METHODS FOR DISTINGUISHING A SET OF HIGHLY DOPED REGIONS FROM A SET OF LIGHTLY DOPED REGIONS ON A SILICON SUBSTRATE

• US 20110045612A1
• Filed: 08/20/2009
• Published: 02/24/2011
• Est. Priority Date: 08/20/2009
• Status: Active Grant

• Current Assignee: Innovalight, Inc. (Corteva, Inc.)
• Original Assignee: Innovalight, Inc. (Corteva, Inc.)
• Inventors: Scardera, Giuseppe, Kelman, Maxim
• Granted Patent: US 8,148,176 B2
• Time in Patent Office: Days
• US Class Current: 438/7
• CPC Class Codes: G01J 3/42 Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry beam switching arrangements G01J3/08
• CPC Class Codes: G01N 21/3563 for analysing solids; Preparation of samples therefor
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: H01L 22/12 for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions electrical measurement of diffusions H01L22/14

Abstract

A method of distinguishing a set of highly doped regions from a set of lightly doped regions on a silicon substrate is disclosed. The method includes providing the silicon substrate, the silicon substrate configured with the set of lightly doped regions and the set of highly doped regions. The method further includes illuminating the silicon substrate with an electromagnetic radiation source, the electromagnetic radiation source transmitting a wavelength of light above about 1100 nm. The method also includes measuring a wavelength absorption of the set of lightly doped regions and the set of heavily doped regions with a sensor, wherein for any wavelength above about 1100 nm, the percentage absorption of the wavelength in the lightly doped regions is substantially less than the percentage absorption of the wavelength in the heavily doped regions.

Claims

1. A method of distinguishing a set of highly doped regions from a set of lightly doped regions on a silicon substrate, comprising:

providing the silicon substrate, the silicon substrate configured with the set of lightly doped regions and the set of highly doped regions;

illuminating the silicon substrate with an electromagnetic radiation source, the electromagnetic radiation source transmitting a wavelength of light above about 1100 nm; and

measuring an absorption of the set of lightly doped regions and the set of heavily doped regions with a sensor, wherein for any wavelength above about 1100 nm, the percentage absorption of the wavelength in the lightly doped regions is substantially less than the percentage absorption of the wavelength in the heavily doped regions.

2. The method of claim 1, further comprising the step of depositing a set of metal contacts on the set of highly doped regions after illuminating the silicon substrate with the electromagnetic radiation source.

3. The method of claim 1, wherein the set of highly doped regions comprises a dopant concentration of 10¹⁸ to 10²⁰ atoms/cm³.

4. The method of claim 1, wherein the set of highly doped regions comprises one of a p-type dopant and an n-type dopant.

5. The method of claim 1, wherein the set of lightly doped regions comprises a dopant concentration of 10¹⁴ to 10¹⁷ atoms/cm³.

6. The method of claim 1, wherein the set of lightly doped regions comprises one of a p-type dopant and an n-type dopant.

7. The method of claim 1, wherein the wavelength of light above about 1100 nm is transmitted with a white light radiation source.

8. The method of claim 7, wherein the white light radiation source is a halogen tungsten lamp.

9. The method of claim 1, wherein the sensor and the electromagnetic radiation source are positioned on opposite sides of the silicon substrate.

10. The method of claim 1, wherein the sensor is an infrared detector.

11. A method of distinguishing a set of highly doped regions from a set of lightly doped regions on a silicon substrate, comprising:

providing the silicon substrate, the silicon substrate configured with the set of lightly doped regions and the set of highly doped regions;

illuminating the silicon substrate with an electromagnetic radiation source, the electromagnetic radiation source transmitting a wavelength of light between about 1100 nm and about 1700 nm; and

measuring an absorption of the set of lightly doped regions and the set of heavily doped regions with a sensor, wherein for any wavelength between about 1100 nm and about 1700 nm, the percentage absorption of the wavelength in the lightly doped regions is substantially less than the percentage absorption of the wavelength in the heavily doped regions.