JPH0737777A - Charged particle beam lithography method - Google Patents

Abstract

PURPOSE:To realize a charged particle beam lithography method which enables precision pattern generation in light screening pattern generation and also in shifter pattern generation. CONSTITUTION:A control computer 12 reads shifter pattern data from a memory 15 and a stage control circuit 9, a blanking control circuit 6 and a deflector control circuit 7 in accordance with data thereof. As a result, a stage 8 is moved properly, a deflection signal is supplied to a deflector 5 in accordance with data in a stop position of each stage, and electron beam is deflected. A shifter pattern is generated in a pattern generation material 3 by movement of the stage 8 and deflection and blanking of electron beam. In the shifter pattern generation, a height of the pattern generation material is measured. The height is measured by height measurement wherein a mark M is used while a height in the first light screening pattern generation is measured by applying an optical equation by a light source 13 and a height detector 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optimum charged particle beam writing method used for making a phase shift mask.

[0002]

2. Description of the Related Art In recent years, attention has been paid to the use of an exposure process using a phase shift mask in the manufacturing process of semiconductor devices. An electron beam drawing apparatus is usually used for producing the phase shift mask. To make this phase shift mask, first, chromium is vapor-deposited on a glass substrate and a resist is applied thereon. Next, an electron beam is drawn on the resist according to the light-shielding pattern, and the resist is developed and etched to form a light-shielding pattern of chromium on the glass substrate.

Next, a shifter material (for example, SOG, SiO) is formed on the glass substrate on which the chrome light shielding pattern is formed.
₂ ) is provided and a resist is further applied thereon. Then, an electron beam is drawn according to the shifter pattern, and the resist is developed or etched to provide the shifter pattern on the glass substrate on which the light shielding pattern is formed.

[0004]

By the way, in the electron beam drawing, the height of the material to be drawn is measured, and the deflection width of the electron beam is adjusted according to the height. For this reason,
The height of the substrate surface is measured prior to the first drawing operation of the light shielding pattern. This height measurement is performed by an optical system in which the substrate is irradiated with light and the reflected light is detected. However, when the height is measured at the time of drawing the shifter pattern by this optical height measuring method, a light-shielding pattern made of chrome is partially formed on the substrate, and the amount of light reflection at the chrome portion is small. The reflection of light from the large, chrome-excluded areas is extremely low. Therefore, it has a drawback that accurate height measurement cannot be performed.

The present invention has been made in view of the above points, and an object thereof is to perform accurate height measurement by accurately measuring the height both when drawing a light-shielding pattern and when drawing a shifter pattern. It is to realize a charged particle beam drawing method that can be performed.

[0006]

According to the charged particle beam drawing method of the present invention, a light shielding material is provided on a transparent substrate, a resist is applied on the light shielding material, and then a light shielding pattern is drawn by the charged particle beam. A first drawing step to be performed, a shifter material is provided on a transparent substrate on the surface of which a light-shielding material corresponding to the pattern is formed by an etching treatment after the first drawing step, and a resist is applied on the shifter material. In the charged particle beam drawing method including the second drawing step of drawing the shifter pattern by the charged particle beam, the optical height of the charged particle beam is measured in the first drawing step. The deflection width is set, and drawing for forming marks other than the light-shielding pattern is performed. At the time of the second drawing step,
The position of the mark formed based on the drawing of the mark in the first drawing step is detected by the charged particle beam, the height of the drawing material is measured, and the deflection width of the charged particle beam is set. There is.

[0007]

In the charged particle beam drawing method according to the present invention, an optical height detection method is used when drawing a light-shielding pattern, and height measurement is performed by detecting the position of a mark when drawing a shifter pattern. Go and do accurate drawing.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 shows an example of an electron beam writing system for carrying out the method according to the invention. In the figure, 1 is an electron gun, and an electron beam E generated from the electron gun 1.
B is finely focused on the drawing material 3 by the electron lens 2. The blanking electrode 4 and the deflector 5 are arranged along the optical axis of the electron beam EB. A blanking signal is supplied from the blanking control circuit 6 to the blanking electrode 4, and the deflector 5 is deflected. A deflection signal is supplied from the control circuit 7.

The drawing material 3 is placed on the moving stage 8. The moving amount and the moving direction of the moving stage 8 are controlled by the stage control circuit 9. The moving amount of the moving stage 8 is constantly monitored by the laser length measuring device 10.

The backscattered electrons generated by irradiating the material 3 with the electron beam are detected by the backscattered electron detector 11, and the detection signal is supplied to the control computer 12. Reference numeral 13 denotes a light source. Light from the light source 13 is applied to the material 3 to be drawn, and light reflected by the material 3 is detected by the height detector 14.

A signal according to the height from the height detector 14 is supplied to the control computer 12. The control computer 12 reads the pattern data stored in the memory 15 and supplies it to the pattern transfer circuit 16. A blanking signal corresponding to the pattern data from the pattern transfer circuit 16 is sent to the blanking control circuit 6, and a deflection signal is sent to the deflector control circuit 7. The operation of such a configuration will be described below.

First, as the material 3 to be drawn, there is prepared a material in which a transparent conductive film is coated on a glass substrate, chromium is vapor-deposited thereon as a light shielding material, and a resist is further coated thereon. And the control computer 12
Reads out the light-shielding pattern drawing data from the memory 15 and controls the stage control circuit 9, the blanking control circuit 6, and the deflector control circuit 7 in accordance with the pattern data.

As a result, the stage 8 is appropriately moved, a deflection signal is supplied to the deflector 5 according to the pattern data at the stop position of each stage, and the electron beam is deflected. The electron beam is blanked by the blanking electrode 4 when the stage 8 moves. Due to the movement of the stage 8 and the deflection and blanking of the electron beam, a light-shielding pattern is drawn on the drawing material 3.

This drawing is carried out for each field of the electron beam, but the light from the light source 13 is always applied to the surface of the material 3 to be drawn during the drawing for each field.
The light from the light source 13 is reflected by the surface of the material 3, and the reflected light is incident on the height detector 14. At this time, the incident position of the reflected light on the height detector 14 changes according to the height of the surface of the material 3. Therefore, in the height detector 14, the material 3 changes depending on the position of the incident light. The position of the surface is detected.

A signal according to the height from the height detector 14 is supplied to the control computer 12. The control computer 12 adjusts the deflection width of the deflector 5 according to the height of the surface of the material 3. When the drawing of the desired light-shielding pattern is completed, the material 3 is taken out of the apparatus, and well-known processes such as resist development and etching are performed to form a chrome light-shielding pattern on the glass substrate.

In the electron beam drawing process described above,
Positioning marks are also drawn in addition to the light-shielding pattern. FIG. 2 shows a plan view of the material 3 created by such drawing and a series of subsequent processes. In the example of FIG. 2, the light-shielding pattern portion P made of chromium and the cross mark M also made of chromium are formed on the glass substrate G.
1 to M3 are formed.

Next, the light shielding pattern portion P and the mark M
A shifter material is provided on the substrate G on which 1 to M3 are formed, and a resist is further applied thereon. FIG. 3 shows a cross section of the drawing material 3 provided with the shifter material and the resist. A transparent conductive film E for preventing charge-up is provided on the substrate G, a light-shielding pattern portion P of chromium and a mark M are formed thereon, and a shifter material S and a resist R are further provided thereon. And are provided in order. Such a material to be drawn is placed on the moving stage 8.

In drawing the material 3 to be drawn shown in FIG. 3, first, the control computer 12 reads the shifter pattern data from the memory 15 and, in accordance with the data, the stage control circuit 9, the blanking control circuit 6 and the deflector. The control circuit 7 is controlled. As a result, the stage 8 is appropriately moved, a deflection signal is supplied to the deflector 5 in accordance with the shifter pattern data at the stop position of each stage, and the electron beam is deflected. The electron beam is blanked by the blanking electrode 4 when the stage 8 moves. Due to the movement of the stage 8, the deflection of the electron beam, and the blanking, a shifter pattern is drawn on the drawing material 3.

Prior to drawing this shifter pattern,
The position of the alignment mark M is detected. The mark position is detected by scanning the electron beam on the mark portion and detecting the reflected electrons from the mark portion.
After detecting the mark position, the shifter pattern is superimposed and drawn by accurately positioning it with respect to the light-shielding pattern formed first.

When drawing the shifter pattern described above, the height of the material to be drawn is measured. This height measurement was performed using the optical method using the light source 13 and the height detector 14 while the height measurement at the time of drawing the first light shielding pattern was performed, while the height measurement using the mark M was performed. Be seen. The principle of this height measurement will be described with reference to FIG.

First, with respect to the drawing material on which the light-shielding pattern P and the three marks M1 to M3 shown in FIG. 2 are formed,
The optical axis is aligned with the first mark M1 portion. Then, this mark position is 1 / of the field size (f)
Move the stage 8 by 2 to move it to the left. As a result, the position of the mark M1 becomes the position of a in FIG. At this time, the moving amount of the stage 8 is accurately measured by the laser length measuring device 10, and the stage 8 accurately measures f /
It is shifted by 2.

Next, the electron beam is deflected by f / 2, and the electron beam is scanned in this state to find the position of the mark M1.
The mark position is measured by scanning the electron beam on the mark portion and detecting the reflected electrons from the mark portion with the detector 11. After the position of the mark M1 in a is measured based on the scanning of the electron beam, the stage is moved to the right, and the mark position is moved to the right side of the optical axis by f /
It is shifted by 2. At this time, the position of the mark M1 becomes the position of b in FIG. Then, in this state, the electron beam is deflected by f / 2, and the electron beam is scanned to find the position of the mark M1 at b.

Through this series of measurement, the difference Δf between the reference field size f (the distance actually moved the mark portion) and the distance obtained by the two mark position detections is measured. When the distance from the deflector 5 to the reference height surface of the material 3 is H, the deviation amount ΔH of the height H is calculated by the following equation.

ΔH = (Δf / f) · H This height deviation ΔH is obtained for each of the marks M1 to M3. The control computer 12 creates a height correction table for the entire surface of the material based on the obtained height information of the three marks. At the time of actual drawing, drawing is executed while adjusting the deflection width of the electron beam based on this correction table.

Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment. For example, although the present invention has been described using the electron beam writing system as an example, the present invention may be implemented using an ion beam writing system. Further, although the example in which three marks are formed in the field has been described, the height of a single mark may be corrected by measuring the height of a single mark. (6 pieces), the heights of many marks may be measured, and then the distortion of the material may be corrected by high-order polynomial approximation. Furthermore, the height correction may use an arithmetic method based on an approximate expression instead of the table method.

[0026]

As described above, the charged particle beam drawing method according to the present invention uses an optical height detection method to draw a light-shielding pattern when a light-shielding pattern having no mark is formed. At the same time, the mark was drawn to form the mark, and when drawing the shifter pattern, the height was measured by detecting the position of the mark.
The height can be measured accurately without being affected by the condition of the material surface even when the shifter pattern is drawn, which could not be measured accurately by the optical height measurement. As a result, both the light-shielding pattern and the shifter pattern can be accurately drawn.

[Brief description of drawings]

FIG. 1 shows an example of an electron beam writing system for carrying out the method according to the invention.

FIG. 2 is a diagram showing a light-shielding pattern and marks formed on a glass substrate.

FIG. 3 is a diagram showing a material to be drawn provided with a shifter material and a resist.

FIG. 4 is a diagram for explaining the principle of height measurement.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electron gun 2 Electron lens 3 Drawing material 4 Blanking electrode 5 Deflector 6 Blanking control circuit 7 Deflector control circuit 8 Moving stage 9 Stage control circuit 10 Laser length measuring device 11 Reflection electron detector 12 Control computer 13 Light source 14 Height detector 15 Memory 16 Pattern data transfer circuit

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location 7352-4M 528

Claims (1)

[Claims] 1. A first drawing step in which a light-shielding material is provided on a transparent substrate, a resist is applied to the light-shielding material, and then a light-shielding pattern is drawn by a charged particle beam, and after the first drawing step. A shifter material is provided on a transparent substrate on the surface of which a light-shielding material corresponding to the pattern is formed by etching or the like, a resist is applied to the shifter material, and a shifter pattern is drawn by a charged particle beam. In the charged particle beam drawing method including the drawing step described above, the deflection height of the charged particle beam is set after the optical height is measured in the first drawing step, and a mark is formed in addition to the light shielding pattern. Drawing for the purpose of performing the drawing, and in the second drawing step, the position of the mark formed based on the drawing of the mark in the first drawing step is loaded. A charged particle beam drawing method in which the height of a drawing material is detected by an electron particle beam and the deflection width of the charged particle beam is set.