Application

ELECTRICAL CHARACTERIZATION OF DIELECTRICS AND INTERFACES

 

Controlling electrical properties of dielectrics and the interfaces they form with semiconductors is imperative for achieving high IC device performance and yield.  Semilab offers metrology solutions to electrically characterize the critical dielectric layers and processes that span process modules ranging from FEOL to BEOL. 

The most common implementation of Semilab’s in-line electrical metrology is replacement of the IC MOS short-loop, which alleviates the need for expensive and time-consuming processing.  The in-line methods provide rapid feedback without the need for preparing devices; resulting in increased process tool utilization time for critical product.   The two primary MOS measurements being replaced are; 1) Capacitance – Voltage (C-V) method for determination of Dielectric Capacitance, Dielectric Charges, and Dielectric/Semiconductor Interface Quality; and 2) the Current – Voltage (I-V) method that measures Dielectric Leakage and Breakdown.

The below table summarizes the dielectric properties measured by Semilab systems, the associated critical IC device parameters that are affected, and the process areas in which the issues are commonly encountered.

Measured properties of dielectrics and interfaces:

Measured Property Affected Device Parameter Process Module
Dielectric/ Semiconductor Interface Quality (Dit, Qit, Nit) Threshold voltage (Vt), Carrier Mobility, Reliability/ Hysteresis Diffusion,
Gate,
Cleaning,
ILD
Plasma
Thin Films
Dielectric Charge (Qf, Qm, Qot, Vfb) Vt, Reliability/ Hysteresis Diffusion
Gate
Plasma
Thin Films
Dielectric Capacitance (CD, CET, EOT) Vt, Reliability/ GOI, RC Diffusion
Gate
ILD
Thin Films
Surface Charge (VPDM, NVD, Vsurf) Reliability/ GOI Cleaning
Plasma
Thin Films
Ion Implant
Dielectric Leakage (I-V, I-E, SILC, Etunnel) Reliability/ GOI Diffusion
Gate
Cleaning
ILD
Plasma

In order to meet the individual requirements of our diverse customer base, Semilab offers various versions of these techniques using multiple approaches; including the non-contact Corona-Kelvin method (FAaST system) and the contact methods using Elastic Metal Probe (FCV system) and Mercury Probe (MCV system).

Technology

MERCURY C-V PROFILING

 

MCV systems allow to eliminate the need for costly metal and poly deposition processes by using a pneumatically controlled, non-damaging probe design and a top-side mercury contact. The system features an extremely stable contact area and uses only a small quantity of mercury to make highly repeatable C-V and I-V measurements for process development and process monitoring applications. MCV is superior technique both for bulk/epitaxial- and dielectric layer characterization.

The Hg C-V technique uses a high repeatability, non-scrubbing, vertical arm probe. The probe includes a 2 cm long capillary that holds a small volume of mercury and is electrostatically shielded to reduce stray capacitance and it’s positional dependence. The epitaxial wafer is placed on the stage, processed side up, either manually or with a robot. The Hg probe is then lowered from the topside in a controlled manner to form a high quality Schottky contact. 

Dielectric constant calculation depends upon two factors:

  • Area repeatability of the Hg probe
  • Accuracy of the ellipsometry measurement to determine oxide thickness.

APPLICATION AND SPECS

MEASURED PARAMETERS

 

C-V measurements of low-K dielectrics, High-k Dielectrics

 

  • Interlayer Dielectrics (Low-k), k = 1 to 3.9

  • Gate Dielectrics (High-k), k => 3.9, EOT > 3 nm

  • Flatband, treshold voltages - VFB , VT
  • Delta VFB,HYS – Δ VFB
  • Effective oxide charge - QEFF
  • Interface state density – DIT
  • Capacitive Effective Thickness- CET
  • Dielectric constant - k
 

QV measurements of Mos Structures

 

  • Range: 5x109 and greater
  • Accuracy: ±5%, 1x1010 carriers/cm2/eV, dependent on user supplied parameters. 

Software automatically calculates sensitivity and valid energy limits.

  • Simultaneously acquired low- and high-frequency C-V curves

  • Interface state density spectrum – DIT(E)

 


 

IV measurements of low-K dielectrics, High-k Dielectrics, Memory Capacitors

 

  • Stepped Voltage, Stepped Current, Constant Current modes
  • DC bias range: -1100V to +1100V
  • Max current/power: 120mA / 180W
  • Leakage current - IL
  • Breakdown voltage - VBD
  • Field to breakdown - FBD
  • Time to dielectric breakdown - TDBD - tBD
  • Charge to breakdown QBD
  • Maximum voltage - Vmax
  • Breakdowns of oxides with different thicknesses

The MCV product line also has powerful features for the Epi Resistivity Measurements and Compound Material Characterization.

FEATURES

Semilab’s mercury (Hg) Schottky C-V technique is suitable for either production or R&D monitoring offering speed, high repeatability, and sensitivity.

  • Complete Schottky C-V resistivity profiling for epitaxial layers
  • Complete MOS C-V electrical characterization for dielectrics to determine thickness, k-value and more
  • Advanced C-V evaluation for compound semiconductors and special applications (HEMT structures, etc.) for detailed analysis of semiconductor-dielectric interface parameters

Product Line

MCV

  • The user friendly software environment controls the measurements and also offers a great flexibility for detailed analysis of the measured structures
  • Full map capability up to 12"/ 300 mm
  • All Semilab's MCV tools are equipped with automated, full hand-off, mercury handling system to increase safety and reliability
  • All features listed above, including optional ones, are compatible with both the manual MCV-530(L) and the automatic MCV-2200/2500 tools.

On top of the standard C-V measurements and standard electronic units, a number of advanced metrology options are available to extend measurement capabilities:

  • Multi-frequency C-V meter (1kHz to 10MHz), KEITHLEY-4200 for advanced dielectric layer characterization
  • Different capillary diameters to meet application demands: standard capillaries d=1.7mm or capillaries with 0.5, 0.7, 1.0 and 4.0mm optionally
  • I-V option: Current-Voltage based Dielectric Integrity and Reliability investigations
  • Q-V option: Low frequency C-V measurements provides the Dit Energy Spectrum
  • Pulsed C-V option
  • Topside Return Contact (TSRC) option for measurement of semiconductor layers deposited on insulating substrates or SOI
  • Mercury Vapour Analyzer option

Products

MCV-2200, MCV-2500

The MCV automatic mapping systems provide a mercury C-V measurement for non-patterned wafers used in epitaxial silicon production and front-end semiconductor processing.

In MCV-2200 and MCV-2500, the wafers are robotically loaded onto the mapping stage from a cassette or opened FOUP. The test wafer moves to each site specified in a pre-programmed map as electrical characterization tests are made. The system stores test data and reports them in a variety of formats.

Optional features:

  • ID reader (front or back, even in case of transparent samples like SiC, GaN)
  • Desorber
  • Light tower option
  • SECS/GEM host communication
  • Can be configured with 300 mm FOUP, 200 mm SMIF or OC

Wafer sizes:

  • Automatic wafer handling:
    • MCV-2200: from 100 mm to 200 mm
    • MCV-2500: from 200 mm to 300 mm
  • Manual wafer handling:
    • Full wafers:
      • MCV-2200: from 50 mm to 200 mm
      • MCV-2500: from 50 mm to 300 mm
    • Coupon samples or fractions:
      • minimum sample size is 40 mm × 40 mm

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MCV-530, MCV-530L

The MCV-530 system is designed for the fast and reliable testing of dielectric and epitaxial layers by mercury probe, and it is ideal for R&D or small volume production.

MCV-530/530L tools are manual loading systems, however they have the same measurement abilities like the automatic MCV-2200/2500 products.

Wafer sizes:

Manual wafer handling:

  • Full wafers:
    • MCV-530L: from 50 mm to 200 mm
    • MCV-530: from 50 mm to 300 mm
  • Coupon samples or fractions:
    • minimum sample size is 40 mm × 40 mm

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