JPH06112166A - Apparatus and method for plasma reaction using electromagnetic rf coupling - Google Patents

Abstract

PURPOSE: To work a sensitive device, without giving damages or using microloadings, to raise a yield and to achieve the etching of an oxygen containing layer present on an oxygen non-containing layer at a high selection degree. CONSTITUTION: A plasma reactor chamber uses an antenna 30 which is driven by RF energy (LF, MF and VHF) inductively coupled inside a reactor dome. The antenna 30 generates a plasma of high density and low energy, for etching the oxygen containing layer present on the oxygen non-containing layer at a high selection degree inside the chamber. Auxiliary RF bias energy impressed to a substrate supporting cathode 32 controls a cathode sheath voltage and controls ion energy, regardless of the density. Along with an etching processing, a vapor-deposition processing and an etching/vapor deposition combined processing, various magnetic and voltage processing improving techniques are presented.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to RF plasma reactors, and more particularly to radio frequency (RF) for electromagnetically coupling the associated RF electromagnetic waves into plasma.
It relates to an energy source, a plasma reactor using a silicon source in contact with a plasma, and a method to be processed in the reactor.

[0002]

BACKGROUND OF THE INVENTION The trend for high density integration is that components of very small dimensions are electrically sensitive and susceptible to damage by energetic particle bombardment when exposed to wafer sheath voltages as small as about 200-300 volts. And brought the device. Unfortunately, such voltages are less than the voltages that circuit components experience during standard integrated circuit manufacturing processes.

MOS-type capacitors and transistors manufactured for advanced devices have very thin gate oxides (200 Angstroms or less). These devices can be damaged by charging, which causes gate breakdown. This may occur during plasma processing due to non-uniformity of plasma potential or plasma density, or due to large RF displacement currents, when surface charge neutralization does not occur. Conductors such as intermediate connecting lines may also be damaged for the same reason.

Conventional plasma etching chambers when very high aspect ratios, ie very deep and very narrow openings and trenches have to be formed in or filled with different semiconductor materials. The etching method achieved within is inadequate. RF system CVD (chemical vapor deposition) reaction system and RIE (Reactive I)
First, a conventional semiconductor processing system such as an on-etching reaction system will be considered. These systems are about 10-500
High frequency energy from low frequencies of KHz to high frequencies of about 13.56-40.68 MHz may be used.
Below about 1 MHz, ions and electrons can be accelerated by an oscillating electric field or any steady-state electric field generated in plasma. At such relatively low frequencies, the electrode sheath voltage developed on the wafer is typically above the 1 kilovolt peak, which is well above the damage threshold of 200-300 volts. Above a few MHz, the electrons can still follow the changing electric field. When the amount of ions is larger than this, it cannot follow the changing electric field and is accelerated by the steady-state electric field. In this frequency range (and practical gas pressures and power levels), steady state sheath voltages range from hundreds of volts to over 1,000 volts. A preferred method for reducing the bias voltage of a magnetic field-enhanced RF system is to apply a magnetic field to the plasma. This B-field confines the electrons to a region near the surface of the substrate, increasing ion flux density and ion flow, thus reducing voltage and ion energy requirements. As a comparative example, a typical non-magnetic RIE process for etching silicon dioxide has RF energy applied at 13.56 MHz, an asymmetric system with a volume of 10-15 liters, a pressure of 50 mTorr and about (8-10). An anode area / substrate support cathode area ratio of 1 is used to generate a substrate (cathode) sheath voltage of about 800 volts. When a magnetic field of 60 Gauss is applied, the bias voltage is about 25-30%, 800
From 500 volts to about 600 volts, the etch rate increases by about 50%.

However, application of a steady B field parallel to the substrate causes a plasma density gradient across the substrate associated with the E × B ion / electron drift. This plasma gradient causes non-uniformity of etching, deposition and other film properties on the substrate. This non-uniformity can be reduced by rotating the magnetic field around the substrate, which usually involves mechanical movement of the permanent magnets, or electromagnetic coil pairs or coil pairs driven in 90 ° quadrature. Current can be reduced by momentarily controlling the current in a magnetic field to step or otherwise move at a controlled rate. However, rotating the magnetic field reduces the non-uniformity gradient, but usually leaves some non-uniformity.

Further, it is difficult to install coils, especially two or more pairs of coils in a chamber to form a compact system, and it is difficult to configure a Helmholtz coil arrangement or individual loadlocks surrounding a common loadlock. Is particularly difficult when using a multi-chamber system consisting of the magnetically enhanced reactor chamber of

A unique reactor system designed to be used in a small multi-chamber reactor system with the ability to instantaneously selectively change the strength and direction of the magnetic field was co-assigned under the name Cheng et al. It is disclosed in U.S. Pat. No. 4,842,683 dated 27th March. Microwave / ECR system For microwave systems and microwave ECR (Electron Cyclotron Resonance) systems, 800 MHz or higher is usually used.
The plasma is excited using microwave energy with a frequency of 2.45 GHz. Although this technique produces a high density plasma, the particle energy may be below the minimum reaction threshold energy for many processes such as reactive ion etching of silicon dioxide. To compensate for this, energy-enhancing low-frequency power is coupled to the substrate support electrode and to the plasma through the substrate.
In this way, the potential for substrate damage is reduced compared to conventional systems.

However, etching or CVD
Microwave systems operating at practical power levels for semiconductor substrate processing such as microwave ECR include large waveguides for power delivery, expensive tuners, directional couplers, circulators, and dummies for operation. Need a load. In addition, a magnetic field of 875 Gauss is required to meet the ECR requirements of a microwave ECR system operating at a commercial frequency of 2.45 GHz, which requires large electromagnet, power and cooling specifications.

Microwave system and microwave EC
It is not easy to scale up or down the R system. The hardware is available for 2.45GHz. This is because this frequency is used in microwave ovens. 91
A 5MHz system is also available, but at a higher cost. Hardware for other frequencies is not readily or economically available. As a result, higher order modes of operation are required when expanding 5-6 inch microwave systems to process larger semiconductor substrates. Scale-up at constant frequencies by operating in this higher mode requires so-called mode flipping to higher or lower loads and very rigorous process control to prevent resulting process changes. Becomes Alternatively, for a 5-6 inch microwave cavity, for example, a divergent magnetic field can be used to spread the plasma flux over a wider area to achieve this scale expansion. This method reduces the effective power density and hence the plasma density.

In addition, ECR systems must be operated at very low pressures, on the order of 2-3 millitorr. This is because the density of the plasma generated in this system very quickly rises above about 2-3 mtorr. This requires a large amount of reactive gas to be supplied to the system, and requires a large exhaust system to remove these large amounts of gas. RF Transmission Line System As mentioned above, the name of the inventor Collins and others is 1990.
Parent U.S. Patent Application No. 559,947 (A) entitled "VHF / UHF Reactor System" transferred concurrently on July 31, 2013
The MAT file 151-1) is referred to here.
In this application, a part of the reaction chamber itself is a high frequency VHF / UH configured as a transmission line structure for applying high frequency plasma generation energy from the matching network to the chamber.
An F reactor system is disclosed. This unique monolithic transmission line structure meets the very short transmission line requirements between the matching network and the load, allowing relatively high frequency specifications from 50MHz to 800MHz. This enables efficient and controllable application of RF plasma generation energy to the plasma electrode, producing commercially acceptable etch and deposition rates at relatively low ion energy and low sheath voltage. This relatively low voltage reduces the likelihood of damage to electrically sensitive small sized semiconductor devices. This VHF / UHF system avoids various other problems in the prior art such as the above-mentioned possibility of enlargement / reduction and power limitation.

[0011]

SUMMARY OF THE INVENTION In one aspect, the present invention solves the problems of the prior art by providing a vacuum chamber having a source region, a process gas source within the chamber, and a plasma from the process gas. RF including a means for electromagnetically coupling RF energy to a plasma region to generate a plasma, a means for capacitively coupling RF energy to a substrate support electrode to control a plasma sheath voltage of the support electrode, and a silicon source in contact with the plasma. It is embodied in the configuration and operation of the plasma processing system.

Preferably, the RF antenna means is adjacent to the plasma region and is coupled to the RF energy source. The chamber of the present invention can be connected to an RF cathode in the process region, an anode defined by champer walls, and electrically floating, grounded, or RF biased to enhance plasma processing. It has a third electrode. The third electrode and / or the champer wall defining the plasma region may be a silicon source to enhance processing, such as oxide etching. With the apparatus of the present invention, plasma etching can be selected almost infinitely, and plasma deposition can be void free.

[0013]

[Example] 1. SUMMARY The present invention provides an apparatus and method for plasma treatment that allows for improved selectivity of the etching process and various etch rates, as well as deposition of deposited layers and simultaneous etching and planarization.

In the chamber of the present invention, preferably,
LF / VHF (low frequency to very high frequency) RF power in the range of 100 KHz to 100 MHz is used. More preferably, M within the range of 300 KHz to 3 MHz
F (medium frequency) RF power is used. Preferably, the coupling means is a multi-turn cylindrical coil antenna having an unwound electrical length of less than λ / 4. Where λ is the wavelength of the high frequency RF excitation energy applied to the coil antenna during plasma operation.

The invention also includes means connected to the antenna for tuning the antenna to resonance, also for matching the input impedance of the plasma source to the output impedance of the means for providing RF energy for the antenna. Load means connected to the antenna. The tuning means may be a variable capacitance electrically connected between one end of the antenna and RF ground. RF
Energy can be applied via taps to selected locations on the coil antenna.

The present invention includes a dielectric dome or cylinder that forms the plasma source region. Suitably, the coil antenna surrounds the dome for inductively coupling high frequency electromagnetic energy into the chamber. The article or substrate to be fabricated can be located in the plasma source region or dome, inside or close to the antenna winding or the bottom winding, or preferably below the antenna.

The present invention also relates to a gas inlet at the top of the dome, a first ring manifold at the base of the plasma source region of the dome, and a substrate support electrode surrounding the chamber with processing diluents, passivations, and other gasses. Means for supplying gas to a chamber comprising a second ring manifold for selectively supplying. Further, an AC power supply and control system couples AC bias power, which is usually at or near the plasma source coil power, to the substrate supporting cathode, thereby irrespective of the plasma density control provided by the plasma source RF power. Controls sheath voltage and ion energy. This system provides bias frequencies selected to serve a number of purposes. First, the upper frequency limit is chosen to prevent "current-induced" damage, which can cause charge-up damage to sensitive devices if the frequency is too high. The lower the bias frequency, the higher the substrate sheath voltage per unit of bias power (excluding substrate heating) and the smaller contribution to plasma density, thus improving the independent control of ion density and ion energy. However, if the bias frequency is too low, the ion follows the RF component of the substrate sheath electric field, which changes the ion energy. As a result, the peak / average energy ratio is increased and the ion energy distribution is widened (2 peaks). Very low bias frequencies cause insulator charge-up, disabling ion-induced processing for some of the bias frequency period. The preferred frequency range satisfying the above precautions corresponds to the preferred plasma source frequency range described above.

In addition, the present invention provides a DC bias voltage with periodic pulses between selected low and high values to passivate a coating (first) on a first selected material on a substrate to be etched. Passivation coating), eg, a control means for forming a polymer coating, to provide a relatively low etch rate of the substrate material and a relatively high rate of the second material, eg, a layer of the second material on the substrate. And, the etching is selectively performed according to the selectivity.

The chamber has a first vacuum pump means connected to the chamber body and a second vacuum pump means connected to the dome.
Is evacuated by means of a vacuum pumping means in the dome, thereby establishing a vertical pressure differential within the dome to establish the flow of neutral particles out of the dome, the voltage of the substrate support electrode being It is sufficient to overcome this pressure differential as it flows towards the chamber body.

The present invention also includes a conductive Faraday shield having a different structure, which is interposed between the coil antenna or other coupling means and the reaction chamber to prevent the electric field component of the high frequency electromagnetic energy from coupling to the chamber.
Also, a high frequency reflector positioned to surround the coil or other coupling means concentrates the emission of high frequency energy within the chamber.

The magnetic enhancement is provided by a peripheral permanent magnet or electromagnet arrangement, which applies a controlled static magnetic field parallel to the axis of the antenna selected from a uniform diverging magnetic mirror arrangement, allowing the plasma below the substrate Control the position and movement of. Also, magnets can be attached around the plasma source and / or the chamber to apply a multi-polar cusp magnetic field to the chamber near the substrate, thereby confining the plasma in the substrate region and at the same time largely eliminating the magnetic field of the substrate. . Furthermore, magnetic shunts can be placed around the substrate and the substrate support electrode to redirect the magnetic field from the substrate support electrode.

This system configuration allows the size to be scaled up while maintaining low mode operation by selecting the operating frequency. In a processing aspect, the present invention provides a vacuum chamber having a plasma source region and a processing region, supporting an article or substrate to be processed on an electrode within the chamber and applying a plasma sheath voltage on the substrate supporting electrode. Providing a silicon ion source for electromagnetically coupling RF energy to the chamber for controlling, capacitively coupling RF energy to the chamber through the supporting electrode for controlling the sheath voltage on the supporting electrode, and in contact with the plasma. And a plasma generating process.

The present invention also includes automatic iterative tuning of the antenna for resonance and loading of its input impedance into the impedance of the RF energy source for the antenna. The plasma generation process provides a vacuum chamber having a plasma source region and a treatment region and a wall, an electrode in the treatment region and an electrode in the plasma source region, wherein the treatment region electrode is the cathode, the wall is the anode, and the plasma source electrode is The electrical connection is selected from ground, floating and RF or bias to electrically connect the electrode in the processing region, the walls of the chamber and the plasma electrode to support the article to be processed on the substrate support electrode, the chamber By a plasma generating gas for processing one or more materials on the article using a cylindrical coil antenna connected to a means for supplying a processing gas to the antenna and providing RF energy to the antenna. , Inductively coupling RF energy into the plasma source region and supporting current to control the sheath voltage at the supporting electrode. Capacitively coupled RF energy into the chamber via, and a processing method and a silicon source in the chamber.

The silicon source is preferably a third electrode located in the plasma source in the chamber, not necessarily the electrode, but somewhere in the chamber in contact with the plasma. Further, the antenna power and the bias power supplied to the electrodes are controlled to selectively perform anisotropic, semi-anisotropic and isotropic etching.

The processing chamber of the present invention is particularly useful for etching a layer of a second material, particularly an oxygen containing layer such as an oxide on an oxygen free substrate such as silicon. The use of a silicon ion source in the process chamber results in improved selectivity and increased etch profile. Further, the process of the present invention cyclically biases the bias voltage to a selected low value to form an etch-inhibiting layer on silicon, such as a polymer, and a high value to etch a second material at a fast rate with respect to the substrate. Including a method of driving. In all cases, the device of the present invention provides a high etch rate and high selectivity that requires making high aspect ratio openings in the second layer towards the substrate.

The processes in the reactor of the present invention include sputter deposition of oxides such as silicon oxide or silicate, and first applying a relatively low RF power to the support electrode to deposit the oxide, and secondly silicon. It involves the two steps of depositing an oxide, sputter faceting the silicon oxide, and applying a relatively high level of RF power to the support electrode to planarize the layer.

A specific method of the present invention is the oxidation including etching contact holes in an oxide formed on an oxygen-free substrate and etching through holes in an oxide formed on aluminum or another substrate. Etching; fast isotropic and anisotropic oxide etching; etching of polysilicon conductors such as gates, photoresist removal; anisotropic etching of single crystal silicon; anisotropic photoresist etching; nitrogen and oxidation Low pressure plasma deposition of nitrogen; high pressure isotropic conformal deposition of oxides, oxynitrides and nitrides; etching of metals such as aluminum, tungsten and titanium and compounds and alloys such as tungsten silicide; and at various deposition rates, Localized with flattening
It includes, but is not limited to, deposition of various materials, including blanket sputter facet deposition. 1. Overview FIGS. 1-3 illustrate a plasma reactor 10 for processing a semiconductor substrate 5 using an inductive plasma source device, a magnetically enhanced plasma source device, a capacitively coupled bias device, and other aspects of the invention. It is a schematic sectional drawing. The three figures show preferred and other features of the system.
Three drawings are used due to the limited drawing space. The illustrated chamber is a modification of that shown in the co-pending, continuation-in-part application having an integral transmission line structure. The important features of the present invention can be widely applied to plasma reactors. In addition, those of ordinary skill in the art will appreciate that various features of the present invention that enhance reactor performance can be utilized individually from the following description and can be optionally omitted from the system. You can also For example, the processing conditions provided by a bias source capacitively coupled to an inductive plasma source device often eliminates the need for magnetic enhancement.

The illustrated system 10 includes a side wall 12, a top wall 1
3. Vacuum chamber housing 11 made of anodized aluminum or other suitable material having a bottom wall 14.
including. Anodized aluminum is preferred because it suppresses arcing and sputtering. However, other materials suitable for this process, such as bare aluminum with or without a polymer, quartz, or ceramic liner, can be used. Top wall 13 is wall 12
Lower chamber substrate processing unit 16 formed between -12
It has a central opening 15 between B and the upper chamber plasma source 16A formed by the dome. The dome is preferably constructed as an inverted single wall or double wall cup formed by a dielectric such as quartz or some other dielectric material such as aluminum or alpha alumina (sapphire). it can. In the embodiment shown in FIG. 1, the dome 17 is a cylindrical wall 17 made of a dielectric material such as quartz.
It consists of W and a cover or top wall 17T made of normal aluminum or anodized aluminum. For purposes such as highly selective oxide etching, silicon or silicon containing top wall means and silicon covered dome sidewalls are preferred.

As shown in FIG. 1, the reduced pressure exhaust inside the chamber housing 11 (chamber 16) is performed by the bottom wall 14
It is controlled by a throttle valve 18 (regulating pressure independent of flow rate) in a vacuum line 19 connected to a vacuum pump system 21 consisting of one or more vacuum pumps connected to the. As described in Section 11, the chamber components, including the chamber walls and dome, can be heated and / or cooled for processing performance. For example, the dome can be heated or cooled by a liquid or gas heat transfer medium, or heating elements can be used to heat the dome directly.

As shown in Section 2 and illustrated in FIG. 2, process gas, purge gas, diluent, etc., are provided at the base of the plasma source (dome), the top plate 17T of the plasma source,
And can be supplied to the chamber by three manifold sources G1, G2, and G3, respectively, arranged around the periphery of the substrate. These gases are supplied to the chamber 11 from, for example, one or more pressurized gas sources via a computer controlled flow controller (not shown). In the main intake manifold G1, gas enters the internal vacuum processing chamber 16 as shown at 22 via a quartz ring gas manifold 51 mounted inside the top wall 13 or integral with the top wall 13. Manifold 23
Is preferably a chamber portion 16 for generating an etching or deposition plasma after the application of RF energy.
The etching gas or vapor deposition gas is supplied at an angle slightly upward with respect to B and 16A. The top manifold device G2 in the top plate 17T of the dome 17 can be used to admit a reactive gas or other gas into the chamber 16. Further, a manifold device G3 for supplying the reactive gas and other gas may be provided around the substrate.

RF energy is supplied to the dome by a plate source consisting of at least one turn antenna 30 or a coil fed by an RF supply and matching network 31. The antenna 30 preferably has a multi-turn, cylindrical configuration. Coil 30 defines a minimum conductor electrical length for a given frequency and plasma source (coil) diameter, and is preferably a quarter wavelength (<
It has an electrical length of λ / 4) or less. The antenna 30 itself is not a resonator, but is tuned to resonance as described in Section 5 to provide effective inductive coupling with the plasma source by Faraday's law of inductive coupling.

Preferably, the chamber plasma source section 16A
From the substrate flows downward toward the substrate 5 and is then extracted radially outward from the substrate. To this end, around the cathode transmission line structure 32, between the chamber wall 12 on one side and the outer transmission line conductor 320 on the other side, and between the bottom chamber bottom wall 14 and the top conductive pumping screen 29. An annular vacuum manifold 33 can be formed. Manifold screen 29 is interposed between vacuum manifold 33 and substrate process chamber 16B to provide a conductive path between chamber wall 12 and outer conductor 320 of transmission line structure 32. Vacuum manifold 3
Reference numeral 3 forms an annular pumping channel for uniformly extracting the exhaust gas from the periphery of the substrate 5 in the radial direction. The vacuum manifold 33 communicates with the exhaust gas system line 19. Gas flow from passage 2 from manifold G1
2 to the dome / plasma source and / or radially inward toward the substrate 5 along passages 24 from manifold G2 and / or passages 26 from manifold G3. The overall gas flow is from the upper chamber plasma source 16A to the substrate 5 along the passage 34, from the substrate through the screen 29 along the passage 3 to the exhaust manifold 3
3, and along passage 37 from exhaust manifold 33 to exhaust system 21. It should be noted that the conductive manifold screen 29 and cathode transmission line structure are optional. Usually, the wavelength is very long on the low frequency side of interest, so no transmission line structure is required.

This is in contrast to conventional RF system configurations, where the RF power is supplied by two electrodes, typically the wafer support electrode 32C, whose top surface supports the substrate 5, and the side walls 12, top wall 13 and 13 of the reactor chamber. And / or a second electrode, which is the manifold 23. In particular, the antenna 30 is located adjacent to the dome 17 and outside of the plasma chamber 16A and is adapted to couple RF electromagnetic (em) energy into the plasma source chamber 16A to induce an electric field in the process gas. . From the Faraday's law of inductive coupling, B where the em energy changes
The (magnetic) component urges the process gas to urge the chamber 16
A plasma having the characteristics of relatively high density and low energetic ions is formed therein (reference numeral 16 collectively refers to chambers 16A, 16B and plasma). This plasma is generated in the dome 17 by being concentrated in a small volume formed in the coil antenna 30.
Active species including ions, electrons, free radicals and excited neutrals move downstream towards the substrate by diffusion and bulk flow by the gas flow described herein. Also, as described in Section 7, an appropriate magnetic field can be used to extract ions and electrons toward the substrate as will be described next. Although this is optional, the bias energy input device 41 of FIG. 1 consisting of the plasma source 42 and the bias matching network 43 provides RF energy to the substrate support electrode 3.
Coupled to 2C, it is preferred to selectively increase the plasma sheath voltage of the substrate, thereby increasing the ion energy of the substrate.

The reflector 44, which is basically an open bottom box, surrounds the antenna at its top and sides, but not at the bottom of the antenna 30. This reflector 44 prevents radiation of RF energy into free space, thereby concentrating radiation and dissipation of power in the plasma for increased efficiency. As described in detail in Section 7, the Faraday shield 45 of FIG. 3 can be placed inside, above and below the antenna 30 to allow the magnetic field to couple to the plasma but to disable direct electric field coupling. ing. Direct electric field coupling can induce tilts and inhomogeneities in the plasma, or can accelerate charged particles to high energy.

As described in Section 8, in order to improve the plasma density on the substrate 5, transfer ions to the substrate, or improve the uniformity of plasma, as shown in FIG.
One or more electromagnets 47-47, or permanent magnets, can be mounted in close proximity to the chamber enclosure 11. As described in detail in Section 4, the present invention uses potentially magnetically damaging components of magnetically coupled components of inductively coupled electromagnetic energy at frequencies well below the microwave or microwave ECR frequencies. A circular electric field is induced in the vacuum chamber to create a plasma with high density and relatively low energy without coupling high power RF energy to the substrate 5. In the preferred downstream plasma source configuration shown, the RF energy is completely absorbed at high plasma density away from the substrate so that the waves do not propagate to the substrate and thus minimize the potential for damage. Optionally and optionally, RF bias energy is applied to the substrate support electrode 32C to increase the substrate sheath voltage and thus the ion energy as needed.

Chamber 16 uses a total chamber pressure of about 0.1 mTorr to about 50 Torr, typically 0.1 mTorr to 200 mTorr for etching to process substrates including semiconductor wafers by vapor deposition and / or etching. it can. The chamber was capable of operating at pressures below 5 mTorr and indeed worked normally at 2 mTorr. However, high pressures are preferred for certain processes in terms of increased pumping speed and flow rate. For example, a pressure range of about 5 mTorr to about 50 mTorr is suitable for oxide etching. At such relatively high pressures, the distance between the plasma source and the substrate must be small. The chamber of the present invention includes the substrate 5 and the antenna 30.
Spacing between the bottom turns and about 5 cm / 2 in. With very small spacing d, which worked very well, it worked well without charge-up damage to sensitive devices. Therefore, the advantage of having such a very small spacing,
That is, improved etch rate and selectivity, reduced bias voltage and ion energy requirements for a given etch rate, and improved energy uniformity on the substrate. For example, the distance d between the substrate 5 and the source antenna 30 is 10 cm / in. When it was reduced from (which itself is a small interval) to 5 cm / 2 in, the required voltage was halved and the uniformity increased from about 2.5% to about 1%. 2. Gas processing system As described above, this chamber is filled with reactive gas, purge gas, etc. at different locations to improve processing depending on the processing conditions (etching, vapor deposition, etc.) and the materials used for the processing. A plurality of gas injection sources G1, G2, G3 (FIG. 2) for allowing the gas injection are incorporated. First, the chamber has a standard radial gas distribution system G1 around the base / bottom of the plasma source region 16B. In the preferred arrangement, the G1 injection system consists of a quartz gas distribution ring 51 at the bottom of the plasma source and a peripheral annular manifold 52 forming a distribution channel for supplying gas to this ring. This ring has radial holes 53-53 facing inward
And preferably has a stepped sintered ceramic porous gas diffusion plug 54-54 inserted into the hole to prevent hollow cathode discharge.

The second gas injector G2 is grounded, made of a material such as anodized aluminum with a central intake hole 56 filled with a porous ceramic diffusion disk 57.
Alternatively it may consist of a floating or biased dome top plate 17T. The third gas injection source G3 is from a ring-shaped intake manifold 58 attached to the periphery of the substrate 5 (or a gas intake port built in a clamp ring (not shown) used to hold the substrate on a support pedestal). Become.

When etching openings through an oxygen-containing layer, such as silicon dioxide, across the surface of an oxygen-free layer containing single crystal or polysilicon, silicon dioxide is preferably etched at a much faster rate than polysilicon or other substrates. To be done. The etching gas containing fluoride is used as an etchant. However, since fluoride etchants usually etch materials such as silicon dioxide and polysilicon at the same rate, for example, the etch has little selectivity for oxide over silicon. However, during reactive ion etching, protective layers of polymer are formed on the sidewalls and bottom of the growing openings. Such polymers are formed from carbon and fluorine,
It typically contains about 30% carbon and about 60% fluorine.

The polymer is separated in the presence of fluorine atoms. What you need is about 50% or more carbon and about 40%
The following is to form a polymer having a high content of carbon including fluorine. If a scavenger for fluoride ions is placed in the reactor, there will be few free fluoride ions in the plasma and C—F bonds will not form in the polymer film. I have found Success in conventional reactors has been obtained by adding a scavenger for fluoride ions to the plasma itself, such as silane or organosilane, to provide free silicon in the plasma. However, because many different plasma ions are formed, the process is "dirty" in nature, the properties of the eygent and polymer are different, and non-uniform, making the process completely reproducible. Absent. Therefore, the present device is excellent because it provides a "clean" silicon source for removing free fluoride ions.

According to the present invention, such a fluoride ion scavenger is a reactant for fluoride. And it is preferably a silicon source in or near the plasma. The foot scavenger is preferably pure silicon such as single crystal silicon, polysilicon or silicon carbide, or the third electrode is preferably made of silicon or a silicon-containing material. Graphite can also be used to remove fluoride ions. For example, the third electrode is made of graphite.

During plasma etching in the chamber of the present invention, the oxygen in the silicon oxide film readily etches the polymer formed on the sidewalls and bottom of the growing trench. However, when the trench depth reaches polysilicon or other oxygen free substrates, there is no oxygen present,
Also, the polymer remains on the polysilicon surface, protecting the substrate from further etching.

Preferred etchants here are CF _4, C ₂ F ₆
And fluorocarbons such as C ₃ F _8, which generate only carbon and fluoride ions. Other known fluorides,
For example CHF ₃ is not preferred. Because they generate hydrogen ions in addition to carbon and fluorine ions. According to the present invention, a very high selectivity between the oxygen-containing layer and the oxygen-free substrate or the lower layer can be obtained almost infinitely. This is because carbon-rich polymers do not decompose on silicon surfaces or oxide-free substrates or oxygen-free layers. These polymers are sensitive to oxygen and, in the absence of oxygen, for example, when the etchant reaches an oxygen-free substrate, the separation of the polymer is reduced, and when bound to the plasma with reduced fluorine ions, the layer is passivated. Forming a relatively inert polymer that is becoming
Protect the bottom layer.

The silicon source is preferably placed near the location where the plasma is generated so that the silicon can scavenge fluoride ions. Fluoride ions rarely react with the surface of the substrate being treated. For example, a silicon mesh is suspended in the plasma region, or silicon is placed near the wall or top of the reactor as part of the RF power source. The silicon source can also be suspended near the surface of the substrate, but polymers with high fluoride content may result.

The silicon source may be located outside the plasma region of the reactor, and in any case at a temperature at which silicon ions are formed to remove fluoride ions, eg at least about 150 ° C. or higher. Be heated. In that case, means for adjusting the temperature of the silicon source must be provided in the reaction chamber.
There are other advantages when the reactor of the present invention is used as a deposition chamber for depositing various films. For example, after a trench or opening is created in the substrate, the trench or opening is filled with another material to form conduction or isolation between devices in the substrate. For example, the openings in the substrate are filled with silicon oxide using silane and oxygen. This requires careful control of the deposition rate to avoid void formation at the bottom corners of the trench, or in the center of the deposit. This latter phenomenon is well known and dealt with for ECR processing. To avoid this problem, it is known to sputter the top of the trench with argon prior to deposition, ie to facet the top of the trench or opening. This allows the top of the trench to be opened without blocking around the void. However, E
The CR process is disadvantageous because very low pressures on the order of 2-3 mTorr are used to maintain high ion densities. The ion density in the ECR is very pressure dependent. The ion density is maximized at about 1-2 mtorr and drops sharply at pressures of 5-10 mtorr. Therefore, a large amount of gas must be supplied to the ECR, and a large vacuum pump is needed to pump out the excess gas.

The device of the present invention forming an inductive plasma maintains a high ion density up to a pressure of about 30 mtorr. Thus, a very high pressure, about 15-30 mtorr, is maintained in the inductively coupled plasma of the present invention, and concomitantly little gas needs to be fed to the reactor. And 1-2 required for vapor deposition in ECR
A small vacuum pump is required to remove by-products and excess gas other than Millitol pressure operation.

The device of the present invention provides trenches which meet the results in an equivalent, but simple and inexpensive way, to those obtained in ECR. Due to the low temperature operation and the ability to adjust the ion density of the plasma generated at low pressure, a similar method can be achieved in the apparatus of the present invention without the need for large volumes of gas or large vacuum pumps. Thus, the introduction of appropriate amounts of silane, oxygen and argon, for example into the reactor, sputters the top, sidewalls of the trench and forms a plasma which fills the trench with silicon oxide. Voids are avoided in the silicon oxide deposition and the formation of the top of the trench and the deposition or filling of the trench can be done in a single process step.

As mentioned above, various types of gases selected from etchants and vapor deposition species, passivation species, dilution species, etc. are used to meet the requirements of special etching and vapor deposition processes and materials. -Supplied to the chamber via one or more sources of G3. For example, the present inductive plasma source antenna 30 provides very high density plasma and is very effective at separating gases in the dome plasma source region 16A of the chamber. As a result, when polymer-forming species are fed into the dome via G1 or G2, the highly isolated species may coat the interior of the dome at the expense of the polysilicon coating, and / or sufficiently. Being separated, it does not adhere to the surface of the polysilicon to be coated for protection. One solution is to use etching species such as C ₂ F ₆ or CF ₄ with G1 or G2, or G1.
And G3 to insert into the plasma source region and provide silicon to remove fluoride ions to form a preferentially carbon-rich polymer on the substrate. Due to the high separation of gases in the plasma source region, free fluoride ions that etch fluorine-containing gas (fluorine may be present with carbon in the fluorine-containing gas) silicon and silicon oxide are typically generated. . Therefore, the etch selectivity for oxide is reduced. In addition to providing a silicon source in the plasma,
When high selectivity is required, additional gases containing silicon are inserted to further scavenge free fluoride ions and to reduce etching of oxygen free substrates. Etching gas and additional gas containing silicon are G1 and G
Can be introduced separately via G2 or G1
And / or mixed via G2. Suitable fluorine-containing silicon-containing additional gases are silane (SiH ₄ ), TEOS, diethylsilane and silicon tetrafluoride.
(SiF ₄ ) is included.

Fluorine-consuming silicon source gas and polymer addition gas can be used together in the same process to enhance etch selectivity. 3. Differential Pumping Figure 2 shows an alternative vacuum pumping configuration. In addition to the vacuum pumping system 21 connected at or near the bottom of the chamber, a vacuum pump 39 is connected via line 38 to the plasma source region 16A in the dome 17. The flow rates of pumping systems 39 and 21 are selected so that they produce a pressure difference ΔP _p in the plasma source region 16B in the vertical direction. This pressure difference ΔP _p is (1) less than the force F _b applied to charged particles such as electrons and ions by the bias voltage (2) to prevent movement of uncharged particles from the plasma source 16A to the substrate 5. Due to ΔP _p , uncharged particles such as radicals do not reach the substrate 5 but rather flow out mainly from the top vacuum connection 38.
Since F _DC > ΔP _p , charged electrons and charged ions mainly flow into the processing region. It is clear that this method is effective when it is desired to selectively place radicals rather than ions outside the substrate processing area. This situation may include, for example, (1) using polymer forming gas chemistry, but where the polymer is formed in the plasma source region and adheres to the sidewalls of the chamber and / or does not adhere well to the desired substrate surface, or (2 ) It occurs when fluorine groups are formed in the plasma source region. 4. RF Power, Top and Bias Source 1) Top or Antenna Source In FIG. 1, preferably the operating frequency of the RF power source 31 of the upper plasma source 16A is to generate a dense plasma to minimize damage to sensitive equipment. And is selected to provide efficient inductive coupling of RF power to the plasma. That is, frequencies above this operating range are limited to minimize "current-induced" damage. The lower limit of operating frequency is selected to increase the efficiency of RF power coupling into the plasma. Suggested limits are mentioned above. 2) The AC power source 42 of the lower portion or the bias source substrate supporting cathode 32C inductively couples RF power to plasma, thereby generating cathode sheath voltage and ion energy which are controlled independently of plasma density control performed by high frequency power. Controls various elements, including: The bias frequency is chosen to achieve many goals. First, the upper frequency limit is chosen to prevent current-induced charge-up damage to sensitive devices. The lower frequencies are selected in part to eliminate voltage-induced damage. Also, if the frequency bias is low, the substrate sheath voltage (excluding heating) per unit bias voltage of the substrate is high, and the contribution to the plasma density is small, thus improving the independent control of the ion density and the ion energy. However, if the bias frequency is too low, the ions will follow the RF component of the substrate sheath electric field, thereby modulating the ion energy. As a result, the peak / average energy ratio is high and the ion energy distribution (between peaks) is wide. At very low bias frequencies, insulation charge-up occurs, which disables ion-induced processing as part of the bias frequency control.

The Applicant has found that the above considerations are satisfied by using a bias frequency range corresponding to the plasma source frequency range described above. 3) Operation of coupling the upper antenna source and the bias source A preferred feature of the present invention is to automatically change the lower or bias power supplied by the power supply 42 to maintain a constant cathode sheath voltage. At low pressures (<500 mtorr) in highly asymmetric systems, the DC bias measured at cathode 32C is an approximation of the cathode sheath voltage. The lower power can be changed automatically to maintain a constant DC bias. The effect of bottom or bias power on plasma density and ion current density is very small. The top or antenna power has a very large effect on the plasma and current densities, but very little on the cathode sheath voltage. Therefore, it is desirable to use the upper power to define the plasma density and the ion current density and the lower power to define the cathode sheath voltage.

Nevertheless, the high frequency of the power source 31 for driving the antenna 30 is microwave or microwave E.
It is also possible to use an optional smaller magnet operated at a lower DC current by a cheaper power supply, since it is much lower than the frequency used in CR applications. In this case, the associated heat load is also reduced. Further, as is clear from the above description, a coaxial cable such as 31C can be used instead of the waveguide. Furthermore, plasma inhomogeneities caused by E × B electron drift in other magnetically enhanced or magnetically assisted systems are not present here. This means that the applied magnetic field (both the magnetic component of the RF field ignited via the antenna 30 and any static magnetic field applied by the magnet 81) is approximately parallel to the electric field of the cathode. Therefore, there is no E × B drift in this system.

A magnetic shunt formed of a material having a high magnetic permeability is used to generate a B field in the plasma source (upper chamber 16A) and not in the substrate. As an option, a permanent magnet or electromagnet may be installed in the lower chamber 16
Multiple cusp magnetic mirrors can be created on the plasma source and / or chamber walls in a multipole array of alternating magnetic pole configurations, usually NS-NS-NS ... N-S, around B.
The magnets can be vertical bar magnets or preferably, for example horizontal ring magnets. Such magnets can be used to reduce electron losses to the walls, thereby improving plasma density and plasma uniformity without exposing the substrate to magnetic fields. 4) RF Power Supply Coupling and Synchronization As mentioned above, the preferred frequencies of operation of the top or antenna RF power supplies and the preferred frequencies of operation of the bottom or bias RF power supplies are conveniently in the same range. A configuration that can be selected here is to combine these two RF power supplies into one power supply instead of using them separately. More generally, three RFs
Signal (including RF bias to third or top electrode)
May be supplied from a single power supply, or one power supply may be used for the antenna and the lower bias, a second power supply may be used for the third electrode, or three separate power supplies may be used. If separate power supplies are used, then one must consider that the frequencies of the separate RF signals must be equal or, if they must, be locked to these desired phase relationships. Whether or not. Preliminary studies have shown that the answers to these questions depend mainly on the selected operating frequency. A single RF power supply is a logical choice if one frequency can be selected for two or three RF power supplies, and that frequency cannot be changed for another process in which this system is used. It will be.

However, subparagraphs 1-3 above
Based on the considerations discussed above, separate RF power supplies are required if different frequencies are required for these plasma sources, or if the frequencies must be changed for use in different processes. If there are separate sources and the same frequency is selected, then phase synchronization is probably not a problem, except at relatively low frequencies such as below a few 100 KHz. For example, the power supply maintains the phase angle between the RF voltage input to the antenna and the RF voltage input to the bottom or substrate electrode at a constant value selected to optimize the repeatability of the process. At high frequencies, operation appears to be independent of phase or frequency synchronization. 5. Antenna Tuning and Load 1) Tuning Normally, the antenna 30 is either (1) changed by changing the frequency of the oscillator 31 to resonate with the antenna, or (2) separately connected to the antenna for tuning. Is tuned to resonance by the resonant element of. For example, the tuning element can be variable inductance-ground or variable capacitance-ground.

It should be noted that inductive tuning and capacitive tuning lower the resonant frequency. Therefore, it is desirable to configure this system for the highest resonance frequency desired, to handle the reduction in resonance frequency when using capacitance or inductance tuning variables. Automatic tuning is preferred and can be performed by driving the tuning / load variable with an impedance phase / amplitude detector. See Figures 6 and 9. Also, both reflected power bridges or VSWR bridges can be used to drive both tuning and load variables, but with repetition. 2) Loading The plasma source antenna 30 can be matched to the impedance of the RF generator 31 and the connecting coaxial cable 31C by using the conductive, capacitive or inductive load means L. For example, a tap or wiper can be brought into ohmic contact with other generator output impedance locations near 50 ohms or 300 ohms or on the antenna. It is also possible to connect a variable inductance or variable capacitance to the generator output impedance point 50 on the antenna. 3) Tuning circuit and load circuit In FIGS. 4 and 9, the tuning means T is preferably integrated with the plasma source antenna 30 to synchronize the plasma source with resonance.
Is provided. In addition, the integrated load means L changes the input impedance of the plasma source antenna 30 to the associated oscillator 31.
(Or used to match the output impedance of the transmission line 31C). 4, in one aspect, the tuning means T is a variable capacitance electrically connected between one end of the antenna 30 and RF ground.

As shown in FIG. 5, and in another aspect, the load means L can be a variable capacitance electrically connected between one end of the antenna and RF ground. The load means may also be a variable position tap 60 that applies RF input power to the antenna. See FIG. 6. In the preferred combination shown in FIG. 7, the tuning means T is a variable capacitance electrically connected between one end of the antenna 30 and RF ground and the load means L is electrically connected between the other end of the antenna and RF ground. Is another variable capacitance connected to. In this configuration, the RF input power can be applied to the antenna via a tap, ie along the antenna or via a tap provided at either end thereof. See FIG. 8.
Also, the RF power input connection 66 can be placed at the connection between the load variable capacitance L and the end of the antenna 30, as shown in FIG. 6. Source / Bias Process Control The present invention also provides a high silicon dioxide etch rate with a sufficiently high bias voltage, and by periodically pulsing the bias voltage to a low value, the etch rate of materials such as silicon dioxide. , Including the discovery that the etch selectivity of silicon dioxide is increased over materials such as silicon. 1) Pulse / modulation bias-of etching rate and selectivity
Enhanced In FIG. 10, the etch rate of materials such as silicon dioxide SiO ₂ typically increases with increasing bias voltage. Therefore, increasing the bias voltage increases the oxide etching rate. Unfortunately, however, the etch rate of related materials in integrated circuit structures such as silicon / polysilicon also increases with bias voltage. Therefore, with a bias voltage of sufficient magnitude to provide a very high silicon dioxide etch rate, the silicon etch rate will be too high (although somewhat lower than the oxide etch rate) and the selectivity will be reduced. . When etching silicon dioxide, a combination of a high oxide etch rate characteristic of a high DC bias voltage V _h and a relatively low silicon etch rate characteristic of a low DC bias voltage V ₁ , and thus a high oxide selectivity. It is quite clear that it is highly desirable to have a degree.

Here, the DC bias voltage waveform 70 of FIG.
Refer to V_hAnd V₁To combine the characteristics of
The seemingly contradictory purpose shown in the previous paragraph is actually high.
Baseline DC bias voltage V_hAnd use this voltage
Low value V₁To periodically pulse or modulate
Therefore, polymer formation etching treatment (materials such as silicon
Smell to form an etching-inhibiting polymer on top of)
Will be achieved. V₁Silicon etching and silicon deposition
Crossing point / voltage between 68 (Fig. 10) and below and oxide
The intersection / voltage is 69 or more. As a result, the protective polymer
Is deposited on silicon, and high-speed etching voltage V_hReturn to
Suppresses etching during_hOxide ed in
Vapor deposition on the oxides would add significant inhibition to the etching.
It does not occur, or even if it does, it is insufficient. Preferably V
₁Features deposition on polysilicon, but at least
A slight etch of oxide. Implementation of this invention
In the example, the parameter V_h(High DC bias voltage
Pressure), V₁(Low DC bias voltage), P_w(Low voltage V
₁Pulse width), and P_rp(Low voltage pulse and high voltage pulse
Pulse repetition rate or combined width)
-400V, -225V, about 0.1 seconds, and about 1 respectively
Seconds. 2)2 frequency bias An alternative method is to use the DC bias voltage waveform 71 of FIG.
Indicate. Basic bias voltage due to relatively low frequency voltage fluctuation
It is superimposed on the frequency. For example, the low frequency T ₂<25
KHz (preferably 5-10 KHz) as a base high frequency T₁
Superposed or mixed at <2 MHz. Silicon oxide
It is an insulator. Silicon / polysilicon is usually very thin
It has only a unique oxide layer. Therefore, low frequency
Number T₂DC bias voltage fluctuations of
Absent. This is because it is charged. Only
However, basically uninsulated polysilicon isLowfrequency
Number T₂Cycle low voltage excursion 72
(V₁), By forming a protective layer in
The low frequency T in a manner similar to₂React to. This low frequency
The number of layers formedhighFrequency T₁Cycle fluctuating high
Disables etching during voltage excursion 73
It As mentioned earlier, the insulating properties of silicon dioxide
T₂Etching suppressed deposition during low voltage excursions of
And the oxide etching causes T₁Cycle high voltage
It progresses unrestrained during the partial period.

That is, the high voltage excursion 7 of the high frequency cycle T ₁ in which the protective layer is formed on the silicon during the low voltage excursion 72 of the low frequency cycle T _{2 and} the oxide is rapidly etched without suppressing the deposition.
Suppress the silicon etching in 3. As a result, a fast etching rate for silicon oxide, a relatively low etching rate for silicon and a high etching selectivity for oxides are obtained, as in the pulse / modulation method described above. It should be noted that the pulse / modulation method is currently preferred by the two frequency bias method. This is because the former can perform precise control. 7. Load capacitor L at the Faraday shield input end, tuning capacitor T at the other end,
Also consider a typical antenna 30 coil configuration with a relatively low voltage at the input and a much higher voltage at the other end. The bottom winding of the coil near ground is connected to the low voltage RF input. Normally, the plasma is exposed to the electrostatic field of a relatively high voltage winding near the tuning end that initiates the plasma by electrostatically initiating decomposition of the gas. Following initiation of decomposition, the coupling to the plasma becomes predominantly electromagnetic or inductive. Such operation is well known. Under steady-state conditions, both electrostatic and electromagnetic inductive coupling usually exist. Although electromagnetic coupling is dominant, some types of processing are sensitive to electrostatic fields. For example, polysilicon etching requires low energy particles and low energy bombardment to prevent oxide etching.

Referring to FIGS. 1 and 15, a Faraday shield 45 may optionally be incorporated in the chamber of the present invention to reduce the steady state electrostatic field. The structure in the embodiment shown in FIG. 15 (A) is a "single" Faraday, consisting of a grounded spaced axially extending post or bar or other cylindrical array surrounding the dome wall 17W and antenna 30. This is called the shield 45S. This single shield can take many forms, from large spaced configurations to configurations where the spacing between each portion of the shield is very small.

FIG. 15B shows a so-called "all" Faraday shield 45F consisting of a pair of concentric shields spaced so that one bar overlaps the other. This eliminates the line of sight of the electric field lines through the shield,
This shunts the electrostatic field. Faraday shield 4
Although various configurations are possible for 5S and 45F,
The presently preferred configuration is the open-ended cylindrical configuration with the outwardly flanged conductive end shown in vertical section in FIG. Field surfaces 46, 47, 48 with single or double-walled openings are the top, inner surface (source) of the antenna
And extends around the bottom surface and the ground side 49 (which may not be open here) is located outside the antenna. According to this configuration, the axial magnetic component of the electromagnetic wave from the antenna 30 generates the plasma 16 in the antenna 30.
It is possible to induce a closed loop electric field parallel to the plane of. However, the shield 45 capacitively shunts the direct electric field component to ground and prevents the direct electric field component of the high frequency electromagnetic energy from coupling to the plasma. Shield 45
Using, the voltage varying along the antenna 30 couples to the plasma according to the Maxwell equation of capacitive displacement current coupling. As a result, the plasma density and the substrate 5
Inhomogeneities and gradients are induced in the energy of the particles, which may cause non-uniformity of processing and high-energy charged particles.
According to Faraday's law in integral form, a changing magnetic field through a surface must produce a closed electric field on that surface. The Maxwell equation, which expresses this phenomenon in a differential form, shows that the induced electric field rotation is proportional to the negative time rate of the magnetic field change. For sinusoidal excitation, the induced E is proportional to the varying B field emission frequency and its peak amplitude.

That is, the discontinuous, slitted or split Faraday shield minimizes the short circuit effect of the shield on the changing electromagnetic field from the coil, reduces eddy current loss and reduces the high frequency axial magnetic field. Allows coupling to the plasma and induces a closed loop electric field that creates the plasma, but disables the direct coupling of this field (which changes on the antenna) to the plasma, thereby causing plasma inhomogeneity and high energy. Eliminate losses such as process non-uniformity for charged particles. 8. Limiting and Enhancing Magnetic Field 1) Limiting In order to reduce the loss (decrease in plasma density) at the wall 17W of the cylindrical / dome plasma source, a magnetic device for generating a peripheral annular (shallow) magnetic field is provided. FIG.
In the preferred configuration shown in the horizontal cross-section of Figure 6, this magnetic field is provided by a "bucket" or cylindrical multipole array of axial permanent magnets or electromagnets 76-76 in close proximity, each magnet having its short length. A magnetic field B is formed around the alternating magnetic poles which are magnetized in the direction and closed.
This multipole arrangement produces a multicusp magnetic mirror 77 on the dome wall. The array can also be horizontal ring magnets. Such a magnet reduces the electron loss on the wall 17W,
Improves plasma density and uniformity without exposing the substrate to a magnetic field.

Similarly, permanent magnets or electromagnets are provided around the lower chamber 16A, usually N--S--N--S ...
It is also possible to arrange in a multipole array of alternating N-S configuration to generate multiple cusp magnetic mirrors on the chamber wall.
These magnets can be vertical bar magnets, and preferably, for example horizontal ring magnets. Such magnets can be used to reduce electron losses in the walls, thereby improving plasma density and uniformity without exposing the substrate to magnetic fields. Further, a radial array of magnets can be mounted on the top of the dome of the cylindrical plasma source or on the top plate 17T to reduce top loss.

Referring to FIG. 3, the substrate processing area 1
The plasma in 6B can be generated or decoupled from the plasma in plasma source region 16A by placing a substantially planar magnet grid at the bottom of the plasma source region and the top of the processing region. This magnetic grid is similar to the above-mentioned bucket configuration, but it is close to the parallel magnetic bars 7.
8 to 78, which is NS magnetized in its short direction so that the magnetic field lines exit from one bar and terminate at the next bar to provide a -NS-NS-NS- magnetic field. The resulting substantially planar magnetic filter 79 on the opening 15 of the plasma source limits the magnetic field to this plane and plate region and does not penetrate either the plasma source or the substrate region.

From the relationship of F = qV × B, the high energy / fast electrons of the plasma source are bent or repelled to a higher degree than the ions by this magnetic field 79 and cannot penetrate into the substrate process area. As a result, the density of high-energy electrons in the process region 16B decreases, and the plasma density in the same region decreases. The process area and the plasma source area are decoupled.

The magnetic limiting method with this filter is particularly effective for decoupling the plasma region of small systems. That is, for example, it provides a high group density without increasing the ion density on the substrate, while maintaining compactness. In one preferred configuration, the filter magnetic restriction is implemented using a machined aluminum plate with hollow bars for air cooling and elongated magnets.

The bucket magnetic limiting arrangement and the filter magnetic limiting arrangement can also be used together. 2) Augmentation As mentioned above, one or more (preferably at least two) permanent magnets or electromagnets 8 shown in FIG.
1-81 to use the horizontal plane of the antenna coil and high frequency RF
It is possible to make a right angle to both of the electric fields induced by the radiating antenna and to form an approximately axial electrostatic field through them. Preferably, one of three types of magnetic fields is used, namely a uniform magnetic field, a divergent magnetic field or a magnetic mirror, as described below.

Referring to FIG. 14A, the magnet 8
A homogeneous axial uniform magnetic field 82 applied perpendicularly to the substrate 5 by 1-81 limits the movement of electrons to the wall. Since the ions cannot follow the high-frequency magnetic field fluctuation, the ions gather in the plasma on the substrate due to the shortage of electrons. For maximum efficiency, this or other static magnetic field can be tuned to resonance with high frequency fields. Ω = 2πF
= Be / m, where B is the magnetic flux density and e and m are the electron charge and mass, respectively.

FIG. 14 schematically shows the divergent magnetic field 83 in the axial direction.
It shows in (B). By storing the magnetic moment, the axial gradient of the magnetic field transforms the circular translational energy into axial translational energy,
It tries to drive electrons and ions from a strong magnetic region to a weaker magnetic region. The divergent magnetic field can be used to push electrons and ions out of the plasma generation region and concentrate the plasma on the substrate.

Referring to FIGS. 14C and 14D, the inflating magnetic field or the assisting magnetic field 84 (see FIG. 15) will be described.
(C)) and a cusp-shaped or opposing magnetic field 85 (FIG. 15).
(D)) is shown. The effect of each of these so-called "magnetic mirror" fields is similar to that of an axially divergent magnetic field. The charged particles are driven from a relatively strong magnetic field region to a relatively weak central region.

By selectively arranging the magnets and selecting and varying the strength of the magnetic field provided by the single or multiple magnets, the associated uniform diverging or mirror field is controlled. , Increase the plasma density of the substrate. In the case of a magnetic mirror field, the preferred substrate location for maximum plasma density enhancement is at or near the overhang or cusp, which maximizes plasma density enhancement.

In some cases, it is desired to use an axial magnetic field for the volume of the antenna to improve plasma generation but to eliminate the magnetic field on the substrate. An annular disk made of a highly permeable material (such as nickel or steel for soft iron) can be interposed on the flat lower substrate 5 of the magnet and antenna. 3. Extraction Ions and electrons can be extracted toward the substrate using an appropriate magnetic field. 9. Control System The following definitions are used for the control system shown in FIG.

Psp Power set point Pf Positive power (measured by directional coupler placed in power supply) Pr Reflected power (measured by directional coupler placed in power supply) | Z | Impedance magnitude <phi Impedance phase Tsp tuning set point Lsp load set point Tfb tuning feedback (measured value) Lfb load feedback (measured value) FIG. 16 is a block diagram of a typical system for controlling various components including a power supply. Here, the system controller 86 is interfaced with the antenna power supply 31, the impedance bridge 87, the antenna 30, the bias power supply 31, the impedance bridge 88, the matching network 43, and the cathode 32. Selected processing parameters for ion flux density and ion energy, antenna power and DC bias are provided as inputs to controller 86. The controller 86 also controls gas flow, chamber pressure, electrode or substrate temperature, chamber temperature, and other parameters. The controller 86 is a Tsp connected to the antenna 30.
It is possible to set the initial tuning 1 and load of the conditions by emitting a signal to _one line and Lsp ₁ line. The controller can also set initial tuning ₂ and load ₂ conditions by issuing signals on the Tsp ₂ and Lsp ₂ lines connected to the matching network 43. Generally, these conditions are selected to optimize the initiation of the plasma (gas breakdown).
Power may first be applied to either antenna 30 or cathode 32, or both at the same time. The controller 86 issues power set points on the Psp ₁ line to the antenna power supply 31 and on the Psp ₂ line to the bias power supply 42 either simultaneously or sequentially (which may be the first).

Electron avalanche breakdown occurs rapidly in gas,
Plasma is generated. The controller 86 uses the antenna 3
Forward power between 0 and (Pf₁) And reflected power (Pr₁)
And the forward power (Pf₂) And
And reflected power (Pr₂) Is monitored. DC bias (cathode
-Anode DC voltage) is also shown to controller 86
To be monitored. The controller 86 is (a) forward power
Pf₁And reflected power Pr ₁Or (b) impedance
Size ｜ Z₁| And impedance phase <phi₁Nozu
Line Tsp based on it₁And Lsp₁Set point above
Coil tuning by emitting₁And load₁Parame
Adjust the data. The bridge 87 is connected to the controller 86.
It gives information on the magnitude and phase angle of impedance. Ante
30 is reflected power Pr₁Is almost zero, the
Pedance (size and phase | Z₁| <Phi) is the coil current
Match when the source output impedance is complex conjugate
is doing. (Zero reflected power condition and conjugate impedance condition
Cases occur at the same time. Therefore, the reflected power is minimized.
Or the impedance is matched.
And the result is the same. Alternatively, VSWR (voltage
The standing wave ratio) or the reflection coefficient is minimized. ) Contro
-86 is (a) forward power Pf₂And reflected power Pr₂Ah
Ruiha (b) Impedance magnitude | Z₂｜ and Impi
Phase of dance <phi₂Line Tsp based on any of
₂And Lsp₂By issuing a set point above
Do 32 and matching network tuning₂And load₂Parame
Adjust the data. The bridge 88 is connected to the controller 86.
Size of Impedance ｜ Z₂｜ and phase <phi₂Information of
Get Similar to the matching of the antenna, the reflected power Pr₂But
When it is almost zero, the impedance (magnitude and
Phase ｜ Z₂｜ ＜ phi₂) Is the bias power supply 504 output impedance
Matching occurs when it is the complex conjugate of dance. Direct current
Bias is monitored by controller 86. Con
The tracker 86 changes the output power of the bias power source.
Obtain the desired measured DC bias. Controller 86 is direct current
Subtract the DC bias measurement from the desired bias value
It When the difference is negative, the output of the bias power supply 42 is
Can be raised. If the difference is positive, the bias power output
Power (the higher the output of the bias power supply, the more
Ias grows in the negative direction. ) According to this method
Proportional control, proportional integral control, or proportional integral derivative control
Alternatively, other controls can be used.

Further, instead of this embodiment in which the output of the bias power source 42 is adjusted to maintain a constant DC bias,
A constant bias power supply output can also be used. In addition to the DC bias servo matching technique described above, automatic tuning can also be accomplished by servoing to peak-to-peak RF voltage. This latter method may be useful, for example, in certain etching processes that require sufficient conductive area at the cathode and anode to provide current for driving the instrument. Using polymer coating techniques, these conductive regions are passivated, preventing current from saturating the instrument and providing a valid reading. In contrast thereto, the peak-to-peak RF voltage method is unaffected at the low frequencies associated with the particularly preferred frequency range. The measurements can be taken with the matching network 43 closer to the chamber rather than the cathode.

The controller 86 can be a central controller or a distributed system of controllers. The turn-on / turn-off sequence is important to obtain a sensitive substrate device structure. It is generally preferred to turn on the plasma source first and turn it off last. This is because this method can minimize changes in the sheath voltage. Depending on the application, it may be better to turn on the bias first. 10. Transmission Line Structure Referenced Patent Application As described in detail in US Pat. No. 559,947, proper coaxial / transmission line design involves feeding through a low characteristic impedance, short transmission from the matching network to the wafer. A return path along the line and the transmission line is required. This design condition isolates the cathode 32C, the concentric annular conductor 320, and the cathode surrounding the cathode 32C from the concentric annular conductor 320, and replaces the potentially yielding process gas with a non-porous low-loss insulator 3.
2I is satisfied by the integrated transmission line structure 32 shown in FIG. For example, Teflon ^™ and quartz materials are suitable because they have high dielectric strength, low relative permittivity, and low loss. The input side of this structure is connected to the matching network in the manner described below. The insulated cathode 32C and outer conductor 320 connect the matching network 43 and the plasma 16
To provide separate current paths between. One reversible current path runs from the matching network along the circumference of the cathode 32C to the plasma sheath on the surface of the chamber (electrode). Second
Reversible path from the plasma 16 along the inner portion of the top of the chamber habit 12 and then along the conductive exhaust manifold screen 29 through the interior of the outer conductor 320 to the matching network. It should be noted that the exhaust manifold screen 29 is part of the uniform radial gas pumping system and the return path for the RF current.

During the application of AC energy, the direction of the RF current path alternates between the direction shown and the opposite direction. Since the transmission line structure 32 is a coaxial cable type structure, and more specifically because the internal impedance of the cathode 32C is high (compared to the outside thereof), the RF current will be in the form of a coaxial transmission line to the outside and outside of the cathode 32C. It flows to the inner surface of the conductor 320. The skin effect concentrates the RF current near the surface of the transmission line, reducing the effective cross section of the current path. Using a large substrate, eg, 4-8 inches in diameter, and a corresponding large diameter cathode 32C and large diameter outer conductor 320, results in a large effective area and low impedance currents flowing through this transmission line structure. Also, if the coaxial transmission line structure 32 is terminated with a pure resistance equal to its characteristic impedance Z ₀ , the matching network will have a constant impedance Z ₀ independent of the length of the transmission line. However, in reality this is not the case. This is because the plasma operates over a range of pressures and powers and consists of various gases that collectively change the load impedance Z ₁ that the plasma presents at the end of the transmission line 32. Load Z ₁ is not ideal (ie not lossless)
Since it is not matched to the transmission line 32, the standing waves on the transmission line increase resistance losses, dielectric losses and other losses between the transmission line and the matching network. The matching network 43 can be used to eliminate standing waves and losses from the input of the matching network to the amplifier or power supply 42, while the matching network, the transmission line 32, and the plasma in the chamber can A resonance system that increases resistance loss, dielectric loss, and other losses between the two 43 is formed. That is, the load impedance Z ₁ does not match the loss, but the loss is minimized when Z ₁ ≈Z ₀ .

In order to eliminate loss due to load mismatch, the coaxial transmission line structure 32 has a characteristic impedance Z most suitable for the range of load impedance associated with plasma operation.
Designed to have ₀ . Generally, for materials considered above operating parameters (eg, bias frequency range of about 0.3-3 MHz), the series equivalent RC load impedance Z ₁ provided by the plasma to the transmission line is from about 10 ohms. It consists of a resistance in the range of 100 ohms and a capacitance in the range of about 50 picofarads to about 400 picofarads. Therefore, the optimum value of the transmission line characteristic impedance Z ₀ is selected in the middle of the load impedance range, that is, about 30 to 50 ohms.

The transmission line 32 must be very short to avoid distortion of the plasma impedance seen by the matching network. Preferably, the transmission line is much shorter than a quarter wavelength (λ / 4). More preferably about (0.05
-0.1) λ. Further, in order to perform power coupling more efficiently, the inner diameter (cross-sectional dimension) of the return conductor 320 should not be significantly larger than the outer diameter (cross-sectional dimension) of the central conductor 32C.

That is, this chamber contains a transmission line structure for coupling the electric power from the matching network 31 to the plasma 33. It is preferable that this transmission line structure is (1) very short or approximately equal to a half wavelength compared to a quarter wavelength at a target frequency in order to prevent deformation of plasma impedance, and (2) plasma An outer conductor track having a characteristic impedance Z ₀ selected to suppress losses due to the presence of standing waves on the lines between the matching networks, and (3) the cross-sectional dimension is not much larger than the cross-sectional dimension of the central conductor. To use. 11. Chamber Temperature Control A temperature control function that can be incorporated into the reactor chamber system 10 includes a fluid transfer to maintain the internal or external temperature of the intake manifold above or below a certain value or within a certain range. Use of a heat transfer medium, resistance heating of the cathode 32C, fluid heat transfer or cooling of the cathode 32C, use of a gas heat transfer medium between the substrate 15 and the cathode 32C, chamber walls 12-14 or dome 17.
Include, but are not limited to, the use of a fluid heat transfer medium to heat or cool the substrate, and mechanical or electrostatic means for constraining the substrate 15 to the cathode 32C. Such features are co-assigned as referenced 19
U.S. Pat. No. 4,872,947 dated October 10, 1989 and co-assigned U.S. Pat. No. 4,872,27, June 27,1989.
No. 842,683.

For example, a recirculation closed loop heat exchanger 90 may be used to flow a fluid, preferably a dielectric fluid, through the substrate support / cathode 32C block and pedestal as outlined in channel 91 to provide substrate support. The body can be cooled (or heated). For silicon oxide etching, a dielectric fluid temperature of, for example, -40 ° C is used. As mentioned above, heat transfer between the substrate 5 and the substrate support 32 is enhanced by an inert gas heat transfer medium such as helium at the substrate-support interface.

The chamber walls and dome can be heated or cooled by convection of air (blowing air) and / or a dielectric fluid heat exchanger. For example, the closed circuit heat exchanger 92 recirculates the dielectric fluid along the passage 93 to the sidewall of the chamber at a controlled temperature from heating to cooling, for example in the range of + 120 ° C to -150 ° C. Similarly, dome sidewall 17W and top wall 17T can be heated or cooled by heat exchangers 94, 96 that recirculate fluid along passages 95, 97.

In an alternative dielectric thermal control system,
The antenna coil 30 is placed between the double walls 17W of the dome, immersed in the recirculating dielectric fluid. In another alternative dome dielectric fluid thermal control method, the coil of antenna 30 is enclosed in high temperature plastic or Teflon ^™ ,
A heat transfer thermal grease is applied between the enclosed antenna and the dome, and the hollow coil is heated or cooled by flowing a dielectric fluid through the coil. RF
Since energy is also added to the coil and in close proximity to the plasma, dielectric oils, in addition to their high specific heat capacity and density for efficient heat transfer at acceptable flow rates,
It must have a good boiling point with good dielectric and insulating properties. A suitable dielectric fluid is Siltherm from DuPont. 12. Three Electrode Configuration Referring to FIG. 1, in the presently preferred embodiment, the chamber incorporates a unique three electrode configuration that allows for new process control and improvements. This configuration consists of a cathode (preferably substrate support electrode 32), an anode (preferably chamber side walls and bottom wall) and a top electrode, the top electrode being the top plate 17T (or including) of the dome from the top electrode. Become. As shown in FIG. 1, the top electrode may be floating, grounded, or connected to an RF power source 40. The top electrode includes various configurations and can be constructed of various materials. That is, it is made of a conductive material (preferably aluminum), a dielectric-coated material such as anodized aluminum, silicon or a silicon-containing conductive material such as an aluminum-silicon alloy, or a sacrificial silicon member 17S such as a silicon wafer. Including but not limited to a silicon substrate. 1) Grounded third electrode Grounded top plate 17T enhances the ground reference plane of the bias voltage (relative to the conventional reference provided by wall 12) so that plasma source 16A to process region 16B It enhances ion extraction and thus increases process rate (etch rate, etc.). In addition, the grounded top plate improves the coupling of the plasma (generated by the plasma source) with the substrate. 2) Biased Third Electrode When using a RF biased third electrode in combination with the supply of free silicon (using an electrode containing or covered by a silicon-containing member) to a source plasma. , Various process characteristics including etching rate and selectivity are improved. Assisted by the strong dissociation properties of the source plasma, silicon enters the gas phase and combines / removes with free fluorine. (Due to the dissociative properties of the source plasma, the use of fluorine-containing gas chemistries, for example in oxide etching, provides high concentrations. This increases the etch rate for oxides but also for related substrate materials such as polysilicon. , Thus reducing the selectivity of the oxide to polysilicon.) Removal of fluoride ions by free silicon forms a carbon-rich polymer. As a result, the oxide etch rate is increased, the selectivity of the oxide to polysilicon is increased, and the anisotropy and vertical profile of the oxide etch is enhanced. In addition, free silicon affects the polymerization reaction, forming a carbon-rich polymer, which is easily etched in the presence of oxygen to etch the oxygen-containing layer, but in the absence of oxygen. For example, when the openings reach a substrate such as an oxygen free layer or polysilicon, the suppression is increased and the selectivity of the oxide is increased with respect to the oxygen free substrate. 13. Process example An example of a process advantageously achieved in the reactor of the present invention is as follows.

Example 1. Etching Polysilicon on Silicon Oxide Polysilicon on top of silicon oxide on a silicon wafer is treated with 50 cc of chlorine (Cl ₂ ) at a pressure ranging from about 2 mTorr to about 20 mTorr in a three electrode chamber of the present invention. The etchant gas flow rate (manifold G1 only) was done using 1500 watts of source power, a 20 volt bias voltage, and a grounded top electrode (no silicon). As a result, a polysilicon etch rate of 3500-4000 Å / min, a vertical etch profile, and a polysilicon selectivity of 100: 1 or higher for oxide were obtained.

Example 2. Silicon Oxide Deposition Two-step bias sputter deposition of silicon dioxide into a high aspect ratio opening formed in a silicon oxide layer on a silicon wafer is performed in a three-electrode chamber at a pressure ranging from about 2 mTorr to about 10 mTorr (both steps ),
Gas flow rate of about 200cc of argon / 90cc of oxygen / 45cc of silane (both steps are manifold G1 only), 20
Performed using a source power of 00 watts (both steps), a top electrode grounded (both steps), a bias voltage of about -20 volts (first step) and about 100-200 volts (second step). . As a result, vapor deposition of 7500 Å / min or more was obtained in the first step (without sputtering), and pure oxide vapor deposition (profile-controlled sputtering vapor deposition) of about 4000-5000 Å / min was obtained in the second step. The upper corners of the opening were machined by argon sputtering, followed by filling the opening with void-free silicon dioxide to planarize the silicon oxide layer. This filling and planarization can be performed continuously in the same vapor deposition chamber of the present invention.

A significant challenge in semiconductor fabrication is when the underlying layer is polysilicon or other oxygen free material.
Etching a selected thickness of silicon dioxide. Although the exposed silicon is hardly etched, high selectivity is required because the silicon oxide is etched at a relatively high rate. However, it is known to add an etching gas such as CHF ₃ to a fluoride source to create a polymeric coating on the substrate, as the two materials etch at approximately the same rate when exposed to plasma. is there. This creates a passivated coating on the polysilicon, although the silicon oxide to be etched is continuous. However, the formation of polymer layers on polysilicon makes etching small device geometries difficult. An important concept in this regard is "microloading", which is defined as 1- (etch rate ratio). Here, the etching rate ratio is the ratio of the etching rate in the small shape of the wafer to the etching rate in the large shape of the wafer. Therefore, if the etching process has the desirable property of etching large and small features at the same rate, this microloading is 1-1 / 1 = 0.
become. In processes where small features are etched at a much slower rate than larger features, microloading approaches 1.0.

The difficulty in applying the etching described above is that a relatively large amount of polymer-forming gas must be used in the plasma in order to obtain a high etching selectivity, but the polymer layer is much more than zero. To produce large microloading. Usually about 0.
For a microloading of 1, one cannot expect a selectivity ratio greater than 10: 1. However,
30: 1 or 4 with microloading close to 0
Many applications require a selectivity ratio of about 0: 1. 2. Use of Silicon in the Plasma Region For high density plasma sources, one of the isolation products that etches polysilicon is fluorine. Silicon can be used to remove free fluorine radicals from the plasma source region. Silicon can be in the form of a coating on the third electrode 17T or on the inner wall 17W of the chamber. If the sacrificial silicon is on the wall, the thickness of the silicon becomes a problem with the frequency at which RF energy is delivered to the plasma from the antenna 30. These parameters are
It must be chosen to ensure that sufficient energy is electromagnetically coupled through the chamber walls. If silicon is included in the third electrode 17T, the thickness of silicon is not so important. In any case, when silicon is utilized to remove free fluorine from the plasma source region, it forms volatile compounds that are easily removed from the chamber.

The silicon scavenger material is itself coated with polymer during the etching process. This polymer can either be removed by elevated temperature heating or by electrically biasing the silicon to increase the bombardment of the silicon surface so that the polymer is sputtered from the surface, thereby freeing silicon. Exposed again. 3. The silicon oxide silicon oxide ene quenching poly on silicon on polysilicon, a pressure of about 2 mTorr with 3 electrodes in a chamber of about 30 mTorr of the invention, CHF _3, 30-60sccm / CO or CO _2, 6-18Sc
cm / Ar, 100-200 sccm (manifold G1 only) gas chemistry flow rate, 2000 watts power supply, 200
A bias voltage of Volts, top electrode 17T and a silicon disk 17S biased with 2 MHz, 1000 watts of RF energy attached to them were used. Silicon oxide was etched at a rate of 8000 Å / min and the oxide selectivity for the polymer was 50: 1. Also, the silicon-containing body can be reinforced by a silica coating on the quartz dome wall 17W. 4. Oxygen-Containing Layer Etching on Oxygen-Free Substrates A series of etching processes were performed by the reactor of the present invention for etching oxygen-containing layers such as silicon oxide on various oxygen-free substrates. After patterning the oxide layer using conventional photolithographic techniques, etching with C ₂ F ₆ was performed in the reactor of the present invention using a grounded third silicon electrode. The results are summarized in Table 1 below.

Table 1 Examples Thickness of silicon oxide Substrate selectivity 4 5000-10000Å WSi 25: 1 6 PECVD Si ₃ N ₄ 15: 1 7 5000-10000Å LPCVD Si ₃ N ₄ 15: 1 8 5000-20000Å TiN / Al * 15: 1 9 5000-20000Å Al 30: 1 10 5000Å Single crystal silicon 30: 1 * 2-3000Å Another series of etchings using CF ₄ is BPSG (Boro).
-Phosph-Silicate-Glass) was performed under the same conditions except that the oxygen-containing layer was replaced. The results are shown in Table 2 below.
Is summarized in.

Table 2Example Silicon oxide thickness substrate Selectivity 11 5000-10000Å WSi 30: 1 12 5000-25000Å p + -doped single crystal 30: 1 silicon 13 5000-25000Å p + -doped single crystal 30: 1 Silicon selectivity is gas flow, power supply and silicon plate Change conditions
Can be adjusted by special oxidation on special substrate
The selectivity of silicon or glass can be made appropriate.
The present invention using a fluorine ion silicon scavenger
In the reactor, selectivities up to 100: 1 can be achieved
It14. Other features 1)Plasma control A feature of this invention is that it automatically changes the "lower" power.
To maintain a constant cathode (substrate) sheath voltage
It Low pressure (<50 in highly asymmetric systems
At 0 millitorr, the DC bias measured at the cathode is
It is an approximate value of the cathode sheath voltage. Lower power is automatic
Can be changed to maintain a constant DC bias
It The lower power has almost no effect on the plasma density or ion current density.
It has no effect. The top or antenna power is plasma-tight
Has a very strong effect on the degree and ion flow density,
The effect on the sheath voltage is very small. According to
The upper power to determine the plasma density and ion current density.
And the lower power is used to determine the cathode sheath voltage.
Is desirable. 2)Differential bias Instead of biasing the substrate 5 to earth,
And as shown by the dotted connection 50 in FIG.
The work piece 43 and the top plate 17T from the ground.
You can also use them as references. Explain Figure 2
When exposed, the top plate is the voltage between the top plate and the substrate.
Pressure V_T-SSIs the voltage V between the top plate and the wall 12_TWLarge of
The voltage V between the substrate and the wall at about twice the size_SS-WAbout the size of
It is differentially driven and balanced so that it doubles. This
Balanced differential drive of plasma and wall interaction
Between the plasma source region 16A and the substrate region 16B
Increase the interaction of, ion extraction. 3)Alternative configuration The plasma reactor system of the present invention is shown in FIG.
(Vertical). Substrate 5 on top of electrode 32 (cathode)
Yes, the antenna 30 surrounds the dome 17 above the electrodes
I'm out. For convenience, the power supplied to the antenna 30 is
Antenna "or" plasma source "or" top "power
The power supplied to the electrode / cathode 32 is
We have called it "as" or "bottom" power.
The names and names are for convenience only and the system
The system is inverted, that is, the antenna is placed on this electrode 32
It can be placed below the pole and configured, or modified.
Arrange in other ways without adding (eg horizontally
Can be placed). That is, this reactor system
Works regardless of orientation. Plasma in inverted configuration
Is generated by the antenna 30 and is conveyed upward to
Toward the substrate 5 located above the antenna by the method described in
U In other words, the transport of active species depends on diffusion and bulk flow.
Occurs. Or optionally have an axial slope
Generated with the help of a magnetic field. This process depends on gravity
And therefore is relatively insensitive to direction. Flipped
The orientation is, for example, the plasma generation region in the gas phase, or
Minimizes the possibility that particles formed on the surface will fall onto the substrate.
It is useful in that it can be made to a small limit. Then by gravity
Only the smallest of these particles is the gravitational potential
Rise against the gradient towards the substrate surface. 4)High and low pressure operation and variable spacing The chamber design of the present invention is designed for both high pressure and low pressure operation.
Is effective for. Substrate supporting cathode 32C and antenna
The spacing d between the faces of the lower coil or winding is high pressure operation
And can be adapted for both low pressure operation. for example
Suitable for high pressure operation of 500 mtorr-50 mtorr.
A spacing d of less than about 5 cm is used for 0.1 mtorr
5 cm for low pressure operation below -500 mtorr
Larger spacings d are preferred. Shown in the chamber
It is also possible to use a fixed spacing d such that
Replaceable or like a nested upper chamber section
Variable spacing designs can also be used. Reactor system 1
0 is the high pressure of materials such as silicon oxide and silicon nitride and
Low pressure deposition, silicon dioxide, silicon nitride, silicon,
Low materials such as polysilicon, glass and aluminum
Pressure anisotropic reactive ion etching, high pressure plastic for such materials
Includes Zuma etching and planarization of substrate topography
CVD including co-deposition and etchback of such materials
It is effective for faceting and other processing. Reactor
These treatments and processes that can use the stem 10
For other processing of VHF / UHF PLASM
A PROCESS FOR USE IN FORMING INTEGRATED CIRCUIT ST
RUCTURES ON SEMICONDUCTOR WAFARS (on a semiconductor wafer
VHF / UHF plasma plates used to form integrated circuits
Collins and others dated July 31, 1990
US patent application Ser. No. 07 / 560,530 (AMAT file
Le No. 151-2). 15.Device example An embodiment of the system of the present invention includes a plasma source structure shown in FIG.
Configuration and antenna configuration are included. 5 inch high quartz
The plasma source chamber 17 has a diameter of 12 inches.
It 2MHz, diameter 13 inches, height 4 inches, 13 rolls
Ile antenna at both ends (with variable capacitor L grounded
0.25 inch (below) from the ground plane (at T)
It terminates at intervals and surrounds the plasma source. Anti
Variable load matching variable capacitor L (10-3000 picof
Supplied by Arad variable capacitor, rated 5kV)
There is. In addition, the capacitive tuning to the resonance of the antenna is
Sensor T (5-100 picofarads, 15kV rating)
It is provided by. 2 kW 2MHz source RF
When operating with energy, 2 inches downstream (plasma
A plasma is provided that extends to the wafer (under the source).
This is 1-2X10 ¹²/cm³Plasma density and substrate
10-15mA / cm downstream²Provides ion saturation current density of
To do. Placed on the support electrode about 2 inches below (downstream) the antenna
2MHz, 600W applied to the placed 5 inch substrate
The bottom of the battery or bias is a 200 volt cathode
Provides the sheath voltage.

It will be apparent to those skilled in the art that the present invention is not limited to the use of domes. Rather, the invention is applicable to almost any configuration having a plasma source region and a process region. This includes, for example, a "stepped" dome chamber configuration as shown, or a non-stepped configuration where the plasma source region and the process region or chamber portions have approximately the same cross section.

As mentioned above, the above-described reactor embodying the present invention is a low pressure chemical vapor deposition (CVD) including reactive ion etching (RIE), high pressure plasma etching, sputter facet deposition and planarization and high pressure conformal isotropic. Providing unique effects for various plasma processing such as chemical CVD. Applications include, but are not limited to, sputter etching, ion beam etching, or as an electron, an ion or active neutral plasma source.

Having described the preferred embodiments of the apparatus and process of the present invention, those skilled in the art will be able to readily apply, modify and extend the apparatus and method within the scope of the claims.

[Brief description of drawings]

FIG. 1 is a sectional view of a plasma reactor according to the present invention.

FIG. 2 is a sectional view of the plasma reactor of the present invention.

FIG. 3 is a sectional view of the plasma reactor of the present invention.

FIG. 4 is a diagram showing a tuning circuit.

FIG. 5 is a diagram showing a load circuit.

FIG. 6 is a diagram showing a load circuit to which an RF input is applied.

FIG. 7 is a diagram showing coupling between a tuning circuit and a load circuit.

FIG. 8 is a diagram of another embodiment showing coupling of a tuning circuit and a load circuit.

FIG. 9 is another embodiment diagram showing the coupling between the tuning circuit and the load circuit.

FIG. 10: Etching / deposition rate with respect to silicon oxide and silicon bias voltage

FIG. 11 is a DC bias voltage waveform diagram applied during etching.

FIG. 12 is another diagram of a DC bias voltage waveform applied during etching.

FIG. 13 is a horizontal plane layout view of a magnet array in the dome of the reaction chamber of the present invention.

14 (A) to (D) are views showing magnetic lines of force of various shapes of the system of the present invention.

15 (A)-(B) are diagrams showing an example of a Faraday shield useful in the system of the present invention.

FIG. 16 is a block diagram of a control system of various components in the system of the present invention.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Chan Rong Yang California, United States 95032 Los Gatos Reloj Avenue 16788 (72) Inventor Jerry Yuen Qui Won United States California 94539 Fremont Cougar Sarkle 44994 (72) Inventor Jeffrey Marks United States California 95129 San Jose Cielo Vista Way 4730 (72) Inventor Peter Earl Keswick United States California 94560 Newark Joaquin Marieta Avenue 6371 A (72) Inventor David W. Gruchel United States California 94087 Sunnyvale Robin Way 927

Claims (10)

[Claims] 1. A) comprising a vacuum chamber for generating a plasma, b) supporting a substance to be treated on an electrode in the chamber, c) supplying a fluorine-containing etching gas to the chamber, d) RF energy is electromagnetically coupled to the chamber from an RF power source to generate high density plasma for treating the material; e) capacitively couples RF energy to the chamber through the support electrode; and f) silicon. A plasma etching method comprising applying an ion source to the plasma. 2. The method of claim 1, wherein the silicon source is located in a plasma region of the chamber. 3. The antenna power and the bias power supplied to the supporting electrode can be changed so as to affect the anisotropy, the semi-anisotropic property and the isotropic property.
The method described in. 4. The method according to claim 1, wherein the substance to be treated comprises an oxygen-free material and an oxygen-containing material on the surface of the material. 5. The fluorine-containing gas is CF _4, C ₂ F _6, C ₃ F ₈
5. A method according to claims 1 to 4, characterized in that it is selected from the group consisting of: 6. The substrate is single crystal silicon, polysilicon,
6. The method according to claim 1, wherein the method is selected from the group consisting of silicon nitride, tungsten silicide, titanium nitride and aluminum. 7. The method according to claim 4, wherein the oxygen-containing material is silicon oxide or glass. 8. The method according to claim 1, wherein an inert polymer containing 50% or more of carbon and 40% or less of fluorine is formed on the substrate. 9. The method of claim 1 wherein a carbon-fluorine containing polymer is formed that contains greater than about 50 percent by weight carbon and less than or equal to 40% fluorine by weight. 10. A vacuum chamber for generating a plasma, b) an electrode provided in the chamber for indicating a substance to be treated, and c) means for supplying a fluorine-containing etching gas to the chamber. D) means for electromagnetically coupling RF energy from an RF power source to the chamber to generate a high density plasma for treating the material; and e) capacitively coupling RF energy to the chamber via the support electrode. And f) a silicon ion source that supplies silicon ions to the plasma.