Presentation is loading. Please wait.

Presentation is loading. Please wait.

A Low Temperature Technology on the Base of Hydrogen Enhanced Thermal Donor Formation for Future High-Voltage Applications R. Job 1, A.G. Ulyashin 1, W.R.

Similar presentations


Presentation on theme: "A Low Temperature Technology on the Base of Hydrogen Enhanced Thermal Donor Formation for Future High-Voltage Applications R. Job 1, A.G. Ulyashin 1, W.R."— Presentation transcript:

1 A Low Temperature Technology on the Base of Hydrogen Enhanced Thermal Donor Formation for Future High-Voltage Applications R. Job 1, A.G. Ulyashin 1, W.R. Fahrner 1, 1 University of Hagen, Dept. of Electrical Engineering and Information Technology (LGBE), Germany F.J. Niedernostheide 2, H.J. Schulze 2, 2 Infineon AG, Munich, Germany E. Simoen 3, C.L. Claeys 3, 4, 3 IMEC, Leuven, Belgium 4 University of Leuven (KU), Dept. of Electrical Engineering, Belgium G. Tonelli 5 5 INFN, Pisa, Italy

2 Dr. Reinhart Job, University of Hagen, Germany Outline of the Talk Introduction Experimental (substrates, H-plasma treatments & annealing) Experimental Results (analysis by SRP measurements, I-V and C-V curves, DLTS, Raman spectroscopy, SEM, TEM ) Discussion (low temperature doping by thermal donors  low thermal budget technology for special devices, i.e. high-voltage devices, radiation detectors, etc.) Summary

3 Dr. Reinhart Job, University of Hagen, Germany Thermal Donors (TDs) 'Old thermal donors' (TDs), oxygen related double donors (TDDs) – formation at T  °C – T > 550 °C  TDs are dissolved – family of 'bistable' double donors TDD1, TDD2,..., TDD16,... (?) – classification by IR-absorption spectroscopy – 2 energy levels of the donor: 70 meV, 150 meV – formation rate R correlated with [O i ] and [C s ]: [O i ] high  R high, [C s ] high  R low Our investigations:  'Old thermal donors' (i.e. TDDs) Other types of TDs:NDs, NTDs, STDs

4 Dr. Reinhart Job, University of Hagen, Germany Thermal Donors 'New donors' (NDs) –formation at T  °C –R correlated with [O i ] and [C s ]: [O i ] high  R high, [C s ] high  R high –energy level of the donor: 17 meV 'New thermal donors' (NTDs) –formation at T  °C –NTDs appear only after very long annealing times (> 10 5 min) –NTDs  double donors –large agglomerates of oxygen (?) 'Shallow thermal donors' (STDs) –formation at T  °C (low concentrations) –family of 7 single donors

5 Dr. Reinhart Job, University of Hagen, Germany Low Thermal Budget Doping by Thermal Donors Hydrogen enhances thermal donor (TD) formation in Cz silicon Thermal donors: 'old' TDs, i.e. TDDs (oxygen related double donors) Counter doping of initial p-type Cz Si by hydrogen enhanced TD formation  formation of deep p-n junctions Developed process routes: - "1-step-process" - "2-step-process"

6 Dr. Reinhart Job, University of Hagen, Germany Experimental Substrates: –p-type Cz Silicon wafers (  = 3 inches, d  µm, (100)-oriented) Impurities: [O i ]   cm -3 (specified, IR-Absorption) [C s ] < 5  cm -3 (specified) Doping:  =  cm,  =  cm,  =  cm [B]  6  cm  cm -3

7 Dr. Reinhart Job, University of Hagen, Germany Experimental Applied measurements: “Spreading-Resistance-Probe”- (SRP-) measurements - resistance profiles in dependence on the depth - estimation of the location of p-n junctions Thermoelectrical Microprobe Method (‘Seebeck-Effect’) - determination of the type of doping (n-type / p-type) C(V) measurements - characterization of p-n junctions due to TD formation Infrared- (IR-) absorption measurements - characterization of TD types (”TDD i - family") I(V) measurements - characterization of diodes (”TD-Diodes”)

8 Dr. Reinhart Job, University of Hagen, Germany "1-Step-Process" for TD Formation Hydrogen enhanced TD formation in Cz Si only by H-plasma treatment "1-step-process": TDD formation during H-plasma treatment (T plasma = °C, t plasma  30 min) Cz Si wafers: [B] = 1  cm -3, [O i ] =  cm -3 Example: DC plasma treatment (RIE setup, 500 V plate voltage, 440 µA/cm 2 )  formation of TDDs, [TDD]  1  cm -3  formation of deep p-n junctions (counter doping)

9 Dr. Reinhart Job, University of Hagen, Germany Formation of p-n Junctions ("1-Step-Process") SRP measurements:  p-n junction location Substrate: 12  cm Cz Si, [B] = 1  cm -3 (p-type) H-Plasma: 30 min at 400 °C (1-step-process)

10 Dr. Reinhart Job, University of Hagen, Germany Formation of p-n Junctions ("1-Step-Process") Free carrier concen- tration N c in depen- dence on the depth Substrate: 12  cm Cz Si, [B] = 1  cm -3 (p-type) H-Plasma: 30 min at 400 °C (1-step-process)

11 Dr. Reinhart Job, University of Hagen, Germany Formation of p-n Junctions ("1-Step-Process") Electron concentra- tion N e(TD) due to TDDs in dependence on the depth Substrate: 12  cm Cz Si, [B] = 1  cm -3 (p-type) H-Plasma: 30 min at 400 °C (1-step-process)

12 Dr. Reinhart Job, University of Hagen, Germany Formation of p-n Junctions ("1-Step-Process") C(V) measurements: C -3  V bias  linear graded junction Substrate: 12  cm Cz Si, [B] = 1  cm -3 (p-type) H-Plasma: 30 min at 400 °C (1-step-process)

13 Dr. Reinhart Job, University of Hagen, Germany Formation of p-n Junctions ("1-Step-Process") SRP measurements:  p-n junction location Substrate: 12  cm Cz Si, [B] = 1  cm -3 (p-type) H-Plasma: 45 min at 400 °C (1-step-process)

14 Dr. Reinhart Job, University of Hagen, Germany Formation of p-n Junctions ("1-Step-Process") Free carrier concen- tration N c in depen- dence on the depth Substrate: 12  cm Cz Si, [B] = 1  cm -3 (p-type) H-Plasma: 45 min at 400 °C (1-step-process)

15 Dr. Reinhart Job, University of Hagen, Germany Formation of p-n Junctions ("1-Step-Process") SRP measurements: p-n junction depth in dependence on the initial p-type doping Substrate: 1, 12  cm Cz Si, [B]  10 15, cm -3 (p-type) H-Plasma: 120 min at 400 °C (1-step-process)

16 Dr. Reinhart Job, University of Hagen, Germany Formation of p-n Junctions ("1-Step-Process") SRP measurements: p-n junction depth in dependence on the amount of incorpo- rated hydrogen Substrate: 12  cm Cz Si, [B] = 1  cm -3 (p-type) H-Plasma: 120 min at 400 °C (1-step-process)

17 Dr. Reinhart Job, University of Hagen, Germany Formation of p-n Junctions ("1-Step-Process") C(V) measurements: N e(TD) in dependen- ce on the hydrogen dose Substrate: 12  cm Cz Si, [B] = 1  cm -3 (p-type) H-Plasma: at 400 °C (1-step-process)

18 Dr. Reinhart Job, University of Hagen, Germany Formation of p-n Junctions ("1-Step-Process") SRP measurements: p-n junction depth in dependence on the plasma treatment time Substrate: 12  cm Cz Si, [B] = 1  cm -3 (p-type) H-Plasma: min at 400 °C (1-step-process)

19 Dr. Reinhart Job, University of Hagen, Germany Kinetic Analysis of the "1-Step-Process" D H : diffusion constant of atomic hydrogen K 1 : rate of H 2 formation K 2 : dissociation constant of H 2 molecules Time dependences of H and H 2 concentrations:

20 Dr. Reinhart Job, University of Hagen, Germany Kinetic Analysis of the "1-Step-Process" K 1 : rate of H 2 formation K 2 : dissociation constant of H 2 molecules D H : "Van Wieringen-Warmholtz" relation  diffusion constant R 0 : capture radius (R 0 = 5 Å * ) ) : vibration frequency of the dissociation of H 2 E b : binding energy (E b = 1.6 eV) * ) J.T. Borenstein et al., J. Appl. Phys. 73, 2751 (1993)

21 Dr. Reinhart Job, University of Hagen, Germany Kinetic Analysis of the "1-Step-Process" N TD : concentration of thermal double donors ("TDD")  compensation (p-n junction): 2  [N TD ] = [B] K 3 : free parameter (deduced by fitting of experimental data) K 3 = 3.8  s -2 Boundary condition: x = 0, t  0: [H 0 ], with [H 0 ] = cm -3 (constant hydrogen concentration at the wafer surface) Time dependence of [TD] :

22 Dr. Reinhart Job, University of Hagen, Germany Formation of p-n Junctions ("1-Step-Process") Simulated curves: [TDD], [H], [H 2 ] in dependence on the depth Assumption: T = 400 °C t = 30 min (1-step-process) [TDD]-profile: K 3 = 3.8  s -2 (Fit to exp. Data)

23 Dr. Reinhart Job, University of Hagen, Germany Formation of p-n Junctions ("1-Step-Process") Comparison of simulated [TD] profiles & experimental data Assumption: T = 400 °C t = 30, 45, 120 min (1-step-process) Fit to exp. Data:  K 3 = 3.8  s -2

24 Dr. Reinhart Job, University of Hagen, Germany Kinetic Analysis of the "1-Step-Process" Summary / Conclusions: "1-Step-Process":  various processes occur –T > 200 °C  no acceptor passivation –incorporation of hydrogen from the plasma ambient –formation and decay of H 2 complexes –diffusion of H via interstitial lattice sites –H lowers the barrier for the diffusion of O i –probability is enhanced that O i forms a TD complex  hydrogen supports the TD formation –loss of O i due to the incorporation of O i into TD-complexes Question:Charge state of hydrogen (H 0, H +, H - ) ?

25 Dr. Reinhart Job, University of Hagen, Germany "2-Step-Process" for TD Formation Hydrogen enhanced TD formation in Cz Si by H-plasma treatment and subsequent annealing "2-step-process": TDD formation during post-hydrogenation annealing - H-plasma exposure: T plasma  250 °C, t plasma = 60 min - annealing: T anneal  450 °C, t anneal  15 min Cz Si wafers: [B] = 1  cm -3, [O i ] =  cm -3 Example: PECVD plasma treatment (110 Mhz, 50 W, 440 µA/cm 2 )  formation TDDs / p-n junctions, [TDD]  1  cm -3

26 Dr. Reinhart Job, University of Hagen, Germany Formation of p-n Junctions ("2-Step-Process") SRP measurements: p-n junction depth in dependence on the post-hydrogenation annealing time Substrate:  cm Cz Si, [B]  7  cm -3 (p-type) H-Plasma: 60 min at 250 °C Annealing: at 450 °C/air

27 Dr. Reinhart Job, University of Hagen, Germany Formation of p-n Junctions ("2-Step-Process") SRP measurements: p-n junction depth in dependence on the post-hydrogenation annealing time Substrate:  cm Cz Si, [B]  2  cm -3 (p-type) H-Plasma: 60 min at 250 °C Annealing: at 450 °C/air

28 Dr. Reinhart Job, University of Hagen, Germany Kinetic Analysis of the "2-Step-Process" "2-step-process":60 min RF H-plasma at  250 °C + annealing at 450 °C/air Hydrogen supports the formation of TDs, i.e. TDDs Supposition:TD formation / depth of p-n junctions  penetration of n-type regions into the wafer bulk are driven by H diffusion "Fick's Diffusion Law": [H]: hydrogen concentration, D: diffusion constant, t: time,

29 Dr. Reinhart Job, University of Hagen, Germany Kinetic Analysis of the "2-Step-Process" "Fick's Law": if D = const.  (D: diffusion constant, d: depth, t: time, [H 0 ]: surface concentration) mean diffusion length: assume: p-n junction depth d pn proportional to diffusion length L:  d pn  L, i.e. d pn  t 1/2

30 Dr. Reinhart Job, University of Hagen, Germany Formation of p-n Junctions ("2-Step-Process") p-n junction depth:  description by the "Fick's diffusion law" (D: diffusion constant) linear slope  D = 2.9  cm 2 s -1 (  cm Cz Si) D = 7.9  cm 2 s -1 (  cm Cz Si)

31 Dr. Reinhart Job, University of Hagen, Germany Kinetic Analysis of the "2-Step-Process" Relation of Van Wieringen and Warmholtz (VWW): (E a = 0.48 eV) VWW equation holds for atomic hydrogen ! extrapolation to 450 °C: D VWW = 4.36  cm 2 /s experiment: D  7.9  cm 2 s -1 (1  cm Cz Si) D  2.9  cm 2 s -1 (5  cm Cz Si)

32 Dr. Reinhart Job, University of Hagen, Germany Formation of p-n Junctions ("2-Step-Process") RF H-plasma exposure at room temperature:  p-n junction formation only after long time annealing at 450 °C (t > 8 hours) Substrate:  cm Cz Si, [B]  1.1  cm -3 (p-type) H-Plasma: 60 min at RT Annealing: at 450 °C/air

33 Dr. Reinhart Job, University of Hagen, Germany Kinetic Analysis of the "2-Step-Process" Summary / Conclusions (1): Hydrogen is amphoteric (standard model: H + in p-type Si, H 0 and H - in n-type Si) Estimated diffusion constants  neutral atomic hydrogen H 0 plays the major role for the TD formation H 0 is responsible for the enhancement of the TD formation in p-type and n-type Cz Si D(H 0 ) is several orders of magnitude larger than the diffusion constant D(H + ) of positively charged H + ions  D(H 0 )/D(H + )  10 5 * ) * ) D. Matthiot, Phys. Rev. B 40, 5867 (1989)

34 Dr. Reinhart Job, University of Hagen, Germany Kinetic Analysis of the "2-Step-Process" Summary / Conclusions (2): "2-Step-Process":  various processes occur –T > 200 °C  no acceptor passivation occurs –T  250 °C  immobile hydrogen complexes are created –T  °C  immobile hydrogen complexes are dissolved  high concentration of mobile H 0 –diffusion of H 0 via interstitial lattice sites –H 0 lowers the barrier for the migration of O i –probability is enhanced that O i forms a TD complex  hydrogen supports the TD formation

35 Dr. Reinhart Job, University of Hagen, Germany Kinetic Analysis of the "2-Step-Process" Summary / Conclusions (3): Dominant reaction at T  250 °C (H-plasma treatment): H + + H 0  H 2 + h + * ) (H +, H 0 : hydrogen in positive, neutral state, h + : hole, compensated by crystal field) * ) S.M. Myers et al., Rev. Mod. Phys. 64, 559 (1992)  immobile H 2 species: "zero spin clusters (ZSC)" Dominant reaction at T  450 °C (annealing):  decay of ZSCs  large concentration of H 0 "2-step-process"  indirect way for H 0 incorporation "1-step-process"  direct way for H 0 incorporation

36 Dr. Reinhart Job, University of Hagen, Germany Formation of Extremely Deep p-n Junctions SRP measurements: ultra-deep p-n junc- tion in highly oxidi- zed Cz Si [O i ] = 1.15  cm -3 Substrate: 12  cm Cz Si, [B]  1  cm -3 (p-type) H-Plasma: 60 min at 450 °C µ-wave H-plasma (1-step-process)

37 Dr. Reinhart Job, University of Hagen, Germany Formation of Extremely Deep Graded Doping SRP measurements: ultra-deep graded doping in highly oxidized Cz Si [O i ] = 1.2  cm -3 Substrate: 5  cm Cz Si, [P]  1  cm -3 (n-type) H-Plasma: 60 min at 450 °C µ-wave H-plasma (1-step-process)

38 Dr. Reinhart Job, University of Hagen, Germany Hydrogen Enhanced Thermal Donor Formation IR-absorption measurements: verification of TDDs (neutral species up to the 5 th generation) Substrate: 12  cm Cz Si, [B]  1  cm -3 (p-type) [O i ] = 1.15  cm -3 H-Plasma: 60 min at 450 °C µ-wave H-plasma (1-step-process)

39 Dr. Reinhart Job, University of Hagen, Germany Hydrogen Enhanced Thermal Donor Formation IR-absorption measurements: verification of TDD + s (singly ionized spe- cies up to the 5 th generation) Substrate: 12  cm Cz Si, [B]  1  cm -3 (p-type) [O i ] = 1.15  cm -3 H-Plasma: 60 min at 450 °C µ-wave H-plasma (1-step-process)

40 Dr. Reinhart Job, University of Hagen, Germany Hydrogen Enhanced Thermal Donor Formation IR-absorption measurements: verification of TDDs (neutral species up to the 5 th generation) Substrate: 5  cm Cz Si, [P]  1  cm -3 (n-type) [O i ] = 1.2  cm -3 H-Plasma: 8 h at 270 °C 1 h at 450 °C µ-wave H-plasma (1-step-process)

41 Dr. Reinhart Job, University of Hagen, Germany IR-absorption measurements: verification of TDDs (neutral species up to the 5 th generation) Substrate: 5  cm Cz Si, [P]  1  cm -3 (n-type) [O i ] = 1.2  cm -3 H-Plasma: 8 h at 270 °C Annealing: 1 h / 4 h at 450 °C/air (2-step-process) Hydrogen Enhanced Thermal Donor Formation

42 Dr. Reinhart Job, University of Hagen, Germany Formation of Diodes by Thermal Donor Doping Substrates: –p-type Cz Si (  cm,  cm,  cm) [B]  6  cm  cm -3 [O i ] = 7  8  cm -3, [C s ] < 5  cm -3 TD formation (plasma treatment / annealing): –H-plasma:µ-wave 2.45 GHz, t pl = 30 min, T pl = 450 °C annealing: no annealing (1-step-process: TD-diode No. 1) –H-plasma:110 MHz, 50 W, t pl = 60 min, T pl = 250 °C annealing: t ann = 20 or 30 min, T ann = 450 °C/air (2-step-process: TD-diodes No. 2, 3) also alternative plasma hydrogenation possible: –H-plasma:DC, 500 V, T pl = °C, t pl  30 min (1-step-process)

43 Dr. Reinhart Job, University of Hagen, Germany TD-diode (No. 1): contact area: 1 mm 2 - SRP profile p-n junction depth: d = 40 µm - I(V) curves at T = RT Substrate:  cm Cz Si H-Plasma: 30 min at 450 °C µ-wave H-plasma (1-step-process) Formation of Diodes by Thermal Donor Doping

44 Dr. Reinhart Job, University of Hagen, Germany TD-diode (No. 2): contact area: 1 cm 2 - SRP profile p-n junction depth: d  170 µm - I(V) curves at T = RT Substrate:  cm Cz Si H-Plasma: 60 min at 250 °C Annealing: 30 min 450 °C/air (2-step-process) Formation of Diodes by Thermal Donor Doping

45 Dr. Reinhart Job, University of Hagen, Germany TD-diode (No. 1): contact area: 1 mm 2 (1-step-process) TD-diode (No. 2): contact area: 1 cm 2 (2-step-process)  Comparison I(V) curves at T = RT:  Data normalized to contact size ! Formation of Diodes by Thermal Donor Doping

46 Dr. Reinhart Job, University of Hagen, Germany TD-diode (No. 1): contact area: 1 mm 2 - I(V) curves at T = RT  150 °C Substrate:  cm Cz Si H-Plasma: 30 min at 450 °C µ-wave H-plasma (1-step-process) Analysis of TD-Diodes

47 Dr. Reinhart Job, University of Hagen, Germany TD-diode (No. 1): contact area: 1 mm 2 - C(V) measurements linear slope   C  V -3  linearly graded p-n junction (if C  V -2  abrupt junction) Substrate:  cm Cz Si H-Plasma: 30 min at 450 °C µ-wave H-plasma (1-step-process) Analysis of TD-Diodes

48 Dr. Reinhart Job, University of Hagen, Germany TD-diode (No. 3): contact area: 1 mm 2 - p-n junction depth: d  100 µm - I(V) curves, mapping at T = RT Substrate:  cm Cz Si H-Plasma: 60 min at 250 °C Annealing: 20 min 450 °C/air (2-step-process) Analysis of TD-Diodes / Wafer Mapping

49 Dr. Reinhart Job, University of Hagen, Germany appropriate plasma hydrogenation  enhanced TD formation counter doping of p-type Cz Si can occurs due to TDs  formation of deep p-n junctions (low thermal budget < 500 °C, process time  1 hour) graded doping in n-type Cz Si p-n junction formation due to TDs  rapid and low thermal budget technology for high voltage or power device applications Summary


Download ppt "A Low Temperature Technology on the Base of Hydrogen Enhanced Thermal Donor Formation for Future High-Voltage Applications R. Job 1, A.G. Ulyashin 1, W.R."

Similar presentations


Ads by Google