JPH05121370A - Dry-etching method - Google Patents
Dry-etching methodInfo
- Publication number
- JPH05121370A JPH05121370A JP27939791A JP27939791A JPH05121370A JP H05121370 A JPH05121370 A JP H05121370A JP 27939791 A JP27939791 A JP 27939791A JP 27939791 A JP27939791 A JP 27939791A JP H05121370 A JPH05121370 A JP H05121370A
- Authority
- JP
- Japan
- Prior art keywords
- etching
- gas
- hbr
- flow rate
- oxide film
- 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.)
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Links
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- Drying Of Semiconductors (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明はドライエッチング方法に
関し、特に多結晶シリコンのドライエッチング方法に関
する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry etching method, and more particularly to a dry etching method for polycrystalline silicon.
【０００２】[0002]
【従来の技術】従来、多結晶シリコンのエッチングには
反応性イオンエッチング（以下ＲＩＥと略す）が主に用
いられている。その反応ガスとしては、（１）フロンガ
スでは（ァ）Ｐｅｒｆｌｕｏｒｏｃａｒｂｏｎ（たとえ
ばＣＦ4 などのＣ，Ｆのみ含む化合物），（ィ）Ｈｙｄ
ｒｏ−ｆｌｕｏｒｏｃａｒｂｏｎ（たとえばＣＨＦ3 な
どのＣ，Ｆのみを含む化合物），（ゥ）Ｃｈｌｏｒｏ−
ｆｌｕｏｒｏｃａｒｂｏｎ（たとえばＣＣｌ2 Ｆ2 など
のＣ，Ｃｌ，Ｆのみを含む化合物），（ェ）Ｈｙｄｒｏ
−Ｃｈｌｏｒｏ−ｆｌｕｏｒｏｃａｒｂｏｎ（たとえ
ば、ＣＨＣｌＦ2 などのＣ，Ｈ，Ｃｌ，Ｆからなる化合
物）があり、又（２）ハロンガス（たとえばＣＣｌＢｒ
Ｆ2 などのようにフロンガスの１つ以上のＦがＢｒに置
き換えた化合物の総称）および（３）Ｃｌ2 ガスが用い
られている。2. Description of the Related Art Conventionally, reactive ion etching (hereinafter abbreviated as RIE) is mainly used for etching polycrystalline silicon. As the reaction gas, (1) CFC gas is (a) Perfluorocarbon (for example, a compound containing only C and F such as CF 4 ) and (ii) Hyd.
ro-Fluorocarbon (e.g. C, such as CHF 3, compounds containing only F), (©) Chloro-
Fluorocarbon (for example, a compound containing only C, Cl, F such as CCl 2 F 2 ), (e) Hydro
-Chloro-fluorocarbon (for example, C, such as CHClF 2, H, Cl, compounds consisting of F) may also (2) halon gas (e.g. CClBr
(3) Cl 2 gas is used, which is a general term for compounds in which one or more Fs in a CFC gas are replaced by Br, such as F 2 .
【０００３】一方、半導体装置の配線は近年微細化が進
んでいるため、エッチング技術としてはアンダーカット
の生じない異方性の形状が要求されている。つまり、図
２に示すようにフォトレジスト２４の線幅（パターン
幅）をＬ1 ，エッチング後の多結晶シリコン層の線幅を
Ｌ2 とすると、エッチング変化率Ｌ2 ／Ｌ1 ができるだ
け１に近いことが要求されている。On the other hand, since the wiring of a semiconductor device has been miniaturized in recent years, an anisotropic shape that does not cause undercut is required as an etching technique. That is, as shown in FIG. 2, assuming that the line width (pattern width) of the photoresist 24 is L 1 and the line width of the polycrystalline silicon layer after etching is L 2 , the etching change rate L 2 / L 1 is 1 as much as possible. It is required to be close.
【０００４】さらに、半導体装置の絶縁膜は薄膜化の傾
向が進んでいるため、多結晶シリコンのエッチングとし
ては下地であるシリコン酸化膜２２との選択比か高いこ
とが要求される。Further, since the insulating film of a semiconductor device is becoming thinner, it is required to have a high selectivity with respect to the underlying silicon oxide film 22 for etching polycrystalline silicon.
【０００５】[0005]
【発明が解決しようとする課題】上述した従来の多結晶
シリコンエッチング用ガスのうち、（１）フロンガスの
（ァ）Ｐｅｒｆｌｕｏｒｏｃａｒｂｏｎは化学反応によ
るエッチングが主であるため、サイドエッチングが生じ
るという問題点がある。また、（ァ）Ｐｅｒｆｌｕｏｒ
ｏｃａｒｂｏｎ及び（ィ）Ｈｙｄｏｒ−ｆｌｕｏｒｏｃ
ａｒｂｏｎは酸化膜をエッチングするため、酸化膜との
選択比が低くなる。Among the conventional polycrystalline silicon etching gases described above, (1) the CFC gas (a) Perfluorocarbon is mainly etched by a chemical reaction, so that there is a problem that side etching occurs. is there. Also, (a) Perfluor
ocarbon and (i) Hydor-fluoroc
Since arbon etches the oxide film, its selectivity with respect to the oxide film becomes low.
【０００６】また、（１）フロンガスの（ゥ）Ｃｈｌｏ
ｒｏ−ｆｌｕｏｒｏｃａｒｂｏｎ，（ェ）Ｈｙｄｒｏ−
Ｃｈｌｏｒｏ−ｆｌｕｏｒｏｃａｒｂｏｎ及び（２）の
ハロンガスは、エッチング形状は良好であるが、酸化膜
との選択比は２０しかない。さらに、成層圏にあるオゾ
ン層を破壊するという環境破壊の問題を有している。In addition, (1) Freon gas (u) Chlo
ro-fluorocarbon, (e) Hydro-
Chloro-fluorocarbon and the halon gas of (2) have good etching shapes, but have a selection ratio of only 20 with an oxide film. In addition, there is a problem of environmental destruction that destroys the ozone layer in the stratosphere.
【０００７】次に、（３）Ｃｌ2 ガス単体の場合は、ア
ンダーカットが生じるという問題点がある。低圧でエッ
チングした場合、アンダーカットは生じないが、フォト
レジストや酸化膜との選択比が低下する。つまり、形状
と選択比がトレードオフの関係にあり、Ｃｌ2 ガス単体
では、両者の両立は困難であるという問題がある。Next, in the case of (3) Cl 2 gas alone, there is a problem that undercut occurs. When etching is performed at a low pressure, undercut does not occur, but the selection ratio with respect to the photoresist and oxide film decreases. That is, there is a trade-off relationship between the shape and the selection ratio, and there is a problem that it is difficult to satisfy both of them by using only Cl 2 gas.
【０００８】本発明の目的は、多結晶シリコン膜のエッ
チングにおいて、フォトレジストの下にアンダーカット
が生じず、さらにシリコン酸化膜との選択比が高いドラ
イエッチング方法を提供することにある。An object of the present invention is to provide a dry etching method which does not cause an undercut under a photoresist in etching a polycrystalline silicon film and has a high selection ratio with a silicon oxide film.
【０００９】[0009]
【課題を解決するための手段】本発明のドライエッチン
グ方法は、エッチング用ガスとしてＣｌ2 ，ＨＢｒ及び
Ｎ2 の混合ガスまたはＣｌ2 ，ＨＢｒ，Ｎ2 及びＨｅの
混合ガスを用いる。In the dry etching method of the present invention, a mixed gas of Cl 2 , HBr and N 2 or a mixed gas of Cl 2 , HBr, N 2 and He is used as an etching gas.
【００１０】[0010]
【実施例】次に本発明について図面を参照して説明す
る。図１は本発明の一実施例によるエッチング方法を適
用して得たエッチング形状の断面図である。シコン基板
１１上にシリコン酸化膜１２を形成し、その上に被エッ
チング物である多結晶シリコン層１３を成長する。その
後、リソグラフィー技術を用いてフォトレジスト１４を
形成する。The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an etching shape obtained by applying an etching method according to an embodiment of the present invention. A silicon oxide film 12 is formed on a silicon substrate 11, and a polycrystalline silicon layer 13, which is an object to be etched, is grown on the silicon oxide film 12. Then, the photoresist 14 is formed by using the lithography technique.
【００１１】次に多結晶シリコン層１３をＨＢｒ，Ｃｌ
2 及びＮ2 ガスを含む混合ガスを用いてＲＩＥでエッチ
ングを行って図１を得る。今回行なったエッチング条件
は、圧力８Ｐａ，ＲＦパワー７００Ｗ，ＨＢｒ流量６０
ｓｃｃｍ，Ｃｌ2 流量４０ｓｃｃｍ，Ｎ2 流量４０ｓｃ
ｃｍである。Next, the polycrystalline silicon layer 13 is formed into HBr, Cl.
1 is obtained by etching by RIE using a mixed gas containing 2 and N 2 gas. The etching conditions used this time are pressure 8 Pa, RF power 700 W, and HBr flow rate 60.
sccm, Cl 2 flow rate 40 sccm, N 2 flow rate 40 sc
cm.
【００１２】ここで、ＨＢｒ流量とＣｌ2 流量の比（つ
まり、ＨＢｒ流量／Ｃｌ2 流量）は１／４以上が望し
い。フォトレジストの線幅をＬ1 ，エッチング後の線幅
をＬ2 とすると、エッチング時の寸法変化率Ｌ2 ／Ｌ1
は図３に示すように、ＢＨｒ流量が増すにつれて増大
し、ガス比が１／４以下になると、アンダーカットが大
きいことがわかる。Here, the ratio of the HBr flow rate to the Cl 2 flow rate (that is, the HBr flow rate / Cl 2 flow rate) is desired to be ¼ or more. When the line width of the photoresist is L 1 and the line width after etching is L 2 , the dimensional change rate during etching is L 2 / L 1
As shown in FIG. 3, it can be seen that the BHr flow rate increases as the BHr flow rate increases, and the undercut is large when the gas ratio becomes ¼ or less.
【００１３】また、図４が示すように、Ｎ2 流量を増加
すると酸化膜との選択比が向上する。Further, as shown in FIG. 4, when the N 2 flow rate is increased, the selectivity with respect to the oxide film is improved.
【００１４】第２の実施例としては、多結晶シリコン層
をエッチングするガスとして、ＨＢｒ，Ｃｌ2 ，Ｎ2 及
びＨｅガスを用いる。今回のエッチング条件は、圧力８
Ｐａ，ＲＦパワー７００Ｗ，ＨＢｒ流量６０ｓｃｃｍ，
Ｃｌ2 流量４０ｓｃｃｍ，Ｎ2 流量４０ｓｃｃｍ，Ｈｅ
流量４０ｓｃｃｍである。In the second embodiment, HBr, Cl 2 , N 2 and He gases are used as a gas for etching the polycrystalline silicon layer. This etching condition is pressure 8
Pa, RF power 700 W, HBr flow rate 60 sccm,
Cl 2 flow rate 40 sccm, N 2 flow rate 40 sccm, He
The flow rate is 40 sccm.
【００１５】多結晶シリコンのエッチングレートのウェ
ハー面内均一性とＨｅ流量の関係は図５に示されてい
る。ここでエッチングレートの最大値，最小値，平均値
をそれぞれＲMAX ，ＲMin ，Ｒとおくと、上記均一性は
（ＲMAX −ＲMin ）／２・Ｒと定義した。図５からわか
るように、Ｈｅガスを添加することによって実施例１と
比べて上記均一性が向上するという利点がある。The relationship between the in-wafer uniformity of the etching rate of polycrystalline silicon and the He flow rate is shown in FIG. Here, if the maximum value, the minimum value, and the average value of the etching rate are respectively set as R MAX , R Min , and R, the above uniformity is defined as (R MAX −R Min ) / 2 · R. As can be seen from FIG. 5, the addition of He gas has the advantage of improving the uniformity as compared with the first embodiment.
【００１６】[0016]
【発明の効果】以上説明したように本発明は、多結晶シ
リコン層のエッチングガスとして、ＨＢｒ，Ｃｌ2 及び
Ｎ2 の混合ガスを用いたので、第１にエッチング後の寸
法をフォトレジストと同一寸法に仕上げることができる
という効果を有する。これによって、例えば、微細パタ
ーンを制御性良く高精度で得ることができる。As described above, according to the present invention, since the mixed gas of HBr, Cl 2 and N 2 is used as the etching gas for the polycrystalline silicon layer, the dimension after etching is the same as that of the photoresist. It has the effect that it can be finished to dimensions. Thereby, for example, a fine pattern can be obtained with good controllability and high accuracy.
【００１７】第２に酸化膜との選択比は４０以上が可能
であり、高い選択比でエッチングできるという効果を有
する。Secondly, the selectivity with respect to the oxide film can be 40 or more, which has the effect that etching can be performed with a high selectivity.
【００１８】また、ＨＢｒ，Ｃｌ2 ，Ｎ2 の上記混合ガ
スにＨｅを添加することにより、ウェハー面内のエッチ
ングレートの均一性を向上できる効果もある。Further, by adding He to the above mixed gas of HBr, Cl 2 and N 2 , there is also an effect that the uniformity of the etching rate within the wafer surface can be improved.
【００１９】さらに、上記混合ガスは地球外のオゾン層
を破壊するガスが含まれていないという利点も有する。Further, the above mixed gas has an advantage that it does not contain a gas that destroys the ozone layer outside the earth.
【図１】本発明の一実施例のドライエッチング方法によ
り得られた半導体装置の縦断面図である。FIG. 1 is a vertical sectional view of a semiconductor device obtained by a dry etching method according to an embodiment of the present invention.
【図２】従来のドライエッチング方法を用いて得られた
半導体装置の縦断面図である。FIG. 2 is a vertical cross-sectional view of a semiconductor device obtained by using a conventional dry etching method.
【図３】実施例１においてＨＢｒ流量寸法変化率の関係
を示すグラフである。FIG. 3 is a graph showing the relationship of the HBr flow rate dimensional change rate in Example 1.
【図４】実施例１において、Ｎ2 流量と酸化膜との選択
比の関係を示すグラフである。FIG. 4 is a graph showing the relationship between the N 2 flow rate and the selection ratio of an oxide film in Example 1.
【図５】実施例２においてＨｅ流量の比率とエッチング
レートのウェーハ面内均一性の関係を示すグラフであ
る。FIG. 5 is a graph showing the relationship between the He flow rate ratio and the in-plane uniformity of the etching rate in the wafer in Example 2.
１１，２１ シリコン基板 １２，２２ シリコン酸化膜 １３，２３ 多結晶シリコン膜 １４，２４ フォトレジスト ２５ アンダーカット 11,21 Silicon substrate 12,22 Silicon oxide film 13,23 Polycrystalline silicon film 14,24 Photoresist 25 Undercut
Claims (2)
グによりドライエッチングする方法において、エッチン
グ用ガスとして、臭化水素（ＨＢｒ），塩素（Ｃｌ2 ）
及び窒素（Ｎ2 ）の混合ガスを用いることを特徴とする
ドライエッチング方法。1. A method for dry etching polycrystalline silicon by reactive ion etching, wherein hydrogen bromide (HBr), chlorine (Cl 2 ) is used as an etching gas.
And a dry etching method using a mixed gas of nitrogen (N 2 ).
（ＨＢｒ），塩素（Ｃｌ2 ）及び窒素（Ｎ2 ）及びヘリ
ウム（Ｈｅ）の混合ガスを用いること特徴とする請求項
１記載のドライエッチング方法。2. The dry etching according to claim 1, wherein a mixed gas of hydrogen bromide (HBr), chlorine (Cl 2 ), nitrogen (N 2 ) and helium (He) is used as the etching gas. Method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3279397A JP2884852B2 (en) | 1991-10-25 | 1991-10-25 | Dry etching method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3279397A JP2884852B2 (en) | 1991-10-25 | 1991-10-25 | Dry etching method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05121370A true JPH05121370A (en) | 1993-05-18 |
| JP2884852B2 JP2884852B2 (en) | 1999-04-19 |
Family
ID=17610553
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3279397A Expired - Fee Related JP2884852B2 (en) | 1991-10-25 | 1991-10-25 | Dry etching method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2884852B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001035455A1 (en) * | 1999-11-09 | 2001-05-17 | Koninklijke Philips Electronics N.V. | Etch process that resists notching at electrode bottom |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03127826A (en) * | 1989-10-13 | 1991-05-30 | Fujitsu Ltd | Dry etching method |
| JPH03222417A (en) * | 1990-01-29 | 1991-10-01 | Nec Corp | Manufacture of semiconductor device |
-
1991
- 1991-10-25 JP JP3279397A patent/JP2884852B2/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03127826A (en) * | 1989-10-13 | 1991-05-30 | Fujitsu Ltd | Dry etching method |
| JPH03222417A (en) * | 1990-01-29 | 1991-10-01 | Nec Corp | Manufacture of semiconductor device |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001035455A1 (en) * | 1999-11-09 | 2001-05-17 | Koninklijke Philips Electronics N.V. | Etch process that resists notching at electrode bottom |
| US6794294B1 (en) | 1999-11-09 | 2004-09-21 | Koninklijke Philips Electronics N.V. | Etch process that resists notching at electrode bottom |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2884852B2 (en) | 1999-04-19 |
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