JPH0793250B2 - Pattern formation method - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a pattern forming method using an exposure apparatus using an electron beam or the like.

[Technical background of the invention]

Conventionally, the following example is known as a drawing method of a raster type electron beam exposure apparatus. That is, as shown in the model diagram of FIG. 3, the spot 1 of the electron beam having the diameter a is deflected in the X direction at a constant speed while the table on which the sample is placed is continuously moved in the Y direction at a constant speed. At this time, ON / OFF of the electron beam is controlled according to the graphic data 2 to be drawn. By this, every time the Y stage moves by the same length ΔY as the size (diameter a) of the spot of the electron beam, X stage moves.
The deflection in the direction is repeated, and scanning is performed in the order of SX ₁ , SX ₂ , SX ₃ , ... SX _n . In general, the drawing width W that can be effectively drawn by one scan is several tens μm to several hundreds μm, and this is defined as a frame. Then, when the scan F1 for one frame is completed, the stage moves in the X direction for one frame, that is, W, and then the scan F2 in the X direction of the next frame is performed. By repeating this, F3, ... F
The sample is drawn in the order of n.

FIG. 4 shows the relationship between the X deflection waveform WS for deflecting the electron beam spot 1 in the X direction and the signal for turning on / off the electron beam in accordance with the graphic data 2 during drawing. In the figure, HS is a synchronizing signal that starts X deflection each time the table moves Δ in the Y direction, and WS is a sawtooth waveform that synchronizes with this and deflects the electron beam in the X direction. SXC ₁ , SXC ₂ , SXC ₃ , SXC
₄ and SXC ₅ are blanking signals corresponding to the scans of SX ₁ to SX _{5 in} FIG. 3, respectively. For example, in the scan of SX ₃ , the position of the drawn pattern and the width of the pattern are
It is controlled by the time of t ₁ , t ₂ , t ₃ , t ₄ . Further, the difference t _s between the time when the synchronization signal for starting the deflection in the X direction is issued and the time when the substantial drawing is performed based on the graphic data is adjusted by the delay line.

[Problems of background technology]

However, according to the conventional technique, the sawtooth wave deflection waveform for deflecting the electron beam is not linear due to the characteristics of the deflection diameter such as the deflection amplifier, and is particularly distorted at the start and end of deflection.
As a result, for example, as shown in FIG. 5, if the sawtooth wave deflection waveform for deflecting the electron beam is ideally linear like VS ₁ , and pattern 11 is drawn, VS ₂
With such a distorted waveform, a pattern 12 is obtained in which both the pattern width and the pattern position are displaced.

As described above, in the conventional electron beam exposure apparatus, the above-described distortion is always generated, and is particularly likely to occur near the deflection start point or the deflection end point. Therefore, for example, distortion of the deflection mode initiation is how to cut that portion is taken by adjusting the t _s shown in Figure 4, but limit the adjusted time t _s to the length of the strain portion Yes, the distortion is applied to the substantial drawing part.

[Object of the Invention]

The present invention has been made in view of the above embodiment, and is one of the deflection ranges corresponding to the deflection voltage for beam raster scanning.
An object of the present invention is to provide a pattern forming method capable of improving drawing pattern accuracy by performing beam blanking control with the distortion at the start and end of deflection in one raster scan being in a beam OFF state. is there.

[Outline of Invention]

The present invention relates to a method of forming a pattern by drawing with an exposure apparatus using an electron beam or an ion beam, in a deflection range corresponding to a deflection voltage for beam raster scanning,
The pattern forming method is characterized in that the beam blanking control is performed with the distortion at the start and the end of the deflection in one raster scan being in the beam OFF state.

Example of Invention

 An embodiment of the present invention will be described below with reference to the drawings.

Example 1 When drawing a pattern as shown in FIG. 6, according to the conventional method,
For example, by dividing the pattern data with a width of 1 frame W, 1
Each time a frame is drawn, one frame W is sent in the beam deflection direction to scan the next frame. In the present invention, for example, the deflection width is increased by ΔW. Then, the pattern data as shown in FIG. 1 is created by setting this ΔW to the beam OFF state. In the figure, 21 to 23 are data of n frames respectively,
Data of (n + 1) frame and data of (n + 2) are shown. 24 and 25 show beam ON data and beam OFF data, respectively. Further, reference numerals 26 and 27 respectively show the actual frame feed width (W) and the deflection width (W + ΔW) when the deflection width is increased by ΔW. Further, reference numeral 28 shows a portion in which beam OFF data is newly added by increasing the deflection width by ΔW. After the pattern data is created, after scanning the n-frame data 21 based on this data, the stage W is moved in the beam deflection direction so that the point P and the point P ′ coincide with each other, and the (n + 1) -frame data 22 To start scanning. After that, this is repeated. As a result, a pattern as shown in FIG. 2 can be formed. In each of FIGS. 1 and 2, the area A,
B and C were patterned at the positions of areas A ', B', and C ', respectively.

Therefore, according to the present invention, the deflection width is increased by ΔW, and the deflection is started by setting this ΔW in the beam OFF state.
The distortion at the end can be cut with the beam turned off.
Therefore, the drawing pattern accuracy can be improved.

Second Embodiment In the first embodiment, the case where the deflection width is changed has been described.
Not limited to this, the same effect can be obtained by substantially shortening the frame width, sending that frame in the deflection direction, and drawing. An embodiment in this case will be described with reference to FIGS. 7 to 9. In FIG. 7, 31 to 33
Is n, (n + 1) by the conventional frame pattern division,
It is an (n + 2) frame. On the other hand, 34 to 36 are n when the substantial frame width is shortened without changing the deflection value of the present invention,
These are (n + 1) and (n + 2) frames. 37 of FIG. 8
39 denotes n, (n +) corresponding to the frames 34 to 36, respectively.
1) and (n + 2) frame data. Based on this data, the deflection width W and the frame feed W-Δ as shown in FIG.
Draw with W '. However, the second embodiment also has the same effect as the first embodiment.

Hereinafter, the above effect will be described with reference to FIGS. 10 to 14 based on the result of drawing a line and space pattern of 4 μm and graphing the pitch variation thereof.

FIG. 10 is a deviation amount characteristic diagram when the conventional deflection width of 256 μm is increased by 32 μm to 288 μm and the frame feed is drawn by the conventional method of 288 μm, that is, the deflection width and the frame feed match. Here, the horizontal axis represents the deflection direction distance (for two frames), and the vertical axis represents the deviation amount from the ideal pitch.
Reference numerals 41 and 42 in the figure respectively denote a first range in which the pitch variation is small except for the deflection start and end where the pitch variation is large with respect to the deflection width 288 μm, and W ₁ is the frame width (288 μm).

FIG. 11 is a deviation amount characteristic diagram when drawing is performed with the frame feed set to 256 μm for the deflection width of 288 μm and the overlapping portion thereof set to beam OFF as in the first embodiment. In addition, 4 in the figure
1 ', 42' and the second range corresponding to the first range 41 and 42 cut a large portion of the respective shift amounts, W ₂ is the frame width (256 .mu.m).

FIG. 12 is a shift amount characteristic diagram in the case of drawing by the conventional method without changing the deflection width. In the figure, 43 and 44 are the third range where the deviation amount is small except the deflection start and end where the deviation amount is large with respect to the deflection width of 256 μm, and 45 is the portion where the deviation amount at the start of deflection is large, Reference numeral 46 indicates a portion having a large deviation amount at the end of deflection. Further, L is 4 μm.

FIG. 13 is a shift amount characteristic diagram in the case of drawing with a substantial frame width and frame feed shorter than the deflection width as in the second embodiment. Incidentally, 43 'in the drawing, 44' the fourth range corresponding to the third range cut a large portion of the respective shift amounts, W ₃ represents a frame width (192μm).

The difference in the amount of shift between the two frames in FIGS. 10 to 13 is slightly different due to the difference in the feeding and returning characteristics in the Y direction perpendicular to the deflection direction. Also, the first range 41,42
And the second range 41 ', 42', and the third range 43, 44 and the fourth range 43 ', 44' do not completely coincide with each other. This is because of the variation due to things. As described above, as shown by 45 and 46 in FIG. 11, the remarkable deviation amount at the start and end of the scan, which appeared in the drawing by the conventional method, is extremely small in FIG. 13 drawn by the method according to the present embodiment. It can be confirmed that
Therefore, it is apparent that the drawing pattern accuracy can be improved according to the present invention.

〔The invention's effect〕

As described in detail above, according to the present invention, it is possible to provide a pattern forming method capable of significantly improving the drawing pattern accuracy as compared with the conventional method.

[Brief description of drawings]

1 and 2 are plan views for explaining the pattern forming method according to the first embodiment, FIG. 3 is a plan view for explaining the drawing method of the raster type electron beam exposure apparatus, and FIG. FIG. 6 is a timing diagram showing the relationship between the periodic signal, the X deflection waveform, and the blanking signal according to the drawing method of FIG. 3, FIG. 5 is an explanatory diagram of the positional deviation and dimension deviation of the drawing pattern when the deflection waveform is distorted, and FIG. Is a plan view for explaining the conventional pattern data, and FIG. 7 is a view for explaining the comparison between the conventional frame pattern division and the method in which the deflection width of the second embodiment is not changed, FIGS. 8 and 9. Is a plan view for explaining the pattern forming method of the second embodiment, FIG. 10 is a deviation amount characteristic diagram by the drawing method in which the conventional deflection width is increased, and FIG. 11 is the deviation amount corresponding to the first embodiment. Deviation amount characteristic diagram by drawing method,
FIG. 12 is a deviation amount characteristic diagram of a conventional drawing method that does not change the deflection width, and FIG. 13 is a deviation amount characteristic diagram of the drawing method that does not change the deflection width according to the second embodiment. 21,37 …… n frame data, 22,38 …… (n + 1) frame data, 23,39 …… (n + 2) frame data, 24 …… Beam ON data, 25 …… Beam OFF data, 26 …… Feed width, 27 …… Deflection width, 28 …… Part to which beam OFF data is added, 34 …… n frames, 35 …… (n
+1) frame, 36 ... (n + 2) frame, 45 ... part where deviation is large at the start of deflection, 46 ... part where deviation is large at the end of deflection.

Claims (1)

[Claims] 1. A method of forming a pattern by drawing with an exposure apparatus using an electron beam or an ion beam, wherein deflection is started and ended in one raster scan within a deflection range corresponding to a deflection voltage for beam raster scanning. A pattern forming method characterized in that beam blanking control is performed with the time distortion set to the beam OFF state.