JP3024757B1 - Electron beam writing method - Google Patents

Abstract

An object of the present invention is to increase the selectable numerical aperture without changing the size of an aperture region that can be selected electro-optically and without reducing the effective drawing speed, thereby improving the throughput. In a continuous moving electron beam writing method, after writing a specific area stripe (17A), movement is performed from an opening (A) to an opening (B) during a turn-back time (a) of a stage. After that, drawing of the stripe 17B is started. At this time,
The position of the opening is measured, and the amount of error in stopping the opening is corrected by applying feedback to the beam deflection position on the sample, thereby performing high-precision drawing. The opening may be moved when the stage is turned back from the stripe 17A to the stripe 17B, or the opening may be moved when the stage is turned back from the chip 16 to the next chip.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to electron beam lithography technique used in the manufacture of semiconductor integrated circuits, in particular an electron beam drawing how to draw the bulk with an electron beam recurring shapes drawing pattern Related.

[0002]

2. Description of the Related Art An electron beam lithography system has a high resolution and a function capable of generating a pattern.
It is used as a photomask manufacturing device in the semiconductor manufacturing process or as a tool for research and development of advanced devices. In recent years, the so-called batch beam drawing method, in which a group of apertures having a specific function is selected by an electron beam and drawing is performed using a beam having the opening shape, has been put to practical use, and the drawing speed has been greatly improved. I have. For this reason, electron beam lithography systems have recently come to be used for mass production lines that have not conventionally been applied in terms of throughput. However, from the viewpoint of further reducing the cost, the electron beam writing method is required to further increase the writing speed. In order to perform complicated and higher-speed drawing on the pattern of the semiconductor element, the type of collective beam, that is, the number of collective apertures may be increased. In a batch writing type electron beam writing apparatus, since it is necessary to select a batch-shaped opening at a high speed, the electron beam is electromagnetically deflected by a selection deflector to select the opening. However, the size of the area on the aperture that can be selected by deflecting the electron beam is not infinite, but is limited by the deflection sensitivity and the electron-optical aberration accompanying the deflection, and the numerical aperture that can be selected by deflection is actually finite. .

Conventionally, when the type of the pattern to be drawn changes, the opening group of the next type is mechanically moved to a selectable area by deflection, and the axis of the electron beam is adjusted again to start writing. Was. These pattern varieties are
Usually, it is composed of a plurality of samples (wafers), and the group of apertures is moved at the frequency of exchanging the samples. Of the semiconductor elements, especially in memories, there are many similar patterns in the pattern, and for example, openings that are symmetrical vertically and horizontally are often used. Providing these symmetrical openings separately reduces the number of batch openings substantially. On the other hand, for example, as described in Japanese Patent Application Laid-Open No. 9-246141, there is a method of increasing the apparent collective numerical aperture by rotating the collectively shaped beam by 180 degrees.

[0004]

As described above, conventionally, since the size of the region is restricted by the electron-optical aberration,
There is a limit to the size of the aperture region that can be selected electro-optically. Therefore, it is difficult to increase the selectable numerical aperture by electro-optics, and as a result, it is extremely difficult to further increase the drawing speed. SUMMARY OF THE INVENTION An object of the present invention is to provide an electron beam lithography method using a collective writing method, in which a collective figure aperture is effectively used without changing the size of an aperture area that can be selected electronically and effectively. without slowing down, it is possible to increase the number of selectable apertures, in that by further providing an electron beam lithography how capable of improving the throughput.

[0005]

To achieve the above object, according to an aspect of, the electron beam writing method of the present invention, the moving mechanism capable of moving provided apertures fast and accurate, it is moved every specific drawing unit While drawing. Also, when selecting the opening of the outer deflectable region selected deflector, using a control device for moving the opening, so that the required opening to enter the selection. Then, a drawing area drawing area particular is divided into strips the sample in the direction of the continuous movement, <br/> Ru you switch their pattern drawing ends at the second opening region mechanically. This ensures, without changing the size of the electro-optically selectable region, and, without reducing the effective drawing speed, by increasing the number of selectable apertures, it is possible to improve the throughput it can.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. (First Embodiment) FIG. 1 is a sectional structural view of an electron beam lithography apparatus showing a first embodiment of the present invention. As shown in FIG. 1, an electron beam 2 emitted from an electron gun 1 is irradiated on a first opening 3, and is further imaged on a second opening 5. The image on the second opening 5 is projected and deflected by the reduction lens 6 and the objective deflecting lens 7, and the sample 8 coated with a photosensitive agent is
The image is projected and projected on the upper side. At this time, a plurality of pattern-shaped openings provided in advance in the second opening 5 are selected by the selection deflector 4. That is, the selection deflector 4 electromagnetically deflects the electron beam 2 to select a plurality of collective figure openings provided around the variable shaping opening at the center of the second opening 5. . The sample 8 placed on the XY stage 9 is moved by the XY stage controller 13 to perform drawing, except for the area deflected by the objective deflection lens 7.

On the other hand, when another type is selected, the second opening 5 is moved by the opening moving mechanism 11 and is controlled by the moving mechanism controller 12 according to the drawing pattern.
That is, by deflecting the aperture group having a pattern different from the current one, the aperture group is mechanically moved to a selectable area under the control of the moving mechanism control device 12, and drawing is started. The control of the whole drawing is uniformly controlled by the drawing control device 10 according to the drawing pattern.

FIG. 2 is a top view showing the second opening in FIG. Usually, a pattern to be drawn is complicated, and it is impossible to draw only a collective figure. The portion other than the area in which the drawing can be performed by the collective figure method is performed by the variable shaped beam method in which the size of the rectangular beam can be changed. For this purpose, the second opening 5 has a shape in which a collective figure opening 14 is arranged around a variable forming opening 15 in the center. In this example, 5 shown in FIG.
One collective figure opening 14 can be selected by the selection deflector 4.

Conventionally, when the type of pattern to be drawn changes, the aperture of the next type is mechanically moved to a selectable area by deflection, and the axis of the electron beam is adjusted again.
I was drawing. These varieties are usually composed of a plurality of samples (wafers), and the opening is moved at this frequency. The reason for this is that if the opening is moved mechanically, it takes longer than the case where the electron beam is electromagnetically deflected, and if the opening is moved frequently, the writing speed is reduced. However, for example, in continuous moving writing in which writing is performed while continuously moving the XY stage, writing is performed for each writing area (stripe) in which the sample is divided into strips in the continuous movement direction. When moving the XY stage to the next stripe after drawing one stripe,
It takes some time. Therefore, according to the present invention, the second opening 5 is set within these periods (that is, each time the divided drawing area ends).
When the is moved mechanically, the number of batch openings can be increased without lowering the overall drawing speed.

FIG. 3 is a diagram showing chips and stripes on the sample in FIG. The operation principle described in FIG.
This will be described with reference to FIG. FIG. 3A shows an example in which drawing is performed on the sample 8. A plurality of chips 16 having a group of functions are arranged on a sample 8 by a semiconductor integrated circuit to perform drawing. At this time, in the continuous movement drawing, a plurality of stripes 1 in the continuous movement direction (shown by the same vertical diagonal line in the figure).
Drawing is performed by dividing into 7A and stripes 17B. That is, after drawing the specific area stripe 17A, the wafer is moved from the opening A to the opening B during the turn-back time a of the stage (see FIG. 5). After that, drawing of the stripe 17B is started. As will be described later, at this time, the position of the aperture is measured by a measuring device, and the amount of stop error of the aperture is corrected by applying feedback to the beam deflection position on the sample,
Perform high-precision drawing. FIG. 3B is an enlarged view of the chip 16 in FIG. A left half of chip 16
If the pattern and the right half are the B pattern, the second opening 5 may be moved between the drawing of the A pattern and the drawing of the B pattern. This is a case where the second opening is moved every time drawing of half of the semiconductor integrated circuit (one chip) is completed.

FIG. 4 is a timing chart showing the relationship between the XY stage and the movement of the aperture. This is because in FIG. 4 showing the arrangement of the second openings, the stripe 1 shown in FIG.
7A is drawn with the opening A, and then the opening 17 is moved from the opening A to the opening B to draw the stripe 17B. FIG. 4 shows the timing of the movement of the XY stage and the opening position at this time. In this example, since the continuous movement direction is the Y direction, the opening position is moved from the opening A to the opening B by changing the X coordinate of the opening position. After the drawing of the stripe 17A is completed, the opening is moved from the opening A to the opening B at the stage turning time, and the drawing of the stripe 17B is performed. When the openings are moved between the adjacent stripes 17A and 17B, the patterns of the openings are arranged such that the adjacent openings such as the openings A and B are used and the moving distance between the openings is minimized. In this case, the moving time between the openings is also minimized.

(Second Embodiment) In the first embodiment, the aperture is moved in units of stripes.
In the case of (A) in which a plurality of types of chips are drawn on one sample 8, the opening may be moved for each chip.
Also, when performing multiple drawing for each of multiple types,
The opening may be moved for each type. That is, FIG.
In (B), the second opening 5 is moved when the writing of one chip composed of the A pattern and the B pattern is completed and the writing of the next one chip is started. This is the case where the second opening is moved each time drawing of the semiconductor integrated circuit (one chip) is completed. In FIG. 3A, a portion separated by a thick black line represents one chip.

(Third Embodiment) FIG. 6 is a sectional structural view of an electron beam lithography apparatus showing a third embodiment of the present invention.
6 differs from the structure in FIG. 1 in that an opening position measuring device 18 is provided at the same position as the second opening 5. In the drawing method of the present invention, it is necessary to perform the mechanical movement of the opening in a short time. Therefore, the position of the opening 5 cannot be adjusted using the electron beam 2 after the stop of the opening movement. In other words, whether the opening really changed,
Whether the location is correct or not can be accurately operated without checking if the accuracy is increased. In this case, the stopping accuracy of the opening 5 is determined by the allowable position error on the sample 8 and the magnification of the electron optical system. Normally, the image of the second opening 5 is projected on the sample 8 in a reduced size, so that mechanical stop accuracy is sufficient. However, as the required drawing accuracy has been improved, mechanical stopping accuracy has become insufficient. In this case, the first method is to improve the mechanical accuracy. However, since the improvement in the mechanical accuracy and the moving speed are in an opposite relationship, the accuracy is limited to a practical moving speed.

On the other hand, if a method of measuring the aperture position and applying feedback to the beam deflection position is used,
High-precision drawing can be maintained even with a certain stop accuracy. For example, as shown in FIG. 6, the position of the second opening 5 is measured by an opening position measuring device 18 such as a laser interferometer. The beam shift amount on the sample 8 is obtained from the measured opening position and the reduction magnification of the opening, and the shift amount is corrected by the selection deflector 4 and the deflector in the objective lens 7. This makes it possible to move the opening at a high speed and maintain high-precision drawing with a constant stopping accuracy. When higher accuracy is required, normal correction such as beam drift correction and beam size correction may be performed immediately after moving the aperture in addition to the above method.

FIG. 5 is a pattern diagram of a second opening showing a fourth embodiment of the present invention.
(A), (B) is a figure which shows the example of application of the pattern of the 2nd opening which is also a 4th Example. In the example shown in FIG. 5, the number of collective figures that can be selected by the selection deflector 4 is five. However, even when the number of collective figures is more than this, the drawing method of the present invention is similarly executed. Can be. That is, in FIG. 5, the collective figure openings 14 inside the deflectable region 19 can be deflected by the selective deflector 4 respectively, and each
Are provided. When the deflectable area 19 shown in FIG. 5 is changed, the deflectable area 19 is mechanically moved by the opening moving mechanism 11 under the control of the moving mechanism control device 12. Usually, as shown in FIG. 5, a set of collective graphic openings 14 is separated by a specific distance so that it can be easily distinguished from an adjacent opening. That is, a predetermined distance exists between the opening A and the opening B. However, if the mechanical movement accuracy of the opening is high, as shown in FIG.
The four may be close to each other without providing a distance. When the frequency of use of the variable shaping beam is low, the number of openings 15 for variable shaping may be reduced to at least one as shown in FIG. 7B.

(Fifth Embodiment) FIG. 8 is a manufacturing process diagram of a semiconductor integrated circuit using an electron beam writing method according to a fifth embodiment of the present invention. FIG.
FIGS. 8A to 8D are cross-sectional views of the element showing the steps. The P well layer 21, the P layer 22, the field oxide film 23, the polysilicon / silicon oxide film gate 24, the P well layer 21, the P layer 22,
The high concentration diffusion layer 25, N high concentration diffusion layer 26 was formed like (FIG. 8 (A)). Then, deposited an insulating layer 27 of phosphosilicate glass (PSG), to form a contact hole 28 an insulating layer 27 by dry etching (FIG. 8 (B)). next,
A material for the W / TiN electrode wiring 30 was applied by a usual method, and the photosensitive agent 29 was patterned thereon (FIG. 8).
(C) ). And W / T by dry etching etc.
The iN electrode wiring 30 was formed. Next, an interlayer insulating film 31 was formed, and a hole pattern 32 was formed by an ordinary method. The inside of the hole pattern 32 is filled with a W plug,
The wiring 33 was connected (FIG. 8D ). For the subsequent passivation step, a conventional method was used.

In this embodiment, only the main manufacturing steps have been described. However, in the lithography step for forming the W / TiN electrode wiring, the same steps as those in the conventional method are performed except that the electron beam writing method of the present invention is used. Using. Through the above steps, a pattern can be formed without deteriorating the quality.
SLSI could be manufactured with high yield. As a result of manufacturing a semiconductor integrated circuit by using the electron beam writing method of the present invention, the production rate per unit time was increased due to the improvement of the writing speed.

[0018]

As described above, according to the present invention,
It is possible to increase the selectable numerical aperture without changing the size of the electron optically selectable aperture area and without reducing the effective drawing speed, thereby improving the throughput. did it.

[Brief description of the drawings]

FIG. 1 is a sectional structural view of an electron beam writing apparatus showing a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an upper surface of a second opening in FIG. 1;

FIG. 3 is a diagram showing chips and stripes on a sample showing a second embodiment of the present invention.

FIG. 4 is a timing chart showing a movement relationship between a stage and an opening in FIG. 1;

FIG. 5 is a diagram showing all patterns of a second opening in the present invention.

FIG. 6 is a sectional structural view of an electron beam writing apparatus according to a third embodiment of the present invention.

FIG. 7 is a diagram of another pattern of the second opening showing the fourth embodiment of the present invention.

FIG. 8 is a manufacturing process diagram of a semiconductor integrated circuit using an electron beam writing method according to a fifth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electron gun, 2 ... Electron beam, 3 ... First aperture, 4 ... Selective deflector, 5 ... Second aperture, 6 ... Reduction lens, 7 ... Objective lens, 8 ... Sample, 9 ... XY stage, 10 ... drawing control device, 11 ... opening moving mechanism, 12 ... moving mechanism control device,
13 ... XY stage control device, 14 ... Opening for batch figure,
15: Opening for variable shaping, 18: Opening position measuring device, 19
... Deflectable region, 16... Chip, 17 A, B... Stripe, 20... N minus silicon substrate, 21... P well layer, 22. , 25 ... P high concentration diffusion layer, 26 ... N high concentration diffusion layer, 27 ... insulating layer, 28 ... contact hole, 29 ... photosensitive agent, 30 ... W / Ti electrode wiring, 31 ... interlayer multi-layer film, 32 ... hole Pattern, 33 ...
Aluminum second wiring.

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Tokuo Saito 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory of Hitachi, Ltd. (56) References JP-A-6-132204 (JP, A) JP-A-4-43629 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027

Claims (3)

(57) [Claims] 1. A sample in a batch writing method using an electron beam.
The drawing on the drawing area (slice) is obtained by dividing the sample into strips.
Electron beam depiction performed by turning and continuously moving every trip
An electron beam writing method for an image forming apparatus , comprising: irradiating an electron beam emitted from an electron source to a first opening.
Shaping the beam into a beam having a predetermined shape, and outputting the beam from the first aperture to the second aperture in advance.
One of the openings for the collective figure of the specified pattern shape provided
Of irradiating a pattern and outputting a beam of the pattern shape
And deflecting the rectangular beam from the first opening by a deflector.
The plurality of collective figure openings provided in the second opening
Selectively irradiating any one of them, and moving the second opening by moving means,
The group of apertures for collective figures in the deflectable area by using
And reducing the beam of the pattern shape from the second opening.
A step of reducing by a lens, and a beam of the pattern shape reduced by the reduction lens.
The step of irradiating the sample with the objective lens, and the continuous transfer of the sample while turning the sample
Moving to the next stripe B after drawing on the stripe A is completed.
While moving the sample by the sample stage for writing
Moving the second opening by the moving means;
An electron beam drawing method, comprising: 2. A sample in a batch writing method using an electron beam.
The drawing on the drawing area (slice) is obtained by dividing the sample into strips.
Electron beam depiction performed by turning and continuously moving every trip
An electron beam writing method for an image forming apparatus , comprising: irradiating an electron beam emitted from an electron source to a first opening.
Shaping the beam into a beam having a predetermined shape, and outputting the beam from the first aperture to the second aperture in advance.
One of the openings for the collective figure of the specified pattern shape provided
By irradiating the step of outputting the beam of the pattern
And deflecting the rectangular beam from the first opening by a deflector.
The plurality of collective figure openings provided in the second opening
Selectively irradiating any one of them, and moving the second opening by moving means,
The group of apertures for collective figures in the deflectable area by using
And reducing the beam of the pattern shape from the second opening.
A step of reducing by a lens, and a beam of the pattern shape reduced by the reduction lens.
The step of irradiating the sample with the objective lens, and the continuous transfer of the sample while turning the sample
Moving to the next stripe B after drawing on the stripe A is completed.
While moving the sample by the sample stage for writing
Moving the second opening by the moving means;
The position of the moved second opening is determined by the opening position measuring means.
And a position of the second opening measured by the opening position measuring means.
Deviation from the beam irradiated to the second aperture based on the information
Amount, and control the deflector to correct the deviation amount.
Electron beam lithography method comprising Rukoto which have a and that step. 3. The electron beam writing method according to claim 2 , wherein a laser interferometer is used as the aperture position measuring means.
An electron beam writing method, wherein the position of the second opening is measured by the laser interferometer .