JP2015126004A - Test piece for calculating electron scattering distance and method for calculating electron scattering distance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a test piece for calculating an electron scattering distance, used for calculating the distribution state of backscattered electron beams that cause a fogging effect in an electron beam exposure system and is incident to a surface of a drawing subject within a chamber of the electron beam exposure system.SOLUTION: A test piece 1 for calculating an electron scattering distance is used for calculating the distribution state of backscattered electron beams that is incident to a surface of a drawing subject within a chamber of an electron beam exposure system. The test piece 1 for calculating an electron scattering distance is obtained by forming a light shielding layer 6 and a resist layer 7 on a transparent substrate 5 and further coating an electron beam sensitive material 8.

Description

  The present invention relates to a method for calculating an electron scattering distance based on a fogging effect of an electron beam exposure apparatus, and more particularly to a method for calculating an electron scattering distance based on a fogging effect using a material that is sensitive when irradiated with an electron beam.

  In semiconductor integrated circuits, in order to improve the degree of integration and reduce power consumption, circuit patterns formed on a wafer are being miniaturized using various resolution improvement techniques. At present, a circuit pattern having a dimension far below the wavelength (193 nm) of an ArF excimer laser, which is an exposure light source used when exposing and transferring a circuit pattern to a wafer, has been formed.

  Against this background, in order to achieve the miniaturization of the pattern formed on the wafer, the miniaturization of the pattern is also required in the photomask used for exposure transfer in the semiconductor lithography process.

In addition to the demand for pattern miniaturization, the process margin in the lithography process has been narrowed with the miniaturization of semiconductor circuit patterns on the wafer. The mask is manufactured by applying a resist having sensitivity to electrons or the like to the photomask blank 11 shown in FIG. 4 in which a light-shielding film is formed on a transparent substrate, and passing through a drawing / developing / etching process using the electron beam 4. A semiconductor circuit pattern of the metal light shielding layer 6 is formed on the transparent substrate 5.

  In the photomask drawing process, 7 resists are applied to the photomask blank 11 using an electron beam exposure apparatus based on the circuit pattern data, the circuit pattern is drawn, and the patterning of the light shielding layer is performed by the development and etching processes. Done.

  When a circuit pattern is drawn, a fogging effect can be cited as a phenomenon that affects the pattern dimension accuracy. FIG. 2 shows the irradiation of the electron beam, and the fogging effect is that the electron beam 4 irradiated from the electron beam exposure apparatus is reflected by the photomask substrate 14 and hits the objective lens 3 for focusing the electron beam 4, The scattered electrons are irradiated again on the photomask substrate 14 and a circuit pattern having a desired line width cannot be transferred, and reflected electrons in the chamber become noise. This phenomenon occurs due to the density of the circuit pattern, which degrades the circuit pattern dimension accuracy on the photomask.

  Therefore, in the electron beam exposure apparatus, the exposure amount of the electron beam is adjusted by the density of the circuit pattern as a correction of the fogging effect. The fogging effect is corrected within an electron scattering distance range of about several tens of mm (Patent Document 1).

  Usually, in order to calculate the electron scattering distance of the fogging effect, by drawing a test pattern on the photomask substrate 14 in which the resist 7 is applied to the photomask blank 11 and measuring the pattern line width after development processing, The electron beam scattering distance of the fogging effect is calculated.

  However, with further miniaturization, it is necessary to accurately calculate the electron scattering distance of the fogging effect in order to improve the circuit pattern dimension accuracy on the photomask.

  As described above, according to the calculation method of the electron scattering distance of the fogging effect so far, what has actually undergone the drawing and developing process is evaluated, and the electron scattering distance is calculated based on the evaluation result.

  For this reason, the influence of non-uniform components in the mask surface depending on the process such as development loading due to the difference in the irradiation area ratio of the electron beam 4 and the flow of the developer in the development apparatus, and the measurement instrument by measuring the pattern size after development processing Since an error occurs, it is difficult to calculate an electron scattering distance due to an accurate fogging effect.

JP 2009-192684 A

  The present invention has been made in order to solve the above-described problem, and is a cause of the fogging effect in the electron beam exposure apparatus. The reflected electron beam incident on the surface of the drawing target in the chamber of the electron beam exposure apparatus. An object of the present invention is to provide an electron scattering distance calculation specimen used for calculating a distribution state.

As a means for solving the above problems, the invention according to claim 1 is an electron scattering distance calculation used for calculating a distribution state of a reflected electron beam incident on a surface of a drawing object in a chamber of an electron beam exposure apparatus. Test specimen,
An electron scattering distance calculation specimen, wherein a light shielding layer and a resist layer are formed on a transparent substrate, and an electron beam sensitive material is further applied.

  According to a second aspect of the present invention, the electron beam sensitive material is a phosphor material, and contains at least one of silver, copper, manganese, aluminum, calcium, magnesium, cerium, potassium, and terbium elements. The electron scattering distance calculation test piece according to claim 1, wherein:

  The invention according to claim 3 is the electron according to claim 1, wherein the electron beam sensitive material is a phosphorescent material and contains at least one of titanium, magnesium, calcium, and potassium elements. This is a scattering distance calculation specimen.

The invention according to claim 4 is the electron scattering distance calculation test body according to any one of claims 1 to 3,
Irradiating a predetermined position with an electron beam from an electron beam exposure apparatus; and
Detecting a position coordinate of a range emitted by irradiation;
An electron scattering distance calculation method comprising: calculating an electron scattering distance from a light emission range.

  Compared to the conventional method that calculates the electron scattering distance by evaluating the actual drawing and development process, the photomask blank is used by the method for calculating the electron scattering distance of the fogging effect by the electron beam exposure apparatus of the present invention. Instead, by recording the position coordinates of the range by the light emission by irradiation, the electron scattering distance due to the fogging effect can be accurately calculated, and it is possible to avoid wasting an expensive photomask blank.

It is a section conceptual diagram showing composition of a specimen for electron scattering distance calculation of the present invention. It is the conceptual diagram which showed irradiation of the electron beam to the test body for electron scattering distance calculation of this invention. It is a conceptual diagram which shows an example of the calculation method of the electron scattering distance by the fogging effect of this invention. It is a cross-sectional conceptual diagram of a photomask blank. It is a top surface conceptual diagram of the test body for electron scattering distance calculation used in the example.

  Hereinafter, an example of the process flow regarding the calculation method of the electron scattering distance by the fogging effect in the form of this invention is shown. In FIG. 1, the conceptual diagram of the fog measurement which concerns on this embodiment is shown. In the fog measurement, the same configuration as that used when irradiating a target substrate such as a photomask blank coated with a normal resist is used, but in this embodiment, instead of the target substrate as shown in the figure. An electron scattering distance calculation specimen 1 is used.

  In such a configuration, the electron beam 4 is irradiated from the electron gun to a predetermined position of the measurement mask 1 through the plurality of apertures and deflectors and the objective lens 3. A backscattered electron prevention plate 2 is provided on the surface of the objective lens 3 facing the measurement mask 1.

  FIG. 1 shows an electron scattering distance calculation specimen 1 according to the present invention. As shown in FIG. 1, a light-shielding film 6 is formed on a transparent substrate 5, a resist layer 7 sensitive to electrons or the like is applied, and a measurement mask 1 in which a phosphor material 8 is further applied thereon is used.

  The measurement mask 1 is irradiated with an electron beam at a predetermined position as shown in FIG. FIG. 3 shows a method for calculating the electron scattering distance. When the electron scattering distance calculation specimen 1 is irradiated with the electron beam 4, the electron beam sensitive material 8 of the electron scattering distance calculation specimen 1 emits light or The recording device 10 records the position coordinates of the range 9 that is emitted by this irradiation.

  As the electron beam sensitive material 8, a fluorescent material that converts external energy into light, or a phosphorescent material that is also called phosphorescence, and that continues to emit light after the disappearance of excitation light such as ultraviolet light and visible light, can be used. Fluorescent materials containing any of copper, manganese, aluminum, calcium, magnesium, cerium, potassium, and terbium elements, and phosphorescent materials containing any of titanium, magnesium, calcium, and potassium elements are suitable.

  The electron scattering distance due to the fogging effect is obtained from the information of the recorded position coordinates.

  According to the present embodiment, it is possible to calculate the electron scattering distance of the fogging effect without being affected by development loading, in-plane non-uniform component depending on the process, and measurement instrument error due to pattern dimension measurement after development. It becomes.

  Hereinafter, the present invention will be described with reference to the drawings. First, FIG. 1 shows a specimen 1 for calculating an electron scattering distance of the present invention.

  A photomask blank is prepared in which a light-shielding film 6 is formed on a quartz glass, which is a transparent substrate 5 having a size of 6 inches × 6 inches × 0.25 inches, using a sputtering apparatus to form a 65 nm film of molybdenum silicide and chromium. To do.

  Next, a positive chemically amplified resist 7 is applied to the photomask blank 11 with a film thickness of 150 nm.

  Next, a phosphor material 8 made of magnesium oxide is formed to a thickness of 10 nm on the resist 7 by magnetron sputtering in a gas atmosphere in which argon and oxygen are mixed with magnesium oxide as a target, and electron scattering is performed. A distance calculating test body 1 was formed.

  An electron beam is irradiated to the position of the mask center origin (X, Y) = (0 μm, 0 μm) by the electron beam drawing machine having the structure shown in FIG.

  By irradiation, the phosphor material which is the electron beam sensitive material 8 starts to emit light around the coordinates (X, Y) = (0 μm, 0 μm). As shown in FIG. 5, the phosphor material that is the electron beam sensitive material 8 also emitted light outside the electron beam irradiation position 12. The position coordinates of the light emission range 13 are recorded in the recording device 10. According to the recorded position coordinates, the distance from the electron beam irradiation position 12 was found to be 17879 μm. This value is the electron scattering distance of the fogging effect.

  By calculating the electron scattering distance of the fogging effect from this example, the fogging effect is not affected by development loading, non-uniform in-plane components depending on the process, and measurement error due to pattern dimension measurement after development. The electron scattering distance of the effect can be calculated.

DESCRIPTION OF SYMBOLS 1 ... Test body for electron scattering distance calculation 2 ... Reflection electron prevention board 3 ... Objective lens 4 ... Electron beam 5 ... Transparent substrate 6 ... Light shielding layer 7 ... Resist 8 ..Electron beam sensitive material 9 ... light emission or light storage range 10 ... recording device 11 ... photomask blank 12 ... electron beam irradiation position 13 ... light emission range 14 ... photo Mask substrate

Claims (4)

In a chamber of an electron beam exposure apparatus, an electron scattering distance calculation test body used for calculating a distribution state of a reflected electron beam incident on a surface to be drawn,
A specimen for electron scattering distance calculation, wherein a light shielding layer and a resist layer are formed on a transparent substrate, and further an electron beam sensitive material is applied.   2. The electron scattering according to claim 1, wherein the electron beam sensitive material is a fluorescent material and contains at least one of silver, copper, manganese, aluminum, calcium, magnesium, cerium, potassium, and terbium elements. Distance calculation specimen.   2. The electron scattering distance calculation specimen according to claim 1, wherein the electron beam sensitive material is a phosphorescent material and contains at least one of titanium, magnesium, calcium, and potassium elements. For the specimen for electron scattering distance calculation according to any one of claims 1 to 3,
Irradiating a predetermined position with an electron beam from an electron beam exposure apparatus; and
Detecting a position coordinate of a range emitted by irradiation;
An electron scattering distance calculation method comprising: calculating an electron scattering distance from a light emission range.