Introduction to DRAM Testing--- DRAM inside team --- 2015.MayAgendanBasis of TestingnTypical DRAM Testing FlownBurn-innDC Test (Open/Short, Leakage, IDD)nFunctional Test ↑(r0,w1);↑(r1,w0);↓(r0,w1);↓(r1,w0); ↓(r0) Operation Count: 10*n Scan type: X-Scan (X inc -> Y inc), Y-Scan(Y inc -> X inc) Fault Coverage: Most of Failure Mode0 00 00 00 0 0 00 00 00 0 0 00 00 00 0 0 00 00 00 00 00 00 00 0 0 00 00 00 0 0 00 00 00 0 0 00 00 0R0R00 00 00 00 0 0 00 00 00 0 0 00 00 00 0 0 00 00 0W1W10 00 00 00 0 0 00 00 00 0 0 00 00 00 0 0 00 0R0R01 10 00 00 00 0 0 00 00 00 0 0 00 00 00 0 0 00 0W1W11 10 00 00 00 0 0 00 00 00 0 0 00 00 00 0 0 0R0R01 11 10 00 00 00 0 0 00 00 00 0 0 00 00 00 0 0 0W1W11 11 10 00 00 00 0 0 00 00 00 0 0 00 00 00 0R0R01 11 11 10 00 00 00 0 0 00 00 00 0 0 00 00 00 0W1W11 11 11 10 00 00 00 0 0 00 00 00 0 1 11 11 11 1 1 11 11 11 10 00 00 00 0 1 11 11 11 1 1 11 11 11 1 1 11 11 11 11 11 11 11 1 1 11 11 11 1 1 11 11 11 1 1 11 11 11 1DRAM Test –Pattern (X-scan)YX0001101100011011DRAM Test – March PatternDRAM Test – Failure ModeStuck-at Fault (SAF)Coupling Fault (CF)nShorts between data linesnCrosstalk between data linesTransistion Fault (TF)nCell can be set to 0 and not to 1 (or vice versa) when it’s operatedAddressing Fault (AF)nAddress line stucknOpen in address linenShorts between address linesnWrong accessnCell stucknDriver stucknData line stuckNeighbor Pattern Sensitive Fault (NPSF)nPattern sensitive interaction between cellsData Retention Fault (DRF)nData can not kept same status in cell as time passDRAM Test – March PatternMarch C- is the most effectiveDRAM Test – 1HTDefect ModeOPENLEAKIDDEFTTESTER RELATED○ ○○ ○○ ○○ ○WAFER ISSUE○ ○○ ○○ ○○ ○DIE CRACK○ ○○ ○○ ○DIE CHIP○ ○○ ○○ ○SURFACE DAMAGE○ ○○ ○NG Die○ ○NON DIE○ ○○ ○NON WIRE○ ○A~E OPEN○ ○WIRE SHORT WITH WIRE○ ○WIRE SHORT WITH DIE EDGE○ ○WIRE SWEEP○ ○NON BROKEN INNER LEAD○ ○○ ○OTHERS○ ○○ ○○ ○○ ○○: SUSPECTION FOR FAILAbove table comes from our experiences. It is not covered all of failure modes vs phenomena. So, it is only for your reference.DRAM Test – Functional TestOther Functional Test Check Core Function (80% of total test time)¨Data Retention, ODT, Burst Read/Write, …etc¨Detect Pattern Sensitive Fault (PSF)0 0 0 0 1 0 0 0 00 0 0 0 0 0 0 0 0DRAM Test – AC TestAC Parameter Test To verify IC can work as each timing parameter defined in datasheet¨ Rise and fall time¨ Setup and hold time¨ Delay test¨ OthersDRAM Test – Speed TestTest DRAM at different speed:1. DDR3-1600(11-11-11) Test2. DDR3-1333(9-9-9) Test3. DDR3-1066(7-7-7) TestTest for each timing (tRCD, tRRD…) ……DDR3-1600DDR3-1333Speed FailDRAM Test – Test Plan in ProgramO/SO/SLeakageLeakageIDDIDDEFTEFTFUNC FUNC TestTestSpeedSpeed1333Fail1600 1866DRAM insideDRAM inside。