JPH09134866A - Electron beam plotting device and forming method of pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an electron beam plotting device to easily correct a pattern on a proximity effect when the pattern is collectively transferred by a method wherein a substrate where apertures are provided is varied in electron transmission inhibiting properties corresponding to the pattern of a collective transfer mask which is made up with the size of an aperture and the type or density of the pattern. SOLUTION: Provided that a square aperture 121 of large area and a linear aperture 123 are provided in a collective transfer mask 12, the mask 12 is set large in thickness at the periphery 122 of the square aperture 121 so as to enhance it in incident electron transmission inhibiting properties. On the other hand, the mask 12 is set small in thickness at the periphery 124 of the linear aperture 123 so as to lessen it in incident electron transmission inhibiting properties, whereby a required electron beam leakage is made liable to occur. A work substrate is mounted on an electron beam plotting device (XY stage) 10, and a pattern on the collective transfer mask 12 of this structure is transferred onto the work substrate through a collective transfer method. At this point, an electron beam 1a penetrating through the non-aperture part of the mask 12 is made to uniformly irradiate the work substrate in a certain range. By this setup, a proximity effect can be easily corrected when a pattern is plotted through a collective transfer method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ULSI (ultra
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam drawing apparatus used for manufacturing a large scale integrated circuit) and the like, and particularly to an electron beam drawing apparatus in which a so-called proximity effect due to scattering of incident electrons in a solid body is reduced by a structure of the apparatus and a pattern forming method using the same.

[0002]

2. Description of the Related Art LSI (large scale integrated circui)
High integration of devices such as t) is supported by the progress of lithography technology that is a means for forming fine patterns.
By the way, until now, the lithographic means of these devices has been photolithography which mainly uses i-line (wavelength: 0.365 μm) of a mercury lamp as exposure light, but the minimum processing dimension of a fine pattern is 0.35 μm, As the exposure wavelength becomes equal to or less than the exposure wavelength, it becomes difficult to process the device by the conventional optical lithography. Therefore, it is necessary to establish a new lithography technique due to this.

On the other hand, as the lithographic means, there is electron beam lithography which uses an electron beam as a radiation source for pattern formation in addition to optical lithography. In this electron beam lithography, a fine pattern can be formed by narrowing down the electron beam. With excellent features such as. Therefore, the post-optical lithography technology has been receiving attention from an early stage, and research and development have been promoted in various places. However, while electron beam lithography has the above-mentioned advantages, since each device pattern is drawn one by one, the problem that the drawing throughput is low, and when drawing a dense and minute device pattern, the incident electrons inside the drawing sample There is a technical difficulty in that it is necessary to correct the so-called proximity effect, which is scattered by. Therefore, DRAM (dynamic
randamaccess memory) and other LSI devices
Electron beam lithography could not be used.

However, recently, it has been found that the drawing throughput can be dramatically improved in the electron beam drawing apparatus. For example, the Digest of Papers Third Micro Process Conference.
pers 3rd Micro ProcessConference), pp. 48-51 (199
0) "EB Cell Projection Lithography" or Digest of Papers 6th Micro Process Conference
Process Conference), pp. 56-57 (1993), "An Elect
ron Beam Block Exposure system for a 256M DRAM lit
As described in "hography", with regard to the drawing of repetitive figures, a method of extracting a basic figure and drawing a group of one figure at a time has been considered. It is called a transfer method.) By using a drawing device that incorporates this method, the possibility of fine processing with both fineness and productivity has emerged.

On the other hand, as for the proximity effect correction method, various proximity effect corrections for obtaining a correction value accurately in a short time with high efficiency have been studied. However, in the commonly used correction of the proximity effect due to the difference in the pattern line width, even if the line width is the same, the correction amount differs if the drawing density is different. Also, when pursuing precision to eliminate this problem, there are some obstacles such as the need for a system with high processing capacity such as a large-scale computer. Therefore, a method of devising a correction corresponding to the proximity effect correction in terms of drawing is also under study. For example, the “resist pattern forming method” in Japanese Examined Patent Publication No. 6-101422 focuses on the difference in stored energy of electrons in a resist film between a large pattern and a fine pattern, and a fine pattern in which the influence of electron scattering is remarkable. In the drawing of, the effect of the proximity effect is affected by performing auxiliary drawing to make the energy storage amount of the main pattern for forming the fine pattern and the energy storage amount of the fine pattern writing portion approximately equal to the maximum energy storage amount of the large pattern. Mitigation methods have been proposed.

[0006]

However, the pattern forming method by the combination of the main drawing and the auxiliary drawing aggravates the problem of the low drawing throughput of the electron beam lithography, which hinders the practical application of the electron beam lithography technique. Become. Further, in the case of writing by the batch transfer method, there is a problem that it is difficult to perform accurate proximity effect correction.

The object of the present invention is to improve the problem of increasing the drawing processing time due to the two drawing processes of the main drawing and the auxiliary drawing of the prior art, and in the case of drawing using a complicated mask such as the batch transfer method. Another object of the present invention is to provide an electron beam drawing apparatus and a pattern forming method using the apparatus for reducing the influence of the proximity effect relatively easily.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide an incident electron to a mask substrate depending on a difference in fineness or density of a basic figure of a batch transfer mask for forming an electron beam into a desired pattern. It is possible to solve the problem relatively easily by using the masks manufactured so that the permeation inhibition ability for the is different. Therefore, the means of the present invention will be described in detail with reference to FIGS. 1 (a), 1 (b) and 1 (c).

First, (a) is an example of a basic figure of a batch transfer mask. Here, the peripheral portion of the square figure opening hole 121 having a large opening area shown in (a) has the above-described opening as shown in the mask cross-sectional view of (b) in order to sufficiently obtain the ability to inhibit the transmission of incident electrons. The film thickness of the hole peripheral portion 122 is increased. on the other hand,
As shown in (b), the peripheral portion of the linear figure opening hole 123 in FIG. 10A is made thinner by reducing the film thickness in the peripheral portion of the opening hole 124 to weaken the impeding ability of incident electrons. Easily caused electron beam leakage. The batch transfer mask 12 having the above structure is mounted on the electron beam drawing apparatus shown in (c), and the work substrate is drawn by the batch transfer method. At this time, the electron beam that has passed through the non-opening hole portion of the mask substrate is uniformly irradiated on the sample surface to be processed within a certain range. Here, the amount of energy accumulated in the drawn substrate to be processed is equal in both the portion corresponding to the square opening hole and the pattern portion corresponding to the linear opening hole, and a desired pattern can be formed. That is, by positively utilizing the leaky beam as described above, the same effect as that of auxiliary drawing can be obtained.
By the way, the effect of impeding the transmission of incident electrons can also be obtained by depositing a heavy metal on the substrate of the mask.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

<Embodiment 1> An embodiment of the present invention is shown in FIGS.
This will be described with reference to FIG. FIG. 1C is a schematic diagram of an electron beam drawing apparatus used to confirm the effect of the present invention. The electron beam drawing apparatus includes an electron beam source 1 that emits at least electrons,
A first beam shaping mask 2 having an electron beam shaping function, a second collective transfer mask 3 having a desired basic figure formed thereon, and electron lenses 4, 5 for focusing an electron beam.
6 and 7, and beam deflection coils 8 and 9 for deflecting the electron beam to a desired region and irradiating only the desired region.
An XY stage 10 for mounting a sample to be processed and driving it arbitrarily, and a control unit 11 for performing desired electron beam drawing.
Consists of The batch transfer mask of this example was mounted on the mask 3 portion of the electron beam drawing apparatus.

In this embodiment, as shown in FIG. 2A, a fine linear figure opening hole transferred to 0.2 μm on the surface of the sample to be processed and a line five times as large as the linear figure opening hole. It is an example of a batch transfer figure composed of square figure opening holes corresponding to the width. Further, as the substrate of the batch transfer mask 21, a silicon substrate which can relatively easily use a semiconductor element processing technique and can obtain a highly accurate processed shape of an opening hole is used.

Here, in designing the collective transfer mask, the ability of impeding the transmission of incident electrons with respect to the acceleration voltage of the silicon substrate was calculated in advance. As a result, the acceleration voltage is 5
It was found that when the voltage is 0 kV, incident electrons can be almost completely blocked when the thickness of the silicon substrate is about 20 μm. Based on this result, as shown in FIG. 2B, the film thickness of the peripheral portion 212 of the square figure opening hole of the mask substrate was set to 20 μm. On the other hand, in the peripheral portion 214 of the linear figure opening hole, the thickness of the silicon substrate is set to 12 μm so that the transmission blocking ability of incident electrons is about 50%.
It became thin with m. Further, here, the thin film region is set to the end of the square figure opening hole 211.

The mask 21 produced as described above was mounted on the electron beam drawing apparatus of FIG. 1C, and a chemically amplified negative resist was drawn with an optimum electron beam irradiation amount.
Both the square pattern and the fine line pattern could be formed in good shapes.

<Embodiment 2> In this embodiment, a heavy metal is deposited on the batch transfer mask to change the ability of impeding the transmission of incident electrons. The size of the pattern is the same as in the first embodiment. This example is shown in FIG. As the batch transfer mask substrate 31, a silicon substrate was used as in Example 1.

First, in order to make the permeation inhibiting ability of the substrate 31 for incident electrons at an acceleration voltage of 50 kV about 50%, a desired opening hole was formed with a substrate film thickness of 12 μm. Then, gold, which is a heavy metal 311, was deposited on the peripheral portion of the rectangular figure opening hole as shown in FIG. 3B to enhance the ability to inhibit the transmission of incident electrons. The gold deposition thickness at this time was 2.5 μm deposited on a desired portion based on the calculation result of the transmission blocking ability of the incident electron of the gold element obtained in advance as in Example 1. Here, the deposition area of the gold element was set to the end of the square figure opening hole as shown in (b).

The mask 31 produced as described above is mounted on the electron beam drawing apparatus of FIG. 1 (c) with an accelerating voltage of 50 kV, and the chemical amplification type positive resist is drawn with the optimum electron beam irradiation amount as before. As a result, as in Example 1, both the square pattern and the fine line pattern could be formed in good shapes.

<Embodiment 3> This embodiment is a batch transfer mask formed so that the desired minimum drawing line width is 0.2 μm in all, and the mask has different opening hole densities of the mask as shown in FIG. This is an example of forming a desired pattern 43 using 41 and 42. Even when a pattern as shown in FIG. 4C is formed with the same electron beam irradiation amount using the patterns as shown in FIGS. 4A and 4B, the first or second embodiment
It turns out that it can be handled in the same way as. in this case,
Since the pattern writing density of (a) is relatively higher than that of (b), the ability of the mask substrate of (a) to inhibit the transmission of incident electrons is set to 50%, while (b) is set to 30%. The desired pattern could be formed by using this function.

Further, the present invention is applied to a batch transfer mask for forming an actual LSI device pattern, resist patterning is performed by an ordinary electron beam drawing process, and a resist pattern forming process including a developing process is further performed. After various dry process of resist pattern and various LSI manufacturing processes such as wiring layer formation,
The LSI device could be manufactured.

Since the essence of the present invention is to reduce the influence of the scattering of electrons in the sample to be processed at the time of drawing by manipulating the transmission blocking ability of incident electrons, the present invention is limited to the above-mentioned embodiment. Not something that is done.

Further, the structure of the peripheral portion of the mask opening hole for enhancing the impeding transmission of incident electrons described in each of the embodiments has a structure in which, for example, a fine opening hole and a relatively large opening hole are close to each other. Taking the example of the batch transfer mask 51 of the transfer pattern 52 as shown in FIG. 5, the structure 511 that surrounds the large opening hole peripheral portion to a maximum extent in a desired range in order to reduce the influence of the proximity effect from the large opening hole. Is more preferable.

Further, by optimizing the transmission blocking ability of incident electrons according to the structure of the batch transfer mask, the proximity effect correction corresponding to the dose correction by pattern line width classification can be easily performed for any batch transfer pattern. be able to. In addition to gold, heavy metals such as tungsten can also be used as the adherent heavy metal that changes the impediment of transmission of incident electrons.

[0022]

Even in the case of drawing such as the batch transfer method, the proximity effect can be corrected relatively easily without incorporating a complicated proximity effect correction system. Therefore, it is possible to contribute to shortening the processing time of fine and highly accurate electron beam writing, strongly promoting the application to mass production technology of electron beam lithography, and further increasing the integration, performance and speed of LSI devices. It is possible to strongly develop the production of semiconductor devices such as.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an outline of the present invention.

FIG. 2 is an explanatory diagram of the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a second embodiment of the present invention.

FIG. 4 is an explanatory view of Embodiment 3 of the present invention.

FIG. 5 is an explanatory diagram of an example of a batch transfer mask of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electron beam source, 1a ... Electron beam, 2 ... Beam shaping mask, 3,12 ... Batch transfer mask, 4, 5, 6, 7 ... Electron lens, 8, 9 ... Beam deflection coil, 10 ... XY stage, 11 ... Control unit 121 ... Square figure opening hole, 122
... Square-shaped figure opening hole peripheral part, 123 ... Linear figure opening hole,
124 ... A peripheral portion of the linear figure opening hole.

Claims (7)

[Claims] 1. An electron beam source for emitting electrons, a first beam forming mask and a second forming mask having an electron beam forming function, or a second collective transfer mask on which a desired basic figure is formed. An electron lens for focusing the electron beam, a beam deflection coil for deflecting the electron beam to a desired region and irradiating only the desired region, and an XY stage for mounting a sample to be processed and arbitrarily driving it. In the electron beam writing apparatus including a control unit for performing desired electron beam writing, the batch transfer mask includes the size of the opening hole forming the batch transfer pattern, the type of the pattern, or the pattern density. An electron beam drawing apparatus comprising a substrate in which the electron transmission inhibiting ability of the substrate forming the opening is changed according to the property. 2. An electron beam source for emitting electrons, a first beam forming mask and a second forming mask having an electron beam forming function, or a second collective transfer mask on which a desired basic figure is formed. An electron lens for focusing the electron beam, a beam deflection coil for deflecting the electron beam to a desired region and irradiating only the desired region, and an XY stage for mounting a sample to be processed and arbitrarily driving it. Further, in the electron beam writing apparatus including a control unit for performing desired electron beam writing, the batch transfer mask has the size or type of the opening holes forming the batch transfer pattern, or the density of the pattern. Accordingly, the electron beam drawing apparatus is characterized in that the film thickness of the substrate of the batch transfer mask in the opening forming portion is changed to a desired thickness. 3. The mass transfer mask according to claim 1, wherein the batch transfer mask for changing the electron transmission inhibiting ability is made of a material such as a heavy metal so that the electron blocking effect is different at a desired portion of the batch transfer pattern. An electron beam drawing apparatus which is a batch transfer mask composed of a substrate adhered to the desired portion. 4. The batch transfer pattern when the pattern length of at least one side of the opening hole of the batch transfer pattern of the batch transfer mask according to claim 1, 2 or 3 is smaller than 1 μm on the sample surface to be processed. Electron beam drawing apparatus for adjusting the electron transmission inhibiting ability of the substrate constituting the substrate. 5. The electron transfer inhibiting ability of the substrate of the batch transfer mask forming the opening hole according to claim 4,
An electron beam drawing apparatus that weakens the above-mentioned permeation inhibiting ability with the miniaturization of the pattern size of the opening hole. 6. The electron transmission inhibiting ability of the opening hole according to claim 5, depending on a size of a pattern transferred inside the collective transfer mask within a range capable of being transferred at one time. An electron beam drawing device that changes the inhibition ability. 7. A pattern forming method for forming a desired pattern using the electron beam drawing apparatus according to claim 1, 2, 3, 4, 5 or 6.