Dispersion model for band gap tracking

Patent metadata

Field	Value
Publication number	US-9595481-B1
Application number	US-201414464640-A
Country	US
Kind code	B1
Filing date	Aug 20, 2014
Priority date	Aug 23, 2013
Publication date	Mar 14, 2017
Grant date	Mar 14, 2017

Abstract

Methods and systems for determining band structure characteristics of high-k dielectric films deposited over a substrate based on spectral response data are presented. High throughput spectrometers are utilized to quickly measure semiconductor wafers early in the manufacturing process. Optical models of semiconductor structures capable of accurate characterization of defects in high-K dielectric layers and embedded nanostructures are presented. In one example, the optical dispersion model includes a continuous Cody-Lorentz model having continuous first derivatives that is sensitive to a band gap of a layer of the unfinished, multi-layer semiconductor wafer. These models quickly and accurately represent experimental results in a physically meaningful manner. The model parameter values can be subsequently used to gain insight and control over a manufacturing process.

First claim

What is claimed is:

1. A non-transitory, computer-readable medium, comprising:
code for causing a computer to receive a spectral response of an unfinished, multi-layer semiconductor wafer across a spectral range;
code for causing the computer to determine a plurality of parameter values of an optical dispersion model of one or more layers of the multi-layer semiconductor wafer based at least in part on the spectral response, wherein the optical dispersion model includes a Cody-Lorentz model having a first derivative of a dielectric function with respect to energy that is continuous at the Urbach transition energy of the Cody-Lorentz model, wherein the rate of attenuation of the Urbach function, E u , is defined as

E
u

=

E
1

∂

E
1

/

∂

E
t

=

E
1

D

,

 wherein

D
=

E
0
4

-

E
t
4

(

E
0
2

-

E
t
2

)

2

+

Γ
2

⁢

E
t
2

+

E
p
2

(

E
t

-

E
g

)

2

+

E
p
2

·

E
t

E
t

-

E
g

;

 and wherein E t , is the demarcation energy, E 0 , is the resonant energy of a Lorentz function, E g , is the band gap energy, E p , is the transition energy, and Γ, is the width of the Lorentz function; and
code for causing the computer to store the plurality of parameter values of the optical dispersion model in a memory.

2. The non-transitory, computer-readable medium of claim 1 , wherein the optical dispersion model is sensitive to a band gap of a layer of the unfinished, multi-layer semiconductor wafer.

3. The non-transitory, computer-readable medium of claim 1 , further comprising:
code for causing the computer to determine a band structure characteristic indicative of an electrical performance of a first layer of the multi-layer semiconductor wafer based at least in part on parameter values of the optical dispersion model of the multi-layer semiconductor wafer.

4. The non-transitory, computer-readable medium of claim 3 , wherein the electrical performance of the multi-layer semiconductor wafer is any of an equivalent oxide thickness (EOT), a leakage current, a threshold voltage, and a breakdown voltage.

5. The non-transitory, computer-readable medium of claim 3 , further comprising:
code for causing the computer to control a process of manufacture of the unfinished, multi-layer semiconductor wafer based at least in part on the band structure characteristic.

6. The non-transitory, computer-readable medium of claim 1 , wherein the one or more layers include at least one nanostructure.

7. The non-transitory, computer-readable medium of claim 6 , wherein the at least one nanostructure is any of a plurality of quantum dots, a plurality of nanowires, and a plurality of quantum wells.

8. The non-transitory, computer-readable medium of claim 1 , wherein a first layer of the one or more layers is an electrically insulative layer disposed above a semiconductor substrate.

9. The non-transitory, computer-readable medium of claim 8 , wherein the first layer includes an intermediate layer between the semiconductor subs

Assignees

• Kla Tencor Corp

Inventors

• Malkova Natalia
• Poslavsky Leonid
• Di ming
• Zhao Qiang
• Hu Dawei

Classifications

• H10P74/203 Primary

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• G01N21/27

  using photo-electric detection (G01N21/31 takes precedence){; circuits for computing concentration (logarithmic circuits G06G7/24; photometric circuits in general G01J)} · CPC title

• G01R31/308

  using non-ionising electromagnetic radiation, e.g. optical radiation {(investigating or analysing materials by the use of optical means G01N21/00; image analysis G06T7/00)} · CPC title

• G01R31/2831

  Testing of materials or semi-finished products, e.g. semiconductor wafers or substrates (G01R31/318511 takes precedence; testing during manufacture H10P74/00) · CPC title

• G01R31/2648

  Characterising semiconductor materials (testing of materials or semi-finished products G01R31/2831; testing during manufacture H10P74/00) · CPC title