JPH0247859B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a comparison type inspection device that inspects an object to be inspected while comparing it to a reference object, and particularly relates to an inspection device in which each object is provided with an automatic focusing mechanism. .

Photomasks used in the photolithography process, which is one of the manufacturing processes for semiconductor devices, are used to form patterns on semiconductor wafers, so they must be rigorously inspected for minute defects and foreign objects. be. In such inspections, a method is often used in which a good mask is generally used as a reference mask, and a mask to be inspected (inspected mask) is compared with this reference mask. FIG. 1 shows a conventional device for performing this type of inspection, in which a reference mask 1 and a mask to be inspected 2 are provided independently on a common Z table 3.
It is placed on XYθ tables 4 and 5. Also,
Each XYθ table 4, 5 has an automatic focus mechanism 6,
7 is installed, and the masks 1 and 2 are moved up and down to align the focus with respect to the inspection objective lenses 8 and 9. The inspection objective lenses 8 and 9 can magnify and observe the opposing parts of the reference mask 1 and the mask to be inspected 2 by the action of the XYθ tables 4 and 5, and the pattern shape observed by each objective lens 8 and 9 can be By comparing the values, defects and foreign substances in the mask 2 to be inspected can be inspected. Further, at this time, the automatic focusing mechanisms 6 and 7 operate independently to focus the masks 1 and 2 on the objective lenses 8 and 9, respectively.

However, in this conventional inspection device, the automatic focusing mechanisms 6 and 7 act independently when aligning the focus position of each mask 1 and 2, so the efficiency of automatic focusing work is poor, and the focus position of each mask 1 and 2 is Since the focus is aligned to each of the objective lenses 8 and 9, there is a problem that the focus alignment accuracy is low when looking at the inspection apparatus as a whole.

Therefore, an object of the present invention is to provide a comparative inspection device that can streamline the automatic focusing operation and perform more accurate focusing.

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

FIG. 2 shows an embodiment of the present invention as a mask inspection device, which is equipped with a relatively large XYθ table 10. This XYθ table 1
A first automatic focusing mechanism 12 that operates in cooperation with one objective lens 11 placed above the table is disposed above the 0, and a support stand 13 is disposed on this first automatic focusing mechanism 12. It is attached to support the reference mask 1 horizontally. The objective lens 11 is disposed above the reference mask 1 so that the pattern of the reference mask can be viewed in an enlarged manner. On the other hand, a small XYθ table 14 is placed on the first autofocus mechanism 12 at a position adjacent to the support base 13, and a second autofocus mechanism 15 is further disposed on this XYθ table 14. Mask to be inspected 2
is being set. An objective lens 16 is disposed above the mask 2 to be inspected so that the pattern of the mask 2 to be inspected can be viewed in an enlarged manner. In addition,
It is preferable that the objective lenses 11 and 16 are configured as part of an automatic pattern recognition device, and it is possible to automatically detect whether the patterns recognized through the objective lenses 11 and 16 are different. In addition, each of the above
The XYθ tables 10 and 14 are controlled by a control section not shown.

According to the above configuration, first, the XYθ table 10
moves in X, Y, and θ to position a predetermined portion of the reference mask 1 corresponding to the objective lens 11, and causes the objective lens 11 to recognize the pattern of the portion. At this time,
The first automatic focusing mechanism 1 cooperates with the objective lens 11.
2 is activated, and the reference mask 1 is moved up and down together with the support stand 13 to focus. Next, this time a small
The XYθ table 14 moves in the
position to correspond to Of course, this predetermined portion is a portion (pattern) that coincides with the predetermined portion of the reference mask 1 described above, and as a result, each of the objective lenses 11 and 16 corresponds to the corresponding pattern of the reference mask 1 and the mask to be inspected 2, respectively. The mask 2 to be inspected is inspected for quality by performing recognition and comparing the results. At this time, the mask to be inspected 2
Focusing with respect to the objective lens 16 is performed by the second automatic focusing mechanism 15 cooperating with the objective lens 16 and moving the mask 2 to be inspected up and down. That is, since the heights of the support base 13 and the XYθ table 14 are approximately equal, the reference mask 1 and the mask to be inspected 2 are at approximately the same height. Therefore, when the reference mask 1 is focused, the mask to be inspected 2 is Although almost a good focusing state is achieved, since the first automatic focusing mechanism 12 only focuses on the reference mask 1, the second automatic focusing mechanism 15 compensates for the positional deviation between both masks 1 and 2. By correcting this, the mask 2 to be inspected is focused. This streamlines automatic focusing work and enables more accurate focusing.

Note that the positions of the reference mask and the mask to be inspected may be exchanged, and the mask to be inspected may be placed on the first automatic focusing mechanism, and the reference mask may be placed on the second automatic focusing mechanism.

As described above, according to the apparatus of the present invention, the first and second objective lenses are provided correspondingly to the reference pattern and the pattern to be inspected, and the first and second objective lenses are provided to correspond to the reference pattern and the pattern to be inspected, respectively. a first automatic focus that simultaneously changes the relative distance to the second objective lens and focuses either the reference pattern or the pattern to be inspected on either the first or second objective lens; In order to focus on the other of the reference pattern and the pattern to be inspected, the distance between the mechanism and the other of the first and second objective lenses is changed by the first automatic focusing mechanism. 1st and 2nd
The second automatic focusing mechanism adjusts the relative distance between the objective lens and the other of the reference pattern and the pattern to be inspected to focus the automatic focusing. This has the effect of streamlining the work and enabling more accurate focusing.

[Brief explanation of the drawing]

FIG. 1 is a front configuration diagram of a conventional device, and FIG. 2 is a front configuration diagram of the device of the present invention. 1...Reference mask, 2...Target mask, 10
...XYθ table, 11 ... Objective lens, 12
...First automatic focus mechanism, 14...XYθ table, 15...Second automatic focus mechanism, 16...Objective lens.

Claims (1)

[Scope of Claims] 1. A comparison type inspection device that inspects a pattern to be inspected by observing a reference pattern and a pattern to be inspected and comparing the two,
Relative distances between first and second objective lenses provided corresponding to the reference pattern and the pattern to be inspected, respectively, and the first and second objective lenses to the reference pattern and the pattern to be inspected. a first automatic focusing mechanism that simultaneously changes the reference pattern and the pattern to be inspected and focuses one of the first and second objective lenses; the first and second objective lenses in order to focus on the other one of the reference pattern and the pattern to be inspected whose distance to the other one of the first and second objective lenses has been changed by A comparison type inspection device comprising: a second automatic focusing mechanism that adjusts the relative distance between one of the reference pattern and the other of the reference pattern and the pattern to be inspected to focus. 2. Claim 1, wherein the first automatic focusing mechanism focuses on the reference pattern, and the second automatic focusing mechanism focuses on the pattern to be inspected. Comparative inspection device as described. 3. The comparative inspection apparatus according to claim 1 or 2, wherein the reference pattern and the pattern to be inspected are composed of a mask for photolithography. 4. A first moving table that simultaneously moves the reference pattern and the pattern to be inspected, and a second moving table that allows adjustment of the relative positions of the reference pattern and the pattern to be inspected. Claims 1 to 3 of the claims
Comparison type inspection device according to any of paragraphs. 5. The comparative inspection apparatus according to any one of claims 1 to 4, wherein the second moving table is provided on the first moving table. 6. The comparative inspection apparatus according to claim 4 or 5, wherein the first moving table and the second moving table are tables movable in the X, Y, and θ directions. . 7. Claim 4, wherein the first automatic focusing mechanism is installed on the first moving table, and the second automatic focusing mechanism is installed on the second moving table. 7. The comparative inspection device according to any one of items 6 to 6.