CN85100503A - The reflection cavity of light emitting semiconductor device and technology thereof - Google Patents

Abstract

The present invention is the reflection cavity and the technology thereof of light emitting semiconductor device, belong to semiconductor photoelectric device, the field of light emitting semiconductor device particularly, it is to utilize the anisotropic etch characteristic of monocrystalline silicon to form various cubes or rectangular taper reflection cavity on (100) of monocrystalline silicon crystal face, plate layer of metal (as Au, Ag or Al etc.) again as metallic mirror surface, thereby can make various LED light, charactron, demonstration of 5 * 7 characters or LED array etc.Reflection cavity technology of the present invention and common semiconductor device technology are compatible, with the LED device that this reflection cavity makes, output intensity are increased, and improve luminous efficiency.

Description

The reflection cavity of light emitting semiconductor device and technology thereof

The present invention relates to semiconductor photoelectric device, particularly the reflection cavity of light emitting semiconductor device.Can be used for light-emitting diode (hereinafter to be referred as LED) and by the LED charactron that LED constituted, the LED character shows and the graphical display of LED array.

LED has been widely used as the indicator light on the various instrument and meters, and charactron on the digitizer instruments and meters and character show.In recent years, the brightness of GaAs-gallium aluminum arsenide double heterojunction LED has reached 3～6 candle lights, uses in some aspects soon to be hopeful to replace illuminator lamp.Yet general LED tube core is all very little, about 0.1mm ²Size, in order to increase the apparent light-emitting area of LED luminous tube, improve the luminous intensity of luminous tube, increase the visual sense degree, the someone has designed various reflection cavities, these reflection cavities have plenty of with metallic support (as using kovar alloy) and are stamped to form (as various instrument and meter indicator lights), have plenty of the reflection cavity (nixie display of using as the digitlization instrument and meter) of the various sizes that form with white plastics.These have report on some national patents in the world, for example: (1) U.S.3820237(1974), (2) DE 3137685(1983), (3) spy opens clear 52-126187(1977) and, (4) spy opens clear 58-66372(1983).

The part yet above-mentioned certain methods comes with some shortcomings when making the reflection cavity of LED: when the stamped metal support forms reflection cavity, the material of mould and the precision of die sinking all there is very high requirement, so cost is very high, determine rational size through overtesting, need repeatedly change mould, even the device shape size is slightly different simultaneously various mould must be arranged, these have all increased cost.For the LED charactron or the character indicator spare that make with white plastic reflective chamber, analysis (R.H.Heite " Trende in LED Display Technology " Proc.1974 according to the R.H.Heite of H.P company, 24th Electronic Components Conferences, p.2) light extraction efficiency is not high, only there is 30～40% light luminous from the exiting surface of cavity, this is mainly due to there being some tangible absorption loss waters in the cavity: the absorption loss water that surface, large-area plastic reflective chamber causes, the absorption loss water that slit between plastics and support causes, the absorption loss water that the slit between the positive and negative electrode lead-in wire causes etc.

The present invention proposes a kind of new LED reflection cavity and technology thereof, and this reflection cavity has the reflective characteristic of good minute surface, on the technology can with traditional semiconductor device technology compatibility, do not need mould, use this reflection cavity, can improve the brightness of luminescent device, reduce power consumption.

The present invention is based on the anisotropic etch characteristic of semiconductor single crystal material silicon.Because the corrosion rate of silicon single crystal crystal face of different crystal orientations in some anisotropic etchant has very big difference, according to result of experiment: the difference of the corrosion rate of (100) face of silicon single crystal and (111) face was up to 400: 1 in potassium hydroxide aqueous solution, the crystal face angle of (K.E.Petersen, Proc.I.E.E.E.70(1982) 420) and (100) face and (111) face is 54.74 °.After corrosion, just can form like this,, just form a kind of reflection cavity that the metallic mirror surface reflection characteristic is arranged as if evaporation (or plating) layer of metal in the above again by 4 (111) crystal faces and (100) square or rectangular groove that the bottom surface constituted.In the semiconductor device technology of silicon, be easy on (100) Si sheet, form needed various squares and rectangular pattern, after corroding, just can on (100) of silicon crystal face, form the direct reflection chamber of difformity size by technologies such as oxidation, photoetching.As if being contained in such reflection cavity, the LED tube core just can form various LED products, as indicator light, and charactron, character shows and various LED array.

This reflection cavity is to be made of with metallic mirror surface the silicon chip surface plating of corroding.Naturally have the reflective characteristic of good minute surface, the light that it can make LED tube core side send, the reflection by reflection cavity obviously increases the light intensity of positive normal direction, has increased the apparent light-emitting area of LED, has increased the visual sense degree greatly.

This reflection cavity size changes quite flexible, do not need die sinking and change the required expensive cost of mould, the formation of different devices is also very convenient, this law and common silicon semiconductor device process compatible, thereby can on silicon chip, form integrated reflection cavity with this method, thereby obtain the LED charactron, 5 * 7 characters, various devices such as 16 * 16 characters or graphical display.This method does not have specific (special) requirements to the silicon single crystal material of selecting for use yet.The made word height of reflection cavity that makes by this technology be the LED charactron of 0.3 inch (about 7.6mm) than the general LED charactron that makes with the plastic reflective chamber, the about forward current of 5mA make whole "

" under the complete bright state, brightness will be enhanced about more than once.

The description of drawings that this patent is listed is as follows:

Fig. 1 illustrates the anisotropic etch characteristic of (100) Si; 1 is silicon single crystal flake among the figure.2 one deck SiO for growth ₂, and opened a square corrosion window.α among the figure=54.74 °.

Fig. 2 a illustrates on (100) Si and this face＜and 110〉orientation.

Fig. 2 b illustrates the SiO of the last growth of (100) Si ₂Photoetching is windowed; 1 is silicon single crystal flake among the figure, and 2 is SiO ₂, 3 are the place of windowing.

Fig. 2 c is the LED that has reflection cavity.1 is silicon single crystal flake among the figure, and 2 is the metallic mirror surface of evaporation, and 3 is the LED tube core.

Fig. 2 d is the LED light that has reflection cavity.1 is base among the figure, and 2 is the Si reflection cavity, and 3 is the coat of metal, and 4 is the LED tube core, and 5 are lead-in wire.

Fig. 3 is Si(100) charactron that constitutes of reflection cavity on the face.

Fig. 4 is Si(100) 5 * 7 characters that constitute of reflection cavity on the face.

0.3 inch charactron and the comparison of sample pipe both at home and abroad that Fig. 5 forms for pressing this patent.Abscissa I _FBe forward current, ordinate P _fBe relative Output optical power.Used tube core is a GaP red LED tube core, the performance basically identical.Curve 1 is to make the luminous power output of charactron and the relation curve of forward current by this patent, and curve 2 is the red GaP LED charactron of import, and curve 3 is the red GaP LED of a HDR-10 charactron.(tube core import, domestic production) under same electric current, uses the LED of the reflection cavity formation of this patent as seen from the figure, and luminous efficiency can improve more than 50% to one times.

Point out a kind of implementation method below: Fig. 2 a is resistance (100) Si monocrystalline (for example resistivity is several ohmcms) in, according to the cutting (sheet), mill (sheet), throw (light) technology of the silicon chip of routine, obtain its thickness of a mirror finish (100) Si single crystalline substrate sheet can guarantee that enough mechanical strengths are as the criterion.Fig. 2 a gives in (100) face upper edge＜110〉crystal orientation datum lines of doing; the layer of oxide layer of on silicon chip, growing then (silicon dioxide or the deposition one deck silicon nitride that form as the autoxidation of silicon); protective layer as corrosion; photoetching forms square fenestra, and window size is 1.2 * 1.2mm ², and make foursquare one side and＜110〉datum line parallel (or vertical).Figure behind the photoetching window is shown in Fig. 2 b, the aqueous solution with for example KOH, the proportioning of choosing is 44 gram potassium hydroxide+100cc deionized waters, at room temperature to 80 ℃ scope internal corrosion (K.E.Petevsen, Proc.I.E.E.E.70(1982) 420) corrosion depth is with slightly thicker in good than LED die thickness, simultaneously also avoid reflection cavity to corrode too deeply, this can unnecessarily increase the thickness of silicon chip on the one hand, also promptly increase cost, simultaneously dark chamber can make light that survey face sends repeatedly reflect and cause loss through reflection cavity.The silicon reflection cavity that corrosion obtains, through the Si of routine sheet clean: promptly 1 part of ammoniacal liquor adds 1 part of hydrogen peroxide and adds 5 parts of deionized waters and boiled several minutes, adding 1 part of hydrochloric acid through 1 part of hydrogen peroxide again adds 6 parts of deionized waters and boiled several minutes, deionized water rinsing is clean, dry up the method for back with evaporation, evaporation layer of metal (as gold, silver or aluminium etc.), promptly formed the reflection cavity that the reflective characteristic of good minute surface is arranged, the LED tube core is bonded in this reflection cavity with conducting resinl, Fig. 2 c is a reflection cavity structure of loading onto the LED tube core, and Fig. 2 d is the LED light that has reflection cavity.On demand generally again through epoxy packages.Load onto the charactron that the LED tube core constitutes by the integrated reflection cavity that this technology can partly integrally form on LED charactron (the being exactly Si(100 as shown in Figure 3) face).Also can form 5 * 7 LED character indicator spare (as shown in Figure 4) or LED array display device of 16 * 16 etc.

Claims (4)

1, a kind of manufacture craft of reflection cavity of light emitting semiconductor device is characterized in that on silicon single crystal flake growth corrosion protection layer after photoetching, corrosion plate reflector layer and form.

2, by the manufacture method of the said reflection cavity of claim 1, it is characterized in that used silicon chip is＜100〉crystal orientation, the photoetching fenestra is square or rectangle, and it is parallel with＜110〉crystal orientation on one side.

3,, it is characterized in that reflecting coating adopts gold, silver or aluminium by claim 1 or 2 said reflection cavity manufacture methods.

4, a kind of reflection cavity of light emitting semiconductor device is characterized in that with the silicon chip being matrix, is the pyramid side with (111) face of four Si, is the various square or rectangular grooves that the bottom surface constitutes with (100) face of Si, and plating is formed with reflecting coating.