JP5413456B2 - Polishing liquid for semiconductor substrate and method for polishing semiconductor substrate - Google Patents

Description

  The present invention relates to a semiconductor substrate polishing liquid suitable for semiconductor substrate surface processing, and a semiconductor substrate polishing method.

  In the polishing process of a semiconductor substrate typified by silicon, generally, a lapping process for smoothing unevenness of a surface generated by slicing and a uniform thickness in a substrate surface, and finishing to a desired surface accuracy are performed. There is a polishing process (polishing process). The polishing process is further divided into a primary polishing process called rough polishing and a final polishing process called precision polishing. In some cases, the primary polishing process is further divided into two processes called a primary polishing process and a secondary polishing process.

  The polishing process is used not only for the manufacturing process of a normal semiconductor substrate but also for reprocessing a used semiconductor substrate. In recent years, it has been studied to use a polishing process in the manufacture of a semiconductor substrate having a structure called a through silicon via (TSV).

  The structure called TSV is a structure in which an electrode for connecting a device formed on the surface layer of a semiconductor substrate and the back surface of the semiconductor substrate is formed so as to penetrate the inside of the semiconductor substrate. Conventionally, when a plurality of semiconductor elements are stacked to form one semiconductor device (semiconductor package), the upper and lower semiconductor elements are connected by wire bonding. By adopting the above TSV structure instead of this wire bonding connection, the area required for the connection between the upper and lower semiconductor elements can be made smaller. Therefore, the technique for forming the TSV replaces the wire bonding. It is expected as a new technology.

  As a process for forming a TSV, it is considered that a process of forming a via in a semiconductor substrate, grinding a back surface of the surface on which the via is formed (back grinding), and penetrating the via is generally considered. The use of CMP (Chemical Mechanical Polishing) in the step of polishing the back surface has been studied (for example, see Non-Patent Document 1 below). From the viewpoint of manufacturing efficiency, a high polishing rate is required for the polishing liquid used in the polishing process on the back surface.

  By the way, conventionally, various polishing liquids have been proposed as polishing liquids for polishing silicon (Si), which is a typical material for forming a semiconductor substrate. For example, Patent Document 1 below shows that colloidal silica and silica gel are useful as a polishing agent for the surface of a semiconductor crystal that is most frequently used in the manufacture of semiconductor devices. Patent Document 1 below describes that the primary particles of colloidal silica and silica gel used have a particle size of 4 to 200 nm.

  In the following Patent Document 2, the use of a combination of either silica or silica gel in a colloidal form with a primary particle size of 4 to 200 nm, preferably 4 to 100 nm, and a water-soluble amine as a polishing agent. It has been disclosed that a substrate, particularly a silicon semiconductor substrate surface, can be effectively polished. The amount of amine with respect to silica present in the silica sol or gel is 0.5-5.0% by weight, preferably 1.0-5.0% by weight, most preferably 2.0-4.0% by weight. ing.

  Patent Document 3 below discloses an aqueous silica composition to which 0.1 to 5.0% by mass (most preferably 2.0 to 4.0% by mass) of a water-soluble quaternary ammonium salt or quaternary ammonium base is added. It has been shown that the use can improve the polishing rate of the silicon substrate.

The following Patent Document 4 discloses a method of polishing a silicon or germanium semiconductor material to a high surface finish. In the technique described in Patent Document 4 below, a polishing liquid having a modified colloidal silica gel, a silica concentration of about 2 to about 50 mass%, and a pH of 11 to 12.5 is used as a polishing liquid. use. In the modification treatment of colloidal silica gel, the surface of the silica particles having a specific surface area of about 25 to 600 m ² / g is formed by chemically bonding aluminum atoms with 100 atoms of aluminum atoms per 100 silicon atoms on the surface of the uncoated particles. It is coated so that there are about 1 to about 50 surface coatings. In general, in the region where the pH is 11 or more, the silica as the abrasive particles is depolymerized to become an alkali silicate, and the pH is lowered. However, Patent Document 4 describes that pH does not occur without causing depolymerization. It has been shown that polishing can be rapidly performed in a region of 11 or more.

Patent Document 5 listed below includes piperazine or piperazine having a lower alkyl substituent on nitrogen and an aqueous colloidal silica sol or gel, and piperazine is contained in an amount of 0.1 to 5% by mass based on the SiO ₂ content of the sol. A polishing liquid is disclosed. Patent Document 5 listed below discloses a silicon wafer and a polishing method for a material similar to the silicon wafer. According to Patent Document 5, it is said that when piperazine is contained in the polishing liquid, an equivalent polishing rate can be obtained with a small amount of colloidal silica as compared with the case where aminoethylethanolamine is used. Patent Document 5 listed below describes that a strongly basic piperazine system can reduce the amount of caustic alkali added to adjust the pH.

  Patent Document 6 below discloses a polishing composition comprising an abrasive, at least one of azoles and derivatives thereof, and water. Patent Document 6 below describes that the polishing ability of the polishing composition is improved by adding azoles and derivatives thereof to the polishing composition. For this reason, it is pointed out that the unshared electron pair of the nitrogen atom of the hetero five-membered ring directly acts on the object to be polished, and specifically, an example in which imidazole is applied is disclosed.

  Patent Document 7 listed below discloses a polishing liquid containing water, a water-soluble polymer such as colloidal silica and polyacrylamide, and a water-soluble salt such as calcium chloride as a polishing liquid for reducing irregularities on the surface of the semiconductor substrate. Has been. However, when the polishing liquid described in Patent Document 7 is used, there arises a problem that the polishing rate is lowered due to the addition of the water-soluble polymer, and the processing time is increased.

In the following Patent Document 8, as a polishing liquid for reducing LPD (light point defect) which is a kind of defect, the concentration of either sodium ion or acetate ion in the polishing composition is 10 ppb or less, or for polishing The concentration of sodium ion and acetate ion in the composition is 10 ppb or less,
The polishing composition discloses a polishing liquid that preferably contains a water-soluble polymer such as hydroxyethyl cellulose, an alkali such as ammonia, and abrasive grains such as colloidal silica. The polishing liquid described in Patent Document 8 contains hydroxyethyl cellulose and polyvinyl alcohol as water-soluble polymers, and shows that LPD improves as the concentration of sodium ions and acetate ions decreases. However, since the addition amount of the water-soluble polymer shown in the examples is 0.002% by mass or less, when the polishing liquid described in Patent Document 8 is used, defects other than LPD (for example, irregularities on the substrate surface) Effects such as reduction are considered to be insufficient.

U.S. Pat. No. 3,170,273 U.S. Pat. No. 4,169,337 U.S. Pat. No. 4,462,188 Japanese Patent Publication No.57-58775 JP 62-30333 A JP 2006-80302 A Japanese Patent Laid-Open No. 02-158684 JP 2008-53414 A

OKI Technical Review October 2007 / No. 211 VOL. 74 No. 3

  The polishing process of the semiconductor substrate is divided into a plurality of processes to reduce the processing time, improve the efficiency and improve the quality. The purpose of each polishing process is different, and the polishing process is used in each polishing process. The characteristics of the polishing liquid are also different.

  At the rough polishing stage, the purpose is to eliminate relatively large irregularities generated in the lapping process or the like, and to remove the damaged semiconductor substrate portion, and therefore, a high polishing rate is required.

  On the other hand, in the final polishing, the major objectives are high-level smoothing of the surface that could not be achieved by rough polishing and reduction of defects in the semiconductor substrate.

  In order to satisfy the above-mentioned characteristics, various polishing liquids and polishing methods have been invented as shown in the prior art. However, the above-mentioned characteristics are not sufficiently satisfied, and further improvements in the polishing liquid and the polishing method are further achieved. It has been demanded.

  When polishing a material for forming a semiconductor substrate such as silicon, it is effective to increase the pH of the polishing liquid in order to increase the polishing rate. However, such polishing liquids often vary in their polishing characteristics. That is, although the polishing liquid has the same composition, polishing characteristics such as polishing rate, scratches, flatness, and in-plane uniformity may not be stable. In addition, when a polishing liquid with an increased amount of abrasive particles is used, there are problems of generation of scratches due to abrasive grains and an increase in cost in disposal processing.

  A first object of the present invention is to provide a semiconductor substrate polishing liquid and semiconductor capable of reducing the processing time of a semiconductor substrate, facilitating process management, and processing a semiconductor substrate with uniform quality by high-speed and stable polishing. A semiconductor substrate polishing method using a substrate polishing liquid is provided.

  A second object of the present invention is to provide a polishing liquid for a semiconductor substrate and a polishing method for the polishing liquid for a semiconductor substrate capable of polishing the surface of a semiconductor substrate to a smooth surface with few irregularities and having few defects. There is.

  The third object of the present invention is to provide a polishing liquid for a semiconductor substrate and a polishing liquid for a semiconductor substrate capable of polishing the surface of a semiconductor substrate into a smooth surface with few irregularities with a practical polishing rate and a small polishing amount. A polishing method is provided.

The present inventors have found that when silica (SiO ₂ ) is used for the abrasive particles, the pH of the polishing liquid decreases with time, and the polishing rate can decrease. Furthermore, the present inventors have found that by using a predetermined additive together with silica, the pH and polishing rate can be controlled, and the roughness of the substrate surface after polishing can be reduced, leading to the present invention.

<First polishing liquid for semiconductor substrate (first invention)>
The first polishing liquid for a semiconductor substrate according to the present invention contains abrasive particles, 1,2,4-triazole, and a basic compound, and the basic compound is a nitrogen-containing basic compound or an inorganic basic compound. The basic compound content is 0.1% by mass or more, and the pH is 9 or more and 12 or less.

  According to the first invention, a semiconductor substrate made of a material typified by silicon or the like can be polished at high speed. In addition, according to the first aspect of the present invention, since the decrease in pH of the polishing liquid during storage and use can be suppressed, the decrease and fluctuation in the polishing rate can be extremely reduced.

  In the first invention, the basic compound acts as a solubilizer for obtaining a polishing rate. And there exists a tendency for polishing rate to become high, so that there is much addition amount of the basic compound in the polishing liquid for semiconductor substrates. From the viewpoint of obtaining a high polishing rate, the content of the basic compound is preferably 0.15% by mass or more, and more preferably 0.2% by mass or more. Further, from the viewpoint of suppressing deterioration in surface roughness due to an increase in etching and depolymerization of silica, the content of the basic compound is preferably 5% by mass or less, and more preferably 2% by mass or less.

  In the first invention, the nitrogen-containing basic compound preferably contains ammonium hydroxide or tetramethylammonium hydroxide. In the first invention, the inorganic basic compound preferably contains potassium hydroxide or sodium hydroxide. These basic compounds are excellent in that they have a low odor.

<Second polishing liquid for semiconductor substrate (second invention)>
The second polishing liquid for a semiconductor substrate according to the present invention contains a modified silica whose surface is modified with aluminate and an inorganic basic compound, and the content of the modified silica is 0.01% by mass or more. 5 mass% or less, and pH is 9 or more and 12 or less.

  According to the second invention, a semiconductor substrate made of a material typified by silicon or the like can be polished at a high speed. Therefore, in the present invention, the processing time of the semiconductor substrate can be reduced.

  In the second invention, the primary particle diameter of the modified silica is preferably 7 to 50 nm.

  When the primary particle diameter of the modified silica is 7 nm or more, it becomes easy to obtain a practical polishing rate. Moreover, it becomes easy to suppress generation | occurrence | production of polishing defects, such as a damage | wound, when the primary particle diameter of modified silica is 50 nm or less.

  In the second invention, the inorganic basic compound preferably contains potassium hydroxide or sodium hydroxide.

  As described above, also in the second invention, the inorganic basic compound acts as a solubilizer for obtaining a polishing rate. And there exists a tendency for polishing rate to become high, so that there is much addition amount of the inorganic basic compound in the polishing liquid for semiconductor substrates. In the second invention, the surface potential of the modified silica (abrasive particles) is maximized by the combination of the modified silica and the inorganic basic compound, so that the polishing rate can be increased. Among inorganic basic compounds, potassium hydroxide or sodium hydroxide is excellent in terms of low odor.

  The second invention preferably further contains 1,2,4-triazole.

  Thereby, since the fall of pH of polishing liquid at the time of a preservation | save or use can be suppressed and the quality of polishing liquid is stabilized, the fall and fluctuation | variation of polishing rate can be made very small. As a result, stable polishing, easy process management, and processing of semiconductor substrates with uniform quality are possible.

  Further, as an invention relating to a method for polishing a semiconductor substrate, the present invention is a method for polishing a semiconductor substrate for forming a through silicon via, the step of forming an uneven portion on one surface of the silicon substrate, A step of embedding metal, a step of back grinding the other surface of the silicon substrate, and a polishing step of polishing the other surface so that the metal is exposed using the first or second polishing liquid for a semiconductor substrate. A method for polishing a semiconductor substrate comprising:

  Thereby, the silicon damage layer after back grinding, which is generated in the process of forming the through silicon via, can be sufficiently flattened while maintaining a good polishing rate.

  In addition, as an invention related to a method for polishing a semiconductor substrate, the present invention includes a step of lapping or grinding a silicon wafer obtained by slicing a silicon single crystal ingot, and then etching the silicon wafer to prepare a rough wafer. And a rough polishing step of polishing a rough wafer using the first or second semiconductor substrate polishing liquid. In the present application, the final polishing process for finishing a silicon wafer as a product is referred to as “finish polishing”, and the polishing process performed as a pre-stage of final polishing is referred to as “rough polishing”.

  With such a semiconductor substrate polishing method, the surface of the semiconductor substrate can be polished at high speed.

  As an invention relating to a semiconductor substrate polishing method, the present invention further relates to a semiconductor substrate polishing method for reuse, the step of performing wet etching on a silicon wafer to which deposits have adhered, and the first or second method. There is provided a method for polishing a semiconductor substrate, comprising: a rough polishing step for polishing a wet-etched silicon wafer using a semiconductor substrate polishing liquid.

  With such a method of polishing a semiconductor substrate, unnecessary deposits are removed from the surface of a semiconductor substrate (such as a test wafer) collected for reuse, and a smooth surface with few irregularities is polished at high speed. It becomes possible to do.

<Third semiconductor substrate polishing liquid (third invention)>
The third polishing liquid for a semiconductor substrate according to the present invention contains abrasive particles, 1,2,4-triazole, a water-soluble polymer, and a basic compound, and has a pH of 9 or more and 12 or less.

  According to the third invention, the surface of the semiconductor substrate made of a material typified by silicon or the like can be polished to a smooth surface with few irregularities.

  In addition, it is preferable that content of water-soluble polymer is 0.001 mass% or more and 10 mass% or less with respect to the total mass of the polishing liquid for semiconductor substrates. Moreover, it is preferable that content of 1,2,4-triazole is 0.01 mass% or more and 10 mass% or less with respect to the total mass of the polishing liquid for semiconductor substrates.

  By setting the content of the water-soluble polymer and 1,2,4-triazole in the above range, the surface of the semiconductor substrate can be more reliably polished to a smooth surface with less unevenness.

<Fourth polishing liquid for semiconductor substrate (fourth invention)>
The fourth polishing liquid for a semiconductor substrate according to the present invention contains abrasive particles, 1,2,4-triazole, a water-soluble polymer, and a basic compound, and contains 1,2,4-triazole. The amount is 0.05% by mass or more and 0.5% by mass or less based on the total mass of the polishing liquid for semiconductor substrate, and the content of the water-soluble polymer is based on the total mass of the polishing liquid for semiconductor substrate. 0.001 mass% or more and 0.1 mass% or less, and pH is 9 or more and 12 or less.

  As a result, the surface of the semiconductor substrate made of a material typified by silicon or the like can be polished to a smooth surface with few irregularities and few defects.

  Further, as an invention relating to a method for polishing a semiconductor substrate, the present invention includes a step of preparing a rough wafer by etching a silicon wafer after wrapping or grinding a silicon wafer obtained by slicing a silicon single crystal ingot; A method for polishing a semiconductor substrate, comprising: a polishing step for polishing a rough wafer; and a final polishing step for further polishing the silicon wafer after the rough polishing step using a third or fourth polishing liquid for a semiconductor substrate. .

  As a result, it is possible to sufficiently eliminate the minute irregularities present on the silicon wafer and to polish the surface with few defects.

  Further, as an invention relating to a method for polishing a semiconductor substrate, the present invention relates to a method for polishing a semiconductor substrate for reuse. The method includes wet etching a silicon wafer to which deposits have adhered, and a wet-etched silicon wafer. A method for polishing a semiconductor substrate comprising: a rough polishing step for polishing; and a final polishing step for further polishing a silicon wafer after the rough polishing step using a third or fourth polishing liquid for a semiconductor substrate.

  With such a method of polishing a semiconductor substrate, unnecessary deposits are removed from the surface of a semiconductor substrate (such as a test wafer) collected for reuse, and minute irregularities existing on the silicon wafer are eliminated. Therefore, a reusable semiconductor substrate with few defects can be provided.

<Fifth semiconductor substrate polishing liquid (fifth invention)>
The fifth polishing liquid for a semiconductor substrate according to the present invention contains abrasive particles, 1,2,4-triazole, a water-soluble polymer, and a basic compound, and contains 1,2,4-triazole. The amount is 0.2% by mass or more and 3.0% by mass or less based on the total mass of the semiconductor substrate polishing liquid, and the content of the water-soluble polymer is based on the total mass of the semiconductor substrate polishing liquid. 0.01 mass% or more and 0.2 mass% or less, and pH is 9 or more and 12 or less.

  Thereby, it is possible to preferentially polish the convex portion when the substrate surface has irregularities while maintaining a predetermined polishing rate for the semiconductor substrate.

  Furthermore, as an invention related to a method for polishing a semiconductor substrate, the present invention is a method for polishing a semiconductor substrate for reuse. The method includes wet etching a silicon wafer to which deposits adhere, and then grinding the silicon wafer. There is provided a method for polishing a semiconductor substrate, comprising: a step of preparing a rough wafer; and a rough polishing step of polishing the rough wafer using a third or fifth semiconductor substrate polishing liquid.

  With such a method for polishing a semiconductor substrate, it is possible to perform rough polishing, which has been conventionally performed in several steps, in one step, and thus it is possible to reduce polishing loss of the semiconductor substrate caused by rough polishing. Become. Thereby, the effect that the frequency | count of reuse of a silicon wafer can be increased more is also acquired.

  Furthermore, as an invention relating to a method for polishing a semiconductor substrate, the present invention is a method for polishing a semiconductor substrate for forming a through silicon via, the step of forming a recess in one surface of the silicon substrate, and a metal in the recess A step of embedding, a step of back grinding the other surface of the silicon substrate, and a polishing step of polishing the other surface using a third or fifth semiconductor substrate polishing liquid so that the metal is exposed. A method for polishing a semiconductor substrate is provided.

  Thereby, grinding marks after back grinding, which are generated in the process of forming through silicon vias, can be sufficiently flattened with a small amount of polishing.

In the above rough polishing step, the polishing amount of the rough wafer is L (nm), the initial step of the rough wafer is R _t0 (nm), and the step of the rough wafer after the rough polishing is R _t1 (nm). When defined, when a rough wafer is polished by L (nm) satisfying R _t0 ≦ L ≦ R _t0 × 1.3 (that is, polished by a polishing amount not more than 1.3 times the initial step), L / ( R _t0 −R _t1 ) ≦ 1.3 and R _t1 ≦ 100 (nm) are preferably satisfied. Needless to say, the final polishing amount may be more than the above-mentioned range (R _t0 ≦ L ≦ R _t0 × 1.3).

  Further, in the above-described method for polishing a semiconductor substrate, the method may further include a final polishing step of polishing the rough wafer after the rough polishing step using a polishing liquid. It contains 4-triazole, a water-soluble polymer, and a basic compound, and preferably has a pH of 9 or more and 12 or less. As a result, the surface of the semiconductor substrate can be polished with less unevenness and smoothness with fewer defects.

  Furthermore, in the above-described method for polishing a semiconductor substrate, the semiconductor wafer may further include a final polishing step of polishing the rough wafer after the rough polishing step using a polishing liquid. It contains 4-triazole, a water-soluble polymer, and a basic compound, and the content of 1,2,4-triazole is 0.05% by mass or more and 0% by mass with respect to the total mass of the semiconductor substrate polishing liquid. 0.5 mass% or less, the content of the water-soluble polymer is 0.001 mass% or more and 0.1 mass% or less with respect to the total mass of the polishing liquid for semiconductor substrate, and the pH is 9 or more and 12 or less. It is preferable that As a result, the surface of the semiconductor substrate can be finished and polished more reliably to a smooth surface with less irregularities and less defects.

  In the third, fourth and fifth semiconductor substrate polishing liquids, the water-soluble polymer is preferably a nonionic polymer. By using a nonionic polymer, the effect of reducing irregularities on the surface of the semiconductor substrate becomes significant. The nonionic polymer is preferably at least one selected from polyvinylpyrrolidone and polyvinylpyrrolidone copolymers. The water-soluble polymer may be a mixture containing at least one selected from polyvinyl pyrrolidone and a polyvinyl pyrrolidone copolymer.

  In the semiconductor substrate polishing liquid according to the present invention, the semiconductor substrate to be polished is preferably silicon or a substrate containing silicon in the substrate structure. That is, the present invention is particularly excellent in the polishing rate for silicon or a substrate containing silicon in the substrate structure.

  In the method for polishing a semiconductor substrate according to the present invention, the surface of the semiconductor substrate is polished using the polishing liquid for a semiconductor substrate according to the present invention. According to such a polishing method, the surface of the semiconductor substrate can be polished to a smooth surface with few defects at a high speed.

  In the present invention, a polishing solution for a semiconductor substrate and a semiconductor substrate polishing solution that can reduce the processing time of a semiconductor substrate, facilitate process control, and process a semiconductor substrate with uniform quality by high-speed and stable polishing. A method for polishing a used semiconductor substrate can be provided.

  In addition, the present invention provides a polishing liquid for a semiconductor substrate and a polishing method for the polishing liquid for a semiconductor substrate, which can polish the surface of a semiconductor substrate to a smooth surface with less unevenness and less defects.

  Further, according to the present invention, there is provided a polishing liquid for a semiconductor substrate and a polishing method for a polishing liquid for a semiconductor substrate capable of polishing the surface of a semiconductor substrate to a smooth surface with a small amount of polishing and less unevenness at a practical polishing rate. Provided.

It is the graph which showed the variation | change_quantity of pH of each polishing liquid 24 hours after the time of preparing each polishing liquid of Examples 1-4 and a prior art example (comparative examples 1-11). The graph which showed the polishing rate immediately after adjustment of each polishing liquid of Examples 1-4 and a prior art example (comparative examples 1-11), and the polishing rate of each polishing liquid 24 hours after the time of preparing each polishing liquid. is there. It is the graph which showed the relationship between the addition amount of the abrasive grain (silica) in each polishing liquid, and the variation | change_quantity of pH of each polishing liquid 24 hours after the time of preparing each polishing liquid. It is a measurement result by the level | step difference, surface roughness, and fine shape measuring apparatus of Example 9. FIG. It is a measurement result by the level | step difference, surface roughness, and fine shape measuring apparatus of the comparative example 20. FIG. It is the graph which showed pH of the polishing liquid of Examples 11-14 and a prior art example (comparative examples 21-24), and polishing rate. It is a measurement result by the level | step difference, surface roughness, and fine shape measuring apparatus of Example 19. It is a measurement result by the level | step difference, surface roughness, and fine shape measuring apparatus of the comparative example 33. It is a measurement result by the level | step difference, surface roughness, and fine shape measuring apparatus of the comparative example 34. It is a measurement result by the level | step difference, surface roughness, and fine shape measuring apparatus of the comparative example 35. 14 is a graph showing the relationship between the polishing amount L and the maximum height Rt in Example 45. 14 is a graph showing a relationship between a polishing amount L and a maximum height Rt in Comparative Example 43. It is a schematic sectional drawing which shows the grinding | polishing method of the semiconductor substrate which concerns on one Embodiment of this invention. It is the flowchart which showed the processing process of the general silicon wafer. It is a schematic diagram which shows the grinding | polishing process of a general silicon wafer. FIG. 16A is a flowchart showing a general process for reclaiming a silicon wafer, and FIG. 16B is a process for regenerating a silicon wafer when the method for polishing a semiconductor substrate according to an embodiment of the present invention is used. It is the flowchart which showed the process. It is a graph which shows content of 1,2,4-triazole and water-soluble polymer in the 3rd-5th polishing liquid for semiconductor substrates.

  Hereinafter, a semiconductor substrate polishing liquid and a semiconductor substrate polishing method using the polishing liquid according to an embodiment of the present invention will be described in detail with reference to the drawings as necessary.

<First polishing liquid for semiconductor substrate>
As an embodiment of the first invention, it contains abrasive particles, 1,2,4-triazole, and a basic compound, the basic compound is a nitrogen-containing basic compound or an inorganic basic compound, and the basic compound The semiconductor substrate polishing liquid having a content of 0.1% by mass or more and a pH of 9 or more and 12 or less will be described.

  In the first embodiment, since the decrease in pH can be suppressed even in a high alkali region where the pH of the polishing liquid is 9 or more and 12 or less, it is possible to extremely reduce the decrease and fluctuation of the polishing rate over time, and at high speed. Polishing of the semiconductor substrate becomes possible.

(PH)
In the first embodiment, in order to obtain a sufficient polishing rate for the semiconductor substrate, the lower limit of the pH of the semiconductor substrate polishing liquid is set to 9.0 or more. In order to obtain a more excellent polishing rate, the pH is preferably 9.5 or more. Furthermore, the upper limit of the pH is 12.0, preferably 11.5 or less, more preferably 11.0 or less in order to sufficiently suppress the pH of the polishing liquid from being lowered during storage or use. preferable.

  The pH can be adjusted by, for example, the amount of 1,2,4-triazole and / or basic compound added. The pH of the semiconductor substrate polishing liquid can be measured with a pH meter (for example, Model pH81, manufactured by Yokogawa Electric Corporation).

(1,2,4-triazole and basic compounds)
An important feature of the polishing liquid for a semiconductor substrate according to the first embodiment is that 1,2,4-triazole is used in combination with a basic compound. The reason why the combined use of 1,2,4-triazole and a basic compound is important for obtaining the effects of the present invention is not known in detail, but the polishing liquid for semiconductor substrates is 1,2,4-triazole. It can be considered that one of the important factors for achieving the effects of the present invention is that the following items 1 and 2 are achieved by containing both the basic compound and the basic compound.
[Item 1] The amount of basic compound added can be increased.
[Item 2] The fluctuation of the pH of the semiconductor substrate polishing liquid over time can be reduced.

The above item 1 will be described in detail. The basic compound acts as a solubilizer for the semiconductor substrate. Therefore, from the viewpoint of obtaining a high polishing rate, it is preferable that the addition amount of the basic compound is large. However, for example, when the target value of the pH of the polishing liquid is set to 11 and potassium hydroxide is added as a basic compound, the pH of the polishing liquid for a semiconductor substrate will rise immediately. However, when 1,2,4-triazole is added to the polishing liquid for a semiconductor substrate, the pKa ₁ of 1,2,4-triazole is as low as 2.2. An increase in the pH of the polishing liquid can be suppressed. For these reasons, it is possible to increase the amount of the basic compound by using 1,2,4-triazole and the basic compound in combination.

  Even if 1,2,4-triazole is contained alone in the polishing liquid, there is almost no effect of improving the polishing rate. In order to improve the polishing rate, it is important to use 1,2,4-triazole in combination with a basic compound that acts as a solubilizer.

  The basic compound can be increased by adding an acid such as sulfuric acid or hydrochloric acid in place of 1,2,4-triazole, but in such a case, a sufficient polishing rate for silicon may not be obtained. The present inventors have found that the effect of suppressing the decrease in pH after blending is small.

The above item 2 will be described. In the polishing liquid containing 1,2,4-triazole, the decrease in pH can be made extremely small even if time elapses from the blending. When 1,2,3-triazole (pKa ₁ = 2.1) or 1H-benzotriazole (pKa ₁ = 8.2) having a similar structure is used instead of 1,2,4-triazole As described in item 1 above, the amount of the basic compound added to the polishing liquid can be increased, but the effect of suppressing the decrease in pH after blending is small, and is commensurate with the amount of basic compound added. It has been found that the effect of improving the polishing rate cannot be obtained. In addition, when an imidazole compound is used instead of 1,2,4-triazole, the pKa _{1 of the} imidazole compound is as high as 14.5, so the amount of basic compound acting as a solubilizer cannot be increased. Moreover, the effect which suppresses the fall of pH after a mixing | blending is also small.

  The addition amount of 1,2,4-triazole in the polishing liquid for a semiconductor substrate according to the first embodiment is 0.1 in that the effect of suppressing the decrease in pH of the polishing liquid and improving the polishing speed can be sufficiently obtained. The content is preferably at least mass%, more preferably at least 0.25 mass%. Further, the amount of 1,2,4-triazole added is preferably 10% by mass or less, more preferably 7% by mass or less, in terms of easily preventing problems such as aggregation of abrasive particles. Most preferably, it is at most mass%. It should be noted that the aggregation of the abrasive particles cannot be generally attributed only to the addition amount of 1,2,4-triazole, but also to the particle size and addition amount of the abrasive particles.

  The basic compound contained in the semiconductor substrate polishing liquid according to the first embodiment is one or more nitrogen-containing basic compounds selected from ammonium hydroxide and tetramethylammonium hydroxide in terms of low odor, or One or more inorganic basic compounds selected from potassium hydroxide and sodium hydroxide are preferred. These can be used alone or in combination.

(Abrasive particles)
In the first embodiment, it is preferable to use silica as the abrasive particles contained in the semiconductor substrate polishing liquid. This makes it easy to obtain a high polishing rate. As the silica that can be used, known ones can be widely used. Specific examples include fumed silica, colloidal silica, and precipitated silica. Among these, fumed silica or colloidal silica is preferable in that high-purity ones can be easily obtained, and colloidal silica is more preferable in that dispersion defects in water and polishing defects such as scratches are unlikely to occur. Silica may be used in combination with other abrasive particles as necessary. Specific examples of other abrasive particles that can be used in combination with silica include alumina, ceria, titania, zirconia, and organic polymers.

  The primary particle diameter of silica is preferably 5 nm or more, more preferably 7 nm or more, and particularly preferably 9 nm or more in that a practical polishing rate can be obtained. Further, the primary particle diameter of silica is preferably 200 nm or less, more preferably 100 nm or less, particularly preferably 50 nm or less, and 40 nm in that it is easy to suppress the occurrence of polishing defects such as scratches. Very preferably, When the primary particle diameter of silica is within the above range, the polishing speed is most improved by the combination of the polishing acceleration effect due to the mechanical action depending on the particle size and the polishing acceleration effect due to the increase in the number of particles accompanying the reduction in particle size. I think that.

In the first embodiment, the primary particle diameter of silica refers to the average diameter of particles that can be calculated from the BET specific surface area V. From the measurement of the adsorption specific surface area (hereinafter referred to as the BET specific surface area) by a gas adsorption method, Equation (1)
D1 = 6 / (ρ × V) (1)
Is calculated by

In the formula (1), D1 represents a temporary particle diameter (unit: m), ρ represents a particle density (unit: kg / m ³ ), and V represents a BET specific surface area (unit: m ² / g).

More specifically, the abrasive grains are first dried with a vacuum freeze dryer, and the residue is finely crushed with a mortar (magnetic, 100 ml) to obtain a measurement sample, which is measured by BET specific surface area manufactured by Yuasa Ionics Co., Ltd. The BET specific surface area V is measured using an apparatus (product name: Autosorb 6), and the primary particle diameter D1 is calculated. When the particles are colloidal silica, the density ρ of the particles is ρ = 2200 (kg / m ³ ).

Therefore, when the BET specific surface area V (m ² / g) is substituted,
D1 = 2.727 × 10 ⁻⁶ / V (m) = 2727 / V (nm)
As such, the primary particle diameter can be determined.

  The addition amount of the abrasive particles is preferably 0.01% by mass or more and 5.0% by mass or less, more preferably 0.05% by mass or more and 3.0% by mass or less, based on the entire polishing liquid. More preferably, it is 0.1 mass% or more and 1.0 mass% or less. By making the addition amount of the abrasive particles 0.01% by mass or more, it becomes easy to obtain a sufficient polishing rate. Moreover, it becomes easy to suppress generation | occurrence | production of defects, such as an abrasion wound, by making the addition amount of an abrasive particle into 5.0 mass% or less.

(Other ingredients)
In the first embodiment, in addition to the above-described components, components other than water, anticorrosives, oxidizing agents, water-soluble polymer polymers, and other components that are generally added to the polishing liquid are impaired. To the extent possible, it can be added to the polishing liquid for semiconductor substrates.

(Storage format)
The semiconductor substrate polishing liquid of the first embodiment can be stored in a concentrated form in which the component concentration is increased in advance. When the polishing liquid is used, the polishing liquid in a concentrated form may be diluted to the original component concentration with water or the like. Furthermore, it is possible to store the components of the polishing liquid for semiconductor substrate in a separated liquid form and mix them at the time of use.

  In 1st embodiment, the effect which suppresses the fall of the pH after the mixing | blending of the polishing liquid for semiconductor substrates can be acquired irrespective of the addition amount of a silica. Further, in the first embodiment, since the addition amount of the basic compound as the dissolving agent can be increased while keeping the pH of the semiconductor substrate polishing liquid within a predetermined range, the chemical action contributing to polishing can be strengthened. As a result, it is considered that a high polishing rate can be obtained even if the addition amount of silica as abrasive particles is reduced.

<Second polishing liquid for semiconductor substrate>
Next, a second semiconductor substrate polishing liquid will be described as an embodiment of the second invention. In addition, about the part which overlaps with the 1st polishing liquid for semiconductor substrates, it abbreviate | omits suitably.

  In the first polishing liquid for a semiconductor substrate, a good polishing rate for silicon was obtained by using 1,2,4-triazole in combination with a basic substance (whether organic or inorganic). A good polishing rate for silicon can also be obtained by using modified silica whose surface is modified by aluminate as particles and using this in combination with an inorganic basic substance.

  That is, as a second embodiment, the modified silica whose surface is modified with aluminate and an inorganic basic compound are contained, and the content of the modified silica is 0.01% by mass or more and 1.5% by mass or less. A polishing liquid for semiconductor substrates having a pH of 9 or more and 12 or less is provided. In the combination of the modified silica and the inorganic basic compound that is a solubilizer for the semiconductor substrate, the surface potential of the modified silica (abrasive particles) becomes the largest, so that the polishing rate can be increased.

(Modified silica)
The modification of the silica surface with aluminate can be performed using, for example, an aluminum compound such as potassium aluminate [(AlO (OH) ₂ K]. By adding potassium aluminate therein and refluxing at 60 ° C. or higher, silanol groups on the silica surface are converted into —Si—O—Al (OH) ₂ groups that are more easily ionized.

  As the modified silica that can be used, for example, fumed silica, colloidal silica, precipitated silica or the like whose surface is modified by aluminate can be used. Among them, modified fumed silica or modified colloidal silica is preferable in that a high-purity product is easily obtained, and modified colloidal silica is most preferable in terms of dispersion stability in water and difficulty in generating polishing defects such as scratches. The modified silica may be used in combination with other abrasive particles as necessary. Specific examples of other abrasive particles that can be used in combination with the modified silica include alumina, ceria, titania, zirconia, and organic polymers.

  If an organic amine such as tetramethylammonium hydroxide is used as a solubilizer, the surface potential of the abrasive particles becomes small, and the effect of improving the polishing rate may not be obtained. In addition, when modified silica having sulfonic acid groups or amino groups on the surface is used in place of modified silica modified by aluminate, the surface potential of modified silica (abrasive particles) is reduced and the polishing rate is improved. There is a risk that the effect of.

  In the second embodiment, the surface potential of the modified silica refers to the zeta potential of the modified silica measured with a zeta potential measuring device. The value of the zeta potential reflects the surface state of the modified silica. In the high alkaline region, the modified silica exhibits a negative zeta potential. When the value of the zeta potential is small, it can be considered that a compound (for example, organic amines) that cancels the potential interacts with the modified silica. The present inventors consider that when a compound that cancels the potential is present on the surface of the modified silica, the mechanical polishing action of the modified silica is buffered and the original polishing power cannot be exhibited.

  In the prior art described in Patent Document 4, the polishing rate is obtained by suppressing the depolymerization of silica that occurs in the region where the pH of the polishing liquid is 10.5 or higher. It is different from technology. In the present invention, the combined use of the modified silica modified by aluminate and the inorganic basic compound demonstrates the inherent polishing power of the modified silica (abrasive particles). It is possible to obtain a high polishing rate. The addition amount of the modified silica modified by aluminate is preferably 0.01% by mass or more and 1.5% by mass or less, and 0.05% by mass or more and 1.0% by mass with respect to the entire polishing liquid. More preferably, it is more preferably 0.1% by mass or more and 0.8% by mass or less. In the present invention, it is easy to obtain a sufficient polishing rate by setting the amount of the modified silica added to 0.01% by mass or more. Further, in the present invention, a sufficient polishing rate can be obtained even if the amount of the modified silica added is small and 1.5% by mass or less.

  The primary particle diameter of the modified silica is preferably 5 nm or more, more preferably 7 nm or more, and particularly preferably 9 nm or more in that a practical polishing rate can be obtained. The primary particle diameter of the modified silica is preferably 200 nm or less, more preferably 100 nm or less, and particularly preferably 50 nm or less, from the viewpoint of easily suppressing the occurrence of polishing defects such as scratches. It is very preferable that it is 40 nm or less. When the primary particle size of the modified silica is within the above range, the polishing rate is the highest due to the combination of the polishing promoting effect due to the mechanical action depending on the particle size and the polishing promoting effect due to the increase in the number of particles accompanying the reduction in the particle size. It is thought to improve.

  The primary particle diameter of the modified silica can be measured in the same manner as the primary particle diameter of silica in the first semiconductor substrate polishing liquid.

(Inorganic basic compounds)
The inorganic basic compound acts as a solubilizer for obtaining a polishing rate and maximizes the surface potential of the modified silica (abrasive particles), so that the polishing rate can be increased. The inorganic basic compound is preferably at least one selected from potassium hydroxide and sodium hydroxide in terms of low odor. These can be used alone or in combination. From the viewpoint of obtaining a high polishing rate, the larger the amount of the inorganic basic compound added, the better. Therefore, it is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and 0.07% by mass or more. Is more preferable. Further, from the viewpoint of suppressing deterioration of surface roughness due to an increase in etching and depolymerization of silica, the content of the inorganic basic compound is preferably 5% by mass or less, more preferably 3% by mass or less, and more preferably 1% by mass or less. Particularly preferred.

  In the second embodiment, 1,2,4-triazole is not an essential component, but it is preferable to further include 1,2,4-triazole in order to obtain a higher polishing rate for silicon.

  When 1,2,4-triazole is used, the polishing rate can be easily improved, and the decrease and fluctuation of the polishing rate over time can be further reduced. As a result, high-speed and stable polishing makes it possible to reduce the processing time of the semiconductor substrate, facilitate process management, and more reliably process a semiconductor substrate with uniform quality.

  In this case, the amount of 1,2,4-triazole added to the second semiconductor substrate polishing liquid is preferably in the same range as the amount added in the first semiconductor substrate polishing liquid.

<Third semiconductor substrate polishing liquid>
Next, a third polishing liquid for a semiconductor substrate will be described as an embodiment of the third invention. In addition, about the part which overlaps with 1st and 2nd polishing liquid for semiconductor substrates, it abbreviate | omits suitably.

  The polishing liquid for a semiconductor substrate of the third embodiment contains abrasive particles, 1,2,4-triazole, a water-soluble polymer, and a basic compound, and has a pH of 9 or more and 12 or less. By using such a polishing liquid for a semiconductor substrate, the surface of the semiconductor substrate can be polished to a smooth surface with few irregularities.

  More specifically, in the third embodiment, since 1,2,4-triazole is contained, it is possible to suppress a decrease in pH even in a high alkaline region where the pH of the polishing liquid is 9 or more and 12 or less. The decrease and fluctuation in speed are extremely reduced, and stable polishing of the semiconductor substrate becomes possible. In the third embodiment, it is possible to process a semiconductor substrate with uniform quality by stable polishing. In the third embodiment, the surface of the semiconductor substrate can be polished to a smooth surface with less unevenness by reducing the unevenness of the substrate surface with the water-soluble polymer and 1,2,4-triazole.

(1,2,4-triazole)
In order to obtain the above-described effect by 1,2,4-triazole, the content of 1,2,4-triazole is 0.001% by mass or more and 10% by mass with respect to the total mass of the polishing liquid for semiconductor substrate. It is preferable that it is below mass%.

(Water-soluble polymer)
Examples of the water-soluble polymer (water-soluble polymer) contained in the semiconductor substrate polishing liquid include alginic acid, pectic acid, carboxymethyl cellulose, agar, xanthan gum, chitosan, methyl glycol chitosan, methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, hydroxy Polysaccharides such as propylmethylcellulose, hydroxyethylcellulose, cardran and pullulan; polyaspartic acid, polyglutamic acid, polylysine, polymalic acid, polymethacrylic acid, polymethacrylic acid ammonium salt, polymethacrylic acid sodium salt, polyamic acid, polymaleic acid, Polyitaconic acid, polyfumaric acid, poly (p-styrenecarboxylic acid), polyvinyl sulfate, polyacrylic acid, polyacrylamide, aminopolyacrylamide, polyacryl Ammonium salt, polyacrylic acid sodium salt, polyamic acid, polyamic acid ammonium salt, polyamic acid sodium salt and polyglyoxylic acid and the like; polyethylenimine and its salt; polyvinyl alcohol, polyvinyl pyrrolidone and poly Examples thereof include vinyl polymers such as acrolein, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and ethylene glycol-propylene glycol block copolymers. Among them, carboxymethyl cellulose, agar, xanthan gum, chitosan, methyl glycol chitosan, methylcellulose, ethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, cardan and pullulan and other polysaccharides, polyacrylamide, polyethyleneimine, Nonionic polymers such as polyvinyl alcohol, polyvinyl pyrrolidone and polyacrolein, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and ethylene glycol-propylene glycol block copolymers are preferred, and polyvinyl pyrrolidone and copolymers thereof are more preferred. preferable. In addition, said water-soluble polymer (water-soluble polymer) can be used individually or even if it mixes multiple types. Moreover, when mixing and using multiple types among said water-soluble polymer, it is preferable that the mixture contains at least 1 type chosen from polyvinylpyrrolidone and its copolymer.

  The present inventors consider that the reduction in unevenness on the surface of the semiconductor substrate in the present invention is caused by adsorption of the water-soluble polymer to the surface of the semiconductor substrate due to the hydrophobic interaction between the semiconductor substrate and the hydrophobic portion of the water-soluble polymer. That is, the water-soluble polymer adsorbed on the surface of the semiconductor substrate is adsorbed on the irregularities on the surface of the semiconductor substrate, and the water-soluble polymer on the convex portions is more easily removed than the concave portions by the polishing pad or polishing particles. It is considered that a smooth surface is formed by promoting the above. Therefore, when a nonionic water-soluble polymer having no ionic group is used as the water-soluble polymer, the effect of reducing unevenness becomes remarkable.

  The addition amount of the water-soluble polymer is preferably 0.001% by mass or more and 10% by mass or less, and more preferably 0.01% by mass or more and 1% by mass or less with respect to the polishing liquid. By making the addition amount of the water-soluble polymer 0.001% by mass or more, the effect of reducing the unevenness tends to increase. Moreover, by making the addition amount of the water-soluble polymer 10% by mass or less, it becomes easy to prevent the increase in the viscosity of the polishing liquid and the decrease in fluidity due to the increase in the viscosity due to the addition of the water-soluble polymer. It will be easier to prevent.

  Generally, when the dissolving action of the polishing liquid is increased, the irregularities on the surface of the semiconductor substrate tend to increase. However, the 1,2,4-triazole contained in the semiconductor substrate polishing liquid according to the present invention is inferior to a water-soluble polymer, but has an effect of reducing the unevenness of the substrate surface. Therefore, in the present invention, the combined use of 1,2,4-triazole and a water-soluble polymer makes it possible to polish the surface of the semiconductor substrate to a smooth surface with few irregularities at a high polishing rate.

<Fourth polishing liquid for semiconductor substrate>
Next, a fourth semiconductor substrate polishing liquid will be described as an embodiment of the fourth invention. In addition, about the part which description overlaps with the 1st, 2nd and 3rd polishing liquid for semiconductor substrates, it abbreviate | omits suitably.

  The polishing liquid for a semiconductor substrate of the fourth embodiment contains abrasive particles, 1,2,4-triazole, a water-soluble polymer, and a basic compound, and the amount of 1,2,4-triazole added. Is 0.05 mass% or more and 0.5 mass% or less, the addition amount of water-soluble polymer is 0.001 mass% or more and 0.1 mass% or less, and pH is 9 or more and 12 or less.

  The fourth embodiment is particularly suitable for finish polishing in a semiconductor wafer manufacturing process. That is, the unevenness existing on the silicon substrate is eliminated rather than the polishing rate with respect to the silicon substrate, the foreign matters remaining on the silicon substrate (such as abrasive particles and abrasion powder generated by abrasion of the polishing pad), and the semiconductor substrate This polishing liquid focuses on reducing crystal defects.

(PH)
In the fourth embodiment, the pH is 9 or more, and more preferably 9.5 or more, from the viewpoint of reducing defects caused by foreign matters adhering to the silicon substrate surface. Moreover, from a viewpoint of suppressing generation | occurrence | production of the defect resulting from excessive etching, pH is 12 or less, 11 or less are preferable and 10.5 or less are more preferable.

(1,2,4-triazole)
In 4th embodiment, the addition amount of the said 1,2,4-triazole is 0.05 mass% or more and 0.5 mass% or less. The pH stability of 1,2,4-triazole, the point at which the effect of improving the polishing rate due to the increase in the amount of the basic compound that is a solubilizing agent is easily obtained, and the haze (HAZE: turbidity) that is an index of the roughness of the wafer surface The addition amount is 0.05% by mass or more, and preferably 0.1% by mass or more. On the other hand, the addition amount is 0.5% by mass or less, and 0.4% by mass or less is more preferable in that haze improvement effect corresponding to the addition amount is not obtained, and aggregation of abrasive particles can be further suppressed. Preferably, 0.3 mass% or less is especially preferable.

(Water-soluble polymer)
In the fourth embodiment, the amount of the water-soluble polymer (water-soluble polymer) added is in the range of 0.001% by mass to 0.1% by mass. The addition amount is 0.001% by mass or more, preferably 0.003% by mass or more, and preferably 0.005% by mass or more in that the effect of reducing defects on the surface of the silicon substrate is sufficiently obtained. Is more preferable, and 0.01% by mass or more is particularly preferable. In addition, the addition amount is 0.1% by mass or less, preferably 0.08% by mass or less, preferably 0.07% by mass in terms of suppressing the occurrence of defects such as polishing inhibition, increase in defects, and haze improvement. % Or less is more preferable, 0.05% by mass or less is particularly preferable, and 0.03% by mass or less is extremely preferable. Here, the defect on the silicon substrate is used as a general term for foreign matters such as abrasion particles generated by abrasion of abrasive particles and polishing pads, crystal defects and scratches generated on the silicon substrate, and the like.

  The reduction of defects due to the addition of water-soluble polymers prevents foreign particles such as abrasive particles and abrasion powder generated by abrasion of polishing pads from adhering to the surface of the semiconductor substrate. It is considered that it can be obtained by suppressing the occurrence of etching in a specific direction due to dangling bonds (unbonded limbs) or COP (Crystal Oriented Particles) on the substrate surface.

  The values of haze and defects are determined by cleaning the surface of the silicon substrate after polishing (for example, cleaning with a general cleaning brush for 60 seconds with a cleaning solution containing 0.06% ammonium hydroxide), and then commercially available. It can be measured using a defect inspection apparatus.

Specifically, for example, values measured under the following conditions can be defined as haze and defects.
Defect inspection system: LS6700 (manufactured by Hitachi Electronics Engineering)
Process condition file (measurement recipe): VeM10L
Defect measurement range: 0.1 μm-3.0 μm
Projection condition: Vertical

  As described above, the fourth embodiment focuses on eliminating minute irregularities on the silicon substrate and reducing defects rather than the polishing rate for the silicon substrate, as in the case of finish polishing in the manufacturing process of a semiconductor wafer. I put it. Therefore, the addition amount of the abrasive particles is preferably 0.05% by mass or more and 0.5% by mass or less with respect to the entire polishing liquid. If it is 0.05% by mass or more, unevenness can be eliminated, and if it is 0.5% by mass or less, the silicon substrate can be prevented from being excessively polished.

<Fifth polishing liquid for semiconductor substrate>
Next, a fifth semiconductor substrate polishing liquid will be described as an embodiment of the fifth invention. In addition, about the part which description overlaps with the 1st, 2nd and 3rd polishing liquid for semiconductor substrates, it abbreviate | omits suitably.

  The polishing liquid for a semiconductor substrate according to the fifth embodiment contains abrasive particles, 1,2,4-triazole, a water-soluble polymer and a basic compound, and the amount of 1,2,4-triazole added is 0.00. 2% by mass or more and 3.0% by mass or less, the addition amount of the water-soluble polymer is 0.01% by mass or more and 0.2% by mass or less, and the pH is 9 or more and 12 or less. A polishing liquid.

(PH)
In the fifth embodiment, from the viewpoint of obtaining a predetermined polishing rate for the silicon, the pH is 9 or more, more preferably 9.5 or more, and even more preferably 10.0 or more. Further, from the viewpoint of suppressing defects caused by excessive etching, the pH is 12 or less, and preferably 11 or less.

  In the fifth embodiment, the amount of 1,2,4-triazole added is large and the amount of the water-soluble polymer added is large compared to the fourth polishing liquid for a semiconductor substrate. By doing in this way, it can be set as the semiconductor substrate polishing liquid which can preferentially polish a convex part, when a surface has an unevenness | corrugation, obtaining the predetermined | prescribed polishing speed with respect to a silicon substrate. In particular, in a silicon substrate having a high step such as a silicon substrate mechanically ground (grinding or the like), the protrusions of the step are preferentially polished to remove grinding marks generated during the grinding. Is possible.

  With such a method for polishing a semiconductor substrate, it is possible to perform rough polishing, which has been conventionally performed in several steps, in one step, and thus it is possible to reduce polishing loss of the semiconductor substrate caused by rough polishing. Become. Thereby, the effect that the frequency | count of reuse of a silicon wafer can be increased more is also acquired.

In the above rough polishing step, the polishing amount of the rough wafer is L (nm), the initial step of the rough wafer is R _t0 (nm), and the step of the rough wafer after the rough polishing is R _t1 (nm). When defined, when a rough wafer is polished by L (nm) satisfying R _t0 ≦ L ≦ R _t0 × 1.3 (that is, polished by a polishing amount not more than 1.3 times the initial step), L / ( R _t0 −R _t1 ) ≦ 1.3 and R _t1 ≦ 100 (nm) are preferably satisfied. Needless to say, the final polishing amount may be more than the above-mentioned range (R _t0 ≦ L ≦ R _t0 × 1.3).

Here, the polishing amount L means the thickness of the portion removed from the rough wafer by polishing. The initial level difference R _t0 is the maximum value of the height difference between the convex and concave portions of the rough wafer surface before rough polishing. The level difference R _t1 of the roughly polished rough wafer is the maximum value of the height difference between the convex and concave portions of the rough polished rough wafer surface.

  FIG. 17 is a graph showing the contents of 1,2,4-triazole and water-soluble polymer in the third to fifth semiconductor substrate polishing liquids. As described above, in the third polishing liquid for a semiconductor substrate, the content of 1,2,4-triazole is 0.01% by mass to 10% by mass with respect to the total mass of the polishing liquid for the semiconductor substrate. The content of the water-soluble polymer is preferably 0.001% by mass or more and 10% by mass or less (preferable range of the third polishing liquid for a semiconductor substrate in FIG. 17). In the fourth polishing liquid for semiconductor substrate, the content of 1,2,4-triazole is 0.05% by mass or more and 0.5% by mass or less with respect to the total mass of the polishing liquid for semiconductor substrate. The content of the water-soluble polymer is 0.001% by mass or more and 0.1% by mass or less. Further, in the fifth polishing liquid for semiconductor substrate, the content of 1,2,4-triazole is 0.2% by mass or more and 3.0% by mass or less with respect to the total mass of the polishing liquid for semiconductor substrate. Yes, the content of the water-soluble polymer is 0.01% by mass or more and 0.2% by mass or less.

<Semiconductor substrate polishing method>
Next, a polishing method for polishing the surface of the semiconductor substrate using the first to fifth semiconductor substrate polishing liquids described so far will be described. As an example of the polishing method, for example, while supplying the polishing liquid for a semiconductor substrate of the present embodiment onto the polishing cloth of the polishing surface plate, the polishing surface plate is pressed against the polishing substrate (semiconductor substrate) against the polishing cloth. The surface of the semiconductor substrate is polished by relatively moving the substrate to be polished.

  As a polishing apparatus that can be used in the polishing method of the present embodiment, for example, a polishing platen on which a holder that holds a substrate to be polished and a motor that can attach a polishing cloth (pad) and can change the number of rotations are attached. A general polishing apparatus having the following can be used. There is no restriction | limiting in particular as polishing cloth on a polishing surface plate, A general nonwoven fabric, a foaming polyurethane, a porous fluororesin, etc. can be used. In order to relatively move the polishing cloth and the substrate to be polished while the semiconductor substrate is pressed against the polishing cloth, specifically, at least one of the substrate and the polishing surface plate may be moved. In addition to rotating the polishing surface plate, polishing may be performed by rotating or swinging the holder.

  Examples of the polishing method include a polishing method in which a polishing platen is rotated on a planetary surface, a polishing method in which a belt-shaped polishing cloth is moved linearly in one direction in the longitudinal direction, and the like. Note that the holder may be in any state of being fixed, rotating and swinging. These polishing methods are appropriately selected according to the substrate to be polished and the polishing apparatus as long as the polishing cloth and the semiconductor substrate are moved relatively. During polishing, it is preferable to continuously supply a polishing solution for a semiconductor substrate to the polishing cloth with a pump or the like.

<Polishing method using first or second semiconductor substrate polishing liquid>
The first and second semiconductor substrate polishing liquids of the present embodiment have excellent polishing characteristics when a silicon or a substrate containing silicon in the substrate structure is polished using the above polishing method. In particular, the polishing rate for silicon or a substrate containing silicon in the substrate structure is excellent.

  Hereinafter, an embodiment of a semiconductor substrate polishing method using the first and second semiconductor substrate polishing liquids will be described.

(Through silicon via backside polishing method)
An example of a polishing process utilizing the polishing characteristics of the first and second semiconductor substrate polishing liquids will be described with reference to FIG. Needless to say, the method for polishing a semiconductor substrate of the present invention is not limited to this example. FIG. 13 is a schematic cross-sectional view showing an example of the through silicon via forming process.

  In FIG. 13A, the semiconductor substrate 1 made of silicon or the like is formed with unevenness for through vias, and a wiring metal 2 such as copper is formed so as to fill the unevenness. Next, the reverse surface (back surface) of the surface on which the unevenness of the semiconductor substrate 1 is formed is back-ground by a known method. At this time, due to the strong mechanical action of the back grind, the silicon damage layer 3 that is mechanically damaged is generated on the back surface of the semiconductor substrate 1 as shown in FIG. Finally, the silicon damage layer 3 and the semiconductor substrate 1 are polished using the semiconductor substrate polishing liquid of this embodiment, and polished until the wiring metal 2 is exposed on the back surface, as shown in FIG. Such a through silicon via is formed.

  Although the surface of the silicon damage layer 3 may have fine irregularities, the method for polishing a semiconductor substrate using the semiconductor substrate polishing liquid of this embodiment is good even for a semiconductor substrate with irregularities on the surface. A high polishing rate. Therefore, the semiconductor substrate polishing method using the semiconductor substrate polishing liquid of this embodiment can be used in various applications for polishing a semiconductor substrate.

  That is, this embodiment is a method of polishing a semiconductor substrate for forming a through silicon via, which includes a step of forming a recess in one surface of the silicon substrate, a step of embedding a metal in the recess, and the other of the silicon substrate. A method for polishing a semiconductor substrate comprising: a step of back grinding a surface; and a polishing step of polishing the other surface using a first or second polishing liquid for a semiconductor substrate so that the metal is exposed.

  In addition, in such a back grind of through silicon vias, the third or fourth semiconductor substrate polishing liquid can also be applied when final polishing is applied at the final stage.

(Polishing method for silicon wafer manufacturing process)
Another example of the polishing process utilizing the polishing characteristics of the first and second semiconductor substrate polishing liquids will be described with reference to FIGS. FIG. 14 is a flow of a general silicon wafer processing technique. A silicon wafer is processed into a wafer shape through a process including a process of slicing a single crystal of silicon (slicing), a lapping process or a grinding process, and an etching process. Since the lapping process or the grinding process is mechanically ground, the silicon crystal may be damaged such as crystal defects. Therefore, in the subsequent etching process, it is common to eliminate such damage and to some extent unevenness on the surface.

  However, even a silicon wafer after undergoing an etching process is not flat enough to produce a so-called semiconductor device, and damage such as crystal defects has not been eliminated. Therefore, as shown in FIG. 15, it is common to obtain a flat silicon wafer through a multi-step polishing process. FIG. 15 shows a two-step rough polishing (rough cutting) process from (a) to (b) and (b) to (c) and a final polishing (final polishing) process from (c) to (d). However, this polishing process varies depending on the wafer manufacturer and the grade of the wafer, and there are cases where the polishing process is more multistage.

  In the rough polishing, polishing is performed while sequentially changing the hardness of a polishing cloth to be used from a hard one to a soft one, and unevenness and damage are gradually eliminated while the film thickness is reduced. In the final polishing process, the polishing rate for silicon is rarely required, and without causing new defects, the abrasive particles adhering during rough polishing are removed, or minute irregularities are eliminated. This is a polishing process intended to make a mirror surface.

  Here, the first and second semiconductor substrate polishing liquids are suitable for the above-described rough polishing. That is, in the present embodiment, after wrapping or grinding a silicon wafer obtained by slicing a silicon single crystal ingot, the silicon wafer is etched to prepare a rough wafer, and the first or second semiconductor And a rough polishing step of polishing a rough wafer using a substrate polishing liquid.

(Polishing method for reclaiming silicon wafers)
Further, the first and second semiconductor substrate polishing liquids can be suitably used in a method for polishing a recycled wafer by utilizing a high polishing rate for silicon. Hereinafter, a method for polishing the recycled wafer will be described.

  In general, in each element process for manufacturing a semiconductor device from a silicon wafer, a large number of wafers are used as test wafers for process testing. Examples of such test wafers include those obtained by forming various films such as an insulating film and a metal film on a flat silicon substrate. The purpose of manufacturing these test wafers is to examine the optimum conditions for depositing various films on a silicon substrate, to examine the optimum conditions for applying and exposing a resist film on a silicon substrate, In addition, when monitoring each of the above optimum conditions, it is widely used, for example, when evaluating polishing characteristics of a polishing liquid for various films formed on a silicon substrate.

  These test wafers are subjected to a regeneration process in order to be used again as test wafers. As the regeneration treatment, generally, deposits such as the above-mentioned various films are removed by wet etching, and a flat wafer is obtained again through rough polishing and finish polishing steps. In addition, the test wafer may have a large scratch before being subjected to the regeneration process, or may form irregularities during evaluation. In this case, it is common that a flat wafer is obtained again by removing scratches and irregularities by grinding and rough polishing and finish polishing.

  Among the semiconductor substrate polishing liquids of the present invention, the first and second semiconductor substrate polishing liquids can be suitably used for rough polishing of such recycled wafers. That is, this embodiment is a method for polishing a semiconductor substrate for reuse, using a step of wet-etching a silicon wafer to which deposits adhere, and a first or second polishing liquid for a semiconductor substrate, And a rough polishing step for polishing a wet-etched silicon wafer.

  If the surface of the silicon substrate to be reused has irregularities and scratches, it may have a mechanical grinding step before the step of polishing using the first or second polishing liquid for a semiconductor substrate. preferable.

<Polishing method using third or fourth semiconductor substrate polishing liquid>
Of the semiconductor substrate polishing liquid of the present embodiment, the third semiconductor substrate polishing liquid contains abrasive particles, 1,2,4-triazole and a basic compound, and has a pH of 9 or more and 12 or less. By incorporating a water-soluble polymer into the polishing liquid, the irregularities on the silicon surface can be eliminated.

  In addition, in the third polishing liquid for semiconductor substrates, the addition amount of 1,2,4-triazole and water-soluble polymer is optimized in order to adjust the polishing rate or change the target size of unevenness to be eliminated. The fourth polishing liquid for a semiconductor substrate can be obtained by controlling the pH and the like as necessary.

  Hereinafter, an embodiment of a semiconductor substrate polishing method using the third or fourth semiconductor substrate polishing liquid will be described.

(Polishing method for silicon wafer manufacturing process)
As described above, in order to obtain a flat silicon wafer, a rough polishing (rough cutting) step and a final polishing (final polishing) step are generally performed as shown in FIG. Here, the third and fourth semiconductor substrate polishing liquids eliminate the unevenness existing on the silicon substrate and the foreign matters remaining on the silicon substrate (due to abrasion of polishing particles and polishing pads) rather than the polishing rate for silicon. It is a polishing liquid with an emphasis on removing generated abrasion powder and the like, and is particularly suitable for use in finish polishing in the manufacturing process of silicon wafers. That is, in the present embodiment, after wrapping or grinding a silicon wafer obtained by slicing a silicon single crystal ingot, the silicon wafer is etched to prepare a rough wafer, and the rough polishing is performed to polish the rough wafer. A semiconductor substrate polishing method comprising: a step and a final polishing step of further polishing the silicon wafer after the rough polishing step using a third or fourth semiconductor substrate polishing liquid. In the rough polishing step for polishing the rough wafer, the first or second semiconductor substrate polishing liquid may be used.

(Polishing method for reclaiming silicon wafers)
Further, the third and fourth semiconductor substrate polishing liquids can also be applied to the above-described final polishing in the process of obtaining the recycled wafer. That is, this embodiment is a method of polishing a semiconductor substrate for reuse, and includes a step of wet-etching a silicon wafer to which deposits are attached, a rough polishing step of polishing a wet-etched silicon wafer, And a final polishing step of further polishing the silicon wafer after the rough polishing step using the third or fourth polishing liquid for a semiconductor substrate. In the rough polishing step for polishing the wet-etched silicon wafer, the first or second semiconductor substrate polishing liquid may be used.

  If the surface of the silicon substrate to be reused has irregularities and scratches, it may have a mechanical grinding step before the step of polishing with the third or fourth semiconductor substrate polishing liquid. preferable.

  In addition, when using the third or fourth semiconductor substrate polishing liquid in order to reduce defects on the silicon substrate rather than the polishing rate for silicon and eliminate the fine irregularities on the surface to obtain a high mirror surface, The polishing pad is preferably soft to some extent. For example, a polishing pad having a hardness (Asker C hardness) measured by an Asker rubber hardness meter C type is preferably less than 60 degrees.

<Polishing method using third or fifth semiconductor substrate polishing liquid>
Among the semiconductor substrate polishing liquids of the present embodiment, the fifth semiconductor substrate polishing liquid has a certain polishing rate for silicon while eliminating surface irregularities as compared to the fourth semiconductor substrate polishing liquid. It is obtained. This makes it possible to preferentially polish the convex portions of the semiconductor substrate having relatively large irregularities. In the polishing method described later, a third semiconductor substrate polishing liquid may be used instead of the fifth semiconductor substrate polishing liquid.

  Hereinafter, an embodiment of a semiconductor substrate polishing method using a fifth semiconductor substrate polishing liquid will be described.

  FIG. 16A is a general process flow for recycling a silicon wafer. The silicon wafer collected for reuse is subjected to acceptance inspection, and then becomes a rough wafer through a wet etching process for removing deposits and a grinding process for eliminating relatively large unevenness. After washing this rough wafer by a predetermined method, it is roughly polished in multiple stages (primary polishing, secondary polishing ...) in the rough polishing process, and further through a final polishing process and a cleaning process, Shipped as a recycled wafer.

  However, under the present circumstances, the silicon wafer is scraped more than necessary due to multi-stage rough polishing after grinding. Therefore, in order to reduce such “polishing margin” and reuse the silicon wafer more efficiently, improvement is still necessary.

  On the other hand, by using the fifth semiconductor substrate polishing liquid, it is possible to provide an unprecedented new polishing method capable of such an improvement. That is, this embodiment is a method for polishing a semiconductor substrate for reuse, and after wet etching a silicon wafer to which deposits are attached, grinding the silicon wafer to prepare a rough wafer; and And a rough polishing step of polishing a rough wafer using a fifth semiconductor substrate polishing liquid.

  With such a method for polishing a semiconductor substrate, the rough polishing that has been conventionally performed in several steps can be performed in one step (see FIG. 16B). The margin can be reduced. Thereby, the effect that the frequency | count of reuse of a silicon wafer can be increased more is also acquired.

In the above rough polishing step, the polishing amount of the rough wafer is L (nm), the initial step of the rough wafer is R _t0 (nm), and the step of the rough wafer after the rough polishing is R _t1 (nm). When defined, when a rough wafer is polished by L (nm) satisfying R _t0 ≦ L ≦ R _t0 × 1.3 (that is, polished by a polishing amount not more than 1.3 times the initial step), L / ( R _t0 −R _t1 ) ≦ 1.3 and R _t1 ≦ 100 (nm) are preferably satisfied. Needless to say, the final polishing amount may be more than the above-mentioned range (R _t0 ≦ L ≦ R _t0 × 1.3).

  Further, in the above-described method for polishing a semiconductor substrate, the method may further include a final polishing step of polishing the rough wafer after the rough polishing step using a polishing liquid. It contains 4-triazole, a water-soluble polymer, and a basic compound, and preferably has a pH of 9 or more and 12 or less. As a result, the surface of the semiconductor substrate can be finished and polished at a high speed to a smooth surface with few irregularities.

  Furthermore, in the above-described method for polishing a semiconductor substrate, the semiconductor wafer may further include a final polishing step of polishing the rough wafer after the rough polishing step using a polishing liquid. It contains 4-triazole, a water-soluble polymer, and a basic compound, and the content of 1,2,4-triazole is 0.05% by mass or more and 0% by mass with respect to the total mass of the semiconductor substrate polishing liquid. 0.5 mass% or less, the content of the water-soluble polymer is 0.001 mass% or more and 0.1 mass% or less with respect to the total mass of the polishing liquid for semiconductor substrate, and the pH is 9 or more and 12 or less. It is preferable that This makes it possible to finish and polish the surface of the semiconductor substrate at a high speed to a smooth surface with less unevenness more reliably.

  The fifth semiconductor substrate polishing liquid can also be suitably applied to the TSV back surface polishing method. Generally, the back surface of the TSV is not required to be as flat as the circuit surface (active surface). Therefore, after performing mechanical grinding in one stage, the TSV back surface polishing is performed using the fifth semiconductor substrate polishing liquid. As a result, a TSV substrate that can withstand practical use can be obtained. Conventionally, the backside polishing of TSV has undergone a plurality of stages of mechanical grinding before polishing, but according to the method of the present invention, the TSV manufacturing process can be greatly simplified.

  Further, in the fifth semiconductor substrate polishing liquid, the polishing pad may have a certain degree of hardness in order to obtain a certain polishing rate for silicon while eliminating a certain degree of unevenness generated on the surface by grinding or the like. Preferably, for example, the hardness (Asker C hardness) measured with an Asker rubber hardness tester C type is preferably 60 degrees or more, more preferably 70 degrees or more, and further preferably 80 degrees or more. By having these hardnesses, it is easy to obtain a good polishing rate, and there is a tendency that the unevenness can be easily eliminated.

  According to such a polishing method, ideally, a plurality of steps of rough polishing are not required, and therefore a semiconductor wafer polishing method consisting of one step of rough polishing, or one step of rough polishing and one step of finish polishing. A method for polishing a semiconductor wafer is provided.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to these Examples.

<First polishing liquid for semiconductor substrate>
(Examples 1-8)
[Preparation of polishing liquid for semiconductor]
According to the following procedure, 1,2,4-triazole, a basic compound, and colloidal silica as abrasive particles are blended in the addition amounts shown in Table 1 to prepare each semiconductor polishing liquid of Examples 1-8. did.

  In the preparation of each polishing liquid, first, 1,2,4-triazole is dissolved in pure water corresponding to 50% by mass of the entire polishing liquid, a basic compound is added thereto, and then a colloidal having a primary particle size of 35 nm. Silica was dispersed, and the remainder was mixed with pure water so that the total amount was 100% by mass.

(Examples 9 and 10)
[Preparation of polishing liquid for semiconductor]
In accordance with the following procedure, 1,2,4-triazole, a basic compound, and colloidal silica as abrasive particles are blended in the addition amounts shown in Table 2 to prepare polishing liquids for semiconductors of Examples 9 and 10. did.

  In the preparation of each polishing liquid, first, 1,2,4-triazole is dissolved in pure water corresponding to 50% by mass of the entire polishing liquid, a basic compound is added thereto, and then colloidal silica having a primary particle size of 17 nm. And the remainder was blended with pure water so that the total amount would be 100% by mass.

[PH measurement]
The pH of each semiconductor polishing liquid of Examples 1 to 10 was measured by the following method.
(Measurement method of pH)
pH meter: Model pH81 manufactured by Yokogawa Electric Corporation
Calibration: Two-point calibration with neutral phosphate pH buffer pH 6.86 (25 ° C) and borate pH standard solution (pH 9.18) (25 ° C) Measurement temperature: 25 ° C
Magnetic Stirrer: AS-30 HS-30D
Measurement procedure: Using a stirrer coated with a fluororesin having a major axis of about 4 cm and a minor axis of about 0.5 cm, pH was measured in a state where the polishing liquid was stirred at 500 rpm.
Measurement period: Immediately after compounding, after standing for one day

  The term “immediately after blending” means that it is less than one hour after the preparation (mixing) of the semiconductor polishing liquid is completed, and the term “after standing for one day” refers to the semiconductor polishing liquid described above. After completion of the adjustment (formulation), after standing for 24 to 25 hours, it means each, and so on.

  Tables 1 and 2 show the pH of each semiconductor polishing liquid immediately after compounding. In addition, Table 1 shows the pH of each semiconductor polishing liquid after being allowed to stand for one day after blending, and the amount of change from the pH measured immediately after blending.

[Semiconductor substrate polishing 1]
While supplying the semiconductor substrate polishing liquid of Example 1 immediately after blending onto the polishing cloth of the polishing surface plate, the polishing surface plate is rotated relative to the semiconductor substrate while the semiconductor substrate is pressed against the polishing cloth. As a result, the surface of the semiconductor substrate was polished. Moreover, the semiconductor substrate was grind | polished by the method similar to Example 1 using each polishing liquid of Examples 2-8 immediately after mixing | blending. The details of the polishing conditions are as follows.
(Polishing condition 1)
Polishing device: FACT-200 type polishing cloth manufactured by Nano Factor: IC-1010 manufactured by Nitta Haas
Polishing platen rotation speed: 80rpm
Holder rotation speed: No drive (free rotation)
Polishing pressure: 33.83 kPa (345 gf / cm ² )
Polishing liquid supply amount: 16 ml / min Polishing time: 5 minutes Semiconductor substrate (object to be polished): 2 cm square silicon wafer (P type <100>)

[Semiconductor substrate polishing 2]
Similarly, while supplying the polishing liquid for semiconductor substrates of Examples 9 and 10 immediately after blending onto the polishing cloth of the polishing surface plate, the polishing surface plate is pressed against the semiconductor substrate while the semiconductor substrate is pressed against the polishing cloth. The surface of the semiconductor substrate was polished by relatively rotating. The details of the polishing conditions are as follows.
(Polishing condition 2)
Polishing equipment: MIRRA manufactured by Applied Materials
Polishing cloth: IC-1010 manufactured by Nitta Haas
Polishing platen rotation speed: 93rpm
Holder rotation speed: 87rpm
Polishing pressure: 20.7 kPa
Polishing liquid supply amount: 200 ml / min Polishing time: 3 minutes Semiconductor substrate (object to be polished): 200 mm silicon wafer (P-type <100>)

[Washing]
After polishing, the semiconductor substrate was cleaned with a polyvinyl alcohol brush and ultrasonic water. After cleaning, the semiconductor substrate was dried with a spin dryer.

[Measurement of polishing rate immediately after compounding]
The silicon wafer was polished by the above method using each of the semiconductor polishing liquids of Examples 1 to 10 immediately after blending, and then the amount of decrease in the mass of the silicon wafer accompanying polishing was measured. Then, the polishing rate (unit: nm / min) was measured from the decrease in mass, wafer area, specific gravity of silicon, and polishing time. In addition, the electronic balance for analysis (AB104 made from METTLER) was used for the mass measurement of a silicon wafer. The measurement temperature was 25 ° C., and the measurement humidity was 40% RH or higher. The specific gravity of silicon was 2.33.

[Measurement of polishing speed after standing for one day]
The polishing rate when each semiconductor polishing liquid of Examples 1 to 8 after standing for one day was measured in the same manner as when each semiconductor polishing liquid of Examples 1 to 8 was used immediately after compounding. did.

[Surface roughness evaluation]
After polishing the silicon wafer by the above method using each of the semiconductor polishing liquids of Examples 9 and 10 immediately after the compounding, the arithmetic average of the polished surface of the silicon wafer was measured using a step, surface roughness, and fine shape measuring device. The roughness was measured under the following conditions.
Step / surface roughness / fine shape measuring device: P16-OF manufactured by KLA Tencor
Measurement mode: Roughness
Measurement length: 200 μm
Measurement speed: 5 μm / sec Measurement load: 1 mg

  The evaluation results of Examples 1 to 8 are shown in Table 1, and the evaluation results of Examples 9 and 10 are shown in Table 2, respectively.

(Comparative Examples 1-14)
The basic compounds shown in Tables 3 and 4 below and colloidal silica as abrasive particles are blended in the addition amounts shown in Tables 3 and 4 according to the following procedure, and for each semiconductor substrate of Comparative Examples 1-14. A polishing liquid was prepared. In the preparation of each polishing liquid, first, a basic compound is added to pure water corresponding to 50% by mass of the entire polishing liquid, then colloidal silica having a primary particle size of 35 nm is dispersed, and the balance is 100% in total with pure water. %. Note that 1,2,4-triazole was not contained in any of the polishing liquids of Comparative Examples 1-14.

  In the same manner as in Example 1, the pH of each semiconductor polishing liquid in Comparative Examples 1 to 14 immediately after compounding, the pH of each semiconductor polishing liquid after standing for one day, and the day after standing for one day immediately after compounding The amount of change in pH was measured. The measurement results are shown in Tables 3 and 4.

  In the same manner as in Example 1, the polishing rate when each of the semiconductor polishing liquids of Comparative Examples 1 to 14 immediately after compounding was used was measured. Moreover, the polishing rate at the time of using each semiconductor polishing liquid of Comparative Examples 1-14 after leaving still for one day was measured by the method similar to Example 1. FIG. The measurement results are shown in Tables 3 and 4.

(Comparative Examples 15-18)
A compound having a pKa shown in Table 5 below (here, pKa is pKa ₁ ; the same shall apply hereinafter) and colloidal silica as abrasive particles are blended in the addition amounts shown in Table 5 according to the following procedure, and compared. The polishing liquid for each semiconductor substrate of Examples 15-18 was prepared. In the preparation of each polishing liquid, a compound having pKa was dissolved in pure water corresponding to 50% by mass of the entire polishing liquid, and a basic compound was added thereto. Next, colloidal silica having a primary particle size of 35 nm was dispersed, and the remainder was blended with pure water so that the total amount was 100% by mass. Note that 1,2,4-triazole was not contained in any of the polishing liquids of Comparative Examples 15 to 18.

(Comparative Example 19)
1,2,4-triazole and colloidal silica as abrasive particles were blended in the addition amounts shown in Table 5 according to the following procedure to prepare a semiconductor substrate polishing liquid of Comparative Example 19. In preparation of the polishing liquid, 1% by mass of 1,2,4-triazole was dissolved in pure water corresponding to 50% by mass of the entire polishing liquid, and colloidal silica having a primary particle size of 35 nm was dispersed therein, and the remainder was purified. It mix | blended so that it might become a total of 100 mass% with water. The polishing liquid of Comparative Example 19 did not contain a basic compound.

  In the same manner as in Example 1, the pH of each semiconductor polishing liquid in Comparative Examples 15 to 19 immediately after compounding, the pH of each semiconductor polishing liquid after standing for one day, the pH after standing for one day immediately after compounding The amount of change was measured. Table 5 shows the measurement results.

  In the same manner as in Example 1, the polishing rate was measured when each of the semiconductor polishing liquids of Comparative Examples 15 to 19 immediately after compounding was used. Moreover, the polishing rate at the time of using each semiconductor polishing liquid of Comparative Examples 15-19 after standing for one day was measured by the same method as Example 1. Table 5 shows the measurement results.

(Comparative Example 20)
The basic compound shown in Table 6 below and colloidal silica as abrasive particles were blended in the addition amounts shown in Table 6 according to the following procedure to prepare a polishing liquid for semiconductor substrate of Comparative Example 20. In the preparation of the polishing liquid, first, a basic compound is added to pure water corresponding to 50% by mass of the entire polishing liquid, then colloidal silica having a primary particle size of 17 nm is dispersed, and the balance is 100% by mass with pure water. It mix | blended so that it might become. The polishing liquid of Comparative Example 20 did not contain 1,2,4-triazole.

  In the same manner as in Example 1, the pH of the semiconductor polishing liquid of Comparative Example 20 immediately after compounding and the polishing rate when using the semiconductor polishing liquid of Comparative Example 20 immediately after mixing were measured. Further, the arithmetic average roughness of the polished surface of the silicon wafer after polishing using the semiconductor polishing liquid of Comparative Example 20 was measured in the same manner as in Examples 9 and 10. Table 6 shows the measurement results and arithmetic average roughness.

  In FIG. 1, pH immediately after the mixing | blending of each polishing liquid of Examples 1-4 and Comparative Examples 1-11 and the amount of pH change of each polishing liquid after leaving still for one day are shown. FIG. 2 shows the pH and polishing rate immediately after the mixing of the polishing liquids of Examples 1 to 4 and Comparative Examples 1 to 11, and the pH and polishing speed after each polishing liquid was allowed to stand for one day. In FIG. 3, the relationship between the addition amount of the abrasive grains (silica) in each polishing liquid of an Example and a comparative example, and the pH variation | change_quantity of each polishing liquid after standing for one day immediately after mix | blending is shown. 1 to 3, “TA” is an example including 1,2,4-triazole, and other marks are comparative examples not including 1,2,4-triazole. “TMAH” means containing tetramethylammonium hydroxide, and “KOH” means containing potassium hydroxide.

  As described above, the polishing liquids for semiconductor substrates of Examples 1 to 8 contain silica and 1,2,4-triazole and a basic compound (tetramethylammonium hydroxide as a nitrogen-containing basic compound or inorganic). Potassium hydroxide) as a basic compound. And in the polishing liquid for semiconductor substrates of Examples 1-8, content of a basic compound is 0.1 mass% or more, and pH is 9-12. In such Examples 1-8, compared with the comparative example similar to each example, the pH immediately after compounding is not significantly different between the polishing rate immediately after compounding the polishing liquid and the polishing rate after standing for one day, It was also found that the amount of change in pH after standing for one day was extremely small. Therefore, it was found that the semiconductor substrate polishing liquid of the present invention can polish silicon at a high speed and the polishing speed is stable.

  On the other hand, Comparative Examples 1 to 5 contain tetramethylammonium hydroxide as a solubilizer as in Examples 1 to 6. However, the pH values of Comparative Examples 1 to 5 are almost the same as those of Examples with the addition of a very small amount of tetramethylammonium hydroxide. In such Comparative Examples 1 to 5, the polishing rate is slower than in the Examples, the amount of pH change immediately after blending the polishing liquid and after standing for one day is large, and the polishing rate after standing for one day is also reduced. I understood it.

  Moreover, Comparative Examples 6-14 contain potassium hydroxide as a solubilizer. Similar to the comparative example described above, the pH of Comparative Examples 6 to 14 is almost the same as that of the example with the addition of a very small amount of potassium hydroxide. In Comparative Examples 6 to 14, the polishing rate is slower than in the Examples, the amount of change in pH immediately after blending the polishing liquid and after standing for one day is large, and the polishing rate after standing for one day is also reduced. I understood it. Moreover, in Comparative Examples 6-14, compared with the polishing liquid which uses tetramethylammonium hydroxide as a solubilizer, there was a tendency for the amount of pH change after standing for one day to increase.

  In Comparative Example 15, the same azole imidazole was added instead of 1,2,4-triazole. In Comparative Example 15, since the pKa was as high as 14.5, the same pH as in Example 3 was obtained with the addition of a very small amount of tetramethylammonium hydroxide. In Comparative Example 15, the polishing rate is slower than in Example 3, and the same azole system as 1,2,4-triazole is used, but the pH change immediately after blending the polishing liquid and after standing for one day. The amount was large, and it was found that the polishing rate after standing for one day also decreased.

  In Comparative Example 16, the same azole-based 1,2,3-benzotriazole was added instead of 1,2,4-triazole. In Comparative Example 16, the pKa was 8.2, and the amount of tetramethylammonium hydroxide that could be added was larger than when no 1,2,3-benzotriazole was added. However, in Comparative Example 16, the polishing rate is slower than in Example 3, the amount of change in pH immediately after blending the polishing liquid and after standing for one day is large, and the polishing rate after standing for one day may also decrease. all right.

  In Comparative Examples 17 and 18, an acid was added instead of 1,2,4-triazole. In Comparative Example 17 in which malic acid was added, tetramethylammonium hydroxide could be added in a larger amount than in the case where malic acid was not added, and in a larger amount than in Example 3. In Comparative Example 17, the polishing rate was the same as in Example 3, but the amount of change in pH immediately after blending the polishing liquid and after standing for one day was large, and it was found that the polishing rate after standing for one day also decreased. It was. In Comparative Example 18 in which sulfuric acid was added, potassium hydroxide could be added more than in the case where sulfuric acid was not added, and there were more amounts than in Example 7. However, in Comparative Example 18, the polishing rate is slower than in Example 7, the amount of change in pH immediately after blending the polishing liquid and after standing for one day is large, and the polishing rate after standing for one day may also decrease. all right.

  Comparative Example 19 is a polishing liquid containing 1,2,4-triazole alone. In Comparative Example 19, there was no change in pH and polishing rate immediately after blending the polishing liquid and after standing for one day, but the polishing rate was as low as less than 200 nm / min, and 1,2,4-triazole alone was used for polishing. It was found that there was almost no effect of increasing the speed.

  Moreover, when Example 9 and 10 and Comparative Example 20 were compared, it turned out that the roughness of the surface after completion | finish of grinding | polishing can be suppressed because polishing liquid contains 1,2, 4- triazole.

<Second polishing liquid for semiconductor substrate>

[Preparation of polishing liquid for zeta potential measurement]
A basic compound (potassium hydroxide) was added to pure water corresponding to 50% by mass of the entire semiconductor polishing liquid until the pH reached 9. Next, 0.5% by mass of modified colloidal silica whose surface was modified with aluminate was added as abrasive grains (abrasive particles), and then mixed with pure water to a total of 95% by mass. A basic compound (potassium hydroxide) was added to a pH of 11, and the remainder was blended with pure water so that the total amount was 100% by mass. In this way, a polishing liquid C for zeta potential measurement was prepared.

The modified colloidal silica added to the polishing liquid C for measuring the zeta potential is obtained by adding potassium aluminate [(AlO (OH) ₂ K] to the silica dispersion and refluxing at 60 ° C. or higher so that the silica surface The silanol group is obtained by making it a -Si-O-Al (OH) ₂ group which is more easily ionized.

  The zeta potential measurement polishing liquids A, B, D, E, F, G, and H were prepared in the same manner as the zeta potential measurement polishing liquid C except that the abrasive grains and basic compounds shown in Table 7 were used. Each was prepared. In addition, all the abrasive grains shown in Table 7 were purchased from an abrasive manufacturer.

[Measurement of zeta potential]
Under the following measurement conditions, the zeta potential of the abrasive grains in each polishing liquid for zeta potential measurement was measured.
Measuring principle: Laser Doppler method zeta potential measuring device: ZETASIZER3000HS (manufactured by MALVERN)
Measurement temperature: 25 ° C
Refractive index of dispersion medium: 1.331
Dispersion medium viscosity: 0.893 cP

(Examples 11 to 16)
[Preparation of polishing liquid for semiconductor]
Each of the polishing liquids for semiconductors of Examples 11 to 16 was prepared by blending the modified silica with aluminate and the inorganic basic compound shown in Table 8 below in the addition amount shown in Table 8 according to the following procedure. The “modified silica with aluminate” shown in Table 8 is a modified colloidal silica modified with aluminate, and is the same as that added to the polishing liquid C for zeta potential measurement.

  In the preparation of each polishing liquid, first, potassium hydroxide as an inorganic basic compound was added to pure water corresponding to 50% by mass of the entire polishing liquid until the pH reached 9. Next, modified colloidal silica modified with aluminate was dispersed as abrasive grains, and blended with pure water to a total of 95% by mass. Furthermore, potassium hydroxide was added to a desired pH, and the remainder was blended with pure water so that the total amount was 100% by mass.

(Example 17)
As shown in Table 8, 1% by mass of 1,2,4-triazole was dissolved in pure water corresponding to 50% by mass of the entire polishing liquid, and potassium hydroxide was added thereto until the pH reached 9. . Next, modified colloidal silica modified with aluminate was dispersed as abrasive grains, and blended with pure water to a total of 95% by mass. Potassium hydroxide was added until the pH was 11, and the remainder was mixed with pure water so that the total amount was 100% by mass. Thus, the polishing liquid for semiconductor substrates of Example 17 was prepared.

[PH measurement]
The pH of each of the semiconductor polishing liquids of Examples 11 to 17 was measured by the following method. Table 8 shows the pH of each semiconductor polishing liquid.
(Measurement method of pH)
pH meter: Model pH81 manufactured by Yokogawa Electric Corporation
Calibration: Two-point calibration with neutral phosphate pH buffer pH 6.86 (25 ° C) and borate pH standard solution (pH 9.18) (25 ° C) Measurement temperature: 25 ° C
Magnetic Stirrer: AS-30 HS-30D
Measurement procedure: Using a stirrer coated with a fluororesin having a major axis of about 4 cm and a minor axis of about 0.5 cm, pH was measured in a state where the polishing liquid was stirred at 500 rpm.
Measurement period: Immediately after blending the polishing liquid

[Semiconductor substrate polishing]
While supplying the semiconductor substrate polishing liquid of Example 11 immediately after blending onto the polishing cloth of the polishing surface plate, the polishing surface plate is rotated relative to the semiconductor substrate while the semiconductor substrate is pressed against the polishing cloth. As a result, the surface of the semiconductor substrate was polished. Moreover, the semiconductor substrate was grind | polished by the method similar to Example 11 using each polishing liquid of Examples 12-17 immediately after mix | blending. The details of the polishing conditions are as follows.
(Polishing conditions)
Polishing device: FACT-200 type polishing cloth manufactured by Nano Factor: IC-1010 manufactured by Nitta Haas
Polishing platen rotation speed: 80rpm
Holder rotation speed: No drive (free rotation)
Polishing pressure: 33.83 kPa (345 gf / cm ² )
Polishing liquid supply amount: 16 ml / min Polishing time: 5 minutes Semiconductor substrate (object to be polished): 2 cm square silicon wafer (P type <100>)

[Washing]
After polishing, the semiconductor substrate was cleaned with a polyvinyl alcohol brush and ultrasonic water. After cleaning, the semiconductor substrate was dried with a spin dryer.

[Measurement of polishing rate]
After polishing the silicon wafer by the above method using each of the semiconductor polishing liquids of Examples 11 to 17 immediately after blending, the amount of decrease in the mass of the silicon wafer accompanying polishing was measured. Then, the polishing rate (unit: nm / min) was measured from the decrease in mass, wafer area, specific gravity of silicon, and polishing time. The measurement results are shown in Table 2. In addition, the electronic balance for analysis (AB104 made from METTLER) was used for the mass measurement of a silicon wafer. The measurement temperature was 25 ° C., and the measurement humidity was 40% RH or higher. The specific gravity of silicon was 2.33.

(Comparative Examples 21-27)
Unmodified colloidal silica and basic compounds shown in Tables 9 and 10 were blended in the addition amounts shown in Tables 9 and 10 according to the following procedures to prepare polishing liquids for semiconductors of Comparative Examples 21 to 27. . In addition, all the silica shown in Tables 9 and 10 was purchased from an abrasive manufacturer.

  In the preparation of each polishing liquid, first, a basic compound was added to pure water corresponding to 50% by mass of the entire polishing liquid until the pH reached 9. Next, unmodified colloidal silica was dispersed as abrasive grains and blended with pure water so that the total amount was 95% by mass. Furthermore, the basic compound was added to the desired pH, and the remainder was blended with pure water so that the total amount was 100% by mass.

(Comparative Example 28)
As shown in Table 10, 1% by mass of 1,2,4-triazole was dissolved in pure water corresponding to 50% by mass of the entire polishing liquid, and potassium hydroxide was added thereto until the pH reached 9. . Next, unmodified colloidal silica was dispersed as abrasive grains and blended with pure water so that the total amount was 95% by mass. Potassium hydroxide was added until the pH was 11, and the remainder was mixed with pure water so that the total amount was 100% by mass. Thus, the polishing liquid for semiconductor substrates of Comparative Example 28 was prepared.

(Comparative Examples 29-32)
The modified silica and basic compound shown in Table 10 were blended in the addition amounts shown in Table 10 according to the following procedure to prepare polishing liquids for semiconductors of Comparative Examples 29-32.

  In the preparation of each polishing liquid, first, a basic compound was added to pure water corresponding to 50% by mass of the entire polishing liquid until the pH reached 9. Next, the modified modified colloidal silica was dispersed as abrasive grains, and blended with pure water to a total of 95% by mass. Further, a basic compound was added until the pH was 11, and the remainder was blended with pure water so that the total amount was 100% by mass.

  In the same manner as in Example 11, the pH of each semiconductor polishing liquid in Comparative Examples 21 to 32 immediately after compounding was measured. The measurement results are shown in Tables 9 and 10.

  In the same manner as in Example 11, the polishing rate when each of the semiconductor polishing liquids of Comparative Examples 21 to 32 immediately after blending was used was measured. The measurement results are shown in Tables 9 and 10.

  FIG. 6 shows the pH and polishing rate of each of the polishing liquids of Examples 11-14 and Comparative Examples 21-24.

  Of Examples 11 to 14, 16 and Comparative Examples 21 to 24, 26, 27, 29 to 32, when Examples and Comparative Examples having the same abrasive grain addition amount and pH are compared, polishing of Examples It was confirmed that the speed was always higher than that of the comparative example.

  In Example 17, it was confirmed that the polishing rate of Example 17 was higher than that of Comparative Example 25 although the amount of added abrasive grains and pH were smaller than Comparative Example 25. In addition, both Example 17 and Comparative Example 28 contain 1,2,4 triazole, and the polishing rate of Example 17 is comparative even though the primary particle diameter, addition amount and pH of both abrasive grains are equal. It was confirmed to be higher than Example 28.

<Third semiconductor substrate polishing liquid>
(Examples 18 to 24)
[Preparation of polishing liquid for semiconductor]
Abrasive particles, water-soluble polymer (water-soluble polymer), 1,2,4-triazole, and basic compound were blended in the addition amounts shown in Table 11 according to the following procedure, and each of Examples 18-24 A semiconductor polishing liquid was prepared. For the preparation of each polishing liquid, one of three types of polyvinylpyrrolidone (PVP_K15, PVP_K30, and PVP_K90) having different K values was used as a water-soluble polymer. Here, the K value expressed as K15 or the like is a viscosity characteristic value correlated with the molecular weight, and is a relative viscosity value at 25 ° C. measured by a capillary viscometer.

  In the preparation of each polishing liquid, first, 1,2,4-triazole and polyvinylpyrrolidone (PVP) are dissolved in pure water corresponding to 50% by mass of the entire polishing liquid, and a basic compound is added to this until the pH reaches 9. Added. Next, 0.5% by mass of colloidal silica having a primary particle size of 17 nm was dispersed, and then mixed with pure water so that the total amount became 95% by mass. And a basic compound was added until it became desired pH, and it mix | blended so that the remainder might be 100 mass% in total with a pure water.

[PH measurement]
The pH of each of the semiconductor polishing liquids of Examples 18 to 24 was measured by the following method. The pH of each semiconductor polishing liquid is shown in Table 11.
(Measurement method of pH)
pH meter: Model pH81 manufactured by Yokogawa Electric Corporation
Calibration: Two-point calibration with neutral phosphate pH buffer pH 6.86 (25 ° C) and borate pH standard solution (pH 9.18) (25 ° C) Measurement temperature: 25 ° C
Magnetic Stirrer: AS-30 HS-30D
Measurement procedure: Using a stirrer coated with a fluororesin having a major axis of about 4 cm and a minor axis of about 0.5 cm, pH was measured in a state where the polishing liquid was stirred at 500 rpm.
Timing of measurement: Immediately after blending the polishing liquid (immediately after blending means less than one hour after completion of adjustment (mixing) of the polishing liquid for semiconductor, and so on).

[Semiconductor substrate polishing]
While supplying the semiconductor substrate polishing liquid of Example 18 immediately after blending onto the polishing cloth of the polishing surface plate, the polishing surface plate is rotated relative to the semiconductor substrate while the semiconductor substrate is pressed against the polishing cloth. As a result, the surface of the semiconductor substrate was polished. Moreover, the semiconductor substrate was grind | polished by the method similar to Example 18 using each polishing liquid of Examples 19-24 immediately after mix | blending. The details of the polishing conditions are as follows.
(Polishing conditions)
Polishing device: FACT-200 type polishing cloth manufactured by Nano Factor: IC-1010 manufactured by Nitta Haas
Polishing platen rotation speed: 80rpm
Holder rotation speed: No drive (free rotation)
Polishing pressure: 33.83 kPa (345 gf / cm ² )
Polishing liquid supply amount: 16 ml / min Polishing time: 5 minutes Semiconductor substrate (object to be polished): 2 cm square silicon wafer (P type <100>)

[Washing]
After polishing, the semiconductor substrate was cleaned with a polyvinyl alcohol brush and ultrasonic water. After cleaning, the semiconductor substrate was dried with a spin dryer.

[Measurement of polishing rate]
The silicon wafer was polished by the above-described method using each of the semiconductor polishing liquids of Examples 18 to 24 immediately after blending, and then the amount of decrease in the mass of the silicon wafer accompanying polishing was measured. Then, the polishing rate (unit: nm / min) was calculated from the decrease in mass, the wafer area, the specific gravity of silicon, and the polishing time. Table 11 shows the calculation results. In addition, the electronic balance for analysis (AB104 made from METTLER) was used for the mass measurement of a silicon wafer. The measurement temperature was 25 ° C., and the measurement humidity was 40% RH or higher. The specific gravity of silicon was 2.33.

[Surface roughness evaluation]
After polishing the silicon wafer by the above method using the polishing liquids of Examples 18 to 24, the arithmetic average roughness of the polished surface of the silicon wafer was measured using the step, surface roughness, and fine shape measuring device under the following conditions: Measured with Table 11 shows the measurement results.
(Measurement condition)
Step, surface roughness, fine shape measuring device: P16-OF manufactured by KLA Tencor
Measurement mode: Roughness
Measurement length: 200 μm
Measurement speed: 5 μm / sec Measurement load: 1 mg

(Comparative Example 33)
Polishing particles for semiconductors of Comparative Example 33 were prepared by blending the abrasive particles, water-soluble polymer (water-soluble polymer), and inorganic basic compound shown in Table 12 below in the amounts shown in Table 12 according to the following procedure. Prepared. Note that 1,2,4-triazole was not added to the polishing liquid of Comparative Example 33.

  In the preparation of the polishing liquid of Comparative Example 33, 0.05% by mass of polyvinylpyrrolidone (PVP_K30) was dissolved in pure water corresponding to 50% by mass of the whole polishing liquid, and potassium hydroxide was added to this until the pH reached 9. Added. Next, 0.5% by mass of colloidal silica having a primary particle size of 17 nm was dispersed, and then mixed with pure water so that the total amount became 95% by mass. And potassium hydroxide was added to desired pH, and the remainder was mix | blended so that it might become a total of 100 mass% with a pure water.

(Comparative Example 34)
Abrasive particles shown in Table 12 below, 1,2,4-triazole, and an inorganic basic compound were blended in the addition amounts shown in Table 12 according to the following procedure to prepare a semiconductor polishing liquid of Comparative Example 2. .
In addition, polyvinyl pyrrolidone was not added to the polishing liquid of Comparative Example 34.

  In the preparation of the polishing liquid of Comparative Example 34, 0.5% by mass of 1,2,4-triazole was dissolved in pure water corresponding to 50% by mass of the entire polishing liquid, and potassium hydroxide was adjusted to a pH of 9. Added until. Next, 0.5% by mass of colloidal silica having a primary particle size of 17 nm was dispersed, and then mixed with pure water so that the total amount became 95% by mass. And potassium hydroxide was added to desired pH, and the remainder was mix | blended so that it might become a total of 100 mass% with a pure water.

(Comparative Example 35)
Polishing particles and inorganic basic compounds shown in Table 12 below were blended in the addition amounts shown in Table 12 according to the following procedure to prepare a polishing liquid for semiconductor of Comparative Example 35. Note that 1,2,4-triazole and polyvinylpyrrolidone were not added to the polishing liquid of Comparative Example 35.

  In the preparation of the polishing liquid of Comparative Example 35, potassium hydroxide was added to pure water corresponding to 50% by mass of the entire polishing liquid until the pH reached 9. Next, 0.5% by mass of colloidal silica having a primary particle size of 17 nm was dispersed, and then mixed with pure water so that the total amount became 95% by mass. And potassium hydroxide was added to desired pH, and the remainder was mix | blended so that it might become a total of 100 mass% with a pure water.

  In the same manner as in Example 18, the pH and polishing rate of each of the semiconductor polishing liquids of Comparative Examples 33 to 35 and the arithmetic average roughness of the surface of the semiconductor substrate after polishing using each of the polishing liquids of Comparative Examples 33 to 35 were used. And the maximum height was measured. Table 12 shows the measurement results.

  In Example 19, it was confirmed that the polishing rate was high, and the arithmetic average roughness and the maximum height were small compared to Comparative Example 33 which was the same as Example 19 except that it did not contain 1,2,4 triazole. It was. In Comparative Examples 34 and 35, it was confirmed that the arithmetic average roughness and the maximum height were larger than those in Examples 18 to 24. From the above, in the present invention, it was confirmed that the surface of the semiconductor substrate can be polished to a smooth surface with few irregularities at a high polishing rate.

<Fourth polishing liquid for semiconductor substrate>
(Examples 25-36)
[Preparation of polishing liquid for semiconductor]
Abrasive particles, a water-soluble polymer (water-soluble polymer), 1,2,4-triazole, and a basic compound were blended in the addition amounts shown in Table 13 according to the following procedure, and each of Examples 25-36. A semiconductor polishing liquid was prepared. For the preparation of each polishing liquid, polyvinylpyrrolidone (PVP_K30) was used as a water-soluble polymer. The K value is a viscosity characteristic value that correlates with the molecular weight, and is a relative viscosity value at 25 ° C. measured by a capillary viscometer.

  In the preparation of each polishing liquid, first, 1,2,4-triazole and polyvinylpyrrolidone (PVP) are dissolved in pure water corresponding to 50% by mass of the entire polishing liquid, and a basic compound is added to this until the pH reaches 9. Added. Next, 0.3% by mass of colloidal silica having a primary particle size of 17 nm was dispersed, and then mixed with pure water so that the total amount became 95% by mass. And a basic compound was added until it became desired pH, and it mix | blended so that the remainder might be 100 mass% in total with a pure water.

[PH measurement]
The pH of each of the semiconductor polishing liquids of Examples 25 to 36 was measured in the same manner as in Example 18. Table 13 shows the pH of each semiconductor polishing liquid.

[Adjustment of coarsely polished semiconductor substrate]
A silicon wafer having a diameter of 300 mm was polished under the following conditions to prepare a silicon wafer whose surface was roughly polished.

Polishing wafer: 300 mm silicon wafer polishing machine: Reflexion (manufactured by Applied Materials)
Polishing platen rotation speed: 123rpm
Holder rotation speed: 117rpm
Polishing pressure: 13.7 kPa
Polishing liquid supply amount: 250 ml / min Polishing pad: SUBA600 (manufactured by Nitta Haas)
Polishing liquid: silica abrasive grains (primary particle size 17 nm) 0.5%, tetramethylammonium hydroxide (hereinafter referred to as “TMAH”), pH 10.5
Polishing time: 90 seconds

[Semiconductor substrate polishing]
While supplying the semiconductor substrate polishing liquid of Example 25 immediately after blending onto the polishing cloth of the polishing surface plate, the polishing surface plate is rotated relative to the semiconductor substrate while the semiconductor substrate is pressed against the polishing cloth. As a result, the surface of the semiconductor substrate was polished. Moreover, the semiconductor substrate was grind | polished by the method similar to Example 25 using each polishing liquid of Examples 26-36 immediately after mixing | blending. The details of the polishing conditions are as follows.
(Polishing conditions)
Polishing wafer: 300 mm silicon wafer polishing machine after rough polishing created above: Reflexion (manufactured by Applied Materials)
Polishing platen rotation speed: 123rpm
Holder rotation speed: 117rpm
Polishing pressure: 9.7 kPa
Polishing liquid supply amount: 250 ml / min Polishing pad: Supreme RN-H Pad 30.5 "D PJ; CX01 (made by Nitta Haas)
Polishing time: 10 minutes

[Washing]
The polished wafer was cleaned under the following conditions.
Washing machine: MESA (Applied Materials)
Cleaning solution: ammonium hydroxide 0.06% by volume
Brush cleaning time: 60 seconds

[Measurement of number of defects and HAZE value]
After polishing and cleaning the silicon wafer by the above method using the polishing liquids of Examples 25 to 36, the values displayed as the number of defects and the HAZE (haze) value were measured using the following apparatus. Table 13 shows the measurement results.
Defect inspection system: LS6700 (manufactured by Hitachi Electronics Engineering)
Process condition file (measurement recipe): VeM10L
Defect measurement range: 0.1 μm-3.0 μm
Projection condition: Vertical

(Comparative Examples 36-39)
[Preparation of polishing liquid for semiconductor]
Abrasive particles, a water-soluble polymer (water-soluble polymer), 1,2,4-triazole, and a basic compound were blended in the amounts shown in Table 14 according to the following procedure, and each of Comparative Examples 36 to 39 was added. A semiconductor polishing liquid was prepared. For the preparation of each polishing liquid, polyvinylpyrrolidone (PVP_K30) was used as a water-soluble polymer. The K value is a viscosity characteristic value that correlates with the molecular weight, and is a relative viscosity value at 25 ° C. measured by a capillary viscometer.

  In the preparation of each polishing liquid, first, 1,2,4-triazole and polyvinylpyrrolidone (PVP) are dissolved in pure water corresponding to 50% by mass of the entire polishing liquid, and a basic compound is added to this until the pH reaches 9. Added. Next, 0.3% by mass of colloidal silica having a primary particle size of 17 nm was dispersed, and then mixed with pure water so that the total amount became 95% by mass. And a basic compound was added until it became desired pH, and it mix | blended so that the remainder might be 100 mass% in total with a pure water.

  In the same manner as in Example 25, the pH of each semiconductor polishing liquid in Comparative Examples 36 to 39, and the number of defects and the HAZE value on the surface of the silicon wafer after polishing using each polishing liquid in Comparative Examples 36 to 39 were measured. did. Table 14 shows the measurement results.

  In Examples 25 to 36, compared with Comparative Examples 36 to 39, the number of defects was small, and the value of HAZE serving as an index of surface roughness was also small, and it was confirmed that unevenness could be eliminated.

<Fifth polishing liquid for semiconductor substrate>
(Examples 37 to 44)
[Preparation of polishing liquid for semiconductor]
Abrasive particles, water-soluble polymer (water-soluble polymer), 1,2,4-triazole, and basic compound were blended in the addition amounts shown in Table 15 according to the following procedure, and each of Examples 37-44 A semiconductor polishing liquid was prepared. For the preparation of each polishing liquid, one of three types of polyvinylpyrrolidone (PVP_K15, PVP_K30, and PVP_K90) having different K values was used as a water-soluble polymer. Was used. The K value is a viscosity characteristic value that correlates with the molecular weight, and is a relative viscosity value at 25 ° C. measured by a capillary viscometer.

  In the preparation of each polishing liquid, first, 1,2,4-triazole and polyvinylpyrrolidone (PVP) are dissolved in pure water corresponding to 50% by mass of the entire polishing liquid, and a basic compound is added to this until the pH reaches 9. Added. Next, 0.5% by mass of colloidal silica having a primary particle size of 17 nm was dispersed, and then mixed with pure water so that the total amount became 95% by mass. And a basic compound was added until it became desired pH, and it mix | blended so that the remainder might be 100 mass% in total with a pure water.

[PH measurement]
The pH of each of the semiconductor polishing liquids of Examples 37 to 44 was measured in the same manner as in Example 18. Table 15 shows the pH of each semiconductor polishing liquid.

[Semiconductor substrate polishing]
While supplying the semiconductor substrate polishing liquid of Example 37 immediately after blending onto the polishing cloth of the polishing surface plate, the polishing surface plate is rotated relative to the semiconductor substrate while the semiconductor substrate is pressed against the polishing cloth. As a result, the surface of the semiconductor substrate was polished. Further, in the same manner as in Example 37, the semiconductor substrate was polished using the polishing liquids of Examples 38 to 44 immediately after compounding. The details of the polishing conditions are as follows.
(Polishing conditions)
Polishing wafer: 300 mm silicon wafer polishing machine after grinding: Reflexion (manufactured by Applied Materials)
Polishing platen rotation speed: 123rpm
Holder rotation speed: 117rpm
Polishing pressure: 13.7 kPa
Polishing liquid supply amount: 250 ml / min Polishing pad: MH-S15C (manufactured by Nitta Haas)

[Washing]
The polished wafer was cleaned under the following conditions.
Washing machine: MESA (Applied Materials)
Cleaning solution: ammonium hydroxide 0.06% by volume
Brush cleaning time: 60 seconds

[Measurement of polishing rate]
After the silicon wafer was polished by the above method, the amount of decrease in the mass of the silicon wafer accompanying polishing was measured. Then, the polishing rate (unit: nm / min) was calculated from the decrease in mass, the wafer area (706.5 cm 2), the specific gravity of silicon, and the polishing time. In addition, the electronic balance for analysis (AB104 made from METTLER) was used for the mass measurement of a silicon wafer. The measurement temperature was 25 ° C., and the measurement humidity was 40% RH or higher. The specific gravity of silicon was 2.33. Table 15 shows the measurement results.

[Surface roughness evaluation]
After the silicon wafer was polished by the above method, a defect evaluation of the polished surface of the silicon wafer was performed under the following conditions using a step / surface roughness / fine shape measuring apparatus. Note that the target polishing amount of the rough wafer is L (nm), the initial step (maximum height) R _t0 (nm) of the rough wafer, and the step (maximum height) R _t1 (nm) of the rough polished rough wafer. did. Table 15 shows the measurement results.
(Measurement condition)
Step, surface roughness, fine shape measuring device: P16-OF manufactured by KLA Tencor
Measurement mode: Roughness
Measurement length: 5mm
Measurement load: 1mg

(Comparative Examples 40-42)
[Preparation of polishing liquid for semiconductor]
Abrasive particles, 1,2,4-triazole, and a basic compound were blended in the addition amounts shown in Table 16 according to the following procedure to prepare polishing liquids for semiconductors of Comparative Examples 40 to 42.

  In preparation of each polishing liquid, first, 1,2,4-triazole was dissolved in pure water corresponding to 50% by mass of the entire polishing liquid, and a basic compound was added thereto until the pH reached 9. Next, in Comparative Example 40, 0.5% by mass of colloidal silica having a primary particle size of 36 nm was dispersed, and then mixed with pure water so that the total amount became 95% by mass. And a basic compound was added until it became desired pH, and it mix | blended so that the remainder might be 100 mass% in total with a pure water. In Comparative Example 41, 0.5% by mass of colloidal silica having a primary particle size of 7 nm was dispersed, and then mixed with pure water so that the total amount became 95% by mass. And a basic compound was added until it became desired pH, and it mix | blended so that the remainder might be 100 mass% in total with a pure water. In Comparative Example 42, 0.5% by mass of colloidal silica having a primary particle size of 17 nm was dispersed, and then mixed with pure water so that the total amount became 95% by mass. And a basic compound was added until it became desired pH, and it mix | blended so that the remainder might be 100 mass% in total with a pure water. In Comparative Example 42, 1,2,4-triazole was not added.

  In the same manner as in Example 37, the pH of each of the semiconductor polishing liquids of Comparative Examples 40 to 42, the polishing rate measurement when the silicon wafer was polished using each of the polishing liquids of Comparative Examples 40 to 42, and surface roughness Evaluation was made. The measurement results are shown in Table 16.

In Examples 37 to 44, compared with Comparative Examples 40 to 42, the grinding mark removal efficiency with respect to the polishing amount L was excellent, and the grinding mark depth R _t1 after polishing was small. That is, it was confirmed that the unevenness can be eliminated with a small polishing amount.

  For the polishing liquids of Example 37 and Comparative Example 40, polishing was performed again in order to investigate the polishing amount L and the grinding mark resolvability in more detail (Example 45 and Comparative Example 43, respectively). A silicon wafer having a grinding mark with a depth of around 1000 nm is polished in advance 7 times, and in each polishing amount L, a portion 0 mm from the center of the wafer (Center), a portion 60 mm from the center of the wafer (Middle), the wafer The maximum height Rt of a portion 120 mm from the center of the wafer (Edge 1) and a portion 140 mm from the center of the wafer (Edge 2) were measured and evaluated. The evaluation results are shown in Tables 17 and 18, and FIGS.

  In Example 45, it can be seen that the maximum height Rt with respect to the polishing amount L is lower at an early stage than in Comparative Example 43, and the grinding mark elimination efficiency is excellent.

  DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 2 ... Metal for wiring, 3 ... Silicon damage layer.

Claims (24)

Containing abrasive particles, 1,2,4-triazole, and a basic compound,
The basic compound is a nitrogen-containing basic compound or an inorganic basic compound,
The content of the basic compound is 0.1% by mass or more,
A polishing liquid for silicon material having a pH of 9 or more and 12 or less. The polishing liquid for silicon materials according to claim 1, wherein the nitrogen-containing basic compound contains ammonium hydroxide or tetramethylammonium hydroxide. The polishing liquid for silicon material according to claim 1 or 2, wherein the inorganic basic compound contains potassium hydroxide or sodium hydroxide. It contains a modified silica whose surface is modified with aluminate, and an inorganic basic compound,
The content of the modified silica is 0.01% by mass or more and 1.5% by mass or less,
A polishing liquid for silicon material having a pH of 9 or more and 12 or less. The polishing liquid for silicon materials according to claim 4, wherein the primary particle diameter of the modified silica is 7 to 50 nm. The polishing liquid for silicon material according to claim 4 or 5, wherein the inorganic basic compound contains potassium hydroxide or sodium hydroxide. Furthermore, the polishing liquid for silicon materials as described in any one of Claims 4-6 containing a 1,2,4-triazole. A method for polishing a semiconductor substrate to form a through-silicon via,
Forming a recess on one surface of the silicon substrate;
Embedding a metal in the recess,
Backgrinding the other surface of the silicon substrate;
A method for polishing a semiconductor substrate, comprising: using the polishing liquid for silicon material according to any one of claims 1 to 7 to polish the other surface so that the metal is exposed. Wrapping or grinding a silicon wafer obtained by slicing a silicon single crystal ingot, and then etching the silicon wafer to prepare a rough wafer;
A method of polishing a semiconductor substrate, comprising: a rough polishing step of polishing the rough wafer using the polishing liquid for silicon material according to claim 1. A method of polishing a semiconductor substrate for reuse,
A step of wet-etching the silicon wafer to which the deposit has adhered;
A method for polishing a semiconductor substrate, comprising: a rough polishing step of polishing the wet-etched silicon wafer using the silicon material polishing solution according to claim 1. Containing abrasive particles, 1,2,4-triazole, a water-soluble polymer, and a basic compound,
A polishing liquid for silicon material having a pH of 9 or more and 12 or less. 12. The polishing liquid for silicon material according to claim 11, wherein the content of the water-soluble polymer is 0.001 to 10% by mass with respect to the total mass of the polishing liquid for silicon material . The polishing for silicon material according to claim 11 or 12, wherein the content of 1,2,4-triazole is 0.01 mass% or more and 10 mass% or less with respect to the total mass of the polishing liquid for silicon material . liquid. Containing abrasive particles, 1,2,4-triazole, a water-soluble polymer, and a basic compound,
The content of 1,2,4-triazole is 0.05% by mass or more and 0.5% by mass or less with respect to the total mass of the polishing liquid for silicon material ,
The content of the water-soluble polymer is 0.001% by mass to 0.1% by mass with respect to the total mass of the polishing liquid for silicon material ,
A polishing liquid for silicon material having a pH of 9 or more and 12 or less. Wrapping or grinding a silicon wafer obtained by slicing a silicon single crystal ingot, and then etching the silicon wafer to prepare a rough wafer;
A rough polishing step for polishing the rough wafer;
A polishing method for a semiconductor substrate, comprising: a final polishing step of further polishing the silicon wafer after the rough polishing step using the polishing liquid for silicon material according to any one of claims 11 to 14. A method of polishing a semiconductor substrate for reuse,
A step of wet-etching the silicon wafer to which the deposit has adhered;
A rough polishing step of polishing the wet-etched silicon wafer;
A polishing method for a semiconductor substrate, comprising: a final polishing step of further polishing the silicon wafer after the rough polishing step using the polishing liquid for silicon material according to any one of claims 11 to 14. Containing abrasive particles, 1,2,4-triazole, a water-soluble polymer, and a basic compound,
The content of 1,2,4-triazole is 0.2% by mass or more and 3.0% by mass or less with respect to the total mass of the polishing liquid for silicon material ,
The content of the water-soluble polymer is 0.01% by mass or more and 0.2% by mass or less with respect to the total mass of the polishing liquid for silicon material ,
A polishing liquid for silicon material having a pH of 9 or more and 12 or less. A method of polishing a semiconductor substrate for reuse,
A step of wet-etching the silicon wafer to which deposits have adhered, and then grinding the silicon wafer to prepare a rough wafer;
A method for polishing a semiconductor substrate, comprising: a rough polishing step of polishing the rough wafer using the polishing liquid for silicon material according to claim 11. In the rough polishing step, when the polishing amount of the rough wafer is L (nm), the initial step of the rough wafer is R _t0 (nm), and the step of the rough polished rough wafer is R _t1 (nm) In this case, when a rough wafer is polished by L (nm) satisfying R _t0 ≦ L ≦ R _t0 × 1.3, L / (R _t0 −R _t1 ) ≦ 1.3 and R _t1 ≦ 100 (nm) are satisfied. The method for polishing a semiconductor substrate according to claim 18, wherein both are satisfied. A finish polishing step of polishing the rough wafer after the rough polishing step using a polishing liquid;
The polishing liquid contains abrasive particles, 1,2,4-triazole, a water-soluble polymer, and a basic compound,
The method for polishing a semiconductor substrate according to claim 18 or 19, wherein the pH is 9 or more and 12 or less. A finish polishing step of polishing the rough wafer after the rough polishing step using a polishing liquid;
The polishing liquid contains abrasive particles, 1,2,4-triazole, a water-soluble polymer, and a basic compound,
The content of the 1,2,4-triazole, based on the total weight of Ken Migakueki, not more than 0.05 mass% to 0.5 mass%,
The content of the water-soluble polymer, relative to the total weight of Ken Migakueki, is 0.1 mass% 0.001 mass% or more,
The method for polishing a semiconductor substrate according to claim 18 or 19, wherein the pH is 9 or more and 12 or less. The polishing liquid for silicon materials according to claim 11, wherein the water-soluble polymer is a nonionic polymer. The polishing liquid for silicon material according to claim 22, wherein the nonionic polymer is at least one selected from polyvinylpyrrolidone and a copolymer of polyvinylpyrrolidone. The polishing for silicon material according to any one of claims 11 to 14, 17, 22, or 23, wherein the water-soluble polymer is a mixture containing at least one selected from polyvinylpyrrolidone and a copolymer of polyvinylpyrrolidone. liquid.