JP2009063799A - Pattern forming method, pattern forming device, photomask and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means of forming a fine pattern with high accuracy while suppressing generation of an electric field without degrading the resolution of a resist on forming a pattern by irradiating a substrate having discontinuous electric conductivity with a charged particle beam. <P>SOLUTION: A conductive film 12 is formed on a second surface 10b which is a back face of a substrate 10 to be processed and a conductive pin 15 is brought into contact with the conductive film 12 to generate charges in the conductive film 12, the charges resisting against accumulated charges by irradiation with a charged particle beam 14, and thereby, to suppress deflection of the charged particle beam due to an electric field. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pattern forming method and a pattern forming apparatus for forming a pattern using a charged particle beam, a photomask patterned using a charged particle beam, and a manufacturing method thereof.

  In order to manufacture a semiconductor device, in a photolithography technique for processing a wafer, a pattern formed on a photomask is generally reduced to a quarter and transferred onto the wafer. With miniaturization of semiconductor devices, pattern miniaturization is always required for photomasks. In particular, with the introduction of so-called super-resolution technology in recent years, the pattern dimensions on the photomask have become finer and more accurate than those on the wafer, and it has become difficult to achieve this.

  FIG. 3 shows a conventional photomask manufacturing process. A light shielding film 21 made of a metal film is formed on the photomask substrate 20. In a super-resolution technique typified by a phase shift method or the like, after the light shielding film 21 is formed in a pattern, the light shielding film is covered with a resist (first resist 23) to form a pattern again.

  In the pattern formation, the electron beam lithography method using a charged particle beam can provide a higher resolution than the photolithographic method. On the other hand, when patterning is performed using a charged particle beam, there is a problem that a part of the charged charged particles stops in the resist and the patterning accuracy decreases. This is because the charged particle beam trajectory is bent as a result of the electric field generated by the charged particle beam remaining in the resist.

  Therefore, as shown in FIG. 3, resist is prevented from being charged by bringing a conductive pin 25 as a conductive means (generally, a pin made of metal, etc.) into contact with the light shielding film 21. The light shielding film 21 is formed of a conductive material such as chromium, and grounded by the conduction pin 25, the electric field generated by the irradiation of the charged particle beam is offset by the shielding effect. However, in the region where the light shielding film 21 is patterned in an island shape, an electric field (not shown) is generated because electrical grounding by the conduction pin 25 cannot be obtained. Since this electric field has an effect of deflecting the trajectory of the charged particle beam, it becomes a factor that a desired pattern cannot be obtained.

  Conventionally, when performing patterning while providing conduction to a substrate to be processed in which such a light shielding film is electrically discontinuous, a coating-type conductive film 22 is uniformly formed on the first resist 23, A method of canceling out the electric field by this shielding effect has been taken. However, the component constituting the conductive film 22 may cause an unintended reaction with the first resist 23 and a required fine pattern may not be obtained with high accuracy.

As another conventional technique, there is a means for removing the conductive film before the post-exposure baking for pattern formation in order to avoid the adverse effect of the conductive film (for example, Patent Document 1). Alternatively, there is a means for avoiding the influence by forming a film that blocks interference between the resist and the conductive film (for example, Patent Document 2).
JP 2003-307856 A JP 11-097325 A

  According to the technique described in Patent Document 1, it is possible to prevent an unintended reaction between the resist and the conductive film when performing post-exposure baking. However, the conductive film component diffused inside the resist before post-exposure baking may react with the resist, and a fine pattern may not be obtained with high accuracy. Further, according to the technique described in Patent Document 2, the reaction between the resist and the conductive film can be prevented as in Patent Document 1, but due to scattering when the charged particle beam passes through the film formed on the resist upper layer, A fine pattern may not be obtained with high accuracy.

  The present invention solves such a problem, and is characterized in that a conductive film is formed on a surface (back surface) opposite to a pattern forming surface of a substrate to be patterned and irradiated with a charged particle beam. . Then, the pattern forming apparatus is provided with a means for establishing electrical continuity with the back surface of the substrate to be processed, and is conductive with the conductive film on the back surface of the substrate.

  The invention according to claim 1 of the present invention is a pattern forming method for forming a pattern on a substrate having a first surface and a second surface facing the first surface, wherein a conductive film is formed on the second surface. And a pattern forming method of forming the pattern on the first surface side by irradiating a charged particle beam from the first surface side.

  The invention according to claim 2 of the present invention is the pattern forming method according to claim 1, wherein a conductive means is connected to the conductive film to form the pattern.

  According to a third aspect of the present invention, the light-shielding film is arranged in an island shape on the first surface, the light-shielding film is covered with a resist, and the charged particle beam is irradiated. The pattern forming method is as described.

  According to a fourth aspect of the present invention, there is provided a pattern forming apparatus for patterning a substrate having a first surface and a second surface facing the first surface, wherein the charge is directed toward the first surface. The pattern forming apparatus includes a particle beam irradiation unit that irradiates a particle beam to form the pattern on the first surface side, and a conduction unit that is electrically connected to the second surface side.

  The invention according to claim 5 of the present invention is the pattern forming apparatus according to claim 4, wherein the conduction means is in contact with the conductive film formed on the second surface and grounded.

  According to a sixth aspect of the present invention, there is provided a substrate having a first surface and a second surface facing the first surface, and a pattern formed by charged particle beam irradiation on the first surface side of the substrate. And a conductive film is formed so as to cover the second surface, or a conductive film is formed and peeled so as to cover the second surface.

  The invention according to claim 7 of the present invention is the photomask according to claim 6, wherein a light shielding film is formed in an island shape on the first surface.

  According to an eighth aspect of the present invention, there is provided a photomask manufacturing method in which a pattern is formed on the first surface side of a substrate having a first surface and a second surface facing the first surface. And forming a pattern on the first surface side by forming a conductive film on the second surface and irradiating a charged particle beam from the first surface side. is there.

  According to the present invention, it is possible to suppress the electric field generated by irradiating a charged particle beam regardless of the shape of the pattern formed on the substrate surface because the substrate to be processed is uniformly grounded. A desired pattern can be formed with high accuracy.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following, a Levenson type phase shift mask is exemplified, but this shows one embodiment of the invention. The present invention aims to prevent a decrease in pattern accuracy due to the generation of an electric field when patterning with a charged particle beam on an electrically discontinuous substrate, as long as the same effect can be obtained. The kind and material of the workpiece are not limited.

[First embodiment]
FIG. 1 is a schematic diagram showing a manufacturing process of a photomask 1 according to an embodiment of the present invention, which is patterned and manufactured by the method according to the present invention. FIG. 2 is a schematic diagram showing a schematic configuration of the pattern forming apparatus 2 used for pattern formation performed in the manufacturing process of the photomask 1.

  In the present embodiment, first, a transparent substrate (for example, a quartz plate) is prepared as the substrate 10 of the photomask 1. As shown in FIG. 1A, a light shielding film 11 made of chromium is patterned by a normal method on one side (first surface 10a) of two surfaces of the substrate 10 facing each other. The light-shielding film 11 does not continuously cover the entire first surface 10a, but has at least one island-shaped portion 11b that is divided and isolated from the surroundings (two in this figure).

  A first resist 13 for forming the second pattern is formed on the light shielding film 11 so as to cover the entire light shielding film 11. The first resist 13 can be used without limitation as long as it reacts with a charged particle beam such as an electron beam. In the example shown in FIG. 1, a positive resist is used as the first resist 13.

  On the opposite surface (second surface 10b) of the first surface 10a, a thin film (conductive film) 12 is formed over the entire surface. The conductive film 12 is provided to provide uniform conductivity to the back surface of the substrate 10 and is formed of a conductive material such as chromium, for example.

  As described above, the substrate 10 has the light shielding film 11 and the first resist 13 formed on the first surface 10a, and the conductive film 12 formed so as to cover the second surface 10b. It is used for the pattern formation process in the state shown. Hereinafter, a pattern forming method according to an embodiment of the present invention using the pattern forming apparatus 2 shown in FIG. 2 will be described.

  The pattern forming apparatus 2 includes a stage 18 on which the substrate 10 is placed, an electron optical system 17 as a particle beam irradiation unit that irradiates an electron beam as a charged particle beam, and a conduction pin 15 as a conduction unit. The electron optical system 17 and the conductive pin 15 are arranged to face each other with the substrate 10 interposed therebetween. The electron beam is controlled by the electron optical system 17, and the electron beam is irradiated from the electron optical system 17 toward the substrate 10 placed on the stage 18. At this time, the stage 18 on which the mask is installed moves appropriately so that a desired pattern is irradiated onto the entire first surface 10 a of the substrate 10. The conduction pin 15 is disposed so that one end thereof is in contact with the back surface of the substrate 10 and is grounded. A positive charge is supplied from the conduction pin 15, and a positive charge is generated in the conductive film 12.

  FIG. 1B shows a state where the substrate 10 is placed on the stage 18 of the pattern forming apparatus 2 and a pattern is formed. The substrate 10 is disposed on the stage 18 so that the conductive pins 15 are in contact with the conductive film 12 formed so as to cover the second surface 10b. In this state, an electron beam 14 for forming a desired pattern is irradiated toward the first resist 13 formed on the first surface 10a. At this time, charges (not shown) derived from the electron beam are accumulated in the substrate 10 and the first resist 13.

  Here, the conductive film 12 is electrically grounded by the conduction pin 15 provided in the pattern forming apparatus 2, and thus, the conductive film 12 in the region facing the first resist 13 where charges are accumulated is opposed to the conductive film 12. Charge (not shown) is generated. That is, the electric field is canceled by these opposite charges, and the irradiation with the electron beam 14 is performed with high accuracy according to a desired pattern.

  After drawing a pattern with an electron beam, the resist in the portion irradiated with electrons in the developing step is dissolved in a developing solution and removed. Then, etching is performed to etch the exposed portion that is not protected by the first resist 13, thereby forming a second pattern on the light shielding film 11 and the substrate 10 (see FIG. 1C).

  Next, a second resist 16 for covering the second pattern is formed on the substrate 10 on which the second pattern is formed. By etching the second surface 10b side of the substrate 10 in this state, the conductive film 12 formed on the second surface 10b is removed as shown in FIG. The conductive film 12 may be removed by ordinary wet etching.

  Finally, as shown in FIG. 1E, the second resist 16 is removed to complete the pattern formation. Through this process, the photomask 1 in which a desired pattern is formed on the substrate 10 is obtained.

  The photomask 1 is patterned in a state in which a conductive film 12 is formed on a surface (second surface 10b) opposite to a surface on which a pattern is formed (first surface 10a), and the conductive pins 15 are conductive. The Since generation of an electric field can thereby be suppressed, distortion of the electron beam is prevented, and the photomask 1 patterned with high accuracy can be obtained.

  Since the conductive film 12 is formed over the entire second surface 10b of the substrate 10, electrical grounding is possible even when the light shielding film 11 is formed in an island shape and is not continuous. In addition, since the conductive film 12 does not come into contact with the first resist 13, the resolution of the resist is not impaired.

  Further, compared to the conventional example shown in FIG. 3, there is less risk of patterning failure due to dust. That is, in the conventional example of FIG. 3, since the first resist 23 is broken and the conduction pin 25 is conducted to the light shielding film 21, the first resist 23 may be perforated to generate dust and cause a patterning defect. . On the other hand, since it is not necessary to perforate the first resist 13 in the present invention, such a fear can be avoided.

  Further, since the pattern forming apparatus 2 includes means for conducting with the conductive film formed on the back surface of the substrate to be processed, the effect of suppressing the generation of an electric field can be imparted to the conductive film.

The schematic diagram which shows the manufacturing process of the photomask manufactured by the pattern formation method which concerns on one Embodiment of this invention. The schematic diagram which shows the structure of the pattern formation apparatus which concerns on this invention. The schematic diagram which shows the pattern formation method which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 20 ... Board | substrate 11, 21 ... Light-shielding film 12, 22 ... Conductive film 13, 23 ... 1st resist 14 ... Electron beam 15, 25 ... Conduction pin 16 ... 2nd resist 17 ... Electro-optic system 18 ... Stage

Claims (8)

A pattern forming method for forming a pattern on a substrate having a first surface and a second surface facing the first surface,
Forming a conductive film on the second surface;
A pattern forming method for forming the pattern on the first surface side by irradiating a charged particle beam from the first surface side.   The pattern forming method according to claim 1, wherein a conductive unit is connected to the conductive film to form the pattern. On the first surface, a light shielding film is disposed in an island shape,
The pattern forming method according to claim 1, wherein the light shielding film is covered with a resist, and the charged particle beam is irradiated. A pattern forming apparatus for patterning a substrate having a first surface and a second surface facing the first surface,
A particle beam irradiation means for irradiating a charged particle beam toward the first surface to form the pattern on the first surface side;
A pattern forming apparatus comprising: a conducting unit that conducts with the second surface side.   The pattern forming apparatus according to claim 4, wherein the conduction unit is in contact with the conductive film formed on the second surface and is grounded. A substrate having a first surface and a second surface facing the first surface;
A pattern formed by charged particle beam irradiation on the first surface side of the substrate,
A photomask in which a conductive film is formed so as to cover the second surface or a conductive film is formed and peeled so as to cover the second surface.   The photomask according to claim 6, wherein a light shielding film is formed in an island shape on the first surface. A method of manufacturing a photomask in which a pattern is formed on the first surface side of a substrate having a first surface and a second surface facing the first surface,
Forming a conductive film on the second surface;
A method for manufacturing a photomask, wherein the pattern is formed on the first surface side by irradiating a charged particle beam from the first surface side.

Images