JPH0557020B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in ion beam processing equipment, and particularly to processing end point detection means that is effective when installed in this type of equipment.

Conventionally, ion beam processing apparatuses that perform sputter processing by irradiating a high-energy ion beam onto a workpiece have not been equipped with a mechanism for detecting the end point of processing with high accuracy. [For example, Applied Physics Letter (Appl.Phys.Lett.)
34(5), March 1979, pp. 310-312] Therefore, it has been impossible to adequately deal with individual differences in the workpieces. Hereinafter, an ion beam mask repair device will be taken up as an example of an ion beam processing device. An ion beam mask repair device is a device that mainly irradiates black spot defects on a photomask for resist exposure with a high-energy ion beam and removes the defects by sputtering. Here, a black spot defect on a mask is an area where a light-shielding material (Cr, Cr ₂ O ₃ , etc.) is originally not present.
Refers to things that adhere regardless of the mask pattern.
What is important in mask correction is that defects can be completely removed and that the underlying substrate (glass, etc.) is not damaged. Conventional mask repair equipment cannot detect the end point with high precision, so it cannot deal with the spread of sunspot defects or irregularities in height.
If the defect cannot be completely removed, or if the lower substrate is processed and the roughness of the substrate surface reduces the light transmittance, black spot defects will be created on the substrate due to the roughness of the substrate. It was hot. Moreover, it cannot cope with changes in ion beam energy and beam current, and the above-mentioned incomplete machining and over-machining have always been a problem.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an ion beam processing apparatus that can perform sputter processing using an ion beam with high precision and good reproducibility.

The gist of the present invention is to provide a first member made of a first material, and a second member made of a second material that is provided on the first member and is a different material from the first material. In an ion beam processing apparatus that removes the second member and exposes the first member by irradiating an ion beam onto a workpiece having a member, the ion beam is irradiated onto the workpiece. means for detecting the number of secondary electrons generated by the processing and detecting the time differential value of the detected value; The ion beam processing apparatus is characterized in that it has means for detecting that the first member is exposed based on a peak value of the differential value.

Hereinafter, the present invention will be explained according to examples.

Here, the aforementioned ion beam mask repair device will be taken up as a representative example of an ion beam processing device.

FIG. 1 shows the basic configuration of an ion beam mask repair apparatus according to the present invention. This is done by monitoring the secondary electrons 8 emitted from the mask defect 5 of the workpiece made of Cr or CrO ₂ by irradiation with the primary ion beam 2 for processing.
This device is equipped with means for detecting the end point of machining. Furthermore, to explain in detail, after the ion beam 2 extracted from the ion source 1 passes through the aperture 3,
A lens 4 is used to irradiate a black spot defect 5 of a mask 6 fixed on a sample stage 7 in a focused manner, and the defect 5 is removed by sputtering. When the defect 5 is irradiated with the ion beam 2, secondary electrons 8 are emitted from the defect 5. This secondary electron 8 is detected by a secondary electron detector 10 and monitored. As the removal of defects 5 progresses, the secondary electron emitting ability (the amount indicating how many secondary electrons are emitted for one ion) of the glass constituting the lower substrate 6 increases as the defect 5 is formed by is
Since it is higher than Cr or CrO ₂ , the count number of secondary electrons 8 changes as shown in FIG. 2a. Normally, the difference between the number of counts of secondary electrons 8 from the defect 5 and the number of counts of secondary electrons 8 from the glass substrate 6 is a small value compared to the number of counts of secondary electrons 8, so the end point of processing is detected. cannot be done accurately. Therefore, in order to more accurately detect the end point of machining, the time differential value of the count number of the secondary electrons 8 can be used as shown in FIG. 2b. In order to extract this differential value as a signal, a lock-in amplifier 11
It was used. The reference signal from the lock-in amplifier 11 is superimposed on the potential of the secondary electron drawing electrode 9 or the sample stage 7, and only the signal synchronized with the reference signal is extracted from the signal of the detected secondary electrons 8. As a result, a differential value of the count number of secondary electrons 8 was obtained as a signal used for end point detection. The end point of machining is F in Figure 2b.
This point was taken as the end point. Whether or not the machining has reached the end point is determined within the machining end point detection controller 12. When the machining reaches the end point, a signal thereof is sent to the blanking electrode controller 13. The blanking electrode controller 13 that received the signal,
Apply voltage to the blanking electrode 14 and
Next, the ion beam 2 is removed from the mask 6 by deflecting it as shown by the broken line until the ion beam 2 is blocked by the aperture 3. Through the above operations, it is possible to completely remove the pattern defects 5 on the mask 6 and perform ion beam processing with good reproducibility without damaging the underlying substrate of the mask 6. Ta.

When using secondary ions emitted from the mask 6 by irradiation with the primary ion beam 2 for processing to detect the end point, the secondary electron detector 10 shown in FIG.
For example, by replacing it with a quadrupole mass spectrometer and performing the same operation as when using the secondary electrons 8 for end point detection, the defect 5 in the pattern on the mask 6 can be removed with high precision. , and can be performed with good reproducibility.

FIG. 3 shows the basic configuration of a reference example of the present invention. This device enters a laser beam 20 from outside the vacuum chamber 23, irradiates the laser beam 20 onto a pattern defect 5, and collects the reflected light. 21 or the transmitted light 22 is monitored to detect the end point of processing. Processing 1 pulled out from ion source 1
Next, the ion beam 2 is focused and irradiated onto the target defect 5 of the mask 6 to perform sputter processing, as in the case of FIG. 1 described above. A laser beam 20 for detecting the end point is transmitted from an oscillator 1 outside the vacuum chamber 23.
5 enters the vacuum chamber 23 through the transmission window 16 and is focused onto the defect 5 by the lens 17. Light 21 reflected from the defect 5 passes through a lens 17 and a transmission window 16 and is monitored by a photodetector 19 outside the vacuum chamber 23. Furthermore, the light 22 transmitted through the defect 5 also passes through the lens 1.
7 and a transmission window 16, and is monitored by a photodetector 18 outside the vacuum chamber 23. The defects 5 on the mask 6 made of Cr, CrO ₂ , etc. on the workpiece are opaque, but the underlying substrate of the mask 6 made of glass is transparent, so as the processing progresses and the defects 5 are removed, , the reflected light 21 decreases and the transmitted light 22 increases. Therefore, the monitored reflected light 21 or
It is possible to use the transmitted light 22 or both to detect the end point of processing. However, even when processing is performed by focusing the primary ion beam 2 for processing to 0.1 μmφ, the laser beam 20 can only be focused to 1.0 μmφ, and the influence of not only the processed part but also the area around the defect 5 is reflected. Light 21, transmitted light 22,
It comes in both. This becomes the background of the reflected light 21 and the transmitted light 22, and has a different value depending on the type of defect 5. Therefore, reflected light 2
1 or by taking the time differential of the intensity of the transmitted light 22 to remove the influence of the background. To obtain the time differential, computer processing was performed within the end point detection controller 12. After that, as in the case of using the above-mentioned secondary electrons, an end point detection signal is sent to the blanking electrode controller 13, a voltage is applied to the blanking electrode 14, and the primary ion beam 2 for processing is deflected as shown by the broken line. The ion beam 2 is prevented from passing through the aperture 3, the ion beam 2 is removed from the mask 6, and the processing is stopped. This reference example also had great effects in improving the accuracy and reproducibility of ion beam processing.

According to the present invention, it is possible to detect the end point in ion beam processing.

[Brief explanation of drawings]

FIG. 1 is an embodiment of the present invention, which is a schematic configuration diagram of an ion beam mask correction device that monitors secondary electrons to detect the end point of processing, and FIG.
b is a graph showing the time change (sputter depth) of the number of detected secondary electrons in the apparatus of FIG. 1 and the time differential curve of the number of detected secondary electrons, and FIG. 3 is a reference example of the present invention, FIG. 2 is a schematic configuration diagram of an ion beam mask repair device that irradiates a processing section with laser light and detects the end point of processing using the reflected light and transmitted light. 1... Ion source, 2... Primary ion beam for processing,
3... Aperture, 4... Electrostatic lens, 5... Mask defect, 6
...Mask (glass substrate), 7...Sample stage, 8...Secondary electrons, 9...Secondary electron drawing electrode, 10...Secondary electron detector, 11...Lock-in amplifier, 12...Processing end point detection controller, 13...Block Ranking electrode controller, 14...Blanking electrode, 15...
Laser oscillator, 16... Transmission window, 17... Optical lens, 18... Transmitted light monitor, 19... Reflected light monitor, 20... Incident laser light, 21... Reflected light, 22
...Transmitted light, 23...Vacuum chamber.

Claims (1)

[Scope of Claims] 1. A first member made of a first material, and a second member provided on the first member and made of a second material that is a different material from the first material. In an ion beam processing apparatus that removes the second member and exposes the first member by irradiating an ion beam onto a workpiece having a member, the ion beam is applied onto the workpiece. means for detecting the number of secondary electrons generated by the irradiation and detecting a time differential value of the detected value; and a means for removing the second member by irradiating the object with the ion beam. An ion beam processing apparatus comprising means for detecting that the first member is exposed based on a peak value of the differential value. 2. The ion beam processing apparatus according to item 1, further comprising means for stopping irradiation of the object with the ion beam based on detection of the peak value.