JPH0375056B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a surface foreign matter inspection device that can be used in vacuum and can be used in vacuum process equipment such as vacuum equipment for semiconductor manufacturing.

BACKGROUND ART For example, in semiconductor manufacturing technology, it is important to observe and inspect foreign substances such as dust particles attached to the surface of a substrate such as a wafer from the viewpoint of improving yield.

Conventionally used methods for inspecting foreign matter on the surface of a substrate include (1) a method that uses light such as a laser beam to detect the particle size of the foreign matter from the scattered light; (2) a method that uses a microscope. (3) There are methods such as observing the shape of foreign objects using a scanning electron microscope.

Among these, the light scattering method is widely used because it can be quickly inspected on the line, and among them, it has high detection sensitivity and can detect even the smallest particles.
A light source using a laser is used. Although these devices are commercially available as complete devices, it is necessary to add a separate inspection step during the manufacturing process, which results in a time penalty.

With the recent development of vacuum processes, there is a demand for incorporating a foreign substance inspection device into manufacturing equipment, and in particular, there is an increasing demand for incorporating it into vacuum process equipment and performing in-line measurements.

By the way, unlike conventional laser dust monitors that are used in the atmosphere, a vacuum window is always required when introducing a laser beam into a vacuum equipment, or when emitting light specularly reflected on a wafer out of a vacuum equipment. This causes problems such as light reflected at the vacuum window part raising the background.

On the other hand, it is known to use a Brieuster window in order to suppress the reflected light of the laser beam as low as possible.

However, if it is necessary to scan a surface such as a wafer, the Brieusta window is not suitable. This is because the Brieuster window is only effective at a certain angle of incidence, and if the angle deviates even slightly, the reflectance increases, so it cannot be used for laser scanning. In addition, in the case of a Brieusta window, a polarized laser beam is used, and the polarization plane of the laser beam must be adjusted to an angle unique to the Brieusta window, so the deflection angle must be adjusted when the laser is installed in the device. be.

Problems to be Solved by the Invention As described above, when a laser beam is introduced into a vacuum device, a Brieusta window is generally used as the vacuum window to suppress the reflectance. When installing, there is a problem that not only the deflection angle needs to be adjusted, but also the laser cannot be scanned. Therefore, it is possible to move the wafer along with the stage without scanning the laser, but moving the stage is impractical when considering incorporating it into an in-line device, and moving the stage also generates dust. It's scary and undesirable. Furthermore, a normal vacuum window has a large reflectance, resulting in a large background, making it impossible to detect small particles.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a surface foreign matter inspection device that solves the problem of background increase due to reflected light without using a Brewster window as a vacuum window, and that can be easily incorporated into a vacuum process line. be.

Means for Solving the Problems In order to achieve the above object, the surface foreign matter inspection device according to the present invention, which can be used in a vacuum, uses a vacuum for introducing a laser beam into a vacuum container containing an object to be inspected for foreign matter. A window and a vacuum window for guiding the laser beam specularly reflected on the object to be inspected in the vacuum container to the outside are provided, and the laser beam introduced onto the surface of the object to be inspected in the vacuum container is directed to the surface of the object to be inspected in the vacuum container. It has a laser scanner that scans the surface of the object to be inspected in at least one direction, and a detector arranged at a position where it can detect the laser beam diffusely reflected by foreign matter on the object to be inspected, and the vacuum window for introducing the laser beam; The device is characterized in that the vacuum window for guiding the laser beam is made of glass with an anti-reflection coating.

In the surface foreign matter inspection device of the present invention configured as described above, which can be used in a vacuum, the laser scanner can scan the surface of the substrate in the vacuum device in the X, Y directions or only in the X direction,
When scanning in both the X and Y directions, the object to be inspected does not move during the measurement. On the other hand, when scanning only in the X direction, the inspection can be carried out while sending the object to be inspected in the Y direction at an appropriate speed using an in-line conveyance system. A laser beam is introduced onto the surface of the object to be inspected inside the vacuum chamber through a vacuum window for introducing the laser beam provided in the vacuum container, and the laser beam scans the surface of the object to be inspected in the X and Y directions. If any foreign matter is present on the surface of the object to be inspected, the introduced laser beam will be specularly reflected on the object to be inspected and will be led out through the vacuum window for guiding the laser beam, as well as the foreign object. The portion of the laser beam that collides with the detector is diffusely reflected and enters the detector. Thereby, the detector detects foreign matter on the surface of the object to be inspected. In this case, a series of foreign object inspection operations can be performed while the object to be inspected is in the vacuum process line.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

The drawing shows the configuration of the surface foreign matter inspection device according to the present invention, 1 is a vacuum container, and this vacuum container 1 has Y
A movable table 2 that can move in a direction is provided, a substrate holder 3 is mounted on the movable table 2, and a substrate 4, which is an object to be inspected, is mounted on the movable table 2. The vacuum container 1 includes a vacuum window 5 for introducing a laser beam, which is provided at a position where the laser beam can be introduced into the substrate 4 at a predetermined angle of incidence, and a vacuum window 5 for introducing the laser beam into the substrate 4 through the vacuum window 5 for introducing the laser beam. A vacuum window 6 for guiding the laser beam is provided at a position where the laser beam is specularly reflected and proceeds.
Reference numeral 7 denotes a laser beam generation and introduction device attached to the laser beam introduction vacuum window 5, and includes a laser light source 7a and a scanner 7b that scans the laser beam from the laser light source 7a on the substrate 4 in the X and Y directions. . On the other hand, a photomultiplier tube 8 forming a detector forms a required angle with respect to a plane passing through the laser beam generation/introduction device 7, the vacuum window 5 for laser beam introduction, and the vacuum window 6 for laser beam derivation, and the photomultiplier tube 8 forms a vacuum vessel. It is attached to 1.
Any suitable type of detector 8 may be used, the output of which is connected, for example, to a computer device (not shown).

The vacuum window 5 for introducing the laser beam and the vacuum window 6 for guiding the laser beam are glass 5b, which is provided with an anti-reflection film sealed at the openings 5a, 6a, respectively.
6b.

In the illustrated apparatus configured as described above, a laser beam is first generated and scanned by the laser light source 7a and the scanner 7b of the laser beam generation/introduction device 7, and is passed through the vacuum window 5 for laser beam introduction onto the movable table 2. The substrate 4 is scanned in the X direction. If there is no foreign matter on the substrate 4 scanned by the laser beam, the laser beam is specularly reflected by the substrate 4 and exits the vacuum chamber 1 through the vacuum window 6 for guiding the laser beam. If there is a foreign object on the substrate, the portion of the laser beam that collides with the foreign object will be scattered, and this scattered light will be detected by the detector 8, thus making it possible to detect the foreign object on the substrate.

In the illustrated embodiment, the detector 8 may be located at any position as long as it can detect light diffusely reflected by foreign matter on the substrate. Further, the scanning operation by the scanner 7b and the movement of the substrate in the Y direction should be performed in synchronization. Further, in the illustrated embodiment, the scanner 7b scans the laser beam only in the X direction and inspects the substrate while moving it in the Y direction.
It may be configured to scan in both the X and Y directions, and the substrate may be kept stationary during inspection.

Effects of the Invention As described above, according to the present invention, a vacuum container for accommodating an object to be inspected for foreign substances is provided with a vacuum window for introducing a laser beam, and a laser beam specularly reflected on the object to be inspected in the vacuum container is provided. A laser scanner and a laser scanner, which are provided with a vacuum window for guiding the laser beam to the outside, and scan the laser beam introduced onto the surface of the object to be inspected in the vacuum container in at least one direction on the surface of the object to be inspected. In a surface foreign matter inspection device that can be used in a vacuum and has a detector placed at a position where it can detect the laser beam diffusely reflected by foreign matter on the inspection object, a vacuum window for introducing the laser beam and a vacuum window for guiding the laser beam are installed. Since it is made of glass with an anti-reflection coating, it is possible to reduce the amount of reflected light to 0.4%, compared to about 4% for regular glass vacuum windows. Ground can be significantly lowered. As a result, the minimum detectable particle size was approximately 2 μm when using a regular glass window, whereas
The device according to the invention can detect particle sizes down to 0.5 μm. Further, the device according to the present invention can be easily incorporated into an in-line vacuum process device, and the inspection process can be simplified.

[Brief explanation of drawings]

The drawing is a schematic diagram showing the configuration of an apparatus according to an embodiment of the present invention. In the figure, 1: vacuum container, 2: movable table, 4:
Substrate, 5: Vacuum window for laser beam introduction, 6: Vacuum window for laser beam extraction, 7: Laser beam generation and introduction device, 7a: Laser light source, 7b: Scanner.

Claims (1)

[Claims] 1. A vacuum container containing an object to be inspected for foreign matter is provided with a vacuum window for introducing a laser beam and a vacuum window for guiding the laser beam specularly reflected on the object to be inspected in the vacuum container to the outside. , a laser scanner that scans a laser beam introduced onto the surface of the object to be inspected in at least one direction on the surface of the object to be inspected, and a laser beam that is diffusely reflected by foreign matter on the object to be inspected can be detected. A surface foreign matter inspection device that can be used in a vacuum and has a detector placed at a certain position, characterized in that the vacuum window for introducing the laser beam and the vacuum window for leading the laser beam are made of glass with an antireflection film. A surface foreign matter inspection device that can be used in a vacuum.