JP3083428B2 - Charged particle beam drawing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for writing a charged particle beam which is most suitable for use in producing a phase shift mask.

[0002]

2. Description of the Related Art In recent years, attention has been paid to using an exposure process using a phase shift mask in a process of manufacturing a semiconductor device. An electron beam lithography apparatus is usually used to create this phase shift mask. In order to create this phase shift mask, first, chromium is 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 or etched to form a chrome light-shielding pattern on the glass substrate.

[0003] Next, a shifter material (for example, SOG, SiO) is formed on a glass substrate on which a chrome light-shielding pattern is formed.
₂ ) is provided, and a resist is applied thereon. Then, an electron beam is drawn according to the shifter pattern, and a resist is developed or etched to form a shifter pattern on the glass substrate on which the light-shielding pattern is formed.

[0004]

In electron beam lithography, the height of the material to be drawn is measured, and the deflection width of the electron beam is adjusted in accordance with the height. For this reason,
Prior to the first light-shielding pattern drawing operation, the height of the substrate surface is measured. This height measurement is performed by an optical method that irradiates light onto the substrate and detects reflected light. However, when the height is measured at the time of drawing a shifter pattern using this optical height measurement method, a light-shielding pattern of chrome is partially formed on the substrate, and the amount of light reflection in the chrome portion is reduced. The reflection of light from the large, chrome-free area is extremely low. For this reason, there is a disadvantage that accurate height measurement cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to accurately measure the height both when writing a light-shielding pattern and when writing a shifter pattern, thereby achieving accurate writing. An object of the present invention is to realize a charged particle beam writing method that can be performed.

[0006]

According to the charged particle beam writing 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 having a light-shielding material corresponding to the pattern formed on a surface thereof by an etching process or the like after the first drawing step, and a resist is applied on the shifter material. In a charged particle beam writing method including a second writing step of writing a shifter pattern with a charged particle beam after the above, an optical height measurement is performed during the first writing step, and then the charged particle beam is written. The deflection width is set, and drawing for forming a mark other than the light shielding pattern is performed. In the second drawing step,
The position of the mark formed based on the mark drawing in the first drawing step is detected by a charged particle beam, the height of the drawing material is measured, and the deflection width of the charged particle beam is set. I have.

[0007]

The charged particle beam writing method according to the present invention uses an optical height detection method when writing a light-shielding pattern, and performs height measurement by detecting the position of a mark when writing a shifter pattern. Perform accurate drawing.

[0008]

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

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

The backscattered electrons generated by the irradiation of 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 irradiated on the material to be drawn 3, and light reflected by the material 3 is detected by a height detector 14.

A signal corresponding 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 the pattern data to the pattern transfer circuit 16. The blanking signal corresponding to the pattern data from the pattern transfer circuit 16 is sent to the blanking control circuit 6, and the deflection signal is sent to the deflector control circuit 7. The operation of such a configuration will now be described.

First, as a material 3 to be drawn, a glass substrate is coated with a transparent conductive film, chromium is deposited as a light-shielding material thereon, and a resist is further applied thereon. And the control computer 12
Reads the drawing data of the light shielding pattern from the memory 15 and controls the stage control circuit 9, blanking control circuit 6, and deflector control circuit 7 according to 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. By the movement of the stage 8, the deflection of the electron beam, and the blanking, a light-shielding pattern is drawn on the drawing target material 3.

This drawing is performed for each field of the electron beam. In drawing for each field, light from the light source 13 is always applied to the surface of the material 3 to be drawn.
Light from the light source 13 is reflected on the surface of the material 3, and the reflected light is incident on the height detector 14. At this time, since the incident position of the reflected light on the height detector 14 changes according to the height of the surface of the material 3, the height detector 14 changes the material 3 according to the position of the incident light. The position of the surface is detected.

A signal corresponding 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 a well-known process such as development or etching of a resist is performed to form a chrome light-shielding pattern on the glass substrate.

In the above electron beam drawing process,
In addition to the light-shielding patterns, alignment marks are also drawn. FIG. 2 shows a plan view of the material 3 created by such a drawing and a series of subsequent processes. In the example of FIG. 2, a light-shielding pattern portion P made of chrome and a cross mark M also made of chrome are formed on a 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 applied thereon. FIG. 3 shows a cross section of the drawing target 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, on which a light shielding pattern portion P of chromium and a mark M are formed, and further thereon, a shifter material S and a resist R Are provided in order. Such a material to be drawn is placed on the moving stage 8.

In drawing the material to be drawn 3 shown in FIG. 3, first, the control computer 12 reads shifter pattern data from the memory 15, and according to the data, the stage control circuit 9, blanking control circuit 6, 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 according to 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. The shifter pattern is drawn on the drawing target material 3 by the movement of the stage 8, the deflection of the electron beam, and the blanking.

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

When the shifter pattern is drawn, the height of the material to be drawn is measured. In this height measurement, the height measurement using the mark M is performed while the height measurement at the time of drawing the first light-shielding pattern is performed using an optical system using the light source 13 and the height detector 14. Will be The principle of this height measurement will be described with reference to FIG.

First, the material to be drawn on which the light shielding pattern P and the three marks M1 to M3 shown in FIG.
The optical axis is aligned with the first mark M1. Then, the mark position is set to 1 / f of the field size (f).
The stage 8 is shifted to the left by moving it by two. As a result, the position of the mark M1 becomes the position a in FIG. At this time, the amount of movement of the stage 8 has been accurately measured by the laser length measuring device 10, and the stage 8 has accurately measured f /
It is shifted by two.

Next, the electron beam is deflected by f / 2, and the position of the mark M1 is obtained by scanning the electron beam in this state.
The measurement of the mark position is performed by scanning the mark portion with an electron beam and detecting reflected electrons from the mark portion with the detector 11. After measuring the position of the mark M1 at position a, based on the scanning of the electron beam, the stage is moved to the right, and the mark position is now shifted to the right with respect to the optical axis.
It is shifted by two. At this time, the position of the mark M1 is the position b in FIG. Then, in this state, the electron beam is deflected by f / 2, and the position of the mark M1 at b is obtained by scanning the electron beam.

Through this series of measurements, the difference Δf between the reference field size f (the distance actually moved the mark portion) and the distance obtained by two mark position detections is measured. Assuming that 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 obtained by the following equation.

ΔH = (Δf / f) · H The 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 writing, writing is performed 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 an electron beam writing system as an example, the present invention may be implemented using an ion beam writing system. Also, an example in which three marks are formed in a field has been described. However, the height of a single mark may be corrected by measuring the height of a single mark. 6), and the distortion of the material may be corrected by high-order polynomial approximation after measuring the heights of a large number of marks. Further, the height correction may be performed not by the table method but by a calculation method using an approximate expression.

[0026]

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

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating a light-shielding pattern and a mark formed on a glass substrate.

FIG. 3 is a diagram showing a drawing material provided with a shifter material and a resist.

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

[Description of Signs] 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 backscattered electron detector 12 Control computer 13 Light source 14 Height detector 15 Memory 16 Pattern data transfer circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/027 G03F 1/08

Claims (1)

(57) [Claims] 1. A first drawing step of providing a light-shielding material on a transparent substrate, applying a resist on the light-shielding material, and writing a light-shielding pattern by a charged particle beam, and after the first writing step. A shifter material is provided on a transparent substrate having a light-shielding material corresponding to the pattern formed on the surface by an etching process or the like, a resist is applied on the shifter material, and a shifter pattern is drawn by a charged particle beam. In the charged particle beam writing method including the writing step, a deflection width of the charged particle beam is set after performing an optical height measurement in the first writing step, and a mark is formed other than the light shielding pattern. 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 writing method in which the height of a writing material is measured by detecting the charged particle beam and the deflection width of the charged particle beam is set.