JPS5931550A - Radical and excited particle measuring equipment during plasma etching - Google Patents

Abstract

PURPOSE:To make the mass spectrometry of a radical and excited particle possible during plasma discharge by providing a light source unit that ionizes by meant of vacuum ultraviolet rays with low energy only radical and excited particle types, that is, the neutral activated partcle types that flow in from a plasma etching room. CONSTITUTION:A magnet 6 is provided at the measurement room 2 side of an orifice 5 for differential exhaust and generates a magnetic field so that a charged particle passing through the orifice 5 from a plasam etching room 1 in which plasma discharge occurs, cannot enter a mass spectrometer 3. The strength of the magnetic field is set to be approximately 150-600gauss. A discharge tube 7 generates vacuum ultraviolet beams (8.4-11.8eV) with low energy that ionize only radical and excited particle types, that is, neutral activated particle types which are made to flow in from the plasma etching room 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a device for measuring radicals and excited molecules during plasma etching.

For example, in the manufacturing of recent semiconductor assembly fi1 circuits, rl
,(,As the technology advances, the concentration increases to 111,
Not only can they be made smaller, but significant improvements can be expected in terms of reliability and performance. Especially i
i＋゛・(Expectations for Fine Processing Techniques 1. It is big and a lot of effort is being made.There are 1 and n types of microfabrication technology, but RF plasma etching is currently attracting particular attention. There are dry etching technologies including

What are the active molecules (radicals, excited molecules) that are formed in plasma etching due to gas discharge? ) Processing it? , which actively uses a chemical reaction with . 'i'r i' of this method! This is because there is selectivity depending on the processing material compared to physical processing methods such as sputter etching (ion milling) using ions. However, if the selectivity is t), even η is limited to a limited number of materials, and not all materials can be processed sufficiently selectively. It is essential to know enough about this.

Conventionally, as methods for determining changes in the plasma state, the luminescence spectroscopy method, infrared absorption method, probe method, shellfish analysis method, etc. have been used to measure gas in plasma.

The analytical method is a method of directly observing ions in plasma, not radicals, and emission spectroscopy is a method of observing ions in the plasma directly, not t, and optical emission spectroscopy is a method of observing ions in the plasma directly, not t. Because this method observes light emission during the transition process to a lower level state, it is not possible to observe molecules whose energy is deactivated without emitting light.

For example, if we consider the case where CF4 gas is used, CF generated in the discharge plasma, CF2. Of the CF3 radicals, only CF and C can be effectively observed by emission spectroscopy.
F2 radical and CF3 radical are effectively t? ! It cannot be measured. Furthermore, infrared absorption method ink is currently not an effective method for measuring radicals in plasma.

By the way, knowing the state in the plasma, especially the ion 'N and radical species, has a great practical advantage in that it can be used to empirically (determine the problems considered in) 4, and to improve the etching speed. This can be reflected in the etching shape, and also problems such as removal of heat sources, search for new etching gases, and improvement of selection +1. !'+'f Gas ゛- and plasma etching reaction j, r, (:・i'i'l fishing・
I'm looking forward to Tomei playing a big role (・matazui)σ) and JllJ. Dimensions Plasma Era song
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It hasn't been done. this'! In order to elucidate r-C (+, l (゛ r5 dinonor measurement is considered essential) Z).

I11'- is this σ) Invention σ) Purpose (・2 [, Plasma family,) 1. Radicals in 1. -Yohi excited molecules 'I! T
2. To provide 4 IJ service 1' in 7υr.
.

For this purpose, according to the invention (J, Plasma Etching 2)
,4 to 'FN' The device F.1 which acts to remove electrons/generates 1 degree) and the plasma etching? A light source device that ionizes with low vacuum ultraviolet rays is installed, and the ionized neutral active molecular species are measured using the above-mentioned analyzer. A device for measuring radicals and molecules generated during plasma etching is provided.

Matatonotsu C: According to Akira, a device that generates a magnetic field]゛j
It is possible to remove the magnet and make it a functional magnet (1).
Skylight outside? By turning off the device, the light υII of ``i!'' is also generated in the plasma.

The present invention will be further described below with reference to the accompanying drawings.

Figure 1 shows an implementation of the device of this invention! 11 is schematically shown, 1 a plasma etching chamber, 2 plasma etching chambers, 1 a measuring chamber accommodating a total of 3, and 4 extending between the plasma etching chamber 1 and the measuring chamber 2; In this passage, an orifice 5 for evacuation with a difference of 1ijl is arranged (t'1'' as shown in the figure d).This orifice 5 i
For example, it has a diameter of approximately 177+++Ig. In addition, a magnet 6 is installed in the measurement chamber 2 (1! In order to prevent
(The strength of this magnetic field is -17'J due to the distance p::+ between the magnet 6 and the quality analyzer 3, but the field is fixed to t'J150-6n0 Gauss.) Nere?l
iru. That is, 1'), a charged electron causes a magnetic field: 11. (Zl, i-when its 119; i'j 11 bent,
Track 51' at that time! The radius (r) is expressed by the 11th order equation.

r=143. q71-product-v/r (C-=nJ where,
M is fsnj'), Vrjload', particle energy (θV'), 11 is magnetism, (I7 gauss, 11 gauss). If the radius of the orbit is as small as 1, that is, the strength of the magnetic W is small,
N'i'1 child iJ quality % '=,) enters analysis meter 3, but
2. Fly close to the ionization chamber of quality B + analysis rule 6 and ionize the neutral particles. Especially out of place. To compensate for this, the strength of the horse must be at least 150 Gauss.

In a small tank 7101, a method of ionizing only the radical species, which are neutral active molecules flowing in from 1 during plasma etching, is carried out in 7 vj directions (ζ 11 engineering). Low inn, y, , 1j-1
Generates p external light +f'1l (8.4 to 11.8 eV).

#4'! , 2 ERI uses CF and SF6 gases as radical measurement conditions in a reactive ion etching device 52C, with a power output of 0.25 W and a polarization of 2 (500
w)・Pressure is 20.05 to 0.07 Torr, power frequency: 13.565MHz, and S is applied to the electrode surface material.
i02, Lyman α rays are used as the light source, and the window material is M.
7F2, and the orifice diameter is ~1mmt7J,
The ions were removed by applying a magnetic field of 550 Gauss, ionized by Lyman alpha radiation emitted from a hydrogen discharge tube, and the reactive ion eratin was measured using a mass spectrometer. indicates the vector, and the graph 'k
) The graph (b) shows the active neutral molecular species generated under the plasma conditions of ricF'4, and the graph (c) shows the case of SF6, and the graph (c) shows the number of hydrogen + H;
This figure shows the results of measurements taken to confirm that ions do not enter the mass spectrometer, and it can be seen that ions are removed by a magnetic field of 556 Gauss.

As a carbon source for ionizing radicals, the resonance lines shown in the table below can be used.

The line has a single wavelength with a narrow energy width, and I
It can be obtained at a pressure around Torr.

Since the generated Z and radical fiTj are dispersed by the species of gas υ11 used in plasma etching f(η,
It is necessary to select the discharge tube to be used as appropriate. In addition, by adjusting the ionization light source, the approximate value of the ionization energy of the radical or the value of the neutral molecular species PinoH
Self-energy can be determined by 411:. 51JV.

The graph (a) Ic in the f42 diagram shows CO (14, 01eV),
C02 (15,7F3ev) has been observed. Therefore, when we calculated the difference in energy between these neutral molecular species and the energy of the ionizing light source, we found that each CO: 3.81
eV.

CO2: 3.50 eV, Co, co2
Is it F that exists in a very high In,F state?
I can get 1. This suggests that in reactive ion etching, both radicals and neutral molecules exist in a highly excited state. This is a fact that has never been observed using conventional measurement methods.

By widely utilizing this method, plasma-like t”
It is expected that more knowledge about FcQ will be obtained regarding No. 11.

Note that there is a method to prevent ions from flowing into the measurement chamber 2 from the plasma etching chamber 1, but it has been experimentally shown that this method is not very suitable for reactive ion etching under high pressure. Found out. In other words, electrons in the plasma fly towards the positively applied ion liberator, and the ion liberate passes through the ion liberator, releasing a large amount of unreacted introduced gas and a small amount of active molecular species in the measurement chamber. This is because it is ionized.The reaction t1-ionbino, which is ionized in a region of low pressure, is the case of etching.
It is possible to use an ion lira method to measure radicals, but since the mean free path is short at high L1 mica: i47. Can not do it.

As explained above, a.]1 For example, the cathode coupling and the lasma etching device f'j°t7.
In I, ions and [(1, energy of child kl 101
Since it is less than 10 eV, it is possible to use a magnet of less than 600 Gauss. Therefore, in the apparatus according to the present invention, a magnet is used to control the ions flowing from the plasma etching chamber through the orifice for differential evacuation. ti↓b(41, b) so that the neutral active molecules qiji flowing in from the plasma etching chamber can be ionized by ultraviolet light P1','i- with low energy and light. Due to this, high sensitivity (
Radicals can be measured at 10A), plasma conditions can be immediately determined, and as a result, nine etching conditions can be determined.

In addition, in this invention, if a sliding magnet is removably provided to simultaneously remove ions and electrons entering the orifice, it is possible to analyze the nature of neutral active molecular species and to remove the ions and electrons generated in the plasma. This has the practical effect of making it possible to perform ion mass and mass analysis with the same analytical performance.

[BRIEF DESCRIPTION OF THE DRAWINGS] Figure 1 is a schematic diagram showing an embodiment of the apparatus according to the present invention, and Figure 2 is a schematic diagram showing an example of a reactive ion etching process using the apparatus according to the present invention. radical'
(This is a graph showing the 'j '4''i spectrum. In the figure, 1: plasma etching chamber, 2: measurement chamber,
3:! Quantity analyzer, 4: Passage, 5 Niorifice,
6: Magnet, 7: Emission mW.

Claims (1)

[Claims] In the passage leading from the plasma etching chamber to the measurement chamber where the mass spectrometer is installed, there is an orifice for differential pumping and a magnetic field near the orifice that acts to remove ions and electrons flowing from the orifice into the measurement chamber. C81, which generates a An apparatus for measuring radicals and excited molecules during plasma etching, characterized in that molecular species are measured using the above mass spectrometer? stomach.