JPH04371588A - Etching end point detector - Google Patents

Abstract

PURPOSE:To provide a device of simple structure capable of easily and surely detecting the etching end point of a work with simple operation. CONSTITUTION:This detector is provided with a light source 13 from which a work 1 to be etched is irradiated with ionizing radiation or light and a light- receiving part 14 for detecting the transmitted light quantity or reflected light quantity of the ionizing radiation or light with which the work 1 is irradiated. Since the reflection of light is changed as the etching of the work 1 such as a metal layer formed on the surface of a support 1a proceeds, the etching end point is detected utilizing the transmission or reflection of light.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching end point detection device, and more particularly to an etching end point detection device suitable for detecting the progress or state of etching of a film that does not transmit ionizing radiation or light.

0002

2. Description of the Related Art For example, in electronic components such as printed circuit boards, miniaturization of wiring is progressing. That is, for the purpose of increasing the density of wiring or downsizing of mounted circuit devices, for example, etching using photolithography technology is used to precisely miniaturize wiring.

By the way, etching methods are generally classified into wet methods and dry methods. In addition, the wet type, which is mainly applied to etching metal films, is a dip type in which the object to be etched 1 is immersed in an etching solution 2 to carry out the required etching, as shown schematically in FIG. 4. There are two types: spray type, which sprays etching liquid onto the object to be etched to perform the desired etching. In addition, in FIG. 4, 3 is an etching tank, 4 is an electrode, and 5 is an etching bath.
indicates an electrometer, respectively.

In these etching means, the etching end point is detected as follows. In other words, in the case of the dip type, it dissolves into the etching solution (
Take the profile of the ion concentration or electrode potential of the dissolved metal (dissolved), and set the desired change point as the end point of etching.If using a spray type, perform preliminary experiments in advance to determine the temperature of the etching solution, the time of exposure to the etching solution, etc. The end point of etching is detected by setting conditions in advance.

On the other hand, in the dry type, as shown schematically in FIG. The required etching is carried out by supplying a reactive gas which has been made into a shape and exposing the object 1 to be etched to the reactive gas. In addition, in FIG. 5, 8 is a base on which the object to be etched 1 is placed, 9 is a radiation shield plate, 10 is a plasma spectroscopic detector, and 11
indicate vacuum pumps, respectively.

[0006] In this etching method, the target wavelength emitted by the object 1 to be etched is emitted by plasma gas is measured, or the plasma power and etching gas flow rate are determined in advance as in the case of the spray type. The end point of etching is detected by setting conditions such as etching time in advance.

[0007]

However, the above-mentioned etching end point detection means is premised on stability of the etching process and strict control of etching conditions, which poses a practical problem. For example, in the case of a wet dip type, depending on the number of objects 1 to be etched to be immersed in the etching solution 2 in the etching bath 3,
Alternatively, the required etching time also changes depending on the frequency of use of the etching solution 2. As the etching time changes, the ion concentration and the amount of change in the electrode potential also change, so it has to be said that it is virtually difficult to appropriately determine the etching end point. Moreover, when a plurality of objects 1 to be etched are etched at the same time, it becomes even more difficult because there is uneven etching among the objects 1 to be etched.

In addition, in the case of the wet spray type, the temperature of the etching solution is kept constant and the etching time is selected and set, so the object to be etched is occasionally taken out during the etching process to determine the end point of the etching. is being detected. In other words, since the etching rate changes at an accelerated rate when the temperature of the etching solution changes even slightly, it is necessary to control the etching solution temperature with high precision, and the actual situation is that complicated operations cannot be avoided.

On the other hand, in the case of the dry method, detection of the end point of etching is actually difficult because the plasma light obstructs the detection of the light emitted from the object 1 to be etched being etched in the plasma. Moreover, the reactive gas in the plasma affects the lifetime of excited matter generated from the object to be etched 1 while etching is progressing, and becomes stabilized before reaching the plasma spectroscopic detector 10. There is a problem in that only light can be detected, or there is a possibility that light will emit light again, making the etching end point likely to be unclear. Therefore, in order to detect the etching end point, it is necessary to use both detection using the plasma spectroscopic detector 10 and control based on the etching processing time.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an etching end point detection device that is simple in structure and operation, and can easily and reliably detect and grasp the etching end point of an object to be etched. purpose.

[0011]

[Means for Solving the Problems] An etching end point detection device according to the present invention includes a light source that irradiates the surface of the object to be etched with ionizing radiation or light, and an amount of transmitted light of the ionizing radiation or light irradiated to the surface of the object to be etched. Alternatively, it is characterized by comprising a light reception detection section that detects the amount of reflected light.

That is, the present invention focuses on the fact that light transmission or light reflection changes with the progress of etching of an object to be etched, such as a metal layer formed on the surface of a supporting substrate. The main idea is to use the method to detect and understand the end point of etching.

[0013]

[Operation] According to the present invention, while the required etching process is progressing on the object to be etched, the light transmittance or light reflectivity accompanying the etching of the object to be etched is detected intermittently or continuously. By,
It becomes possible to easily and reliably detect and understand the end point of etching. In other words, it greatly contributes to etching and forming fine patterns with high precision without involving any complicated means.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows a mode in which an etching end point detection device according to the present invention is attached to a so-called etching apparatus to carry out a required etching process. In FIG. 1, 3 is an etching tank, 12 is a circulation pump that circulates the etching solution 2, and 1 is a metal layer such as a chromium layer formed on a light-transmissive supporting substrate 1a such as a glass plate (for example, a metal layer to be etched). ), it is supported almost vertically on a support (not shown) and immersed in the etching solution 2 in the etching bath 3. Reference numeral 13 denotes a light source that irradiates the surface of the object to be etched immersed in the etching solution 2 with ionizing radiation or light. It is placed and attached to the window. Further, reference numeral 14 is disposed and attached to a transparent window portion forming a part of the side wall portion of the etching tank 3 in correspondence with the light source 13, and is attached to the etching target object 1.
This is a light reception detection unit that receives and detects ionizing radiation or light that irradiates the surface and passes through it.

Next, the etching process of the object to be etched 1 and the detection of the etching end point with the above configuration will be explained. Drive the circulation pump 12 to supply the etching solution 2.
is circulated to proceed with the required etching process while preventing concentration unevenness in the etching liquid 2 near the object 1 to be etched. On the other hand, a predetermined ionizing radiation or light is generated and emitted from the light source 13, and the surface of the object to be etched is irradiated. In this example, a light-transmitting glass plate is used as the support base 1a, and since the object to be etched is a chromium layer, a light source 13 that emits white light is used. As the etching process progresses, in other words, as the object to be etched 1 is thinned or removed by etching,
The amount of light transmitted to the surface of the object to be etched increases, and the amount of light received by the light reception detection section 14 also increases, and eventually becomes constant and the end of etching is detected. It is preferable that the etching end point detected by the light reception detection section 14 be a change point slightly before the time when the amount of received light becomes constant. Figure 2
1 schematically shows a mode in which the etching end point detection device according to the present invention is attached to a so-called dry etching device to perform a required etching process. Figure 2
6 an etching chamber, 7 a high frequency generator,
8 is a base on which the object to be etched 1 is placed, 9 is a radiation shield plate, 10 is a plasma spectroscopic detector, 11 is a vacuum pump, 15
A and 15b are preliminary chambers for storing the object to be etched 1 to be etched in the etching chamber 6 or for storing the object to be etched 1 which has been etched in the etching chamber 6. Reference numeral 13 denotes a light source that irradiates ionizing radiation or light onto one surface of the object to be etched disposed in the etching chamber 6, and in this example, a light source forming part of the upper wall of the etching chamber 6. It is placed and attached to the sex window. Further, reference numeral 14 indicates an etching chamber 6 corresponding to the light source 13.
It is placed and attached to the translucent window that forms part of the lower wall of the
This is a light reception detection section that irradiates one surface of the object to be etched and receives and detects the transmitted ionizing radiation or light.

In this configuration, the progress of the etching process or dry etching is similar to that of the conventional dry etching method. That is, the reactive gas is excited by the high frequency generator 6, becomes plasma, and is introduced into the etching chamber 6 as an etching gas. The etching gas introduced here is diffused by the radiation shield plate 9 so as not to directly hit the object 1 to be etched, and participates in the required etching. As the film of the object to be etched 1 is thinned or removed by the dry etching process, the amount of light transmitted onto the surface of the object to be etched increases, and the amount of light received by the light reception detection section 14 also increases. It increases and eventually becomes constant, and the end of etching is detected. In this way, when the end of the required etching is detected, the output of the high frequency generator 6 is stopped and the plasma flow is stopped. In this example, the etching end point can be detected with higher accuracy by shifting the emission wavelength of the plasma and the wavelength of the irradiated light.

In the above, an example of use or configuration for detecting the etching end point by detecting the amount of light transmitted through the object to be etched 1 has been shown. For example, FIG. 3 shows an embodiment of the etching end point detection device according to the present invention. The etching end point may be detected from the amount of reflected light (reflectance), as shown schematically in the main part. In other words, when the supporting base 1a is non-transparent, it is set to a reflective type. Further, the etching process can be applied to a so-called wet spray type etching process, and the etching end point detection device according to the present invention is not limited to the above-mentioned usage mode or configuration.

[0019]

As described above, according to the etching end point detection device according to the present invention, the etching end point of the object to be etched can be easily and precisely detected and grasped. In other words, it is possible to accurately detect and understand the etching end point with good reproducibility, regardless of the etching atmosphere, the life of the etching solution, the concentration of the etching solution, etc. Moreover, since the ionizing radiation or light irradiated onto the surface of the object to be etched can be made into a beam and controlled spot-wise, it can also be applied to selective etching of fine patterns. Furthermore, when used in a dry etching method, since the progress state of etching of the object to be etched is also detected, it is possible to produce an arbitrary etching state with good reproducibility. In this respect, in the case of the conventional dry etching method, the etching rate is almost constant, so the amount detected by the plasma spectroscopic detector is also constant and the etching state cannot be detected, which is significant.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view schematically showing a mode of etching processing performed by an etching apparatus equipped with an etching end point detection device according to the present invention.

FIG. 2 is a cross-sectional view schematically showing a mode of etching processing performed by a dry etching apparatus equipped with an etching end point detection device according to the present invention.

FIG. 3 is a sectional view schematically showing another usage example of the etching end point detection device according to the present invention.

FIG. 4 is a cross-sectional view schematically showing an etching process performed by a conventional etching apparatus equipped with an etching end point detection device.

FIG. 5 is a cross-sectional view schematically showing an etching process performed by a conventional dry etching apparatus equipped with an etching end point detection device.

[Explanation of symbols]

1...Etched object 1a...Support base
2...Etching solution 3...Etching tank
4... Electrode 5... Electrometer 6... Etching chamber 7... High frequency generator 8... Base
9...Breakproof plate 10...Plasma spectroscopic detector
11...Vacuum pump 12...Circulation pump 1
3...Ionizing radiation or light source 14...Ionizing radiation or light reception detection section 15...Preliminary room

Claims (1)

[Claims] 1. A light source that irradiates the surface of the object to be etched with ionizing radiation or light, and a light reception detection section that detects the amount of transmitted light or reflected light of the ionizing radiation or light irradiated to the surface of the object to be etched. An etching end point detection device characterized by: