JPH07105326B2 - Alignment device - Google Patents

Description

DETAILED DESCRIPTION [Overview] A positioning device used for an electron beam device using an electron beam such as an SEM and an electron beam exposure device.

The resolution is inferior to that of SEM, etc., but the wide field of view makes it easy to identify the position of the object.An optical system monitor is installed in the sample exchange chamber of the electron beam device, and the position of this optical system monitor is adjusted to After the desired point of the object such as the semiconductor wafer placed on the table is specified, the coordinates of the optical system monitor at that time are detected, and then the object such as the semiconductor wafer is put into the sample chamber. , The stage is automatically aligned with the position corresponding to the above coordinates, and as a result, the electron beam is automatically irradiated to a desired point on an object such as a semiconductor wafer. It is a positioning device.

[Industrial application field]

The present invention relates to a positioning device used in an electron beam device that uses an electron beam such as an SEM and an electron beam exposure device.

[Conventional technology]

Electron beam devices that use electron beams, such as SEM and electron beam exposure devices, have high resolution, because they are not affected by Franhofer diffraction.
It is highly accurate and extremely excellent.

[Problems to be solved by the invention]

Since the electron beam device has a high resolution and thus has a very narrow field of view and is invisible, it is not easy to align an object such as a semiconductor wafer with the reference point of the electron beam. In particular, it is extremely difficult to align an object such as a semiconductor wafer after loading it into the sample chamber.

An object of the present invention is to eliminate this drawback, and it is an object of the present invention to provide an alignment apparatus capable of aligning an object such as a semiconductor wafer with a reference point of an electron beam.

[Means for solving problems]

The means adopted by the present invention to achieve the above object is provided in the sample exchange chamber 2, can move along the surface of the sample table 22, and can be used for a semiconductor wafer or the like placed on the sample table 22. An optical system monitor 21 for monitoring the object 5, an object coordinate detecting means 3 for detecting coordinates representing the position of the optical system monitor 21, and a coordinate provided by the object coordinate detecting means 3 provided in the sample chamber 11. That is, the alignment device is configured with the alignment means 4 for aligning the position on the object 5 corresponding to the above with the predetermined position in the sample chamber.

However, the sample stage provided in the sample exchange chamber and the stage provided in the sample chamber are supposed to take positions corresponding to each other, but some position errors are difficult to avoid in the meantime,
It is advantageous to provide means for correcting this.

[Action]

In the present invention, the resolution is inferior to that of SEM, etc., but the field of view is wide, so that it is easy to identify the position of the object. Then, the desired point of the object placed on the sample table is specified, the coordinates of the optical system monitor at that time are detected, and after the object is put in the sample chamber, the stage is The position is automatically adjusted to the position corresponding to the above coordinates, and as a result, the electron beam is automatically irradiated to a desired point on the object.

〔Example〕

An alignment apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

See FIG. 1. In the figure, 1 is an electron beam device such as SEM, to which a sample chamber 11 is attached.

2 is a sample exchange chamber, on which a sample table on which the wafer 5 is placed
22 and an optical system monitor 21 that moves along the surface of the sample table 22 and monitors a desired point on the wafer 5 are attached. This optical system monitor 21 is a telescope for visually observing a desired point on the wafer 5.
211 and servo system that moves this telescope 211 in XY directions
It consists of 212. The optical system monitor 21 is the sample exchange room 2
It is provided so as to face the sample table 22 with a transparent partition wall 23 in between.

Reference numeral 3 denotes an object coordinate detecting means, which is means for detecting the XY coordinates of the point to which the servo system 212 has moved. Even if the machine of the object coordinate detecting means 3 follows the servo system 212,
Further, the detection value of a separate position sensor provided in the telescope 211 may be followed. In addition, the reference point of the sample table 22 is used as the origin of the coordinates, and the origin of the coordinates is used as a reference to measure X.
-It is realistic to use the Y coordinate value.

Reference numeral 4 denotes a positioning means for positioning the stage 111 provided in the sample chamber 11 at a position corresponding to the coordinate value detected by the object coordinate detecting means 3 described above, and automatically aligns with the servo system 41. It comprises a control system 42. The servo system 41 moves the stage 111 in the XY directions based on a command from the automatic control system 42. Further, the automatic control system 42 may be any mechanism as long as the stage 111 is aligned with the position corresponding to the coordinate value detected by the object coordinate detecting means 3 described above. Means 3
When the coordinate value detected by (0, 0) is aligned with the reference position (0, 0), the coordinate value detected by the object coordinate detecting means 3 is (A, B).
At this time, it is realistic to invert the sign of the coordinate value detected by the object coordinate detecting means 3 and use it as the atomic command information so that the stage 111 is aligned with (-A, -B). Is.

Although the position of the sample table 22 and the stage 111 in the sample chamber 11 are supposed to correspond to each other, some position errors (offset error, pitch error, etc.) are difficult to avoid. Is preferably corrected. In order to realize this position error correction, the fixed error may be moved fixedly by moving the stage reference point by a distance corresponding to this fixed error, but the variation error changes the correction amount as the wafer 5 moves. It is necessary to provide means for detecting this correction amount. Since this is complicated, a simple method such as a table lookup method may be used.

The speed command information is given based on the deviation between the position command information corrected as described above and the position information detected by the stage position detector 43. The speed command information and the servo system 41 are given.
The torque information is given on the basis of the deviation from the speed information, and the torque is given by the servo system 41 on the basis of this torque information to realize the movement of the stage 111.

〔The invention's effect〕

In the alignment device configured as described above, the resolution is lower than that of the electron beam device, but the field of view is large, and the desired position of the object such as a semiconductor wafer is specified by using an optical system monitor. Since the stage can be aligned to the position corresponding to the specified position,
By using this electron beam alignment apparatus, it is possible to automatically irradiate a desired position on an object such as a semiconductor wafer with an electron beam.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a positioning device according to an embodiment of the present invention. 1 ... Electron beam device, 111 ... Stage, 11 ... Sample chamber, 2 ... Sample exchange chamber, 21 ... Optical system monitor, 211 ... Telescope, 212 ... Servo system, 22 ... Sample stand, 23 ...... Transparent partition wall, 3 …… Object coordinate detection means, 4 …… Alignment means, 41 …… Servo system, 42 …… Automatic control system, 43 …… Stage position detector, 5 …… Object (wafer) .

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01L 21/66 C 7630-4M

Claims (2)

[Claims] 1. A sample table (2) provided in a sample exchange chamber (2).
2) can be moved along the surface of the sample table (2
2) An optical system monitor (21) for monitoring the object (5) placed on it, an object coordinate detecting means (3) for detecting coordinates representing the position of the optical system monitor (21), and a sample chamber Positioning means (11) for aligning a position on the object (5) corresponding to the coordinates detected by the object coordinate detecting means (3) with a predetermined position in the sample chamber ( 4) A positioning device comprising: 2. The position error correcting means for correcting the position error of the sample stage (22) is added to the coordinates detected by the object coordinate detecting means (3). The alignment device according to item 1.