JPH04342120A - Manufacture of hydrogenated amorphous silicon thin film - Google Patents
Manufacture of hydrogenated amorphous silicon thin filmInfo
- Publication number
- JPH04342120A JPH04342120A JP3140679A JP14067991A JPH04342120A JP H04342120 A JPH04342120 A JP H04342120A JP 3140679 A JP3140679 A JP 3140679A JP 14067991 A JP14067991 A JP 14067991A JP H04342120 A JPH04342120 A JP H04342120A
- Authority
- JP
- Japan
- Prior art keywords
- film
- hydrogen
- gas
- atomic
- amorphous silicon
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 229910021417 amorphous silicon Inorganic materials 0.000 title claims abstract description 48
- 239000010409 thin film Substances 0.000 title claims abstract description 15
- 238000004519 manufacturing process Methods 0.000 title claims description 9
- 239000007789 gas Substances 0.000 claims abstract description 60
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 56
- YZCKVEUIGOORGS-UHFFFAOYSA-N Hydrogen atom Chemical compound [H] YZCKVEUIGOORGS-UHFFFAOYSA-N 0.000 claims abstract description 54
- 239000000758 substrate Substances 0.000 claims abstract description 51
- 238000000034 method Methods 0.000 claims abstract description 27
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 claims abstract description 21
- 229910000077 silane Inorganic materials 0.000 claims abstract description 18
- 239000002994 raw material Substances 0.000 claims abstract description 15
- UFHFLCQGNIYNRP-VVKOMZTBSA-N Dideuterium Chemical compound [2H][2H] UFHFLCQGNIYNRP-VVKOMZTBSA-N 0.000 claims abstract description 6
- 238000000151 deposition Methods 0.000 claims description 23
- YZCKVEUIGOORGS-OUBTZVSYSA-N Deuterium Chemical compound [2H] YZCKVEUIGOORGS-OUBTZVSYSA-N 0.000 claims description 13
- 238000005979 thermal decomposition reaction Methods 0.000 claims description 10
- 238000000354 decomposition reaction Methods 0.000 claims description 6
- 229910052805 deuterium Inorganic materials 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 3
- 238000005984 hydrogenation reaction Methods 0.000 claims 2
- 239000010408 film Substances 0.000 abstract description 73
- 229910052739 hydrogen Inorganic materials 0.000 abstract description 36
- 239000001257 hydrogen Substances 0.000 abstract description 36
- 230000003287 optical effect Effects 0.000 abstract description 9
- 230000008569 process Effects 0.000 abstract description 4
- 230000006866 deterioration Effects 0.000 abstract description 2
- 239000010410 layer Substances 0.000 description 35
- 230000008021 deposition Effects 0.000 description 19
- 239000002243 precursor Substances 0.000 description 15
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 10
- 230000001788 irregular Effects 0.000 description 10
- 230000015572 biosynthetic process Effects 0.000 description 8
- 238000005268 plasma chemical vapour deposition Methods 0.000 description 8
- 229910003828 SiH3 Inorganic materials 0.000 description 7
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical group [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 7
- XMIJDTGORVPYLW-UHFFFAOYSA-N [SiH2] Chemical compound [SiH2] XMIJDTGORVPYLW-UHFFFAOYSA-N 0.000 description 7
- 238000001816 cooling Methods 0.000 description 7
- OLRJXMHANKMLTD-UHFFFAOYSA-N silyl Chemical compound [SiH3] OLRJXMHANKMLTD-UHFFFAOYSA-N 0.000 description 7
- 238000002230 thermal chemical vapour deposition Methods 0.000 description 7
- 230000008859 change Effects 0.000 description 6
- 230000007423 decrease Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 230000004913 activation Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 239000003921 oil Substances 0.000 description 4
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 4
- 229910052721 tungsten Inorganic materials 0.000 description 4
- 239000010937 tungsten Substances 0.000 description 4
- 229910008045 Si-Si Inorganic materials 0.000 description 3
- 229910006411 Si—Si Inorganic materials 0.000 description 3
- 238000005229 chemical vapour deposition Methods 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 238000012544 monitoring process Methods 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 2
- 238000004566 IR spectroscopy Methods 0.000 description 2
- 229910008314 Si—H2 Inorganic materials 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- ZOCHARZZJNPSEU-UHFFFAOYSA-N diboron Chemical compound B#B ZOCHARZZJNPSEU-UHFFFAOYSA-N 0.000 description 2
- 238000010574 gas phase reaction Methods 0.000 description 2
- 238000004050 hot filament vapor deposition Methods 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 229910021424 microcrystalline silicon Inorganic materials 0.000 description 2
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 2
- 238000001782 photodegradation Methods 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 230000007847 structural defect Effects 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 101100256922 Caenorhabditis elegans sid-3 gene Proteins 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- XYFCBTPGUUZFHI-UHFFFAOYSA-N Phosphine Chemical compound P XYFCBTPGUUZFHI-UHFFFAOYSA-N 0.000 description 1
- 241000220317 Rosa Species 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 125000004429 atom Chemical group 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- PZPGRFITIJYNEJ-UHFFFAOYSA-N disilane Chemical compound [SiH3][SiH3] PZPGRFITIJYNEJ-UHFFFAOYSA-N 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 238000007733 ion plating Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000013081 microcrystal Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 108091008695 photoreceptors Proteins 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 238000005546 reactive sputtering Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 241000894007 species Species 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
- VEDJZFSRVVQBIL-UHFFFAOYSA-N trisilane Chemical compound [SiH3][SiH2][SiH3] VEDJZFSRVVQBIL-UHFFFAOYSA-N 0.000 description 1
- 238000007738 vacuum evaporation Methods 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
Landscapes
- Photovoltaic Devices (AREA)
Abstract
Description
【0001】0001
【産業上の利用分野】本発明は、機能性膜、特に画像入
力用ラインセンサー、撮像デバイス、太陽電池、光セン
サー、電子写真用感光体デバイス、および薄膜トランジ
スター等の半導体電子デバイスの用途に有用な水素化非
晶質シリコン薄膜の製造方法に関するものである。[Industrial Application Field] The present invention is useful for functional films, particularly for applications in line sensors for image input, imaging devices, solar cells, optical sensors, photoreceptor devices for electrophotography, and semiconductor electronic devices such as thin film transistors. The present invention relates to a method for producing a hydrogenated amorphous silicon thin film.
【0002】0002
【従来の技術】従来、半導体膜、絶縁膜、光導電膜、磁
性膜、あるいは金属膜等の非晶質および多結晶質の機能
性膜は、所望される物理的特性や用途等の観点から個々
に適した成膜法が採用されている。[Prior Art] Conventionally, amorphous and polycrystalline functional films such as semiconductor films, insulating films, photoconductive films, magnetic films, and metal films have been developed from the viewpoint of desired physical properties and uses. A film formation method suitable for each individual is adopted.
【0003】例えば、必要に応じて水素原子(H)等の
補償剤で不対電子が補償された非晶質や多結晶質の非単
結晶シリコン(以後「NON−Si:H」と略記し、そ
のなかでも殊に非晶質シリコンを示す場合には「a−S
i:H」、多結晶質シリコンを示す場合には「poly
−Si:H」と記す)膜等のシリコン堆積膜(尚、いわ
ゆる微結晶シリコン(μc−Si:H)は、a−Si:
Hの範疇にはいる)の形成には、真空蒸着法、プラズマ
化学気相成長法(以後、「プラズマCVD法」と略記す
る)、熱化学気相成長法(以後、「熱CVD法」と略記
する)、反応性スパッタリング法、イオンプレーティン
グ法、光CVD法等が試みられており、一般的には、プ
ラズマCVD法が広く用いられており、企業化されてい
る。For example, amorphous or polycrystalline non-single-crystal silicon (hereinafter abbreviated as "NON-Si:H") whose unpaired electrons are compensated with a compensating agent such as a hydrogen atom (H) as necessary. , especially when referring to amorphous silicon, "a-S"
i:H", and "poly" to indicate polycrystalline silicon.
-Si:H") film (so-called microcrystalline silicon (μc-Si:H))
H) can be formed using vacuum evaporation, plasma chemical vapor deposition (hereinafter abbreviated as "plasma CVD"), and thermal chemical vapor deposition (hereinafter referred to as "thermal CVD"). (abbreviated), reactive sputtering method, ion plating method, photo-CVD method, etc., and generally, plasma CVD method is widely used and has been commercialized.
【0004】0004
【発明が解決しようとする課題】周知のごとく、a−S
i:Hにおける水素(H)の役割は、その結晶構造上の
特徴であるところの不規則網目構造を保持するに当たっ
て必要となるシリコン原子の不対電子(いわゆるダング
リング・ボンド)と結合してこれを補償し、非晶質半導
体に特有の局在準位密度を低減することにある。[Problem to be solved by the invention] As is well known, a-S
The role of hydrogen (H) in i:H is to bond with the unpaired electrons of silicon atoms (so-called dangling bonds), which are necessary to maintain the irregular network structure that is a characteristic of its crystal structure. The purpose is to compensate for this and reduce the localized level density, which is specific to amorphous semiconductors.
【0005】従来、1パスカル(Pa)以下の圧力で、
シラン(SiH4)ガスを成膜基板近傍で1350℃程
度に加熱されたタングステン、モリブデン、あるいはタ
ンタル等からなるヒータにより熱分解してSiH2 前
駆体を生成し、これを200℃程度に加熱保持された成
膜基板上に堆積させ構造的に良好なa−Si:H膜を形
成する熱CVD法(いわゆるHOMO−CVD法)は、
a−Si:H膜の形成法として工業的にも利用されてい
るプラズマCVD法に比べて、プラズマ中で生成するイ
オン種によるa−Si:H膜へのイオン・ダメージを受
けないことから、高品質a−Si:H膜の形成方法とし
て期待されている。Conventionally, at a pressure of 1 Pascal (Pa) or less,
Silane (SiH4) gas was thermally decomposed near the film-forming substrate using a heater made of tungsten, molybdenum, tantalum, etc. heated to about 1350°C to generate a SiH2 precursor, which was then heated and maintained at about 200°C. Thermal CVD method (so-called HOMO-CVD method), which forms a structurally good a-Si:H film by depositing it on a film-forming substrate,
Compared to the plasma CVD method, which is also used industrially as a method for forming a-Si:H films, this method does not cause ion damage to the a-Si:H film due to ion species generated in the plasma. This method is expected to be a method for forming high-quality a-Si:H films.
【0006】ところが、前記SiH2 前駆体が自然分
解するために、a−Si:H膜中に多数のSi−Hポリ
マーが形成され、微小欠陥(いわゆるボイド)の多い膜
を形成してしまい、膜中含有水素量CH が11〜18
原子%(at.%)程度と、プラズマCVD法により形
成されたa−Si:H膜の膜中含有水素量と比較しても
大差がないにもかかわらず、照射光強度100mW/c
mの白色光下で測定した明導電率σphは10−6〜1
0−7シーメンス/cm(s/cm)程度とプラズマC
VD法で形成したa−Si:H膜と比較して2桁程度劣
る膜しか作製できないという問題点があった。However, due to the natural decomposition of the SiH2 precursor, a large number of Si-H polymers are formed in the a-Si:H film, resulting in the formation of a film with many micro defects (so-called voids). Medium hydrogen content CH is 11-18
Although there is no significant difference in the amount of hydrogen contained in the a-Si:H film formed by the plasma CVD method, the irradiation light intensity is 100 mW/c.
The bright conductivity σph measured under white light at m is 10-6 to 1
0-7 Siemens/cm (s/cm) and plasma C
There was a problem in that it was possible to produce a film that was only about two orders of magnitude inferior to the a-Si:H film formed by the VD method.
【0007】この様なSi−Hポリマーの形成を防ぐた
め、たとえば松村が雑誌「電子通信学会技術研究報告」
SDM87−42(1987年)の13頁に発表してい
る様な、前記原料ガスとしてシランガスに水素(H2
)ガスを混合して用い、500Pa程度の圧力で、これ
をタングステン製ヒータで1000〜1500℃の高温
で熱分解してSiH2 前駆体と原子状水素(atm.
H)とを生成し、290〜320℃程度に加熱した成膜
基板上にa−Si:H膜を堆積する「触媒CVD法」と
いう方法が提案されている。これによれば、明導電率σ
phが従来のプラズマCVD法に匹敵する10−3〜1
0−4s/cm程度で、S/N比(明導電率/暗導電率
比)も10−4のオーダーで、光学的バンドギャップE
goptが1.7eV程度の膜が得られている。これは
、原子状水素が大きく作用したためと考えられる。即ち
、光学的バンドギャップEgoptから推測される膜中
含有水素量が10atm.%程度と、従来のプラズマC
VD法で形成した場合と殆ど変わらないことから、シラ
ンガスの熱分解により解離したSiH2 前駆体に、同
じく水素ガスの熱分解により生成した原子状水素が気相
反応してSiH3 前駆体を生成し、これが成膜基板表
面に堆積して、シランガスを脱離放出しながら成長層を
形成する従来のプラズマCVD法に近い堆積メカニスム
が実現されるためと考えられる。また、赤外吸収分光法
(FT−IR法)による観察から、熱CVD法において
もまたこれら膜中含有水素はシリコン原子とSi−H結
合あるいはSi−H2 結合の形態で結合していること
が分かっている。[0007] In order to prevent the formation of such Si-H polymers, for example, Matsumura has
Hydrogen (H2
) gas at a pressure of about 500 Pa and a tungsten heater at a high temperature of 1,000 to 1,500°C to form a SiH2 precursor and atomic hydrogen (atm.
A method called "catalytic CVD method" has been proposed in which an a-Si:H film is deposited on a film-forming substrate heated to about 290 to 320°C. According to this, the bright conductivity σ
pH is 10-3 to 1, comparable to conventional plasma CVD method
The optical band gap E is about 0-4 s/cm, the S/N ratio (bright conductivity/dark conductivity ratio) is on the order of 10-4
A film with gopt of about 1.7 eV has been obtained. This is thought to be due to the large effect of atomic hydrogen. That is, the amount of hydrogen contained in the film estimated from the optical bandgap Egopt is 10 atm. % and conventional plasma C
Since it is almost the same as when formed by the VD method, the SiH2 precursor dissociated by the thermal decomposition of silane gas is reacted in the gas phase with atomic hydrogen also generated by the thermal decomposition of hydrogen gas to generate the SiH3 precursor. This is thought to be due to the fact that this is deposited on the surface of the film-forming substrate, and a deposition mechanism similar to that of the conventional plasma CVD method in which a grown layer is formed while desorbing and releasing silane gas is realized. Furthermore, observation using infrared absorption spectroscopy (FT-IR method) shows that even in thermal CVD, hydrogen contained in these films is bonded to silicon atoms in the form of Si-H bonds or Si-H2 bonds. I know it.
【0008】ところが、近年、プラズマCVD法で形成
したa−Si:H膜の研究から、これら水素原子が、隣
接するシリコン原子どうしの結合角や結合距離に「ゆら
ぎ」を生ぜしめ、a−Si:H特有の価電子帯側の裾状
の準位を形成することが指摘されている。また、内面に
水素原子が結合した微小空孔や、界面にSi−H2 結
合の形態で水素が多数存在している微結晶粒界などの、
中、長距離の巨視的構造でとらえた構造欠陥が、伝導帯
側の裾状の準位の形成およびa−Si:Hの移動度やラ
イフ・タイム等の電気特性に深く関与していると考えら
れている。さらにまた、a−Si:Hに特有の性質であ
る光照射下でのスピン密度の増加(いわゆる光劣化)も
、近年の研究から、水素とシリコンとの電気陰性度の違
いから生ずるというモデルが提唱されている。このよう
に、最近の水素に対する認識は、a−Si:Hに含有さ
れる水素の濃度をいかに低減し、緻密で且つ微小構造欠
陥の少ない不規則網目構造を形成するかという課題を提
起している。これに関しては、熱CVD法で形成したa
−Si:H膜も例外ではない。しかし、熱CVD法によ
るa−Si:H膜の形成は、ようやくSi−Hポリマー
の形成を回避してプラズマCVD法と同程度の膜質を得
られる様になった段階であり、高移動度あるいは光劣化
のない膜形成方法の実現が望まれている。However, in recent years, research on a-Si:H films formed by plasma CVD has revealed that these hydrogen atoms cause "fluctuations" in the bond angles and bond distances between adjacent silicon atoms. : It has been pointed out that a tail-like level on the valence band side peculiar to H is formed. In addition, micropores with hydrogen atoms bonded to their inner surfaces, and microcrystal grain boundaries where many hydrogens exist in the form of Si-H2 bonds at the interface, etc.
Structural defects observed in the macroscopic structure at medium and long distances are deeply involved in the formation of skirt-like levels on the conduction band side and in the electrical properties such as the mobility and lifetime of a-Si:H. It is considered. Furthermore, recent research suggests that the increase in spin density under light irradiation (so-called photodegradation), which is a characteristic characteristic of a-Si:H, is caused by the difference in electronegativity between hydrogen and silicon. It has been proposed. As described above, recent recognition of hydrogen has raised the issue of how to reduce the concentration of hydrogen contained in a-Si:H and form a dense irregular network structure with few microstructural defects. There is. Regarding this, a
-Si:H film is no exception. However, the formation of a-Si:H film by thermal CVD method has finally reached the stage where it has become possible to avoid the formation of Si-H polymer and obtain film quality comparable to that of plasma CVD method. It is desired to realize a film forming method that does not undergo photodeterioration.
【0009】本発明は、以上の様な従来技術の問題点に
鑑み、緻密で水素含有量が少なく明導電率が高く光劣化
が少ないa−Si:H膜を得ることを目的とするもので
ある。In view of the problems of the prior art as described above, the present invention aims to obtain a dense a-Si:H film with low hydrogen content, high bright conductivity, and little photodegradation. be.
【0010】0010
【課題を解決するための手段】本発明によれば、この様
な目的は、シラン系ガスと水素ガス及び/または重水素
ガスとからなる原料ガスを成膜基板近傍において熱分解
して該成膜基板上に水素化非晶質シリコン薄膜を堆積さ
せる水素化非晶質シリコン薄膜の製造方法において、前
記成膜基板を150〜300℃に加熱保持して水素化非
晶質シリコン薄膜を堆積させる第1の工程と、前記原料
ガスの熱分解を行いながら、前記原料ガスの熱分解とは
別の手段で生成した原子状水素及び/または原子状重水
素に前記成膜基板をさらす第2の工程とを交互に繰り返
して行うことを特徴とする、水素化非晶質シリコン薄膜
の製造方法、により達成される。[Means for Solving the Problems] According to the present invention, such an object is achieved by thermally decomposing a raw material gas consisting of a silane gas and hydrogen gas and/or deuterium gas in the vicinity of a film forming substrate. In a method for producing a hydrogenated amorphous silicon thin film in which a hydrogenated amorphous silicon thin film is deposited on a film substrate, the film forming substrate is heated and maintained at 150 to 300°C to deposit a hydrogenated amorphous silicon thin film. a first step, and a second step of exposing the film-forming substrate to atomic hydrogen and/or atomic deuterium generated by a means other than the thermal decomposition of the source gas while thermally decomposing the source gas. This is achieved by a method for producing a hydrogenated amorphous silicon thin film, which is characterized in that the steps are repeated alternately.
【0011】本発明においては、前記第1の工程1回に
おいて堆積される堆積層の厚みが10〜60Åであり、
前記第2の工程1回において堆積される堆積層の厚みが
20Å未満であるのが好ましい。また、本発明において
は、前記原子状水素及び/または原子状重水素の生成を
、分子状水素ガス及び/または分子状重水素ガスをグロ
ー放電分解することにより行うことができ、また別法と
して分子状水素ガス及び/または分子状重水素ガスを前
記原料ガスの熱分解温度より更に高い温度で熱分解する
ことにより行うことができる。[0011] In the present invention, the thickness of the deposited layer deposited in one step of the first step is 10 to 60 Å,
Preferably, the thickness of the deposited layer deposited in one second step is less than 20 Å. Further, in the present invention, the atomic hydrogen and/or atomic deuterium can be generated by glow discharge decomposition of molecular hydrogen gas and/or molecular deuterium gas, and as an alternative method. This can be carried out by thermally decomposing molecular hydrogen gas and/or molecular deuterium gas at a temperature higher than the thermal decomposition temperature of the raw material gas.
【0012】0012
【作用】本発明は、シラン系ガスの熱分解により生成し
たSiH2 前駆体に、水素ガスの熱分解により解離し
た原子状水素を気相反応に寄与させてSiH3 前駆体
を生成し、成膜基板表面における結合水素との間でシラ
ン(SiH4 )を形成して脱離、放出させて不規則網
目構造を形成する触媒CVD法において、前記原料ガス
とは別に生成した原子状水素を表面から注入、拡散させ
ることにより、成長層の不規則網目構造におけるSi−
H結合及びマイクロ・ボイド内面の結合水素等を切断し
て、水素分子を生成し放出させてSi−Si結合の復興
を促すとともに、シリコン原子の不対電子を原子状水素
により補償することで、緻密で且つ膜中含有水素量を低
減した不規則網目構造を有するa−Si:H膜を形成す
るものである。尚、シラン系ガスとしては、シラン(S
iH4 )ガス以外に、ジシラン(Si2 H6 )ガ
スやトリシラン(Si3 H8 )ガス等の高次シラン
ガスを使用することもできる。[Operation] The present invention generates a SiH3 precursor by causing atomic hydrogen dissociated by thermal decomposition of hydrogen gas to contribute to a gas phase reaction in a SiH2 precursor generated by thermal decomposition of a silane-based gas. In the catalytic CVD method in which silane (SiH4) is formed with bonded hydrogen on the surface, desorbed and released to form an irregular network structure, atomic hydrogen generated separately from the source gas is injected from the surface, By diffusing Si-
By cutting H bonds and bonded hydrogen on the inner surface of micro-voids, generating and releasing hydrogen molecules to promote the recovery of Si-Si bonds, and compensating for unpaired electrons in silicon atoms with atomic hydrogen, An a-Si:H film is formed which is dense and has an irregular network structure with a reduced amount of hydrogen contained in the film. Incidentally, as the silane-based gas, silane (S
In addition to iH4 ) gas, higher-order silane gases such as disilane (Si2 H6) gas and trisilane (Si3 H8) gas can also be used.
【0013】一方、原子状重水素(atm.D)にさら
した場合も、前記SiH3 前駆体がSiH2 D、S
iHD2 、SiD3 等の前駆体の形態をとり、また
膜表面から脱離、放出されるガス分子がH2 分子以外
にSiD4 分子あるいはHD分子等の形態をとる以外
は原子状水素にさらした場合と全く同じ作用をする。On the other hand, when exposed to atomic deuterium (atm.D), the SiH3 precursor becomes SiH2D, S
It takes the form of precursors such as iHD2 and SiD3, and the gas molecules desorbed and released from the film surface take the form of SiD4 molecules or HD molecules in addition to H2 molecules. have the same effect.
【0014】ここで、成長層が安定した不規則網目構造
を形成するためには、成膜条件にもよるが、第1の工程
で数原子層程度の厚み即ち10〜60Å程度の厚みの形
成が必要であり、余り厚くすると内部層が形成されるた
め、ここに分子状水素が閉じ込められて放出されなくな
り、本発明の作用を十分には発揮することができない。
また、原子状水素にさらす第2の工程では、原子状水素
が成長表面に到達したSiH3 前駆体と反応し、Si
H4 ガス分子として再放出され、堆積速度が低下する
ために、20Å程度の厚みのa−Si:H膜を堆積する
時間でも、原子状水素は十分に上記作用を完了する。尚
、原子状水素または原子状重水素は、その荷電状態にか
かわらず使用することができるが、熱CVD法の特徴が
イオン・ダメージ・フリーであることを考慮すると、電
気的に中性である方が好ましい。Here, in order to form a stable irregular network structure in the grown layer, it is necessary to form a thickness of about several atomic layers, that is, about 10 to 60 Å, in the first step, although it depends on the film forming conditions. If the thickness is too thick, an inner layer will be formed, and molecular hydrogen will be trapped there and will not be released, making it impossible to fully exhibit the effects of the present invention. In addition, in the second step of exposure to atomic hydrogen, the atomic hydrogen reacts with the SiH3 precursor that has reached the growth surface, and the Si
Since it is re-emitted as H4 gas molecules and the deposition rate is reduced, the atomic hydrogen is sufficient to complete the above action even in the time it takes to deposit an a-Si:H film with a thickness of about 20 Å. Note that atomic hydrogen or atomic deuterium can be used regardless of its charge state, but considering that the thermal CVD method is free from ion damage, it is electrically neutral. is preferable.
【0015】また、ドーピングを行う場合には、従来の
熱CVD法と同様、原料ガスにジボラン(B2 H6
)ガスあるいはホスフィン(PH3 )ガスを混合して
熱分解して価電子制御を行うことができる。Furthermore, when doping is performed, diborane (B2 H6
) gas or phosphine (PH3) gas can be mixed and thermally decomposed to control valence electrons.
【0016】[0016]
【実施例】図1は、本発明の一実施例に用いる熱CVD
装置を示す断面図である。堆積管11の内部には、成膜
用ガラス基板1を支持し、その温度を一定に保持する恒
温台12がある。該恒温台12には基板1を加熱保持す
るためのヒータ13及び冷却管14が内蔵されている。
該冷却管14の内部にはオイルが流れている。基板1の
近傍には基板温度モニター用の熱電対15が設置されて
おり、これをモニターしてヒータ13の加熱温度と冷却
管14内のオイル流量とを調整して基板温度を一定に保
持することができる。基板1の真上20mmの位置には
タングステン製リボン・ヒータ16が設置されており、
直流定電流電源17により2000℃まで加熱できる。
尚、リボン・ヒータ16の表面は、a−Si:H膜への
タングステンの混入を防ぐため、アルミナ・セラミック
ス材(図示されていない)により被覆されている。堆積
管11の端部には原料ガス導入管18及び原子状水素導
入管19が接続されており、堆積管11のもう一方の端
部には排気管20が接続されている。原料ガス導入管1
9には高速開閉バルブ21及び他の真空排気装置(図示
されていない)に接続されたT字配管22、さらには周
波数2.45GHzのマイクロ波電源23に接続された
アプリケータ型放電管24が接続されている。また、排
気管20には、コンダクタンス・バルブ25を介して真
空ポンプ26が接続されている。[Example] Figure 1 shows a thermal CVD method used in an example of the present invention.
FIG. 2 is a sectional view showing the device. Inside the deposition tube 11, there is a constant temperature table 12 that supports the glass substrate 1 for film formation and keeps its temperature constant. The constant temperature table 12 has a built-in heater 13 and a cooling pipe 14 for heating and holding the substrate 1. Oil flows inside the cooling pipe 14. A thermocouple 15 for monitoring the substrate temperature is installed near the substrate 1, and by monitoring this, the heating temperature of the heater 13 and the oil flow rate in the cooling pipe 14 are adjusted to keep the substrate temperature constant. be able to. A tungsten ribbon heater 16 is installed at a position 20 mm directly above the substrate 1.
It can be heated up to 2000°C by the DC constant current power supply 17. Note that the surface of the ribbon heater 16 is coated with an alumina ceramic material (not shown) to prevent tungsten from being mixed into the a-Si:H film. A source gas introduction pipe 18 and an atomic hydrogen introduction pipe 19 are connected to one end of the deposition tube 11, and an exhaust pipe 20 is connected to the other end of the deposition pipe 11. Raw material gas introduction pipe 1
9 has a T-shaped pipe 22 connected to a high-speed opening/closing valve 21 and other evacuation equipment (not shown), and an applicator type discharge tube 24 connected to a microwave power source 23 with a frequency of 2.45 GHz. It is connected. Further, a vacuum pump 26 is connected to the exhaust pipe 20 via a conductance valve 25.
【0017】この装置を用いて行われた本発明の一実施
例を、図2を参照して述べる。An embodiment of the present invention carried out using this apparatus will be described with reference to FIG.
【0018】まず、基板1を恒温台12の上に設置し、
堆積管11の扉を閉めてコンダクタンス・バルブ25を
全開にして真空ポンプ26でその内部を真空に排気し、
堆積管11内のリボン・ヒータ16及びヒータ13に通
電し、冷却管14内にオイルを流して、熱電対15をモ
ニターしながら恒温台12上の基板1の温度が250℃
になる様に調整した。次に、高速開閉バルブ21を開け
、水素ガスを50sccmの流量で堆積管11内に導入
し、コンダクタンス・バルブ25の開口度を調節して堆
積管11内の圧力を1.00Torrに調整した。この
状態で、1時間ほど水素ガスを流し続け、リボン・ヒー
タ16の温度が1200℃になる様に直流定電流電源1
7の電流値を調整すると同時に、その輻射熱により基板
1の温度が上昇するため、冷却管14のオイル流量を調
整して冷却し基板温度を250℃に保持した。First, the substrate 1 is placed on a constant temperature table 12,
The door of the deposition tube 11 is closed, the conductance valve 25 is fully opened, and the inside is evacuated using the vacuum pump 26.
The ribbon heater 16 and heater 13 in the deposition tube 11 are energized, oil is flowed into the cooling tube 14, and the temperature of the substrate 1 on the thermostatic table 12 is raised to 250° C. while monitoring the thermocouple 15.
I adjusted it so that Next, the high-speed opening/closing valve 21 was opened, hydrogen gas was introduced into the deposition tube 11 at a flow rate of 50 sccm, and the opening degree of the conductance valve 25 was adjusted to adjust the pressure inside the deposition tube 11 to 1.00 Torr. In this state, continue to flow hydrogen gas for about an hour, and keep the DC constant current power supply 1 so that the temperature of the ribbon heater 16 reaches 1200°C.
At the same time as the current value of 7 was adjusted, the temperature of the substrate 1 rose due to the radiant heat, so the oil flow rate of the cooling pipe 14 was adjusted to cool the substrate 1 and maintain the substrate temperature at 250°C.
【0019】次に、リボン・ヒータ16及び基板1の温
度が安定したところで、マイクロ波電源23からアプリ
ケータ型放電管24にマイクロ波電力を供給し、放電管
内にて水素プラズマを生起させ、原子状水素を生成した
。次に、高速開閉バルブ21を閉じ、T字配管22から
他の真空排気装置に原子状水素を捨て、アプリケータ型
放電管24内の水素プラズマを維持した。高速開閉バル
ブ21を閉じたと同時に、原料ガス導入管18からシラ
ンガス及び水素ガスを各々20sccm及び50scc
mの流量で、堆積管11内に導入し、且つコンダクタン
ス・バルブ25の開口度を調節して堆積管11内の圧力
を2.00Torrに調整した。導入したシランガス及
び水素ガスはリボン・ヒータ16の熱により解離し、図
2の(a)に示す様に、SiH2 前駆体2及び原子状
水素3が生成する。これらの活性種は更に気相反応して
SiH3 前駆体4を生成して基板1に到達し、堆積速
度3.4Å/secでa−Si:H膜の成長層5が堆積
した。このとき、a−Si:Hに特有の不規則網目構造
の大枠ができあがる。表面にはSi−H2 結合が多く
、また成長層5自体もSi−Si結合への構造緩和過程
にあり、Si−H結合や内面にSi−H結合を多数有す
る微小空孔を多く含有する。更に堆積を継続すると、表
面近傍の過剰水素原子は他の過剰水素原子とともに水素
分子を形成し、膜外に脱離、放出されるが、構造緩和が
更に進んだ成長層5の内部では、基板1に近い層から徐
々に構造的自由度を確保しながら凝固し始めるために、
不対電子を水素原子で補償した不規則網目構造を有する
内部層5’が形成される。300℃程度の温度では、こ
の成長層5及び内部層5’の結合水素原子の自発的な解
離は起こらず、10%程度の水素原子がSi−H結合や
微小空孔を形成する形で膜中に残留することになる。Next, when the temperatures of the ribbon heater 16 and the substrate 1 have stabilized, microwave power is supplied from the microwave power source 23 to the applicator type discharge tube 24 to generate hydrogen plasma in the discharge tube, and atoms Hydrogen was produced. Next, the high-speed opening/closing valve 21 was closed, and the atomic hydrogen was discarded from the T-shaped pipe 22 to another vacuum evacuation device to maintain the hydrogen plasma in the applicator type discharge tube 24. At the same time as the high-speed opening/closing valve 21 is closed, silane gas and hydrogen gas are supplied from the raw material gas introduction pipe 18 at 20 sccm and 50 sccm, respectively.
The pressure inside the deposition tube 11 was adjusted to 2.00 Torr by adjusting the opening degree of the conductance valve 25. The introduced silane gas and hydrogen gas are dissociated by the heat of the ribbon heater 16, and a SiH2 precursor 2 and atomic hydrogen 3 are produced as shown in FIG. 2(a). These active species further reacted in the gas phase to generate SiH3 precursor 4, which reached the substrate 1, and a growth layer 5 of an a-Si:H film was deposited at a deposition rate of 3.4 Å/sec. At this time, a large frame of an irregular network structure peculiar to a-Si:H is completed. There are many Si--H2 bonds on the surface, and the growth layer 5 itself is in the process of structural relaxation to Si--Si bonds, and contains many Si--H bonds and micropores having many Si--H bonds on the inner surface. As the deposition continues, the excess hydrogen atoms near the surface form hydrogen molecules together with other excess hydrogen atoms, and are desorbed and released outside the film. In order to gradually start solidifying from a layer close to 1 while ensuring structural freedom,
An inner layer 5' having an irregular network structure in which unpaired electrons are compensated with hydrogen atoms is formed. At a temperature of about 300°C, the bonded hydrogen atoms in the grown layer 5 and the inner layer 5' do not spontaneously dissociate, and about 10% of the hydrogen atoms form Si-H bonds and micropores in the film. It will remain inside.
【0020】原料ガスを導入してから15秒後、成長層
5の厚みが50Åに到達し、内部層5’が形成され始め
たところで、高速開閉バルブ21を開け、堆積管11内
にマイクロ波放電により水素ガスをプラズマ分解して得
た原子状水素6を導入すると、図2の(b)に示す様に
、成長層5の表面はこの原子状水素にさらされることに
なる。この原子状水素6の一部は堆積空間内のSiH3
前駆体4と気相反応してシラン(SiH4 )ガスを
形成し、原子状水素処理層7の堆積速度を1.1Å/s
ec程度に低下させるが、同時にそれ以外の原子状水素
6は成長表面から更に膜中に拡散することができ、原子
状水素処理中に前記成長層5及び内部層5’に到達する
ことができる。成長層5に達した原子状水素8は、微小
空孔内のSi−H結合を切断してSi−Si結合を復興
させ、これらを凝縮することで、緻密な不規則網目構造
を実現する。このとき、原子状水素8と結合したSi−
H結合の水素原子8’は、水素分子9となり徐々につぶ
れていく複数の微小空孔内を伝わって原子状水素処理層
7の表面に達し、膜外に放出される。一方、内部層5’
に達した原子状水素8は、主にシリコン原子の不対電子
と結合して、これを補償するが、原子状水素処理時間が
18秒間(原子状水素処理層7の膜厚は20Å)と短い
ことから、その量は少ない。この原子状水素処理により
膜中含有水素の量が減少する。この原子状水素処理時間
は内部層5’が形成され始めるまでの程度であるのが好
ましく、あまり長い時間原子状水素6にさらすと、拡散
した原子状水素8が内部層5’のSi−Si結合までも
切断して残留し、本発明の効果を十分には発揮すること
ができなくなる。15 seconds after the introduction of the raw material gas, when the thickness of the growth layer 5 reaches 50 Å and the internal layer 5' begins to be formed, the high-speed opening/closing valve 21 is opened and the microwave is introduced into the deposition tube 11. When atomic hydrogen 6 obtained by plasma decomposing hydrogen gas by electric discharge is introduced, the surface of the growth layer 5 is exposed to this atomic hydrogen, as shown in FIG. 2(b). A part of this atomic hydrogen 6 is SiH3 in the deposition space.
Silane (SiH4) gas is formed by a gas phase reaction with the precursor 4, and the deposition rate of the atomic hydrogen treatment layer 7 is increased to 1.1 Å/s.
ec, but at the same time, other atomic hydrogen 6 can diffuse further into the film from the growth surface and reach the growth layer 5 and inner layer 5' during the atomic hydrogen treatment. . The atomic hydrogen 8 that has reached the growth layer 5 breaks the Si--H bonds within the micropores, restores the Si--Si bonds, and condenses them to realize a dense irregular network structure. At this time, Si-
The H-bonded hydrogen atoms 8' become hydrogen molecules 9, travel through a plurality of micropores that gradually collapse, reach the surface of the atomic hydrogen treatment layer 7, and are released outside the film. On the other hand, the inner layer 5'
The atomic hydrogen 8 that has reached this level mainly combines with unpaired electrons of silicon atoms to compensate for this, but the atomic hydrogen treatment time is 18 seconds (the thickness of the atomic hydrogen treatment layer 7 is 20 Å). Since it is short, the amount is small. This atomic hydrogen treatment reduces the amount of hydrogen contained in the film. It is preferable that the time for this atomic hydrogen treatment is long enough until the inner layer 5' begins to be formed.If the atomic hydrogen 6 is exposed for too long, the diffused atomic hydrogen 8 will be absorbed into the Si-Si layer 5'. Even the bonds are broken and remain, making it impossible to fully exhibit the effects of the present invention.
【0021】次に、高速開閉バルブ21を閉じて、原子
状水素6の供給を停止し、図2の(c)に示す様に、第
1の工程(原料ガスのみによる堆積工程)に戻し、成長
層5を堆積させた。成長層5の厚みが内部層5’が形成
される程度に厚くなると、図2の(b)において堆積し
た原子状水素処理層7以下の層は構造が安定し、緻密で
構造欠陥の少ない不規則網目構造を有する低水素含有a
−Si:H膜10となる。この様にして膜厚6000Å
の低水素含有a−Si:H膜を成膜基板1上に堆積させ
た後、シランガス及び水素ガスの供給を停止して堆積を
完了し、高速開閉バルブ21も閉じて、原子状水素6の
供給を停止し、リボン・ヒータ16及びヒータ13の電
源を切り、基板1を冷却し、バタフライ・バルブ25を
閉じて、堆積管11を大気圧に戻した後、扉を開けて基
板1を搬出した。Next, the high-speed opening/closing valve 21 is closed to stop the supply of atomic hydrogen 6, and as shown in FIG. A growth layer 5 was deposited. When the thickness of the grown layer 5 becomes thick enough to form the inner layer 5', the layers below the atomic hydrogen treatment layer 7 deposited in FIG. 2(b) have a stable structure, are dense, and have few structural defects. Low hydrogen content a with regular network structure
-Si:H film 10 is obtained. In this way, the film thickness was 6000Å.
After depositing a low hydrogen-containing a-Si:H film on the deposition substrate 1, the supply of silane gas and hydrogen gas is stopped to complete the deposition, and the high-speed opening/closing valve 21 is also closed to remove the atomic hydrogen 6. After stopping the supply, turning off the power to the ribbon heater 16 and heater 13, cooling the substrate 1, and closing the butterfly valve 25 to return the deposition tube 11 to atmospheric pressure, the door is opened and the substrate 1 is carried out. did.
【0022】同様にして、赤外吸収分光法(FT−IR
法)による膜中含有水素量の測定のため、n型単結晶シ
リコン基板を用いてa−Si:H膜を堆積した。Similarly, infrared absorption spectroscopy (FT-IR
In order to measure the amount of hydrogen contained in the film using the method, an a-Si:H film was deposited using an n-type single crystal silicon substrate.
【0023】図3は、上記実施例の方法で基板温度を1
50℃から300℃まで50℃おきに変えて作製したa
−Si:H膜の、基板温度変化に対する、膜中含有水素
量CH (at.%)の変化、及び光学的バンドギャッ
プEgopt(eV)の変化の測定結果を示す。本発明
実施例(図3で実線で示されている)の膜中水素含有量
CHは、基板温度の上昇に伴って減少し、原子状水素処
理を施さなかった場合(図3で破線で示されている)に
比べて5at.%程度減少し、基板温度250℃では7
at.%であった。また、光学的バンドギャップは膜中
含有水素量に伴って変化することが知られており、基板
温度の上昇に伴って単調に減少し、原子状水素処理を施
さなかった場合(図3で破線で示されている)に比べて
0.05eV以上狭くなっており、基板温度250℃で
は1.67eVであった。FIG. 3 shows that the substrate temperature is increased by 1 using the method of the above embodiment.
A made by changing the temperature from 50℃ to 300℃ every 50℃
The measurement results of changes in hydrogen content CH (at.%) and optical band gap Egopt (eV) of the -Si:H film with respect to changes in substrate temperature are shown. The hydrogen content CH in the film of the present invention example (indicated by the solid line in FIG. 3) decreases as the substrate temperature increases, and when no atomic hydrogen treatment is performed (indicated by the broken line in FIG. 3), the hydrogen content CH in the film decreases as the substrate temperature increases. 5at. 7% at a substrate temperature of 250°C.
at. %Met. Furthermore, it is known that the optical bandgap changes with the amount of hydrogen contained in the film, and decreases monotonically as the substrate temperature increases, and when no atomic hydrogen treatment is performed (the broken line in Figure 3 ) is narrower by more than 0.05 eV, and it was 1.67 eV at a substrate temperature of 250°C.
【0024】また、図4は、同じく基板温度変化に対す
る、a−Si:H膜の活性化エネルギーEad(eV)
の変化、及びAM−1での照射光強度100mW/cm
2 での明導電率σp (s/cm)と暗導電率σd
(s/cm)との変化を示す。活性化エネルギーEad
は基板温度の上昇とともにn− 型のままで僅かながら
小さくなるが、図3に示した様に、光学的バンドギャッ
プも膜中含有水素量に伴って狭くなっているため、フェ
ルミ・レベルが実際に伝導帯側に移動したかどうかは不
明である。
また、明導電率σp 及び暗導電率σd は基板温度2
50℃付近を境にして大きく変化し、明導電率σp は
7×10−5s/cmが最大値であり、暗導電率σd
は7×10−10 s/cmが最小値となる。ここで、
基板温度150℃において明/暗導電率比(S/N比)
が2桁程度しかとれない原因としては、基板温度が低温
になるほど膜中にマイクロ・ボイドが多数形成されるた
め、上記処理条件でもこれらボイドを完全には除去でき
ないためであると考えられる。いずれにせよ、250℃
を中心として最適な基板温度が選択できる。FIG. 4 also shows the activation energy Ead (eV) of the a-Si:H film with respect to substrate temperature changes.
change, and irradiation light intensity 100 mW/cm in AM-1
Bright conductivity σp (s/cm) and dark conductivity σd at 2
(s/cm). Activation energy Ead
remains n- type and becomes slightly smaller as the substrate temperature rises, but as shown in Figure 3, the optical bandgap also narrows as the amount of hydrogen contained in the film increases, so the Fermi level actually It is unclear whether it moved to the conduction band side. In addition, the bright conductivity σp and the dark conductivity σd are determined by the substrate temperature 2
It changes greatly around 50℃, and the bright conductivity σp has a maximum value of 7×10-5 s/cm, and the dark conductivity σd
has a minimum value of 7×10−10 s/cm. here,
Bright/dark conductivity ratio (S/N ratio) at substrate temperature 150°C
It is thought that the reason why . In any case, 250℃
The optimum substrate temperature can be selected based on
【0025】図5は、同じく基板温度変化に対する、最
小金属伝導度σ0(s/cm)の変化、一定光電流法(
CPM)で測定した価電子帯側裾準位分布を表すアーバ
ック・テールの傾きE0 (meV)と不対電子(ダン
グリング・ボンド)が作るバンド中央付近の局在準位の
密度DOS(1/cm3 )値の変化を示す。絶対零度
のときの伝導度を前記活性化エネルギー及び暗導電率か
ら算出した最小金属伝導度σ0 は、250℃付近に最
大106 のオーターのピークをもつ曲線を示し、これ
は大きな移動度を予見させるものである。また、アーバ
ック・テールの傾きE0も基板温度の上昇とともに急に
なり、膜中含有水素量の低下とともに「ゆらぎ」が改善
されたことを示している。さらにまた、DOS値も25
0℃付近で最小となり1014のオーダーとなった。こ
れは、原子状水素処理を施さなかった場合のDOS値が
1015のオーダーであったことと比較すると、膜中含
有水素量の低下にもかかわらず、緻密な不規則網目構造
の形成と並行して不対電子の補償が行われることを示唆
する。以上のことから、原子状水素処理の基板温度条件
としては、250℃程度を選択するのが好ましい。FIG. 5 also shows the change in the minimum metal conductivity σ0 (s/cm) with respect to the change in substrate temperature, using the constant photocurrent method (
The slope E0 (meV) of the Urbach tail representing the valence band side tail level distribution measured by CPM) and the density of localized levels near the band center created by unpaired electrons (dangling bonds) DOS (1 /cm3) shows the change in value. The minimum metal conductivity σ0, which is the conductivity at absolute zero calculated from the activation energy and dark conductivity, shows a curve with a maximum peak of 106 degrees around 250°C, which predicts a large mobility. It is something. Furthermore, the slope E0 of the Urbach tail also became steeper as the substrate temperature increased, indicating that the "fluctuation" was improved as the amount of hydrogen contained in the film decreased. Furthermore, the DOS value is also 25.
It reached its minimum around 0°C and was on the order of 1014. This is in parallel with the formation of a dense irregular network structure despite the decrease in the amount of hydrogen contained in the film, compared to the DOS value of the order of 1015 without atomic hydrogen treatment. This suggests that compensation for unpaired electrons is performed. From the above, it is preferable to select about 250° C. as the substrate temperature condition for the atomic hydrogen treatment.
【0026】図6は、基板温度250℃の条件で作製し
たa−Si:H膜に対し連続的に光照射した場合(AM
−1;照射光強度100mW/cm2 )の明導電率σ
p の経時変化を示す。比較のため、原子状水素処理を
施さずに作製したa−Si:H膜の明導電率σp の経
時変化を破線で示す。1000分(約16.5時間)経
過後に、原子状水素処理を施さなかった場合には初期値
の1/50程度になったのに対し、原子状水素処理を施
した本発明実施例の場合には初期値の1/2程度と劣化
が極めて少なく、a−Si:H膜に特有の問題点として
認識されていた光劣化が改善された。これは、本発明に
よる膜中含有水素量低減の効果の一つである。FIG. 6 shows the case where an a-Si:H film prepared at a substrate temperature of 250° C. was continuously irradiated with light (AM
-1; bright conductivity σ at irradiation light intensity 100 mW/cm2)
It shows the change in p over time. For comparison, the broken line shows the change over time in the bright conductivity σp of the a-Si:H film produced without atomic hydrogen treatment. After 1000 minutes (approximately 16.5 hours), the value was about 1/50 of the initial value when atomic hydrogen treatment was not performed, whereas in the case of the present invention example where atomic hydrogen treatment was performed. The deterioration was extremely small, being about 1/2 of the initial value, and the photodeterioration, which had been recognized as a problem specific to a-Si:H films, was improved. This is one of the effects of reducing the amount of hydrogen contained in the film according to the present invention.
【0027】本発明の他の実施例を示す。Another embodiment of the present invention will now be described.
【0028】シランガス20sccmとともに水素ガス
で希釈したジボラン(B2 H6 )ガス50sccm
を原料ガス導入管18から供給し、a−Si:H膜への
ドーピングを行った。このときのドーピング量は、ジボ
ランガスとシランガスとの濃度比で3000ppmの濃
度であった。得られたa−Si:H膜は、暗導電率が2
×10−3s/cmで、活性化エネルギーが0.3eV
であった。20 sccm of silane gas and 50 sccm of diborane (B2 H6) gas diluted with hydrogen gas.
was supplied from the raw material gas introduction pipe 18 to dope the a-Si:H film. The doping amount at this time was a concentration ratio of diborane gas and silane gas of 3000 ppm. The obtained a-Si:H film has a dark conductivity of 2
×10-3s/cm, activation energy is 0.3eV
Met.
【0029】尚、原子状水素または原子状重水素の生成
方法としては、前記実施例におけるマイクロ波プラズマ
による分解が最も効率が良いが、これ以外に、原子状水
素導入管19に接続したマイクロ波電源23及びアプリ
ケータ型放電管24の代わりに、図7に示す様に、水素
ガス分解炉として石英管に容量結合型電極を配置し、そ
の一方の電極に周波数13.56MHzの高周波電源2
7を接続した高周波放電管28を用い、これを原子状水
素導入管19に接続して、水素ガスを分解してもよい。
但し、この場合は、前記マイクロ波放電を用いる場合に
比べてプラズマの電子密度が低いため、水素分子の分解
効率が低下することを考慮して、高出力の高周波電力を
投入するのがよい。As for the method of producing atomic hydrogen or atomic deuterium, decomposition using microwave plasma in the above embodiment is the most efficient, but in addition to this, microwave Instead of the power source 23 and the applicator type discharge tube 24, as shown in FIG. 7, a capacitively coupled electrode is arranged in a quartz tube as a hydrogen gas decomposition furnace, and a high frequency power source 2 with a frequency of 13.56 MHz is connected to one of the electrodes.
Hydrogen gas may be decomposed by using a high-frequency discharge tube 28 connected to 7 and connecting it to the atomic hydrogen introduction tube 19. However, in this case, since the electron density of the plasma is lower than in the case of using the microwave discharge, it is preferable to input high-output radio-frequency power, taking into consideration that the decomposition efficiency of hydrogen molecules will be lowered.
【0030】尚、前記実施例では、単層膜の改質につい
て例示したが、図3に示す様に光学的バンドギャップを
適宜選択できることから、多層構造の素子等に用いる場
合には、その界面層の改質に利用することができる。In the above embodiment, modification of a single layer film was exemplified, but since the optical band gap can be appropriately selected as shown in FIG. It can be used to modify layers.
【0031】[0031]
【発明の効果】本発明によれば、シラン系ガスと水素ガ
ス及び/または重水素ガスとを原料とし、これを熱分解
して150〜300℃に加熱保持した基板上にa−Si
:H膜を堆積させる第1の工程と、前記原料ガスの熱分
解を行いながら、前記原料ガスの熱分解とは別の手段で
生成した原子状水素及び/または原子状重水素に前記成
膜基板をさらす第2の工程とを交互に繰り返して行うこ
とで、成長表面層の過剰結合水素をSi−H結合を保存
したまま分子状水素として脱離、放出することで膜中含
有水素量を低減し、これに引き続いて原子状水素及び/
または原子状重水素にさらすことで、成長層及びその直
下の内部層にこれらを注入、拡散せしめ、複数のSi−
H結合を切断してSi−Si結合の復興を促し、且つシ
リコン原子の不対電子を原子状水素により補償し、緻密
で水素含有量の少ない不規則網目構造を形成することが
でき、局在準位密度が極めて少なく、明導電率に優れ且
つ長時間の光照射でも明導電率が殆ど低下しないa−S
i:H膜を製造できることから、光電変換特性に優れ、
光劣化の少ない光センサーや太陽電池、更には高速応答
性能に優れたTFTなどを実現する上で、極めて有効で
ある。According to the present invention, silane gas and hydrogen gas and/or deuterium gas are used as raw materials, which are thermally decomposed and a-Si is deposited on a substrate heated and maintained at 150 to 300°C.
: A first step of depositing a H film, and while performing thermal decomposition of the raw material gas, forming the film on atomic hydrogen and/or atomic deuterium generated by a means other than the thermal decomposition of the raw material gas. By repeating the second step of exposing the substrate alternately, excess bonded hydrogen in the growing surface layer is desorbed and released as molecular hydrogen while preserving Si-H bonds, thereby reducing the amount of hydrogen contained in the film. This is followed by atomic hydrogen and/or
Alternatively, by exposing to atomic deuterium, these can be implanted and diffused into the growth layer and the inner layer immediately below it, resulting in multiple Si-
It can cut H bonds to promote the recovery of Si-Si bonds, and compensate for the unpaired electrons of silicon atoms with atomic hydrogen, forming a dense irregular network structure with low hydrogen content. a-S with extremely low level density, excellent bright conductivity, and almost no decrease in bright conductivity even after long-term light irradiation
Since the i:H film can be manufactured, it has excellent photoelectric conversion properties,
It is extremely effective in realizing optical sensors and solar cells with little photodeterioration, as well as TFTs with excellent high-speed response performance.
【図1】本発明の実施に用いる装置の断面図である。FIG. 1 is a cross-sectional view of an apparatus used to practice the invention.
【図2】本発明の工程の説明のための模式的断面図であ
る。FIG. 2 is a schematic cross-sectional view for explaining the process of the present invention.
【図3】本発明の実施により得られるa−Si:H膜の
特性の一例を示す図である。FIG. 3 is a diagram showing an example of the characteristics of an a-Si:H film obtained by implementing the present invention.
【図4】本発明の実施により得られるa−Si:H膜の
特性の一例を示す図である。FIG. 4 is a diagram showing an example of the characteristics of an a-Si:H film obtained by implementing the present invention.
【図5】本発明の実施により得られるa−Si:H膜の
特性の一例を示す図である。FIG. 5 is a diagram showing an example of the characteristics of an a-Si:H film obtained by implementing the present invention.
【図6】本発明の実施により得られるa−Si:H膜の
特性の一例を示す図である。FIG. 6 is a diagram showing an example of the characteristics of an a-Si:H film obtained by implementing the present invention.
【図7】本発明の実施に用いる装置の断面図である。FIG. 7 is a cross-sectional view of an apparatus used to practice the invention.
1 成膜基板 2 SiH2 前駆体 3 原子状水素 4 SiH3 前駆体 5 成長層 5’ 内部層 6 原子状水素 7 原子状水素処理層 8,8’ 原子状水素 9 分子状水素 11 堆積管 12 恒温台 13 ヒータ 14 冷却管 15 熱電対 16 リボン・ヒータ 17 ヒータ電源 18 原料ガス導入管 19 原子状水素導入管 20 排気管 21 高速開閉バルブ 22 T字配管 23 マイクロ波電源 24 アプリケータ型放電管 25 コンダクタンス・バルブ 26 真空ポンプ 27 高周波電源 28 容量結合型高周波放電管 1 Film-forming substrate 2 SiH2 precursor 3 Atomic hydrogen 4 SiH3 precursor 5 Growth layer 5’ inner layer 6 Atomic hydrogen 7 Atomic hydrogen treatment layer 8,8' Atomic hydrogen 9 Molecular hydrogen 11 Deposition tube 12 Thermostatic stand 13 Heater 14 Cooling pipe 15 Thermocouple 16 Ribbon heater 17 Heater power supply 18 Raw material gas introduction pipe 19 Atomic hydrogen introduction tube 20 Exhaust pipe 21 High-speed opening/closing valve 22 T-shaped piping 23 Microwave power supply 24 Applicator type discharge tube 25 Conductance valve 26 Vacuum pump 27 High frequency power supply 28 Capacitively coupled high frequency discharge tube
Claims (4)
重水素ガスとからなる原料ガスを成膜基板近傍において
熱分解して該成膜基板上に水素化非晶質シリコン薄膜を
堆積させる水素化非晶質シリコン薄膜の製造方法におい
て、前記成膜基板を150〜300℃に加熱保持して水
素化非晶質シリコン薄膜を堆積させる第1の工程と、前
記原料ガスの熱分解を行いながら、前記原料ガスの熱分
解とは別の手段で生成した原子状水素及び/または原子
状重水素に前記成膜基板をさらす第2の工程とを交互に
繰り返して行うことを特徴とする、水素化非晶質シリコ
ン薄膜の製造方法。1. Hydrogenation in which a raw material gas consisting of a silane-based gas and hydrogen gas and/or deuterium gas is thermally decomposed in the vicinity of a film-forming substrate to deposit a hydrogenated amorphous silicon thin film on the film-forming substrate. In the method for producing an amorphous silicon thin film, a first step of depositing a hydrogenated amorphous silicon thin film by heating and holding the film-forming substrate at 150 to 300° C., and thermally decomposing the source gas, Hydrogenation, characterized in that a second step of exposing the film-forming substrate to atomic hydrogen and/or atomic deuterium produced by a means other than the thermal decomposition of the source gas is repeated alternately. A method for producing an amorphous silicon thin film.
る堆積層の厚みが10〜60Åであり、前記第2の工程
1回において堆積される堆積層の厚みが20Å未満であ
ることを特徴とする、請求項1に記載の水素化非晶質シ
リコン薄膜の製造方法。2. The thickness of the deposited layer deposited in the first step is 10 to 60 Å, and the thickness of the deposited layer deposited in the second step is less than 20 Å. The method for producing a hydrogenated amorphous silicon thin film according to claim 1.
水素の生成を、分子状水素ガス及び/または分子状重水
素ガスをグロー放電分解することにより行うことを特徴
とする、請求項1または請求項2に記載の水素化非晶質
シリコン薄膜の製造方法。3. The method according to claim 1, wherein the atomic hydrogen and/or atomic deuterium is generated by glow discharge decomposition of molecular hydrogen gas and/or molecular deuterium gas. The method for producing a hydrogenated amorphous silicon thin film according to claim 2.
水素の生成を、分子状水素ガス及び/または分子状重水
素ガスを前記原料ガスの熱分解温度より更に高い温度で
熱分解することにより行うことを特徴とする、請求項1
または請求項2に記載の水素化非晶質シリコン薄膜の製
造方法。4. The atomic hydrogen and/or atomic deuterium is produced by thermally decomposing molecular hydrogen gas and/or molecular deuterium gas at a temperature higher than the thermal decomposition temperature of the raw material gas. Claim 1, characterized in that
Or the method for producing a hydrogenated amorphous silicon thin film according to claim 2.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP3140679A JPH04342120A (en) | 1991-05-17 | 1991-05-17 | Manufacture of hydrogenated amorphous silicon thin film |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP3140679A JPH04342120A (en) | 1991-05-17 | 1991-05-17 | Manufacture of hydrogenated amorphous silicon thin film |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH04342120A true JPH04342120A (en) | 1992-11-27 |
Family
ID=15274236
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP3140679A Pending JPH04342120A (en) | 1991-05-17 | 1991-05-17 | Manufacture of hydrogenated amorphous silicon thin film |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH04342120A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH06283430A (en) * | 1993-01-28 | 1994-10-07 | Applied Materials Inc | Method for execution of multilayer cvd at inside of single chamber |
JPH06291044A (en) * | 1993-01-28 | 1994-10-18 | Applied Materials Inc | Method for depositing amorphous silicon thin film on glass substrate of large area by CVD at high deposition rate |
JP2008135556A (en) * | 2006-11-28 | 2008-06-12 | Sanyo Electric Co Ltd | P-type amorphous silicon thin film, photovoltaic device, and manufacturing method for them |
-
1991
- 1991-05-17 JP JP3140679A patent/JPH04342120A/en active Pending
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH06283430A (en) * | 1993-01-28 | 1994-10-07 | Applied Materials Inc | Method for execution of multilayer cvd at inside of single chamber |
JPH06291044A (en) * | 1993-01-28 | 1994-10-18 | Applied Materials Inc | Method for depositing amorphous silicon thin film on glass substrate of large area by CVD at high deposition rate |
US6444277B1 (en) | 1993-01-28 | 2002-09-03 | Applied Materials, Inc. | Method for depositing amorphous silicon thin films onto large area glass substrates by chemical vapor deposition at high deposition rates |
JP2008135556A (en) * | 2006-11-28 | 2008-06-12 | Sanyo Electric Co Ltd | P-type amorphous silicon thin film, photovoltaic device, and manufacturing method for them |
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