JPH0555632A - Led array - Google Patents

Abstract

PURPOSE:To suppress a fluctuation in a light emission output due to accuracy deviation of an electrode shape and make a brightness distribution uniform inside a light emitting body by partially shielding a protrusion by an electrode and providing a clearance according to the electrode shape accuracy between the electrode and the light emitting body except on a protrusion. CONSTITUTION:A light emitting body 12 is partially equipped with protrusions 14 at least at both ends, while electrodes 16, 18 partially cover the protrusions 14 and a predetermined clearance 22 is provided between the electrodes 16, 18 and the light emitting body 12 except on the protrusions 14. Positioning accuracy of the electrodes 16, 18 with respect to the light emitting body 12 has a limitation approximately + or -5mum due to a warp of a substrate 10, positioning accuracy of the light emitting body 2 itself, masking accuracy at the time of electrode formation, difference in etching speeds, existence of side etch, etc. A width D of the protrusion 14 is a 1/4 to 1/2 of a width W which can permit the light emitting bodies 12 to uniformly emit light. Thus influence of electrode width can be suppressed and the light emitting bodies 12 can emit light uniformly.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【発明の利用分野】この発明はＬＥＤアレイの発光体と
電極構造とに関し、例えばＬＥＤプリンタヘッドに用い
れば好適なものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting body and an electrode structure of an LED array, and is suitable for use in an LED printer head, for example.

【０００２】[0002]

【従来技術】ＬＥＤアレイの電極構造としては、例えば
図４（実開平１−１６５，６６５号，特開平２−１７
２，７７２号）、図５（実開平１−１６５，６６５号，
特開昭５７−３１，１８５号）に示すものが知られてい
る。図４の電極配置は発光体２の一端に電極４を設けた
もので、図５の電極配置は発光体２の中央を縦断するよ
うに電極６を設けたものである。なお各図でハッチング
を加えた部分８，９は、電極４，６で発光体２を被覆し
た遮蔽部である。2. Description of the Related Art As an electrode structure of an LED array, for example, a structure shown in FIG.
2,772), FIG. 5 (actual Kaihei 1-165,665,
Those disclosed in JP-A-57-31,185) are known. In the electrode arrangement shown in FIG. 4, the electrode 4 is provided at one end of the light emitting body 2, and in the electrode arrangement shown in FIG. 5, the electrode 6 is provided so as to vertically cut the center of the light emitting body 2. The hatched portions 8 and 9 in the respective drawings are shielding portions in which the light emitting body 2 is covered with the electrodes 4 and 6.

【０００３】図４の電極配置では、電極４が図の上下に
シフトすると、電極４による遮蔽部８の面積が変化し、
発光出力が変動する。また発光体２の輝度分布は図４の
右側の特性となり、電極４側と反対側とで輝度が異な
り、発光体２の全面を均一に発光させられないため発光
出力も低下する。In the electrode arrangement of FIG. 4, when the electrode 4 shifts up and down in the figure, the area of the shielding portion 8 by the electrode 4 changes,
The light output changes. Further, the luminance distribution of the light emitting body 2 has the characteristic on the right side of FIG. 4, the luminance is different between the electrode 4 side and the opposite side, and since the entire surface of the light emitting body 2 cannot be emitted uniformly, the light emission output is also reduced.

【０００４】図５の電極配置では、図の上下への電極６
のシフトでは出力に影響は生じないが、図の左右に電極
６がシフトすると出力が変動する。更に図の鎖線で示し
たように、電極６の幅が変動すると発光出力が変動す
る。In the electrode arrangement shown in FIG. 5, the electrodes 6 are placed on the upper and lower sides of the figure.
The shift does not affect the output, but the output fluctuates when the electrode 6 shifts left and right in the figure. Further, as indicated by the chain line in the figure, when the width of the electrode 6 changes, the light emission output also changes.

【０００５】このような電極の位置のむらや幅のむらが
生じる原因について検討する。電極は通常、基板の全面
に形成した後エッチングにより製造する。あるいは最初
にレジストによるマスクを形成した後、全面に電極を形
成し、リフトオフにより所望の形状とする。ここで電極
のマスクと基板との、マスク合わせ精度が有る。またＬ
ＥＤアレイに主として用いられるＧａＡｓ系の基板は、
反りが±１００μｍ程度と大きく、マスク合わせだけで
は解決できない斜め露光等の問題が有る。更に多数の発
光体を集積したＬＥＤアレイでは、発光体２自体の位置
もアレイの左右でばらつきが有る。これらの他にエッチ
ング条件の変動がある。例えば僅かなエッチング液の濃
度変動や温度変動、エッチング時間の変動等により、エ
ッチング不足が生じ、あるいは逆にエッチング過剰が生
じる。結局これらのために、電極の発光体に対する位置
精度は±５μｍ程度が限界となる。ＬＥＤアレイの数十
μｍ角程度の発光体に対し±５μｍ程度の電極のずれ
は、±１０％程度の発光出力の変動をもたらし、例えば
プリンタヘッドに用いる場合の印画品質を低下させる。The cause of such uneven position and uneven width of the electrodes will be examined. The electrodes are usually manufactured by etching after forming on the entire surface of the substrate. Alternatively, a resist mask is first formed, electrodes are formed on the entire surface, and a desired shape is obtained by lift-off. Here, there is mask alignment accuracy between the electrode mask and the substrate. Also L
The GaAs type substrate mainly used for the ED array is
The warpage is as large as about ± 100 μm, and there are problems such as oblique exposure that cannot be solved only by mask alignment. In an LED array in which a large number of light emitters are integrated, the position of the light emitter 2 itself also varies from side to side in the array. In addition to these, there are variations in etching conditions. For example, due to slight fluctuations in the concentration of the etching solution, fluctuations in temperature, fluctuations in etching time, and the like, insufficient etching occurs, or conversely, excessive etching occurs. After all, for these reasons, the positional accuracy of the electrode with respect to the light emitter is limited to about ± 5 μm. The deviation of the electrodes of about ± 5 μm with respect to the light emitting body of the LED array having a size of several tens of μm square causes a variation of the light emission output of about ± 10%, and deteriorates the printing quality when used for a printer head, for example.

【０００６】[0006]

【発明の課題】この発明の課題は、ＬＥＤアレイの電極
形状の最適化に有り、電極位置の変動に対する許容幅が
大きく、発光体内部の輝度分布が均一で、電極による発
光体の遮蔽面積が小さい、電極形状を提供することに有
る。SUMMARY OF THE INVENTION An object of the present invention is to optimize the electrode shape of an LED array, which has a large tolerance for fluctuations in electrode position, has a uniform luminance distribution inside the light emitter, and has a shielded area of the light emitter by the electrode. It is to provide a small electrode shape.

【０００７】[0007]

【発明の構成】この発明は、半導体基板上に多数の発光
体を形成し、各発光体に電極を接続したＬＥＤアレイに
おいて、該発光体は少なくともその両端に突き出し部を
部分的に設け、電極は該突き出し部を部分的に被覆する
と共に、突き出し部以外の部分では、電極と発光体との
間に所定幅のクリアランスを設けたことを特徴とする、
ＬＥＤアレイに有る。According to the present invention, in an LED array in which a large number of light-emitting bodies are formed on a semiconductor substrate and electrodes are connected to the respective light-emitting bodies, the light-emitting bodies are provided with protruding portions at least at both ends thereof, Is characterized in that the protruding portion is partially covered, and a clearance having a predetermined width is provided between the electrode and the light emitting body in a portion other than the protruding portion.
It is in the LED array.

【０００８】[0008]

【発明の作用】この発明では、発光体の突き出し部以外
の部分では、電極と発光体との間にクリアランスを設け
る。ここでクリアランスを電極の発光体に対する位置精
度（以下単に電極の位置精度という）以上の幅とすれ
ば、電極位置が変動しても発光体には影響しない。また
突き出し部は発光体の両端に設け、両端から発光電流を
流し込むので、発光体の内部での輝度分布はほぼ均一と
なる。そして突き出し部は発光体に比べ小さいので、電
極による遮蔽面積は小さく、かつ突き出し部での電極位
置が変動しても、小さな突き出し部での遮蔽面積が変動
するだけで発光出力への影響は小さい。According to the present invention, a clearance is provided between the electrode and the light emitting body at a portion other than the protruding portion of the light emitting body. If the clearance has a width greater than the positional accuracy of the electrode with respect to the light emitter (hereinafter simply referred to as electrode position accuracy), the light emitter is not affected even if the electrode position changes. Further, since the protruding portions are provided at both ends of the light emitting body and a light emitting current is supplied from both ends, the luminance distribution inside the light emitting body becomes substantially uniform. Since the protruding portion is smaller than the light emitting body, the shielding area by the electrode is small, and even if the electrode position at the protruding portion changes, the shielding area at the small protruding portion only changes and the influence on the light emission output is small. ..

【０００９】[0009]

【実施例】図１に実施例を示し、図２にその変形例を示
し、図３に実施例の輝度分布を示す。図１において、１
０はＧａＡｓ基板で、１２は発光体である。発光体１２
は例えば３００ＤＰＩの密度で配置し、１アレイに６４
個集積する。この結果、発光体１２の幅Ｗは４５μｍ、
長さＬは６０μｍ、発光体１２のピッチは８４．６μｍ
となる。１４は発光体１２の突き出し部で、発光体１２
の長手方向の両端に設けたが、ピッチが許す場合左右の
両端に設けても良い。１６，１８は電極で、発光体１２
の突き出し部１４とオーミック接続し、電極１６，１８
から上下両端の突き出し部１４に発光電流を流し込み、
発光体１２を発光させる。電極１６，１８の材質には、
例えばＡｌを用いる。なお電極１６を電極１８と左右反
転にしたのは、ＬＥＤアレイの端の電極だからである。
２０は、電極１６，１８による突き出し部１４の遮蔽部
である。遮蔽部２０には右下向きのハッチングを施し
た。また２２は電極１６，１８と発光体１２の間のクリ
アランスで、電極１６，１８の形状精度±５μｍに応
じ、５μｍ以上の幅とする。２４は、ＧａＡｓ基板１０
の発光体１２以外の部分を被覆した、ＳｉＮｘ等の保護
膜である。EXAMPLE FIG. 1 shows an example, FIG. 2 shows a modification thereof, and FIG. 3 shows the luminance distribution of the example. In FIG. 1, 1
Reference numeral 0 is a GaAs substrate, and 12 is a light emitter. Luminous body 12
Are arranged at a density of, for example, 300 DPI, and 64 are arranged in one array.
Collect individually. As a result, the width W of the light emitting body 12 is 45 μm,
The length L is 60 μm, and the pitch of the light emitters 12 is 84.6 μm.
Becomes Reference numeral 14 denotes a protruding portion of the light emitting body 12,
Although they are provided at both ends in the longitudinal direction, they may be provided at both left and right ends if the pitch allows. Reference numerals 16 and 18 denote electrodes, which are light-emitting members
Ohmic connection to the protruding portion 14 of the
Light emission current is flown into the protruding portions 14 at the upper and lower ends,
The light emitting body 12 is caused to emit light. The materials of the electrodes 16 and 18 are
For example, Al is used. The electrode 16 is laterally inverted with respect to the electrode 18 because it is an electrode at the end of the LED array.
Reference numeral 20 is a shielding portion of the protruding portion 14 by the electrodes 16 and 18. The shielding portion 20 is hatched in the lower right direction. Reference numeral 22 denotes a clearance between the electrodes 16 and 18 and the light emitting body 12, which has a width of 5 μm or more depending on the shape accuracy of the electrodes 16 and 18 of ± 5 μm. 24 is a GaAs substrate 10
Is a protective film made of SiNx or the like, which covers portions other than the light emitting body 12.

【００１０】電極１６，１８の発光体１２への位置精度
は、基板１０の±１００μｍ程度の反り、発光体１２自
体の±５μｍ程度の位置精度、電極形成時のマスクの精
度、エッチング速度のむらやサイドエッチの有無等によ
り、±５μｍ程度が限界となる。そこで各部の形状をこ
の精度に準じて定めた。先ず突き出し部１４は、図の上
下の奥行きを１５μｍとし、このうち露出部の奥行きＡ
を５μｍ、遮蔽部２０の奥行きＣを１０μｍとし、±５
μｍの変動で発光体１２の本体（４５×６０μｍの部
分）を遮蔽せず、少なくとも５μｍの遮蔽部が残るよう
にした。突き出し部１４の幅Ｄは４５μｍよりも小さい
範囲で任意であるが、発光体１２を均一に発光させ得る
値として、実験結果に基づき１５μｍとした。幅Ｄの好
ましい範囲は、幅Ｗの１／４〜１／２である。電極１
６，１８は、発光体１２の長手方向に平行な最も幅の狭
い部分で８μｍ幅とし、電極１６，１８が平行に並ぶ部
分で、３つの隙間に対し各８μｍ弱を割り当てた。クリ
アランス２２の、発光体１２の長手方向に平行な部分で
の幅Ｂは８μｍである。The positional accuracy of the electrodes 16 and 18 with respect to the light emitting body 12 is such that the substrate 10 has a warp of about ± 100 μm, the positional accuracy of the light emitting body 12 itself is about ± 5 μm, the accuracy of the mask during electrode formation, and the uneven etching rate. The limit is about ± 5 μm depending on the presence or absence of side etching. Therefore, the shape of each part was determined according to this accuracy. First, the protruding portion 14 has a vertical depth of 15 μm in the figure, of which the depth A of the exposed portion is
Is 5 μm and the depth C of the shielding portion 20 is 10 μm, and ± 5
The main body of the light emitting body 12 (45 × 60 μm portion) was not shielded by the fluctuation of μm, and at least a shield portion of 5 μm was left. The width D of the protruding portion 14 is arbitrary within a range smaller than 45 μm, and is set to 15 μm based on the experimental result as a value capable of causing the light emitting body 12 to uniformly emit light. The preferable range of the width D is 1/4 to 1/2 of the width W. Electrode 1
Numerals 6 and 18 have a width of 8 μm at the narrowest portion parallel to the longitudinal direction of the light emitting body 12, and portions where the electrodes 16 and 18 are arranged in parallel are assigned a little less than 8 μm to each of the three gaps. The width B of the clearance 22 in the portion parallel to the longitudinal direction of the light emitting body 12 is 8 μm.

【００１１】図２の変形例では、発光体３２の上下に突
き出し部１４を設け、左右に突き出し部３４を設けた。
３８は発光体３２の４周を囲む電極、４０は左右の突き
出し部３４の遮蔽部、４２はクリアランスである。In the modification of FIG. 2, the protrusions 14 are provided on the upper and lower sides of the light emitting body 32, and the protrusions 34 are provided on the left and right sides.
Reference numeral 38 is an electrode that surrounds the light-emitting body 32 around the four circumferences, 40 is a shielding portion for the left and right protrusions 34, and 42 is a clearance.

【００１２】図１の実施例の特性を説明する。電極１
６，１８は、クリアランス２２の幅Ｂを８μｍ、幅Ａを
５μｍとしたので、電極位置が±５μｍ変動しても、発
光体１２の本体（４５×６０μｍの部分）には接触しな
い。突き出し部１４の部分では、電極が±５μｍ変動し
ても発光体１２の本体を遮蔽せず、また遮蔽部２０は少
なくとも５μｍの奥行きが残る。また発光特性は図３に
示すように、（図３には発光体１２の中心に沿った輝度
分布を示す）、発光体１２の上下両端から発光電流を注
入するため、図の実線のように突き出し部１４を除き、
ほぼ均一な輝度分布が得られる。なお図の破線は各遮蔽
部からの発光電流を示す。遮蔽部２０の面積は小さく、
突き出し部１４の幅が狭いため電極位置が変動しても遮
蔽面積の変動は小さい。The characteristics of the embodiment shown in FIG. 1 will be described. Electrode 1
In Nos. 6 and 18, the width B of the clearance 22 is 8 μm and the width A is 5 μm. Therefore, even if the electrode position fluctuates by ± 5 μm, it does not contact the main body of the light-emitting body 12 (45 × 60 μm portion). In the protruding portion 14, even if the electrode fluctuates ± 5 μm, the main body of the light emitting body 12 is not shielded, and the shielding portion 20 has a depth of at least 5 μm. As for the light emission characteristics, as shown in FIG. 3 (the luminance distribution along the center of the light emitting body 12 is shown in FIG. 3), since the light emitting current is injected from the upper and lower ends of the light emitting body 12, as shown by the solid line in the figure. Excluding the protruding portion 14,
An almost uniform brightness distribution can be obtained. The broken line in the figure indicates the light emission current from each shield. The area of the shielding portion 20 is small,
Since the width of the protruding portion 14 is narrow, the variation of the shielding area is small even if the electrode position varies.

【００１３】図４，図５の従来例と、図１の実施例につ
いて、電極による遮蔽面積とその変動とについて、比較
する。なお発光体はいずれも４５μｍ×６０μｍとす
る。図４の従来例で遮蔽部８の幅は、±５μｍの電極精
度を考慮すると１０μｍが必要である。また図５の従来
例では、エッチングの過不足による電極６の左右のシフ
トが±２．５μｍとすると、１０μｍ幅の電極が必要と
なる。これらを基に、発光体の総面積、電極による標準
遮蔽面積、電極位置の上下左右への±５μｍのアライン
メント誤差による遮蔽面積の変化、±２．５μｍのエッ
チングの過不足による遮蔽面積の変化を、表１に示す。The shielding area by the electrode and its variation will be compared between the conventional example shown in FIGS. 4 and 5 and the embodiment shown in FIG. The size of each light-emitting body is 45 μm × 60 μm. In the conventional example of FIG. 4, the width of the shielding portion 8 needs to be 10 μm in consideration of the electrode accuracy of ± 5 μm. Further, in the conventional example of FIG. 5, if the lateral shift of the electrode 6 due to excess or deficiency of etching is ± 2.5 μm, an electrode having a width of 10 μm is required. Based on these, the total area of the light emitter, the standard shielding area by the electrode, the variation of the shielding area due to the alignment error of ± 5 μm up and down and left and right of the electrode position, and the variation of the shielding area due to the excess or deficiency of etching of ± 2.5 μm , Shown in Table 1.

【００１４】[0014]

【表１】 [Table 1]

【００１５】表１から明らかなように実施例では、電極
による遮蔽面積が小さく発光体１２を有効に発光させる
ことができ、電極１６，１８のマスク合わせ時のアライ
ンメント誤差では遮蔽面積が変動せず、更にエッチング
の過不足に対する遮蔽面積の変動も少ない。遮蔽面積の
変動はエッチングの過不足によるものだけで、その値は
総発光面積の２．５％程度に過ぎず、図４，図５の従来
例の１／４以下となる。更に図５の従来例では、電極６
が左右にずれると輝度が不均一となるが、実施例では電
極１６，１８の左右のずれは遮蔽部２０に影響しない。
これらのため、実施例のＬＥＤアレイをプリンタヘッド
に用いると、各発光体１２の内部での輝度が均一で、電
極の精度による発光出力の変動が小さいため、高品質の
印画賀できる。As is clear from Table 1, in the embodiment, the shielding area by the electrodes is small and the light emitting body 12 can effectively emit light, and the shielding area does not change due to the alignment error at the time of mask alignment of the electrodes 16 and 18. Moreover, the variation of the shielded area with respect to the excess or deficiency of etching is small. The variation of the shielded area is only due to the excess or deficiency of etching, and its value is only about 2.5% of the total light emitting area, which is 1/4 or less of the conventional example of FIGS. 4 and 5. Furthermore, in the conventional example of FIG.
However, in the embodiment, the horizontal displacement of the electrodes 16 and 18 does not affect the shielding portion 20.
For these reasons, when the LED array of the embodiment is used for a printer head, the luminance inside each light emitting body 12 is uniform, and the fluctuation of the light emission output due to the accuracy of the electrodes is small, so that high quality printing can be performed.

【００１６】[0016]

【発明の効果】この発明では、電極位置の変動やエッチ
ングの過不足による電極幅の影響を抑え発光体を均一に
発光させると共に、発光体の内部での輝度分布を小さく
し、高品位のＬＥＤアレイが得られる。According to the present invention, it is possible to suppress the influence of the electrode width due to the fluctuation of the electrode position and the excess or deficiency of etching, and to make the light emitting body emit light uniformly, and to reduce the luminance distribution inside the light emitting body, thereby providing a high quality LED. An array is obtained.

【図面の簡単な説明】[Brief description of drawings]

【図１】 実施例のＬＥＤアレイの要部平面図FIG. 1 is a plan view of a main part of an LED array according to an embodiment.

【図２】 変形例のＬＥＤアレイの要部平面図FIG. 2 is a plan view of a main part of a modified LED array.

【図３】 実施例のＬＥＤアレイの輝度分布を示す特性
図FIG. 3 is a characteristic diagram showing the luminance distribution of the LED array of the example.

【図４】 従来例のＬＥＤアレイの要部平面図FIG. 4 is a plan view of a main part of a conventional LED array.

【図５】 従来例のＬＥＤアレイの要部平面図FIG. 5 is a plan view of a main part of a conventional LED array.

【符号の説明】[Explanation of symbols]

１０ ＧａＡｓ基板 １２ 発光体 １４ 突き出し部 １６ 電極 １８ 電極 ２０ 遮蔽部 ２２ クリアランス ２４ 保護膜 10 GaAs Substrate 12 Light-Emitting Body 14 Projection 16 Electrode 18 Electrode 20 Shield 22 Clearance 24 Protective Film

Claims (1)

【特許請求の範囲】[Claims] 【請求項１】 半導体基板上に多数の発光体を形成し、
各発光体に電極を接続したＬＥＤアレイにおいて、 該発光体は少なくともその両端に突き出し部を部分的に
設け、電極は該突き出し部を部分的に被覆すると共に、
突き出し部以外の部分では、電極と発光体との間に所定
幅のクリアランスを設けたことを特徴とする、ＬＥＤア
レイ。1. A large number of light emitters are formed on a semiconductor substrate,
In an LED array in which an electrode is connected to each light-emitting body, the light-emitting body is partially provided with protruding portions at both ends thereof, and the electrodes partially cover the protruding portions, and
An LED array, characterized in that a clearance having a predetermined width is provided between the electrode and the light-emitting body in a portion other than the protruding portion.