芯片質(zhì)量與可靠性測(cè)試

1、芯片質(zhì)量與可靠性測(cè)試 質(zhì)量( Quality )和可靠性( Reliability )在一定程度上可以說是 IC 產(chǎn)品的生 命，好的品質(zhì)，長(zhǎng)久的耐力往往就是一顆優(yōu)秀 IC 產(chǎn)品的競(jìng)爭(zhēng)力所在。在做產(chǎn)品 驗(yàn)證時(shí)我們往往會(huì)遇到三個(gè)問題，驗(yàn)證什么，如何去驗(yàn)證，哪里去驗(yàn)證，這就 是 what, how , where 的問題了。解決了這三個(gè)問題，質(zhì)量和可靠性就有了保證，制造商才可以大量地將產(chǎn) 品推向市場(chǎng)，客戶才可以放心地使用產(chǎn)品。本文將目前較為流行的測(cè)試方法加 以簡(jiǎn)單歸類和闡述，力求達(dá)到拋磚引玉的作用。Quality 就是產(chǎn)品性能的測(cè)量，它回答了一個(gè)產(chǎn)品是否合乎SPEC 的要求，是否符合各項(xiàng)性能指標(biāo)的問

2、題； Reliability 則是對(duì)產(chǎn)品耐久力的測(cè)量，它回答了 一個(gè)產(chǎn)品生命周期有多長(zhǎng)，簡(jiǎn)單說，它能用多久的問題。所以說 Quality 解決的 是現(xiàn)階段的問題， Reliability 解決的是一段時(shí)間以后的問題。知道了兩者的區(qū)別，我們發(fā)現(xiàn)， Quality 的問題解決方法往往比較直接，設(shè) 計(jì)和制造單位在產(chǎn)品生產(chǎn)出來后，通過簡(jiǎn)單的測(cè)試，就可以知道產(chǎn)品的性能是 否達(dá)到 SPEC 的要求，這種測(cè)試在 IC 的設(shè)計(jì)和制造單位就可以進(jìn)行。相對(duì)而 言， Reliability 的問題似乎就變的十分棘手，這個(gè)產(chǎn)品能用多久， who knows? 誰 會(huì)能保證今天產(chǎn)品能用，明天就一定能用？為了解決這個(gè)問題

3、，人們制定了各 種各樣的標(biāo)準(zhǔn)，如MIT-STD-883E Method 1005.8JESD22-A108-AEIAJED- 4701-D101 等等，這些標(biāo)準(zhǔn)林林總總，方方面面，都是建立在長(zhǎng)久以來 IC 設(shè)計(jì)，制造和使用的經(jīng)驗(yàn) 的基礎(chǔ)上，規(guī)定了 IC 測(cè)試的條件，如溫度，濕度，電壓，偏壓，測(cè)試方法等，獲得標(biāo)準(zhǔn) 的測(cè)試結(jié)果。這些標(biāo)準(zhǔn)的制定使得 IC 測(cè)試變得不再盲目，變得有章可循，有法可依， 從而很好的解決的 what ， how 的問題。而 Where 的問題，由于 Reliability 的測(cè)試需要 專業(yè)的設(shè)備，專業(yè)的器材和較長(zhǎng)的時(shí)間，這就需要專業(yè)的測(cè)試單位。這種單位提供專業(yè) 的測(cè)試機(jī)臺(tái)，

4、并且根據(jù)國(guó)際標(biāo)準(zhǔn)進(jìn)行測(cè)試，提供給客戶完備的測(cè)試報(bào)告，并且力求準(zhǔn)確的 回答 Reliability 的問題在簡(jiǎn)單的介紹一些目前較為流行的 Reliability 的測(cè)試方法之前，我們先來認(rèn) 識(shí)一下 IC 產(chǎn)品的生命周期。典型的 IC 產(chǎn)品的生命周期可以用一條浴缸曲線 ( Bathtub Curve )來表示，如圖所示Region (I) 被稱為早夭期( Infancy period )這個(gè)階段產(chǎn)品的 failure rate 快速下降，造成失效的原因在于 IC 設(shè)計(jì)和生 產(chǎn)過程中的缺陷；Region (II) 被稱為使用期( Useful life period )在這個(gè)階段產(chǎn)品的 failur

5、e rate 保持穩(wěn)定，失效的原因往往是隨機(jī)的，比如EOS,溫度變化等等；Region (III) 被稱為磨耗期( Wear-Out period )在這個(gè)階段 failure rate 會(huì)快速升高,失效的原因就是產(chǎn)品的長(zhǎng)期使用所造 成的老化等。認(rèn)識(shí)了典型 IC 產(chǎn)品的生命周期,我們就可以看到, Reliability 的問題就是 要力圖將處于早夭期 failure 的產(chǎn)品去除并估算其良率,預(yù)計(jì)產(chǎn)品的使用期,并 且找到 failure 的原因,尤其是在 IC 生產(chǎn),封裝,存儲(chǔ)等方面出現(xiàn)的問題所造成 的失效原因。下面就是一些 IC Product Level reliability test i

6、tems>Robustness test itemsESD, Latch-up對(duì)于 Robustness test items 聽到的 ESD, Latch-up 問題,有很多的精彩的說 明,這里就不再錦上添花了。下面詳細(xì)介紹其他的測(cè)試方法。>Life test itemsEFR, OLT (HTOL), LTOLEFR: Early fail Rate TestPurpose: 評(píng)估工藝的穩(wěn)定性,加速缺陷失效率,去除由于天生原因失效的 產(chǎn)品。Test condition: 在特定時(shí)間內(nèi)動(dòng)態(tài)提升溫度和電壓對(duì)產(chǎn)品進(jìn)行測(cè)試Failure Mechanisms ：材料或工藝的缺陷包括諸如

7、氧化層缺陷,金屬刻鍍, 離子玷污等由于生產(chǎn)造成的失效Reference ：具體的測(cè)試條件和估算結(jié)果可參考以下標(biāo)準(zhǔn)MIT-STD-883E Method 1015.9JESD22-A108-AEIAJED- 4701-D101HTOL/ LTOL ： High/ Low Temperature Operating LifePurpose: 評(píng)估器件在超熱和超電壓情況下一段時(shí)間的耐久力Test condition: 125?C , 1.1VCC, 動(dòng)態(tài)測(cè)試Failure Mechanisms ：電子遷移,氧化層破裂,相互擴(kuò)散,不穩(wěn)定性,離子玷污等Reference ：簡(jiǎn)單的標(biāo)準(zhǔn)如下表所示，125?

8、C 條件下1000 小時(shí)測(cè)試通過IC 可以保證持續(xù)使用 4年， 2000 小時(shí)測(cè)試持續(xù)使用 8 年； 150?C 測(cè)試保證使用 8 年， 2000 小時(shí)保證使用 28 年。150?C8 years28 years125?C1000 hrs4 years2000 hrs8 years具體的測(cè)試條件和估算結(jié)果可參考以下標(biāo)準(zhǔn)MIT-STD-883E Method 1005.8 JESD22-A108-AEIAJED- 4701-D101>Environmental test itemsPRE-CON, THB, HAST, PCT, TCT, TST, HTST, Solderability

9、Test, Solder Heat TestPRE-CON: Precondition TestPurpose: 模擬 IC 在使用之前在一定濕度，溫度條件下存儲(chǔ)的耐久力，也就 是 IC 從生產(chǎn)到使用之間存儲(chǔ)的可靠性。Test Flow:Step 1: SAM (Scanning Acoustic Microscopy)Step 2: Temperature cycling- 40?C(or lower) 60?C(or higher) for 5 cycles to simulate shipping conditionsStep 3: BakingAt minimum 125?C for

10、24 hours to remove all moisture from the packageStep 4: SoakingUsing one of following soak conditions -Level 1: 85?C / 85%RH for 168 hrs（多久都沒關(guān)系）-Level 1: 85?C / 60%RH for 168 hrs（一年左右）-Level 1: 30?C / 60%RH for 192 hrs（一周左右）Step5: Reflow240?C (- 5?C) / 225?C (-5?C) for 3 times (Pb-Sn) 245?C (- 5?C)

11、/ 250?C (-5?C) for 3 times (Lead-free)* choose according the package sizeFailure Mechanisms: 封裝破裂，分層Reference ：具體的測(cè)試條件和估算結(jié)果可參考以下標(biāo)準(zhǔn) JESD22-A113-DEIAJED- 4701-B101THB: Temperature Humidity Bias TestPurpose: 評(píng)估 IC 產(chǎn)品在高溫，高壓，偏壓條件下對(duì)濕氣的抵抗能力，加速其失效進(jìn)程Test condition: 85?C ， 85%RH, 1.1 VCC, Static biasFailure M

12、echanisms ：電解腐蝕Reference ：具體的測(cè)試條件和估算結(jié)果可參考以下標(biāo)準(zhǔn)JESD22-A101-DEIAJED- 4701-D122HAST: Highly Accelerated Stress TestPurpose: 評(píng)估 IC 產(chǎn)品在偏壓下高溫，高濕，高氣壓條件下對(duì)濕度的抵抗能力，加速其失效過程Test condition: 130?C ， 85%RH, 1.1 VCC, Static bias ，2.3 atmFailure Mechanisms ：電離腐蝕，封裝密封性Reference ：具體的測(cè)試條件和估算結(jié)果可參考以下標(biāo)準(zhǔn)JESD22-A110PCT: Pres

13、sure Cook Test (Autoclave Test)Purpose: 評(píng)估 IC 產(chǎn)品在高溫，高濕，高氣壓條件下對(duì)濕度的抵抗能力，加速其失效過程Test condition: 130?C ， 85%RH, Static bias ，15PSIG ( 2 atm )Failure Mechanisms ：化學(xué)金屬腐蝕，封裝密封性Reference ：具體的測(cè)試條件和估算結(jié)果可參考以下標(biāo)準(zhǔn)JESD22-A102 EIAJED- 4701-B123*HAST 與 THB 的區(qū)別在于溫度更高，并且考慮到壓力因素，實(shí)驗(yàn)時(shí)間可以縮短，而PCT 則不加偏壓，但濕度增大。TCT: Temperatu

14、re Cycling TestPurpose: 評(píng)估 IC 產(chǎn)品中具有不同熱膨脹系數(shù)的金屬之間的界面的接觸良 率。方法是通過循環(huán)流動(dòng)的空氣從高溫到低溫重復(fù)變化。Test condition: Condition B: - 55?C to 125?CCondition C: - 65?C to 150?CFailure Mechanisms ：電介質(zhì)的斷裂，導(dǎo)體和絕緣體的斷裂，不同界面的分層Reference ：具體的測(cè)試條件和估算結(jié)果可參考以下標(biāo)準(zhǔn)MIT-STD-883E Method 1010.7JESD22-A104-AEIAJED- 4701-B-131TST: Thermal Shoc

15、k TestPurpose: 評(píng)估 IC 產(chǎn)品中具有不同熱膨脹系數(shù)的金屬之間的界面的接觸良 率。方法是通過循環(huán)流動(dòng)的液體從高溫到低溫重復(fù)變化。Test condition: Condition B: - 55?C to 125?CCondition C: - 65?C to 150?CFailure Mechanisms ：電介質(zhì)的斷裂，材料的老化（如 bond wires ） , 導(dǎo)體機(jī) 械變形Reference ：具體的測(cè)試條件和估算結(jié)果可參考以下標(biāo)準(zhǔn)MIT-STD-883E Method 1011.9JESD22-B106EIAJED- 4701-B-141* TCT 與 TST 的區(qū)別

16、在于 TCT 偏重于 package 的測(cè)試，而 TST 偏重于晶園的測(cè) 試HTST: High Temperature Storage Life TestPurpose: 評(píng)估 IC 產(chǎn)品在實(shí)際使用之前在高溫條件下保持幾年不工作條件 下的生命時(shí)間。Test condition: 150?CFailure Mechanisms ：化學(xué)和擴(kuò)散效應(yīng)， Au-Al 共金效應(yīng)Reference ：具體的測(cè)試條件和估算結(jié)果可參考以下標(biāo)準(zhǔn)MIT-STD-883E Method 1008.2JESD22-A103-AEIAJED- 4701-B111Solderability TestPurpose: 評(píng)估

17、 IC leads 在粘錫過程中的可考度Test Method: 1. 蒸汽老化 8 小時(shí)2. 侵入 245?C 錫盆中 5 秒Failure Criterion ：至少 95 良率Reference ：具體的測(cè)試條件和估算結(jié)果可參考以下標(biāo)準(zhǔn)MIT-STD-883E Method 2003.7 JESD22-B102SHT Test: Solder Heat Resistivity TestPurpose: 評(píng)估 IC 對(duì)瞬間高溫的敏感度Test Method: 侵入 260?C 錫盆中 10 秒Failure Criterion ：根據(jù)電測(cè)試結(jié)果Reference ：具體的測(cè)試條件和估算結(jié)果

18、可參考以下標(biāo)準(zhǔn)MIT-STD-883E Method 2003.7EIAJED- 4701-B106>Endurance test itemsEndurance cycling test, Data retention testEndurance Cycling TestPurpose: 評(píng)估非揮發(fā)性 memory 器件在多次讀寫算后的持久性能Test Method: 將數(shù)據(jù)寫入 memory 的存儲(chǔ)單元，在擦除數(shù)據(jù)，重復(fù)這個(gè)過 程多次Test condition: 室溫，或者更高，每個(gè)數(shù)據(jù)的讀寫次數(shù)達(dá)到 100k1000kReference ：具體的測(cè)試條件和估算結(jié)果可參考以下標(biāo)準(zhǔn) M

19、IT-STD-883E Method 1033Data Retention TestPurpose: 在重復(fù)讀寫之后加速非揮發(fā)性 memory 器件存儲(chǔ)節(jié)點(diǎn)的電荷損失Test condition: 在高溫條件下將數(shù)據(jù)寫入 memory 存儲(chǔ)單元后，多次讀取驗(yàn) 證單元中的數(shù)據(jù)Failure Mechanisms ： 150?CReference ：具體的測(cè)試條件和估算結(jié)果可參考以下標(biāo)準(zhǔn)MIT-STD-883E Method 1008.2MIT-STD-883E Method 1033在了解上述的 IC 測(cè)試方法之后， IC 的設(shè)計(jì)制造商就需要根據(jù)不用 IC 產(chǎn)品的 性能，用途以及需要測(cè)試的目的，

20、選擇合適的測(cè)試方法，最大限度的降低 IC 測(cè)Bathtub CurveTypical fa11uf« rat« cum of IC product*Basic FA FlowsEvery experienced failure analyst knows that every FA is unique. Nobody can truly say that he or she has developed a standard FA flow for every FA that will come his or her way. FA's have a tendency

21、 of directing themselves, with each subsequent step depending on the outcome of the previous step.The flow of an FA is influenced by a multitude of factors: the device itself, the application in which it failed, the stresses that the device has undergone prior to failure, the point of failure, the f

22、ailure rate, the failure mode, the failure attributes, and of course, the failure mechanism. Nonetheless, FA is FA, so it is indeed possible to define to a certain degree a 'standard' FA flow for every failure mechanism.This article aims to give the reader a basic idea of how the FA flow for

23、 a given failure mechanism may be standardized. 'Standardization' in this context does not mean defining a step-by-step FA procedure to follow, but rather what to look for when analyzing failures depending on what the observed or suspected failure mechanism is.Basic Die-level FA Flow1) Failu

24、re Information Review. Understand thoroughly the customer's description of the failure. Determine: a) the specific electrical failure mode that the customer is experiencing; b) the point of failure or where the failure was encountered (field or manufacturing line and at which step?); c) what con

25、ditions the samples have already gone through or been subjected to; and d) the failure rate observed by the customer.2) Failure Verification. Verify the customer's failure mode by electrical testing. Check the datalog results for consistency with what the customer is reporting.3) External Visual

26、 Inspection. Perform a thorough external visual inspectionon the sample. Noteallmarkings on the package and look for external anomalies, i.e., missing/bent leads, package discolorations, package cracks/chip-outs/scratches, contamination, lead oxidation/corrosion, illegible marks, non-standard fonts,

27、 etc.4) Bench Testing. Verify the electrical test results by bench testing to ensure that all ATE failures are not due to contact issues only. The ideal case is for the customer's reported failure mode, ATE results, and bench test results to be consistent with each other.5) Curve Tracing. Perfor

28、m curve tracing to identify which pins exhibit current/voltage (I/V) anomalies. The objective of curve tracing is to look for open or shorted pins and pins with abnormal I/V characteristics (excessive leakage, abnormal breakdown voltages, etc.). FA may then be focused on circuits involving these ano

29、malous pins. Dynamic curve tracing, wherein the unit is powered up while undergoing curve tracing, may be performed if static curve tracing does not reveal any anomalies.6) X-ray Inspection. Perform x-ray inspection to look for internal package anomalies such as broken wires, missing wires, incorrec

30、t or missing die, excessive die attach voids, etc, without having to open the package. Xray inspection results must be consistent with curve trace results, e.g., if x-ray inspection revealed a broken wire at a pin, then curve tracing should reveal that pin to be open.7) CSAM. Perform CSAM on plastic

31、 packages to determine if the samples have any internal delaminations that may lead to other failure attributes such as corrosion, broken wires, and lifted bonds.8) Decapsulation. Once all the non-destructive steps such as those above have been completed, the samples may be subjected to decapsulatio

32、n to expose the die and other internal features of the device for further FA.9) Internal Visual Inspection. Perform internal visual inspection after decap. This is usually done using a low-power microscope and a high-power microscope, proceeding from low magnification to higher ones.Look for wire/bo

33、nd anomalies, die cracks, wire and die corrosion, die scratches, EOS/ESD sites, fab defects, and the like. SEM inspection may be needed in some instances.10) Hot Spot Detection. If curve trace results indicate some major discrepancies between the I/V characteristics (especially with regard to power dissipation) of the samples and known good