Method and device for measuring dimension of semiconductor structure

Patent metadata

Field	Value
Publication number	US-11656245-B2
Application number	US-202117392430-A
Country	US
Kind code	B2
Filing date	Aug 3, 2021
Priority date	Jan 15, 2021
Publication date	May 23, 2023
Grant date	May 23, 2023

Abstract

A method and device for measuring dimension of a semiconductor structure are provided. A probe of an Atomic Force Microscope (AFM) is controlled at first to move a first distance from a preset reference position to a top surface of a semiconductor structure to be measured in a direction perpendicular to the top surface of the semiconductor structure to be measured, then the probe is controlled to scan the surface of the semiconductor structure to be measured while keeping the first distance in a direction parallel to the top surface of the semiconductor structure to be measured, amplitudes of the probe at respective scanning points on the surface of the semiconductor structure to be measured are detected, and a Critical Dimension (CD) of the semiconductor structure to be measured is determined according to the amplitudes of the probe at respective scanning points on the surface of the semiconductor structure.

First claim

The invention claimed is:

1. A method for measuring dimension of a semiconductor structure, comprising:
controlling a probe of an Atomic Force Microscope (AFM) to move a first distance from a preset reference position to a top surface of a semiconductor structure to be measured in a direction perpendicular to the top surface of the semiconductor structure to be measured;
controlling the probe to scan the top surface of the semiconductor structure to be measured while keeping the first distance in a direction parallel to the top surface of the semiconductor structure to be measured, and detecting amplitudes of the probe at respective scanning points on the top surface of the semiconductor structure to be measured; and
determining a Critical Dimension (CD) of the semiconductor structure to be measured according to the amplitudes of the probe at respective scanning points on the top surface of the semiconductor structure to be measured;
wherein the amplitudes of the probe are extents of oscillations of the probe.

2. The method of claim 1 , wherein before controlling the probe of the AFM to move the first distance from the preset reference position to the top surface of the semiconductor structure to be measured in the direction perpendicular to the top surface of the semiconductor structure to be measured, the method further comprises:
controlling the probe to move the first distance from the preset reference position to a top surface of a semiconductor reference sample in a direction perpendicular to the top surface of the semiconductor reference sample;
controlling the probe to scan the top surface of the semiconductor reference sample while keeping the first distance in a direction parallel to the top surface of the semiconductor reference sample, and detecting amplitudes of the probe at respective scanning points on the top surface of the semiconductor reference sample; and
determining a first amplitude threshold and a second amplitude threshold according to the amplitudes of the probe at respective scanning points on the top surface of the semiconductor reference sample.

3. The method of claim 2 , wherein determining the first amplitude threshold and the second amplitude threshold according to the amplitudes of the probe at respective scanning points on the top surface of the semiconductor reference sample comprises:
calculating the first amplitude threshold A 1 based on:
A i =Ā− 3σ; and

calculating the second amplitude threshold A 2 based on:
A 2 =Ā+ 3σ,

where

σ
=

∑

j
=
1

m

(

A
j

-

A
¯

)

2

m
-
1

,

where Ā represents an average value of the amplitudes of the probe at respective scanning points on the top surface of the semiconductor reference sample, A j represents the amplitude of the probe at a jth scanning point on the top surface of the semiconductor reference sample, and m represents a number of the scanning points of the probe on the top surface of the semiconductor reference sample.

4. The method of claim 3 , wherein determining the CD of the semiconductor structure to be measured according to the amplitudes of the probe at respective scanning points on the top surface of the semiconductor structure to be measured comprises:
when the amplitude at a present scanning point on the top surface of the semiconductor structure to be measured is greater than or equal to the first amplitude threshold and less than or equal to the second amplitude threshold, outputting a first identifier at the present scanning point;
when the amplitude at the present scanning point on the top surface of the semiconductor structure to be measured is greater than the second amplitude threshold, outputting a second identifier at the present scanning point; and
determining the CD of the semiconductor structure to be measured according to identifiers output when the top surface of the semiconductor structure to be measured is scanned.

5. The method of claim 4 , wherein determining the CD of the semiconductor structure to be measured according to the identifiers output when the top surface of the semiconductor structure to be measured is scanned comprises:
determining a first region where the first identifiers output when the top surface of the semiconductor structure to be measured is scanned are distributed and a second region where the second identifiers output when the top surface of the semiconductor structure to be measured is scanned are distributed; and
determining a boundary between the first region and the second region, and determining the CD of the semiconductor structure to be measured according to the boundary between the first region and the second region.

6. The method of claim 4 , further comprising:
when the amplitude at the present scanning point on the top surface of the semiconductor structure to be measured is less than the first amplitude threshold, outputting preset prompting information for prompting a tester that the top surface of the semiconductor structure to be measured is abnormal.

7. The method of claim 2 , wherein before controlling the probe to move the first distance from the preset reference position to the top surface of the semiconductor reference sample in the direction perpendicular to the top surface of the semiconductor reference sample, the method further comprises:
determining a first amplitude when the probe is at the preset reference position and a driving frequency is a target driving frequency value and a second amplitude when the probe moves the first distance in the direction perpendicular to the top surface of the semiconductor reference sample and the driving frequency is the target driving frequency value according to a relation between a curve of an amplitude and driving frequency of the probe in absence of an acting force and a curve of an amplitude and driving frequency of the probe in presence of the acting force;
adjusting the probe to the preset reference position, and adjusting the driving frequency of the probe to the target driving frequency value;
controlling the probe to move for multiple times from the preset reference position in the direction perpendicular to the top surface of the semiconductor reference sample, and recording movement distances that the probe moves every time and amplitudes of the probe after respective movements until the amplitude of the probe is the second amplitude; and
determining the first distance according to the recorded movement distances that the probe moves every time.

8. The method of claim 7 , wherein determining the first distance according to the recorded movement distan

Assignees

• Changxin Memory Tech Inc

Inventors

• Li Zheng

Classifications

• H10P74/203

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• G01Q10/06 Primary

  Circuits or algorithms therefor · CPC title

• G01Q20/00

  Monitoring the movement or position of the probe · CPC title

• G01Q10/02

  Coarse scanning or positioning · CPC title

• G01Q60/24 Primary

  AFM [Atomic Force Microscopy] or apparatus therefor, e.g. AFM probes · CPC title