JPH0669109A - Chip and method for measuring shape of electron beam spot - Google Patents

Abstract

PURPOSE:To provide a chip for measuring the shape of an electron beam spot in which highly efficient alignment is realized between dots and the electron beam spot. CONSTITUTION:The chip 20 for measuring the shape of an electron beam spot has a pattern 23 for measuring the shape of the electron beam spot formed on an Si chip substrate 21. The measuring pattern 23 comprises a grid pattern formed by X-direction lines 26-1-26-4 and Y-direction lines 27-1-27-4 made of Ta, and dots 28-1-28-9 in each grid made of Ta. The dots 28-1-28-9 are located at predetermined positions with respect to the lines 26-1-26-4, 27-1-27-4. Each line 26-1-26-4, 27-1-27-4 is constituted to function as a reference position when the dots 28-1-28-9 are searched.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam spot shape measuring chip used in an electron beam exposure apparatus and an electron beam spot shape measuring method using the same.

In the electron beam exposure apparatus, it is necessary to adjust the electron beam prior to the electron beam exposure in order to perform the exposure with high accuracy.

The adjustment of the electron beam is performed by measuring the current electron beam spot shape to obtain information on the current electron beam spot shape, and adjusting various parts of the electron beam exposure apparatus accordingly. By doing so.

It is desirable that this electron beam adjustment be performed efficiently in a short time.

In order to improve the efficiency of electron beam adjustment, first of all, it is necessary to efficiently measure the shape of the spot of the current electron beam on the wafer.

Here, for convenience of description, the principle of measuring the electron beam spot shape using dots will be described.

First, the measurement of the presence or absence of rotation will be described.

In FIG. 11, the left side is the case without rotation,
The right side is the case with rotation.

The rectangular electron beam spot 1 shown in FIG. 11A has no rotation. The rectangular beam spot 1A in FIG. 11F has a rotation of an angle θ.

First, as shown in FIGS. 11 (A) and 11 (F), alignment is performed so that one edge 2 (2A) of the rectangular beam spot 1 (1A) and the dot 3 coincide with each other.

The dots 3 are a material having a large amount of reflected electrons.
The portion 4 around the dot 3 is a material having a small amount of backscattered electrons.

Next, in the same figure, (A), (B), (C),
As shown in (D) and (F), (G), (H), and (I) of the same figure, the beam spot 1 (1A) is scanned in the X direction.

In FIG. 11 (E), reference numerals (A), (B),
(C) and (D) are shown in FIGS. 11 (A), (B), (C),
Corresponds to (D). Similarly, reference numerals (F), (G), (H), and (I) in FIG.
It corresponds to (G), (H), and (I).

With respect to the beam spot 1, the area of the dot 3 remains constant and does not change, and the waveform of the reflected electron intensity is as shown in FIG.
-(C) section is flat.

On the other hand, regarding the beam spot 1A, the area of the dot 3 gradually increases, and the waveform of the reflected electron intensity becomes as shown in FIG.
The section (G)-(H) is inclined.

The presence or absence of rotation of the beam spot is measured based on the reflected electron intensity waveform.

The shape defect of the rectangular beam spot is
It is measured as described below.

The rectangular beam spot 1 in FIG. 12A has no shape defect. The rectangular beam spot 1B in FIG. 7E has a notch 5 and has a shape defect.

Also in this case, similarly to the above, first, as shown in FIGS. 9A and 9E, one edge 2 (2B) of the rectangular beam spot 1 (1B) and the dot 3 coincide with each other. To align.

Next, the beam spot 1 (1B) is shifted in the Y direction as shown in FIGS. (A), (B), (C) and (E), (F), (G) in the same figure. Meanwhile, it is repeatedly scanned in the X direction.

As for the beam spot 1, as shown in FIG. 3D, a backscattered electron intensity waveform whose right and left are aligned is obtained.

On the other hand, regarding the beam spot 1B, the reflected electron intensity waveform shown in FIG. In this waveform, there is an irregular portion indicated by reference numeral 6, and this reflects the notch portion 5.

Therefore, the shape defect of the rectangular beam spot can be measured depending on whether the reflected electron intensity waveform has an irregular portion or not.

In any of the above cases, the work of aligning the dots with the edges of the beam spot is done. The present invention makes it possible to easily perform this work.

[0025]

2. Description of the Related Art FIG. 13 shows a conventional method for measuring a beam spot shape.

Reference numeral 10 is an electron beam exposure apparatus main body, 11 is a stage, 12 is a wafer holder, and 13 is a Si wafer.

Conventionally, first of all, submicron-sized Au is used.
The particles 14 are dispersed on the wafer 13, and then the stage 11 is moved while observing the monitor image, so that one Au particle 1
4 is detected, the Au particles 14 are aligned so that they coincide with the edge 2 of the beam spot 1 on the wafer 13 of the electron beam 15, and then the beam spot 1 is scanned as described above to perform the measurement. Was.

[0028]

Since the Au particles 14 are scattered and their positions are not specified, the stage 11 is moved by trial and error to move one Au particle 14 to another.
The work of searching for is required.

This work is tedious and time consuming.

Further, since the Au particles 14 are irregular,
Even if one Au particle is searched for, if the size of the Au particle is too large, another Au particle must be searched again.

Further, Au particles of the same size cannot always be used with good reproducibility every time the shape of the beam spot is measured, and the shape of the beam spot cannot be constantly measured under the same conditions.

Therefore, the present invention provides an electron beam spot shape measuring chip that realizes easy dot search and an electron beam spot shape measuring method using the same, as a structure provided with a reference for finding a dot. The purpose is to do.

[0033]

According to a first aspect of the present invention, there is provided the above-mentioned holder of an electron beam exposure apparatus, which irradiates a sample on a holder fixed to a stage with an electron beam formed through a slit to expose the sample. An electron beam spot shape measuring chip used for measuring the shape of a spot formed on the sample of the electron beam, which is fixedly provided and detects backscattered electrons, comprising: The chip substrate has an electron beam spot shape measurement pattern formed of a material having a different proportion of reflected electrons or having a thickness different from that of the substrate, and the electron beam spot shape measurement pattern has the above-mentioned spot size. The size of the dots is smaller than that of the spots, and the width of the dots is narrower than the size of the spots. When the one in which was become more configuration.

According to a second aspect of the present invention, in the first aspect, the chip substrate has a SiO ₂ film on the surface thereof, and has dots, X-direction lines, and Y-direction lines embedded in the SiO ₂ film. It was done.

According to a third aspect of the present invention, the electron beam spot shape measuring chip according to the first or second aspect is used, the electron beam spot is scanned, reflected electrons are detected, and the X-ray of the electron beam spot is detected. The coordinates of the current position with respect to the direction line and the Y-direction line are calculated, the relative coordinates of the dot with respect to the current position of the electron beam spot are calculated, and the dot is moved to the position of the electron beam spot. The stage is moved according to the calculated relative coordinates.

According to a fourth aspect of the present invention, the electron beam spot shape measuring chip according to the first or second aspect is used, the electron beam spot is scanned, reflected electrons are detected, and the X-ray of the electron beam spot is detected. The coordinate of the current position with respect to the directional line and the Y-direction line is obtained, the electron beam spot is scanned, the reflected electrons are detected, and the Y coordinate of the position where the electron beam spot scans the adjacent X-direction line and the electron beam. The X coordinate of the position where the spot scans the adjacent Y-direction line is obtained, the coordinate of the center position is calculated from the obtained Y coordinate and X coordinate, and the calculation is performed so that the dot reaches the position of the electron beam spot. The configuration is such that the stage is moved according to the center coordinates.

According to a fifth aspect of the present invention, in the electron beam spot shape measuring chip according to the first or second aspect, a line pattern is used, the electron beam spot is scanned, reflected electrons are detected, and block exposure is performed. It is configured to measure the relative displacement or shape of the electron beam spot in.

[0038]

The X-direction line and the Y-direction line of claim 1 are:
It functions as a reference for specifying the dot position.

Each dot has the same size, and regardless of which dot is used, the conditions for measuring the shape of the beam spot are the same.

The structure of embedding the X-direction line and the Y-direction line in claim 2 acts so that the side surface of each line is less likely to be affected.

The structure for obtaining the coordinates of the current position of the electron beam spot and the relative coordinates of the dot with respect to the current position coordinates of claim 3 functions so as to enable calculation of the amount of movement of the stage.

The configuration for obtaining the midpoint coordinates of claim 4 also works so as to make it possible to calculate the amount of movement of the stage by calculation.

The structure using the line pattern according to the fifth aspect operates so as to accurately measure the relative displacement of the electron beam spot and the like.

[0044]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an enlarged main part of an electron beam spot shape measuring chip 20 according to an embodiment of the present invention.

Reference numeral 21 is a Si chip substrate.

On this Si chip substrate 21, a cross mark 22 (which is a conventional technique per se) and an electron beam spot shape measuring pattern 23 which is an essential part of the present invention are provided.

As shown in FIG. 2 as well, the cross mark 22 is formed by extracting the Ta film 24 in a cross shape, the ground is Si, and the width W ₁ is about 10 μm.

Si has a low electron reflection rate, and Ta has a high electron reflection rate.

This cross mark 22 is the same as the conventional one.
It is used to measure the sharpness of the electron beam spot and the position of the electron beam spot.

Numeral 25 is an electron beam spot, which is about 1 μm.
m is the size of the corner.

As shown also in FIG. 3, the pattern 23 is formed by removing the Ta film by etching and leaving a part of the Ta film, and the X direction line 26-extending in the X direction. 1 to 26-4 and Y direction lines 27-1 to 2 extending in the Y direction and orthogonal to the X direction lines 26-1 to 26-4
7-4, and dots 28-1 to 28-9 positioned one by one in each frame formed by the X-direction line and the Y-direction line.

The width W ₂ of the X-direction lines 26-1 to 26-4 and the Y-direction lines 27-1 to 27-4 is 0.1 μm, which is considerably smaller than the electron beam spot 25.

The diameter D _{1 of the} dots 28-1 to 28-9 is
They are uniform, have a size of 0.1 μm, and have an electron beam spot of 25.
Considerably smaller.

Each of the dots 28-1 to 28-9 has the same role as the Au particles in the conventional example.

The positions of the dots 28-1 to 28-9 with respect to the X-direction lines 26-1 to 26-4 and the Y-direction lines 27-1 to 27-4 are predetermined and known.

The distance X from the X direction line 26-1 of the dot 28-1 is, for example, 7 μm, and the distance Y from the Y direction line 27-1 is, for example, 7 μm. This distance X, Y
Is the distance within the deflection range of the electron beam.

The X-direction lines 26-1 to 26-4 and the Y-direction lines 27-1 to 27-4 function as a reference when searching for the respective dots 28-1 to 28-9.

If the intersections of the X-direction lines 26-1 to 26-4 and the Y-direction lines 27-1 to 27-4 are coordinates (0,0),
Each dot 28-1 to 28-9 is located at a point of coordinates (X, Y).

The pattern 23 is provided on the Si chip substrate 21 at a predetermined position P ₂ with respect to the position P ₁ of the cross mark 22. That is, pattern 23
The position of the cross mark 22 with respect to the cross mark 22 is known.

Next, measurement of the electron beam spot shape using the measuring tip 20 of FIG. 1 will be described.

In FIG. 4, parts corresponding to those shown in FIG. 13 are designated by the same reference numerals.

The measuring chip 20 is mounted on the wafer holder 12
The upper portion is fixed at a position near the portion where the Si wafer 13 is fixed.

A control unit 30 applies a deflection voltage to the deflection coil 31 of the electron beam exposure apparatus main body 10, and
A signal from the backscattered electron detector 32 at the bottom of the apparatus body 10 is applied, and a signal is applied to the stage drive unit 33.

First, the stage 11 is moved, and as shown in FIG. 4, the cross mark 22 of the measuring chip 20 is set so as to be directly below the exposure apparatus main body 10.

An electron beam 35 is emitted from the electron gun 34, passes through the rectangular slit 37 of the mask 36, and is shaped. The shaped electron beam 38 is used as the measuring tip 2
0, the cross mark 22 is irradiated.

From this state, as shown in FIG.
The rectangular electron beam spot 25 has one edge 2
All the operations until the 5a is aligned so as to match the dot 28-1 are controlled by the microcomputer in the control unit 30.

This will be described below.

First, in FIG. 5, the electron beam spot position is measured (ST1).

Here, the beam spot 25 is swung so as to cross the cross mark 22 by the deflection coil 31, and the reflected electrons at this time are detected by the detector 32 to measure the position of the beam spot 25.

Then, the stage is moved (ST2).

The stage driving unit 33 causes the stage 1
1 is moved by a predetermined amount corresponding to the positions P ₁ and P ₂ ,
The beam spot 25 is moved to a position in the pattern 23 (this position is unknown at this point), as shown by a chain double-dashed line in FIG. This position is called the current position.

Next, waveform measurement is performed (ST3).

Here, a deflection voltage is applied to the deflection coil 31, and the beam spot 25 has an X direction line 26-1 and a Y direction line 27-1 as indicated by arrows 40 and 41.
Is scanned until it crosses. The detection waveform of the detector 32 at this time is measured.

Next, the coordinates of the electron beam spot 25 are calculated (ST4).

Here, the detected waveform of the detector 32 is measured, and the coordinates (x, y) of the current position of the electron beam spot 25 with respect to the lines 26-1 and 27-1 are calculated and obtained.

Next, the coordinates of the dot 28-1 are calculated (S
T5).

Since the coordinates (X, Y) are known in FIGS. 1 and 6A, the dot 2 with respect to the beam spot 25 is
The coordinates (X- _x , Y- _y ) of 8-1 are obtained by calculation.

Then, the stage is moved (ST6).

A signal corresponding to the above coordinates (X- _x , Y- _y ) is applied to the stage drive unit 33, the stage 11 is moved, and as shown in FIG. The edge 25a of the spot 25 is brought into contact with the edge 25a.

From this state, the beam spot is scanned according to the command as shown in FIG. 11 or 12, and the presence or absence of rotation of the beam spot and the presence or absence of shape defect of the beam spot are detected.

In the above embodiment, the cross mark 22 on the measuring chip 20 is not always necessary, and the measuring chip may have only the measuring pattern 23.

Further, W or Au can be used instead of Ta described above.

Even if the current position of the beam spot is in any of the plurality of frame portions of the measurement pattern 23, the dots in the frame portion correspond to the beam spot by the same operation as described above. It is aligned with the part to be used.

Here, the dots 28-1 to 28-9 in each frame portion
Have the same size, the shape of the beam spot is measured under the same condition no matter which dot is aligned with the beam spot.

Next, another example of alignment of dots with electron beam spots will be described.

In this example, as shown in FIG. 8A, the dot 28A-1 is formed by the adjacent X direction lines 26-1 and 26-2 and the adjacent Y direction lines 27-1 and 27-2. The dot 28A-1 is provided at the center of the enclosed square frame 50.
It is effective when applied to each line when the coordinates for each line are unknown.

FIG. 7 shows a flowchart of the operation. S
T1 to ST4 are the same as in FIG.

Next, waveform measurement is performed (ST10).

A deflection voltage is applied to the deflection coil 31, and the beam spot 25 extends over the entire width of the frame until it crosses the Y-direction line 27 and the X-direction line facing each other as shown by arrows 51 and 52 in FIG. It is scanned and the detection waveform of the detector 32 at this time is measured.

Next, calculation of the center coordinates of the frame portion (ST11)
I do.

By measuring the detection waveform of the above detector 32,
The coordinates X ₁ , X ₂ , Y ₁ , Y ₂ on each line are obtained, and from this,

[0092]

[Equation 1]

Is calculated.

Next, the stage is moved (ST1
2).

[0095]

[Equation 2]

Then, a signal corresponding thereto is applied to the stage drive unit 33, the stage 11 is moved, and
As shown in (B), the dot 28A-1 is brought into a state of hitting one edge 25a of the electron beam spot 25.

Further, in the measurement pattern 23,
Since the Y-direction line 27-1 is considerably narrower than the size of the beam spot, it is possible to measure the shape of the beam spot using the Y-direction line 27-1 as shown in FIG. I can.

When the beam spot is, for example, an L-shaped beam spot 60, when the beam spot is scanned so as to cross the Y direction line 27-1, a reflected electron intensity signal having a waveform indicated by a line 61 is obtained.

The shape of the beam spot can be measured from this waveform.

Next, a modified example of the above measurement pattern will be described with reference to FIG.

[0102] The measurement pattern 23A includes, over a Si chip substrate 21 has a SiO ₂ film 70, and the SiO ₂ film 70, X-direction line 26A-1,26A-2 manufactured by W, and manufactured by W The Y direction lines 27A-1 and 27A-2 and the W dot 28B-1 are provided.

The lines 26A-1, 27A-1 and the dots 28B-1 are formed by forming a SiO ₂ film 40 on the Si chip substrate 21, coating a resist on the surface, exposing a pattern, and etching and ashing. This is done by forming patterned grooves and pits, and selectively growing W to fill the grooves and pits.

The pattern 23A of this configuration has the line 26
The side surfaces of A-1 and 27A-1 do not affect the waveform obtained in step ST3 in FIG. 6, and finally the dot coordinates are accurately obtained, and the beam spot is the dot 28B.
-1 is more accurately aligned.

[0104]

As described above, according to the first aspect of the present invention, it is possible to provide a reference for aligning the beam spot with the dot.

The shape of the beam spot can always be measured under the same conditions.

According to the invention of claim 2, the coordinates of the X-direction line and the Y-direction line can be accurately obtained.

According to the invention of claim 3, since the amount of moving the stage for aligning the dot with the electron beam spot can be obtained by calculation, trial and error is not required, and the dot can be formed in a short time. It can be aligned with the electron beam spot.

According to the invention of claim 4, as in the invention of claim 3, the dot can be aligned with the electron beam spot in a short time without trial and error.

According to the invention of claim 5, it is possible to accurately measure the relative displacement or shape of the electron beam spot in the block exposure.

[Brief description of drawings]

FIG. 1 is a plan view of an electron beam spot shape measuring chip according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along line II-II in FIG.

FIG. 3 is an enlarged cross-sectional view taken along the line III-III in FIG.

FIG. 4 is a diagram illustrating measurement of an electron beam spot shape using the measuring tip of FIG.

FIG. 5 is a flowchart of an operation of aligning a dot with an edge of an electron beam spot.

FIG. 6 is a diagram for explaining alignment of dots with edges of electron beam spots in FIG. 5;

FIG. 7 is a flowchart of an operation of aligning a dot with an edge of an electron beam spot.

FIG. 8 is a diagram illustrating another example of alignment of dots with electron beam spots in FIG. 7.

FIG. 9 is a diagram illustrating beam spot shape measurement using a line in the Y direction.

FIG. 10 is a diagram showing a modification of the measurement pattern of FIG.

FIG. 11 is a diagram showing a measurement principle of rotation of an electron beam spot.

FIG. 12 is a diagram showing a principle of measuring a shape defect of an electron beam spot.

FIG. 13 is a diagram showing a conventional method of measuring a beam spot shape.

[Explanation of symbols]

20 Electron Beam Spot Shape Measurement Chip 21 Si Chip Substrate 22 Cross Mark 23, 23A Electron Beam Spot Shape Measurement Pattern 24 Ta Film 25 Electron Beam Spot 25a Edge 26-1 to 26-4, 26A-1, 26A-2 X Direction lines 27-1 to 27-4, 27A-1, 27A-2 Y direction lines 28-1 to 28-9, 28A-1, 28B-1 dots 30 control unit 31 deflection coil 32 backscattered electron detector 33 stage drive Part 34 Electron gun 35 Electron beam 36 Mask 37 Slit 38 Molded electron beam 50 Frame part 70 SiO ₂ film

Claims (5)

[Claims] 1. An electron beam exposure apparatus which irradiates a sample on a holder fixed to a stage with an electron beam formed through a slit to expose the sample, is fixed to the holder, and detects backscattered electrons. An electron beam spot shape measuring chip used for measuring the shape of a spot of the electron beam formed on the sample, the material being different in the proportion of reflected electrons from the chip substrate. It has an electron beam spot shape measuring pattern (23) formed of a different thickness from that of the substrate, and the electron beam spot shape measuring pattern has a dot (28) having a size smaller than the size of the spot.
-1 to 28-9), which is narrower than the size of the above-mentioned spot, and is arranged in the vicinity of the dot in a direction orthogonal to each other in the X direction line (26-1 to 26-4) and the Y direction line. (27-1 ~ 2
7-4) A chip for measuring an electron beam spot shape, characterized in that 2. A SiO ₂ film (7) is formed on the surface of the chip substrate.
0) and embedded in the SiO ₂ film (28B
-1), X-direction lines (26A-1 to 26A-2), and Y-direction lines (27A-1 to 27A-2). For chips. 3. The electron beam spot shape measuring chip according to claim 1 is used to scan the electron beam spot to detect backscattered electrons,
The coordinates of the current position of the electron beam spot with respect to the X-direction line and the Y-direction line are obtained (ST3, ST
4) Calculate the relative coordinates of the dot with respect to the current position of the obtained electron beam spot (ST5), and move the stage according to the calculated relative coordinates so that the dot reaches the position of the electron beam spot. Is moved (ST6), the electron beam spot shape measuring method. 4. The electron beam spot shape measuring chip according to claim 1 is used to scan the electron beam spot to detect backscattered electrons,
The coordinates of the current position of the electron beam spot with respect to the X-direction line and the Y-direction line are obtained (ST3, ST
4), scanning the electron beam spot, detecting backscattered electrons,
The Y coordinate of the position where the electron beam spot scans the adjacent X direction line and the Y coordinate where the electron beam spot is adjacent
Obtain the X coordinate of the position to scan the direction line (ST1
0), the coordinates of the center position are calculated from the obtained Y coordinate and X coordinate (ST11), and the dot is moved according to the calculated center coordinates so as to reach the position of the electron beam spot (ST1).
2) A method for measuring an electron beam spot shape, which has a configuration. 5. The electron beam spot shape measuring chip according to claim 1, wherein a line pattern is used, the electron beam spot is scanned, reflected electrons are detected, and the electron beam spot in the block exposure is detected. An electron beam spot shape measuring method characterized by measuring a relative displacement or a shape.