JP3168072B2 - Electron beam spot shape measuring chip and electron beam spot shape measuring method using the same - Google Patents

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

In the adjustment of the electron beam, information on the current shape of the electron beam spot is obtained by measuring the shape of the current electron beam spot, and various parts of the electron beam exposure apparatus are adjusted accordingly. By doing that.

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

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

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

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

In FIG. 11, the left side shows the case without rotation.
The right side shows 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 the angle θ.

First, as shown in FIGS. 11A and 11F, one edge 2 (2A) of a rectangular beam spot 1 (1A) is aligned with a dot 3 so as to be coincident.

The dot 3 is a material having a large amount of reflected electrons.
A portion 4 around the dot 3 is made of a material having a small amount of reflected electrons.

Next, FIGS. 3 (A), 3 (B), 3 (C),
As shown in (D) and FIGS. (F), (G), (H), and (I), the beam spot 1 (1A) is scanned in the X direction.

In FIG. 11E, reference numerals (A), (B),
(C) and (D) show FIGS. 11 (A), (B), (C),
This corresponds to (D). Similarly, in FIG. 11 (J), reference numerals (F), (G), (H), and (I) denote FIG. 11 (F),
(G), (H), and (I).

Regarding the beam spot 1, the area covering the dot 3 is constant without changing, and the waveform of the reflected electron intensity is as shown in FIG.
Section (C) is flat.

On the other hand, as for 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 as follows.
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.

In this case, as described above, first, one edge 2 (2B) of the rectangular beam spot 1 (1B) coincides with the dot 3, as shown in FIGS. Align as follows.

Next, as shown in FIGS. 3A, 3B and 3C and FIGS. 3E, 3F and 3G, the beam spot 1 (1B) is shifted in the Y direction. While repeatedly scanning in the X direction.

With respect to the beam spot 1, as shown in FIG. 3D, a reflected electron intensity waveform in which the left and right are aligned is obtained.

On the other hand, regarding the beam spot 1B, a reflected electron intensity waveform shown in FIG. This waveform has an irregular portion indicated by reference numeral 6, which reflects the missing portion 5.

Therefore, the shape defect of the rectangular beam spot is measured depending on whether or not there is an irregular portion in the reflected electron intensity waveform.

In any of the above cases, the operation of aligning the dot with the edge of the beam spot is performed. The present invention enables this operation to be performed easily.

[0025]

FIG. 13 shows a conventional method for measuring a beam spot shape.

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

Conventionally, first, a submicron-sized Au
The particles 11 are scattered on the wafer 13, and then the stage 11 is moved while viewing the monitor image, so that one Au particle 1
4, 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 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
It is necessary to search for.

This operation is troublesome and time-consuming.

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, every time the shape of the beam spot is measured, Au particles having the same size cannot always be used with good reproducibility, 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 which realizes easy dot search and an electron beam spot shape measuring method using the same, as a configuration provided with a reference for searching for a dot. The purpose is to do.

[0033]

According to a first aspect of the present invention, there is provided an electron beam exposure apparatus for irradiating a sample on a holder fixed to a stage with an electron beam formed through a slit and exposing the electron beam to the holder. A fixedly provided, electron beam spot shape measuring chip used to detect reflected electrons and measure the shape of a spot formed on the sample of the electron beam, the chip being provided on a chip substrate, The chip substrate has an electron beam spot shape measurement pattern made of a material having a different ratio of reflected electrons or a thickness different from that of the substrate, and the electron beam spot shape measurement pattern has a size corresponding to the size of the spot. A dot having a smaller size than that of the spot and an X-direction line and a Y-direction line which are narrower than the size of the spot and are arranged in an orthogonal arrangement in the vicinity of the dot. 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 a dot, an X direction line, and a Y direction line 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 to scan an electron beam spot, detect reflected electrons, and detect the X-ray of the electron beam spot. The coordinates of the current position with respect to the direction line and the Y direction line are obtained, and the relative coordinates of the obtained electron beam spot with respect to the current position of the obtained electron beam spot are calculated. In this configuration, the stage is moved according to the calculated relative coordinates.

According to a fourth aspect of the present invention, an electron beam spot shape measuring chip according to the first or second aspect is used to scan an electron beam spot, detect reflected electrons, and detect the X-ray of the electron beam spot. The coordinates of the current position with respect to the direction line and the Y direction line are determined, the electron beam spot is scanned, 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 are detected. 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 the X-coordinate, and the calculation is performed so that the dot reaches the position of the electron beam spot. In this configuration, 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, an electron beam spot is scanned, reflected electrons are detected, and block exposure is performed. In this configuration, the relative displacement or shape of the electron beam spot is measured.

[0038]

According to the first aspect, the X direction line and the Y direction line are
Functions as a reference for specifying the position of the dot.

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

The structure in which the X-direction line and the Y-direction line are embedded in the second aspect acts so that the side surface of each line is hardly affected.

According to the third aspect of the present invention, the coordinates of the current position of the electron beam spot are obtained, and the coordinates of the dot relative to the current position are obtained.

The structure for obtaining the coordinates of the middle point according to claim 4 also works so that the amount of movement of the stage can be calculated by calculation.

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

[0044]

FIG. 1 is an enlarged view of an essential part of an electron beam spot shape measuring chip 20 according to an embodiment of the present invention.

Reference numeral 21 denotes a Si chip substrate.

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

As shown in FIG. 2, 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 rate of reflecting electrons, and Ta has a high rate of reflecting electrons.

The cross mark 22 is formed as in the prior art.
It is used to measure the sharpness of the electron beam spot and the position of the electron beam spot.

Reference numeral 25 denotes an electron beam spot having a size of about 1 μm.
m is the size of the square.

As shown 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 27-2 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 located 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
Uniform, 0.1 μm, electron beam spot 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 of the dot 28-1 from the X-direction line 26-1 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 references when searching for the dots 28-1 to 28-9.

If the intersection of the X-direction lines 26-1 to 26-4 and the Y-direction lines 27-1 to 27-4 is coordinate (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, the pattern 23
Are known with respect to the cross mark 22.

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

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

The measuring chip 20 is attached to the wafer holder 12
The upper part is fixed at a position near the part where the Si wafer 13 is fixed.

A control unit 30 applies a deflection voltage to a 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 main body 10 is applied, and a signal is applied to the stage driving unit 33.

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

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

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

Hereinafter, this will be described.

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

Here, the position of the beam spot 25 is measured by deflecting the beam spot 25 across the cross mark 22 by the deflection coil 31 and detecting the reflected electrons at this time by the detector 32.

Next, the stage is moved (ST2).

The stage 1 is driven by the stage driving section 33.
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 time) as shown by a two-dot chain line in FIG. This position is called the current position.

Next, waveform measurement is performed (ST3).

Here, a deflecting voltage is applied to the deflecting coil 31, and the beam spot 25 is moved to the X-direction line 26-1 and the Y-direction line 27-1 as indicated by arrows 40 and 41.
Are scanned until they cross. The waveform detected by the detector 32 at this time is measured.

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

Here, the detection 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
The coordinates (X- _x , Y- _y ) of 8-1 are obtained by calculation.

Next, the stage is moved (ST6).

A signal corresponding to the coordinates (X _-x , Y _-y ) is applied to the stage drive unit 33, the stage 11 is moved, and as shown in FIG. The spot 25 is in a state of covering one edge 25a.

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

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

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

Even if the current position of the beam spot is within any of the plurality of frames of the measurement pattern 23, the dots in the frame correspond to the beam spot by the same operation as described above. Position.

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

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

In this example, as shown in FIG. 8A, a dot 28A-1 is formed by an adjacent X-direction line 26-1, 26-2 and an adjacent Y-direction line 27-1, 27-2. The dot 28A-1 is provided at the center of the enclosed square frame portion 50.
This is effective 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 portion 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. Scanning is performed, and the detected waveform of the detector 32 at this time is measured.

Next, the center coordinates of the frame are calculated (ST11).
I do.

The detection waveform of the detector 32 is measured, and
The coordinates X ₁ , X ₂ , Y ₁ , and Y ₂ on each line are obtained, and

[0092]

(Equation 1)

Is calculated.

Next, the stage is moved (ST1).
2).

[0095]

(Equation 2)

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

In the measurement pattern 23,
Since the Y-direction line 27-1 is considerably narrower than the size of the beam spot, the shape of the beam spot can be measured using the Y-direction line 27-1 as shown in FIG. I can do it.

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

From the waveform, the shape of the beam spot can be measured.

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

The measurement pattern 23A has an SiO ₂ film 70 on the Si chip substrate 21, and the X direction lines 26A-1, 26A-2 and W made of W are formed in the SiO ₂ film 70. , And a W-shaped dot 28B-1.

The lines 26A-1 and 27A-1 and the dots 28B-1 are formed by forming an SiO ₂ film 40 on the Si chip substrate 21, applying a resist to the surface, exposing the pattern, and performing etching and ashing. Then, pattern-like grooves and pits are formed, and W is selectively grown to fill the grooves and pits.

The pattern 23A having this configuration is composed of a line 26
The side surfaces of A-1 and 27A-1 do not affect the waveform obtained in step ST3 in FIG. 6, and the coordinates of the dot are finally obtained with high accuracy, and the beam spot is formed by 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 positioning a beam spot with respect to a dot.

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

According to the second aspect of the present invention, the coordinates of the X direction line and the Y direction line can be obtained with high accuracy.

According to the third aspect of the present invention, the amount by which the stage is moved to align the dot with the electron beam spot can be obtained by calculation, so that 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, similarly to the invention of claim 3, it is possible to align the dots with the electron beam spot in a short time without trial and error.

According to the fifth aspect of the present invention, the relative displacement or shape of the electron beam spot in the block exposure can be accurately measured.

[Brief description of the drawings]

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

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

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

FIG. 4 is a diagram illustrating measurement of an electron beam spot shape using the measurement chip of FIG. 1;

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 illustrating the alignment of dots with the edge of an electron beam spot 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 for explaining another example of alignment of dots with an electron beam spot in FIG. 7;

FIG. 9 is a diagram illustrating measurement of a beam spot shape using a Y-direction line.

FIG. 10 is a diagram showing a modification of the measurement pattern of FIG. 1;

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

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

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

[Explanation of symbols]

REFERENCE SIGNS LIST 20 chip for measuring electron beam spot shape 21 Si chip substrate 22 cross mark 23, 23A pattern for measuring electron beam spot shape 24 Ta film 25 electron beam spot 25a edge 26-1 to 26-4, 26A-1, 26A-2 X Direction line 27-1 to 27-4, 27A-1, 27A-2 Y direction line 28-1 to 28-9, 28A-1, 28B-1 Dot 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 shaped electron beam 50 frame part 70 SiO ₂ film

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-242919 (JP, A) JP-A-4-137720 (JP, A) JP-A-1-316933 (JP, A) JP-A-58-58 161326 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/027 G03F 7/20

Claims (5)

(57) [Claims] 1. An electron beam exposure apparatus for irradiating a sample on a holder fixed to a stage with an electron beam formed by passing through a slit and irradiating the sample with the electron beam for exposure. 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 having a different ratio of reflected electrons from the chip substrate on the chip substrate. And a pattern (23) for measuring an electron beam spot shape, which is formed with a thickness different from that of the substrate or the substrate.
X-line (26-1 to 26-4) and Y-direction line, which are narrower than the spot size and are arranged in an orthogonal arrangement near the dot. (27-1 to 2
7-4) A chip for measuring an electron beam spot shape, characterized in that the chip has the configuration of 7-4). 2. An SiO ₂ film (7) is formed on the surface of the chip substrate.
0) and dots (28B) embedded in the SiO ₂ film.
2. An electron beam spot shape measuring apparatus according to claim 1, wherein said electron beam spot shape measuring device has a configuration having an X direction line (26A-1 to 26A-2) and a Y direction line (27A-1 to 27A-2). For chips. 3. An electron beam spot shape measuring chip according to claim 1 is used to scan an electron beam spot to detect reflected 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, ST3).
4) calculating relative coordinates of the dot with respect to the current position of the obtained electron beam spot (ST5), and setting the stage according to the calculated relative coordinate so that the dot reaches the position of the electron beam spot. The electron beam spot shape measuring method, characterized in that the electron beam spot is moved (ST6). 4. An electron beam spot shape measuring chip according to claim 1 is used to scan an electron beam spot to detect reflected 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, ST3).
4), scan the electron beam spot, detect reflected electrons,
The Y coordinate of the position where the electron beam spot scans the adjacent X-direction line and the Y coordinate at which the electron beam spot is adjacent
The X coordinate of the position for scanning the direction line is obtained (ST1).
0), the coordinates of the center position are calculated from the obtained Y coordinates and X coordinates (ST11), and the dots are moved according to the calculated center coordinates so that the dots reach the position of the electron beam spot (ST1).
2) An electron beam spot shape measuring method characterized by having a configuration. 5. An electron beam spot shape measuring chip according to claim 1, wherein the line beam pattern is used to scan the electron beam spot, to detect reflected electrons, and to detect an electron beam spot in the block exposure. An electron beam spot shape measuring method characterized by measuring a relative displacement or a shape.