JPH04168269A - Sputtering system - Google Patents

Abstract

PURPOSE:To instantaneously and precisely discriminate the life of a target by embedding a different material in the recess provided on the rear of the target and furnishing a detector for the specified light emitted from the target when sputter-etched. CONSTITUTION:This sputtering system consists of a target 1 capable of generating a material to be deposited on a substrate 2 by sputtering, a target holder 4, etc. A recess 8 is provied at a part on the rear of the target 1 to be most severely eroded. A material different from the target 1 is embedded in the recess 8. A spectrope element 9 is also furnished, and the light emitted when the different material is sputter-etched by a plasma discharge is spectrally split into the beams of desired wavelengths. The intensity of the split beam is detected by a photosensor 10, and the target 1 is used with maximum efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a sputtering apparatus, and particularly to a target life determination mechanism.

[Prior Art] In a sputtering device, accelerated argon ions collide with the target surface, and atoms and molecules ejected from the target surface are deposited on the processing substrate, but this method is not currently used for industrial purposes. Most of the sputtering equipment used is
It uses a magnetron sputtering method that converges plasma using a magnetic field. For this reason, the target is sputter-etched locally in areas where the magnetic field is strong, and its use limits are at the most heavily eroded area within the target plane.
That is, it is determined by the thinnest part. In other words, when the minimum thickness within the target plane becomes small,
It becomes unusable and the target must be replaced.

In conventional sputtering equipment, the lifespan of a target is determined by integrating the sputtering power from the time a new target is used and comparing that integrated power value with the integrated power value at a preset target usage limit. was.

[Problems to be Solved by the Invention] In the conventional sputtering apparatus described above, the correlation between the sputtering integrated power value and the minimum thickness of the target is investigated by using the target once until the end of its life, and the sputtering integrated power value at the limit of use is determined. Values must be input into the device in advance. However, since the sputter etching speed of the target differs depending on its material, when using a target where the relationship between the sputtering integrated power value and the target's minimum thickness is unknown, it is not possible to determine the lifespan by monitoring the integrated power value. It disappears.

Therefore, in order to determine the lifespan of a target, it is necessary to open the vacuum processing chamber to the atmosphere and actually measure the erosion depth of the target using a caliper or the like each time the determination is made.

In addition, in this method, in order to make the vacuum processing chamber atmospheric,
Before the film can be formed again, high vacuum evacuation, cleaning of the target surface by bliss sputtering, etc. must be performed, which requires a lot of man-hours and time, and further causes a decrease in the operating rate. On the other hand, if sputtering is continued with a long target check period, there is a risk that holes will be formed in the target. In this case, there are problems in that the support plate of the target is also sputtered, contaminating the processing substrate and the inside of the vacuum processing chamber, and eventually cracking the target.

On the other hand, even when using a target with a known relationship between the sputtering integrated power value and the minimum thickness of the target, considering the reproducibility of the relationship between the two and the error in the sputtering integrated power value,
The lifespan is set at the time when a thickness margin of about 2 to 3M is left in the target.

As a result, targets were not used as efficiently as possible.

SUMMARY OF THE INVENTION An object of the present invention is to provide a sputtering apparatus that can accurately determine target life without exposing vacuum processing to the atmosphere.

[Means for Solving the Problems] In order to achieve the above object, a sputtering apparatus according to the present invention includes a target that generates a substance to be deposited on a processing substrate by a sputtering phenomenon, and a target support plate that supports this target. In the sputtering apparatus, a recess is provided on the back surface of the part of the target that is expected to be most eroded, a material different from the target is embedded in the recess, and the material embedded in the recess is caused by plasma discharge. It has a spectroscopic element that separates light emitted during sputter etching into desired wavelengths, and an optical sensor that detects the intensity of the separated light.

[Operation] A recess is provided on the back surface of the part of the target that is expected to be eroded the most, a material different from that of the target is buried in the recess, and when the material embedded in the recess is sputter-etched by plasma discharge, The light emitted by the sensor is split into desired wavelengths, and the intensity of the split light is detected.

[Example] Next, the present invention will be explained with reference to the drawings.

FIG. 1(a) is a sectional view showing the vicinity of the cathode in an embodiment of the present invention, and FIG. 1(b) is a plan view of the target as seen from the back side.

In the figure, ■ is a target, and atoms and molecules scattered from this target adhere to the opposing processing substrate 2 and form a film. 3 is a vacuum container, 4 is a target support plate on which the target 1 is fixed and supported, and both are connected via an insulator 5 and O-rings 6a and 6b for insulation. Furthermore, a cooling water channel (not shown) is provided inside the target support plate 4, and has the function of cooling the target 1, which becomes hot during sputtering. In addition, since the plasma is focused by the magnetic field formed by the magnets 7a, 7b, and 7c, the target is
Localized sputter etching is performed as shown in .

Further, on the back surface of the target 1, there is a recess 1a in a part where the target 1 is expected to be thinnest when it reaches the end of its life.
is provided, and its depth is set to the remaining thickness of the target when the target is judged to have reached the end of its life, for example, 1 mm. In this example, the material of target 1 is A1.
In the recess 1a provided in the Al target 1, a spacer 8 made of a material different from that of the target, for example, Sl, is embedded.

On the other hand, the vacuum container 3 is equipped with a filter 9 that has a high transmittance for wavelengths in a specific range, and an optical sensor 10 that detects the intensity of light emitted when a target is sputter-etched through the filter 9. There is. The filter 9 is selected so that its transmission wavelength is approximately equal to the peak wavelength of light emitted when the material embedded in the recessed portion of the target 1 is sputter-etched. In this embodiment, the material of the spacer 8 is Si, and the peak wavelength of its emission spectrum is known to be 252,288 nm. Therefore, the filter 9 used has a high transmittance for light in the wavelength range including 252 or 288 nm. It is being

Usually, A is sputter-etched by plasma.
Therefore, the output level of the optical sensor 10 is low. Erosion of target 1 progresses with sputtering,
When the erosion depth reaches the concave portion 1a as shown by the virtual line (-dotted chain line), that is, when the target 1 reaches the end of its life, S
The spacer 8 consisting of i is exposed on the surface side of the target,
Sputter etched. Since the wavelength transmitted by the filter 9 is matched to the bean wavelength of the light emitted when 81 is sputter-etched, the output level of the optical sensor 10 increases at this moment, and the device detects that the target l has reached the end of its life. Decide and stop sputtering.

In this example, Si is sputter-etched for a very short time, but the effect is only on one processed substrate, and the amount contained in the deposited thin film is very small.

Thus, the sputtering apparatus of the present invention includes an optical sensor 10.
The life of the target 1 can be determined based on the output.

[Effects of the Invention] As explained above, the present invention embeds a material different from the target in a recess provided on the back surface of the target, and emits light of a specific wavelength when the material embedded in the recess is sputter-etched. By providing a filter and an optical sensor to detect the intensity of the target, the lifespan of the target can be determined instantaneously and with high precision.

In addition, since the accuracy and reliability are superior to the conventional indirect life judgment based on integrated power values, it is possible to set a large target erosion depth when the target reaches the end of its life, which improves target usage efficiency. It has the effect of being able to. Furthermore, since the lifespan of the target can be determined while the vacuum processing chamber is maintained in a vacuum, it is possible to eliminate downtime of the apparatus that occurs when determining the lifespan due to exposure to the atmosphere.

[Brief explanation of the drawing]

FIG. 1(a) is a sectional view showing the vicinity of the cathode in an embodiment of the present invention, and FIG. 1(b) is a plan view of the target as seen from the back side. ■...Target 1a...Concavity 2...
Processing substrate 3... Vacuum container 4... Target support plate 5... Insulators 6a, 6b...
・O-rings 7a, 7b, 7c...Magnet 8...Spacer 9...Filter 10
...light sensor

Claims (1)

[Claims] (1) In a sputtering apparatus that has a target that generates a substance to be deposited on a processing substrate by a sputtering phenomenon and a target support plate that supports this target, the back surface of the part of the target that is expected to be most eroded. a spectroscopic element, in which a recess is provided in the recess, a material different from the target is embedded in the recess, and the light emitted when the material embedded in the recess is sputter-etched by plasma discharge is separated into desired wavelengths; A sputtering apparatus comprising: a light sensor that detects the intensity of the separated light.