JPH04109108A - Foreign object inspecting device - Google Patents

Abstract

PURPOSE:To perform correction in response to various thin films by determining the grain size of grains with a grain size calculating circuit according to the grain size-scattered light intensity characteristic curve generated by a correction curve generating circuit based on the data from a scattered light detector. CONSTITUTION:A film thickness meter 2 measures the thickness of a thin film formed on a semiconductor wafer 1 and measures the reflection coefficient of the thin film, and it sends the data of the film thickness and reflection coefficient to a correction curve generating circuit 4. A scattered light detector 3 irradiates the light to the wafer 1 and detects the intensity of the scattered light generated on the wafer 1. The data are sent to a grain size calculating circuit 5. The circuit 4 receives the data of the film thickness and reflection coefficient and performs light scatter simulation to generate a grain size- scattered light intensity characteristic curve for the sensitivity correction of the detector 3 in response to the thickness of the thin film of the wafer 1. The scattered light intensity detected by the detector 3 is corrected based on this curve, thus a stable foreign object inspection can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention (Industrial Application Field) The present invention relates to a foreign matter inspection device for inspecting foreign matter, such as the particle size of particles attached to a semiconductor wafer.

(Prior Art) In the manufacturing process of semiconductor wafers, inspection is performed for foreign matter adhering to the surface of the ware 1 that causes defects in the semiconductor.

In this inspection, the semiconductor wafer is irradiated with light, and the particle size of the foreign matter is determined using the scattered light generated by the foreign matter adhering to the wafer. Incidentally, the scattered light from foreign objects varies greatly depending on the characteristics such as the thickness, material, and refractive index of the thin film formed on the surface of the semiconductor wafer. For this reason, it is necessary to perform correction according to characteristics such as the thickness, material, and refractive index of the thin film.

This correction is performed by changing the sensitivity of the scattered light detector depending on the thickness and material of the thin film, or by memorizing the particle size-scattered light intensity characteristic curve for each condition in the case of film thickness and multilayer. There is.

However, the method of changing the sensitivity of the scattered light detector cannot be applied at all when the scattered light intensity does not change depending on the film thickness or material. Furthermore, it is difficult to store the method of storing each particle size-scattered light intensity characteristic curve in order to be able to apply the method to all types of thin films.

(Problems to be Solved by the Invention) As described above, corrections have been made based on film thickness, material, etc., but in any case, it is difficult to make corrections based on various thin films and materials.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a foreign matter inspection device that can perform corrections according to conditions such as various thin films and materials.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a foreign matter inspection device for inspecting particles attached to a thin film for particle size and foreign matter. a scattered light detector to detect; and a correction curve creation means for creating a particle size-scattered light intensity characteristic curve for correcting the output of the scattered light detector according to the characteristics such as the thickness and refractive index of the thin film. and a foreign matter inspection means for receiving the scattered light intensity detected by the scattered light detector and inspecting the foreign matter according to the particle size-scattered light intensity characteristic curve.

(Function) With the provision of such means, the particle size-scattered light intensity characteristic curve for correction of the scattered light detector can be created by the correction curve creation means based on the characteristics such as the film thickness, material, and refractive index of the thin film. By correcting the scattered light intensity detected by the scattered light detector based on the particle size-scattered light intensity characteristic curve created by the foreign material inspection means, stable foreign material inspection can be performed.

(Embodiment 11 FIJ) Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of an attached particle inspection device. An uninspected semiconductor wafer (1) is placed below a film thickness meter (2) by a loader device (not shown), and then placed under a scattered light detector (3).
The semiconductor wafer is then unloaded as a test flow semiconductor wafer.

The film thickness meter (2) applies Fourier spectroscopy, and has the function of obtaining a spectrum by Fourier transforming the interference curve (ink ferrogram) obtained by a beam interferometer, and obtaining the film thickness from the linear component of this spectrum. It has become.

The film thickness meter (2) has the function of measuring the thickness of a thin film formed on the surface of the semiconductor wafer (1) and detecting the refractive index of the thin film. In addition, a scattered light detector (
3) has a function of measuring the light intensity of scattered light generated when light is incident on the semiconductor wafer (1). The film thickness and refractive index data measured by the film thickness meter (2) are sent to a correction curve creation circuit (4).

This correction curve creation circuit (4) receives the film thickness and refractive index data measured by the film thickness meter (2), and executes a light scattering simulation based on these data to determine the thin film of the semiconductor wafer (1). It has a function of creating a particle size-scattered light intensity characteristic curve for correcting the scattered light detector according to the film thickness.

Further, the data of the scattered light intensity detected by the scattered light detector (3) is sent to a particle size calculation circuit (5) which is a foreign matter inspection means. This particle size calculation circuit (5) receives data from the scattered light detector (3) and calculates the particle size of the particles according to the particle size-scattered light intensity characteristic curve created by the correction curve creation circuit (4). It has the functionality you are looking for.

A display circuit (6) is connected to this particle size calculation circuit (5), so that the particle size of the particles determined by the particle size calculation circuit (5) is displayed.

Next, the operation of the apparatus configured as described above will be explained.

The semiconductor wafer (1) is measured by a film thickness meter (2) using a loader device.
is placed below. The film thickness meter (2) measures the thickness of the thin film formed on the semiconductor wafer (1) placed below, and also measures the reflectance of the thin film, and uses these film thickness and refractive index data to create a correction curve. Send to (4).

Next, the semiconductor wafer (1) is placed below the scattered light detector (3) by a loader device. This scattered light detector (3
) irradiates light onto the semiconductor wafer (1) and detects the intensity of scattered light generated on the semiconductor wafer (1). This scattered light intensity data is sent to a particle size calculation circuit (5).

The correction curve creation circuit (4) receives each data of film thickness and reflectance, executes a light scattering simulation based on these data, and detects a scattered light detector (4) according to the film thickness of the thin film of the semiconductor wafer (1). 3) Create a particle size-scattered light intensity characteristic curve for sensitivity correction.

Here, light scattering simulation will be explained. Adhering particles 1 slightly above the semiconductor wafer (1) shown in FIG.
The light scattered by 0 is determined from Mie's scattering theory. (α,
Amplitude ST of light in the scattered light detector (3) in the β) direction
(α, β) are direct scattering light detectors from attached particles (3)
The light SD is considered to be a combination of the light SD that reaches the point 1, and the light SR that is reflected by the -degree semiconductor tube (1) and then enters the detector (3). Since SR is the product of the scattered light SR in the angular direction (α゛, β-) before reflection multiplied by the reflectance R (β) at the semiconductor wafer (1), the light amplitude ST (α, β) is expressed as in equation (1).

Generally, reflectance is a function of angle of incidence. As expressed by the above equation (1), amplitude reflectance is used and angular dependence is taken into consideration, so-called phase jump is also taken into consideration.

So (α, β), SR (α′, β) in equation (1) above
') into the coordinate system used in calculations based on Mie scattering theory, respectively, and S(θ.

φD) and S(θR1φR). Since it is sufficient to consider the combination of waves at points P and P' shown in FIG. 3, the above equation can be rewritten as equation (2).

Here, h is the distance between the semiconductor wafer (1) and the attached particles 10.

On the other hand, in the case of the optical system shown in Fig. 4, the scattered light detector (3)
The intensity PA of the scattered light incident on is expressed by equation (3).

p-J ′oJ II 1 <θ, φ) S1nθd
θdφ...(3) And the intensity I(θ, φ) per unit solid angle is the (4th
) is expressed by the formula.

2, where Io is the illuminance of the incident light.

Therefore, S(θ, φ) in equation (4) is replaced by S(θp,
By substituting φD) and S(θR2φR), the light intensity of the scattered light can be determined. Then, by executing a light scattering simulation in which the particle size of the particles is changed in the same manner as described above, the particle size-scattered light intensity characteristic is determined.

When the particle size-scattered light intensity characteristic is determined in this way,
A particle size calculation circuit (5) receives data from the scattered light detector (3) and calculates the particle size of the particles 10 based on this data according to a particle size-scattered light intensity characteristic curve. This particle size is then displayed on a display circuit (6).

The inspected semiconductor wafer (1) is unloaded, and the next semiconductor wafer (1) is loaded below the film thickness gauge (2).

After this, if the type of thin film formed on the uninspected semiconductor wafer (1) is the same, the semiconductor wafer (1) is placed below the scattered light detector (3>) and the adhered particles 10 are inspected. It will be done.

In this way, in the above embodiment, a light scattering simulation is executed based on the film thickness etc. measured by the film thickness meter (2), and the particle size-scattered light intensity for correction of the scattered light detector (3) is calculated. A characteristic curve is created, and the particle size is determined according to the particle size-scattered light intensity characteristic curve based on the scattered light intensity detected by the scattered light detector (3). The particle size-scattered light intensity characteristic curve of the sensitivity correction for the scattered light detector (3) can be obtained in accordance with the measurement, and the particle size of adhered particles on the semiconductor wafer (1) on which various thin films have been formed can be measured with high precision. can.

Note that the present invention is not limited to the above-mentioned embodiment, and may be modified without departing from the spirit thereof. For example, the correction curve creation circuit (4) receives data from the film thickness meter (2) and creates a particle size-scattered light intensity characteristic curve, but if data regarding the thin film is known in advance, the data is corrected. It may also be directly input to the curve creation circuit (4). Further, in this embodiment, a film thickness meter using Fourier spectroscopy was used, but a film thickness meter using other methods such as an ellipsometer may be used.

Further, other simulation methods may be used for the light scattering simulation.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide a foreign matter inspection device that can perform corrections according to various thin films.

[Brief explanation of the drawing]

1 to 4 are diagrams for explaining one embodiment of a foreign matter inspection device according to the present invention, in which FIG. 1 is a configuration diagram and FIG. 2 is a diagram showing a particle model on a semiconductor wafer 1. 3 is a schematic diagram showing the combination of the direct light and the light reflected by the semiconductor sea urchin 71, and FIG. 4 is a diagram showing the optical system for the scattered light detector. 1... Semiconductor sea urchin/%, 2... Film thickness meter, 3... Scattered light detector, 4... Correction curve creation circuit, 5... Particle size calculation circuit, 6... Display circuit . Applicant's agent Patent attorney Takehiko Suzue Figure 1 2'rl! J

Claims (1)

[Claims] A foreign matter inspection device that inspects foreign matter such as the particle size of particles attached to a thin film includes a scattered light detector that detects scattered light from particles attached to the thin film, and a scattered light detector that detects scattered light from particles attached to the thin film, and a correction curve creation means for creating a particle size-scattered light intensity characteristic curve for correcting the output of the scattered light detector according to the characteristics; 1. A foreign matter inspection device comprising a foreign matter inspection means for inspecting foreign matter according to a diameter-scattered light intensity characteristic curve.