JP2959710B2 - Area beam shape detection system, charged particle beam writing apparatus and electron beam writing apparatus including the same, and electron beam writing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique using an area beam, such as an electron beam lithography apparatus using a collective pattern irradiation method used in the manufacture of semiconductor devices and the like, and in particular, it is possible to use a highly accurate area beam. The present invention relates to an area beam shape detection system, a charged particle beam writing apparatus and an electron beam writing apparatus having the same, and an electron beam writing method.

[0002]

2. Description of the Related Art An electron beam (beam) is used in a charged particle beam lithography apparatus, for example, an electron beam lithography apparatus used for manufacturing a semiconductor device or the like. With the improvement of the beam quality, further improvement of the beam calibration accuracy is required. Various techniques have been devised to improve the accuracy of this beam calibration. One of them is a technology for detecting a beam shape. In particular, an electron beam lithography system using a batch figure irradiation method uses an area beam, and it is necessary to enlarge or reduce the area beam (change the magnification), rotate the area beam, or connect the area beams together. In many cases, the shape can be easily detected and calibrated.

Conventionally, such detection of a beam shape is performed by two-dimensionally scanning a fine dot mark with a beam (electron beam) and detecting the transmitted or reflected electrons. And these dot marks are
Generally, it is made by forming a heavy metal on a light element. Such a technology is described in, for example, “Journal of
Vacuum Science and Technology B, Vol.11, No.6, No
v / Dec 1993 P.2346-2351 ". In this technique, a gold dot mark on a silicon substrate is two-dimensionally scanned, and the reflected electron is detected to detect the beam shape, thereby correcting the position of the area beam.

However, in this technique, there is a limit in the detection accuracy of the beam shape. In other words, if an attempt is made to detect a fine pattern in order to increase the detection accuracy, the contrast of the acquired image will decrease. That is, the resolution of the beam detection is almost equal to the size of the minute dot. As the minute dot becomes smaller, a finer pattern can be detected, but the contrast of the detection signal becomes smaller as described below.

[0005] The contrast C of the detection signal is such that the beam area is S0, the minute dot area is S1, the electron reflectivity of the mark underlayer (light element such as silicon) is r0, and the electron reflectivity of the mark (gold or other heavy element). Assuming that r1, C = (S1 × r1) ÷ (S0 × r0) = (detection signal of beam portion) ÷ (detection signal of no beam portion). When the dot area S1 is reduced in order to detect a fine pattern, the contrast C is reduced from the above-described expression “S1 ÷ S0”, and the beam is easily buried in noise. That is, the beam becomes difficult to see.

[0006]

The problem to be solved is that, in the prior art, in order to detect a finer pattern of the area beam, a decrease in the contrast of the detection signal cannot be avoided. . The object of the present invention is to solve these problems of the prior art, to enable the detection of the shape of the area beam to be performed with high precision, to make the calibration of the area beam highly accurate, and to enable high-definition drawing. An object of the present invention is to provide an area beam shape detection system capable of improving the performance of an electron beam writing apparatus, a charged particle beam writing apparatus and an electron beam writing apparatus including the same, and an electron beam writing method therefor.

[0007]

In order to achieve the above object, an area beam shape detection system according to the present invention comprises: (1) a sample mark 104 having an upper surface having an area larger than the area of the area beam 102 and a right-angled end face; This sample mark 1
A scanning control unit 103 for two-dimensionally scanning the area beam on and around the area 04; a measuring unit 105 for measuring the amount of reflection or transmission of the area beam 102 from the sample mark 104 during the two-dimensional scanning; Shape detector 106 for detecting the shape of area beam 102 based on the measurement result
And at least the following. Also,
(2) In the area beam shape detection system according to (1), the sample mark 104 is formed of a rectangular parallelepiped. (3) In the area beam shape detection system according to any one of (1) and (2),
The shape detection unit 106 detects the shape of the area beam 102 by differentiating the amount of reflection or transmission of the area beam 102 from the sample mark 104 measured by the measurement unit 105 in each of the two-dimensional scanning directions. . Also,
(4) In the area beam shape detection system according to any one of (1) and (2), the shape detection unit 106
Is characterized in that the shape of the area beam 102 is detected by filtering the amount of reflection or transmission of the area beam 102 from the sample mark 104 measured by the measuring unit 105. (5) The area beam shape detection system according to any one of (1) to (4), further including a display control unit 107 that displays an image of the shape of the area beam 102 detected by the shape detection unit 106. Features.
(6) The charged particle beam device of the present invention determines the position of the area beam 10 based on the shape of the area beam 10 detected by the area beam shape detection system according to any one of (1) to (5). A correction means (control computer 18) is provided to emit the area beam 10 whose position has been corrected. (7) The electron beam lithography apparatus of the present invention determines the position of the area beam 10 based on the shape of the area beam 10 detected by the area beam shape detection system according to any one of (1) to (5). A correction means (control computer 18) is provided, and a semiconductor pattern is drawn on a wafer with the area beam 10 whose position has been corrected. (8) In the electron beam writing method of the electron beam writing apparatus according to the present invention, the area beam shape detection system according to any one of (1) to (5) is used to shape the electron beam emitted from the electron gun 1. Based on the process of detecting the shape of the area beam 10 thus detected (steps 601 to 604) and the shape of the area beam 10 thus detected,
Processing for correcting the position of the area beam 10 (step 60)
5) and a process of drawing a semiconductor pattern on the wafer using the area beam 10 whose position has been corrected (step 6).
06) at least.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the configuration according to the present invention of the area beam shape detection system of the present invention. In FIG. 1, reference numeral 101 denotes a CPU.
(Central Processing Unit) and ROM (Read Only Mem)
ory), a RAM (Random Access Memory), etc., and a computer for controlling the overall operation of the area beam shape detection system according to the present invention by computer processing. The processing unit 102 is formed by being radiated from an electron gun (not shown). Area beam, hereinafter according to the present invention, 103 is a scanning control unit, 104
Is a sample mark, 105 is a measurement unit, 106 is a shape detection unit,
107 is a display control unit.

The sample mark 104 is formed of a plate-like rectangular parallelepiped, has a right angle, and the upper surface on which the area beam 102 is irradiated has a larger area than the area beam 102.
With such a configuration, the area beam shape detection system of the present embodiment detects the shape of the area beam 102 as follows. First, the scanning controller 103 causes the area beam 102 to two-dimensionally scan the sample mark 104 and its periphery including a corner. Next, by the measuring unit 105,
The amount of reflected electrons or the amount of transmitted electrons from the sample mark 104 of the area beam 102 to be two-dimensionally scanned is measured. Then, the shape detection unit 106 obtains an image based on the measurement result of the measurement unit 105, and further performs a differentiation process and a filtering process on the image data to obtain an area beam image. The display control unit 108 displays the area beam image acquired by the shape detection unit 106 in the CRT (Cath
ode Ray Tube).

As described above, in the area beam shape detection system according to the present embodiment, the area beam 1 to be detected has a right angle with respect to the conventional beam detection using dot marks and is detected.
A sample mark 104 larger than 02 is used. Then, a desired area beam shape is obtained by differentiating the detection signal with respect to x and y or performing an appropriate filtering process. Thus, it is possible to prevent a decrease in contrast, which has been a problem in beam detection using a conventional dot mark, and to detect an area beam with high accuracy. Hereinafter, an electron beam lithography apparatus including such an area beam detection system will be described.

FIG. 2 is a block diagram showing an embodiment of the configuration according to the present invention of an electron beam lithography apparatus having the area beam detection system of the present invention. In FIG. 2, reference numeral 1 denotes an electron gun for emitting an electron beam (electron beam), reference numerals 2 and 5 denote first and second transfer masks, reference numerals 3 and 4 denote first and second transfer lenses, and 6, 7.
Are first and second reduction lenses, 8 and 9 are first and second objective lenses, and 10 is each mask (2, 5) and various lenses (3, 4, 4).
6 to 9), 11 is an area mark as a sample mark of the present invention, 12 is an area beam 10
Reflected electrons from the area mark 11, and reflected electrons 12
18 is a CPU (Central Pr
control computer for controlling the overall operation of the electron beam lithography apparatus by computer processing and controlling the operation as an area beam shape detection system according to the present invention; 19 is a deflector for deflecting the area beam 10;
0 is a lens / deflector power supply, 27 is a Faraday cup for detecting the area beam 10 transmitted through the area mark 11, 28
Is a reflection detection circuit that receives the detection result from the backscattered electron detector 13, and 29 is a transmission detection circuit that receives the detection result from the Faraday cup 27.

In this embodiment, the control computer 18 has the functions of the shape detection unit 106 and the display control unit 107 in FIG. 1, and the backscattered electron detector 13, the reflection detection circuit 28, and
1 by the Faraday cup 27 and the transmission detection circuit 29.
And the control computer 18
1 by the lens / deflector power supply 20 and the deflector 19
Of the scanning control unit 103. Hereinafter, the operation of the electron beam lithography apparatus having such a configuration according to the present invention will be described.

An area beam 10 radiated from the electron gun 1 and shaped by various lenses and masks (apertures) 2 to 9
Is formed on the target surface, and the area mark 11 placed on the target surface is two-dimensionally scanned by the deflector 19. The operation of each lens and deflector 19 is controlled by a control computer 18 via a lens / deflector power supply 20. The backscattered electrons 12 obtained by the scanning of the area beam 10 are detected by a backscattered electron detector 13. The detected backscattered electrons are processed by the backscattered electron detection circuit 28 and the control computer 18.

Hereinafter, scanning of such an area beam 10 will be described.
FIGS. 3 and 4 show details of the shape detection operation of the area beam 10 by the backscattered electron detection circuit 28 and the control computer 18 using the backscattered electrons 12 obtained by this scanning. FIG. 3 is an explanatory diagram showing a first example of an area beam detecting operation of the electron beam lithography apparatus in FIG. 2 according to the present invention. In FIG. 3, 14 is a silicon substrate, 15 is a tungsten mark as a sample mark of the present invention, 16 is a corner of the tungsten mark, 17 is an area beam, and 26 is a scanning locus of the area beam 17.

As described above, in this embodiment, the tungsten mark 15 formed on the silicon substrate 14 is used as the area mark 11 in FIG. In the area beam shape detection technique of the present example, the detection resolution of the area beam 17 is determined by the corner 16 of the tungsten mark. Therefore, the roundness of the corner 16 of the tungsten mark is desirably as small as possible, and is set to a right angle (90 °). . In addition, the scanning of the area beam 17 is performed in a range where the area beam 17 does not completely exist on the tungsten mark 15, passes through the corner 16 of the tungsten mark, and completely covers the tungsten mark 15, as indicated by a scanning locus 26.

The backscattered electrons 12 accompanying the scanning of the area beam 17 are detected by a backscattered electron detector 13. The backscattered electron signal detected by the backscattered electron detector 13 is received by the reflection detection circuit 28 in FIG. 2 and its amount is measured, and the measured amount is calculated by the control computer 18 in x and y.
By differentiating in the direction, the beam shape is obtained.
That is, assuming that the intensity of the reflected electron signal at the scanning position (x, y) is I (x, y), the beam shape signal D (x, y)
y) can be obtained by the following equation. D (x, y) = ∂ ² I (x, y) / ∂x∂y

FIG. 4 specifically shows such an area beam detecting operation and the result thereof. FIG. 4 is an explanatory diagram showing a specific example of an area beam shape detection operation by the electron beam lithography apparatus in FIG. This example particularly shows the shape detection operation of the collective figure beam shown in FIG. 3, and FIG.
Collective figure beam (area beam) used for detection, FIG.
FIG. 4B is an acquired image (detected image), and FIG.
The image (area beam image) after the differentiation processing is shown.

On the tungsten mark 15 shown in FIG.
Two-dimensional scanning is performed using an area beam (collective figure beam) 21 having the pattern shown in FIG. Then, in the control computer 18 of FIG. 2, the detected image 22 shown in FIG.
Is obtained, and further differentiated into x and y, an area beam image 23 shown in FIG. 4C can be obtained. As a result, the beam detection resolution, which was conventionally 0.25 μm, has been improved to 0.1 μm in this embodiment. Further, the detection contrast was improved from about 1 to 5.

Further, based on the detection result of such an area beam, the electron beam writing apparatus of FIG.
To correct the drawing position of the collective figure beam. As a result, the positional accuracy of the collective figure drawing, which was conventionally 0.03 μm, has been improved to 0.02 μm, and it has become possible to draw a semiconductor pattern with higher accuracy on a wafer.
In this embodiment, the silicon substrate 1 is used as the area mark.
4, the same effect can be obtained by using other mark materials as described with reference to FIG. In this embodiment,
Although the beam shape detection technique according to the present invention is applied to an electron beam lithography apparatus, a similar effect can be obtained when applied to a focused ion beam or other charged particle beam apparatus.

FIG. 5 is an explanatory diagram showing a second example of the area beam detecting operation of the electron beam writing apparatus in FIG. 2 according to the present invention. In FIG. 3, the area mark shape was measured using the tungsten mark 15 provided on the silicon substrate 14 as the area mark 11 in FIG. 2, but in this example, the knife edge was used as a sample mark to form the area beam. Perform measurement. That is, the knife edge 24 is mounted as the area mark 11 in the electron beam lithography apparatus of FIG.

The beam detection accuracy is determined by the angle 2 of the knife edge.
5, the roundness of the knife edge corner 25 is preferably as small as possible. Knife edge 2 of this example
Reference numeral 4 has a 90-degree angle and has directions in both x and y directions. The beam scanning and signal processing operations are the same as those described with reference to FIG. That is, the scanning of the beam is performed in the scanning trajectory 2
As shown in FIG. 6, the process is performed in a range where the area beam 17 does not exist at all on the knife edge 24, passes through the knife edge corner 25, and completely covers the knife edge 24.

During this scanning, the transmitted electrons of the knife edge 24 are detected by the Faraday cup 27. This detection signal is sent to the transmission detection circuit 29 in FIG. 2 and its amount is measured. Based on the measurement result of the transmission electrons, the control computer 18 controls the tungsten mark 15 in FIG.
4A to 4C, the shape of the area beam is detected with high accuracy, as in the case of using. Further, the position of the area beam 11 is corrected by the control computer 18 based on the detection result. As a result, the conventional 0.2
In the present embodiment, the beam detection resolution, which was 5 μm, is reduced to 0.
It improved to 08 μm. Further, the detection contrast is about 1
From 5 to 5. Then, as a result of correcting the drawing position of the collective figure beam using the technique of
The accuracy of the batch figure drawing position, which was 3 μm, is 0.018 μm
Improved.

In the above two examples, the shape of the area beam is obtained by differentiating the obtained image, but the following example shows an example of obtaining the beam shape by another image processing technique. The electron beam lithography apparatus and area marks used are the same as those in the above two examples. In this example, each pixel (i, j) of the acquired image shown in FIG.
, The following filtering process is added.

By this filtering process, similarly to the above two examples, the beam shape is detected using the area mark, and the area beam image shown in FIG. 4C can be obtained. As a result, the beam detection resolution, which was conventionally 0.25 μm, has been improved to 0.1 μm in this example. Further, the detection contrast was improved from about 1 to 5. As a result of correcting the drawing position of the collective figure beam using the present technology, the collective figure drawing position accuracy, which was conventionally 0.03 μm, has been improved to 0.02 μm. The same beam image detection can be performed by using a differential filter such as a Roberts filter or another image processing technique as an image processing filter in addition to the present example.

Next, the operation of drawing a semiconductor pattern by the electron beam drawing apparatus shown in FIG. 2 having the area beam shape detection system of the present invention will be described. FIG. 6 is a flowchart showing an operation example according to the present invention of the electron beam drawing apparatus in FIG. First, the area beam 10 having the shape shown in FIG. 4A is two-dimensionally scanned from outside to above the area mark 11 formed of a rectangular parallelepiped having a larger area than the area beam 10 (step 601). ), The reflected electrons 12 from the area mark 11 of the area beam 10 due to the scanning are reflected by the reflected electron detector 13 and the reflection detection circuit 28.
4 (step 602), and based on the measurement result, the control computer 18 obtains an image shown in FIG. 4B (step 603).

Further, the control computer 18 performs filtering processing or differentiation processing on this image to obtain an area beam image shown in FIG. 4C (step 604). Then, based on the area beam image obtained in this way, the control computer 18 controls the lenses 3, 4, 6 to 9 and the deflector 19 via the lens / deflector power supply 20 to obtain the area beam 10 Is performed (step 605). Then, a semiconductor pattern is drawn on the wafer by the position-corrected area beam 10 (step 606).

As described above with reference to FIGS. 1 to 6, in the area beam shape detection system of this embodiment and the electron beam lithography apparatus having the same, conventionally, beam detection is performed using dot marks. Whereas, by changing the mark structure and signal processing technology, using a mark with a right angle corner and larger than the area beam to be detected,
Performs beam detection. Then, differential processing or appropriate filtering processing is performed on x and y with respect to the resulting detection signal, and a desired area beam shape is obtained. As a result, the area beam shape can be detected with high accuracy without lowering the contrast. Then, it becomes possible to calibrate the area beam used in an electron beam lithography apparatus or the like by the collective figure irradiation method with high accuracy.

The present invention is not limited to the embodiment described with reference to FIGS. 1 to 6, and can be variously modified without departing from the gist thereof. For example, in the present embodiment, the area beam is moved to perform the two-dimensional scanning on the sample mark. However, the area mark may be moved to perform the two-dimensional scanning on the sample mark. Further, the rectangular parallelepiped of the sample mark of the present invention is a rectangle including a square.

[0029]

According to the present invention, a finer pattern of an area beam can be detected without lowering the contrast, and the shape of the area beam can be detected with high definition. Of the electron beam drawing apparatus can be improved, and high-definition drawing can be performed, and the performance of the electron beam drawing apparatus can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a configuration according to the present invention of an area beam shape detection system of the present invention.

FIG. 2 is a block diagram showing one embodiment of a configuration according to the present invention of an electron beam lithography apparatus including the area beam detection system of the present invention.

FIG. 3 is an explanatory diagram showing a first example of an area beam detection operation of the electron beam lithography apparatus in FIG. 2 according to the present invention.

FIG. 4 is an explanatory diagram showing a specific example of an area beam shape detection operation by the electron beam drawing apparatus in FIG. 2;

FIG. 5 is an explanatory diagram showing a second example of the area beam detecting operation of the electron beam lithography apparatus in FIG. 2 according to the present invention.

FIG. 6 is a flowchart showing an operation example according to the present invention of the electron beam drawing apparatus in FIG. 2;

[Explanation of symbols]

1: electron gun, 2: first transfer mask, 3: first transfer lens, 4: second transfer lens, 5: second transfer mask, 6: first reduction lens, 7: second reduction lens, 8: first transfer lens 1 objective lens, 9: second objective lens, 10, 17: area beam, 1
1: area mark, 12: backscattered electron, 13: backscattered electron detector, 14: silicon substrate, 15: tungsten mark,
16: corner of tungsten mark, 18: control computer, 1
9: deflector, 20: lens / deflector control power supply, 21: area beam, 22: detected image, 23: area beam image, 2
4: knife edge, 25: corner of knife edge, 26: scanning locus, 27: Faraday cup, 28: reflection electron detection circuit, 29: transmission electron detection circuit, 101: processing unit, 10
2: Area beam, 103: Scan control unit, 104: Sample mark, 105: Measurement unit, 106: Shape detection unit, 107:
Display control unit.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuko Goto 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (56) References JP-A-6-177025 (JP, A) JP-A-5 -144715 (JP, A) JP-A-1-243424 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 21/027 G03F 7/20 504

Claims (8)

(57) [Claims] 1. An area beam shape detection system for detecting a shape of an area beam based on an amount of reflection or transmission of an area beam scanned on the mark from the mark, the area beam being larger than the area of the area beam. A sample mark having an area upper surface and a right-angled end face, a scanning control means for two-dimensionally scanning the area beam on and around the sample mark, and a reflection amount or a reflection amount of the area beam from the sample mark during the two-dimensional scanning. An area beam shape detection system comprising: at least a measuring means for measuring a transmission amount; and a shape detecting means for detecting a shape of the area beam based on a measurement result of the measuring means. 2. The area beam shape detection system according to claim 1, wherein said sample mark is formed of a rectangular parallelepiped. 3. The area beam shape detecting system according to claim 1, wherein said shape detecting means reflects said area beam from said sample mark measured by said measuring means. Alternatively, there is provided an area beam shape detection system comprising means for differentiating the transmission amount in each of the two-dimensional scanning directions to detect the shape of the area beam. 4. The area beam shape detecting system according to claim 1, wherein said shape detecting means includes a reflection amount of said area beam from said sample mark measured by said measuring means. Alternatively, there is provided an area beam shape detection system comprising means for detecting a shape of the area beam by filtering a transmission amount. 5. The area beam shape detection system according to claim 1, further comprising means for displaying an image of the shape of said area beam detected by said shape detection means. Beam shape detection system. 6. A means for correcting the position of the area beam based on the shape of the area beam detected by the area beam shape detection system according to claim 1, wherein the position of the area beam is corrected. A charged particle beam device, which emits a focused area beam. 7. A means for correcting the position of the area beam based on the shape of the area beam detected by the area beam shape detection system according to any one of claims 1 to 5, wherein the position is corrected. An electron beam lithography apparatus for drawing a semiconductor pattern on a wafer by using the formed area beam. 8. A step of detecting a shape of an area beam formed by shaping an electron beam radiated from an electron gun by the area beam shape detection system according to claim 1; An electron beam lithography method comprising: at least a step of correcting the position of the area beam based on the shape of the beam; and a step of writing a semiconductor pattern on a wafer using the area beam whose position has been corrected. .