Atomic Layer Deposition in Semiconductor Manufacturing

Home , Atomic layer deposition

Juan Pablo Trelles

Design and Technology Solutions, Intel Corporation [email protected]

Washington State University, Vancouver, WA November 7, 2011

1 Outline

1. Overview of Semiconductor Manufacturing – Semiconductor industry and work @ Intel

2. Introduction to Atomic Layer Deposition – Chemistry, process

3. Industrial ALD Processes – How to make ALD feasible in industry – Role of Computational Modeling & Simulation

2 1. Overview of Semiconductor Manufacturing

3 About Intel

• Semiconductor Manufacturing  Silicon, Software, Solutions – Deliver the “Computing Continuum” • +90 000 employees worldwide

D1C D1D (latest)

• R & D facilities in Hillsboro, OR • 2 Fabs in OR + 1 new (D1X) in 2012

> 2 Billion $ D1X (new)

http://download.intel.com/newsroom/kits/22nm/pdfs/Global-Intel-Manufacturing_FactSheet.pdf 4 Integrated Circuits Integrated circuit ~ electric - logical unit • Circuit design: logic equations  transistors • Layout: circuit schematics  layers to be fabricated

C = A & B

logic circuit layout

• Chip ~ 3.5 Billion transistors (contrast: world population 7.0 Billion)

controller core Core i7 (4 cores) shared L3 cache

http://www.intel.com/pressroom/archive/releases/2008/20081117comp_sm.htm 5 Semiconductor Manufacturing

apply exposure sand melted Si monocrystal ingot slicing wafer exposure photoresist ingot (transis. level)

single die slicing & wash-off selection 3 main types of processes: photoresist – Deposition of material (CVD, PVD, ALD, EP) – Removal of material (wet etch, dry etch, CMP) – Modification of material (litho, implant, annealing) sort test etching

ready apply high-k ion remove polishing electroplating metal layers transistor dielectric implantation photoresist

http://www.intel.com/pressroom/kits/chipmaking/ 6 Moore’s Law • “The number of transistors on a chip doubles about every two years” – Driven by High Volume Manufacturing + Economics – Drives Semiconductor Research roadmap

# trans. / chip 2011 106  220 # trans. / chip 1971

Gordon Moore, Co-founder, Intel Corporation http://www.intel.com/pressroom/kits/events/moores_law_40th

• Compared to Intel’s first microprocessor, latest microprocessors … • Run +4000X faster • Each transistor uses +5000X less energy • Price per transistor dropped by +50 000X

7 Technology Development @ Intel

• A New Technology introduced every 2 years (Tic – Toc)

transistor

chip cross interconnects section

transistors

chip top view ~ 300 transistors

http://download.intel.com/newsroom/kits/22nm/pdfs/22nm-Details_Presentation.pdf

red blood cell http://en.wikipedia.org/wiki/File: Red_White_Blood_cells.jpg 8 Technology Development @ Intel (cont.)

• New Technology often involve revolutionary innovations …

2013 2015 14 nm 10 nm ? ?? http://download.intel.com/newsroom/kits/22nm/pdfs/22nm-Details_Presentation.pdf

ALD technology enabler ALD intrinsic in process development

9 2. Introduction to Atomic Layer Deposition

10 Atomic Layer Deposition (ALD)

Thin Film deposition process characterized by: 1. Complementary and Self-limiting surface reactions 2. Monolayer thickness control 3. ALD processes often involve cyclic exposures and purges of reactants

Example: GeO2 over crystalline Ge for MOSFETs

~ 1 atom thickness

Tanaka and Takagi, ECT Trans, 2011

11 Examples & Uses of ALD

Industries: • Semiconductors coating of • Micro-Electro-Mechanical Systems (MEMS) nano-particles • Nano-Electro-Mechanical Systems (NEMS) nanopores • Displays and OLED Lighting Technologies • Flexible electronics • Textiles

Applications: • Lubrication of moving parts lining & filling • Optical coatings (reflective, anti‐reflective, absorbers) • Corrosion protection • Increased hardness of the mechanical layer nanotube • Tuning of mechanical properties (i.e., stiffness) coating • Charge dissipation photonic • Hydrophobic surface or uniform nucleation layers crystals • Protective layers for biocompatible coating of MEMS • Controlled gap filling, closing on nano‐scale pores • Hermetic coatings • Growth of sacrificial layers for small gaps

A. Londergan (Qualcomm), New Opportunities for ALD in MEMS, NEMS, Displays and OLED Lighting Technologies, Workshop, Atomic Layer Deposition, Cambridge, MA, 2011

R. Gordon, Atomic Layer Deposition (ALD): An Enabler for Nanoscience and Nanotechnology, Harvard University

12 Gas Chemistry Kinetics

• Elementary reaction: A B k C  D

produces with 1 mole of  1 mole of  probability k 1 mole of  1 mole of    "collides" with     together with   molecules A molecules B molecules C molecules D

Reaction rate: R  k A B d[A] d[B] d[C] d[D] ([ ] = molar concentration)          R dt dt dt dt

• Example: Hydrogen Bromide synthesis

k H2 (g)  Br2 (g) 2HBr(g)

H Br Br H H Br H + Br

13 Surface Chemistry Kinetics

• Similar to Gas kinetics, BUT surface as reactant • Ex: Silicon deposition from Silane H H H H Si H SiH (g)  Si(s)  Si(b)  Si(s)  2H (g) H H 4 2 H +

(g): gas surface  Si Si Si … Si Si Si (s): surface bulk  (b): bulk Si

• Film growth occurs by repetitive insertion of bulk species; types:

a) two-dimensional b) island c) random

1. R. L. Puurunen, J. App. Phys. 97, 121301 (2005) 14 ALD Chemistry

• “Complementary Self-Limiting Surface Reactions” Ideal 2-step ALD • “Canonical” ideal ALD of A-B film chemistry is rarely (if ever) found (g): gas, (s): surface, (b): bulk

B(b) in bi-prod out A(b) in bi-prod out bulk

AB film

time

inject A A(g)  B(s) k1  A(s)  C(g)  B(b) insert B inject B B(g)  A(s) k2 B(s)  C(g)  A(b) insert A

precursors surface termination bi-products film

+ D(g), dilutant always present 15 Example: ALD of TiN

• TiN deposition from TiCl4 and NH3

TiCl4 (g)  NH 2 (s)  TiCl2 (s)  2HCl(g)  N(b)  N deposition

2NH 3 (g) TiCl2 (s)  2NH 2 (s)  2HCl(g) Ti(b)  Ti deposition                     precursors intermediate surface termination gaseous bi-product products

H. Kim, J. Vac. Sci. Technol. B 21„(6), Nov/Dec 2003

N deposition Ti deposition

16 Elements in ALD

Elements used in ALD films

~ most elements Combination of BUT often: high T, elements in ALD films undesired bi- prods, expensive, …

R. Gordon, Introduction to the Chemistry of ALD, Atomic Layer Deposition, Cambridge, MA, 2011 based on data in R. Puurunen, J. Appl. Phys. 97, 121301 (2005) 17 ALD Process

Typical type showerhead reactor “Cyclic exposure and removal of reactants over the substrate”

• Example 2-reactans, 4-stages cycle:

1. Flow reactant A over substrate for time t1 wafer

2. Evacuate reactant A for time t2 Flow path exhaust 3. Flow reactant B over substrate, time t3 B. Devulapalli, Deposition: One Layer at a 4. Evacuate reactant B, time t4 Time, Report, Fluent (2003)

A(s)

B(s)

1. R. L. Puurunen, J. App. Phys. 97, 121301 (2005) 18 Molecular Dynamics Simulation of ALD