CN102841281B - Detection method and device for LED epitaxial wafer - Google Patents
Detection method and device for LED epitaxial wafer Download PDFInfo
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- CN102841281B CN102841281B CN201210347164.2A CN201210347164A CN102841281B CN 102841281 B CN102841281 B CN 102841281B CN 201210347164 A CN201210347164 A CN 201210347164A CN 102841281 B CN102841281 B CN 102841281B
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Abstract
The invention discloses a detection method and device for an LED epitaxial wafer. The method comprises the following steps: exerting an AC square wave voltage between the lower and the upper ends of the LED epitaxial wafer, wherein the intensity of the AC square wave voltaic voltage is large enough to drive the LED epitaxial wafer to give out light. The detection device comprises a conductive substrate used for bearing the LED epitaxial wafer and being in contact with the lower end surface of the LED epitaxial wafer, a conductive probe in contact with the upper end surface of the LED epitaxial wafer, and an AC square wave voltage source used for exerting the AC square wave voltage between the conductive substrate and the conductive probe, wherein the intensity of the AC square wave voltaic voltage is large enough to drive the LED epitaxial wafer to give out light. Compared with a current probe type electroluminescence (EL) test method, the detection method provided by the invention has the advantages that only the probe is required, operations of clicking an In point and the like are avoided, and the LED epitaxial wafer can not be polluted or damaged, and also has the advantages of simplicity in operation, high efficiency, quickness, low cost, and stable and accurate test result. Therefore, the detection method can be used for on-line EL test of various LED epitaxial wafers, and has strong universality.
Description
Technical field
The present invention be more particularly directed to a kind of LED detection method and device.
Background technology
Along with the continuous progress of semiconductor technology, if LED, photovoltaic cell, semiconductor laser etc. semiconductor devices is by people's widespread use in daily life, work.For the quality in guarantee semiconductor devices production run and cost control, generally need to carry out various on-line performance test to it in semiconductor devices production run.For LED, in LED processing procedure, usually need to carry out EL test (electroluminescent properties test) to LED.Such as, consult Fig. 1, for the LED 10 with sapphire insulation substrate 12, existing EL method of testing is generally a sidepiece point In point 20 of the semiconductor material layer 110 in LED 10, and contact with the upper surface of LED with conducting probe, between this conducting probe and In point 20, apply DC voltage afterwards, thus realize EL test.But this kind of EL method of testing exists number of drawbacks, such as:
One, this method of testing operation inconvenience, such as, because use In as contact, need heating to execute In point position, and high-purity In is with high costs during operation;
Its two, after this method of testing is completed, can in LED residual In, thus LED to be polluted, affects its quality;
Its three, need at least two conducting probes in this method of testing, and be employing DC voltage, the test wavelength of EL can change with size of current, not only can affect the accuracy of test result, and LED may be caused impaired.
Summary of the invention
An object of the present invention is to provide a kind of LED detection method, and it has and is easy to operation, with low cost, and the feature such as test result is accurate, thus overcome deficiency of the prior art.
For achieving the above object, the LED detection method that the present invention adopts can comprise:
Between the upper and lower end face of LED, apply an ac square-wave voltage, and the size of described ac square-wave voltage is enough to the luminescence of driving LED epitaxial wafer.
Further, this LED detection method can also comprise:
LED is placed in a conductive substrates, and the upper and lower end face of described LED is contacted with a conducting probe and conductive substrates respectively,
And, between described conductive substrates and conducting probe, apply one exchange (AC) ac square-wave voltage, and the size of described ac square-wave voltage is enough to the luminescence of driving LED epitaxial wafer.
Another object of the present invention is to provide a kind of LED pick-up unit, comprising:
One for carrying the conductive substrates of LED, and described conductive substrates contacts with LED lower surface;
One conducting probe, it contacts with the upper surface of LED,
And for applying the ac square-wave voltage source of an ac square-wave voltage between described conductive substrates and conducting probe, the size of described ac square-wave voltage is enough to the luminescence of driving LED epitaxial wafer.
One of preferably, the size of aforementioned ac square-wave voltage is 2-250V, is especially preferably 3-60V.
One of preferably, the frequency of described ac square-wave voltage is 50-1MHz.
Further, described LED bottom is provided with substrate, and the lower surface of described substrate contacts with conductive substrates.
Further, described conducting probe can be electrically connected with a pole in ac square-wave voltage source, and described conductive substrates can ground connection or be electrically connected with another pole in ac square-wave voltage source.
Further, aforesaid substrate can be selected from the known all kinds of conduction in this area or dielectric substrate, especially the dielectric substrate of the material such as sapphire, but is not limited thereto.
Further, described conductive substrates can comprise metal dish, but is not limited thereto.
Compared with prior art, the present invention at least has following good effect:
(1) this LED detection method without the need to putting In in LED, and only can need implement by a conductive substrates and a conducting probe, simple to operate, with low cost, efficiency is high, can realize on-line checkingi, and any pollution can not be caused to LED, thus its quality of energy effective guarantee;
(2) this LED detection side genealogy of law adopts alternating voltage, and particularly ac square-wave voltage is tested LED, and wavelength is not easy with size of current change, and result is stablized, and can not cause damage to the structure of LED.
(3) this LED detection method and device are suitable for carrying out EL test to the LED of any type, have versatility, effectively can reduce the cost of user.
Accompanying drawing explanation
Fig. 1 is the schematic diagram of existing LED EL method of testing;
Fig. 2 is the schematic diagram of LED EL method of testing of the present invention;
Fig. 3 is one of equivalent circuit diagram of LED EL method of testing of the present invention;
Fig. 4 is the equivalent circuit diagram two of LED EL method of testing of the present invention;
Fig. 5 is the structural representation of LED EL proving installation in a preferred embodiment of the present invention;
Description of reference numerals: LED 10, semiconductor material layer 110, semiconductor material P-type layer 11, semiconductor material Multiple Quantum Well (MQW) layer 11 ', semiconductor material N-type layer 11 ", dielectric substrate 12, In point 20, conductive substrates 30, conducting probe 40, equivalent series resistance R
s, equivalent parallel resistance R
p, equivalent capacity C, equivalent diode D, Sapphire Substrate 111, U-shaped GaN layer 112, N-type GaN layer 113, MQWs(multi-quantum pit structure) 114, P type GaN layer 115, metal dish 3, metal probe 4.
Embodiment
Because many defects of existing EL method of testing, the invention provides a kind of LED detection method and device, as follows its technical scheme is further explained.
LED detection method of the present invention is mainly achieved by the following technical solution, that is: between the upper and lower end face of LED, apply an ac square-wave voltage, and the size of described ac square-wave voltage is enough to the luminescence of driving LED epitaxial wafer.
Further, consult Fig. 2, this LED detection method can be implemented by a LED pick-up unit, and this LED pick-up unit can comprise conductive substrates 30, conducting probe 40 and an ac square-wave voltage source (not shown).
This LED detection method can comprise:
LED 10 is placed in a conductive substrates 30, and the upper surface of described LED 10 is contacted with a conducting probe 40 and conductive substrates 30 respectively with the substrate 12 of bottom,
And, between described conductive substrates 30 and conducting probe 40, apply an ac square-wave voltage, and the size of described ac square-wave voltage is enough to driving LED epitaxial wafer 10 luminescence.
Consult the equivalent circuit diagram formed by conductive substrates, conducting probe and tested LED in this LED EL method of testing of Fig. 3 system, if aforesaid substrate 12 is dielectric substrate, then this equivalent electrical circuit system comprises by semiconductor material P-type layer 11 in LED 10, Multiple Quantum Well (MQW) layer 11 ' and N-type layer 11 " the equivalent PN junction diode D that formed and equivalent parallel resistance R
p, primarily of semiconductor material P-type layer 11 and N-type layer 11 " self resistance formed an equivalent series resistance R
s, and in conductive substrates 30 and semiconductor material N-type layer 11 " between the equivalent capacity C that formed.
When applying a size and be enough to the ac square-wave voltage of driving LED epitaxial wafer 10 luminescence between conductive substrates 30 and conducting probe 40, if LED 10 is normal, then:
When conducting probe is in noble potential, equivalent diode D conducting, equivalent capacity C charges, and electric current is uniflux in equivalent electrical circuit, makes LED 10 luminous;
And when conducting probe is in electronegative potential, then equivalent diode D closes, equivalent capacity C is by equivalent parallel resistance R
pelectric discharge, LED 10 is not luminous.
The size of aforementioned ac square-wave voltage and frequency can be that those skilled in the art suitably select according to the needs of practical application.
One of preferably, the size of aforementioned ac square-wave voltage can be 2-250V, is especially preferably 3-60V.
One of preferably, the frequency of aforementioned ac square-wave voltage can be 50-1MHz.
Postscript, aforesaid ac square-wave voltage source can realize by all kinds of ac square-wave voltage generation equipment of commonly seeing.
Again and, as a selectable embodiment of the present invention, in this LED detection method, conducting probe 40 can be electrically connected with a pole in ac square-wave voltage source, and be electrically connected by conductive substrates 30 ground connection or with another pole in ac square-wave voltage source.
Aforesaid substrate 12 can comprise Sapphire Substrate, but is not limited thereto.
And if aforesaid substrate 12 is employing conductive substrates, then in EL method of testing, as shown in Figure 4, it comprises by semiconductor material P-type layer 11 in LED 10, Multiple Quantum Well (MQW) layer 11 ' and N-type layer 11 structure of the equivalent circuit diagram formed by conductive substrates, conducting probe and tested LED " the equivalent PN junction diode D that formed and equivalent parallel resistance R
p, primarily of semiconductor material P-type layer 11 and N-type layer 11 " self resistance formed an equivalent series resistance R
s.
When applying a size and be enough to the ac square-wave voltage of driving LED epitaxial wafer 10 luminescence between conductive substrates 30 and conducting probe 40, if LED 10 is normal, then:
When conducting probe is in noble potential, equivalent diode D conducting, electric current is uniflux in equivalent diode, makes LED 10 luminous;
And when conducting probe is in electronegative potential, then equivalent diode D closes, LED 10 is not luminous.
Below in conjunction with a preferred embodiment, technical scheme of the present invention is further described.
Consult Fig. 5, the present embodiment system relates to a kind of method of LED of commonly seeing being carried out to EL test, the method is by a LED EL proving installation, and this device comprises metal dish 3, metal probe 4 and an ac square-wave voltage source (not shown).
This LED of commonly seeing comprises the Sapphire Substrate 111 of thick about 5-1000 μm, and described Sapphire Substrate 111 is formed with U-shaped GaN layer 112, N-type GaN layer 113, MQWs(multi-quantum pit structure successively) 114, P type GaN layer 115.
When carrying out EL test, this LED system that commonly sees is placed on described metal dish 3, and its substrate floor contacts with metal dish 3, and metal probe 4 to be commonly see with this upper surface of LED contact,
This metal probe 4 is also electrically connected with a pole in an ac square-wave voltage source, and this metal dish 3 can ground connection or be electrically connected with another pole in this ac square-wave voltage source, when opening ac square-wave voltage source, and when applying an ac square-wave voltage between this metal probe 4 and metal dish 3, then when conducting probe noble potential, this LED is by normal luminous, and when electronegative potential, this LED is not luminous.
The size of aforementioned ac square-wave voltage can be 2-250V, and be preferably 3-60V, frequency can be 50-1MHz.
So, by aforesaid simple test method and apparatus, can complete and test the EL of LED of commonly seeing, it, than existing EL method of testing, only needs Single probe, without the need to operations such as In, not only simple to operate, efficient quick, with low cost, can not pollute or damage LED, and test result is accurately stable.
Utilize the present invention can realize testing the online EL of all kinds LED.
Above-described embodiment, only for technical conceive and the feature of the present invention are described, its object is to person skilled in the art can be understood content of the present invention and implement according to this, can not limit the scope of the invention with this.All equivalences done according to Spirit Essence of the present invention change or modify, then all should be encompassed within protection scope of the present invention.
Claims (8)
1. a LED detection method, is characterized in that, it comprises:
LED is placed in a conductive substrates, and the upper surface of the semiconductor material layer being positioned at described LED top is contacted with a conducting probe, make the lower surface of the substrate being positioned at described LED bottom contact with a conductive substrates simultaneously,
And, between described conductive substrates and conducting probe, apply an ac square-wave voltage, and the size of described ac square-wave voltage is enough to the luminescence of driving LED epitaxial wafer.
2. LED detection method according to claim 1, is characterized in that, the size of described ac square-wave voltage is 2-250V.
3. a LED pick-up unit, is characterized in that, it comprises:
For carrying the conductive substrates of LED, and described conductive substrates contacts with the lower surface of the substrate being positioned at LED bottom;
Conducting probe, it contacts with the upper surface of the semiconductor material layer being positioned at LED top,
And for applying the ac square-wave voltage source of an ac square-wave voltage between described conductive substrates and conducting probe, the size of described ac square-wave voltage is enough to the luminescence of driving LED epitaxial wafer.
4. LED pick-up unit according to claim 3, is characterized in that, the size of described ac square-wave voltage is 2-250V.
5. LED pick-up unit according to claim 4, is characterized in that, the size of described ac square-wave voltage is 3-60V.
6. the LED pick-up unit according to any one of claim 3-5, is characterized in that, described conducting probe is electrically connected with a pole in ac square-wave voltage source, described conductive substrates ground connection or be electrically connected with another pole in ac square-wave voltage source.
7. LED pick-up unit according to claim 3, is characterized in that, described substrate comprises dielectric substrate or conductive substrates, and described dielectric substrate comprises Sapphire Substrate.
8. LED pick-up unit according to claim 3, is characterized in that, described conductive substrates comprises metal dish.
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| CN100418203C (en) * | 2002-07-05 | 2008-09-10 | 清华大学 | LED epitaxial wafer electroluminescent nondestructive detection method |
| TWI272874B (en) * | 2002-08-09 | 2007-02-01 | Semiconductor Energy Lab | Organic electroluminescent device |
| KR100495215B1 (en) * | 2002-12-27 | 2005-06-14 | 삼성전기주식회사 | VERTICAL GaN LIGHT EMITTING DIODE AND METHOD OF PRODUCING THE SAME |
| TWM255514U (en) * | 2003-10-16 | 2005-01-11 | Arima Optoelectronics Corp | Structure improvement of Gallium Indium Nitride light-emitting diode |
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| CN101599523A (en) * | 2009-06-01 | 2009-12-09 | 广东昭信光电科技有限公司 | The light emitting diode (LED) chip with vertical structure and the manufacture method thereof that adopt conducting polymer to shift |
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