Complaint Case-LED Chip Problem

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Contents

Ø ESD damage

l    ESD的產生

l    靜電傷害的現象

l     ESD的防護

Ø Thyristor Effect

l     LED的Thyristor現象

l    LED的Thyristor特性

l    Thyristor的篩除

Ø Investigation of Failure Conditions

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半導體失效原因的排序

EOS/ESD is the #1 Cause of

Semiconductor Failure

Source : Semiconductor Reliability News, March 1993

 EOS/ESD 59%

 Electrical testing 3%

 Oxide/passivation failure 3%  Conductor failure 3%

 Die fracture 4%

 Lead short/open 7%

 Wire bonds 15%

Others 6%

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ESD damage

ESD的產生

Electrostatic generation arising from friction between two materials is called triboelectric charging.It occurs when two materials are separated or rubbed together. Examples include:

•Opening a common plastic bag.

•Removing adhesive tape from a roll or container. •Walking across a floor.

•Transporting computer boards or components around in their trays on carts.

•Sliding circuit boards on a work bench.

When handling parts or their containers, ungrounded personnel can transfer high static charges.Unless these static charges are slowly

靜電傷害的現象

二、三元或四元晶片

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靜電傷害的現象

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大電流Burn-out表面現象

二、三元或四元晶片

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靜電傷害的現象

藍光晶片

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ESD的防護

Solutions to Static Problems

•Prevention (預防) of Charge Generation

•Neutralization (中和) of Charge

•Shielding (遮蔽) from Electrostatic Field

•Dissipation (消散) of Charge

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Thyristor Effect

Thyristor

閘流體是指需要快速脈衝控制電流以啟動的電子開關，在控制 脈衝電流停止後，閘流體仍繼續作業，閘流體由P型和N型物質

交錯組成，在電流反向流通時，如同傳統的整流器般作用，而

在電流正向流通時，則如同開關的整流器組合作業

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LED的Thyristor 現象

LED上產生閘流體，是表示LED有缺陷，指在晶片磊晶時

的缺陷所造成非生產製程上造成，簡單說就是電壓對電流 的曲線與正常不同，不正常曲線在某電壓範圍，電流並沒 有相對提高，可能造成LED無法驅動等缺陷

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LED的Thyristor特性

用電壓源驅動LED無法觀察到Thyristor現象，當使用電

流源時才可觀察此現象

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Thyristor的篩除

1. 以不同電流源量測相對電壓值 判定標準

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Thyristor的篩除

2.固定小電流量測相對電壓值是否在正常晶片的電壓範

圍

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Investigation of Failure Conditions

Specific information is collected:

•            Time and place of failure occurrence or detection(Was the failure detected during processing, at acceptance inspection, in the field, during reliability testing, or under other circumstances?)

•            Type of machine in which the part was being used, operating environment, stockroom conditions (temperature, humidity, atmosphere), storage period, operating time and operating conditions (source, voltage, frequency, load)

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•            Lot number, time of production, history

•          Failure rate, lot dependence, conditions of past failures

•          Symptoms (complete failure, partial malfunction, change in characteristics)

•            Recurrence (stable, intermittent, dependent on temperature or other operating conditions)

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