semiconductor wafers) therein. The quartz windows  110  can be installed on the inside of the main-sidewalls  142  and radiant heat energy can be transmitted from the exterior of the process chamber  100  to the interior of the process chamber  100  through the quartz windows  110 . Diffuser shield plates  150  can be located between the quartz windows  110  and the interior of the process chamber  100 . The diffuser shield plates  150  may diffuse heat energy emitted from the radiant heat sources  130 .  
         [0026]    The boat  170  is located at the interior of the process chamber  100 . The boat  170  may include a plurality of susceptors  172 , and substrates are placed on the susceptors  172 . The boat  170  may rotate during a process, so that layers may be more uniformly deposited on the substrates. The substrates can be placed on the boat  170  in a loader (not shown) located below the process chamber  100 .  
         [0027]    The showerhead  200  can be installed on one sub-sidewall  144  and can have sufficient length to uniformly spray gases to all substrates which are placed on the boat  170 . The exhaust  300  can be installed on a sub-sidewall  144  opposite of the showerhead  200 , and may be formed having a length the same as that of the showerhead  200 . The gases can be sprayed in the process chamber  100  in parallel with surfaces of the substrates through the showerhead  100  so that deposition layers can be formed uniformly on all substrates.  
         [0028]    [0028]FIG. 4 is a perspective view illustrating the showerhead  200  according to embodiments of the present invention, and FIG. 5 is a sectional view taken along line I-I of FIG. 4. Referring to FIGS. 4 and 5, the showerhead  200  may include a housing  210 , a heating element, and a cooling element (not shown). The housing  210  may include four side walls, the spray plate  220  and an inlet plate. The spray plate  220  can be installed on a rear side of the housing  210  adjacent to the process chamber  100 , and the inlet plate having an inlet port  230  can be installed on a front side of the housing  210 , that is, on a side opposite of the spray plate  220 . The inlet plate may be joined to the housing  210 , for example, by screws or welding. Optionally, the inlet plate and the housing  210  may be integrally formed.  
         [0029]    The spray plate  220  may be joined/separated to/from the housing  210  and an o-ring may be inserted between the spray plate  220  and the housing  210  for sealing. A plurality of spray holes  222  can be formed on the spray plate  220  and gases or radicals in the showerhead  200  can be supplied to the process chamber  100  through the spray holes  222 . Optionally slits may be formed on the spray plate  220  instead of or in addition to the spray holes  222 .  
         [0030]    The showerhead  200  may include the heating element to decompose the reactant gases that come in the housing  100  through the inlet port  230 . The term decompose means separation of a chemical combination into constituents. The heating element may include a heating wire  260  (or filament) and terminals  250 . The projections  240  may be formed on two opposing side walls that face each other and the terminals  250  may be inserted in the projection  240 . The heating wire  260  is located in the housing  100  and both ends of the heating wire  260  are connected with respective terminals  250 . Also, a plurality of heating wires  260  may be installed on the housing  100 .  
         [0031]    Referring to FIG. 5, the terminals  250  each have a connecting portion  252  at one end thereof, and ends of the wire  260  are connected with respective terminals  250 . The connecting portions  252  may have two elastic members with triangular shape. A space with a width smaller than the diameter of the wire  260  is formed between the two elastic members. The heating wire  260  is pushed toward the space between two elastic members to connect the heating wire  260  with terminals  250 . Insulator members  254  may be inserted between each of the terminals  250  and the housing  210 .  
         [0032]    The heating wire  260  can be formed as a coil to supply a relatively wide heat transfer area, thereby increasing an amount of heat that can be transferred to reactant gases. The heating wire  260  can be made of tungsten to catalyze the decomposition of the reactant gases. The showerhead  200  can include a cooling element such as a duct (not shown) surrounding the housing  210  through which cooling water can flow. The cooling may reduce heating of the housing  210  of the showerhead  200  due to heat emitted from the heating wire  260 .  
         [0033]    [0033]FIG. 6 is a perspective view illustrating another example of a showerhead  200  and FIG. 7 is a sectional view taken along line II-II of FIG. 6. Referring to FIGS. 6 and 7, the housing  210  may include three plenums  212  separated by partitions  216 . Each of the plenums  212  may have a respective inlet port  230  where the reactant gases are introduced, and the spray plate  220  may include a respective column of holes  222  for each plenum. The terminals  250  are inserted at the both ends of each plenum  212 , and a heating element  260  such as a tungsten wire can be connected with the terminals  250  in each plenum. A different kind of gas may flow in a each plenum  212  without mixture. The gases can be supplied to the process chamber  100  through the spray plate  220  after being decomposed in respective plenums  212 .  
         [0034]    According to embodiments of the present invention, because the reactant gases are decomposed in the showerhead  200 , the process can proceed in the chamber  100  at a lower temperature than may otherwise be used in a conventional vertical furnace. Thermal stress induced in the substrate may thus be reduced during deposition of the layer, and cracking of the deposited layer may be reduced.  
         [0035]    Because the reactant gases can be decomposed in the showerhead  200  and supplied to the process chamber  100  without delay, a recombination of radicals can be reduced.  
         [0036]    [0036]FIG. 8 is a perspective view illustrating the showerhead  200  according to additional embodiments of the present invention. FIGS. 9 and 10 are sectional views taken along line III-III and line IV-IV of FIG. 8. Referring to FIG. 8, the showerhead  200  can include a housing  210 , a heating element and a cooling element as discussed with respect to FIGS. 4 and 5. The housing  210  of FIGS.  8 - 10  includes a plurality of plenums  212  and  214  separated by partitions  216 , so that the reactant gases are supplied to the process chamber  100  without mixture.  
         [0037]    Referring to FIGS. 9 and 10, the length of the center plenum  212  may be the same as that of the side plenums  214 . An inlet plate having an inlet port  230  can be installed on each of the plenums  212  and  214 . The spraying plate  220  is located on a side of the plenums opposite the inlet plates. First reactant gases can be supplied to center plenum  212  and second reactant gases can be supplied to the side plenums  214 . The first gases can be gases that are supplied to the process chamber  100  after decomposition, and the second gases can be gases that are supplied to the process chamber  100  without decomposition.  
         [0038]    The terminals  250  are provided at opposite sides of the center plenum  212  and the heating wire  260  can be connected with the terminals  212 . For example, when forming an aluminum oxidation layer on a substrate using an atomic layer deposition system according to embodiments of the present invention, tri-metal aluminum (Al(CH 3 ) 3 , TMA) composed of aluminum and a metal ligand can be supplied to the process chamber  100  through one or both of the side plenums  214 . Then water vapor can be supplied to the process chamber  100  through the center plenum  212 . The water vapor can be decomposed in oxygen ligand and hydrogen ligand in the center plenum  212 . Before the water vapors are supplied to the chamber  100 , an inert gas (such as nitrogen gas) may be provided to the process chamber  100  through one or both of the side plenums  214  or a different spray pipe. A number of heated plenums  212  and unheated plenums  214  may be changed according to a number of the reactant gases to be used.  
         [0039]    [0039]FIG. 11 is a perspective view showing a showerhead  200  according to yet additional embodiments of the present invention, and FIG. 12 is a sectional view taken along line V-V of FIG. 11. In embodiments illustrated in FIGS. 11 and 12, the heat emitted by the heating wire  260  (such as a tungsten wire) located in the central plenum  212  is transferred to side walls of the second plenums  214 . Accordingly, reactant gases in the side plenums  214  may be decomposed by the heat. According to embodiments illustrated in FIGS. 11 and 12, the housing  210  has the central plenum  212  supplying first reactant gases to the process chamber  100  after decomposing them and the side plenums  214  may supply additional reactant gases to the process chamber  100  without decomposing them. The central plenum  212  with the heating wire  260  can be longer than the side plenums  214 . In other words, the central plenum  212  can have an extended portion projecting from the central plenum  214 . The heating wire  260  (such as a tungsten wire) can be installed on the extended portion in the central plenum  212  to reduce heating of the side plenums  214  due to heat that is generated from the heating wire  260 .  
         [0040]    A duct  270  may be installed surrounding the extended portion of the central plenum  212 , and cooling water may flow through the duct  270 . The duct  270  may optionally be installed on entire outer wall of the central plenum  212  or the housing  210 .  
         [0041]    If it is necessary to decompose two or more different reactant gases, the reactant gases can be supplied to the process chamber  100  through the same central plenum  212 . Optionally the housing  210  may comprise a plurality of the central plenums  212  and the reactant gases may be supplied to the process chamber  100  through respective central plenums  212 .  
         [0042]    A deposition system according to embodiments of the present invention may be used to process a single substrate or to simultaneously process a plurality of substrates. In addition, atomic layer deposition and/or chemical vapor deposition may be performed in a deposition system according to embodiments of the present invention  
         [0043]    According to embodiments of the present invention, a deposition system may provide improved deposition characteristics and structures. According to embodiments of the present invention, a deposition system may include a process chamber, a boat on which substrates are placed, and a showerhead that sprays gases in parallel with surfaces of substrates placed on the boat.  
         [0044]    The showerhead may include a housing and a heating element for decomposing the gases. An inlet port connected with a pipe can be installed on a side of the housing and a spray plate spraying the decomposed gases into the process chamber can be installed on the opposite side of the housing. The heating element may include a heating wire and terminals. The terminals can be provided at opposite sides of the housing and the heating wire can be connected with the terminals. The heating wire can be made of a catalytic material (such as tungsten) to accelerate decomposition of the gases, and the heating wire can be formed in a coil. Insulators may be inserted between the housing and the terminals, and a cooling element can be provided in the outer wall of the housing.  
         [0045]    According to additional embodiments of the present invention, the showerhead may include a plurality of plenums and a heating element may be installed in at least one but not all of the plenums.  
         [0046]    According to yet additional embodiments of the present invention, the showerhead may have at least a first plenum where first gases flow and at least a second plenum where second gases flow. A heating element such as a hot wire can be installed in the first plenum, and the first plenum can have an extended portion projecting from the second plenum. In addition, a heating element such as a heating wire can be located in the extended portion to reduce heating of the second plenum due to heat that is generated from the heating element.  
         [0047]    While this invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and equivalents.