TWI229379B

TWI229379B - Method and solution for selectively etching III-V semiconductor

Info

Publication number: TWI229379B
Application number: TW93105099A
Authority: TW
Inventors: Yeong-Her Wang; Chin-I Liao; John Liu; Mau-Phon Houng; Chien-Liang Lin
Original assignee: Yeong-Her Wang; Chin-I Liao; John Liu; Mau-Phon Houng; Chien-Liang Lin
Priority date: 2004-02-27
Filing date: 2004-02-27
Publication date: 2005-03-11
Also published as: TW200529309A

Abstract

A method for selectively etching III-V semiconductor is disclosed to etch a GaAs layer on an AlGaAs layer of a semiconductor substrate with high selectivity. Firstly an etching solution is prepared, that comprises citric acid, hydrogen peroxide and water. Volume percent of the hydrogen peroxide is higher than volume percent of the citric acid, and is between 0.2-0.3 times the volume percent of the wafer. Therefore, there is a dominant progress to etch the GaAs layer with high etching selectivity over AlGaAs and lower etching rate.

Description

1229379 五、發明說明（1) 【發明所屬之技術領域】本發明係有關於一種I I I — V族半導體之選擇性触刻方 ' 法’特別係有關於一種在含鋁量係不超過30%之砷化鋁鎵 . 層〔A 1 G a A s〕上選擇性敍刻坤化鎵層〔◦ a a s〕之方法及其 ’ 使用之溶液。 ' ‘ 【先前技術】 I I I - V族半導體裝置係可廣泛運用在假型高速電子移動電日日體〔pseudomorphic high electron mobility transistor，PHEMT〕、異質接面雙載子電晶體〔hetero junction bipolar transistors，HBT〕、發光馨二極體裝置〔light emitting diodes，LED〕及雷射裝置〔laser〕等產品，而i丨丨—v族半導體裝置在製程上仍有可改進之處，特別是在選擇性蝕刻製程。 •習知II I -V族半導體裝置之選擇性蝕刻方法係可區分為氣相選擇性離子蝕刻〔selective reactive i〇n etching〕與選擇性濕式化學蝕刻〔selective wet chemical etching〕，其中在氣相選擇性離子蝕刻方法中所產生之離子羼擊〔i〇rl bombardment〕仍會些許影響 111 -V族半導體裝置之光電特性，甚至會導致不當之損傷’此外’氣相選擇性離子蝕刻設備如氣體儲存塔、氣體_ 輸送管與離子化反應腔均相當昂貴。然而選擇性濕式化學蝕刻方法雖有簡單、低成本、降低產品損傷等優點，但在實際製程操作上仍有諸多待克服的問題，當以選擇性濕式化學蝕刻方法移除一丨i丨—v族半1229379 V. Description of the invention (1) [Technical field to which the invention belongs] The present invention relates to a method of selective etching of a III-V semiconductor, and particularly to a method in which the aluminum content does not exceed 30%. Method for selectively engraving the gallium layer [◦ aas] on the layer [A 1 G a A s] and its solution. '' [Prior art] III-V semiconductor devices are widely used in pseudomorphic high electron mobility transistors (PHEMT), hetero junction bipolar transistors, HBT], light emitting diodes (LED) and laser devices [laser], and i 丨丨 -v semiconductor devices can still be improved in the manufacturing process, especially in selective Etching process. • The conventional selective etching methods of II-V semiconductor devices can be divided into selective reactive ion etching in the gas phase and selective wet chemical etching, in which The ion bombardment produced by the phase selective ion etching method will still slightly affect the optoelectronic characteristics of 111-V semiconductor devices, and even cause improper damage. In addition, gas phase selective ion etching equipment such as Gas storage towers, gas_pipes, and ionization chambers are all quite expensive. However, although the selective wet chemical etching method has the advantages of simplicity, low cost, and reduced product damage, there are still many problems to be overcome in actual process operations. When the selective wet chemical etching method is used to remove a 丨 i 丨—V family half

第7頁 1229379Page 7 1229379

導體裝置之神仆错r Γ» Λ 、 + .,_ a 鎵曰 GaAS 日寸，應注意不可移除在爷础化鎵層下方之砷化钮你s 秒陈社4申在銘…* & Y 層 As〕，目前已確定的是， =除在，化紹鎵層上之砂化鎵層之敍刻溶液比較上，梓上軋水之蝕刻液將比磷酸/雙氧水蝕刻液與氨水/雙丁乳水蝕刻液更具有較佳蝕刻選擇性〔etching s e 1 e c t i v i t y〕與較平坦的餘刻表面，但只有將砷化鋁鎵層之含鋁量高於30%以上才能使得檸檬酸/雙氧水蝕刻液罝有100以上之蝕刻選擇性比值，但如此高的含紹量卻改變、了 I I I -V族半導體元件之電氣特性並影響元件的可靠度〔請參考Y. Uenishi，H. Tanaka，andH. Ukita，The god of the conductor device is wrong r Γ »Λ, +., _ A Gallium is the GaAS daily inch. It should be noted that the arsenic button below the primary basal gallium layer cannot be removed. You s seconds Chen She 4 Shen Zai Ming ... * & Y Layer As], it has been determined at present that, = In addition to the comparison of the etched solution of the gallium sand layer on the chemical gallium layer, the etchant of the rolling water on the silk will be more than the phosphoric acid / hydrogen peroxide etchant and ammonia / dibutyl Emulsion etchants have better etch selectivity and flatter etched surface, but only when the aluminum content of the aluminum gallium arsenide layer is higher than 30% can the citric acid / hydrogen peroxide etchant be made.罝 There is an etching selectivity ratio of more than 100, but such a high content changes the electrical characteristics of III-V semiconductor devices and affects the reliability of the devices [please refer to Y. Uenishi, H. Tanaka, and H. Ukita ,

Characterization of AlGaAs microstructureCharacterization of AlGaAs microstructure

fabricated by AlGaAs/GaAs micromachining，" IEEEfabricated by AlGaAs / GaAs micromachining, " IEEE

Trans· Electron Devices， vol· 41， pp· 1778一1783，〇ct · 1 994·文獻〕，對於元件長久的穩定性考量，鋁含量若低於2 3 %以下可避免此問題，但如降低砷化結鎵層之含鋁量，將發現檸檬酸/雙氧水蝕刻液之蝕刻選擇性比值亦將嚴重降低，此外，以目前的餘刻水準，使用擰檬酸/ 雙氧水蝕刻液在鋁含量低於23%以下欲得高選擇性，對於Trans. Electron Devices, vol. 41, pp. 1778-1783, oct. 1 994, literature], for long-term stability considerations of components, if the aluminum content is less than 23%, this problem can be avoided, but if arsenic is reduced The aluminum content of the gallium layer will be found, and the etch selectivity ratio of the citric acid / hydrogen peroxide etchant will also be severely reduced. In addition, at the current level, the use of citric acid / hydrogen peroxide etchant at an aluminum content of less than 23 For high selectivity below%, for

珅化鎵層之ϋ刻速率將高達110 A/sec，〔請參考E. a Moon, J. J. Lee, and Η. M. Yoo, "Selective wet etching of GaAs on k\xGa{ . xAs forThe etching rate of the gallium gallium layer will be as high as 110 A / sec. [Please refer to E. a Moon, J. J. Lee, and Η. M. Yoo, " Selective wet etching of GaAs on k \ xGa {. XAs for

AlGaAs/InGaAs/AlGaAs pseudomorphic high electron mobility transistor,M J· Appl. Phys·， vol· 84， pp. 3933-3938，1 998·文獻〕，以此一過高蝕刻速率將在選AlGaAs / InGaAs / AlGaAs pseudomorphic high electron mobility transistor, M.J. Appl. Phys., Vol. 84, pp. 3933-3938, 1 998. Literature], with this high etching rate will be selected

第8頁 1229379 五、發明說明（3) 擇性蝕刻時，該I I I -V族半導體裝置之砷化鎵層〔cap 1 a y e r〕將被過度側向刻〔e X c e s s i v e 1 a t e r a 1 etching〕，導致增加源極電阻〔source resistance〕並降低產品特性’因此，在199 4年】.£16〇1；1'〇(：116111.8〇〇:· 141卷第1082〜1085頁中Mao發表了一篇「The applications of citric acid/ hydrogen peroxide etching solutions in the processing of pseudomorphic MODFETs」文獻，Mao嘗試以去離子水〔DI water〕直接稀釋檸檬酸/雙氧水蝕刻液，以降低對石申化錄層之触刻速率，但不幸的是，砷化鎵層比砷化鋁鎵層之蝕刻選擇性將消失，無法達到高選擇性蝕刻在砷化鋁鎵層上之砷化鎵層。Page 8 1229379 V. Explanation of the invention (3) During selective etching, the gallium arsenide layer [cap 1 ayer] of the III-V semiconductor device will be excessively etched laterally [e X cessive 1 atera 1 etching], resulting in Increasing source resistance and reducing product characteristics'. Therefore, in 1949]. £ 16〇1; 1'〇 (: 116111.8〇〇: · 141 Volume 1082 ~ 1085 published a " "The applications of citric acid / hydrogen peroxide etching solutions in the processing of pseudomorphic MODFETs" document, Mao tried to directly dilute the citric acid / hydrogen peroxide etching solution with DI water to reduce the contact rate of the Shishenhua layer. However, unfortunately, the etching selectivity of the gallium arsenide layer over the aluminum gallium arsenide layer will disappear, and it is impossible to achieve the high selective etching of the gallium arsenide layer on the aluminum gallium arsenide layer.

中之準確化銘鎵錄層之 1 : 300 子層作當蝕刻蚀刻速至該砷名虫刻該〔gate 坤化鋁化學蝕層上之間額外〔體積為钱玄I】至該石夕率，使化ί呂鎵矽原子〕，可鎵層上 ^ ^ 刻控制砷化鎵製作一比〕之深度之原子層得該氨層，再層，在以確定之砷化告第277 1 45號「III-V化合物半導體之方法」揭示有一種選擇性蝕刻在石] 層之方法，其係在砷化鋁鎵層與砷十矽原子層，以氨水：雙氧水：水=2 ：混合液蝕刻該砷化鎵層，而以該矽，控制層’該氨水/雙氧水/水之皞合分時會被抑制而大量降低其縱深方向^ 水/雙氧水/水之混合液不會過度餃系以氫I酸/氨水/雙氧水/水之混合液顯露之砷化鋁鎵層上製作閘極的是該氨水/雙氧水/水之混合液對方鎵層不具有顯著的蝕刻選擇性，製4The accuracy of the gallium recording layer 1: 300 sublayer is used as the etching speed until the arsenic is engraved with [gate Kunhua aluminum chemical etching layer extra [volume is Qian Xuan I] to the stone Xi rate The atomic layer can be formed on the gallium layer ^ ^ to control the depth of the gallium arsenide to make a ratio] to obtain the ammonia layer, and then layered, to determine the arsenization report No. 277 1 45 The "III-V compound semiconductor method" reveals a method for selectively etching the silicon layer, which is based on the aluminum gallium arsenide layer and the arsenic ten silicon atom layer. Ammonia: hydrogen peroxide: water = 2: mixed solution is used to etch the The gallium arsenide layer, and the silicon, the control layer 'the coupling of ammonia / hydrogen peroxide / water will be inhibited and the depth direction will be greatly reduced ^ The mixed solution of water / hydrogen peroxide / water will not excessively dump hydrogen with hydrogen I The gate electrode on the aluminum gallium arsenide layer exposed by the acid / ammonia / hydrogen peroxide / water mixture is that the ammonia / hydrogen peroxide / water mixture does not have significant etching selectivity on the gallium layer.

1229379 五、發明說明（4) 在坤化紹鎵層與砷化鎵層之間手段，佶得鉍Μ命_ , X 7原千層顯為必要之技術于奴使侍蝕刻與製程步驟增加，然而，在源搞血巧搞卞方之砷化鋁鎵層與砷化鎵層之間矽+屏響πΙ:ν料導體裝置之電性㈣。以切原子層，影美國專利第 5374328 號「METHOD OF FUlUCATIMr =:;=_」則揭示有另-種選化銥III-V+導體之方法，其方式為在含鋁量低於2〇% 二J層下方額外製作另一高含銘量〔Α1>25%-〕之薄珅化二俨m触：停止層，而敍刻溶液係包含有擰檬酸、私松St息及雙氧水，並控制溶液PH值在3 6之，刻速率至50 A/Sec以下〔可由該專利前案第3圓了得降低知^，蝕刻選擇性之控制係取決於蝕刻溶液之pH值及溶液含里，但由該專利前案第4圖及詳細說明發現，下層薄砷化鋁鎵層之含鋁量對蝕刻選擇性有著更明顯之影響，當下層薄砷化鋁鎵層之含鋁量低於30%時，以該蝕刻溶液钱田刻該上層低含鋁量砷化鋁鎵層之選擇性比值無法超過丨〇〇以上0 【發明内容】1229379 V. Description of the invention (4) The method between the Kunhua Shao gallium layer and the gallium arsenide layer, obtained bismuth M life, X 7 original thousand layers is a necessary technology for slave etching and process steps increased, However, the electrical properties of the silicon + screening π: ν material conductor device between the aluminum gallium arsenide layer and the gallium arsenide layer are at the source. To cut the atomic layer, U.S. Patent No. 5,374,328 "METHOD OF FUlUCATIMr =:; = _" reveals another method for selecting an iridium III-V + conductor, which is in a way that the aluminum content is less than 20%. Below the J layer, another thin thin film with a high content [Α1> 25%-] is additionally produced: the stop layer, and the engraving solution contains citric acid, osteoporosis and hydrogen peroxide, and the pH of the solution is controlled. The value is 36, and the etch rate is below 50 A / Sec. [It can be reduced from the third round of the previous case of the patent. The control of the etching selectivity depends on the pH value of the etching solution and the content of the solution. Figure 4 and the detailed description of the pre-patent case found that the aluminum content of the lower thin aluminum gallium arsenide layer has a more significant effect on the etch selectivity. When the aluminum content of the lower thin aluminum gallium arsenide layer is less than 30%, Using the etching solution Qian Tian to etch the selectivity ratio of the upper layer of low aluminum content aluminum gallium arsenide layer cannot exceed 丨 00 above 0 [Content of the invention]

本發明之主要目的係在於提供一種Η丨—V族半導體之選擇性蝕刻方法，為了以溼式化學蝕刻技術高選擇彳生蝕刻在一含鋁量低於30 %之砷化鋁鎵層上之砷化鋁層，所提供之餘刻溶液係包含有擰檬酸、雙氧水及水，其中雙氧水之體積百分比係高於擰檬酸之體積百分比並且介於水之體積百分比之0· 2〜0· 3倍之間，在蝕刻該砷化鎵層過程將可達The main purpose of the present invention is to provide a selective etching method for Η 丨 -V semiconductors, in order to use a wet chemical etching technique to selectively etch a semiconductor layer on an aluminum gallium arsenide layer with an aluminum content of less than 30%. The aluminum arsenide layer provides a solution containing citric acid, hydrogen peroxide, and water. The volume percentage of hydrogen peroxide is higher than the volume percentage of citric acid and is between 0.2 and 0. Between 3 times, the process of etching the gallium arsenide layer will reach

1229379 …丨丨丨五、發明說明（5) 到超出預期想像高於J 〇〇以上 ’1 —selectlvity〕，不需以J擇性比值〔― 層之含紹量，並且敍刻速率不可^要制早在下層石申化㈣供產業上利用。 ^了控制在Μ A/^以下，以依本發明之111 - V族半導體之選擇性蝕含之步驟有··先提供有一半導 / ^ 少包含有m ^ 板，該半導體基板係至有中化鋁銥層及一砷化鎵層，其中誃石φ外奴綠展之含鋁量係不超過3〇%，接下來，八〜、曰 :二鎵層之溶液係包含有檸檬酸、雙氧水及並且义於n Γ二之體積百分比係高於檸檬酸之體積百分比 f積百分比之〇.2〜〇.3倍之間，以達到低姓 m〔〈5g A/sec〕與高㈣選擇性比值〔>m〕地银 =石申2鎵層’其中在一具體實施例中，該餘刻溶液之擰板S文之體積百分比係不高於水之體積百分比之〇. 〇2倍，可得到高於100以上之高蝕刻選擇性比值，在另一具體實施例中，該蝕刻溶液之檸檬酸之體積百分比係不高於水之體積百分比之〇· 01倍，可得到高於20 0以上之高蝕刻選擇性比值。【實施方式】參閱所附圖式，本發明將列舉以下之實施例說明。依本發明之第一具體實施例，請參閱第1圖，首先提供一半導體基板10，該半導體基板10係可提供製作各式 I I I - V族半導體裝置，例如一砷化鎵晶圓並至少包含有一石申化铭鎵層11及一砷化鎵層丨2，其中該砷化鋁鎵層丨丨之含 a 第11頁 1229379 五、發明說明（6) 铭量係不超過30%，在本實施例中，該砷化鋁鎵層丨丨之含 I呂量係為2 0 % ’以假型高速電子移動電晶體 Cpseudomorphic high electron mobility transistor, PHEMT〕之I I I-V族半導體裝置例舉之，該pHEMT半導體基板1 0係包s有蒸鍵形成之A u g e / n i / a u源極〔s 〇 u r c e〕與沒極〔d r a i n〕’再經過約4 2 〇之退火處理後形成歐姆接觸〔ohmic contact〕電極。接下來，分別以習知方式與本發明之配比方式製備多種蝕刻溶液，在閘極〔gate〕預定1229379… 丨丨丨 V. Description of the invention (5) If it exceeds the expected imagination, it is higher than J 〇 above '1 —selectlvity], it is not necessary to use the J selectivity ratio [― the content of the layer, and the narrative rate is not necessary. The system was used early in the lower-level Shishen Chemical Industry for industrial use. ^ Controlled below M A / ^ to select selective etching of 111-V semiconductors according to the present invention. The steps are as follows: firstly, half of the conductors are provided, and ^ plates are included, the semiconductor substrate is Sinochemical aluminum iridium layer and a gallium arsenide layer, in which the aluminum content of the vermiculite φ exo green exhibition does not exceed 30%. Next, the solution of the two gallium layer contains citric acid, The volume percentage of hydrogen peroxide and n Γ is higher than the volume percentage of citric acid by 0.2 times to 0.3 times the volume percentage, so as to achieve a low surname m [<5g A / sec] and high ㈣ selection Sex ratio [> m] ground silver = Shishen 2 gallium layer 'Wherein in a specific embodiment, the volume percentage of the screw plate S of the solution at this moment is not higher than 0.2% of the volume percentage of water A high etch selectivity ratio higher than 100 can be obtained. In another specific embodiment, the volume percentage of citric acid in the etching solution is not more than 0.01 times the volume percentage of water, which can be higher than 20 High etching selectivity ratio above 0. [Embodiment] With reference to the drawings, the present invention will be described by the following embodiments. According to a first specific embodiment of the present invention, please refer to FIG. 1. First, a semiconductor substrate 10 is provided. The semiconductor substrate 10 is capable of providing various types of III-V semiconductor devices, such as a gallium arsenide wafer and includes at least There is a gallium layer 11 and a gallium arsenide layer. The aluminum gallium arsenide layer contains a. Page 11 1229379 V. Description of the invention (6) The amount of inscription is not more than 30%. In this embodiment, In the aluminum gallium arsenide layer, the I-containing amount is 20%. As an example, a group II semiconductor device of pseudomorphic high electron mobility transistor (PHEMT) is used. The pHEMT semiconductor The substrate 10 includes an Auge / ni / au source electrode [s 〇urce] and a drain electrode formed by vapor bonding, and then annealed about 4 2 0 to form an ohmic contact electrode. Next, a plurality of etching solutions are prepared in a conventional manner and a ratioing manner according to the present invention, and are predetermined at the gate.

形成位置濕式化學蝕刻處理該砷化鎵層丨2，以供後續 Ti/Pt/Au閘極之製作。在開始調配每一蝕刻溶液時，先將純檸檬酸與去離子水〔DI water〕以一比一重量比例混合成5〇%擰檬酸溶液’再混入適當體積比例之雙氧水與去離子水，再以各種 =同比例的蝕刻溶液在常溫下進行濕式化學蝕刻，再水洗 f半導體基板10，而停止蝕刻，之後，利用掃瞒式電子顯微鏡〔scanning electron microscopy，SEM〕觀察蝕刻後物質表面，並可在移除光阻層之後量測蝕刻深度與表面粗糙 J 均方根值 RMS〔root meari SQUare〕。A position wet chemical etching process is performed to form the gallium arsenide layer 2 for subsequent fabrication of the Ti / Pt / Au gate. At the beginning of preparing each etching solution, first mix pure citric acid and deionized water [DI water] into a 50% citric acid solution in a one-to-one weight ratio, and then mix the appropriate volume ratio of hydrogen peroxide and deionized water. Wet chemical etching at various temperatures with the same proportion of etching solution at normal temperature, and then washed the semiconductor substrate 10 with water to stop the etching. After that, the surface of the etched material was observed using a scanning electron microscopy (SEM). After removing the photoresist layer, the etch depth and surface roughness J RMS [root meari SQUare] can be measured.

请f閱第2圖，習知蝕刻溶液之調配係將5〇%檸檬酸〔以下簡稱檸檬酸〕：雙氧水以3 :丨體積比固定不變之條 $下直接加水稀釋，在未添加去離子水之前，以3 : 1檸檬酸/雙氧水蝕刻溶液可得到對該砷化鎵層丨2產生有丨丨〇 A /sec之蝕刻速率，以及得到對該砷化鋁鎵層丨丨產生有8〇人/56(：之蝕刻速率，其砷化鎵層/(人12〇%)砷化結鎵層之Please refer to Fig. 2. The conventional etching solution is prepared by diluting 50% citric acid (hereinafter referred to as citric acid): hydrogen peroxide with a fixed volume ratio of 3: 丨 and directly diluting it with water. Deionization is not added. Before water, an etching rate of 3: 1 citric acid / hydrogen peroxide solution can be used to obtain an etch rate of the gallium arsenide layer, which is 2 A / sec, and that of the aluminum gallium arsenide layer, which is 8%. Human / 56 (: etch rate, its GaAs layer / (human 12%) GaAs layer

1229379 五、發明説明（7) 一 — '一"· 蝕刻選擇性係為1 · 3 7 5，相當低且蝕刻速率過高，由第j圖可知’當增加水量〔X〕時，可以降低3 : 1 : X檸檬酸/雙氧水/水之蝕刻溶液對該砷化鎵層丨2之蝕刻速率至丨〇 A /sec以下，但對該砷化鋁鎵層丨丨之蝕刻速率並未等比降低，導致對該砷化鋁鎵層1 1之蝕刻速率反而大於對該砷化鎵層1 2之蝕刻速率，使得蝕刻選擇性小於丨，完全無選擇性餘刻之特性。凊參閱第3圖，將|虫刻溶液之擰檬酸與水固定在3 : 1 5 0體積比〔即檸檬酸之體積百分比係不高於水之體積百分比之0.02倍〕，而改變雙氧水之混合用量〔γ〕，試驗發現’當雙氧水之用量在43時〔即雙氧水之體積百分比係為水之體積百分比之0.286倍，使其介於水之體積百分比之0 · 2〜0 · 3倍之間〕將得到大幅降低對該珅化紹鎵層11之餘刻速率〔1 A / sec以下〕，然而其對該砷化鎵層丨2之敍刻速率仍有42· 84 A /sec，將砷化鎵層12之蝕刻速率與坤化鋁鎵層11之姓刻速率相除，可得到珅化鎵層/神化紹嫁層之蝕刻選擇性對照圖，如第4圖所示，當雙氧水之用量在4 3時砷化鎵層/坤化鋁鎵層之蝕刻選擇性係超出預期想像地高達1 02，達到相當高之蝕刻選擇性並且可控制對坤化鎵層12之触刻速率在50 A/sec以下，如第4圖之插圖所示，利用此比例之溶液在1 0分鐘蝕刻PHEMT基板後使用掃瞄式電子顯微鏡拍攝之表面圖可發現其蝕刻表面相當均勻’而雙氧水之用量超出範圍之上或是低於範圍之下均無法達到如此高之蝕刻選擇性。請再參閱第3及4圖，將雙^1229379 V. Description of the invention (7) A — 'A " · The etching selectivity is 1 · 3 7 5, which is quite low and the etching rate is too high. It can be seen from the figure j that when the amount of water [X] is increased, it can be reduced. 3: 1: X citric acid / hydrogen peroxide / water etching solution on the gallium arsenide layer 丨 2 etch rate to less than 〇A / sec, but the etching rate on the aluminum gallium arsenide layer 丨丨 is not equal The reduction results in that the etching rate of the aluminum gallium arsenide layer 1 1 is higher than that of the gallium arsenide layer 12, so that the etching selectivity is less than 丨 and there is no characteristic of selective remaining.凊 Refer to Figure 3, fix the citric acid and water of the insect solution at a volume ratio of 3: 150 (that is, the volume percentage of citric acid is not higher than 0.02 times the volume percentage of water), and change the hydrogen peroxide. Mixed amount [γ], the test found that when the amount of hydrogen peroxide is 43 [that is, the volume percentage of hydrogen peroxide is 0.286 times the volume percentage of water, making it between 0, 2 and 0, 3 times the volume percentage of water. Time] will greatly reduce the remaining etch rate of the GaAs layer 11 [less than 1 A / sec], but the etch rate of the GaAs layer 2 will still be 42 · 84 A / sec. The etching rate of GaAs layer 12 is divided by the etching rate of Kunhua AlGa layer 11 to obtain the etching selectivity comparison chart of GaF layer / Shenhua Shao layer. As shown in Figure 4, when the hydrogen peroxide When the dosage is 4 3, the etching selectivity of the gallium arsenide layer / kunhua aluminum gallium layer is as high as 102 as expected, achieving a very high etch selectivity and controlling the contact rate to the kunhua gallium layer 12 at 50 Below A / sec, as shown in the illustration in Figure 4, using this ratio of solution to etch PHEM in 10 minutes After scanning the surface of the T substrate using a scanning electron microscope, it can be found that the etching surface is quite uniform, and the amount of hydrogen peroxide above or below the range cannot achieve such a high etching selectivity. Please refer to Figures 3 and 4 again.

1^1 第13頁 12293791 ^ 1 Page 13 1229379

五、發明說明（8)V. Description of the invention (8)

， 4 J 水之混合用量〔Y〕分為A, B，C區域並加以解釋，.af :，雙氧水之用量係介於〇〜15,隨著雙氧水=，二 ^層1 2之姓刻速率與對該石_化 ^ 時增加，又該砷化鋁鎵芦n夕為^ t y心蝕到迷羊係同鎵層12之㈣速率，“化率係稍微高於該碎化 ^ ^ . ΛΛ. a 1 〇 {乳水之用1係介於I 5〜4 0，對 =化，層12之㈣速率將超過對料化紹鎵層"之姓玄 ==:ΐ之間並沒有明顯變化。然而，在C區域，當大於4〇之初期，該神化鎵層12之韻刻速率 ϊΓίϊ1之飯刻速率均急遽減少，再恢復為緩慢，低：在蝕刻速率急遽減少之雙氧水用量範圍β，對該砷鎵層12之蚀刻速率之；降n:、：”大於對該神化心阿蝕刻選擇性。由以往之文獻研究，量中，瞭解雙氧水係作為氧化劑，而才丁才象S夂係為還原劑^士 ^ 生成在该砷化鋁鎵層11表面之不溶性氧化鋁會抑制檸檬酸溶液之蝕刻速率，為了進一步能清楚 t析其反應機制，將A區域視為檸檬酸豐富區段，B區域視為反應平衡區段，c區域視為雙氧水豐富區段。在雙氧水豐富之C區域，氧化劑生成足夠濃度之氧化層作為蝕刻阻障層，由於A1—0鍵更強於以―0鍵與AS-0鍵且氧化鋁〔A丨2 〇3〕極難溶於低檸檬酸濃度之蝕刻溶液，故雙氧水在C區域之初期少量增加導致對該砷化鋁鎵層1丨之蝕刻速率大幅下降，呈現明顯的蝕刻選擇性。在反應平衡之, 4 J The mixed amount of water [Y] is divided into areas A, B, and C and explained. .Af :, the amount of hydrogen peroxide is between 0 ~ 15. With the increase of the petrochemical time, the aluminum gallium arsenide renewed the rate of palladium etched to the lamella system with the gallium layer 12, "The chemical conversion rate is slightly higher than the fragmentation ^ ^. ΛΛ. a 1 〇 {The use of milk 1 is between I 5 and 4 0. The rate of ㈣ of layer 12 will be faster than that of the material layer. The surname Xuan of ==: 并 has not changed significantly. However, in the area C, when the initial rate is greater than 40, the rate of rhyme engraving of the deified gallium layer 12 decreases sharply, and then returns to slow and low: the range of hydrogen peroxide consumption β, which decreases sharply at the etching rate, The etch rate of the arsenic-gallium layer 12 is lower than n:,: ", and the selectivity is greater than that of the apotheosis. From previous literature studies, in terms of quantity, we understand that hydrogen peroxide system is used as the oxidant, and only the Sr series is used as the reducing agent ^ ± ^ The insoluble alumina generated on the surface of the aluminum gallium arsenide layer 11 will inhibit the etching of the citric acid solution Rate, in order to further analyze the reaction mechanism, the region A is regarded as a citric acid-rich region, the region B is regarded as a reaction equilibrium region, and the c region is regarded as a hydrogen peroxide-rich region. In the C region rich in hydrogen peroxide, the oxidant generates an oxide layer with a sufficient concentration as an etching barrier layer. Because the A1-0 bond is stronger than the -0 bond and the AS-0 bond, and the aluminum oxide [A 丨 2 03] is extremely insoluble. In the etching solution with a low citric acid concentration, a small increase in hydrogen peroxide in the early stage of the C region leads to a significant decrease in the etching rate of the aluminum gallium arsenide layer 1 and a significant etching selectivity. In the reaction equilibrium

第14頁 1229379Page 14 1229379

五、發明說明（9) B"區域，其係表示有適量之擰檬酸係溶解由雙氧水形成之氧化物，當蝕刻溶液中氧化與溶解反應完全平衡時，可達到泫砷化鎵層1 2與該砷化鋁鎵層丨丨之蝕刻速率為 :分別為 55.5 Α/sec 與 52 A/sec〕。在m = 區域，忒砷化鋁鎵層1 1之蝕刻速率則稍微高於該砷化鎵層 1 2之蝕刻速率，在a區域中，雙氧水之濃度相當低，使得缺乏氧化劑，以保護被蝕刻面，而檸檬酸濃度係相對地高’足以輕易打斷A 1-0, Ga-〇, As-0鍵。此外，鋁係為極容易軋化之金屬，以熱化學角度觀之，氧化銘形成之aGt。〔Gibbs energy change〕係大於氧化鎵〔請參考〇· Kubaschewski, C. B. Alcock, and P. J. Spencer,V. Description of the invention (9) B " area, which means that there is an appropriate amount of citric acid to dissolve the oxide formed by hydrogen peroxide. When the oxidation and dissolution reactions in the etching solution are completely balanced, the gallium arsenide layer can be reached. 1 2 The etching rate of the AlGaAs layer is 55.5 A / sec and 52 A / sec, respectively. In the m = region, the etching rate of the gadolinium aluminum gallium arsenide layer 1 1 is slightly higher than the etching rate of the gallium arsenide layer 12. In the region a, the concentration of hydrogen peroxide is quite low, which makes the lack of an oxidant to protect the etched. The citric acid concentration is relatively high enough to easily break the A 1-0, Ga-〇, As-0 bonds. In addition, aluminum is a metal that is extremely easy to be rolled. From a thermochemical point of view, aGt is formed by oxidation. [Gibbs energy change] is greater than gallium oxide [please refer to 〇 · Kubaschewski, C. B. Alcock, and P. J. Spencer,

Materials Thermochemistry, 6th ed: Pergamon， 1993, p p · 6 - 2 6 ·文獻〕，故在相同雙氧水比例時該珅化銘鎵層 11之氧化速率大於該氧化鎵層1 2之氧化速率，所以在擰檬酸豐富之A區域可以有較高之該砷化鋁鎵層11之蝕刻速率。依本發明之第二具體實施例，請參閱第5圖，將蝕刻溶液之檸檬酸與水固定在2 ·· 2 5 0體積比〔即檸檬酸之體積百分比係約為於水之體積百分比之〇 . 〇〇 8倍〕，而改變雙氧水之混合用量〔X〕，試驗得知，當雙氧水之用量在 6卜6 5時〔即雙氧水之體積百分比係為水之體積百分比之 0.244〜0·26倍，不超過水之體積百分比之〇.2〜0.3倍之間〕，該珅化鋁鎵層11之敍刻速率將大幅降低至 0· 23〜0· 1 7 A/sec，但對該砷化鎵層1·2之蝕刻速率係介於Materials Thermochemistry, 6th ed: Pergamon, 1993, pp. 6-2 6 · Literature], so the oxidation rate of the tritium gallium layer 11 is greater than the oxidation rate of the gallium oxide layer 12 at the same hydrogen peroxide ratio. The citric acid-rich A region can have a higher etching rate of the aluminum gallium arsenide layer 11. According to the second specific embodiment of the present invention, please refer to FIG. 5. The citric acid and water of the etching solution are fixed at a volume ratio of 2 ·· 250. [That is, the volume percentage of citric acid is about the volume percentage of water. 〇. 〇〇〇 times], and change the mixed amount of hydrogen peroxide [X], the test shows that when the amount of hydrogen peroxide is 6 ~ 65 [that is, the volume percentage of hydrogen peroxide is 0.244 ~ 0 · 26 of the volume percentage of water Times, not more than 0.2 to 0.3 times the volume percentage of water], the etch rate of the aluminum gallium halide layer 11 will be greatly reduced to 0 · 23 ~ 0 · 17 A / sec, but the arsenic The etch rate of the gallium layer 1 · 2 is between

第15頁 1229379Page 15 1229379

41· 6〜43. 8 A/sec，計算得知，最佳之砷化鎵層/砷化鋁鎵層之蝕刻選擇性係為256〔當χ = 63〕。明參閱第6圖，將蝕刻溶液之檸檬酸與水固定在2 : 250體積比並選定雙氧水之體積百分比係介於水之體積百分比之0.2〜0.3倍〔Χ = 63〕，分別蝕刻一坤化鎵基板與該. ΡΗΕΜΤ半導體基板丨〇，該蝕刻溶液對該砷化鎵基板之蝕刻深度係與㈣時間為等比線性關係，而當以該敍刻溶液濕式化學蝕刻該ΡΗΕΜΤ半導體基板1〇時，在一段蝕刻時間後，因已蝕刻至該砷化鋁鎵層丨丨，其蝕刻深度〔約3〇〇 A〕無法再等比增加，故該蝕刻溶液係具有相當高度之蝕& 刻選擇性。清參閱第7圖，以該蝕刻溶液對該pHEMT半導體基板1〇進行不同蝕刻時間之濕式化學蝕刻，蝕刻之半導體基板】〇在源極與汲極施加電壓，由於1〇秒至8分鐘蝕刻時間之内，在该砷化鋁鎵層11之蝕刻速率變得相當緩慢，因此，，，電流可控制在一合袼百分比，.使得蝕刻操作變得相當簡單’不會有過度餘刻或敍刻不足之問題，此外，由第7 圖的插圖顯示，該PHEMT半導體基板1〇在蝕刻後之表面經由SEM觀察可知相當平坦，即使在5 〇分鐘蝕刻時間之後，其粗糙度約在1·17 A ，以利閘極〔gate〕之形成，可供壜產業上利用。本發明之保護範圍當視後附之申請專利範圍所界定者為準’任何熟知此項技藝者，在不脫離本發明之精神和範圍内所作之任何變化與修改，均屬於本發明之保護範圍。41 · 6 ~ 43.8 A / sec, the calculation shows that the optimal etching selectivity of the gallium arsenide layer / aluminum gallium arsenide layer is 256 [when χ = 63]. Refer to Fig. 6. Fix the citric acid and water in the etching solution at a volume ratio of 2: 250 and select the volume percentage of hydrogen peroxide to be 0.2 to 0.3 times the volume percentage of water (X = 63). The gallium substrate and the PEGMT semiconductor substrate, the etching depth of the etching solution on the gallium arsenide substrate is linearly proportional to the time, and the PEGMT semiconductor substrate is wet-etched with the etch solution. At this time, after a period of etching time, the etching depth [about 300A] cannot be increased in proportion because the aluminum gallium arsenide layer has been etched. Therefore, the etching solution has a relatively high degree of etching. Selective. Refer to FIG. 7. The pHEMT semiconductor substrate 10 is subjected to wet chemical etching with different etching times using the etching solution, and the semiconductor substrate is etched. The voltage is applied to the source and drain electrodes, and the etching is performed for 10 seconds to 8 minutes. Within time, the etching rate of the aluminum gallium arsenide layer 11 becomes quite slow. Therefore, the current can be controlled at a combined percentage, which makes the etching operation quite simple. The problem of insufficient etching is also shown in the illustration in Fig. 7. The surface of the PHEMT semiconductor substrate 10 after etching is quite flat through SEM observation. Even after 50 minutes of etching time, the roughness is about 1.17. A. The formation of Eli gate can be used in the industry. The scope of protection of the present invention shall be determined by the scope of the appended patent application. 'Anyone skilled in the art and any changes and modifications made without departing from the spirit and scope of the present invention shall fall within the protection scope of the present invention. .

第16頁 1229379 圖式簡單說明圖式簡單說明第1圖：依據本發明之111 -V族半導體之選擇性蝕刻方法，所提供之半導體基板截面圖；第2圖：該半導體基板以習知蝕刻溶液隨著水含量變化之蝕刻速率對照圖；第3圖：依據本發明之丨丨丨-V族半導體之選擇性蝕刻方法，在第一具體實施例中隨著雙氧水含量變化之蝕刻速率對照圖；第4圖··依據本發明之丨丨丨—v族半導體之選擇性蝕刻方法，在第一具體實施例中隨著雙氧水含量變化之對於坤化鎵層與坤化紹鎵層之钱刻選擇性比值對照圖，其插圖為ΡΗΕΜΤ基板利用在第一具體實施 7中有最高選擇性比例溶液在丨〇分鐘蝕刻後使用掃瞒式電子顯微鏡拍攝之表面圖；第5圖：依據本發明之m—v族半導體之選擇性蝕刻方法，在第二具體實施例中隨著雙氧水含量變化之蝕刻速率對照圖與蝕刻選擇性比值對照圖；第6圖：依據本發明之m—v族半導體之選擇性蝕刻方法’在第二具體實施例中隨著隨著蝕刻時間之蝕刻深度對照圖；及 _ 第7圖：依據本發明之ΙΠ—ν族半導體之選擇性蝕刻方，’在第二具體實施例中隨著隨著蝕刻時間之常態電流對照圖，其插圖為ΡΗΕΜΤ基板在5〇分鐘蝕 -刻後在第二具體實施例中有最高選擇性比例溶液Page 16 1229379 Brief description of the drawings Brief description of the drawings Figure 1: Sectional view of a semiconductor substrate provided by a selective etching method of a 111-V semiconductor according to the present invention; Figure 2: The semiconductor substrate is etched by conventional methods Comparison diagram of the etching rate of the solution as the water content changes; Figure 3: Comparison diagram of the etching rate as the hydrogen peroxide content changes in the first embodiment according to the selective etching method of the Group V semiconductor of the present invention Figure 4 ·· According to the selective etching method for a group v semiconductor according to the present invention, in the first specific embodiment, the engraving of the Kunhua gallium layer and the Kunhua Shao gallium layer with the change of the hydrogen peroxide content Selectivity ratio comparison chart, the illustration of which is a surface view of a PQETM substrate using the sweep electron microscope after etching with a solution with the highest selectivity ratio in the first specific implementation 7 minutes; Figure 5: According to the present invention The selective etching method for m-v semiconductors, in the second specific embodiment, a comparison chart of the etching rate and the ratio of the etching selectivity with the change of the hydrogen peroxide content; Fig. 6: Selective etching method of m-v semiconductors according to the present invention, 'Comparison of etching depth with etching time in the second embodiment; and Fig. 7: III according to the present invention- Selective etching method for ν semiconductors, 'In the second specific embodiment, a comparison diagram of the normal current with the etching time is shown in the second specific embodiment. Highest selectivity ratio solution

第17頁 1229379Page 17 1229379

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Claims

1229379 六、申請專利範圍 --- 【申請專利範圍】 1、 <種I I卜V族半導體之選擇性蝕刻方法，包含：提供一半導體基板，該半導體基板係至少3 化鋁鎵層及一石申化鎵層；及匕3有甲包！=:!化鎵層，而用以蝕刻該钟化鎵層之溶液係包a有如板酸、雙氧水及水，其中雙氧水之係高於擇樣酸之體積百分比並且介於水之體積百分1之〇·2〜0.3倍之間，以達到高選擇性蝕刻該坤化鎵層。 2、如申請專利範圍第1項所述之m-v族半導體^選擇 Ο 性蝕刻方法，其中該蝕刻溶液分別對於該砷化鎵層與該石申化銘鎵層之蝕刻選擇性比值係高於1 0 〇。《 ^ 3、如申請專利範圍第1項所述之III-V族半導體之選擇性蝕刻方法，其中該蝕刻溶液分別對於該砷化鎵層、與該石申化銘鎵層之蝕刻選擇性比值係高於2 0 〇。一 " 4 如申凊專利範圍第1項所述之I Π - V族半導體之選擇性餘刻方法，其中該砷化鋁鎵層之含鋁量係不、 30%。之、如申請專利範圍第1項所述之111-ν族半導體之選擇性餘刻方法，其中該蝕刻溶液之檸檬酸之體積百分比係不高於水之體積百分比之〇 · 〇 2倍。 ’ 、如申請專利範圍第1項所述之Π I -V族半導體之選擇性餘刻方法，其中該蝕刻溶液之檸檬酸之體積百分比係不高於水之體積百分比之〇·〇1倍。、如申請專利範圍第丨項所述之I丨丨—ν族半導體之選擇1229379 VI. Scope of Patent Application --- [Scope of Patent Application] 1. <Selective etching method of II type II semiconductors, including: Providing a semiconductor substrate, the semiconductor substrate is at least 3 aluminum gallium layer and one stone application Gallium layer; and Dagger 3 has an armor pack! = :! Gallium layer, and the solution used to etch the gallium layer includes a plate acid, hydrogen peroxide, and water, where the hydrogen peroxide is higher than the volume percentage of the selected acid and is between the volume percentage of water Between 0.2 and 0.3 times to achieve highly selective etching of the KunF layer. 2. The selective etching method of the mv group semiconductor as described in item 1 of the scope of the patent application, wherein the etching selectivity ratio of the etching solution to the gallium arsenide layer and the gallium layer of Shishenhuaming is higher than 100. . << ^ 3. The selective etching method for a III-V semiconductor as described in item 1 of the scope of the patent application, wherein the etching selectivity ratio of the etching solution to the gallium arsenide layer and the gallium layer of Shishenhuaming is higher At 200. A " 4 The selective remaining method of the group I Π-V semiconductor as described in the first item of the patent application, wherein the aluminum content of the aluminum gallium arsenide layer is not more than 30%. The selective remaining method of the 111-ν semiconductor as described in item 1 of the scope of the patent application, wherein the volume percentage of citric acid in the etching solution is not more than 0.2 times the volume percentage of water. ′ The selective remaining method of the group I-V semiconductor as described in item 1 of the scope of the patent application, wherein the volume percentage of citric acid in the etching solution is not greater than 0.001 times the volume percentage of water. I. The choice of ν family semiconductor as described in item 丨 of the scope of patent application

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六、申請專利範圍性蝕刻方法，其中該蝕刻溶液對該係不超過50 A /sec。琢層之餘刻速率 8、一種III-V族半導體之選擇性蝕刻溶液，酸、雙氧水及水，其中雙氧水之體積 3古有= 酸之體積百分比並且介於水之體積百分比之。係二於擰檬之間，以達到高選擇性蝕刻一砷化鎵層。 .仏 9、如申請專利範圍第8項所述之〖丨丨巧族半導體性触刻=液，其中該㈣溶液分別對於該对化鎵層與該石申化紹鎵層之蝕刻選擇性比值係高於1 〇〇。 ’、 10、如申請專利範圍第8項所述之ΙΠ-ν族半導體之選擇性蝕刻溶液，其中該蝕刻溶液分別對於該砷化鎵層與該坤化銘鎵層之蝕刻選擇性比值係高於2 〇〇。 η 11、如申請專利範圍第8項所述之丨丨丨—V族半導體之選擇性姓刻溶液，其中該蝕刻溶液之擰檬酸之體積百分比係不高於水之體積百分比之〇 · 〇 2倍。 12、如申請專利範圍第8項所述之III-V族半導體之選擇性触刻溶液，其中該蝕刻溶液之擰檬酸之體積百分比係示高於水之體積百分比之〇 · 〇 1倍。 1 3、如申請專利範圍第8項所述之I I I -V族半導體之選擇性蝕刻溶液，其中該蝕刻溶液對該砷化鎵層係具有不超過50 A/sec之蝕刻速率。6. The scope of the patent application etching method, wherein the etching solution does not exceed 50 A / sec for the system. Cut-off rate 8. A selective etching solution for III-V semiconductors, such as acid, hydrogen peroxide and water, where the volume of hydrogen peroxide is equal to the volume percentage of acid and is between the volume percentage of water. It is between two layers to achieve a highly selective etching of a gallium arsenide layer. 9. 仏 As described in item 8 of the scope of the patent application, the semiconductor group semiconductor etching = liquid, wherein the etching selectivity ratios of the gallium solution to the pair of gallium layer and the gallium layer of Shishenhua are respectively. Department is higher than 100. ', 10. The selective etching solution for a group ΙΠ-ν semiconductor as described in item 8 of the scope of the patent application, wherein the etching solution has a higher etching selectivity ratio for the gallium arsenide layer and the Kunhuaming gallium layer, respectively. At 2000. η 11. As described in item 8 of the scope of the patent application, the selective surname solution of a group V semiconductor, wherein the volume percentage of the citric acid of the etching solution is not higher than the volume percentage of water. 2 times. 12. The selective etching solution of the III-V semiconductor as described in item 8 of the scope of the patent application, wherein the volume percentage of the citric acid of the etching solution is 0.001 times higher than the volume percentage of water. 1 3. The selective etching solution for the I I I -V semiconductor as described in item 8 of the scope of the patent application, wherein the etching solution has an etching rate of no more than 50 A / sec for the gallium arsenide layer system.

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