JP2016124943A - Polishing composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing composition which can get superior characteristics in all of surface roughness of a wafer, shape of wafer and surface smoothness in the penumbra of the wafer without reducing grind speed in the grind of the semiconductor wafer.SOLUTION: A polishing composition contains a polyvinyl alcohol-based water-soluble polymer compound and a piperazine compound. The polishing composition preferably contains abrasive grains.SELECTED DRAWING: None

Description

  The present invention relates to a polishing composition used for polishing a semiconductor wafer.

  In the process of polishing a semiconductor silicon wafer, a polishing composition is used. Properties required for the polishing composition include polishing rate, surface properties of the polished wafer, and the like.

  In general, in order to improve the polishing rate of a wafer, an amine compound is blended with the polishing composition. However, when the compounding amount of the amine compound is excessive, the characteristics of the wafer surface may be deteriorated. Therefore, for the purpose of improving surface characteristics (for example, improving surface roughness and reducing wafer defects), a water-soluble polymer compound of a cellulose derivative (for example, hydroxyethyl cellulose (HEC)) or a block type is used as a polishing composition. Mixing a polyether (for example, polyoxyethylene polyoxypropylene ether) or the like is performed.

  Patent Document 1 discloses a polishing composition containing silicon dioxide, an alkali compound, and an anionic surfactant. In the polishing composition disclosed in Patent Document 1, it is described that the anionic surfactant is at least one selected from a sulfonic acid surfactant, a carboxylic acid surfactant, and a sulfate ester surfactant. ing. Patent Document 1 describes that according to this polishing composition, the surface roughness of the silicon wafer can be reduced and the polishing rate can be increased.

  Patent Document 2 includes polishing comprising (a) silicon dioxide, (b) water, (c) a water-soluble polymer compound, (d) an alkali compound, and (e) a compound having 1 to 10 alcoholic hydroxyl groups. A composition for use is disclosed. In the polishing composition disclosed in Patent Document 2, the water-soluble polymer compound is a cellulose derivative. Moreover, according to Patent Document 2, according to this polishing composition, foreign matter (particles) adhering to the wafer surface can be reduced without deteriorating the haze level and the surface roughness improving characteristics, and at the same time, excellent. It is described that a polished surface can be formed.

JP 2005-568665 A Japanese Patent No. 4115562

  By the way, when the present inventors compound a cellulose derivative as a water-soluble polymer compound in the polishing composition, the polishing rate at the peripheral portion of the wafer is smaller than the inside, and as a result, polishing at the peripheral portion of the wafer after polishing is performed. I found that the amount would be smaller than the inside. That is, in the polished wafer, the peripheral edge of the wafer becomes thicker than the inner side, resulting in a roll-up shape.

  In order to search for this cause, the present inventors examined a polishing pad, a polishing liquid, and polishing conditions. As a result, the present inventors have obtained the knowledge that the water-soluble polymer compound is causing the roll-up. Specifically, more polishing liquid exists in the peripheral portion due to the centrifugal force at the peripheral portion of the wafer and the inside thereof. Therefore, it is considered that more water-soluble polymer compound is adsorbed on the peripheral edge portion and the inner periphery thereof. Since the influence of the water-soluble polymer compound appears strongly at the peripheral portion of the wafer, the knowledge that the polishing rate at the peripheral portion of the wafer is smaller than that at the inner side and a roll-up phenomenon occurs was obtained.

  Accordingly, the present invention provides a polishing composition capable of obtaining excellent characteristics in all of the surface roughness of the wafer, the shape of the wafer, and the flatness at the peripheral edge of the wafer without reducing the polishing rate. Objective.

  The polishing composition of the present invention that solves the above problems comprises a piperazine compound and a water-soluble polymer compound of polyvinyl alcohols.

  According to the present invention, since the polishing composition contains a piperazine compound and a water-soluble polymer compound of polyvinyl alcohols, the surface roughness of the wafer, the shape of the wafer, and the peripheral edge of the wafer can be reduced without reducing the polishing rate. Excellent characteristics can be obtained in all of flatness.

FIG. 1A is a cross-sectional view of a wafer showing a state of roll-up of the wafer after polishing, and FIG. 1B is a cross-sectional view of the wafer showing a state of roll-off of the wafer after polishing.

  Polishing composition COMP by embodiment of this invention contains the water-soluble high molecular compound which is polyvinyl alcohol, and a piperazine compound. The polishing composition COMP is used for polishing a silicon wafer.

  Polyvinyl alcohols are polymer compounds containing a structure represented by the following formula (1) as a repeating unit. The polyvinyl alcohols preferably contain the repeating unit of the following formula (1) as a main structural unit, and more preferably contain a majority of structural units. In addition, polyvinyl alcohol may contain structures other than the following Formula (1). Moreover, structures other than the following Formula (1) contained in polyvinyl alcohol may be contained as a repeating unit. Polyvinyl alcohols contain, for example, the structure of the following formula (1) as a repeating unit at a polymerization degree of 20 to 20000. Polyvinyl alcohols have, for example, an average weight molecular weight of 1,000 to 1,000,000.

  In the formula (1), X may be a hydroxy group (OH group). Moreover, in Formula (1), X may substitute a part of hydroxy group (OH group) by another functional group. That is, the polyvinyl alcohols may be unmodified polyvinyl alcohol or modified polyvinyl alcohol (polyvinyl alcohol derivative). When polyvinyl alcohol is unmodified polyvinyl alcohol, in the above formula (1), X is a hydroxy group. Further, when the polyvinyl alcohol is a modified polyvinyl alcohol, the polyvinyl alcohol includes a structure in which X in the above formula (1) substitutes a part of the hydroxy group (OH group) with another functional group. As polyvinyl alcohols, unmodified polyvinyl alcohol or modified polyvinyl alcohol may be used alone, or both may be used in combination.

  Examples of the modified polyvinyl alcohol include carboxy modified polyvinyl alcohol, sulfonic acid modified polyvinyl alcohol, phosphoric acid modified polyvinyl alcohol, silanol modified polyvinyl alcohol, epoxy modified polyvinyl alcohol, acetoacetyl modified polyvinyl alcohol, nitrile modified polyvinyl alcohol, pyrrolidone modified polyvinyl alcohol. , Silicone-modified polyvinyl alcohol, cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol and the like. Moreover, modified polyvinyl alcohol obtained by copolymerizing ethylene, vinyl ether having a long chain alkyl group, (meth) acrylamide, or the like is also included as the modified polyvinyl alcohol. Furthermore, as the modified polyvinyl alcohol, a compound obtained by cyclic acetalization of polyvinyl alcohol (for example, polyvinyl butyral, polyvinyl propiral, polyvinyl ethylal, polyvinyl methylal, etc.) is also included. One of these may be used as the modified polyvinyl alcohol, or two or more may be used in combination.

  Among these, as polyvinyl alcohol compounds, for example, polyvinyl alcohol represented by the following formula (2), butanediol vinyl alcohol represented by the following formula (3), polyvinyl acetate represented by the following formula (4), etc. Preferably used.

  The content of the polyvinyl alcohol in the polishing composition COMP is preferably 0.001% by weight or more, for example, from the viewpoint of improving the surface roughness characteristics. Moreover, it is preferable that content of polyvinyl alcohol in polishing composition COMP is 0.1 weight% or less from a viewpoint of suppressing the fall of a polishing rate, for example.

  It is preferable that the polishing composition COM does not contain a hydrophobic polymer compound. This is because if the hydrophobic polymer compound is blended in the polishing composition COMP, the shape of the wafer and the flatness characteristics of the peripheral edge of the wafer may be deteriorated. Here, the hydrophobic polymer compound means a polymer compound having hydrophobicity with respect to the wafer. Note that “having hydrophobicity with respect to the wafer” means a property in which the water-soluble matter does not easily spread on the surface of the wafer when the water-soluble matter of the hydrophobic polymer compound is placed on the wafer. Examples of such a hydrophobic polymer compound include compounds having an alkylenediamine structure such as ethylenediaminetetrapolyoxyethylenepolyoxypropylene (poloxamine).

  The piperazine compound is an amine compound having a cyclic amine structure. Examples of piperazine compounds include anhydrous piperazine, piperazine hexahydrate, 1- (2-aminoethyl) piperazine (AEP), N-methylpiperazine, 1- (2-hydroxyethyl) piperazine (piperazine-2-ethanol). (HEP). The structural formulas of 1- (2-aminoethyl) piperazine (AEP) and 1- (2-hydroxyethyl) piperazine (HEP) are represented by the following formulas (5) and (6), respectively.

  From the viewpoint of improving the polishing rate, the content of the piperazine compound in the polishing composition COMP is preferably 0.05% by weight or more, for example. Further, the content of the piperazine compound in the polishing composition COMP is, for example, 2.0% by weight or less from the viewpoint of suppressing a decrease in flatness of the surface of the wafer after polishing and a specific decrease in surface roughness. It is preferable.

  The polishing composition COMP may contain an amine compound other than the piperazine compound.

  As the abrasive grains, those commonly used in this field can be used, and examples thereof include colloidal silica, fumed silica, colloidal alumina, fumed alumina, cerium oxide, silicon carbide, and silicon nitride. Of these, colloidal silica is preferably used as the abrasive.

  In the embodiment of the present invention, it is preferable that the polishing composition COMP further contains an alkali compound. Examples of the alkali compound include hydroxides or carbonates of alkali metals or alkaline earth metal elements, quaternary ammonium and salts thereof, primary amines other than the piperazine compounds, secondary amines and tertiary amines. An amine etc. are mentioned. Specifically, examples of the alkali compound include potassium carbonate, potassium hydroxide, sodium hydroxide, sodium bicarbonate, sodium carbonate, ammonia, tetramethylammonium hydroxide, tetraethylammonium hydroxide, methylamine, dimethylamine, and trimethylamine. , Ethylamine, diethylamine, triethylamine, ethylenediamine, monoethanolamine, N- (β-aminoethyl) ethanolamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine and the like.

  In the embodiment of the present invention, it is preferable that the polishing composition COMP further contains a chelating agent. Examples of chelating agents include aminocarboxylic acid chelating agents and organic phosphonic acid chelating agents. Aminocarboxylic acid chelating agents include ethylenediaminetetraacetic acid (EDTA), ethylenediaminetetraacetic acid sodium, hydroxyethylenediaminetriacetic acid (HEDTA), hydroxyethylethylenediaminetriacetic acid sodium salt, diethylenetriaminepentaacetic acid (DTPA), diethylenetriaminepentaacetic acid sodium salt, triethylenetetramine Examples include hexaacetic acid, sodium triethylenetetramine hexaacetate, nitrilotriacetic acid (NTA), sodium nitrilotriacetate, ammonium nitrilotriacetate, and triethylenetriaminepentaacetic acid (TTHA). Organic phosphonic acid chelating agents include 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri (methylenephosphonic acid), ethylenediaminetetrakis (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid) Ethane-1,1, -diphosphonic acid, ethane-1-hydroxy-1,1,2-triphosphonic acid, ethane-1,2-dicarboxy-1,2-diphosphonic acid, methanehydroxyphosphonic acid, and 2- Phosphonobutane-1,2-dicarboxylic acid and the like are included.

  In addition to the above, the polishing composition COMP can optionally contain any compounding agent generally known in the field of polishing compositions, such as a pH adjuster and a surfactant.

  Polishing composition COMP is produced by mixing water-soluble polymer compounds of polyvinyl alcohols, piperazine compounds, and other compounding materials as appropriate, and adding water. Or polishing composition COMP is produced by mixing the water-soluble polymer compound of polyvinyl alcohol, a piperazine compound, and another compounding material in water one by one. As means for mixing these components, means commonly used in the technical field of polishing compositions such as a homogenizer and ultrasonic waves are used.

  The polishing composition COMP described above is diluted with water (for example, deionized water) so as to have an appropriate concentration, and then used for polishing a silicon wafer.

  In the polishing composition COMP of the present invention, the chelating agent and the alkaline compound are not essential components. Even in the case where at least one of a chelating agent and an alkaline compound is not blended in the polishing composition COMP, it has excellent characteristics in terms of surface roughness, shape deterioration amount, and flatness of the peripheral portion of the wafer without reducing the polishing rate. Can be obtained.

  In the polishing composition COMP of the invention, the abrasive grains are not an essential component. Even in the case where abrasive grains are not blended in the polishing composition COMP, excellent characteristics can be obtained in terms of surface roughness, shape deterioration amount and flatness of the peripheral edge of the wafer without reducing the polishing rate.

  Hereinafter, the present invention will be described in detail using examples.

  Table 1 shows the components of the polishing compositions of Examples 1 to 8. In Table 1, the weight% of each component represents the weight% with respect to the entire polishing composition (stock solution).

The polishing composition of Example 1 comprises 3.0% by weight abrasive grains (colloidal silica), 0.25% by weight 1- (2-aminoethyl) piperazine (AEP), 0.03% by weight polyvinyl alcohol. (PVA), 0.6% by weight of potassium carbonate (K ₂ CO ₃ ), and 0.01% by weight of diethylenetriaminepentaacetic acid (DTPA) are mixed in water to make a total of 100 parts by weight. This polishing composition (stock solution) was diluted 10 times with deionized water, and the wafer was polished as a polishing liquid. The average primary particle diameter (BET method) of the abrasive grains used here is 35 nm, and the average secondary particle diameter is 70 nm. The degree of polymerization of the used polyvinyl alcohol is about 500.

  The polishing compositions (stock solutions) of Example 2 and Example 3 have the same composition as Example 1 except that the blending amounts of AEP were 0.5% by weight and 1% by weight, respectively.

  The polishing compositions (stock solutions) of Example 4 and Example 5 have the same composition as Example 2 except that the blending amounts of PVA were 0.01% by weight and 0.05% by weight, respectively. .

  The polishing composition (stock solution) of Example 6 has the same composition as Example 2 except that it does not contain potassium carbonate. That is, the polishing composition of Example 6 does not contain an alkali compound.

  The polishing composition (stock solution) of Example 7 has the same composition as Example 2 except that the content of colloidal silica was 6.0% by weight.

  The polishing composition (stock solution) of Example 8 has the same composition as Example 2 except that 0.03% by weight of butanediol vinyl alcohol was blended in place of PVA. Here, the weight average molecular weight of the butanediol vinyl alcohol used is about 20,000.

  Next, Table 2 and Table 3 show the components of the polishing compositions of Comparative Examples 1 to 11. In Table 2 and Table 3, the weight% of each component represents the weight% with respect to the whole polishing composition (stock solution).

  The polishing composition of Comparative Example 1 has the same composition as Example 2 except that it does not contain AEP. That is, the polishing composition of Comparative Example 1 does not contain an amine compound.

  The polishing composition of Comparative Example 2 has the same composition as Comparative Example 1 except that it does not contain PVA. That is, the polishing composition of Comparative Example 2 contains neither an amine compound nor a water-soluble polymer compound.

  The polishing composition of Comparative Example 3 has the same composition as Example 2 except that it does not contain PVA. That is, the polishing composition of Comparative Example 3 does not contain a water-soluble polymer compound.

  The polishing composition of Comparative Example 4 has the same composition as that of Example 2 except that 0.01% by weight of hydroxyethyl cellulose (HEC) was blended instead of PVA. Here, the weight average molecular weight of the used HEC is about 800,000. The polishing composition of Comparative Example 4 does not contain a water-soluble polymer compound of polyvinyl alcohol.

  The polishing composition of Comparative Example 5 has the same composition as Comparative Example 4 except that the HEC content was 0.03% by weight.

  The polishing composition of Comparative Example 6 was blended with 0.005% by weight of ethylenediaminetetrapolyoxyethylenepolyoxypropylene (poloxamine), which is a hydrophobic polymer compound, instead of PVA, which is a water-soluble polymer compound, and It has the same composition as Example 2 except not containing potassium carbonate.

  Each of the polishing compositions of Comparative Examples 7 to 10 was further polished by the compositions of Example 1, Example 2, Example 3 and Example 7, except that 0.004 part by weight of poloxamine was further added. Have the same composition as each of the objects. In the polishing compositions of Comparative Examples 7 to 10, PVA (water-soluble polymer compound) and poloxamine (hydrophobic polymer compound) are used in combination as polymer compounds.

  The polishing composition of Comparative Example 11 has the same composition as the polishing composition of Example 2 except that 0.50% by weight of guanidine carbonate was blended instead of AEP. Here, the used guanidine carbonate is a trade name “guanidine carbonate” manufactured by Tokyo Chemical Industry Co., Ltd. The polishing composition of Comparative Example 11 contains a compound other than the piperazine compound as the amine compound.

(Polishing rate evaluation)
For polishing of Examples 1 to 8 and Comparative Examples 1 to 11 on a polishing pad made of nonwoven fabric (SUBATM400, manufactured by Nittah Haas) using a polishing apparatus (SPP800S single-side polishing machine, manufactured by Okamoto Machine Tool Works) The composition is supplied at a rate of 0.6 L / min, and the polishing platen is rotated at a rotation speed of 33 rpm while applying a pressure of 110 gf / cm ² to a silicon wafer having a diameter of 12 inches, and the carrier is rotated at a rotation speed of 30 rpm. Polishing was carried out for 4 minutes while rotating at. The rocking speed of the lower base plate of the polishing apparatus was 500 mm / min, and the rocking distance was 40 mm. The silicon wafer used had a P-type conductivity, a crystal orientation of <100>, and a resistivity of 0.1 Ω · cm or more and less than 100 Ω · cm.

  After the polishing, the difference in thickness of the silicon wafer removed by polishing was measured using a wafer flatness inspection apparatus (Nanometro 300TT-A, manufactured by Kuroda Seiko Co., Ltd.). The polishing rate was evaluated by the thickness (μm / min) of the silicon wafer removed by polishing per unit time.

Further, the characteristics of the polishing rate were evaluated by the following symbols “◎”, “◯”, and “×” according to the value of the polishing rate.
A: 0.30 μm / min or more O: 0.15 μm / min or more and less than 0.30 μm / min X: Less than 0.15 μm / min

(Wafer shape evaluation: Shape deterioration amount)
In order to evaluate the polished wafer shape, GBIR (Global Backside Ideal Range) was measured using a wafer flatness inspection apparatus (Nanometro 300TT-A, Kuroda Seiko Co., Ltd.). This GBIR is obtained by measuring the difference between the actual surface and the ideal plane with respect to the back surface for the entire front surface of the wafer, and calculating the range of these deviations. It can be treated as an index of the overall flatness of the wafer surface excluding.

And the value computed by the following formula | equation was evaluated as a shape deterioration amount. The “polishing allowance (A)” in the equation is a value obtained from the difference in average thickness of the wafer before and after polishing measured by the above-described wafer flatness inspection apparatus. Regarding the value of the shape deterioration amount, it can be determined that the smaller the numerical value, the better the characteristics.
[Shape deterioration amount] = [GBIR] / [Polishing allowance (A)]

In addition, according to the value of the shape deterioration amount, the characteristics of the shape deterioration amount were evaluated by the following symbols “◎”, “◯”, and “×”.
◎: Less than 0.15 ○: 0.15 or more and less than 0.30 ×: 0.3 or more

(Wafer shape evaluation: roll-off amount (RoA))
Further, using the above-described wafer flatness inspection apparatus, the polishing allowance (hereinafter also referred to as “polishing allowance D1”, see FIG. 1) at a location 10 mm from the outer periphery of the wafer, and from the outer periphery of the wafer. The polishing allowance (hereinafter also referred to as “polishing allowance D2”, see FIG. 1) at a location of 1 mm was measured. Then, the difference between the polishing allowance D1 and the polishing allowance D2 was evaluated as a roll-off amount (RoA).
[RoA] = [Polishing allowance D1]-[Polishing allowance D2]

  FIGS. 1A and 1B are cross-sectional views of the wafer W for explaining the evaluation of the value of RoA. In FIGS. 1A and 1B, a region indicated by a broken line indicates a portion P removed by polishing. A hatched area indicates a cross section of the wafer W after polishing. As for the value of RoA, when RoA takes a positive value (that is, when the value of the polishing allowance D1 is larger than the value of the polishing allowance D2), the final shape of the wafer W is a roll-up in which the peripheral edge is bounced up. It becomes the shape of. Conversely, when RoA takes a negative value (that is, when the value of the polishing allowance D1 is smaller than the value of the polishing allowance D2), the peripheral shape of the final shape of the wafer W is polished more than inward. It becomes a roll-off shape. In other words, when the value of RoA is 0, it means that polishing is ideally performed uniformly at the peripheral edge of the wafer W.

Further, the flatness of polishing at the peripheral edge of the wafer was evaluated by the following symbols “◎”, “◯”, and “×” according to the value of the roll-off amount.
A: 0 μm or more and less than 0.05 μm ○: 0.05 μm or more and less than 0.10 μm ×: 0.10 μm or more

(Surface roughness evaluation)
As the evaluation of the surface roughness Ra, using the non-contact surface roughness measuring machine (Wyko NT9300, manufactured by Veeco), the polishing compositions according to Examples 1 to 8 and Comparative Examples 1 to 11 were used. The surface roughness of each wafer after polishing the silicon wafer was measured.

Further, according to the value of the surface roughness, the characteristics of the surface roughness were evaluated by the following symbols “◎”, “◯” and “×”.
◎: Less than 0.25 nm ○: 0.25 nm or more and less than 0.34 nm ×: 0.34 nm or more

(Evaluation results)
Using the polishing compositions according to Examples 1 to 8 and Comparative Examples 1 to 11, the above-described polishing rate (RR), surface roughness (Ra), shape deterioration amount, and roll-off amount (RoA) Table 4 to Table 6 show the results measured for the above.

  Referring to Table 4 and Table 5, when Examples 1 to 8 are compared with Comparative Examples 1 and 2, Comparative Example 1 and Comparative Example 2 that do not include an amine compound include an amine compound. It can be seen that the polishing rate is lower than in Examples 1 to 8. This shows that the amine compound contributes to obtaining a good polishing rate in the polishing composition.

  When comparing Example 1 to Example 8 and Comparative Example 3 with reference to Table 4 and Table 5, Comparative Example 3 containing neither a water-soluble polymer compound nor a hydrophobic polymer compound was water-soluble. It turns out that the characteristic of surface roughness is falling rather than Example 1- Example 8 containing a conductive polymer compound. This shows that the water-soluble polymer compound of the polishing composition contributes to obtaining excellent characteristics with respect to the surface roughness of the polished wafer.

  Referring to Tables 4 and 5, when Examples 1 to 8 are compared with Comparative Examples 4 and 5, Comparative Examples 4 and 5 that do not contain polyvinyl alcohol as a water-soluble polymer compound. In Example 1, it can be seen that RoA is larger than in Examples 1 to 8 containing polyvinyl alcohols, and the flatness at the peripheral edge of the wafer is reduced. From this, it can be seen that, among the water-soluble polymer compounds, in particular, the polyvinyl alcohol improves the flatness at the peripheral portion of the wafer.

The present inventors considered as follows that the roll-off characteristics of a polished wafer are improved when polyvinyl alcohol is blended in the polishing composition. A silicon oxide film (SiO ₂ ) was formed on the surface of the silicon wafer before polishing, and it was analyzed that the adsorptivity of the water-soluble polymer compound to the silicon oxide film was related to roll-off characteristics.

  When the polymer compound is not a polyvinyl alcohol (for example, in the case of a cellulose derivative or an alkylene oxide copolymer), the polymer compound has high adsorptivity to the silicon oxide film. Since the amount of dispersion of the polishing liquid at the peripheral edge of the wafer increases due to the centrifugal force during polishing, the amount of the polymer compound adsorbed on the silicon oxide film of the polishing liquid is greater at the peripheral edge of the wafer than at the center of the wafer. It will be. Therefore, it is considered that the silicon oxide film protected by the polymer compound is difficult to be polished at the peripheral portion of the wafer, and the polishing allowance at the peripheral portion of the wafer is reduced.

  On the other hand, polyvinyl alcohols have lower adsorptivity to silicon oxide films than celluloses and alkylene oxide copolymers. Therefore, polyvinyl alcohols are not adsorbed to the silicon oxide film even in the peripheral portion of the wafer as in the case of cellulose derivatives and alkylene oxide copolymers. Therefore, it is considered that the difference in the polishing allowance between the peripheral portion of the wafer and the inside thereof becomes small, and as a result, good roll-off characteristics can be obtained.

  When comparing Example 1 to Example 8 with Comparative Example 6 to Comparative Example 10 with reference to Tables 4 to 6, in Comparative Examples 6 to 10 containing a hydrophobic polymer compound, It can be seen that both the shape deterioration amount and the properties of RoA are lower than those of Examples 1 to 8 which do not contain a conductive polymer compound. Therefore, it can be seen that the hydrophobic polymer compound is preferably not blended in the polishing composition from the viewpoint of the shape deterioration amount and the flatness of the peripheral edge of the wafer.

  The present inventors considered as follows that the performance deteriorates in terms of the shape deterioration amount when a hydrophobic polymer compound is blended in the polishing composition.

  First, as a polymer compound, regarding the mechanism of polishing when a water-soluble polymer compound is blended in the polishing composition, a portion (convex portion) that contacts the polishing pad on the surface of the wafer, and a polishing pad Consider separately the parts that do not contact (wafer recesses). In the portion of the wafer surface that comes into contact with the polishing pad (the convex portion of the wafer), the polymer compound in the polishing liquid is detached from the polishing liquid by friction due to contact with the polishing pad. Therefore, the convex part of the wafer is polished by the chemical etching action by the amine compound in the polishing liquid and the mechanical polishing action by the abrasive grains. On the other hand, the water-soluble polymer compound wets and spreads on the surface of the wafer and protects the surface of the wafer at a portion of the wafer surface that does not come into contact with the polishing pad (a concave portion of the wafer). Therefore, the concave portion of the wafer becomes difficult to be chemically or mechanically polished due to the protective effect of the wafer by the water-soluble polymer compound. Therefore, when the polishing composition contains a water-soluble polymer compound, the convex portion of the wafer is easily polished, and the concave portion is difficult to be polished, so that good flatness can be obtained as a whole wafer.

  On the other hand, regarding the mechanism of the occurrence of polishing when a hydrophobic polymer compound is blended in the polishing composition as the polymer compound, the portion of the wafer surface that contacts the polishing pad (convex portion) and the polishing pad Consider separately the parts that do not contact (wafer recesses). The hydrophobic polymer compound has a property that it is difficult to wet and spread on the surface of the wafer as compared with the water-soluble polymer compound. Therefore, it is considered that the hydrophobic polymer compound does not exist uniformly on the surface of the wafer.

  At the portion of the wafer surface that comes into contact with the polishing pad (the convex portion of the wafer), as in the case of the water-soluble polymer compound, the polymer compound in the polishing liquid comes into contact with the polishing pad and is removed from the polishing liquid by friction. Detach. Therefore, the convex part of the wafer is polished by the chemical etching action by the amine compound in the polishing liquid and the mechanical polishing action by the abrasive grains.

  On the other hand, the state of the hydrophobic polymer compound in the portion of the wafer surface that does not come into contact with the polishing pad (wafer recess) will be considered. As described above, since the hydrophobic polymer compound has low uniform dispersibility on the wafer surface, there are variations in the abundance in the recesses of the wafer. For this reason, in the portion where the amount of the hydrophobic polymer compound is large in the wafer recess, the hydrophobic polymer compound sufficiently exhibits the effect of protecting the surface of the wafer, and the progress of polishing is suppressed. On the other hand, since the hydrophobic polymer compound is less effective in protecting the wafer surface at the portion where the amount of the hydrophobic polymer compound is small in the concave portion of the wafer, the effect of suppressing the progress of polishing. Also lower. Therefore, the low wettability of the hydrophobic polymer compound appears as a variation in polishing progress in the polished wafer. In other words, the polished state of the wafer after polishing is more non-uniform than the water-soluble polymer compound having high wettability on the surface of the wafer. Therefore, when the polishing composition contains a hydrophobic polymer compound, good flatness cannot be obtained as compared with the case of the water-soluble polymer compound (that is, the shape deterioration amount and the RoA characteristics are lowered). )

  Referring to Table 4 and Table 6, when Examples 1 to 8 containing a piperazine compound were compared with Comparative Example 11, a comparative example in which guanidine carbonate (that is, an amine compound other than the piperazine compound) was blended. 11 shows that the three characteristics of the surface roughness, the shape deterioration amount, and the RoA do not satisfy satisfactory levels.

  With reference to Table 4, from the evaluation results of Examples 1 to 3 in which the blending amount of AEP is different, polishing was performed in the range where the concentration of AEP in the stock solution of the polishing composition was 0.25 to 1.00% by weight. It was confirmed that excellent performance can be obtained in all of the surface roughness, the shape deterioration amount, and the roll-off characteristics without reducing the speed.

  Referring to Table 4, from the evaluation results of Example 2, Example 4 and Example 5 in which the blending amount of PVA is different, the concentration of PVA in the stock solution of the polishing composition is 0.01 to 0.05% by weight. In the range, it was confirmed that excellent performance can be obtained in all of the surface roughness, the shape deterioration amount, and the roll-off characteristics without reducing the polishing rate.

  Referring to Table 4, from the evaluation results of Example 2 and Example 6 in which the presence or absence of potassium carbonate is different, when AEP and PVA are blended in the polishing composition, whether or not potassium carbonate is blended Regardless of this, it was confirmed that excellent performance can be obtained in all of the surface roughness, the shape deterioration amount, and the roll-off characteristics without reducing the polishing rate.

  Referring to Table 4, from the evaluation results of Example 2 and Example 7 in which the blending amount of abrasive grains is different, even when the blending amount of abrasive grains is increased, AEP and PVA are blended in the polishing composition It was confirmed that excellent performance can be obtained in all of the surface roughness, the shape deterioration amount, and the roll-off characteristics.

  Referring to Table 4, when both the water-soluble polymer compounds are polyvinyl alcohols and the types are different, the evaluation results of Example 2 and Example 8 show that the polyvinyl alcohols are blended in the polishing composition. It was confirmed that excellent performance can be obtained in all of the surface roughness, the shape deterioration amount, and the roll-off characteristics without reducing the polishing rate.

  From the above evaluation results, the polishing composition contains a water-soluble polymer compound and a piperazine compound of polyvinyl alcohol, so that the surface roughness, the shape deterioration amount, and the roll-off characteristics are all reduced without reducing the polishing rate. It can be seen that excellent performance can be obtained.

  As mentioned above, embodiment mentioned above is only the illustration for implementing this invention. Therefore, the present invention is not limited to the above-described embodiment, and can be implemented by appropriately modifying the above-described embodiment without departing from the spirit thereof.

  The polishing composition according to this embodiment of the present invention contains a water-soluble polymer compound of polyvinyl alcohols and a piperazine compound.

  The polishing composition according to this embodiment of the present invention preferably does not contain a hydrophobic polymer compound.

  The polishing composition according to this embodiment of the present invention may further contain abrasive grains.

  The polishing composition according to this embodiment of the present invention may further contain an alkaline compound and a chelating agent.

  The present invention can be used for polishing compositions.

Claims (3)

A water-soluble polymer compound of polyvinyl alcohol;
A piperazine compound;
A polishing composition comprising: The polishing composition according to claim 1,
Polishing composition which does not contain hydrophobic polymer compound. In the polishing composition according to claim 1 or 2,
Furthermore, polishing composition containing an abrasive grain.

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