JPS59117118A - Stage - Google Patents

Abstract

PURPOSE:To realize precision focusing by a method wherein a holding table which holds a photomask is provided on X-Y-Z-theta stages and this holding table is supported by fine displacement devices at a plurality of supporting points. CONSTITUTION:The Y stage 3, the X stage 4, the Z stage 22, the theta stage 23 and a mask holder (holding table) 24 are provided on a stage base 2. The photomask 1 is focused on the object lenses 9, 10 by the Z stage and its inclination is adjusted by the theta stage. Then the photomask 1 is scanned along the X-Y directions by the X-Y stages and tested by pattern sensors 11, 12 and a comparison circuit 15. At this time, each one of fine displacement devices 30, which are provided to a plurality of supporting points, is driven to be adjusted and the movement error of the X-Y stages and the discrepancy of focucing due to the processing error of the photomask are absorbed. Thus, by providing the fine displacement devices which have resolution of approximately 0.1mum, focusing of less than + or -0.2mum precision can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a stage that moves in X-Y-Z-〇, and is particularly used as a stage for semiconductor inspection equipment and processing equipment.

[Prior art]

The present invention is a semiconductor device with a high degree of threat and high precision.
Taking an automatic LSI photomask appearance inspection device as an example, the explanation will be given according to FIGS. 1 to 3. A photomask 1, which is an object to be inspected, is placed on an has been adjudicated.

The Y stage 3 and the X stage 4 are connected to a Y-axis moving section 5 and an X @ drive section 6 of an external drive device so that they can move in the Y direction and the X direction, respectively. The amount of movement of the XY stage is measured by a Y-axis length measuring device 7 and an X-axis length measuring device 8. Above the photomask 1, there is a left objective lens 9 that projects the pattern on the photomask and a stone objective lens 10.
02 lenses are arranged, and a right pattern sensor 11 and a right pattern sensor 12 are placed on the imaging plane of each objective lens.
is installed. The left pattern sensor 11, the left pattern signal binarization circuit 16, the right pattern sensor 12, the right pattern signal 21:=1 and the circuit 14 are connected, and the left pattern code 2Ilji conversion circuit 10 and the right pattern signal binarization The output signal of the circuit 14 is input to the signal comparison circuit 15 at a ratio of 2:9.
The output of the signal comparison circuit 15 is led to the microprocessor 18.

The Y-axis length measuring device 7 and the X-axis length measuring device 8 are connected to a coordinate length measuring circuit 16, and the coordinate length measuring circuit 16 is connected to a microprocessor 18.
is connected to. The microprocessor 1B is also connected to the XY drive control section 17 and can control the X-axis section 6, Y-axis, and drive section 5 through the XY drive control section 17.

In the conventional photomask inspection apparatus described above, the pattern of the photomask 1 shown in FIG. 2 is inspected by comparing two patterns. That is, since the LSI circuit patterns are arranged upside down and regularly on the photomask 1, the patterns at the same location on the adjacent chips 20 and 21 are compared and if there is a difference, it is determined to be a defect. The pattern of the chip 20 is converted into an image signal by the left objective lens 9 and the left pattern sensor 11, and the left pattern signal binarization circuit 16 converts it into a left digital image signal of logic level SS□//, 1λ1〃. The pattern of the chip 21 is the right objective lens 101
It is converted into an image signal by the right pattern sensor 12, and converted to a logic level SS O#1 by the right pattern signal binarization circuit 14.
This is the right digital image signal of 1S 11F. The left and right digital image signals described above are compared by a signal comparison circuit 15, and if there is a difference, a signal is sent to a microprocessor 18.

The microprocessor 18 determines whether the difference is due to a defect, and if so, outputs a message to the printer 19 indicating the defect. In the above inspection, the entire surface is sequentially inspected by moving the photomask 1 in the direction of the arrow in FIG. The microprocessor 18 controls the Y-axis moving unit 5,
Controls the X-axis moving section 6. The coordinate measurement circuit 16 measures the inspection position of the photomask 1, and if a defect is detected, the coordinates of the photomask are outputted to the printer 19 through the microprocessor 18. In some cases, the location of the location is recorded.

The above inspection device detects minute defects in the photomask 1, that is, 1
It is a device that detects defects of ~2 μm.For this reason, the inspection stage used in this type of device also has a high running degree and a core thickness that has a highly rigid structure. FIG. 6 shows a cross-sectional view of a conventional stage used as an inspection stage in the above-mentioned inspection apparatus. An XY stage consisting of a stationary stage 2, an X stage 3, and an X stage 4 that scans the photomask 1 in the XY direction, a Z stage 22 that aligns the pattern surface of the photomask 1 with the objective lens 9.10, and a Z stage 22 that places the photomask 1 on the XY stage. The θ stage 23,
A mask holder 24 that holds the photomask 1, and a mask holder 2 that is held by a leaf spring 25 and a spacer 26 in order to focus the mask being scanned on the objective lens 9.10.
4 from the focus holder that moves up and down by turning 2 screws once.
:+S rA colle. Further, inside the stage, left and right illumination lenses 28 and 29 are arranged to transmit and illuminate the photomask 1, and above the illumination section of the photomask 1, left and right objective lenses 9 and 10 are installed. This left and right objective lens 9
．． A nozzle is formed at the tip of each of the nozzles 10 and has a structure that allows air to be supplied. This detects the gap between the photomask 1 and the objective lens 9, 10 using the principle of air micromake.

The creation of the inspection stage in the above configuration will be explained.

When the operator places the photomask 1 on the mask holder 24, the Z stage 22 focuses the patterned surface of the photomask 1 onto the objective lens 9.10.
In order to correctly match the pattern with the feed of the XY stage, 23 θ stages are used to align the inclinations. Now, the inspection will start in the order of the arrows shown in the second arrow 1, but since the photomask 1 has undulations, errors caused by the linear movement of the XY stage, and machining errors of the mask holder 24 are also added, the It is necessary to focus the objective lens 9.10. During this inspection, the gears and pulls of the host mask and objective lens are detected using the principle of an air micrometer, and the screw 27 is
41. Perform inspection after driving and focusing; 41st.
pl g Is the intervening objective lens 9 showing the focusing method? L O (= This is in focus, right objective lens 1
0 focus plane? Screw 27 to focus on no.
Turn to tilt the mask holder 24. However, leaf spring 25
Since the mask holder 24 is tilted using the fulcrum, the left objective lens 9 will be out of focus by 91,1-fIL(+.
? When trying to point the needle to LQ, the right objective lens 10 is rRl.
−? Ro focus goes crazy. In this method, the θ stage must also be moved up and down to obtain a correct result.In this conventional method, defects of 1 to 2 μm are detected, so the focusing accuracy is only about 1 pm, which is less than the above. Even with the method, it was possible to detect defects using Sudejike scanning (7) while scanning the pin.

However, with the miniaturization of LSI patterns, A has become smaller than 1 μm.
It has become necessary to detect defects smaller than 0.05 μm, and even defects smaller than 0.05 μm. For this reason, the distance resolution I/lens, for example, NA・19, focusing method f〆02μm high'MI
It is necessary to use a Gi lens.

In the focusing device shown in Fig. 4 above, in order to focus the left and right objective lenses within 0.2 μm, the linear error of the XY stage should be 1 μm or less, and the machining error of the mask holder should be 1 μm or less. 2 stage and θ stage as well.
During the inspection, it must be completely static and the feed of the screw 27 must be 01 μm'8 degrees. Furthermore, the photomask must also be free of ridges 9. In reality, it is almost impossible to maintain such stage accuracy, and a stage equipped with a pin and twist device as described above has the disadvantage that it cannot be applied to a defect detection device of 1 μm or less.

[Purpose of the invention]

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the conventional kW, enable precise focusing with a high-resolution lens, and
The purpose is to provide a stage that can move in θ.

[Summary of the invention]

That is, in order to achieve the above object, the present invention provides a θ stage on the XY stage, a θ stage on the θ stage, and a holding stand for holding a photomask on the θ stage, and moves the holding stand slightly up and down at multiple locations. It is characterized by providing a plurality of minute displacement means.

[Embodiments of the invention]

The stages of the present invention will be explained below with reference to FIG. Fifth
The figure shows the conventional example shown in FIG. 3, except for the screw 27, with the addition of a minute displacement part 30, and the other configurations and operations are the same as those shown in FIG. 1.

Next, we will discuss the differences from the conventional device.

When the photomask is placed on the mask holder 24, the θ stage 22 moves it toward the focus of the objective lens. In order to correctly match the pattern of the photomask with the feed of the X and Y stages, the θ stage 26 is used to shade the inclination. Next, a plurality of minute displacement parts 30 arranged under the mask holder 24 are independently driven to perform focusing. The focusing method will be explained using FIG. 6. Is the amount of focus of the right objective lens 10 △? Rs Movement amount Z of the right micro-displacement device so that both of them are in focus at the same time when the out-of-focus of the left objective lens 9≠ is △2L R1 Movement iZL of the left micro-displacement device is ZR, = (i + -) △ 1R --△rL (4)S
S , I t ZL=-sweet △y R+ (1+ s ) △gL (5).

When the right objective lens 10 is inspecting the rightmost end of the photomask 1, the Y position of the X-Y stage is fyOl, and if the value of m at that time is mo, then
Arbitrary coordinate positions y and m are expressed as m=mo+(y-yo) (6).

Since mo and yo are constant values, if they are measured in advance, y and m will have a linear relationship expressed by (6), and therefore (4
), (5) Salel ZR,, Z L Ha△f'R
It can be found by measuring 1ΔfL, )·, S.

As the above-mentioned minute displacement means, an actuator with a resolution of about 01 μm is used, such as a minute displacement means applying pressure changes of a piezo element or a gamma digit body, or a kumite mechanism using a wedge action and a lever.

In addition, a plate spring is used as a means for supporting the mask holder, so that the mask holder does not shift when slightly moved.

As mentioned above, by placing a minute displacement device with a resolution of about 01 μIn on the stage that moves in xly, z, and θ, a high-resolution objective lens can be used, and
For photomasks with waviness of about m, it is now possible to create pins within ±0.2 μm.

〔Effect of the invention〕

According to the present invention described above, conventionally, in LSI photomask appearance, inspection equipment, etc., only the focus blueness of about 1 μm has been examined, and the limit is that it is possible to inspect defects of 1 to 2 μm 4 x 1. What was there, depth of focus 02 μnl
It is now possible to detect minute defects of less than -*-11 .mu.n using the high-elevation image lens.

Furthermore, the present invention is not limited to semi-four-way inspection, processing, and measurement equipment, but can also be used as a high-precision stage for general machining machines and production slip machines.

[Brief explanation of drawings]

Figure 1 is a ten-hole diagram showing an example of an LSI photomask inspection device, Figure 2 is a plan view showing an LSI 7i mask and its inspection order, and Figure 6 is the LSI photomask inspection device shown in Figure 1. 4 is a diagram illustrating conventional focus separation, FIG. 5 is a schematic diagram of the configuration of a stage according to an embodiment of the present invention, and FIG. 6 is a diagram showing a stage according to the present invention. FIG. 1...Photomask 2...Stage base 6...Y stage 4...X stage 22...X stage 23...・θ stage 24...Mask holder 25...Plate spring 26...Spacer 30...Minute displacement device Fig. 1 No.q No.8 O? figure

Claims (1)

[Claims] 1 means to horizontally move the observed object on a stage of a device that processes, inspects, and measures the observed object by observing the observed object with one or more imaging devices and moving the observed object. a holding table for holding an object to be observed on top of the means for rotating and moving horizontally; A stage comprising a plurality of minute displacement means for minutely moving the holding table up and down at a plurality of locations.