WO-2026095053-A1 - POLISHING DEVICE AND METHOD FOR EVALUATING WORK-AFFECTED LAYER IN POLISHING DEVICE

WO2026095053A1WO 2026095053 A1WO2026095053 A1WO 2026095053A1WO-2026095053-A1

Abstract

A new evaluation method for a work-affected layer using an eddy current sensor is provided.　A polishing device for polishing a workpiece having a work-affected layer is provided. This polishing device comprises: a first holder configured to hold and rotate the workpiece; a second holder configured to hold and rotate a polishing tool for polishing the workpiece so as to face the workpiece; at least one eddy current sensor provided at one of the first holder and the second holder; and a controller. The controller is configured to acquire an output signal of the eddy current sensor during polishing of the workpiece, calculate an electric resistance value of a polished layer in the workpiece on the basis of the output signal of the eddy current sensor, and determine the thickness of the work-affected layer in the workpiece on the basis of a deviation of the calculated electric resistance value of the polished layer from a predetermined reference.

Inventors

KOSHINO, Ryota
YASUDA, HOZUMI
HONJO, KEIJI
MASUYA, Koichi
AIDA, HIDEO

Assignees

株式会社荏原製作所
国立大学法人長岡技術科学大学

Dates

Publication Date: 20260507
Application Date: 20251031
Priority Date: 20241031

Claims (15)

A polishing apparatus for polishing a workpiece having a processed altered layer, A first holder configured to hold and rotate the workpiece to be polished, A second holder is configured to hold and rotate a polishing tool for polishing the workpiece so as to face the workpiece, At least one eddy current sensor provided in one of the first holder and the second holder, Control unit and Equipped with, The control unit, During the polishing of the workpiece, the output signal of the eddy current sensor is acquired. Based on the output signal of the eddy current sensor, the electrical resistance value of the polished layer in the workpiece is calculated. Based on the deviation of the calculated electrical resistance value of the polished layer from a predetermined standard, the thickness of the processed and altered layer in the polished object is determined. A polishing device configured as follows.
The polishing apparatus according to claim 1, wherein the predetermined standard is the relationship between the thickness of the polished layer and the electrical resistance value in a workpiece that does not have a processed and altered layer.
The aforementioned determination is, Based on the thickness of the layer to be polished and the calculated electrical resistance value of the layer to be polished, the magnitude of the deviation from the predetermined standard is calculated. Based on the magnitude of the deviation from the predetermined standard, the thickness of the processed altered layer in the workpiece is determined. The polishing apparatus according to claim 2, including the following:
The aforementioned determination is, The second derivative of the calculated electrical resistance value of the polished layer with respect to the thickness of the polished layer is calculated, When the second derivative of the polished layer with respect to its electrical resistance becomes zero, it is determined that the thickness of the processed and altered layer in the polished object has become zero. The polishing apparatus according to claim 2, including the following:
The polishing apparatus according to claim 4, comprising estimating the time when the value of the second derivative becomes zero using the multiple second derivative values calculated above.
The aforementioned determination is, The rate of change of the calculated electrical resistance value of the layer to be polished with respect to the thickness of the layer to be polished is calculated, When the rate of change of the electrical resistance of the polished layer becomes constant, it is determined that the thickness of the processed and altered layer in the polished object has reached its minimum value. The polishing apparatus according to claim 2, including the following:
The polishing apparatus according to any one of claims 1 to 6, wherein, during the polishing of the workpiece, the eddy current sensor is driven using a drive frequency that changes from a first frequency to a second frequency higher than the first frequency.
The system further includes an airbag capable of adjusting the polishing pressure applied to the workpiece, The control unit is further configured to control the internal pressure of the airbag based on the thickness of the processed altered layer in the workpiece. The polishing apparatus according to any one of claims 1 to 6.
Multiple eddy current sensors are provided in the first holder. The plurality of eddy current sensors are arranged in a line along the circumferential or radial direction of the first holder. The polishing apparatus according to any one of claims 1 to 6.
The first holder comprises a first portion that does not rotate and a second portion configured to rotate relative to the first portion. The first portion of the first holder is provided with at least one eddy current sensor, The workpiece to be polished is held in the second portion of the first holder. The polishing apparatus according to any one of claims 1 to 6.
A method for evaluating the processed layer of a workpiece in a polishing apparatus for polishing a workpiece having a processed layer, wherein the polishing apparatus is A first holder configured to hold and rotate the workpiece to be polished, A second holder is configured to hold and rotate a polishing tool for polishing the workpiece so as to face the workpiece, At least one eddy current sensor provided in one of the first holder and the second holder, The method comprises, The steps include acquiring the output signal of the eddy current sensor while polishing the workpiece, The steps include: calculating the electrical resistance value of the polished layer in the workpiece based on the output signal of the eddy current sensor; A step of determining the thickness of the processed and altered layer in the workpiece based on the deviation of the calculated electrical resistance value of the workpiece from a predetermined standard, Methods that include...
The method according to claim 11, wherein the predetermined standard is the relationship between the thickness of the polished layer and the electrical resistance value in a workpiece that does not have a processed and altered layer.
The aforementioned determination step is, A step of calculating the magnitude of deviation from the predetermined standard based on the thickness of the layer to be polished and the calculated electrical resistance value of the layer to be polished, A step of determining the thickness of the processed altered layer in the workpiece based on the magnitude of the deviation from the predetermined standard, The method according to claim 12, including the method described in claim 12.
The aforementioned determination step is, The steps include: calculating the second derivative of the calculated electrical resistance value of the polished layer with respect to the thickness of the polished layer; The step of determining that the thickness of the processed and altered layer in the workpiece has become zero when the second derivative of the polished layer with respect to its electrical resistance becomes zero, The method according to claim 12, including the method described in claim 12.
The aforementioned determination step is, The steps include: calculating the rate of change of the calculated electrical resistance value of the layer to be polished with respect to the thickness of the layer to be polished; The step of determining that the thickness of the processed and altered layer in the workpiece has reached its minimum value when the rate of change of the electrical resistance value of the polished layer becomes constant, The method according to claim 12, including the method described in claim 12.

Description

Polishing apparatus and method for evaluating the processed altered layer in the polishing apparatus This invention relates to a polishing apparatus and a method for evaluating the processed and altered layer in a polishing apparatus. One type of semiconductor device manufacturing equipment is a CMP (Chemical Mechanical Polishing) machine. A typical CMP machine comprises a polishing table with a polishing pad attached and a polishing head with a substrate attached. In a typical CMP machine, polishing fluid is supplied to the polishing pad, and the substrate is polished by rotating at least one of the polishing table and the polishing head while the polishing pad and the substrate are in contact. On the surface of a workpiece such as a substrate, a processed layer may be formed during processing steps such as cutting, which are pre-processing steps before polishing. This processed layer is a layer whose physical properties have changed from the original material, and it is required to be completely removed by polishing. Reference 1 discloses a technique for detecting this processed layer using an eddy current sensor. This is a front view of a polishing apparatus according to one embodiment of the present invention.This is a schematic cross-sectional view showing the structure of an exemplary substrate that is to be polished by a polishing device.This is an illustrative model showing the relationship between the depth x from the substrate surface and the electrical resistivity ρ at that location.Figure 3 is a graph showing the relationship between the sheet resistance R_S and thickness t of the substrate obtained using the model.This is another type of graph showing the relationship between the sheet resistance R<sub>S</sub> and thickness t of the substrate obtained using the model in Figure 3.This figure shows the estimated point at which the thickness of the processed and altered layer becomes zero.This is a flowchart showing a control method for a polishing apparatus according to one embodiment of the present invention.This is yet another type of graph showing the relationship between the sheet resistance R<sub>S</sub> and thickness t of the substrate obtained using the model in Figure 3.This is a front view of a polishing apparatus according to a second embodiment of the present invention.This is a top view of a substrate holder of a polishing apparatus according to a second embodiment of the present invention.This is a cross-sectional view showing a modified example of the substrate holder of a polishing apparatus according to a second embodiment of the present invention.This is a front view of a modified example of a polishing apparatus according to a second embodiment of the present invention. The embodiments of the present invention will be described below with reference to the drawings. In the drawings described below, identical or corresponding components are denoted by the same reference numerals, and redundant descriptions are omitted. <First Embodiment> Figure 1 is a front view of a polishing apparatus 100 according to one embodiment. The polishing apparatus 100 shown in Figure 1 is a CMP (Chemical Mechanical Polishing) apparatus. However, the polishing apparatus 100 is not limited to a CMP apparatus. The polishing apparatus 100 can be any apparatus that polishes an object to be polished, such as a substrate, by rotating a polishing table equipped with an eddy current sensor. The CMP apparatus 100 comprises a polishing table 110, a polishing head 120, and a liquid supply mechanism 130. The CMP apparatus 100 further includes a control unit 140 for controlling each component. The control unit 140 may include, for example, a storage device 141, a processor 142, and an input/output device 143. A polishing pad 111 is detachably attached to the upper surface of the polishing table 110. Here, the upper surface of the polishing table 110 refers to the surface of the polishing table 110 facing the polishing head 120. Therefore, the upper surface of the polishing table 110 is not limited to the surface located vertically upward. The polishing head 120 is positioned to face the polishing table 110. A substrate 121 is detachably attached to the surface of the polishing head 120 facing the polishing table 110. The substrate 121 is an example of a workpiece. The substrate 121 may be, for example, a Si (silicon) substrate, a SiC (silicon carbide) substrate, a GaN (gallium nitride) substrate, etc. It is not limited to such semiconductor substrates; any object may be used as the workpiece. The liquid supply mechanism 130 is configured to supply a polishing liquid such as slurry to the polishing pad 111. The liquid supply mechanism 130 may also be configured to supply cleaning liquid or chemical solutions in addition to polishing liquid. The CMP apparatus 100 lowers the polishing head 120 using a vertical movement mechanism (not shown) to bring the substrate 121 into contact with the polishing pad 111. However, th