JPH05129659A - Manufacture of light emission diode chip - Google Patents
Manufacture of light emission diode chipInfo
- Publication number
- JPH05129659A JPH05129659A JP32135591A JP32135591A JPH05129659A JP H05129659 A JPH05129659 A JP H05129659A JP 32135591 A JP32135591 A JP 32135591A JP 32135591 A JP32135591 A JP 32135591A JP H05129659 A JPH05129659 A JP H05129659A
- Authority
- JP
- Japan
- Prior art keywords
- layer
- type
- gaas
- algaas
- substrate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
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- Led Devices (AREA)
Abstract
Description
【0001】[0001]
【産業上の利用分野】本発明は、発光ダイオード(LE
D)チップの製造方法に関するものである。BACKGROUND OF THE INVENTION The present invention relates to a light emitting diode (LE).
D) The present invention relates to a chip manufacturing method.
【0002】[0002]
【従来の技術】AlGaAsLEDを製造する場合、通常GaAs
基板上に発光層を含むAlGaAs層をエピタキシャル成長さ
せるが、そのエピタキシャル層を図2に示す。図2にお
いて、1はp型のGaAs基板を示し、順に4,5,6はい
ずれもp型のAlxGa1-xAsを示すが、4,5,6はAlx ,
Gax の混晶比xにおいては相違し、7はn型のAlGaAsを
示し、8はn型のGaAs層であり、このようにエピウエハ
が形成される。なおAlGaAs層6は発光層である。LED
を点灯させたとき、発光層6から下方に出た光はGaAs基
板1により吸収されてしまう。これを避けるため、AlGa
As層4を厚く( 120μm程度以上)成長させて、GaAs基
板1をエッチングまたは研磨により除去して光の吸収を
小さくする構造が採用されている。この場合、下方に出
た光がチップ裏面で効率よく反射して取り出せるよう
に、チップ裏面の電極(図示していない)は全面に形成
されず、ドット状等の電極が用いられることが多い。ま
た、電極を形成する場合、AlGaAs層に直接電極を形成す
ると、GaAs層上に形成する場合に比べて接触抵抗が高く
なり易いため、AlGaAs層7の上にもGaAs層8が形成さ
れ、電極以外の部分のGaAs層をエッチングにより除去す
ることが行われている。2. Description of the Related Art When manufacturing an AlGaAs LED, GaAs is usually used.
An AlGaAs layer including a light emitting layer is epitaxially grown on a substrate, and the epitaxial layer is shown in FIG. In FIG. 2, 1 indicates a p-type GaAs substrate, and 4, 5 and 6 indicate p-type AlxGa 1 -xAs, respectively, while 4, 5 and 6 indicate Alx,
The mixed crystal ratio x of Gax is different, 7 is n-type AlGaAs, and 8 is an n-type GaAs layer, thus forming an epi-wafer. The AlGaAs layer 6 is a light emitting layer. LED
When is turned on, the light emitted downward from the light emitting layer 6 is absorbed by the GaAs substrate 1. To avoid this, AlGa
A structure is adopted in which the As layer 4 is grown thick (about 120 μm or more) and the GaAs substrate 1 is removed by etching or polishing to reduce light absorption. In this case, an electrode (not shown) on the back surface of the chip is not formed over the entire surface so that the light emitted downward is efficiently reflected on the back surface of the chip and can be extracted, and an electrode having a dot shape or the like is often used. Further, in the case of forming an electrode, if the electrode is directly formed on the AlGaAs layer, the contact resistance tends to be higher than that on the GaAs layer. Therefore, the GaAs layer 8 is also formed on the AlGaAs layer 7, The GaAs layer other than the above is removed by etching.
【0003】[0003]
【発明が解決しようとする課題】上述のように、GaAsに
電極を形成しようとする場合、表面の場合はエピタキシ
ャル成長により、薄いGaAsを成長させればよいが、裏面
の場合には、GaAs基板を薄く残して除去する必要があ
る。しかし、GaAs基板1をエッチングにより除去する場
合には、ウエハの周辺と中心部でエッチングレートが少
し異なるため、ウエハ全面でGaAs基板を均一に薄く残し
てエッチングを止めることは難しいし、また研磨により
基板を除去する場合にも、ウエハのそりのため、均一な
研磨は難しく、そのためウエハの裏面全面において、均
一に接触抵抗を低くすることはできない。本発明は、前
記裏面における電極形成のための薄いGaAs層を均一に形
成するようにしようとすることを課題とするものであ
る。As described above, when an electrode is formed on GaAs, thin GaAs may be grown by epitaxial growth on the front surface, but a GaAs substrate may be formed on the back surface. It must be left thin and removed. However, when removing the GaAs substrate 1 by etching, it is difficult to stop the etching by leaving the GaAs substrate uniformly thin over the entire surface of the wafer because the etching rate is slightly different between the periphery and the center of the wafer. Even when the substrate is removed, it is difficult to uniformly polish the wafer due to the warpage of the wafer, and therefore the contact resistance cannot be uniformly lowered on the entire back surface of the wafer. An object of the present invention is to uniformly form a thin GaAs layer for forming an electrode on the back surface.
【0004】[0004]
【課題を解決するための手段】図1(a)〜(e)は本
発明の実施説明図であり、図2と同一部分は同一符号で
示す。(a)図に示すように、後にエッチングにより除
去されるが、p型GaAs基板1上にp型AlGaAs層2、p型
GaAs層3をエピタキシャル成長させ、その上に図2で示
したような従来のLEDチップ製造時と同様に、p型Al
GaAs層4、その上にp型AlGaAs層5、AlGaAs発光層6、
n型AlGaAs層7、n型GaAs層8が順に形成される。その
後、(b)図に示すように、GaAs基板1を除去し、次に
AlGaAsのみを選択エッチングし、GaAsをエッチングしな
いようなエッチング液を用いて、(c)図に示すよう
に、AlGaAs層2を選択除去することによりAlGaAsの裏面
に薄いGaAs層3の露出したウエハを得ることができる。
次にこのGaAs層3とすでに形成されているGaAs層8に
(d)図に示すように電極10,9を形成し、GaAsを、Ga
Asのみエッチングするエッチング液により選択除去する
ことにより、図(e)に示すように、接触抵抗の低い電
極9,10を備えたLEDウエハを得ることができる。1 (a) to 1 (e) are illustrations for explaining the embodiment of the present invention, in which the same parts as in FIG. 2 are designated by the same reference numerals. As shown in (a), the p-type AlGaAs layer 2 and the p-type AlGaAs layer 2 are formed on the p-type GaAs substrate 1, which will be removed later by etching.
A GaAs layer 3 is epitaxially grown, and a p-type Al layer is formed on the GaAs layer 3 as in the conventional LED chip manufacturing as shown in FIG.
GaAs layer 4, p-type AlGaAs layer 5, AlGaAs light emitting layer 6 thereon,
The n-type AlGaAs layer 7 and the n-type GaAs layer 8 are sequentially formed. Then, the GaAs substrate 1 is removed as shown in FIG.
By using an etching solution that selectively etches only AlGaAs and does not etch GaAs, the AlGaAs layer 2 is selectively removed as shown in FIG. Obtainable.
Next, electrodes 10 and 9 are formed on the GaAs layer 3 and the GaAs layer 8 already formed as shown in FIG.
By selective removal with an etchant that etches only As, an LED wafer having electrodes 9 and 10 having low contact resistance can be obtained as shown in FIG.
【0005】[0005]
【作用】予めGaAs基板上にAlGaAsを形成して、この上に
GaAsの層を形成しているので、GaAs基板の除去、AlGaAs
層に対するエッチングにより、GaAsの薄層はウエハ全面
で均一に残すことができ、前記のように接触抵抗の低い
電極が得られ、LEDの順方向電圧を下げることがで
き、また、より小さい面積の電極でも、同程度の順方向
電圧とすることが可能なため、LEDチップの裏面電極
を小さくすることにより、発光の取り出し効率をよくし
て、LEDの出力を大きくすることができる。[Function] Form AlGaAs on the GaAs substrate in advance and
Since the GaAs layer is formed, the GaAs substrate is removed, AlGaAs
By etching the layer, a thin layer of GaAs can be left uniformly over the entire wafer, resulting in an electrode with low contact resistance as described above, lowering the forward voltage of the LED, and reducing the area. Since the electrodes can have the same forward voltage, the back electrode of the LED chip can be made small to improve the extraction efficiency of light emission and increase the output of the LED.
【0006】[0006]
【実施例】まず、p型GaAs基板1上に表1のドーパン
ト、混晶比x、厚み(μm )を有する2〜8のエピタキ
シャル層を、スライドボートを用いた液相エピタキシャ
ル法で連続して成長させ、図1(a)の構造のエピウエ
ハを作成した。EXAMPLE First, 2 to 8 epitaxial layers having the dopant of Table 1, mixed crystal ratio x and thickness (μm) are successively formed on a p-type GaAs substrate 1 by a liquid phase epitaxial method using a slide boat. An epitaxial wafer having the structure shown in FIG.
【0007】[0007]
【表1】 [Table 1]
【0008】次に、ウエハ表面がエッチング液に接触し
ないように表面にテープを貼り付けて、アンモニア系の
選択液により、GaAs基板1をエッチング除去した。そし
て塩酸によりAlGaAs層2を除去し、表面テープをはがし
た。得られたウエハの表面および裏面にオーミック電極
9,10を形成し、電極以外のGaAs層をアンモニア系のエ
ッチング液で除去した。このウエハを 300×300μm 角
にダイシングした。表面電極と裏面電極との間に電流20
mAを流したときの順方向電圧は1.48V であった。また、
GaAs層2、AlGaAs層3を成長させず、AlGaAs4に裏面電
極を付けたときの20mAでの順方向電圧は1.60V であっ
た。なお、p型GaAs基板直上のp型Alx Ga1-xAs 層混晶
比xは0.3 以上とされるが、xが0.3 以下であると、塩
酸エッチングされず、p型GaAs及びn型GaAsを2μm以
下とするのは、あまり厚くない方が電極形成後のエッチ
ングが容易であるためである。又、p型AlGaAsを80μ
m以上とするのは、この層が薄いと後工程のLED組み
立て時に、導電性接着剤のまわり込みが発生し易くなる
ためである。Next, a tape was attached to the surface of the wafer so that it would not come into contact with the etching solution, and the GaAs substrate 1 was removed by etching with an ammonia-based selective solution. Then, the AlGaAs layer 2 was removed with hydrochloric acid, and the surface tape was peeled off. Ohmic electrodes 9 and 10 were formed on the front and back surfaces of the obtained wafer, and the GaAs layer other than the electrodes was removed with an ammonia-based etching solution. This wafer was diced into 300 × 300 μm square. There is a current of 20 between the front and back electrodes.
The forward voltage when mA was applied was 1.48V. Also,
The forward voltage at 20 mA when the back electrode was attached to AlGaAs 4 without growing the GaAs layer 2 and AlGaAs layer 3 was 1.60V. The p-type Alx Ga 1 -xAs layer mixed crystal ratio x immediately above the p-type GaAs substrate is set to 0.3 or more. However, when x is 0.3 or less, hydrochloric acid etching is not performed and p-type GaAs and n-type GaAs are 2 μm in thickness. The reason for the following is that etching after forming the electrode is easier if the thickness is not too thick. Also, p-type AlGaAs is 80μ
The reason why the thickness is set to m or more is that if this layer is thin, the conductive adhesive easily wraps around during LED assembly in a later step.
【0009】[0009]
【発明の効果】以上説明したように、本発明によれば、
LED用ウエハの裏面に薄層で均一厚みのGaAs層を得る
ことができ、順方向電圧の電圧の低いLEDチップを簡
単に得ることができ、また順方向電圧が高くならず、裏
面電極を小さくすることで、LEDチップの出力を向上
させることができる。As described above, according to the present invention,
A thin GaAs layer having a uniform thickness can be obtained on the back surface of the LED wafer, an LED chip having a low forward voltage can be easily obtained, and the forward voltage does not become high and the back electrode is small. By doing so, the output of the LED chip can be improved.
【図1】図(a),(b),(c),(d),(e)は
順に本発明実施の工程を示す。FIG. 1A, FIG. 1B, FIG. 1C, FIG. 1D, and FIG.
【図2】従来のLEDエピウエハのエピタキシャル各層
の成長順を示す。FIG. 2 shows a growth order of epitaxial layers of a conventional LED epi-wafer.
1 p型GaAs基板 2 p型AlGaAs層 3 p型GaAs層 4 p型AlGaAs層 5 p型AlGaAs層 6 AlGaAs発光層 7 n型AlGaAs層 8 n型GaAs層 9,10 電極 1 p-type GaAs substrate 2 p-type AlGaAs layer 3 p-type GaAs layer 4 p-type AlGaAs layer 5 p-type AlGaAs layer 6 AlGaAs light-emitting layer 7 n-type AlGaAs layer 8 n-type GaAs layer 9, 10 electrode
Claims (2)
層、p型GaAs層、p型AlGaAs層、AlGaAs発光層、n型Al
GaAs層をエピタキシャル成長した後、前記p型GaAs基板
を選択エッチングにより除去し、さらに該基板に連続す
るp型AlGaAs層を選択エッチングにより除去した後、該
エッチングにより露出したp型GaAsの一部にオーミック
電極を形成し、該p型GaAs層の電極以外の部分を選択エ
ッチングにより除去することを特徴とする発光ダイオー
ドチップの製造方法。1. A p-type AlGaAs is continuously formed on a p-type GaAs substrate.
Layer, p-type GaAs layer, p-type AlGaAs layer, AlGaAs light-emitting layer, n-type Al
After the GaAs layer is epitaxially grown, the p-type GaAs substrate is removed by selective etching, and the p-type AlGaAs layer continuous to the substrate is removed by selective etching, and then ohmic contact is formed on part of the p-type GaAs exposed by the etching. A method for manufacturing a light-emitting diode chip, which comprises forming an electrode and removing a portion of the p-type GaAs layer other than the electrode by selective etching.
0.3以上のp型AlxGa1-xAs層、厚みが2μm 以下のp型G
aAs層、厚みが80μm 以上のp型AlGaAs層、AlGaAs発光
層、n型AlGaAs層および厚みが2μm 以下のn型GaAs層
を形成した後、前記p型GaAs基板、p型AlGaAs層を次に
選択エッチングにより除去した後、該エッチングにより
露出したp型GaAsならびに前記表面となるn型GaAs層の
一部にオーミック電極を形成し、これら両電極以外の部
分を選択エッチングにより除去することを特徴とする発
光ダイオードチップの製造方法。2. A mixed crystal ratio x is continuously formed on a p-type GaAs substrate.
P-type AlxGa 1 -xAs layer of 0.3 or more, p-type G of 2 μm or less in thickness
After forming an aAs layer, a p-type AlGaAs layer with a thickness of 80 μm or more, an AlGaAs light emitting layer, an n-type AlGaAs layer and an n-type GaAs layer with a thickness of 2 μm or less, select the p-type GaAs substrate and p-type AlGaAs layer next. After removing by etching, ohmic electrodes are formed on the p-type GaAs exposed by the etching and a part of the n-type GaAs layer serving as the surface, and the parts other than these electrodes are removed by selective etching. Manufacturing method of light emitting diode chip.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP32135591A JPH05129659A (en) | 1991-11-07 | 1991-11-07 | Manufacture of light emission diode chip |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP32135591A JPH05129659A (en) | 1991-11-07 | 1991-11-07 | Manufacture of light emission diode chip |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH05129659A true JPH05129659A (en) | 1993-05-25 |
Family
ID=18131655
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP32135591A Pending JPH05129659A (en) | 1991-11-07 | 1991-11-07 | Manufacture of light emission diode chip |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH05129659A (en) |
-
1991
- 1991-11-07 JP JP32135591A patent/JPH05129659A/en active Pending
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