JPH0430415A - Electron beam lithography device and adjusting method of orthogonality of molding aperture - Google Patents

Abstract

PURPOSE:To reduce the defectively formed pattern by a variably forming electronic beam lithography device by a method wherein, in the variably forming electronic beam lithography device in which first and second molding aperture are incorporated for the purpose of conducting electron beam molding, an adjusting hole is provided on the molding apertures, and the detection and the calibration of adjustment state is conducted automatically. CONSTITUTION:As the electron beam emitted from an electron gun 1 is made incident on a Faraday cup, to be used to detect the condition of orthogonal intersection of an aperture, through a first rectangular aperture 2 and a second rectangular aperture 3, three holes for adjustment of degree of orthogonal intersection are arranged on the above-mentioned aperture 3 along the extension line of the side used by the hole for adjustment of degree of orthogonal intersection. The current value of the electron beam passed through each hole is detected by the Faraday cup while the electron beam is being scanned on the aperture 3 along the side to be used. When the second rectangular aperture 3 is rotationally adjusted using a driving part 10 so as to make all current values uniform, the degree of orthogonal inter-section of the aperture 2 is adjusted automatically, and defectively formed pattern can be reduced.

Description

[Detailed description of the invention] [Industrial application field]

The present invention aims at simplifying the method for adjusting the orthogonality of a forming aperture after starting up the variable forming electron beam lithography system used for pattern formation of semiconductor elements, and also provides a stable system that is not influenced by the subjectivity of the adjustment operator. Concerning methods for creating conditions.

[Conventional technology]

The integration and density of ULSI has been increasing four times in three years, and a 4 megabit dRAM has already been prototyped. Along with this, the dimensions required for microfabrication are 0
．． It has been miniaturized to 5 μm. Lithography has a role to play in driving these miniaturization technologies. Lithography technology includes pattern formation methods using light, X-rays, electron beams, etc. Among them, electron beam writing technology is
．． This technology is essential for creating next-generation semiconductor devices that require patterns of 3 μm or less. As the line width of patterns has become finer, the specifications required of electron beam lithography systems have also become more sophisticated. In order to meet this requirement, each manufacturer has devised its own unique ideas to improve the functionality and accuracy of drawing devices during pattern formation. However, on the other hand, there are few devices designed to simplify maintenance and adjustment. In this regard, much remains to be relied on the experience and subjectivity of the adjustment operator. One of these is adjusting the orthogonality of the aperture. “Solid State Technology”
Technology) Japanese board November 1984
As described in ``Direct Writing Electron Beam Lithography Technology - Its Position in the Manufacturing Line'', published in 2007, ``Direct Write Electron Beam Lithography Technology - Its Position in the Manufacturing Line'', in general variable shaping type lithography equipment, the desired shot is created by changing the cut of two apertures. , connect them to form a pattern. Therefore, the above adjustment is the key to the drawing accuracy of the drawing apparatus. However, in conventional drawing apparatuses, adjustment operators rely on their intuition gained over many years to make adjustments.

[Problem to be solved by the invention]

However, as a result of drawing using a device that had been adjusted using the method described above, abnormalities in the shape of the pattern occurred in microscopic areas due to residual adjustment, resulting in problems such as the orthogonality of the apertures having to be readjusted. . This problem is likely to occur because the adjustment depends on the subjectivity of the operator in charge. Conventionally, this adjustment has been performed approximately in the following procedure. A shaped beam with a maximum variable area is irradiated onto microscopic gold particles provided on the stage, and reflected electrons are detected. The obtained signal is processed and displayed on a monitor as an image. A deflector is used in each of the W (horizontal) direction and the H (vertical) direction to create a state in which the aperture appears to be moved. While checking the rotational state of the aperture in the image, set the aperture adjustment mechanism to the desired state. Furthermore, as a method of increasing the accuracy of the orthogonality state of the aperture, the above adjustment is performed with the shots made finer.
However, with this method, as the shot size of the electron beam decreases, the signal detection level decreases, and as a result, it becomes difficult to adjust the degree of orthogonality in minute areas, making it impossible to improve the accuracy of the degree of orthogonality. Connect - If electron beam lithography equipment is used to form patterns at the 0.3 μm level or smaller in the future, even residual adjustments, which were not a big problem in the past, may have a negative impact on the characteristics of semiconductor devices. . In view of the above phenomenon, the present invention aims to reduce defective pattern formation in variable-forming electron beam lithography equipment, simplify start-up work after maintenance of the equipment, and improve future U.S.
The purpose of this paper is to enhance the functions of variable-forming electron beam lithography equipment, which is indispensable to the LSI manufacturing process, and to introduce its method.

[Means to solve the problem]

The problem is that as a method of adjusting the orthogonality of the aperture, the adjustment hole is provided on the molded aperture, and the lateral ratio of the adjusted state is
This problem can be solved by automatically performing calibration.

[Effect]

The automation of the adjustment eliminates the adjustment defects that have hitherto been caused by the subjectivity of the adjustment operator. Further, the adjustment does not require skill and can be performed easily and stably.

【Example】

The first embodiment relates to an apparatus and method for automatically adjusting the orthogonality of a forming aperture, as shown in FIG. The apparatus shown in FIG. 1 includes an electron gun 1 for irradiating an electron beam,
Detects the state of orthogonality of the first rectangular aperture 2, the second rectangular aperture 3, the deflector 5 used to shape the electron beam 4, the deflection control circuit 6 that controls the deflector, and the aperture. a Faraday cup 7 for storage, a memory 8 for storing detected values, a signal processing circuit 9 for comparing the detected signal with an ideal value of orthogonality and calculating a difference value, and a calculated difference value. Drive unit 1 that rotates according to
0 and a control section 11 that performs overall control during adjustment. We attempted to automatically adjust the degree of orthogonality using this device. As shown in FIG. 2, the orthogonality adjusting holes were three rectangular holes each having a length of 50 .mu.m and arranged along the extension of the side of the molding aperture at intervals of 200 .mu.m. While scanning the electron beam along the side of the aperture, the current value of the electron beam that passed through the aperture was detected using a Faraday cup. FIG. 3 and FIG. 4 show the above detection results. Current waveforms 1.2.3 are obtained corresponding to the adjustment holes 1.2.3 (vertical) and 1.2.3 (horizontal). FIG. 3 shows a state where the degree of orthogonality is not adjusted correctly. In this state, a difference can be seen in the current value for each adjustment hole. The rotation of the second rectangular aperture 3 was adjusted using the drive unit 10 so that the current values were all constant. As a result, as shown in FIG. 4, it was possible to keep the current values obtained at all adjustment holes constant. Thereafter, a line pattern of 0.3 μm was actually drawn using this device, and the pattern in both the vertical and horizontal directions was observed using an electron microscope. As a result, no shot abnormality due to unadjusted orthogonality was observed. The second embodiment relates to a case where three orthogonality adjustment holes each having a unique shape whose arrangement position can be specified are provided in a molded aperture, and the adjustment is automatically performed by image recognition. A schematic diagram of an apparatus incorporating the present invention is shown in FIG. FIG. 6 shows a state where the degree of orthogonality is not adjusted correctly. In this state, images of all adjustment holes incorporated in the molded aperture cannot be completely confirmed. The second rectangular aperture 503 was rotated and adjusted using the drive unit 511 to a position where the entire image could be confirmed. As a result, as shown in FIG. 7, images of all adjustment holes could be confirmed. After that, a line pattern of 0.3 μm was actually drawn using one device, and the pattern in both the vertical and horizontal directions was observed using an electron microscope. As a result, as in the first example, no shot abnormality due to the remaining adjustment of orthogonality was observed. There wasn't. According to the present invention, complicated orthogonality adjustment of a molding aperture as shown in FIG. 8 can be easily and automatically performed. Conventionally, when the shape of the molding aperture becomes complicated as shown in FIG. 8, it becomes difficult to determine the correspondence between the detection signal and the adjustment position, making accurate adjustment extremely difficult. According to the above, regardless of the opening shape of the forming aperture, by performing the adjustment in the same manner as in Example 1, it is possible to perform a good orthogonality adjustment of the forming aperture without shot abnormalities. (Effects of the Invention) According to the present invention, the drawing accuracy of the variable shape electron beam drawing apparatus,
In particular, it is possible to prevent wedge-shaped shot abnormalities during processing at the 0.3 μm level. Further, the device can always be set to the same good condition in a short time after maintenance. It is possible to strongly promote the production of ultra-fine devices for semiconductor elements such as ULSI, which will become increasingly highly integrated in the future.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a variable molding type electron beam lithography system equipped with an automatic molding aperture adjustment function, Fig. 2 is a diagram showing an example in which a hole for orthogonality adjustment is provided in the second molding aperture, and Fig. 3 is a diagram showing an example in which a hole for orthogonality adjustment is provided in the second molding aperture.
Figure (a) shows the state when the orthogonality of the second molding aperture is poor, and Figures 3 (b) and (c) show the state of the current passing through the adjustment hole when the orthogonality of the second molding aperture is poor. Figure, 4th
Figure (a) is a diagram showing when the orthogonality of the molding aperture is good; Figures 4 (b) and (c) are diagrams showing the state of the current passing through the adjustment hole when the orthogonality of the molding aperture is good; The figure is the second
A diagram showing an electron beam lithography system equipped with an image recognition function for automatic adjustment of the molding aperture, FIG. 6(a) is a diagram showing when the orthogonality of the second molding aperture is poor, and FIG. c.
) is a diagram showing an image of the adjusting hole when the second molding aperture has poor orthogonality, FIG. 7(a) is a diagram showing when the second molding aperture has good orthogonality, and FIGS. 7(b) and (c) ) is a diagram showing an image of the adjustment hole when the second molding aperture has good orthogonality, and FIG. 8 shows an example of a method for arranging the orthogonality adjustment hole in a plurality of second molding apertures of various types. It is a diagram. Explanation of symbols 1... Electron gun, 2... First rectangular aperture, 3...
- Second rectangular aperture, 4... Electron beam, 5... Deflector, 6... Deflection control circuit, 7... Faraday cup,
8... Memory, 9... Signal processing circuit, 10... Drive section, 11... Control section, 501... Electron gun, 502
...First shaping aperture, 503...Second shaping aperture, 504...Electron beam, 505...Deflector, 506
... Deflection control circuit, 507 ... Conductive irradiated substrate,
508...Detector, 509...Image processing circuit, 51
0... Image recognizer, 511... Drive unit, 512...
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Claims (1)

[Claims] 1. In a variable shaping type electron beam lithography device incorporating a first shaping aperture and a second shaping aperture for shaping an electron beam, the second shaping aperture is provided with a hole for orthogonality adjustment. What is claimed is: 1. An electron beam lithography apparatus comprising: an automatic adjustment function for the orthogonality of an aperture; 2. The electron beam according to claim 1, wherein as the orthogonality adjusting holes of the second molded aperture, a large number of holes having the same opening area or having a shape that allows the placement position to be specified are used. drawing device. 3. The interval at which the orthogonality adjustment holes are arranged is longer than the diagonal line of the first molded aperture, and the reference position during arrangement is such that information on the second molded aperture and the adjustment hole are simultaneously detected. 3. The electron beam lithography apparatus according to claim 2, wherein the electron beam lithography apparatus is located at such a position that the electron beam lithography apparatus is not exposed to the electron beam. 4. Electron beam lithography according to claim 2, characterized in that when the angle formed by the side used in the second forming aperture is a right angle, a hole for orthogonality adjustment is arranged along an extension of the side. Device. 5. When the second molded aperture has an arbitrary shape, orthogonality adjustment is performed perpendicularly to the vertical and horizontal directions with respect to the second molded aperture, with reference to an arbitrary point on the opening surface of the second molded aperture. Claim 2 characterized in that an irrigation hole is arranged.
The electron beam lithography apparatus described above. 6. When a wide variety of molded apertures or a plurality of molded apertures are considered as one molded aperture, the perpendicularity adjustment holes are arranged in the vertical and horizontal directions with respect to the endmost side of the second molded aperture. The electron beam lithography apparatus according to claim 2. 7. The electron beam lithography apparatus according to claim 2, wherein the orthogonality adjustment holes are arranged based on the center of gravity of each opening surface. 8. The orthogonality automatic adjustment function includes a detection section for detecting the electron beam passing through the orthogonality adjustment hole, a memory section for storing each detection value obtained by the detection section, and a detection section for detecting the electron beam that has passed through the orthogonality adjustment hole. It is characterized by consisting of a processing section that compares the ideal value and the detected value and calculates the difference value, a drive section that rotates the molding aperture by an amount corresponding to the difference value, and a control section that controls the whole. The electron beam lithography apparatus according to claim 1. 9. The electron beam lithography apparatus according to claim 8, wherein the detection section comprises a Faraday cup for detecting a current value or a conductive substrate for detecting reflected electrons or secondary electrons. 10. A method for adjusting the degree of orthogonality of a molding aperture, characterized in that the degree of orthogonality is detected using an output value obtained by scanning the adjustment hole with an electron beam. 11. Claim 10, wherein the scanning direction of the electron beam is horizontal and vertical scanning with the forming aperture as a base point.
The described method for adjusting the orthogonality of a molding aperture. 12. An electron beam lithography apparatus having a function of detecting orthogonality by recognizing shape information of the orthogonality adjustment hole obtained by scanning the electron beam over the orthogonality adjustment hole.