激光隐形切割

1、Stealth Dicing Process Introduction,What is Stealth Dicing?,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 laser,Focusing le

2、ns,Workpiece,SD layer,Stealth Dicing process flow,Stealth Dicing,Die Breaking & Tape Expanding,Form an SD layer,DFL7340,STW210,Completely dry process Suitable for devices that are vulnerable to contamination and particles (e.g. MEMS). No mechanical load applied to the wafer Suitable for devices that

3、 are vulnerable to physical loads (e.g. Ultra-thin wafer / MEMS ). No debris during dicing Generates no particles by processing below the surface of the wafer Needs no spinner cleaning after processing,Advantages of SD process - 1,After expanding,Kerf width: 0 um Chipping : 0 um,(A few micrometers o

4、f meander might occur during the separation process.),Before expanding,Extremely thin kerf Greatly contributes to street reduction because the kerf width can be made extremely thin,Advantages of SD process - 2,- The number of passes 1 - Feed speed 300 mm/s - Die size 55 mm,Si: Thickness 100 m,55m,SD

5、 layer,- The number of passes 7 * - Feed speed 300 mm/s - Die size 55 mm *One extra pass per street is needed to map (measure + record) the workpiece surface,Si: Thickness 300 m,40m,SD layer,Dicing without front or back side chipping By controlling the position of the SD layer, the damage to both su

6、rfaces can be reduced,Advantages of SD process - 3,T : Wafer thickness W : Street width or clear width,Limitation of street width W 0.4xT,W,Limitations of the SD process Metal in the street A laser can not penetrate the metal Films (e.g. SiO2, SiN, polyimide) They are permeable materials, but can be

7、processed Street width / thickness ratio Clear width is determined by the thickness of the wafer Limitation of the expand process Thick metal It may be difficult to separate all of the metal Die size of 1mm square or less A separation process will be needed for small die,Limitations of SD process,SD

8、 solution of ShinAu,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 & Transferring,Form an SD layer,DF

9、L7340,STW210,Pattern side,Silicon side,Tape mount from wafer back side,Tape mount,Silicon side,Pattern 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 im