KR20070012209A - Polishing composition and polishing method - Google Patents

Abstract

A polishing composition is provided to suitably polish the (0001)Si face, (000-1)C face, and both (0001)Si face and (000-1)C face of a silicon carbide single crystal substrate. The polishing composition contains abrasive particles and an oxo compound, and has a pH of 6 or higher. The oxo compound includes oxygen acid, periodic acid, or salts thereof. The polishing composition further comprises alkali including a lithium compound or ammonia. The polishing composition is used for polishing an object formed of single crystal silicon carbide.

Description

Polishing composition and polishing method {POLISHING COMPOSITION AND POLISHING METHOD}

The present invention provides a polishing composition used for polishing a polishing object made of a semiconductor single crystal, in particular for polishing a polishing object made of a silicon carbide single crystal such as a hexagonal silicon carbide single crystal substrate, and a polishing method using the polishing composition. It is about.

Silicon carbide single crystal substrates, such as 4H-SiC single crystal substrates and 6H-SiC single crystal substrates, are usually a step of pre-polishing the surface of the substrate using a slurry containing diamond abrasive grains and a process of finishing polishing the surface of the pre-polished substrate. Are manufactured. In the final polishing, preliminary polishing removes the amorphous working altered layer formed on the surface of the substrate, and at the same time, the crystal surface of the substrate exposed after the removal of the processed altered layer is planarized. As a polishing composition used at the time of finishing polishing, as disclosed in Japanese Patent Laid-Open No. 2004-290018, a polishing composition having a pH of 7 to 10 containing colloidal silica is known. However, since the polishing composition of this publication has a low ability to polish a crystal surface, when the polishing composition of this publication is used, there is a problem that the time required for finish polishing becomes extremely long.

The 4H-SiC single crystal substrate and the 6H-SiC single crystal substrate which are hexagonal silicon carbide single crystal substrates have both surfaces comprised by the crystal surface of another surface orientation called (0001) Si surface and (000-1) C surface, respectively. The (0001) Si surface of the 4H-SiC single crystal substrate and the 6H-SiC single crystal substrate is the surface of the 4H-SiC single crystal substrate or the 6H-SiC single crystal substrate other than the (0001) Si surface (for example, the (000-1) C surface Oxidation rate and etching rate are lower than Therefore, it has conventionally been difficult to polish a (0001) Si surface at a high polishing rate. Moreover, when the (000-1) C surface of the 4H-SiC single crystal substrate and the 6H-SiC single crystal substrate was polished using the polishing composition of the above publication, there was also a problem that surface defects such as holes were likely to occur.

In addition, since the chemical and mechanical properties of the (0001) Si plane and the (000-1) C plane of the hexagonal silicon carbide single crystal substrate are significantly different, conventionally, when polishing both sides of the hexagonal silicon carbide single crystal substrate, Polishing is performed one by one using two kinds of polishing compositions having different compositions suitable for polishing each of the 0001) Si and (000-1) C surfaces. However, in order to improve the work efficiency, it is preferable that both the (0001) Si surface and the (000-1) C surface can be polished suitably with one kind of polishing composition.

It is a first object of the present invention to provide a polishing composition capable of polishing a (0001) Si surface very suitably and a polishing method using such a polishing composition. A second object of the present invention is to provide a polishing composition capable of polishing the (000-1) C surface very suitably and a polishing method using such a polishing composition. A third object of the present invention is to provide a polishing composition capable of polishing both the (0001) Si surface and the (000-1) C surface very suitably and a polishing method using such a polishing composition.

In order to achieve the above object, the present invention provides a polishing composition containing polishing particles and an oxo compound, and also having a pH of 6 or more.

The present invention also provides a polishing composition containing an oxo compound and having a pH of 8 or less in a polishing composition used for polishing a polishing object made of a semiconductor single crystal.

In addition, the present invention provides a polishing composition containing polishing particles and an oxo compound, and having a pH of 6 to 8 in the polishing composition used for polishing a polishing object made of silicon carbide single crystal.

Moreover, this invention provides the method of grinding | polishing the grinding | polishing object which consists of a silicon carbide single crystal. The method includes a step of adjusting any of the polishing compositions and a polishing step of polishing a polishing object using the adjusted polishing composition.

EMBODIMENT OF THE INVENTION Hereinafter, the 1st and 2nd embodiment of this invention is described.

The polishing composition of the first embodiment is prepared by mixing a predetermined amount of oxo acid salt or peroxo acid salt with a colloidal silica colloidal solution and diluting with water as necessary. Thus, the polishing composition of the first embodiment consists substantially of colloidal silica as polishing particles, oxo- or peroxate as oxo compounds, and water.

The polishing composition of the second embodiment is prepared by mixing a predetermined amount of oxo acid or peroxo with an alkali and a colloidal silica colloidal solution and diluting with water as necessary. Therefore, the polishing composition of the second embodiment substantially consists of colloidal silica as polishing particles, oxo acid or peroxo acid as oxo compound, alkali as pH adjuster, and water. That is, the polishing composition of the second embodiment differs from the polishing composition of the first embodiment in that it contains an oxo acid or a peroxo acid as an oxo compound instead of an oxo acid salt or a peroxate and an alkali. .

The polishing compositions of the first and second embodiments are for polishing 4H-SiC single crystal substrates or 6H-SiC single crystal substrates, and more specifically, (0001) Si faces of 4H-SiC single crystal substrates or 6H-SiC single crystal substrates. Used for polishing.

When the content of the colloidal silica in each polishing composition of the first and second embodiments is less than 0.05% by mass, more specifically, less than 0.1% by mass, more specifically, less than 1% by mass, the polishing composition is There is a fear that they do not have sufficient polishing ability. Therefore, in order to obtain a higher polishing rate, the content of the colloidal silica in each polishing composition of the first and second embodiments is preferably 0.05 mass% or more, more preferably 0.1 mass% or more, most preferably 1 mass. More than% On the other hand, when the content of the colloidal silica in each polishing composition of the first and second embodiments is more than 50% by mass, more specifically, more than 48% by mass, more specifically, more than 45% by mass, commercially available Colloidal silica colloidal solutions of higher concentration than colloidal silica colloidal solutions are of no benefit because they are necessary for the preparation of polishing compositions. Therefore, it is preferable that content of the colloidal silica in each polishing composition of 1st and 2nd embodiment is 50 mass% or less, More preferably, it is 48 mass% or less, Most preferably, it is 45 mass% or less.

Colloidal silica with an average primary particle diameter of less than 5 nm, moreover colloidal silica with an average primary particle diameter of less than 15 nm, more specifically colloidal silica with an average primary particle diameter of less than 25 nm are used to polish (0001) Si faces. The ability is not very high. Therefore, in order to obtain a higher polishing rate, the average primary particle diameter of the colloidal silica included in each polishing composition of the first and second embodiments is preferably 5 nm or more, more preferably 15 nm or more, most preferably Is 25 nm or more. On the other hand, when the average primary particle diameter of the colloidal silica is larger than 120 nm, more specifically, larger than 100 nm, more specifically, larger than 85 nm, the first and second agents may be used for the polishing composition to exhibit sufficient polishing ability. It is necessary to make content of colloidal silica in each polishing composition of 2nd embodiment considerably high. Therefore, in order to reduce the cost of the polishing composition, the average primary particle diameter of the colloidal silica included in each polishing composition of the first and second embodiments is preferably 120 nm or less, more preferably 100 nm or less, most preferably. Preferably 85 nm or less. In addition, the average primary particle diameter of colloidal silica is computed from the specific surface area measured by the BET method, for example.

In order to improve the polishing rate, the oxo compound contained in the polishing composition of the first embodiment may be any of oxo acid salts and peroxate salts, but is preferably a peroxo acid salt, and more preferably metaperioxo. Sodium acid (NaIO ₄ ). Peroxates are preferred because of their higher redox potential and stronger oxidative power than oxoates, and sodium metaperoxate is available compared to other peroxates. It is preferable because of its ease.

The oxo compound included in the polishing composition of the second embodiment may be any of oxo acid and peroxo acid for the purpose of improving the polishing rate. Among them, peroxo acid is preferable, and ortho peroxo acid (H) is more preferable. ₅ IO ₆ ). Peroxo acids are preferred because of their higher redox potential and stronger oxidizing power than oxo acids, and orthoperoxo acids are preferred because they are more readily available than other peroxo acids.

When the content of the oxo compound in each polishing composition of the first and second embodiments is less than 0.1 g / l, more specifically, less than 0.5 g / l, more specifically, less than 1 g / l, too There is a fear that the (0001) Si surface cannot be polished at a high polishing rate. Therefore, in order to obtain a higher polishing rate, the content of the oxo compound in each polishing composition of the first and second embodiments is preferably 0.1 g / l or more, more preferably 0.5 g / l or more, most preferably 1 g / l or more. On the other hand, when the content of the oxo compound in each polishing composition of the first and second embodiments is more than 500 g / l, more specifically, more than 250 g / l, more specifically, more than 100 g / l There is a risk of deterioration of the polishing pad. In addition, when the oxo compound contained in a polishing composition is an oxo acid salt or a peroxo acid salt, there exists a possibility that precipitation may arise in a polishing composition. Therefore, in order to avoid such inconvenience, it is preferable that content of the oxo compound in each polishing composition of 1st and 2nd embodiment is 500 g / L or less, More preferably, it is 250 g / L or less, Most preferably, 100 g / l or less

The alkali contained in the polishing composition of the second embodiment is preferably a lithium compound such as lithium hydroxide (LiOH) or an inorganic lithium salt or ammonia (NH ₃ ) in order to obtain a polishing composition having good storage stability. Preferably lithium hydroxide or ammonia. Specific examples of the inorganic lithium salts include lithium chloride, lithium carbonate, lithium nitrate, lithium lactate, lithium phosphate, and the like. Among them, lithium chloride and lithium carbonate are easily available.

When the content of alkali in the polishing composition of the second embodiment is less than 0.1 g / l, more specifically, less than 0.5 g / l, more specifically, less than 1 g / l, the pH of the polishing composition is Since it is not so high (0001), there exists a possibility that the ability of the polishing composition to polish a Si surface may fall. Therefore, in order to obtain a higher polishing rate, the content of alkali in the polishing composition of the second embodiment is preferably 0.1 g / l or more, more preferably 0.5 g / l or more, most preferably 1 g / l or more to be. On the other hand, when the content of alkali in the polishing composition of the second embodiment is more than 20 g / l, more specifically, more than 15 g / l, more specifically, more than 10 g / l, There exists a possibility that storage stability may fall. Therefore, in order to obtain good storage stability, the content of alkali in the polishing composition of the second embodiment is preferably 20 g / l or less, more preferably 15 g / l or less, most preferably 10 g / l or less. .

It is essential that the pH of each polishing composition of the first and second embodiments is 6 or more in order to realize highly suitable polishing of the (0001) Si surface. However, even if the pH is 6 or more, as the pH is lowered, the ability of each polishing composition to polish the (Si) surface tends to decrease. Therefore, in order to obtain a higher polishing rate, the pH of each polishing composition of the first and second embodiments is preferably 7 or more. On the other hand, when the pH of each polishing composition of the first and second embodiments is too high, there is a fear that the colloidal silica in the polishing composition causes dissolution. Therefore, from the viewpoint of preventing the dissolution of colloidal silica, the pH of each polishing composition of the first and second embodiments is preferably 14 or less, more preferably 13 or less, and most preferably 12 or less.

According to 1st and 2nd embodiment, the following advantages can be acquired.

Each polishing composition of the first and second embodiments has the ability to polish the (0001) Si surface of the 4H-SiC single crystal substrate or the 6H-SiC single crystal substrate at a high polishing rate, as compared with the conventional polishing composition. This is because the oxo compound, oxo acid, or oxo compound composed of such salts contained in each polishing composition of the first and second embodiments exhibits sufficient oxidizing power to oxidize the (0001) Si surface in a pH 6 or higher region. I think.

Alkali is mix | blended with the polishing composition of 2nd Embodiment. Therefore, even if it contains the acid called oxo acid or peroxo acid as an oxo compound, there is no difficulty in preparing the polishing composition of 2nd Embodiment so that pH may be 6 or more.

The first and second embodiments can be modified as follows.

The abrasive grains included in each polishing composition of the first and second embodiments may be silica other than colloidal silica such as fumed silica, or may be alumina or chromium oxide. However, when silica (especially colloidal silica) is used, since it is less likely to be damaged on the surface of the polishing object after polishing, compared to when alumina or chromium oxide is used, silica (especially colloidal silica) is preferable. .

The alkali as a pH adjuster can be added to the polishing composition of 1st Embodiment as needed. Preferable types of alkali added to the polishing composition of the first embodiment and preferred contents of the alkali in the polishing composition of the first embodiment are the same as those of the second embodiment.

The alkali contained in the polishing composition of the second embodiment can be omitted. That is, the polishing composition of the second embodiment may be substantially made of colloidal silica, oxo acid or peroxo acid, and water. However, in order to obtain a higher polishing rate, it is preferable to contain an alkali. In addition, even when alkali is omitted, it is essential that pH of a polishing composition is 6 or more.

Well-known additives, such as a preservative and an antifoamer, can be added to each polishing composition of 1st and 2nd embodiment as needed.

Each polishing composition of the first and second embodiments can be used for polishing a surface of a 4H-SiC single crystal substrate or a 6H-SiC single crystal substrate other than the (0001) Si surface. Or a polishing object composed of a cubic crystal silicon carbide single crystal such as a 3C-SiC single crystal substrate. It can also be used for polishing a polishing object made of a silicon carbide single crystal other than a silicon carbide single crystal substrate, or it can be used for polishing a polishing object other than a polishing object made of a silicon carbide single crystal. However, each polishing composition of the first and second embodiments has a (0001) Si surface of a polishing object, in particular, a 4H-SiC single crystal substrate or a 6H-SiC single crystal substrate, compared with a conventional polishing composition. The ability to polish is particularly high. Therefore, it is preferable to be used for the grinding | polishing object which consists of a silicon carbide single crystal, and it is more preferable to use for the grinding | polishing (0001) Si surface of a 4H-SiC single crystal substrate or a 6H-SiC single crystal substrate.

EMBODIMENT OF THE INVENTION Hereinafter, the Example and comparative example concerning 1st and 2nd embodiment of this invention are demonstrated.

The polishing composition of Examples 1-11 and Comparative Examples 1-13 was prepared by mixing colloidal silica colloid solution, an oxo compound, or a compound which replaces it, and a pH adjuster suitably, and diluting with water as needed. The details of the colloidal silica, oxo compound or the compound and pH adjuster in each polishing composition and the pH of each polishing composition are shown in Table 1. In addition, the average primary particle diameter of the colloidal silica contained in each polishing composition is 35 nm.

Using the polishing compositions of Examples 1 to 11 and Comparative Examples 1 to 13, the (0001) Si surface of the silicon carbide single crystal substrate was polished under the polishing conditions shown in Table 2. The weight of the substrate before and after polishing is measured, and the polishing rate calculated from the measured value is shown in the "polishing rate" column of Table 1.

100 ml of each polishing composition of Examples 1 to 11 and Comparative Examples 1 to 13 were placed in a polycontainer having a capacity of 250 ml, and allowed to stand at room temperature for 3 months, and the appearance change of the polishing composition was regularly observed. Based on the observation result, the result of evaluation about the storage stability of each polishing composition is shown in the "stability" column of Table 1. In the same column, ◎ (excellent) indicates that changes in gelation, precipitation, viscosity increase, etc. were not recognized in the polishing composition after 3 months, and ○ (good) was not recognized after 1 month. After 3 months, the change was recognized.

Colloidal silica Oxo compounds or compounds replacing them pH regulator pH Polishing speed [nm / hr.] stability Content [mass%] designation Content [g / ℓ] designation Content [g / ℓ] Example 1 40 NaIO ₄ 5 - 0 8.2 36.2 ○ Example 2 40 NaIO ₄ 10 - 0 7.8 45.4 ○ Example 3 40 NaIO ₄ 15 - 0 7.5 54.5 ○ Example 4 40 NaIO ₄ 10 LiOH 1.8 10.8 59.4 ○ Example 5 40 H ₅ IO ₆ 10 LiOH 1.8 9.0 48.0 ○ Example 6 40 H ₅ IO ₆ 10 LiOH 0.8 6.5 30.2 ○ Example 7 40 H ₅ IO ₆ 10 LiOH 3.6 10.7 64.0 ○ Example 8 5 H ₅ IO ₆ 10 NH ₃ 0.4 7.4 37.0 ◎ Example 9 10 H ₅ IO ₆ 10 NH ₃ 0.6 7.7 39.0 ◎ Example 10 20 H ₅ IO ₆ 10 NH ₃ 1.2 7.7 49.9 ◎ Example 11 30 H ₅ IO ₆ 10 NH ₃ 1.5 7.4 67.9 ◎ Comparative Example 1 40 - 0 - 0 9.5 11.6 ◎ Comparative Example 2 0 H ₅ IO ₆ 10 - 0 1.2 0.5 ◎ Comparative Example 3 40 - 0 NH ₃ 4.5 10.4 14.0 ◎ Comparative Example 4 40 - 0 Triethanol amine 50 10.2 13.3 ◎ Comparative Example 5 40 - 0 KOH 4.2 10.7 7.2 ○ Comparative Example 6 40 - 0 LiOH 1.8 10.8 8.8 ○ Comparative Example 7 40 - 0 H ₂ SO ₄ 4.9 4.2 8.5 ○ Comparative Example 8 40 NaIO ₄ 5 H ₂ SO ₄ 7.4 1.9 13.3 ○ Comparative Example 9 40 H ₅ IO ₆ 10 - 0 4.7 19.2 ○ Comparative Example 10 40 NaClO ₂ 10 - 0 8.8 6.6 ○ Comparative Example 11 40 NaClO ₃ 10 - 0 8.9 5.7 ○ Comparative Example 12 40 NaClO ₄ 10 - 0 9.0 10.4 ○ Comparative Example 13 40 NaBrO ₃ 10 - 0 9.1 10.9 ○

Polishing object: (0001) Si surface polishing machine of 4H-SiC single crystal substrate having a diameter of 2 inches (50 mm): Supply amount of EJ-380IN polishing composition from Engis Co., Ltd., Japan: 50 ml / min Polishing pressure: 500 g / cm ² Table rotation speed: 80 rpm Head rotation speed: 30 rpm Polishing time: 4 hours Polishing pad: Suba800 of Nitta Haas Co., Ltd.

As shown in Table 1, according to the polishing composition of Examples 1-11, starting with the comparative example 1 corresponded to the polishing composition of Unexamined-Japanese-Patent No. 2004-299018, compared with the polishing composition of Comparative Examples 2-13, , A high polishing rate could be obtained. Moreover, the polishing compositions of Examples 1 to 11 were also capable of satisfying the storage stability. As for the polishing compositions of Comparative Examples 10 to 13, sodium chlorite, sodium chlorate, sodium perchlorate and sodium fluorate were used in place of the oxo compound, but the polishing rates that can be obtained with these polishing compositions were all Examples 1 to 11. It was low compared with the polishing rate which can be obtained with the polishing composition of. These results show that even a halogen compound such as an oxo compound has no effect of increasing the ability of the polishing composition to polish the (0001) Si surface to the chlorine compound and the fluorine compound.

EMBODIMENT OF THE INVENTION Hereinafter, the 3rd Embodiment of this invention is described.

The polishing composition of the third embodiment is prepared by mixing a predetermined amount of an oxo compound and a colloidal silica colloidal solution and diluting with water as necessary. Therefore, the polishing composition of the third embodiment consists essentially of colloidal silica, oxo compound, and water as polishing particles. The polishing composition of the third embodiment is for polishing a 4H-SiC single crystal substrate or a 6H-SiC single crystal substrate, more specifically, a (000-1) C surface of a 4H-SiC single crystal substrate or a 6H-SiC single crystal substrate. It is used for the purpose.

When the content of the colloidal silica in the polishing composition of the third embodiment is less than 0.05% by mass, more specifically, less than 0.1% by mass, more specifically, less than 1% by mass, the polishing composition has sufficient polishing ability. There is a fear that you do not have. Therefore, in order to obtain a higher polishing rate, the content of the colloidal silica in the polishing composition of the third embodiment is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and most preferably 1% by mass or more. On the other hand, when the content of the colloidal silica in the polishing composition of the third embodiment is more than 40 mass%, more specifically, more than 35 mass%, more specifically, more than 30 mass%, the polishing rate is close to saturation. It is not economical because it does not rise so much. Therefore, it is preferable that content of the colloidal silica in the polishing composition of 3rd Embodiment is 40 mass% or less, More preferably, it is 35 mass% or less, Most preferably, it is 30 mass% or less.

Colloidal silicas with an average primary particle diameter of less than 5 nm, more specifically colloidal silicas with an average primary particle diameter of less than 15 nm, more specifically colloidal silicas with an average primary particle diameter of less than 25 nm have a (000-1) C plane. The ability to polish is not very high. Therefore, in order to obtain a higher polishing rate, the average primary particle diameter of the colloidal silica included in the polishing composition of the third embodiment is preferably 5 nm or more, more preferably 15 nm or more, most preferably 25 nm or more. to be. On the other hand, in the case where the average primary particle diameter of the colloidal silica is larger than 120 nm, more specifically, larger than 100 nm, more specifically, larger than 85 nm, the polishing composition exhibits sufficient polishing ability in the third embodiment. It is necessary to make the content of colloidal silica in the polishing composition extremely high. Therefore, in order to reduce the cost of the polishing composition, the average primary particle diameter of the colloidal silica included in the polishing composition of the third embodiment is preferably 120 nm or less, more preferably 100 nm or less, most preferably 85 nm. It is as follows. In addition, the average primary particle diameter of colloidal silica is computed from the specific surface area measured by the BET method, for example.

The oxo compound contained in the polishing composition of the third embodiment for the purpose of improving the polishing rate may be any of oxo acid, peroxo acid and such salts, but it is preferable that the oxo compound or the peroxoate is more preferable. Preferably, orthoperoxoic acid (H ₅ IO ₆ ) or sodium metaperoxonate (NaIO ₄ ). Peroxo acids and peroxoates are preferred because of their high redox potential and strong oxidizing power over oxo acids and oxoacid salts, and ortho and oxo acid and sodium metaperoxate are easier to obtain than other peroxo acids and peroxoates It is preferable because of one point.

When the content of the oxo compound in the polishing composition of the third embodiment is less than 0.1 g / l, more specifically, less than 1 g / l, more specifically, less than 5 g / l, the polishing rate is too high. (000-1) C surface may not be polished. Therefore, in order to obtain a higher polishing rate, the content of the oxo compound in the polishing composition of the third embodiment is preferably 0.1 g / L or more, more preferably 1 g / L or more, most preferably 5 g / L That's it. On the other hand, when the content of the oxo compound in the polishing composition of the third embodiment is more than 500 g / l, more specifically, more than 250 g / l, more specifically, more than 100 g / l, There is a possibility that the deterioration may be accelerated, and in addition, when the oxo compound contained in the polishing composition is an oxo acid salt or a peroxate salt, precipitation may occur in the polishing composition. Therefore, in order to avoid such inconvenience, the content of the oxo compound in the polishing composition of the third embodiment is preferably 500 g / l or less, more preferably 250 g / l or less, and most preferably 100 g / l or less. .

It is essential that pH of the polishing composition of 3rd Embodiment is 8 or less in order to implement | achieve highly suitable grinding | polishing of (000-1) C surface. However, even if pH is 8 or less, as the pH increases, the ability of the polishing composition to polish the (000-1) C surface tends to decrease. Therefore, in order to obtain a higher polishing rate, the pH of the polishing composition of the third embodiment is preferably 7.5 or less, and more preferably 7 or less. On the other hand, when the pH of the polishing composition of the third embodiment is too low, the polishing machine tends to corrode. Therefore, from the viewpoint of preventing corrosion of the polishing machine, the pH of the polishing composition of the third embodiment is preferably 0.5 or more, more preferably 0.8 or more, most preferably 1 or more.

According to the third embodiment, the following advantages can be obtained.

The polishing composition of the third embodiment has the ability to polish the (000-1) C surface of the 4H-SiC single crystal substrate or the 6H-SiC single crystal substrate at a high polishing rate, as compared with the conventional polishing composition. This is because the oxo acid, peroxo acid or the oxo compound composed of such salts contained in the polishing composition of the third embodiment exhibits sufficient oxidizing power to oxidize the (000-1) C plane in the pH 8 or lower region. I think.

The pit, which is a kind of surface defect, is a result of the rapid progress of the polishing of the part which is easy to be polished, compared to the polishing of the part that is hard to be polished. Therefore, compared with the conventional polishing composition, the (000-1) C surface after polishing using the polishing composition of the third embodiment having the ability to polish the (000-1) C surface at a high polishing rate is conventional. There are few pits compared with the (000-1) C surface after grinding | polishing using a polishing composition.

The third embodiment can be changed as follows.

The polishing particles included in the polishing composition of the third embodiment may be silica other than colloidal silica such as fumed silica, or may be alumina or chromium oxide. However, when silica (especially colloidal silica) is used, since it is less likely to be damaged on the surface of the polishing object after polishing, compared to when alumina or chromium oxide is used, silica (especially colloidal silica) is preferable. .

Colloidal silica contained in the polishing composition of the third embodiment can be omitted. That is, the polishing composition of the third embodiment may be substantially made of an oxo compound and water. However, in order to obtain a higher polishing rate, it is preferable to contain polishing particles such as colloidal silica.

Well-known additives, such as a pH adjuster, an antiseptic | preservative, and an antifoamer, can be added to the polishing composition of 3rd Embodiment as needed.

The polishing composition of the third embodiment can be used for polishing a surface of a 4H-SiC single crystal substrate or a 6H-SiC single crystal substrate other than the (000-1) C surface except for the (0001) Si surface. Or a polishing object composed of a cubic crystal silicon carbide single crystal such as a 3C-SiC single crystal substrate. It can also be used for polishing a polishing object made of a silicon carbide single crystal other than a silicon carbide single crystal substrate, or it can be used for polishing a polishing object other than a polishing object made of a silicon carbide single crystal. However, compared with the conventional polishing composition, the polishing composition of the third embodiment is for polishing a (000-1) C surface of a polishing object made of silicon carbide single crystal, in particular, a 4H-SiC single crystal substrate or a 6H-SiC single crystal substrate. The ability is particularly high. Therefore, it is preferable to be used for the grinding | polishing object which consists of a silicon carbide single crystal, and it is more preferable to be used for the grinding | polishing (000-1) C surface of a 4H-SiC single crystal substrate or a 6H-SiC single crystal substrate. .

EMBODIMENT OF THE INVENTION Hereinafter, the Example and comparative example which concern on 3rd Embodiment of this invention are demonstrated.

The polishing compositions of Examples 101 to 116 and Comparative Examples 101 to 111 were prepared by appropriately mixing the polishing particles, the oxo compound or the compound substituted therewith, and the pH adjusting agent, and diluting with water as necessary. Table 3 shows the details of the abrasive particles, the oxo compound or the compound instead of the compound and the pH adjuster in each polishing composition, and the pH of each polishing composition.

First, the (000-1) C plane of the silicon carbide single crystal substrate was preliminarily polished under the polishing conditions shown in Table 4 using a slurry containing polycrystalline diamond abrasive grains having an average particle diameter of 0.5 mu m. Thereafter, the (000-1) C plane of the preliminarily polished silicon carbide single crystal substrate was subjected to finish polishing under the polishing conditions shown in Table 5 using the polishing compositions of Examples 101 to 116 and Comparative Examples 101 to 111. The weight of the board | substrate before and after finish grinding | polishing is measured, and the polishing rate computed from the measured value is shown in the "polishing rate" column of Table 3.

Moreover, the (000-1) C surface after finish grinding | polishing was observed by 50 times the magnification with an optical microscope. Based on the observation result, the evaluation result about the generation | occurrence | production situation of the surface defect by each polishing composition is shown in the "surface state" column of Table 3. In the same column, ○ (good) indicates that any one of the pits, the step and the face was not recognized, and × (defect) indicates that any one of the pits, the step and the face was recognized. In addition, when the (000-1) C plane after prepolishing was observed at 50 times the magnification by an optical microscope prior to the finish polishing, none of pits, steps and faces were recognized.

Abrasive particles Oxo compounds or compounds replacing them pH regulator pH Polishing rate [nm / hr.] Surface state designation Average particle diameter [nm] Content [mass%] designation Content [g / ℓ] designation Content [g / ℓ] Example 101 Colloidal silica - 0 H ₅ IO ₆ 10 - 0 1.8 100 ○ Example 102 Colloidal silica 75 0.04 H ₅ IO ₆ 10 - 0 1.1 196 ○ Example 103 Colloidal silica 75 0.2 H ₅ IO ₆ 10 - 0 1.3 242 ○ Example 104 Colloidal silica 75 5 H ₅ IO ₆ 10 - 0 2.3 300 ○ Example 105 Colloidal silica 75 30 H ₅ IO ₆ 10 - 0 2.5 307 ○ Example 106 Colloidal silica 75 30 H ₅ IO ₆ 5 - 0 2.8 190 ○ Example 107 Colloidal silica 75 30 H ₅ IO ₆ 20 - 0 2.0 352 ○ Example 108 Colloidal silica 75 30 H ₅ IO ₆ 50 - 0 1.3 295 ○ Example 109 Colloidal silica 75 0.6 NaIO ₄ 10 - 0 5.9 141 ○ Example 110 Colloidal silica 75 5 NaIO ₄ 10 - 0 6.7 171 ○ Example 111 Colloidal silica 75 5 NaIO ₄ 7 - 0 7.7 131 ○ Example 112 Colloidal silica 75 30 NaIO ₄ 10 H ₂ SO ₄ 2 2.4 384 ○ Example 113 Colloidal silica 16 One H ₅ IO ₆ 10 - 0 1.8 177 ○ Example 114 Colloidal silica 38 One H ₅ IO ₆ 10 - 0 1.8 219 ○ Example 115 Colloidal silica 75 One H ₅ IO ₆ 10 - 0 1.8 262 ○ Example 116 Colloidal silica 30 One H ₅ IO ₆ 10 - 0 1.8 183 ○ Comparative Example 101 Colloidal silica 75 30 - 0 - 0 9.8 18 × Comparative Example 102 Colloidal silica 75 30 H ₂ O ₂ 5 - 0 9.5 7 × Comparative Example 103 Colloidal silica 75 30 HNO ₃ 6 - 0 1.8 21 × Comparative Example 104 Colloidal silica 75 30 Al (NO ₃ ) ₃ 10 HNO ₃ 6 1.6 19 × Comparative Example 105 Colloidal silica 75 30 Fe (NO ₃ ) ₃ 10 HNO ₃ 6 1.6 19 × Comparative Example 106 Colloidal silica 75 30 0.5N HCl 0.5 - 0 1.8 13 × Comparative Example 107 Colloidal silica 75 30 NaClO 10 - 0 9.3 26 × Comparative Example 108 Colloidal silica 75 30 HclO ₄ 10 - 0 1.0 14 × Comparative Example 109 Colloidal silica 75 30 H ₂ O ₂ 5 H ₂ SO ₄ 2 2.0 11 × Comparative Example 110 Colloidal silica 75 30 Phosphonic acid 10 - 0 1.5 3 × Comparative Example 111 Colloidal silica 75 30 Malic acid 10 - 0 3.2 4 ×

 Preliminary polishing  Polishing object: (000-1) C surface polishing machine of 4H-SiC single crystal substrate of 2 inches (50mm) in diameter: FACT-200 platen rotation speed of nano factor: 120rpm Polishing time: 40 minutes Polishing pad: Nitta Haas Corporation Suba800

 Finishing polishing Polishing object: 4H-SiC single-crystal board | substrate grinder of 2 inches of diameter (50mm) after preliminary grinding: Udagawa Iron Works lens grinder (Oscar type) Supply amount of composition for polishing: 6.7 ml / min Polishing pressure: 200 g / cm ² Surface rotation speed: 130 rpm Head rotation speed: 0 rpm Polishing time: Two hours Polishing pad: Suba800 of Nitta Haas Co., Ltd.

As shown in Table 3, according to the polishing composition of Examples 101-116, starting with Comparative Example 101 which corresponds to the polishing composition of Unexamined-Japanese-Patent No. 2004-290018, compared with the polishing composition of Comparative Examples 102-111, , A high polishing rate could be obtained. Moreover, the polishing compositions of Examples 101 to 116 were also able to satisfy the surface state after polishing.

EMBODIMENT OF THE INVENTION Hereinafter, 4th Embodiment of this invention is described.

The polishing composition of the fourth embodiment is prepared by mixing a predetermined amount of an oxo compound and a colloidal silica colloidal solution and diluting with water as necessary. Therefore, the polishing composition of the fourth embodiment consists essentially of colloidal silica, oxo compound, and water as polishing particles. The polishing composition of the fourth embodiment is used for polishing a 4H-SiC single crystal substrate or a 6H-SiC single crystal substrate, more specifically, silicon carbide constituted along each of the (0001) Si plane and the (000-1) C plane. It is used to polish both front and back sides of a single crystal substrate simultaneously or sequentially. When the (0001) Si surface and the (000-1) C surface of the substrate are polished sequentially, the order of polishing the (0001) Si surface and the (000-1) C surface is not asked.

When the content of the colloidal silica in the polishing composition of the fourth embodiment is less than 0.05% by mass, more specifically, less than 0.1% by mass, more specifically, less than 1% by mass, the polishing composition has sufficient polishing ability. There is a fear that you do not have. Therefore, in order to obtain a higher polishing rate, the content of the colloidal silica in the polishing composition of the fourth embodiment is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and most preferably 1% by mass or more. On the other hand, when the content of the colloidal silica in the polishing composition of the fourth embodiment is more than 40% by mass, more specifically, more than 35% by mass, more specifically, more than 30% by mass, the polishing rate is close to saturation. It is not economical because it does not rise so much. Therefore, it is preferable that content of the colloidal silica in the polishing composition of 4th embodiment is 40 mass% or less, More preferably, it is 35 mass% or less, Most preferably, it is 30 mass% or less.

Colloidal silicas with an average primary particle diameter of less than 5 nm, more specifically colloidal silicas with an average primary particle diameter of less than 15 nm, more specifically colloidal silicas with an average primary particle diameter of less than 25 nm are (0001) Si face and (000 -1) The ability to polish the C surface is not very high. Therefore, in order to obtain a higher polishing rate, the average primary particle diameter of the colloidal silica included in the polishing composition of the fourth embodiment is preferably 5 nm or more, more preferably 15 nm or more, most preferably 25 nm or more. to be. On the other hand, in the case where the average primary particle diameter of the colloidal silica is larger than 120 nm, more specifically, larger than 100 nm, more specifically, larger than 85 nm, the polishing composition exhibits sufficient polishing capability in the fourth embodiment. It is necessary to make the content of colloidal silica in the polishing composition extremely high. Therefore, in order to reduce the cost of the polishing composition, the average primary particle diameter of the colloidal silica included in the polishing composition of the fourth embodiment is preferably 120 nm or less, more preferably 100 nm or less, most preferably 85 nm. It is as follows. In addition, the average primary particle diameter of colloidal silica is computed from the specific surface area measured by the BET method, for example.

The oxo compound contained in the polishing composition of the fourth embodiment may be any of oxo acid, peroxo acid and such salts for the purpose of improving the polishing rate, but it is preferable that the oxo compound or the peroxo acid salt is more preferable. Preferably, orthoperoxoic acid (H ₅ IO ₆ ) or sodium metaperoxonate (NaIO ₄ ). Peroxo acids and peroxoates are preferred because of their high redox potential and strong oxidizing power over oxo acids and oxoacid salts, and ortho and oxo acid and sodium metaperoxate are easier to obtain than other peroxo acids and peroxoates It is preferable because of one point.

When the content of the oxo compound in the polishing composition of the fourth embodiment is less than 0.1 g / l, more specifically, less than 1 g / l, more specifically, less than 5 g / l, the polishing rate is too high. There is a possibility that the (0001) Si surface and the (000-1) C surface cannot be polished. Therefore, in order to obtain a higher polishing rate, the content of the oxo compound in the polishing composition of the fourth embodiment is preferably 0.1 g / L or more, more preferably 1 g / L or more, most preferably 5 g / L That's it. On the other hand, when the content of the oxo compound in the polishing composition of the fourth embodiment is more than 500 g / l, more specifically, more than 250 g / l, more specifically, more than 100 g / l, There is a possibility that deterioration will be accelerated, and in addition, if the oxo compound included in the polishing composition of the fourth embodiment is an oxo acid salt or a peroxate salt, precipitation may occur in the polishing composition. Therefore, in order to avoid such inconvenience, the content of the oxo compound in the polishing composition of the fourth embodiment is preferably 500 g / l or less, more preferably 250 g / l or less, and most preferably 100 g / l or less. .

When the pH of the polishing composition of the fourth embodiment is less than 6, the polishing composition lacks the ability to polish the (0001) Si surface, and when the pH exceeds 8, the ability of the polishing composition to polish the (000-1) C surface. Lacks this. Therefore, it is essential that pH of the polishing composition of 4th embodiment is 6-8 in order to implement | achieve highly suitable grinding | polishing of both (0001) Si surface and (000-1) C surface.

According to the fourth embodiment, the following advantages can be obtained.

The polishing composition of the fourth embodiment has the ability to polish both (0001) Si and (000-1) C surfaces of a 4H-SiC single crystal substrate or a 6H-SiC single crystal substrate at a high polishing rate. This is because the oxo compound made from oxo acid, peroxo acid or such salt contained in the fourth polishing composition of the present embodiment oxidizes (0001) Si and (000-1) C surfaces in the region of pH 6-8. It seems to be because it exhibits sufficient oxidizing power.

The fourth embodiment can be changed as follows.

The abrasive grains contained in the polishing composition of the fourth embodiment may be silica other than colloidal silica such as fumed silica, or may be alumina or chromium oxide. However, when silica (especially colloidal silica) is used, since it is less likely to be damaged on the surface of the polishing object after polishing, compared to when alumina or chromium oxide is used, silica (especially colloidal silica) is preferable. .

Well-known additives, such as a pH adjuster, an antiseptic | preservative, and an antifoamer, can be added to the polishing composition of 4th Embodiment as needed.

The polishing composition of the fourth embodiment is not intended for polishing a substrate on which front and back surfaces are formed along each of the (0001) Si plane and the (000-1) C plane, but the (0001) Si plane and (000-1). It can be used for the purpose of grinding | polishing the grinding | polishing object which has the surface where C surface is mixed. It can also be used for polishing a surface of a 4H-SiC single crystal substrate or a 6H-SiC single crystal substrate other than the (0001) Si plane and (000-1) C plane. Or a polishing object composed of a cubic crystal silicon carbide single crystal such as a 3C-SiC single crystal substrate. It can also be used for polishing a polishing object made of a silicon carbide single crystal other than a silicon carbide single crystal substrate, or it can be used for polishing a polishing object other than a polishing object made of a silicon carbide single crystal. However, the polishing composition of the fourth embodiment has the ability to polish both the (0001) Si and (000-1) C surfaces of the 4H-SiC single crystal substrate or the 6H-SiC single crystal substrate at a high polishing rate. To grind both (0001) Si and (000-1) C surfaces simultaneously or sequentially, or to polish surfaces where (0001) Si and (000-1) C surfaces are mixed. More preferably used.

EMBODIMENT OF THE INVENTION Hereinafter, the Example and comparative example which concern on 4th Embodiment of this invention are demonstrated.

The colloidal silica colloidal solution, orthoperoxoic acid (oxo compound), and ammonia (pH regulator) were mixed suitably, and diluted with water as needed, and the polishing compositions of Examples 201-205 and Comparative Examples 201-205 were prepared. The details of colloidal silica, orthoperoxo acid and ammonia in each polishing composition and the pH of each polishing composition are shown in Table 6. In addition, the average primary particle diameter of the colloidal silica contained in each polishing composition is 38 nm.

Using the polishing compositions of Examples 201 to 205 and Comparative Examples 201 to 205, the (0001) Si and (000-1) C surfaces of the silicon carbide single crystal substrate were polished under the polishing conditions shown in Table 7, respectively. The polishing rate calculated by measuring the weight of the substrate before and after polishing of the (0001) Si surface and calculated from the measured value is shown in the "Polishing rate of the (0001) Si surface" column of Table 6, and polishing the (000-1) C surface. The polishing rate which measured the weight of the board | substrate before and after and computed from the measured value is shown in the "polishing rate of (000-1) C surface" column of Table 6.

(0001) Si plane and (000-1) C plane of the silicon carbide single crystal substrate after polishing under the polishing conditions shown in Table 7 using the polishing compositions of Examples 201 to 205 and Comparative Examples 201 to 205, respectively. It observed by 50 times magnification by Based on the observation result, the evaluation result about the surface defect occurrence condition by each polishing composition was evaluated in the "surface state of (0001) Si surface" column, and "surface state of (000-1) C surface" of Table 6. Column is shown. In the same column, ○ (good) indicates that the pit, the step and the face were not recognized, and × (defect) indicates that one of the pit, the step and the face was recognized.

Content of colloidal silica [mass%] Content of Ortho and Oxo Acid [g / ℓ] Ammonia Content [g / ℓ] pH Polishing rate of (0001) Si plane [nm / hr.] Surface state of (0001) Si plane Polishing rate of (000-1) C plane [nm / hr.] Surface state of (000-1) C plane Comparative Example 201 10 10 0 2.2 7.4 ○ 506 ○ Comparative Example 202 10 10 0.6 4.3 7.5 ○ 391 ○ Example 201 10 10 0.7 6.0 10.5 ○ 343 ○ Example 202 10 10 0.8 6.6 14.3 ○ 326 ○ Example 203 10 10 0.9 7.0 17.5 ○ 279 ○ Example 204 20 10 0.9 7.0 19.1 ○ 281 ○ Example 205 10 10 1.4 7.6 20.1 ○ 265 ○ Comparative Example 203 10 10 1.8 8.2 22.5 ○ 248 × Comparative Example 204 10 10 7.5 9.9 30.9 ○ 154 × Comparative Example 205 10 0 0 9.5 7.2 ○ 36 ×

Polishing object: (0001) Si surface polishing machine of 4H-SiC single crystal substrate having a diameter of 2 inches (50 mm): Supply amount of EJ-380IN polishing composition from Engis Co., Ltd., Japan: 50 ml / min Polishing pressure: 230 g / cm ² Table rotation speed: 80 rpm Head rotation speed: 30 rpm Polishing time: 4 hours Polishing pad: Suba800 of Nitta Haas Co., Ltd.

As shown in Table 6, for Examples 201 to 205, the surface states of the (0001) Si surface and the (000-1) C surface after polishing were both good, and the polishing rate of the (0001) Si surface and ( The polishing rate of the surface of 000-1) C was both high.

According to the polishing composition of the present invention, both the (0001) Si plane of the silicon carbide single crystal substrate, the (000-1) C plane of the silicon carbide single crystal substrate, and both the (0001) Si plane and the (000-1) C plane Can be polished very suitably.

Claims (11)

A polishing composition containing polishing particles and an oxo compound, and having a pH of 6 or more. The polishing composition of claim 1, wherein the oxo compound comprises oxo acid, peroxo acid or such salts. The polishing composition according to claim 1 or 2, wherein the polishing composition further contains an alkali containing a lithium compound or ammonia. The polishing composition according to claim 1 or 2, wherein the polishing composition is used for polishing a polishing object made of a silicon carbide single crystal. A polishing composition used for polishing a polishing object made of a semiconductor single crystal, the polishing composition containing an oxo compound and having a pH of 8 or less. 6. The polishing composition according to claim 5, wherein the polishing composition further contains polishing particles. The polishing composition according to claim 5 or 6, wherein the oxo compound comprises oxo acid, peroxo acid or a salt thereof. 7. A polishing composition according to claim 5 or 6, wherein the polishing object is made of silicon carbide single crystal. A polishing composition used for polishing a polishing object made of a silicon carbide single crystal, the polishing composition containing polishing particles and an oxo compound and having a pH of 6 to 8. The polishing composition of claim 1, wherein the oxo compound comprises oxo acid, peroxo acid or a salt thereof. A method for polishing a polishing object made of silicon carbide single crystal, comprising the steps of adjusting the polishing composition according to any one of claims 1, 2, 5, 6, 9 and 10 and using the adjusted polishing composition And a polishing step of polishing the polishing object.