JP6335444B2 - 再成長構造を用いたiii族窒化物トランジスタ - Google Patents
再成長構造を用いたiii族窒化物トランジスタ Download PDFInfo
- Publication number
- JP6335444B2 JP6335444B2 JP2013132779A JP2013132779A JP6335444B2 JP 6335444 B2 JP6335444 B2 JP 6335444B2 JP 2013132779 A JP2013132779 A JP 2013132779A JP 2013132779 A JP2013132779 A JP 2013132779A JP 6335444 B2 JP6335444 B2 JP 6335444B2
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- JP
- Japan
- Prior art keywords
- barrier layer
- layer
- gate
- resistive
- regrowth structure
- 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.)
- Expired - Fee Related
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Classifications
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10D30/00—Field-effect transistors [FET]
- H10D30/01—Manufacture or treatment
- H10D30/015—Manufacture or treatment of FETs having heterojunction interface channels or heterojunction gate electrodes, e.g. HEMT
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10D30/00—Field-effect transistors [FET]
- H10D30/40—FETs having zero-dimensional [0D], one-dimensional [1D] or two-dimensional [2D] charge carrier gas channels
- H10D30/47—FETs having zero-dimensional [0D], one-dimensional [1D] or two-dimensional [2D] charge carrier gas channels having 2D charge carrier gas channels, e.g. nanoribbon FETs or high electron mobility transistors [HEMT]
- H10D30/471—High electron mobility transistors [HEMT] or high hole mobility transistors [HHMT]
- H10D30/475—High electron mobility transistors [HEMT] or high hole mobility transistors [HHMT] having wider bandgap layer formed on top of lower bandgap active layer, e.g. undoped barrier HEMTs such as i-AlGaN/GaN HEMTs
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10D62/00—Semiconductor bodies, or regions thereof, of devices having potential barriers
- H10D62/40—Crystalline structures
- H10D62/402—Amorphous materials
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10D62/00—Semiconductor bodies, or regions thereof, of devices having potential barriers
- H10D62/80—Semiconductor bodies, or regions thereof, of devices having potential barriers characterised by the materials
- H10D62/85—Semiconductor bodies, or regions thereof, of devices having potential barriers characterised by the materials being Group III-V materials, e.g. GaAs
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10D62/00—Semiconductor bodies, or regions thereof, of devices having potential barriers
- H10D62/80—Semiconductor bodies, or regions thereof, of devices having potential barriers characterised by the materials
- H10D62/85—Semiconductor bodies, or regions thereof, of devices having potential barriers characterised by the materials being Group III-V materials, e.g. GaAs
- H10D62/8503—Nitride Group III-V materials, e.g. AlN or GaN
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10D64/00—Electrodes of devices having potential barriers
- H10D64/111—Field plates
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10D64/00—Electrodes of devices having potential barriers
- H10D64/20—Electrodes characterised by their shapes, relative sizes or dispositions
- H10D64/27—Electrodes not carrying the current to be rectified, amplified, oscillated or switched, e.g. gates
- H10D64/311—Gate electrodes for field-effect devices
- H10D64/411—Gate electrodes for field-effect devices for FETs
Landscapes
- Insulated Gate Type Field-Effect Transistor (AREA)
- Junction Field-Effect Transistors (AREA)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US13/535,127 US8975664B2 (en) | 2012-06-27 | 2012-06-27 | Group III-nitride transistor using a regrown structure |
| US13/535,127 | 2012-06-27 |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2017243108A Division JP6554530B2 (ja) | 2012-06-27 | 2017-12-19 | 再成長構造を用いたiii族窒化物トランジスタ |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| JP2014011462A JP2014011462A (ja) | 2014-01-20 |
| JP2014011462A5 JP2014011462A5 (enExample) | 2016-07-14 |
| JP6335444B2 true JP6335444B2 (ja) | 2018-05-30 |
Family
ID=49754231
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2013132779A Expired - Fee Related JP6335444B2 (ja) | 2012-06-27 | 2013-06-25 | 再成長構造を用いたiii族窒化物トランジスタ |
| JP2017243108A Expired - Fee Related JP6554530B2 (ja) | 2012-06-27 | 2017-12-19 | 再成長構造を用いたiii族窒化物トランジスタ |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2017243108A Expired - Fee Related JP6554530B2 (ja) | 2012-06-27 | 2017-12-19 | 再成長構造を用いたiii族窒化物トランジスタ |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US8975664B2 (enExample) |
| JP (2) | JP6335444B2 (enExample) |
| DE (1) | DE102013010487A1 (enExample) |
| TW (1) | TWI610438B (enExample) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2924064B2 (ja) | 1990-03-31 | 1999-07-26 | スズキ株式会社 | パワートレイン |
| EP4550422A1 (en) * | 2023-10-30 | 2025-05-07 | GlobalFoundries U.S. Inc. | High electron mobility transistor with regrown barrier structure |
Families Citing this family (45)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7501669B2 (en) | 2003-09-09 | 2009-03-10 | Cree, Inc. | Wide bandgap transistor devices with field plates |
| US9773877B2 (en) | 2004-05-13 | 2017-09-26 | Cree, Inc. | Wide bandgap field effect transistors with source connected field plates |
| US11791385B2 (en) | 2005-03-11 | 2023-10-17 | Wolfspeed, Inc. | Wide bandgap transistors with gate-source field plates |
| JP5966301B2 (ja) * | 2011-09-29 | 2016-08-10 | 富士通株式会社 | 化合物半導体装置及びその製造方法 |
| US9123533B2 (en) | 2012-08-10 | 2015-09-01 | Avogy, Inc. | Method and system for in-situ etch and regrowth in gallium nitride based devices |
| US8884334B2 (en) * | 2012-11-09 | 2014-11-11 | Taiwan Semiconductor Manufacturing Co., Ltd. | Composite layer stacking for enhancement mode transistor |
| US9171946B2 (en) * | 2013-03-05 | 2015-10-27 | Seoul Semiconductor Co., Ltd. | Nitride semiconductor device and method of manufacturing the same |
| US9847411B2 (en) * | 2013-06-09 | 2017-12-19 | Cree, Inc. | Recessed field plate transistor structures |
| US9679981B2 (en) * | 2013-06-09 | 2017-06-13 | Cree, Inc. | Cascode structures for GaN HEMTs |
| US9755059B2 (en) | 2013-06-09 | 2017-09-05 | Cree, Inc. | Cascode structures with GaN cap layers |
| WO2015029434A1 (ja) * | 2013-08-30 | 2015-03-05 | 独立行政法人科学技術振興機構 | 半導体素子 |
| CN106922200B (zh) * | 2014-12-18 | 2021-11-09 | 英特尔公司 | N沟道氮化镓晶体管 |
| TWI569439B (zh) * | 2015-03-31 | 2017-02-01 | 晶元光電股份有限公司 | 半導體單元 |
| CN106298903A (zh) * | 2015-05-18 | 2017-01-04 | 中国科学院苏州纳米技术与纳米仿生研究所 | 二次外延p型ⅲ族氮化物实现增强型hemt的方法及增强型hemt |
| TWI563654B (en) * | 2015-08-26 | 2016-12-21 | Globalwafers Co Ltd | Enhancement-Mode High-Electron-Mobility Transistor Structure |
| JP6746887B2 (ja) * | 2015-09-16 | 2020-08-26 | 住友電気工業株式会社 | 高電子移動度トランジスタ、及び高電子移動度トランジスタの製造方法 |
| CN105355555A (zh) * | 2015-10-28 | 2016-02-24 | 中国科学院微电子研究所 | 一种GaN基增强型功率电子器件及其制备方法 |
| US10068976B2 (en) * | 2016-07-21 | 2018-09-04 | Taiwan Semiconductor Manufacturing Co., Ltd. | Enhancement mode field-effect transistor with a gate dielectric layer recessed on a composite barrier layer for high static performance |
| CN106876443A (zh) * | 2017-03-03 | 2017-06-20 | 上海新傲科技股份有限公司 | 高击穿电压的氮化镓高电子迁移率晶体管及其形成方法 |
| TWI661555B (zh) * | 2017-12-28 | 2019-06-01 | Nuvoton Technology Corporation | 增強型高電子遷移率電晶體元件 |
| TWI726282B (zh) * | 2019-02-19 | 2021-05-01 | 世界先進積體電路股份有限公司 | 半導體裝置及其製造方法 |
| CN111668302B (zh) * | 2019-03-08 | 2023-03-14 | 世界先进积体电路股份有限公司 | 半导体装置及其制造方法 |
| US11335797B2 (en) | 2019-04-17 | 2022-05-17 | Vanguard International Semiconductor Corporation | Semiconductor devices and methods for fabricating the same |
| CN110676316B (zh) * | 2019-09-20 | 2023-04-11 | 中国电子科技集团公司第十三研究所 | 增强型场效应晶体管 |
| US11658233B2 (en) | 2019-11-19 | 2023-05-23 | Wolfspeed, Inc. | Semiconductors with improved thermal budget and process of making semiconductors with improved thermal budget |
| JP7262379B2 (ja) * | 2019-12-16 | 2023-04-21 | 株式会社東芝 | 半導体装置 |
| CN111463259B (zh) * | 2020-03-10 | 2022-09-13 | 安徽长飞先进半导体有限公司 | 高电子迁移率场效应晶体管及其制备方法 |
| CN111668101B (zh) * | 2020-06-03 | 2022-07-01 | 西安电子科技大学 | 一种增强型氮化镓高电子迁移率晶体管及其制备方法 |
| WO2021246202A1 (ja) * | 2020-06-04 | 2021-12-09 | 三菱電機株式会社 | 半導体装置 |
| CN116034485B (zh) * | 2020-08-28 | 2025-10-03 | 华为技术有限公司 | 一种衬底及功率放大器件 |
| US11502178B2 (en) | 2020-10-27 | 2022-11-15 | Wolfspeed, Inc. | Field effect transistor with at least partially recessed field plate |
| US12266721B2 (en) | 2020-10-27 | 2025-04-01 | Wolfspeed, Inc. | Field effect transistor with multiple stepped field plate |
| US12408403B2 (en) | 2020-10-27 | 2025-09-02 | Macom Technology Solutions Holdings, Inc. | Field effect transistor with stacked unit subcell structure |
| US11658234B2 (en) * | 2020-10-27 | 2023-05-23 | Wolfspeed, Inc. | Field effect transistor with enhanced reliability |
| US11749726B2 (en) | 2020-10-27 | 2023-09-05 | Wolfspeed, Inc. | Field effect transistor with source-connected field plate |
| WO2022124868A1 (ko) * | 2020-12-11 | 2022-06-16 | 경북대학교 산학협력단 | 고전자이동도 트랜지스터 및 그 제조방법 |
| US12261168B2 (en) | 2021-02-16 | 2025-03-25 | Efficient Power Conversion Corporation | Gate metal-insulator-field plate metal integrated circuit capacitor and method of forming the same |
| CN113113478B (zh) * | 2021-03-01 | 2022-10-04 | 西安电子科技大学 | 基于欧姆再生长的GaN基射频功率器件及其制备方法 |
| US11581448B2 (en) * | 2021-04-01 | 2023-02-14 | Raytheon Company | Photoconductive semiconductor switch laterally fabricated alongside GaN on Si field effect transistors |
| KR20230000718A (ko) * | 2021-06-25 | 2023-01-03 | 삼성전자주식회사 | 고전자이동도 트랜지스터 및 그 제조 방법 |
| KR102568798B1 (ko) * | 2021-07-13 | 2023-08-21 | 삼성전자주식회사 | 고전자 이동도 트랜지스터 |
| US12218202B2 (en) * | 2021-09-16 | 2025-02-04 | Wolfspeed, Inc. | Semiconductor device incorporating a substrate recess |
| JP7739982B2 (ja) | 2021-11-30 | 2025-09-17 | 富士通株式会社 | 半導体装置 |
| KR102535264B1 (ko) * | 2021-12-09 | 2023-05-26 | 울산대학교 산학협력단 | 고전자 이동성 트랜지스터의 제조방법 |
| WO2023239942A1 (en) * | 2022-06-10 | 2023-12-14 | The Board Of Trustees Of The Leland Stanford Junior University | Passivation and high temperature oxidation of iridium oxide schottky contacts for iii-nitride devices |
Family Cites Families (28)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5915164A (en) | 1995-12-28 | 1999-06-22 | U.S. Philips Corporation | Methods of making high voltage GaN-A1N based semiconductor devices |
| WO2003015174A2 (en) * | 2001-08-07 | 2003-02-20 | Jan Kuzmik | High electron mobility devices |
| JP2006032552A (ja) | 2004-07-14 | 2006-02-02 | Toshiba Corp | 窒化物含有半導体装置 |
| US7238560B2 (en) | 2004-07-23 | 2007-07-03 | Cree, Inc. | Methods of fabricating nitride-based transistors with a cap layer and a recessed gate |
| JP2006286698A (ja) * | 2005-03-31 | 2006-10-19 | Furukawa Electric Co Ltd:The | 電子デバイス及び電力変換装置 |
| WO2008027027A2 (en) * | 2005-09-07 | 2008-03-06 | Cree, Inc | Transistor with fluorine treatment |
| JP5100002B2 (ja) * | 2005-12-14 | 2012-12-19 | 新日本無線株式会社 | 窒化物半導体装置 |
| JP5087240B2 (ja) * | 2006-06-28 | 2012-12-05 | 新日本無線株式会社 | 窒化物半導体装置の製造方法 |
| JP2008124374A (ja) * | 2006-11-15 | 2008-05-29 | Sharp Corp | 絶縁ゲート電界効果トランジスタ |
| JP2008153330A (ja) * | 2006-12-15 | 2008-07-03 | Oki Electric Ind Co Ltd | 窒化物半導体高電子移動度トランジスタ |
| JP2008270794A (ja) | 2007-03-29 | 2008-11-06 | Matsushita Electric Ind Co Ltd | 半導体装置及びその製造方法 |
| JP2008288405A (ja) * | 2007-05-18 | 2008-11-27 | Nippon Telegr & Teleph Corp <Ntt> | ヘテロ構造電界効果トランジスタ |
| WO2008151138A1 (en) * | 2007-06-01 | 2008-12-11 | The Regents Of The University Of California | P-gan/algan/aln/gan enhancement-mode field effect transistor |
| JP2008306130A (ja) * | 2007-06-11 | 2008-12-18 | Sanken Electric Co Ltd | 電界効果型半導体装置及びその製造方法 |
| US7795642B2 (en) * | 2007-09-14 | 2010-09-14 | Transphorm, Inc. | III-nitride devices with recessed gates |
| US20090072269A1 (en) * | 2007-09-17 | 2009-03-19 | Chang Soo Suh | Gallium nitride diodes and integrated components |
| JP2009231396A (ja) * | 2008-03-19 | 2009-10-08 | Sumitomo Chemical Co Ltd | 半導体装置および半導体装置の製造方法 |
| US7985986B2 (en) * | 2008-07-31 | 2011-07-26 | Cree, Inc. | Normally-off semiconductor devices |
| JP2010103478A (ja) * | 2008-09-25 | 2010-05-06 | Panasonic Corp | 窒化物半導体装置及びその製造方法 |
| US8754496B2 (en) | 2009-04-14 | 2014-06-17 | Triquint Semiconductor, Inc. | Field effect transistor having a plurality of field plates |
| WO2010151721A1 (en) | 2009-06-25 | 2010-12-29 | The Government Of The United States Of America, As Represented By The Secretary Of The Navy | Transistor with enhanced channel charge inducing material layer and threshold voltage control |
| JP2011082216A (ja) * | 2009-10-02 | 2011-04-21 | Fujitsu Ltd | 化合物半導体装置及びその製造方法 |
| US8748244B1 (en) * | 2010-01-13 | 2014-06-10 | Hrl Laboratories, Llc | Enhancement and depletion mode GaN HMETs on the same substrate |
| JP2011187623A (ja) * | 2010-03-08 | 2011-09-22 | Furukawa Electric Co Ltd:The | 半導体素子、および半導体素子の製造方法 |
| US20110241020A1 (en) * | 2010-03-31 | 2011-10-06 | Triquint Semiconductor, Inc. | High electron mobility transistor with recessed barrier layer |
| KR102065115B1 (ko) * | 2010-11-05 | 2020-01-13 | 삼성전자주식회사 | E-모드를 갖는 고 전자 이동도 트랜지스터 및 그 제조방법 |
| KR20130004760A (ko) * | 2011-07-04 | 2013-01-14 | 삼성전자주식회사 | 파워소자 및 이의 제조방법 |
| WO2013095643A1 (en) | 2011-12-23 | 2013-06-27 | Intel Corporation | Iii-n material structure for gate-recessed transistors |
-
2012
- 2012-06-27 US US13/535,127 patent/US8975664B2/en active Active
-
2013
- 2013-06-24 TW TW102122338A patent/TWI610438B/zh not_active IP Right Cessation
- 2013-06-24 DE DE102013010487.4A patent/DE102013010487A1/de not_active Withdrawn
- 2013-06-25 JP JP2013132779A patent/JP6335444B2/ja not_active Expired - Fee Related
-
2017
- 2017-12-19 JP JP2017243108A patent/JP6554530B2/ja not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2924064B2 (ja) | 1990-03-31 | 1999-07-26 | スズキ株式会社 | パワートレイン |
| EP4550422A1 (en) * | 2023-10-30 | 2025-05-07 | GlobalFoundries U.S. Inc. | High electron mobility transistor with regrown barrier structure |
Also Published As
| Publication number | Publication date |
|---|---|
| TW201405823A (zh) | 2014-02-01 |
| US20140001478A1 (en) | 2014-01-02 |
| DE102013010487A1 (de) | 2014-01-02 |
| JP6554530B2 (ja) | 2019-07-31 |
| US8975664B2 (en) | 2015-03-10 |
| JP2018082192A (ja) | 2018-05-24 |
| TWI610438B (zh) | 2018-01-01 |
| JP2014011462A (ja) | 2014-01-20 |
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