JPH03194916A - Method and apparatus for detecting alignment mark position - Google Patents

Abstract

PURPOSE:To perform alignment even when a space in the vicinity of an object to be exposed is small in a charged electron beam exposure system or the like by reading an alignment mark position based on current change positions where current flowing in a substrate changes due to secondary electrons and secondary ions and deflection information of a charged electron beam. CONSTITUTION:In a method for detecting an alignment mark position for detecting the position of an alignment mark 5b on a substrate 5a with a charged electron beam 21 radiated onto the substrate 5a, the charged electron beam 21 is radiated to the substrate 5a and the alignment mark 5b formed on the substrate 5a, current change positions x1, x2 where current 1 flowing in the substrate changes due to secondary electrons and secondary ions emitted from the substrate 5a and the alignment mark 5b are detected, and based on the current change positions x1, x2 and information of deflecting voltage for deflecting the charged electron beam 21 the position of the alignment mark 5b is read. For example, a material of the substrate 5a is A (silicon, etc.) while a material of the alignment mark 5b is B (a region containing much boron, phosphorous, arsenic, etc., or aluminum, etc.) different from A.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an alignment mark position detection method and apparatus in charge electron beam exposure equipment and the like that draw fine patterns on wafers such as integrated circuit elements and mask substrates.

(Prior Art) In a charged electron beam exposure apparatus, it is important to accurately position (align) a sample such as a wafer to be imaged. For this reason, alignment marks are usually formed on a substrate such as a wafer, and positioning is performed by detecting the position of the alignment marks. This alignment mark position detection method detects secondary ions emitted when a charged electron beam is irradiated onto an alignment mark formed of a material different from that of the substrate, and detects the mark position by combining this with deflection information from a deflector. The applicant has already proposed this (Japanese Patent Application No. 231281/1981).

(Problems to be Solved by the Invention) The method proposed in item 1 requires a mass separator for secondary ion detection, and this mass separator usually has a diameter of 2 to 3 cm. For this reason, for example, in multi-charged electron beam exposure equipment, the distance between the screen lens and the sample is 1 to 2.
+1 for the fact that it is physically difficult to install a mass separator if the mass is about cm! ! There was a problem.

The present invention has been made in view of the above-mentioned points, and provides an alignment mark detection method that allows alignment of an exposed object even when the space near the exposed object is narrow in a charged electron beam exposure apparatus or the like. and equipment.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an alignment mark position detection method in which the position of an alignment mark on the substrate is detected by irradiating a charged electron beam onto the substrate. A charged electron beam is irradiated onto the alignment mark formed on the substrate, and a current change position where the current flowing through the substrate changes due to secondary electrons and secondary ions emitted from the substrate and the alignment mark is detected, and the current change position is detected. and information on a deflection voltage for deflecting the charged electron beam, the position of the alignment mark is read,
In an alignment mark position detection device that irradiates a charged electron beam onto a substrate and detects the position of an alignment mark on the substrate, when the substrate and the alignment mark formed on the substrate are irradiated with the charged electron beam, and alignment] - Current change position detection means for detecting a current change position where the current flowing through the substrate changes due to secondary electrons and secondary ions emitted from the mark, and deflecting the current change position and the charged electron beam. and alignment mark position reading means for reading the position of the alignment mark based on the deflection voltage information.

(Function) When the substrate and alignment mark are irradiated with the charged electron beam, a current change position where the current flowing through the substrate changes due to the emitted secondary electrons and secondary ions is detected, and this current change position and the charge electron beam are The alignment mark position is read based on the deflection information.

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

FIG. 1 is a block diagram of a main part of a charged electron beam exposure apparatus to which the alignment mark position detection force method of the present invention is applied. In the figure, reference numeral 1 denotes an ion source that outputs an ion beam (charged electron beam) 2. Below the ion source 1, an aperture 2, an electrostatic lens 3, and a deflector 4 are arranged in this order.

Further, the sample (exposed object) 5 to be exposed by the ion beam 21 is transferred to the X-Y table 5 by the vacuum chuck 7.
The vacuum chuck 7 and the XY table 6 are insulated from each other. The vacuum chuck 7 is a current detector 9
It is connected to the negative electrode of a power source 16 (for example, one that generates a voltage of about 10 KV) through the power source 16, and the positive electrode of the power source 16 is connected to ground. The two consecutive borrowing elements 1 to 9 and 16 are housed in a vacuum chamber 10, and the vacuum chamber 10 is heated to a predetermined pressure (for example, 10"
□ 4 to 10-7 [TORR]) The ion source generates ions (charge electrons) and
The ions are output as a predetermined ion beam 21, and in this embodiment, a positively charged ion beam is generated. The aperture 2 shapes the shape of the ion beam 2I, and the electrostatic lens 3 shapes the shape of the ion beam 2I.
is focused on two sides of sample 5. The deflector 4 deflects the ion beam 21 to scan the upper surface of the sample 5. X-Y
The table 6 is a table movable in X and Y directions perpendicular to each other, and moves the sample 5 to a predetermined irradiation position.

The current detector 9 detects the current I flowing from the vacuum chuck 7 to the negative electrode of the power source 16, and supplies the detection signal to the mark position calculation circuit (alignment mark position reading stage f) 12.

The output side of the deflection information generator 2g+4 is connected to the deflection controller l3 and the mark position calculation circuit 12, and supplies deflection information to these. The deflection controller 13 drives and controls the deflector 4 based on this deflection information. The mark position calculation circuit 12 calculates the position of the alignment mark 5b provided on the sample 5 as described later based on the deflection information and the current detection signal from the current detector 9, and determines the drawing position of the sample 5. The 6X-Y table controller 15 supplies X-Y table drive data to the X-Y table controller 15 as X-Y table drive data for correction.
Drive control of the X-Y table 6 according to Y table drive data.

A method for detecting alignment mark positions in the charged electron beam exposure apparatus configured as above will be described in detail below.

FIG. 2 is a diagram for explaining the alignment mark position detection knob method. In the figure, 5a is the substrate of the sample 5, and 5b is the alignment mark. In the illustrated example, the material of the substrate 5a is A (for example, silicon ), and the material of the alignment mark 5b is 13 different from A (for example, boron (B), which is a semiconductor impurity).

A region containing a large amount of phosphorus (P), arsenic (As), antimony (Sb), or aluminum (Aα), etc.).

When the surface of the sample 5 is irradiated with the ion beam 21 and scanned by the deflector 4 in the X-axis force direction shown by the arrow X in FIG. 2(b) based on the deflection information, the part irradiated by the ion beam 21 Secondary ions and secondary electrons corresponding to the material (in this case, positively charged secondary ions for both materials Δ and B) are emitted.

On the other hand, the current value I detected by the current detector 9 is given by the following equation (1).

1=I i-(i-1e)-(1) where 11. i and Ie are the current values of the ion beam 21.secondary ions and secondary electrons, respectively. Also, generally i
/ I e= 10-2~l O-' and Ie)i
holds true.

Therefore, between the substrate 5a and the alignment mark 5b, there are 2
Current value l due to secondary ions and secondary electrons.

Since re changes, the detected current value I changes (in this case, the contribution of changes in the secondary electron current re is particularly large). The mark position calculation circuit I2 calculates the boundary positions Xi, X2 in the X direction between the substrate 5a and the alignment mark 5b based on the change position of the current detection signal and the deflection information from the deflection information generator I4, Let (Xl+X2)/2 be the alignment mark position. Further, the position in the Y direction can also be calculated in the same manner as described above.

In the embodiment described above, the position of the current detector 9 is not particularly restricted, so even if a screen lens is provided directly above the sample as in a multi-charge electron beam exposure device, the alignment mark Position detection can be performed.

In addition, in the embodiment described above, the alignment mark 5b is made of a different material from the substrate 5a, but the material is not limited to this.
For example, by providing parts with different shapes such as recesses on the substrate 5a,
This may be used as an alignment mark. 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 mark position detection method or apparatus of the present invention, the alignment mark position is detected by detecting the change position of the current flowing through the substrate, so that the mass separator There is no need to provide a detector whose installation location is restricted, and alignment can be performed even when the space near the substrate is narrow.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a main part of a charged electron beam exposure apparatus to which the alignment mark position detection method of the present invention is applied, and FIG. 2 is a diagram for explaining the alignment mark position detection method. ]... Ion source (charge electron source), 4... Deflector, 5a
... Board, 5b... Alignment mark, 7...
Vacuum chuck, 9... Current detector, 12... Mark position calculation circuit (alignment mark position reading means),
13... Deflection controller, 14... Deflection information generator, 21... Ion beam (charge electron beam).

Claims (1)

[Claims] 1. In an alignment mark position detection method in which a charged electron beam is irradiated onto a substrate and the position of an alignment mark on the substrate is detected, the charged electron beam is irradiated onto the substrate and the alignment mark formed on the substrate. irradiate the substrate and detect the current change position where the current flowing through the substrate changes due to secondary electrons and secondary ions emitted from the substrate and the alignment mark, and detect the current change position and the deflection voltage for deflecting the charged electron beam. An alignment mark position detection method characterized in that the position of the alignment mark is read based on information. 2. In an alignment mark position detection device that irradiates a charged electron beam onto a substrate and detects the position of an alignment mark on the substrate, when the substrate and the alignment mark formed on the substrate are irradiated with the charged electron beam, the substrate and current change position detection means for detecting a current change position where the current flowing through the substrate changes due to secondary electrons and secondary ions emitted from the alignment mark, and the current change position;
An alignment mark position detection device comprising: alignment mark position reading means for reading the position of the alignment mark based on information on a deflection voltage for deflecting the charged electron beam.