JP2003505858A - Polishing mixture and method for reducing the incorporation of copper into silicon wafers - Google Patents

Abstract

(57) [Summary] A method for reducing the incorporation of copper into a semiconductor single crystal silicon wafer during polishing comprises the following steps: a) adding a copper conditioning additive to a copper-containing polishing mixture; Reacting the additive with the copper in the polishing mixture to produce a copper compound having a solubility product ( _Ksp ) of less than about ^10-20 ; and b) then, as the wafer moves relative to the abrasive, Polishing the wafer surface by contacting the wafer surface with an abrasive and the polishing mixture. Also disclosed are novel polishing mixtures used to polish semiconductor single crystal silicon wafers and reduce the incorporation of copper into the wafers.

Description

Detailed Description of the Invention

TECHNICAL FIELD The present invention relates generally to polishing mixtures and methods for reducing the incorporation of copper into silicon wafers, and more particularly, during the polishing of silicon wafers without adversely affecting polishing performance. It relates to a method of reducing the amount of copper entering.

BACKGROUND ART Conventional polishing mixtures contain inorganic bases and colloidal silica. Such mixtures, and other polishing chemistries present in the mixtures, contain trace metallic impurities. Of these, copper is a particular problem because it is incorporated into the wafer during surface polishing. Since the majority of random semiconductor devices and gate oxide defects are derived from copper silicide precipitates, it is important to reduce such copper contamination. In addition, high levels of copper contamination result in an undesired increase in resistivity, facilitating decomposition of the wafer surface known as chemical haze. For these reasons, integrated circuit manufacturers generally
Requires that the copper concentration of the silicon wafer surface in the art is measured by the general method is 1 × 10 ^{1 0} atoms / cm ² to 1 × 10 ¹¹ atoms / cm ² or less. This condition is expected to be reduced to 1 × 10 ⁹ atoms / cm ^{2 to} 5 × 10 ⁹ atoms / cm ² or less.

One method of reducing wafer contamination by copper during surface polishing is to use high purity polishing mixtures and other polishing chemistries. However, the standards for trace metals on wafers have become extremely strict, and it has become increasingly costly and inefficient to meet the standards by simply using pure chemicals.

German Patent DE 39393661 and the article by Prigge et al. Journal of the Electroc
hemical Society, vol.138, (1991), pp.1385-1389 describes a method to solve this problem without removing trace copper impurities from the polishing mixture. According to the disclosure of the German patent, the incorporation of copper into a silicon wafer during surface polishing by adding to the polishing mixture certain chemicals that form copper complexes having certain coordination configurations or morphologies. Is reduced. An advantageous form is one that is sufficiently different from the square planar form, with a tetrahedral form or arrangement being preferred. It has been determined that such advantageous ligands for complexing with copper are alcohols and hydroxycarboxylic acids, such as ethylene glycol and tartaric acid, respectively. On the contrary,
It has been determined that compounds that promote the incorporation of copper into silicon during polishing are nitrogen compounds that act as Lewis bases, such as ammonia and amines. In polishing, it is customary to add amines and / or ammonia to the polishing mixture to increase the silicon removal rate during polishing.

As a result, amines and ammonia are present in the polishing mixture despite concerns regarding copper contamination. Thus, while the prior art references also disclose that amines and ammonia increase copper contamination, copper contamination is controlled by the use of additives that form the preferred copper complex, although such additives do not. Is not sufficiently effective to counteract the adverse effects of amines or ammonia. Furthermore, said prior art also discloses controlling copper contamination by adding a complexing ligand in the order of 6 to 7 higher than the copper present in the polishing mixture. Not only is such addition inefficient, it also changes the pH and other conditions of the polishing mixture from the optimal conditions needed for the polishing process.

Therefore, it reduces the incorporation of copper into the wafer during polishing, is effective in the presence of ammonia or amines and does not adversely affect the polishing rate or process.
Improved polishing compounds and methods are still needed.

DISCLOSURE OF THE INVENTION It is an object of the present invention to provide polishing methods and polishing mixtures that reduce copper incorporation into silicon wafers during polishing; such methods effective in the presence of ammonia or amines. And a polishing mixture; and, providing such a method and a polishing mixture using the additive at a concentration at which polishing rate and performance are substantially unaffected. Other objects and features will be in part apparent and in part pointed out below.

Briefly, the present invention relates to a method of reducing the incorporation of copper into a semiconductor single crystal silicon wafer during polishing, the method comprising the steps of: a) containing copper Adding a copper control additive to the polishing mixture to react with copper in the polishing mixture to produce a copper compound having a solubility product (K _sp ) of less than about 10 ^-20 ; and b. Next, a step of polishing the wafer surface by bringing the wafer surface into contact with the polishing material and the polishing mixture as the wafer moves with respect to the polishing material.

The present invention further relates to a polishing mixture used to polish a single crystal silicon wafer and reduce the incorporation of copper into the wafer during polishing, the polishing mixture comprising:
Inorganic bases, colloidal silica, and copper compounds having a solubility product (K _sp ) less than about 10 ^-20 produced by reacting copper present in the polishing mixture with a copper modifying additive added to the polishing mixture. Comprising.

According to the present invention, a copper conditioning additive that reacts with copper impurities in the polishing mixture to form a copper compound having a solubility product (K _sp ) of less than about 10 ^{−20 is} added to a conventional polishing mixture. It was then found that polishing the wafer with the resulting polishing mixture can reduce the incorporation of copper into the semiconductor single crystal silicon wafer during polishing.

As is known, polishing mixtures used to polish semiconductor single crystal silicon wafers generally contain colloidal silica, which is commercially available as a silica slurry, and an inorganic base (eg, an alkali metal hydroxide). Contains as the main component. In such polishing mixtures, copper impurities are generally present in concentrations of the order of 1 to 10 weight ppb, rarely up to 100 weight ppb, depending on the purity of silica and the other components of the polishing mixture.

In the practice of the present invention, the copper modifying additive is any compound that reacts with copper impurities in the polishing mixture to produce a copper compound having a solubility product (K _sp ) of less than about 10 ^−20. Good. The copper-containing additive preferably comprises an anion selected from the group consisting of phosphates, sulfides, selenides, and arsenates, in an alkaline aqueous medium having a pH in the range common to polishing mixtures. It is chemically stable. The additive is
It can be dissociated into a dissolved state prior to addition to the polishing mixture. The amount of copper control additive added to the polishing mixture is preferably at least stoichiometrically equal to the copper content of the polishing mixture, and more preferably at least the theoretical equivalent of the copper content of the polishing mixture. It is about 100 times, more preferably about 100 to about 10,000 times the theoretical equivalent of the copper content of the polishing mixture. Examples of compounds that may be used in the practice of this invention are:
Potassium monohydrogen phosphate, potassium phosphate, hydrogen sulfide, ammonium sulfide, and potassium selenide. Other compounds that react with copper impurities to form sufficiently insoluble copper compounds, such as copper (II) phosphate, copper (II) sulfide, copper (II) selenide, or copper (II) arsenate may also be used. It will be understood.

It has been observed that the reduction of copper introduced into the wafer during polishing is maximized by adding a copper control additive to the polishing mixture at least about 24 hours before the start of the polishing operation. Without being bound to any particular theory, it is believed that a time of at least about 24 hours allows the polishing mixture to reach chemical equilibrium.

[0014]   Without being bound to any particular mechanism with respect to the present invention, polishing
A copper conditioning additive added to the mixture precipitates copper as a nearly insoluble compound,
This may prevent it from being incorporated into the silicon wafer during polishing.
Be done. Therefore, it reacts with copper impurities and has a very low solubility in precipitates, i.e.
Ten^-20Solubility product less than (K_spAny compound that forms a precipitate with
, Effective for controlling copper pollution. About 10^-20Limit maximum solubility product of less than (K _sp ) Is a simple single-phase solution model (a liquid solution containing an inorganic base and copper impurities).
) Was used to determine quantitatively. Hydroxide ions are present in high concentrations, therefore
Copper (II) hydroxide, Cu (OH)₂Are produced prior to the addition of the copper control additive. Copper hydroxide (I
I) is about 10^-20K_spIt is a stable compound having
Because of the undesirable copper contamination of the wafer during_spThe value is low enough
There is no. Therefore, an effective copper modifier is about 10^-20Produces copper compounds with Ksp values less than
Must be done. About 10 copper control additives^{-twenty three}Less than, more preferably about 10^-26 Less, more preferably about 10^-29Less, more preferably about 10^-32Less than, better
More preferably about 10^-35Less than K_spIt is preferred to produce a copper compound having a value.

The amount of copper control additive added to the polishing mixture is sufficient to potentially precipitate all copper impurities, ie, at least equivalent to the theoretical equivalent of the copper content of the polishing mixture. There must be. For example, if the molarity of copper is [Cu], then when hydrogen sulfide is used as an additive, the precipitate formed is CuS, so its molarity, expressed as [H ₂ S], is at least [Cu 2 ] Must correspond to. Similarly,
If potassium monohydrogen phosphate is used as an additive, assuming that the monohydrogen phosphate ion is completely decomposed, the precipitate is Cu ₃ (PO ₄ ) ₂ and therefore its molar concentration indicated by [K ₂ HPO ₄ ]. Must correspond to at least (2/3) [Cu]. However, in practice, it was observed that copper precipitation was not maximized by the stoichiometric amount of additive, so it is preferred that the amount of copper control additive added to the polishing mixture is in excess of stoichiometric amount. . Since the typical value of [Cu] is extremely small (generally around 10 ⁻⁷ M), the preferred amount of additive, 100 to 10,000 times the copper content of the polishing mixture, does not change the pH of the mixture, The amount is sufficiently small so as not to adversely affect the polishing performance.

Any method for removing silicon from a wafer surface by contacting the wafer with an abrasive and a polishing mixture and polishing the wafer surface as the wafer moves relative to the abrasive is described. It is also effective for polishing operations and can be used on all types of silicon polishers, including, but not limited to, single sided, double sided and edge polishers.

Accordingly, the present invention overcomes the shortcomings of the prior art and provides an effective means of reducing copper incorporation into silicon wafers during polishing. The improved method and polishing mixture of the present invention are effective in the presence of ammonia or amines and do not substantially change the chemical composition of the final polishing mixture and do not affect the polishing rate at such low levels of additive. Allows the use of compounds.

[0018] (Example)   The following examples illustrate the practice of this invention.

Example 1 In the following test, a diameter of 200 mm, a (100) crystal array, and 0.071 to 0.084 Ω · c
A boron-doped p-type silicon wafer grown by the Czochralski method with a resistivity of m was used. In one test, potassium monohydrogen phosphate was added to a conventional polishing mixture at a concentration of 10 ^-4 mol / L by feeding the polishing pad. In the second test, hydrogen sulfide was added to the conventional polishing mixture at a concentration of 1.5 × 10 ⁻³ mol / L by feeding the polishing pad. The common components of the polishing mixture were colloidal silica and amines stabilized by alkali hydroxide. Wafers were polished for 7 psig in 245 seconds using the two polishing mixes obtained.
Polishing was performed at a pressure of 12.6 at pH 12.6. The results are shown in FIGS. 1 and 2. The dependent variable is
It was the surface concentration of copper measured on the wafer after heat treatment at 120 ° C. for 90 minutes. The heat treatment process allows the copper embedded in the wafer body to diffuse back to the wafer surface (Prigge et al., Journal of the Electrochemical Society, vol.138, (1991),
pp.1385-1389). The assay consists of acid drip extraction of the surface and analysis of the extract for trace copper by ICP-MS (Inductively Coupled Plasma / Mass Spectroscopy). The result is converted into the surface copper concentration shown by {Cu}, and is represented by the number of atoms per cm ^{2 of} the wafer surface. In both tests, a control group of wafers was polished using the same polishing mixture but without the copper control additive. As can be seen from FIGS. 1 and 2, the present invention is effective in reducing the incorporation of copper into a semiconductor single crystal silicon wafer during polishing.

Example 2 In the following test, the diameter was 200 mm, the (100) crystal array, and 0.071 to 0.084 Ω · c.
In polishing a wafer of boron-doped p-type silicon grown by the Czochralski method with a resistivity of m, in reducing the incorporation of copper into the wafer,
The effectiveness of various additives was evaluated. Other conditions were the same as in Example 1. In particular,
Each test was aimed at assessing the effectiveness of a single polishing additive, the first six additives shown in Table 1 below are known in the art as copper complexing additives and others The additive is believed to regulate copper by forming a copper compound / precipitate.

Each test consists of: a) polishing 7 to 8 wafers with a polishing mixture containing the additives to be tested, b) without additives and with the same polishing mixture. Polishing 7-8 wafers, c) heat treating all the polished wafers above, and 5-8 unpolished wafers, and d) removing copper from the surface of the heat treated wafers by acid drip method. Extract and analyze the extract for traces of copper by the ICP-MS method (Inductively Coupled Plasma / Mass Spectroscopy) and convert the results to a surface copper concentration in number of atoms per cm ² of the wafer surface. The heat treatment process allows the copper embedded in the wafer body to back-diffuse to the wafer surface (Prigge et al., Journal of the Electrochemical S
ociety, vol.138, (1991), pp.1385-1389).

The numerical results of the tests depend on the nature of the wafers used and the heat treatment method, but not enough of the same wafers were obtained for all tests. Despite the differences in test wafers and heat treatment methods in the various tests, a common criterion for comparison of numerical results was obtained by: a) using randomized wafers cut from the same crystal part, b) Introduce a specific measure of surface copper concentration change due to additives. This amount is {Cu
} And is defined by the following formula:

[0023]

[Equation 1]

{Cu} _ad and {Cu} _st indicate the average surface copper concentration of wafers polished with the polishing mixture with and without additives, respectively. {Cu} _unp is
The average surface concentration of all unpolished wafers used in the same test is shown. Therefore, the formula (1
) Is the δ {Cu} predicted for wafers polished with and without additives and is expressed as a percentage of the change due to polishing observed when polished without additives, and Specified as the difference. Separation of δ {Cu} from different test wafers and heat treatment methods of various tests is based on the following assumptions: a) Copper incorporation rate during polishing is the average surface concentration of copper before polishing {Cu} _Independent of _unp , b) copper incorporated into the wafer during the polishing step diffuses completely from the wafer during the heat treatment. A negative value of δ {Cu} means that the reduction of copper contamination during polishing was achieved by using the additive, a positive value means an increase. Moreover, in the absence of statistical uncertainty regarding the numerical results, a negative δ {Cu} value of 100 means complete suppression of copper contamination during polishing and a value of zero means no effect. Finally, additives that produce copper compounds with the same δ {Cu} values when tested under the same conditions should be considered as effective in reducing copper incorporation into the wafer during polishing. Is.

[0025]

[Table 1] Table 1

The first column of Table 1 shows the additives tested. The total molar concentration of the additive is 3 × 10 ^-4 mol / L in all cases, provided that the molar concentration in the case of K ₂ HPO ₄ is 10 ^-4 mol / L, in the case of H ₂ S The molar concentration was 1.5 × 10 ⁻³ mol / L. The latter concentration is
The higher concentration ensures a sufficiently high concentration of decomposed sulfide ions in the polishing mixture to compensate for the low dissociation constant of hydrogen sulfide. The total molar concentration of copper in the polishing mixture was 6 × 10 ^-8 to 10 ^-7 mol / L (3.8 and 6.4 mass ppb, respectively). Therefore, the stoichiometric excess of additive to total copper is 10 ^{3 in} all cases.
It was about 10 ⁴ . The second column of Table 1 shows the compound that is believed to precipitate by the reaction of the copper impurities with the additive, and the solubility product K _sp of that compound. The third column is the difference in the surface copper concentration of the wafer polished without and with the additive, which is indicated by the amount δ {Cu} defined in equation (1). Indicates. The fourth column shows the 95% confidence level of the difference in surface copper concentration between the wafers polished with additives and the wafers polished without additives, calculated using analysis of variance (ANOVA). Indicates whether or not is significant. Finally, the fifth column shows the p-value obtained with ANOVA.

In most tests, the polishing removal rate of wafers polished with additives,
No statistically significant difference was observed in the polish removal rate of wafers polished without additives. The only statistically significant differences observed are: 2.5% higher rates with ammonium citrate than without; with gluconic acid than without 1.4% higher rate; 4.6% higher rate with hydrogen sulfide than without. The difference in these removal rates is defined as the percent removal rate without the additive.

Each tested copper control additive that reacts with copper to form a copper compound / precipitate, whether positive or negative, has a statistically significant change in the final copper concentration of the wafer. Occurred. In contrast, only one of the copper complexing additives used in the art to reduce copper contamination (1,2-benzenediol (o-catechol)) showed a statistically significant difference in final copper contamination. And its effect was to increase copper contamination.

Hydrogen sulphide, ammonium sulphide, potassium monohydrogen phosphate and ammonium monohydrogen phosphate, when added to the polishing mixture, produce copper compounds with a solubility product K _sp of less than 10 ⁻²⁰ , each of 21.6%. , 13.9%, 18.6% and 12.3% reduce copper contamination of polished wafers, Table 1 shows. However, Table 1 also shows that not all test compounds that meet the defined dissolution criteria are effective in reducing copper contamination of the wafer during polishing. In particular, two of the additives expected to reduce copper contamination, namely potassium carbonate and sodium monohydrogen phosphate, effectively increased wafer contamination by copper.

Additives containing carbonate anions react with hydroxide ions and copper impurities present in the polishing mixture to produce simple copper carbonate CuCO ₃ having a K _sp of 10 ^−9.6 , and 10 ^{−3 3.8} and Basic copper carbonates Cu ₂ (OH) ₂ CO ₃ and Cu ₃ (OH with K _sp values of 10 ^-46 respectively
) ₂ (CO ₃ ) ₂ (the above K _sp values are based on Smith, RM and Martell, AE).
., Critical Stability Constants, Plenum vol.4, (1976)). Basic copper carbonate had a K _sp value of less than 10 ⁻²⁰ and was expected to be effective in reducing copper contamination. Without being bound to any particular theory, the observed negative results are because the putative single-phase model (ie, liquid only) is not sufficient to produce a two-phase colloidal suspension of the actual polishing mixture. It is believed that there is. In particular, basic copper carbonate preferentially precipitates on the surface of silica particles having an OH ion concentration significantly higher than that of the liquid layer. Furthermore, silica particles participate in the chemical mechanical reaction with silicon during the polishing process (Fussstetter, H. et al.
Et al., `` Impact of Chemomechanical Polishing on the Chemical Composition an
d Morphology of the Silicon Surface, Materials Research Society Sympos
ium Proceedings, vol.386, (1995), p.97), a basic copper precipitate can be activated to react with silicon and release copper. If the above hypothesis is correct, then no form of carbonate is effective in reducing copper contamination from the polishing mixture.

It is believed that the undesired effect of sodium phosphate is due to the interaction of sodium and lithium potassium ions with colloidal silica particles at pH levels above 11. That is, only at pH values below 11 and unlike all other cations that have such an effect, sodium and lithium cause aggregation of silica particles at pH values above 11 (Iler, R., Chemistry of Silica. , Wiley, (1979), p
.375). Perhaps this behavior, along with the interaction of copper impurities and silica particles,
It is considered that when sodium phosphate was used as an additive, it contributed to the increase of copper contamination during polishing. If so, the sodium and lithium cations are
It is considered to have the same effect when used as an additive in combination with other anions.

In view of the above, it will be seen that the objects of the invention are achieved and other advantageous results attained.

All modifications contained in the above description and shown in the accompanying drawings are intended to be exemplary, as various modifications may be made to the above processes or methods and products without departing from the scope of the present invention. It should be understood that there are things that are not limiting.

[Brief description of drawings]

FIG. 1 shows the reduction of copper incorporation into semiconductor single crystal silicon wafers,
5 is a graph showing the effect of the addition of potassium monohydrogen phosphate to the polishing mixture.

FIG. 2 In reducing the incorporation of copper into semiconductor single crystal silicon wafers,
3 is a graph showing the effect of adding hydrogen sulfide to the polishing mixture.

[Procedure for Amendment] Submission for translation of Article 34 Amendment of Patent Cooperation Treaty

[Submission date] May 7, 2001 (2001.5.7)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Contents of correction]

[Claims]

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE), CN, JP, K R, SG (72) Inventor Andjerko Basic             United States 63376 St. Missouri             Peters, Mail Zone MZ             33, Post Office Box 8, Par             Le Drive 501, MMC             Electronic Materials Inco             ー Porated (72) Inventor Lois Ilig             United States 63376 St. Missouri             Peters, Mail Zone MZ             33, Post Office Box 8, Par             Le Drive 501, MMC             Electronic Materials Inco             ー Porated (72) Inventor James Sea Joe's Jr.             United States 63376 St. Missouri             Peters, Mail Zone MZ             33, Post Office Box 8, Par             Le Drive 501, MMC             Electronic Materials Inco             ー Porated F-term (reference) 3C047 FF08 GG15 GG20                 3C058 AA07 CA01 DA02 DA12

Claims (23)

[Claims] 1. A method for reducing the incorporation of copper into a single crystal silicon wafer during polishing, the method comprising the steps of: a) adding a copper control additive to a polishing mixture containing copper, said copper control additive. The additive reacts with copper in the polishing mixture to produce a copper compound having a solubility product (K _sp ) of less than about 10 ⁻²⁰ ; and b) then, as the wafer moves relative to the abrasive. Polishing the wafer surface by contacting the wafer surface with an abrasive and the polishing mixture. 2. The copper conditioning additive comprises an anion selected from the group consisting of phosphates, sulfides, selenides, and arsenates, the anion reacting with copper to form a copper compound. The method according to Item 1. 3. The method of claim 1 wherein the copper modifying additive is selected from the group consisting of potassium monohydrogen phosphate, potassium phosphate, hydrogen sulfide, ammonium sulfide, potassium selenide, ammonium monohydrogen phosphate. 4. The method of claim 3, wherein the copper conditioning additive is potassium monohydrogen phosphate. 5. The method of claim 3, wherein the copper conditioning additive is hydrogen sulfide. 6. The copper compound produced according to claim 1, which is selected from the group consisting of copper (II) phosphate, copper (II) sulfide, copper (II) selenide, and copper (II) arsenate. Method. 7. The method of claim 1, wherein the copper compound produced has a solubility product (K _sp ) of less than about 10 ⁻²³ . 8. The method of claim 7, wherein the copper compound produced has a solubility product (K _sp ) of less than about 10 ⁻²⁶ . 9. The method of claim 1, wherein the amount of copper control additive added to the polishing mixture is at least stoichiometrically equal to the copper content of the polishing mixture. 10. The method of claim 9, wherein the amount of copper control additive added to the polishing mixture is at least about 100 times the theoretical equivalent of the copper content of the polishing mixture. 11. The method of claim 10, wherein the amount of copper control additive added to the polishing mixture is from about 100 to about 10,000 times the theoretical equivalent of the copper content of the polishing mixture. 12. A copper conditioning additive is added to the polishing mixture for at least about 24.
The method of claim 1, wherein the wafer surface is not polished until the time has elapsed. 13. A polishing mixture used to polish a single crystal silicon wafer and reduce the incorporation of copper into the wafer during polishing, the polishing mixture comprising:
Inorganic bases, colloidal silica, and copper compounds having a solubility product (K _sp ) less than about 10 ^-20 produced by reacting copper present in the polishing mixture with a copper modifying additive added to the polishing mixture. A polishing mixture comprising: 14. The copper conditioning additive comprises an anion selected from the group consisting of phosphates, sulfides, selenides, and arsenates, the anion reacting with copper to form a copper compound. Item 14. The polishing mixture according to Item 13. 15. The polishing mixture of claim 13, wherein the copper modifying additive is selected from the group consisting of potassium monohydrogen phosphate, potassium phosphate, hydrogen sulfide, ammonium sulfide, potassium selenide, ammonium monohydrogen phosphate. 16. The polishing mixture according to claim 15, wherein the copper conditioning additive is potassium monohydrogen phosphate. 17. The polishing mixture of claim 15, wherein the copper conditioning additive is hydrogen sulfide. 18. The copper compound is copper (II) phosphate, copper (II) sulfide, copper selenide (
II) The polishing mixture of claim 13 selected from the group consisting of copper (II) arsenate. 19. The polishing mixture according to claim 13, wherein the copper compound has a solubility product (K _sp ) of less than about 10 ⁻²³ . 20. The polishing mixture of claim 19, wherein the copper compound has a solubility product (K _sp ) of less than about 10 ⁻²⁶ . 21. The polishing mixture of claim 13, wherein the amount of copper conditioning additive added to the polishing mixture is at least stoichiometrically equal to the copper content of the polishing mixture. 22. The polishing mixture of claim 21, wherein the amount of copper control additive added to the polishing mixture is at least about 100 times the theoretical equivalent of the copper content of the polishing mixture. 23. The polishing mixture of claim 22, wherein the amount of copper conditioning additive added to the polishing mixture is about 100 to about 10,000 times the theoretical equivalent of the copper content of the polishing mixture.