JP2007019249A - Electron beam exposure equipment and device manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide electron beam exposure equipment having a reduced electron optical system and an object electron optical system while maintaining the predetermined value of overall magnification upon an image rotation correction, and generating no change in an image surface position as well as the image magnification on a wafer, and to provide the manufacturing method of a device employing the electron beam exposure equipment. <P>SOLUTION: The ray exposure device is provided with the shrink electron optical system 11 constituted of a first magnetic field lens 5 and a second magnetic field lens 6, and the object electron optical system 12 constituted of a third magnetic field lens 7 and a fourth magnetic field lens 8. The overall magnification maintains a predetermined value when taking the change of the image magnification generated by a first image rotation lens 9 provided above the second magnetic field lens in the magnetic field of the first magnetic field lens, and the image magnification generated by a second image rotation lens 10 provided above a fourth magnetic field lens in the third magnetic field lens into consideration. Further, the overall magnification maintains a predetermined value also upon an image rotation correction, and generates no change of the image surface position and the image magnification on the wafer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electron beam exposure apparatus for correcting a rotation error of a drawing pattern on a surface to be exposed of a wafer and a device manufacturing method using the electron beam exposure apparatus.

In general, there is a need for an exposure apparatus that exposes a miniaturized pattern at a high speed by improving the degree of integration of semiconductor devices. An electron beam exposure apparatus excellent in resolution performance is capable of drawing a fine pattern, but is inferior to a conventional light exposure apparatus in terms of throughput performance.
In recent years, in order to solve this drawback, a transfer type electron beam exposure apparatus for transferring a pattern formed on a mask onto a wafer and a multi-beam electron beam exposure apparatus for simultaneously drawing using a plurality of electron beams have been developed. Yes. The feature of these apparatuses is that the processing capability is high because a wide exposure area or drawing area is obtained.
However, if the exposure area is increased, the influence of the rotation error of the exposure region on the splicing accuracy becomes sensitive, and it is necessary to improve the setting accuracy of the rotation angle.
Therefore, for example, Japanese Patent Application Laid-Open No. 2004-193157 (Patent Document 1) proposes a method for correcting image rotation in an electron beam exposure apparatus, and the image rotation lens is arranged by arranging the image rotation lens at the pupil plane position of the irradiation system. The magnification can always be maintained at a constant value even if the intensity of the lens is changed.
JP 2004-193157 A

The image rotation lens in the conventional electron beam exposure apparatus as described above can be arranged when there is a relatively large space between the magnetic lens.
However, in recent years, in the case of a magnetic doublet lens used in a transfer type exposure apparatus, the set magnification is determined by the ratio of the set focal length of the two-stage magnetic lens constituting the magnetic doublet lens. Since it is necessary to design the distance between the object images as short as possible in consideration of the amount of beam blur due to the Coulomb effect, in the case of a high-magnification doublet lens, the set focal length of the lower magnetic lens is about 20 mm to 40 mm.
In the symmetric magnetic doublet lens, the ratio between the gap length and the inner diameter of the upper and lower magnetic poles needs to be set to a magnification value, so the inner diameter of the lower magnetic lens pole needs to be reduced. Therefore, the rotational lens is arranged in the magnetic pole of the lower magnetic field lens at the pupil plane position of this optical system. Further, since it is necessary to arrange a deflector and a dynamic corrector at the time of deflection at that location, it is difficult to ensure the space where the rotating coil is arranged.
Accordingly, the present invention provides a reduction electron optical system including a magnetic doublet lens of a first magnetic lens disposed on the upper side and a second magnetic lens disposed on the lower side, and a third magnetic lens disposed on the upper side. And an objective electron optical system comprising a magnetic doublet lens of a fourth magnetic lens disposed on the lower side, and the overall magnification is maintained at a predetermined value even during image rotation correction An electron beam exposure apparatus that does not cause changes in image plane position and image magnification on a wafer, and a device manufacturing method using the electron beam exposure apparatus.

In order to solve the above problems, an electron beam exposure apparatus of the present invention is an electron beam exposure apparatus that exposes a pattern on an exposed surface using an electron beam.
A first electron optical system having a first magnetic lens disposed on the upper side and a second magnetic lens disposed on the lower side;
A second magnetic optical system having a third magnetic lens disposed on the upper side and a fourth magnetic lens disposed on the lower side, and provided below the first electron optical system;
A first image rotation lens provided in the magnetic field from the first magnetic lens and above the second magnetic lens;
A second image rotation lens provided in the magnetic field from the third magnetic lens and above the fourth magnetic lens,
The total magnification considering the change in image magnification caused by the first image rotation lens and the change in image magnification caused by the second image rotation lens is maintained at a predetermined value.
Furthermore, in the electron beam exposure apparatus of the present invention, the positions of the first image rotation lens and the second image rotation lens in the optical axis direction are set such that the total magnification is maintained at the predetermined value. The

In the electron beam exposure apparatus of the present invention, the excitation currents of the first image rotation lens and the second image rotation lens are controlled so that the total magnification is maintained at the predetermined value.
Furthermore, the electron beam exposure apparatus according to the present invention includes the polarities of the axial magnetic fields of the first magnetic lens and the second magnetic lens and the polarities of the axial magnetic fields of the third magnetic lens and the fourth magnetic lens. Are set to have opposite polarities, and the polarity of the on-axis magnetic field generated by the first image rotation lens and the polarity of the on-axis magnetic field generated by the second image rotation lens are the same. Is set as follows.
Furthermore, the electron beam exposure apparatus according to the present invention includes the polarities of the axial magnetic fields of the first magnetic lens and the second magnetic lens and the polarities of the axial magnetic fields of the third magnetic lens and the fourth magnetic lens. Are set to have the same polarity, and the polarity of the on-axis magnetic field generated by the first image rotation lens and the polarity of the on-axis magnetic field generated by the second image rotation lens are opposite to each other. Is set as follows.
Furthermore, the device manufacturing method of the present invention comprises a step of exposing the object to be exposed using the electron beam exposure apparatus, and a step of developing the exposed object to be exposed. .

According to the electron beam exposure apparatus of the present invention, the first electron optical system having the first magnetic lens arranged on the upper stage side and the second magnetic lens arranged on the lower stage side, and arranged on the upper stage side. A second magnetic optical system having a third magnetic lens and a fourth magnetic lens disposed on the lower side, provided below the first electron optical system; and a magnetic field from the first magnetic lens And a first image rotation lens provided above the second magnetic lens and a magnetic field from the third magnetic lens and provided above the fourth magnetic lens. Two image rotation lenses,
Since the total magnification taking into account the change in image magnification caused by the first image rotation lens and the change in image magnification caused by the second image rotation lens is maintained at a predetermined value, the total magnification is maintained even during image rotation correction. The predetermined value is maintained, and the image plane position on the wafer and the image magnification do not change.
Furthermore, according to the electron beam exposure apparatus of the present invention, the total magnification of the first image rotation lens and the second image rotation lens in the optical axis direction is maintained at the predetermined value. Therefore, astigmatism and lateral chromatic aberration of the reduction electron optical system and objective electron optical system can be reduced.
Furthermore, according to the electron beam exposure apparatus of the present invention, the excitation currents of the first image rotation lens and the second image rotation lens are controlled so that the total magnification is maintained at the predetermined value. Thus, there is no change in magnification, and a wide range of image rotation angles can be corrected.
Furthermore, according to the electron beam exposure apparatus of the present invention, the polarities of the on-axis magnetic fields of the first magnetic lens and the second magnetic lens and the on-axis magnetic fields of the third magnetic lens and the fourth magnetic lens. The polarities of the axial magnetic field generated by the first image rotating lens and the polarities of the axial magnetic field generated by the second image rotating lens are the same as each other. Therefore, it is possible to reduce the astigmatism and the anisotropic component of the magnification aberration of the reduction electron optical system and the objective electron optical system.
Furthermore, according to the electron beam exposure apparatus of the present invention, the polarities of the on-axis magnetic fields of the first magnetic lens and the second magnetic lens and the on-axis magnetic fields of the third magnetic lens and the fourth magnetic lens. The polarities of the on-axis magnetic field generated by the first image rotation lens and the polarities of the on-axis magnetic field generated by the second image rotation lens are opposite to each other. Therefore, there is no change in magnification, and a wide range of image rotation angles can be corrected.
Furthermore, according to the device manufacturing method of the present invention, the method includes the steps of exposing the object to be exposed using the electron beam exposure apparatus, and developing the exposed object to be exposed. Therefore, the total magnification maintains a predetermined value even during image rotation correction, and the image plane position on the wafer and the image magnification do not change. For this reason, a semiconductor device can be manufactured efficiently.

  Hereinafter, the present invention will be described with reference to the drawings based on the embodiments.

Next, an electron beam exposure apparatus according to the first embodiment of the present invention will be described with reference to FIG.
The reduction electron optical system 11 includes a magnetic doublet lens of a first magnetic lens 5 disposed on the upper side and a second magnetic lens 6 disposed on the lower side, and an electron beam 3 emitted from the object surface 1. Is an optical system that forms an image on the intermediate image plane 4. The inner diameter of the first magnetic lens 5 arranged on the upper stage side has a larger space than the inner diameter of the second magnetic lens 6 arranged on the lower stage side.
The objective electron optical system 12 is provided below the reduction electron optical system 11 and includes a magnetic doublet lens of a third magnetic lens 7 disposed on the upper side and a fourth magnetic lens 8 disposed on the lower side. The optical system forms an image on the wafer surface 2. The inner diameter of the third magnetic lens 7 disposed on the upper stage side has a larger space than the inner diameter of the fourth magnetic lens 8 disposed on the lower stage side.
The first image rotation lens 9 disposed on the upper side is provided in the magnetic field of the first magnetic lens 5 and above the second magnetic lens 6. Since the first image rotation lens 9 is provided in the magnetic field of the first magnetic lens 5 having a large inner diameter space, it is possible to increase the number of turns of the excitation coil of the first image rotation lens 9 and to correct it. The image rotation angle spreads.
The second image rotation lens 10 disposed on the lower side is provided in the magnetic field of the third magnetic lens 7 and above the fourth magnetic lens 8. Since the second image rotation lens 10 is provided in the magnetic field of the third magnetic lens 7 having a wide inner diameter space, the number of turns of the excitation coil of the second image rotation lens 10 can be increased, and correction is possible. The image rotation angle spreads.
The control means (not shown) controls the total magnification taking into account the change in the image magnification caused by the first image rotation lens 9 and the change in the image magnification caused by the second image rotation lens 10 so as to maintain a predetermined value. The positions of the first image rotation lens 9 and the second image rotation lens 10 in the optical axis direction are arranged so that the total magnification maintains a predetermined value. Further, a control unit (not shown) controls the excitation currents of the excitation coils of the first image rotation lens 9 and the second image rotation lens 10 so that the total magnification maintains a predetermined value.

The total magnification Mt by the first image rotation lens 9 and the second image rotation lens 10 is expressed by the following equation.
Mt = (M1 + ΔM1) (M2 + ΔM2) =
M1 * M2 + M1ΔM2 + M2ΔM1 + ΔM1ΔM2 (Equation 1)
Here, M1 is a desired setting magnification of the reduction optical system, M2 is a desired setting magnification of the objective optical system, and ΔM1 and ΔM2 are image magnification changes caused by two image rotation coils.
Since ΔM1ΔM2 = 0 is considered,
Mt = M1 * M2 + M1ΔM2 + M2ΔM1 (Expression 2)
The condition under which Mt does not change is M1ΔM2 = −M2ΔM1 (Equation 3)
From FIG. 3, the relationship between the excitation currents (Icoil 1 and 2) of the first image rotation lens 9 and the second image rotation lens 10 and the change in magnification is expressed by the following equation.
ΔM1 = K1 * Icoil1, ΔM2 = −K2 * Icoil2...
(Formula 4)
The excitation current ratio of the first image rotation lens 9 and the second image rotation lens 10 under which the condition that the total magnification Mt remains unchanged is obtained from (Equation 3) and (Equation 4).
Icoil1 / Icoil2 =-(M1 * K2) / (M2 * K1) ...
(Formula 5)
Therefore, the first image rotation lens 9 and the second image rotation lens 10 are maintained in the state in which the set excitation ratios of the first image rotation lens 9 and the second image rotation lens 10 are maintained at the values expressed by Formula 5. By changing the excitation current by a control means (not shown), it is possible to adjust the image rotation angle on the wafer surface 2.

Next, referring to FIG. 2, the on-axis magnetic fields 11a and 12a of the reduction electron optical system 11 and the objective electron optical system 12, the first image rotation lens 9 disposed on the upper stage side, and the second image disposed on the lower stage side. The axial magnetic fields 9a and 10a of the image rotation lens 10 will be described.
The control means (not shown) determines the polarity of the on-axis magnetic field 11a generated by the first magnetic lens 5 and the second magnetic lens 6 constituting the reduction electron optical system 11 and the objective system so that the total magnification is maintained at a predetermined value. The polarities of the on-axis magnetic field 12a generated by the third magnetic field lens 7 and the fourth magnetic field lens 8 constituting the electron optical system 12 are set to opposite polarities, and the first image rotation lens 9 and the second magnetic field lens The axial magnetic field 9a generated by the image rotation lens 10 and the magnetic field 10a are set to the same polarity.
Theoretically, in the first magnetic lens 5, the second magnetic lens 6, the third magnetic lens 7, and the fourth magnetic lens 8, which are symmetric magnetic doublet lenses, off-axis aberrations. The anisotropic component and image distortion are canceled out.
However, in the first magnetic lens 5, the second magnetic lens 6, the third magnetic lens 7, and the fourth magnetic lens 8 that are actual magnetic doublet lenses, there are restrictions on design arrangement, mechanical properties, and the like. Due to an error or the like, the above-mentioned anisotropic component of off-axis aberrations and image distortion aberration remain.
As shown in the first embodiment, the first magnetic lens 5, the second magnetic lens 6, the third magnetic lens 7, and the fourth magnetic field, which are magnetic doublet lenses disposed on the upper side or the lower side. By setting the magnetic fields of the lenses 8 to opposite polarities, a doublet lens first magnetic lens 5 in which astigmatism and lateral chromatic aberration are arranged on the upper side or the lower side among the remaining anisotropic aberrations, The second magnetic lens 6, the third magnetic lens 7, and the fourth magnetic lens 8 cancel each other. As a result, the aberration amounts of the reduction electron optical system 11 and the objective electron optical system 12 are reduced, and the resolution performance is improved.
Here, the control means (not shown) determines the polarities of the on-axis magnetic fields generated by the first magnetic lens 5 and the second magnetic lens 6 constituting the reduction electron optical system 11 so that the total magnification maintains a predetermined value. The polarities of the on-axis magnetic fields generated by the third magnetic field lens 7 and the fourth magnetic field lens 8 constituting the objective electron optical system 12 are set to be the same polarity, and are arranged on the upper stage side. The on-axis magnetic field 9a and the on-axis magnetic field 10a generated by one image rotation lens 9 and the second image rotation lens 10 disposed on the lower side may be set to have opposite polarities.

Next, correction characteristics of the first image rotation lens 9 disposed on the upper stage side and the second image rotation lens 10 disposed on the lower stage side that constitute Embodiment 1 of the present invention will be described with reference to FIG. To do.
The horizontal axis in FIG. 3 indicates the excitation intensity of the first image rotation lens 9 and the second image rotation lens 10, and the vertical axis indicates the change in image rotation angle and magnification. When the excitation intensity of the first image rotation lens 9 and the second image rotation lens 10 is changed, the image rotation angle changes in proportion to the value.
On the other hand, the magnification changes in proportion to the rotation coil 9b of the upper first image rotation lens 9, but the rotation coil 10b of the second image rotation lens 10 arranged on the lower side has an inversely proportional relationship.
This is because the on-axis magnetic field 11a of the reduction electron optical system 11 shown in FIG. 2 and the on-axis magnetic field 9a of the first image rotation lens 9 arranged on the upper side have the same polarity. When the excitation intensity of the rotating lens 9 is increased, the position of the intermediate image plane 4 moves to the object plane 1 side, and the total magnification of the reduction electron optical system 11 and the objective electron optical system 12 is reduced.
On the other hand, since the axial magnetic field 10a of the rotating coil 10b of the second image rotating lens 10 disposed on the lower stage side is opposite in polarity to the axial magnetic field 12a of the objective electron optical system 12, the position of the wafer surface 2 is changed. When the excitation intensity of the rotating coil 10b of the second image rotating lens 10 is increased in the fixed state, the intermediate image surface 4 moves to the wafer surface 2 side, and the overall magnification increases.
Regarding the image rotation angle, since the on-axis magnetic field 9a and the on-axis magnetic field 10a of the first image rotation lens 9 and the second image rotation lens 10 have the same polarity, the change in the image rotation angle shows the same tendency.
Due to such characteristics, the first image rotation lens 9 disposed on the upper stage side and the second image rotation lens 10 disposed on the lower stage side cancel out the change in magnification and the first image rotation lens disposed on the upper stage side. The corrected image rotation angles of the image rotation lens 9 and the second image rotation lens 10 disposed on the lower stage side can be added to the image rotation angle of two stages to correct a wide range.

Next, an electron beam exposure apparatus according to the second embodiment of the present invention will be described with reference to FIG.
Although the position of the first image rotation lens 9 is located above the first magnetic field lens 5 and the position of the second image rotation lens 10 is above the fourth magnetic field lens 8, The point located below the third magnetic lens 7 is different from the first embodiment of the present invention.

Next, as Example 3 of the present invention, a semiconductor device manufacturing process using the electron beam exposure apparatus of Example 1 will be described.
FIG. 4 is a flowchart showing the overall manufacturing process of the semiconductor device.
In step 1 (circuit design), a semiconductor device circuit is designed.
In step 2 (EB data conversion), exposure control data for the exposure apparatus is created based on the designed circuit pattern.
On the other hand, in step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer using lithography using the exposure apparatus and wafer to which the exposure control data has been input. The next step 5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer produced in step 4, and is an assembly process (dicing, bonding), packaging process (chip encapsulation), etc. Process. In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. A semiconductor device is completed through these processes, and is shipped in Step 7.
The wafer process in step 4 includes the following steps. An oxidation step for oxidizing the surface of the wafer, a CVD step for forming an insulating film on the wafer surface, an electrode formation step for forming electrodes on the wafer by vapor deposition, an ion implantation step for implanting ions on the wafer, and applying a photosensitive agent to the wafer The resist processing step, the exposure step for printing and exposing the circuit pattern onto the wafer after the resist processing step by the above-described exposure apparatus, the development step for developing the wafer exposed in the exposure step, and the etching for removing portions other than the resist image developed in the development step Step, resist stripping step to remove resist that is no longer needed after etching. By repeating these steps, multiple circuit patterns are formed on the wafer.

It is a block diagram of the electron beam exposure apparatus of Example 1 of this invention. It is a figure which shows the axial magnetic field of the reduction electron optical system which comprises the electron beam exposure apparatus of Example 1 of this invention, and an objective electron optical system, and the axial magnetic field of a 1st image rotation lens and a 2nd image rotation lens. . It is a figure which shows the relationship between the excitation intensity of the 1st image rotation lens which comprises the electron beam exposure apparatus of Example 1 of this invention, and a 2nd image rotation lens, an image rotation angle, and magnification. It is a block diagram of the electron beam exposure apparatus of Example 2 of this invention. It is a figure which shows the flow of the whole manufacturing process of the semiconductor device of Example 3 of this invention using the electron beam exposure apparatus of Example 1 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Object surface position of reduction objective 2 Wafer surface 3 Electron beam 4 Intermediate image surface 5 First magnetic lens 6 Second magnetic lens 7 Third magnetic lens 8 Fourth magnetic lens 9 First image rotation lens
9a Axial magnetic field of first image rotation lens 9b Rotating coil
10 Second image rotation lens
10a On-axis magnetic field of second image rotation lens 10b Rotating coil 11 Reduced electron optical system 11a On-axis magnetic field of reduced electron optical system 12 Objective electron optical system 12a On-axis magnetic field of objective electron optical system

Claims (6)

In an electron beam exposure apparatus that exposes a pattern on an exposed surface using an electron beam,
A first electron optical system having a first magnetic lens disposed on the upper side and a second magnetic lens disposed on the lower side;
A second magnetic optical system having a third magnetic lens disposed on the upper side and a fourth magnetic lens disposed on the lower side, and provided below the first electron optical system;
A first image rotation lens provided in the magnetic field from the first magnetic lens and above the second magnetic lens;
A second image rotation lens provided in the magnetic field from the third magnetic lens and above the fourth magnetic lens,
2. An electron beam exposure apparatus according to claim 1, wherein a total magnification including a change in image magnification caused by the first image rotation lens and a change in image magnification caused by the second image rotation lens is maintained at a predetermined value.   2. The electron beam exposure apparatus according to claim 1, wherein positions of the first image rotation lens and the second image rotation lens in an optical axis direction are set such that the total magnification is maintained at the predetermined value.   3. The electron beam exposure apparatus according to claim 1, wherein excitation currents of the first image rotation lens and the second image rotation lens are controlled so that the total magnification is maintained at the predetermined value.   The polarities of the axial magnetic fields of the first magnetic lens and the second magnetic lens and the polarities of the axial magnetic fields of the third magnetic lens and the fourth magnetic lens are set to be opposite to each other. The polarity of the on-axis magnetic field generated by the first image rotation lens and the polarity of the on-axis magnetic field generated by the second image rotation lens are set to be the same polarity. The electron beam exposure apparatus according to any one of the above.   The polarities of the axial magnetic fields of the first magnetic lens and the second magnetic lens and the polarities of the axial magnetic fields of the third magnetic lens and the fourth magnetic lens are set to be the same polarity. The polarity of the on-axis magnetic field generated by the first image rotation lens and the polarity of the on-axis magnetic field generated by the second image rotation lens are set to be opposite to each other. The electron beam exposure apparatus according to any one of the above.   A step of exposing the object to be exposed using the electron beam exposure apparatus according to any one of claims 1 to 5 and a step of developing the exposed object to be exposed are provided. Device manufacturing method.

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