Iodine removal method of diiodosilane

Abstract

The invention discloses a method for removing iodine from diiodosilane. The iodine removal method comprises the following steps: providing a diiodosilane crude product, wherein the diiodosilane crude product contains diiodosilane and elemental iodine; enabling the diiodosilane crude product to be in contact with copper powder, so that the iodine elementary substance and the copper powder are subjected to chemical reaction to be removed; wherein the particle size of the copper powder is 50 nm to 45 [mu] m. The invention provides a method for efficiently and simply removing the iodine impurity from the DIS crude product, the method can realize iodine removal without pre-treating or pre-purifying the DIS, and the method provided by the invention does not cause degradation of the DIS, does not bring in new impurities, does not influence the stability of the treated DIS, and is very beneficial to the preparation of high-purity DIS and the application of the high-purity DIS in the field of semiconductors.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of silicon-based precursor materials, and particularly to a method for removing iodine from disilane diiodide. Background Art

[0002] Disilane diiodide (DIS) is a new type of silicon-based precursor material, which is suitable for forming silicon-containing films, including silicon nitride films, by atomic layer deposition (ALD) at a relatively low temperature, and can be used to produce high-end semiconductor chips. DIS can be prepared through various routes. The most common preparation method is, for example, through the iodination reaction of elemental iodine and phenylsilane. The DIS product obtained after the reaction always contains a certain amount of iodine, resulting in DIS, which is essentially colorless, showing gray, or pink, or red colors, and the chromaticity increases with the increase of iodine content. At the same time, DIS is sensitive to oxygen. High-purity colorless DIS will be quickly oxidized to form elemental iodine and become a colored material if exposed to air. Regardless of its source, iodine is an impurity in high-purity DIS, which will affect the application of DIS in semiconductor coating, for example, semiconductor coating generally requires that the impurity content is not higher than 1 ppm.

[0003] Once DIS is contaminated with iodine, it is very difficult to completely remove iodine impurities by distillation. Iodine is an effective dye, and the human eye has a high sensitivity to the color of iodine, which can accurately qualitatively determine the level of iodine content. Therefore, an effective method for removing iodine is needed to reduce the iodine content in DIS to at least the level where the color cannot be observed by the naked eye.

[0004] Moreover, DIS has high reactivity, and both Si-H and Si-I bonds in the molecule are very easy to participate in chemical reactions. Its high reactivity also results in DIS being very sensitive to certain reagents. These reagents can cause DIS to degrade, reduce the yield or introduce new impurities.

[0005] In addition, some existing technologies involve removing elemental iodine from DIS. For example, some patents disclose a method for removing iodine from DIS using copper powder. This method uses copper powder with a relatively large particle size and requires that the DIS to be treated must be purified by distillation. This requirement for pre-purification increases the complexity and cost of the process and makes it difficult to apply in mass production.

[0006] Therefore, how to simply and efficiently remove elemental iodine and avoid the decomposition of DIS is very important for the wide application of DIS in the semiconductor field. Summary of the Invention

[0007] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a method for removing iodine from disilane diiodide.

[0008] To achieve the foregoing invention purpose, the technical solutions adopted by the present invention include:

[0009] The present invention provides a method for removing iodine from disilane, which includes:

[0010] Providing a crude disilane product, which contains disilane and iodine;

[0011] Bringing the crude disilane product into contact with copper powder so that the iodine reacts chemically with the copper powder and is removed;

[0012] Wherein, the particle size of the copper powder is 50 nm - 45 μm.

[0013] Based on the above technical solution, compared with the prior art, the beneficial effects of the present invention at least include:

[0014] The present invention provides a method for efficiently and simply removing iodine impurities from crude DIS. This method can achieve iodine removal without requiring pretreatment or pre-purification of DIS. Moreover, the provided method does not cause degradation of DIS, does not introduce new impurities, does not affect the stability of DIS after treatment, and is very beneficial to the preparation of high-purity DIS and its application in the semiconductor field.

[0015] The above description is only an overview of the technical solution of the present invention. In order to enable those skilled in the art to more clearly understand the technical means of the present application and implement it in accordance with the content of the specification, the following is described with preferred embodiments of the present invention as follows. Detailed Embodiments

[0016] In view of the deficiencies in the prior art, the inventors of this case have proposed the technical solution of the present invention through long-term research and a large number of practices. The following will further explain the technical solution, its implementation process and principle, etc.

[0017] Many specific details are set forth in the following description in order to provide a thorough understanding of the present invention. However, the present invention may be practiced in other ways than those described herein. Therefore, the scope of protection of the present invention is not limited by the specific embodiments disclosed below.

[0018] An embodiment of the present invention provides a method for removing iodine from disilane, which includes the following steps:

[0019] Providing a crude disilane product, which contains disilane and iodine;

[0020] Bringing the crude disilane product into contact with copper powder so that the iodine reacts chemically with the copper powder and is removed;

[0021] Wherein, the particle size of the copper powder is 50 nm - 45 μm.

[0022] In some embodiments, the crude diiodosilane is directly contacted with the copper powder without pretreatment.

[0023] In the present invention, the raw materials for synthesizing DIS can be, for example, phenylsilane and iodine. During the synthesis process, since iodine is not completely reacted or diiodosilane reacts with oxygen during the reaction to regenerate iodine, the crude DIS product appears red or dark red, and the impurity iodine cannot be removed by normal distillation or rectification. At the same time, considering that DIS has high reactivity, during the iodine removal process, the reaction or degradation of DIS should be avoided, which increases the difficulty of purification or reduces the purity of the product. Therefore, on the premise of not affecting the purity of the crude diiodosilane and the difficulty of purification, the present invention uses copper powder within a selected particle size range to treat the crude diiodosilane. Within seconds after the addition of the copper powder, the crude product changes from the initial iodine-containing red color to iodine-free colorless, and the color does not change after long-term storage. After testing the composition of the crude product, the product purity is hardly affected.

[0024] The crude DIS used in the present invention does not need to be pre-purified and can be a direct synthesis mixture or other forms of iodine-contaminated DIS, including DIS exposed to air. The copper powder used has a particle size smaller than 45 μm, that is, 300 mesh. Copper powder of such a size has a large enough specific surface area to effectively remove iodine impurities in the crude DIS.

[0025] In some prior arts, the treatment steps clearly require pre-purification. The purpose of pre-purification is to "remove by-products", and the by-products include benzene and HI. This also shows that the copper powder with a particle size of 0.6 - 6 mm used by it has lower efficiency in iodine removal than copper powder with smaller particles. Because the iodine removal efficiency of 0.6 - 6 mm copper powder is low, it is necessary to pre-purify the reaction product first to remove part of the iodine through pre-purification so as to ensure the iodine removal effect of 0.6 - 6 mm copper powder. Although the prior art points out that the smaller the particle size of the copper powder, the higher the treatment efficiency, on the one hand, the treatment efficiency it indicates refers to the rate of chemical reaction, that is, it can achieve the effect of removing iodine in the pre-treated crude product in a shorter time, rather than the progress of the chemical reaction. That is, it does not indicate that reducing the particle size of the copper powder can bring the technical effect of effectively removing iodine without pretreatment; on the other hand, based on the control experiments carried out in the embodiments of the present invention, it can be clearly seen that using millimeter-sized copper powder (or called copper particles), no matter how the treatment time is extended, it is impossible to achieve iodine removal without pretreatment, which also confirms that the technical path inspired by the above prior art necessarily includes a pretreatment step (regardless of the particle size of the copper powder).

[0026] Therefore, the key technical means of the present invention, which is also the main technical innovation point of the present invention, lies in the discovery that copper powder within a selected particle size range can directly process the crude DIS without pretreatment to obtain a purified product. This is not guided by the prior art.

[0027] Regarding the specific reactant composition, in some embodiments, the crude disilane also includes an organic solvent.

[0028] For the composition of the above reactants, in some embodiments, the iodine removal method may further include:

[0029] Rectifying the mixture obtained after the chemical reaction between the iodine and the copper powder to obtain pure disilane.

[0030] More specifically, in some embodiments, the mass fraction of disilane in the crude disilane is 1-99%;

[0031] In some embodiments, the mass fraction of elemental iodine in the crude disilane is 0.01-10%.

[0032] In some embodiments, the organic solvent includes any one or a combination of two or more of hydrocarbon solvents.

[0033] In some embodiments, the temperature of the chemical reaction between the iodine and the copper powder is 10-40°C, and the time is within 24 hours. In some embodiments, it is preferably within 2 hours, and in some embodiments, it is further preferably within 30 minutes.

[0034] The technical solution provided by the present invention can usually achieve the fading of the color of the crude product within 1 minute. However, in specific implementation, the contact time between the copper powder and the crude product is not limited to within 1 minute. In order to prevent the crude product from further oxidizing, after the reaction is relatively complete, the copper powder and the crude product can be kept in contact until the mixture is distilled. This can also be regarded as a method for preserving the mixture after iodine removal treatment.

[0035] Regarding the source of the crude disilane, in some embodiments, the preparation method of the crude disilane includes:

[0036] Reacting an aromatic silane with elemental iodine to generate disilane, thereby forming the crude disilane.

[0037] Based on the above preparation method, in some embodiments, the crude diiodosilane formed also contains moniodosilane and triiodosilane. Specifically, for example, in the crude diiodosilane synthesized, the main component other than DIS is the solvent, and it also contains a small amount of other iodosilanes, such as about 2% triiodosilane and about 1% moniodosilane.

[0038] As an effect of the above technical solution, in some embodiments, after being treated by the iodine removal method, the iodine content in the obtained diiodosilane mixture and the purified product after distillation are both lower than the level observable by the naked eye, and it can be considered a colorless and transparent liquid.

[0039] The technical solution of the present invention will be further described in detail below through several examples. However, the selected examples are only used to illustrate the present invention and do not limit the scope of the present invention.

[0040] Example 1

[0041] This example demonstrates the iodine removal process of diiodosilane as follows:

[0042] Add the following copper powder with an average particle size ≤ 45μm to a 20 - milliliter glass bottle respectively, and inject 1.5 milliliters of the crude DIS product into it. The crude product contains 8% DIS and is red in color. Observe the color change of the crude product within several seconds to dozens of seconds, within 2 hours, and within 1 day, as well as the change in the DIS content of the sample with iodine removal effect after 1 day.

[0043] Example 2

[0044] This example demonstrates an iodine removal process of diiodosilane, which is generally the same as Example 1, except that:

[0045] Change the particle size of the copper powder, and select copper powder with a particle size of 50nm. The composition, ratio, and treatment conditions of the remaining raw materials remain unchanged.

[0046] Comparative Example 1

[0047] This comparative example demonstrates an iodine removal process of diiodosilane, which is generally the same as Example 1, except that:

[0048] Change the particle size of the copper powder, and select copper powder with a particle size of 2mm. The composition, ratio, and treatment conditions of the remaining raw materials remain unchanged.

[0049] Comparative Example 2

[0050] This comparative example demonstrates an iodine removal process of diiodosilane, which is generally the same as Example 1, except that:

[0051] Replace the copper powder with other metal powders of different particle sizes and different materials, while keeping the composition, ratio, and treatment conditions of the other raw materials unchanged.

[0052] The iodine removal effects of the above-mentioned examples and comparative examples were tested. The test method used was as follows: Add 0.075 grams of metal powder to a 20-milliliter glass bottle, seal the glass bottle, and then inject 1.5 milliliters of the red DIS synthetic crude product containing iodine into the sealed glass bottle using a syringe. Observe the color change of the crude product within a few seconds, within 2 hours, and within 1 day. The disappearance of the red color indicates that the impurity iodine has been completely removed. For the samples with iodine removal effect, after 1-day storage, GC analysis was performed to compare the change in DIS content. If the DIS content decreased, it indicated that DIS had degraded. The metal powders, experimental phenomena, and test data used in the above examples and comparative examples are shown in Table 1 below.

[0053] Table 1

[0054]

[0055] The examples show that using copper powders with particle sizes ≤45μm and 50 nanometers for treatment can not only completely and rapidly remove the impurity iodine in the DIS synthetic crude product, but also does not cause the degradation of DIS. Using large-particle 2-millimeter copper powder results in a significant decrease in iodine removal efficiency. Among the other 9 metal powders, some cannot effectively remove iodine in the DIS crude product, or cause the degradation of DIS (such as tin powder). Moreover, when using copper powders with particle sizes ≤45μm and 50 nanometers, the iodine removal time is <1 minute.

[0056] In addition, other examples of the present invention also conducted multiple tests using copper powders provided by different manufacturers between 50nm - 45μm, and the same regular patterns as the above phenomena were observed.

[0057] Based on the above detection results, it can be clearly seen that the examples of the present invention provide a method for efficiently and simply removing iodine impurities from the DIS crude product. This method can achieve iodine removal without requiring pretreatment or pre-purification of DIS. Moreover, the provided method does not cause the degradation of DIS, does not introduce new impurities, and does not affect the stability of the treated DIS, which is very beneficial to the preparation of high-purity DIS and its application in the semiconductor field.

[0058] It should be understood that the above examples are only used to illustrate the technical concept and characteristics of the present invention, and their purpose is to enable those familiar with this technology to understand the content of the present invention and implement it accordingly. It should not be used to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for removing iodine from diiodosilane, It is characterized in that include: Providing a crude diiodosilane product, wherein the crude diiodosilane product contains diiodosilane and iodine; The crude diiodosilane is brought into contact with copper powder so that the iodine element reacts chemically with the copper powder and is removed; Wherein, the particle size of the copper powder is 50nm-45μm.

2. The iodine removal method according to claim 1, It is characterized in that The crude diiodosilane is directly contacted with the copper powder without being pretreated.

3. The iodine removal method according to claim 1, It is characterized in that The crude diiodosilane also includes an organic solvent.

4. The iodine removal method according to claim 3, It is characterized in that Also includes: The mixture obtained after the iodine element and the copper powder undergo a chemical reaction is distilled to obtain pure diiodosilane.

5. The iodine removal method according to claim 3, It is characterized in that The mass fraction of diiodosilane in the crude diiodosilane is 1-99%; And / or, the mass fraction of elemental iodine in the crude diiodosilane is 0.01-10%.

6. The iodine removal method according to claim 3, It is characterized in that The organic solvent includes any one or a combination of two or more hydrocarbon solvents.

7. The iodine removal method according to claim 1, It is characterized in that The temperature for the chemical reaction between the iodine element and the copper powder is 10-40°C, and the time is within 24 hours, preferably within 2 hours, and more preferably within 30 minutes.

8. The iodine removal method according to claim 1, It is characterized in that The preparation method of the crude diiodosilane comprises: The aromatic silane is subjected to an iodination reaction with elemental iodine to generate diiodosilane, thereby forming the crude diiodosilane.

9. The iodine removal method according to claim 8, It is characterized in that The crude diiodosilane formed also contains monoiodosilane and triiodosilane.

10. The iodine removal method according to claim 1, It is characterized in that After being treated by the iodine removal method, the obtained diiodosilane mixture is a colorless transparent liquid.

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