激光隐形切割

Stealth Dicing Process Introduction What is Stealth Dicing?l Stealth dicing （ SD） An SD layer is formed below the surface of a workpiece by focusing a laser beam. Die separate by expanding the dicing tape. The SD process is a dry process and applies no force to the wafer. Short pulse laserFocusing lensWorkpiece SD layerStealth Dicing process flowStealth Dicing Die Breaking & Tape ExpandingForm an SD layer DFL7340 STW210 Die separationDicing tapeSiDicing tapeSi l Completely dry process Suitable for devices that are vulnerable to contamination and particles (e.g. MEMS).l No mechanical load applied to the wafer Suitable for devices that are vulnerable to physical loads (e.g. Ultra-thin wafer / MEMS ).l No debris during dicing Generates no particles by processing below the surface of the wafer Needs no spinner cleaning after processingWafer with narrow streets MEMSVulnerable to the waterSilicon devicesThin wafer with DAF SEM photograph Advantages of SD process - 1 After expanding Kerf width : 0 um Chipping : 0 um (A few micrometers of meander might occur during the separation process.) 200mm Before expanding 20mm l Extremely thin kerf Greatly contributes to street reduction because the kerf width can be made extremely thinAdvantages of SD process - 2 - The number of passes 1- Feed speed 300 mm/s- Die size 5 5 mmSi: Thickness 100 m50mm 55mSD layer - The number of passes 7 *- Feed speed 300 mm/s- Die size 5 5 mm *One extra pass per street is needed to map (measure + record) the workpiece surface 100mmSi: Thickness 300 m 40mSD layer l Dicing without front or back side chipping By controlling the position of the SD layer, the damage to both surfaces can be reduced Advantages of SD process - 3 T : Wafer thicknessW : Street width or clear width TSi Incident point Limitation of street width W 0.4xTWl Limitations of the SD process Metal in the streetl A laser can not penetrate the metal Films (e.g. SiO2, SiN, polyimide) l They are permeable materials, but can beprocessed Street width / thickness ratiol Clear width is determined by the thickness of the waferl Limitation of the expand process Thick metal l It may be difficult to separate all of the metal Die size of 1mm square or lessl A separation process will be needed for small die Limitations of SD process SD solution of ShinAul ShinAu will provide the special SD solution, which is to be processed from backside of workpiece. If so, the SD process wont be limited by the street width & metal in the street. ShinAu SD process flow Stealth Dicing Die Breaking, Tape expanding & TransferringForm an SD layerDFL7340 STW210Die separationDicing tapeSiPattern sideSilicon sideTape mount from wafer back sideTape mount Silicon sidePattern side Quality Control- Particles Required no particle on the pad-Kerf linearity Kerf offset distance less than 5um- No double die occurred during wafer breaking Concern & Discussion- Need bumping layout to check if any impact to SD process - Dummy wafer/ Engineering qual process required Capacity Capacity(Pcs/month)Laser-Saw 2,000