JPS5849019B2 - drawing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drawing device such as an electron beam exposure device that draws a pattern by scanning an electron beam, X-ray, or other light beam.

When an IC mask is manufactured using an electron beam exposure system, the resulting IC mask may differ from the desired pattern obtained by the drawing data output signal due to disturbances such as electrical noise or external magnetic field changes. There is.

Therefore, it is essential to check whether the pattern is correctly drawn over the entire range of the mask substrate.

Conventionally known methods for this check include:
There are two options:

(1) Detect the beam irradiated onto the board by detecting secondary electrons using a photomultiplier tube or by detecting the beam current flowing through the board, and display it on a monitor such as a CRT. How to visually check.

(2) A method in which the exposed substrate is developed and then visually observed under magnification using a microscope or the like.

However, both methods (1) and (2) are extremely inefficient as they require visual checks over a wide area.
There is a high possibility that the check was missed.

Especially when it comes to LSIs, the size is, for example, 80 rran square, and the minimum element size within that is about 0.5 μm square.
Visually checking the pattern is a difficult task.

Furthermore, method (2) has a major drawback in that errors cannot be determined if the mask is thrown away after being manufactured.

The present invention has been made in view of the above-mentioned points, and it is an object of the present invention to provide a drawing device that can check errors in patterns due to disturbances during drawing, and can easily check error positions even after development.

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

FIG. 1 shows an example of application to an electron beam exposure apparatus.

In the figure, 1 is a computer, and a desired drawing data signal is output from this computer 1.

This drawing data output signal is converted from parallel to serial by a shift register 2 star 3 according to a signal from a clock pulse control circuit 2.
The planking electrode 5K of the electron beam irradiation device is applied via the planking control circuit 4.

Thereby, the electron beam 7, which is deflected by the deflection system and scans over the mask substrate 6, is turned on and off according to the writing data.

A resist film that is exposed to an electron beam 7 is coated on the entire surface of the mask substrate 6 .

The clock pulse control circuit 2 starts its operation under the control of the Y-direction table position detection circuit 8.

That is, the table 9 on which the mask substrate 6 is placed is
When the table scans one line in the X direction, it is moved one step in the Y direction by a drive circuit (not shown), which is detected by the table position detection circuit 8 and outputs a drawing data signal in synchronization with the next electron beam scan. To send the clock pulse control circuit 2
is designed to be controlled.

A secondary electron detector 10 is composed of a photomultiplier tube and an amplifier, and detects the secondary electron current irradiated from the mask substrate 6 when the electron beam 7 is irradiated.

The output of the secondary electron detector 10 is sent to a comparison circuit 11, where it is compared with the drawing data output signal from the shift register 3 in terms of phase difference, signal width, etc.

The operation of the comparator circuit 11 will be explained below using the time chart shown in FIG.

FIG. 2a shows one of the drawing data output signals from the shift register 3. If electron beam irradiation is performed without any disturbance, the output signal of the secondary electron detector 10 will be the drawing data output signal as shown in FIG. 2b. Both pulse width and phase match the output signal.

If there is any disturbance, the output signal of the secondary electron detector 10 will have a narrow pulse width as shown in Figure 2C, a wide pulse width as shown in Figure 2D, or a pulse width as shown in Figure 2E. The phase may be significantly shifted from the drawing data output signal.

If a mismatch between the two signals is detected, it is determined that an error pattern has been drawn on the mask substrate 6, and the comparison circuit 11
is designed to output an output signal.

The counter 12X for detecting the position in the X direction and the counter 12Y for detecting the position in the Y direction obtain information indicating the position in the X direction and the Y direction on the mask substrate 6, which is irradiated with the electron beam 7, respectively.

That is, since the clock pulse control circuit 2 sends clock pulses corresponding to the number of bits drawn in one scanning line of the electron beam to the shift register 3 in synchronization with electron beam scanning, the output thereof is counted by the counter 12X. The position in the X direction can be determined by this.

Further, the Y-direction position can be determined by counting the output of the Y-direction table position detection circuit 8 with a counter 12Y.

The counter 12X detects the X direction position and checks the number of drawing bits corresponding to one scanning line of the electron beam, and stops the operation of the cloth pulse control circuit 2 when it counts up to the final bit signal of the set number of bits. It has become.

In this way, while the comparator circuit 11 detects drawing errors, the counters 12X and 12Y simultaneously detect drawing position information.

When the comparison circuit 11 receives an output, that is, when an error pattern is drawn, the output signal controls the data latch circuits 1 3X # 1 3Y, and the contents of the counters 12X and 12Y at that time are stored in the memories 14X and 14
Write in Y.

Reference numeral 15 denotes an address counter, which specifies addresses in the memories 14X and 14Y and sequentially stores information on the positions where error patterns are drawn in the memories 14X and 14Y.

As described above, in this electron beam exposure apparatus, it is possible to determine the quality of the exposure pattern while detecting the output of the comparison circuit 11 during exposure, and it is also possible to easily check the position and number of erroneous patterns. It is possible to fabricate patterns for IC masks, etc. very efficiently.

Moreover, since the error portions of the drawn pattern are stored in the memory, they can be used as effective reference data when visually checking the pattern after the development process.

Note that the present invention is not limited to electron beam exposure apparatuses, but can be similarly applied to apparatuses that draw patterns by scanning X-rays or other light beams.

Further, in the embodiment, an error pattern is checked by detecting secondary electrons and comparing them with the drawing data output signal, but instead of the secondary electrons, the beam current flowing through the substrate may be detected.

In addition, the present invention can be modified in various ways without departing from its spirit.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a diagram showing the configuration of an electron beam exposure apparatus according to an embodiment of the present invention, and FIG. 2 is a time chart for explaining the operation of the comparison circuit 11 in the first line. . 1... Computer, 2... Clock pulse control circuit, 3... Shift register, 4...
... Planking control circuit, 5 ... Planking electrode, 6 ... Mask substrate, 7 ...
...Electron beam, 8...Y direction table position detection circuit, 9...Table, 10...2
Secondary electron detector, 11... Comparison circuit, 12X...
...Counter for X-direction position detection, 12Y...
・Y direction position detection counter, 13X, 13Y...
...Data latch circuit, 14X, 14Y...Memory, 15...Address counter.

Claims (1)

[Claims] 1 In an apparatus that performs writing on a desired substrate by applying a writing data output signal to a bushing electrode to control on/off of a scanning beam, the writing data output signal and a secondary electron current obtained from a substrate irradiated with the beam or means for comparing the signal width and phase difference with the beam current signal;
1. A drawing apparatus comprising: a memory for storing the position of a beam irradiation point on a substrate when the comparison results do not match.