CN104646314A - Method for screening LED core particles - Google Patents
Method for screening LED core particles Download PDFInfo
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- CN104646314A CN104646314A CN201510051000.9A CN201510051000A CN104646314A CN 104646314 A CN104646314 A CN 104646314A CN 201510051000 A CN201510051000 A CN 201510051000A CN 104646314 A CN104646314 A CN 104646314A
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Abstract
The invention discloses a method for screening LED core particles, which is particularly suitable for screening LED core particles with unfavorable forward current leakage produced in the later machining process (including thinning a substrate, cutting a wafer, automatic sorting, etc.) after the photoelectric parameter test. The method comprises the steps of exciting a light source and an optical filter to acquire exciting light of a fixed waveband, illuminating the to-be-tested LED core particles by virtue of the exciting light, observing and analyzing intensity and color distribution of a fluorescent image of the LED core particles by virtue of a blocking optical filter and an optical microscope, wherein the normal LED core particles and the LED core particles with unfavorable forward current leakage are different in fluorescent intensity and different in colors, so that the unqualified LED core particles can be screened. The method is intuitive, convenient, high in resolution ratio and low in cost; moreover, the LED core particles do not need to be touched, so that the secondary damage of the core particles can be avoided.
Description
Technical field
The invention belongs to semiconductor light emitting field, especially relate to a kind of screening technique of LED core particle.
Background technology
Be limited to the technology of preparing of epitaxial material, the LED wafer of current full wafer is also difficult to meet human eye to the conforming requirement of photoelectric characteristic, therefore before the follow-up encapsulation of input, need to carry out strict detection to LED wafer, then will have the conforming LED core particle of photoelectricity again according to the testing result of wafer and be sorted into together (LED wafer is divided into a large amount of LED core particle).But; in LED wafer after photoelectric parameter testing; usually also will through technological processes such as substrate thinning, wafer cutting and automatic sortings; and in these processes; likely there is the underproof LED core particle of new photoelectric parameter in LED film, the dominant failure feature of these defective LED core particle is exactly occur forward leakage current increase in various degree under the effect of mechanical force, electrostatic, pollutant etc.Thus, the defective LED core particle of some will be mixed in the qualified LED core particle gone out according to LED wafer photoelectric parameter testing result automatic sorting.If this part underproof core grain flows into encapsulated phase, the obvious increase of the decline of LED yield and cost will be caused, bring reliability hidden danger to device application simultaneously.
In order to screen out above-mentioned underproof LED core particle further, current industrial circle normally adopts ordinary optical microscope picking, but bad order product can only be rejected by this method, the core grain leaking electricity bad for the qualified forward of outward appearance then cannot effectively be rejected, and this method resolution ratio is lower, speed is slow.
summary of the invention:
The object of the invention is to the screening technique proposing a kind of LED core particle, it is effectively screened out by the fluoroscopic image of observation analysis LED core particle to be measured has forward and to leak electricity bad LED core particle, this method is directly perceived, convenient, resolution ratio is high, cost is low, and without the need to contacting LED core particle, the secondary damage of core grain can not be caused.
The object of the present invention is achieved like this:
A kind of screening technique of LED core particle, feature is: first send exciting light by excitation source, exciter filter is equipped with in subsequent optical path, exciter filter filters exciting light to obtain the exciting light of fixed band, again this exciting light is radiated in LED core particle to be measured and excites LED core particle, then by the fluoroscopic image of the blocking-up optical filter directly over LED core particle and observation by light microscope LED core particle, qualified LED core particle, screen out forward leak electricity defective LED core particle (forward electric leakage qualified namely when the voltage at LED core particle electrode two ends is 1.8V, forward current is less than 1uA, otherwise then forward electric leakage is defective).
The excitation wavelength obtained through exciter filter is less than the emission wavelength of LED core particle itself, can excite LED core particle emitting fluorescence smoothly.The royal purple light of blue-ray LED core grain wavelength between 390nm ∽ 460nm excites, and the blue light of green light LED core grain wavelength between 460nm to 500nm excites.
Described blocking-up optical filter, in order to block the reverberation of various veiling glare and exciting light, only through the fluorescence that LED core particle is launched.
Before screening LED core particle, have passed through wafer detections successively, substrate thinning, wafer cut and the step of core grain sorting.
Operation principle:
When LED core particle is penetrated in illumination, the photon that carrier can absorb certain wavelength transits to the higher excitation state of energy by lower state, usually can discharge the light of specific wavelength, be fluorescence when returning lower state.The fluorescence of LED core particle is formed primarily of yellow luminescence two parts of quantum well radiation and GaN material.Wherein, the luminous zone of SQW and LED core particle, the yellow luminescence of the luminescence mechanism of SQW, emission wavelength and luminous intensity and GaN material all has a great difference.In emission wavelength, the color of common GaN base LED has blue light and green glow two kinds.About luminous intensity, under normal circumstances SQW send out intensity much larger than the yellow luminescence of GaN material, usually at the fluoroscopic image of viewed LED core particle at the yellow luminescence cannot seeing GaN material.But, when the PN junction of LED core particle occurs that forward leaks electricity, quantum well radiation will occur that non-uniform light, luminescence are more weak or not luminous, and at this time the yellow luminescence of GaN material no longer can be ignored in whole fluorescent light beam, will cause the intensity of fluorescence, color generation significant change.It is pointed out that the mechanism due to GaN yellow luminescence is different from SQW, insensitive to forward electric leakage, that is forward electric leakage does not have a significant effect to the intensity of GaN yellow luminescence.
Illustrate for GaN base blue led core grain below, when there is the electric leakage of less forward in blue led core grain, its SQW send out blue-fluorescence and can leak electricity core grain qualified and die down by relative forward, by contrasting normal LED core particle and there is the leak electricity intensity of blue-fluorescence of LED core particle of less forward and can filter out the bad core grain that leaks electricity; When there is forward electric leakage largely in LED core particle, blue led core grain SQW turns blue look fluorescence intensity can degradation, now the yellow luminescence of GaN material just can not send out by SQW blue-fluorescence cover, SQW blue light there will be white light after mixing with GaN yellow luminescence, from SQW to send out blue-fluorescence completely different, thus be easy to differentiate; When the electric leakage of blue led core grain is very serious, SQW is completely not luminous, and be now only left GaN yellow luminescence, LED core particle presents yellow fluorescence, is very easy to differentiate yet.
The intensity of the fluoroscopic image of LED core particle and distribution of color can embody the size of LED core particle forward leakage current, and applicant screens out forward by the fluoroscopic image of observation analysis LED core particle to be measured and to leak electricity bad LED core particle.The present invention first obtains the exciting light of fixed band by excitation source and exciter filter, again exciting light is radiated in LED core particle to be measured, then by blocking the fluoroscopic image of optical filter and observation by light microscope LED core particle, qualified LED core particle, screen out forward and to leak electricity defective LED core particle.
The present invention screens out defective LED core particle by observing fluoroscopic image, very intuitively, conveniently; The fluoroscopic image of LED core particle clearly can show the luminous pattern of LED core particle, evenly whether core grain luminous, the whether forward electric leakage of core grain, the position of leakage point of electricity, the latency that whether has micro-crack etc. to affect core grain quality in core grain can clearly be observed, and resolution ratio is very high; The fluoroscopic image observing LED core particle only needs simple ripe device, and cost is low; The present invention, without the need to contacting LED core particle, can not cause the secondary damage of core grain.
Therefore, the present invention has intuitively, facilitates, resolution ratio is high, cost is low, can not cause the advantage of the secondary damage of core grain without the need to contacting LED core particle.
accompanying drawing illustrates:
Fig. 1 is principle schematic of the present invention, and wherein, Reference numeral 1-excitation source, 2-exciter filter, 3-LED core grain, 4-blocks optical filter, 5-light microscope.
detailed description of the invention:
Below in conjunction with the drawings and specific embodiments, the present invention is described in detail.It should be noted that, accompanying drawing of the present invention all adopts the non-accurate ratio simplified very much, only in order to convenient, distinct aid illustration the present invention.
As shown in Figure 1, a kind of screening technique of LED core particle 3, first by LED core particle successively through wafer detection, substrate thinning, wafer cutting and the step of core grain sorting, exciting light is sent again by excitation source 1, exciter filter 2 is equipped with in subsequent optical path, the light that exciter filter 2 will be selected through fixed band, excite LED core particle 3(to be measured usual, the blue-ray LED core grain 3 royal purple light of wavelength between 390nm ∽ 460nm excites, green light LED core grain 3 blue light of wavelength between 460nm to 500nm) excite; In other words, through exciter filter 2 through optical wavelength need to be less than the emission wavelength of the LED core particle 3 that is excited, could effectively excite LED core particle 3 to send corresponding fluorescence.
Just can judge that the forward leakage current of LED core particle 3 is whether in acceptability limit by the intensity of fluoroscopic image and distribution of color of observing LED core particle 3, and then forward can be screened out to leak electricity underproof LED core particle.In order to clearly observe the fluoroscopic image of LED core particle 3, being equipped with in follow-up light path and blocking optical filter 4, in order to block the reverberation of various veiling glare and exciting light.Because LED core particle 3 is less, usually between submillimeter level to grade, so the fluoroscopic image of LED core particle 3 observed by the present invention's light microscope 5.
Claims (5)
1. the screening technique of a LED core particle, it is characterized in that: first send exciting light by excitation source, exciter filter is equipped with in subsequent optical path, exciter filter filters exciting light to obtain the exciting light of fixed band, again this exciting light is radiated in LED core particle to be measured and excites LED core particle, then by the fluoroscopic image of the blocking-up optical filter directly over LED core particle and observation by light microscope LED core particle, forward leaks electricity qualified LED core particle, screen out forward and to leak electricity defective LED core particle; Qualified namely when the voltage at LED core particle electrode two ends is 1.8V to electric leakage, forward current is less than 1uA; Otherwise then forward electric leakage is defective.
2. screening technique according to claim 1, is characterized in that: described exciter filter is in order to select through the light of certain wave band to excite LED core particle.
3. screening technique according to claim 1, it is characterized in that: the excitation wavelength obtained through exciter filter is less than the emission wavelength of LED core particle itself, LED core particle emitting fluorescence can be excited smoothly, the royal purple light of blue-ray LED core grain wavelength between 390nm ∽ 460nm excites, and the blue light of green light LED core grain wavelength between 460nm to 500nm excites.
4. screening technique according to claim 1, is characterized in that: block optical filter in order to block the reverberation of various veiling glare and exciting light, the fluorescence only launched through described LED core particle.
5. screening technique according to claim 1, is characterized in that: described LED core particle: before experience screening, have passed wafer cutting, automatic sorting operation.
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| CN201510051000.9A CN104646314A (en) | 2015-02-02 | 2015-02-02 | Method for screening LED core particles |
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| CN201510051000.9A CN104646314A (en) | 2015-02-02 | 2015-02-02 | Method for screening LED core particles |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106124548A (en) * | 2016-06-23 | 2016-11-16 | 中山德华芯片技术有限公司 | A kind of the hidden of composite construction SiC substrate cuts experimental test procedures |
| CN109287110A (en) * | 2017-07-20 | 2019-01-29 | 日本梅克特隆株式会社 | Substrate position identification device, position identification processing unit (plant) and manufacture of substrates |
| CN110600401A (en) * | 2019-08-26 | 2019-12-20 | 格力电器（合肥）有限公司 | Screening method for early failure of light-emitting diode |
| CN110788025A (en) * | 2019-11-14 | 2020-02-14 | 广西立盛茧丝绸有限公司 | Fluorescence spectrum cocoon selection method |
| CN111715561A (en) * | 2020-06-28 | 2020-09-29 | 厦门理工学院 | Detection device and method for Micro-LED display substrate |
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| CN110788025A (en) * | 2019-11-14 | 2020-02-14 | 广西立盛茧丝绸有限公司 | Fluorescence spectrum cocoon selection method |
| CN111715561A (en) * | 2020-06-28 | 2020-09-29 | 厦门理工学院 | Detection device and method for Micro-LED display substrate |
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