TWI342629B - Pyramidal photonic crystal light emitting device - Google Patents
Pyramidal photonic crystal light emitting device Download PDFInfo
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
- H01L33/20—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a particular shape, e.g. curved or truncated substrate
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2933/00—Details relating to devices covered by the group H01L33/00 but not provided for in its subgroups
- H01L2933/0083—Periodic patterns for optical field-shaping in or on the semiconductor body or semiconductor body package, e.g. photonic bandgap structures
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
- H01L33/10—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a light reflecting structure, e.g. semiconductor Bragg reflector
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/44—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the coatings, e.g. passivation layer or anti-reflective coating
- H01L33/46—Reflective coating, e.g. dielectric Bragg reflector
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Description
13426291342629
^ 九、發明說明: t發明所屬之技術領域3 發明領域 本發明有關於具有改良光汲出及方向性的發光二極 5 體,且特別是與應用光子晶體結構的裝置有關。 t先前技術3 發明背景IX. INSTRUCTIONS: TECHNICAL FIELD OF THE INVENTION The present invention relates to a light-emitting diode having improved light extraction and directivity, and in particular to a device employing a photonic crystal structure. t prior art 3 invention background
發光二極體(LEDs)的光以一個順向偏壓的p-n接面為 • 基礎且最近已充分到達高亮度而使其適合作為新的固態照 10 明應用以及替換投影器光源。透過高效率LEDs的經濟增 ' 益,連同其高可靠性,長使用壽命及環境利益而使其能進 入這些市場内。尤其,在固態照明的應用中要求LED超越 目前藉由可選擇之日光燈照明技術所達成的效率。 液晶顯示器(LCD)面板的背光單元(BLU)是一LCD面 .. 15 板之性能中的關鍵元件。現在,大多數的LCD面板使用小The light from the LEDs is based on a forward biased p-n junction and has recently reached high brightness to make it suitable for new solid-state applications and replacement of projector sources. The economic benefits of high-efficiency LEDs, along with their high reliability, longevity and environmental benefits, enable them to enter these markets. In particular, in solid-state lighting applications, LEDs are required to exceed the efficiency currently achieved with alternative fluorescent lighting technologies. The backlight unit (BLU) of a liquid crystal display (LCD) panel is a key component in the performance of an LCD panel. Now, most LCD panels use small
型陰極螢光燈(ccfl)光源。然而,這些光源因有一些問題而 ® 不理想,包括不佳的色域、環境回收和製造爭議、厚度和 、 輪廓、高電壓條件、不良熱管理、重量和高耗電量等。為 了要減少這些問題,LCD製造業者正在推行LED背光照明 20 單元。這些提議在許多領域皆能提供助益,包括色域、較 低的耗電量、輪廓薄,電壓需求低、良好熱管理及重量低。 現今的LED背光照明系統將LED分配於LED的背面 上,如同US7052152中所說明對於小顯示器而言這些通常 是低成本設計。然而,對於較大的LCD面板而言,例如大 5 於32吋,使光均勻地分配在LCD面板之背部所需要的LED 數目使此一途徑成本上不再具有經濟性。在US7052152中提 出124 LEDs應用作為一32吋LCD面板顯示器。 對於一些應用而言,一種更為各向同性或一 LED的朗 伯特光分配是被需要的且一種用來達成此一性質的技術是 粗化光通過而結合的表面。一特定程度的粗糙度視LED之 製作程序而定可為固有者。然而,藉由利用諸如蝕刻技術, 一控制程度的表面粗糙可被達成以改進由LED發出之光的 不規則性以及均匀性。 US2006/0181899和 US2006/0181903揭露一安排成使光 平均地分散在完整的LCD面板表面上的光學導光板或波 導。藉由使用側懸掛式LED光源光被耦合至導光板中。當 與直接LED背光照明相較下,側懸掛式因每單位面積之背 光LCD中所需之LEDs數目顯著減少而為有利者。已有32〇才 LCD面板可利用少至〗2個LED光源照明的建議。然而使漫 射在LCD面板上的光最大化則需要將LED光最佳耦合至導 光板中。 高亮度LEDs應用上的另一應用領域是前投式和背投 式投影機的光引擎°低效率和短壽命一直是習知高強度放 電(HID)型投影機光引擎的障礙,以致其被消費市場採用受 到延滯。在本申印案中光源的集光率值需要小於或與微型 顯不器集光率值相配。此一互適性對於改進完整光投射引 擎之整體系統效率非常重要。此外,總發錄出高及耗電 量低亦非常重要,尤其在大的f投式躲(大於对)及前投 工系統之應用中此為被需要者。為使熱控制題減至 =需要低耗電量。來自具有小集光率數值的紅色、綠 和藍色的單—顏色LED光源被多路傳輸以在投影系統中 生所需要的顏色。此可免除色環及相_外成本的需 求°集光率數值£可依照下列的方程式計算: £ =…心、Sin(a) (1) β式中E疋光源的集光率,a是發光裝置的表面積,且。 是光源半角。因此,可瞭解到對於投射應用而言,發光源 的準直程度是-項_因素且減少光源之半角能顯著地改 善光引擎的整體效率。 LED的整體效率可藉由三個主要因素定量即内量子 效率、注人效率、以及歧出料。減少由-LED之光及 出效率的主要限制因素之-是發出光子的全内反射及它們 被捕陷在形成LED的高折射率材料巾。這些被捕陷的波導 模態傳佈在LED的結構中直至它們被散射或再吸收為止。 LED結構的厚度決定可被支持的模態數目。 US5779924和US5955749兩者皆描述使用定義在led 之半導體層中的光子晶體結構影響光傳佈通過淺表構造。 所形成的光子帶結構容使捕陷模態被汲出且因而增加=沒 出效率且最終增加LED的總外部效率。在一 LED^使用光 子晶體結構比其他光汲出技術有利的原因在於它們隨著 LED的有效表面積縮放大小,因而提供—種改進_大面積 高亮度LED結構之光沒出的理想方法。LED大小的縮放比 例對於需要絕對發光輸出的固態發光應用十分重 然 而,許多這些光子晶體LEDs的總光汲出不及更傳統的表面 粗化LED高。 US6831302和US2005/0285132描述利用以鎵氮化物 (GaN)為基礎的材料製作具有光子晶體結構之發光二極體 的方法。在兩案的例子中處理上皆包含最後會影響LED晶 圓產量與成本的許多複雜而昂貴的步驟。尤其,US683I302 描述一包括下列步驟的製作方法:在一匹配單晶晶圓的晶 格上生長一η-GaN層,一有效QW區域和一p-GaN層,接著 在頂端表面上共熔鍵合一底層封裝或封裝載板、晶圓覆晶 封裝、生長晶圓剝離(利用一諸如雷射剝離之技術)、表面拋 光以提供一光學平滑的表面(使用一諸如化學機械拋光之 程序),在該表面上界定一光子晶體(藉由一諸如奈米壓印, 微影,或雷射攝影術),且最後使光子晶體利用GaN之一適 當的乾(例如RIE或ICP)或濕蝕刻轉移至GaN材料。 所牵涉之複雜處理步驟之一是晶圓的抛光,由於在控 制跨越整個晶圓表面品質上的困難,該步驟會對生產量有 不利的影響。佈於全表面上的小擦傷可能影響傳佈於led 晶圓上之電流且最終造成一使整個LED短路的路徑,或對 正向電壓有不不良影響。另外,GaN淺表結構的厚度對光 子晶體的光汲出圖形的有效設計很重要。高折射率作用成 -高度多模態波導,因而厚度決定了咖異質結構存在的 模態數目。因使用一拋光程序而造成辦LED結構絕對厚度 的不良控制,最終影響由一處理批次到另一處理批a的 LED晶圓整體輸出。 另一個複雜的製作步驟是界定300nm至500nm範圍間 的小規模—階光子晶體的特徵間距,以及200nm至400nm的 孔直特徵。此種圖形目前利用奈米壓印或雷射攝影術定 義。別者目前對於在LED晶圓上之此一小型特徵尚非一種 成热的技術且僅可達成低生產量。除此之外,該技術的缺 失為小製造量需要較高的成本。後者的微影技術缺失在於 複雜的對準及穩定性以及低產量。 因此對—種新型態的具表面圖形LED有所需求,該 LED表現得比習知表面粗化或光子晶體LED裝置更佳且可 依-簡單和具有成本效益的方法被製作。 【菊明内容】 發明概要 依據本發明的第一層面,一個發光裝置(led)包含: 一第一層,包含—具有第一型攙雜之第一半導體材料; 一第二層,包含一具有第二型攙雜的第二半導體材 料;以及 一配置在第一層與第二層之間的光產生層, 其中该第一層具有一遠離光產生層的上表面及一接近 光產生層的下表面,且其中在光產生層中所產生的光由 led結構經由第—層的上表面出現該第_層進—步包含 第-半導體材料馳成的角錐型絲錐型上表面突出部蓋 瓦配置’該突出部由—與第—半導體材料之折射率不同的 材:所圍繞’其中突出部之蓋瓦配置與周圍材料構成—光 子^。構I其中4突出部及其蓋瓦配置的安排使得由 1342629 LED結構形成通過上表面之光實質上比得自一朗伯特源光 源的光更具有方向性。 依據本發明的第二層面,一發光裝置(LED)包括: 一第一層,包含一具有一第一型攙雜的第一半導體材 5 料; 一第二層,包含一具有一第二型攙雜的一第二半導體 材料;以及,Type cathode fluorescent lamp (ccfl) light source. However, these sources are not ideal due to some problems, including poor color gamut, environmental recycling and manufacturing controversy, thickness and profile, high voltage conditions, poor thermal management, weight and high power consumption. In order to reduce these problems, LCD manufacturers are implementing LED backlighting unit 20. These proposals can be helpful in many areas, including color gamut, lower power consumption, thin profile, low voltage requirements, good thermal management, and low weight. Today's LED backlighting systems distribute LEDs on the back side of the LEDs, which are typically low cost designs for small displays as described in US7052152. However, for larger LCD panels, for example, larger than 32 吋, the number of LEDs required to evenly distribute light across the back of the LCD panel makes this approach no longer cost effective. The 124 LEDs application is presented in US7052152 as a 32" LCD panel display. For some applications, a more isotropic or LED-LAMP light distribution is needed and one technique used to achieve this property is to roughen the surface through which light passes. A certain degree of roughness may be inherent to the LED fabrication process. However, by utilizing, for example, etching techniques, a controlled degree of surface roughness can be achieved to improve the irregularity and uniformity of the light emitted by the LED. US 2006/0181899 and US 2006/0181903 disclose an optical light guide or waveguide arranged to evenly distribute light over the surface of a complete LCD panel. Light is coupled into the light guide by using a side-mounted LED source. When compared to direct LED backlighting, side suspension is advantageous because the number of LEDs required per unit area of the backlight LCD is significantly reduced. There are 32 LCD LCD panels that can be used with as little as 2 LED light source illumination recommendations. However, maximizing the light diffused across the LCD panel requires optimal coupling of the LED light into the light guide. Another application area for high-brightness LEDs is the light engine of front-projection and rear-projection projectors. Low efficiency and short life have always been obstacles to the conventional high-intensity discharge (HID) projector light engine, so that it is Consumer market adoption has been delayed. In this application, the etendue value of the source needs to be less than or match the micro-emitter etendue value. This interoperability is important to improve the overall system efficiency of a complete light projection engine. In addition, the high total output and low power consumption are also very important, especially in large f-type (more than) and pre-commissioning systems. To reduce the thermal control problem to = need low power consumption. Red-green and blue single-color LED sources from small etendue values are multiplexed to produce the desired color in the projection system. This eliminates the need for color circles and phase-outside costs. The etendue value can be calculated according to the following equation: £ =...heart, Sin(a) (1) The etendue of the E-source in the β-form, a is The surface area of the illuminating device, and. It is the half angle of the light source. Thus, it can be appreciated that for projection applications, the degree of collimation of the illumination source is a - factor and reducing the half angle of the source can significantly improve the overall efficiency of the light engine. The overall efficiency of an LED can be quantified by three main factors: internal quantum efficiency, injection efficiency, and disproportionation. The main limiting factor in reducing the light and efficiency of the -LED is the total internal reflection of the emitted photons and their trapping of the high refractive index material sheet forming the LED. These trapped waveguide modes are propagated throughout the structure of the LED until they are scattered or reabsorbed. The thickness of the LED structure determines the number of modes that can be supported. Both US5779924 and US5955749 describe the use of a photonic crystal structure defined in a semiconductor layer of a LED to affect the propagation of light through a superficial configuration. The resulting photonic band structure allows the trapping mode to be scooped out and thus increased = no efficiency and ultimately increases the overall external efficiency of the LED. The reason why the use of photonic crystal structures in an LED is advantageous over other optical extraction techniques is that they scale with the effective surface area of the LEDs, thus providing an ideal way to improve the large-area high-brightness LED structure. The scaling of the LED size is critical for solid-state lighting applications that require absolute illumination output, and the total light output of many of these photonic crystal LEDs is not as high as the more conventional surface roughening LEDs. US6831302 and US2005/0285132 describe a method of fabricating a light-emitting diode having a photonic crystal structure using a gallium nitride (GaN)-based material. In both cases, the processing involves many complex and expensive steps that ultimately affect the LED wafer yield and cost. In particular, US683I302 describes a method of fabricating an η-GaN layer, an effective QW region and a p-GaN layer on a lattice of a matched single crystal wafer, followed by eutectic bonding on the top surface. An underlying package or package carrier, wafer flip chip, growth wafer stripping (using a technique such as laser stripping), surface polishing to provide an optically smooth surface (using a procedure such as chemical mechanical polishing), The surface defines a photonic crystal (by a method such as nanoimprinting, lithography, or laser photography), and finally the photonic crystal is transferred to a suitable dry (eg, RIE or ICP) or wet etch of GaN to GaN material. One of the complex processing steps involved is the polishing of the wafer, which has a detrimental effect on throughput due to difficulties in controlling the quality across the entire wafer surface. Small scratches on the full surface can affect the current spreading on the led wafer and ultimately cause a path that shorts the entire LED or has no adverse effect on the forward voltage. In addition, the thickness of the GaN superficial structure is important for the effective design of the photo-extraction pattern of the photonic crystal. The high refractive index acts as a highly multimodal waveguide, and thus the thickness determines the number of modes present in the heterogeneous structure. The poor control of the absolute thickness of the LED structure due to the use of a polishing process ultimately affects the overall output of the LED wafer from one process batch to another. Another complex fabrication step is to define the feature spacing of small-scale photonic crystals ranging from 300 nm to 500 nm, and the hole-straight features from 200 nm to 400 nm. Such graphics are currently defined using nanoimprint or laser photography. Other small features on LED wafers are not yet a hot technology and can only achieve low throughput. In addition to this, the lack of this technology requires a relatively high cost for small manufacturing volumes. The latter's lithography technology is missing due to complex alignment and stability and low throughput. There is therefore a need for a new type of surface patterned LED that behaves better than conventional surface roughening or photonic crystal LED devices and can be fabricated in a simple and cost effective manner. [Jiume Content] SUMMARY OF THE INVENTION In accordance with a first aspect of the present invention, a light emitting device (LED) includes: a first layer comprising: a first semiconductor material having a first type of doping; a second layer comprising a a second type doped second semiconductor material; and a light generating layer disposed between the first layer and the second layer, wherein the first layer has an upper surface away from the light generating layer and a lower surface adjacent to the light generating layer And wherein the light generated in the light generating layer is formed by the LED structure via the upper surface of the first layer, and the first layer further comprises a pyramidal taper type upper surface protrusion tile arrangement of the first semiconductor material. The protrusion is made of a material different from the refractive index of the first semiconductor material: the tiling arrangement around which the protrusion is formed and the surrounding material constitutes a photon. The arrangement of the four projections and their tile configurations is such that the light formed by the 1342629 LED structure through the upper surface is substantially more directional than the light from a Lambertian source. According to a second aspect of the present invention, a light emitting device (LED) includes: a first layer comprising a first semiconductor material having a first type doping; a second layer comprising a second type doped a second semiconductor material; and,
一配置在第一層與第二層之間的光產生層,其中第一 ^ 層有一遠離光產生層之上表面及一接近該光產生層的下表 10 面,且其中在光產生層中所產生的光通過第一層的上表面 由LED構造的出現,該第一層進一步包含一在第一半導體 材料中由上表面朝向光產生層延伸,且由一折射率與第一 半導體材料不同之材料所組成之倒角錐型或倒截錐型凹痕 蓋瓦配置,其中該凹痕的蓋瓦配置及周圍第一半導體材料 . 15 包含一光子帶結構,且其中該凹痕及其蓋瓦配置的安排使a light generating layer disposed between the first layer and the second layer, wherein the first layer has a surface away from the upper surface of the light generating layer and a surface 10 close to the light generating layer, and wherein the light generating layer is in the light generating layer The generated light is formed by an LED structure through the upper surface of the first layer, the first layer further comprising a first semiconductor material extending from the upper surface toward the light generating layer and having a refractive index different from that of the first semiconductor material a chamfered or inverted truncated dent tiling arrangement comprising a material, wherein the tiling of the dent and the surrounding first semiconductor material. 15 comprises a photonic band structure, and wherein the dent and its tiling Configuration arrangement
得透過該上表面從LED的結構出現的光比得自一朗伯特光 ® 源、者更具有方向性。 一朗伯特光源在任一方向每單位立體角之光通量與該 一方向與其所由之發射的表面法線之間所成角度的餘弦成 20 比例。此導致球形分配的均一發光。一 LED包括一依據本 發明之結構,該結構結合更大方向性的發光以及由裝置所 產生之光耦合至發射光束之效率上的改進。此可透過角錐 型或截錐型表面突出部,或倒角錐型或倒截錐型凹痕的新 穎蓋瓦配置被達成角錐型。 10 有二種較佳的光子蓋即短程與長程有序光子 晶體,短程無序但長程有序準光子晶體,短程間隔有序但 長程無序無定形蓋瓦模式。在無定形的情況下 ,鄰接角錐 狀區域被固定而旋轉對稱性隨機化。 本發明中所提出的—高階角錐狀或倒角錐狀光子晶體 =準晶體模式當與較為習知的—階光子晶體模式比較時可 提供增加的纽出。光子晶體的精C設計也允許定制由裝 置所產生之遂場光。詳言之,具有一角度之側壁之突出部 的角錐形狀或凹痕_角錐形狀,以及它們的界定明確蓋 瓦配置能從LED汲出一比從朗伯特光源更為準直的光束, 甚至在具有大晶格常數(>1μηι)的模式下亦如此。 較佳地’角錐型突出部或倒角錐型的凹痕具有一大於 ΐΟμηι的尺寸。,然而,他們的尺寸可大於i 5叫或2 〇叫或 甚至於大於2·5μπι。相對上較大的角錐體或倒角錐體尺寸釋 出製作上的容差且亦意表在角錐型突出部或倒角錐型壓形 成之别不需要作表面拋光’因它們的尺寸充分大於殘餘的 表面粗度。 此外,更佳者是蓋瓦配置的間距尺寸上大於1祚〇1或 2.5μηι甚至於大於3.〇。 對於許多應用而言,突出部或凹痕最好配置成使得一 顯著比例(>35%)的光在一對垂直轴具有一3〇。半角的中央 圓錐中被汲出。最好是大於37〇/〇、38%或甚至於40%從中央 圓錐中被汲出。此能使光有效且均一地耦合至狹長的光導 中而忒光導通常與光源一起被使用在投射應用場合。 1342629 v 或者,角錐體或倒角錐體以及蓋瓦圖形可配置成使得 光主要以一比此為大的角度以一種側邊發光型式被沒出。 例如,光可以一被瞄準之環或像油炸圈餅一樣的分配圍繞 垂直軸被發出。在此一情況下,分配的中心可與垂直轴成 • 5 一大於或等於30。、40。、50。或60。之角度,或相等地與表面 相等地成一小於或等於60。、50。、40。或30。的角度。The light that emerges from the structure of the LED through the upper surface is more directional than that obtained from a Lambert light source. The luminous flux per unit solid angle of a Lambertian source in either direction is 20 proportional to the cosine of the angle between the direction and the surface normal emitted by it. This results in a uniform illumination of the spherical distribution. An LED includes a structure in accordance with the present invention that combines greater directional illumination and an improvement in the efficiency of coupling of light generated by the device to the emitted beam. This can be achieved by a pyramidal or truncated cone shaped surface projection, or a chamfered or inverted truncated dent in a new tiling configuration. 10 There are two preferred photonic caps, short-range and long-range ordered photonic crystals, short-range disordered but long-range ordered quasi-photonic crystals, short-range interval ordered but long-range disordered amorphous gable modes. In the case of amorphous, the adjacent pyramidal regions are fixed and the rotational symmetry is randomized. The high order pyramidal or chamfered cone photonic crystal proposed in the present invention = quasi-crystal mode provides an increased click when compared to the more conventional - order photonic crystal mode. The fine C design of the photonic crystal also allows customization of the field light produced by the device. In particular, the pyramid shape or the dent-corner shape of the protrusions of the side walls of an angle, and their definitively defined tiling arrangement, can extract a more collimated beam from the LED than from the Lambertian source, even in The same is true in the mode with a large lattice constant (>1μηι). Preferably, the 'tapered-shaped projection or the chamfered-cone shaped dimple has a size greater than ΐΟμηι. However, their size can be greater than i 5 or 2 squeak or even greater than 2·5μπι. The relatively large pyramid or chamfer cone size releases the tolerances produced and is also intended to be surface polished in the form of pyramidal or chamfered cones 'because their dimensions are sufficiently larger than the residual surface roughness. In addition, it is better that the spacing of the tiling configuration is greater than 1祚〇1 or 2.5μηι or even greater than 3.〇. For many applications, the projections or indentations are preferably configured such that a significant proportion (> 35%) of the light has a 3 〇 on a pair of vertical axes. The central cone of the half-angle is pulled out. It is preferably greater than 37 〇 / 〇, 38% or even 40% from the central cone. This enables light to be efficiently and uniformly coupled into the elongated light guide and the light guide is typically used with the light source in projection applications. 1342629 v Alternatively, the pyramid or chamfer cone and the tile pattern can be configured such that light is predominantly out of a side illumination pattern at a greater angle. For example, light can be emitted around a vertical axis as a ring of aiming or dispensing like a doughnut. In this case, the center of the distribution can be greater than or equal to 30 with the vertical axis. 40. 50. Or 60. The angle, or equal to the surface, is equal to or less than 60. 50. 40. Or 30. Angle.
具有第一型攙雜的第一半導體材料可以是η型攙雜或p 型攙雜,該一情況下具有第二型攙雜之第二半導體材料將 # 被Ρ型攙雜或η型攙雜。 10 第一層可包含一層埋入第一半導體材料中之一預定深 度的蝕刻停止材料,該一情況下由第一半導體材料所形成 的突出部可從钮刻停止材料之一表面延伸且倒錐狀凹痕將 一直延伸至姓刻停止材料層。 在一特別的較佳實施例中’第一半導體材料包含η型攙 - 15雜GaN或InGaN且第二半導體材料包含ρ型攙雜之GaN或The first semiconductor material having the first type of doping may be an n-type doped or p-type doped, in which case the second semiconductor material having the second type doping is #Ρ-type doped or n-type doped. The first layer may comprise a layer of etch stop material buried in the first semiconductor material at a predetermined depth, in which case the protrusion formed by the first semiconductor material may extend from the surface of one of the button stop materials and the inverted cone The indentations will extend until the last stop material layer. In a particularly preferred embodiment, the first semiconductor material comprises n-type germanium - 15 hetero-GaN or InGaN and the second semiconductor material comprises p-type doped GaN or
InGaN。最好光產生層包括一 GaN-InGaN之多重量子井構 ® 造。從角錐體的直徑方面而言,較高階的光子晶體尺寸典 型地在Ι.Ομηι至3.0μηι範圍内,惟此係依一範圍之因素而 , 定,包括波長,遠場圖形、LED厚度以及整體GaN異質結構 20内的多重量子井構造。適當的蝕刻停止材料包括AlGaN和 InGaN 〇 為了更進一步提高光汲出’ led最好進一步包含一光 學反射器以反射傳遞自第一層上汲出表面的光,否則該光 不會被汲出。光學反射器設置於鄰近第二半導體材料的第 12 1342629 二層以使得第二層位於光產生層和反射器之間。 較適宜地,光學反射器包括一金屬材料單一層,或其 可包含一多層電介質結構。可供選擇地,光學反射器可能 包含一分佈式布拉格反射器(DBR)或一全方向反射器 5 (ODR)。 較適宜地,光產生層和光學反射器之間的分隔距離是 ' 構成一可提高朝向第一層之上光汲出表面傳播之生成光量InGaN. Preferably, the light generating layer comprises a multi-quantum well structure of GaN-InGaN. From the aspect of the diameter of the pyramid, the higher order photonic crystal size is typically in the range of Ι.Ομηι to 3.0μηι, but it depends on a range of factors, including wavelength, far field pattern, LED thickness and overall Multiple quantum well structures within the GaN heterostructure 20. Suitable etch stop materials include AlGaN and InGaN 〇 In order to further enhance the light exit, the LED preferably further includes an optical reflector to reflect light transmitted from the surface of the first layer, otherwise the light will not be ejected. The optical reflector is disposed adjacent to the second layer of the first semiconductor material 12 1342629 such that the second layer is between the light generating layer and the reflector. Preferably, the optical reflector comprises a single layer of metallic material or it may comprise a multilayer dielectric structure. Alternatively, the optical reflector may comprise a distributed Bragg reflector (DBR) or an omnidirectional reflector 5 (ODR). Preferably, the separation distance between the light generating layer and the optical reflector is 'constituting an amount of light that can be generated to propagate toward the light exiting surface of the first layer.
的微腔。此微腔效應在光汲出效率上甚至提供一超越光學 • 反射器之單純反射的更大光汲出效率提升。一最佳的分隔 10 是光產生層之波長的〇.5-0.7倍之間。當一微腔存在時,最 好角錐型突出部或倒角錐型凹痕以及其蓋瓦配置被組配成 能夠與微腔效應有最佳的配合作用以進一步提高光由LED 汲出的效率。 依照本發明的第三層面,一光學投影儀單元的光引擎 _ 15 包括多數依據第一或第二層面的發光裝置。上述之LED特 別適合用來應用在固態照明光源中,包括前後投影儀。Microcavity. This microcavity effect provides even greater light extraction efficiency over the optical reflection of the reflector in the light extraction efficiency. An optimum separation 10 is between 55 and 0.7 times the wavelength of the light generating layer. When a microcavity is present, the best pyramidal or chamfered indentation and its tiling arrangement are combined to provide optimal coordination with the microcavity effect to further increase the efficiency of light exiting from the LED. In accordance with a third aspect of the invention, the light engine -15 of an optical projector unit includes a plurality of illumination devices in accordance with the first or second level. The LEDs described above are particularly suitable for use in solid state lighting sources, including front and rear projectors.
® 依照本發明的第四層面,一種根據第一層面製作一發 光裝置(LED)的方法包含的步驟是: 提供一發光裝置異質結構,包括一包含有一具有一第 20 一型摻雜之第一半導體材料的第一層,一包含有一具有第 二型摻雜之第二半導體的第二層,以及一設置在該第一與 第二層之間的光產生層,其中該第一層具有一遠離光產生 層的上表面與一接近光產生層的下表面,且其中在光產生 層中所產生的光透過第一層的上表面由LED結構顯現, 13 1342629 ι· 在第一層上形成一姓刻光罩,該光罩包含光罩材料島 塊,該島塊位於一對應一預定蓋瓦配置的位置,其中形成 光罩的步驟包含之數個步驟為: 沈積一層光阻劑在該第一層上; 5 依據預定的蓋瓦配置藉由曝光形成光阻劑圖形;以及, 除去未曝光的光阻劑而在對應於預定蓋瓦配置的位置 4 留下光阻劑之島塊;In accordance with a fourth aspect of the present invention, a method of fabricating a light emitting device (LED) according to a first level includes the steps of: providing a light emitting device heterostructure comprising: a first comprising a 20th type doping a first layer of semiconductor material, a second layer comprising a second semiconductor doped with a second type, and a light generating layer disposed between the first and second layers, wherein the first layer has a Moving away from the upper surface of the light generating layer and a lower surface close to the light generating layer, and wherein the light generated in the light generating layer passes through the upper surface of the first layer is visualized by the LED structure, 13 1342629 ι· is formed on the first layer a mask engraved, the reticle comprising a glazing material island block, the island block being located at a position corresponding to a predetermined tiling arrangement, wherein the step of forming the reticle comprises a plurality of steps of: depositing a layer of photoresist On the first layer; 5 forming a photoresist pattern by exposure according to a predetermined tiling configuration; and removing the unexposed photoresist to leave an island block of the photoresist at a position 4 corresponding to the predetermined tiling configuration;
在第一層中沿預定晶體平面藉由等向性濕蝕刻第一半 • 導體材料至一預定深度在光罩材料之島塊下的位置形成 10 第一半導體材料的角錐型或載錐型突出部;以及, 除去光罩材料之島塊以留下預定的角錐型或截錐型突 出部蓋瓦配置,該突出部與一不同折射率之周圍材料相組 合以構成一光子帶結構。 依照本發明的第五層面,一種製作一依據第二層面之 „ 15 一發光裝置(LED)的方法包括之步驟為:Forming 10 a pyramidal or cone-shaped protrusion of the first semiconductor material by isotropically wet etching the first half of the conductor material along a predetermined crystal plane to a predetermined depth below the island block of the reticle material along the predetermined crystal plane And removing the island block of the reticle material to leave a predetermined pyramid or truncated pyramid tiling arrangement that combines with a surrounding material of a different refractive index to form a photonic band structure. In accordance with a fifth aspect of the present invention, a method of fabricating a method according to a second level of a light emitting device (LED) includes the steps of:
提供一發光裝置異質結構,該異質結構包括一包含 ^ 具有第一型攙雜的第一半導體材料之第一層,一包含具 有第二型攙雜的第二半導體材料之第二層以及一排列在 該第一與第二層間之光產生層,其中該第一層具有一遠 20 離光產生層之上表面與一鄰近該光產生層的下表面且其 中在該光產生層所產生之光通過該第一層之上表面從 LED構造顯現, 在第一層上形成一钱刻光罩,該光罩包括位置對應 於一預定蓋瓦配置之缺失光罩材料,其中形成光罩的步 14 1342629 驟包含: 依據預定蓋瓦配置藉由曝光形成光阻劑圖形;以及, 除去未曝光的光阻劑以在對應於預定蓋瓦配置之位 置留下缺失光阻劑島塊; 5 藉由沿預定晶體平面以等向性濕蝕刻該第一半導體Providing a light emitting device heterostructure comprising a first layer comprising a first semiconductor material having a first type doping, a second layer comprising a second semiconductor material having a second type doping, and an array disposed thereon a light generating layer between the first layer and the second layer, wherein the first layer has a far surface 20 from an upper surface of the light generating layer and a lower surface adjacent to the light generating layer, and wherein light generated in the light generating layer passes through the light The upper surface of the first layer emerges from the LED structure, forming a reticle on the first layer, the reticle including a missing reticle material corresponding to a predetermined tiling configuration, wherein step 14 1342629 of forming the reticle The method comprises: forming a photoresist pattern by exposure according to a predetermined tiling configuration; and removing the unexposed photoresist to leave a missing photoresist island at a position corresponding to the predetermined tiling configuration; 5 by following a predetermined crystal Etching the first semiconductor with isotropic wetness
材料至一預定深度,以在第一半導體第一層中缺失光罩 材料之島塊下方位置形成角錐型或截錐型凹痕;以及, 除去剩餘的光罩材料而在第一半導體材料中留下倒 • 角錐型或倒截錐型之凹痕的預定蓋瓦配置,該凹痕包括 10 —周圍之第一半導體材料折射率不同的材料且一起構 成一光子帶結構。 發光裝置異質結構本身可藉任何適當的習知程序製 作,包括覆晶封裝程序。 光阻劑層可能本身能是光罩層,此一情況下光罩材料 . 15 之島塊為光阻劑之島塊。藉由曝光形成光阻劑圖形的任何Materialing to a predetermined depth to form a pyramidal or truncated cone indentation below the island block in which the reticle material is missing in the first layer of the first semiconductor; and removing the remaining reticle material to remain in the first semiconductor material A predetermined tiling arrangement of a pyramid or truncated cone shaped dimple comprising 10 - a material having a different refractive index of the surrounding first semiconductor material and together forming a photonic band structure. The illuminating device heterostructure itself can be fabricated by any suitable conventional procedure, including flip chip packaging procedures. The photoresist layer may itself be a photomask layer, in which case the island material of the photomask material is an island of photoresist. Any of the photoresist patterns formed by exposure
適當程序皆可被利用,包括紫外線微影。未曝光的光阻劑 ^ 使用一適當的顯影劑除去且餘留的未曝光光阻劑島塊藉由 剝離去除。有多種不同的蝕刻劑可用來作等向性的濕蝕 刻,包括KOH、NaOH或H3P04的溶液。 20 可選擇地,一較硬的光罩材料可被使用,該光罩材料 對於等向性的濕蝕刻具有抗蝕刻性。因此需要更進一步的 程序步驟。 在第四層面的方法中,形成一蝕刻光罩的步驟最好進 一步包含以下步驟: 15 在沈積光阻劑層的步驟前於第一層上沈積一層硬光罩 材料; 在除去光阻劑的步驟之後除去硬光罩材料以在光阻劑 之島塊下面留下硬光罩材料島塊;以及, 除去光阻劑的剩餘島塊留下蝕刻光罩,蝕刻光罩構成 對應於預定蓋瓦配置之位置的硬光罩材料島塊。 在第五層面的方法中,形成一蝕刻光罩的步驟最好進 一步包含以下步驟: 在沈積光阻劑層之步驟前在第一層上沈積一層硬光罩 材料, 在除去光阻劑的步驟之後除去硬光罩材料以在光限劑 之島塊下面留下缺失硬光罩材料之島塊;以及, 除去剩餘光阻劑以留下蝕刻光罩,蝕刻光罩構成對應 於預定蓋瓦配置之位置的缺失硬光罩材料島塊。 適當的硬光罩材料包括藉PECVD沈積之Si02或Si3N4 或者藉由淹錄或蒸錢沈積的一金屬。一旦角錐型突出部已 經形成,硬光罩材料的剩餘島塊藉由一適當的濕或乾蝕刻 程序除去。同樣地,一旦倒角錐型凹痕已被形成,圍繞島 塊的剩餘硬光罩材料藉一適當的濕或乾蝕刻程序除去。 在第四層面的方法中,等向性蝕刻的深度將決定是截 錐型抑或是角錐型突出部被形成以及其尺寸。然而,如果 根據蝕刻速度與蝕刻時間,則等向性蝕刻深度的精確控制 可能很困難。因此,一蝕刻停止層可被用來確保蝕刻在一 特定深度被終止。同樣地,如果以在第五層面的方法中, 1342629 等向性的深度_將妓形成凹㈣尺寸。 時間為依據,等向性的精確控祕刻深度== 月匕會有困難。此外’需要㈣停止層以便形成倒截雜型凹 較佳地’發光骏置異質結構的第一層包含—層埋入第 —半導體材料中之預㈣深度的關停止材料。第一半導 體材料之等向性蝕刻接著將繼續直到抵達蝕刻停止材料層 為止’如此提供製作方法的較高均勻性與可重覆性。在第 五層面的方法中’倒平頭或載錐型凹痕允許被形成。 〗因此纟發明也提供—光子晶體型態LED結構的簡化 製&方法藉由利用低成本光微影技術或類似程序使-大 型特徵光子晶趙定義被轉移至—咖上^需要複雜的拋 光程序。 圖式簡單說明 15 本發明之實例現在料細地參照圖式說明其中: 第1圖表示發明所提出之裝置的-橫 第2A圖表示以—規則正方晶格排列的角錐體; 第2B圖表不以—丨2次對稱性準晶體排列的角錐體; 20Appropriate procedures can be utilized, including UV lithography. The unexposed photoresist is removed using a suitable developer and the remaining unexposed photoresist islands are removed by lift-off. A variety of different etchants are available for isotropic wet etching, including solutions of KOH, NaOH or H3P04. Alternatively, a harder reticle material can be used which is etch resistant to isotropic wet etching. Therefore, further procedural steps are required. In the method of the fourth aspect, the step of forming an etch mask preferably further comprises the steps of: 15 depositing a hard mask material on the first layer before the step of depositing the photoresist layer; removing the photoresist After the step, the hard mask material is removed to leave a hard mask material island under the island of the photoresist; and the remaining island block of the photoresist is left to leave an etching mask, and the etching mask is formed to correspond to the predetermined tile A hard mask material island block in the configuration location. In the method of the fifth aspect, the step of forming an etch mask preferably further comprises the steps of: depositing a hard reticle material on the first layer before the step of depositing the photoresist layer, and removing the photoresist The hard mask material is then removed to leave an island block missing the hard mask material under the island of light confinement; and the remaining photoresist is removed to leave an etch mask that corresponds to the predetermined tiling configuration The location of the missing hard reticle material island block. Suitable hard mask materials include SiO 2 or Si 3 N 4 deposited by PECVD or a metal deposited by flooding or steaming. Once the pyramidal projections have been formed, the remaining islands of the hard reticle material are removed by a suitable wet or dry etch procedure. Similarly, once the chamfered cone indentation has been formed, the remaining hard mask material surrounding the island block is removed by a suitable wet or dry etching procedure. In the method of the fourth level, the depth of the isotropic etching will determine whether the truncated cone or the pyramidal protrusion is formed and its size. However, precise control of the isotropic etch depth can be difficult depending on the etch rate and etch time. Therefore, an etch stop layer can be used to ensure that the etch is terminated at a particular depth. Similarly, if in the method of the fifth level, 1342629 isotropic depth _ will form a concave (four) size. Time-based, isotropic precision control secret depth == months will be difficult. Further, it is desirable to (4) stop the layer to form an inverted miscellaneous recess. Preferably, the first layer of the emissive heterojunction comprises a pre-(four) depth shutdown material buried in the first semiconductor material. The isotropic etch of the first half of the conductor material will then continue until the etch stop material layer is reached' thus providing a higher uniformity and reproducibility of the fabrication process. In the method of the fifth level, 'flattening or carrying cone-shaped indentations are allowed to be formed. Therefore, the invention also provides - the simplification of the photonic crystal type LED structure by using low-cost photolithography or similar procedures to make the definition of large-scale photonic crystals transferred to - coffee on the surface requires complex polishing program. BRIEF DESCRIPTION OF THE DRAWINGS 15 Examples of the present invention will now be described in detail with reference to the drawings: Fig. 1 shows a device of the present invention - a horizontal 2A diagram showing a pyramid arranged in a regular square lattice; Pyramids arranged in a 丨2 symmetry quasicrystal; 20
第3圖以量子井對鏡像間隔距離之函數表示一⑽ LED的常態化光照強度; 第4A至4D圖紛示制 氣作一發光裝置以高速覆晶封裝 基礎的製造方法; 所-一角錐 17 1342629 ^ 第5A圖表示對於一角錐型光子晶體-LED而言,與一無 圖形結構之裝置相較光汲出提高一 30°圓錐; 第5B圖表示對於一角錐型光子晶體-LED而言,與一無 圖形結構之裝置相較總光汲出提高; 5 第5C圖表示對於不同的角錐型光子晶體發光裝置而言 在30°圓錐中之光的百分比; <· 第6A圖表示對一依據本發明一較佳實施例之光子晶體 -LED構造的遠場圖形;Figure 3 shows the normalized illumination intensity of a (10) LED as a function of the distance between the quantum wells and the image; the 4A to 4D diagram shows the manufacturing method of the gas-emitting device as a high-speed flip chip package; 1342629 ^ Figure 5A shows that for a pyramidal photonic crystal-LED, the aperture is increased by a 30° cone compared to a device without a pattern structure; Figure 5B shows that for a pyramidal photonic crystal-LED, A device with no graphic structure is improved compared to the total light output; 5 Figure 5C shows the percentage of light in a 30° cone for different pyramidal photonic crystal illuminators; <· Figure 6A shows the basis for this A far field pattern of a photonic crystal-LED construction in accordance with a preferred embodiment of the invention;
• 第6B圖繪示為依據身本發明另一較佳實施例之光子晶 10 體-LED結構的遠場圖形; 第7A圖出示使用發明的製作方法被形成的隔離角錐體 的一電子顯微影像圖; 第7 B圖繪示使用本發明的製作方法被形成的一角錐體 的光子準晶體配置的電子顯微影像圖; . 15 第8A圖是一習知光子晶體-LED與一具有微腔之角錐• Figure 6B is a far field diagram of a photonic crystal 10 -LED structure in accordance with another preferred embodiment of the present invention; Figure 7A shows an electron microscopy of an isolated pyramid formed using the fabrication method of the invention Figure 7B is an electron micrograph of a photonic quasi-crystal configuration of a pyramid formed using the fabrication method of the present invention; 15 Figure 8A is a conventional photonic crystal-LED with a micro Cavity pyramid
型光子晶體-LED相較於一無圖形結構LED的光汲出提高對 ® *子晶體填充部分之-圖形; . 第8B圖是一角錐型光子晶體-LED相較於具有及不具 有微腔之無圖形結構LED的光汲出提高對光子晶體填充部 20 分之一圖形;以及, 第9圖是一角錐型光子晶體-L E D相較於一無圖形結構 LED的的光汲出提高對LED異質結構核心厚度的圖形。 第10圖繪示倒角錐型裝置之一橫截面; 第11A至11D圖說明製作一發光裝置之一高速覆晶封 18 1342629 裝程序為基礎的製造方法; 第11E圖至111圖說明在第hj圖所示之裝置的上層中 製作一倒角錐型或截頭倒角錐型光子晶體構造之附加製造 步驟; 5 第12A圖繪示一角錐型光子晶體-LED與一無圖形結構 裝置相較在一 30°圓錐中的光汲出提高。 第12B圖繪示一角錐型光子晶體_LED與一無圖形結構 裝置相較的總光汲出提高;The photonic crystal-LED is improved in comparison with the light-emitting of a non-patterned LED to the pattern of the filling portion of the *sub-crystal; Figure 8B is a pyramid-shaped photonic crystal-LED compared to with and without a microcavity The light output of the non-graphical structure LED is increased by one-half of the pattern of the photonic crystal filling portion; and, FIG. 9 is a pyramidal photonic crystal-LED compared to the light-emitting output of a non-graphical structure LED to the LED heterostructure core Thickness of the graph. Figure 10 is a cross-sectional view showing one of the chamfered cone-shaped devices; Figures 11A to 11D are diagrams showing a manufacturing method based on a high-speed flip-chip seal 18 1342629 for manufacturing a light-emitting device; 11E to 111 are illustrated at the An additional manufacturing step of fabricating a chamfered or truncated cone-shaped photonic crystal structure in the upper layer of the apparatus shown in FIG. 5; FIG. 12A illustrates a pyramidal photonic crystal-LED compared to a non-graphical structure device The light output in the 30° cone is increased. Figure 12B shows that the total optical output of a pyramidal photonic crystal_LED is improved compared to a device without a graphic structure;
第12C圖繪示不同的角錐型光子晶體發光裝置在3〇。圓 1〇 錐中之光的百分比; 第13圖繪示依據本發明之一較佳實施例的光子晶體 -LED構造的遠場圖形特性曲線; 第14圖繪示一使用本發明的製作方法被形成的隔離倒 角錐體的的角錐體的一電子顯微影像圖; 15 第15A圖是一習知光子晶體-LED與一具有微腔之角錐Figure 12C shows different pyramidal photonic crystal illuminators at 3 〇. The percentage of light in a circle of cones; Figure 13 is a diagram showing the far-field pattern characteristic of a photonic crystal-LED structure in accordance with a preferred embodiment of the present invention; and Figure 14 is a diagram showing the use of the method of the present invention. An electron micrograph of the pyramid formed by the isolated chamfer cone; 15 Figure 15A is a conventional photonic crystal-LED with a pyramid with a microcavity
型光子晶體-LED相較於一無圖形結構LED的光汲出提高對 光子晶體填充部分之一圖形; 第15B圖是一倒角錐型光子晶體-LED相較於一具有及 不具有微腔之無圖形結構LED的光汲出提高對光子晶體填 20 充部分之一圖形。 t 較佳實施例之詳細說明 本發明的〜項目的是提供改良的光汲出以及發光裝置 的定制遠場發射。這些裝置可應用大範圍的發光半導體材 19 1342629 料系統,包括但未受限於,InGaN、丨nGaP、InGaAs、InP 或ZnO。發明說明將側重於實施於綠光InGaN發光裝置中的 定向光汲出技術。然而,設計能在其他利用此一材料的發 射波長(諸如藍或紫外線),以及利用其他材料系統的發射波 5 長,諸如適於發射紅及黃色波長的inGaP中被最佳化及實 施0The photonic crystal-LED has a pattern of filling the photonic crystal compared to the light-emitting of a non-patterned LED; Figure 15B is a chamfered cone photonic crystal-LED compared to one with and without a microcavity The light output of the graphic structure LED increases the pattern of the filling portion of the photonic crystal. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An item of the present invention is to provide improved light exit and custom far field emission of a light emitting device. These devices can be used with a wide range of luminescent semiconductor materials, including but not limited to, InGaN, 丨nGaP, InGaAs, InP or ZnO. SUMMARY OF THE INVENTION A focus will be placed on directional light extraction techniques implemented in green InGaN light emitting devices. However, the design can be optimized and implemented in other emission wavelengths (such as blue or ultraviolet) that utilize this material, as well as in the use of other material systems, such as inGaP, which is suitable for emitting red and yellow wavelengths.
在本發明的較佳實施中所提出的一種新穎高階角錐变 光子晶體(PC)或準晶體圖形在與一階光子晶體結構相較之 下提供增加之光汲出。光子晶體設計也考慮到定制由裝置 10 發出之遠場光分配。光子晶體子區城的角錐型形狀及其良 好定義之蓋瓦配置容使由裝置以一光束汲出光,該一方式 較諸由一朗伯特光源的光汲出更為準直。一可供製造該裝 置的簡化程序也將被描述。A novel high order pyramidal photonic crystal (PC) or quasi-crystal pattern proposed in a preferred embodiment of the present invention provides increased light output compared to a first order photonic crystal structure. The photonic crystal design also takes into account the customization of the far-field light distribution by the device 10. The pyramidal shape of the photonic crystal sub-region and its well-defined tiling arrangement allow the device to illuminate with a beam of light that is more collimated than the light exiting from a Lambertian source. A simplified procedure for making the device will also be described.
就角錐體直徑而言,較高階的光子晶體尺寸在尺寸方 15 面大於Ι Ομπι且可能大於1.5μηι或2.0μΐΏ,且尺寸上可大到 3.0μιη. ’ 5μηι和4‘Ομηι但不限於此。這係取決於遠場圖形, LED厚度及量子井在GaN異質結構中之位置而變化。 第1圖繪示本發明提出之發光裝置的一橫截面,該發光 裝置包括週期性地突出於于η型攙雜GaN或InGaN層上的角 20錐體10卜準晶態、無定形或其他複雜的有序或重覆蓋瓦配 置。角錐型蓋瓦配置被設計成提供容許被捕陷的光進入光 子晶體之布洛赫模態的色散帶。一旦光進入布洛赫模態 内,光子晶體即提供一使光進入自由空間的方式。 第1圖所示之裝置包含一發光異質結搆,該異質結搆包 20 1342629In terms of the pyramidal diameter, the higher order photonic crystal size is larger than Ι Ομπι and may be larger than 1.5 μm or 2.0 μΐΏ in size, and may be as large as 3.0 μm in size and not larger than 3.0 μm. This depends on the far field pattern, the thickness of the LED, and the location of the quantum well in the GaN heterostructure. 1 is a cross-sectional view of a light-emitting device according to the present invention, which includes an angle 20 cone 10 periodically epitaxial, amorphous or other complex periodically protruding from an n-type doped GaN or InGaN layer. Ordered or heavily covered tile configuration. The pyramidal tiling arrangement is designed to provide a dispersive band that allows trapped light to enter the Bloch mode of the photonic crystal. Once the light enters the Bloch mode, the photonic crystal provides a way to get the light into free space. The device shown in Figure 1 comprises a luminescent heterostructure, the heterostructure package 20 1342629
^ 括一 n-GaN或InGaN頂層102及一下方的p-型GaN或InGaN 層104,一多重量子井(MQW)結構103存在於這些層之間。 在p-型層104之下方存在一反射層105,反射層可為金屬反 射器形式諸如銀,或呈一DBR或全方向反射器(ODR)形式。 5 發光結構被一載體底板或載片106支持。在一較佳實施例 中,載體底板包括一具有高導熱率的導電材料諸如金屬或 μA n-GaN or InGaN top layer 102 and a lower p-type GaN or InGaN layer 104 are included, and a multiple quantum well (MQW) structure 103 is present between the layers. There is a reflective layer 105 beneath the p-type layer 104, which may be in the form of a metal reflector such as silver, or in the form of a DBR or omnidirectional reflector (ODR). 5 The light emitting structure is supported by a carrier substrate or carrier 106. In a preferred embodiment, the carrier substrate comprises a conductive material having a high thermal conductivity such as metal or μ
金屬合金或是矽或碳化矽。在另一較佳實施例中存在一蝕 刻停止層,107,蝕刻停止層可由像是AlGaN,InGaN等材 • 料所形成但不限於此,該蝕刻停止層容許角錐體深度的精 10 確控制。此層是埋設η-型層101和102之間。 本發明中較佳的光子蓋瓦配置主要有三種,且該等配 置具有下列性質:短程及長程有序,即光子晶體;短程平 移無序但長程有序,即光子準晶體;以及短程間隔有序且 長程無序,即無定形蓋瓦配置。在一無定形配置情況下, 15 鄰接之角錐型和倒角錐型區域之間的間隔距離是固定的但 迴轉對稱隨機化。The metal alloy is either tantalum or tantalum carbide. In another preferred embodiment, there is an etch stop layer, 107, which may be formed of, but not limited to, a material such as AlGaN, InGaN, etc., which allows for precise control of the pyramid depth. This layer is buried between the n-type layers 101 and 102. There are three main types of photonic shingles in the present invention, and the configurations have the following properties: short-range and long-range order, that is, photonic crystals; short-range translation disorder but long-range order, that is, photon quasicrystals; and short-range intervals Sequence and long-range disorder, that is, amorphous tiling configuration. In the case of an amorphous configuration, the separation distance between the 15 adjacent pyramidal and chamfered cone regions is fixed but rotationally symmetrically randomized.
® 這些圖形定義的種類亦可包括具有上述蓋瓦配置的重 . 覆單元。另外,他們能區域可包括具有缺陷的區域,亦即 角錐體與倒角錐體被除去或角錐體的形狀或大小被修正的 20 區域。子區域亦可由具有未被蝕刻之尖銳頂點區域的角錐 體組成,引發平頭(截頭)角錐體。 圖形定義可藉一些參數賦與特徵,包括定義成分隔二 鄰接角錐體或倒角錐體中心之距離的晶格間距,以及角錐 體結晶學曝光面與GaN晶格之間所形成的角度0。在本發 21 明的—層面—蝕刻停止層107被用來控制蝕刻深度。此可允 。+角錐體基部直徑的正確控制。就一特定蝕刻深度d而言, 角錐體的基部直徑φ是: Φ = 2^d/tan(6) ⑺ 本發明的一個主要主要層面是利用結晶學上對齊的大 型特徵來提供最大圖形再現準確度以及和放鬆的位置準確 度。 六角形角錐體或倒角錐體(在c_平面GaN中被形成)能 排列成一規則模式、準結晶態模式、無定形模式或其他的 適§排列。第2 A圖中所示之一例中六角形的角錐體以一規 則的正方形晶格排列而形成一光子晶體。第2B圓繪示一排 列成一 12對稱正方-三角準晶體蓋瓦的角錐體或倒角錐體 以形成一光子準晶體。 本發明的一增強型式應用一置放在發光區域下方的光 學反射器以將朝上方傳播的光向下反射。此外,發光區域 與反射器之間的分隔距離被設計成基於所謂的微腔效應提 高朝上發射之光。角錐型或倒角錐型光子晶體接著與微腔 效應結合更進一步提高光汲出而被最佳化。如Appishen於 2003年4月7日在Appl.PhysLett.82,14,2221中揭述’下列方程 式描述在一LED頂表面的相對功率強度為QW區域和反射 器間之分隔距離的函數: E = w〇2+ wr2+2w〇wrcos(K+0+0,) (3) Φ' = 2 n(2dcos(6))/X„ ⑷ 式中的相關數如下: 1342629 vv0=發射光振輻; wr=反射光振輻; φ=鏡上反射的相移; Φ’ =由於發射光與反射光之間的路徑長度差所致的相 5移’該相移隨著微腔和QW間的間隔距離以及LED材料的入 射角和波長而改變;以及,0=相對法線的發射角。® The types of these graphic definitions can also include heavy-duty units with the above-described tiling configuration. In addition, their energy regions may include regions with defects, i.e., regions in which the pyramids and chamfers are removed or the shape or size of the pyramids are corrected. The sub-region may also consist of a pyramid having a sharp apex region that is not etched, causing a flat (truncated) pyramid. The graphical definition can be characterized by a number of parameters, including the lattice spacing defined as the distance separating the two adjacent pyramids or the center of the chamfer, and the angle 0 formed between the crystallographic exposure surface of the pyramid and the GaN lattice. In the layer of the present invention, the etch stop layer 107 is used to control the etching depth. This is acceptable. + Correct control of the base diameter of the pyramid. For a particular etch depth d, the base diameter φ of the pyramid is: Φ = 2^d/tan(6) (7) A major primary aspect of the invention is the use of large features that are crystallographically aligned to provide maximum pattern reproduction accuracy. Degree as well as the location accuracy of relaxation. Hexagonal pyramids or chamfer cones (formed in c-plane GaN) can be arranged in a regular pattern, a quasi-crystalline mode, an amorphous mode, or other suitable arrangement. In the example shown in Fig. 2A, the hexagonal pyramids are arranged in a regular square lattice to form a photonic crystal. The 2B circle shows a series of pyramids or chamfers of a 12-symmetric square-triangular quasi-crystal tiling to form a photonic quasicrystal. An enhanced version of the invention applies an optical reflector placed below the illumination area to reflect light propagating upwardly downward. Furthermore, the separation distance between the illuminating region and the reflector is designed to increase the upwardly emitted light based on the so-called microcavity effect. The pyramidal or chamfered cone photonic crystals are then optimized in combination with the microcavity effect to further enhance light exit. As Appishen, published in Appl. PhysLett. 82, 14, 2221, on April 7, 2003, 'the equation below describes the relative power intensity at the top surface of an LED as a function of the separation distance between the QW region and the reflector: E = W〇2+ wr2+2w〇wrcos(K+0+0,) (3) Φ' = 2 n(2dcos(6))/X„ (4) The correlation in the equation is as follows: 1342629 vv0=transmitted light vibration; Wr=reflected light vibration; φ=phase shift of specular reflection; Φ′ = phase shift due to path length difference between emitted light and reflected light' the phase shift with the interval between microcavity and QW The distance and the angle of incidence and wavelength of the LED material vary; and, 0 = the angle of emission relative to the normal.
為說明微腔效應,第3圖為由一具有一反射鏡之GaN LED所獲得之光強度為量子井與反射鏡間之距離的函數 圖。該強度對由一不具反射鏡之GaN LED所獲得之強度常 10態化’藉以說明其增強。為簡化起見,假設反射鏡具有100% 之反射率。很明顯地當與一個無反射鏡的平坦GaN發光裝 置相較最高有大約多3.5倍的光被汲出。有關反射器單獨的 貢獻,此相當於因微腔效應而有大約多175倍的光被汲 出。置子井置放在與反射鏡的正確距離處是在一 lED中獲 I5 得最大光沒出效率的關鍵。To illustrate the microcavity effect, Figure 3 is a graph of the intensity of light obtained from a GaN LED with a mirror as a function of the distance between the quantum well and the mirror. This intensity is indicative of the enhancement of the intensity obtained by a GaN LED without a mirror. For the sake of simplicity, the mirror is assumed to have a reflectivity of 100%. It is apparent that about 3.5 times more light is thrown out than a flat mirrorless GaN light-emitting device. Regarding the individual contribution of the reflector, this corresponds to approximately 175 times more light being extracted due to the microcavity effect. Placement of the well at the correct distance from the mirror is the key to achieving maximum light out efficiency in IED in a lED.
當與一朗伯特光源的相較之下微腔效應也在LED之遠 場輻射形狀中導入偏差。在本發明的背景中,增加波瓣輻 射可與表面光子晶體結構共同被最佳化,俾使得能比個別 應用兩種光汲出技術所期望者從LED有更大的光汲出及方 20向性。微腔效應在異質結構内減少發射的均質性,藉此允 許内部入射至光子晶體的光更為準直。 由於高深寬比特徵以及光子帶結構提供的大介電對比 度,LED的波導模態可肖光子帶結構的色散帶有效地重疊 以容使其間有強耗合。然而,在一厚核心内部的等方性發 23 1342629 射情況之下,有許多波導模態被建立。是以光子晶體的色 散帶無法設計成與所有的捕陷模態重疊。然而,藉由利用 微腔準直光束可減少建立之波導模態數目。隨之光子的帶 結構可被最佳化設計俾有效汲出捕陷於LED中的更為緊密 5間隔且數目較少的模態。The microcavity effect also introduces a bias in the far field radiation shape of the LED when compared to a Lambertian source. In the context of the present invention, the addition of lobe radiation can be optimized along with the surface photonic crystal structure, which enables greater light output and square 20-direction from LEDs than would be expected for individual applications. . The microcavity effect reduces the homogeneity of emission within the heterostructure, thereby allowing the light incident internally to the photonic crystal to be more collimated. Due to the high aspect ratio characteristics and the large dielectric contrast provided by the photonic band structure, the waveguide modes of the LEDs can effectively overlap with the dispersion bands of the Schematic subband structure to accommodate strong intervening. However, under the condition of an isotropic 23 133422 inside a thick core, many waveguide modes are established. It is because the chromatic dispersion of the photonic crystal cannot be designed to overlap with all trap modes. However, the number of waveguide modes established can be reduced by utilizing a microcavity collimated beam. The band structure of the photons can then be optimally designed to effectively capture a tighter 5 interval and fewer modes trapped in the LED.
本發明的一更進一步層面是一種具有上述之角錐型結 構之光子帶結構的LED簡化製造方法。一種可行的製造程 序繪示於第4A至41圖。最初,一n型攙雜GaN或lnGaN層4〇1 是藉由金屬有機化學氣相蒸汽沈澱(MOCVD)或其他類似 技術(像是MBE)在一晶格匹配的基質410上生長,通常所使 用的基質是藍寶石,GaN以及SiC。在本發明之一較佳實施 例中,一由諸如為InGaN或AlGaN之一材料所形成的蝕刻停 止層409被埋入η-GaN層中。n_GaN或InGaN層持續生長為姓 刻停止層403上方之層408。多重GaN-InGaN量子井402接著 由一p-型GaN層403生長。此一階段所生產的完成LED異質 結構繪示於第4A圖。A still further aspect of the present invention is a simplified LED manufacturing method having the photonic band structure of the above-described pyramidal structure. A possible manufacturing process is shown in Figures 4A through 41. Initially, an n-type doped GaN or lnGaN layer 4〇1 is grown on a lattice-matched substrate 410 by metal organic chemical vapor phase vapor deposition (MOCVD) or other similar technique (such as MBE), typically used. The matrix is sapphire, GaN and SiC. In a preferred embodiment of the invention, an etch stop layer 409 formed of a material such as InGaN or AlGaN is buried in the η-GaN layer. The n-GaN or InGaN layer continues to grow into a layer 408 over the stop layer 403. Multiple GaN-InGaN quantum wells 402 are then grown from a p-type GaN layer 403. The completed LED heterostructure produced in this stage is shown in Figure 4A.
一反射鏡404接著沈積在如第4B圖所示的口-〇抓層4〇3 頂部。反射器可以是金屬的,包括諸如銀或金之一層由濺 鍍或蒸鍍沈積的適當金屬。或者,反射器可為—呈分佈反 20饋反射器(DBR)或全方向反射器(ODR)形式的介電多層。此 種構造可利用諸如PECVD之技術藉由濺鍍沈積。 如第4C圖所示,第4B圖的異質結構接著被結合至一基 質405。基質405最好為-提供良好導熱與導電性的金屬合 金,但可由其他材料諸如SiC^tSi組成。在結合操作前可在 24 反射鏡404上沈積其他層以輔助結合程序。A mirror 404 is then deposited on top of the port-scratch layer 4〇3 as shown in Figure 4B. The reflector may be metallic, including a suitable metal such as silver or gold deposited by sputtering or evaporation. Alternatively, the reflector can be a dielectric multilayer in the form of a distributed inverse feedback reflector (DBR) or an omnidirectional reflector (ODR). Such a construction can be deposited by sputtering using techniques such as PECVD. As shown in Fig. 4C, the heterostructure of Fig. 4B is then bonded to a substrate 405. Substrate 405 is preferably a metal alloy that provides good thermal and electrical conductivity, but may be composed of other materials such as SiC^tSi. Additional layers may be deposited on the 24 mirror 404 prior to the bonding operation to aid in the bonding process.
在最後的習知製作步驟中,藍寶石基質4H)接著利用雷 射制離或其他相似技術除去以提供如第4D圖中所示之異質 結構。雖然典型上钱刻停止層不存在,此一結構可形成一 最為的元整習知裝置。雷射剝離程序使n_GaN層·的表面 粗糙(典型地達5〇11111至30〇11爪等級)。在一比較傳統的裝置 中,表面可更進一步被粗化以改進光汲出。在本發明的一 層面中,光子帶結構角錐體的尺寸與表面粗度相較之下較 大’因此在定義圖形前不需要拋光表面。 10 第4E至41圖所示為依據本發明製作一如第41圖中所示 之裝置的增加製程步驟。 第4E圖繪示掩蔽層的沈積。特別是圖中繪示一可取捨 的方法步驟,藉以使一硬光罩層406被沈積以供後續轉移所 需要的圖形至n-GaN層401。硬光罩層由PECVD沈積的Si02 15或以办4所構成或是其可為一藉由濺鍍或蒸鍍沈積的金屬。 一光阻劑407接著沈積在硬光罩406上。然而,在一些情況In the final conventional fabrication step, the sapphire substrate 4H) is then removed by laser separation or other similar technique to provide a heterostructure as shown in Figure 4D. Although typically the stop layer does not exist, this structure can form a most sophisticated device. The laser lift-off procedure roughens the surface of the n-GaN layer (typically up to 5〇11111 to 30〇11 claw grade). In a more conventional device, the surface can be further roughened to improve light exit. In one aspect of the invention, the size of the pyramid of the photonic strip structure is relatively large compared to the surface roughness' so there is no need to polish the surface prior to defining the pattern. 10 Figures 4E through 41 illustrate an incremental process step for fabricating a device as shown in Figure 41 in accordance with the present invention. Figure 4E depicts the deposition of the masking layer. In particular, a method step is illustrated in which a hard mask layer 406 is deposited for subsequent transfer of the desired pattern to the n-GaN layer 401. The hard mask layer is composed of PECVD deposited SiO 2 15 or it may be a metal deposited by sputtering or evaporation. A photoresist 407 is then deposited on the hard mask 406. However, in some cases
中’可能省卻硬光罩層而光阻劑層407直接被沈積至n-GaN 層401上。 由於角錐型特徵的尺寸大,光阻劑407可利用標準紫外 20 線微影技術曝光以使其具有所需蓋瓦配置的圖形。曝光區 域的橫向形狀可對應於所需角錐體的橫載面形狀,或是可 為較簡單的形狀,諸如正方形。已曝光的光阻劑接著顯影 留下對應於角錐體頂點之所需位置的分離材料島塊,如第 4F圖所示。如果硬光罩406存在,則利用RIE、ICP或一類似 25 1342629 程序乾蝕刻。這一個步驟將圖形定義由光阻劑4〇7轉移至硬 光罩406,如第4G圖所示。剩餘的光阻劑4〇7接著被剝離。 接著’ n-GaN層401利用一等向性濕蝕刻被晶體濕蝕 刻’如第4H圖所示。一濕触刻GaN的較佳方法是使用一浴 5恤度範圍由室溫至lOOl的到8M濃度範圍koh溶液。钱 刻時間範圍大約在45分鐘左右。可選替的濕蝕刻劑包含 NaOH 或 Η3Ρ04。The middle may omit the hard mask layer and the photoresist layer 407 is directly deposited onto the n-GaN layer 401. Due to the large size of the pyramidal features, the photoresist 407 can be exposed using standard ultraviolet 20-line lithography techniques to have a pattern of the desired tiling configuration. The lateral shape of the exposed area may correspond to the cross-sectional shape of the desired pyramid, or may be a relatively simple shape such as a square. The exposed photoresist is then developed leaving a separate island of material corresponding to the desired location of the pyramidal apex, as shown in Figure 4F. If the hard mask 406 is present, it is dry etched using RIE, ICP or a similar 25 1342629 procedure. This step transfers the graphical definition from photoresist 4〇7 to hard mask 406 as shown in Figure 4G. The remaining photoresist 4〇7 is then stripped. Next, the 'n-GaN layer 401 is wet etched by the crystal by an isotropic wet etching as shown in Fig. 4H. A preferred method of wet-etching GaN is to use a bath of 5 zeos ranging from room temperature to 100 l to a concentration range of 8 M koh solution. The time range for money is about 45 minutes. The optional wet etchant contains NaOH or Η3Ρ04.
藉姓刻程序形成的六角形角錐體的晶面是GaN晶體的 { 10-M }平面。他們與角錐體底部形成一角度58 4。。蝕 10刻停止層409之存在容許高度的正確控制故亦使角錐體的 基部直徑能正確控制。最後,如果一硬光罩4〇6被使用,則 其可利用一適當的濕或乾蝕刻程序除去而留下第41圖中所 示之最終結構。The crystal plane of the hexagonal pyramid formed by the surname process is the { 10-M } plane of the GaN crystal. They form an angle 58 4 with the bottom of the pyramid. . The presence of the etch stop layer 409 allows the correct control of the height and thus allows the base diameter of the pyramid to be properly controlled. Finally, if a hard mask 4 〇 6 is used, it can be removed using a suitable wet or dry etch procedure leaving the final structure shown in Figure 41.
第7A圖繪示由此一方法所製造之一種角錐體的掃瞄式 15電子顯微照片。在此一情況,角錐體被隔離且使用較佳製 作貫施例被形成,小晶界面{ 1〇_M丨示於7〇1。第78圖為 此種角錐體之一光子準晶體蓋瓦的掃瞄式電子顯微照片, 忒—蓋瓦已經利用較佳製作技術被蝕刻在 n-GaN頂面中。角 錐體7破安排成一正方形_三角形的蓋瓦且第7b圖所示之結 20構線展不條繪示底層的蓋瓦正方形和三角形而圓圈強調 準晶體圖形的頂點。 在較佳實施例中’包括層401,409和408的複合n-GaN 上邛區域設置在發光構造上方。因此,光從層4〇2發出且在 最後紐由401區域放出前經歷多重内部反射。 26 1342629 一個厚的n-GaN生長區域必需減少缺陷密度以便形成 高品質量子井(QW)層,且因而改善LED的内部量子效率。 為了製造上的利益上部區域(層401,409和408)作為脆弱之 QW區域402的一保護層,防止其在角錐體的濕蝕刻期間受 5 到損害且將QW區域的表面復合極小化。對QW區域之蝕刻 也會因減少最大有效發光區域而不利地影響LED的總發光 輸出。Fig. 7A is a scanning 15 electron micrograph of a pyramid produced by this method. In this case, the pyramids are isolated and formed using a preferred embodiment, and the small crystal interface {1〇_M丨 is shown at 7〇1. Figure 78 is a scanning electron micrograph of a photonic quasi-crystal tiling of such a pyramid, which has been etched into the top surface of the n-GaN using a preferred fabrication technique. The pyramids 7 are broken into a square-triangled tiling and the knot shown in Fig. 7b shows the underlying tiling squares and triangles and the circles emphasize the apex of the quasi-crystal pattern. In the preferred embodiment, the composite n-GaN upper germanium region comprising layers 401, 409 and 408 is disposed over the light emitting structure. Thus, light is emitted from layer 4〇2 and undergoes multiple internal reflections before the final button is released from the 401 region. 26 1342629 A thick n-GaN growth region must reduce the defect density in order to form a high quality quantum well (QW) layer and thus improve the internal quantum efficiency of the LED. For the benefit of the upper region (layers 401, 409 and 408) as a protective layer of the fragile QW region 402, it is prevented from being damaged during the wet etching of the pyramid and minimizing the surface recombination of the QW region. Etching of the QW region also adversely affects the total illumination output of the LED by reducing the maximum effective illumination area.
另外,有關於光汲出的改進,所需要的角錐體直徑尺 寸達1·75μπι之級度,中心之間距為2.5μπι。尺寸限制了層401 10 的最小厚度,因此角錐體最好位於厚的n-GaN層上。同時, 為了改進光汲出,藉由蝕刻減少存在異質結構中的捕陷模 態數目以減少LED波導區域的總厚度。此可使光子帶結構 與一較大百分比之捕陷模態重疊,藉以提供如第8圖中所示 的改進光汲出。另外’ n-GaN為高度傳導性者且此一性質使 15得獨立電流傳佈層沈積在光子結構頂部表面的需求減至最 少’該獨立電流傳佈層之沈積對於由裝置光汲出有不利的 影響。 數值模擬的成果繪示於第5A,5B和5C圖,說明典型角 錐型光子帶結構裝置的表現。Z軸顯示與一具反射器之非圖 20形化LED相較的總光汲出提高因素。成果繪製成沿X軸501 為填充部分(以%計)之函數圖形且沿γ軸5〇2為光子帶結構 之間距(以nm計)的函數。填充部分定義為直徑/間距*1〇〇。 第5A圖繪示一角錐型光子晶體與一具有一底部反射器 的無圖形結構LED相較在一中央3〇。圓錐中的光汲出提 27 1342629 高。成果顯示對於一間距2500nm及一填充邹分75%,且在 一 d = 0.6/ λ n〜13 lnm之位置的QW區域下方有一最佳化微 腔設計時,最大提高為5.45。這些參數相當於一以2 5μηι間 距相間隔一具有約1.9μπι角錐體直徑的裝置。 5 使用一 2D有限差分時域法實施模擬。重要的是注意這 些模擬未併入由2D轉換成在空間中的3D模擬時的數值偏 差因而使實驗成果被預期提供更大的光汲出值。 第5B圖以晶格常數與填充部分函數表示相較於一具有 一底部反射器的無圖形結構led的光汲出提高。如第5八圖 10中所示,成果的重點是最佳的操作範圍出現在一間距 2500nm且填充部分為75%,QWs之下具有—最佳化微腔設 計處。 最後,第5C圖表不-具有角錐型光子晶體結構之裝置 的光在30。圓錐中的百分比。如圖中所見,由裝置發出的光 15南達45%可被導向於垂直於裝置表面具有_3()。半角的中心 圓錐中。此相當於與一朗伯特發光裝置相較在一定向圓錐 中有多出84%的光。方向性的増加是由於肖錐體的有序排 列以及角錐體的定義良好斜側壁。與一般的直側Μ、餘刻、 空氣桿相較’斜側壁可在30。圓錐内提供大約多出3〇%的光。 2〇 第从和68圖為一平面中之光分布的橫截面。成果以沿 X軸的遠場角6G1的函數作圖且表示光強度由一底部有 反射器之未具圖形LED對其歸一化。遠場圖形是參考 LED的表面垂直線。第6A圖顯示晶格常數為丨獅nm且角錐 體直L為112〇nm之LED的遠場圖形,該LED的總光沒出提 28 1342629 高至高於具有一反射器以及最佳化微腔之發光裝置的2.67 倍。在30°圓錐中的提高是4.57倍且在30。圓錐中含有總光汲 出光的40.5%。 第6B圖顯示晶格常數為25〇〇nrn且角錐體直徑為 5 1870nm之LED的遠場圖形,該LED的總光汲出提高大於具 有一反射器以及一最佳化微腔之發光裝置的3 61倍。30。圓 錐中的提高是5.45倍且在3〇。圓錐中含有總量光的35.8%。In addition, with regard to the improvement of the light extraction, the required pyramidal diameter is up to a scale of 1.75 μm, and the distance between the centers is 2.5 μm. The size limits the minimum thickness of layer 401 10, so the pyramid is preferably located on a thick n-GaN layer. At the same time, in order to improve the pupil output, the total number of trapping modes in the heterostructure is reduced by etching to reduce the total thickness of the LED waveguide region. This allows the photonic band structure to overlap with a larger percentage of trapping modes to provide improved light exit as shown in FIG. In addition, 'n-GaN is highly conductive and this property minimizes the need for 15 separate current spreading layers to deposit on the top surface of the photonic structure. The deposition of the independent current spreading layer has a detrimental effect on device light exit. The results of the numerical simulations are shown in Figures 5A, 5B and 5C, illustrating the performance of a typical pyramidal photonic band structure device. The Z-axis shows the overall light output improvement factor compared to a reflector that is not a 20-shaped LED. The results are plotted as a function of the fill portion (in %) along the X-axis 501 and along the γ-axis 5〇2 as a function of the distance (in nm) between the photonic band structures. The fill portion is defined as diameter/pitch*1〇〇. Figure 5A shows a pyramidal photonic crystal in a central 3" compared to a non-graphical LED having a bottom reflector. The light in the cone is raised 27 1342629 high. The results show a maximum increase of 5.45 for an optimized microcavity design with a pitch of 2500 nm and a fill margin of 75% and a QW region below a d = 0.6/ λ n~13 lnm. These parameters correspond to a device having a cone diameter of about 1.9 μπι spaced apart by a distance of 25 μm. 5 Simulate the simulation using a 2D finite difference time domain method. It is important to note that these simulations do not incorporate numerical deviations from 2D to 3D simulations in space and thus allow experimental results to be expected to provide greater pupil output values. Figure 5B is enhanced by the lattice constant and the fill portion function representation compared to a light pattern of a non-graphical structure led with a bottom reflector. As shown in Figure 5, Figure 10, the focus of the results is that the optimal operating range is at a pitch of 2500 nm and a fill portion of 75%, with QWs having an optimized microcavity design. Finally, the 5C chart does not - the light of the device having the pyramidal photonic crystal structure is at 30. The percentage in the cone. As seen in the figure, up to 45% of the light emitted by the device can be directed to have a _3() perpendicular to the surface of the device. The center of the half angle is in the cone. This is equivalent to 84% more light in a directional cone than a Lambertian illuminator. The directional addition is due to the ordered arrangement of the pyramids and the well defined oblique sidewalls of the pyramids. Compared with the general straight side Μ, the remaining moment, and the air rod, the slant side wall can be 30. Approximately 3% more light is provided within the cone. 2〇 The second and 68 are cross sections of the light distribution in a plane. The result is plotted as a function of the far field angle 6G1 along the X axis and indicates that the light intensity is normalized by a non-patterned LED with a reflector at the bottom. The far field pattern is the vertical line on the surface of the reference LED. Figure 6A shows the far-field pattern of an LED with a lattice constant of 丨 lion nm and a pyramidal straight L of 112 〇 nm. The total light of the LED is not raised 28 1342629 up to a higher than a reflector and optimized microcavity The light-emitting device is 2.67 times. The increase in the 30° cone is 4.57 times and is at 30. The cone contains 40.5% of the total pupil output. Figure 6B shows the far field pattern of an LED with a lattice constant of 25 〇〇nrn and a pyramidal diameter of 5 1870 nm. The total light output of the LED is increased more than that of a luminaire having a reflector and an optimized microcavity. 61 times. 30. The increase in the cone is 5.45 times and is 3 inches. The cone contains 35.8% of the total light.
此相當於與一朗伯特發光裝置相較在一定向圓錐中有多出 46%的光。 10 下列表1就相同的綠色GaNLED設計成一包含蝕刻空This corresponds to 46% more light in a directional cone than a Lambertian illuminator. 10 Below Table 1 is the same green GaN LED designed to include an etched empty
氣桿之一階光子晶體LED的簡單朗伯特發射器,以及設計 成一包含钱刻角錐體之角錐型光子晶體LED,以總發射光 之百分比表示在一狹窄30。圓錐角内發射之光的比較。就光 子晶體裝置而言,尺寸被最佳化而在30。圓錐中汲出最大百 15分比之光。一階光子晶體尺寸是由一間距為350nm,直徑大 約是21〇nm且蝕刻深度為120nm左右的晶格空氣桿所組 成’而角錐型光子晶體尺寸係如上所述。 表1 裝置類型 朗伯特LED 光子晶體LED 角錐型光子晶體 LED 在30°圓錐中的 光百分比 24.9 34.9 45.0 如同所見,方向性之增加可在使用一更為優化的結構 中獲得。 第8A和8B圖說明當一光子帶結構以一微腔發光裝置 29 1342629 最佳化時可達成的光汲出增加。本例中一間距為5〇〇nm且有 一簡單反射器之常規光子晶體與一間距相同但亦具有一微 腔反射器的倒角錐型光子晶體比較。在第8A與8B圖中總體 光提高802以光子晶體填充部分801之函數作圖。 5 在第8A圖中’實線803表示一由具有一反射器的非圖形A simple Lambert emitter of a gas-pole one-step photonic crystal LED, and a pyramidal photonic crystal LED designed to include a money engraved pyramid, expressed as a percentage of total emitted light at a narrow 30. A comparison of the light emitted within the cone angle. In the case of a photonic crystal device, the size is optimized at 30. A maximum of one hundred and fifteen points of light is emitted from the cone. The first-order photonic crystal size is composed of a lattice air rod having a pitch of about 350 nm and a diameter of about 21 Å and an etching depth of about 120 nm. The pyramidal photonic crystal size is as described above. Table 1 Device Types Lambert LED Photonic Crystal LED Pyramid Photonic Crystal LED Percentage of light in a 30° cone 24.9 34.9 45.0 As can be seen, the increase in directivity can be achieved with a more optimized structure. Figures 8A and 8B illustrate the increase in pupil output that can be achieved when a photonic band structure is optimized with a microcavity illumination device 29 1342629. In this example, a conventional photonic crystal having a pitch of 5 〇〇 nm and having a simple reflector is compared with a chamfered cone photonic crystal having the same pitch but also having a microcavity reflector. The overall light enhancement 802 is plotted as a function of photonic crystal fill portion 801 in Figures 8A and 8B. 5 in Figure 8A, 'solid line 803 indicates a non-graphic with a reflector
化LED總光汲出增加歸一至輸出中。虛線8〇4代表兼具有微 腔與反射器的光子晶體與一具有一反射器之非圖形化led 相較的總光汲出提高。第8B圖突出由於微腔效應所獲得之 增加光汲出效果。虛線805顯示當結合微腔、歸一化至具有 10 一反射器及一微腔的非圖形化LED時,與實線803相較之下 所增加的光子晶體光汲出效果,顯示當從一僅具有一簡單 反射器的非圖形化LED歸一化至同一裝置時的結果。因此 結合效應所造成的差別增加清楚可見。The total LED output is increased to the output. The dashed line 8〇4 represents an increase in total light output compared to a photonic crystal with a microcavity and a reflector compared to a non-patterned led with a reflector. Fig. 8B highlights the effect of increased light extraction due to the microcavity effect. Dotted line 805 shows the increased photonic crystal light extraction effect compared to the solid line 803 when combined with a microcavity, normalized to a non-patterned LED having 10 reflectors and a microcavity, displayed when only from one The result of normalizing a non-patterned LED with a simple reflector to the same device. Therefore, the increase in the difference caused by the combined effect is clearly visible.
第9圖就角錐型及倒角錐型兩者說明減少一光子之帶 15結構發光異質結構區域厚度的效應。光汲出902與具有一反 射器的裸平坦LED相較對以奈米變化的led異質結構核心 厚度901作圖。可清楚看見的是當異質結構的厚度減少時, 光汲出量增加。在本實例中的情況,光子晶體結構尺寸和 幾何學對所有的異質結構厚度被固定且未應用微腔效應。 20因此,對於光汲出而言明顯地角錐型結構被蝕刻至異質結 構中是有利的,因LED的有效厚度會被減少。 在本發明的另一較佳實施中,一新穎的高階倒角錐型 光子晶體(PC)或準晶體圖形被提出,與一階光子晶體圖形 相較該圖形提供增加的光汲出。光子晶體設計也考慮到裝 30 1342629 置發出之遠場光分配的定制。光子晶體子區域的倒角錐形 狀以及其被良好定義的蓋瓦配置允許光以一比從一朗伯特 光源更為準直的光束從裝置中汲出。製造該裝置的一個簡 化程序也將被描述。 5 根據倒角錐體直徑,較高階的光子晶體尺寸大於Ι.Ομπι 且可能大於1·5μηι或2.0μηι,以及可大到但不限於3.〇μιη、 3,5μηι與4.0μιη。此係依遠場圖形、[ED的厚度以及量子井 在GaN異質結構之光產生區域中的位置而變化。Figure 9 illustrates the effect of reducing the thickness of a photo-emitting heterostructure region for both a pyramidal and a chamfered cone. The light exit 902 is plotted against the bare heterostructure core thickness 901 of nanometer variation compared to a bare flat LED having a reflector. It can be clearly seen that when the thickness of the heterostructure is reduced, the amount of light extraction increases. In the case of this example, the photonic crystal structure size and geometry are fixed for all heterostructure thicknesses and no microcavity effect is applied. Thus, it is advantageous for the exit pupil to be etched into the heterostructure for the apparent pyramidal structure, since the effective thickness of the LED can be reduced. In another preferred embodiment of the invention, a novel high order chamfer cone photonic crystal (PC) or quasi-crystal pattern is proposed which provides increased pupil output compared to a first order photonic crystal pattern. The photonic crystal design also takes into account the customization of the far-field light distribution issued by 30 1342629. The chamfered cone shape of the photonic crystal sub-region and its well-defined tiling configuration allow light to be extracted from the device by a beam that is more collimated than from a Lambertian source. A simplified procedure for making the device will also be described. 5 According to the chamfer cone diameter, the higher order photonic crystal size is larger than Ι.Ομπι and may be greater than 1·5μηι or 2.0μηι, and may be large but not limited to 3.〇μιη, 3,5μηι and 4.0μιη. This is a function of the far field pattern, [the thickness of the ED, and the position of the quantum well in the light generating region of the GaN heterostructure.
第10圖說明所提出之發光裝置的橫截面,其包含以一 10週期性之準晶體、無定型或其他複合有序或重覆蓋瓦配置 姓刻在η型攙雜GaN或InGaN層中的角錐體1 〇〇 1。倒角錐型 蓋瓦配置被設計提供讓捕陷的光耦合至光子晶體的布洛赫 模態中的分散帶。一旦光被耦合至布洛赫模態中,光子晶 體提供一使光耦合至自由空間内的手段。 15 第10圖所示之裝置包含一發光異質結構,該異質結構Figure 10 illustrates a cross-section of the proposed illumination device comprising a pyramid with a periodic periodic, amorphous or other composite ordered or heavy overlay tile profile engraved in an n-type doped GaN or InGaN layer. 1 〇〇1. The chamfered cone tiling configuration is designed to provide a dispersion band for the trapped light to couple into the Bloch mode of the photonic crystal. Once the light is coupled into the Bloch mode, the photonic crystal provides a means of coupling the light into the free space. 15 The device shown in Figure 10 comprises a luminescent heterostructure, the heterostructure
包括一 η-GaN或InGaN頂層1002以及一下方之p-型GaN或 InGaN層1004,並有一多重量子井(MQW)結構1003介於這 兩層之間。在p-型層104之下存在一反射層1005,該反射層 可為一DBR形式的金屬反射器,金屬諸如為銀,或全方向 2〇 反射器(ODR)形式。發光結構可被一載具基板或托板1〇〇6 支持。在一較佳實施例中,載具基板包括一具有一高導熱 性之導電材料諸如金屬或金屬合金或者矽或碳化矽中之 另外,光子晶體可由具有缺陷的區域,亦即倒角錐體 31 1342629 被移除或倒角錐體的形狀或大小被修正的區域所組成。子 區域亦可由具有未被钱刻之尖銳頂點區域所組成,引發: 成扁平頂部(截頭)倒角錐體。An η-GaN or InGaN top layer 1002 and a lower p-type GaN or InGaN layer 1004 are included, and a multiple quantum well (MQW) structure 1003 is interposed between the two layers. There is a reflective layer 1005 beneath the p-type layer 104, which may be a metal reflector in the form of a DBR, such as silver, or an omnidirectional 2 反射 reflector (ODR). The light emitting structure can be supported by a carrier substrate or pallet 1〇〇6. In a preferred embodiment, the carrier substrate comprises a conductive material having a high thermal conductivity such as a metal or a metal alloy or tantalum or tantalum carbide. The photonic crystal may be a defective region, that is, a chamfer cone 31 1342629 The area where the shape or size of the chamfered cone is removed or corrected. The sub-area may also consist of a sharp apex region that has not been engraved, triggering: a flat top (flip) chamfer.
圖形定義可由-些參數表示特性,包括定義成分隔二 5鄰接角錐體或倒角錐體中心之距離的晶格間距和角錐體結 晶學曝光面間所形成以及GaN晶格的水平結晶之間的角^ Θ。在本發明的—層面—_停止層_被用來控制^ 深度。此可允許角錐體基部直徑的正確控制。就一特定蝕 刻深度d而言,角錐體的基部直徑Φ是: 10 〇=2><d/tan(0)(5)The graphical definition may be characterized by a number of parameters, including the lattice spacing defined by the distance separating the two adjacent pyramids or the center of the chamfer cone and the angle formed between the crystallographically exposed faces of the pyramidal crystal and the horizontal crystallization of the GaN lattice. ^ Θ. At the level of the present invention - the stop layer _ is used to control the depth. This allows for proper control of the diameter of the base of the pyramid. For a specific etch depth d, the base diameter Φ of the pyramid is: 10 〇 = 2 ><d/tan(0)(5)
本發明的進一層面是一種具有上述倒角錐體型式之光 子帶結構的LED的簡化製造方法。一可能製造方法的兩種 變化繪示於第11A至11J圖。起始一η型攙雜GaN或1〇(}3]^層 11 〇 1藉金屬有機化學蒸汽沈積(MOCVD)或其他類似技術 15 (諸如MBE)生長在一晶格匹配的基質111〇上。一般所使用的 基質是藍寶石,GaN及SiC。在本發明的一個特別實施例 中,一由一材料諸如InGaN或AlGaN所形成的蝕刻停止層 409埋入n-GaN層中。n-GaN或InGaN層在蝕刻停止層上方持 續生長為層1108。多個GaN-InGaN量子井1102被生長且隨 2〇 繼一P-型GaN層1103。此一階段所製造的完整LED異質結構 疊層繪示於第11A圖。 如第11B圖所示,一反射鏡1104接著被沈積在p-GaN層 1103之頂部。反射器可以是金屬的,包括_層適當的金屬, 諸如藉由賤鍵或蒸鍵沈積的銀或金。或者,反射器可由一 32 1342629 J 呈分布反饋器(DBR)或全向反射器(ODR)形式之介電多層 堆疊所組成。此種構造可使用諸如PECVD之沈積技術以濺 鍍方式沈積。 如第11C圖所示,第11B圖的異質結構接著被結合於一 5 基質1105。該基質1105最好是一金屬合金,因金屬合金可 具有良好的導熱及導電性,但亦可由其他材料諸如SiC或Si 組成。在結合操作前可將另一些層沈積在反射鏡1104上以 輔助結合操作。A further aspect of the invention is a simplified method of fabricating an LED having the chamfer cone type photonic band structure described above. Two variations of a possible manufacturing method are shown in Figures 11A through 11J. The first n-type doped GaN or 1 〇 (}3] layer 11 〇1 is grown on a lattice-matched substrate 111 by metal organic chemical vapor deposition (MOCVD) or other similar technique 15 (such as MBE). The substrates used are sapphire, GaN and SiC. In a particular embodiment of the invention, an etch stop layer 409 formed of a material such as InGaN or AlGaN is buried in the n-GaN layer. n-GaN or InGaN layer A layer 1108 is continuously grown over the etch stop layer. A plurality of GaN-InGaN quantum wells 1102 are grown and followed by a P-type GaN layer 1103. The complete LED heterostructure stack fabricated in this stage is shown in 11A. As shown in Fig. 11B, a mirror 1104 is then deposited on top of the p-GaN layer 1103. The reflector may be metallic, including a layer of a suitable metal, such as deposited by a ruthenium bond or a vapor bond. Silver or gold. Alternatively, the reflector may consist of a dielectric multilayer stack in the form of a distributed feedback device (DBR) or an omnidirectional reflector (ODR) 32. The configuration can be sputtered using deposition techniques such as PECVD. Method of deposition. As shown in Figure 11C, the heterostructure of Figure 11B It is bonded to a 5 matrix 1105. The substrate 1105 is preferably a metal alloy, which may have good thermal and electrical conductivity, but may also be composed of other materials such as SiC or Si. Others may be combined prior to the bonding operation. A layer is deposited on the mirror 1104 to assist in the bonding operation.
• 在最後的習知製作步驟中,藍寶石基質1110接著利用 10 雷射剝離或其他的類似技術除去以提供如第11D圖中所示 之異質結構。雖然典型地可能並無蝕刻停止層,此一結構 仍可能形成一最終完成的習知裝置。雷射剝離程序使得 n-GaN層的表面1101粗縫。(典型地為50nm至300nm等級)。 在一個比較傳統的裝置中,此一表面可能更進一步被粗化 . 15 以改進光汲出。在本發明的一層面,光子帶結構角錐體的• In the final conventional fabrication step, the sapphire substrate 1110 is then removed using a 10 laser lift or other similar technique to provide a heterostructure as shown in Figure 11D. While there may typically be no etch stop layers, this configuration may still result in a well-formed conventional device. The laser lift-off procedure causes the surface 1101 of the n-GaN layer to be nicked. (typically on the order of 50 nm to 300 nm). In a more conventional device, this surface may be further roughened. 15 to improve light extraction. At one level of the invention, the photonic band structure has a pyramid
尺寸相形於表面粗糙度較大,因此在定義圖形之前不需要 _ 拋光表面。 - 第11E至111或11J圖表示依據本發明製作最終裝置時 所需要的增加程序步驟,如第11我和11J圖所示。就最後一 20 步驟示於第111圖之程序的的實施例而言,蝕刻停_止層1109 不存在於前述步驟11A至11H中,但存在於製成如第11J圖所 〆-- 示裝置的實施例中。 第11E圖表示掩蔽層之沈積。特別是一可取捨的方法步 驟示於圖中,藉以使一硬光罩層1106被沈積以供接著將需 33 1342629 要的圖形轉移至n.GaN層11()1。此可由_藉由MM㈣ 之_或帥4所組成’或其可為—藉由顧或諸沈積的 金屬。一層光阻劑1107接著被沈積在硬光罩U06上。然而, 在-些情況下可省卻硬光罩層而光阻劑⑽直接沈積至 5 n-GaN 層 1101 之上。The dimensions are similar to the surface roughness, so there is no need to _ polish the surface before defining the pattern. - Figures 11E to 111 or 11J show the additional program steps required to make the final device in accordance with the present invention, as shown in Figures 11 and 11J. With respect to the embodiment of the last step 20 shown in the procedure of FIG. 111, the etch stop layer 1109 is not present in the aforementioned steps 11A to 11H, but is present in the apparatus shown in FIG. 11J. In the embodiment. Figure 11E shows the deposition of the masking layer. In particular, a method of alternative method is shown in the figure whereby a hard mask layer 1106 is deposited for subsequent transfer of the pattern required by 33 1342629 to the n.GaN layer 11(). This may be made up of _ (by MM (4) or 帅4' or it may be - by deposition or deposition of metal. A layer of photoresist 1107 is then deposited on the hard mask U06. However, in some cases the hard mask layer can be omitted and the photoresist (10) deposited directly onto the 5 n-GaN layer 1101.
由於倒角錐㈣徵的尺寸大,纽劑贿可利用標譯 紫外線微影定義所需要的蓋瓦配置圖形。曝光區域的橫冷 形狀可對應於所需要之倒角錐體的橫截面,或可以是更窗 單的形狀諸如正方形。曝料紘_著«留下對鮮 所需倒角錐體頂點位置的分離材料島塊,如第HF圖所示 如果硬光罩11G6存在,則利細E、ICp或—類似程序乾食 刻。此一步驟將圖形定義由光阻劑n〇7轉移至硬光罩· 如第UGSI所示。剩餘的光阻劑術接著被剝離。 接著,n-GaN層蘭利用一等向性濕姓刻晶體濕链刻 如第圖所示。一較佳之祕刻⑽的方法是使用一浴泛 度範圍自室溫至loot的购_濃度範圍k〇h溶液。似 時間範圍大約在45分鐘左右。可選替的祕刻劑包含Na〇t 或时〇4。藉钱刻程序形成的六角形倒角錐體的晶面兔⑽ 、晶體的{ 10小"平面。他們與角錐體底部形成二角度 58.4。。最後,若—硬光罩概被使用,則其可利用—適當的 濕或乾钱刻程序除去而留下第】i ί圖中所示之最終結構。Due to the large size of the chamfer cone (4), the brix can be used to define the tiling pattern required for the definition of UV lithography. The transversely cold shape of the exposed area may correspond to the cross section of the desired chamfer cone, or may be a more window shaped shape such as a square. The 纮 着 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ This step transfers the graphic definition from photoresist n〇7 to the hard mask as shown in UGSI. The remaining photoresist is then peeled off. Next, the n-GaN layer is patterned using an isotropic wet-stained crystal wet chain as shown in the figure. A preferred method of secret engraving (10) is to use a one-bath range of solutions ranging from room temperature to loot. The time range is about 45 minutes. The optional secret agent contains Na〇t or 〇4. The crystal face rabbit (10) of the hexagonal chamfer cone formed by the money engraving program, and the {10 small " plane of the crystal. They form two angles with the bottom of the pyramid 58.4. . Finally, if a hard mask is used, it can be removed using a suitable wet or dry program to leave the final structure shown in the figure.
1515
被倒角錐體的絕對尺寸主要將被钱刻硬光罩區域的尺 寸所決定。硬光罩_長將提供停止障壁且且允許 GaN的頂表面(c平面)向下敍卿成倒角錐體。㈣錐體的 34 名義直徑將和在關硬光罩區域周長上任何㈣之間的最 大對向距離相等。其次,倒角錐體的直徑也由不同晶體的 平面的選擇性ϋ刻速率且因此由總钱刻時間決定。 在一可選替的實施例中,—蝕刻停止層,1109,被埋 置在層1101和1108之間的η型攙雜材料中。該触刻停止層包 含-諸如AlGaN ’ InGaN的材料,但亦可使用其他材料。钱 刻停止層1109之存在容許形成截頭㈣錐體(㈣錐體)且 亦容許對角錐型結構作正確控制同時㈣時間決定倒角錐 體的絕對直徑。第UJ圖之插人圖INSET顯示___ 結構的放大頂視圖。 第14圖所示為此一程序所製成之倒角錐體的一掃瞄式 電子顯微照片。在此-情況中,角錐體被隔離而且利用較 佳製作實施例形成,晶體的{10_M}小晶界面示於7⑴。 在較佳實施例中’包括層1101,11〇9和11〇8的複合 n-GaN上部區域1被設置在發光構造上方。因此,光從層丨丨 發出且在最後經由1101區域放出前經歷多重内部反射。 一個厚的n-GaN生長區域必需減少缺陷密度以便形成 高品質量子井(QW)層’且因而改善led的内部量子效率 為了製造上的利益’上部區域(層11〇1,U09和11〇8)作為脆 弱之QW區域Π02的一保護層,防止其在倒角錐體的濕蝕刻 期間受到損害且將Qw區域的表面復合極小化。對^^區域 之钱刻也會因減少最大有效發光區域而對led的總發光輸 出有不利影響。 另外,有關於光學及出之改進,所需要的倒角錐體尺 1342629 ^ 寸為1·75μηι之級度,直徑位於一2,5μηι之間距的中央。該尺The absolute size of the chamfered cone will be determined primarily by the size of the hard mask area. The hard mask _ long will provide a stop barrier and allow the top surface (c-plane) of GaN to be chamfered down into a chamfer cone. (d) The 34 nominal diameter of the cone will be equal to the maximum opposing distance between any (four) of the perimeter of the hard reticle area. Secondly, the diameter of the chamfer cone is also determined by the selective engraving rate of the plane of the different crystals and is therefore determined by the total time. In an alternate embodiment, an etch stop layer, 1109, is embedded in the n-type dopant material between layers 1101 and 1108. The etch stop layer contains a material such as AlGaN' InGaN, but other materials may also be used. The presence of the stop layer 1109 allows the formation of a truncated (four) cone ((4) cone) and also allows proper control of the pyramidal structure while (iv) time determines the absolute diameter of the chamfer cone. The insertion diagram of the UJ diagram INSET shows an enlarged top view of the ___ structure. Figure 14 shows a scanning electron micrograph of the chamfer cone made for this procedure. In this case, the pyramids are isolated and formed using a preferred fabrication embodiment, and the {10_M} crystallet interface of the crystal is shown at 7(1). In the preferred embodiment, the composite n-GaN upper region 1 comprising layers 1101, 11 〇 9 and 11 〇 8 is disposed over the luminescent structure. Therefore, light is emitted from the layer 且 and undergoes multiple internal reflections before being finally discharged through the 1101 area. A thick n-GaN growth region must reduce the defect density in order to form a high quality quantum well (QW) layer 'and thus improve the internal quantum efficiency of the LED for manufacturing benefits' upper region (layers 11〇1, U09 and 11〇8) As a protective layer of the fragile QW region Π02, it is prevented from being damaged during the wet etching of the chamfer cone and the surface recombination of the Qw region is minimized. The money engraving of the ^^ region also adversely affects the total luminous output of the LED by reducing the maximum effective illumination area. In addition, with regard to optical and improvement, the required chamfer cone 1342629 ^ inch is 1.75μηι, and the diameter is at the center of a distance of 2,5μη. The ruler
寸限制了層1101的最小厚度,因此角錐體最好位於厚的 n-GaN層上。同時,為了改進光汲出,藉蝕刻減少存在異質 結構中的捕陷模態數目以減少LED波導區域的總厚度。此 5可使光子帶結構與較大百分比的捕陷模態重疊,藉以提供 如第15圖中所示之進光汲出。另外,n_GaN也具高度傳導性 且此一性質使得需要沈積在光子帶結構頂部表面的獨立電 流傳佈層減至最少,該沈積之獨立電流傳佈層對裝置之光 ® 汲出有不利的影響。 10 數值模擬的成果繪示於第12A,12B和12C圖,說明典 型倒角錐型光子帶結構裝置的表現。z軸顯示與一具反射器 之非圖形化LED相較的總光汲出提高因素。成果沿^軸丨2〇2 繪成光子帶結構之間距(以〇111計)的函數。填充部分定義成 直徑/間距* 100。 • 15 第12A圖繪示一倒角錐型光子晶體與一具有底部反射The inch limits the minimum thickness of layer 1101, so the pyramid is preferably located on a thick n-GaN layer. At the same time, in order to improve the pupil output, the number of trap modes in the heterostructure is reduced by etching to reduce the total thickness of the LED waveguide region. This 5 overlaps the photonic band structure with a larger percentage of trapping modes to provide the exit pupil as shown in FIG. In addition, n-GaN is also highly conductive and this property minimizes the need for an independent current spreading layer deposited on the top surface of the photonic strip structure, which has a detrimental effect on the light exit of the device. The results of the numerical simulation are shown in Figures 12A, 12B and 12C, illustrating the performance of a typical chamfer cone photonic band structure. The z-axis shows the overall light output improvement factor compared to a non-patterned LED with a reflector. The result is plotted along the axis 丨2〇2 as a function of the distance between the photonic band structures (in 〇111). The fill portion is defined as diameter/pitch* 100. • 15 Figure 12A shows a chamfered cone photonic crystal with a bottom reflection
φ 裔之無圖形結構LED相較在一中央30。圓錐中的光汲出提 高。成果顯示對於一間距15〇〇nm及一填充部分1〇〇%,且在 一4=0.6/;111〜1311111:1之位置的()〜區域下方有一最佳化微 腔設計時,最大提高為4.90。這些參數相當於一以! _間 20距相間隔—具有約15叫倒角錐體直徑的裝置。 〃與在角錐形之例子中相同地使用- 2 D有限差分時域法 實把模擬,因此在本例中此一實驗結果亦被預期提供甚至 更大的光;:及出值。 第12B圖以晶格常數與填充部分兩數表示相較於一具 36 1342629 有一底部反射器的無圖形結構LED的光汲出提高。如第12A 圖中所示,成果的重點在於最佳操作範圍出現在一間距 1500nm且填充部分為100%’QWs之下具有一最佳化微腔設 計處。 5 最後’第12C圖表示—具有倒角錐型光子晶體結構之裝 置的光在30。圓錐中的百分比。如圖中所見,由裝置發出的 光高達39%可被導向於垂直於裝置表面具有一3〇。半角的中 心圓錐中。此相當於與一朗伯特發光敦置相較在一定向圓 錐中有多出57%的光。方向性增加是由於倒角錐體的有序 10排列以及倒角錐體的良好定義斜側壁。斜側壁與一般的直 側壁、蝕刻 '空氣桿相較可在30。圓錐内提供大約多出15% 的光。 第13圖為一倒角錐形結構在一平面上之光分布的橫戴 面。成果以沿X軸的遠場角1301的函數作圖且表示光強度 15 1302由一底部有一反射器之未具圖形LED對其歸一化。遠 場圖形是參考LED的表面垂直線。第13圖顯示晶格常數為 1500nm且角錐體直徑為150〇11111之LED的遠場圖形,該LED 的總光汲出提高至比一具有一反射器以及最佳化微腔之發 光裝置的2.98倍。在30。圓錐中的提高是4,85倍且30。圓錐中 20 含有總汲出光的38.6%。 下列表2就相同的綠色GaNLED設計成一包含蝕刻空 氣桿之一階光子晶體LED的簡單朗伯特發射器,以及設計 成一包含姓刻倒角錐體之角錐型光子晶體LEd,以總發射 光之百分比表示在一狹窄3〇。圓錐角内發射之光的比較。就 37 1342629 光子晶體裝置而言,尺寸被最佳化而在3〇。圓錐中及出最 百分比之光。一階光子晶體尺寸是由一間距為35〇 大約是210nm且蝕刻深度為120nm左右的晶格空 成’而倒角錐型光子晶體尺寸係如上所述。 1ΠΊ ’直役 氣椁所組The φ-like non-graphical LED is compared to a central 30. The light in the cone is raised. The results show that for a pitch of 15〇〇nm and a filled portion of 1〇〇%, and an optimized microcavity design below the ()~ region at a position of 4=0.6/;111~1311111:1, the maximum improvement Is 4.90. These parameters are equivalent to one! _ 20 spaced apart - a device having a diameter of about 15 chamfer cones. 〃 is the same as in the case of the pyramidal shape using the - 2 D finite-difference time-domain method, so in this case the experimental results are also expected to provide even larger light; and the value. Fig. 12B shows an increase in the optical output of the unpatterned LED having a bottom reflector compared to a 36 1342629 lattice constant and a filled portion. As shown in Figure 12A, the focus of the results is that the optimal operating range is at a pitch of 1500 nm and the fill portion is 100% 'QWs with an optimized microcavity design. 5 Finally, Figure 12C shows that the light having a chamfered cone-shaped photonic crystal structure is at 30. The percentage in the cone. As seen in the figure, up to 39% of the light emitted by the device can be directed to have a 3 垂直 perpendicular to the surface of the device. In the center cone of the half angle. This is equivalent to 57% more light in a directional cone than a Lambert illuminator. The increase in directivity is due to the ordered 10 arrangement of the chamfer cones and the well defined oblique side walls of the chamfer cone. The slanted side wall can be at 30 compared to a normal straight side wall and an etched 'air rod. Approximately 15% more light is provided inside the cone. Figure 13 is a cross-sectional view of the light distribution of a chamfered conical structure on a plane. The result is plotted as a function of the far field angle 1301 along the X-axis and indicates that the light intensity 15 1302 is normalized by a non-patterned LED with a reflector at the bottom. The far field pattern is the vertical line of the surface of the reference LED. Figure 13 shows the far-field pattern of an LED with a lattice constant of 1500 nm and a pyramidal diameter of 150〇11111. The total light output of the LED is increased to 2.98 times that of a light-emitting device having a reflector and an optimized microcavity. . At 30. The increase in the cone is 4,85 times and 30. 20 of the cone contains 38.6% of the total light emitted. Table 2 below shows the same green GaN LED as a simple Lambert emitter containing a one-step photonic crystal LED of an etched air rod, and a pyramidal photonic crystal LEd containing a chamfered pyramid, as a percentage of total emitted light. Expressed in a narrow 3 〇. A comparison of the light emitted within the cone angle. For the 37 1342629 photonic crystal device, the size is optimized at 3 〇. The most percentage of light is in the cone. The first-order photonic crystal size is a lattice free of a gap of 35 Å approximately 210 nm and an etch depth of approximately 120 nm and the chamfered cone photonic crystal size is as described above. 1ΠΊ ’ 直直气椁
表2 裝置類型 朗伯特LED 光子晶體LED 角錐^ 光在30°圓錐中 24.9 的百分比 34.9 38.6 如同所見,方向性之增加可在使用一更為優化的結構 中獲得。 第15A和15B圖說明當一光子帶結構以一微腔發光裝 10置最佳化時可達成的光汲出增加。本例中一間距為500nm 且有一簡單反射器之常規光子晶體與一間距相同但亦具有 一微腔反射器的倒角錐型光子晶體比較。在第15A與15B圖 中總體光提高1502以光子晶體填充部分1501之函數作圖。Table 2 Device Types Lambert LED Photonic Crystal LED Corner Cone ^ Light in a 30° Cone 24.9 Percentage 34.9 38.6 As can be seen, the increase in directivity can be achieved with a more optimized structure. Figures 15A and 15B illustrate the increase in pupil output that can be achieved when a photonic strip structure is optimized with a microcavity. In this example, a conventional photonic crystal having a pitch of 500 nm and having a simple reflector is compared with a chamfered cone photonic crystal having the same pitch but also having a microcavity reflector. The overall light increase 1502 in Figures 15A and 15B is plotted as a function of photonic crystal fill portion 1501.
在第15A圖中’實線15〇3表示一由具有一反射器的非圖 15 形化LED總光沒出增加歸一至輸出中。虛線1504代表兼具 有微腔與反射器的光子晶體與一具有一反射器之非圖形化 LED相較的總光及出提高。第15B圖突出由於微腔效應所獲 得之增加光汲出效果。虛線1505顯示當結合微腔、歸一化 至具有一反射器及一微腔的非圖形化LED時與實線1503相 20 較增加光子晶體的光沒出效果,顯示當從一僅具有一簡單 反射器的非圖形化LED歸一化至同一裝置時的結果。因此 結合效應所造成的差別增加清楚可見。 38 1342629In Fig. 15A, the solid line 15〇3 indicates that a total light from a non-illustrated LED having a reflector is added to the output to the output. Dotted line 1504 represents the total light and output enhancement of a photonic crystal having both a microcavity and a reflector compared to a non-patterned LED having a reflector. Figure 15B highlights the increased light extraction effect due to the microcavity effect. Dotted line 1505 shows that when combined with a microcavity, normalized to a non-patterned LED having a reflector and a microcavity, the photon illuminating effect of the photonic crystal is increased with the solid line 1503, and the display has only one simple The result of the non-patterned LED of the reflector normalized to the same device. Therefore, the increase in the difference caused by the combined effect is clearly visible. 38 1342629
熟習忒技藝的人士將可理解到本發明能使高效率及指 向性的發光裝置被貫現,因而令其可作為可能存在之光源 的實用替代光源。本發明在於角錐型突出部及倒角錐型蝕 刻以及其蓋瓦配置的精心設計,該一精心設計能產生一對 5有效光麵合最佳化的光子帶結構,同時能夠控制由裝置所 發出之光的傳佈及遠場性質。該裝置的實用性可藉提供一 间單的圖形久義與餘刻程序來製作該裝置而被提高,且該 裝置能夠容易地用來加強製作較傳統裝置的現存技術。ΛThose skilled in the art will appreciate that the present invention enables high efficiency and directivity of the illumination device to be achieved, thereby making it a useful alternative source of light for possible sources. The invention is based on the careful design of the pyramid-shaped protrusion and the chamfer-cone etching and the configuration of the tiling thereof, which is designed to produce a pair of 5 effective optical surface-optimized photonic band structures, and can control the device to emit The spread of light and the nature of the far field. The utility of the device can be enhanced by providing a single graphical long-term and residual program to make the device, and the device can be readily utilized to enhance existing techniques for making more conventional devices. Λ
【圖式簡單·明】 1〇 第1圖表示發明提出之裝置的-橫截面; 第2Α圖表示以—規則正方晶格排列的角錐體; 第2Β圖表示以_ 12次對稱性準晶體排列的角雜體; 第3圖以*子井鏡像間隔距離之函數表現―⑽ LED的常態化光照強度;[Simple and clear] 1〇 Figure 1 shows the cross-section of the device proposed by the invention; Figure 2 shows the pyramids arranged in a regular square lattice; Figure 2 shows the quasicrystals arranged in _ 12 symmetry The horn hybrid; Figure 3 is a function of the distance between the mirrors of the sub-wells - (10) the normalized illumination intensity of the LED;
第4A至4D圖繪示製作一 基礎的製造方法; 發光裝置以高速覆晶封裝為4A to 4D illustrate a manufacturing method for fabricating a foundation; the light-emitting device is packaged at a high speed flip chip
第5A圖表不對於—角錐型光子晶體·⑽而言,斑 2〇圖形結構之裝置相較光⑼提高-30。_; ' 第5B圖表不對於〜角錐型光子晶體-LED而言,愈一叙 圖形結構之裝置相較總 *''' 第冗圖表示對於不同的角錐型光子晶體 在3〇。圓錐中之光的百分tt; m 39 1342629 第6A圖表示對一依據本發明一較佳實施例之光子晶體 -LED構造的遠場圖形; 第6B圖繪示為依據身本發明另一較佳實施例之光子晶 體-LED結構的遠場圖形; 5 第7A圖出示使用發明的製作方法被形成的隔離角錐體 的一電子顯微影像圖; 第7B圖繪示使用本發明的製作方法被形成的一角錐體 的光子準晶體配置的電子顯微影像圖;The 5A chart is not for the pyramidal photonic crystal (10), and the device of the speckle pattern is increased by -30 compared to the light (9). _; 'The 5B chart is not for the ~ pyramidal photonic crystal-LED, the more detailed the structure of the device compared to the total *''''''''''''''' The percentage of light in the cone tt; m 39 1342629 Figure 6A shows a far field pattern of a photonic crystal-LED structure according to a preferred embodiment of the present invention; Figure 6B shows another comparison according to the invention. The far field pattern of the photonic crystal-LED structure of the preferred embodiment; 5 Figure 7A shows an electron micrograph of the isolated pyramid formed using the fabrication method of the invention; Figure 7B shows the fabrication method using the method of the present invention. An electron micrograph of the photon quasi-crystal configuration of the formed pyramid;
第8A圖是一習知光子晶體-LED與一具有微腔之角錐 10型光子晶體-led相較於一無圖形結構LED的光汲出提高對 光子晶體填充部分之一圖形; 第8B圖是一角錐型光子晶體-LED相較於具有及不具 有微腔之無圖形結構LED的光汲出提高對光子晶體填充部 分之一圖形;以及, 15 第9圖是一角錐型光子晶體-LED相較於一無圖形結構 LED的的光汲出提高對LED異質結構核心厚度的圖形。Figure 8A is a diagram showing a pattern of a photonic crystal-filled portion of a conventional photonic crystal-LED and a pyramid-shaped photonic crystal-led having a microcavity compared to a non-patterned LED; FIG. 8B is a diagram The pyramidal photonic crystal-LED has a pattern of filling the photonic crystal with respect to the light-emitting of the non-patterned LED with and without the microcavity; and, Fig. 9 is a pyramidal photonic crystal-LED compared to The light exit of a non-graphical LED increases the pattern of the core thickness of the LED heterostructure.
第10圖繪示倒角錐型裝置之一橫截面; .第11A至11D圖說明製作一發光裝置之一高速覆晶封 裝程序為基礎的製造方法; 20 第11E圖至111圖說明在第11J圖所示之裝置的上層中 製作一倒角錐型或截頭倒角錐型光子晶體構造之附加製造 步驟; 第12A圖繪示一角錐型光子晶體-LED與一無圖形結構 裝置相較在一 30。圓錐中的光汲出提高。 40 1342629 •‘ 第12B圖繪示一角錐型光子晶體-LED與一無圖形結構 裝置相較的總光汲出提高; 第12C圖繪示不同的角錐型光子晶體發光裝置在30°圓 錐中之光的百分比; 5 第13圖繪示依據本發明之一較佳實施例的光子晶體 -LED構造的遠場圖形特性曲線; 第14圖繪示一使用本發明的製作方法被形成的隔離倒 角錐體的的角錐體的一電子顯微影像圖;Figure 10 is a cross-sectional view showing one of the chamfered cone-shaped devices; Figure 11A to Figure 11D illustrate a manufacturing method based on a high-speed flip chip packaging process for fabricating a light-emitting device; 20 Figure 11E to Figure 111 illustrates the image in Figure 11J An additional manufacturing step of forming a chamfered or truncated cone-shaped photonic crystal structure in the upper layer of the device is shown; Figure 12A shows a pyramidal photonic crystal-LED compared to a non-graphical device. The light in the cone increases. 40 1342629 • ' Figure 12B shows the increase in total light output of a pyramidal photonic crystal-LED compared to a non-patterned device; Figure 12C shows the light of a different pyramidal photonic crystal illuminator in a 30° cone Percentage; 5 Figure 13 illustrates a far field pattern characteristic of a photonic crystal-LED configuration in accordance with a preferred embodiment of the present invention; and Figure 14 illustrates an isolated chamfer formed using the fabrication method of the present invention. An electron micrograph of the pyramid;
• 第15A圖是一習知光子晶體-LED與一具有微腔之角錐 10 型光子晶體-LED相較於一無圖形結構LED的光汲出提高對 光子晶體填充部分之一圖形; 第15B圖是一倒角錐型光子晶體-LED相較於一具有及 不具有微腔之無圖形結構LED的光汲出提高對光子晶體填 充部分之一圖形。• Figure 15A is a diagram of a conventional photonic crystal-LED with a microcavity pyramid type 10 photonic crystal-LED compared to a non-patterned LED to enhance the filling of the photonic crystal; Figure 15B is A chamfered cone photonic crystal-LED enhances the pattern of one of the photonic crystal fill portions compared to a light exit of an unpatterned LED with and without a microcavity.
15 【主要元件符號說明】 101...角錐體 403...ρ-型層 102...頂層 404...反射鏡 103...多重量子井結構 405...基質 104...p-型層 406...硬光罩層 105...反射層 407…光阻劑層 106...載片 408...層 107...蝕刻停止層 409...餘刻停止層 401...η-型携;雜層 410...藍寶石基質 402...多重量子井 1001...角錐體 41 1342629 ' 1004...p-型層 1005.. .反射層 1006.. .托板 1101.. . η型攙雜層 1102.. .GaN-InGaN 量子井 1103.. .p-型層 1104.. .反射鏡 1105.. .基質 1106.. .硬光罩層 1107.. .光阻劑 1109.. .蝕刻停止層 1110.. .基質15 [Description of main component symbols] 101...Corner 403...p-type layer 102...top layer 404...reflector 103...multiple quantum well structure 405...matrix 104...p - Type layer 406... Hard mask layer 105... Reflective layer 407... Photoresist layer 106... Slide 408... Layer 107... Etch stop layer 409... Remaining stop layer 401 ...η-type carrying; heterogeneous layer 410...sapphire matrix 402...multiple quantum wells 1001...corner cones 41 1342629 '1004...p-type layer 1005...reflective layer 1006.. . Pallet 1101.. n-type doping layer 1102.. GaN-InGaN quantum well 1103..p-type layer 1104.. mirror 1105.. substrate 1106.. hard mask layer 1107.. Photoresist 1109.. Etch stop layer 1110.. substrate
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