KR100755108B1 - Equipment for measuring overlay of semiconductor and method for measuring - Google Patents

Abstract

Equipment and a method for measuring overlay mark of a semiconductor device are provided to reduce overlay measurement time of a wafer by measuring four overlay marks in one shot region at the same time. A measuring unit(100) is installed at an end of an arm(40) including a Z-shaft stage to measure two or more overlay mark at one shot region at the same time. The measuring unit is comprised of plural moving arm units(110) and a camera unit(120). The moving arm units move horizontally along alignment position of the overlay mark. The camera unit including a lens is installed an end of the each moving arm. The moving arm is comprised of a motor, a lead screw, a first arm, and a second arm. The lead screw is rotated from the motor. The first arm is connected to the lead screw to be rotated and move straightly. The second arm is connected to the first arm through a bearing to move straightly.

Description

OVERLAY OF SEMICONDUCTOR AND METHOD FOR MEASURING}

1 is a schematic side view of a conventional overlay mark measuring apparatus,

2 is a view showing a wafer in which nine shot regions are formed on a wafer according to the related art.

3 is a view showing a position in which the overlay mark of the bar shape according to the prior art is disposed in the shot area of the photomask,

4 is a perspective view of an overlay mark measuring apparatus of a semiconductor device according to the present invention;

5 is a cross-sectional view of the movable arm portion according to the present invention.

<Description of the symbols for the main parts of the drawings>

10: base plate 20: XYT axis stage

30: pillar 40: arm

42: Z axis stage 60: shot area

100: measuring means 110: moving arm

111: motor 112: lead screw

113, 115: 1st, 2nd arm 114: bearing

120: camera portion 122: lens

The present invention relates to an overlay mark measuring device and a measuring method of a semiconductor device, and more particularly, to an overlay mark measuring device and a measuring method of a semiconductor device capable of measuring two or more overlay marks at a time during overlay measurement in a photolithography process. It is about.

Generally, in order to manufacture a semiconductor chip, a layer is formed by forming a circuit in a stacked manner, which is formed by photolithography, photolithography, and photolithography. It is implemented by the process. That is, the photolithography process is a patterning process in which a desired pattern formed on a mask is implanted onto a substrate on which an actual semiconductor chip is made through photoresist coating, exposure, and development.

At present, it is common to repeat the patterning process for the same substrate to manufacture a semiconductor device. Most of these patterning processes use a mask suitable for each patterning process. Therefore, in the current semiconductor device manufacturing process, whether or not it is possible to satisfactorily realize a pattern of successive layers in a horizontal and vertical alignment has become an important issue as semiconductor devices are integrated.

Currently, the integration of DRAM and logic devices has reached a design rule of 0.15 micrometers (μm) to control overlay as well as patterning in terms of photolithography. Doing so also faces technical limitations.

Overlay refers to the numerical display of the alignment between the layers implemented in the previous process and the layers formed in the current process. In a typical semiconductor manufacturing process, the measured overlay value is exposed to an exposure such as a scanner or stepper. By feeding back the equipment, the degree of overlap between the bottom and top layers is improved.

In the photolithography process, which is one of the semiconductor manufacturing processes, the shape of the pattern actually formed on the wafer is greatly affected by the change in the leveling value generated during exposure. As semiconductor devices become finer, the possibility of change is increasing.

In order to effectively cope with such a possibility of change, it is necessary to keep the leveling value at an optimal state during exposure.

Here, most of the photolithography process uses an optical technology equipped with a lens, and such a lens generates a shift that is different in accuracy depending on the shape and size of an actual pattern. This can cause misalignment.

Therefore, in the related art, after performing the exposure step, the overlay measurement process for comparing and measuring the pattern alignment degree and how much the actual pattern formed on the wafer is aligned with the reference pattern formed on the mask is performed, which is performed by the overlay measurement facility. do.

1 is a schematic side view of a conventional overlay mark measuring apparatus.

As shown in the drawing, the base plate 10 and the XYT axis stage 20 capable of shifting the tilt of the wafer seated on the base plate 10, such as the movement of the X axis or the Y axis, are provided. ) Is provided with a vertical pillar 30, an arm 40 including a Z-axis stage 42 in the orthogonal direction at the end of the pillar 30, and overlay measurement at the end of the arm 40 An optical camera unit 50 is installed.

Looking at the overlay mark measurement by the above measurement equipment, Figure 2 is a view showing a wafer in which nine shot areas are formed on the wafer according to the prior art, Figure 3 is a bar-shaped overlay mark according to the prior art of the photomask It is a figure which shows the position arrange | positioned at a shot area.

The measurement method designates shots for making measurements in the wafer W and generally designates five shots or nine shots as shown. Therefore, if the outer box and the inner box of the overlay mark are deformed or rotated on the X and Y axes, much overlay data is required. Thus, as shown in FIG. 3, four or more overlay marks (©, ⓓ, ⓔ, ⓕ) are required outside the shot area 60 of the photo mask, so that the overlay marks occupy a substantial area of the photo mask.

Accordingly, when the XYT axis stage 20 moves to the first shot area 60-1 to measure the overlay of the nine shot areas 60, the arm 40 descends to the Z axis stage 42. In the first shot region 60-1, the overlay mark ⓒ is measured. The 9th overlay mark ⓒ is measured in order by moving to measure the overlay mark ⓒ of the second shot region 60-2. When the measurement of the overlay mark ⓒ is completed, the measurement of the overlay marks ⓓ, ⓔ, and ⓕ again from the first shot region 60-1 to the shot region 60-9 in the same manner as described above.

Therefore, a total of 36 measurements are made while rotating the nine shot regions 60.

As such, in the conventional overlay metrology facility, since four measurements are performed on one shot region 60, a long time is required to measure one wafer, and thus there is a problem that productivity is lowered.

The present invention has been made to solve the above-described drawbacks, it is possible to measure the four overlay marks at the same time in one shot area, the overlay mark measuring equipment of the semiconductor device that can reduce the overlay measurement time of the wafer And to provide a measuring method.

The present invention for achieving the above object, in the overlay mark measuring equipment of the semiconductor device, is provided at one end of the arm including the Z-axis stage can measure at least two overlay marks at the same time in one shot area Provided is an overlay mark measuring apparatus for a semiconductor device including measuring means.

In addition, the present invention provides an overlay mark measuring method of a semiconductor device for simultaneously measuring four overlay marks in one shot area by using the measuring apparatus of the present invention.

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

4 is a perspective view of an overlay mark measuring apparatus of a semiconductor device according to the present invention, Figure 5 is a cross-sectional view of the movable arm portion according to the present invention.

The overlay mark measuring device will be described with the same reference numerals for the same constituent members as those shown in the prior art with reference to the prior drawings.

The base plate 10 and the XYT axis stage 20 are installed to allow the wafers mounted on the base plate 10 to be tilted like the X and Y axes. The base plate 10 is also provided with a base plate 10. The vertical column 30 is provided, and the arm 40 including the Z-axis stage 42 in the orthogonal direction is provided at the end of the column 30. And at the end of the arm 40 is provided measuring means 100 which is a feature of the present invention.

As shown in FIG. 4, the measuring means 100 measures two or more overlay marks simultaneously in one shot area. The measuring means 100 includes a moving arm 110 and a camera 120.

The moving arm unit 110 is provided in plurality in the lower portion of the arm 40 which is moved up and down through the Z-axis stage 42, preferably extending in all directions from the lower portion of the arm 40 to the overlay mark (see Fig. 3): Ⓒ, ⓓ, ⓔ, ⓕ) is installed to move horizontally according to the alignment position.

And each of the movable arm 110, as shown in FIG. 5, the motor 110, which can be rotated forward and backward is installed or installed in the arm 40, the lead screw 112 receives the rotational drive from the motor 111 is The first arm 113 is installed to include the lead screw 112 therein and is rotated and linearly moved along the thread. The bearing 114 is provided at one end of the first arm 113. The second arm 115, which is linearly moved, is installed in the form of "a".

And the camera unit 120 is installed on the lower end side of the two arms (115) facing the "a".

The camera unit 120 is provided with a lens 122 capable of focusing each overlay mark (ⓒ, ⓓ, ⓔ, ⓕ).

Here, the measuring means 100 is displayed by toll monitor not shown.

Referring to the operation and method of the overlay mark measuring equipment of the semiconductor device configured as described above are as follows.

First, the overlay mark is described in more detail by using the overlay mark. The overlay mark includes an outer box (unsigned) and an inner box (unsigned). Here, the outer box is formed in the form of a box in which a bar pattern is disposed on four surfaces of the lower structure of the semiconductor substrate, and the inner box is a mask used for patterning the lower structure on the interlayer insulating layer, for example, the photoresist is formed on four sides. It is formed in the form of a box in which the eva pattern is arranged.

Therefore, by measuring the distance between the outer box and the inner box, the overlay of the semiconductor device was measured according to whether these distances were the same or different.

The overlay measurement scans the outer box and the inner box using an interferometer measuring the edge signal of the overlay mark, checks each center point of the edge signal position in the scanned area, and calculates the overlay measurement value using the center point spacing.

Such overlay measurement is performed as follows through the measuring device of the present invention. A shot area (see FIG. 2: 60) for measuring in the wafer is designated as five or nine shots. In addition, four or more overlay marks (refer to FIG. 3: ©, ⓓ, ⓔ, ⓕ) are required outside the shot area 60 of the photo mask, so that the overlay marks occupy a substantial area of the photo mask.

As a result, the XYT axis stage 20 moves to the shot area 60 so that the nine shot regions 60 are sequentially measured, and the arm 40 descends as the Z axis stage 42. In addition, the movable arm 110 positioned at the lower end of the arm 40 is adjusted in length according to the alignment position of each overlay mark (ⓒ, ⓓ, ⓔ, ⓕ) to move horizontally.

That is, the lead screw 112 is rotated by the driving of the motor 11, and the rotational movement of the lead screw 112 causes the first arm 113 to rotate and linearly move, and the first screw 113 is installed through the bearing 114. The two arms 115, like the camera unit 120, set the position by a change in the length of moving forward and backward in the horizontal direction.

After fixing the position of each moving arm unit 110 as follows, each camera unit 120 focuses an overlay mark through the lens 122 and simultaneously measures four overlay marks.

As described above, one or more overlay marks for one shot region 60 may be displayed on the monitor while measuring the nine shot regions 60.

As such, by measuring each overlay mark in one shot region 60, four overlays in one shot region through the plurality of moving arm units 110 and the camera unit 120 may take a lot of measurement time. The mark is measured at the same time, and moreover, when the overlay mark is simultaneously measured, the overlay mark image is displayed on the monitor at the same time, thereby greatly reducing the measurement time of the overlay mark.

As described above, the overlay mark measuring apparatus and measuring method of the semiconductor device according to the present invention can measure four overlay marks simultaneously in one shot area, thereby significantly reducing the overlay measuring time of the wafer and It's a huge boost to productivity without the need for additional purchases.

What has been described above is just one embodiment for implementing the overlay mark measuring equipment and measuring method of the semiconductor device according to the present invention, the present invention is not limited to the above-described embodiment, it is claimed in the claims As will be apparent to those skilled in the art to which the present invention pertains without departing from the gist of the present invention, the technical spirit of the present invention may be changed to the extent that various modifications can be made.

Claims (5)

In the overlay mark measuring equipment of a semiconductor device, Measuring means installed at one end of the arm including the Z-axis stage and capable of simultaneously measuring two or more overlay marks in one shot region; Overlay mark measuring equipment of a semiconductor device comprising a. The method of claim 1, The measuring means, A plurality of moving arm portions which are connected to a lower part of the arm and horizontally move according to the alignment position of the overlay mark; A camera unit including a lens at an end side of each of the moving arm units, Overlay mark measuring equipment of a semiconductor device, characterized in that configured. The method of claim 2, The moving arm unit, Motor, A lead screw driven to rotate from the motor; A first arm connected to the lead screw and rotating and linearly moving; A second arm that is linearly connected with the first arm and the bearing as a medium; Overlay mark measuring equipment of a semiconductor device, characterized in that configured. An overlay mark measuring method of a semiconductor device for simultaneously measuring four overlay marks in one shot region by using the measuring apparatus of claim 1. The method of claim 4, wherein The overlay mark measuring method of a semiconductor device, characterized in that the overlay mark image is displayed on the monitor at the same time when the overlay mark is measured simultaneously.

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