200929758 九、發明說明： 【發明所屬之技術領域】 本發明係有關一種可電激發面射型雷射（VCSEL)及其製作方法，特別 是指一種具備透明電極及無裂縫氮化鋁/氮化鎵系列反射鏡之可電激發面 射型雷射及其製作方法。 【先前技術】 為了實現高反射率、高品質的可電激發面射型雷射，有學者藉由設計 不同大小(aperature size)的電流阻絕層來達到雷射所需的臨界電流密 Q 度，或是使用不同的材料交互堆疊沈積形成的布拉格反射鏡（DBR)，如氮 化鋁及氮化鎵（AlN/GaN)或氮化鋁鎵及氮化鎵（AlGaN/GaN)等材料，或 是使用不同的結構減少因電流耗損產生熱效應。 如美國專利第6233267號所揭露之一種垂直共振腔面射型雷射，主要 是利用黃光微影技術將下層的布拉格反射鏡的沈積區域定義出來再鍍上介 電值布拉格反射鏡，然後以金屬有機氣相沈積法（M0CVD)成長η型氮化鎵 (GaN)，並在此區域中加入氮化矽(Si3N4)或氧化矽(Si〇2)形成電流阻絕層， Q 使電流密度可以大幅的提升而達到雷射所需的電流密度，之後，再繼續成 長主動發光層（MQW)及p型氮化鎵，最後，再將上層介電值布拉格反射鏡沈 積在元件上形成雷射共振腔，達到可電激發的藍光面射型雷射。此方法由 於上、下層介電質布拉格反射鏡均需外界支援，加上再成長（regrowth) 的技術，以及外部的電流注入方式均使製程及磊晶的困難度相對提高許 多’而此結構缺少電流擴散層的效果，如何獲得預期的元件特性亦有一定 的困難度，在未來的應用上勢必會存在著技術移轉上的問題。 5 200929758 【發明内容】 蓉於以上的問題’本發_主要目的在概供—種具備義電極及無 裂⑽/氮化鎵細反概之可電激發面_及其雜方法，乃利 帛超晶格結構釋放張應力，達顯除裂縫’並藉由電流阻㈣有效控制電 流集中，以及利用透明電極增加電流擴散效率，其具有高透光性與高電導 率，因此能提升整體效率。 本發明所揭露之具備透明電極及無裂縫氮化銘化嫁系列反射鏡之 〇可電激發面射型雷射，糊金財機化學IU目沈積法⑽GVD)製作出下層布 拉格反射鏡結構’並經由外部形成上層介電值布㈣反射賴構而構成藍 光面射型雷射。由於下層雜格反射鏡結構使贱她/氮化鎵的多層結構 穿插使贱魅/氮化鎵的超晶格、轉，可達顺職並且·最少的層數 而達到最佳的反射率及反射區段（st〇p band)，因此有效的降低蟲晶的困 難度。再者’本發明利用黃光微影技術或離子佈值方式形成電流阻絕層， 可以有效的減少漏電流的產生，增加發光效率。另外，本發明在形成上層 〇布拉格反射鏡結構之前，以透明導電玻璃取代傳統使用鎳金(Ni/Au)合金做 為電流擴散層，此方法可以有效的提升義度，更可以齡吸收並且增加 發光效率，在未來的藍光面射型雷射的應用上具有相當大的潛力。 為使對本發明的目的、特徵及其功能有進一步的了解，茲配合圖式詳 細說明如下： 【實施方式】 清參見第1A圓~第1H圖，為本發明之實施例所提供之具備透明電極及 無裂縫氮化紹/氮化鎵系列反射鏡之可電激發面射型雷射的製作流程。以下 6 200929758 詳細說明各個步驟。 首先’如第u圖所示，將藍寶石基板10置入金屬有機化學氣相沈積 設備’先在謂。(:之高溫與氫氣氣氛下去除基板1〇表面的雜質5分鐘。然 後’降溫到5GGt，成長3〇奈米（nm)的_ u，再於緩衝層u上成 長2微米（卿）的氮化鎵層12。成長壓力為_托耳（τ〇γγ)，底座旋轉速 度為每分鐘900轉。 如第1Β®柄，躲纽錢氣下絲⑽鎵/氮她之第一布 〇拉格反射鏡結構20與超晶格結構3〇。其載氣氣體流量為氮氣/氣氣 =4200/· ，成長Μ力為⑽托耳，成長溫度為ii()(rc，且根據成長 速率來控纖長成長速率是以雷射姆干涉方式制，確保每一層 厚度為光學厚度1/4波長。第-布拉格反射鏡結構2〇是由交錯成長的氣化 鎵反射層與氮化銘反射層所構成，而本實施例每成長一組第—布拉格反射 鏡結構20，會再接著成長-組超晶格結構3〇。每一組超晶格結構3〇是由 -超晶格層31和-氮化鎵層32構成，超晶格層31可包含氮脑、氮化鎵 〇或氮化銘鎵系列材料之超晶格層，本實施例之超晶格層31則是由5 5週期 的氮化鋁超晶格層和氮化鎵超晶格層構成，且兩邊為薄的氮化鋁超晶格 層’確保邊界是由氮化銘向氛化鎵過渡。 至於每一組第一布拉格反射鏡結構2〇是由多少對的i化銘反射層和氮 化鎵反射層所構成，主要看裂缝出現的情況而確定。本實施例在成長五對 的氮化鋁反射層和氮化鎵反射層沒有裂縫，但是在成長十對的氮化鋁反射 層和氮化鎵反射層出現了裂縫，所以本實施例以每五對的氮化鋁反射層和 7 200929758 氮化鎵反射層構成一組第一布拉格反射鏡結構20。 如第1C圖所示，整個結構40係利用金屬有機氣相沈積法沈積出氮化 鋁與氮化鎵交互疊加25對的布拉格反射鏡（也就是五組第一布拉格反射鏡 結構20)，並穿插使用了四組的氮化鋁跟氮化鎵的超晶格結構30。 接著’如第1D圖所示，再成長380奈米的η型氮化鎵層50、10奈米 的多層量子井結構之主動發光層51，量子井結構包含1〇對的氮化銦鎵/氮 化鎵（In〇_2Ga〇.IGaN)(厚度為2.5奈米/7.5奈米），以及成長1〇〇奈米的 0 P型氮化鎵層52以形成3 λ厚的共振腔。 如第1Ε圖所示’利用電漿輔助化學氣相沈積（pECVD)成長〇 6微米 的二氧化矽（Si〇2)層’並且利用黃光微影技術定義出蝕刻區域與未钱刻區 域’放至電感耦合電漿式反應性離子蝕刻系統中進行姓刻，通入氣氣/氬氣 (Ch/Ar)，施加的電漿與偏壓功率為13.56 MHz。將p型氮化鎵層52、主 動發光層51及部分η型氮化鎵.層50之一側蚀刻去除，並露出η型氮化鎵 層50。 Ο 如第1F圖所示，在定義電流注入區域61部分，可以使用沉積0.3微 米氮化矽（SiNx)或二氧化矽（Si〇2)作為電流阻絕層6〇，並且用黃光微 影技術定義或者使用摻雜鎂離子定義此區域，用以集中電流。 如第1G圖所示’利用電子束微影定義出金屬電極區域，於電流注入區 域61與露出的η型氮化鎵層50上分別鍍上透明電極70與η型歐姆接觸電 極80，再於電流阻絕層60與透明電極70之鄰接處上鍍上ρ型歐姆接觸電 極81。而透明電極70使用氧化銦錫（ΙΤ0)或二氧化錫（Sn〇2)，ns歐姆接 8 200929758 觸電極80使用鈦/鋁/鎳/金（Ti/Al/Ni/Au) (20/150/20/200奈米），p型 歐姆接觸金屬81使用鎳/金（Ni/Au) (20/150奈米）。 最後’如第1H圖所示，使用電子搶（E-GUN)鍍上六對交疊的二氧化 石夕（Si〇2)反射層與二氧化鈦（Ti〇2)反射層構成高反射率的第二布拉格反 射鏡結構90。 根據本發明所揭露之具備透明電極及無裂縫氮化銘/氮化鎵系列反射 鏡之可電激發面射型雷射及其製作方法，利用沈積於無裂縫的氮化鋁及氮 〇 化鎵的布拉格反射鏡上***氮化鋁/氮化鎵超晶格結構來釋放張應力，從而 有效消除張應力引起的裂縫，而這些超晶格結構與反射鏡的成長方式是一 樣的’僅需藉由控制成長時間來得到所需的超晶格結構，而每組超晶格結 構對於被反射的光來說相當於一層低折射率的氮化鋁鎵薄膜，可用較少的 層數獲得高反射率及反射區段的反射鏡。而加入電流阻絕層可以有效阻絕 電流，造成只有局部區域有電流通過，可以有效控制電流集中，達到有效 共振。另外’本發明利用透明電極增加電流擴散效率’由於透明電極具有 〇 高透光性以及高電導率，因此能提升整體效率。 本發明乃適用於所有成長自藍寶石基板(Sapphire)、碳化石夕(SiC)、氧 化鋅(ZnO)或矽（Si)基板之反射鏡，並適用於所有以金屬有機化學氣相蟲 晶(M0CVD)、氫化物氣相磊晶(HVPE)、分子束磊晶(MBE)或熱壁磊晶(h〇t㈣i epitaxy)方法成長氮化鎵系列之反射鏡及可電激發面射型雷射。 雖然本發明以前述之實施例揭露如上，然其並非用以限定本發明。在 不脫離本發明之精神和範圍内，所為之更動與潤飾，均屬本發明之專利保 200929758 護範圍。關於本發明所界定之保護範圍請參考所附之申請專利範圍。 【圖式簡單說明】 第1Α圖〜第1Η圖係為本發明之實施例所提供之具備透明電極及無裂縫氣化 銘/氮化鎵系列反射鏡之可電激發面射型雷射的製作流程。 【主要元件符號說明】 10基板 11緩衝層 12氮化鎵層 20第一布拉格反射鏡結構 3〇超晶格結構 31超晶格層 32氮化嫁層 4〇穿插使用超晶格結構的第一布拉格反射鏡結構 50 η型氮化鎵層 51主動發光層 52 Ρ型氮化鎵層 6〇電流阻絕層 61電流注入區域 7〇透明電極 8〇 η型歐姆接觸電極 81 Ρ型歐姆接觸電極 90第二布拉格反射鏡結構200929758 IX. The invention relates to: an electro-excitable surface-emitting laser (VCSEL) and a manufacturing method thereof, in particular to a transparent electrode and a crack-free aluminum nitride/nitriding An electrically excitable surface-emitting laser of a gallium series mirror and a manufacturing method thereof. [Prior Art] In order to achieve high reflectivity and high quality electrically excitable surface-emitting lasers, some scholars have designed a current-resistance layer of different size to achieve the critical current density Q required for lasers. Or alternately stacking deposited Bragg mirrors (DBR) using different materials, such as aluminum nitride and gallium nitride (AlN/GaN) or aluminum gallium nitride and gallium nitride (AlGaN/GaN), or Use different structures to reduce thermal effects due to current consumption. A vertical cavity surface-emitting laser as disclosed in U.S. Patent No. 6,233,267, mainly uses a yellow lithography technique to define a deposition region of a lower Bragg mirror and then plate a dielectric value Bragg mirror, and then metal organic Vapor deposition (M0CVD) is used to grow n-type gallium nitride (GaN), and in this region, tantalum nitride (Si3N4) or yttrium oxide (Si〇2) is added to form a current blocking layer, and Q can greatly increase the current density. After reaching the current density required for the laser, the active light-emitting layer (MQW) and the p-type gallium nitride are further grown, and finally, the upper dielectric value Bragg mirror is deposited on the element to form a laser cavity. An electrically excited blue surface-emitting laser. This method requires external support for both the upper and lower dielectric Bragg mirrors, plus the regrowth technique and the external current injection method, which make the process and the difficulty of epitaxy relatively improved. The effect of the current diffusion layer is also difficult to obtain the expected component characteristics. In the future application, there will be problems in technology transfer. 5 200929758 [Summary of the Invention] The problem of the above is the 'main purpose _ the main purpose is to provide a kind of electrode with non-cracking (10) / gallium nitride fine anti-electrical excitation surface _ and its hybrid method, The superlattice structure releases tensile stress, shows the removal of cracks, and effectively controls current concentration by current resistance (4), and increases current spreading efficiency by using transparent electrodes, which has high light transmittance and high electrical conductivity, thereby improving overall efficiency. According to the invention, the transparent electrode and the crack-free nitriding etched series mirror can be electrically excited by the surface-emitting laser, and the IU mesh deposition method (10) GVD) is used to fabricate the underlying Bragg mirror structure. A blue surface-emitting laser is formed by externally forming an upper dielectric value cloth (four) reflecting structure. Due to the lower layer of the mirror structure, the multilayer structure of her/GaN is interspersed to make the super-lattice, turn, and the minimum number of layers of the enchanting/gallium nitride to achieve the best reflectivity and The reflection zone (st〇p band) is therefore effective in reducing the difficulty of the insect crystal. Furthermore, the present invention utilizes a yellow lithography technique or an ion cloth value method to form a current blocking layer, which can effectively reduce the generation of leakage current and increase the luminous efficiency. In addition, the present invention replaces the conventional use of nickel-gold (Ni/Au) alloy as a current diffusion layer by transparent conductive glass before forming the upper layer 〇 Bragg mirror structure, and the method can effectively improve the degree of symmetry, and can absorb and increase in age. Luminous efficiency has considerable potential for future applications of blue-emitting lasers. In order to further understand the objects, features and functions of the present invention, the following detailed description will be made with reference to the following drawings: [Embodiment] Referring to the 1A- 1H figure, a transparent electrode provided in an embodiment of the present invention is provided. And the production process of the electrically excitable surface-emitting laser with no cracking nitride/GaN gallium mirror. The following 6 200929758 details the steps. First, as shown in Fig. u, the sapphire substrate 10 is placed in a metal organic chemical vapor deposition apparatus. (: The high temperature and hydrogen atmosphere remove the impurities on the surface of the substrate 1 for 5 minutes. Then 'cool down to 5GGt, grow 3 〇 nanometer (nm) _ u, then grow 2 micron (clear) nitrogen on the buffer layer u Gallium layer 12. The growth pressure is _Torr (τ〇γγ), and the rotation speed of the base is 900 rpm. For example, the first Β® handle, hiding the money, the wire (10) gallium/nitrogen, the first cloth 〇rag The mirror structure 20 and the superlattice structure 3〇 have a carrier gas flow rate of nitrogen/gas = 4200/·, a growth force of (10), and a growth temperature of ii() (rc, and are controlled according to the growth rate). The slender growth rate is made by the laser interference method, ensuring that each layer has a thickness of 1/4 wavelength of optical thickness. The first-Bragd mirror structure 2〇 is composed of a staggered vaporized gallium reflective layer and a nitrided reflective layer. In the present embodiment, each time a set of the first Bragg mirror structure 20 is grown, the growth-group superlattice structure 3〇 is further connected. Each group of superlattice structures 3〇 is composed of a superlattice layer 31 and a nitrogen. The gallium layer 32 is formed, and the superlattice layer 31 may comprise a superlattice layer of a nitrogen brain, a gallium nitride or a nitrided gallium series material. The superlattice layer 31 is composed of a 5 5 cycle aluminum nitride superlattice layer and a gallium nitride superlattice layer, and a thin aluminum nitride superlattice layer on both sides ensures that the boundary is nitrided. Intermining the transition to the gallium arsenide. As for each set of the first Bragg mirror structure 2〇 is composed of a number of pairs of i-type reflective layer and gallium nitride reflective layer, mainly determined by the occurrence of cracks. There are no cracks in the five pairs of the aluminum nitride reflective layer and the gallium nitride reflective layer, but cracks occur in the ten pairs of the aluminum nitride reflective layer and the gallium nitride reflective layer, so the present embodiment has five pairs of nitrogen. The aluminum reflective layer and the 7 200929758 gallium nitride reflective layer form a set of first Bragg mirror structures 20. As shown in FIG. 1C, the entire structure 40 is deposited by metal organic vapor deposition to form aluminum nitride and gallium nitride. 25 pairs of Bragg mirrors (ie, five sets of first Bragg mirror structures 20) are alternately superimposed, and four sets of aluminum nitride and gallium nitride superlattice structures 30 are interspersed. Next, as shown in FIG. 1D Show, then grow 380 nm of η-type gallium nitride layer 50, 10 nanometers The active light-emitting layer 51 of the quantum well structure, the quantum well structure comprises a pair of indium gallium nitride/gallium nitride (In〇_2Ga〇.IGaN) (thickness of 2.5 nm / 7.5 nm), and growth 1 0 Nano's 0 P-type gallium nitride layer 52 to form a 3 λ thick resonant cavity. As shown in Fig. 1 'Using plasma-assisted chemical vapor deposition (pECVD) to grow 〇 6 μm of cerium oxide (Si) 〇 2) layer 'and use the yellow lithography technology to define the etched area and the unetched area' into the inductively coupled plasma reactive ion etching system for surname, gas/argon (Ch/Ar), The applied plasma and bias power is 13.56 MHz. One side of the p-type gallium nitride layer 52, the active light-emitting layer 51 and a portion of the n-type gallium nitride layer 50 is etched away, and the n-type gallium nitride layer 50 is exposed. . Ο As shown in Figure 1F, in the definition of the current injection region 61, 0.3 micron lanthanum nitride (SiNx) or cerium oxide (Si 〇 2) may be deposited as the current blocking layer 6 〇 and defined by yellow lithography or This region is defined using doped magnesium ions to concentrate the current. As shown in FIG. 1G, the metal electrode region is defined by electron beam lithography, and the transparent electrode 70 and the n-type ohmic contact electrode 80 are respectively plated on the current injection region 61 and the exposed n-type gallium nitride layer 50, and then A p-type ohmic contact electrode 81 is plated on the adjacent side of the current blocking layer 60 and the transparent electrode 70. The transparent electrode 70 uses indium tin oxide (ΙΤ0) or tin dioxide (Sn〇2), ns ohms 8 200929758, and the contact electrode 80 uses titanium/aluminum/nickel/gold (Ti/Al/Ni/Au) (20/150). /20/200 nm), p-type ohmic contact metal 81 uses nickel/gold (Ni/Au) (20/150 nm). Finally, as shown in Figure 1H, six pairs of overlapping dioxide (Si〇2) reflective layers and titanium dioxide (Ti〇2) reflective layers are coated with E-GUN to form a high reflectivity. Two Bragg mirror structures 90. An electrically excitable surface-emitting laser having a transparent electrode and a crack-free nitride/GaN gallium mirror disclosed in the present invention and a method for fabricating the same, using aluminum nitride and gallium nitride deposited without cracks Inserting an aluminum nitride/gallium nitride superlattice structure on the Bragg mirror to release tensile stress, thereby effectively eliminating cracks caused by tensile stress, and these superlattice structures are grown in the same way as mirrors. The desired superlattice structure is obtained by controlling the growth time, and each set of superlattice structure is equivalent to a low refractive index aluminum gallium nitride film for the reflected light, and high reflection can be obtained with a small number of layers. The mirror of the rate and reflection section. Adding a current blocking layer can effectively block the current, causing only a local area to pass current, which can effectively control the current concentration and achieve effective resonance. Further, the present invention utilizes a transparent electrode to increase current spreading efficiency. Since the transparent electrode has high light transmittance and high electrical conductivity, the overall efficiency can be improved. The invention is applicable to all mirrors grown from sapphire, SiC, zinc oxide (ZnO) or bismuth (Si) substrates, and is applicable to all metal organic chemical vapor crystals (M0CVD). ), hydride vapor epitaxy (HVPE), molecular beam epitaxy (MBE) or thermal wall epitaxy (h〇t (tetra) i epitaxy) method to grow gallium nitride series of mirrors and electrically excited surface-emitting lasers. Although the present invention has been disclosed above in the foregoing embodiments, it is not intended to limit the invention. The modifications and retouchings are within the scope of the patent protection 200929758 of the present invention without departing from the spirit and scope of the present invention. Please refer to the attached patent application for the scope of protection defined by the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to FIG. 1 are diagrams showing the fabrication of an electrically excitable surface-emitting laser having a transparent electrode and a crack-free gasification/GaN gallium mirror provided by an embodiment of the present invention. Process. [Major component symbol description] 10 substrate 11 buffer layer 12 gallium nitride layer 20 first Bragg mirror structure 3 〇 superlattice structure 31 superlattice layer 32 nitriding layer 4 〇 interspersed with the use of superlattice structure Bragg mirror structure 50 η-type gallium nitride layer 51 active light-emitting layer 52 Ρ-type gallium nitride layer 6 〇 current blocking layer 61 current injection region 7 〇 transparent electrode 8 〇 n-type ohmic contact electrode 81 Ρ type ohmic contact electrode 90 Two Bragg mirror structure