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

ELASTIC METAL PROBE C-V PROFILING

 

 

The FCV method makes rapid measurement of electrical parameters associated with dielectrics including gate oxides and most near-surface implants including source/drain.  The system has excellent sensitivity over a wide range of implant dose.

FCV is a very effective method for measuring the electrical properties of dielectrics, pn-junctions, Si, SiC and GaN epitaxial layers on either bare or patterned wafers. CV Measurements are performed using patented EM-probe technology without chemical treatment, eliminating mercury contacts and damage or contamination on the wafer surface.

FCV systems use a small elastic probe to form a temporary gate on the dielectric surface.

There are two types of Elastic Material Probes (EM-Probes) that are used. The first, a type A probe is used for all CV and GV and surface resistivity measurements. It has a self-contained dielectric on the probe surface that blocks direct tunneling currents and allows for leakage free CV measurements down to about 6 Angstroms of SiO2. For IV measurements, a type C probe is used. This probe uses a unique metal that does not readily oxidize and whose oxide is conductive rather than insulating. The elastic probe has a diameter of less than 30 µm and does not damage the dielectric surface.

MEASURED PARAMETERS:

  • Capacitive Effective Thickness (CET)
  • Equivalent Oxide Thickness (EOT)
  • Density of Interface State (Dit)
  • Flatband Voltage (Vfb)
  • Threshold Voltage (VT)
  • Oxide capacitance
  • Average Surface Doping (NSURF)
  • Changing of Flatband Voltage (Delta Vfb)
  • Conductance Peak (Gmax)

FCV forward and reverse CV curves. The key CV based parameters are shown in the figure.

FEATURES

  • Non-penetrating Elastic Material probe for rapid monitoring of epi layers
  • Hard probe for patterned wafers with metal pads
  • Specially designed EM probe ensures that no damage is made to the wafer

 

  • The EM probe is not damaging and not contaminating the wafer surfaces
  • Measurement is possible on test vehicles of product wafers
  • Complete C-V profiling, frequency from 1 kHz to 10 MHz

 

Product Line

FCV

Gate dielectrics characterization and ion implant monitoring (10 – 250 Å silicon dioxide or high-k dielectric). Site-based measurements (typically 5 or 9 points per wafer according to SEMI standard testing patterns)
Specially designed probe ensures that no damage is made to the wafer, because the probe is not contaminating the wafer surfaces.

  • Near Surface Electrically Active Dopant Density  (NSURF, ρSURF)
  • Resistivity range: 0.005 to 200 Ωcm  
  • Can measure I-V down to 1 fA

Measurement Capabilities:

  • C-V measurement
  • I-V measurement
  • Ramped Current Stress Test (RCST)
  • Constant Current Stress Test (CCST)

 

  • Ramped Voltage Stress Test (RVST)
  • Constant Voltage Stress Test (CVST)
  • Offline Carrier Profiling

 

 

 

Products

FCV-3000

Advanced Implant Metrology System

The FCV-3000 Advanced Implant Metrology System makes rapid measurement of electrical parameters associated with dielectrics including gate oxides and most near-surface implants including source/drain.  The system has excellent sensitivity over a wide range of implant dose.

The system contains a class 1 mini-environment and meets applicable SEMI and CE standards.

FCV Systems use a small elastic probe to form a temporary gate on the dielectric surface. An integrated pattern recognition system locates scribe line test areas.
The elastic probe has a diameter of less than 30 µm for dielectric characterization, and more than 200 µm for surface resistivity measurements, and does not damage the dielectric surface.
Beside the elastic probe, a hard metal probe for 1-pin measurements and a hard metal probe pair for 2-pin measurements are also available which gives a more precise positioning.

Features and System specifications:

  • No mercury contact.  Non-damaging and non-contaminating probe permits wafer reuse.
  • Easy to learn and use SAM User Interface running under Windows 7.
  • Easy transfer of data over fab networks with common networking software. 
  • Easy storage, management, and use of over 200 measurement recipes for process-specific needs.
  • Loading from a dual load port in FCV-3000.
  • Measurements down to 1 mm edge exclusion.
  • Integrated desorber, programmable pretreatment to stabilize wafer surfaces.
  • Automated wafer handling for 200 and 300 mm wafers
  • OHT

Each system is then configured to the user’s requirements by adding measurement capabilities and automation capabilities described below.

Measurement Capabilities:

  • C-V measurement
  • I-V measurement
  • Ramped Current Stress Test (RCST)
  • Constant Current Stress Test (CCST)
  • Ramped Voltage Stress Test (RVST)
  • Constant Voltage Stress Test (CVST)
  • Offline Carrier Profiling

Probe movement, wafer motion, cassette loading/uploading, and wafer pretreatment are controlled by an internal computer according to user-defined stored recipes. Data analysis is preformed in a comprehensive C-V analysis package.  All are controlled by a simple-to-use graphical user interface complying with the SEMI E95 standard. The basic system includes the Front End Module (including wafer stage, robot, and pre-aligner), System Controller, Electronic Cabinet, Pneumatics Control Unit, EM-probe system and optional one- or two- pin hard probe with online backup, Capacitance-Voltage Meter, and a comprehensive software suite, including system control software, recipe and measurements databases, and a library of C-V measurement types.

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