JPS61220330A - Method and apparatus for ion beam processing of semiconductor device - Google Patents

Abstract

PURPOSE:To detect the end point of processing easily and exactly, by detecting the change of current flowing in the semiconductor device irradiated by the ion beam, wherein the current detecting means are applied. CONSTITUTION:The ion beam 2 is led out, converged, deflected, and applied to process the semiconductor device 9 like VLSI, etc. The substrate current is amplified by the head amplifier 20, converted to the digital signal by the A/D converter 21, and delivered to the main controller. Changing synchronously with the beam scanning, the substrate current becomes small for the scanning lines of the central part, and becomes large for those of the upper and the lower parts. Therefore, in order to obtain the same signal for all of the scanning lines, the synchronizing signal for the beam scanning is inputted to the main controller 22 from the deflector controller 14. Thus, the main controller processes the given substrate current signal, judges, for example, the end point of processing of the aluminum wiring layer B, sends the ON signal to the blanking power source 17, and cuts off the beam to halt the processing.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a semiconductor device,! ￥ Concerning ion beam processing methods and equipment for K-ion beams such as HCVLSI, etc.

[Background of the invention]

Previously, "Surface Analysis" tabulation, edited by Yasamori, Kodansha 4th edition 198
1 m Published on September 1st, as described on page 61, use a narrow ion beam aperture and a tarp.

There is no device for the purpose of irradiating and processing targets, but SIMSI'-Secondary 9-4-on Mass Spectrocopy J
In the field of mass spectroscopy, the beam is aimed at a target, and the atoms of the target are submerged.

Analyzing the secondary ions that come out has been done. If a SIMS device is viewed as an ion beam processing device, it can be said that the processing end point is detected by detecting secondary ions. However, in the ion beam processing equipment referred to in this invention, the beam current itself that irradiates the target is two to three orders of magnitude smaller than the beam current of SIMS, etc., so the amount of secondary ions generated is small, and these are used for processing. It is difficult to use it for end point detection. Additionally, when attempting to detect secondary ions, a highly sensitive mass spectrometer equipped with a secondary ion energy filter is required.
This will significantly increase the price of processing equipment.

[Purpose of the invention]

The purpose of the present invention is to perform ion beam processing 1c on semiconductor devices.
The present invention provides an ion beam processing method for a semiconductor device and an apparatus for the same, in which the end point of a semiconductor device can be easily detected with a high degree of accuracy.

[Summary of the invention]

The present invention removes processing deviations from a semiconductor device having multiple layers using an ion beam, detects a current flowing through the semiconductor device irradiated with the ion beam using a current detection means, and detects a change in the detected current at a high temperature. Moreover, the present invention provides an ion beam processing method and an apparatus for processing a semiconductor device, characterized in that the processing end point can be easily detected. That is, the present invention can be applied to a bar as shown in FIG. 2 (ta), for example.

Cipation film A1 Aluminum wiring layer B%8i (h/jtf
c.

Silicon substrate with aluminum wiring layer and 5I depending on the location
When processing a semiconductor device such as Vl or SI in which several Oz layers are stacked by scanning an ion beam in a predetermined area as shown in FIG. 2(G), the substrate current flowing from the silicon substrate As shown in Fig. 2(b), in region A where the sipation film is processed, the change in current due to scanning is small, and in region B where the aluminum layer is processed, the change in current due to scanning is large, and 5iOzFfjC We focused on the fact that in the region where the substrate is processed, the change in current due to scanning becomes larger, and in the region where the silicon substrate is processed, the change in current due to scanning after I& is smaller. IcI enables ultra-fine machining to be performed, allowing highly accurate detection of the end point of the layer required for beam machining.

[Embodiments of the Invention] The present invention will be described below based on embodiments shown in the drawings. 1st
The figure shows the basic configuration of an ion beam processing apparatus for carrying out the ion beam processing method for semiconductor devices of the present invention. That is, a voltage is applied between the ion source 1 and the extraction electrode 5 to extract the ion beam 2, and the focusing lens 4
to focus the beam onto target 9. In addition to the above-mentioned electrodes, the ion optical system includes a beam defid/guarantee 5, a blanking electrode 6, a graph/king aperture,
A deflector electrode 8 is provided. Blanking electrode 6
A voltage is applied from the blanking electrode 17, the ion beam is deflected at high speed, and the beam is turned on and off at the tarp. In addition, the ion beam deflection voltage is applied to the Guifuta electric @ 8 from the Guifuta controller 14, and the same deflection voltage is applied to the deflection WL of the C T1s.
Give it to the sick. At this time, the secondary electrons 11 generated from the target 9 are detected by the detector 12, and the brightness modulation is applied to the CRT 15 with the signal amplified by the amplifier 15, thereby obtaining a secondary electron signal on the surface of the target 9. Using the same principle as a scanning electron microscope, it can be used as a scanning ion microscope to observe the surface of the processed surface. Now, perform processing positioning. Further, the current taken out from the table 10 is measured with an ammeter 16 and recorded on a recorder 18.

Next, specific examples of the present invention will be described.

<Embodiment t> FIG. 3 shows an embodiment of the present invention. As mentioned above, the ion beam 2 is extracted, focused, and deflected, and the V
A semiconductor device 9 such as an LSI is processed. At this time, the substrate current is amplified by the amplifier 20, and the A/D converter 2
1 as a digital signal and input it to the main controller 22. In addition, the substrate current changes in synchronization with beam scanning,
It is small in the central scanning line, and large in the scanning lines at the upper and lower ends. Therefore, a beam scanning synchronization signal is input from the deflector controller 14 to the main controller 22 so that the same scanning line signal can always be obtained. The main controller 22 processes the input substrate current signal, determines the end point of processing up to, for example, aluminum wiring layer B, sends a button-on signal to the blanking power supply 17, cuts off the beam, and stops processing.

The substrate current changes BK as shown in FIG. 4(a) as processing progresses. The substrate current reaches its maximum value when one scan ends and the next scan begins. Furthermore, the value is the minimum value at the center of the scanning area. Therefore, the maximum current value of the substrate X current as shown in FIG.
Monitor min. This time, one scan was relatively slow on the order of one second, so we extracted signals using a synchronization signal, but 1
When scanning is made faster, the synchronization signal is used as a trigger for A/
The system is changed to one in which the D gomperter 21 is operated. Figure 4 (
Although it is possible to obtain the minimum value as shown in b) and detect the end point of processing only from the change in the minimum value over time, depending on the structure of the semiconductor, the minimum value may not vary significantly depending on the material. In that case, the difference between the maximum value and the minimum value of the substrate current is calculated, and monitoring is performed during the change as shown in FIG. 4(c), thereby making it possible to accurately detect the end point.

Currently, the processing speed is about Q, 1 μns l/SeC.

When machining a rectangular shape of 2 μm x 2 μm, the processing speed in the depth direction is CLO 25 μm/see. - scan 1
Machining is proceeding in seconds, but since the end point is determined by sequentially comparing four points, α1pm machining progresses while the end point is being determined. However, the thickness of the glabella insulating film is about 1p#1, and for practical purposes (11%), there is no problem even if M processing progresses, and the end point detection N degree is sufficient.If even higher precision processing end point detection is required. d Increase the scanning speed or reduce the number of scanning lines,
- The depth processed by scanning can be reduced.

<Example 2> FIG. 5 is an explanatory diagram of this example. In this embodiment, it was considered that only changes in pure substrate current could be monitored, excluding the effect of secondary electrons. The secondary electrons 11 apply a positive potential to the lead-in electrode 24 from the lead-in power source 23, and most of them are introduced into the Faraday force or tube 26. faraday cup 2
At 6, a negative potential is applied to the electron trap electrode 25 from a source 27 so that the secondary electrons generated therefrom do not escape. Furthermore, the Faraday force pu 26 itself is floated to a positive potential by the secondary electron accelerating power supply 28. The secondary electron current is amplified by the amplifier 29 in the same way as the substrate current, and then
It is subtracted from the substrate current by a subtracter 30. The substrate current, excluding the effect of secondary electrons, passes through the A/D converter 31 and is signal-processed by the main controller 22 to determine the end point of machining and send an on signal to the blanking power supply 17 to stop the machining. Change in substrate current excluding the effect of secondary electrons (Figure 4 fb)
Although a change close to the minimum value of the substrate current shown in FIG. 1 is obtained, this completely reflects only the 9-direction current to the substrate, and the reliability of end point detection is increased. However, since the end point is determined using the same method as in Example t, an error of about 11 μm occurs.

However, this does not pose a practical problem.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to detect the end point of machining with an accuracy of less than [L1 μm, so damage to the lower part can be suppressed to an extent that is not a problem in practice. In addition, since other methods require a single Xl equipment configuration compared to, for example, a method of detecting secondary ions, they have the effect of reducing the cost of the processing equipment and at the same time increasing the reliability of end point detection.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of the ion beam processing apparatus, Fig. 2 is an explanatory diagram showing the processing process, Fig. 3 is an equipment configuration diagram of Example t, Fig. 4 is an explanatory diagram showing signal processing of substrate current, FIG. 5 is a diagram showing the equipment configuration of Example 20. DESCRIPTION OF SYMBOLS 1... Ion source, 2... Ion beam, 3... Extraction electrode, 4... Actual speed lens, 5... Beam-defining aperture, 6... Blanking electrode, 7... Blanking aperture, 8... Deflector electrode, 9... Tarp, ), 10... Table, 1
1...Secondary electron, 12...Secondary electron detector, 1
5... to doorbell, 14... deflector controller, 15... CRT, 16... ammeter, 17...
・Blanking power supply, 19...Recorder, 20...
To, door, 21...A/D converter, 22...
・Main controller, 23...Secondary electron drawing power supply, 24...Secondary electron drawing electrode, 25...Secondary electron trap electrode, 26...Faraday force, 27
. . . Secondary electron tracker, pull electrode, 28 . . . Secondary electron accelerating power source, 29 .
1... A/D converter. 1st figure 2nd figure 3 illustrator 4 illusion 50

Claims (1)

[Claims] 1. An ion beam emitted from an ion source is focused by an ion optical system, further deflected by a deflection electrode, etc., and irradiated onto a semiconductor device having multiple layers, and a current flows through the irradiated semiconductor device. A method for processing a semiconductor device with an ion beam, the method comprising detecting the current by a current detection means, and detecting and processing the end point of processing a certain layer of the semiconductor device based on a change in the detected current. 2. The ion beam processing method for a semiconductor device according to claim 1, wherein the current leaks to the substrate as a current flowing through the semiconductor device. 3. The ion beam emitted from the ion source is focused by an ion optical system, further deflected by a deflection electrode, etc., and irradiated onto a semiconductor device having multiple layers, and the current flowing through the irradiated semiconductor device is detected by a current detection means. Then, secondary electrons generated from the irradiated semiconductor device are detected by a secondary electron detection means, and the end point of processing a certain layer of the semiconductor device is detected and processed based on a change in the difference between these detected signals. An ion beam processing method for semiconductor devices characterized by: 4. An ion source that emits an ion beam, an ion optical system that focuses the ion beam emitted from the ion source, a deflection electrode that deflects the ion beam emitted from the ion source, and the ion optical system and deflection. A table on which a semiconductor device is placed, which is irradiated with an ion beam focused and deflected by an electrode, a current detection means for detecting a current flowing through the semiconductor device, and a current detection means for detecting a change in the current detected by the current detection means. An ion beam processing apparatus for a semiconductor device, characterized in that it is equipped with processing end point detection means for detecting the end point of processing. 5. An ion source that emits an ion beam, an ion optical system that focuses the ion beam that is emitted from the ion source, a deflection electrode that deflects the ion beam that is emitted from the ion source, and the ion optical system and deflection. A table on which a semiconductor device is irradiated with an ion beam focused and deflected by an electrode, a current detection means for detecting a current flowing through the semiconductor device, and secondary electrons generated when the semiconductor device is irradiated with the ion beam. The end point of machining is detected based on a change in a machining end point detection signal obtained based on a Faraday cup that captures and detects a secondary electron signal detected from the Faraday cup and a current signal detected from a current detection means. An ion beam processing device for semiconductor devices, characterized in that it is equipped with processing end point detection means. 6. The ion beam processing apparatus according to claim 5, wherein the processing end point detection means obtains the processing end point detection signal by subtracting the secondary electron signal from the current signal.