JPS61256627A - Charged particle exposure equipment - Google Patents

Abstract

PURPOSE:To enable continuously correcting the variation of the dimensions of a pattern by providing a sub-deflection control equipment which controls a sub-deflection control equipment which controls a sub-deflection equipment to change the scanning speed of a charged particle beam by a main deflection equipment near the boundary of the non-exposure region and the exposure region of a pictured pattern. CONSTITUTION:The correction of pattern dimensions depends upon a sub- deflection control signal SC generated by a sub-deflection driving equipment 19. The sub-deflection control signal SC has a pulse which has the same timing of the two pulses contained in an edge detection signal ED. The polarity and the gain of the pulse, however, are varied according to the quantity of correction of the dimensions. For example, suppose if the sub-deflection control signal is SC1, i.e., the first pulse is negative and the second pulse is positive, the dimensions are corrected in the longitudinal like a pattern P1. Since the pulse gain can continuously be varied as analog quantity, the quantity of the correction can also be varied continuously.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a charged particle exposure apparatus, and particularly to a charged particle exposure apparatus for forming fine patterns used in the manufacture of semiconductor devices.

(Technical background of the invention) The configuration of the conventional so-called Rusk type charged particle exposure apparatus is
As shown in the figure. A charged particle beam 1 passes through a blanking electrode 2 and a deflection electrode 3 and is irradiated onto a scanning surface 4 . The charged particle beam 1 is deflected by the voltage applied to the deflection electrode 3, and a scanning line 5 is obtained on the scanning plane 4 in the X direction. Scanning plane 4
moves in the Y direction for each scan on the stage, and
A two-dimensional pattern will be obtained on the top. Figure 5 (a
) is an explanatory diagram showing beam scanning in the X direction and movement of the stage in the Y direction. Here, the dashed line indicates the scanning direction, and the band-shaped area separated by straight lines indicates the area to which the beam spot 6 is irradiated by one scanning. After completing one scan, the stage moves by ΔY in the Y direction.

Although the beam spot 6 is represented by a circle in FIG. 5(a), the charged particle irradiation density at the beam irradiation point actually has a Gaussian distribution as shown in FIG. 5(b). In the following description, for convenience, the beam spot will be represented by a circle as shown in FIG. 5(a). Now, Figure 5 (a
), the beam is turned on only when the beam scans this drawing area, and is turned off in other areas. Therefore, irradiation with charged particles is not actually performed at the spot positions indicated by the open circles in the figure, but irradiation with charged particles is performed only at the spot positions indicated by the hatched circles. The 0N10FF of the beam is controlled by the voltage applied to the blanking electrode 2.

The drawing operation will be explained with reference to FIG. 4 again.

The pattern storage device 8 stores two-dimensional patterns for drawing. The pattern data signal generator 9 generates a pattern data signal PD representing exposure/non-exposure information on one scanning line based on this drawing pattern. That is, the signal PD is obtained by converting two-dimensional pattern data into a serial signal. On the other hand, the position measurement circuit 10 is a circuit that detects the movement of the stage in the Y direction, and provides the detected signal to the synchronization circuit 11. The synchronization circuit 11 receives this detection signal, generates a synchronization pulse SP at the end of the movement in the Y direction, and supplies it to the blanking circuit 12 and the deflection circuit 13. The blanking circuit 12 uses this synchronization pulse SP
blanking signal B based on signal PD
A blanking operation is performed by applying L to the blanking electrode 2. Further, the deflection circuit 13 is triggered by the synchronization pulse SP to apply a deflection signal DF to the deflection electrode 3 to scan the beam 1. FIG. 6 shows the relationship among the signals in one scan when drawing the pattern 7 shown in FIG. 5(a).

[Problems with background technology]

When drawing a rectangular pattern 7 as shown in FIG. 7(a) using a conventional charged particle exposure device, scanning is performed as shown in FIG.
b) is carried out in the X direction as shown by the dashed line, and this is
You will have to repeat this direction several times.

For this reason, the drawing pattern that is finally formed is shown in Figure 7 (
The square pattern 7 shown in a) is not the same as that shown in the same figure (C
) as shown in pattern 7'.

That is, on the contour line, the pattern is almost faithfully reproduced in the X direction, but the charged particle density distribution becomes jagged in the Y direction, making it impossible to accurately reproduce the pattern. This is because continuous scanning is performed in the X direction, whereas discrete stage movement is performed in the Y direction. Therefore, when we compare the charged particle density in the sample in the In this direction, this rise becomes very slow, resulting in dimensional variations in the pattern. Conventionally, the following process has been performed to correct this dimensional variation in the X direction. That is, as shown in FIG. 8, a delayed data signal PDD is generated by delaying the pattern data signal PD by a delay time d, and the logical sum (PD), OR (PDD), or logical product (PD) of these two signals is performed.
The blanking operation is performed based on the AND (PDD) signal. As a result, the pattern width W becomes longer as W+ΔW when the OR signal is used, and becomes shorter as W−ΔW when the AND signal is used.

However, such processing by conventional devices has the drawback that accurate correction cannot be performed.

This is because the pattern data signal PD is a digital signal,
The delay time d is caused by the fact that it is created in the form of a digit shift of the digital signal. That is, the delay time d cannot be a continuously variable amount, but takes discrete values.

Therefore, the limit of accuracy correction by the conventional device is correction in units of 0.1 μm.

Furthermore, if the delay circuit d is to be changed significantly, the ROM itself used for the delay circuit must be replaced, which is very inconvenient to operate.

[Purpose of the invention]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a charged particle exposure apparatus that can continuously correct dimensional variations in a pattern.

(Summary of the invention).

The present invention is characterized by a charged particle exposure apparatus that scans a charged particle beam to form a drawing pattern on a scanning surface.
a pattern storage device for storing a drawing pattern; a main deflection device for deflecting the charged particle beam to scan it at a constant speed along a constant scanning line; and a main deflection device for deflecting the charged particle beam in the same direction as the deflection direction by the main deflection device. a sub-deflection device that deflects;
A blanking device that blanks the charged particle beam based on the drawing pattern, and a sub-deflection device that changes the scanning speed of the charged particle beam by the main deflection device near the boundary between the non-exposed area and the exposed area of the drawing pattern. A sub-deflection control device for controlling the apparatus is provided, and correction of dimensional variations is performed by sub-deflection rather than blanking operation, thereby making it possible to perform continuous correction.

[Embodiments of the invention]

The present invention will be described below based on an illustrated embodiment. FIG. 1 is a block diagram of a charged particle exposure apparatus according to this embodiment. This device includes a pattern storage device 8, a pattern data signal generation device 9, a delay device 14, an edge detection bag @1
5. Consists of a blanking device @16, a main deflection device 17, a sub-deflection device 18, and a sub-deflection drive bag @19. A two-dimensional pattern for drawing is stored in the pattern storage device 8, and a pattern data signal generator @9 generates a pattern data signal PD representing exposure/non-exposure information on one scanning line based on this drawing pattern. occurs. This signal PD is applied to delay device 14 and edge detection device 15. Delay device 14 delays this signal PD by a predetermined time d and supplies it to edge detection device 15 and blanking device 16 as delayed data signal PDD. The relationship between signal PD and signal PDD is as shown in FIG.

The blanking device N16 consists of a blanking circuit 12 and a blanking electrode 2, and performs a blanking operation based on the delayed data signal PDD. Therefore, compared to the case where the blanking operation is performed based on the pattern data signal PD, the formed pattern will be shifted by the delay time d, but all patterns will be shifted by the same amount.
No problem will occur because all patterns will be shifted by the same amount.

The feature of this device is that beam scanning is performed by two deflection devices, a main deflection device 17 and a sub-deflection device 18. The main deflection bag @17 is composed of a main deflection circuit 13a and a main deflection electrode 3a. The main deflection circuit 13a applies a main deflection signal DFa as shown in FIG. 2 to the main deflection electrode 3a to perform beam scanning. The sub-deflection device 18 includes a sub-deflection circuit 13b and a sub-deflection electrode 3b.
It consists of The sub-deflection circuit 13b applies a sub-deflection signal DFb, which will be described later, to the sub-deflection electrode 3b to perform beam scanning. In the end, the beam is divided into the main deflection signal DFa and the sub deflection signal DFb.
is scanned according to a deflection signal OF superimposed with

Next, the process of generating the sub-deflection signal DFb will be explained. The edge detection device 15 inputs the pattern data signal PD from the pattern data signal generator 9 and the delay signal PDD from the delay device 14, and outputs the signal PDD as shown in FIG.
generating a first pulse of a predetermined width triggered by the rise of , that is, a change from a state indicating non-exposure to a state indicating exposure;
A second pulse of a predetermined width is generated triggered by the fall of the signal PD, that is, a change from a state indicating no exposure to a state indicating non-exposure. Edge detection signal ED having these two pulses
is applied to the sub-deflection drive device 19.

The sub-deflection drive device 19 generates a sub-deflection control signal SC based on this edge detection signal ED and provides it to the sub-deflection circuit 13b, and the sub-deflection circuit 13b generates a sub-deflection signal DFb based on this sub-deflection control signal SC. Occur.

The size correction of the pattern is determined depending on the sub-deflection control signal SC generated by the sub-deflection drive device 19. Sub-deflection control signal S
C has pulses with the same timing as the two pulses of the edge detection signal ED. However, the polarity and gain of the pulse change depending on the amount of dimensional correction. For example, the second
As shown in the figure, when the sub-deflection control signal is set to 5C(1), that is, when the first pulse is a negative pulse and the second pulse is a positive pulse, the pattern P(1) is obtained. The dimensions will be corrected in the longer direction.

This principle will be explained using FIG. 3. Sub-deflection control signal 5
The sub-deflection control signal DFb generated based on G(1) is
Although this signal has a voltage value to be applied to the sub-deflection electrode 3b, its waveform is almost the same as the signal 5C(1).

However, the pulse portion will be slightly rounded depending on the time constant of the deflection system. In the end, the deflection of the charged particle beam is controlled by the deflection signal D, which is a superimposed signal of the signal DFa and the signal DFb.The time differential of the signal DF is calculated as shown in Fig. 3, dDF/dt. waveform.Deflection signal O
Since F is a quantity corresponding to the scanning position of the charged particle beam, its time differential dDF/dt is a value corresponding to the scanning speed of the charged particle beam. As described above, since the blanking device 16 performs the blanking operation based on the delay signal PDD, the section in which beam irradiation is actually performed is between sections 1-N in FIG. 3. Here, the scanning speed is an interval! It can be seen that it is slow in ~J, fast in interval J~, steady in interval -L, fast in interval LM, and slow in interval M~N. That is, when considering the beam irradiation sections (1) to (N), the scanning speed becomes slow at both ends of the section. Since the charged particle beam intensity is constant, a slower scanning speed means that the charged particle density in the irradiated area increases. Therefore, the influence of the proximity effect due to beam irradiation becomes large, and the pattern P(1) actually formed has an exposed portion size of 11 as shown in FIG. This dimension is longer than the dimension for controlling exposure/non-exposure in the blanking operation (the dimension of the signal PDD in FIG. 2).

Similarly, when the sub-deflection control signal is set to SG<2, that is, when the first pulse is a positive pulse and the second pulse is a negative pulse, exposure P( 2
), the exposed portion dimension L2 is shorter than the dimension. In this way, when making corrections to lengthen the pattern dimensions, the first pulse is negative and the second pulse is positive; when making corrections to shorten the pattern dimensions, the first pulse is positive, the second pulse is negative, and the gain of each pulse h1.
h2 may be adjusted depending on the degree of correction.

Since this pulse gain can be changed continuously as an analog range, the correction amount can also be changed continuously.

〔Effect of the invention〕

As described above, according to the present invention, in a charged particle exposure apparatus, a main deflection device that scans a charged particle beam, a sub deflection device that changes a beam scanning speed at an edge portion of a pattern,
Since this is provided, it becomes possible to continuously correct dimensional variations.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a charged particle exposure apparatus according to the present invention,
2 and 3 are signal waveform diagrams showing the operation of the device shown in FIG. 1, FIG. 4 is a block diagram of a conventional charged particle exposure device, and FIGS. FIG. 6 is a signal waveform diagram showing the operation of the device shown in FIG. 4, and FIG. FIG. 8 is an explanatory diagram of the dimensional correction by the apparatus shown in FIG. 4. 1... Charged particle beam, 2... Blanking electrode,
3... Deflection electrode, 3a... Main deflection electrode, 3b...
Sub-deflection electrode, 4...scanning surface, 5...scanning line, 6...
・Subots 1~. 7... Quadrilateral pattern, 8... Pattern storage device, 9... Pattern data signal generator, 10... Position measurement circuit, 11... Synchronization circuit, 12
... Blanking circuit, 13 ... Deflection circuit, 13a
...Main deflection circuit, 13b...Sub deflection circuit, 14...
- Delay device, 15... Edge detection device, 16... Blanking device, 17... 1 bias. Own device, 18...Sub-deflection device, 19...Sub-deflection drive device, PD...Pattern data signal, PDD...Delay signal, BL...Blanking signal, DF...Deflection signal, DFa...Main deflection signal, DFb...Sub deflection signal. Figure 3 (α) ○:Heam 0FFO゛Beam 0N (b) Horse Figure 5 ((1) (b) Figure 7 Figure 8

Claims (1)

[Scope of Claims] 1. A charged particle exposure apparatus that scans a charged particle beam to form a drawing pattern on a scanning surface, the apparatus comprising: a pattern storage device for storing the drawing pattern; and a pattern storage device for storing the drawing pattern; a main deflection device that deflects the beam to scan at a constant speed along a scanning line; a sub-deflection device that deflects the charged particle beam in the same direction as the deflection direction by the main deflection device;
a blanking device that blanks the charged particle beam based on the drawing pattern; and a scanning speed of the charged particle beam by the main deflection device in the vicinity of a boundary between a non-exposed area and an exposed area of the drawing pattern. A charged particle exposure apparatus comprising: a sub-deflection control device that controls the sub-deflection device so that the sub-deflection device 2. The sub-deflection control device includes a pattern data signal generation device that generates a pattern data signal representing exposure/non-exposure information on one scanning line based on the drawing pattern stored in the pattern storage device; a delay device that outputs a delayed data signal obtained by delaying the input signal by a predetermined time; and a delay device that outputs a first pulse triggered by a change in the delayed data signal from a state indicating non-exposure to a state indicating exposure. an edge detection device that outputs a second pulse triggered by a change in the pattern data signal from a state indicating exposure to a state indicating non-exposure; 2. The charged particle exposure apparatus according to claim 1, further comprising: a sub-deflection drive device that drives the sub-deflection device so as to deflect the sub-deflection device by a desired amount in a desired direction when the charged particle exposure device is deflected by a desired amount in a desired direction. 3. Charged particle exposure according to claim 1 or 2, wherein the main deflection device and the sub-deflection device each have a deflection electrode, and the deflection is performed by applying a voltage to the deflection electrode. Device. 4. The charged particle exposure apparatus according to any one of claims 1 to 3, wherein the edge detection device has a differential circuit.