JPH0722117B2 - Charged particle beam drawing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a charged particle beam drawing method suitable for drawing a pattern having a long minute width.

(Prior Art) Recently, an aperture plate having a plurality of (for example, two) square or rectangular holes, and a focusing lens and a shaping deflector are arranged between the aperture plates along the optical axis. , The charged particle beam that has passed through the light of the upper aperture plate is deflected by the deflector, and the beam of a predetermined cross-sectional shape and size is passed through the hole of the lower aperture plate, and the beam is directed onto the target by the positioning deflector A charged particle beam drawing method (for example, see Japanese Patent Application No. 50-127833) is used for drawing a pattern by drawing a predetermined pattern by irradiating a predetermined position. According to this method, the pattern is drawn by changing the acceptance surface shape and size of the beam in accordance with the shape and size of the pattern drawn on the target, so that the pattern can be drawn at high speed and with high accuracy.

Now, when a pattern with a very small width is drawn by using such a drawing method, the cross section of the beam is shaped to have the same width as the width of the pattern to be drawn and an appropriate length, and the shaping is performed. The beam is moved at a pitch equal to the length of the shaped beam. However, the beam intensity of such a rectangular shaped beam (FIG. 3 (a)) is not uniform, and for example, the beam intensity distribution in the longitudinal direction is sag in the peripheral portion as shown in FIG. 3 (b). There is. Therefore, the joint portion of the pattern for each shot of the drawn pattern is not smooth.

In order to solve such a problem, the following drawing method has been proposed.

FIG. 2 is a diagram for explaining a drawing procedure for drawing the pattern 1 having the minute width ΔW and the length L by sequentially moving the rectangular beam in the direction of the arrow 2. Hereinafter, it is not particularly described that the length of the rectangular beam used for drawing is increased or decreased by the beam cross-section shaping method and the beam is moved by the control of the positioning deflector. First, as shown in the drawing, a small rectangular beam 5 is used for drawing, the next shot is the rectangular beam 6, the next is the rectangular beam 7, and the size of the rectangular beam is increased for each shot. Then, the rectangular beam 8 having the length 1 is reached. During this time, the end points 5'to 8'of the rectangular beams 5 to 8 are fixed while keeping the positions of the end points 3 to the starting point of the pattern 1 and the length of the rectangular beam in the beam moving direction (direction of arrow 2). Increase. The length of the rectangular beam is the length of the beam 5 used for the first shot, which is 1 / n of the reference length l.
(N is an integer). In FIG. 2, since n = 4,
The length of the beam 5 is l / 4. Then beam 6 is 2l / 4,
The length of the beam 7 is 3l / 4, and the length of the beam 8 is 1 at a constant rate. After the length of the rectangular beam reaches l, the beam length is fixed at l and the position of the beam is changed in the direction of the arrow 2 for each shot by the rectangular beams 9, 10, 11, 12, ..., l / Move at a pitch of 4. Then, reaching the rectangular beam 13, the end portion side end portion 13 ′ coincides with the position of the end portion side end portion 4 of the pattern 1. After this, the beam length is reduced by l / 4 for each shot with the rectangular beams 14, 15 and 16, and the rectangular beam 16 with a length of l / 4 is finally shot to complete the entire writing process of the pattern 1.
Between the beams 13 to 16, the positions of the end portions 13 'to 16' on the end point side are fixed while being aligned with the end portion 4 on the end point side of the pattern 1.

According to such a method, in the pattern 1 to be drawn, the exposure amount for four shots is given to all the remaining portions except the joint of each shot. The maximum number of joints between shots is 5 shots or less, and the minimum is 3
Since the number of shots is equal to or more than that of the shots (see Japanese Patent Laid-Open No. 57-112016), the exposure amount is within 4 shots ± 1 shot over the entire pattern 1. That is, the fluctuation of the exposure amount by this method is ± 25% or less. In this embodiment, since n is 4, the fluctuation of the exposure amount is ± 25% or less, but the fluctuation of the exposure amount (± 100% / n) can be made smaller by increasing n.

(Problems to be Solved by the Invention) In the above drawing method, the length L of the pattern 1 to be drawn is good when it is an integral multiple of the pitch (l / n), but the length L of the pattern 1 is When it is not an integral multiple of the pitch (l / n), for example, when the length of the pattern 1 is L + ΔH (ΔH <L / n), after drawing the length of L by the above method, the cross section A rectangular beam having a width of ΔW and a length of ΔH is shaped, the shot time is increased by the beam, and the remaining portion is drawn.

However, it is troublesome to change the shot time only for the final shot.

In addition, since it is difficult to form a beam having an extremely short length, the drawing accuracy at the end point of the pattern is reduced.

The present invention aims to solve such a problem.

(Means for Solving the Problem) Therefore, the present invention shapes the projected image of the charged particle beam on the material surface into a desired shape, and moves the shaped beam at a predetermined pitch to draw a predetermined pattern. In the charged particle beam drawing method, at the start of drawing, the end part of the shaping beam is aligned with the end part of the starting point of the pattern to be drawn, and shaping is performed for each shot while the end part of the shaping beam is fixed. The length of the beam is increased stepwise, and after the length of the shaped beam reaches the reference length, the shaped beam of the reference length is moved for each shot at a pitch smaller than the reference length of the shaped beam. At most, when the distance between the end of the shaped beam and the end of the drawing end of the pattern to be drawn becomes smaller than twice the pitch, the next beam is subtracted from the distance by one pit. Corresponding to The length of the shaped beam is gradually reduced for each shot with the end point side end of the beam fixed while shaping the length to the length obtained by adding the above-mentioned reference length. Then, the plural shots are drawn substantially uniformly on all the portions of the pattern to be drawn.

(Embodiment) FIG. 1 is a diagram showing a procedure of an embodiment of the present invention.
Minute width ΔW and length L + ΔH (ΔH is smaller than the pitch)
The pattern 17 will be described using an example in which a rectangular beam is sequentially moved in the direction of arrow 18 to be drawn. 19 and 20 are patterns
17 shows end points on the drawing start point and end point side. Hereinafter, it is not particularly described that the length of the rectangular beam used for drawing is increased or decreased by the beam cross-section shaping method and the beam is moved by the control of the positioning deflector.

First, when the pitch is set to the reference length l / n (n is an integer), for example, when n = 4, the rectangular beam 5 having the length l / 4 is used for drawing. The next shot is a 2l / 4 rectangular beam 6, the next is a 3l / 4 rectangular beam 7, and the size of the rectangular beam is increased for each shot. Then, a rectangular beam 8 having a length 1 is reached. During this time, the ends 5'to 8'of the rectangular beams 5 to 8 on the starting point side
Is fixed while keeping the position of the end portion 19 on the starting point side of the pattern 17, and the length of the rectangular beam is increased in the moving direction of the beam (direction of arrow 18). After the length of the rectangular beam reaches l, the beam length is fixed to l and the position of the beam is changed in the direction of the arrow 18 for each shot by the rectangular beams 9, 10, 11, 12 ,.
...... and move at l / 4 pitch.

Thereafter, the position of the beam is sequentially moved to perform drawing, and when the rectangular beam 21 is reached, the end 21 ′ of the rectangular beam 21 is moved from the end 20 on the end side of the pattern 17 to be drawn in the direction opposite to the beam moving direction. It is at a distance of l / 4 + ΔH. After this, in the present embodiment, the length of the rectangular beam to be shot next is shaped to l + ΔH, and the end 22 ′ of the rectangular beam 22 is made to coincide with the drawing end point 20 of the pattern 17 and shot. And, this control has rectangular beams 23, 24, 25 and beam length for each shot.
The pattern beam 17 is reduced by l / 4, and the rectangular beam 25 having a length of l / 4 + ΔH is used as the final shot to complete the entire drawing process of the pattern 17. Between the beams 22, 23, 24 and 25, the positions of the end points 22 'to 25' on the end point side are fixed while being aligned with the end point 20 of the pattern 17.

The present invention is not limited to the case of drawing a long pattern with a minute width by a drawing method of shaping the cross-sectional shape and size of an electron beam according to the pattern to be drawn and shooting at a predetermined position, and the same ion beam drawing. It can also be used when a long pattern with a small width is drawn by the method.

(Effect) In the present invention, when the drawing is started, the drawing beam starting point side end part of the pattern to be drawn is made to coincide with the shaping beam starting point side end part,
For each shot, the length of the shaped beam is increased stepwise while the end of the shaped beam on the starting point side is fixed, and after the length of the shaped beam reaches the reference length, the shaped beam of the reference length is obtained. Is moved at a pitch smaller than the reference length of the shaped beam for each shot, and the distance between the end of the shaped beam and the end of the drawing end of the pattern to be drawn becomes smaller than twice the pitch. Then the next beam, 1 from the distance
The beam is shaped into a length corresponding to the distance subtracted by the pitch plus the reference length, and is moved by one pitch, and thereafter, the end of the beam is fixed and the shaped beam of each beam is shot for each shot. Since the length is reduced in stages and multiple shots are drawn almost uniformly on all parts of the pattern to be drawn, if the length of the pattern to be drawn is not an integer multiple of the pitch, the final Since the beam size does not become so small that it cannot be created as in the conventional case, the drawing accuracy at the end point is improved.

Further, since it is not necessary to change the shot time of the final shot as in the conventional case, the operation becomes simple.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a drawing procedure of an embodiment of the present invention, FIG. 2 is a diagram for explaining a conventional drawing procedure, and FIG. 3 is a diagram for explaining an intensity distribution of a rectangular beam. Is. 1 ... Pattern to be drawn, 2 ... Rectangular beam traveling direction, 3 ... End of drawing start point, 4 ... End of drawing end, 5
~ 16 ...... rectangular beam, 5 '~ 8' ... start end side end, 13 '
~ 16 '…… End end side, 21 ～ 25 …… Rectangular beam, 21' ～
25 '... End of end point, 17 ... Pattern to be drawn, 18 ...
… Direction of rectangular beam, 19 …… End of drawing start point, 20 ……
End of drawing end

Claims (1)

[Claims] 1. A charged particle beam drawing method of shaping a projected image of a charged particle beam on a material surface into a desired shape and moving the shaped beam at a predetermined pitch to draw a predetermined pattern, when starting drawing. Match the starting point side end of the shaped beam to the drawing starting point side end of the pattern to be drawn, and gradually increase the length of the shaped beam while fixing the starting point side end of the shaped beam for each shot, After the length of the shaped beam reaches the reference length, the shaped beam having the reference length is moved at a pitch smaller than the reference length of the shaped beam for each shot, and the end point side end portion of the shaped beam is moved. When the distance at the end point side of the drawing end of the pattern to be drawn becomes smaller than twice the pitch length, the reference length is set to the length corresponding to the distance obtained by subtracting one pitch from the next beam. Added length The beam is shaped and moved by one pitch, and then the length of the shaped beam is reduced stepwise for each shot while the end portion of the beam is fixed, so that all portions of the pattern to be drawn are substantially uniform. An electron beam drawing method characterized in that a plurality of shots are drawn on the same.