JPS61129555A - Monitor with space resolution - Google Patents

Abstract

PURPOSE:To attain precisely spectral analysis to irradiation in the discharge space of a plasma device by providing a mask which cuts off optical-axis light on the prolongation of an optical axis penetrating the discharge space of the plasma device on measurement points, and providing a movable condenser lens system behind it. CONSTITUTION:The plasma device is provided with a vacuum chamber, a counter electrode, and a vapor-deposited substrate and discharges dope gas, etc., by electric discharge. Measurement points X1-X5 are set on the prolongation of the optical axis of a plasma chamber and the condenser lens system B is provided on the optical axis. The condenser lens system B is provided with the mask 23, condenser lenses 3, and 4, a movable lens barrel 18, and a photodetection surface 21. Further, light from the measurement point X1 passes through the periphery of the mask 23 and forms an image on the photodetection surface 21. Further, light from the measurement point X2 forms an image by moving and adjusting the lens barrel 18. Thus, light beams from the measurement points X3-X5 form images by moving and adjusting the lens barrel 18 to adjust the arrival on the photodetection surface 21. Thus, the mask is provided on the optical axis, so light emission at various points in the discharge space is analyzed and plasma is controlled efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a monitor that performs spectroscopic measurements of a reaction device for forming an elastomy film or other reaction device that emits light from plasma or the like.

[Prior art]

Etching and film forming methods that utilize discharge phenomena, such as plasma chemical vapor deposition (CVD), are widely used and are currently being actively researched. Although the properties of the discharge space greatly affect the film thickness distribution, composition, composition distribution, film formation rate, and other characteristics during film formation, a method for precisely observing or monitoring the discharge space has not yet been proposed. do not have. Conventional monitors have only been used to attach light-transmitting windows to plasma CVD equipment, etc., and to separate the light emitted from the windows, making it difficult to see the average behavior of the discharge space. Not too much.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a monitor capable of performing precise spectroscopic measurements of discharge spaces in t2I expansion, etching, and other reaction apparatuses such as plasma CVD.

[Summary of the invention]

The monitor of the present invention is a condensing lens system that is aligned on an extension of an optical axis passing through a point to be measured in a discharge space of a device that utilizes a discharge phenomenon, and whose focal position is variable. It consists of a condensing lens system equipped with a mask that blocks incident light, a means for separating light from the condensing lens system, a means for converting the separated light into an electrical signal, and, if necessary, a display means.

1. Since the monitor of the present invention has a spatial resolution that allows information on a desired point in the discharge space, rather than an average image of the discharge space, it allows for precise and easy research and process control of this type of reaction. can be done.

It is necessary to completely block the narrow optical beam incident along the optical axis on the objective side of the condensing lens system. This makes it possible to spectroscopically measure information or data only about the discharge at the point that is currently in focus with respect to the optical axis.

〔Example〕

FIG. 1 shows an overall view of a discharge space monitor A according to a first embodiment of the present invention, and FIG. 2 shows details of the condenser lens system B of FIG. 1. FIG. 2 is a diagram showing another example of application of the device of the present invention.

The example shown in FIG. 1 shows a monitor for spectroscopically measuring the plasma space (discharge space) in a plasma CVD film forming apparatus T. The film forming apparatus includes a vacuum chamber 11 and an opposing pole 12. 15. A vapor deposition substrate 14 is provided on the surface of the electrode 15, and a plasma 15 of source gas, dope gas, etc. is generated in the chamber by RF discharge or the like. For example, to form a silicon film, SiH4 gas, H gas, BAH@ for doping, or the like is introduced into the chamber and discharged. The state of the discharge space is, for example, SiH emission spectrum line 416 nm % H emission spectrum line 6
It can be determined by measuring the intensity and spatial distribution of 56 nm, etc., or the spectra of each point.

A light-transmitting window 16 is formed in the plasma chamber 11, and the emitted light is incident on the monitor of the present invention. The monitor has a mirror 1.2 close to the window 16, which splits the light into two parts and directs it to the condenser lens system B. bar 7
Mi2- may be a single mirror depending on the measurement purpose. The optical axis of the condenser lens system B will effectively be substantially aligned with the optical axis passing through the measurement point in the plasma space. The condensing lens system B mainly includes a mask (see FIG. 2, described later) that blocks the optical axis light on the incident side, and a pair of lenses 3.4. The light is then guided by an optical fiber 5 to a mo/meter 6 and an optical filter 7, where it is separated into spectra, and a photo! The plasma reaction is amplified by the multiplier 8, converted into an electrical signal by the photodetector 9, and recorded on the recorder 1G. Figure 2 is a detailed diagram of the condensing lens system B.
Consists of a lens barrel 17 and a movable lens barrel 1B fitted therein,
The movable lens barrel 1B is guided through the slot of the lens barrel 17 by its pin 19 and knob 20. A pair of lenses 3.4 are held inside the movable lens barrel 17, a mask 23 is arranged on the optical axis on the input side, and a light receiving end 21 of the optical fiber bundle 5 is arranged on the optical axis on the output side. There is.

Assume that during use, the movable lens barrel 18 is adjusted to form an image of a point Xl in the plasma space on the light receiving end 21. At this time, if there is no mask 23, the points X2 and X on the same optical axis
All the light from other measurement points such as 3, X4, and Xs also enters the light receiving end 21. Because of the mask 23, all light on the optical axis is blocked. On the other hand, light off the optical axis that comes out from point Xl is imaged at the light receiving end, but points Xs-, Xs S
The light emitted from Xa and Xs does not reach the light receiving end 21. The same applies to light emitted from other optical axes. Also, light emitted from other points is received! There is something that reaches 21, but image formation 1,
A school of fish is sent to the fish 1, and the light that shines on the demon Sue at the bell and the ψ^11-cho 6 will mainly give information on the point x1.

The light from point X1 is then passed through monochromator 6 and/or
The light is separated by an optical filter 7, and then converted into an electrical signal by a photodetector 9, which is then used for a recorder and automatic control of film forming conditions.

Note that any spectroscopic means may be used instead of 6.7.

To measure other points X2..., prepare a movable mirror.

FIG. 3 shows an example applied to a plasma CVD film forming equipment using a cylindrical electrode, in which a plasma space 15 is formed in an annular shape between a cylindrical electrode 25 and a center electrode 26, and a window 16 is formed. From point X 11X 2 in plasma space,
X 3 points can be arbitrarily measured 0 Note that the monitor person may be supported in a movable manner so that various points along different optical axes in the plasma space can be measured. Furthermore, the 8-7 mirror used in the above example may be omitted and the condenser lens system may be directly aligned with the window 16.

Next, referring to FIGS. 4 and 5, FIG. 4 of the present invention is a diagram similar to FIG. This shows that the image is formed on the light receiving surface 21 of the detector.

Generally, the energy radiated in one direction (for example, the X-axis direction) from a unit area of the plasma surface per unit solid angle per unit time can be expressed by equation (1).

A. Probability of transition from m level to n level n of a light-emitting molecule or atom v Frequency of light when transitioning from sm level to n level n N Density of molecule or atom at In level xl , x
2. The distribution of luminescent particles that are focused when the lens is focused at each position of xl is expressed as f'', f'', and
Let it be f.

(1) In equation (1), transition probability A for the small space is 1 and -n. If we focus only on the constant wavelength, Arnnhν, = α (constant) (
2) can be assumed to be a constant. Therefore, the emission intensities corresponding to Xi % T-2 and xl are each 1. ,I, ,13.

Here, 0 mouth Δ11=α(zfLnΔVn-, if2njVn)
Consider (4).

Next, considering (4)-(5), it approximately corresponds to the energy of light at point x2.

By applying equation (6), which is actually a calculation of the intensity of light incident on the light receiving surface of the detector (7) Δl2=I + 13 212 (7), the density distribution of luminescent particles at position W x 2 can be obtained. is required.

[Effect]

As described above, according to the present invention, it has become possible to perform luminescence analysis of various points on a predetermined optical axis in a discharge space, for example, a space on a substrate surface in a film forming apparatus.

This clarified the correlation between information on plasma potential and light emission, which is closely related to the properties of plasma.
The parameters of plasma generation conditions can be grasped, or the parameters can be automatically controlled.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the spectroscopic measurement monitor of the present invention, FIG. 2 is an enlarged detailed view of the condensing lens system of FIG. 1, FIG. 5 is a diagram showing another application example of the present invention, and FIG. The main parts in Figure 0, which is a diagram explaining the principle of the present invention, are as follows. A: Monitor B: Condensing lens system 1.2: Half mirror 3, 4: Condensing lens 5: Optical fiber 6: Monochromator 7: Optical filter 8: Fold multiplier 9; 7-tooth detector 10 recorder iy: @Simplified 18: Movable mirror 21: Light receiving surface 25: Mask XI, X2, X3, X4, X@: Measurement point 1
Figure 3 L J

Claims (1)

[Scope of Claims] 1. In a monitor that spectroscopically measures a discharge space of a film forming, etching, or other reaction device that involves discharge of plasma, etc., a monitor that is aligned on an extension of an optical axis passing through a measurement point of the discharge space and that corresponds to A condensing lens system that is movable in the direction of the extension line and has a mask that blocks optical axis light on the incident side and has a light receiving end on the output side, and a means for separating the light from the light receiving end. and means for converting light from the spectroscopic means into electrical signals, the monitor having spatial resolution. 2. The monitor according to item 1 above, wherein the condenser lens system is movable so as to be aligned on extensions of different optical axes. 3. The condensing lens system consists of a fixed mirror and a movable mirror that slides on the fixed mirror. The movable mirror has a mask, a condensing lens, and a light receiving end, and a constant discharge is generated from the condensing lens. 3. The monitor according to claim 1 or 2, wherein a point in space is imaged onto the light receiving point.