Patent Publication Number: US-2012037931-A1

Title: Semiconductor light emitting devices including an optically transmissive  element and methods for packaging the same

Description:
RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 12/886,001 filed Sep. 20, 2010, which is a continuation of U.S. Pat. No. 7,799,586 issued Sep. 21, 2010 (U.S. patent application Ser. No. 12/398,626 filed Mar. 5, 2009), which is a continuation of U.S. Pat. No. 7,517,728 issued Apr. 14, 2009 (U.S. patent application Ser. No. 11/055,194 filed Feb. 10, 2005), which claims the benefit of and priority to U. S. Provisional Patent Application No. 60/558,314, entitled “Reflector Packages and Methods for Forming Packaging of a Semiconductor Light Emitting Device,” filed Mar. 31, 2004, and U.S. Provisional Patent Application No. 60/637,700, entitled “Semiconductor Light Emitting Devices Including a Luminescent Conversion Element and Methods for Packaging the Same,” filed Dec. 21, 2004, the disclosures of which are hereby incorporated herein by reference as if set forth in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to semiconductor light emitting devices and fabricating methods therefore, and more particularly to packaging and packaging methods for semiconductor light emitting devices. 
     It is known to provide semiconductor light emitting device type light sources in packages that may provide protection, color selection, focusing and the like for light emitted by the light emitting device. For example, the light emitting device may be a light emitting diode (“LED”). Various problems may be encountered during packaging of a power LED for use as a light source. Examples of such possible problems will be described with reference to the cross-sectional illustrations of a power LED in  FIGS. 1 and 2 . As shown in  FIGS. 1 and 2 , a power LED package  100  generally includes a substrate member  102  on which a light emitting device  103  is mounted. The light emitting device  103  may, for example, include an LED chip/submount assembly  103   b  mounted to the substrate member  102  and an LED  103   a  positioned on the LED chip/submount assembly  103   b.  The substrate member  102  may include traces or metal leads for connecting the package  100  to external circuitry. The substrate  102  may also act as a heatsink to conduct heat away from the LED  103  during operation. 
     A reflector, such as the reflector cup  104 , may be mounted on the substrate  102  and surround the light emitting device  103 . The reflector cup  104  illustrated in  FIG. 1  includes an angled or sloped lower sidewall  106  for reflecting light generated by the LED  103  upwardly and away from the LED package  100 . The illustrated reflector cup  104  also includes upwardly-extending walls  105  that may act as a channel for holding a lens  120  in the LED package  100  and a horizontal shoulder portion  108 . 
     As illustrated in  FIG. 1 , after the light emitting device  103  is mounted on the substrate  102 , an encapsulant material  112 , such as liquid silicone gel, is dispensed into an interior reflective cavity  115  of the reflector cup  104 . The interior reflective cavity  115  illustrated in  FIG. 1  has a bottom surface defined by the substrate  102  to provide a closed cavity capable of retaining a liquid encapsulant material  112  therein. As further shown in  FIG. 1 , when the encapsulant material  112  is dispensed into the cavity  115 , it may wick up the interior side of the sidewall  105  of the reflector cup  104 , forming the illustrated concave meniscus. 
     As shown in  FIG. 2 , a lens  120  may then be placed into the reflective cavity  115  in contact with the encapsulant material  112 . When the lens  120  is placed in the cavity  115 , the liquid encapsulant material  112  may be displaced and move through the gap  117  between the lens  120  and the sidewall  105 . The encapsulant may, thus, be moved out onto the upper surface of the lens  120  and/or upper surfaces of the sidewall  105  of the reflector cup  104 . This movement, which may be referred to as squeeze-out, is generally undesirable for a number of reasons. In the depicted package arrangement, the lens will sit on a lower shelf if the encapsulant is not cured in a domed meniscus shape prior to the lens attach step. This may cause the lens to not float during thermal cycling and fail via delamination of encapsulation to other surfaces or via cohesive failure within the delamination, both of which may affect the light output. The encapsulant material or gel is generally sticky and may interfere with automated processing tools used to manufacture the parts. Moreover, the gel may interfere with light output from the lens  120 , for example, by changing the light distribution pattern and/or by blocking portions of the lens  120 . The sticky gel may also attract dust, dirt and/or other contaminants that could block or reduce light output from the LED package  100 . The gel may also change the shape of the effective lens, which may modify the emitted light pattern/beam shape. 
     After placement of the lens  120 , the package  100  is typically heat-cured, which causes the encapsulant material  112  to solidify and adhere to the lens  120 . The lens  120  may, thus, be held in place by the cured encapsulant material  112 . However, encapsulant materials having a slight shrinkage factor with curing, such as a silicone gel, generally tend to contract during the heat curing process. In addition, the coefficient of thermal expansion (CTE) effect generally causes higher floating of the lens at elevated temperatures. During cool-down, parts have a tendency to delaminate. As the illustrated volume of encapsulant beneath the lens  120  shown in  FIG. 2  is relatively large, this contraction may cause the encapsulant material  112  to delaminate (pull away) from portions of the package  100 , including the light emitting device  103 , a surface of the substrate  102 , the sidewalls  105  of the reflector cup  104  and/or the lens  120  during the curing process. The delamination may significantly affect optical performance, particularly when the delamination is from the die, where it may cause total internal reflection. This contraction may create gaps or voids  113  between the encapsulant material  112  and the light emitting device  103 , lens  120 , and/or reflector cup  104 . Tri-axial stresses in the encapsulant material  112  may also cause cohesive tears  113 ′ in the encapsulant material  112 . These gaps  113  and/or tears  113 ′ may substantially reduce the amount of light emitted by the light emitting device package  100 . The contraction may also pull out air pockets from crevices (i.e., reflector) or from under devices (i.e., die/submount), which may then interfere with optical cavity performance. 
     During operation of the lamp, large amounts of heat may be generated by the light emitting device  103 . Much of the heat may be dissipated by the substrate  102  and the reflector cup  104 , each of which may act as a heatsink for the package  100 . However, the temperature of the package  100  may still increase significantly during operation. Encapsulant materials  112 , such as silicone gels, typically have high coefficients of thermal expansion. As a result, when the package  100  heats up, the encapsulant material  112  may expand. As the lens  120  is mounted within a channel defined by the sidewalls  105  of the reflector cup  104 , the lens  120  may travel up and down within the sidewalls  105  as the encapsulant material  112  expands and contracts. Expansion of the encapsulant material  112  may extrude the encapsulant into spaces or out of the cavity such that, when cooled, it may not move back into the cavity. This could cause delamination, voids, higher triaxial stresses and/or the like, which may result in less robust light emitting devices. Such lens movement is further described, for example, in United States Patent. Application Pub. No. 2004/0041222. The sidewalls  105  may also help protect the lens  120  from mechanical shock and stress. 
     SUMMARY OF THE INVENTION 
     Embodiments of the present invention provide methods of packaging a semiconductor light emitting device. A first quantity of encapsulant material is dispensed into a cavity including the light emitting device (which may be a plurality of light emitting devices, such as light emitting diodes), which may be a reflective cavity. The first quantity of encapsulant material in the reflective cavity is treated to form a hardened upper surface thereof having a shape. A luminescent conversion element is provided on the upper surface of the treated first quantity of encapsulant material. The luminescent conversion element includes a wavelength conversion material, such as phosphor and/or nano-crystals, and has a thickness at a middle region of the reflective cavity greater than at a region proximate a sidewall of the reflective cavity. 
     The thickness of the luminescent conversion element may continuously decrease as the luminescent conversion element extends radially outward from the middle region to the sidewall. The thickness of the luminescent conversion element may vary by more than ten percent of a maximum thickness of the luminescent conversion element. The luminescent conversion element may have a biconvex, plano-convex or concavo-convex shape. 
     In other embodiments of the present invention, the methods further include dispensing a second quantity of encapsulant material onto the luminescent conversion element to form a convex meniscus of encapsulant material in the reflective cavity providing a desired shape of a lens. The second quantity of encapsulant material is cured to form the lens for the packaged light emitting device from the encapsulant material. In alternative embodiments, the methods include dispensing a second quantity of encapsulant material onto the luminescent conversion element and positioning a lens in the reflective cavity on the dispensed second quantity of encapsulant material. The dispensed second quantity of encapsulant material is cured to attach the lens in the reflective cavity. 
     In further embodiments of the present invention, providing a luminescent conversion element includes dispensing a second quantity of encapsulant material onto the upper surface of the first quantity of encapsulant material. The second quantity of encapsulant material has the wavelength conversion material therein. The second quantity of encapsulant material is cured to define the luminescent conversion element. 
     In some embodiments of the present invention, the luminescent conversion element has a biconvex shape. The shape is concave and dispensing and curing the second quantity of encapsulant material includes dispensing and curing the second quantity of encapsulant material to form a convex upper surface of the second quantity of encapsulant material. 
     In further embodiments of the present invention, the luminescent conversion element has a plano-convex shape and the shape is concave. Dispensing and curing the second quantity of encapsulant material includes dispensing and curing the second quantity of encapsulant material to form a planar upper surface of the second quantity of encapsulant material. In alternative plano-convex shape embodiments, the shape is planar and dispensing and curing the second quantity of encapsulant material includes dispensing and curing the second quantity of encapsulant material to form a convex upper surface of the second quantity of encapsulant material. 
     In other embodiments of the present invention, the luminescent conversion element has a concavo-convex shape and the shape is convex. Dispensing and curing the second quantity of encapsulant material includes dispensing and curing the second quantity of encapsulant material to form a convex upper surface of the second quantity of encapsulant material. In alternative concavo-convex shape embodiments, the shape is concave and dispensing and curing the second quantity of encapsulant material includes dispensing and curing the second quantity of encapsulant material to form a concave upper surface of the second quantity of encapsulant material. 
     In further embodiments of the present invention, treating the first quantity of encapsulant material includes curing the first quantity of encapsulant material. In alternative embodiments, treating the first quantity of encapsulant material includes pre-curing the first quantity of encapsulant material to form a hardened skin on the upper surface thereof and the method further comprises curing the first quantity of encapsulant material after providing the luminescent conversion element. The wavelength conversion material may be phosphor and the first quantity of encapsulant material is substantially free of phosphor. 
     In other embodiments of the present invention, the luminescent conversion element is a pre-formed insert and the pre-formed insert is placed on the upper surface of the treated first quantity of encapsulant material. The pre-formed insert may be a molded plastic phosphor-loaded piece part. Placing the pre-formed insert on the upper surface may be preceded by testing the pre-formed insert. 
     In yet other embodiments of the present invention, packaged semiconductor light emitting devices include a body, such as a reflector, having a lower sidewall portion defining a cavity, which may be a reflective cavity. A light emitting device is positioned in the cavity. A first quantity of cured encapsulant material is provided in the cavity including the light emitting device. A luminescent conversion element is on the upper surface of the first quantity of encapsulant material. The luminescent conversion element includes a wavelength conversion material and has a thickness at a middle region of the cavity greater than at a region proximate a sidewall of the cavity. The thickness of the luminescent conversion element may continuously decrease as the luminescent conversion element extends radially outward from the middle region to the sidewall. The thickness of the luminescent conversion element may vary by more than ten percent of a maximum thickness of the luminescent conversion element. 
     In some embodiments of the present invention, the luminescent conversion element has a biconvex, plano-convex or concavo-convex shape. The light emitting device may be a light emitting diode (LED). 
     In other embodiments of the present invention, the device has a minimum color temperature no more than 30 percent below a maximum color temperature thereof over a 180 (+/−90 from central axis)-degree range of emission angles. The device may have a primary emission pattern having a total correlated color temperature (CCT) variation of less than about 1000K over a 180 (+/−90 from central axis)-degree range of emission angles. In other embodiments, the device has a primary emission pattern having a total CCT variation of about 500K over a 180 (+/−90 from central axis)-degree range of emission angles or over a 120 (+/−45 from central axis)-degree range of emission angles. In yet other embodiments, the device has a primary emission pattern having a total correlated color temperature (CCT) variation of less than about 500K over a 90 (+/−45 from central axis)-degree range of emission angles. 
     In yet further embodiments of the present invention, packaged semiconductor light emitting devices include a body having a sidewall portion defining a cavity and a light emitting device positioned in the cavity. A first quantity of cured encapsulant material is in the cavity including the light emitting device and a luminescent conversion element is on an upper surface of the first quantity of encapsulant material. The luminescent conversion element includes a wavelength conversion material. The packaged semiconductor light emitting device exhibits a variation of correlated color temperature (CCT)) across a 180 (+/−90 from central axis)-degree range of emission angles of less than 2000K. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 and 2  are cross-sectional side views illustrating a conventional light emitting device package; 
         FIGS. 3A to 3C  are cross-sectional side views illustrating methods of packaging a light emitting device according to some embodiments of the present invention; 
         FIG. 4A  is a top view illustrating a light emitting device package suitable for use with some embodiments of the present invention; 
         FIG. 4B  is a cross-sectional side view illustrating the light emitting device package of  FIG. 4A ; 
         FIG. 5A  is a top view illustrating a light emitting device package according to some embodiments of the present invention; 
         FIG. 5B  is a cross-sectional side view illustrating the light emitting device package of  FIG. 5A ; 
         FIG. 6  is a cross-sectional side view illustrating a light emitting device package according to further embodiments of the present invention; 
         FIG. 7  is a cross-sectional side view illustrating a light emitting device package according to other embodiments of the present invention; 
         FIGS. 8A to 8C  are cross-sectional side views illustrating methods of packaging a light emitting device according to further embodiments of the present invention; 
         FIGS. 9A to 9C  are cross-sectional side views illustrating methods of packaging a light emitting device according to other embodiments of the present invention; 
         FIGS. 10A to 10C  are cross-sectional side views illustrating methods of packaging a light emitting device according to yet further embodiments of the present invention; 
         FIG. 11  is a flowchart illustrating operations for packaging a light emitting device according to some embodiments of the present invention; 
         FIG. 12  is a flowchart illustrating operations for packaging a light emitting device according to some other embodiments of the present invention; 
         FIG. 13  is a flowchart illustrating operations for packaging a light emitting device according to yet further embodiments of the present invention; 
         FIG. 14  is a schematic diagram illustrating path length for light traveling through a layer; 
         FIG. 15  is a polar plot of color-temperature for a light emitting diode (LED) emission pattern; 
         FIGS. 16A to 16C  are cross-sectional side views illustrating methods of packaging a light emitting device including a luminescent conversion element according to further embodiments of the present invention; 
         FIGS. 17A to 17C  are cross-sectional side views illustrating methods of packaging a light emitting device including a luminescent conversion element according to other embodiments of the present invention; 
         FIGS. 18A to 18C  are cross-sectional side views illustrating methods of packaging a light emitting device including a luminescent conversion element according to some other embodiments of the present invention; 
         FIG. 19  is a flowchart illustrating operations for packaging a light emitting device according to some further embodiments of the present invention; 
         FIG. 20A  is a polar plot of color-temperature for a light emitting diode (LED) emission pattern for a glob-top semiconductor light emitting device without a luminescence conversion element of the present invention; 
         FIG. 20B  is a polar plot of color-temperature for a light emitting diode (LED) emission pattern for a semiconductor light emitting device with a luminescence conversion element according to some embodiments of the present invention; 
         FIGS. 21A and 21B  are digitally analyzed plots of the near field emission pattern of packaged semiconductor light emitting device without a luminescence conversion element; and 
         FIGS. 22A and 22B  are digitally analyzed plots of the near field emission pattern of packaged semiconductor light emitting device including a luminescence conversion element according to some embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as 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 scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. Like numbers refer to like elements throughout. 
     It will be understood that when an element such as a layer, region or substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. It will be understood that if part of an element, such as a surface, is referred to as “inner,” it is farther from the outside of the device than other parts of the element. Furthermore, relative terms such as “beneath” or “overlies” may be used herein to describe a relationship of one layer or region to another layer or region relative to a substrate or base layer as illustrated in the figures. It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures. Finally, the term “directly” means that there are no intervening elements. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention. 
     Various embodiments of the present invention for packaging a semiconductor light emitting device  103  will be described herein. As used herein, the term semiconductor light emitting device  103  may include a light emitting diode, laser diode and/or other semiconductor device which includes one or more semiconductor layers, which may include silicon, silicon carbide, gallium nitride and/or other semiconductor materials, a substrate which may include sapphire, silicon, silicon carbide and/or other microelectronic substrates, and one or more contact layers which may include metal and/or other conductive layers. In some embodiments, ultraviolet, blue and/or green light emitting diodes (“LEDs”) may be provided. Red and/or amber LEDs may also be provided. The design and fabrication of semiconductor light emitting devices  103  are well known to those having skill in the art and need not be described in detail herein. 
     For example, the semiconductor light emitting device  103  may be gallium nitride-based LEDs or lasers fabricated on a silicon carbide substrate such as those devices manufactured and sold by Cree, Inc. of Durham, N.C.. The present invention may be suitable for use with LEDs and/or lasers as described in U.S. Pat. Nos. 6,201,262; 6,187,606; 6,120,600; 5,912,477; 5,739,554; 5,631,190; 5,604,135; 5,523,589; 5,416,342; 5,393,993; 5,338,944; 5,210,051; 5,027,168; 5,027,168; 4,966,862 and/or 4,918,497, the disclosures of which are incorporated herein by reference as if set forth fully herein. Other suitable LEDs and/or lasers are described in published U.S. Patent Publication No. US 2003/0006418 A1 entitled Group III Nitride Based Light Emitting Diode Structures With a Quantum Well and Superlattice, Group III Nitride Based Quantum Well Structures and Group III Nitride Based Superlattice Structures, published Jan. 9, 2003, as well as published U.S. Patent Publication No. US 2002/0123164 A1 entitled Light Emitting Diodes Including Modifications for Light Extraction and Manufacturing Methods Therefor. Furthermore, phosphor coated LEDs, such as those described in U.S. application Ser. No. 10/659,241, entitled Phosphor-Coated Light Emitting Diodes Including Tapered Sidewalls and Fabrication Methods Therefor, filed Sep. 9, 2003, the disclosure of which is incorporated by reference herein as if set forth fully, may also be suitable for use in embodiments of the present invention. The LEDs and/or lasers may be configured to operate such that light emission occurs through the substrate. In such embodiments, the substrate may be patterned so as to enhance light output of the devices as is described, for example, in the above-cited U.S. Patent Publication No. US 2002/0123164 A1. 
     Embodiments of the present invention will now be described with reference to the various embodiments illustrated in  FIGS. 3-11 . More particularly, some embodiments of a double-cure encapsulation process for use in packaging a light emitting device  103  are illustrated in  FIGS. 3A through 3C . Such a double cure encapsulation process may reduce problems associated with shrinkage of encapsulant material during curing. As will be described herein, for some embodiments of the present invention, the double cure process may include three dispense operations and two cure operations. However, it will be understood that more or less dispense operations and cure operations may also be used in packaging the light emitting device in other embodiments of the present invention. As will also be further described herein, embodiments of the present invention also include a multi-dispense operation, leading to a first cure operation followed by another set of dispense and cure operations to attach a lens. 
     As illustrated in  FIG. 3A , a first predetermined amount (quantity) of an encapsulant material, including two encapsulant material portions  112 ,  114  in the illustrated embodiments, is dispensed within the cavity  115 . The encapsulant material  112 ,  114  may be, for example, a liquid silicon gel, an epoxy or the like. The first portion  112  may be dispensed to wet exposed surface portions of the light emitting device  103 , more particularly, the led chip/submount assembly  101  of the light emitting device  103 , and the substrate  102 . Portions of the reflector cup  104  may also be wet by the initial dispense. In some embodiments of the present invention, the quantity of encapsulant material dispensed as the first portion  112  is sufficient to wet the light emitting device  103  without filling the reflective cavity to a level exceeding the height of the light emitting device  103 . In some other embodiments of the present invention, the quantity of encapsulant material dispensed as the first portion  112  is sufficient to substantially cover the light emitting device  103  without forming any air pockets in the encapsulant material  112 . 
     As shown in  FIG. 3A , the light emitting device is positioned at about a midpoint  115   m  of the reflective cavity  115 . The encapsulant material may be dispensed from a dispenser  200  at a point  115   d  displaced from the midpoint  115   m  towards a sidewall  105  of the reflective cavity  115  so that the encapsulant material  112  is not dispensed directly onto the light emitting device  103 . Dispensing encapsulant material  112  directly on the light emitting device  103  may cause trapping of bubbles as the encapsulant material  112  passes over the structure of the light emitting device  103  from above. However, in other embodiments of the present invention, the encapsulant material  112  is dispensed on top of the light emitting device  103  die in addition to or instead of an offset dispense. Dispensing the encapsulant material  112  may include forming a bead of the encapsulant material  112  on an end of a dispenser  200  and contacting the formed bead with the reflective cavity  115  and/or the light emitting device  103  to dispense the bead from the dispenser. 
     The viscosity and/or other properties of the material used for a dispense may be selected such that, for example, wetting occurs without bubble formation. In further embodiments of the present invention, coatings may be applied to surfaces contacted by the dispensed material to speed/retard the wetting rate. For example, using certain known cleaning procedures that leave microscopic residue, such as an oil film, selected surfaces may be treated and, thus, used to engineer the dynamics of the wetting action. 
     Due to the surface properties of the inner surface of the reflector cup  104  defining the cavity  115 , of the light emitting device  103  and of the encapsulant material  112 , dispensed encapsulant material  112 , even when dispensed from a point  115   d  displaced from the midpoint  115   m  of the cavity  115 , may flow within the cavity  115  in a manner that could still cause bubbles in the encapsulant material  112 . In particular, the encapsulant material  112  is expected to move or “wick” more rapidly around the inner surface of the reflector cup  104  and the sidewalls of the light emitting device  103  faster than over the top of the light emitting device  103 . As a result, a bubble could be trapped on a side of the cavity  115  opposite from the side where the encapsulant material is dispensed when the side flowing encapsulant material meets and then encapsulant material flows over the top of the light emitting device  103 , thus being locally dispensed from above with no side outlet for air flow. Accordingly, the quantity of the first portion of dispensed encapsulant material  112  may be selected to reduce or prevent the risk of forming such bubbles. As such, as used herein, reference to “substantially” covering the light emitting device  103  refers to covering enough of the structure of the light emitting device  103  so that such a bubble will not result when the remaining portion  114  of the first quantity of encapsulant material  112 ,  114  is dispensed. 
     After the initially dispensed encapsulant material  112  is allowed to settle, the second portion  114  of the first predetermined quantity of encapsulant material is dispensed into the reflective cavity  115 . The second portion  114  of the encapsulant material, in some particular embodiments of the present invention, is about twice the first portion  112 . 
     After dispensing all the first quantity of encapsulant material  112 ,  114 , the first quantity of the encapsulant material  112 ,  114  is cured, for example, by a heat treatment, to solidify the encapsulant material  112 ,  114 . After curing, the level of the encapsulant material  112 ,  114  within the reflective cavity  115  may drop from the level  114 A to the level  114 B as a result of shrinkage of the encapsulant material  112 ,  114 . 
     In some embodiments of the present invention, the first portion  112  is cured before the second portion  114  is dispensed into the reflective cavity  115 . For example, it is known to add a light converting material, such as a phosphor, nano-crystals, or the like, to the encapsulant material  112 ,  114  to affect the characteristics of the light emitted from the package  100 . For purposes of the description herein, references will be made to a phosphor as a light converting material. However, it will be understood that other light converting materials may be used in place of phosphor. Depending on the desired color spectrum and/or color temperature tuning for the package  100 , phosphor may be most beneficially utilized when positioned adjacent the emitter  103   b,  in other words, directly on top of the light emitting device  103 . As such, it may be desirable to include a phosphor in the second portion  114  while not including a phosphor in the first portion  112 . However, as the first portion  112  is below the second portion  114 , phosphor may settle from the second portion  114  into the first portion  112 , reducing the effectiveness of the phosphor addition in the second portion  114 . Accordingly, phosphor can be added to the first portion  112  to limit such settling and/or the first portion  112  can be cured before dispensing the second portion  114 . The use of multiple dispenses may also allow the addition of a phosphor preform/wafer of a desired configuration for light conversion. In addition, multiple dispenses may allow for the use of materials having different indexes of refraction to provide, for example, a buried lens (i.e., formed by the interface between two dispenses of materials with different refractive indexes). 
     As illustrated in  FIG. 3B , a second quantity of encapsulant material  116  is dispensed in a predetermined amount onto the cured first quantity of encapsulant material  112 ,  114  in the reflective cavity  115 . In some particular embodiments of the present invention the second quantity  116  is about equal to the first portion  112  of the first quantity of encapsulant material  112 ,  114 . The second quantity  116  may be substantially free of phosphor, however, in other embodiments of the present invention, phosphor may also be included in the second quantity  116 . 
     As shown in  FIG. 3C , before the second quantity of encapsulant material  116  is cured, a lens  120  is positioned within the reflective cavity  115  and against the second quantity of encapsulant material  116 . The second quantity of encapsulant material  116  is then cured, for example, by heating, to harden the encapsulant material  116  and to attach the lens  120  in the reflective cavity  115 . In some embodiments of the present invention, use of a double cure process as described above to encapsulate the light emitting device  103  in the package  100  may reduce delamination of the cured encapsulant material  112 ,  114 ,  116  from the light emitting device  103 , the lens  120  and/or the reflector cup  104 . 
     The reflector cup  104  shown in  FIGS. 3A-3B  is further illustrated in  FIGS. 4A-4B .  FIG. 4A  is a top plan view of the reflector cup  104  showing the top surfaces of the upper sidewall  105 , the lower sidewall  106  and a substantially horizontal shoulder sidewall portion  108  between the upper sidewall  105  and the lower sidewall  106 .  FIG. 4B  is a cross-sectional view of the reflector cup  104  taken along line B-B of  FIG. 4A . 
     Alternative reflector cup configurations according to various embodiments of the present invention will now be described as well as methods for packaging of a light emitting device using such alternative reflector cup configurations. In various embodiments of the present invention, these alternative reflector cup configurations may reduce the incidence and/or amount of squeeze out of encapsulant material on insertion of a lens into encapsulant material in the reflector cup.  FIGS. 5A-5B ,  6  and  7  illustrate various alternative reflector configurations as will now be described.  FIG. 5A  is a top plan view of a reflector cup  4  and  FIG. 5B  is a cross-sectional view of the reflector cup  4  taken along line B-B of  FIG. 5A .  FIG. 6  is a cross-sectional view of a reflector cup  4 A and  FIG. 7  is a cross-sectional view of a reflector cup  4 B. Each of the illustrated reflector cups  4 ,  4 A,  4 B includes an upper sidewall  5 , an angled lower sidewall  6  and a horizontal shoulder portion  8  between the upper sidewall  5  and the lower sidewall  6 , together defining a reflective cavity  15 . As used herein with reference to the shoulder portion  8 , “horizontal” refers to the general direction in which the shoulder portion  8  extends between the lower sidewall portion  6  and the upper sidewall portion  8  (i.e., as compared to the lower  6  and upper  5  sidewall portions), not to the particular angle of the shoulder portion  8  at any intermediate portion thereof (see, e.g.,  FIG. 7  where the horizontal shoulder portion may actually have some change in vertical height between the lower  6  and upper  5  sidewall portions to accommodate other features thereof). In addition, each of the reflector cups  4 ,  4 A,  4 B may include at least one moat  18  surrounding the lower sidewall  6 , with the moat  18  being separated from the lower sidewall  6  by a lip (i.e., a projecting edge)  22 . The moat  18  is illustrated as formed in the shoulder portion  8 . 
     In the embodiments of  FIGS. 5A-5B , the moat  18  could be formed by stamping, in which case the lip  22  between the moat  18  and the lower sidewall  6  may be provided with a sharp edge instead of a flat surface. However, it will be understand that, due to the limitations of the fabricating processes used, the flat surface of the lip  22  schematically illustrated in  FIG. 5B  may actually have a more rounded profile. Too much of a rounded profile may be undesirable as will be further described with reference to  FIGS. 8A-8C . 
     Further embodiments of a reflector cup  4 A will now be described with reference to the cross-sectional view of  FIG. 6 . As shown in  FIG. 6 , a first moat  18  is formed between the upper sidewall  5  and the lower sidewall  6 , with a first or inner lip  22  separating the lower sidewall  6  and the first moat  18 . A second moat  24  is formed between the upper sidewall  5  and the first moat  18 . A second or outer lip  26  separates the second moat  24  from the first moat  18 . 
     Yet further embodiments of a reflector cup  4 B will now be described with reference to the cross-sectional view of  FIG. 7 . As shown in  FIG. 7 , a first moat  18  is formed between the upper sidewall  5  and the lower sidewall  6 , with a first or inner lip  22  separating the lower sidewall  6  and the first moat  18 . A second moat  24  is formed between the upper sidewall  5  and the first moat  18 . A second or outer lip  26 ′ separates the second moat  24  from the first moat  18 . As illustrated in  FIG. 7 , the second lip  26 ′ is elevated with respect to the first lip  22 . 
     In particular embodiments of the present invention, the first lip  22  has a peak having a radius of curvature of less than about 50 micrometers (μm) and the second lip  26 ,  26 ′ has a peak having a radius of curvature of less than about 50 μm. The first moat  18  and the second moat  24  may be stamped features of the horizontal shoulder portion  8 . As shown in  FIGS. 6 and 7 , the second moat  24  may have a width extending from the second lip  26 ,  26 ′ to the upper sidewall portion  5 . 
     In some embodiments of the present invention, the sloped lower sidewall portion  6  may be substantially conical and may have a minimum diameter of from about 1.9 millimeters (mm) for a 500 μm light emitting device chip to about 3.2 mm for a 900 μm light emitting device chip and a maximum diameter of from about 2.6 mm for a 500 μm light emitting device chip to about 4.5 mm for a 900 μm light emitting device chip and a height of from about 0.8 mm to about 1.0 mm. The upper sidewall portion may be substantially oval and have an inner diameter of from about 3.4 mm to about 5.2 mm and a height of from about 0.6 mm to about 0.7 mm. The horizontal shoulder portion may have a width from the lower sidewall portion to the upper sidewall portion of from about 0.4 mm to about 0.7 mm. It will be understood that, as used herein, the terms “oval” and “conical” are intended to encompass circular, cylindrical and other shapes, including irregular shapes based on the fabrication technology used to form the reflector cup  4 ,  4 A,  4 B that may, nonetheless, in combination with a substrate  2  or otherwise, operate to provide a reflector for the light emitting device  103  and retain and harden an encapsulant material  12 ,  14 ,  16  therein. 
     In some embodiments of the present invention, the first moat  18  has a width from about 0.3 mm to about 0.4 mm and the second moat  24  has a width of from about 0.3 mm to about 0.4 mm. As illustrated in  FIG. 6 , the edge of the first moat  18  may be a first lip  22  having a height relative to a bottom end (i.e., a top surface of the substrate  2 ) of the lower sidewall portion  6  of from about 0.79 mm to about 0.85 and the edge of the second moat  24  may be a second lip  26  having a height relative to bottom end of the lower sidewall portion  6  of from about 0.79 mm to about 0.85 mm. In other embodiments of the present invention as illustrated in  FIG. 7 , the first lip  22  has a height relative to a bottom end of the lower sidewall portion of from about 0.79 mm to about 0.85 mm and the second lip  26 ′ has a height relative to a bottom end of the lower sidewall portion of from about 0.9 mm to about 1.0 mm. 
     The reflector cups  4 ,  4 A,  4 B, in various embodiments of the present invention may, provide for meniscus control when packaging the light emitting device  103  in a reflector cup  4 ,  4 A,  4 B. As will be further described, when combined with the double cure methods described above, a distinct convex meniscus may also be provided for different dispenses of encapsulant material and, as a result, the incidence of doming failure may be reduced. In other embodiments of the present invention, the provided meniscus control may reduce the difficulty of lens placement at a desired depth and/or angle, reduce lens wicking or squeeze-out of encapsulant material onto the top of the lens and/or allow for configuration of the optical characteristics of the packaged light emitting device. For example, phosphor may be concentrated in the center (midpoint) of the package by doming (convex meniscus) of phosphor loaded encapsulant material over the midpoint of the package. 
     Different optical patterns (viewing angles, custom color spectrums, color temperature tuning and the like) may be provided by using multiple meniscus control techniques in combination with dispensing and/or curing variations in the process. For example, a high peaked dome of a phosphor loaded material may provide greater color spectrum uniformity of white temperature light emission with less shift to yellow towards the edges of the reflector cup by providing a more uniform length of the light path through the phosphor loaded material from the light emitting device. Similarly, where desired, a greater color spectrum variation from white at the midpoint to yellow at the edges may be provided by a flatter dome. In some other embodiments of the present invention, where protection related functionality is provided by features other than a lens, meniscus control may allow for packaging a light emitting device without a lens by using the encapsulant material as the lens, with the meniscus being configured to provide the desired lens shape. 
       FIGS. 8A-8C  illustrate methods of packaging a light emitting device, using the structural characteristics of a reflector cup for meniscus control, according to some embodiments of the present invention. The operations illustrated in  FIGS. 8A-8C  utilize the reflector cup  4  illustrated in  FIGS. 5A-5B  and the double curing operations also previously described. As shown in  FIG. 8A , a first quantity  14  of encapsulant material is deposited in the reflective cavity  15  of the package  10 A. In some embodiments of the present invention, the first quantity  14  may be dispensed using a separate (wetting) dispense and second dispense. With proper control of the amount of encapsulant material dispensed, surface tension will cause the liquid encapsulant material  14  to cling to the lip  22 , forming a convex meniscus as illustrated in  FIG. 8A  at a height indicated at  14 A. Thus, the lip  22  may be used to prevent the dispensed encapsulant material  14  from contacting and wicking up the upper sidewall  5  and forming a concave meniscus as shown in  FIG. 1 . 
     The dispensed encapsulant material  14  is cured, for example, by heating, and may shrink down to a height indicated at  14 B. As shown in  FIG. 8B , a second quantity  16  of encapsulant material is then dispensed into the cavity  15  on the cured first quantity  14  of encapsulant material. In some embodiments, as illustrated in  FIG. 8B , the second quantity  16  of encapsulant material may also cling to the same edge of the lip  22  to form a convex meniscus. In other embodiments, the lip  22  may have an inner and outer edge thereon and the second quantity  16  of encapsulant material may cling to the outer edge and the first quantity  14  may cling to the inner edge. Thus, the second quantity  16  of encapsulant material may also not contact or wick up the upper sidewall  5  to form a concave meniscus. 
     Referring to  FIG. 8C , the lens  20  is inserted into reflective cavity  15  and brought into contact with the uncured liquid encapsulant material  16 . As such, the encapsulant material  16  may be squeezed out from underneath the lens  20 . However, in some embodiments of the present invention, instead of squeezing out onto the exposed upper surfaces of the reflector cup and the lens (as shown in  FIG. 2 ), the excess of the encapsulant material  16  is squeezed into and received by the moat  18 , thus limiting wicking of the encapsulant material  16  up the sidewall  5  even after the lens  20  is inserted and the convex meniscus shown in  FIG. 8B  is displaced. The encapsulant material  16  is then cured to attach the lens  20  in the package  10 A and to solidify the encapsulant material  16 . 
       FIGS. 9A-9C  illustrate methods of packaging a light emitting device, using the structural characteristics of a reflector cup for meniscus control, according to some embodiments of the present invention. The operations illustrated in  FIGS. 9A-9C  utilize the reflector cup  4 A illustrated in  FIG. 6  and the double curing operations also previously described. As shown in  FIG. 9A , a first quantity  14  of encapsulant material is deposited in the reflective cavity  15  of the package  10 B. In some embodiments of the present invention, the first quantity  14  may be dispensed using a distinct first (wetting) dispense and a second dispense after wetting of the light emitting device. With proper control of the amount of encapsulant material dispensed, surface tension will cause the liquid encapsulant material  14  to cling to the inner lip  22 , forming a convex meniscus as illustrated in  FIG. 9A  at a height indicated at  14 A. Thus, the inner lip  22  may be used to prevent the dispensed encapsulant material  14  from contacting and wicking up the upper sidewall  5  and forming a concave meniscus as shown in  FIG. 1 . 
     The dispensed encapsulant material  14  is cured, for example, by heating, and may shrink down to a height indicated at  14 B. As shown in  FIG. 9B , a second quantity  16  of encapsulant material is then dispensed into the reflective cavity  15  on the cured first quantity  14  of encapsulant material. In some embodiments, as illustrated in  FIG. 9B , the second quantity  16  of encapsulant material clings to the outer lip  26 , forming a convex meniscus. Thus, the outer lip  26  may be used to prevent the dispensed second quantity  16  of encapsulant material from contacting and wicking up the upper sidewall  5  and forming a concave meniscus as shown in  FIG. 1 . 
     Referring to  FIG. 9C , the lens  20  is inserted into reflective cavity  15  and brought into contact with the uncured liquid encapsulant material  16 . As such, the encapsulant material  16  may be squeezed out from underneath the lens  20 . However, in some embodiments of the present invention, instead of squeezing out onto the exposed upper surfaces of the reflector cup and the lens (as shown in  FIG. 2 ), the excess of the encapsulant material  16  is squeezed into and received by the second moat  24 , thus limiting wicking of the encapsulant material  16  up the sidewall  5  even after the lens  20  is inserted and the convex meniscus shown in  FIG. 9B  is displaced. The encapsulant material  16  is then cured to attach the lens  20  in the package  10 B and to solidify the encapsulant material  16 . 
       FIG. 9C  further illustrates that, in some embodiments of the present invention, the cured encapsulant  14  may be used as a stop to provide for level (depth of placement) control for the lens  20 . Such control over the positioning of the lens  20  may facilitate the production of parts with more consistent optical performance. 
     As shown in  FIG. 9C , the lens  20  in some embodiments of the present is positioned without advancing into the cavity until it contacts the cured first quantity of encapsulant material  14  as a film of the encapsulant material  16  remains therebetween. Thus, in some embodiments of the present invention, the device is configured so that the lens  20  may be advanced to a position established by the first quantity of encapsulant material  14 , which position may be established with or without contact of the lens  20  to the cured encapsulant material  14  in various embodiments of the present invention. 
       FIGS. 10A-10C  illustrate methods of packaging a light emitting device, using the structural characteristics of a reflector cup for meniscus control, according to some embodiments of the present invention. The operations illustrated in  FIGS. 10A-10C  utilize the reflector cup  4 B illustrated in  FIG. 7  and the double curing operations also previously described. As shown in  FIG. 10A , a first quantity  14  of encapsulant material is deposited in the reflective cavity  15  of the package  10 C. In some embodiments of the present invention, the first quantity  14  may be dispensed using a separate (wetting) dispense and a second dispense. With proper control of the amount of encapsulant material dispensed, surface tension will cause the liquid encapsulant material  14  to cling to the inner lip  22 , forming a convex meniscus as illustrated in  FIG. 10A  at a height indicated at  14 A. Thus, the inner lip  22  may be used to prevent the dispensed encapsulant material  14  from contacting and wicking up the upper sidewall  5  and forming a concave meniscus as shown in  FIG. 1 . 
     The dispensed encapsulant material  14  is cured, for example, by heating, and may shrink down to a height indicated at  14 B. As shown in  FIG. 10B , a second quantity  16  of encapsulant material is then dispensed into the reflective cavity  15  on the cured first quantity  14  of encapsulant material. In some embodiments, as illustrated in  FIG. 10B , the second quantity  16  of encapsulant material clings to the outer lip  26 ′, forming a convex meniscus. Thus, the outer lip  26 ′ may be used to prevent the dispensed second quantity  16  of encapsulant material from contacting and wicking up the upper sidewall  5  and forming a concave meniscus as shown in  FIG. 1 . 
     Referring to  FIG. 10C , the lens  20  is inserted into reflective cavity  15  and brought into contact with the uncured liquid encapsulant material  16 . As such, the encapsulant material  16  may be squeezed out from underneath the lens  20 . However, in some embodiments of the present invention, instead of squeezing out onto the exposed upper surfaces of the reflector cup and the lens (as shown in  FIG. 2 ), the excess of the encapsulant material  16  is squeezed into and received by the second moat  24 , thus limiting wicking of the encapsulant material  16  up the sidewall  5  even after the lens  20  is inserted and the convex meniscus shown in  FIG. 10B  is displaced. The encapsulant material  16  is then cured to attach the lens  20  in the package  10 C and to solidify the encapsulant material  16 . 
       FIG. 10C  further illustrates that, in some embodiments of the present invention, the outer lip  26 ′ may be used as a stop to provide for level (depth of placement) control for the lens  20 . Such control over the positioning of the lens  20  may facilitate the production of parts with more consistent optical performance. In this embodiment, the lens placement does not depend on the amount of shrinkage of the encapsulant during the first cure step. For the embodiments illustrated in  FIG. 10C , as contrasted with those illustrated in  FIG. 9C , the placement of the lens  20  need not be dependent on the amount of shrinkage of the first quantity  14  of encapsulant material as the placement depth is, instead, defined by the height of the outer lip  26 ′. As such, in some embodiments of the present invention, the placement may be more exact, which may result in improved optical performance of the package  10 C. 
     Methods for packaging a light emitting device using a first (wetting) dispense according to some embodiments of the present invention will now be further described with reference to the flowchart illustrations of  FIG. 11 . As shown in  FIG. 11 , operations may begin at Block  1100  by mounting the light emitting device on a bottom surface of a reflective cavity. The mounted light emitting device has an associated height relative to the bottom surface of the reflective cavity. A first quantity of encapsulant material is dispensed into the reflective cavity including the light emitting device (Block  1120 ). 
     The first quantity may be sufficient to substantially cover the light emitting device without forming any air pockets in the encapsulant material. In some embodiments of the present invention, the first quantity may be sufficient to wet the light emitting device without filling the reflective cavity to a level exceeding the height of the light emitting device. In other embodiments of the present invention, the time/speed of dispense of the encapsulant material may be changed to reduce the formation of air pockets in the encapsulant material. In yet further embodiments, a single dispense may be used, for example, with a slow dispense rate, from a small dispense needle, low pressure, or the like, allowing an air pocket to potentially form and then cave/collapse before enough encapsulant material has been dispensed to prevent collapse of the air pocket. Thus, the first (wetting) dispense and second dispense may be provided by a continuous dispense at a selected rate of a selected viscosity encapsulant material that allows cave/collapse of a formed air pocket during the dispense operation The first quantity may be sufficient to wet the light emitting device without filling the reflective cavity to a level exceeding the height of the light emitting device. 
     A second quantity of encapsulant material is dispensed onto the first quantity of encapsulant material (Block  1130 ). The dispensed first and second quantity of encapsulant material are then cured (Block  1140 ). In some embodiments of the present invention, the first dispensed wetting quantity of encapsulant material may be cured before the remainder of the encapsulant material is dispensed. 
     The first quantity  12 ,  14  and the second quantity  16  of the encapsulant material may be the same or different materials. Similarly, the first  12  and second  14  portions of the first quantity of the encapsulant material may be the same or different materials. Examples of materials that may be used as an encapsulant material in various embodiments of the present invention include silicon. 
     Operations related to packaging a semiconductor light emitting device according to some embodiments of the present invention using meniscus control will now be described with reference to the flowchart illustration of  FIG. 12 . As shown in  FIG. 12 , operations may begin at Block  1200  with mounting of the light emitting device  103  in a reflective cavity  15  of a reflector  5 . Encapsulant material is dispensed into the reflective cavity  15  including the light emitting device  103  therein to cover the light emitting device  103  and to form a convex meniscus of encapsulant material in the reflective cavity extending from an edge of the moat without contacting the upper sidewall  5  of the reflector  4 ,  4 A,  4 B (Block  1210 ). More generally, operations at Block  1210  provide for formation of a convex meniscus extending from an outer edge of the meniscus that is at a height positioning the outer edge of the meniscus within the reflective cavity  15 . For example, selection of materials used for the upper sidewall  5  and the encapsulant material  12 ,  14 ,  16  may facilitate formation of a convex, rather than concave, meniscus extending into the reflective cavity  15 . The encapsulant material  12 ,  14 ,  16  is in the reflective cavity  15  (Block  1220 ). In embodiments where a lens  20  is included in the package  10 A,  10 B,  10 C, insertion of the lens  20  may include collapsing the convex meniscus and moving a portion of the encapsulant material  12 ,  14 ,  16  into the moat  18 ,  24  with the lens  20  and then curing the encapsulant material  12 ,  14 ,  16  to attach the lens  20  in the reflective cavity  15 . Alternatively, the encapsulant material  12 ,  14 ,  16  may be cured to form a lens for the packaged light emitting device  103  from the encapsulant material  12 ,  14 ,  16  and the encapsulant material  12 ,  14 ,  16  may be dispensed to form a convex meniscus providing a desired shape of the lens. 
     Embodiments of methods of packaging a semiconductor light emitting device  103  in a reflector  4 ,  4 A,  4 B having a moat  18 ,  24  positioned between a lower  6  and an upper  5  sidewall thereof, the upper  5  and lower  6  sidewall defining a reflective cavity  15 , using a multiple dispense and/or cure operation will now be further described with reference to  FIG. 13 . As shown in the embodiments of  FIG. 13 , operations begin at Block  1300  by dispensing a first quantity  14  of encapsulant material into the reflective cavity  15  to form a first convex meniscus. The first quantity  14  of encapsulant material is cured (Block  1310 ). A second quantity  16  of encapsulant material is dispensed onto the cured first quantity  14  of encapsulant material to form a second convex meniscus of encapsulant material in the reflective cavity  15  extending from an edge of the moat  18 ,  24  without contacting the upper sidewall  5  of the reflector  4 ,  4 A,  4 B (Block  1320 ). 
     The second convex meniscus and the first convex meniscus of encapsulant material may both extend from the same edge of the moat  18  as illustrated in  FIG. 8B . However, in other embodiments of the present invention, the moat  18 ,  24  may have an inner edge and an outer edge, such as the first lip  22  and the second lip  26 ,  26 ′, and the second convex meniscus of encapsulant material extends from the outer edge (second lip  26 ,  26 ′)of the moat  18 ,  24  and the first convex meniscus of encapsulant material extends from the inner edge (first lip  22 ) of the moat  18 ,  24 . Thus, using the first lip  22 , the inner moat  18  may be configured to limit wicking of encapsulant material  14  outwardly along the horizontal shoulder portion  8  to allow formation of a first convex meniscus of encapsulant material dispensed into the reflective cavity  15 . Using the second lip  26 ,  26 ′, the outer moat  24  may be configured to limit wicking of encapsulant material outwardly along the horizontal shoulder portion  8  to allow formation of a second convex meniscus of encapsulant material dispensed into the reflective cavity  15 . 
     In some embodiments of the present invention including a lens, the lens  20  is positioned in the reflective cavity  15  proximate the dispensed second quantity  16  of encapsulant material (Block  1330 ). Positioning the lens  20  may include collapsing the second convex meniscus and moving a portion of the second quantity  16  of encapsulant material into the outer moat  24  with the lens  20  as illustrated in  FIGS. 9C and 10C . In addition, as illustrated in  FIG. 10C , the second lip  26 ′ may have a height greater than that of the first lip  22 . The height of the second lip  26 ′ may be selected to provide a desired position for the lens  20  and the lens  20  may be moved into the reflective cavity  15  until it contacts the second lip  26 ′. In other embodiments of the present invention, as illustrated in  FIG. 9C , the lens  20  is advanced into the reflective cavity  15  until it contacts the cured first quantity  14  of encapsulant material and the dispensed first quantity  14  of encapsulant material sufficient to establish a desired position for the lens  20  in the reflective cavity  15 . The dispensed second quantity  16  of encapsulant material is cured to attach the lens  20  in the reflective cavity  15  (Block  1340 ). 
     The flowcharts of  FIGS. 11-13  and the schematic illustrations of  FIGS. 8A-8C ,  9 A- 9 C and  10 A- 10 C illustrate the functionality and operation of possible implementations of methods for packaging a light emitting device according to some embodiments of the present invention. It should be noted that, in some alternative implementations, the acts noted in describing the figures may occur out of the order noted in the figures. For example, two blocks/operations shown in succession may, in fact, be executed substantially concurrently, or may be executed in the reverse order, depending upon the functionality involved. 
     As discussed above, different optical patterns (viewing angles, custom color spectrums, color temperature tuning and the like) may be provided by using multiple meniscus control techniques in combination with dispensing and/or curing variations in the process. For example, a high peaked dome of a phosphor loaded material may provide greater color spectrum uniformity of white temperature light emission with less shift to yellow towards the edges of the reflector cup by providing a more uniform length of the light path through the phosphor loaded material from the light emitting device. 
     Embodiments of the present invention provide one or more light emitting devices (i.e. chips) mounted in an optical cavity with a phosphor-loaded luminescent conversion layer formed in proximity to the light emitting device (i.e. adjacent or in a spaced relationship thereto). Conventional packaging technology teaches that the luminescent conversion layer should have a thickness variation less than or equal to ten percent (10%) of the average thickness of the luminescent conversion layer. However, such a requirement means that light emission from the optical cavity may travel substantially different path lengths through the luminescent conversion layer depending on the angle of emission, resulting in non-uniform wavelength conversion (and therefore non-uniform correlated color temperature or CCT) as a function of viewing angle. For example, light traveling in a direction normal to a luminescent conversion layer having a thickness t will travel through the luminescent conversion layer by a path length (PL) equal to t, the shortest possible path length. However, as shown schematically in  FIG. 14 , light emitted by a light emitting device  103  and passing through the luminescent conversion layer at an angle of incidence a has a path length equal to the thickness t divided by the cosine of the angle of incidence. Thus, for example, light passing through a luminescent conversion layer at an angle of incidence of 60° would travel through the layer by a path length that is twice the path length of light traveling in a normal direction.  FIG. 15  is a polar plot of an emission pattern showing substantial sidelobes at off-axis angles of emission that may result from a conventional glob-top type semiconductor light emitting device including a light emitting diode (LED). 
     The methods disclosed herein for meniscus control may be employed to form a shaped luminescent conversion region or element that may result in improved color uniformity. Improved color uniformity may be quantified, for example, by improved angular uniformity of correlated color temperature or reduced variation in CCT across all viewing angles. Alternatively, the improved uniformity is evidenced by near field optical measurements as a reduced spatial CCT variation across the emission surface of the LED. 
     In some embodiments, a phosphor-loaded luminescent conversion region or element is characterized by a non-uniform thickness that is greater in the middle of the optical cavity and smaller near the sidewalls of the optical cavity. In some embodiments, a phosphor-loaded luminescent conversion region or element is thickest at the center of the optical cavity and becomes thinner as it extends radially outward toward the edge of the luminescent conversion region. In some embodiments, the thickness variation of the phosphor-loaded luminescent conversion region is greater than 10% of the maximum thickness of the luminescent conversion region. In some embodiments, the luminescent conversion region or element is shaped in the form of a biconvex, plano-convex or concavo-convex region. In some embodiments, the luminescent conversion element comprises a pre-formed structure, such as a molded plastic phosphor-loaded piece part, that is inserted into the reflective cavity of the package. 
     Embodiments of the invention in which the phosphor-loaded region is shaped to provide improved color uniformity are shown in  FIGS. 16A-16C , which illustrate methods of packaging a light emitting device and resulting devices using the structural characteristics of a reflector cup for meniscus control. The operations illustrated in  FIGS. 16A-16C  utilize the reflector cup  4  illustrated in  FIGS. 5A-5B  and multiple curing operations similar to those previously described. As shown in  FIG. 16A , a first quantity  14  of encapsulant material is deposited in the reflective cavity  15  of the package  10 . In some embodiments of the present invention, the first quantity  14  may be dispensed using a separate (wetting) pre-dispense followed by another dispense. With proper control of the amount of encapsulant material dispensed, surface tension will cause the liquid encapsulant material  14  to cling to the lip  22 , forming a meniscus as illustrated in  FIG. 16A  at a height indicated at  14 A. The initial meniscus formed by encapsulant material  14  may be concave, convex or substantially flat as illustrated in  FIG. 16A . 
     The dispensed encapsulant material  14  is cured, for example, by heating, and may shrink down to a lower height indicated at  14 B. In the illustrated embodiment, the cured encapsulant material  14  shrinks down to form a concave surface  14 C, which in three dimensions may be substantially bowl-shaped (i.e. lowest in the center and sloping radially upwards). In some embodiments (in particular embodiments in which the first encapsulant material  14  is dispensed to form a concave surface prior to curing), the encapsulant material  14  may be pre-cured, i.e. exposed to a lower temperature or for shorter cure times, such that the encapsulant material does not completely solidify but rather merely forms a solid “skin” over its surface. The purpose of forming the skin is to prevent subsequently dispensed encapsulant material from intermixing with the first encapsulant material  14 . Subsequent encapsulant dispenses may contain wavelength conversion materials (such as phosphors) and, as discussed above, it may be desirable for the phosphor-loaded luminescent conversion region to retain a characteristic shape rather than becoming intermixed with the first encapsulant material  14 . Subjecting the first encapsulant layer  14  to a pre-cure instead of a full cure may speed the manufacturing process and may result in an improved interface between the first encapsulant material and subsequent encapsulant regions. 
     As shown in  FIG. 16B , a second quantity  16  of encapsulant material is then dispensed into the cavity  15  onto bowl-shaped surface  14 C. The second encapsulant material  16  includes a luminescent wavelength conversion material, such as a phosphor, in the illustrated embodiments. In some embodiments, the first encapsulant material  14  includes no luminescent wavelength conversion material. In other embodiments, the first encapsulant material  14  includes a lower concentration of luminescent wavelength conversion material than the second encapsulant material  16 . 
     In some embodiments, as illustrated in  FIG. 16B , the second encapsulant material  16  may also cling to the same edge of the lip  22  to form a convex meniscus. The second encapsulant material  16  is then cured (along with the first encapsulant material  14  if the first encapsulant material  14  was only pre-cured before the second encapsulant material  16  was dispensed). In some embodiments, the second encapsulant material  16  may also be pre-cured, i.e. exposed to a lower temperature or for shorter cure times, in order to prevent or reduce the risk of subsequently dispensed encapsulant material from intermixing with the second encapsulant material  16 . However, in other embodiments, the second encapsulant material  16  may be more fully cured in order to solidify the material before the lens  20  is inserted into the cavity  15 . As discussed below, once solidified, the second encapsulant material  16  may act as a mechanical stop to assist with correct placement of the lens  20 . 
     The resulting cured (or pre-cured) second encapsulant material  16  defines a luminescent conversion element  19  characterized by a non-uniform thickness that is greatest near the center of the optical cavity and that decreases radially towards the outer edge of the luminescent conversion element  19 . In the illustrated embodiment, the luminescent conversion element  19  is a bi-convex structure including a convex upper surface  19 A and a convex lower surface  19 B. 
     As mentioned above, while it is possible to form the luminescent conversion element  19  using the meniscus control methods described herein, in other embodiments, the luminescent conversion element  19  may be a pre-formed phosphor-loaded insert that is placed within the reflective cavity  15  of the package  10 . Such a structure may have some advantages for device performance and manufacturability. In particular, forming the luminescent conversion element  19  as a pre-formed insert may result in improved quality control as the pre-formed inserts may be individually tested before insertion. In addition, by forming the phosphor-loaded luminescent conversion element  19  as a pre-formed insert, liquid phosphor-loaded material does not have to be used in the final assembly process. This can provide benefits, as phosphor-loaded material can be abrasive and can interfere with the operation of automated machinery. Finally, a cure step may be avoided by forming the phosphor-loaded luminescent conversion element  19  as a pre-formed insert. 
     In further embodiments, a transparent, convex hemispherical mold (not shown) may be placed over first encapsulant  14  before or after it is cured in order to receive the second encapsulant  16 . Upon curing, the second encapsulant  16  will take the shape of the convex hemispherical mold, which may provide improved control over the final shape of the luminescent conversion element  19 . 
     After formation or insertion of the luminescent conversion element  19 , a quantity of a third encapsulant material  17  is dispensed within the cavity  15  as further illustrated in  FIG. 16B . The third encapsulant material  17  may be an optically transparent material, such as silicone or epoxy, with no luminescent conversion material or a low concentration of luminescent conversion material. Because the third encapsulant material  17  is dispensed following a cure or pre-cure step, the phosphor conversion material embedded in luminescent conversion element  19  may not substantially intermix with the third encapsulant material  17 . 
     In some embodiments, as illustrated in  FIG. 16B , the lip  22  may have an inner and outer edge thereon and the third quantity  17  of encapsulant material may cling to the outer edge of the lip  22 , forming a convex meniscus above luminescent conversion element  19 . Thus, the third encapsulant material  17  may also not contact or wick up the upper sidewall  5  to form a concave meniscus. 
     Referring to  FIG. 16C , the lens  20  is inserted into reflective cavity  15  and brought into contact with the uncured liquid third encapsulant material  17 . As such, the third encapsulant material  17  may be squeezed out from underneath the lens  20 . However, in some embodiments of the present invention, instead of squeezing out onto the exposed upper surfaces of the reflector cup and the lens (as shown in  FIG. 2 ), the excess of the third encapsulant material  17  is squeezed into and received by the moat  18 , thus limiting wicking of the encapsulant material  17  up the sidewall  5  even after the lens  20  is inserted and the convex meniscus of third encapsulant material  17  shown in  FIG. 16B  is displaced. The encapsulant material  17  is then cured to attach the lens  20  in the package  10  and to solidify the encapsulant material  17 . 
     In some embodiments, the lens  20  is advanced into the reflective cavity  15  until it contacts the luminescent conversion element  19  to establish a desired position for the lens  20  in the reflective cavity  15 . In other words, the luminescent conversion element  19  may act as a mechanical stop to assure correct placement of the lens  20 . In other embodiments, the lens  20  is advanced into the reflective cavity  15  until it contacts a lip formed in the cavity sufficient to establish a desired position for the lens  20  in the reflective cavity  15 , as illustrated in  FIG. 10C . 
     In some embodiments, the first encapsulant material  14  may include a scattering material embedded therein for scattering light passing therethrough, which may better improve angular uniformity of light emission. 
     In some embodiments, the first encapsulant material  14  may have a high index of refraction for better light extraction from the device  103 . If luminescent conversion element  19  has a different index of refraction from that of the first encapsulant material  14 , light rays passing through the interface between the two regions may be refracted, altering the light emission patterns of the device. If the index of refraction of the luminescent conversion element  19  is lower than that of first encapsulant material  14 , light rays will tend to be refracted away from the normal direction, which may result in a more pronounced path length. difference. The shape of luminescent conversion element  19  may be chosen or altered to offset such effects. For example, as discussed above, the luminescent conversion element  19  may be bi-convex, plano-convex or concavo-convex. 
     An example of forming a plano-convex luminescent conversion element using meniscus control techniques described herein is illustrated in  FIGS. 17A-17C . As shown therein, a quantity of first encapsulant material  14  is deposited in the reflective cavity  15  of the package  10 . With proper control of the amount of encapsulant material dispensed, surface tension will cause the liquid encapsulant material  14  to cling to the lip  22 , forming a convex meniscus as illustrated in  FIG. 17A  at a height indicated at  14 A. After curing, the first encapsulant material  14  relaxes to a height indicated at  14 B, forming an approximately flat surface  14 C. Second encapsulant material  16  is then dispensed, forming a convex meniscus that clings to an inner or outer edge of lip  22 . After curing, the second encapsulant material  16  forms a plano-convex luminescent conversion element  19  having a convex surface  19 A above a planar surface  19 B. The remaining manufacturing steps are generally the same as were described above in connection with  FIGS. 16A-16C . 
     Using similar techniques, the luminescent conversion element  19  may be formed as a plano-convex region with a planar region above a convex surface ( FIG. 18A ), a concavo-convex region with a convex surface above a concave surface ( FIG. 18B ) or a concavo-convex region with a concave surface above a convex surface ( FIG. 18C ). As discussed above, in each embodiment, the luminescent conversion element  19  includes a wavelength conversion material, such as a phosphor material. The first encapsulant material  14  and the third encapsulant material  17  may have no wavelength conversion material or a lower concentration of wavelength conversion material compared to the luminescent conversion element  19 . Although the embodiments of  FIGS. 16A-C ,  17 A-C and  18 A-C are illustrated in connection with a reflector cup  4  as illustrated in  FIGS. 5A-B , the techniques described above are applicable to other reflector cup designs, including reflector cups that include multiple moats and reflector cups that do not include a moat. 
     Embodiments of methods of packaging a semiconductor light emitting device  103  in a reflector  4  having a lower  6  and an upper  5  sidewall defining a reflective cavity  15  and incorporating a phosphor-loaded luminescent conversion element  19  with a non-uniform thickness will now be further described with reference to  FIG. 19 . As shown in the embodiments of  FIG. 19 , operations begin at Block  1900  by dispensing a first quantity  14  of encapsulant material into the reflective cavity  15  to form a first meniscus. The meniscus may have a convex, concave or substantially planar shape depending on the desired final shape of the luminescent conversion element  19 . The shape of the meniscus is determined by the physical dimensions of the reflector  4  and the quantity of encapsulant dispensed into the cavity. The first quantity  14  of encapsulant material is then cured or pre-cured (Block  1910 ). Next, Branch A of the flowchart of  FIG. 19  may be followed if it is desired to form the luminescent conversion element  19  using meniscus control methods. Branch B may be followed if it is desired to form luminescent conversion element  19  using a pre-formed insert. 
     Following Branch A, a second quantity  16  of encapsulant material containing a concentration of wavelength conversion material that is greater than that of first encapsulant material  14  is dispensed onto the cured first encapsulant material  14  (Block  1920 ). 
     The second encapsulant material  16  is then cured or pre-cured to form a luminescent conversion element  19  (Block  1930 ). 
     If Path B is followed, then a pre-formed luminescent conversion element  19  is inserted into the cavity  15  in contact with first encapsulant material  14  (Block  1950 ). In some embodiments, the step of curing the first quantity of encapsulant material may be performed after insertion of the pre-formed luminescent conversion element  19 . 
     After formation or insertion of luminescent conversion element  19  (Block  1930  or Block  1950 ), third encapsulant material  17  is dispensed within cavity  15  (Block  1960 ). In some embodiments of the present invention including a lens, the lens  20  is positioned in the reflective cavity  15  proximate the dispensed third quantity  17  of encapsulant material (Block  1970 ). Positioning the lens  20  may include collapsing a meniscus of third encapsulant material  17  and moving a portion of the third quantity  17  of encapsulant material into a moat  18 ,  24  with the lens  20  as illustrated in  FIGS. 9C ,  10 C,  16 C and  17 C. In addition, as illustrated in  FIG. 10C , the package may include a second lip  26 ′ having a height greater than that of the first lip  22 . The height of the second lip  26 ′ may be selected to provide a desired position for the lens  20  and the lens  20  may be moved into the reflective cavity  15  until it contacts the second lip  26 ′. In other embodiments of the present invention, as illustrated in  FIGS. 9C ,  16 C and  17 C, the lens  20  is advanced into the reflective cavity  15  until it contacts the luminescent conversion element  19  sufficient to establish a desired position for the lens  20  in the reflective cavity  15 . The dispensed third quantity  17  of encapsulant material is cured to attach the lens  20  in the reflective cavity  15  (Block  1980 ). 
     The flowchart of  FIG. 19  and the schematic illustrations of  FIGS. 16A-16C ,  17 A- 17 C and  18 A- 18 C illustrate the functionality and operation of possible implementations of methods for packaging a light emitting device according to some embodiments of the present invention. It should be noted that, in some alternative implementations, the acts noted in describing the figures may occur out of the order noted in the figures. For example, two blocks/operations shown in succession may, in fact, be executed substantially concurrently, or may be executed in the reverse order, depending upon the functionality involved. 
     Emission patterns for light emitting device packages will now be further discussed with reference to  FIGS. 20A ,  20 B and  21 .  FIG. 20A  is a polar plot of color-temperature for a glob-top light emitting diode (LED) emission pattern without a luminescent conversion element of the present invention generated using a goniometer.  FIG. 20B  is a polar plot of color-temperature for a light emitting diode (LED) emission pattern with a luminescent conversion element according to some embodiments of the present invention. A comparison of  FIG. 20B  to  FIG. 20A  shows an improvement in uniformity provided by the luminescent conversion region (i.e., the radius of the emission pattern is more uniform in  FIG. 20B ). As seen in  FIG. 20B , the packaged semiconductor light emitting device has a minimum color temperature (5.3 kK at about −85°) approximately 26 percent below a maximum color temperature (7.2 kK at about 0°) thereof over the measured 180 (+/−90 from normal or central axis)-degree range of emission angles. Various embodiments of the present invention may provide a minimum color temperature no more than 30 percent below a maximum color temperature for the semiconductor light emitting device package over a measured 180 (+/−90 from normal or central axis)-degree range of emission angles or over a measured 120 (+/−45 from normal or central axis)-degree range of emission angles. 
       FIGS. 21A and 21B  and  22 A and  22 B further illustrate improvement in color uniformity obtained according to some embodiments of the present invention. 
       FIGS. 21A and 21B  are digitally analyzed plots of the near field emission pattern of a first packaged device including a substrate/reflector assembly in which a Model C460XB900 light emitting diode manufactured by Cree, Inc. was mounted. 0.0030 cc Silicone (example: vendor e.g. Nye Synthetic Lubricants) mixed with 4% YAG doped with Ce Phosphor (example: from Philips) was pre-dispensed over the light emitting device, followed by a dispense of 0.0070 cc of the same encapsulant. Next, the dispensed encapsulant was cured for 60 minutes at a temperature of 70 C. A second quantity of 0.0050 cc of clear encapsulant material was then dispensed into the optical cavity and a lens was positioned in the optical cavity in contact with the second quantity of encapsulant. The second quantity of encapsulant was then cured for 60 minutes at a temperature of 70 C. The resulting structure was then energized and the near field emission pattern was recorded and analyzed. The emission pattern shows a total CCT variation of approximately 2000K over the measured 180 (+/−90 from normal or central axis)-degree range of emission angles. 
       FIGS. 22A and 22B  are digitally analyzed plots of the near field emission pattern of a second packaged device including a substrate/reflector assembly in which a C460XB900 light emitting diode manufactured by Cree, Inc. was mounted. 0.0020 cc of clear silicone (example: vendor e.g. Nye Synthetic Lubricants) was pre-dispensed over the light emitting device, followed by a first dispense of 0.0035 cc of the same encapsulant. The first encapsulant (including the pre-dispensed encapsulant) contained no wavelength conversion material. Next, the first encapsulant was cured for 60 minutes at a temperature of 70 C to form a concave meniscus. A second quantity of 0.0045 cc encapsulant material containing a wavelength conversion phosphor, namely 7% by weight of YAG doped with Ce Phosphor (example: from Philips) was then dispensed into concave meniscus formed by the first encapsulant. The second encapsulant was then cured for 60 minutes at a temperature of 70 C to form a luminescent conversion element having a thickness that was greatest at the center of the optical cavity and that decreased radially outward. A third quantity of 0.0050 cc encapsulant (which did not contain any wavelength conversion material) was then dispensed into the optical cavity and a lens was positioned in the optical cavity in contact with the third quantity of encapsulant. The third quantity of encapsulant was then cured for 60 minutes at a temperature of 70 C. The resulting structure was then energized and the near field emission pattern was recorded and analyzed. The emission pattern shows a total CCT variation of approximately 500K over the same range of emission angles. 
     In some embodiments of the present invention, a CCT variation of less than about 1000K is provided over a measured 180, 120 or 90 (centered on normal or central axis)-degree range of emission angles. In other embodiments of the present invention, a CCT variation of less than about 2000K is provided over a measured 180, 120 or 90 (centered on normal or central axis)-degree range of emission angles. In yet further embodiments of the present invention, a CCT variation of less than about 500K is provided over a measured 120 or 90 (centered on normal or central axis)-degree range of emission angles. It will be understood that the CCT variation referred to herein is based on a primary emission pattern of a device including primary optics processed with the device without the use of any additional secondary optics added to or used in combination with the packaged semiconductor light emitting device to improve color variation. Primary optics refers to the optics integral to the device, such as a luminescent conversion element in combination with a lens built into the device as described for various embodiments of the present invention herein. 
     The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although a few exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the claims. Therefore, it is to be understood that the foregoing is illustrative of the present invention and is not to be construed as limited to the specific embodiments disclosed, and that modifications to the disclosed embodiments, as well as other embodiments, are intended to be included within the scope of the appended claims. The invention is defined by the following claims, with equivalents of the claims to be included therein.