JPH08159979A - Surface inspecting apparatus - Google Patents

Abstract

PURPOSE: To provide a surface inspecting apparatus in which the surface can be inspected by automatically totally reflecting merely by placing an element to be inspected on a stage and driving the apparatus. CONSTITUTION: The surface inspecting apparatus comprises a light source 16 for inspecting a surface by emitting a light to the surface of an element 1 to be inspected as to totally reflect, a detector 18 for inspecting the surface to detect the reflected light reflected on the surface of the element 1 to be inspected, a refractive index measuring means 13 for detecting the refractive index of the element 1 to be inspected, and a process controller 10 for controlling the positions of the source 16 and the detector 18 based on the totally reflecting angle to obtain the angle from the refractive index obtained by the means 13. The means 13 has a light source 12 for measuring the index to emit the light toward the surface of the element 1 to be inspected and a detector 13 for measuring the index to detect the light reflected on the surface of the element 1 to be detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface inspection apparatus, and more particularly to a technique effective when applied to the surface inspection of a semiconductor substrate (wafer) in the manufacture of semiconductor devices.

[0002]

2. Description of the Related Art A semiconductor substrate is used in the manufacture of semiconductor devices such as ICs and LSIs, but with the miniaturization of circuit patterns, it is important to detect the state of the wafer surface.
That is, the surface of the wafer is, for example, published in Press Journal, Inc., "Monthly Semiconductor World", March 1986.
Monthly issue, issued February 15, the same year, as described in "Application of light scattering to surface defect inspection" on pages 109-115, there are many defects due to particle (foreign matter) adhesion, pits or scratches, spikes, and other irregularities. Exists. As an inspection means for inspecting such foreign matter, as shown in the same document, foreign matter inspection means by detecting scattered light of the light irradiated on the wafer surface, and "Electronic Material" issued by the Industrial Research Committee, August 1991 issue, There is known a wafer surface analysis means utilizing total reflection described in P32 to P36, issued on August 1, the same year.

[0003]

The total reflection fluorescent X-ray analysis method is, as described in the above-mentioned document, (1) information on the vicinity of the surface can be obtained, and (2) a general fluorescent X-ray analysis method. It has the features that it is not easily affected by coexisting elements, which is always a problem, and that (3) scattering from the inside of the sample that causes background is less likely to occur.

A conventional surface inspection apparatus utilizing total reflection is
After recognizing the total reflection angle of the object to be inspected, the surface inspection is performed by setting the positions of the light source for surface inspection and the detector for surface inspection. However, in the conventional surface inspection apparatus, it is difficult to set the positions of the surface inspection light source and the surface inspection detector when the total reflection angle of the substance on the surface of the inspection object is not known.

It is an object of the present invention to provide a surface inspection apparatus capable of automatically performing surface inspection by total reflection simply by placing an inspection object on a stage and driving the apparatus.

The above and other objects and novel features of the present invention will be apparent from the description of the present specification and the accompanying drawings.

[0007]

The outline of the representative ones of the inventions disclosed in the present application will be briefly described as follows. That is, the surface inspection apparatus of the present invention includes a surface inspection light source that emits light so as to cause total reflection on the surface of the inspection object, and a surface inspection detection device that detects reflected light reflected on the surface of the inspection object. And a refractive index measuring means for detecting the refractive index of the object to be inspected, and the total reflection angle is obtained from the refractive index obtained by the refractive index measuring means. And a processing / control device for controlling the positions of the light source for surface inspection and the detector for surface inspection based on the above. The surface inspection light source and the surface inspection detector are arranged so that movement can be controlled along a rail extending in an arc shape attached to a dome arranged above a stage on which an object to be inspected is mounted. There is. Further, the refractive index measuring means comprises a refractive index measuring light source for irradiating the surface of the object to be inspected with light, and a refractive index measuring detector for detecting light reflected on the surface of the object to be inspected, and It is fixed to the dome.

[0008]

According to the above means, the surface inspection apparatus of the present invention automatically measures the refractive index of the surface of the inspection object when the inspection object is placed on the stage and the apparatus is driven. The total reflection angle is obtained, and the position of the light source for surface inspection and the position of the detector for surface inspection can be controlled to perform surface inspection by total reflection, so total reflection is possible without knowing the refractive index or total reflection angle of the surface of the object to be inspected. Surface inspection by use becomes possible.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 is a schematic cross-sectional view showing a main part of a surface inspection apparatus according to an embodiment of the present invention, FIG. 2 is a schematic plan view showing the same main part, and FIG. 3 is an outline of a support part for supporting a surface inspection light source. FIG. 4 is a schematic sectional view showing the same, FIG.
FIG. 3 is a block diagram showing a functional configuration of the surface inspection apparatus of this embodiment.

The surface inspection apparatus of this embodiment has a stage 2 on which an object to be inspected 1 such as a semiconductor substrate (wafer) is placed. The stage 2 is composed of an X table 4 which is moved by driving a motor 3 in a plane X direction and a Y table 6 which is moved by driving a motor 5 in a plane Y direction. The stage 2 is controlled by the processing / control device 10.

On the other hand, a hemispherical dome 11 is arranged above the stage 2. A refractive index measuring light source 12 and a refractive index measuring detector 13 are arranged on the ceiling surface of the dome 11. Light is emitted from the refractive index measuring light source 12 toward the inspection object 1. The light reflected by the surface of the inspection object 1 is detected by the refractive index measuring detector 13 and the refractive index of the surface of the inspection object 1 is measured. The refractive index measurement light source 12 and the refractive index measurement detector 13 are arranged in a positional relationship as shown in FIG.

On the other hand, an arcuate rail 15 is arranged so as to be attached to the ceiling surface of the dome 11. A light source support device 17 to which a light source 16 for surface inspection is attached and a detector support device 19 to which a detector 18 for surface inspection is attached are attached to the rail 15. The light source supporting device 17 and the detector supporting device 19 are the same except for the light source 16 for surface inspection and the detector 18 for surface inspection.

The light source support device 17 has a structure as shown in FIGS. That is, the rail 15 is
For example, as shown in FIG. 4, the cross section has an I-shaped structure, and the wheel 20 is rotatably fitted in the recess of the I-shaped structure. The wheel 20 has a U-shaped housing 21
Supported by. The housing 21 covers the inside of the rail 15 having an I-shaped structure. A rack 22 is fixed to the inner surface of the rail 15 so as to be attached thereto. A pinion 23 is attached to the rack 22 so as to mesh with each other. The pinion 23 is fixed to a rotary shaft 25 of a motor 24 attached to the outside of the housing 21. Therefore, the light source support device 17 moves up along the rail 15 by the forward rotation of the motor 24, and the light source support device 17 moves down along the rail 15 by the reverse rotation.

A support plate 26 is attached to the housing 21, and a surface inspection light source 16 is attached to the support plate 26. Since the detector support device 19 has the same structure as the light source support device 17 as described above, as shown in FIG. 1, the names and symbols of the parts other than the surface inspection detector 18 are the light source support devices. Same as device 17.

Next, the control system will be described. FIG. 5 is a block diagram showing a functional configuration of the surface inspection apparatus of this embodiment, 10 is a processing / control apparatus, 30 is an instruction input unit, and 13 is
Is a refractive index measurement detector, 2 is a stage, 31 is a surface inspection light source system, 32 is a surface inspection detection system, 33 is an information output device, and 34 is an auxiliary storage device. The processing / control device 1
Reference numeral 0 denotes a computer, which controls the stage 2, the surface inspection light source system 31, and the surface inspection detection system 32, and the surface of the inspection object (wafer) 1 based on the information from the refractive index measurement detector 13. The total reflection angle θ of the substance (film) is calculated, the position control of the surface inspection light source system 31 and the surface inspection detection system 32 is performed, and the surface state of the wafer 1 is detected in the total reflection detection state. There is. Further, the stage 2 is controlled by the processing / control device 10, and the surface of the entire surface of the wafer 1 to be placed is inspected. The detection information of the surface is output from the information output device 33 and stored in the auxiliary storage device 34.

From the refractive index n detected by the refractive index measuring detector 13, the total reflection angle θ is obtained by the following equation.

[0017]

## EQU00001 ## .theta. = Sin-1 (1 / n) ... (1) In such a surface inspection apparatus, foreign matter, pits, spikes, etc. due to particles in the wafer 1 placed on the stage 2 The presence or absence of abnormalities and the abnormal distribution of are detected. In this case, even if the measurer does not know the refractive index of the surface of the wafer 1 or the total reflection angle, the surface inspection apparatus of the present embodiment automatically measures the refractive index and determines the total reflection angle. Then, surface inspection such as foreign matter inspection is performed in the state of total reflection.

That is, when the wafer 1 is placed on the stage 2 and a work start is input from the instruction input section 30,
The surface of the wafer 1 is irradiated with light, for example, laser light of 300 to 400 nm from the light source 12 for measuring the refractive index. This laser light is reflected by the surface of the wafer 1, and the reflected light is detected by the refractive index measuring detector 13, and the refractive index is measured. For example, the refractive index is 1.45 for a SiO2 film,
In the case of a SiN film, it becomes 2.00. A commercially available device is used as the refractive index measuring detector 13. Refractive index measuring detector 1
The measurement information of 3 is sent to the processing / control device 10. In the processing / control device 10, the calculation unit calculates the total reflection angle θ.
Is required. The processing / control device 10 controls the motor 24 in the light source support device 17 and the detector support device 19 from the total reflection angle θ to cause the surface inspection light source 16 to operate.
The position of the surface inspection detector 18 is controlled, and the surface inspection detector 18 is set to detect the totally reflected light. The light source 16 for surface inspection is, for example, 300 to 400.
It is composed of a semiconductor laser that emits laser light having a wavelength of nm.

Next, after the surface inspection light source 16 is set to a position where total reflection occurs, the surface of the wafer 1 is inspected. During this inspection, the stage 2 is controlled to move in the plane XY directions,
The entire surface of the wafer 1 is scanned. Surface inspection information is
The information is output by the information output device 33 and stored in the auxiliary storage device 34.

According to the surface inspection apparatus of the present embodiment, the refractive index of the inspection object 1 placed on the stage 2 is automatically measured.

According to the surface inspection apparatus of the present embodiment, the refractive index of the inspection object 1 placed on the stage 2 is automatically measured and the total reflection angle θ is automatically obtained.

According to the surface inspection apparatus of this embodiment, the light source 16 for surface inspection and the detector 18 for surface inspection are automatically set in position with respect to the object 1 to be inspected mounted on the stage 2, It is set so that the inspection detector 18 can detect the totally reflected light.

According to the surface inspection apparatus of the present embodiment, the surface inspection of the inspection object 1 placed on the stage 2 is automatically performed by the detection by the total reflected light.

Although the invention made by the present inventor has been specifically described based on the embodiments, the invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say. For example,
In the above-described embodiment, an optical sensor is attached instead of the surface inspection detector 18 so that the light intensity is kept constant to detect the degree of change in the applied voltage of the surface inspection light source 16 and perform the surface inspection. Even if it is performed, highly accurate detection is possible. That is, the light intensity (Po) of the optical sensor is the same as the inspection object 1 on the stage 2 and a dummy product having no foreign matter or the inspection object 1 is not placed (blank state).
) Is detected. After that, the inspection object 1 is placed on the stage 2, the light intensity P in the optical sensor is detected, and the output of the light source 16 for surface inspection is controlled so that the light intensity P becomes Po. The more foreign matter and the like are present on the surface of the object to be inspected 1, the light intensity P decreases, so the surface inspection light source 16
The voltage applied to is increased. Therefore, the presence of foreign matter and the state of foreign matter distribution are known from the change in the voltage applied to the surface inspection light source 16.

As another device, a light source whose wavelength can be continuously changed is provided, the refractive index and the film thickness are measured, the wavelength reflected on the surface is calculated, and the foreign matter may be inspected by the wavelength. This example is a general apparatus that does not rely on total reflection for foreign matter inspection.

[0026]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows. According to the surface inspection apparatus of the present invention, the surface inspection by total reflection can be automatically performed by placing the inspection object on the stage and driving the apparatus. Therefore, the refractive index and the total reflection angle of the inspection object can be determined. Surface inspection by total internal reflection can be performed without knowing it.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a main part of a surface inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic plan view showing a main part of the surface inspection apparatus according to the present embodiment.

FIG. 3 is a schematic diagram showing an outline of a support portion that supports a light source for surface inspection in the surface inspection apparatus according to the present embodiment.

FIG. 4 is a schematic cross-sectional view showing an outline of a support portion that supports a surface inspection light source in the surface inspection apparatus according to the present embodiment.

FIG. 5 is a block diagram showing a functional configuration of the surface inspection apparatus of this embodiment.

[Explanation of symbols]

1 ... Object to be inspected, 2 ... Stage, 3 ... Motor, 4 ... X table, 5 ... Motor, 6 ... Y table, 10 ... Processing / control device, 11 ... Dome, 12 ... Refractive index measuring light source, 13 ...
Refractive index measuring detector, 15 ... Rail, 16 ... Surface inspection light source, 17 ... Light source supporting device, 18 ... Surface inspection detector,
19 ... Detector support device, 20 ... Wheels, 21 ... Housing, 22 ... Rack, 23 ... Pinion, 24 ... Motor, 2
5 ... Rotating shaft, 26 ... Support plate, 30 ... Instruction input unit, 31 ...
Surface inspection light source system, 32 ... Surface inspection detection system, 33 ... Information output device, 34 ... Auxiliary storage device.

Claims (3)

[Claims] 1. A surface inspection light source for irradiating light on a surface of an object to be inspected so as to cause total reflection, and a surface inspection detector for detecting reflected light reflected on the surface of the object to be inspected. A surface inspection apparatus, wherein the refractive index measuring means for detecting the refractive index of the object to be inspected, and the total reflection angle from the refractive index obtained by the refractive index measuring means and the surface based on the total reflection angle A surface inspection apparatus having a processing / control device for controlling the positions of an inspection light source and a surface inspection detector. 2. The surface inspection light source and the surface inspection detector are movable and controllable along a circular arc-shaped rail attached to a dome arranged above a stage on which an object to be inspected is mounted. The surface inspection apparatus according to claim 1, wherein the surface inspection apparatus is provided. 3. The refractive index measuring means comprises a refractive index measuring light source for irradiating the surface of the object to be inspected with light, and a refractive index measuring detector for detecting the light reflected by the surface of the object to be inspected. The surface inspection apparatus according to claim 1, wherein the surface inspection apparatus is fixed to the dome.