JPS5856336A - Composite dry etching device - Google Patents

Abstract

PURPOSE:To combine etching, the heat treatment, etc., and to perform processing by etching desirable for compound semiconductor holding the surface of a sample in purity as it is by a method wherein a dry etching device is constituted of four chambers of a preparation chamber, an etching chamber, a heat treatment chamber and a surface analizing chamber. CONSTITUTION:The etching device is consisting of the preparation chamber 1, the etching chamber 2, the heat treatment chamber 3 and the surface analizing chamber 4, and the respective chambers are intercepted by gate valves 8, 9, 10 inserted in the coupling parts 5, 6, 7 to constitute respectively independent vacuum devices. At the etching chamber 2, etching gas excited into plasma condition is injected through a waveguide 13, and applies impacts of ions on the surface of the sample 17 to perform etching. At this time, neutral and radical particles reach the surface of the sample due to the thermal motion to perform etching by chemical reaction. Moreover the device thereof is provided with a mass analizing means 18 for particles.

Description

[Detailed description of the invention] The present invention relates to a dry etching apparatus.

Dry etching technology accounts for 81% of semiconductors today.
Etching technology occupies an extremely reasonable position as one of the core manufacturing technologies for LSI (Large-Scale Integrated Circuits) at Kyushu Electronics. There are essential techniques for processing thin films and substrate materials such as electrodes and glossy Q semiconductors into unique patterns. In recent years, the degree of integration of ICs has improved dramatically, and the minimum dimension of the unique pattern has become microscopic, less than 1ξ Kuhn (μ-). Etching has a limited pattern size and uniformity within a crystal wafer, so the process in which it can be used is limited, and recently dry etching has been exclusively used.

For dry etching, chemically active particles (9 radicals, ions, etc.) in active gas (e.g. halogen gas, etc.) plasma are used.
9-button etching, which utilizes a chemical reaction between the substrate material and the substrate material, and ion beam etching, which ionizes an inert gas (such as argon) in a high electric field and accelerates it in the electric field to impact and scrape the substrate material. (or ion J-ring). The former method has the advantage that the etching rate is very high depending on the combination of the gas used and the substrate material, so that the IC manufacturing time can be shortened. On the other hand, like wet etching, etching is isotropic, so selective etching using a resist mask pattern is not possible.
However, etching is performed directly under the mask, making it difficult to etch fine dimensions. On the other hand, the latter has the advantage that the etching progresses quickly in the direction of acceleration of the ions, so that the etching is strongly directional, and that it is therefore possible to perform so-called sharp-cut etching with a steep cross section. On the other hand, since the latter etching is performed only by ion bombardment, the etching rate is generally about six orders of magnitude lower than the former, and furthermore, the damage to the substrate is much greater.

Kinto has developed reactive ion etching (reactive ion etching) that utilizes the advantages of both plasma etching and ion beam etching mentioned above.
or reactive sputter etching.

(also called reactive dry etching) has been attracting attention.

A wide variety of apparatus structures for such reactive ion etching are known, but basically, in a vacuum apparatus, seven nodes and a counter electrode, for example, one side of a parallel plate solder electrode, which constitutes a cathode, are connected to one side of the cathode. The substrate for etching is placed on the substrate, and an active gas such as carbon hepide (CFa, CC
A plasma discharge is generated by introducing a gas such as sulfur (Ik, etc.) or /SP gunned sulfur (SF-, etc.) and applying a high voltage, for example, an RF voltage of IKVIi degree (often frequency, 56 MHz) between both electrodes. At this time, an ion sheath is generated near the cathode electrode on the substrate side, and the cathode has a negative DC potential, so the ions in the plasma are accelerated and impact the substrate. Therefore, in such a structure, as described above, etching progresses on the substrate surface while the two etching phenomena, chemical etching due to Goodsmer reaction and physical etching due to ion bombardment, are intertwined at appropriate contribution rates.

For this reason, reactive ion etching allows a pattern with a steep cross section to be obtained at a high etching rate, and the etching is highly dependent on the material.

It has the advantage of superior machining accuracy and high economic efficiency. Also, damage to the board due to ion bombardment, *
This is far less than the ion beam etching fK mentioned above.

By the way, apart from the LSI using the
Research and development of ICs using am-v group compound semiconductors is now attracting attention. One of the aims of such an IC is to realize a high-speed logic IC by taking advantage of the fact that the mobility of these compound semiconductors is greater than that of Si. Another aim is that the compound semiconductor can be used as a laser,
Since it is possible to realize optical elements such as photodiodes, ICs monolithically incorporate these optical elements and the high-speed electronic elements.

That is, opto-elect sy 2yri (0pto-E1@t
romie IC (hereinafter referred to as -1:0EIC). The latter is currently being used in the field of optical communications, which is rapidly being put into practical use. It appears in the connection section of the mesh, and is considered to be an IC with functions such as large capacity, high-speed optical line switch, repeater, or signal processing.

When manufacturing the above chemical formula 1411 semiconductor IC&', 5t-x
Similar to c., dry etching technology is an essential and important technology. However, when looking at the target material to which the dry etching technology is applied or the required processing performance, especially when increasing the 0EIC to 1, the 5i
-The situation is quite different from the case of IC. That is, 5i-I
In the case of C, the material to be etched is, for example, the M electrode for disposing the gate electrode (for example, polysilicon: I/) in the MO8 structure, or the insulation II (for example, silicon oxide film, SL film, etc.) for forming puncture holes therein. etc. In addition, the conditions for processing KIN are that the pattern is highly dense, so the processing dimensions can be as small as 4 micrometers, and the processing cross-sectional shape is steep, and the material selection process for etching is economical. was large, etc.

In contrast, for example in the case of a GaAs-0EIC, the region to be etched is one
It is often GaAj itself including an optically active layer, such as the output end face obtained by I-opening, or processing of an active layer for current confinement or an optical waveguide structure. Therefore, processing K
i! The conditions imposed are to suppress surface damage and surface contamination due to etching as much as possible, and if possible, to achieve a mirror-like smooth finish. Furthermore, the machined cross-sectional profile is sometimes controlled to be sharp, sometimes almost sinusoidal.

As mentioned above, the processing performance required for dry etching for conductor in compound 0EIC is truly severe. As a way to satisfy these demands,
First, surface damage - contamination - @! before and after dry etching or during processing. Second, it is possible to accurately control the contribution ratio of both the chemical and chemical etching mechanisms mentioned above, and third, it is possible to detect surface damage. In the event of such damage, measures should be taken to quickly reverse the damage. On the other hand, even if we focus on conventional dry etching equipment, especially the aforementioned reactive ion etching equipment which is said to have excellent processing performance in many respects, it must be said that it is still far from satisfying the above requirements. That is, in conventional devices, the contribution rate of the chemical/physical etching phenomenon is generally determined by the applied voltage and ion current.

This is determined by the type of gas introduced, the gas pressure, etc., but these vacuum meters depend on the structure of the device.

Therefore, the range in which the chemical etching and physical etching can be controlled independently by changing the bacmeter is as follows:
Although it varies depending on the device, it is generally limited to a certain range. Furthermore, under conditions where the contribution rate of the chemical etching mechanism is large, if the vapor pressure of the product produced by the reaction between the substrate material and the chemically active gas is low, the substrate surface will be contaminated, causing uneven etching as a source of contamination. In the currently known reactive ion etching equipment, these groups a
It does not have a means to quantitatively or qualitatively analyze m-plane residue. Furthermore, under etching conditions in which the contribution rate of the physical etching mechanism is large, damage to the substrate surface occurs due to ion bombardment (as described above), but current reactive ion etching equipment cannot quantitatively or qualitatively reduce such surface damage. There is no means for analyzing or repairing surface damage.This situation is not limited to reactive ion etching equipment, but also to the previously known plasma etching equipment and ion beam etching equipment mentioned above. The same was true for etching equipment.

As mentioned above, conventional dry etching equipment has many drawbacks as an etching equipment for manufacturing AOE I Ctl using compound medium conductor ICs, especially tv* compound conductors such as GaAs. Ta.

An object of the present invention is to provide a dry etching apparatus of a new structure which eliminates these drawbacks. According to the present invention, in an etching apparatus provided with a means for causing a physical or chemical interaction between a gas phase as an etching gas and the same phase as a substrate to be etched in a vacuum apparatus, the scissors etching apparatus is used. Preparation room/Etching room/
Heat treatment chamber and II! Consisting of four houses of internal analysis and wealth, the etching chamber is responsible for at least % of the physical relationship of the gas phase and solidity.
L (is a means of forcing chemical interaction, and mosquito interaction K
comprising means for mass spectrometry of primary or secondary particles giving m;
The heat #1 & barrier includes means for heating at least the substrate;
The surface analysis chamber is equipped with a means for compensating for fluctuations in the stoichiometric ratio of the substrate's constituent elements that occur when the substrate is heated, and a means for evaluating the crystalline portion of the substrate's surface layer. It is equipped with means to enable the identification of surface-adsorbed elements and the analysis of chemical bonding states, and the preparation chamber, etching chamber, heat treatment chamber, and surface analysis chamber are separated by gate pulp inserted into each joint. A composite dry etching apparatus is obtained in which the substrate is evacuated and the substrate can be transferred between the four chambers by a load rotor mechanism.

Next, the present invention will be explained in detail using the drawings.

FIG. 1 is a schematic diagram of the configuration of an embodiment of the present invention.

In the figure, the preparation chamber 1, the etching chamber 3 and the surface analysis chamber 4 are formed by gate pulps 8, 9 and 1O inserted into the joints 5, 6 and 7. In the figure, the ion shower etching section is located in the plasma chamber 11.
, a microwave waveguide 13 , an etching gas introduction tube 14 for /1ρ gene compound, and an ion extraction grid 12
It consists of

The etching gas is sent into the plasma chamber 11 through the gas introduction pipe 14 from the gas-to-controller 15, which is capable of switching between multiple types of etching gases and controlling the flow rate. It is excited into a plasma-like state 11 by microwaves. The area around the Gutsuzu V chamber is covered with a magnet for plasma convergence. )~-gen gas or metal halide gas in an ion or neutral radical state is present in the plasma chamber 11. Of these, particles in an ionic state are separated from the grid 12.
It is accelerated by the nine electric fields applied to it and flies out of the plasma chamber.

Ion bombardment is applied to the surface of the sample 17 fixed on the substrate support 16 to perform etching. At this time, the neutral radical particles existing in the goods matrix are accelerated by the grid, but they fly out due to thermal motion, and the particles that arrive at the sample surface undergo a chemical reaction that causes etching of the sample surface. A part of the ions (primary particles) that are accelerated by the electric field and arrive at the sample surface are transferred to the support table 16.
Pass through the permeation hole provided in the
i A mass spectrometer 18 is used to perform elemental analysis. Similarly, among the particles (secondary particles) that the primary particles hit the sample surface and flew out from the substrate at 9 o'clock, the particles that flew in the direction of the arrow n are transferred to the quadruple 111m mass spectrometer 19. Elemental analysis is performed. These mass spectrometer needles are capable of identifying the elements of primary particles and secondary particles as well as quantitative analysis to some extent, so that a predetermined etching gas flow rate to the plasma chamber,
Information on the relationship between primary particles and secondary particles incident on the sample with respect to ion extraction voltage, wholesale sputtering rate, etc. can be obtained.

In addition, the ode is #stoma. Also, as a matter of course, the sample introduced into the preparation chamber (Fig. 1) K from the atmosphere is sent to the corresponding etching chamber 2 by opening the gate pulp 8, and at the same time as the etching is completed, the gate pulp 9 is opened and transferred to the adjacent chamber 3. be done. All of these sample transfers, including those described below, are performed by a load rotor mechanism.

FIG. 3 is a diagram illustrating a specific structure of the heat treatment chamber 3 shown in FIG. 1. In the figure, a sample 32 fixed on a sample support stand 31 with a built-in heater for heat treatment is analyzed for surface crystallinity 11 by high-speed reflection electron diffraction (at R-D) 33 before being subjected to heat treatment. and evaluate the degree of surface damage caused by dry etching.

The diagonal is a screen that projects the diffraction pattern of the RHEED. If the surface damage is large, the heater in the sample support stand 31 is energized to treat the sample at a high temperature to recover from the damage. An example of heat treatment conditions is 700°C for 15 minutes. At this time, if the sample 32 is made of GaAs, gas is emitted and the back layer of the sample often moves in a stoichiometric ratio. For this reason, it is necessary to provide an h evaporation source 35 and use it to perform thermal earthquake while evaporating A- to control the M partial pressure in the room. A light beam entrance window for evaluating the luminescence and an argon ion gun 37 for surface cleaning are a must for the photo! Provided accordingly. The main processing chamber is also evacuated through an independent exhaust hole, similar to the pre-etching chamber. The degree of vacuum in the etching chamber is 10 to 10 Tsrr when the maximum is reached, and 1O4 during etching.
~16'τ・ry and 9, but the heat section Rumuro is 1a4~1
0 ↑orrK is reached. For this reason, since the above-mentioned mu-evaporation is performed in a clean atmosphere, it is close to molecular beam deposition, and therefore h compensation during the heat treatment is performed extremely effectively.

may be immediately before or immediately after the heat treatment.

In either case, sample 42 was subjected to surface analysis in our laboratory.5o4
3 is an Auger electron spectroscopy needle (MUEB), 4B and 46 are an xIs source for X-ray excitation photoelectron spectroscopy (XPS) and an ultraviolet source analyzer for ultraviolet excitation photoelectron spectroscopy (UPS), respectively. In the tooth surface analysis room, elemental analysis (including distribution in the R direction) of the sample surface layer is mainly obtained using MuES, and XP8, U
PS reveals the chemical bonding state of the sample surface layer elements or surface adsorbed elements. The exhaust hole 47 is connected to an independent exhaust system like the two chambers mentioned above, and is connected to the tooth surface analysis chamber &-1.
It is maintained at an ultra-high vacuum of 0 to 1 10 Torr.

Next, the effects of the present invention will be described using examples. First, as mentioned above, the present invention is a dry etching apparatus devised for producing OGXC conductors in compounds such as KG&AI. In this case, the required machining performance is
To clarify again here, first of all, surface damage or contamination is suppressed as much as possible, and processing I! The surface must be extremely smooth, and the machined cross section must be extremely steep and mirror-like. In contrast, the friend-reactive ion etching system, which is superior to the conventional 8l-LSI K in various respects, can perform elemental analysis or chemical bond state evaluation of the sample surface layer without exposing it to the atmosphere immediately before or after etching. They had no means of repairing surface damage caused by etching or searching for the source of contamination9.

Therefore, it can be said that the conventional apparatus consists of only nine etching chambers as shown in FIG. In contrast, in the present invention, since it is possible to accurately evaluate the sample surface condition by surface analysis immediately before etching, it is possible to obtain information regarding irregularities in the front surface raccoon stitch for each sample, and to correct such irregularities. Etching conditions for etching can be easily set. In addition, if the surface is severely damaged due to excessive etching where ion equilibrium is dominant, the damage can be repaired in the heat treatment chamber without exposing the sample to the atmosphere, that is, while keeping the sample surface clean. Also, depending on the incompleteness after recovery, the old damaged layer can be removed by etching again without adding new damage under etching conditions where chemical reactions are dominant. In this way, the device of the present invention performs a delicate etching process on compound conductors, which could not be achieved with conventional devices, by combining etching φ hot part U-surface analysis in various ways while keeping the sample surface clean. This is the greatest effect and advantage of the present invention.

In the embodiment of the present invention, a so-called ion shower etching method was introduced into the etching chamber. This is because we focused on the fact that this method has a structure that makes it easy to control the behavior of ions in plasma. Other etching methods such as magnetic field microwave and two-dimensional etching are also promising, and can be easily employed in the apparatus of the present invention. In addition, in the example, tIK3
Although an electric furnace 721 method using a heater was adopted as the heat treatment method shown in the figure, it is also possible to use a laser beam 721 method or an electron beam annealing method.

Although the present invention has been described in detail using the embodiments above, the patent rights of the present invention are not limited to the embodiments described above, but extend to all composite dry etching apparatuses shown in the claims.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the configuration of an embodiment of the present invention, and Fig. 2 is an explanatory diagram of the specific structure of the etching chamber shown in Fig. 1. storm,
19 is the quadrupole layer mass spectrometry needle, and RHEI Ro 31i! m
Qi F7=-1-143 is Ag3.454:! X! I source,
46 is an ultraviolet light source, and I is an energy analyzer. lr 1 illustrious 2 bold

Claims (1)

[Claims] 1. A gas phase as an etching gas in a vacuum scissors apparatus;
The etching apparatus is equipped with a means for promoting physical or chemical interaction with the solid phase as the substrate to be etched, and the etching apparatus is connected to the preparation room and the etching room alIli11. ψ and a surface analysis chamber 4WL;
Equipped with means for mass spectrometry of primary or secondary particles involved in shell interactions, the tIIl heat recording chamber J611 is equipped with at least means for heating the substrate and for detecting fluctuations in the stoichiometric ratio of the constituent elements of the substrate that occur when heating the substrate. Equipped with a means for compensating and a means for evaluating the crystalline state of the substrate surface layer, the pre-destructive box analysis
It is equipped with a means to enable the identification of the yc element and the analysis of the chemical bonding state, and further includes the preparation room, etching room, and heating section*i.
ii and the surface analysis chamber are isolated by the GoodPanel inserted in each coupling 11K and evacuated independently, and the substrate is made to be able to transfer the four chambers by the two-door mechanism. A composite dry etching device featuring: 1. The etching gas is a Hague compound, the gas phase/solid phase interaction is induced by an ion shower etching device, and the primary or secondary particle mass spectrometry means is a A mass spectrometry needle is used, and the means for evaluating the crystalline state is a high-speed reflective layer electron beam diffraction device, which makes it possible to identify the constituent elements of the substrate surface layer or the elements adsorbed on the III box and to analyze the chemical bonding state. The means is an Osin electron spectrometer or a photoelectron spectrometer. A composite dry etching apparatus according to claim 1.