US-20260124711-A1 - CHEMICAL MECHANICAL PLANARIZATION TOOL

Abstract

A system includes a platen configured to hold a polishing pad, wherein the polishing pad includes grooves in a top surface of the polishing pad and openings extending from the grooves to a bottom surface of the polishing pad; a holder configured to hold a workpiece above the polishing pad; and optical inspection devices within the platen, wherein the optical inspection devices are configured to measure a characteristic of a bottom surface of the workpiece through the openings in the polishing pad.

Inventors

• Jhih Guang WU
• Chih Hung Chen
• Jin-Hao JHANG

Assignees

• TAIWAN SEMICONDUCTOR MANUFACTURING CO., LTD.

Dates

Publication Date

20260507

Application Date

20250411

Claims (20)

1. 1 . A system comprising: a platen configured to hold a polishing pad, wherein the polishing pad comprises: a plurality of grooves in a top surface of the polishing pad; and a plurality of openings extending from the grooves to a bottom surface of the polishing pad; a holder configured to hold a workpiece above the polishing pad; and a plurality of optical inspection devices within the platen, wherein the optical inspection devices are configured to measure a characteristic of a bottom surface of the workpiece through the plurality of openings in the polishing pad.
2. 2 . The system of claim 1 , wherein the polishing pad further comprises a transparent layer extending across the plurality of openings.
3. 3 . The system of claim 1 , wherein the characteristic is a thickness of a bottom layer of the workpiece.
4. 4 . The system of claim 1 , wherein the grooves of the plurality of grooves are in concentric circles.
5. 5 . The system of claim 1 , wherein the grooves of the plurality of grooves are in a spiral arrangement.
6. 6 . The system of claim 1 , wherein the plurality of optical inspection devices are configured to rotate with the platen.
7. 7 . The system of claim 1 , wherein each optical inspection devices comprises a light source and a light sensor.
8. 8 . The system of claim 1 , wherein each opening of the plurality of openings extends over more than one optical inspection device.
9. 9 . An apparatus comprising: a platen configured to rotate, wherein the platen comprises a plurality of optical inspection systems, wherein each optical inspection system respectively comprises a light source and a light sensor; and a polishing pad attached to the platen, wherein the polishing pad comprises: a first pad comprising a plurality of first apertures extending through the first pad, wherein each first aperture is aligned to at least one optical inspection system; and a second pad on the first pad, wherein the second pad comprises: a plurality of second apertures extending through the second pad, wherein each second aperture is aligned to at least one first aperture; and a plurality of first grooves in a top side of the second pad opposite the first pad, wherein each first groove extends over at least one second aperture.
10. 10 . The apparatus of claim 9 , wherein the second pad further comprises a plurality of second grooves in the top side, wherein the second grooves are separated from the plurality of second apertures.
11. 11 . The apparatus of claim 9 , wherein the first apertures and the second apertures have a same width.
12. 12 . The apparatus of claim 9 , wherein the first apertures and the second apertures have different widths.
13. 13 . The apparatus of claim 9 , wherein at least one second aperture extends over multiple optical inspection systems.
14. 14 . The apparatus of claim 9 , wherein the light source is a broadband light source.
15. 15 . The apparatus of claim 9 , wherein the light sensor is a spectrometer.
16. 16 . A method comprising: attaching a polishing pad to a platen, wherein the platen comprises a plurality of light sources and a plurality of optical detectors, wherein the polishing pad comprises a plurality of holes; placing a wafer on the polishing pad, wherein the wafer comprises a gate structure over a plurality of nanostructures; rotating the polishing pad to polish the wafer; while rotating the polishing pad, emitting light from the plurality of light sources through the plurality of holes toward the wafer, and, using the plurality of optical detectors, detecting light reflected from the wafer through the plurality of holes toward the plurality of optical detectors; and singulating the wafer into a plurality of dies.
17. 17 . The method of claim 16 further comprising, based on the light detected by the optical detectors, determining a thickness of a bottom layer of the wafer.
18. 18 . The method of claim 17 further comprising, based on the thickness, stopping rotation of the polishing pad.
19. 19 . The method of claim 16 , wherein polishing the wafer comprises polishing a surface of the gate structure.
20. 20 . The method of claim 16 , wherein the polishing pad further comprises a plurality of grooves aligned to the plurality of holes.

Description

PRIORITY CLAIM AND CROSS-REFERENCE This application claims the benefits of U.S. Provisional Application No. 63/715,039, filed on Nov. 1, 2024, which application is hereby incorporated herein by reference in its entirety. BACKGROUND As the layers of a semiconductor device are formed, planarization processes may be performed to planarize the layers to facilitate formation of subsequent layers. For example, the formation of metallic features in the substrate or in a metal layer may cause uneven topography. This uneven topography may create difficulties in the formation of subsequent layers. For example, uneven topography may interfere with the photolithographic process commonly used to form various features in a device. Therefore, it may be advantageous to planarize the surface of the device after various features or layers are formed. Chemical mechanical polishing (CMP) is a common practice in the formation of integrated circuits. Typically, CMP is used for the planarization of semiconductor wafers. CMP takes advantage of the synergetic effect of both physical and chemical forces for the polishing of wafers. It is performed by applying a load force to the back of a wafer while the wafer rests on a polishing pad. A polishing pad is placed against the wafer. Both the polishing pad and the wafer are then rotated while a slurry containing both abrasives and reactive chemicals is passed therebetween. CMP is an effective way to achieve global planarization of wafers. BRIEF DESCRIPTION OF THE DRAWINGS Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. FIG. 1 illustrates a perspective view of a chemical mechanical polishing (CMP) apparatus, in accordance with an embodiment. FIG. 2 illustrates a magnified cross-sectional view of a CMP apparatus, in accordance with an embodiment. FIG. 3 illustrates a partial schematic of a CMP apparatus in a perspective view, in accordance with an embodiment. FIGS. 4, 5, 6, and 7 illustrate magnified cross-sectional views of a CMP apparatus, in accordance with some embodiments. FIG. 8 illustrates a magnified cross-sectional view of a CMP apparatus, in accordance with an embodiment. FIGS. 9, 10, 11, 12, 13, 14, 15, and 16 illustrate top-down plan views of polishing pads, in accordance with some embodiments. FIG. 17 illustrates a perspective view of example Complementary Field-Effect Transistors (CFETs), in accordance with some embodiments. FIGS. 18, 19, 20, 21, 22, 23, 24, and 25 illustrate cross-sectional views of intermediate stages in the manufacturing of a CFET structure, in accordance with some embodiments. DETAILED DESCRIPTION The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. Through the description herein, unless other specified, the same reference numeral in different figures refers to the same or similar component. Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly. Chemical mechanical polishing (CMP) is a method of planarizing features produced in the manufacture of semiconductor devices. The process uses an abrasive material in a reactive chemical slurry in conjunction with a polishing pad. The polishing pad typically has a greater diameter than that of the semiconductor wafer. In some cases, the polishing pad may be formed of a stack of multiple pads, such as a top pad attached to a sub pad, or the like. The pad and wafer are pressed together during the CMP process. The process removes material and tends to even out irregular topography, making the wafer flat or substantially planar. This