JP4193017B2 - Method for forming boron doped silicon film - Google Patents

Description

【０００９】
の如き水素化多環状ケイ素化合物を挙げることができる。これらは２種以上混合して使用することができる。
これらのうち、合成および精製の容易性、安定性などの点でＳｉ_xＨ_y（ｙ＝２ｘ）が好ましく、とくに、シクロペンタシラン、シリルシクロペンタシラン、シクロヘキサシラン、シクロヘプタシランなどが好ましい。
上記のシラン化合物は単独で、または２種以上一緒に用いることができる。
本発明において用いられるボラン・スルフィド錯体は、下記式（３）
ＢＨ₃・ＳＲ¹Ｒ² ．．．（３）
ここで、Ｒ¹およびＲ²は互いに独立に水素原子または一価の有機基である、
で表される化合物である。
【００１０】
一価の有機基としては、例えばメチル基、エチル基、プロピル基、ブチル基、ペンチル基およびフェニル基等を好ましいものとして挙げることができる。
ＢＨ₃は室温下ではガス状であるため密閉の圧力容器などに入れる必要があり取り扱いに難があるが、ＢＨ₃・ＳＲ¹Ｒ²のようにイオウ原子で配位させることにより液体状、または固体状になるため取り扱いが極めて容易になる。しかも、ボラン・スルフィド錯体は一定以上の温度でＢＨ₃分子とＳＲ¹Ｒ²分子に解離するためＢＨ₃分子の前駆体として使用できる。またボラン・スルフィド錯体は不活性有機媒体に可溶性であるため取り扱いが極めて容易である。
【００１１】
ボラン・スルフィド錯体の具体例としては、ボラン・ジメチルスルフィド錯体、ボラン・ジエチルスルフィド錯体、ボラン・ジプロピルスルフィド錯体、ボラン・ジブチルスルフィド錯体、ボラン・ジペンチルスルフィド錯体、ボラン・ジフェニルスルフィド錯体、ボラン・メチルエチルスルフィド錯体、ボラン・メチルフェニルスルフィド錯体などを挙げることができ、好ましくはボラン・ジメチルスルフィド錯体、ボラン・ジエチルスルフィド錯体等を挙げることができる。
【００１２】
本発明において、上記シリコン化合物は、ボラン・スルフィド錯体と一緒に、不活性有機媒体蒸気の共存下で熱分解に付される。不活性有機媒体としては、例えば炭化水素およびエーテル類が好ましく用いられる。炭化水素としては、例えばベンゼン、トルエン、キシレンの如き芳香族炭化水素、ヘキサン、ヘプタン、デカンの如き脂肪族炭化水素、シクロペンタン、シクロヘキサン、デカリンの如き脂環族炭化水素を挙げることができる。また、エーテルとしては、例えばジイソプロピルエーテル、イソプロピルブチルエーテルの如き線状エーテルおよびテトラヒドロピラン、テトラヒドロフラン、ジオキサンの如き環状エーテルを挙げることができる。
【００１３】
本発明において、熱分解は大気圧下、減圧下および加圧下のいずれにおいて行うこともできるが、大気圧下で行うのが好ましい。熱分解は、好ましくは２００℃〜６００℃の温度、より好ましくは３００℃〜５００℃の温度で実施される。シリコン化合物およびボラン・スルフィド錯体は熱分解を受け基体上に堆積してホウ素でドープされたシリコン膜を与える。
【００１４】
本発明方法は次のようにして実施することができる。
（１）前記式（１）で表される化合物および前記式（２）で表される化合物よりなる群から選ばれる少なくとも１種のシリコン化合物、ボラン・スルフィド錯体および不活性有機媒体の混合物中に、不活性ガスを通気して不活性ガス担体中に上記シリコン化合物、ボラン・スルフィド錯体および不活性有機媒体蒸気を含有する気体混合物を生成せしめ、次いで（２）該気体混合物を加熱してその中に含有されるシリコン化合物を熱分解せしめて基体上にシリコンを堆積せしめることを特徴とする、基体上にシリコン膜を形成する方法である。
【００１５】
上記工程（１）において、シリコン化合物、ボラン・スルフィド錯体および不活性有機媒体の混合物は溶液の形態にあるのが好ましい。シリコン化合物は好ましくは０.０１〜５０重量％の濃度に調整される。また、ボラン・スルフィド錯体は好ましくは０.０００１〜１重量％の濃度に調整される。
ここでいう不活性ガスとは、原料のケイ素化合物、およびボラン・スルフィド錯体に対して反応性を実質上持たないものをいい、たとえば水素、ヘリウム、アルゴン、窒素およびこれらの混合ガスが挙げられる。
混合物中への不活性ガスの通気は、シリコン化合物および不活性有機媒体の蒸気を含有する気体混合物を容易に生成する。通気の際、過度に加熱することは望ましくない。通気の際の混合物の温度は好ましくは１０〜５０℃に維持するのが望ましい。通気中に、必要に応じ、混合物中にシリコン化合物、ボラン・スルフィド錯体および／または不活性有機媒体を添加して補充することができる。
【００１６】
工程（１）で得られた気体混合物は次いで工程（２）の実施のために導かれ、工程（２）において加熱されてシリコン化合物およびボラン・スルフィド錯体が分解される。加熱温度は上記のとおり２００〜６００℃が好ましい。シリコン化合物の分解により生成したシリコンおよびボラン・スルフィド錯体の分解により生成したホウ素は基体上に堆積されホウ素でドープされたシリコン膜を形成する。工程（２）の実施のため、気体混合物は連続的にあるいは間歇的に導入することができる。導入する時間は、気体混合物中のシリコン化合物およびボラン・スルフィド錯体の濃度、基体の面積あるいは形成しようとするホウ素でドープされたシリコン膜の厚さ等により適宜変えることができる。本発明によれば、基体上にホウ素でドープされたシリコン膜を均一な膜厚で容易に形成できる。形成されたホウ素でドープされたシリコン膜はホウ素でドープされたアモルファスシリコンからなる。このホウ素でドープされたアモルファスシリコン膜は窒素雰囲気下で高温度例えば７００〜９００℃に加熱されるかあるいはレーザー光照射を受けることによりホウ素でドープされた多結晶シリコン膜に変換できる。
【００１７】
【実施例】
以下に、本発明を実施例により詳細に説明するが、本発明はこれら実施例に限定されるものではない。
【００１８】
合成例１
（１）温度計、冷却コンデンサー、滴下ロートおよび攪拌装置を取り付けた内容量が３Ｌの４つ口フラスコ内をアルゴンガスで置換した後、乾燥したテトラヒドロフラン１Ｌとリチウム金属１８．３ｇを仕込み、アルゴンガスでバブリングした。この懸濁液を０℃で攪拌しながらジフェニルジクロロシラン３３３ｇを滴下ロートより添加し、滴下終了後、室温下でリチウム金属が完全に消失するまでさらに１２時間攪拌を続けた。反応混合物を５Ｌの氷水に注ぎ、反応生成物を沈殿させた。この沈殿物を濾別し、水で良く洗浄した後シクロヘキサンで洗浄し、真空乾燥することにより白色固体１４０ｇを得た。この白色固体はＩＲ、¹Ｈ−ＮＭＲ、²⁹Ｓｉ−ＮＭＲの各スペクトルにより、２成分から成る混合物であることが示された。このケイ素化合物の混合物を高速液体クロマトグラフィーにより分離したところ、主生成物と副生成物の比は８：１であることが判った。さらに、それぞれのＩＲ、¹Ｈ−ＮＭＲ、²⁹Ｓｉ−ＮＭＲ、ＴＯＦ−ＭＳの各スペクトルを測定したところ、主生成物はデカフェニルシクロペンタシランで、副生成物はドデカフェニルシクロヘキサシランであることが確認できた。
（２）上記ケイ素化合物の混合物５０ｇと乾燥したトルエン５００ｍｌを１Ｌのフラスコに仕込み、塩化アルミニウム２ｇを加え、室温下で塩化水素を導入し、アルゴン雰囲気下で５時間反応を続けた。ここで別途に、水素化リチウムアルミニウム２０ｇとジエチルエーテル２００ｍｌを２Ｌのフラスコに仕込み、アルゴン雰囲気下、０℃で攪拌しながら上記反応混合物を加え、同温にて１時間撹拌後さらに室温で１２時間撹拌を続けた。反応混合物よりアルミ化合物を除去し溶媒を留去したところ粘稠な油状物が５ｇ得られた。このものはＩＲ、¹Ｈ−ＮＭＲ、²⁹Ｓｉ−ＮＭＲ、ＧＣ−ＭＳの各スペクトルより、シクロペンタシランおよびシリルシクロペンタシランを、この順で８：１の比で含む混合物であることが判った。シクロペンタシランおよびシリルシクロペンタシランはそれぞれ下記式（４）および（５）で表される。
【００１９】
【化２】

【００２０】
参考例１
アルゴン雰囲気下、合成例１で得られたケイ素化合物の混合物５ｇをトルエン４５ｇに溶解して溶液を調製した。この溶液を図１の受器１にセットし、さらに加熱管２の内部に石英ガラス基板をセットした。加熱管２を４００℃に加熱しながらガス導入口３より窒素ガスを１リットル／分の速度で１０分間流したところ、石英基板上に金属光沢を有する薄膜が形成されていた。このときトルエンの蒸気圧は３０ｍｍＨｇであった。この金属光沢を有する薄膜をＥＳＣＡスペクトルを測定したところ、９９ｅＶにＳｉに帰属されるピークのみが観察され炭素など溶剤起因の他の元素は全く検出されなかった。このシリコン膜の膜厚は８０ｎｍであった。また、このＳｉ膜のラマンスペクトル測定したところ、アモルファスシリコンであることが判った。このアモルファスシリコンの比抵抗は５×１０⁹Ωｃｍであった。
【００２１】
実施例１
合成例１で得られたケイ素化合物の混合物５ｇをトルエン４５ｇに溶解した溶液にボラン・ジメチルスルフィド（ＢＨ₃・ＳＭｅ₂）錯体のトルエン溶液（２モル／Ｌ濃度）を１０ｍｌ添加し調製した。この溶液を図１の受器１にセットし、さらに加熱管２の内部に石英ガラス基板をセットした。加熱管２を４００℃に加熱しながらガス導入口３より窒素ガスを１リットル／分の速度で２０分間流したところ、石英基板上に金属光沢を有する薄膜が形成されていた。このときトルエンの蒸気圧は３０ｍｍＨｇであった。この金属光沢を有する薄膜のＥＳＣＡスペクトルを測定したところ、９９ｅＶにシリコン原子に帰属されるピークとホウ素原子のみが観察され、シリコン原子とホウ素原子の比は９：１であった。このときのＥＳＣＡスペクトルを図２に示す。またこの薄膜には炭素、イオウなど溶剤起因の他の元素は全く検出されす、ホウ素含有シリコン膜であることが分かった。このホウ素含有シリコン膜の膜厚は１２０ｎｍであった。また、この膜はラマンスペクトルの解析からアモルファス状であることが判った。このときのラマンスペクトルを図３に示す。また、このホウ素含有のアモルファスシリコンの比抵抗は３×１０⁴Ωｃｍであった。
【００２２】
実施例２
実施例１で得られたホウ素含有のアモルファスシリコン膜を形成した基板に窒素雰囲気下、ＸｅＣｌエキシマレーザー（３０８ｎｍ）を照射した。レーザー照射後の膜のラマンスペクトルを測定したところ、多結晶シリコンに由来するピークが観察され、その結晶化率は６５％と計算された。このときのラマンスペクトルを図４に示す。
【００２３】
実施例３
実施例１で得られたホウ素含有のアモルファスシリコン膜を形成した基板について、窒素雰囲気下、８００℃で３０分間熱処理を行なった。熱処理後の膜のラマンスペクトルを測定したところ、多結晶シリコンに由来するピークが観察され、その結晶化率は５５％と計算された。
【００２４】
実施例４
実施例１において、実施例１で用いた石英基板に替えてポリイミドフィルム基板をセットし、基板の温度を３００℃に替え、他は実施例１と同様にして実施したところ、ポリイミド基板上にホウ素含有のアモルファスシリコン膜を形成することができた。
この膜中のシリコン原子とホウ素原子の比は９：１であった。
【００２５】
比較例１
実施例１で使用したケイ素化合物の替わりに、モノシランガスと、水素ガスで希釈されたボランガスの混合ガスを実施例１と同様に４００℃にセットした装置で１リットル／分の流速で３０分間流した。石英基板には何も堆積しなかった。
【００２６】
【発明の効果】
本発明によれば、シリコン膜の形成とドーパントのドーピングとを２段に分けて行うことなく、簡単な操作や装置で、基体上にホウ素でドープされたシリコン膜を、一段で、効率的に例えば高い歩留りや大きい形成速度で形成することができる。
【図面の簡単な説明】
【図１】参考例１および本発明方法を実施するために実施例１で用いられた装置の概略説明図である。
【図２】実施例１で得られたホウ素含有シリコン膜のＥＳＣＡスペクトル図である。
【図３】実施例１で得られたホウ素含有シリコン膜のラマンスペクトル図である。
【図４】実施例２で得られたホウ素含有シリコン膜のラマンスペクトル図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of forming a boron-doped silicon film on a substrate. More specifically, the present invention relates to a method for forming a silicon film doped with boron, which can efficiently form a silicon film doped with boron on a substrate with a simple operation or apparatus.
[0002]
[Prior art]
Conventionally, as a method for forming an amorphous silicon film or a polysilicon film used for manufacturing a solar cell, a thermal CVD (Chemical Vapor Deposition) method using monosilane gas or disilane gas, plasma CVD, photo-CVD, or the like is used. Generally, thermal CVD (see J. Vac. Sci. Technology., Vol. 14, page 1082 (1977)) is used to form a polysilicon film, and plasma CVD (Solid StateCom.,) Is used to form an amorphous silicon film. 17 (page 1193 (1975)) is widely used.
However, in the formation of silicon films by these CVD methods, since silicon particles are generated in the gas phase because a gas phase reaction is used, the production yield is low due to contamination of the apparatus and the generation of foreign materials, and the raw material is gaseous. It is difficult to obtain a uniform film thickness on a substrate with an uneven surface, the productivity is low due to the slow film formation speed, and the plasma CVD method requires complicated and expensive high-frequency generators and vacuum devices. There was a problem such as that, and further improvement was awaited.
[0003]
In addition, in terms of materials, gaseous silicon hydride having high toxicity and reactivity is used, so that not only handling is difficult, but since it is gaseous, a sealed vacuum device is required. In general, these devices are large-scale and are not only expensive, but also consume a lot of energy in the vacuum system and plasma system, leading to high product costs.
Further, when the silicon film is used for a solar cell, it is usually necessary to dope with a Group 3 element or a Group 5 element in the periodic table and use it as a p-type or n-type semiconductor. Conventionally, these dopings have been performed by thermal diffusion or ion implantation after forming a silicon film, so it is necessary to carry out in a vacuum, and the process control is complicated. In particular, it is uniformly doped on a large substrate. It was difficult to form a silicon film.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide a method of forming a boron-doped silicon film on a substrate.
Another object of the present invention is to efficiently form a silicon film doped with boron on a substrate in a single step with a simple operation and apparatus, without forming the silicon film and doping in two steps. For example, it is an object of the present invention to provide a method for forming a boron-doped silicon film that can be formed at a high yield and a high formation rate.
Still another object of the present invention is to provide a method for forming a silicon film doped with boron using a silicon compound that is a stable compound and a borane / sulfide complex, unlike a gaseous silicon hydride that is highly toxic and reactive. It is to provide.
Still other objects and advantages of the present invention will become apparent from the following description.
[0005]
[Means for Solving the Problems]
According to the present invention, the above objects and advantages of the present invention are as follows.
Si _x H _y . . . (1)
Here, x is a number from 3 to 12, and y is a number from 2x-2 to 2x + 2, and the following formula (2)
Si _n H _n . . . (2)
Here, n is a number from 6 to 12,
At least one silicon compound selected from the group consisting of the compounds represented by the formula (I) and borane / sulfide complex, which is thermally decomposed in the presence of an inert organic medium vapor, doped with boron on the substrate This is achieved by a method of forming a silicon film.
[0006]
The silicon compound used in the present invention has the following formula (1):
Si _x H _y . . . (1)
Here, x is a number from 3 to 12, and y is a number from 2x-2 to 2x + 2, and the following formula (2)
Si _n H _n . . . (2)
Here, n is a number from 6 to 12,
It is at least 1 sort (s) chosen from the group which consists of a compound represented by these.
[0007]
Examples of the compound represented by the formula (1) include hydrogenated cyclic silane compounds such as cyclotrisilane, cyclotetrasilane, cyclopentasilane, silylcyclopentasilane, cyclohexasilane, cycloheptasilane, and cyclooctasilane; Chain silane compounds such as n-pentasilane, i-pentasilane, neo-pentasilane, n-hexasilane, n-heptasilane, n-octasilane, n-nonasilane; 1,1′-bicyclobutasilane, 1,1′-bicyclopenta Silane, 1,1′-bicyclohexasilane, 1,1′-bicycloheptasilane, 1,1′-cyclobutasilylcyclopentasilane, 1,1′-cyclobutasilylcyclohexasilane, 1,1′-cyclo Butasilylcycloheptasilane, 1,1′-cyclopentasilylcyclohexasilane, 1,1′-si Lopentasilylcycloheptasilane, 1,1'-cyclohexasilylcycloheptasilane, spiro [2.2] pentasilane, spiro [3.3] heptatasilane, spiro [4,4] nonasilane, spiro [4.5] decasilane And spiro [4.6] undecasilane, spiro [5.5] undecasilane, spiro [5.6] undecasilane, and spiro [6.6] tridecasilane.
Examples of the compound represented by the above formula (2) include:
[Chemical 1]

[0009]
Examples thereof include hydrogenated polycyclic silicon compounds. These can be used in combination of two or more.
Of these, Si _x H _y (y = 2x) is preferred from the viewpoint of easiness of synthesis and purification, stability, etc., and cyclopentasilane, silylcyclopentasilane, cyclohexasilane, cycloheptasilane, etc. are particularly preferred. .
The above silane compounds can be used alone or in combination of two or more.
The borane sulfide complex used in the present invention has the following formula (3):
BH ₃ · SR ¹ R ² . . . (3)
Here, R ¹ and R ² are each independently a hydrogen atom or a monovalent organic group.
It is a compound represented by these.
[0010]
Preferred examples of the monovalent organic group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a phenyl group.
Since BH ₃ is gaseous at room temperature, it needs to be placed in a sealed pressure vessel and is difficult to handle. However, it is liquid by coordinating with sulfur atoms like BH ₃ · SR ¹ R ² , or Since it becomes solid, handling becomes extremely easy. Moreover, since the borane / sulfide complex dissociates into BH ₃ molecules and SR ¹ R ² molecules at a certain temperature or higher, it can be used as a precursor of BH ₃ molecules. Borane sulfide complexes are very easy to handle because they are soluble in inert organic media.
[0011]
Specific examples of borane / sulfide complexes include borane / dimethyl sulfide complex, borane / diethyl sulfide complex, borane / dipropyl sulfide complex, borane / dibutyl sulfide complex, borane / dipentyl sulfide complex, borane / diphenyl sulfide complex, borane / methyl. An ethyl sulfide complex, a borane / methyl phenyl sulfide complex and the like can be mentioned, and a borane / dimethyl sulfide complex, a borane / diethyl sulfide complex and the like can be mentioned preferably.
[0012]
In the present invention, the silicon compound is subjected to thermal decomposition in the presence of an inert organic medium vapor together with a borane sulfide complex. As the inert organic medium, for example, hydrocarbons and ethers are preferably used. Examples of the hydrocarbon include aromatic hydrocarbons such as benzene, toluene and xylene, aliphatic hydrocarbons such as hexane, heptane and decane, and alicyclic hydrocarbons such as cyclopentane, cyclohexane and decalin. Examples of the ether include linear ethers such as diisopropyl ether and isopropyl butyl ether, and cyclic ethers such as tetrahydropyran, tetrahydrofuran and dioxane.
[0013]
In the present invention, the thermal decomposition can be performed under atmospheric pressure, reduced pressure, or increased pressure, but is preferably performed under atmospheric pressure. Pyrolysis is preferably performed at a temperature of 200 ° C to 600 ° C, more preferably at a temperature of 300 ° C to 500 ° C. The silicon compound and borane sulfide complex undergo thermal decomposition and are deposited on the substrate to provide a silicon film doped with boron.
[0014]
The method of the present invention can be carried out as follows.
(1) In a mixture of at least one silicon compound selected from the group consisting of the compound represented by the formula (1) and the compound represented by the formula (2), a borane sulfide complex and an inert organic medium. A gas mixture containing the silicon compound, borane / sulfide complex and inert organic medium vapor in an inert gas carrier by bubbling an inert gas, and then (2) heating the gas mixture therein. A method of forming a silicon film on a substrate, wherein the silicon compound contained in the substrate is thermally decomposed to deposit silicon on the substrate.
[0015]
In the step (1), the mixture of the silicon compound, borane sulfide complex and inert organic medium is preferably in the form of a solution. The silicon compound is preferably adjusted to a concentration of 0.01 to 50% by weight. The borane / sulfide complex is preferably adjusted to a concentration of 0.0001 to 1% by weight.
The inert gas here refers to a material that has substantially no reactivity with the raw material silicon compound and borane / sulfide complex, and examples thereof include hydrogen, helium, argon, nitrogen, and a mixed gas thereof.
Inert gas venting into the mixture readily produces a gaseous mixture containing silicon compound and an inert organic medium vapor. Excessive heating during venting is undesirable. The temperature of the mixture during aeration is preferably maintained at 10-50 ° C. During aeration, if necessary, the mixture can be supplemented with silicon compounds, borane sulfide complexes and / or inert organic media.
[0016]
The gas mixture obtained in step (1) is then led to perform step (2) and heated in step (2) to decompose the silicon compound and borane sulfide complex. As described above, the heating temperature is preferably 200 to 600 ° C. Silicon produced by the decomposition of the silicon compound and boron produced by the decomposition of the borane sulfide complex are deposited on the substrate to form a silicon film doped with boron. For the implementation of step (2), the gas mixture can be introduced continuously or intermittently. The introduction time can be appropriately changed depending on the concentration of the silicon compound and borane / sulfide complex in the gas mixture, the area of the substrate, or the thickness of the silicon film doped with boron to be formed. According to the present invention, a silicon film doped with boron can be easily formed on a substrate with a uniform film thickness. The formed boron doped silicon film is made of amorphous silicon doped with boron. The amorphous silicon film doped with boron can be converted into a polycrystalline silicon film doped with boron by heating to a high temperature, for example, 700 to 900 ° C. in a nitrogen atmosphere, or by receiving laser light irradiation.
[0017]
【Example】
EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.
[0018]
Synthesis example 1
(1) After replacing the inside of a 3 L four-necked flask equipped with a thermometer, a cooling condenser, a dropping funnel and a stirrer with argon gas, 1 L of dried tetrahydrofuran and 18.3 g of lithium metal were charged, and argon gas was charged. Bubbling. While this suspension was stirred at 0 ° C., 333 g of diphenyldichlorosilane was added from a dropping funnel, and after completion of the dropping, stirring was further continued for 12 hours until lithium metal disappeared completely at room temperature. The reaction mixture was poured into 5 L of ice water to precipitate the reaction product. The precipitate was separated by filtration, washed well with water, then washed with cyclohexane, and vacuum dried to obtain 140 g of a white solid. This white solid was shown to be a mixture of two components by IR, ¹ H-NMR and ²⁹ Si-NMR spectra. When the mixture of silicon compounds was separated by high performance liquid chromatography, it was found that the ratio of main product to by-product was 8: 1. Furthermore, when each IR, ¹ H-NMR, ²⁹ Si-NMR, and TOF-MS spectra were measured, the main product was decaphenylcyclopentasilane and the by-product was dodecaphenylcyclohexasilane. Was confirmed.
(2) 50 g of the mixture of silicon compounds and 500 ml of dried toluene were charged into a 1 L flask, 2 g of aluminum chloride was added, hydrogen chloride was introduced at room temperature, and the reaction was continued for 5 hours under an argon atmosphere. Separately, 20 g of lithium aluminum hydride and 200 ml of diethyl ether were charged into a 2 L flask, the above reaction mixture was added with stirring at 0 ° C. in an argon atmosphere, stirred at the same temperature for 1 hour, and further at room temperature for 12 hours. Stirring was continued. When the aluminum compound was removed from the reaction mixture and the solvent was distilled off, 5 g of a viscous oil was obtained. From the IR, ¹ H-NMR, ²⁹ Si-NMR, and GC-MS spectra, this was a mixture containing cyclopentasilane and silylcyclopentasilane in this order at a ratio of 8: 1. . Cyclopentasilane and silylcyclopentasilane are represented by the following formulas (4) and (5), respectively.
[0019]
[Chemical 2]

[0020]
Reference example 1
Under an argon atmosphere, 5 g of the mixture of silicon compounds obtained in Synthesis Example 1 was dissolved in 45 g of toluene to prepare a solution. This solution was set in the receiver 1 of FIG. 1, and a quartz glass substrate was set inside the heating tube 2. When nitrogen gas was allowed to flow from the gas inlet 3 at a rate of 1 liter / min for 10 minutes while heating the heating tube 2 to 400 ° C., a thin film having a metallic luster was formed on the quartz substrate. At this time, the vapor pressure of toluene was 30 mmHg. When the ESCA spectrum of this thin film having metallic luster was measured, only a peak attributed to Si was observed at 99 eV, and other elements derived from the solvent such as carbon were not detected at all. The thickness of this silicon film was 80 nm. Further, when the Raman spectrum of this Si film was measured, it was found to be amorphous silicon. The specific resistance of this amorphous silicon was 5 × 10 ⁹ Ωcm.
[0021]
Example 1
10 ml of a toluene solution (2 mol / L concentration) of borane / dimethyl sulfide (BH ₃ .SMe ₂ ) complex was added to a solution obtained by dissolving 5 g of the mixture of silicon compounds obtained in Synthesis Example 1 in 45 g of toluene. This solution was set in the receiver 1 of FIG. 1, and a quartz glass substrate was set inside the heating tube 2. When nitrogen gas was allowed to flow from the gas inlet 3 at a rate of 1 liter / min for 20 minutes while heating the heating tube 2 to 400 ° C., a thin film having a metallic luster was formed on the quartz substrate. At this time, the vapor pressure of toluene was 30 mmHg. When the ESCA spectrum of this thin film having metallic luster was measured, only a peak attributed to silicon atoms and boron atoms were observed at 99 eV, and the ratio of silicon atoms to boron atoms was 9: 1. The ESCA spectrum at this time is shown in FIG. It was also found that this thin film was a boron-containing silicon film in which other elements derived from solvents such as carbon and sulfur were completely detected. The film thickness of this boron-containing silicon film was 120 nm. Further, this film was found to be amorphous from the analysis of Raman spectrum. The Raman spectrum at this time is shown in FIG. The specific resistance of the boron-containing amorphous silicon was 3 × 10 ⁴ Ωcm.
[0022]
Example 2
The substrate on which the boron-containing amorphous silicon film obtained in Example 1 was formed was irradiated with a XeCl excimer laser (308 nm) in a nitrogen atmosphere. When the Raman spectrum of the film after laser irradiation was measured, a peak derived from polycrystalline silicon was observed, and the crystallization rate was calculated to be 65%. The Raman spectrum at this time is shown in FIG.
[0023]
Example 3
The substrate on which the boron-containing amorphous silicon film obtained in Example 1 was formed was heat-treated at 800 ° C. for 30 minutes in a nitrogen atmosphere. When the Raman spectrum of the heat-treated film was measured, a peak derived from polycrystalline silicon was observed, and the crystallization rate was calculated to be 55%.
[0024]
Example 4
In Example 1, a polyimide film substrate was set instead of the quartz substrate used in Example 1, and the temperature of the substrate was changed to 300 ° C. The others were carried out in the same manner as in Example 1. As a result, boron was formed on the polyimide substrate. A contained amorphous silicon film could be formed.
The ratio of silicon atoms to boron atoms in this film was 9: 1.
[0025]
Comparative Example 1
Instead of the silicon compound used in Example 1, a mixed gas of monosilane gas and borane gas diluted with hydrogen gas was allowed to flow at a flow rate of 1 liter / min for 30 minutes in an apparatus set at 400 ° C. as in Example 1. . Nothing was deposited on the quartz substrate.
[0026]
【The invention's effect】
According to the present invention, a silicon film doped with boron on a substrate can be efficiently and efficiently formed in a single step with a simple operation and apparatus, without forming a silicon film and doping a dopant in two steps. For example, it can be formed at a high yield and a high formation speed.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view of an apparatus used in Reference Example 1 and Example 1 for carrying out the method of the present invention.
2 is an ESCA spectrum diagram of the boron-containing silicon film obtained in Example 1. FIG.
3 is a Raman spectrum diagram of the boron-containing silicon film obtained in Example 1. FIG.
4 is a Raman spectrum diagram of the boron-containing silicon film obtained in Example 2. FIG.

Claims (2)

Following formula (1)
Si _x H _y . . . (1)
Here, x is a number from 3 to 12, and y is a number from 2x-2 to 2x + 2, and the following formula (2)
Si _n H _n . . . (2)
Here, n is a number from 6 to 12,
At least one silicon compound selected from the group consisting of the compounds represented by the formula (I) and borane / sulfide complex, which is thermally decomposed in the presence of an inert organic medium vapor, doped with boron on the substrate A method of forming a silicon film. (1) The following formula (1)
Si _x H _y . . . (1)
Here, x is a number from 3 to 12, and y is a number from 2x-2 to 2x + 2, and the following formula (2)
Si _n H _n . . . (2)
Here, n is a number from 6 to 12,
An inert gas is passed through a mixture of at least one silicon compound selected from the group consisting of compounds represented by the formula: borane / sulfide complex and inert organic medium, and the above silicon compound, borane in an inert gas carrier. -A gas mixture containing a sulfide complex and an inert organic medium vapor is formed, and then (2) the gas mixture is heated to thermally decompose the silicon compound and borane sulfide complex contained therein onto the substrate. A method of forming a silicon film doped with boron on a substrate, comprising depositing silicon doped with boron.

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