JPH08210985A - Detecting method for particle in film, and detecting device therefor - Google Patents

Abstract

PURPOSE: To improve the detecting sensitivity of fine particle (particle) dispersed in a film formed on a wafer. CONSTITUTION: A light L is incident on a transparent film 12 formed on the surface of a wafer 11, and advanced in the transparent film 12. At that time, the light L is incident from the end surface 12e of the transparent film 12 into the transparent film 12 at either one of the incident angle for advancing in the film substantially in parallel to the surface 12s of the transparent film 12 and the incident angle for advancing in the transparent film 12 while fully reflecting between the surface-side critical surface 12a and wafer-side critical surface 12b of the transparent film 12. The scattered light Ls caused by scattering the light L by a particle 31 contained in the transparent film 12 is detected, whereby the particle 31 in the transparent film 12 is measured. When the light L is emitted, the wafer 11 is rotated in the state where the surface is within a fixed surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting particles in a film and a detection apparatus therefor, which is used when controlling film formation quality in the manufacture of semiconductor devices.

[0002]

2. Description of the Related Art A CVD insulating film used for a semiconductor device is controlled in film quality and the number of particles on the film surface. In the conventional detection method, light is vertically incident on the wafer to be inspected, and the light scattered by the particles on the film surface is detected to measure the particles. At this time, the thickness of the film to be inspected is set so that the reflected light on the film surface and the reflected light on the wafer have the same phase.

[0003]

However, in a semiconductor device, not only particles on the film surface but also particles in the film cause defects. For example, particles in the film serve as a mask during etching back for flattening to generate a residue, and the protrusion of this residue causes a short circuit of the wiring. Even if the detection light is incident perpendicularly to the wafer surface as described above, scattered light is generated by particles in the film, but the light scattered in the film interferes with the reflected light on the wafer surface. Weakened by Therefore, although it is possible to detect a huge particle, it is difficult to detect a minute particle. In particular, since defects that cause problems with etchback when forming a planarization film are minute particles with a size of approximately 0.4 μm or less, it is required to detect particles in the film with high sensitivity. It

It is an object of the present invention to provide a method for detecting particles in a film, which is excellent in detecting fine particles in a film, and a detection device therefor.

[0005]

SUMMARY OF THE INVENTION The present invention provides a method for detecting particles in a film and an apparatus for detecting the same, which has been made to achieve the above object.

The detection method of particles in a film is a detection method in which a transparent film formed on the surface of a wafer is irradiated with light and scattered light due to particles contained in the transparent film is detected to measure the particles. Therefore, the light has an incident angle that travels in the film substantially parallel to the surface of the transparent film and an incident angle that travels in the film while being totally reflected between the surface side interface of the transparent film and the wafer side interface. Irradiation into the film from the end face of the transparent film at at least one of the incident angles.

The device for detecting particles in the film has the following configuration. That is, a stage on which a wafer on which a transparent film to be measured is formed is placed is provided, and a drive means for rotating the stage is connected to the stage. Furthermore, a light source that irradiates light in parallel with the surface of the transparent film is provided. A photodetector is installed on the wafer. Further, a measurement processor for measuring the particles in the transparent film based on the rotation angle of the stage and the signal from the photodetector is provided.

[0008]

In the above-mentioned method for detecting particles in a film, light is transmitted through the film substantially parallel to the surface of the transparent film while being totally reflected between the surface side interface of the transparent film and the wafer side interface. The light travels in the transparent film because the film is irradiated from the end surface of the transparent film at an incident angle of at least one of the incident angles traveling through the film. Therefore, when the transparent film contains particles, the light hits the particles and is scattered. Therefore, the particles in the transparent film are measured by detecting the scattered light on the surface side of the transparent film. Moreover, the irradiated light is not emitted to the outside from the surface side of the transparent film, except for being scattered by the particles in the transparent film. Therefore, scattered light due to the particles in the transparent film is easily detected on the surface side of the transparent film.

In the above-mentioned in-film particle detecting apparatus, since the driving means for rotating the stage in the circumferential direction of the wafer to be mounted is provided, the stage is rotated by the driving means and mounted on the stage. The wafer is also rotated. Moreover, since the light source for irradiating the light substantially parallel to the surface of the transparent film formed on the wafer is provided, the light source irradiates the light in one direction of the surface of the transparent film. For this reason,
Since the light is scanned over the entire surface of the transparent film by the rotation of the wafer, the light incident on the transparent film is scattered by the particles when the particles are present in the transparent film. Further, since the photodetector is provided above the optical path of the light traveling in the transparent film, the light scattered by the particles in the transparent film is detected by a part of this photodetector, and The scattered position and scattered light intensity are converted into signals. Since the measurement processor that measures the particles in the transparent film based on the rotation angle of the stage and the signal from the photodetector is provided, the position of the photodetector with respect to the wafer is calculated, and the transparent film is calculated. The position, number, particle size, etc. of particles existing in the plane are measured.

[0010]

Embodiments of the detection method of the present invention will be described with reference to the schematic view of FIG. In the figure, as an example, a method of making light incident from the end face side of the transparent film will be described.

As shown in the figure, a transparent film 12 is formed on the surface of the wafer 11. The transparent film 12 is formed by a film forming technique such as plasma CVD, sputtering, vapor deposition, and coating, and is made of a transparent film such as a silicon oxide film. The surface 12s of the transparent film 12
Angle of incidence substantially parallel to or the surface side interface 12 of the transparent film 12
Light L having an incident angle of total reflection between a and the wafer-side interface 12b is incident on the end surface 12e of the transparent film 12 into the film. In the figure, the light L incident in the state of total reflection is shown. The light L incident on the transparent film 12 is scattered by the particles 31 included in the film, and the scattered light L
Part of s is emitted from the surface side of the transparent film 12 to the outside.
The emitted scattered light Ls is detected by the photodetector 21, and the position, size and number of the particles 31 are measured.

In the above detection method, the wafer 1
1 is rotated with its surface lying within a certain plane. Therefore, the light L is applied to the entire transparent film 12.

In the method for detecting particles in the film, the transparent film 12 is used.
Of light L at an incident angle substantially parallel to the surface of the transparent film 12 and at least one of the incident angles of total reflection between the surface-side interface 12a and the wafer-side interface 12b of the transparent film 12. Since it enters the film from the end face 12e of the light, the light L traveling in the transparent film 12 is not emitted to the outside from the surface side of the transparent film 12 except that it is scattered only by the particles 31 in the film. Therefore, the scattered light Ls is detected on the front surface side of the transparent film 12.

When the wafer 11 is rotated, the light L is applied to the entire transparent film 12, so that the particles 31 can be measured over the entire transparent film 12. . When the wafer 11 is rotated and measured in this manner, the particles 31 existing on the straight line in the transparent film 12 can also be measured.

Next, a device for detecting particles in a film according to an embodiment of the present invention will be described with reference to the schematic configuration diagram of FIG. In this figure, the same reference numerals are given to the components as described in FIG. 1 above.

As shown in FIG. 2, a stage 41 on which the wafer 11 is placed is provided. A transparent film 12 is formed on the surface of the wafer 11. Further, the stage 41 is provided with drive means 42 for rotating the stage 41 in the arrow A direction, for example. The driving means 42 is, for example, a stepping motor. A light source 43 for irradiating the light L in a state where the light L travels in the transparent film 12 is provided. The light source 43 is a laser light oscillator, for example, a helium (He) -neon (Ne) laser oscillator.

On the optical path of the light L emitted from the light source 43 toward the transparent film 12, a first diaphragm 44 and a second diaphragm 45 are arranged as diaphragms. A light shield 46 is installed near the optical path and on the side periphery of the wafer 11 placed on the stage 41. The light shield 46 is arranged in a state where the light diffracted by the first and second diaphragms 44 and 45 and the reflected light when entering the transparent film 12 are not detected by the photodetector 21, for example, 3 from the edge of the wafer 11.
It covers about mm and is made of a light-shielding material.

Further, a photodetector 21 is installed above the optical path of the light L traveling in the transparent film 12. For example, the photodetector 21 is provided, for example, above the wafer 11 in the diameter direction. The photodetector 21 is, for example, a linear sensor in which a plurality of light receiving elements (not shown) are arranged in series. The rotation angle of the stage 41 is, for example, the drive means 42.
Of the particles 31 in the transparent film 12 based on the rotation angle signal Sa and the scattered light signal Ss received by the photodetector 21. A measurement processor 51 for measuring the quantity, position, etc. is installed.

The measurement processor 51 is, for example, an arithmetic unit 52.
And an image processing unit 53 and a display unit 54. Further, the rotation angle signal Sa is, for example, a rotation angle rotated from the predetermined position of the stage 41 in the mounting surface circumferential direction (for example, a direction in which the arrow A is positive), and the driving means 42 for obtaining the rotation angle.
Is indicated by the amount of rotation. The scattered light signal Ss is represented by the intensity distribution of the scattered light Ls detected by the photo detector 21.

The calculation unit 52 calculates the scattered light intensity distribution at the rotating position where the scattered light signal Ss is detected from the rotating angle signal Sa and the scattered light signal Ss, and the wafer 11 is calculated.
The distribution of scattered light intensity in the plane of the transparent film 12 formed on the surface of is obtained. Then, based on the distribution of scattered light within the surface of the transparent film 12 thus obtained, the transparent film 1 having a peak scattered light intensity
Assuming that the particle 31 exists at the position in 2, the particle 31
The position data and the number data of the particles 31 are obtained, and the diameter data of the particles 31 are obtained from the scattered light intensity.

The image processing unit 53 creates a map within the plane of the transparent film 12 based on the position data of the particles 31, the number data of the particles 31 and the diameter data of the particles 31. The display unit 54 displays the map 61 created by the image processing unit 53. Further, the measurement processor 51 may be capable of performing a totaling process such as classification of the number of particles for each particle size and creation of a map 61 for each particle size based on each data.

Although the detecting device 1 does not use a light collecting system when collecting the scattered light Ls by the particles 31,
By increasing the number of times of light collection, it is possible to accumulate the amount of light collection and supplement the detection sensitivity.

Further, in the detection device 1, it is difficult to make the light L completely parallel to the surface of the transparent film 12 incident. Therefore, when the incident light L travels in the transparent film 12, this transparent film 12 is made. The positions of the stage 41 and the light source 43 are determined in a state of proceeding with total internal reflection. As shown in FIG. 3, the total reflection condition is such that the total reflection angle is φ _C , the refractive index of the transparent film 12 formed on the surface of the wafer 11 is n ₁ , and the refractive index in the air is n ₂ ( It can be expressed by the formula 1). Note that hatching showing a cross section is omitted in this figure.

[0024]

[Equation 1] sin φ _C = n ₂ / n ₁ (1)

Therefore, the total reflection angle φ _C that satisfies the above equation (1) is determined. The surface-side interface 12a and the wafer-side interface 12b when the light L travels in the transparent film 12
When the incident angle φ on the transparent film 12 is larger than φ _C
The light L may be incident from the end surface 12e of the. Therefore, in order to make the light L incident on the end surface 12e of the transparent film 12 so as to obtain the incident angle φ, the inclination angle of the incident surface of the light L with respect to the surface 12s of the transparent film 12 is ψ, and the incident angle of the light L with respect to this incident surface is ψ. Is θ ₁ and its refraction angle is θ ₂ , the law of refraction and θ
_{From the} relation of ₂ = π-φ-ψ, it becomes as shown in equation (2).

[0026]

[Number 2] _{sinθ 1 = (n 2 / n} 1) sin (π-φ-ψ) ··· (2)

[0027] Thus, the incident angle theta ₁ to the transparent film 12 of the light L may be satisfied the expression (2), such that the incident angle to obtain the light becomes theta _1, stage described by FIG 2 The positional relationship between the wafer mounting surface of 41 and the light source 43 is set.

Next, a method of detecting particles in the film by using the above inspection device 1 will be described. In this description, refer to FIG. 2 for the configuration of the detection device 1, and FIG. 1 for the traveling state of the light L and the traveling state of the scattered light Ls in the transparent film 12.

In the detection device 1, the stage 41 is rotated in the arrow A direction by the driving means 42,
The wafer 11 mounted on the wafer also rotates in the same direction. Then, the light L from the light source 43 is applied to the end surface 12e of the transparent film 12 formed on the wafer 11 through the first and second diaphragms 44 and 45.
The light L travels in the transparent film 12 and scatters when the particles 31 in the transparent film 12 are irradiated with the scattered light Ls. The scattered light Ls is emitted to the outside from the surface side of the transparent film 12. At that time, the wafer 1 together with the stage 41
Since 1 is rotated, the light L is scanned over the entire transparent film 12. Therefore, the transparent film 12
The light L incident on the transparent film 1 is scattered by the particles 31 when the particles 31 exist in the transparent film 12.
The scattered light Ls is generated at the position where the particles 31 exist in 2.

Since the photodetector 21 is provided above the path of the light L transmitted through the transparent film 12, the scattered light Ls is detected by the photodetector 21 at the same time when the scattered light Ls is generated. . At that time, the scattered light Ls is detected by the photodetector 2
Since it is detected by a part of the light-receiving elements that form No. 1, the position of the light-receiving element that detects the scattered light Ls with respect to the photodetector 21 can be known. That is, since the light amounts detected by the individual light receiving elements are different, it can be seen that particles exist at the position below the light receiving element that has detected the strongest light amount. Thereby, the generation position of the scattered light Ls with respect to the photodetector 21 at the time of detecting the scattered light Ls is grasped, and the position and the scattered light intensity are converted into a signal.

Then, the measurement processor 51 obtains the position of the particles 31 on the surface of the transparent film 12 based on the rotation angle signal Sa of the stage 41 and the scattered light signal Ss from the photodetector 21. .

That is, the calculation unit 52 calculates the scattered light intensity distribution at the rotating position where the scattered light signal Ss is detected from the rotating angle signal Sa and the scattered light signal Ss.
The scattered light intensity distribution within the plane of the transparent film 12 is obtained. Then, based on the intensity distribution of the scattered light in the plane of the transparent film 12 thus obtained, the position data of the particles 31 and the number data of the particles 31 are obtained, assuming that the particles 31 exist at the position where the scattered light intensity has a peak. The diameter data of the particles 31 can be obtained from the scattered light intensity.

Then, the image processing unit 53 creates a map within the plane of the transparent film 12 based on the position data of the particles 31, the number data of the particles 31 and the diameter data of the particles 31. Then, the display unit 54 displays the map 61 created by the image processing unit 53. Further, the measurement processor 51 is
Based on each data, the total number of particles may be classified according to particle diameter, and the aggregation processing such as creation of the map 61 for each particle diameter may be performed.

In the detection device 1, since the first and second diaphragms 44 and 45 are installed on the optical path of the light L emitted from the light source 43, the light L can be easily radiated into the transparent film 12. It can be narrowed down. Further, since the light shield 46 is provided in the vicinity of the optical path and in the vicinity of the side circumference of the wafer 11, the light diffracted by the first and second diaphragms 44 and 45 and the reflected light when entering the transparent film 12 are shielded. To be Therefore, it becomes easy to detect the scattered light Ls.

Further, in the above detection device 1, the light source 43
In order to adjust the incident angle of the light L emitted from the optical axis, a reflection optical system 71 may be provided as an optical system for changing the incident angle in the optical path between the light source 43 and the wafer 11, as shown in FIG. Good. The reflection optical system 71 includes a first reflecting mirror 72 that reflects the light L from the light source 43 and a second reflecting mirror 72 that reflects the light L reflected by the first reflecting mirror 72 toward the transparent film 12 of the wafer 11.
And a reflecting mirror 73. The first reflecting mirror 72 is provided with a first driving section 74 for rotating it in the arrow A direction in the drawing, and the second reflecting mirror 73 is provided with a second driving section for rotating it in the arrow C direction in the drawing. 75 are provided. Further, in order to adjust the irradiation position of the light L on the transparent film 12, a drive unit (not shown) capable of moving the reflective optical system 71 in the optical path direction may be provided.

In the reflection optical system 71, the first and second drive
By driving the parts 74 and 75, the first and second reflecting mirrors
Rotation of 72 and 73 causes the light L to enter the transparent film 12.
Angle θ ₁Is adjusted.

[0037]

As described above, according to the method for detecting particles in the film of the present invention, the light incident on the transparent film travels in the transparent film unless scattered by the particles in the transparent film. The light emitted from the surface of the transparent film to the outside becomes scattered light due to the particles existing in the transparent film. Since the scattered light is detected, the particles in the transparent film can be measured.

According to the device for detecting particles in the film of the present invention, the light from the light source can travel in the transparent film except that the light is incident from the end face of the transparent film and scattered by the particles in the transparent film. Moreover, since the stage is rotated by the driving means, light can be scanned over the entire transparent film. Therefore, it becomes possible to inspect the presence of particles in the transparent film over the entire transparent film. Furthermore, since the photodetector is provided above the optical path of the light traveling in the transparent film,
Light scattered by particles in the transparent film can be detected.
Since the measurement processor that measures the particles in the transparent film based on the rotation angle of the stage and the signal of the scattered light obtained by the photodetector, the position, number, and particle size of the particles present in the transparent film are provided. Etc. can be measured.

[Brief description of drawings]

FIG. 1 is a schematic view of an embodiment relating to the detection method of the present invention.

FIG. 2 is a schematic configuration diagram of an embodiment relating to a detection device of the present invention.

FIG. 3 is an explanatory diagram of a light incident angle condition.

FIG. 4 is an explanatory diagram of a reflective optical system.

[Description of Reference Signs] 1 detection device 11 wafer 12 transparent film 12a surface side interface 12b wafer side interface 12e (transparent film 12) end face 12s (transparent film 12) surface 21 photodetector 31 particle 41 stage 42 driving means 43 light source 51 Measurement Processor L Light Ls Scattered Light

Claims (18)

[Claims] 1. A method for detecting in-film particles, which comprises measuring scattered particles produced by irradiating a transparent film formed on a wafer surface with light, the scattered light being generated by the particles contained in the transparent film. The incident angle of the light traveling in the transparent film substantially parallel to the surface of the transparent film, and the incident angle of total reflection in the transparent film between the surface side interface of the transparent film and the wafer side interface. A method for detecting particles in a film, characterized in that the particles enter the transparent film from an end face of the transparent film at an incident angle of at least one of the above. 2. The method for detecting in-film particles according to claim 1, wherein the wafer is rotated while the light is being irradiated while the wafer surface is within a certain plane. Detection method. 3. A stage on which a wafer on which a transparent film is formed is placed, a driving means for rotating the stage, a light source for irradiating light on the surface of the transparent film substantially in parallel, and the transparent film. A film comprising a photodetector provided above an optical path in the inside, and a measurement processor for measuring particles in the transparent film by a rotation angle of the stage and a signal from the photodetector. Medium particle detector. 4. The in-film particle detection device according to claim 3, wherein a diaphragm is provided on an optical path of the light emitted from the light source. 5. The in-film particle detection device according to claim 3, further comprising a light shield provided in the vicinity of the optical path of the light and on the side periphery of the wafer. apparatus. 6. The in-film particle detection device according to claim 4, wherein a light-shielding device is provided in the vicinity of the optical path of the light and on the side periphery of the wafer. apparatus. 7. The in-film particle detection device according to claim 3, wherein an incident angle of the light with respect to the transparent film is varied in an optical path of the light emitted from the light source, and reflective surfaces are substantially opposed to each other. An apparatus for detecting particles in a film, which is provided with a reflection optical system including a reflection mirror. 8. The in-film particle detection device according to claim 4, wherein an incident angle of the light with respect to the transparent film is varied in an optical path of the light emitted from the light source, and reflective surfaces are substantially opposed to each other. An apparatus for detecting particles in a film, which is provided with a reflection optical system including a reflection mirror. 9. The detection device for in-film particles according to claim 5, wherein an incident angle of the light with respect to the transparent film is varied in an optical path of light emitted from the light source, and reflective surfaces are substantially opposed to each other. An apparatus for detecting particles in a film, which is provided with a reflection optical system including a reflection mirror. 10. The in-film particle detection device according to claim 6, wherein an incident angle of the light with respect to the transparent film is varied in an optical path of the light emitted from the light source, and reflective surfaces are substantially opposed to each other. An apparatus for detecting particles in a film, which is provided with a reflection optical system including a reflection mirror. 11. The in-film particle detection device according to claim 3, wherein the photodetector is a linear sensor in which a plurality of light receiving elements are arranged in series. 12. The in-film particle detection device according to claim 4, wherein the photodetector is a linear sensor in which a plurality of light receiving elements are arranged in series. 13. The in-film particle detection device according to claim 5, wherein the photodetector is a linear sensor in which a plurality of light receiving elements are arranged in series. 14. The in-film particle detection device according to claim 6, wherein the photodetector is a linear sensor in which a plurality of light receiving elements are arranged in series. 15. The detection device for in-film particles according to claim 7, wherein the photodetector is a linear sensor in which a plurality of light receiving elements are arranged in series. 16. The in-film particle detection device according to claim 8, wherein the photodetector is a linear sensor in which a plurality of light receiving elements are arranged in series. 17. The in-film particle detection device according to claim 9, wherein the photodetector is a linear sensor in which a plurality of light receiving elements are arranged in series. 18. The in-film particle detection device according to claim 10, wherein the photodetector is a linear sensor in which a plurality of light receiving elements are arranged in series.