Shape measuring device using frequency scanning interferometer

• US 9,835,444 B2
• Filed: 05/20/2014
• Issued: 12/05/2017
• Est. Priority Date: 05/20/2013
• Status: Active Grant

• Current Assignee: Koh Young Technology Inc.
• Original Assignee: Koh Young Technology Inc.
• Inventors: Ser, Jang-Il, Kim, Hong-Ki
• Primary Examiner(s): Chowdhury, Tarifur
• Assistant Examiner(s): Cook, Jonathon
• Application Number:
  US14/892,330
• Publication Number:
  US 20160109227A1
• Time in Patent Office: 1,295 Days
• Field of Search: 356503, 356513, 356515
• CPC Class Codes: G01B 11/0608 Height gauges
• CPC Class Codes: G01B 11/2441 using interferometry
• CPC Class Codes: G01B 2210/56 Measuring geometric parameters of semiconductor structures, e.g. profile, critical dimensions or trench depth
• CPC Class Codes: G01B 9/02 Interferometers
• CPC Class Codes: G01B 9/02002 using two or more frequencies
• CPC Class Codes: G01N 2021/95646 Soldering

Abstract

A shape measuring device includes a light source unit, a light splitting unit, a reference mirror, a light receiving unit and a processing unit. The light source unit generates light and can change the wavelength of the light. The light splitting unit splits the light generated from the light source unit into at least a reference light and a measurement light. The light receiving unit receives the reference light which is reflected by the reference mirror so as to form a reference light path, and the measurement light which is reflected by a light-transmitting target object formed on a substrate so as to form a measurement light path. The processing unit calculates the shape of the measurement argent object based on an interference change resulting from a wavelength change of the light between the reference light and the measurement light received by the light receiving unit.

Claims

1. A shape measuring device, comprising:

a light source unit configured to generate a light and change a wavelength of the light;

a light splitting unit configured to split the light generated from the light source unit into at least a reference light and a measurement light;

a reference mirror configured to reflect the reference light;

a light receiving unit configured to receive the reference light reflected by the reference mirror so as to form a reference light path and to receive the measurement light reflected by a measurement target object formed on a material having an irregular reflection property so as to form a measurement light path, the measurement target object being formed in a lumpy shape with a peak point and a slant surface, and the measurement target object including a first area having the peak point, and a second area having at least a portion of the slant surface; and

a processing unit configured to calculate a relative height of the second area based on a first light path difference between a reference measurement light path and a first measurement light path and to calculate a shape of the measurement target object based on the relative height of the second area,

wherein the reference measurement light path is formed by a reference measurement light,

wherein the reference measurement light is reflected at an exposed portion of an upper surface of the material,

wherein the first measurement light path is formed by a first measurement light,

wherein the first measurement light is refractively transmitted through the second area of the measurement target object along an incidence path, irregularly reflected at a covered portion of the upper surface of the material, and then returned backward through the incidence path, and

wherein the covered portion is covered with the measurement target object.

2. The shape measuring device of claim 1,

wherein the material comprises a substrate including a base substrate, a non-conductive layer having the exposed portion, and a conductive layer having the covered portion, and

wherein the processing unit is configured:

to calculate an absolute height of the first area based on a second light path difference between the reference measurement light path and a second measurement light path and a third light path difference between the reference measurement light path and a third measurement light path; and

to calculate the shape of the measurement target object by matching the absolute height of the first area and the relative height of the second area,

wherein the second measurement light path is formed by a second measurement light,

wherein the second measurement light is reflected at the first area of the measurement target object,

wherein the third measurement light path is formed by a third measurement light, and

wherein the third measurement is transmitted through the first area of the measurement target object, and reflected at the covered portion.

3. A shape measuring method in a frequency scanning interferometer including a light source unit capable of changing a wavelength of a light, a reference mirror, a beam splitter, a light receiving unit and a processing unit, the shape measuring method comprising:

splitting, by the reference mirror, the light generated from the light source unit into a first light having a first light path;

splitting, by the beam splitter, the light generated from the light source unit into a second light different from the first light and having a second light path, by the second light being reflected by a measurement target object formed on a material having an irregular reflection property, the measurement target object being formed in a lumpy shape with a peak point and a slant surface, and the measurement target object including a first area having the peak point, and a second area having at least a portion of the slant surface;

calculating, by the processing unit, a relative height of the second area based on a first light path difference between a reference measurement light path and a first measurement light path; and

calculating, by the processing unit, a shape of the measurement target object based on the relative height of the second area,

wherein the reference measurement light path is formed by a reference measurement light,

wherein the reference measurement light is reflected at an exposed portion of an upper surface of the material,

wherein the exposed portion is not covered with the measurement target object,

wherein the first measurement light path is formed by a first measurement light,

wherein the first measurement light is refractively transmitted through the second area of the measurement target object along an incidence path, irregularly reflected at a covered portion of the upper surface of the material, and then returned backward through the incidence path; and

wherein the covered portion is covered with the measurement target object.

4. The shape measuring method of claim 3, wherein calculating the shape of the measurement target object comprises:

calculating, by the processing unit, an absolute height of the first area based on a second light path difference between the reference measurement light path and a second measurement light path a third light path difference between the reference measurement light path and a third measurement light path; and

calculating, by the processing unit, the shape of the measurement target object by matching the absolute height of the first area and the relative height of the second area,

wherein the second measurement light path is formed by a second measurement light,

wherein the second measurement light is reflected at the first area of the measurement target object,

wherein the third measurement light path is formed by a third measurement light, and

wherein the third measurement light is transmitted through the first area of the measurement target object and reflected at the covered portion.

5. A shape measuring device, comprising:

a light source unit configured to generate a light and change a wavelength of the light;

a first light path changing unit configured to enable a first light, which is a portion of the light generated from the light source unit, to have a first light path;

a second light path changing unit configured to enable a second light, which is at least a portion of the light generated from the light source unit and is different from the first light, to have a second light path by being reflected by a measurement target object formed on a material having an irregular reflection property, the measurement target object being formed in a lumpy shape with a peak point and a slant surface, and the measurement target object including a first area including the peak point, and a second area including at least a portion of the slant surface;

a light receiving unit configured to receive the first light passing through the first light path and the second light passing through the second light path; and

a processing unit configured to calculate a relative height of the second area based on a first light path difference between a reference measurement light path and a first measurement light path, and to calculate a shape of the measurement target object based on the relative height of the second area,

wherein the reference measurement light path is formed by a reference measurement light,

wherein the reference measurement light is reflected at an exposed portion of an upper surface of the material,

wherein the first measurement light path is formed by a first measurement light,

wherein the first measurement light is refractively transmitted through the second area of the measurement target object along an incidence path, irregularly reflected at a covered portion of the upper surface of the material, and then returned backward through the incidence path, and

wherein the covered portion is covered with the measurement target object.

6. The shape measuring device of claim 5,

wherein the material comprises a substrate including a base substrate, a non-conductive layer having the exposed portion, and a conductive layer having the covered portion, and

wherein the processing unit is configured:

to calculate an absolute height of the first area based on a second light path difference between the reference measurement light path and a second measurement light path, and a third light path difference between the reference measurement light path and a third measurement light path, and to calculate the shape of the measurement target object by matching the absolute height of the first area and the relative height of the second area,

wherein the second measurement light path is formed by a second measurement light,

wherein the second measurement light is reflected at the first area of the measurement target object,

wherein the third measurement light path is formed by a third measurement light, and

wherein the third measurement Light is transmitted through the first area of the measurement target object and reflected at the covered portion.