JPH01211924A - Method of flattening wafer surface - Google Patents
Method of flattening wafer surfaceInfo
- Publication number
- JPH01211924A JPH01211924A JP3537988A JP3537988A JPH01211924A JP H01211924 A JPH01211924 A JP H01211924A JP 3537988 A JP3537988 A JP 3537988A JP 3537988 A JP3537988 A JP 3537988A JP H01211924 A JPH01211924 A JP H01211924A
- Authority
- JP
- Japan
- Prior art keywords
- oxide film
- silicon wafer
- silicon
- interface
- 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.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 16
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 40
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 40
- 239000010703 silicon Substances 0.000 claims abstract description 40
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 7
- 229910017604 nitric acid Inorganic materials 0.000 claims description 7
- 230000001678 irradiating effect Effects 0.000 claims description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 abstract description 12
- 229910052814 silicon oxide Inorganic materials 0.000 abstract description 12
- 238000009792 diffusion process Methods 0.000 abstract description 10
- 238000011109 contamination Methods 0.000 abstract description 8
- 239000012535 impurity Substances 0.000 abstract description 5
- 239000013078 crystal Substances 0.000 abstract description 3
- 230000004927 fusion Effects 0.000 abstract 1
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 10
- 230000003746 surface roughness Effects 0.000 description 7
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 5
- 229910052786 argon Inorganic materials 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 3
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 229910000040 hydrogen fluoride Inorganic materials 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 230000015654 memory Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
Landscapes
- Drying Of Semiconductors (AREA)
Abstract
Description
【発明の詳細な説明】
〔概要〕
ウェハ表面の平坦化方法に関し、特に微小凹凸を有する
ウェハ表面上に酸化膜を形成し、熱線を照射して界面を
平坦化する方法に関し、シリコンウェハ表面を、不純物
等の汚染の熱拡散を防止して平坦化することができるシ
リコンウェハの平坦化方法を提供することを目的とし、
シリコンウェハ（１１）表面を硝酸溶液に浸漬し酸化膜
（１２）を形成する工程と、
この酸化膜（１２）を形成したシリコンウェハ（１１）
上を熱線で走査しながら照射する工程と、前記酸化膜（
１２）を除去する工程とを有することを特徴とするウェ
ハ表面の平坦化方法を含み構成する。[Detailed Description of the Invention] [Summary] This invention relates to a method for flattening a wafer surface, particularly a method in which an oxide film is formed on a wafer surface having minute irregularities and the interface is flattened by irradiation with heat rays. , aims to provide a method for flattening a silicon wafer that can flatten a silicon wafer by preventing thermal diffusion of contamination such as impurities,
A step of immersing the surface of a silicon wafer (11) in a nitric acid solution to form an oxide film (12), and a step of forming an oxide film (12) on the silicon wafer (11).
A step of scanning and irradiating the top with a hot ray, and a step of irradiating the oxide film (
12) A method for planarizing a wafer surface is characterized by comprising a step of removing.
（産業上の利用分野〕
本発明は、ウェハ表面の平坦化方法に関し、特に微小凹
凸を有するウェハ表面上に酸化膜を形成し、熱線を照射
して界面を平坦化する方法に関する。(Industrial Application Field) The present invention relates to a method for flattening a wafer surface, and more particularly to a method for forming an oxide film on a wafer surface having minute irregularities and irradiating it with heat rays to flatten the interface.
近年、半導体装置の製造においては、集積密度の向上と
ともに３次元的に寸法が縮小され、例えば、ＭＯＳ
）ランジスタのゲート酸化膜やダイナミック・メモリの
電荷蓄積用キャパシタの酸化膜は１００Å以下の膜厚が
必要になってきている。また、これら素子の微細化にと
もない、シリコンと酸化シリコン膜との界面の凹凸や、
これに起因した酸化膜厚の変動（ゆらぎ）が素子劣化を
引き起こすことが知られている。このシリコンと酸化シ
リコン膜との界面の凹凸を発生させる原因として、は、
ウェハ表面の微小凹凸、不純物、自然酸化膜の不均一分
布が知られており、現状では２０人を越す界面の突起も
観察されている。従って、酸化膜の膜厚制御は素子特性
を左右する重要な要素として考えられている。In recent years, in the manufacture of semiconductor devices, dimensions have been reduced three-dimensionally as integration density has improved, and for example, MOS
) Gate oxide films of transistors and oxide films of charge storage capacitors of dynamic memories need to have a film thickness of 100 Å or less. Additionally, with the miniaturization of these devices, the unevenness of the interface between silicon and silicon oxide film,
It is known that variations (fluctuations) in the oxide film thickness caused by this cause device deterioration. The causes of unevenness at the interface between silicon and silicon oxide film are as follows.
Microscopic irregularities, impurities, and uneven distribution of native oxide films on the wafer surface are known, and currently more than 20 protrusions at the interface have been observed. Therefore, controlling the thickness of the oxide film is considered to be an important factor that influences device characteristics.
一方、シリコンウェハの表面に熱酸化膜を形成し、９５
０〜９７５°Ｃ程度の温度で熱処理を施すと、界面近傍
が溶融し、粘性流によりシリコンウェハと酸化シリコン
膜との界面が平坦化することが知られている。これは、
シリコン表面のストレスが緩和することによる。On the other hand, a thermal oxide film was formed on the surface of the silicon wafer, and
It is known that when heat treatment is performed at a temperature of about 0 to 975°C, the vicinity of the interface melts and the interface between the silicon wafer and the silicon oxide film becomes flat due to viscous flow. this is,
This is due to the relaxation of stress on the silicon surface.
しかし、上記熱酸化膜によりシリコンウェハと酸化シリ
コン膜との界面を平坦化する方法では、熱処理に拡散炉
を用いるため、汚染の拡散が悪影響を及ぼす問題点があ
った。However, in the method of planarizing the interface between the silicon wafer and the silicon oxide film using the thermal oxide film, a diffusion furnace is used for the heat treatment, and therefore there is a problem in that the diffusion of contamination has an adverse effect.
そこで本発明は、シリコンウェハ表面を、不純物等の汚
染の熱拡散を防止して平坦化することができるシリコン
ウェハの平坦化方法を提供することを目的とする。SUMMARY OF THE INVENTION An object of the present invention is to provide a method for planarizing a silicon wafer, which can planarize the surface of a silicon wafer while preventing thermal diffusion of contamination such as impurities.
上記問題点は、シリコンウェハ表面を硝酸溶液に浸漬し
酸化膜を形成する工程と、この酸化膜を形成したシリコ
ンウェハ上を熱線で走査しながら照射する工程と前記酸
化膜を除去する工程と、を有することを特徴とするウェ
ハ表面の平坦化方法によって解決される。The above-mentioned problems include a step of immersing the surface of a silicon wafer in a nitric acid solution to form an oxide film, a step of scanning and irradiating the silicon wafer with the oxide film formed thereon with a hot ray, and a step of removing the oxide film. The problem is solved by a method for planarizing a wafer surface, which is characterized by having the following features.
即ち、本発明は、微小凹凸を有するシリコンウェハ表面
に酸化膜を形成し、シリコンウェハ上を熱線で走査しな
がら照射する。これにより局所的に界面近傍が溶融し粘
性流によりストレスが緩和され、シリコンウェハと酸化
シリコン膜との界面が平坦化される。このとき界面は、
熱線照射による溶融後、直ちに凝固し常温に戻るため、
シリコン結晶は汚染の拡散の如き熱の影響を受けること
がない。That is, in the present invention, an oxide film is formed on the surface of a silicon wafer having minute irregularities, and the silicon wafer is irradiated with a hot ray while being scanned. As a result, the vicinity of the interface is locally melted, the stress is alleviated by the viscous flow, and the interface between the silicon wafer and the silicon oxide film is flattened. At this time, the interface is
After melting by heat ray irradiation, it immediately solidifies and returns to room temperature, so
Silicon crystals are not affected by heat such as contamination diffusion.
以下、本発明を図示の一実施例により具体的に説明する
。Hereinafter, the present invention will be specifically explained with reference to an illustrated embodiment.
第１図は、本発明実施例に係るシリコンウェハ表面の平
坦化方法を示す製造工程断面図である。FIG. 1 is a cross-sectional view of a manufacturing process showing a method for planarizing a silicon wafer surface according to an embodiment of the present invention.
まず、同図（ａ）に示す如く、シリコンウェハ１１は、
表面に微小凹凸が形成されている。First, as shown in the same figure (a), the silicon wafer 11 is
Microscopic irregularities are formed on the surface.
次に、ｌ１ｌ（ｂ）に示す如く、シリコンウェハ１１の
表面を常温中において、例えば硝酸（ＨＮＯ３）と過酸
化水素（ｏｚｏｚ）’と水（ｔｔｚｏ）との割合が２：
３：６の清浄な硝酸溶液に浸漬し、その表面に約３０程
度度の酸化シリコン膜（Ｓ ｉ Ｏを膜）１２を形成す
る。Next, as shown in l1l(b), the surface of the silicon wafer 11 is heated at room temperature, and the ratio of, for example, nitric acid (HNO3), hydrogen peroxide (ozoz)' and water (ttzo) is 2:
It is immersed in a clean nitric acid solution with a ratio of 3:6 to form a silicon oxide film (S i O film) 12 with a thickness of about 30 degrees on its surface.
次に、同図（Ｃ）に示す如く、波長４８８ｎｍ、ビーム
径１ｍｍΦ程度のアルゴン（Ａｒ）レーザで、酸化シリ
コン膜（ＳｉＯ□膜）１２を形成したシリコンウェハ１
１表面上を、走査しながら照射する。Next, as shown in the same figure (C), a silicon wafer 1 on which a silicon oxide film (SiO□ film) 12 was formed using an argon (Ar) laser with a wavelength of 488 nm and a beam diameter of about 1 mmΦ.
1. Irradiate the surface while scanning.
次に、同図（ロ）に示す如く、フッ化水素（ＩＦ）と水
（０１０）の割合が１：３のフッ酸水溶液で酸化シリコ
ン膜１２を除去する。Next, as shown in FIG. 3B, the silicon oxide film 12 is removed using a hydrofluoric acid aqueous solution containing hydrogen fluoride (IF) and water (010) in a ratio of 1:3.
このような方法によれば、アルゴンレーザをシリコンウ
ェハ１１表面上に走査しながら照射するため、局所的に
界面近傍が溶融し粘性流によりストレスが緩和され、シ
リコンウェハ１１と酸化シリコン膜１２との界面が平坦
化される。このとき界面は、アルゴンレーザ照射による
溶融後、直ちに凝固し常温に戻るため、汚染の拡散等シ
リコン結晶が受ける熱の影響を避けることができる。最
後にフッ酸水溶液で酸化シリコン膜１２を除去すること
により、微小凹凸が平坦化された表面を持つシリコンウ
ェハ１１が得られる。According to this method, since the argon laser is scanned and irradiated onto the surface of the silicon wafer 11, the vicinity of the interface melts locally, the stress is alleviated by the viscous flow, and the bond between the silicon wafer 11 and the silicon oxide film 12 is reduced. The interface is flattened. At this time, the interface solidifies immediately after being melted by argon laser irradiation and returns to room temperature, making it possible to avoid the effects of heat on the silicon crystal, such as the diffusion of contamination. Finally, by removing the silicon oxide film 12 with an aqueous hydrofluoric acid solution, a silicon wafer 11 having a surface with flattened minute irregularities is obtained.
上記方法では、レーザ出力と走査速度等によりシリコン
ウェハ１１表面の平坦化の程度（表面粗さ）が変化する
。In the above method, the degree of flattening (surface roughness) of the surface of the silicon wafer 11 changes depending on the laser output, scanning speed, etc.
第２図は、レーザ出力と表面粗さとの関係を示す線図で
ある。なお、表面粗さは自乗平均平方根粗さＲｒ、、
（ｎｍ）により示す。同図に示す如く、走査速度が４
ｃｍ／ｓｅｃで一定のとき、レーザ出力が２→ＩＯＷと
徐々に増加するとともに、粗さＲｒ□が１．０→０．２
ｎｍに徐々に減少する。FIG. 2 is a diagram showing the relationship between laser output and surface roughness. Note that the surface roughness is the root mean square roughness Rr,
(nm). As shown in the figure, the scanning speed is 4
When the speed is constant at cm/sec, the laser output gradually increases from 2 to IOW, and the roughness Rr□ increases from 1.0 to 0.2.
gradually decreases to nm.
第３図は、レーザの走査速度と表面粗さとの関係を示す
線図である。同図に示す如く、レーザ出力が８Ｗで一定
のとき、走査速度が２→１０ｃｍ／ｓｅｃと徐々に増加
するとともに、粗さＲｒｍｓが０．８→０．２ ｎｍと
徐々に減少する。FIG. 3 is a diagram showing the relationship between laser scanning speed and surface roughness. As shown in the figure, when the laser output is constant at 8 W, the scanning speed gradually increases from 2 to 10 cm/sec, and the roughness Rrms gradually decreases from 0.8 to 0.2 nm.
すなわち、アルゴンレーザでは、出力が６Ｗ以上、走査
速度が６ ｃｍ／ｓｅｃ以下の条件でシリコンウェハ１
１の表面凹凸が大幅に減少することを示している。In other words, with the argon laser, the silicon wafer 1 is
This shows that the surface roughness of No. 1 is significantly reduced.
なお、上記実施例ではアルゴンレーザを用いているが、
シリコンウェハ１１表面上にスポット状に集光され走査
しながら照射して、局所的に界面近傍が溶融する熱線で
あればよい。In addition, although an argon laser is used in the above example,
Any hot ray may be used as long as it is condensed into a spot on the surface of the silicon wafer 11 and irradiated while scanning to locally melt the vicinity of the interface.
また、シリコンウェハ１１表面上には、熱拡散を防止す
るよう常温中で、硝酸溶液に浸漬して薄い酸化シリコン
膜１２を形成すればよい。Furthermore, a thin silicon oxide film 12 may be formed on the surface of the silicon wafer 11 by immersing it in a nitric acid solution at room temperature to prevent thermal diffusion.
〔発明の効果］
以上説明したように本発明によれば、表面に酸化膜を形
成したシリコンウェハ上を熱線で走査しながら照射する
ため、局所的に界面近傍が溶融し粘性流によりストレス
が緩和され、シリコンウェハ表面を、不純物等の汚染の
熱拡散を防止して平坦化することができる。[Effects of the Invention] As explained above, according to the present invention, since a silicon wafer with an oxide film formed on the surface is irradiated while scanning with a hot ray, the vicinity of the interface is locally melted and stress is alleviated by viscous flow. The surface of the silicon wafer can be flattened by preventing thermal diffusion of contamination such as impurities.
第１図（ａ）〜（ｄ）は、本発明実施例に係るシリコン
。
ウェハ表面の平坦化方法を示す製造工程断面図、第２図
は、レーザ出力と表面粗さとの関係を示す線図、
第３図は、レーザの走査速度と表面粗さとの関係を示す
線図である。
図において、
１１はシリコンウェハ、
１２は酸化膜、
を示す。FIGS. 1(a) to 1(d) show silicon according to an embodiment of the present invention. A cross-sectional view of the manufacturing process showing the method for flattening the wafer surface, Figure 2 is a diagram showing the relationship between laser output and surface roughness, and Figure 3 is a diagram showing the relationship between laser scanning speed and surface roughness. It is. In the figure, 11 is a silicon wafer, and 12 is an oxide film.
Claims (1)
膜（１２）を形成する工程と、 この酸化膜（１２）を形成したシリコンウェハ（１１）
上を熱線で走査しながら照射する工程と、 前記酸化膜（１２）を除去する工程とを有することを特
徴とするウェハ表面の平坦化方法。[Claims] A step of immersing the surface of a silicon wafer (11) in a nitric acid solution to form an oxide film (12), and a silicon wafer (11) on which the oxide film (12) is formed.
A method for flattening a wafer surface, comprising the steps of: scanning and irradiating the wafer surface with a hot ray; and removing the oxide film (12).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3537988A JPH01211924A (en) | 1988-02-19 | 1988-02-19 | Method of flattening wafer surface |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3537988A JPH01211924A (en) | 1988-02-19 | 1988-02-19 | Method of flattening wafer surface |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH01211924A true JPH01211924A (en) | 1989-08-25 |
Family
ID=12440262
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3537988A Pending JPH01211924A (en) | 1988-02-19 | 1988-02-19 | Method of flattening wafer surface |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH01211924A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1997007931A1 (en) * | 1995-08-22 | 1997-03-06 | Seagate Technology, Inc. | Laser surface treatments for magnetic recording media |
| US6048255A (en) * | 1995-08-22 | 2000-04-11 | Seagate Technology, Inc. | Pulsed laser surface treatments for magnetic recording media |
-
1988
- 1988-02-19 JP JP3537988A patent/JPH01211924A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1997007931A1 (en) * | 1995-08-22 | 1997-03-06 | Seagate Technology, Inc. | Laser surface treatments for magnetic recording media |
| US6048255A (en) * | 1995-08-22 | 2000-04-11 | Seagate Technology, Inc. | Pulsed laser surface treatments for magnetic recording media |
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