Microwave Device Term Project

Microwave Device Term Project Metamorphic Hemt device 성능 최적화 & 연구방향 2004/ 6/ 22 Lee Kang Min School of Electrical Engineering and Computer Science Seoul National University, Korea Millimeterwave Device and Circuit Lab.

Content 1. Overview of Metamorphic-HEMT. - Introduction of Metamorphic-HEMT. 2. Key issue for Good performance Metamorphic-HEMT. -Process part. -Material Growth part. 3.Overcome method each key issue. -Process part. -Material Growth part. 4.Conclusion. -future work.

Metamorphic low cost Good performance 1. Overview of Metamorphic-HEMT 1.HEMT 소자의 종류( 구조별 분류) 1) Lattice-matched HEMT -격자 상수가 비슷한 물질들의 이용한 HEMT 구조 -Conventional AlGaAs/GaAs 구조 -ex) InP based HEMT: Al0.48In0.52As/In0.53Ga0.47As/InP 구조 2) Pseudomorphic HEMT -격자 상수가 다른 물질을 채널에 얇게 기른 HEMT 구조 -ex)AlGaAs/GaAs HEMT의 channel에 InGaAs 물질을 사용 3) Metamorphic HEMT - GaAs substrate + InP HEMT Epitaxy를 이용한 HEMT 구조 - Buffer 사용 GaAs InP

1. Overview of Metamorphic-HEMT 2. Introduction of Metamorphic-HEMT ▶ Advantage - low cost & large scale (using GaAs substrate) - Multi-used. ( flexible Epitaxy design ) Low noise amp , power amp , switch …. - Stable High frequency & low noise performance ▶ Disadvantage - Buffer issue-lattices mismatching  defect (Metamorphic buffer)

SiN x Gate C C g,ext g,ext Lg Side Recess Dg Channel SiN x EHP Passivation Generation 2. Key issue for Good performance Metamorphic-HEMT 1.Process part • General process issue • Lg  Keeping (Lg/Dg)  • Suppression of Cg,ext. • Surface Passivation. • Gate, Ohmic metal tech. • Side Recess tech ( Breakdown voltage)

2. Key issue for Good performance Metamorphic-HEMT 2.Material Growth part (Epitaxy design) Gate Source Drain • General Material issue • Use of suitable InGaAs Channel • Use of suitable M-buffer layer (Epi growth) • & Doping profile InAlAs Barrier InGaAs cap InGaAs Channel InAlAs buffer Si delta doping Metamorphic-buffer GaAs Substrate

3.Overcome method each key issue 1.Process part 1) Lg  Keeping (Lg/Dg)  - Cappy group 2002. EL ( Lg=60nm ) DC: Gm= 850mS/mm , Ids~600mA/mm RF: Ft=260GHz , Fmax=490GHz * General Lg=0.1um Ft>200GHz (In0.53Ga0.48As channel using )

3.Overcome method each key issue 1.Process part 2) Suppression of Cgext – MDCL. 2004 GaAs Mantech.(Lg=0.15um) DC: Gm= 500mS/mm , Ids~450mA/mm RF: Ft=147GHz (15% Improve) * In0.40Ga0.6As channel using

3.Overcome method each key issue 1.Process part 3) Surface passivation – MDCL. Experiment (Lg=0.1um) DC: Gm= 590mS/mm(~20% improve) , Ids=600mA/mm * In0.35Ga0.65As channel using

3.Overcome method each key issue 1.Process part 4) Gate, Ohmic metal tech – Jantz group, GaAs reilability symposium 2001 (lg=0.12um) Ti Oxidation , Pt buried gate – better reilabilty & device performance * In0.3Ga0.7As channel using

3.Overcome method each key issue 1.Process part 4) Gate, Ohmic metal tech – MDCL experiment , * In0.35Ga0.65As channel using : Rc= 0.13 General using : Rc= 0.15 (cappy group) Rc≥0.15 *) Reliability of metamorphic HEMTs on GaAs substrates,Raytheon GaAs reilability symposium 2001 Pd ohmic

3.Overcome method each key issue 1.Process part 5) Side Recess tech- K.C Hwang group , IEEE MGWL1998 (Lg=0.1um)  Double Recess ,Double Doped Gm : 1050 mS/mm Current density : 750mA/mm BVgd: 8.3V Power sensity: 509mW/mm ( InP-645mW/mm) • 최적의 전력 성능 – 높은 출력 current, 높은 breakdown 전압 • Epi- Drain 부근의 InGaAs channel 에서 최대 전계 감소시키는 구조 • Double-doped process 구조 - drain 전류 breakdown 전압 최적화 * In0.65Ga0.35As channel using

3.Overcome method each key issue 2.Material Growth part (Epitaxy design) 1) Use of suitable InGaAs Channel – Oki elecrtonic JJAP Vol42 ,2003 (Lg = 0.1um)

3.Overcome method each key issue 2.Material Growth part (Epitaxy design) 1) Use of suitable InGaAs Channel – Weimen group EDL 1996 (0.13um) •  Composit channel (for kink free) • In0.52Al0.48As : transport 특성이 우수함. • In0.32Ga0.68As : impact ionization 특성이 낮아서 좋음. • 두 물질을 섞어서 사용하여 DC 특성 및 • impact ionization 특성이 우수한 mHEMT 소자 구현 Output conductance : 20 mS/mm Maximum drain current : 750 mA/mm Ft= 160GHz ,Fmax= 350GHz

3.Overcome method each key issue 2.Material Growth part (Epitaxy design) 2) Use of suitable M-buffer layer (Epi growth) –G.Borghs group, 1999 GaAs Mantech 1> ternary buffer (InAlAs) – General grading 2> quaternary buffer (AlGaAsSb)- Top of buffer ( lattice-matching InAlAs ) - low defect density quaternary buffer (AlGaAsSb) • Gm=800ms/mm, Ids~500mA Ft=87GHz Fmax=140GHz ternary buffer (InAlAs) • Gm=860ms/mm, Ids~450mA Ft=75GHz Fmax=115GHz

4.Conclusion 1.경제적인 소자 2.목적에 따른 소자 연구가능& application 다양 (high speed MHEMT, power MHEMT, ..)  Power HEMT 에 집중하는 것이 효과적. 3. Process-고려 해야 할 변수가 많다. 기준에 따른 최적화 (trade off) (Idss & BVgd , ..) 4. Epitaxy- 최적화를 위한 Epi design (buffer, channel ,Ns..)

Referance 1. 0.13 μm gate-length In0.52Al0.48As-In0.53Ga0.47 As metamorphic HEMTs on GaAs substrate- Dumka, D.C ,Device Research Conference, 2000. Conference Digest 2. 0.1um gate metamorphic HEMT on GaAs and its application to SCFL- Tomoyuki . JJAP 2003 3. Reliability of metamorphic HEMTs on GaAs substrates-Marsh, P.F , GaAs Reliability Workshop, 2001 4. Status of metamorphic InxAl1-xAs/Inx Ga1-xAs HEMTs- cappy A , Gallium Arsenide Integrated Circuit (GaAs IC) Symposium, 1999 5. Metamorphic InAlAs/InGaAs HEMTs on GaAs substrates with a novel composite channels designChertouk, M. Electron Device Letters 1996 6. Fmax of 490 GHz metamorphic In0.52Al0.48 As/In0.53Ga0.47As HEMTs on GaAs substrate- Cappy A . Electronics Letters 2002 7. Properties of metamorphic materials and device structures on GaAs substrates- Hsieh, K.C Molecular Beam Epitaxy International Conference 2002 8. Effect of gate metal on reliability of metamorphic HEMTs- Jantz, W GaAs Reliability Workshop, 2001 9. Metamorphic InAlAs/InGaAs HEMT on GaAs substrate with a novel composite channel design Weimann , Electronics Device Letters 1996 10. 0.15µm In0.4GaAs/In0.4AlAs Metamorphic HEMT’s (M-HEMT’s) Using A Novel Triple Shaped Gate Structure Assisted By PMGI Resist- Kim . GaAs Mantach 2004 …..

Microwave Device Term Project