JPH03180469A - Device for detecting service life of target - Google Patents

Abstract

PURPOSE:To easily discriminate the service life of a target by forming the substrate layer of the target with a material emitting special light and detecting the emitted light. CONSTITUTION:A target 5 is sputtered in a chamber 1 to form a thin film on a substrate. In this case, the substrate layer 6 of the target 5 is formed with an In alloy, and stuck to a plate 7. Sputtering is carried out under such a constitution, and the emitted light characteristic of In is mixed into the light of a discharge field S as the target 5 is progressively consumed and the substrate layer 6 begins to sputter. The light in the discharge field S is condensed by the condensing lens 10 of a detecting means 8 and introduced into a spectroscope 11 through an optical fiber cable 15. The emission wavelength characteristic of In is selectively taken out by the spectroscope 11, transduced into an electric signal (a) by a photoelectric transducer 12, sent to a comparator 13 through a preamplifier 13, and always compared with the reference value (b) of a reference signal generator 14. When the value exceeds the reference value (b) an output (c) is emitted. Consequently, the service life of the target 5 is easily discriminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a target life detection device applied to a sputtering device for forming a thin film.

[Background Art] A sputtering apparatus is a technology for forming a thin film by sputtering particles from a target, which is a raw material for a thin film, and adhering and depositing the particles on a counter substrate.

The target is attached to the target holder via an underlying layer such as a backing plate or bonding material.
Each time it is depleted, it is replaced with a new target.

By the way, in the conventional batch type, the target replacement timing is determined visually or by mechanically measuring the erosion depth. In addition, in the in-line type with a load lock mechanism, the reaction chamber in which the target is placed is not always open to the atmosphere, and the method described above for the batch type cannot be used. When this reaches a certain limit value set empirically, it is determined that the target life has been reached and replacement is performed.

[Problems to be Solved by the Invention] However, the batch type method is an artificial measurement, the measurement environment is poor, and the life determination lacks accuracy. For this reason, the target may be used continuously for a long period of time even after its life has expired, and the contamination of the base material into the film is likely to continue, resulting in the inconvenience of prolonging product defects.

Furthermore, since the in-line method does not rely on direct measurement, it is necessary to set a limit value with some margin. Therefore, the target material is likely to be wasted accordingly.

The present invention has been made in view of these problems, and aims to effectively solve these problems.

[Means for Solving the Problems] In order to achieve the above object, the present invention employs the following configuration.

That is, the target life detection device of the present invention includes a base layer made of a material different from that of the target and closely disposed on the back surface of the target, and a natural characteristic of the material emitted when the base layer is sputtered. It is characterized by comprising a detection means for optically detecting light emission facing the glow discharge field. In addition, if spontaneous light emission cannot be directly expected from the base material due to ion beam sputtering, etc., an excitation means is added to excite the sputtered particles and forcefully emit light when the base layer is sputtered, and the light emission is detected. It may be detected by some means.

[Function] With such a configuration, when the light emission peculiar to the base material is monitored through the detection means, when the target is consumed and the base layer is exposed, sputtering to the base layer starts and the light emission is detected. That will happen.

[Example code] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an example in which the present invention is applied to a general parallel plate type magnetron sputtering apparatus. In this apparatus, a substrate holder 2 and a target holder 3 are arranged facing each other in a chamber 1, a sputtering power source 4 is connected to the target holder 3, and the substrate holder 2 is held at ground potential. Then, an inert gas such as Ar is introduced into the opposing gaps S to generate plasma by magnetron discharge, thereby making it possible to perform sputtering on the target 5 with high efficiency.

As shown in FIG. 2, the target 5 is attached to a backing plate 7 via a bonding material 6 as a base layer, and this backing plate 7 is attached to the target holder 3.
I am trying to attach it to. Various materials are used for the target 5, such as Au and Al5NiSCr, depending on the purpose. In addition, as the bonding material 6, I
n (indium) alloy is used. This is because In has a different emission wavelength from other metals and has a high thermal conductivity, so it is convenient for transmitting the cold heat of the cooling water circulating in the holder 3 to the target 5.

On the other hand, facing the discharge field S, the detection means 8 according to the present invention
is attached. This detection means 8 includes a lens 10 that collects the light of the discharge field S through an observation window 9, and a lens 10 that introduces the collected light via an optical fiber cable 15.
A spectrometer (for example, a monochromator) 11 that selectively extracts a specific emission wavelength, and a photoelectric converter (such as a
For example, a photodiode) 12 and this photoelectric converter 12
It consists of a comparator 13 that constantly compares the electricity (No. 3 a) introduced from the source via a preamplifier 16 with a reference value and outputs C when it exceeds it.The reference value is a reference signal generator. 14, and its size is set to such an extent that spontaneous light emission when the bonding material 6 is sputtered can be captured early and clearly.

FIG. 3 shows how the signal a input to the comparator 13 changes over time when such a sputtering apparatus is operated. As shown by the solid line in Figure 2, target 5
The discharge field S remains sufficiently long and has not reached the end of its life.
The light is only the light emitted from Ar and the target material, and there is almost no light emitted from In, so the output C of the detection device is approximately zero.

However, as the target 5 wears out and the bonding material 6 begins to be sputtered as shown by the broken line in FIG. increases rapidly as shown in FIG. Then, when the signal a exceeds the reference value S at the time indicated by the arrow A, the output C is taken out from the comparator 13, and it is determined that the life of the target 5 has come to an end.

Therefore, if a warning light is activated by the output C, for example, the appropriate time to replace the target 5 will be automatically notified, which will reduce the rate of unused targets and at the same time can be effectively prevented.

Note that the base layer may be a backing plate, etc.
Moreover, materials other than In alloy can also be used. On this occasion,
If spontaneous luminescence cannot be directly expected from the underlying material, an excitation means (using an electron beam, etc.) is added to excite the sputtered particles when the underlying layer is sputtered to force them to emit light. may be detected by the detection means. Further, the optical system from the observation window of the chamber to the spectroscope may have other configurations. moreover,
The spectrometer may be a simple spectroscopic filter as long as it has the necessary resolution. The photoelectric converter is not particularly limited as long as it can extract an electrical signal corresponding to the amount of received light, and the processing system for the signal from the photoelectric converter can also have various configurations and functions.

[Effects of the Invention] According to the target life detection device of the present invention, it is possible to detect by the detection means that the target has been consumed and the underlayer has begun to be sputtered, thereby reducing the waste and excessiveness of replacing the target without using it. This effectively prevents deterioration in film quality due to contamination of the base material caused by overuse of the material, thereby making it possible to improve operating costs and yield.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a conceptual diagram of the structure of a target life detection device applied to a sputtering device, FIG. 2 is a cross-sectional view of a target and an underlayer, and FIG.
The figure is an explanatory diagram of the action. 5... Target 6... Base layer (bonding material) 8... Detection means S... Glow discharge field

Claims (2)

[Claims] (1) Applicable to sputtering equipment,
A base layer made of a material different from that of the target and placed closely behind the target, and a natural luminescence unique to the material emitted when this base layer is sputtered are optically detected by facing a glow discharge field. What is claimed is: 1. A target life detection device comprising: a detection means for detecting a target life. (2) Applicable to sputtering equipment,
an underlayer made of a material different from that of the target and disposed closely behind the target; an excitation means for exciting the sputtered particles to forcibly emit light when the underlayer is sputtered; A target life detection device comprising a detection means for optically detecting a discharge field.