JPH0279412A - Alignment mark position detection and device therefor - Google Patents

Abstract

PURPOSE:To improve the detection accuracy of an alignment mark position by detecting an emitted ion kind change position where the kinds of emitted secondary ions changes when charged electron beams are applied to a substrate and an alignment mark so as to read the alignment mark position based on this emitted ion kind change position and the charged beam deflection information. CONSTITUTION:When ion beams 21 are applied to the surface of a sample 5 and are scanned in the direction of an X axis based on the deflection information by a deflecting system 4, secondary ions A<+> and B<+> in accordance with the material quality of the part irradiated with ion beams 21 are emitted and are entered into a mass separator 7. The ions B<+> which are separated and detected by the mass separator 7 are supplied to a mark position calculating circuit 12 as a secondary ion detection signal through an electron doubling tube 8 and a current detector 9. The mark position calculating circuit 12 calculates the boundary positions x1 and x2 in the X direction of a board 5 and an alignment mark based on this secondary ion detection signals and the deflection information from a deflection information preparator 14, and makes (x1+x2)/2 an alignment mark position. Also, the positions in Y direction can be calculated similarly.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method and apparatus for detecting an alignment mark position in a charged electron beam exposure apparatus or the like that draws fine patterns on a wafer such as an integrated circuit element or a mask substrate.

(Prior Art) In a charged electron beam exposure apparatus, it is important to accurately position (align) a wafer or the like 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. As a method for detecting the alignment mark position, a method has been proposed in which a mark is formed on the substrate using a luminescent material that emits light when irradiated with an electron beam, a laser beam, etc., and the mark position is detected by receiving light from the mark. (For example, JP-A-63-10
Publication No. 2316).

FIG. 5 is a diagram showing an outline of the conventional mark position detection method, in which 51 is a substrate, 52 is a mark formed of a luminescent material, 53 is a resist that blocks the beam in areas where beam irradiation is unnecessary, and 54 is a load. The electron beam 55 is a photocell that receives light from the mark. In the method shown in FIG. 5, the photocell 55 receives the light emitted from the mark 52 by scanning the mark 52 with the charged electron beam 54, detects the edge positions ff1c and D of the mark 52, and detects the edge positions ff1c and D of the mark 52 (C
+D)/2 is set as the mark position.

(Problem to be Solved by the Invention) In the conventional mark position detection method described above, since the mark 52 forms a convex portion on the substrate, the resist 53 is also lifted by the mark portion, creating a thin portion and a thick portion of the resist, and the mark is There is a problem in that the edges of No. 52 are substantially sagging (the edge portions are optically widened). Furthermore, since a photocell is used as the detection means, the accuracy of position detection is low, and this, along with the sagging of the mark edge, is a factor that reduces the accuracy of mark position detection. In addition, the material of the mark is limited to a luminescent material (for example, 1nP), which has restrictions on the type of material, and there is also the problem that the mark cannot be easily manufactured.

The present invention has been made to solve the above problems, and provides an alignment mark position detection method that has high alignment mark position accuracy, is easy to manufacture, and improves the detection accuracy of the alignment mark position. An object of the present invention is to provide a method and apparatus.

(Means for Solving the Problems) To achieve the above object, the present invention provides an alignment mark position detection method for detecting the position of an alignment mark on a substrate by irradiating a charged electron beam onto the substrate. A charged electron beam is irradiated onto an alignment mark formed of a material different from that of the substrate, and the position of change in the radiation ion species of secondary ions emitted from the substrate and the alignment mark is detected. An alignment mark position detection device that reads the position of the alignment mark based on information on a deflection voltage for deflecting a charged electron beam, or irradiates a charged electron beam onto a substrate and detects the position of the alignment mark on the substrate. When a valence electron beam is irradiated on a substrate and an alignment mark formed on the substrate using a material different from the substrate,
radiation ion species change position detection means for detecting a radiation ion species change position of secondary ions emitted from the substrate and the alignment mark; information on the radiation ion species change position and a deflection voltage for deflecting the charged electron beam; alignment mark position reading means for reading the position of the alignment mark based on the alignment mark position.

The radiation ion species change position detection means may include ion separation detection for separately detecting first secondary ions emitted from the substrate and second secondary ions emitted from the alignment mark. an electron multiplying means for converting the separated and detected secondary ions into electrons and multiplying the electrons; and a current detecting means for detecting the output of the electron multiplier as a current. is desirable.

(Function) When the substrate and alignment mark are irradiated with a charged electron beam, the position where the type of emitted secondary ions changes is detected, and the position where the emitted ion species changes is combined with the deflection information of the charged electron beam. Based on this, the alignment mark position is read.

In addition, either the first secondary ion emitted from the substrate or the second secondary ion emitted from the alignment mark is separated and detected, and the separated and detected secondary ion is converted into an electron and multiplied. This is detected as a large current, and the position of change in the emitted ion species of the secondary ions is detected.

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

FIG. 1 is a schematic configuration diagram of a charged electron beam exposure apparatus to which the alignment mark position detection method of the present invention is applied, in which 1 is an ion source (charged electron source), 2 is an aperture, 3 is an electrostatic lens, 4 is a deflector, 5 is a sample (for example, a resist-coated silicon wafer or a silicon wafer), and 6 is an x-
Y table, 7 is a mass separator (ion separation detection means),
8 is an electron multiplier tube (electron multiplier), 9 is a current detector (radio wave detection means), 10 is a vacuum chamber, and 11 is an exhaust device.

The ion source l 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 21, and the electrostatic lens 3 shapes the shape of the ion beam 21.
is focused on the upper surface of sample 5. The deflector 4 deflects the ion beam 21 to scan the upper surface of the sample 5. The X-Y 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 mass separator 7 collects secondary ions generated from the sample 5 by irradiating the sample 5 with the ion beam 21.
As will be described later, only desired ions are detected using the difference in mass of the secondary ions and supplied to the electron multiplier 8. The electron multiplier tube 8 is based on the principle shown in FIG. 4, and outputs several thousand times more electrons than the incident ions.

41 in Figure 4 is, for example, length 0.481Wl, inner diameter 12
It is a cylindrical glass wall with a diameter of approximately μm, and a voltage is applied so that the input side thereof has a negative potential with respect to the output side.

When ions enter from the input side and collide with the glass wall 41, secondary electrons are generated, and while repeating collisions, the secondary electrons are attracted by the potential gradient and reach the output side. At this time, each time an electron collides with the glass wall, secondary electrons are emitted from the wall surface, so the output electrons are several thousand times or more larger than the incident ions.

The current detector 9 converts the output electrons of the electron multiplier tube 8 into a current and sends it as a secondary ion detection signal to the mark position calculation circuit 12.
(alignment mark position reading means). The vacuum chamber 10 houses the above-mentioned components 1 to 9,
A predetermined pressure (for example, io- to 10-
”[yoRt] ).

The output side of the deflection information generator 14 is connected to the deflection controller 13 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 uses the deflection information and the two from the current detector 9.
Based on the next ion detection signal, sample 5 is
The position of the alignment mark provided on the sample 5 is calculated and supplied to the X-Y table controller 15 as X-Y table drive data for correcting the drawing position of the sample 5. The X-Y table controller 15 drives and controls the X-Y table 6 according to the X-Y table drive data.

A method for detecting alignment marks in the charged electron beam optical system configured as above will be described in detail below.

FIG. 2 is a diagram showing an outline of the alignment mark position detection method, in which 5a is the substrate of the sample 5, and 5b is the alignment mark. The material of the substrate 5a is A (for example, silicon), and the material of the alignment mark 5b is B (for example, it contains a large amount of semiconductor impurities such as boron (b), phosphorus (P), arsenic (As), and antimony (sb)). or aluminum (AQ), 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 direction (not indicated by arrow X in FIG. 2) based on the deflection information, the material of the portion irradiated with the ion beam 21 Secondary ions A'' and B' are emitted according to the material (here, material A).

Both B emit positively charged secondary ions), mass separator 7
is incident on the

FIG. 3 is a diagram showing the operating principle of this mass separator 7,
In the figure, 31 is an electrostatic lens (a coil may be used). Ions A" and B" incident on the mass separator 7 are deflected by the electrostatic lens 31, but ions with lighter mass are deflected more than heavier ions, so for example, if ion B7 is lighter, As shown in the figure, the ion B+
The ion 80 passes through the slit 32 near the electrostatic lens 31, while the ion 80 passes through the slit 33 farther away. Therefore, by extracting only the ions that have passed through the slit 32, it is possible to separate and detect only the ions B+.

Ions B1 separated and detected by the mass separator 7 are supplied to the mark position calculation circuit 12 as a secondary ion detection signal via the electron multiplier 8 and the current detector 9, as described above. The mark position calculation circuit 12 calculates the boundary positions XI and X2 in the X direction between the substrate 5a and the alignment mark 5b based on this secondary ion detection signal and the deflection information from the city information generator 14, Let (X1+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 above-mentioned embodiment, an example was shown in which positively charged secondary ions are generated as the material B, but the material is not limited to this, and for example, 5ia
N4. A material that generates negatively charged secondary ions (nitrogen ions, oxygen ions), such as SiO, may also be used.

In addition, although secondary ions have been described as detection targets, any detection target may be used as long as it is possible to irradiate a charged electron beam and determine the difference in the material.For example, characteristic X-rays, Auger electrons, etc. can be detected.
It can also be performed in the same manner as the alignment method using secondary ions described above.

(Effects of the Invention) As described in detail above, the present invention provides an alignment mark position detection method for detecting the position of an alignment mark on a substrate by irradiating a charged electron beam onto the substrate. Alignment marks formed of different materials are irradiated with a charged electron beam, the position of change in the radiation ion species of secondary ions emitted from the substrate and the alignment mark is detected, and the position of change in the radiation ion species and the charged electron beam are detected. In an alignment mark position detection device that detects the position of the alignment mark on the substrate by irradiating a charged electron beam onto the substrate and reading the position of the alignment mark based on the information of the deflection voltage to be deflected, And is there a load on the alignment mark formed on the substrate using a material different from that of the substrate? radiation ion species change position detection means for detecting the radiation ion species change position of secondary ions emitted from the substrate and the alignment mark when irradiated with the LT-beam; Since the alignment mark position reading means is provided to read the position of the alignment mark based on the information of the deflection voltage to be deflected, the material of the alignment mark may be a material different from that of the substrate, and is limited to a luminescent material. It is possible to select from a wide range without any problems, and it is possible to easily manufacture alignment marks with high precision. Furthermore, since the position where the emitted ion species of the secondary ions change is detected as an electric signal such as a current, it is possible to improve the alignment mark position detection accuracy.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a charged electron beam n-optical device to which the alignment mark position detection method of the present invention is applied, Fig. 2 is a diagram showing an overview of the alignment mark position detection method of the present invention, and Fig. 3 is a mass separation diagram. FIG. 4 is a diagram showing the operating principle of an electron multiplier tube, and FIG. 5 is a diagram showing an outline of a conventional mark position detection method. ■... Ion source (charge electron source), 4... Deflector, 5a
... Board, 5b... Alignment mark, 7...
Mass separator (ion separation detection means), 8... Electron intensifier tube (1 stage of electron multiplication), 9... Current detector (current detection means), 12... Mark position calculation circuit (alignment mark position) reading means), 13... deflection controller,
I4... Deflection information generator, 21... Ion beam (
charged electron beam).

Claims (1)

[Claims] 1. 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, which includes: a substrate and an alignment mark formed on the substrate from a material different from that of the substrate; irradiating the mark with a charged electron beam, detecting a change position of the emitted ion species of secondary ions emitted from the substrate and the alignment mark, and obtaining information on the change position of the emitted ion species and a deflection voltage for deflecting the charged electron beam; An alignment mark position detection method characterized by reading the position of the alignment mark based on. 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, the charged electron beam is applied to the substrate and an alignment mark formed on the substrate using a material different from that of the substrate. Radiation ion species change position detection means for detecting the radiation ion species change position of secondary ions emitted from the substrate and the alignment mark when irradiated, the radiation ion species change position and a deflection voltage that deflects the charged electron beam. and alignment mark position reading means for reading the position of the alignment mark based on the information. 3. The radiation ion species change position detection means is an ion separation detection means for separating and detecting the first secondary ions emitted from the substrate and the second secondary ions emitted from the alignment mark. and an electron multiplier that converts the separated and detected secondary ions into electrons and multiplies them;
3. The alignment mark position detection device according to claim 2, further comprising current detection means for detecting the output of said electron multiplier as a current.