JPH0645896B2 - Low temperature plasma processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a plasma processing apparatus.

[Conventional technology]

Conventionally, this type of film forming and surface treatment apparatus uses an electron cyclotron resonance method using microwaves to generate plasma, so that the generated plasma has high ionization degree and high electron temperature and electron density. For this reason, the temperature of the treated substrate can be lowered, and a film having a high film quality can be formed.

However, taking the case of forming a thin film on a processed substrate as an example, the uniformity on the surface, that is, the uniformity and reproducibility of the film thickness and film quality, depends on the amount of plasma introduced from the plasma generation chamber to the sample chamber. It strongly depends on (electron temperature, electron density) and spatial and temporal homogeneity of the reaction gas for film formation. And in the following known example, even if the discharge state of the plasma changes within the processing time, since there is no function to return it to the immediately preceding discharge state, the uniformity of the plasma immediately after the start of the treatment is impaired just before the end of the treatment. As a result, there was a problem that the film thickness over the entire surface of the substrate, the uniformity of film quality, and the reproducibility were poor. Further, in the past, in order to minimize this problem, the device operator had to keep on observing the discharge state which changes delicately from moment to moment.

FIG. 3 shows a conventional example of a plasma processing apparatus.
This figure shows an example of an electron cyclotron resonance (ECR) type plasma processing apparatus (film forming apparatus) (see Japanese Patent Application Laid-Open No. 55-141729). As shown in the figure, a microwave 2 from a microwave oscillator (not shown) is placed in the plasma generation chamber 1.
Is supplied through the waveguide 3, the cyclotron motion frequency of the electrons due to the magnetic field of the magnetic field coil 4 and the frequency of the microwave 2 coincide with each other, resonance development occurs, and electrons are supplied from the plasma-producing gas supply pipe 5. It collides with the gas for generation 6 and is discharged, and low temperature plasma 7 is generated. In the figure, 8 is cooling water, 9 is a quartz plate, and 10 is vacuum exhaust.

This low-temperature plasma 7 is transported to the sample chamber 11 by a diffusion magnetic field, and activates or ionizes the reaction gas 13 supplied through the reaction gas supply pipe 12 into the sample chamber 11 to remove the sample 15 on the sample table 14. Form a thin film on the surface. In this case, the film quality of the thin film deposited on the surface of the sample 15, the uniformity and reproducibility of the film thickness are controlled by the uniformity of the spatial and temporal distribution of the density and energy of the reaction gas molecules immediately before the deposition. Even if the spatial distribution is temporarily homogenized in this state, due to changes in the surface condition of the container and the accompanying changes in the electromagnetic field in the container space over the treatment time, plasmas that are separated from each other by discharge are separated. The distribution of the amount is significantly different. Therefore, the operator of the apparatus constantly monitors this state change, and adjusts the current value of the magnetic field coil 4 or the microwave oscillator, which is the dominant parameter of the discharge state, in order to return to the previous discharge state when the discharge state changes. There was a problem I had to do. Also, if this adjustment is neglected, there is a problem that the film quality and film thickness uniformity of the thin film after film formation will be significantly different from what is expected from the initially set discharge state, but this has been confirmed by experiments. It is that.

FIG. 4 shows another conventional example of the plasma film forming apparatus. In the figure, 16 is a coaxial transmission tube, and 4a is a static magnetic field generating coil for adjusting the diameter of the plasma flow. This is also a low temperature plasma processing apparatus similar to that shown in FIG. 3, that is, an ECR type film forming apparatus (see Japanese Patent Application Laid-Open No. 57-79621), which operates in the same manner as in the above case, but is similar to the above case. Had a glitch. Regarding this, in addition to the above-mentioned JP-A-55-141729 and JP-A-57-79621, JP-A-56-15
There is a publication of 5535.

[Problems to be solved by the invention]

The above-mentioned prior art is based on the film thickness of the sample after film formation and surface treatment,
No consideration was given to the temporal change in the spatial distribution of low-temperature plasma quantities that directly affect the uniformity and reproducibility of the film quality and surface treatment, and the film thickness, film quality and surface of the sample after deposition and surface treatment were not taken into consideration. There were problems with processing uniformity, reproducibility, and workability during equipment operation.

The present invention has been made in view of the above points, and it is possible to perform film formation and surface treatment with uniform and reproducible film thickness, film quality and surface treatment without monitoring the discharge state within the treatment time. Of course, it is an object of the present invention to provide a low temperature plasma processing apparatus that can ensure the uniformity of the spatial distribution of various plasma quantities.

[Means for solving problems]

The above-mentioned object is to provide a control means for controlling the discharge state of the plasma or the reactive gas being processed in the sample chamber by a plurality of synchrotron radiation spectra of the plasma or the reactive gas being processed,
The control means is provided between a photosensor with a filter for measuring a plurality of radiant light spectra of at least one kind of plasma or a reaction gas in the sample chamber, and the photosensor with the filter and the first or second current controller. Provided, the difference between the measured values of the synchrotron radiation spectrum and the preset value, or the difference between the ratio of the plural radiant spectrum of a plurality of types and the preset value is detected, and the detected difference is And a differential amplifier feeding back to the first or second current controller.

[Action]

The synchrotron radiation spectrum of the low temperature plasma or the reactive gas molecules activated or ionized by the low temperature plasma reflects the density and energy state of the gas molecules in the plasma state. When the atoms of two kinds of A and B are combined to form a film composition after film formation, the intensity ratio between the typical line spectrum A _I of A and the typical line spectrum B ₁ of B is determined by the film composition and the film structure. It is known to strongly influence the generation probability. On the other hand, the spatial distribution of low-temperature plasma quantities is governed by the spatial distribution of microwave intensity or magnetic flux density that determines the electron cyclotron resonance ionization surface. For this reason, one or more synchrotron radiation spectra are measured with a filter or an optical sensor with a spectroscope, and the difference between that value and the preset value that has been measured in advance or the difference between the ratio of multiple spectra and the preset value is calculated. If the current value of the magnetic field coil or microwave oscillator is fed back through the amplifier, the microwave intensity or magnetic flux density distribution will be corrected even if the discharge state changes due to external factors, and the original spatial distribution of various low-temperature plasma quantities will be corrected. Therefore, the film forming conditions can be kept constant within the processing time.

〔Example〕

Hereinafter, the present invention will be described based on the illustrated embodiments. FIG. 1 shows an embodiment of the present invention. Since the same parts as those of the prior art are designated by the same reference numerals, the description thereof will be omitted. As shown in the figure, the microwave oscillator 17 has a first
Power source 18 is connected via a first current controller 19,
A second power supply 18a is connected to the magnetic field coil 4 via a second current controller 19a. In the low temperature plasma processing apparatus configured as described above, in the present embodiment, the plasma 7 or the reaction gas 1 being processed is processed in the sample chamber 11a according to a plurality of emission spectra of the plasma 7 or the reaction gas 13 being processed.
Control means for controlling the discharge state of No. 3 to be constant is provided. By doing so, the sample chamber 11a is provided with a control means for controlling the discharge state of the plasma 7 or the reaction gas 13 being processed to be constant according to a plurality of emission spectra of the plasma 7 or the reaction gas 13 being processed. Like this,
The discharge state of the plasma 7 or the reaction gas 13 during processing becomes constant, and film thickness and film quality and surface treatment are uniform and film formation and surface treatment are performed with reproducibility without monitoring the discharge state within the processing time. It is possible to obtain a low-temperature plasma processing device that makes it possible.

That is, the control means for controlling the discharge state of the plasma 7 or the reaction gas 13 being processed to be constant according to a plurality of radiant light spectra of the plasma 7 or the reaction gas 13 is provided.
This control means is provided in the sample chamber 11a, and photosensors 21 and 22 with filters for measuring two radiant light spectra 20a and 20b in the horizontal direction and the photosensors 2 with filters are provided.
Two synchrotron radiation spectra measured by connecting to 1, 2
The radiant light spectrum 20 calculated by the divider 23 is connected between the divider 23 for calculating the ratio of 0a, 20b and the divider 23 and the first or second current controller 19, 19a.
The differential amplifier 25 detects the difference between the ratio of a and 20b and a preset setting value 24, and feeds the detected difference to the first or second current controller 19 or 19a with feedback feedback. By doing this, A near the sample surface
Synchrotron radiation spectrum 20a which is a typical line spectrum of a species
And synchrotron radiation spectrum, which is a typical line spectrum of B type 20
b is received by the optical sensors with filters 21 and 22,
After adjusting the sensitivity, it is taken into the divider 23, and both spectra 2
A ratio of 0a, 20b is taken. If this is assumed to be the emissivity, this emissivity is further measured and set to a preset value 24
It is transmitted to the differential amplifier 25 which detects the difference between and. Then, both spectra 20a, 2 detected by the differential amplifier 25
The difference between the ratio of 0b and the set value 24 is applied to the second or first current controller 19a, 19 of the second or first power supply 18a, 18 for supplying a current to the magnetic field coil 4 or the microwave oscillator 17, respectively. Feed back. As a result, the discharge state of the plasma 7 or the reactive gas 13 during processing is controlled to be constant.

That is, the resonance ionization surface where ionization strongly progresses due to electron cyclotron resonance is dominated by the intensity and distribution of the microwave intensity or magnetic flux density, so the change in the synchrotron radiation spectrum ratio appears as a change in the shape and intensity of the ionization surface. , The synchrotron radiation spectrum ratio is controlled so as to maintain the set value. As a result, from the fact that the film composition is the same if the synchrotron radiation spectrum ratio is constant (Takuo Sugano ed., Sangyo Tosho, Semiconductor Plasma Process Technology, P165-P178), both film quality and film thickness are monitored without the operator's supervision. Initial setting 24
If the optimum conditions can be set for the apparatus main body, the film quality and film thickness will be uniform and reproducible film formation will be possible.

As described above, according to this embodiment, the uniformity and reproducibility of the film quality, film thickness and surface treatment accuracy of the formed thin film can be greatly improved without constantly monitoring the discharge state. Further, the uniformity of the spatial distribution of various plasma quantities can be improved.

FIG. 2 shows another embodiment of the present invention. In this embodiment, two radiant light spectra 20a, 20 in the vertical direction are used.
b, that is, the synchrotron radiation spectrum 20 above the sample table 14
All of a and 20b are taken into the optical sensors with filters 21 and 22. In this case, the sample table 14
As the upper radiant light spectrums 20a and 20b are all taken into the filter-attached optical sensors 21 and 22,
The detection accuracy can be improved as compared with the case described above.

Although the optical sensors with filters 21 and 22 are used as the optical sensors in these embodiments, optical sensors with a spectroscope may be used.

〔The invention's effect〕

As described above, in the present invention, the sample chamber is provided with the control means for controlling the discharge state of the plasma or the reactive gas being processed by a plurality of radiant light spectra of the plasma or the reactive gas being processed, and the control means is provided for the sample. An optical sensor with a filter for measuring a plurality of emission spectra of at least one kind of plasma or a reaction gas in the room, and a plurality of the optical sensors provided between the optical sensor with the filter and the first or second current controller The difference between the value of the synchrotron radiation spectrum and the preset value, or the difference between the ratio of the plural radiant spectrums of a plurality of types and the preset value is detected, and the detected difference is used as the first or second current. Since it is formed with a differential amplifier that feeds back to the controller, even if the discharge state changes due to external factors, the microwave intensity or magnetic flux density distribution is corrected,
The original spatial distribution of low-temperature plasma quantities can be
It becomes possible to keep the film formation conditions within the processing time constant, and the film thickness, film quality and surface treatment are uniform without monitoring the discharge state within the processing time, and reproducible film formation and surface treatment. It is of course possible to obtain a low-temperature plasma processing apparatus capable of ensuring the uniformity of the spatial distribution of various plasma amounts.

[Brief description of drawings]

FIG. 1 is a diagram showing an apparatus configuration of an embodiment of a low temperature plasma processing apparatus of the present invention, FIG. 2 is a diagram showing an apparatus configuration of another embodiment of a low temperature plasma processing apparatus of the present invention, and FIG. FIG. 4 is a diagram showing an apparatus configuration of a conventional low temperature plasma processing apparatus, and FIG. 4 is a diagram showing an apparatus configuration of another example of the conventional low temperature plasma processing apparatus. 1 ... Plasma generation chamber, 2 ... Microwave, 3 ... Waveguide, 4 ... Magnetic field coil, 7 ... Low temperature plasma, 11a ...
... sample chamber, 12 ... reaction gas supply pipe, 13 ... reaction gas, 14 ... sample stage, 15 ... sample, 17 ... microwave oscillator, 18 ... first power supply, 18a ... second Power source, 19 ... First current controller, 19a ... Second current controller, 20a, 20b ... Radiant light spectrum, 21,
22 ... Optical sensor with filter, 23 ... Divider, 24
…… Set value, 25 …… Differential amplifier.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location H01L 21/31 C (72) Inventor Tadashi Sonobe 3-1-1 Sachimachi, Hitachi City, Ibaraki Stock Hitachi, Ltd., Hitachi Works (56) References JP 62-89869 (JP, A) JP 62-93382 (JP, A)

Claims (1)

[Claims] 1. A plasma generation chamber for generating a low-temperature plasma, and a sample chamber connected to the plasma generation chamber for introducing the plasma, the plasma generation chamber being provided with a first power source on top of the plasma generation chamber. 1, a microwave oscillator connected via a current controller, a waveguide for introducing microwaves from the microwave oscillator, and a second power source connected to a second power source on the outer periphery thereof via a second current controller, Further, the sample chamber has a magnetic field coil for generating a magnetic field for generating an electron cyclotron resonance discharge by the microwave, and the sample chamber has a sample stand on which a sample is placed, and a reaction gas supply pipe for supplying a reaction gas to a side wall thereof. In the low temperature plasma processing apparatus for treating the surface of the sample by activating or ionizing the reaction gas introduced into the sample chamber with the plasma, The control means is provided for controlling the discharge state of the plasma or the reaction gas under the processing by a plurality of emission spectra of the plasma or the reaction gas under the processing, and the control means is provided for at least the plasma or the reaction gas in the sample chamber. An optical sensor with a filter for measuring a plurality of radiant light spectra, and a plurality of measured radiant light spectrum values provided between the optical sensor with a filter and the first or second current controller. A difference for detecting a difference from a preset setting value or a difference between a ratio of a plurality of types of synchrotron radiation spectra and a setting value and feeding back the detected difference to the first or second current controller. A low-temperature plasma processing apparatus formed by a dynamic amplifier.