Granted Patent B2

US 12,506,038 · App. 18/410,770 · Granted Dec 23, 2025

Inventor: Ilseok Son (Albany, NY)

Assignee: Tokyo Electron Limited

H01L22/12G01B11/272

Abstract

Claims (50)

1 . A method for measuring overlay, comprising:

receiving an image of a bonded wafer;

generating, based on the image, a profile of the bonded wafer; and

adjusting, using the profile, an objective lens of a single-focus image-based infrared (IR) system to perform an overlay measurement of the bonded wafer.

2 . The method of claim 1 , wherein the profile comprises a contour of the bonded wafer, and wherein adjusting the objective lens comprises:

adjusting the objective lens along the contour of the bonded wafer to perform the overlay measurement of the bonded wafer.

3 . The method of claim 2 , wherein the contour of the bonded wafer is determined without a vertical scan of the bonded wafer.

4 . The method of claim 1 , wherein generating the profile comprises:

scanning a low spatial frequency component of warpage of at least the bonded wafer; and

mapping the low spatial frequency component of the warpage to the image of the bonded wafer to generate the profile.

5 . The method of claim 1 , wherein adjusting the objective lens comprises:

adjusting the objective lens to a position having a predefined focal distance from the bonded wafer according to the profile; and

responsive to adjusting the objective lens, obtaining at least one image of the bonded wafer at the position using the objective lens.

6 . The method of claim 1 , wherein the bonded wafer comprises a first wafer coupled to a second wafer, and wherein the overlay measurement comprises an overlay mark between the first wafer and the second wafer.

7 . The method of claim 1 , further comprising:

receiving a second image of a second bonded wafer; and

adjusting, using the profile, the objective lens to perform the overlay measurement of the second bonded wafer.

8 . The method of claim 7 , wherein a variation between a first contour of the bonded wafer and a second contour of the second bonded wafer is within a predefined range.

9 . The method of claim 1 , further comprising:

storing the profile of the bonded wafer in a look-up table in response to generating the profile.

10 . The method of claim 1 , wherein receiving the image of the bonded wafer comprises scanning at least one of an x-axis or a y-axis of the bonded wafer to generate the image.

11 . A measurement system, comprising:

at least one processor configured to:

receive an image of a bonded wafer;

generate, based on the image, a profile of the bonded wafer; and

adjust, using the profile, an objective lens of a single-focus image-based infrared (IR) system to perform an overlay measurement of the bonded wafer.

12 . The measurement system of claim 11 , wherein the profile comprises a contour of the bonded wafer, and wherein to adjust the objective lens, the measurement system is configured to:

adjust the objective lens along the contour of the bonded wafer to perform the overlay measurement of the bonded wafer.

13 . The measurement system of claim 12 , wherein the contour of the bonded wafer is determined without a vertical scan of the bonded wafer.

14 . The measurement system of claim 11 , wherein to generate the profile, the at least one processor is configured to:

scan a low spatial frequency component of warpage of at least the bonded wafer; and

map the low spatial frequency component of the warpage to the image of the bonded wafer to generate the profile.

15 . The measurement system of claim 11 , wherein to adjust the objective lens, the at least one processor is configured to:

adjust the objective lens to a position having a predefined focal distance from the bonded wafer according to the profile; and

responsive to adjusting the objective lens, obtain at least one image of the bonded wafer at the position using the objective lens.

16 . An apparatus, comprising:

an inspection system comprising at least one processor configured to:

receive an image of a bonded wafer;

generate, based on the image, a profile of the bonded wafer; and

a single-focus image-based infrared (IR) system comprising an objective lens, configured to:

adjust, using the profile, the objective lens to perform an overlay measurement of the bonded wafer.

17 . The apparatus of claim 16 , wherein the bonded wafer comprises a first wafer coupled to a second wafer, and wherein the overlay measurement comprises an overlay mark between the first wafer and the second wafer.

18 . The apparatus of claim 16 , wherein:

the at least one processor is further configured to:

receive a second image of a second bonded wafer; and

the single-focus IR system is further configured to:

adjust, using the profile, the objective lens to perform the overlay measurement of the second bonded wafer.

19 . The apparatus of claim 18 , wherein a variation between a first contour of the bonded wafer and a second contour of the second bonded wafer is within a predefined range.

20 . The apparatus of claim 16 , further comprising:

a storage device configured to store the profile of the bonded wafer in a look-up table in response to generating the profile.

Assignments (1)

Continuity (1)

References Cited (9)