JPH01305893A - Method of cleaning silicon substrate - Google Patents

Method of cleaning silicon substrate

Info

Publication number
JPH01305893A
JPH01305893A JP13695688A JP13695688A JPH01305893A JP H01305893 A JPH01305893 A JP H01305893A JP 13695688 A JP13695688 A JP 13695688A JP 13695688 A JP13695688 A JP 13695688A JP H01305893 A JPH01305893 A JP H01305893A
Authority
JP
Japan
Prior art keywords
substrate
oxide film
disilane
cleaning
cracking
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
Application number
JP13695688A
Other languages
Japanese (ja)
Other versions
JP2663518B2 (en
Inventor
Hiroyuki Hirayama
平山 博之
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NEC Corp
Original Assignee
NEC Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by NEC Corp filed Critical NEC Corp
Priority to JP13695688A priority Critical patent/JP2663518B2/en
Publication of JPH01305893A publication Critical patent/JPH01305893A/en
Application granted granted Critical
Publication of JP2663518B2 publication Critical patent/JP2663518B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Abstract

PURPOSE:To sufficiently clean a silicon substrate at a low temp. in a short period of time by cracking gaseous disilane by a specific method and supplying the cracked gas to the substrate in cleaning of the substrate before a material to be grown is grown on the substrate. CONSTITUTION:The gaseous disilane 11 cracked by a cracking cell 6 for which electron cyclotron resonance is utilized is supplied, to the surface of the silicon substrate 3 loaded into a growth chamber 1 in order to grow the material to be grown thereon after the surface is chemically treated by an ordinary method using a liquid mixture composed of NH3, H2O2 and water and a protective oxide film is formed thereon. The protective oxide film of SiO2 on the surface of the substrate 3 is thereby removed and the surface is cleaned. Namely, the disilane is dissociated by the cracking to SiH2 and H and the SiH2 forms volatile SiO by reacting with the oxide film of SiO2, thus accelerating the desorption of the protective oxide film. The H has an effect of reducing O in the SiO2 film and exhibits the effect of etching the SiO2 film.

Description

【発明の詳細な説明】 (産業上の利用分野) 本発明はシリコン基板上への結晶などの成長法に関し、
詳しくは成長前の基板清浄化方法に関する。
[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for growing crystals on a silicon substrate,
More specifically, the present invention relates to a method for cleaning a substrate before growth.

(従来の技術) 近年、高速バイポーラ素子、マイクロ波用素子等への応
用を目的として薄いベース層を持つことを特徴とするシ
リコン系のバイポーラトランジスタ作成に関する研究開
発が盛んに行われている。
(Prior Art) In recent years, research and development has been actively conducted on the production of silicon-based bipolar transistors, which are characterized by having a thin base layer, for the purpose of application to high-speed bipolar devices, microwave devices, and the like.

予め設計したとおりの不純物濃度をもつ薄いベース層を
作成する場合には膜厚制御性が良くしかも急峻な不純物
プロファイルを有するエピタキシャル膜を作成できるシ
リコンの分子線成長技術が仔効である。シリコンの分子
線成長法では成長に先立ち基板の清浄化を行うことが重
要である。この基板初期清浄化がうまく行われない場合
には良好なエピタキシャル膜を得ることが出来ない。更
にシリコン分子線成長法をデバイス作成に応用する際に
はあらかじめ作成した不純物プロファイルが熱拡散によ
って崩れないように低温で基板初期清浄化およびエピタ
キシャル成長を行わなければならない。シリコン分子線
成長法では、最近平田らは第35回応用物理学関係連合
講演会においてジシランを用いたガスソース分子線成長
法によりエピタキシャル成長温度は630℃程度まで低
下できることを報告した(講演予稿集31p−Q−17
)。しかし基板清浄化温度はエピタキシャル温度より高
く、これを低くすることが重要である。現行のシリコン
分子線エピタキシャル成長では通常量Fの方法で基板清
浄化を行う。基板をアンモニア:過酸化水素水二本=1
:8:20の混合液で処理し基板表面にIOA程度の保
護酸化膜を形成し、この状態で分子成長装置にロードす
る。成長室中でこの上にIOA程度のアモルファスシリ
コンを蒸着しこの後基板温度を800℃まで上昇して表
面の酸化膜を揮発性の810に替えて取り去ることによ
り表面の保護酸化膜とともに基板表面に存在する不純物
を取り去り清浄化を果たす。辰巳らがジャパニーズジャ
ーナルオブアプライドフィジクス24巻L227−L2
29ページ(Japan J、Appl、Phys、。
When creating a thin base layer with a pre-designed impurity concentration, silicon molecular beam growth technology is effective because it can create an epitaxial film with good film thickness controllability and a steep impurity profile. In silicon molecular beam growth, it is important to clean the substrate prior to growth. If this initial cleaning of the substrate is not performed well, a good epitaxial film cannot be obtained. Furthermore, when applying the silicon molecular beam growth method to device fabrication, initial cleaning of the substrate and epitaxial growth must be performed at low temperatures so that the impurity profile created in advance is not destroyed by thermal diffusion. Regarding silicon molecular beam growth, Hirata et al. recently reported at the 35th Joint Conference on Applied Physics that the epitaxial growth temperature can be lowered to around 630°C by gas source molecular beam growth using disilane (Presentation proceedings, p. 31). -Q-17
). However, the substrate cleaning temperature is higher than the epitaxial temperature, and it is important to lower this temperature. In current silicon molecular beam epitaxial growth, substrate cleaning is usually performed by a method of amount F. Substrate with ammonia: 2 bottles of hydrogen peroxide = 1
: 8:20 to form a protective oxide film on the surface of the substrate of about IOA, and in this state it is loaded into a molecular growth apparatus. Amorphous silicon of about IOA is deposited on top of this in a growth chamber, and then the substrate temperature is raised to 800°C to replace the oxide film on the surface with volatile 810 and remove it, forming a protective oxide film on the surface of the substrate. Cleans by removing existing impurities. Tatsumi et al. Japanese Journal of Applied Physics Volume 24 L227-L2
29 pages (Japan J, Appl, Phys.

24(1985)pp、L227−L229)に報告し
ているように、この方法で清浄化した後にエピタキシャ
ル成長した膜の表面欠陥密度カ月02CF2以下の良好
な膜を得るためには基板の清浄化温度780°C以上の
基板加熱が必要でありこれはエピタキシャル温度に比べ
て高い温度となっている。
24 (1985) pp, L227-L229), in order to obtain a good film with a surface defect density of 02CF2 or less after epitaxial growth after cleaning with this method, the cleaning temperature of the substrate must be 780°C. It is necessary to heat the substrate to a temperature of .degree. C. or higher, which is higher than the epitaxial temperature.

(本発明が解決しようとする問題点) 従来のシリコン分子線成長法における基板の清浄化方法
、すなわちアンモニア:過酸化水素水:水=1:6:2
0によって化学処理し、表面に薄い保護酸化膜をつけた
シリコン基板を成長室にロードし、この上にIOA程度
のアモルファスシリコン膜を堆積し、その後基板温度を
上げて基板を清浄化する方法では清浄化のために780
℃以上の高い温度が必要である。このためシリコン分子
線成長法の半導体デバイスの作成への応用を考えた場合
には高い基板温度のために結晶中に作り込んだ不純物プ
ロファイルが熱拡散によってくずれてしまいデバイスの
特性が劣化するといった問題点がある。
(Problems to be Solved by the Present Invention) A method for cleaning a substrate in the conventional silicon molecular beam growth method, that is, ammonia: hydrogen peroxide solution: water = 1:6:2
This method involves loading a silicon substrate that has been chemically treated with 0 and a thin protective oxide film on the surface into a growth chamber, depositing an amorphous silicon film of about IOA on top of this, and then raising the substrate temperature to clean the substrate. 780 for cleaning
A high temperature of ℃ or higher is required. Therefore, when considering the application of silicon molecular beam growth to the production of semiconductor devices, there is a problem that the high substrate temperature causes the impurity profile created in the crystal to collapse due to thermal diffusion, resulting in deterioration of device characteristics. There is a point.

本発明は以上に述べた従来の分子線成長法における基板
清浄化方法の問題点である清浄化温度が高いという点を
解決することを目的とする。
An object of the present invention is to solve the above-mentioned problem of the conventional substrate cleaning method in the molecular beam growth method, which is that the cleaning temperature is high.

(問題を解決するための手段) 基板ははじめに通常と同様にアンモニア:過酸化水素水
:水=1:6:20によって処理し基板表面に薄い保護
酸化膜を形成する。この後基板は成長室内にロードされ
る。本発明における基板の清浄化はこの成長室内にロー
ドされた基板表面に電子サイクロトロン共鳴(Elec
tron CyclotronResonance :
 ECR)を利用したクラッキングセルによってジシラ
ンガスクラッキングした後で照射することによって果た
される。
(Means for Solving the Problem) The substrate is first treated in the usual manner with ammonia:hydrogen peroxide:water=1:6:20 to form a thin protective oxide film on the surface of the substrate. After this the substrate is loaded into the growth chamber. Cleaning of the substrate in the present invention involves electron cyclotron resonance (Electron cyclotron resonance) on the surface of the substrate loaded in this growth chamber.
tron Cyclotron Resonance:
This is accomplished by cracking disilane gas with a cracking cell using ECR) and then irradiating it.

(作用) ジシランを電子サイクロトロン共鳴を利用してクラッキ
ングした場合にはジシラン分子は解離して主にSiH2
とHが生成される。基板清浄化は薄い保護酸化膜で覆わ
れた基゛板上の保護酸化膜をきれいに取り去ることによ
って果たされるが、ジシランの電子サイクロトロン共鳴
を利用したクラッキングによって生成された5il12
はStの供給源として働き、S10□酸化膜と反応して
揮発性のSIOを形成して保護酸化膜の脱離を促進する
。またH原子はsho□膜中の酸素原子に対し還元作用
を持ち、SiO3膜のエツチング作用を示す。このため
電子サイクロトロン共鳴によってクラッキングしたジシ
ランを供給すると酸化膜のエツチングが効率良く行え、
通常のIOA程度のアモルファスシリコンを保護酸化膜
上に積んでこれを基板加熱によって510にして取り去
る方法に比べて低温で、しかも良好な清浄表面を得るこ
とが出来る。なお露出したS1表面上では5ll(2は
やはりSiの供給源として働き表面上のSt原子のダン
グリングボンドと反応してSlのエピタキシャル成長に
寄与するために過剰に供給されたジシランが格子欠陥の
発生原因になるということもない。
(Function) When disilane is cracked using electron cyclotron resonance, the disilane molecules dissociate and become mainly SiH2
and H are generated. Substrate cleaning is accomplished by removing the protective oxide film on the substrate covered with a thin protective oxide film, but 5il12 generated by cracking using the electron cyclotron resonance of disilane is
acts as a supply source of St, reacts with the S10□ oxide film, forms volatile SIO, and promotes removal of the protective oxide film. Furthermore, H atoms have a reducing effect on oxygen atoms in the sho□ film, and exhibit an etching effect on the SiO3 film. Therefore, if disilane cracked by electron cyclotron resonance is supplied, the oxide film can be etched efficiently.
Compared to a method in which amorphous silicon of the order of IOA is deposited on a protective oxide film and then removed by heating the substrate to 510, it is possible to obtain a clean surface at a lower temperature and with good quality. Note that on the exposed S1 surface, 5ll(2) still acts as a source of Si and reacts with the dangling bonds of St atoms on the surface, contributing to the epitaxial growth of Sl, so disilane supplied in excess causes lattice defects. There's no way it could be the cause.

また通常の電子サイクロトロン共鳴を用いた成長装置で
は基板と電子サイクロトロン共鳴部分の距離が短く、直
接基板がプラズマにさらされるために表面の損傷が激し
い。本方法では電子サイクロトロン共鳴部分をクラッキ
ング用セル内に限定することにより、基板と電子サイク
ロトロン共鳴部分を離し、基板が直接プラズマにさらさ
れることによる損傷を防ぐことができる。
Furthermore, in a typical growth apparatus using electron cyclotron resonance, the distance between the substrate and the electron cyclotron resonance part is short, and the substrate is directly exposed to plasma, resulting in severe surface damage. In this method, by limiting the electron cyclotron resonance part within the cracking cell, the substrate and the electron cyclotron resonance part can be separated from each other, thereby preventing damage to the substrate due to direct exposure to plasma.

(実施例) 以下図面を用いて詳細に説明する。第1図は、本発明の
詳細な説明するための装置概略図である。アンモニア:
過酸化水素水:水=1:6:20の混合液による洗浄に
よって表面に薄い保護酸化膜を形成したSl基板を電子
サイクロトロン共鳴セルを持ったガスソースシリコン分
子線成長装置において基板表面清浄化を行った例である
。装置の成長室内に保護酸化膜で覆われた5t(111
)基板がセットされている。これに対しtooxジシラ
ンガスを電子サイクロトロン共鳴クラッキングセルを通
して基板に向かって供給する。この時基板の保護酸化膜
が取れて行く様子を反射電子線回折によって観測する。
(Example) A detailed explanation will be given below using the drawings. FIG. 1 is a schematic diagram of an apparatus for explaining the present invention in detail. ammonia:
The Sl substrate with a thin protective oxide film formed on the surface by cleaning with a mixture of hydrogen peroxide and water at a ratio of 1:6:20 was cleaned in a gas source silicon molecular beam growth apparatus equipped with an electron cyclotron resonance cell. This is an example of what we did. A 5t (111
) The board is set. To this end, toox disilane gas is supplied toward the substrate through an electron cyclotron resonance cracking cell. At this time, the removal of the protective oxide film on the substrate is observed using reflected electron diffraction.

保護酸化膜に覆われている場合には酸化膜によるハロー
な反射電子線回折パターンが観測される。保護酸化膜が
とれて清浄な表面が現れた場合には清浄なSl (11
1)表面に時打なシャープな7X7表面超構造の反射電
子線回折パターンが観測される。これを用いて基板表面
の清浄化に必要な基板温度と清浄化に必要な時間を測定
した結果を第2図にジシラン照射(ECRあり) IG
として示す。図中には比較の為に基板加熱のみ14とし
てジシラン分子線を照射せずに単に基板の熱だけによっ
て清浄化した場合およびジシラン照射I5として電子サ
イクロトロン共鳴によるクラッキングを行わすにジシラ
ン分子線を供給した場合の結果も併せて示している。ジ
シラン分子線の供給量はlsecmでありこの時の成長
室内の真空度は5X 10−5〜2X 10−’Tor
rであった。ジシランを供給せずに基板の熱だけで清浄
化を行う場合には表面の保護酸化膜はその下のSlと反
応してS10となって脱離する。ジシランを供給した場
合にはジシラン分子の中で基板で解離するものがあり、
これがSIの供給源となるためにこの反応はさらに促進
されるものと考えられる。電子サイクロトロン共鳴を利
用してクランキングしたジシランを供給した場合には、
基板表面に予め解離した5III2とHが供給されるた
め、作用の所で述べたような機構に従ってさらに基板の
清浄化が促進される。実際電子サイクロトロン共鳴を用
いてクランキングしたジシランを基板に供給した場合に
は清浄化温度は600°Cまで低下でき、この時必要な
清浄化時間は15分と短く実用的であった。さらにクラ
ンキングしたジシランを用いて600℃において初期清
浄化したSl (Ill )基板上にジシランガスソー
ス分子線成長でエピタキシャル膜を成長させた場合には
得られる膜の表面欠陥密度は102cm−2以下であっ
た。このような良質のエピタキシャル膜かえられたのは
本方法によって基板初期清浄化が十分に果たされている
ことをしめしている。
When covered with a protective oxide film, a halo reflection electron beam diffraction pattern due to the oxide film is observed. When the protective oxide film is removed and a clean surface appears, clean Sl (11
1) A sharp backscattered electron diffraction pattern with a 7X7 surface superstructure is observed on the surface. Figure 2 shows the results of measuring the substrate temperature and time required for cleaning the substrate surface using this method.Disilane irradiation (with ECR) IG
Shown as For comparison, the figure shows a case in which the substrate is heated only (14), in which the substrate is cleaned simply by heating the substrate without irradiating it with a disilane molecular beam, and a case in which a disilane molecular beam is supplied to perform cracking by electron cyclotron resonance (disilane irradiation I5). The results are also shown. The amount of disilane molecular beam supplied is lsecm, and the degree of vacuum in the growth chamber at this time is 5X 10-5 to 2X 10-'Tor.
It was r. When cleaning is performed only by heat of the substrate without supplying disilane, the protective oxide film on the surface reacts with the underlying Sl to form S10 and is desorbed. When disilane is supplied, some of the disilane molecules dissociate on the substrate,
It is thought that this reaction is further promoted because it serves as a source of SI. When disilane cranked using electron cyclotron resonance is supplied,
Since the previously dissociated 5III2 and H are supplied to the substrate surface, cleaning of the substrate is further promoted according to the mechanism described in the operation section. In fact, when disilane cranked using electron cyclotron resonance was supplied to the substrate, the cleaning temperature could be lowered to 600°C, and the required cleaning time was as short as 15 minutes, which was practical. Furthermore, when an epitaxial film is grown by disilane gas source molecular beam growth on a Sl (Ill) substrate that has been initially cleaned at 600°C using cranked disilane, the surface defect density of the resulting film is less than 102 cm-2. Met. The fact that such a good quality epitaxial film was obtained indicates that the initial cleaning of the substrate is sufficiently accomplished by this method.

以上の実施例においては51基板上にSlのエピタキシ
ャル成長を分子線成長法により行った場合について説明
したが、本発明の基板の清浄化方法は、Slのエピタキ
シャル成長に限らず他の半導体の成長や電極金属などの
形成の際の基板の前処理としても用いられ、また成長方
法も分子線成長に限らず他の気相成長方法でも良い。
In the above embodiments, the epitaxial growth of Sl was performed on the 51 substrate by the molecular beam growth method, but the substrate cleaning method of the present invention is applicable not only to the epitaxial growth of Sl but also to the growth of other semiconductors and It is also used as a pretreatment for a substrate when forming metals, etc., and the growth method is not limited to molecular beam growth, but other vapor phase growth methods may be used.

(発明の効果) 以上詳しく説明したように、電子サイクロトロン共鳴ク
ラッキングセルを利用してクラッキングしたジシランを
用いて基板の清浄化を行った場合には600℃という低
温においても十分な基板の清浄化を行うことが出来る。
(Effects of the Invention) As explained in detail above, when a substrate is cleaned using disilane cracked using an electron cyclotron resonance cracking cell, the substrate can be sufficiently cleaned even at a low temperature of 600°C. It can be done.

【図面の簡単な説明】[Brief explanation of the drawing]

第1図は本発明の実施例で用いたジシランガスソース分
子線成長装置の概略図。 第2図は本発明と従来の清浄化方法を用いた清浄化に必
要な基板温度と時間を示す図。 図において、1はシリコン分子線成長表置の成長室、2
はシリコン基板加熱装置、3は保護酸化膜で覆われた4
インチSi (111>基板、4は基板シャッター、5
は電子サイクロトロン共鳴セルの発散磁界、6は電子サ
イクロトロン共鳴を利用したクラッキングセル、7は電
子サイクロトロン共鳴装置にマイクロ波を伝える導液管
、8はマイクロ波を発生するためのクライストロン、9
.10はジシランガスボンベのバルブ、11はジシラン
ガスボンベ、12は反射電子線回折用電子銃、13は反
射電子線回折用蛍光スクリーンを各々示す。
FIG. 1 is a schematic diagram of a disilane gas source molecular beam growth apparatus used in an example of the present invention. FIG. 2 is a diagram showing the substrate temperature and time required for cleaning using the present invention and a conventional cleaning method. In the figure, 1 is a growth chamber with a silicon molecular beam growth surface, 2
3 is a silicon substrate heating device, and 3 is a device 4 covered with a protective oxide film.
inch Si (111>substrate, 4 is substrate shutter, 5
is a divergent magnetic field of an electron cyclotron resonance cell, 6 is a cracking cell that uses electron cyclotron resonance, 7 is a liquid conduit that transmits microwaves to the electron cyclotron resonance device, 8 is a klystron for generating microwaves, 9
.. 10 is a bulb of a disilane gas cylinder, 11 is a disilane gas cylinder, 12 is an electron gun for backscattered electron diffraction, and 13 is a fluorescent screen for backscattered electron diffraction.

Claims (1)

【特許請求の範囲】[Claims]  シリコン基板上に被成長材料を成長する前の基板清浄
化において、電子サイクロトロン共鳴を利用したクラッ
キングセルによりジシランガスをクラッキングした後、
基板に供給することを特徴とするシリコン基板の清浄化
方法。
When cleaning the substrate before growing the material to be grown on the silicon substrate, after cracking disilane gas using a cracking cell using electron cyclotron resonance,
A method for cleaning a silicon substrate, the method comprising: supplying a silicon substrate to the substrate.
JP13695688A 1988-06-02 1988-06-02 Silicon substrate cleaning method Expired - Fee Related JP2663518B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP13695688A JP2663518B2 (en) 1988-06-02 1988-06-02 Silicon substrate cleaning method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP13695688A JP2663518B2 (en) 1988-06-02 1988-06-02 Silicon substrate cleaning method

Publications (2)

Publication Number Publication Date
JPH01305893A true JPH01305893A (en) 1989-12-11
JP2663518B2 JP2663518B2 (en) 1997-10-15

Family

ID=15187435

Family Applications (1)

Application Number Title Priority Date Filing Date
JP13695688A Expired - Fee Related JP2663518B2 (en) 1988-06-02 1988-06-02 Silicon substrate cleaning method

Country Status (1)

Country Link
JP (1) JP2663518B2 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000016384A1 (en) * 1998-09-14 2000-03-23 Matsushita Electric Industrial Co., Ltd. Apparatus for manufacturing semiconductor device and its manufacturing method

Cited By (1)

* Cited by examiner, † Cited by third party
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WO2000016384A1 (en) * 1998-09-14 2000-03-23 Matsushita Electric Industrial Co., Ltd. Apparatus for manufacturing semiconductor device and its manufacturing method

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