KR20020087477A - Improved cleaning of a plasma processing system silicon roof - Google Patents

Abstract

The present invention provides an apparatus for cleaning a silicon loop of a plasma chamber by etching the loop without substantially damaging the silicon structure. Etching using deionized water to clean the loop and determine the amount of particulate matter in the deionized water used to clean the loop is performed after cleaning the loop. This is done by quantitatively determining how much more than a certain size of particulate material is in the deionized water. If the amount of particulate matter in the deionized water is below a predetermined criterion, the particulate matter deposited on a material such as a silicon wafer processed in the chamber is significantly reduced. The stability of plasma processing over time is improved, with the time between loop cleaning being about 200 hours to nearly 300 hours.

Description

IMPROVED CLEANING OF A PLASMA PROCESSING SYSTEM SILICON ROOF}

Plasma processing systems, and particularly inductively coupled plasma systems, are important for semiconductor processing. Considerably thin, well controlled layers can be formed and shaped. However, the energy induced in the plasma can cause contamination and severe corrosion of the chamber, in particular the roof of the chamber.

Although the use of various types of silicon, such as silicon carbide or polycrystalline silicon, can reduce problems due to corrosion, efforts to remove the contamination present greater challenges. Single crystal materials have also been considered, but polycrystalline materials are preferred in view of all aspects of the materials used, such as cost and mechanical strength. This dielectric loop is also important for an inductively coupled plasma source (IPS) where the RF power from the coil and the coils is connected to the interior of the chamber and to the plasma.

New and faster devices use copper to form contact lines. The process of making copper wire is known as double damascene. However, since copper is not volatile, this process leads to copper contamination, which is widely known as the pollutant in question. It is important that as much contaminant as possible is removed from the chamber during the cleaning operation after using the chamber.

Coatings such as polymer films are often used to further stabilize the surface and can remove large amounts of contamination by removing or etching the polymer film. However, contaminants penetrate the base material and therefore must be removed or suppressed.

Since these contaminants are relatively fixed in the chamber material, it is clear that these contaminants can be removed by removing the chamber surface and, in the instant, the loop material. Preferred methods include removal by silicon carbide (SiC), since silicon carbide consists of silicon and carbon, both of which are advantageous materials for semiconductor processing, and is a very hard material (comparable to diamond). to be. Although this removal causes debris on the surface, it is widely known that some acids, in particular hydrofluoric acid (HF), are quite effective in cleaning such debris. HF has the advantage of strongly etching glass (SiO 2), which is often formed on a silicon surface, such as the surface of a chamber of an IPS having a silicon (Si) loop.

After the surface has been removed and etched, DI water is used to clean residual acid and residual debris, since deionized water, which can be dispersed with water vapor, is an inert material.

While the cleaning method described above is quite effective, particulate material has often been found in chambers in subsequent processing. These sources of particulate material are traceable with reasonable certainty on the chamber surface, and reducing the number and size of particles has been an issue of increasing interest. Although the particle size and number remained high, the effect of the particles was increased because the structure size was reduced by improved techniques. For example, a small particle size, such as 0.2 micron, in a large structure size in processing technology is not so important, although there are more proportionally smaller particles. However, at present in structures less than 0.2 microns, the size and number of small particles are of significant importance.

Particles are known to fall off due to reactive removal of processes inside the chamber, such as ionization deposition processing or reactive ion etching. Reducing particulate matter will likely require less active processing which negatively impacts yield and likelihood. However, this cannot be tolerated.

The need to reduce both particle size and particle number, if not satisfactorily addressed, can hinder future growth in the electronics industry, such as semiconductor chips.

The present invention is directed to the cleaning of the plasma type processing chamber as a complete solution, rather than merely improving a single parameter or problem.

1A illustrates an IPS system with an IPS chamber in accordance with the present invention.

1B shows the energy contained in bonding particulate matter to the chamber loop as a function of the chemical structure of the particle.

2 shows the dispersion of copper (Cu) in a contaminated chamber loop.

FIG. 3 is an enlarged photograph of nearly 100 × of a surface prepared by cleaning with BB (bead blasting) and strong HF with SiC in the prior art. FIG.

FIG. 4 is an enlarged photograph of almost 1000 × of a surface prepared by cleaning with BB (bead blasting) and strong HF with SiC in the prior art. FIG.

5 shows the etch rate of a ternary system of acids when applied to a chamber loop.

FIG. 6 shows particulate matter in the wafer after supersonic agitation with and without the HF cleaning step. FIG.

FIG. 7 is an enlarged photograph of almost 200 × of a silicon surface shaved after a base clean process (BCP).

FIG. 8 is an enlarged photograph of approximately 2000 × with a silicon surface scraped after base cleaning process (BCP).

FIG. 9 is an enlarged photograph of nearly 200 × of a silicon surface shaved after acid chemical polishing (ACP).

FIG. 10 is an enlarged photograph of approximately 2000 × with a silicon surface mowed after acid chemical polishing (ACP).

FIG. 11 illustrates laser particle number (LPC) from silicon loop after BCP operation and BKM # 2 cleaning.

12 illustrates the laser particle number (LPC) from the silicon loop after ACP operation and BKM # 2 cleaning.

FIG. 13 illustrates the effect of the present invention on particle reduction and removal of metal contamination from the chamber loop for both base cleaning and acid chemical polishing processes.

14 shows the effect of the present invention on reducing the number of silicon (Si) fine particles with BCP.

FIG. 15 shows the effect of the present invention on the reduction of the number of silicon (Si) fine particles with ACP.

FIG. 16 shows an example of particulate matter number (PMC) for a 200 mm silicon wafer in accordance with the present invention, the graph of the bottom of the figure showing PMC versus particle size.

FIG. 17 shows an example of particulate matter number (PMC) for a 200 mm silicon wafer according to the prior art, with a graph at the bottom of the figure showing PMC versus particle size.

It is an object of the present invention to provide a method and apparatus for cleaning chambers used to process semiconductor wafers, in particular chambers used for material deposition or reactive ion etching (RIE).

The present invention solves the problem of cleaning the chamber while reducing particulate matter by reducing the activity of removal and etching. In the present invention, a fairly soft removable material such as Teflon or acrylic beads can be used to remove the surface of the contaminated chamber, such as a loop. The softer removal material less damages the grain structure of the silicon-based material used on the chamber surface, thus preventing the degradation of grain integrity. In addition, or alternatively, a fairly neat cleaning or etching material is used after or in place of the removal material. The use of fairly neat acids or bases, such as ternary systems of acetic acid, nitric acid and HF acid, reduces damage to the grain boundaries of silicon-based materials used on the chamber surface, where HF is a heavier bufful @ (Heavily Abuffered @). The cleaning material may be an acid, often referred to as acid chemical polishing (ACP), or may be a base in a base cleaning process (BCP). However, base etching is slower and more selective as a function of the material composition and is very sensitive to certain polycrystalline structures. BCP is also more sensitive to shaving the material to be etched and can shorten the life of the loop to be cleaned. As a result, ACP is good. As a result of the neat processing of the present invention, damage to the silicon-based surface material is reduced, and particles of material are more tightly bonded to the surface. During continuous operation, the corrosion of the surface, such as the surface of the chamber loop, is reduced by improved surface integrity.

A fairly soft material, often in the form of Abead @, may be used in the present invention for removal, sometimes referred to as Abead Blasting @ (BB), but a very soft ternary acid mixture. Pure chemical approach using is preferred. Since the chamber loop material is removed much less violently, the crystal structure is certainly less damaging and, as a result, the particle count is reduced. Initial removal is carried out or replaced after fairly soft etching, such as tertiary acid mixtures of C ₂ H ₃ OOH (acetic acid), HNO ₃ (nitric acid) and HF (hydrofluoric acid), as shown in the figure. Since the mixture is selected and adjusted to reduce or even eliminate damage to grain boundaries, the material grain structure is less prone to fracture. The etch rate depends on the crystal structure of the loop. Preferred etch rates are mostly 1 micron per minute, but the rate obtained depends on the nature of the silicon loop and can range from about 0.1 to 10 microns per minute. Surface roughness or morphology (R _A ) is preferably about 150, but may range from about 100 to 200. The neat etching of the present invention results in less particulate material dispersing from the loop during the continuous processing operation. As a result, for example, less particulate matter is present on silicon wafers during semiconductor processing, and is described in the present invention to be less than 100,000 (100K) per cubic centimeter.

Another advantage of the present invention is that the particulate material is isolated and reduced from the point at which it can be quantized, for example by the particulate material number (PMC) in DI water used for the final rinse of the chamber surface. It is well known to quantify particulate matter in DI, for example by measuring the resistance of water. Unlike quantitative methods, the content of these measurements of particulate matter on wafers is unknown or even unthinkable. The present invention allows for qualitative measurements rather than conventional quantitative measurements by reducing PMC below expected levels, where wafer rejection by particulate matter can be expected with significant accuracy based on PMC in water. . This results in a reliable qualitative method for determining how much to do with the particles deposited on the semiconductor wafer.

Other objects, features and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are used in this specification and constitute a part of this specification, illustrate embodiments of the invention with description, and serve to explain the principles of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Now, a detailed description will be given of the preferred embodiment of the present invention, which is illustrated in the accompanying drawings. Although the invention has been described in connection with the preferred embodiments, it is to be understood that there is no intention to limit the invention to these embodiments. On the contrary, the invention will cover modifications, improvements and equivalents that may be included within the spirit and scope of the invention as defined by the appended claims.

The present invention is directed to the cleaning of the plasma type processing chamber as a complete solution, rather than merely improving a single parameter or problem. Therefore, there is a need to consider both reducing contamination levels, especially copper contamination, and reducing the number of particulate matter, mainly silicon-based particles. Cleaning the surface and in particular removing Cu from the surface is also important for controlling the operation of the chamber. Contamination of the loops or windows of the IPS causes process drift that changes the coupling of the RF power from the coil to the plasma and affects controllability. Mostly sputtered particles are volatile and easily removed. However, copper is nonvolatile and difficult to remove from the chamber.

As can be thought of by those skilled in the art, the number of particulate matter is indicative of processing excellence and is not an absolute index. For example, the number of particles slightly acceptable to a high pressure device is known to have a relaxed geometry because of its large geometry, but it is fatal for high density integrated circuits with very small geometries and tight tolerances. At least in nature and in accordance with the present invention the property data is important in all cases, so the particle number size limit of interest can be for example 1 micron or 0.2 micron or less, but the relative particle number is the most important. In addition, the present invention describes that reducing the particulate material number (PMC) below the reference quality results in a near complete reduction of PMC on the material to be treated, such as a silicon wafer. In one embodiment of the invention, the reference quality is 100K per milliliter (mL).

Continuously smaller particle sizes of interest will require megahertz agitation of the solution because higher frequencies are required to resonate smaller particles. It would also be important to improve the removal of contaminant levels. Contaminant levels that may not be important in large power units may be related to VLSI or ULSI, and the relative levels of contamination are always of great interest.

Reducing the number of particulates and reducing contamination are all achieved by the neat cleaning of the present invention. In the conventional approach, contamination was considered to be well treated by etching and rough removal of the surface, particulate matter was thought to be a function of surface smoothness only, and surface slipping was assured by rough removal and vigorous etching.

1A illustrates an IPS chamber system 10 of the present invention. In FIG. 1, an IPS chamber 12 having a loop 22 is connected to the jungle 14 through plumbing 16 under a false floor 20. When the chamber 12 is in use, the material (not shown) in the chamber 12 is deteriorated by the plasma (not shown). The loop 22, which helps to form an almost vacuum inside the plasma chamber 24, is aggravated by the plasma, including impingement by materials in the chamber.

FIG. 1B shows XPS / ESCA analysis of Si roof particles (XS / ESCA analysis of Si Roof Particles), which is an X-ray spectrometer and chemical analysis electron spectrometer (XPS / ESCA) for chemical analysis, Si for processing chamber It is used to determine the binding energy and the chemical composition of the particles in the loop. In Fig. 1, the total particle number C / S is shown at 103 and then decomposed into constituent particles. The first large peak 105 is SiO ₂ (glass). The second large peak 107 is silicon (Si). Silicate, SiX, is shown as peak 109, where X can be, for example, nitric acid or a similar material. Particles of this type are not easily large enough at either particle size or particle number of great interest. The next peak 111 is often vulnerable to silicon carbide (SiC) used for bead blasting (BB). BB is similar to, for example, Asand blasting @ which is suitable for removing paint from buildings. Peak 111 is also not of great interest. In addition, the present invention does not use SiC and preferably does not use BB.

As will be apparent to those skilled in the art, reducing the particle number will not weaken the silicon-based material bond.

FIG. 2 is a Cu Contamination SIMS Depth Profile (Plasma Side), illustrating Cu contamination in the Si loop of several processing chambers after using the chamber for Cu deposition, for example. In FIG. 2, as is known to those skilled in the art, Cu is a highly desirable material for forming mutual contact with deadly contaminants for integrated circuits, such as Si-based integrated circuits. The chamber of the present invention contains Cu, which is preferred as the processing material, but decreases as much as possible when Cu is undesirable.

As shown in FIG. 2, copper forms a dense surface concentration and is dispersed to a relatively significant depth below the surface. For example, copper appears to be substantially deeper than 1.5 microns at an unacceptable high concentration 203, such as 1x10 ¹⁶ atoms / cubic centimeter (cc), which is nearly 10 microns deep in the case of FIG. In some applications as determined by the present invention, the concentration of copper contamination is uncertainly extinguished to a depth of about 20 microns and should be extinguished to 50 microns in accordance with precautions to clean the loop.

FIG. 3 shows a Silicon Loop: SEM Surface Microstructure Post Bead Blasting & HF Treatment (Current BKM) and is subjected to SiC BB and HF etching of the prior art. Shows a loop. The surface appears very flat, which is intuitively expected that the particulate matter will still attach to the loop, even though small particles are clearly laid loose on the surfaces 213 and 215. The surface clearly represents the prior art assumption that prior art BB and etching provide optimal control of the particulate problem.

4 shows how the prior art roof surface shown in FIG. 3 is so exaggerated that it appears. In FIG. 4, those skilled in the art will see a solid surface and will be able to confirm that particulate matter dispersion is minimized. However, in light of the present invention, more detailed informational examination of the surface shows evidence of delamination 221 from other flat surfaces, such as in flat area 223. In this respect, the surface allows foreseeing the tendency of the particulate problem to be evident as in this case.

5 shows an HNO ₃ —HF—CH ₃ COOH ternary etch diagram useful for determining etch activity, such as etch rate, on the silicon loop of the chamber of the present invention. In FIG. 5, the present invention uses HNO ₃ to oxidize silicon on Si0 ₂ to trap contaminants. HF is used to remove SiO ₂ formed by HNO ₃ , while C ₂ H ₃ OOH wets the material to facilitate the formation and subsequent removal of SiO ₂ . This is a relatively neat process that hardly damages the silicon-based structure of the loop.

Dense concentrations of HF that benefit from the rapid removal of contaminated surfaces are known in the art. HF is also useful for removing glass that HF penetrates strongly. For example, it is also known that applying HF Aclean @ after a SiC BB operation is particularly effective at removing surface debris produced by BB. SiC is known as one of the hardest materials, so relatively small amounts of SiC dust @ are generated in the BB, and SiC BB is known to provide substantial surface removal in a relatively short time.

The prior art has relied on SiC BB and high concentrations of HF cleaning to regenerate contaminated chamber loop material, especially copper contaminated loop material, which is very difficult to remove from the chamber surface, which is very difficult to remove from the chamber surface. It is effective in coupling copper plasma to RF sources and creates problems of system stability. Intuitively, the contamination of rough removal of the surfaces connected by vigorous (also called strongly) etching represents the most economical and effective way of providing the lowest contamination and particulate problems.

However, the present invention results in the conventional SiC BB vulnerably binding the fine particles to the loop material. In addition, relatively concentrated HF infiltrates the grain boundaries of the material, in particular SiC BB here, making the material brittle, resulting in high particulate matter counts and the possibility of contaminants moving to the material. The present invention can avoid fragile materials of prior art BB and coarse HF cleaning. The result of this advantage is not evident by using only soft materials in the BB, or by less vigorous HF etching after SiC BB. Rather, the primary result of either BB or less vigorous HF etching except for the present invention is to reduce material throughput and correspondingly increase cost. However, when both the BB and HF treatments are properly modified or if they are only optimized bases or preferably are optimized acidic etchings used in accordance with the present invention as at point 303 of the ternary diagram above. There is a significant improvement.

FIG. 6 is an embodiment of the present invention that includes LPC Particle Count Analysis Si Roof Coupon: Post Bead Blasting, illustrating the effect of particulate matter in post HF cleaning versus HF free cleaning. Indicates. In FIG. 6, using HF versus not using HF seems to produce equivalent results, but in a number of Ultrasonification steps, and in this figure, more than 10 sonication steps utilize conventional HF cleaning. Deterioration due to the use of the method according to the technique. The present invention utilizes HF but does considerably less powerful cleaning than the prior art. In this figure, it can be seen that the reduction of HF usage in loop cleaning results in a reduction of particulate matter from the loop.

FIG. 7 is an embodiment including SEM Microstructure Post Base Solution Treatment (w / o bead blasting), illustrating how BCP results in high faceted surfaces in polycrystalline silicon. Illustrated. In addition, the anisotropic nature of BCP can be confirmed by discernable micro pitting between the faceted crystals. In FIG. 7, one can see how the grain boundaries are preferentially etched 503. Without careful control, it is clear that the process will cause damage to these boundaries.

FIG. 8 shows the BCP according to the invention at a higher magnification as in FIG. 7, showing that damage to the grain boundary is not very serious as long as care is taken. In FIG. 8, it is believed that there are facets which are mainly a result of anisotropic etching and have somewhat more reflective surfaces, but the integrity of the surface is very good and there is no obvious delamination as in the prior art BB and HF etching processes.

FIG. 9 relates to a SEM microstructure Post ACP Treatment Si Coupon # 2 and illustrates an ACP according to the present invention. In FIG. 9 a more blurred or substantially non-reflective surface is clearly shown. While there are no or little fitting or similar problems, brighter surfaces represent relatively rough surfaces of very small scale.

FIG. 10 shows a higher magnification of the ACP of the embodiment according to the present invention as in FIG. 9. In Figure 10, one can see the properties of the relatively rough surface. Here, the anisotropic etching of the ACP produces a series of wavy valleys surrounded by very small ridges having a very small, substantially acid-like shape, as described above. It can be seen that the highly reflective facet of the material surface of the BCP is avoided by the ACP.

FIG. 11 is an IPS Roof Metal Concentration level Base Treatment w / o Bead Blasting + BKM2 rinse, showing an embodiment of a reference cleaning of the present invention as IPS Roof Metal Concentration Level Base Treatment w / o Bead Blasting + BKM2 Rinse. In FIG. 11, a typical BKM cleaning may be combined with a Sailing Post Base Clean with a “dirty” loop or Ceiling Before Clean, for example, 28,000,000 × 10 ¹⁰ Cu contaminations per square centimeter. Compared. All fine metals are reduced in this figure, and the most important contaminant, Cu, is reduced by a factor of at least 20 and below the reference level of about 1 × 10 ¹⁰ . Potassium, not shown in the conventional BKM cleaning of the prior art, was eliminated and all fine metals were reduced. This reduction is particularly important with respect to copper, since copper is shown to be the cause of instability in the plasma.

FIG. 12 is an IPS Roof Metal Concentration level ACP Treatment w / o Bead Blasting + BKM2 rinse, showing an embodiment of a reference cleaning of the present invention as IPS Roof Metal Concentration Level ACP Treatment w / o Bead Blasting + BKM2 Rinse. In FIG. 12, a “dirty” loop of 112,000,000 × 10 ¹⁰ Cu contamination, for example 2.8 × 10 ¹⁷ atoms per square cm, was cleaned with ACP. The result of ACP is a large fine metal reduction above the conventional BKM cleaning of the prior art. For example, the reduction of Cu, the most important fine metal contaminant, is made by more than 100 factors. In the reduced state shown, the stability of the IPS process adversely affected by copper is reduced, and thus can be used for nearly 300 (identified as 294) hours before the cleaned loop is typically cleaned again. This advantageous result is obtained by the level of copper pollutants that are 1 × 10 ¹⁰ atoms or less per square centimeter, such as 0.2 × 10 ¹⁰ atoms per square centimeter. In the prior art, the cleaned loop could only be used for about 200 hours until it was cleaned again. The achieved concentration reduces the fine metal concentration to an almost insignificant level and essentially returns the loop to the unused loop conditions for fine metal contamination.

FIG. 13 illustrates an embodiment of the present invention for base cleaning (BCP) and acid chemical polishing (ACP). It will be noted that while the process according to the invention in FIG. 13 presents the same result, the BCP takes about 6 hours compared to about 0.5 to 1 hour for ACP. For isotropic etching of ACP, it will be appreciated that the BCP is anisotropically etched, resulting in more difficult BCP control. ACP results in a rounded contour of the semiconductor surface, whereas BCP results in a significantly shaved surface on the semiconductor surface. However, an important point of this figure is that acids or bases may be used in accordance with the present disclosure.

FIG. 14 is an example illustrating how the number of particulate matter is affected by subsequent BKM # 2, ie, further improved BKM cleaning, after base etch (BCP) of the present invention. In Fig. 14, it is evident that ACP is an inherent cleaning process, since only the residue is hardly affected by removal by the BKM # 2 process. This is clearly shown by the difference in particulate matter after 40 minutes of sonication time or in an ultrasonic stirring environment. Here, there is a net change of 215,698 and 123,529 differences per square centimeter. According to the present invention, further ultrasonification up to 70 minutes can be achieved with a particulate matter number below 200,000 baseline and preferably below 100,000 baseline, both with and without BKM # 2 treatment. PMC).

FIG. 15 is an example illustrating how particulate matter number is affected by subsequent BKM # 2, ie, further improved BKM cleaning, after acidic etching (ACP) of the present invention. In Figure 15 it is clear that the ACP is an inherent cleaning process since the residue is hardly affected by removal by the BKM # 2 process. This is clearly shown by the difference in particulate matter after 40 minutes of sonication time or time in an ultrasonic stirring environment. Here, only a net change in the number of particles of order 263,521 and 242,936 per square centimeter, or slightly more than 21,000 per square centimeter, occurs. It will be understood that such numbers are approximate and will vary with the practice of the present invention. According to the present invention, further sonication up to 70 minutes reduces PMC below the baseline of 200,000 PMC with or without BKM # 2 treatment.

16 is an embodiment of the invention showing a silicon wafer with particles after being processed in the chamber of the present invention. In FIG. 16, an embodiment of the present invention results in less than 100K (100,000) particles per milliliter (mL) of water used to rinse the loop surface. Low particle counts will cause relatively minor problems with particulate matter in materials processed in the chamber of the present invention, such as silicon wafer 703. This belief is demonstrated by the almost absence of particles 705 on the illustrated wafer, which have a total of four particles of 0.2 microns or larger.

Plot 707 at the bottom of FIG. 16 shows the PMC in terms of particle size. There are three particles with a diameter slightly larger than 0.2 micron and one particle with a diameter of about 0.8 micron.

FIG. 17 shows the total particle count achieved with conventional BB and HF etching through contrast. In FIG. 17, particulate material 803 is optionally scattered on wafer 805. Depending on the size of the integrated circuits of the wafer as well as the structure size and density of these circuits, the particulate material can substantially fill the product labeled Ayield @ on these silicon wafers.

Diagram 807 at the bottom of FIG. 17 shows the PMC with respect to the size of the wafer. Most particles are about 0.3 microns in diameter, but these range up to about 1.5 microns, four of which are much larger than 1 micron in diameter.

The foregoing description of certain embodiments of the present invention has been provided for purposes of illustration. It is to be understood that these embodiments are not intended to be exhaustive or to limit the invention to the precise form described, and that numerous modifications are possible in light of the above teaching. The embodiments have been selected and described in order to provide an optimal description of the principles and practical embodiments of the invention to enable those skilled in the art to make various modifications that are suitable to the particular use contemplated by the invention. It is intended that the scope of the invention be limited by the appended claims and equivalents thereof.

Claims (29)

A method of cleaning a silicon loop of a plasma chamber, Etching the loop; Cleaning the loop after the etching step, Rinsing the loop with deionized water after the washing step; Determining an amount of the first particulate material of a predetermined size or more inside the deionized water, and Comparing the first particulate material to a predetermined reference amount of particulate material. The method of claim 1, wherein the etching is performed without substantial damage to the silicon structure. The method of claim 1 wherein said etching is performed by acid. The method of claim 1 wherein said etching is performed with a base. The method of claim 1, wherein the silicon loop is polycrystalline silicon. The method of claim 1 wherein the material to be treated is a silicon wafer. A method of cleaning a silicon loop of a plasma chamber, Etching the loop until fine metal contaminants are reduced below a predetermined value, and Cleaning the loop after the etching step. The method of claim 1 wherein said etching is performed by acid. 8. The method of claim 7, wherein said etching is performed with a base. 10. The method of claim 9, wherein the base is ammonium hydroxide or potassium hydroxide. 8. The method of claim 7, wherein the silicon loop is polycrystalline silicon. 8. The method of claim 7, wherein the material to be treated is a silicon wafer. A process of cleaning the silicon loop of a plasma chamber, Etching the loop without substantial damage to the silicon structure until fine metal contaminants are reduced below a predetermined value; Cleaning the loop after the etching step, and Rinsing the loop with an inert material after the cleaning step. The method of claim 13, wherein the inert material is deionized water. The method of claim 13, wherein the fine metal contaminants are copper. The method of claim 15, wherein the amount of copper fine metal is 1 × 10 ¹⁰ _{atoms / cm 3} or less. A process of cleaning a silicon loop of a plasma chamber, the method comprising determining an amount of particulate material from the silicon loop, the method comprising: Etching the loop without substantial damage to the silicon structure; Cleaning the loop after the etching step, Rinsing the loop with an inert material, and Reducing the amount of the first particulate material below a reference amount of the predetermined particulate material. The process of claim 17 wherein the inert material is deionized water. 18. The process of claim 17, wherein the material to be treated is a silicon wafer. A cleaning process of a silicon loop, comprising improving the stability of an IPS plasma, Etching the loop; Cleaning the loop after the etching step, Rinsing the loop with an inert material, and Reducing copper contaminants in the loop below a predetermined copper threshold. An apparatus for cleaning a silicon loop of a plasma chamber, Means for etching the loop until fine metal contaminants are reduced below a predetermined value; Means for cleaning the loop after the etching, Deionized water means for rinsing the loop after the cleaning, Means for quantitatively determining the amount of particulate material of a predetermined size or more inside deionized water after rinsing the loop, and Means for comparing the amount of particulate matter with a predetermined reference amount. The apparatus of claim 21, wherein the means for etching is an acid. The apparatus of claim 21, wherein the means for etching is a base. The device of claim 21, wherein the silicon loop is polycrystalline silicon. The apparatus of claim 21 wherein the material to be treated is a silicon wafer. An apparatus for cleaning a silicon loop of a plasma chamber, Means for etching the loop, Means for cleaning the loop after the etching, Inert material means for rinsing the loop after the cleaning, Means for quantitatively determining the amount of particulate material of a predetermined size or more inside the inert material after rinsing the loop, and Means for comparing a quantity of said particulate matter with a predetermined reference amount. 27. The apparatus of claim 26, wherein the inert material is deionized water. 27. The apparatus of claim 26, wherein the base is no more than 200,000 particulate matter per cubic centimeter. 27. The device of claim 26, wherein the base is preferably no greater than 100,000 particulate matter per cubic centimeter.