JP2563589B2 - Foreign matter inspection device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foreign matter inspection for detecting foreign matter on a semiconductor wafer.

2. Description of the Related Art In recent years, the pattern of elements formed on a semiconductor wafer has been miniaturized due to high integration of integrated circuit technology. Therefore, the presence of foreign matter on the semiconductor wafer hinders the formation of these fine patterns and reduces the yield of integrated circuits. Therefore, it is necessary to inspect fine foreign matters on the semiconductor wafer and manage the number, size and distribution of these foreign matters. Conventionally, a so-called laser scattering method has been used for detecting foreign matter on a semiconductor wafer, in which a laser light source is incident on the semiconductor wafer and when the foreign matter is present on the semiconductor wafer, the scattering of the laser light is detected.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the conventional foreign substance inspection method by laser scattering, since a light source of a single wavelength is used as a light source, scattered light causes interference due to the size of the foreign substance, and there is a region where the ability to discriminate the size of the foreign substance is poor. The size of foreign matter is large at 632.8 nm of the existing He-Ne laser, which is the most commonly used laser light source.
It was not possible to detect a very fine foreign substance of 0.2 μmφ or less with high accuracy. Further, since the scattering of light is used, when various films are present on the semiconductor wafer, the scattering state on the surface of the semiconductor wafer varies depending on each film, and accurate measurement cannot be performed.

The present invention uses a change in electrostatic capacity for foreign matter detection to increase the size of extremely fine foreign matter to large foreign matter without being affected by the interference that occurs when light is used or the reflectance of the semiconductor wafer surface. It is a foreign matter inspection device that detects with high accuracy.

Means for Solving the Problems The present invention provides a capacitance by a first electrode also serving as a table on which a semiconductor wafer to be measured is placed and a flat plate-type second electrode provided on the semiconductor wafer. When detecting a foreign substance on the semiconductor wafer by a detector for detecting and a change in electrostatic capacitance between the semiconductor wafer and the detector, the second electrode is fixed and the semiconductor wafer is placed. Or a means for scanning the semiconductor wafer in the XY direction by moving the first electrode, or one horizontal direction while rotating the first electrode for detecting the electrostatic capacitance. It is provided with a means for spirally scanning the semiconductor wafer by moving it to the action. According to the foreign matter inspection apparatus of the present invention, it is easy to obtain a high accuracy in the measurement of the capacitance, and Reduction along with can detect very fine foreign material because of the linearity, the size of the foreign object can be detected better linearity. Further, it becomes possible to inspect foreign matter when various films are formed on a semiconductor wafer, which is difficult with the conventional method using light, and a highly sensitive and highly accurate foreign matter inspecting apparatus can be realized.

Practical Example Hereinafter, an example in which the electrostatic capacity detector is fixed and the semiconductor wafer is moved to scan the wafer will be described based on the apparatus configuration diagram shown in FIG.

In FIG. 1, a capacitance detector 1 is mounted on the tip of a support arm 2 and fixed to 100 to 200 μm on a semiconductor wafer 3. On the other hand, the semiconductor wafer 3 is vacuum-adsorbed on the conductive support 4, and the support 4 moves in the X direction by the X-axis drive unit 6 while rotating itself by the step motor 5. This causes the capacitance detector to scan the wafer in a spiral manner. If a foreign substance is present between the electrostatic capacitance detector and the semiconductor wafer, the electrostatic capacitance between the electrostatic capacitance detector and the wafer changes as compared with the case where there is no foreign substance, and the foreign substance is detected by this change. The rotation of the wafer keeps the linear velocity between the capacitance detector and the wafer constant, so that the rotation speed becomes faster near the inner circumference than near the outer circumference. On the other hand, in the X direction, about 20 rotations are made for each rotation of the wafer.
Move in μm steps. In this way, the semiconductor wafer is scanned. On the other hand, the capacitance change obtained by the capacitance detector becomes information on the size of the foreign matter through the capacitance calculator 7 and the particle size converter 8. At the same time, the scanning position information is transmitted to the position calculator 9 from the step motor and the X-axis drive unit, and the position and size information of the foreign matter is displayed together on the display unit 10. A particle size histogram of the foreign material is displayed.

EFFECTS OF THE INVENTION As described above, according to the foreign matter inspection apparatus of the present invention, it is possible to inspect foreign matter on a semiconductor wafer with high sensitivity and high accuracy.

[Brief description of drawings]

FIG. 1 is a structural diagram of a foreign matter inspection apparatus according to the present invention. 1 ... Capacitance detector, 2 ... Capacitance detector support arm, 3 ... Semiconductor wafer, 4 ... Support stand, 5 ... Step motor, 6 ... X-axis drive unit, 7 ... Static Capacitance calculator, 8 ... Particle size calculator, 9 ... Position calculator, 10 ... Display, 11 ... Shaft, 12 ... Foreign matter.

Claims (2)

(57) [Claims] 1. A detector for detecting an electrostatic capacitance by a first electrode also serving as a table on which a semiconductor wafer to be measured is mounted and a flat plate type second electrode placed on the semiconductor wafer. When detecting foreign matter on the semiconductor wafer due to a change in capacitance between the semiconductor wafer and the detector, the second electrode is fixed, and the first electrode on which the semiconductor wafer is mounted is fixed. And a means for scanning the semiconductor wafer in the XY directions by moving the foreign matter inspection apparatus. 2. A means for spirally scanning the semiconductor wafer by moving the first electrode for detecting electrostatic capacitance in one horizontal direction while rotating the first electrode. The foreign matter inspection apparatus according to item 1.