JPH03201526A - Alignment device and method of multiple-charged particle beam exposure system - Google Patents

Abstract

PURPOSE:To improve accuracy and reduce a fraction defective, and to enhance production yield by detecting specific alignment marks at every chip and obtaining exposure coordinates to each chip of charged-particle beams on the basis of the deflection information of charged- particle beams and alignment-mark detecting information. CONSTITUTION:When the surface of a sample 8 is irradiated with ion beams 101 and the ion beams 101 are scanned in the direction of an X-axis by a deflecting system 4 on the basis of deflection information from a computer 28 for control, secondary ions and secondary electrons corresponding to the material S of a substrate 8a and the material T of an alignment mark 8b are discharged while a current value 1 changing by a current detector is detected. S represents silicon and T boron, etc. A mark-position computing circuit 21 computes the positions x1, x2 of boundaries in the X direction of the substrate 8a and the alignment mark 8b on the basis of the location of the change of the current detecting signal and deflection information from the control computer 28, and (x1+x2)/2 is used as the position of the alignment mark. Alignment is conducted by driving an XY stage as the whole sample 8 while an XY deflecting system 6 is controlled in response to the detecting result of the positional displacement of ion beams at every chip, thus correcting the coordinates of exposure.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an alignment device and method for a charged electron beam exposure device that draws fine patterns on a sample of a wafer or mask substrate in the manufacturing process of integrated circuit devices, etc. In particular, the present invention relates to improvements in an alignment device and method for a multi-charged electron beam exposure device that can simultaneously write a large number of chips.

(Prior art) A multi-charge electron beam that irradiates a sample with multiple charge electron beams in parallel using a screen lens (fly's eye lens) having a large number of lens holes, making it possible to draw multiple chips at the same time. Exposure apparatuses are conventionally known.

In such a multi-charge electron beam exposure apparatus, a slight deviation occurs in the focusing position of the charge electron beam between the center and the periphery of the sample, resulting in image blurring at one periphery. Therefore, in order to improve productivity, it is necessary to prevent image blurring in the peripheral areas. Conventionally, a device has been proposed (Japanese Patent Application Laid-Open No. 173834/1983) in which a deflector is provided in the screen lens to individually correct the deflection of a plurality of beams that have passed through a screen lens.

In addition, in charged electron beam exposure equipment, it is important to accurately position (alignment) the sample such as a wafer to be imaged, so seven alignment marks are formed on the substrate such as the wafer, and the position of the alignment mark is detected. Alignment is performed by doing this.

(Problems to be Solved by the Invention) The exposure apparatus proposed above can prevent image blurring (improvement of resolution) in the peripheral area of the sample, but the alignment of multiple chips that are simultaneously drawn on the sample must be adjusted for each chip. For this reason, it cannot be done every time.

There was still room for improvement in terms of production.

The present invention has been made in view of the above points, and provides an alignment device and method that can reduce the defective rate and improve production yield by accurately aligning each chip in a multi-electron beam exposure device. The purpose is to provide.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a multi-charge electron beam exposure method in which a charged electron beam is irradiated onto an object to be exposed through a deflector and a screen lens, and a plurality of chips are drawn simultaneously. In the alignment device of the device, detection is performed according to the alignment marks provided at different positions for each chip in each scanning direction of the charged electron beam, and the amount of electrons emitted from the exposed object when scanning the alignment marks. an alignment mark detection means for detecting the location of the alignment mark based on the amount of electricity detected; and deflection control of the charged electron beam by the deflector; A beam deflection control means for determining the exposure coordinates of the electron beam for each chip may be provided, or the object to be exposed may be irradiated with the charged electron beam through a deflector and a screen lens.
In an alignment method for a multi-charge electron beam exposure device that simultaneously draws a plurality of chips, alignment marks are provided at different positions for each chip in each scanning direction of the charge electron beam, and when the alignment marks are scanned, objects to be exposed are emitted. detecting the location of the alignment mark based on the amount of electricity detected in accordance with the amount of electrons, and controlling the deflection of the charged electron beam by the deflector;
The exposure coordinates of the charged electron beam for each chip are determined based on the deflection control information and the alignment mark detection information.

Further, in the alignment device, a beam splitting means is provided between the deflector and the screen lens and splits the valence electron beam corresponding to each small lens on the screen lens, and the beam splitting means and the screen lens are The alignment method may further include a multi-beam deflection means provided between the deflector and the screen lens for deflecting the divided charge electron beams and emitting them to the small lenses of the screen lens. It is desirable that the charge electron beam be divided between the screen lens and the charge electron beam corresponding to each small lens on the screen lens, and that the divided charge electron beams be respectively deflected and emitted to the small lenses of the screen lens.

(Operation) A unique alignment mark for each chip is detected, and the exposure coordinates of the charged electron beam for each chip are determined based on the deflection information of the charged electron beam and the alignment mark detection information.

Furthermore, the alignment of the charged electron beam is performed independently for each chip according to the exposure coordinates for each chip.

(Example) An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a block diagram of a main part of a multi-charge electron beam exposure apparatus according to an embodiment of the present invention. 1 in the figure is an ion beam (
This is an ion beam source (charge electron beam source) that outputs a charge electron beam (charge electron beam) 101, and a blanker 2. An object aperture 3, a deflector 4, a beam limiting aperture 5, an XY direction deflector 6, and a screen lens 7 are arranged in this order. ion beam 10
1 is blanker 2, object aperture 3, deflector 4
．． A sample (exposed object, for example, a silicon wafer) 8 is irradiated with the beam through a beam limiting aperture 5, an xY direction deflector 6, and a screen lens 7, and a pattern is drawn on the sample 8. The sample 8 is placed on a conductive plate 9 that is insulated from the XY stage 11 by an insulating plate 10, and is fixed by a stopper 12. The conductive plate 9 is connected to a power source (for example, one that generates a voltage of about 10 KV) 20 via a current detector 19.
The positive electrode of the power supply 20 is connected to the ground.

The ion beam source 1 includes an ion source that generates ions (charge electrons), a focusing lens, and the like, and in this embodiment, generates a positively charged ion beam.

The blanker 2 is a type of deflector, and deflects the ion beam 101 as necessary so that the ion beam 101 is blocked by the object aperture 3, turning the ion beam 101 on (irradiating the sample 6) and off. (interruption). The object aperture 3 shapes the shape of the ion beam 101, and an image corresponding to the shape of the beam shaping hole 3a of the object aperture 3 is the sample 8.
projected on top. The deflector 4 includes a first electrode 4a and a second electrode 4b, and the beam forming hole 3 on the sample 8.
It is used to adjust the imaging range of a.

The beam limiting aperture 5 is provided with a plurality of shaped holes corresponding to the lens holes of the screen lens, and limits the charged electron beam passing through the lens holes of the screen lens. The beam limiting aperture 5 is made of a conductive, non-magnetic material (for example, stainless steel, tungsten, silicon, molybdenum).

As shown in FIG. 2, the XY direction deflectors 6 are provided in a number corresponding to the number of lens holes 7a of the screen lens 7 in order to deflect each of the plurality of valence electron beams that have passed through the beam limiting aperture 5. (Part of the illustration is omitted in Figure 2). This XY deflector 6 will be further described later. The screen lens 7 is made of silicon or aluminum deposited with a metal (for example, gold) that is difficult to oxidize, and is provided with a large number of lens holes (for example, circular holes with a diameter of 1 mm). This screen lens 7 causes an image of the beam shaping hole 3a of the object aperture 3 (for example, 1μ
A rectangular image (m×1 μm) is projected, and a plurality of the same patterns are simultaneously drawn on the sample 8. Here, the distance between the screen lens 7 and the sample 8 is set to, for example, about 20 mm, and a negative voltage (for example, -9 KV) is applied to the sample 8 with respect to the screen lens 7.

The XY stage 11 is driven by a stage drive motor 18.
The table is movable in the X-axis and Y-axis directions, which are orthogonal to each other, and moves the sample 8 to a predetermined irradiation position. This X
A length measuring mirror 13 is provided on the Y stage 11, and the position of the xY stage 11 is measured with high precision by the length measuring mirror 13 and the laser length measuring device 16.

Among the above-mentioned components 1 to 13, the vacuum chamber 1
4, and the vacuum chamber 14 is heated to a predetermined pressure (for example, 10-6 to 10-5 torrl) by an exhaust device 15.
) is exhausted.

Ion beam source 1, blanker 2, deflector 4. XY direction deflector 6. An ion beam source controller 22, a blanker controller 23, a beam deflection controller 24, an XY direction beam deflection controller 25, and an exhaust controller 26 are connected to the exhaust device 15 and the ion beam source 1, respectively. Blanker 2° deflector 4. XY direction deflector 6 and exhaust device 1
5 are respectively driven and controlled.

The laser length measuring device 16 and the stage drive motor 18 are
It is connected to the stage drive device 17.

The stage drive device 17 detects the position of the XY stage 11 and drives it.

The current detector 19 detects the current I flowing from the conductive plate 9 to the negative electrode of the power source 20 and supplies the detection signal to the mark position calculation circuit 21 .

Each of the controllers 22 to 26 and the stage drive device 17
The mark position calculation circuit 21 is connected to a control computer 28 via a CPU interface control circuit 27, and the control computer 28 controls the operation of the entire exposure apparatus. An input/output device 29 is connected to the control computer 28, and irradiation position data, deflection amount data of each of the XY direction deflectors 6, etc. are inputted thereto.

The XY direction deflector 6 includes two deflection electrodes 6a, 6b, 6c, 6 provided in the X direction and two in the Y direction for each lens hole 7a of the screen lens 7, as shown in FIG.
d, between terminals X1 and X2 and between Yl and Y2
By applying a voltage between the charged electron beam 101
to correct the focal position 11P on the sample 8 (for example, move from the state shown by the dotted chain dots to the state shown by the solid line in the figure). The amount of movement of the focal position for this correction is as follows: The maximum is about ±1 μm. Also, the voltage between the electrodes is 50 to 20
0V range, and the lens hole 7a of the screen lens 7
and the center distance of the lens holes 7a.

The alignment method in the charged electron beam exposure apparatus configured as above will be described in detail below.

Figure 4 shows the alignment mark position r in the two embodiments.
8 is a diagram for explaining a method of detecting t.
a is the substrate of sample 8, 8b is the alignment mark 1
In the illustrated example, the material of the substrate 8a is S (for example, silicon), and the material of the alignment mark 8b is T (different from S).
For example, semiconductor impurities such as boron (B), phosphorus (P),
Arsenic (As).

A region containing a large amount of antimony (sb) or aluminum (AQ), etc.).

The surface of the sample 8 is irradiated with the ion beam 101, and the fourth beam is irradiated by the deflector 4 based on the deflection information from the control computer 28.
When scanning in the X-axis direction indicated by the arrow X in FIG.
Next ion (here.

For both materials S and T, positively charged secondary ions) and secondary electrons are emitted.

On the other hand, the current value ■ detected by the current detector is given by the following equation (1).

I=I i −(i − I e) ・= (1
) Here, Ii, i and Is are respectively ion beam 1
01. ．． This is the current value of secondary ions and secondary electrons. In addition, generally i/Ia=10-' to 10-3 and Ie>
i holds true.

Therefore, between the substrate 8a and the alignment mark 8b, there are 2
Current value I due to secondary ions and secondary electrons.

Since Ie changes, the detected current value 1 changes (in this case, the contribution of the change in the secondary electron current Ie is particularly large). The mark position calculation circuit 21 calculates, based on the change position of the current detection signal and the deflection information from the control computer 28,
The boundary value in the X direction between the substrate 8a and the alignment mark 8b [
Calculate Xl and Xl, and set (X1+X2)/2 as the alignment mark position. Further, the position in the X direction can also be calculated in the same manner as described above.

In addition, in this example, as shown in FIG.
An alignment mark 8bx in the X direction and an alignment mark 8by in the X direction are formed for each chip to be drawn above, and the alignment mark positions of each chip are made to be different from each other. That is, for example, chip A in FIG.
If we focus on B.

The alignment marks 8bx^ and 8bxn in the X direction are formed so that their relative positions with respect to the outer shape of the chip are shifted by a predetermined distance do (for example, 10 μm). The same applies to the X direction. In addition, in FIG. 5(a), chip A
-Alignment mark 8 bx^~8 only for F
bxp, 8 bv^~8 byF was shown.

Similarly, the other chips are formed so that the relative positions with respect to the external shape of each chip are different from each other.

If alignment marks are formed at the same position for all chips as shown in FIG. 6, it is only possible to detect positional deviations for the entire sample 8 (all chips), whereas in this example By forming alignment marks in this way, it becomes possible to specify the exposure coordinates of the ion beam for each chip. That is, according to this embodiment, while the alignment of the sample 8 as a whole is performed by driving the XY stage, the positional deviation of the ion beam is detected for each chip, and the XX direction deflector 6 is adjusted according to the detection result. The exposure coordinates of each ion beam corresponding to each chip are corrected by controlling. With this correction, it is possible to align each chip with high precision and improve production yield, regardless of sample distortion or manufacturing errors in alignment marks.

In this embodiment, the alignment mark position is detected by a current detector, but the present invention is not limited to this. For example, a secondary electron detector may be provided near the sample (for example, an ion separation detector, The position of the alignment mark may be detected by detecting secondary electrons emitted from the sample (using a quantity analyzer).

Further, in this embodiment, the alignment mark 8b is aligned with the substrate 8a.
Although the material is different from that, the material is not limited to this. For example, the substrate 8a may be provided with four portions having different shapes, and these may be used as alignment marks. Even in this case, the detected current value I changes at the boundary position of the alignment mark, so that the mark position can be detected.

(Effects of the Invention) As detailed above, according to the alignment apparatus of claim 1 or the alignment method of claim 3, the exposure coordinates of the charged electron beam corresponding to each chip are determined by the alignment mark unique to each chip. It is possible to obtain local alignment information for highly accurate pattern drawing.

According to the alignment apparatus according to the second aspect or the alignment method according to the fourth aspect, the alignment of the valence electron beam is performed independently for each chip according to the exposure coordinates for each chip, so that distortion of the exposed object is avoided.

Regardless of alignment mark manufacturing errors, each chip can be aligned with high precision and production yield can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the main parts of a multi-charge electron beam exposure apparatus according to an embodiment of the present invention, FIG. 2 is an enlarged perspective view of a part of FIG. 1, and FIG. 3 is a deflector in the XX direction. Figure 4 is a diagram for explaining the method of detecting the alignment mark position, Figure 5 is a diagram showing the alignment mark position on the sample, and Figure 6 is a diagram showing the conventional alignment mark position. It is. 1... Ion beam source (charge electron beam source), 4...
Deflector, 5...Beam control aperture, 6...XX
Directional deflector, 7...Screen lens, 8...Sample (exposed object) 19...Current detector, 20...Power source.

Claims (1)

[Scope of Claims] 1. In an alignment device of a multi-charge electron beam exposure apparatus that irradiates a charged electron beam onto an exposed object through a deflector and a screen lens to simultaneously draw a plurality of chips, scanning of the charged electron beam is performed. The location of the alignment mark is determined using alignment marks provided at different positions for each chip in each direction and an amount of electricity detected according to the amount of electrons emitted from the exposed object when scanning the alignment mark. an alignment mark detection means for detecting;
Beam deflection control means for controlling the deflection of the charged electron beam by the deflector and determining exposure coordinates of the charged electron beam for each chip based on the deflection control information and the alignment mark detection information. Alignment device for multi-charged electron beam exposure equipment. 2. Provided between the deflector and the screen lens,
A beam splitting means for splitting the charged electron beam corresponding to each small lens on the screen lens, and a beam splitting means provided between the beam splitting means and the screen lens to respectively deflect the split charged electron beam and 2. The alignment device for a multi-charge electron beam exposure apparatus according to claim 1, further comprising a multi-beam deflection means for emitting the beam to a small lens of the lens. 3. In an alignment method for a multi-charge electron beam exposure apparatus in which a charged electron beam is irradiated onto an object to be exposed through a deflector and a screen lens to draw multiple chips simultaneously, each chip is aligned in each scanning direction of the charged electron beam. Alignment marks are provided at different positions for each alignment mark, and the location of the alignment mark is detected by the amount of electricity detected according to the amount of electrons emitted from the object to be exposed when the alignment mark is scanned, and the charged electron beam is An alignment method for a multi-charge electron beam exposure apparatus, characterized in that deflection is controlled by the deflector, and exposure coordinates of the charge electron beam for each chip are determined based on the deflection control information and the alignment mark detection information. 4. Split the charge electron beam between the deflector and the screen lens corresponding to each small lens on the screen lens, deflect the divided charge electron beams respectively, and emit them to the small lenses of the screen lens. 4. The alignment method for a multi-charge electron beam exposure apparatus according to claim 3.