Deep Reactive Ion Etching. Joey Greenspun

Transcription

1 Deep Reactive Ion Etching Joey Greenspun

2 Wet Dry Isotropic Lee, Nature 2012 Anisotropic

3 DRIE Goal: Etch deep, arbitrary features into silicon BOSCH Mask (Black is Chrome) Wafer

4 DRIE Goal: Etch deep, arbitrary features into silicon BOSCH

5 DRIE Goal: Etch deep, arbitrary features into silicon BOSCH

6 DRIE Goal: Etch deep, arbitrary features into silicon BOSCH

7 DRIE Goal: Etch deep, arbitrary features into silicon

8 DRIE Goal: Etch deep, arbitrary features into silicon BOSCH

9 Goal: Etch deep, arbitrary features into silicon Silicon Plasma Etch (RIE) KOH with {110} wafers {110} {111} {111} Kendall, Ann. Rev. MatSci 1979 Pro: Arbitrary features Con: Limited aspect ration (10:1) Hard to etch deep (selectivity issues) Pro: High aspect ratio > 600:1 Con: Extremely limited features

10 Wet Dry Isotropic Lee, Nature 2012 Anisotropic

11 Deep Reactive Ion Etching Gas Inlet SF 6 for i = 1:N Isotropic_Etch() end Passivate() Coil RF Matching Unit Pump Port Platen RF

12 Deep Reactive Ion Etching Gas Inlet for i = 1:N end Isotropic_Etch() Passivate() SF 6 Coil RF Matching Unit Pump Port Platen RF

13 Deep Reactive Ion Etching for i = 1:N Gas Inlet end Isotropic_Etch() Passivate() SF 6 SF SF 6 SF 6 6 SF 6 SF SF 6 6 SF 6 SF 6 SF 6 SF 6 Coil RF Matching Unit Pump Port Platen RF

14 Deep Reactive Ion Etching for i = 1:N Gas Inlet end Isotropic_Etch() Passivate() SF 6 Coil RF Matching Unit Pump Port Platen RF

15 Deep Reactive Ion Etching for i = 1:N Gas Inlet end Isotropic_Etch() Passivate() SF 6 Coil RF Matching Unit Pump Port Platen RF

16 Deep Reactive Ion Etching for i = 1:N Gas Inlet end Isotropic_Etch() Passivate() SF 6 Coil RF Matching Unit Pump Port Platen RF

17 Deep Reactive Ion Etching for i = 1:N Gas Inlet end Isotropic_Etch() Passivate() SF 6 Coil RF Matching Unit Pump Port Platen RF

18 Deep Reactive Ion Etching for i = 1:N Gas Inlet end Isotropic_Etch() Passivate() SF 6 Coil RF Matching Unit Pump Port Platen RF

19 Deep Reactive Ion Etching for i = 1:N Gas Inlet end Isotropic_Etch() Passivate() SF 6 SF x SF x Coil RF Matching Unit Pump Port Platen RF

20 Deep Reactive Ion Etching for i = 1:N Gas Inlet end Isotropic_Etch() Passivate() SF 6 Coil RF Matching Unit Pump Port Platen RF

21 Deep Reactive Ion Etching for i = 1:N Gas Inlet end Isotropic_Etch() Passivate() SF 6 SF x SF x Coil RF Matching Unit Pump Port Platen RF

22 Deep Reactive Ion Etching for i = 1:N Gas Inlet end Isotropic_Etch() Passivate() SF 6 Coil RF Matching Unit Pump Port Platen RF

23 Deep Reactive Ion Etching for i = 1:N Gas Inlet end Isotropic_Etch() Passivate() SF 6 Coil RF Matching Unit Pump Port Platen RF

24 Deep Reactive Ion Etching for i = 1:N Gas Inlet end Isotropic_Etch() Passivate() SF 6 SF x SF x Coil RF Matching Unit Pump Port Platen RF

25 Deep Reactive Ion Etching for i = 1:N Gas Inlet end Isotropic_Etch() Passivate() SF 6 SF x SF x Coil RF Matching Unit Pump Port Platen RF

26 Deep Reactive Ion Etching for i = 1:N Gas Inlet end Isotropic_Etch() Passivate() SF 6 SF x SF x Coil RF Matching Unit Pump Port Platen RF

27 Deep Reactive Ion Etching for i = 1:N Gas Inlet end SF 6 Isotropic_Etch() Passivate() Coil RF Matching Unit Pump Port Platen RF

28 Deep Reactive Ion Etching for i = 1:N Gas Inlet end Isotropic_Etch() Passivate() F SF 6 Coil RF Matching Unit Pump Port Platen RF

29 Deep Reactive Ion Etching for i = 1:N Gas Inlet end Isotropic_Etch() Passivate() SiF 4 SF 6 Coil RF Matching Unit Pump Port Platen RF

30 Deep Reactive Ion Etching for i = 1:N Gas Inlet end Isotropic_Etch() Passivate() SF 6 Coil RF Matching Unit Pump Port Platen RF

31 Deep Reactive Ion Etching Gas Inlet for i = 1:N end Isotropic_Etch() Passivate() SF 6 C 4 F C 8 4 F 8 Coil RF Matching Unit Pump Port Platen RF

32 Deep Reactive Ion Etching Gas Inlet for i = 1:N end Isotropic_Etch() Passivate() SF 6 CF 2 * CF 2 * CF x CF 2 * CF x CF x Coil RF Matching Unit Pump Port Platen RF

33 Deep Reactive Ion Etching Gas Inlet for i = 1:N end Isotropic_Etch() Passivate() CF 2 * CF 2 * CF 2 * CF 2 * CF 2 * CF 2 * CF 2 * SF 6 CF 2 * CF 2 * CF x CF 2 * CF x CF x Coil RF Matching Unit Pump Port Platen RF

34 Deep Reactive Ion Etching Gas Inlet for i = 1:N end Isotropic_Etch() Passivate() CF 2 * CF 2 * CF 2 * CF 2 * CF 2 * CF 2 * CF 2 * SF 6 CF 2 * CF 2 * CF x CF 2 * CF x CF x Coil RF Matching Unit Pump Port Platen RF

35 Deep Reactive Ion Etching for i = 1:N Gas Inlet end SF 6 Isotropic_Etch() Passivate() Coil RF Matching Unit Pump Port Platen RF

36 Deep Reactive Ion Etching for i = 1:N Gas Inlet end SF 6 Isotropic_Etch() Passivate() Coil RF Matching Unit Pump Port Platen RF

37 Deep Reactive Ion Etching for i = 1:N Coil RF Gas Inlet end SF Matching Unit Isotropic_Etch() Passivate() Pump Port Platen RF

38 Deep Reactive Ion Etching for i = 1:N Gas Inlet end Isotropic_Etch() Passivate() CF 2 * CF 2 * CF 2 * CF 2 * CF 2 * CF 2 * CF 2 * CF 2 * CF 2 * CF 2 * CF2 * SF 6 CF 2 * CF 2 * CF x CF 2 * CF x CF x Coil RF Matching Unit Pump Port Platen RF

39 Deep Reactive Ion Etching for i = 1:N Gas Inlet end Isotropic_Etch() Passivate() CF 2 * CF 2 * CF 2 * CF 2 * CF 2 * CF 2 * CF 2 * CF 2 * CF 2 * CF 2 * CF2 * SF 6 CF 2 * CF 2 * CF x CF 2 * CF x CF x Coil RF Matching Unit Pump Port Platen RF

40 Deep Reactive Ion Etching for i = 1:N Coil RF Gas Inlet end SF Matching Unit Isotropic_Etch() Passivate() Pump Port Platen RF

41 Deep Reactive Ion Etching for i = 1:N Gas Inlet end Isotropic_Etch() Passivate() CF 2 * CF 2 * CF 2 * CF 2 * CF 2 * CF2 * CF 2 * CF 2 * CF 2 * CF 2 * CF 2 * Coil RF SF 6 CF 2 * CF 2 * CF x CF x CF 2 * CF x Matching Unit Pump Port Platen RF

42 DRIE Applications in CMOS Gambino, 2015 DRAM TSVs

43 DRIE and Silicon-on-Insulator Buried Oxide (BOX) Device Silicon Handle Silicon

44 DRIE and Silicon-on-Insulator

45 DRIE and Silicon-on-Insulator

46 DRIE Nonidealities - ARDE Aspect Ratio Dependent Etch Smaller holes/trenches etch more slowly Fix Tune recipe Limit feature size variation

47 DRIE Nonidealities Bullseye Bullseye Effect Edges of wafer etch more quickly than center

48 DRIE Nonidealities Bullseye Bullseye Effect Edges of wafer etch more quickly than center

49 DRIE Nonidealities Bullseye Bullseye Effect Edges of wafer etch more quickly than center

50 DRIE Nonidealities Bullseye Bullseye Effect Edges of wafer etch more quickly than center Fix Checkerboard

51 DRIE Nonidealities Microloading Microloading (RIE-lag) Isolated areas etch more quickly than dense arrays Fix Uniform layout Limit etched area

52 DRIE Nonidealities Uniformity Recap ARDE Bullseye Microloading (RIE-lag) Why do we care?

53 DRIE Nonidealities Footing Haobing, Liu, and Franck Chollet. "Layout controlled one-step dry etch and release of MEMS using deep RIE on SOI wafer." Journal of microelectromechanical systems 15.3 (2006):

54 DRIE Nonidealities Footing Giapis, Konstantinos P., and Gyeong S. Hwang. "Patterndependent charging and the role of electron tunneling." (1998) Haobing, Liu, and Franck Chollet. "Layout controlled one-step dry etch and release of MEMS using deep RIE on SOI wafer." Journal of microelectromechanical systems 15.3 (2006):

55 DRIE Nonidealities Footing Haobing, Liu, and Franck Chollet. "Layout controlled one-step dry etch and release of MEMS using deep RIE on SOI wafer." Journal of microelectromechanical systems 15.3 (2006):

56 DRIE Nonidealities Footing Haobing, Liu, and Franck Chollet. "Layout controlled one-step dry etch and release of MEMS using deep RIE on SOI wafer." Journal of microelectromechanical systems 15.3 (2006):

57 DRIE Nonidealities Footing

58 DRIE Nonidealities Footing

59 DRIE Nonidealities Footing

60 DRIE Nonidealities Footing

61 DRIE Nonidealities Footing

62 DRIE Nonidealities Footing 4 mm 6.5 mm

63 DRIE Nonidealities Footing 4 mm 6.5 mm

64 DRIE Nonidealities Footing Si BOX SUB 4 mm 6.5 mm Thermomechanical simulation Heat flux of 7 W/cm 2 Beams heat up by 0.1 C

65 DRIE Nonidealities Footing Si BOX SUB 4 mm 6.5 mm Thermomechanical simulation Springs fully footed Heat flux of 7 W/cm 2 Beams heat up to 517 C

66 DRIE Nonidealities Footing Footing/Notching Lateral silicon etching at oxide interface Fix Aluminum etch stop LF platen source LF platen duty cycle

67 DRIE Nonidealities Footing Noworolski, Solid-State Sensors and Actuators, 1995 Fix: Aluminum etch stop Kim, Journal of Micromechanics and Microengineering, 2011

68 DRIE Nonidealities Footing Gas Inlet SF MHz SF x Coil RF Matching Unit Fix: LF platen source LF platen duty cycle Pump Port Platen RF

69 DRIE Nonidealities Footing Gas Inlet SF MHz Coil RF Matching Unit Fix LF platen source LF platen duty cycle Pump Port Platen RF

70 DRIE Nonidealities Footing Gas Inlet SF khz Coil RF Matching Unit Fix LF platen source LF platen duty cycle Pump Port Platen RF

71 DRIE Nonidealities Footing Gas Inlet SF khz Coil RF Matching Unit Fix LF platen source LF platen duty cycle Pump Port Platen RF

72 DRIE Nonidealities Footing Gas Inlet SF 6 Coil RF Samukawa, Appl. Phys. Lett Fix LF platen source LF platen duty cycle Pump Port Matching Unit Platen RF

73 DRIE Nonidealities Grass Grass Thin pillars of silicon created at bottoms of trenches Fix Limit exposed area Recipe tune Docker, J. Micromechanics and Microengineering, 2004

74 DRIE Nonidealities Sidewall Angle Sidewall Angle Sidewalls are not always 90 Fix Recipe tune

75 DRIE Nonidealities Sidewall Angle Sidewall Angle Sidewalls are not always 90 Fix Recipe tune

76 DRIE Nonidealities Mask Undercut 2 µm Mask Undercut PR mask is naturally undercut by process 2.5 µm Fix Decrease etch time

77 Recipe Tuning

78 Recipe Tuning Design of Experiments Factors Response Wasilik, 2001

79 Joey Greenspun Daniel Contreras Craig Schindler The Pister Group Daniel Drew Brian Kilberg Hani Gomez