JP2677292B2 - Method for manufacturing semiconductor device and transmission mask for charged particle beam - Google Patents

Description

The present invention relates to manufacturing of a semiconductor device using a charged particle beam exposure of a shaped beam system in which a mask is used to transfer a mask pattern, and a repetitive pattern is efficiently drawn with the charged particle beam. And a means for generating a charged particle beam, and one selected small section in one section of a transmission mask by electromagnetically deflecting the charged particle beam. And a means for exposing the semiconductor to be exposed by reducing the patterned charged particle beam by transmitting through one selected small section of the transmission mask. The partition is sized so that the charged particle beam can be deflected, one small section of the transmission mask is sized so that the charged particle beam can be irradiated onto it at one time, and the pattern of a semiconductor device for exposure is provided. A pattern group including a repeating basic pattern that represents at least a part of a figure that is a unit of repeat for drawing a repeating pattern is formed as a group of small sections within the one section, and is used as drawing pattern information of the semiconductor device. In addition, a step of exposing a pattern by selecting one section as necessary and mechanically moving the transmission mask or electromagnetically deflecting the charged particle beam to sequentially select the small sections in the one section. Configure to include.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of a semiconductor device using charged particle beam exposure such as electron beam exposure, and in particular to shaped beam type charged particle beam exposure for transferring a mask pattern using a mask. Related to the manufacture of semiconductor devices.

In recent years, with the increase in the density of integrated circuits, photolithography, which has been the mainstream for circuit pattern formation for many years, has been replaced by
Exposure to charged particle beam such as electron beam has been studied and has been actually used.

The charged particle beam exposure has a great feature in that a pattern can be formed by using an electron beam or the like which can be electromagnetically controlled, and a fine pattern of a submicron or so-called submicron can be formed. The charged particle beam exposure is roughly classified into a Gaussian beam system and a shaped beam system.

In addition, in this specification, "electromagnetic" means "electrical or magnetic". Electromagnetic control is an electric field,
Including control by magnetic field or a combination thereof.

[Prior Art] Recently, the trend toward miniaturization of semiconductor device patterns has been rapidly increasing. The electron beam exposure has the ability to expose a submicron pattern, and can sufficiently meet the requirement in terms of resolution. However, the exposure of fine spot scanning or continuous shot exposure of a small variable rectangular beam does not improve the processing capability because it is so-called one-stroke exposure. The exposure time becomes very long to expose a large area.

In order to solve this problem, there is a conventional invention of a block pattern exposure method (Japanese Patent Laid-Open No. 52-11985).
This is a method in which a mask having different patterns formed at different block positions is provided in the electron beam path, the electron beam is deflected to select a desired block, and the pattern of the block is exposed. In order to expose various circuit patterns in a short time by this method, it is necessary to form a huge number of patterns on the mask. It is not realistic to create a mask having such a huge number of pattern blocks and perform electron beam exposure.

There are various other proposals based on the same idea as in JP-A-52-119185, but none of them is actually easy to use.

In Japanese Patent Application No. 62-260322, at least one quadrilateral-shaped opening is provided, and a pattern consisting of an aggregate of a plurality of openings, which is an integral multiple of a minimum unit of a pattern repeatedly formed, is provided on a forming diaphragm plate. Is proposing that. The quadrilateral aperture is intended to enable irradiation of as many memory cell patterns as possible at one time while maintaining the versatility of variable rectangular beam exposure. According to this method, one forming diaphragm plate is formed for each repetitive pattern, which is not realistic.

[Problems to be Solved by the Invention] In recent semiconductor devices that require ultra-fine patterns, for example, most of the exposed areas, which are fine, such as 16M-DRAM, are repetitive patterns.

According to the conventional technique, there is a problem that the exposure time becomes longer as the pattern becomes finer.

An object of the present invention is to provide a method of manufacturing a semiconductor device suitable for efficiently drawing a repetitive pattern with a charged particle beam.

Another object of the present invention is, in charged particle beam exposure,
An object of the present invention is to provide a transmission mask for a charged particle beam suitable for manufacturing a semiconductor device having a repeating pattern.

[Means for Solving the Problems] FIGS. 1A, 1B, and 1C show the basic concept of the present invention. Referring to FIG. 1 (A), a charged particle beam 10 is generated from a charged particle beam generating means 1, is deflected by a deflecting means 2 for electromagnetically deflecting the charged particle beam, and impinges on a transmission mask 3. . The transparent mask 3 is mechanically moved by mechanical driving means 9a and 9b. Fig. 1 (B)
As shown in FIG. 3, the transmission mask 3 is provided with a plurality of sections 4, and each section is further provided with a plurality of small sections 5. Each small section 5 is an area irradiated by the charged particle beam at one time, and each section 4 is a range in which the deflecting means 2 can scan the charged particle beam. As shown in FIG. 1 (C), the subdivision group has a repeating basic pattern 5b that represents at least a part of a figure that is a unit of repeat of a repeating pattern.
And an opening pattern 5a for synthesizing a non-repeating portion with a pattern such as a variable rectangle similar to the conventional one. If necessary, a matching alignment pattern 5c for alignment is further provided. The alignment pattern 5c for alignment is provided at a key place in each partition and is used for alignment alignment of the small partition. The repeating basic pattern 5b is convenient for forming a repeating pattern characteristic of the device to be manufactured, and is selected within a range that meets requirements such as obtaining a charged particle beam with less aberration. For example, one or several DRAM cells or SRAM
One cell or at least a part of several cells may be targeted. The repeating basic pattern 5b is configured such that a repeating pattern can be drawn by connecting one of the repeating basic patterns 5b itself with a head-to-tail or connecting a combination of some of them with a head-to-tail. For example, when an attempt is made to combine rectangular patterns as shown in the right side of FIG. 1C, a pattern including a plurality of combinations of a plurality of rectangular patterns and a plurality of rectangular patterns on the left side are distributed. There are patterns etc. If a large pattern of a complicated figure is used, the number of types of the non-repeating pattern is likely to be extremely large. Therefore, as in the conventional case, a pattern is formed by combining variable rectangular openings. Therefore, the opening pattern 5a is required. As a result, it is desirable to install the opening pattern 5a having a rectangular shape having a common shape at least partially in each of the many sections.

The patterned charged particle beam 10 which has passed through the transmission mask 3 is reduced by the reduction exposure means 7 to be exposed 8
Irradiated on top.

[Operation] The number of exposure shots can be greatly reduced by patterning a complicated figure to some extent. If you try to pattern all the patterns, the number will be enormous. If it is attempted to form it on a transmission mask for one reduction exposure system, the size of the transmission mask becomes very large, and the range in which the charged particle beam can be electromagnetically deflected is easily exceeded. Electromagnetic deflection can be performed in, for example, about microseconds, but if the transparent mask 3 is mechanically moved,
It easily consumes tens or hundreds of milliseconds.
Therefore, the exposure time becomes long.

The transmission mask is divided into a plurality of sections, each section having a size capable of electromagnetically deflecting the charged particle beam, and a repeating basic pattern convenient for drawing a figure including one repeating pattern together with a non-repeating pattern opening pattern. It is possible to expose the repetitive pattern efficiently in a short time by storing it in one section and preparing a repeating basic pattern in each section corresponding to different figures.

Providing a plurality of sections on the transmission mask, mechanically moving the transmission mask to set one desired section within the deflection range of the charged particle beam, and thereafter, scanning and exposing the charged particle beam by electromagnetic deflection. Thus, many figures can be efficiently exposed using a single transmission mask.

When exposing a new pattern, mechanical drive means 9a, 9b
The transmission mask 3 is moved by and the appropriate section 4 is selected.

Since a relatively large pattern on the transmission pattern 3 is reduced, it is easy to form a latent image with a desired resolution.

[Embodiment] FIGS. 2A to 2E show an embodiment of the present invention.

FIG. 2A shows an electron beam exposure apparatus. Electron gun 21
The electron beam 20 emitted from is shaped into a rectangle by the first shaping aperture 22 and focused by the lens 23. The focused electron beam is transmitted through the transmission mask 26 by the deflector 24 for selecting small sections.
The patterned basic electron beam irradiated to the repeating basic pattern of the arbitrary small section 28 in the upper section 27 is formed by the lens 29.
Then it is focused on the deflector 30. After that, the patterned electron beam is applied to the reduction lens 31, and further the lens
32, a wafer 35 by a deflection system 34 having a deflector 33
It is deflected and exposed. A variable rectangular opening (a slit without a pattern) is also provided on one section 27 of the transmission mask 26 for a non-repeating pattern.

The first shaping aperture 22 is for defining the contour of the electron beam 20, and irradiates only one small section 28 on the transmission mask 26 and does not irradiate the adjacent small section.

The small section selecting deflector 24 deflects the electron beam within one section 27 on the transmission mask 26. For example, on the transmission mask 26, the deflection is performed in one direction to about 3 to 5 mm.

The electron beam 20 patterned by the opening of one small section 28 of the transmission mask 26 is once imaged by the lens 29, and is reduced to, for example, 1/100 by the reduction lens 32. The drawing pattern is made fine by reducing the size.
Therefore, when you want to draw a finer pattern, use a mask
26 It is recommended to expose the pattern above with a large reduction ratio.

As shown in FIG. 2B, the transparent mask 26 is formed by thinning the central portion 41 of the silicon wafer 40 in a stencil shape and forming an opening pattern. However, not only silicon but also a metal plate or the like may be used. Central part 41 of the transparent mask 26
As shown in FIG. 2 (C), each has a rectangular shape with a side of 30 to 50 mm, and a plurality of partitions 27 are formed therein. The partition 27 has a rectangular pattern forming area having a side of 3 to 5 mm, which is a range in which the electron beam can be deflected without mechanically moving the mask stage. Separation area between compartments
Separated by 44.

Within one section 27, for example, as shown in FIG. 2 (D), short subsections 28 each having a side of 200 to 500 μm are distributed in a matrix. The size of the small section 28 is determined by the size of the electron beam that can focus the pattern on the wafer 35, which is the object to be exposed, and reduce and expose it.

Another arrangement of sub-compartments within the compartment is shown in FIG. 2 (E). Like the sub-lattice of the lattice structure, it has a configuration in which a small group of alignment matching patterns and a small group of pattern forming patterns are combined. Each reference point of the pattern for shape creation
The coordinate of 0i is identified by the matching pattern for the peripheral alignment.

FIGS. 3A and 3B schematically show a configuration example of a transmission mask by picking up only one section.

In FIG. 3 (A), the Si substrate 51 has a central portion 52 that is thinned by etching from the back surface. Transmission patterns 53a and 53b are formed in the central portion 52, and the electron beam 55 is incident from above the front surface side.

FIG. 3 (B) is a bottom view of the transmission mask of FIG. 3 (A). Between the thin central portion 52 and the thick peripheral portion 51 is a portion 56 of which the thickness gradually changes. The central portion 52 forms one section, and has four sub-sections, which are patternable regions 58a, 58b, 58c, and 58d. The transmissive patterns 53a, 5a are formed in the pattern formable regions 58a, 58b, 58c, 58d.
3b, 53c and 53d are formed. The pattern 53a is a pattern including four rectangles, the pattern 53b is a pattern obtained by comparing two shapes in which one end is bulged in antiparallel, and the pattern 53c is a pattern of two parallel paths having a detour. These are the shapes that are the units of the repeat of the repeating pattern. pattern
53d is an opening for non-repeating patterns, and normally two sides thereof are used to shape the incident beam.

An actual transmission mask includes a plurality of such sections, and it is convenient that the number of patterns in one section is usually larger.

In the exposure process, the basic pattern is repeatedly exposed within one chip of the semiconductor device, for example. For example, the pattern 53c of FIG. 3B is continuously exposed in the vertical direction to expose two long lines in the vertical direction.

When exposing a new shape, an appropriate section is selected according to the shape and the section is mechanically moved to the electron beam irradiation position.

 An example of the mechanical movement mechanism is shown in FIGS. 4 (A) and 4 (B).

In FIG. 4 (A), 61 is a motor, 62 is a joint, and the joint holds the guide 63. Reference numeral 64 is a ball that rotates in an arbitrary direction, and area 65 is a place for mounting a mask plate on which patterns are arranged. A mirror 66 is attached to the side surface and reflects the light from the laser 67 to measure the length. A laser length measuring device is also provided in the vertical direction (not shown), and the mask plate is aligned while monitoring the position.

FIG. 4 (B) shows an electric control part. CPU69 creates exposure data based on the graphic data in file 68,
It is temporarily stored in the buffer memory 70. The pattern generation unit 71 reads the exposure data, the beam forming plate movement control unit 74 issues a command to move an appropriate section to the electron beam irradiation position, and drives the motor 61 via the DA converter 75 and the amplifier 76. After the appropriate section is mechanically moved, the pattern generator 71 reads the pattern of the exposure data, and the DA converter
The electron beam is controlled via the 72 and the amplifier 73.

[Effects of the Invention] Since repetitive basic patterns convenient for exposing one repetitive pattern are collected in one section, repetitive patterns can be exposed in a short time.

Since a plurality of sections are formed on one transmission mask, various repeating patterns can be drawn.

[Brief description of the drawings]

1 (A), (B) and (C) show the basic concept of the present invention, (A) is an overall view, (B) is a plan view of a transmission mask,
(C) is a partial plan view of one section of the transmission mask, and FIGS. 2 (A), (B), (C), (D), and (E) are views for explaining an embodiment of the present invention. (A) is an overall view of the electron beam exposure apparatus, (B) is a cross-sectional view of a transmission mask, (C) is a plan view of the transmission mask, (D) is a plan view of one section of the transmission mask, (E) ) Is a plan view of another section of the transmission mask, FIGS. 3A and 3B are simplified views for explaining the configuration of the transmission mask, FIG. 4B is a bottom view, FIG. 4A and FIG. 4B show a mechanical control unit and the like of the transmission mask, FIG. 4A is a mechanical drive unit, and FIG. In the figure, 1 ... Charged particle beam generation means 2 ... Deflection means 3 ... Transmission mask 4 ... Section 5 ... Small section 5a ... Non-repeating pattern opening pattern 5b ... Repeating basic pattern 5c. Matching pattern 6 ... Separation area 7 ... Reduction exposure means 8 ... Exposed object 9a, 9b ... Mechanical driving means

Claims (2)

(57) [Claims] 1. Means (1) for producing a charged particle beam;
Deflection means (2) for electromagnetically deflecting the charged particle beam to irradiate one selected small section (5) in one section (4) of the transmission mask (3) and the selected transmission mask. Means for exposing a semiconductor to be exposed by reducing the patterned charged particle beam by passing through one small section, and using one section (4) of the transmission mask (3) as the charged particle. The size is such that the beam can be deflected, one small section (5) of the transmission mask can be irradiated onto the charged particle beam at one time, and a repetitive pattern of the pattern of the semiconductor device to be exposed is drawn. A pattern group including a repeating basic pattern that represents at least a part of a figure that is a unit of repeat is formed as a group of small sections (5) within the one section,
If necessary, one section is selected according to the drawing pattern information of the semiconductor device to mechanically move the transmission mask, and the charged particle beam is electromagnetically deflected to successively select the small sections within the one section. A method of manufacturing a semiconductor device, comprising the step of exposing a pattern by exposure. 2. A transmission mask (3) having a transmission pattern for patterning a charged particle beam, comprising a plurality of sections (4), each adjacent section (4) being a separation region (6). Are separated from each other by a group of subdivisions (5) in each subdivision (4), and the subdivisions within one subdivision are independent patterns and are openings for non-repeating patterns that are often used in the exposure. The small section of the pattern (5a) and the small section of the repeating basic pattern (5b) representing at least a part of a figure which is a unit of repeat for drawing a repeating pattern on the semiconductor chip, and the one section The size of (4) is selected to be a size capable of deflecting the charged particle beam in the charged particle beam exposure apparatus, and the size of the one small section (5) is selected to be a size capable of irradiating the charged particle beam onto it at one time. For charged particle beam transmission mask.