Visible laser probing for circuit debug and defect analysis

Patent metadata

Field	Value
Publication number	US-9651610-B2
Application number	US-201313931869-A
Country	US
Kind code	B2
Filing date	Jun 29, 2013
Priority date	Jun 29, 2013
Publication date	May 16, 2017
Grant date	May 16, 2017

Abstract

Visible laser probing is described. In one example a probe device has a laser configured to provide a laser beam at a visible wavelength, an objective lens positioned in front of the laser to focus the laser beam on an active region of an integrated circuit through a back side of an integrated circuit die, and a detector positioned to receive a reflected laser beam reflected from the active region through a back side of the die, through the objective lens. The detector is configured to detect an amplitude modulation of the reflected laser beam wherein the amplitude modulation is attributable to the electric field at the active region.

First claim

What is claimed is:

1. A method for detecting a voltage at an active region of an integrated circuit (IC), the method comprising:
operating a laser beam at a visible wavelength;
focusing the laser beam through a back side of the IC on an active region of the IC, the back side being opposite a front side, the front side having the active region and metal routing layers;
receiving light of the laser beam from the active region of the front side through the back side of the IC at a detector; and
determining a voltage of the region of the front side based on the received light.

2. The method of claim 1 , wherein determining a voltage comprises detecting an amplitude modulation of the received light and relating the amplitude modulation to an electric field in the active region.

3. The method of claim 1 , wherein receiving light comprises receiving light through a GaP solid immersion lens.

4. The method of claim 1 , wherein receiving light at the detector comprises bandpass filtering for receiving only light of the visible wavelength of the laser beam.

5. The method of claim 1 , further comprising thinning the back side of the IC adjacent the active region by about 100 to 1000 μm before focusing the laser beam on the active region through the back side of the IC.

6. The method of claim 1 , wherein the laser beam is a first laser beam, the method further comprising:
operating a second laser beam at an infrared wavelength longer than the visible wavelength; and
combining the first and second laser beams, wherein focusing comprises focusing the first and second combined laser beams.

7. The method of claim 6 , wherein the first laser beam is a pump laser to excite the active region of the IC and the second laser beam is a probe laser, the reflection of which is to be detected.

8. The method of claim 7 , further comprising driving he active region at a clock frequency, wherein the pump laser is modulated at a frequency much lower than the clock frequency, and wherein the probe laser is driven with a continuous wave.

9. The method of claim 6 , wherein receiving light at the detector comprises bandpass filtering for receiving only light of an infrared wavelength.

10. The method of claim 6 , wherein receiving light at the detector comprises bandpass filtering for receiving only light of a visible wavelength.

11. The method of claim 10 , further comprising for line a dimple on the back side of the IC to reduce the thickness of the back side of the IC over the active region.

12. The method of claim 10 , further comprising thinning the back side of the IC to reduce the thickness of the back side of the IC over the active region.

13. A device for detecting an electric field in an integrated circuit (IC), the method comprising: a laser configured to provide a laser beam at a visible wavelength; an objective lens positioned in front of the laser to focus the laser beam on an active region of an integrated circuit through a back side of the IC, the back side being opposite a front side, the front side having the active region and metal routing layers; and, a detector positioned to receive a reflected laser beam reflected from the active region of the front side through a back side of the IC, through the objective lens, the detector configured to detect an amplitude modulation of the reflected laser beam, and wherein the amplitude modulation is attributable to the electric field an the active region of the front side.

14. The device of claim 13 , wherein the amplitude modulation is further attributable to photo-absorption and reflectance modulation of the laser beam in the active region.

15. The device of claim 13 , further comprising a test driver to drive the active region at a clock frequency.

16. The device of claim 13 , wherein the objective lens is a GaP solid immersion lens.

17. A device for detecting an electric field in an integrated circuit (IC), the method comprising a first laser configured to provide a laser beam at a visible wavelength; a second laser configured to provide a laser beam at an infrared wavelength; an objective lens positioned in front of the first and second laser to focus the first and second laser beams on an active region of an integrated circuit through a back side of the IC, the back side being opposite a front side, the from side having the active region and metal routing layers; a beam splitter positioned between the first and second lasers and the objective lens to combine the first and second laser beams; a detector positioned to receive a reflected laser beam reflected from the active region of the front side through a back side of the IC, through the objective lens, the detector configured to detect an amplitude modulation of the reflected laser beam; and a test driver to drive the active region of the front side at a clock frequency and to drive the second laser with a continuous wave, wherein the amplitude modulation is attributable to the electric field at the active region.

18. The device of claim 17 , wherein the beam splitter is a polarizing beam splitter, the device further comprising a half wave plate and quarter wave plate, the polarizing beam splitter positioned between the half wave plate and the quarter wave plate.

19. The device of claim 17 , wherein the detector comprises an infrared detector.

20. The device of claim 17 , wherein the detector comprises a visible light detector.

Assignees

• Eiles Travis M
• Giridharagopal Rajiv
• Shykind David
• Intel Corp

Inventors

• Eiles Travis M
• Giridharagopal Rajiv
• Shykind David

Classifications

• G01R31/2656 Primary

  using non-ionising electromagnetic radiation, e.g. optical radiation · CPC title

• G01R31/311

  of integrated circuits {(G01R31/31728 takes precedence)} · CPC title