reflow简介reflow+review+and+process+suggetion HAN L.ppt

STMicroelectronics REFLOW review and process suggestion Prepared by HAN Lei ST Confidential * 2 Outline REFLOW cleaning review REFLOW recipe configuration Inline low yield control ST Confidential * 3 Issue description: Verify reflow cleaning procedure, especially quartz window cleaning. The brief cleaning procedure as following chart: Maintenance modemanual controlpurge valve susceptor sweepingchamber cleaning (foam detergent /alcohol) Exit (Maintenance mode)stand by *The key step Cleaning is operated under “purge valve”state. After cleaning operator need to select “stand by” to make sure that susceptor load and unload normally. REFLOW cleaning review ST Confidential * 4 REFLOW cleaning review Heater: IR halogen lamp Lamp power: 6 kW/480V Lamp qty: 24 Temp zone: 6 The key parts of REFLOW is IR reactor as following images. 292 x 10mm Quartz window ST Confidential * 5 REFLOW cleaning review *The images above show the 6 temperature zones of Infrared halogen lamps. *Halogen element of lamp enable the lamp durable and hi-temp-useful. *The heat transfers through quartz window and functions in chamber. *Two problems are concern: (1)Need to double confirm cleaning effective. Clean Quartz window Reflow #5 Dirty Quartz window Reflow #6 ST Confidential * 6 (2)What detergent is preferred? Inline detergent is alkaline, but quartz is weak acid. *The quartz is weak acid substance. *Small traces of alkaline (finger prints!) will lead to unavoidable surface damage when heated over 900 . *Even at room temperature, the particular properties of quartz will be highly influenced by its purity and cleanliness, which impact heat transferring and lamp life. *so contact by skin and similar impurities (especially detergents = soaps) should immediately be cleaned off by pure alcohol (isopropanol) and a clean, lint free cloth REFLOW cleaning review Alkaline Substance pH: 1010.5 foam detergent ST Confidential * 7 REFLOW cleaning review Action suggestion: (1)Clean chamber especially quartz window more than two times by pure alcohol . And need other person to double check. (2)Collect data to confirm whether the detergent impact quartz quality at both high temperature and room temperature. ST Confidential * 8 REFLOW recipe configuration 250um solder400 pitch K90Z*EMI10LV10LV-125 K0K0*TAH14V2 250-LG-125 K0K0*TKU18V1 K0M0*4XWSOIA 250-NH-125 K9M0*EMI2H3G KBM0*EMI3T3B KBG0*EMIF7LF 300um solder500 pitch K9QE*EMIF10R10R-125 K9QB*EMI2TDEFC01-125 FZQA*EF04IC2 KBQC*EMI2T4GFC03-125 K0QA*DAL14V4 K9QD*TJATT3C K9QD*EMI6T1D K9QE*EMI10TNFC04-125 K9QB*EMI3T2N K9QC*EMI6T7B K0QA*EAG18V4FC05-125 ball count/ dice POA 400um pitch POA 500um pitch 46K0QA 710M0QB 1116N0QC 1720G0QD 21250ZQE 2630 N/A QF 30QH Issue description: how to study reflow recipe and brife recipe analysis *The following tables show some REFLOW recipes for 250um solder & 300um solder devieces. 250um solder correspond to 400um pitch and 300um correspond to 500um pitch. *Difference of product code correspond to the difference of ball count on one dice, whose detail are all read from MBD. *The recipe partly correspond to the gross ball count on one wafer. ST Confidential * 9 REFLOW recipe configuration ST Confidential * 10 Generally, REFLOW recipe mainly includes 4 tempeture variation zones. (1)Preheat, which consists of gradually ramping up the setting temperature. 13/s. (2)Tin Activation, which consists of bringing the solder ball to a temperature at which it is chemically activated, allowing SiF6 function sufficiently, uniforming the tempereture within wafer. 20 150 220 260 Preheat 20 150 Tin Activation 150220 Actual Reflow 220 260 Cooldown 260 room temp The area of peak is preferred to be small. REFLOW recipe configuration e.g: Recipe of EAG18V4 ST Confidential * 11 (3)Actual Reflow, which consists of ramping up the temperature to the point at which the solder melts, causing the solder to sufficiently wet. The peak reflow temperature should be significantly 2040 higher than the solder alloys melting point to ensure good wetting. The area of peak is preferred to be smallest. (4) Cooldown, which consists of ramping down the temperature at optimum speed (fast enough to form small grains that lead to higher fatigue resistance, but slow enough to prevent thermo-mechanical damage to the solder) until the solder becomes solid again. 80 is the final temperature. REFLOW recipe configuration ST Confidential * 12 98.8%Sn Vs. 1.2%Ag Assessed Ag - Sn phase diagram REFLOW recipe configuration Melting point ST Confidential * 13 Inline low yield control 250um DEVICEYIELDCOMMENT EMIF7LE88.20% ALIGN FAIL EMIF7LF96.90% DOUBLE TAH14V497.50% SMALL EMIF7LE98.10%MISSING EMIF7LE98.30%MISSINGSTAIN EMIF7LF98.30%MISSINGSMALL EMIF7LF98.30%MISSING EMIF7LE98.40%MISSINGSCRATCH EMI10LV98.40%MISSINGLARGE EMIF7LF98.40%MISSINGSTAIN EMIF7LE98.50% LARGE EMI3T2P98.50%MISSINGLARGE EMIF7LF98.50%MISSING EMIF7LF98.50%MISSING 250um DEVICEYIELDCOMMENT EMIF7LE98.70%MISSING EMIF7LF98.70%MISSING EMI2H2J98.70% STAIN EMIF7LF98.80%MISSING EMIF7LE98.90%MISSING EMIF7LE98.90%MISSING EMIF7LF98.90%MISSING EMIF7LE98.90%MISSING EMIF7LF98.90%MISSING EMI10LV98.90%MISSING EMI10LV98.90% SCRATCH EMI10LV98.90% SCRATCH EMIF7LF98.90%MISSING EMIF7LF98.90%MISSING Issue description: Bumping inline low yield (14 300um DEVICEYIELDCOMMENT EMI1H1F94.90% STAIN EMI10TN95.60%MISSING EMI10TN97.70% LARGE SCRATCH EMI10TN98.20%MISSING EMI10TN98.20% MISFORM EMI10TN98.50%MISSING LARGE MISFORM EMI10TN98.50%MISSINGMISFORM EMI10TN98.50% LARGE EMI10TN98.60%MISSINGLARGE EMI10TN98.60%MISSING 300um DEVICEYIELDCOMMENT EMI10TN98.60% EMI6T3B98.70% STAIN EMI10TN98.70%MISSINGLARGE EMI10TN98.70%MISSINGSCRATCH EMI10TN98.70% LARGE EMI6T3B98.80% STAIN EMI10TN98.80% MISPLACE EMI10TN98.80%MISSINGLARGE EMI2T4G98.80% SCRATCH DOUBLE Inline low yield control ST Confidential * 15 Inline low yield control Low yield reason maily: MISSING especially for 250um bumping device Root cause: nonstability of manual operation and REFLOW issue. Action suggestion: (1)If there is no obvious missing pattern within wafer. List the low yield impacted wafers common path, such as which PLASMA and REFLOW ran from, when solder finish PLASMA washing. 250um bumping device low yield reasons from 1st14, July 300um bumping device low yield reasons from 1st14, July Check yield of other wafer with same path 99.0%release Check REFLOW history for temperature & gas flow Check manual operation & mask Do one more wafer sample to test shear & diameter ST Confidential * 16 Inline low yield control slot 25 slot 24 slot 23 Action suggestion: (2)Yield testing sample modify. The first 3 wfsThe first 2 wfs + The last 2 wfs Modify to Modifying concern: *Match sample collecting rule of front end FAB inline defect auto scanning. *To make sure that solder/UBM layer is normal for wafer to wafer. *UBM is deposited by sputting & etch process. One lot of 25 wafers run through different Chambers in one EQP. Eath process chamber need to do clean for every clean cycle (processing some pieces of wafers). Any shift of gas flo