JPH11322491A - Production of silicon single crystal wafer and silicon single crystal wafer - Google Patents
Production of silicon single crystal wafer and silicon single crystal waferInfo
- Publication number
- JPH11322491A JPH11322491A JP11050396A JP5039699A JPH11322491A JP H11322491 A JPH11322491 A JP H11322491A JP 11050396 A JP11050396 A JP 11050396A JP 5039699 A JP5039699 A JP 5039699A JP H11322491 A JPH11322491 A JP H11322491A
- Authority
- JP
- Japan
- Prior art keywords
- single crystal
- silicon single
- wafer
- nitrogen
- crystal wafer
- 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.)
- Granted
Links
- 239000013078 crystal Substances 0.000 title claims abstract description 173
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 105
- 239000010703 silicon Substances 0.000 title claims abstract description 105
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 104
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 19
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 155
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 77
- 230000007547 defect Effects 0.000 claims abstract description 60
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 59
- 239000001301 oxygen Substances 0.000 claims abstract description 59
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 59
- 238000000034 method Methods 0.000 claims abstract description 58
- 238000010438 heat treatment Methods 0.000 claims abstract description 53
- 239000002344 surface layer Substances 0.000 claims abstract description 21
- 125000004429 atom Chemical group 0.000 claims description 17
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 16
- 229910052786 argon Inorganic materials 0.000 claims description 8
- 239000001257 hydrogen Substances 0.000 claims description 7
- 229910052739 hydrogen Inorganic materials 0.000 claims description 7
- 230000008018 melting Effects 0.000 claims description 7
- 238000002844 melting Methods 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 6
- 125000004435 hydrogen atom Chemical class [H]* 0.000 claims 2
- 235000012431 wafers Nutrition 0.000 abstract description 97
- 230000000694 effects Effects 0.000 abstract description 26
- 238000001556 precipitation Methods 0.000 abstract description 11
- 230000001737 promoting effect Effects 0.000 abstract description 5
- 238000005247 gettering Methods 0.000 abstract description 3
- 230000002401 inhibitory effect Effects 0.000 abstract 1
- 239000002244 precipitate Substances 0.000 description 10
- 230000015572 biosynthetic process Effects 0.000 description 8
- 239000007789 gas Substances 0.000 description 7
- 238000007796 conventional method Methods 0.000 description 6
- 238000005530 etching Methods 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- 238000005259 measurement Methods 0.000 description 5
- 230000015556 catabolic process Effects 0.000 description 4
- 150000002431 hydrogen Chemical class 0.000 description 4
- 239000010453 quartz Substances 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 238000004220 aggregation Methods 0.000 description 3
- 230000002776 aggregation Effects 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 230000002950 deficient Effects 0.000 description 3
- 239000010410 layer Substances 0.000 description 3
- 150000004767 nitrides Chemical class 0.000 description 3
- 230000006911 nucleation Effects 0.000 description 3
- 238000010899 nucleation Methods 0.000 description 3
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 101100001673 Emericella variicolor andH gene Proteins 0.000 description 1
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 125000004433 nitrogen atom Chemical group N* 0.000 description 1
- 231100000989 no adverse effect Toxicity 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 229920005591 polysilicon Polymers 0.000 description 1
- 230000007261 regionalization Effects 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 150000003376 silicon Chemical class 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Crystals, And After-Treatments Of Crystals (AREA)
- Mechanical Treatment Of Semiconductor (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、チョクラルスキー
法（以下、ＣＺ法という）によってシリコン単結晶を引
上げる際に、窒素をドープして結晶内部に存在するグロ
ーンイン（Ｇｒｏｗｎ−ｉｎ）欠陥と呼ばれる結晶欠陥
のサイズを小さくするとともに、熱処理を加えることに
よってゲッタリング能力に優れたシリコン単結晶ウエー
ハを高生産性で製造する方法、およびこの方法で製造さ
れたシリコン単結晶ウエーハに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the growth of a silicon single crystal by the Czochralski method (hereinafter referred to as the CZ method) when a silicon single crystal is grown. The present invention relates to a method for producing a silicon single crystal wafer having excellent gettering ability by reducing the size of a so-called crystal defect and performing heat treatment with high productivity, and a silicon single crystal wafer produced by this method.
【０００２】[0002]
【従来の技術】半導体集積回路等のデバイスを作製する
ためのウエーハとしては、主にチョクラルスキー法（Ｃ
Ｚ法）によって育成された、シリコン単結晶ウエーハが
用いられている。このようなシリコン単結晶ウエーハに
結晶欠陥が存在すると、半導体デバイス作製時にパター
ン不良などを引き起こしてしまう。特に、近年の高度に
集積化されたデバイスにおけるパターン幅は、０．３５
ミクロン以下といった非常に微細となっているため、こ
のようなパターン形成時には、０．１ミクロンサイズの
結晶欠陥の存在でもパターン不良等の原因になり、デバ
イスの生産歩留あるいは品質特性を著しく低下させてし
まう。従って、シリコン単結晶ウエーハに存在する結晶
欠陥は極力減少させなければならない。2. Description of the Related Art Wafers for manufacturing devices such as semiconductor integrated circuits are mainly manufactured by the Czochralski method (C
A silicon single crystal wafer grown by the Z method is used. If a crystal defect exists in such a silicon single crystal wafer, a pattern defect or the like is caused at the time of manufacturing a semiconductor device. In particular, the pattern width in recent highly integrated devices is 0.35
In such a pattern formation, the presence of a crystal defect of a size of 0.1 micron may cause a pattern defect or the like at the time of forming such a pattern. Would. Therefore, crystal defects existing in the silicon single crystal wafer must be reduced as much as possible.
【０００３】特に最近になって、ＣＺ法により育成され
たシリコン単結晶中には、上記グローンイン欠陥と呼ば
れる、結晶成長中に導入された結晶欠陥がさまざまな測
定法で見いだされることが報告されている。例えば、こ
れらの結晶欠陥は商業レベルで生産されている一般的な
成長速度（例えば、約１ｍｍ／ｍｉｎ以上）で引き上げ
られた単結晶では、Ｓｅｃｃｏ液（Ｋ2 Ｃｒ2 Ｏ7 と弗
酸と水の混合液）で表面を選択的にエッチング（Ｓｅｃ
ｃｏエッチング）することによりピットとして検出が可
能である（特開平４−１９２３４５号公報参照）。In recent years, it has recently been reported that in a silicon single crystal grown by the CZ method, crystal defects introduced during crystal growth, referred to as the above-mentioned grown-in defects, are found by various measuring methods. I have. For example, in the case of a single crystal pulled at a general growth rate (for example, about 1 mm / min or more) produced at a commercial level, these crystal defects are formed in a Secco solution (K 2 Cr 2 O 7 , hydrofluoric acid and water). Selectively etch the surface with a mixture of
The pits can be detected by co-etching (see Japanese Patent Application Laid-Open No. 4-192345).
【０００４】このピットの主な発生原因は、単結晶製造
中に凝集する原子空孔のクラスタあるいは石英ルツボか
ら混入する酸素原子の凝集体である酸素析出物であると
考えられている。これらの結晶欠陥はデバイスが形成さ
れるウエーハの表層部（０〜５ミクロン）に存在する
と、デバイス特性を劣化させる有害な欠陥となるので、
このような結晶欠陥を低減するための種々の方法が検討
されている。It is considered that the main cause of the formation of pits is a cluster of atomic vacancies that aggregate during the production of a single crystal or an oxygen precipitate that is an aggregate of oxygen atoms mixed in from a quartz crucible. If these crystal defects are present in the surface layer (0 to 5 microns) of the wafer on which the device is formed, they become harmful defects that degrade the device characteristics.
Various methods for reducing such crystal defects have been studied.
【０００５】例えば、上記原子空孔のクラスタの密度を
低減するためには、結晶成長速度を極端に低下（例え
ば、０．４ｍｍ／ｍｉｎ以下）して結晶を育成させれば
よいことが知られている（特開平２−２６７１９５号公
報参照）。ところが、この方法であると、新たに過剰な
格子間シリコンが集まって形成する転位ループと考えら
れる結晶欠陥が発生し、デバイス特性を著しく劣化さ
せ、問題の解決とはならないことがわかってきた。しか
も、結晶成長速度を従来の約１．０ｍｍ／ｍｉｎ以上か
ら、０．４ｍｍ／ｍｉｎ以下に低下させるのであるか
ら、著しい単結晶の生産性の低下、コストの上昇をもた
らしてしまう。[0005] For example, it is known that the density of the clusters of atomic vacancies can be reduced by growing the crystal at an extremely low crystal growth rate (for example, 0.4 mm / min or less). (See Japanese Patent Application Laid-Open No. 2-267195). However, it has been found that this method causes crystal defects which are considered to be dislocation loops formed by newly gathering excess interstitial silicon, significantly degrades device characteristics, and does not solve the problem. In addition, since the crystal growth rate is reduced from about 1.0 mm / min or more to 0.4 mm / min or less, the productivity of single crystals is significantly reduced and the cost is increased.
【０００６】一方、ウエーハ表層部の酸素析出物に起因
する結晶欠陥を低減するために、結晶中の初期酸素濃度
を低くして結晶を育成させる方法がある。しかし、この
方法では、デバイスを形成する表層部のみならず、ウエ
ーハのバルク中の酸素濃度、酸素析出量も低下してしま
う。ウエーハバルク中の酸素析出量が減少してしまう
と、デバイス工程において有害な重金属等の不純物を捕
捉する、いわゆるイントリンシックゲッタリング効果
（ＩＧ効果）が得られなくなって、結果的にデバイス製
造歩留を悪化させてしまう。On the other hand, in order to reduce crystal defects caused by oxygen precipitates on the wafer surface layer, there is a method of growing the crystal by lowering the initial oxygen concentration in the crystal. However, according to this method, not only the surface layer portion forming the device, but also the oxygen concentration and the amount of precipitated oxygen in the bulk of the wafer are reduced. If the amount of oxygen precipitated in the wafer bulk decreases, a so-called intrinsic gettering effect (IG effect) for capturing harmful impurities such as heavy metals in the device process cannot be obtained, resulting in a device manufacturing yield. Worsens.
【０００７】[0007]
【発明が解決しようとする課題】本発明はこのような問
題点に鑑みて為されたもので、ＣＺ法によって作製され
るシリコン単結晶ウエーハにおける、結晶欠陥（グロー
ンイン欠陥）の成長を抑制し、特にウエーハの表面層で
の結晶欠陥を低減すると共に、ウエーハのバルク部では
酸素の析出を促進することによって、充分なＩＧ効果を
有するシリコン単結晶ウエーハを、高生産性でかつ簡単
に作製する製造方法を提供することを主たる目的とす
る。SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and suppresses the growth of crystal defects (grown-in defects) in a silicon single crystal wafer produced by the CZ method. In particular, by reducing crystal defects in the surface layer of the wafer and promoting the precipitation of oxygen in the bulk part of the wafer, a silicon single crystal wafer having a sufficient IG effect can be manufactured easily and with high productivity. Its primary purpose is to provide a method.
【０００８】[0008]
【課題を解決するための手段】上記課題を解決するた
め、本発明の請求項１に記載した発明は、チョクラルス
キー法によって窒素をドープしたシリコン単結晶棒を育
成し、該単結晶棒をスライスしてシリコン単結晶ウエー
ハに加工した後、該シリコン単結晶ウエーハに熱処理を
加えてウエーハ表面の窒素を外方拡散させることを特徴
とするシリコン単結晶ウエーハの製造方法である。In order to solve the above-mentioned problems, the invention described in claim 1 of the present invention grows a silicon single crystal rod doped with nitrogen by the Czochralski method, A method for producing a silicon single crystal wafer, comprising slicing and processing into a silicon single crystal wafer, and then subjecting the silicon single crystal wafer to heat treatment to diffuse nitrogen on the wafer surface outward.
【０００９】このように、ＣＺ法によって単結晶棒を育
成する際に、窒素をドープすることによって、前記結晶
成長中に導入される結晶欠陥の成長を抑制することが出
来る。また、結晶欠陥の成長が抑制される結果、結晶成
長速度を高速化することが出来るので、結晶の生産性を
著しく改善することが出来る。As described above, when a single crystal rod is grown by the CZ method, the growth of crystal defects introduced during the crystal growth can be suppressed by doping with nitrogen. In addition, since the growth of crystal defects is suppressed, the crystal growth rate can be increased, so that the productivity of the crystal can be significantly improved.
【００１０】そして、このような窒素をドープしたシリ
コン単結晶から加工されたウエーハに熱処理を加えて、
ウエーハ表面の窒素を外方拡散すれば、ウエーハ表面層
では結晶欠陥がきわめて少ないとともに、窒素も外方拡
散されているため、作製されるデバイスに悪影響を及ぼ
すこともない。また、この熱処理により同時に酸素も外
方拡散されるので、一層表面の欠陥密度を低減すること
が出来る。一方、ウエーハのバルク部では窒素の存在に
より酸素析出が促進されるので、充分にＩＧ効果を有す
るウエーハを製造することが出来る。Then, a heat treatment is applied to the wafer processed from such a nitrogen-doped silicon single crystal,
When nitrogen on the wafer surface is outwardly diffused, crystal defects are extremely small in the wafer surface layer, and nitrogen is also outwardly diffused, so that there is no adverse effect on a device to be manufactured. Further, oxygen is simultaneously diffused outward by this heat treatment, so that the defect density on the surface can be further reduced. On the other hand, in the bulk portion of the wafer, oxygen is promoted by the presence of nitrogen, so that a wafer having a sufficient IG effect can be manufactured.
【００１１】この場合、請求項２に記載したように、チ
ョクラルスキー法によって窒素をドープしたシリコン単
結晶棒を育成する際に、単結晶棒にドープする窒素濃度
を、１×１０10〜５×１０15atoms/cm3 にすることが好
ましい。これは、結晶欠陥の成長を充分に抑制するに
は、１×１０10atoms/cm3 以上にするのが望ましいこと
と、シリコン単結晶の単結晶化の妨げにならないように
するためには、５×１０15atoms/cm3 以下とするのが好
ましいからである。In this case, when growing a silicon single crystal rod doped with nitrogen by the Czochralski method, the concentration of nitrogen doped into the single crystal rod is 1 × 10 10 -5. It is preferably set to × 10 15 atoms / cm 3 . In order to sufficiently suppress the growth of crystal defects, it is desirable that the concentration be 1 × 10 10 atoms / cm 3 or more. In order not to hinder the single crystallization of silicon single crystal, This is because it is preferably set to 5 × 10 15 atoms / cm 3 or less.
【００１２】また、請求項３に記載したように、チョク
ラルスキー法によって窒素をドープしたシリコン単結晶
棒を育成する際に、単結晶棒に含有される酸素濃度を、
１．２×１０18atoms/cm3 （ＡＳＴＭ ’７９値）以下
にするのが好ましい。このように、低酸素とすれば、結
晶欠陥の成長を一層抑制することができるし、表面層で
の酸素析出物の形成を防止することも出来る。一方、バ
ルク部では、窒素の存在により酸素析出が促進されるの
で、低酸素としても十分にＩＧ効果を発揮することが出
来る。Further, as described in claim 3, when growing a silicon single crystal rod doped with nitrogen by the Czochralski method, the concentration of oxygen contained in the single crystal rod is determined as follows:
It is preferable that the concentration be 1.2 × 10 18 atoms / cm 3 (ASTM '79 value) or less. As described above, when the oxygen content is low, the growth of crystal defects can be further suppressed, and the formation of oxygen precipitates on the surface layer can be prevented. On the other hand, in the bulk portion, since oxygen precipitation is promoted by the presence of nitrogen, the IG effect can be sufficiently exhibited even with low oxygen.
【００１３】次に、本発明の請求項４に記載した発明で
は、ウエーハ表面の窒素を外方拡散させる熱処理を、９
００℃〜シリコンの融点以下の温度で行なうようにし
た。このような温度範囲で熱処理をすることによって、
十分にウエーハ表面層の窒素を外方拡散できるととも
に、同時に酸素をも外方拡散させることができる。従っ
て、ウエーハ表面層を極めて低欠陥とすることが出来
る。一方、バルク部においては、熱処理によって酸素析
出物を成長させることができるので、ＩＧ効果を有する
理想的なウエーハとすることができる。Next, in the invention described in claim 4 of the present invention, the heat treatment for outwardly diffusing nitrogen on the wafer surface is performed by 9 heat treatment.
The process was performed at a temperature of from 00 ° C. to the melting point of silicon. By performing heat treatment in such a temperature range,
Not only can nitrogen in the wafer surface layer be sufficiently diffused outward, but also oxygen can be diffused outward. Therefore, the wafer surface layer can have extremely low defects. On the other hand, in the bulk portion, an oxygen precipitate can be grown by heat treatment, so that an ideal wafer having an IG effect can be obtained.
【００１４】また、請求項５に記載したように、ウエー
ハ表面の窒素を外方拡散させる熱処理を、酸素、水素、
アルゴンあるいはこれらの混合雰囲気下で行なうのが好
ましい。このようなガス雰囲気で熱処理をすることによ
って、シリコンウエーハに有害となる表面被膜を形成さ
せることなく、有効に窒素を外方拡散させることができ
る。Further, as described in claim 5, the heat treatment for outwardly diffusing nitrogen on the wafer surface is performed by oxygen, hydrogen,
It is preferable to carry out the reaction under argon or a mixed atmosphere thereof. By performing the heat treatment in such a gas atmosphere, nitrogen can be effectively diffused outward without forming a harmful surface film on the silicon wafer.
【００１５】そして、本発明の製造方法で製造されたシ
リコン単結晶ウエーハ（請求項６）は、例えば、請求項
７のように、チョクラルスキー法により窒素をドープし
て育成されたシリコン単結晶棒をスライスして得たシリ
コン単結晶ウエーハであって、該シリコン単結晶ウエー
ハ表面の窒素が、熱処理により外方拡散されているもの
である。The silicon single crystal wafer (claim 6) manufactured by the manufacturing method of the present invention is, for example, a silicon single crystal wafer grown by doping with nitrogen by the Czochralski method. A silicon single crystal wafer obtained by slicing a rod, wherein nitrogen on the surface of the silicon single crystal wafer is diffused outward by a heat treatment.
【００１６】そして、この場合、請求項８のように、窒
素濃度を、１×１０10〜５×１０15atoms/cm3 とし、請
求項９のように、酸素濃度を、１．２×１０18atoms/cm
3 以下とすることができる。In this case, the nitrogen concentration is set to 1 × 10 10 to 5 × 10 15 atoms / cm 3, and the oxygen concentration is set to 1.2 × 10 18 atoms / cm
3 or less.
【００１７】また、請求項１０のように、窒素を外方拡
散させるために加えられた熱処理が、９００℃〜シリコ
ンの融点以下の温度の熱処理であるものとし、請求項１
１のように、熱処理が、酸素、水素、アルゴンあるいは
これらの混合雰囲気下の熱処理であるものとすることが
できる。The heat treatment applied to diffuse nitrogen outward may be a heat treatment at a temperature from 900 ° C. to the melting point of silicon.
As in 1, the heat treatment may be a heat treatment in an atmosphere of oxygen, hydrogen, argon, or a mixture thereof.
【００１８】このようなシリコン単結晶ウエーハであれ
ば、表面層は結晶欠陥がきわめて少ないものとなり、バ
ルク部では酸素析出により十分にＩＧ効果のあるものと
なる。特に、請求項１２のように、ウエーハ表面層の結
晶欠陥の密度を３０ケ／ｃｍ 2 以下とすることができる
ので、デバイス作製時の歩留を著しく改善出来るものと
なる。In such a silicon single crystal wafer,
If the surface layer has very few crystal defects,
In the luk area, it is assumed that oxygen precipitation has a sufficient IG effect
Become. In particular, as described in claim 12, the bonding of the wafer surface layer is performed.
30 defects / cm Two Can be
Therefore, the yield during device fabrication can be significantly improved.
Become.
【００１９】以下、本発明についてさらに詳述するが、
本発明はこれらに限定されるものではない。本発明は、
ＣＺ法によってシリコン単結晶育成中に窒素をドープす
る技術とシリコン単結晶ウエーハに熱処理を加えてＩＧ
効果を持たせる技術とを組み合わせることによって、デ
バイス形成層（ウエーハ表面層）中の結晶欠陥が少な
く、かつ高いＩＧ効果を有するシリコン単結晶ウエーハ
を、高生産性で得ることが出来ることを見出し、諸条件
を精査して本発明を完成させたものである。Hereinafter, the present invention will be described in more detail.
The present invention is not limited to these. The present invention
Technology of doping nitrogen during silicon single crystal growth by CZ method and heat treatment applied to silicon single crystal wafer for IG
It has been found that a silicon single crystal wafer having few crystal defects in a device forming layer (wafer surface layer) and having a high IG effect can be obtained with high productivity by combining the technique with the effect. The present invention has been completed by examining various conditions.
【００２０】すなわち、窒素をシリコン単結晶中にドー
プすると、シリコン中の原子空孔の凝集が抑制され、結
晶欠陥サイズが縮小することが指摘されている（T.Abe
andH.Takeno,Mat.Res.Soc.Symp.Proc.Vol.262,3,1992
）。この効果は原子空孔の凝集過程が、均一核形成か
ら不均一核形成に移行するためであると考えられる。し
たがって、ＣＺ法によりシリコン単結晶を育成する際
に、窒素をドープすれば、結晶欠陥サイズを小さくした
シリコン単結晶およびこれを加工してシリコン単結晶ウ
エーハを得ることが出来る。しかも、この方法によれ
ば、前記従来法のように、結晶成長速度を必ずしも低速
化する必要がないため、高生産性でシリコン単結晶ウエ
ーハを得ることが出来る可能性がある。That is, it has been pointed out that when nitrogen is doped into a silicon single crystal, the aggregation of atomic vacancies in silicon is suppressed and the crystal defect size is reduced (T. Abe).
andH.Takeno, Mat.Res.Soc.Symp.Proc.Vol.262,3,1992
). This effect is considered to be due to the transition of the process of aggregation of atomic vacancies from formation of uniform nuclei to formation of heterogeneous nuclei. Therefore, when nitrogen is doped when growing a silicon single crystal by the CZ method, a silicon single crystal having a reduced crystal defect size and a silicon single crystal wafer can be obtained by processing the same. Moreover, according to this method, unlike the above-described conventional method, it is not always necessary to reduce the crystal growth rate, and thus it is possible to obtain a silicon single crystal wafer with high productivity.
【００２１】ところが、このシリコン単結晶中の窒素原
子は、酸素析出を助長させる効果があることが知られて
おり（例えば、F.Shimura and R.S.Hockett,Appl.Phys.
Lett.48,224,1986）、ＣＺ法によるシリコン単結晶ウエ
ーハ中にドープすると、デバイス工程中の熱処理等で、
デバイス形成層中にＯＳＦ（酸化誘起積層欠陥）等の酸
素析出起因の欠陥を多発させる。したがって、従来窒素
をドープしたＣＺシリコン単結晶ウエーハは、デバイス
作製用のウエーハとしては用いられていなかった。However, it is known that nitrogen atoms in this silicon single crystal have an effect of promoting oxygen precipitation (for example, F. Shimura and RSHockett, Appl. Phys.
Lett. 48, 224, 1986), when doped into a silicon single crystal wafer by the CZ method, heat treatment during the device process, etc.
Defects caused by oxygen precipitation, such as OSF (oxidation-induced stacking fault), occur frequently in the device formation layer. Therefore, conventionally, a CZ silicon single crystal wafer doped with nitrogen has not been used as a wafer for device fabrication.
【００２２】そこで、本発明では、窒素ドープ結晶では
結晶欠陥（グローンイン欠陥）が成長しにくいと言う利
点を生かすこととし、一方酸素析出が助長されることに
起因して発生する欠陥は、ウエーハに熱処理を加えて、
窒素および酸素を外方拡散させることによって、ウエー
ハ表面においてきわめて結晶欠陥の少ないシリコン単結
晶ウエーハを得ることに成功した。また、ウエーハのバ
ルク部には窒素が含有されているため、酸素の析出が促
進される結果、窒素の入っていない通常のウエーハの同
じ酸素濃度のものよりも析出物が多くＩＧ効果が強いも
のとなる。したがって、含有酸素濃度を低減することが
でき、一層表面における結晶欠陥の発生を抑制すること
が出来る。しかも、ＣＺ法において結晶引上げ速度を低
下させる必要がないため高生産性であるという利点もあ
る。Therefore, the present invention takes advantage of the fact that crystal defects (grown-in defects) are unlikely to grow in nitrogen-doped crystals, while defects generated due to the promotion of oxygen precipitation are limited to wafers. Heat treatment,
By diffusing nitrogen and oxygen outward, a silicon single crystal wafer with very few crystal defects on the wafer surface was successfully obtained. In addition, since nitrogen is contained in the bulk portion of the wafer, the precipitation of oxygen is promoted, and as a result, the amount of precipitates is larger than that of a normal wafer having no nitrogen and having the same IG effect, and the IG effect is stronger. Becomes Therefore, the concentration of oxygen contained can be reduced, and the generation of crystal defects on the surface can be further suppressed. In addition, there is an advantage that the productivity is high because there is no need to lower the crystal pulling speed in the CZ method.
【００２３】[0023]
【発明の実施の形態】本発明において、ＣＺ法によって
窒素をドープしたシリコン単結晶棒を育成するには、例
えば特開昭６０−２５１１９０号に記載されているよう
な公知の方法によれば良い。DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a silicon single crystal rod doped with nitrogen by the CZ method may be grown by a known method described in, for example, Japanese Patent Application Laid-Open No. 60-251190. .
【００２４】すなわち、ＣＺ法は、石英ルツボ中に収容
された多結晶シリコン原料の融液に種結晶を接触させ、
これを回転させながらゆっくりと引き上げて所望直径の
シリコン単結晶棒を育成する方法であるが、あらかじめ
石英ルツボ内に窒化物を入れておくか、シリコン融液中
に窒化物を投入するか、雰囲気ガスを窒素を含む雰囲気
等とすることによって、引き上げ結晶中に窒素をドープ
することができる。この際、窒化物の量あるいは窒素ガ
スの濃度あるいは導入時間等を調整することによって、
結晶中のドープ量を制御することが出来る。That is, according to the CZ method, a seed crystal is brought into contact with a melt of a polycrystalline silicon raw material contained in a quartz crucible,
This is a method of growing a silicon single crystal rod of a desired diameter by slowly pulling it up while rotating it. The nitride is put in a quartz crucible in advance, the nitride is put into a silicon melt, or the atmosphere is By setting the gas to an atmosphere containing nitrogen, nitrogen can be doped into the pulled crystal. At this time, by adjusting the amount of nitride, the concentration of nitrogen gas, the introduction time, etc.,
The doping amount in the crystal can be controlled.
【００２５】このように、ＣＺ法によって単結晶棒を育
成する際に、窒素をドープすることによって、結晶成長
中に導入される結晶欠陥の成長を抑制することが出来
る。また、従来法のように、結晶欠陥の成長を抑制する
ために、結晶成長速度を例えば、０．４ｍｍ／ｍｉｎ以
下といった低速化する必要がないので、結晶の生産性を
著しく改善することが出来る。As described above, when a single crystal rod is grown by the CZ method, the growth of crystal defects introduced during crystal growth can be suppressed by doping with nitrogen. Further, unlike the conventional method, it is not necessary to reduce the crystal growth rate to, for example, 0.4 mm / min or less in order to suppress the growth of crystal defects, so that crystal productivity can be significantly improved. .
【００２６】窒素をシリコン単結晶中にドープすると、
シリコン中に導入される結晶欠陥の成長が抑制される理
由は、前述の通り原子空孔の凝集過程が、均一核形成か
ら不均一核形成に移行するためであると考えられる。従
って、ドープする窒素の濃度は、十分に不均一核形成を
引き起こす、１×１０10atoms/cm3 以上にするのが好ま
しく、より好ましくは５×１０13atoms/cm3以上とする
のがよい。これによって結晶欠陥の成長を充分に抑制す
ることができる。一方、窒素濃度が、シリコン単結晶中
の固溶限界である５×１０15atoms/cm3を越えると、シ
リコン単結晶の単結晶化そのものが阻害されるので、こ
の濃度を越えないようにする。When nitrogen is doped into a silicon single crystal,
It is considered that the reason why the growth of crystal defects introduced into silicon is suppressed is that the aggregation process of atomic vacancies shifts from uniform nucleation to heterogeneous nucleation as described above. Therefore, the concentration of nitrogen to be doped is preferably set to 1 × 10 10 atoms / cm 3 or more, which causes sufficient heterogeneous nucleation, and more preferably 5 × 10 13 atoms / cm 3 or more. . Thereby, the growth of crystal defects can be sufficiently suppressed. On the other hand, if the nitrogen concentration exceeds the solid solution limit of 5 × 10 15 atoms / cm 3 in the silicon single crystal, the single crystallization of the silicon single crystal itself is hindered. .
【００２７】また、本発明では、ＣＺ法によって窒素を
ドープしたシリコン単結晶棒を育成する際に、単結晶棒
に含有される酸素濃度を、１．２×１０18atoms/cm3 以
下にするのが好ましい。シリコン単結晶中の酸素濃度
を、このように低酸素とすれば、窒素が含有されている
こととも相まって、結晶欠陥の成長を一層抑制すること
ができるし、前記ＯＳＦの形成等も抑制出来るからであ
る。In the present invention, when growing a silicon single crystal rod doped with nitrogen by the CZ method, the concentration of oxygen contained in the single crystal rod is set to 1.2 × 10 18 atoms / cm 3 or less. Is preferred. When the oxygen concentration in the silicon single crystal is set to such low oxygen, the growth of crystal defects can be further suppressed, and the formation of the OSF can be suppressed, in combination with the fact that nitrogen is contained. It is.
【００２８】シリコン単結晶棒を育成する際に、含有さ
れる酸素濃度を上記範囲に低下させる方法は、従来から
慣用されている方法によれば良い。例えば、ルツボ回転
数の減少、導入ガス流量の増加、雰囲気圧力の低下、シ
リコン融液の温度分布および対流の調整等の手段によっ
て、簡単に上記酸素濃度範囲とすることが出来る。When growing a silicon single crystal rod, the concentration of oxygen contained therein may be reduced to the above range by a conventionally used method. For example, the above oxygen concentration range can be easily set by means such as a decrease in the number of rotations of the crucible, an increase in the flow rate of the introduced gas, a decrease in the atmospheric pressure, and a control of the temperature distribution and convection of the silicon melt.
【００２９】こうして、ＣＺ法において所望濃度の窒素
がドープされ、所望濃度の酸素を含有する、シリコン単
結晶棒が得られる。これを通常の方法にしたがい、内周
刃スライサあるいはワイヤソー等の切断装置でスライス
した後、面取り、ラッピング、エッチング、研磨等の工
程を経てシリコン単結晶ウエーハに加工する。もちろ
ん、これらの工程は例示列挙したにとどまり、この他に
も洗浄等種々の工程があり得るし、工程順の変更、一部
省略等目的に応じ適宜工程は変更使用されている。In this manner, a silicon single crystal rod doped with a desired concentration of nitrogen in the CZ method and containing a desired concentration of oxygen is obtained. This is sliced by a cutting device such as an inner peripheral blade slicer or a wire saw according to a usual method, and then processed into a silicon single crystal wafer through processes such as chamfering, lapping, etching, and polishing. Needless to say, these steps are merely listed as examples, and there may be various other steps such as washing, and the steps are appropriately changed and used according to the purpose, such as a change in the order of the steps or a partial omission.
【００３０】次に、得られたシリコン単結晶ウエーハに
熱処理を加えてウエーハ表面の窒素を外方拡散させる。
ウエーハ表面の窒素を外方拡散するのは、窒素の酸素析
出促進効果により、ウエーハ表面層のデバイスを形成す
る領域で酸素が析出し、これに基づく欠陥の形成によ
り、形成されるデバイスに悪影響を及ぼすことを防止す
るためである。そして、窒素の結晶育成中の結晶欠陥の
成長抑制効果とも相まって、ウエーハ表面層を著しく低
欠陥化することが出来る。Next, a heat treatment is applied to the obtained silicon single crystal wafer to diffuse nitrogen on the wafer surface outward.
The outward diffusion of nitrogen on the wafer surface is because oxygen precipitates in the region of the wafer surface layer where the device is formed due to the effect of promoting the oxygen precipitation of nitrogen, and the formation of defects based on this causes an adverse effect on the formed device. This is to prevent the influence. In combination with the effect of suppressing the growth of crystal defects during the growth of nitrogen crystals, the wafer surface layer can be significantly reduced in defects.
【００３１】この場合、窒素のシリコン中での拡散速度
は、酸素より著しく速いので、熱処理を加えることによ
って、確実に表面の窒素を外方拡散することができる。
ウエーハ表面の窒素を外方拡散させる具体的な熱処理の
条件としては、９００℃〜シリコンの融点以下の温度で
行なうのが好ましい。In this case, since the diffusion rate of nitrogen in silicon is significantly higher than that of oxygen, it is possible to surely diffuse nitrogen on the surface outward by applying a heat treatment.
As a specific heat treatment condition for out-diffusing nitrogen on the wafer surface, the heat treatment is preferably performed at a temperature of 900 ° C. to the melting point of silicon or lower.
【００３２】このような温度範囲で熱処理をすることに
よって、十分にウエーハ表面層の窒素を外方拡散できる
とともに、同時に酸素をも外方拡散させることができる
ので、表面層における酸素析出物に起因する欠陥の発生
をほぼ完全に防止することが出来るからである。一方、
バルク部においては、上記熱処理によって酸素析出物を
成長させることができるので、ＩＧ効果を有するウエー
ハとすることができる。特に、本発明では、バルク部に
おいては、窒素の存在により酸素析出が促進されるの
で、ＩＧ効果の高いものとなり、たとえ低酸素濃度のシ
リコンウエーハであっても十分にＩＧ効果を発揮するこ
とが出来るものとなる。By performing the heat treatment in such a temperature range, nitrogen in the wafer surface layer can be sufficiently diffused outward and oxygen can also be diffused outward at the same time. This is because the occurrence of a defect can be almost completely prevented. on the other hand,
In the bulk portion, an oxygen precipitate can be grown by the heat treatment, so that a wafer having an IG effect can be obtained. In particular, in the present invention, in the bulk portion, oxygen precipitation is promoted by the presence of nitrogen, so that the IG effect is high, and even if the silicon wafer has a low oxygen concentration, the IG effect can be sufficiently exhibited. You can do it.
【００３３】熱処理は、９００℃〜シリコンの融点以下
の温度の熱処理を１段で行なってもよいし、複数段で行
なっても良い。また、他の熱処理と複合して行なっても
良く、例えば上記９００℃〜シリコンの融点以下の高温
熱処理の後に、６５０℃〜８００℃程度の低温熱処理を
加えても良い。これによって、バルク部の酸素析出物を
成長させることが出来、ＩＧ効果がより高いものとする
ことが可能である。The heat treatment may be performed in a single step at a temperature of 900 ° C. to the melting point of silicon or lower, or may be performed in a plurality of steps. The heat treatment may be performed in combination with another heat treatment. For example, a low-temperature heat treatment at about 650 ° C. to 800 ° C. may be added after the high-temperature heat treatment at 900 ° C. to the melting point of silicon or lower. Thereby, the oxygen precipitate in the bulk portion can be grown, and the IG effect can be further enhanced.
【００３４】また、ウエーハ表面の窒素を外方拡散させ
るための熱処理雰囲気を、酸素、水素、アルゴンあるい
はこれらの混合雰囲気下で行なうのが好ましい。このよ
うなガス雰囲気で熱処理をすることによって、シリコン
ウエーハに有害となる表面被膜を形成させることなく、
効率的に窒素を外方拡散させることができる。特に、水
素、アルゴンあるいはこれらの混合雰囲気のような、還
元性の雰囲気で高温熱処理を行なうと、ウエーハ表面の
結晶欠陥が消滅し易いのでより好ましい。Preferably, the heat treatment atmosphere for outwardly diffusing nitrogen on the wafer surface is performed in an atmosphere of oxygen, hydrogen, argon or a mixture of these. By performing heat treatment in such a gas atmosphere, without forming a harmful surface film on the silicon wafer,
It is possible to efficiently diffuse nitrogen outward. In particular, it is more preferable to perform the high-temperature heat treatment in a reducing atmosphere such as an atmosphere of hydrogen, argon, or a mixture thereof because crystal defects on the wafer surface are easily eliminated.
【００３５】こうして、窒素をドープしたＣＺ法による
シリコン単結晶ウエーハであって、該シリコン単結晶ウ
エーハ表面の窒素が、熱処理により外方拡散されている
という本発明のシリコン単結晶ウエーハを得ることが出
来る。このようなシリコン単結晶ウエーハは、表面層で
は結晶欠陥がきわめて少なく、バルク部では十分に酸素
析出物を有し、ＩＧ効果の高いものとなる。特に、ウエ
ーハ表面層の結晶欠陥の密度を３０ケ／ｃｍ2 以下とす
ることができるので、デバイス作製時の歩留を著しく改
善出来るものとなる。Thus, it is possible to obtain a silicon single crystal wafer according to the present invention, wherein the silicon single crystal wafer is a nitrogen-doped CZ method, wherein nitrogen on the surface of the silicon single crystal wafer is outwardly diffused by heat treatment. I can do it. Such a silicon single crystal wafer has extremely few crystal defects in the surface layer, has sufficient oxygen precipitates in the bulk portion, and has a high IG effect. In particular, since the density of crystal defects in the wafer surface layer can be reduced to 30 / cm 2 or less, the yield during device fabrication can be significantly improved.
【００３６】[0036]
【実施例】以下、本発明の実施例および比較例を挙げて
具体的に説明するが、本発明はこれらに限定されるもの
ではない。 （実施例、比較例）ＣＺ法により、直径１８インチの石
英ルツボに、原料多結晶シリコン４０ｋｇをチャージ
し、直径６インチ、Ｐ型、方位＜１００＞の結晶棒を、
通常の引き上げ速度である、０．８〜１．５ｍｍ／ｍｉ
ｎの範囲の種々の速度で１０本引き上げた。そのうち５
本の引き上げでは、原料中にあらかじめ０．１２ｇの窒
化珪素膜を有するシリコンウエーハを投入しておいた
が、残り５本の結晶の引き上げでは窒素をドープしなか
った。また、何れの結晶とも、引き上げ中ルツボ回転を
制御して、単結晶中の酸素濃度が０．９〜１．０×１０
18atoms/cm3 となるようにした。EXAMPLES The present invention will now be described specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. (Example, Comparative Example) A quartz crucible having a diameter of 18 inches was charged with 40 kg of raw material polycrystalline silicon by a CZ method, and a crystal rod having a diameter of 6 inches, a P type, and an orientation of <100> was formed.
0.8 to 1.5 mm / mi, which is the normal lifting speed
Ten were raised at various speeds in the range of n. 5 of them
In pulling the book, a silicon wafer having a 0.12 g silicon nitride film was previously charged in the raw material, but nitrogen was not doped in pulling the remaining five crystals. In addition, the crucible rotation during pulling was controlled for each crystal so that the oxygen concentration in the single crystal was 0.9 to 1.0 × 10
It was adjusted to 18 atoms / cm 3 .
【００３７】窒素をドープした方の結晶棒の尾部の窒素
濃度をＦＴ−ＩＲにより測定したところ、平均で５．０
×１０14atoms/cm3 であった（窒素の偏析係数は非常に
小さいので、結晶棒の直胴部の濃度はこの値以下とな
る。）。また、すべての単結晶棒の酸素濃度をＦＴ−Ｉ
Ｒにより測定したところ、どの結晶もおよそ０．９〜
１．０×１０18atoms/cm3 の酸素濃度となっていること
を確認した。The nitrogen concentration at the tail of the nitrogen-doped crystal rod was measured by FT-IR and found to be 5.0 on average.
× 10 14 atoms / cm 3 (Since the segregation coefficient of nitrogen is very small, the concentration of the straight body portion of the crystal rod is lower than this value.) Further, the oxygen concentration of all the single crystal rods was measured by FT-I
As measured by R, all crystals were approximately 0.9-
It was confirmed that the oxygen concentration was 1.0 × 10 18 atoms / cm 3 .
【００３８】ここで得られた単結晶棒から、ワイヤソー
を用いてウエーハを切り出し、面取り、ラッピング、エ
ッチング、鏡面研磨加工を施して、窒素のドープの有無
以外の条件はほぼ同一とした、２種類の直径６インチの
シリコン単結晶鏡面ウエーハを作製した。A wafer was cut out from the obtained single crystal rod using a wire saw, chamfered, wrapped, etched, and mirror-polished, and the conditions were substantially the same except for the presence or absence of nitrogen doping. A silicon single crystal mirror surface wafer having a diameter of 6 inches was produced.
【００３９】得られたシリコン単結晶ウエーハにＳｅｃ
ｃｏエッチングを施し、表面を顕微鏡観察してピット密
度を測定することによって、表面から深さ５μｍまでの
結晶欠陥（グローンイン欠陥）の密度を測定した。測定
結果を、図１に示した。黒丸が窒素をドープした本発明
方法であり、白丸が窒素をドープしていない従来法であ
る。The obtained silicon single crystal wafer was subjected to Sec.
By performing co-etching and observing the surface with a microscope and measuring the pit density, the density of crystal defects (glow-in defects) from the surface to a depth of 5 μm was measured. The measurement results are shown in FIG. The solid circles indicate the method of the present invention doped with nitrogen, and the open circles indicate the conventional method without nitrogen doping.
【００４０】この結果を見ると、窒素をドープした本発
明方法では、引き上げ速度を１．０ｍｍ／ｍｉｎ以上と
いう、従来と同等以上の速度で引き上げているにもかか
わらず、従来法より結晶欠陥密度が２０分の１程度にま
で減少している。すなわち、窒素をドープすることによ
って、結晶欠陥の成長が抑制され、検出できるほど大き
くなっているものが減少することがわかる。The results show that, in the method of the present invention doped with nitrogen, although the pulling speed is 1.0 mm / min or more, which is equal to or higher than the conventional speed, the crystal defect density is higher than that of the conventional method. Has been reduced to about one-twentieth. In other words, it can be seen that the doping with nitrogen suppresses the growth of crystal defects, and reduces those that are large enough to be detected.
【００４１】次に、上記のウエーハに、１０００℃で１
０時間の熱処理を施し、ウエーハ表面の窒素あるいは酸
素を外方拡散させるとともに、バルク層の酸素を析出さ
せた。なお、雰囲気ガスとしては、１００％酸素ガス雰
囲気、１００％アルゴンガス雰囲気、１００％水素ガス
雰囲気、５０％アルゴンと５０％水素の混合ガス雰囲気
とした。Next, the above-mentioned wafer was added at 1000 ° C. for 1 hour.
A heat treatment for 0 hour was performed to diffuse nitrogen or oxygen outward on the wafer surface and to precipitate oxygen in the bulk layer. The atmosphere gas was a 100% oxygen gas atmosphere, a 100% argon gas atmosphere, a 100% hydrogen gas atmosphere, or a mixed gas atmosphere of 50% argon and 50% hydrogen.
【００４２】熱処理後のウエーハに、Ｓｅｃｃｏエッチ
ングを施し、再び表面を顕微鏡観察してピット密度を測
定することによって、結晶欠陥密度に変化があるかを測
定した。窒素をドープした場合の測定結果を、図１に合
わせてプロットした。The wafer after the heat treatment was subjected to Secco etching, the surface was again observed with a microscope, and the pit density was measured to determine whether there was a change in the crystal defect density. The measurement results in the case of doping with nitrogen are plotted in accordance with FIG.
【００４３】この結果を見ると、窒素をドープしたウエ
ーハ表面層の結晶欠陥は、１０００℃の熱処理によっ
て、約２０ケ／ｃｍ2 以下にまで減少することがわか
る。すなわち、熱処理によって、窒素および酸素が外方
拡散し、ウエーハの表面が無欠陥化されることがわか
る。特に、ウエーハ表面層の結晶欠陥の密度を、確実に
３０ケ／ｃｍ2 以下とすることができる。The results show that the crystal defects of the wafer surface layer doped with nitrogen are reduced to about 20 / cm 2 or less by the heat treatment at 1000 ° C. That is, it is understood that nitrogen and oxygen diffuse outward by the heat treatment, and the surface of the wafer is made defect-free. In particular, the density of crystal defects in the wafer surface layer can be reliably reduced to 30 / cm 2 or less.
【００４４】次に、上記熱処理後のウエーハの酸化膜耐
圧特性（Ｃ−モード）を測定した。酸化膜耐圧特性（Ｃ
−モード）の測定条件は、酸化膜厚：２５ｎｍ、測定電
極：リンドープ・ポリシリコン、電極面積：８ｍｍ2 、
判定電流：１ｍＡ／ｃｍ2とした。一般に、絶縁破壊電
界が８ＭＶ／ｃｍ以上のものが良品と判定される。測定
結果を、図２に示した。Next, the oxide film breakdown voltage characteristics (C-mode) of the wafer after the heat treatment were measured. Oxide film breakdown voltage characteristics (C
The measurement conditions for (mode) were as follows: oxide film thickness: 25 nm, measurement electrode: phosphorus-doped polysilicon, electrode area: 8 mm 2 ,
Judgment current: 1 mA / cm 2 . Generally, those having a dielectric breakdown electric field of 8 MV / cm or more are determined to be good. The measurement results are shown in FIG.
【００４５】本発明の窒素をドープしたシリコン単結晶
ウエーハに熱処理を加えたものは（曲線Ａ〜Ｄ）、いず
れの熱処理雰囲気としても、８ＭＶ／ｃｍ以上の良品の
発生度数が高く、殆どが良品となるのに対し、従来法
（曲線Ｅ）では、８ＭＶ／ｃｍに満たない不良品が、約
７０％も発生することがわかる。The nitrogen-doped silicon single crystal wafers of the present invention subjected to the heat treatment (curves A to D) have a high frequency of non-defective products of 8 MV / cm or more, and almost all non-defective products, in any heat treatment atmosphere. On the other hand, according to the conventional method (curve E), it can be seen that about 70% of defective products are less than 8 MV / cm.
【００４６】さらに、上記熱処理後のウエーハをへき開
し、そのへき開面（ウエーハ断面）をＳｅｃｃｏエッチ
ングをした後、顕微鏡観察することにより、ウエーハの
バルク部における酸素析出物の密度（ピット密度）を測
定した。Further, the wafer after the heat treatment was cleaved, the cleaved surface (wafer cross section) was subjected to Secco etching, and then observed under a microscope to measure the density of oxygen precipitates (pit density) in the bulk portion of the wafer. did.
【００４７】その結果、窒素のドープされていない従来
法のウエーハでは、低酸素であることからピット密度が
５×１０2 〜５×１０3 /cm2程度であるのに対し、本発
明のウエーハでは、１×１０4 /cm2以上のピット密度で
あった。すなわち、本発明方法では、低酸素であるにも
かかわらず十分なＩＧ効果を有するシリコン単結晶ウエ
ーハを作製出来ることがわかった。As a result, the pit density of the conventional wafer not doped with nitrogen is about 5 × 10 2 to 5 × 10 3 / cm 2 due to low oxygen, whereas the wafer of the present invention is not. Had a pit density of 1 × 10 4 / cm 2 or more. That is, it was found that the method of the present invention can produce a silicon single crystal wafer having a sufficient IG effect despite low oxygen.
【００４８】なお、本発明は、上記実施形態に限定され
るものではない。上記実施形態は、例示であり、本発明
の特許請求の範囲に記載された技術的思想と実質的に同
一な構成を有し、同様な作用効果を奏するものは、いか
なるものであっても本発明の技術的範囲に包含される。The present invention is not limited to the above embodiment. The above embodiment is an exemplification, and has substantially the same configuration as the technical idea described in the scope of the claims of the present invention. It is included in the technical scope of the invention.
【００４９】例えば、本発明においてチョクラルスキー
法によって窒素をドープしたシリコン単結晶棒を育成す
るに際しては、融液に磁場が印加されているか否かは問
われないものであり、本発明のチョクラルスキー法には
いわゆる磁場を印加するＭＣＺ法も含まれる。For example, in growing a silicon single crystal rod doped with nitrogen by the Czochralski method in the present invention, it does not matter whether a magnetic field is applied to the melt or not. The Ralski method includes a so-called MCZ method in which a magnetic field is applied.
【００５０】また、上記では、含有酸素濃度を低酸素濃
度とした場合に、より低結晶欠陥とすることができるこ
とを示したが、本発明はこれには限定されず、例え酸素
濃度が１．２〜１．５×１０18atoms/cm3 、あるいはそ
れ以上の高酸素濃度の場合であっても、効果を有するも
のであることは言うまでもない。In the above description, it has been shown that when the oxygen concentration is low, crystal defects can be further reduced. However, the present invention is not limited to this. It goes without saying that even if the oxygen concentration is as high as 2 to 1.5 × 10 18 atoms / cm 3 or higher, the effect is obtained.
【００５１】[0051]
【発明の効果】本発明では、窒素をドープしたシリコン
単結晶ウエーハにＩＧ熱処理を施すことによって、ＣＺ
法によって作製されるシリコン単結晶中の結晶欠陥の形
成を抑制し、ウエーハの表面層での結晶欠陥がきわめて
少ないと共に、ウエーハのバルク部では酸素の析出を促
進することによって充分なＩＧ効果を有するシリコン単
結晶ウエーハを、高生産性でかつ簡単に作製することが
できる。According to the present invention, the IG heat treatment is applied to a nitrogen-doped silicon single crystal wafer to obtain a CZ
Suppresses the formation of crystal defects in the silicon single crystal produced by the method, has very few crystal defects in the surface layer of the wafer, and has a sufficient IG effect by promoting the precipitation of oxygen in the bulk portion of the wafer. A silicon single crystal wafer can be easily manufactured with high productivity.
【図１】実施例、比較例において、Ｓｅｃｃｏエッチン
グ後、表面を顕微鏡観察してピット密度を測定した結果
と熱処理の効果を示す結果図である（黒丸が窒素をドー
プした本発明方法であり、白丸が窒素をドープしていな
い従来法である。）。FIG. 1 is a diagram showing the results of measuring the pit density by observing the surface with a microscope after Secco etching and showing the effect of heat treatment in Examples and Comparative Examples (black circles indicate the method of the present invention in which nitrogen is doped, The white circles indicate the conventional method without nitrogen doping.)
【図２】熱処理後のウエーハの酸化膜耐圧特性（Ｃ−モ
ード）を測定した結果を示す結果図である。FIG. 2 is a result diagram showing a result of measuring an oxide film breakdown voltage characteristic (C-mode) of a wafer after a heat treatment.
Claims (12)
プしたシリコン単結晶棒を育成し、該単結晶棒をスライ
スしてシリコン単結晶ウエーハに加工した後、該シリコ
ン単結晶ウエーハに熱処理を加えてウエーハ表面の窒素
を外方拡散させることを特徴とするシリコン単結晶ウエ
ーハの製造方法。A silicon single crystal rod doped with nitrogen is grown by the Czochralski method, the single crystal rod is sliced and processed into a silicon single crystal wafer, and then the silicon single crystal wafer is subjected to a heat treatment to be processed. A method for producing a silicon single crystal wafer, characterized by outwardly diffusing nitrogen on the surface.
ドープしたシリコン単結晶棒を育成する際に、該単結晶
棒にドープする窒素濃度を、１×１０10〜５×１０15at
oms/cm3 にすることを特徴とする請求項１に記載したシ
リコン単結晶ウエーハの製造方法。2. When growing a silicon single crystal rod doped with nitrogen by the Czochralski method, the concentration of nitrogen doped into the single crystal rod is 1 × 10 10 to 5 × 10 15 at.
2. The method for producing a silicon single crystal wafer according to claim 1, wherein the production rate is oms / cm 3 .
ドープしたシリコン単結晶棒を育成する際に、該単結晶
棒に含有される酸素濃度を、１．２×１０18atoms/cm3
以下にすることを特徴とする請求項１または請求項２に
記載したシリコン単結晶ウエーハの製造方法。3. When growing a silicon single crystal rod doped with nitrogen by the Czochralski method, the concentration of oxygen contained in the single crystal rod is set to 1.2 × 10 18 atoms / cm 3.
3. The method for producing a silicon single crystal wafer according to claim 1, wherein:
る熱処理を、９００℃〜シリコンの融点以下の温度で行
なうことを特徴とする請求項１ないし請求項３のいずれ
か１項に記載のシリコン単結晶ウエーハの製造方法。4. The silicon according to claim 1, wherein the heat treatment for outwardly diffusing nitrogen on the wafer surface is performed at a temperature of 900 ° C. to a melting point of silicon or less. A method for producing a single crystal wafer.
る熱処理を、酸素、水素、アルゴンあるいはこれらの混
合雰囲気下で行なうことを特徴とする請求項１ないし請
求項４のいずれか１項に記載のシリコン単結晶ウエーハ
の製造方法。5. The method according to claim 1, wherein the heat treatment for outwardly diffusing nitrogen on the surface of the wafer is performed in an atmosphere of oxygen, hydrogen, argon, or a mixture thereof. For producing a silicon single crystal wafer.
って製造されたシリコン単結晶ウエーハ。6. A silicon single crystal wafer manufactured by the method according to claim 1.
して育成されたシリコン単結晶棒をスライスして得たシ
リコン単結晶ウエーハであって、該シリコン単結晶ウエ
ーハ表面の窒素が、熱処理により外方拡散されているも
のであることを特徴とするシリコン単結晶ウエーハ。7. A silicon single crystal wafer obtained by slicing a silicon single crystal rod grown by doping with nitrogen by the Czochralski method, wherein nitrogen on the surface of the silicon single crystal wafer is moved outward by heat treatment. A silicon single crystal wafer characterized by being diffused.
が、１×１０10〜５×１０15atoms/cm3 であることを特
徴とする請求項７に記載したシリコン単結晶ウエーハ。8. The silicon single crystal wafer according to claim 7, wherein the nitrogen concentration of the silicon single crystal wafer is 1 × 10 10 to 5 × 10 15 atoms / cm 3 .
が、１．２×１０18atoms/cm3 以下であることを特徴と
する請求項７または請求項８に記載したシリコン単結晶
ウエーハ。9. The silicon single crystal wafer according to claim 7, wherein the oxygen concentration of the silicon single crystal wafer is 1.2 × 10 18 atoms / cm 3 or less.
せるために加えられた熱処理が、９００℃〜シリコンの
融点以下の温度の熱処理であることを特徴とする請求項
７ないし請求項９のいずれか１項に記載のシリコン単結
晶ウエーハ。10. The method according to claim 7, wherein the heat treatment applied to diffuse nitrogen on the wafer surface outward is a heat treatment at a temperature of 900 ° C. to the melting point of silicon or lower. 2. The silicon single crystal wafer according to claim 1.
せるために加えられた熱処理が、酸素、水素、アルゴン
あるいはこれらの混合雰囲気下の熱処理であることを特
徴とする請求項７ないし請求項１０のいずれか１項に記
載のシリコン単結晶ウエーハ。11. A heat treatment applied to diffuse nitrogen out of the wafer surface out of the wafer is a heat treatment in an atmosphere of oxygen, hydrogen, argon or a mixture thereof. The silicon single crystal wafer according to any one of the above.
１項に記載のシリコン単結晶ウエーハであって、ウエー
ハ表面層の結晶欠陥の密度が３０ケ／ｃｍ2 以下である
ことを特徴とするシリコン単結晶ウエーハ。12. The silicon single crystal wafer according to claim 7, wherein a density of crystal defects in a wafer surface layer is 30 / cm 2 or less. Silicon single crystal wafer.
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|---|---|---|---|
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| JP10-74868 | 1998-03-09 | ||
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| JP2001253795A (en) * | 2000-03-09 | 2001-09-18 | Sumitomo Metal Ind Ltd | Silicon epitaxial wafer and manufacturing method thereof |
| JP2001284362A (en) * | 2000-03-31 | 2001-10-12 | Toshiba Ceramics Co Ltd | Silicon wafer manufacturing method |
| JP2001328897A (en) * | 2000-03-16 | 2001-11-27 | Toshiba Ceramics Co Ltd | Silicon wafer and method for manufacturing the same |
| JP2002076005A (en) * | 2000-08-24 | 2002-03-15 | Toshiba Ceramics Co Ltd | Silicon single crystal wafer |
| JP2003068743A (en) * | 2001-08-23 | 2003-03-07 | Shin Etsu Handotai Co Ltd | Epitaxial wafer and method for manufacturing the same |
| JP2003086525A (en) * | 2001-09-12 | 2003-03-20 | Toshiba Ceramics Co Ltd | Jig for heat treatment of silicon wafer and method of manufacturing the same |
| JPWO2003003441A1 (en) * | 2001-06-28 | 2004-10-21 | 信越半導体株式会社 | Method of manufacturing annealed wafer and annealed wafer |
| JP2006093645A (en) * | 2004-08-24 | 2006-04-06 | Toshiba Ceramics Co Ltd | Silicon wafer manufacturing method |
| US7147711B2 (en) | 2000-09-20 | 2006-12-12 | Shin-Etsu Handotai Co., Ltd. | Method of producing silicon wafer and silicon wafer |
| JP4102988B2 (en) * | 2000-06-26 | 2008-06-18 | 信越半導体株式会社 | Method for producing silicon wafer and epitaxial wafer, and epitaxial wafer |
| US7875117B2 (en) | 2004-08-12 | 2011-01-25 | Sumco Techxiv Corporation | Nitrogen doped silicon wafer and manufacturing method thereof |
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| JP2001253795A (en) * | 2000-03-09 | 2001-09-18 | Sumitomo Metal Ind Ltd | Silicon epitaxial wafer and manufacturing method thereof |
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| JP4102988B2 (en) * | 2000-06-26 | 2008-06-18 | 信越半導体株式会社 | Method for producing silicon wafer and epitaxial wafer, and epitaxial wafer |
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| JP2003086525A (en) * | 2001-09-12 | 2003-03-20 | Toshiba Ceramics Co Ltd | Jig for heat treatment of silicon wafer and method of manufacturing the same |
| US7875117B2 (en) | 2004-08-12 | 2011-01-25 | Sumco Techxiv Corporation | Nitrogen doped silicon wafer and manufacturing method thereof |
| JP2006093645A (en) * | 2004-08-24 | 2006-04-06 | Toshiba Ceramics Co Ltd | Silicon wafer manufacturing method |
| US7291220B2 (en) | 2004-08-24 | 2007-11-06 | Covalent Materials Corporation | Process of producing silicon wafer |
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