JP3019526B2 - Method for manufacturing thin film transistor - Google Patents
Method for manufacturing thin film transistorInfo
- Publication number
- JP3019526B2 JP3019526B2 JP3238512A JP23851291A JP3019526B2 JP 3019526 B2 JP3019526 B2 JP 3019526B2 JP 3238512 A JP3238512 A JP 3238512A JP 23851291 A JP23851291 A JP 23851291A JP 3019526 B2 JP3019526 B2 JP 3019526B2
- Authority
- JP
- Japan
- Prior art keywords
- film
- photoresist film
- gate electrode
- diffusion region
- photoresist
- 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
Links
- 239000010409 thin film Substances 0.000 title description 18
- 238000004519 manufacturing process Methods 0.000 title description 9
- 238000000034 method Methods 0.000 title description 6
- 229920002120 photoresistant polymer Polymers 0.000 claims description 36
- 238000009792 diffusion process Methods 0.000 claims description 25
- 239000004065 semiconductor Substances 0.000 claims description 17
- 239000000758 substrate Substances 0.000 claims description 11
- 238000005530 etching Methods 0.000 claims description 10
- 239000012535 impurity Substances 0.000 claims description 7
- 238000000151 deposition Methods 0.000 claims description 2
- 230000000873 masking effect Effects 0.000 claims 1
- 239000010408 film Substances 0.000 description 82
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 19
- 229910004298 SiO 2 Inorganic materials 0.000 description 16
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 10
- 229910052710 silicon Inorganic materials 0.000 description 10
- 239000010703 silicon Substances 0.000 description 10
- 229910052796 boron Inorganic materials 0.000 description 9
- -1 boron ions Chemical class 0.000 description 7
- 238000005468 ion implantation Methods 0.000 description 5
- 238000004518 low pressure chemical vapour deposition Methods 0.000 description 5
- 230000005684 electric field Effects 0.000 description 4
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 229910052698 phosphorus Inorganic materials 0.000 description 3
- 239000011574 phosphorus Substances 0.000 description 3
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 229910052785 arsenic Inorganic materials 0.000 description 2
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 2
- 229910021417 amorphous silicon Inorganic materials 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 238000010884 ion-beam technique Methods 0.000 description 1
- 238000000206 photolithography Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- 238000001039 wet etching Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
- H01L29/76—Unipolar devices, e.g. field effect transistors
- H01L29/772—Field effect transistors
- H01L29/78—Field effect transistors with field effect produced by an insulated gate
- H01L29/786—Thin film transistors, i.e. transistors with a channel being at least partly a thin film
- H01L29/78606—Thin film transistors, i.e. transistors with a channel being at least partly a thin film with supplementary region or layer in the thin film or in the insulated bulk substrate supporting it for controlling or increasing the safety of the device
- H01L29/78618—Thin film transistors, i.e. transistors with a channel being at least partly a thin film with supplementary region or layer in the thin film or in the insulated bulk substrate supporting it for controlling or increasing the safety of the device characterised by the drain or the source properties, e.g. the doping structure, the composition, the sectional shape or the contact structure
- H01L29/78621—Thin film transistors, i.e. transistors with a channel being at least partly a thin film with supplementary region or layer in the thin film or in the insulated bulk substrate supporting it for controlling or increasing the safety of the device characterised by the drain or the source properties, e.g. the doping structure, the composition, the sectional shape or the contact structure with LDD structure or an extension or an offset region or characterised by the doping profile
Description
【０００１】[0001]
【産業上の利用分野】本発明は薄膜トランジスタの製造
方法に関し、特にＬＤＤ構造の薄膜トランジスタの製造
方法に関する。The present invention relates to a method of manufacturing a thin film transistor, and more particularly to a method of manufacturing a thin film transistor having an LDD structure.
【０００２】[0002]
【従来の技術】近年、多結晶シリコン又は無定型シリコ
ンを基板とする薄膜ＭＯＳトランジスタをＳＲＡＭの負
荷素子として用いるという提案がなされている。これは
インターナショナル・エレクトロン・デバイシス・ミー
ティング・テクニカル・ダイジェスト（Ｉｎｔｅｒｎａ
ｔｉｏｎａｌ Ｅｌｅｃｔｒｏｎ Ｄｅｖｉｃｅｓ Ｍ
ｅｅｔｉｎｇ Ｔｅｃｈｎｉｃａｌ Ｄｉｇｅｓｔ）１
９８８年、第４８頁等に見られる。この場合、最も重要
となる項目としてリーク電流の低減があげられる。例え
ば４ＭｂｉｔのＳＲＡＭにおいてスタンバイ電流を１μ
Ａ以下に抑えるためには、１素子当りのリーク電流を
０．２５ｐＡ以下にしなくてはならない。このリーク電
流の低減にはチャネルとなるシリコン膜の薄膜化、ドレ
イン領域の電界緩和が効果的である。チャネル領域の薄
膜化のためには、ゲート電極がチャネル領域の下部にあ
る下部ゲート型が有利である。ゲート電極がチャネル領
域の上部にある上部ゲート型では、エッチングによって
チャネル領域のシリコン膜にダメージが与えられてしま
う可能性が高いからである。また、ドレイン領域の電界
緩和のためには、いわゆるＬＤＤ構造をとるのが有効で
ある。このようにＳＲＡＭの負荷素子として薄膜トラン
ジスタを用い、リークを低減しようとすると、下部ゲー
ト型でＬＤＤ構造を形成する必要が出てくる。2. Description of the Related Art In recent years, it has been proposed to use a thin film MOS transistor having a substrate of polycrystalline silicon or amorphous silicon as a load element of an SRAM. This is the International Electron Devices Meeting Technical Digest (Interna
Tional Electron Devices M
eating Technical Digest) 1
988, p. 48, etc. In this case, the most important item is reduction of leakage current. For example, in a 4 Mbit SRAM, the standby current is set to 1 μm.
In order to suppress the leakage current to A or less, the leakage current per element must be 0.25 pA or less. To reduce the leak current, it is effective to reduce the thickness of the silicon film serving as a channel and to alleviate the electric field in the drain region. In order to reduce the thickness of the channel region, a lower gate type in which the gate electrode is located below the channel region is advantageous. This is because, in an upper gate type in which the gate electrode is provided above the channel region, there is a high possibility that the silicon film in the channel region is damaged by etching. In order to alleviate the electric field in the drain region, it is effective to adopt a so-called LDD structure. In order to reduce the leakage by using the thin film transistor as the load element of the SRAM as described above, it is necessary to form a lower gate type LDD structure.
【０００３】以下に従来の技術による、下部ゲート型、
ＬＤＤ構造の薄膜トランジスタの製造方法を、図面を用
いて説明する。A lower gate type according to the prior art will be described below.
A method for manufacturing a thin film transistor having an LDD structure will be described with reference to the drawings.
【０００４】図３（ａ）〜（ｂ）は従来の薄膜トランジ
スタの製造方法を説明するための工程順に示した半導体
チップの断面図である。FIGS. 3A and 3B are cross-sectional views of a semiconductor chip shown in the order of steps for explaining a conventional method of manufacturing a thin film transistor.
【０００５】まず、図３（ａ）に示すように、シリコン
基板１の上に熱酸化あるいは公知のＬＰＣＶＤ法により
厚さ０．１〜１μｍのＳｉＯ2 膜２を形成する。次に、
ＳｉＯ2 膜2 の上にＬＰＣＶＤ法により厚さ５０〜２０
０ｎｍの多結晶シリコン膜を堆積し、イオン注入あるい
は拡散法によってホウ素、リンなどの不純物を１０19〜
１０20ｃｍ-3の濃度にドープした後、選択的にエッチン
グしてゲート電極３を形成する。次に、ゲート電極３の
表面にゲート酸化膜となるＳｉＯ2 膜４を熱酸化あるい
はＬＰＣＶＤ法により１０〜１００ｎｍの厚さに形成
し、ＳｉＯ2 膜４の上にＬＰＣＶＤ法により多結晶シリ
コン膜を１０〜１００ｎｍの厚さに堆積し、イオン注入
法によりリン又はヒ素を１０16〜１０17ｃｍ-3の濃度に
ドープしてチャネル領域となるＮ型多結晶シリコン膜５
を形成する。First, as shown in FIG. 3A, an SiO 2 film 2 having a thickness of 0.1 to 1 μm is formed on a silicon substrate 1 by thermal oxidation or a known LPCVD method. next,
A thickness of 50 to 20 on the SiO 2 film 2 by LPCVD.
A polycrystalline silicon film having a thickness of 0 nm is deposited, and impurities such as boron and phosphorus are doped by ion implantation or a diffusion method for 10 19 to
After doping to a concentration of 10 20 cm -3 , the gate electrode 3 is formed by selective etching. Next, an SiO 2 film 4 serving as a gate oxide film is formed on the surface of the gate electrode 3 to a thickness of 10 to 100 nm by thermal oxidation or LPCVD, and a polycrystalline silicon film is formed on the SiO 2 film 4 by LPCVD. N-type polycrystalline silicon film 5 which is deposited to a thickness of 10 to 100 nm and doped with phosphorus or arsenic to a concentration of 10 16 to 10 17 cm -3 by ion implantation to form a channel region
To form
【０００６】次に、図３（ｂ）に示すように、ゲート電
極３上のＮ型多結晶シリコン膜５の表面にパターニング
して設けたホトレジスト膜１４をマスクとして、ホウ素
イオン１５をイオン注入法により１０17〜１０18ｃｍ-3
の濃度にドープし、Ｐ- 型拡散領域９を形成する。Next, as shown in FIG. 3B, boron ions 15 are ion-implanted by using a photoresist film 14 patterned on the surface of the N-type polycrystalline silicon film 5 on the gate electrode 3 as a mask. 10 17 to 10 18 cm -3
To form a P − type diffusion region 9.
【０００７】次に、図３（ｃ）に示すように、ホトレジ
スト膜１４を除去した後、再度ホトレジスト膜１６を塗
布してパターニングし、ホトレジスト膜１６をマスクと
して、イオン注入法によりホウ素イオンをドープして、
Ｐ- 型拡散領域９と接続する１０19〜１０20ｃｍ-3の濃
度を持つＰ+ 型拡散領域１１を形成する。Next, as shown in FIG. 3C, after removing the photoresist film 14, a photoresist film 16 is applied again and patterned, and boron ions are doped by ion implantation using the photoresist film 16 as a mask. do it,
A P + -type diffusion region 11 having a concentration of 10 19 to 10 20 cm −3 connected to the P − -type diffusion region 9 is formed.
【０００８】次に、図３（ｄ）に示すように、ホトレジ
スト膜１６を除去して下部ゲート型の薄膜トランジスタ
を構成する。Next, as shown in FIG. 3D, the photoresist film 16 is removed to form a lower gate type thin film transistor.
【０００９】ここで、ホトレジスト膜１６によってマス
クされる領域はホトレジスト膜１４によってマスクされ
る領域よりも広いので、チャネル領域となるＮ型多結晶
シリコン膜５と、ソース・ドレイン領域となるＰ+ 型拡
散領域１１との間に、Ｐ- 型拡散領域９ができ、ＬＤＤ
構造が形成されて、ドレイン領域の電界を緩和する。Here, since the region masked by the photoresist film 16 is wider than the region masked by the photoresist film 14, the N-type polycrystalline silicon film 5 serving as a channel region and the P + -type film serving as source / drain regions are provided. A P − type diffusion region 9 is formed between the diffusion region 11 and the LDD region.
A structure is formed to reduce the electric field in the drain region.
【００１０】[0010]
【発明が解決しようとする課題】この従来の薄膜トラン
ジスタの製造方法は、ホトレジスト膜によるマスクを２
回使っており、自己整合的にＬＤＤ構造を形成すること
ができない。すなわち、ホトレジスト膜１４とホトレジ
スト膜１６はゲート電極３に対して位置を合わせる必要
があり、そのときの位置合わせ誤差が重なって大きくな
る可能性がある。その一例を図４に示す。図４は図３
（ｄ）の一部を拡大したものであるが、位置合わせ誤差
のないときの、Ｐ- 型拡散領域９の長さをＸ、ゲート電
極３とホトレジスト膜１４との位置合わせ誤差をσ1 ゲ
ート電極３とホトレジスト膜１６との位置合わせ誤差を
σ2 とすると、位置合わせ誤差があるときの、Ｐ- 型拡
散領域９の長さＹはＸ−（σ1 ＋σ2 ）となり、おのお
のの誤差の和が全体の誤差となる。Ｘとして用いられる
のは通常２００〜６００ｎｍであり、σ1 ，σ2 は１０
０〜２００ｎｍであるので、全体の誤差σ1 ＋σ2 は２
００〜４００ｎｍとなってＸと同等、あるいはそれ以上
となってしまう。この位置合わせ誤差は制御するのが困
難である上、薄膜トランジスタの特性はドレイン領域の
電界に敏感であるため、従来の技術では位置合わせ誤差
によって薄膜トランジスタの特性が大きく変動するとう
いう問題点があった。In this conventional method of manufacturing a thin film transistor, a mask made of a photoresist film is used.
The LDD structure cannot be formed in a self-aligned manner. That is, it is necessary to position the photoresist film 14 and the photoresist film 16 with respect to the gate electrode 3, and there is a possibility that the positioning error at that time overlaps and increases. An example is shown in FIG. FIG. 4 shows FIG.
(D) is an enlarged view, but when there is no alignment error, the length of the P − type diffusion region 9 is X, and the alignment error between the gate electrode 3 and the photoresist film 14 is σ 1 gate. Assuming that the alignment error between the electrode 3 and the photoresist film 16 is σ 2 , when there is an alignment error, the length Y of the P − -type diffusion region 9 is X− (σ 1 + σ 2 ). The sum is the overall error. X is usually 200 to 600 nm, and σ 1 and σ 2 are 10
0 to 200 nm, the overall error σ 1 + σ 2 is 2
It becomes 00 to 400 nm, which is equal to or larger than X. This alignment error is difficult to control, and the characteristics of the thin film transistor are sensitive to the electric field of the drain region. Therefore, the conventional technology has a problem that the characteristics of the thin film transistor greatly fluctuate due to the alignment error. .
【００１１】[0011]
【課題を解決するための手段】本発明の薄膜トランジス
タの製造方法は、半導体基板上に設けた絶縁膜の上に選
択的にゲート電極を形成する工程と、前記ゲート電極の
表面にゲート酸化膜を形成する工程と、前記ゲート酸化
膜を含む表面に一導電型半導体膜及び絶縁膜を順次堆積
する工程と、前記ゲート電極上の絶縁膜上に選択的にホ
トレジスト膜を形成する工程と、前記ホトレジスト膜を
マスクとして前記絶縁膜を等方性エッチングして前記ホ
トレジスト膜の端部にアンダーカット部を設ける工程
と、前記ホトレジスト膜をマスクとして前記半導体膜に
逆導電型不純物を斜め方向からイオン注入して前記アン
ダーカット部を含む前記半導体膜に逆導電型低濃度拡散
領域を形成する工程と、前記ホトレジスト膜をマスクと
して逆導電型不純物を垂直方向からイオン注入して前記
半導体膜に逆導電型高濃度拡散領域を形成する工程とを
含んで構成される。According to a method of manufacturing a thin film transistor of the present invention, a step of selectively forming a gate electrode on an insulating film provided on a semiconductor substrate, and a step of forming a gate oxide film on the surface of the gate electrode. Forming, sequentially depositing a one conductivity type semiconductor film and an insulating film on the surface including the gate oxide film, selectively forming a photoresist film on the insulating film on the gate electrode, and forming the photoresist Providing an undercut portion at an end of the photoresist film by isotropically etching the insulating film using a film as a mask, and ion-implanting a reverse conductivity type impurity into the semiconductor film obliquely using the photoresist film as a mask. Forming a reverse conductivity type low concentration diffusion region in the semiconductor film including the undercut portion by using the photoresist film as a mask; Configured and forming a opposite conductivity type high concentration diffusion region in the semiconductor film from the perpendicular direction by ion implantation.
【００１２】[0012]
【実施例】次に、本発明について図面を参照して説明す
る。Next, the present invention will be described with reference to the drawings.
【００１３】図１（ａ）〜（ｅ）は本発明の第１の実施
例を説明するための工程順に示した半導体チップの断面
図である。FIGS. 1A to 1E are sectional views of a semiconductor chip shown in the order of steps for explaining a first embodiment of the present invention.
【００１４】まず、図１（ａ）に示すように、従来例と
同様の工程によりシリコン基板１の上に設けたＳｉＯ2
膜２の上にゲート電極３を設け、ゲート電極３を含む表
面にＳｉＯ2 膜４及びＮ型多結晶シリコン膜５を順次堆
積して設ける。次にＮ型多結晶シリコン膜５の上にＬＰ
ＣＶＤ法によりＳｉＯ2 膜６を２００〜３００ｎｍの厚
さに堆積する。First, as shown in FIG. 1A, an SiO 2 film provided on a silicon substrate 1 in the same process as in the conventional example is used.
A gate electrode 3 is provided on the film 2, and a SiO 2 film 4 and an N-type polycrystalline silicon film 5 are sequentially provided on the surface including the gate electrode 3. Next, LP on the N-type polycrystalline silicon film 5
An SiO 2 film 6 is deposited to a thickness of 200 to 300 nm by a CVD method.
【００１５】次に、図１（ｂ）に示すように、ＳｉＯ2
膜６の上にホトレジスト膜７を塗布してパターニング
し、ゲート電極３上にマスクを設ける。[0015] Next, as shown in FIG. 1 (b), SiO 2
A photoresist film 7 is applied on the film 6 and patterned, and a mask is provided on the gate electrode 3.
【００１６】次に、図１（ｃ）に示すように、ウェット
エッチングの様な等方性エッチングによりホトレジスト
膜７をマスクとしてＳｉＯ2 膜６を除去する。この等方
性エッチングにより、ＳｉＯ2 膜６はホトレジスト膜７
よりも２００〜３００ｎｍ内側までエッチングされるこ
ととなる。次に、シリコン基板１を回転させながらシリ
コン基板１に対して３０〜６０°の角度でホウ素イオン
８をイオン注入し、不純物濃度が１０17〜１０18ｃｍ-3
のＰ- 型拡散領域９を形成する。ここで、Ｐ- 型拡散領
域９はホトレジスト膜７よりも１００〜５００ｎｍ内側
まで形成されることとなる。Next, as shown in FIG. 1C, the SiO 2 film 6 is removed by isotropic etching such as wet etching using the photoresist film 7 as a mask. By this isotropic etching, the SiO 2 film 6 becomes a photoresist film 7.
Etching is performed 200 to 300 nm inward. Next, while rotating the silicon substrate 1, boron ions 8 are ion-implanted into the silicon substrate 1 at an angle of 30 to 60 °, and the impurity concentration is 10 17 to 10 18 cm −3.
The P - -type diffusion region 9. Here, the P − type diffusion region 9 is formed to be 100 to 500 nm inside the photoresist film 7.
【００１７】次に、図１（ｄ）に示すように、シリコン
基板１に対して垂直にホウ素イオン１０を注入し、不純
物濃度が１０19〜１０20ｃｍ-3のＰ+ 型拡散領域１１を
形成する。Next, as shown in FIG. 1D, boron ions 10 are implanted perpendicularly to the silicon substrate 1 to form a P + type diffusion region 11 having an impurity concentration of 10 19 to 10 20 cm -3. Form.
【００１８】次に、図１（ｅ）に示すように、ホトレジ
スト膜７を除去して薄膜トランジスタを構成する。な
お、ＳｉＯ2 膜６は平坦性を高めるためにエッチングに
より除去してもよい。Next, as shown in FIG. 1E, the photoresist film 7 is removed to form a thin film transistor. Note that the SiO 2 film 6 may be removed by etching to improve flatness.
【００１９】以上のような製造方法によれば、Ｐ- 型拡
散領域９はホトレジスト膜７より１００〜５００ｎｍ内
側にまで入っているのに対し、Ｐ+ 型拡散領域１１はホ
トレジスト膜７より外側にしか形成されないので、チャ
ネル領域となるＮ型多結晶シリコン膜５とソース・ドレ
イン領域のＰ+ 型拡散領域１１の間にＰ- 型拡散領域９
を設けることになり１つのホトレジスト膜７をマスクと
してＬＤＤ構造を形成することができる。According to the manufacturing method described above, the P − -type diffusion region 9 extends 100 to 500 nm inside the photoresist film 7, whereas the P + -type diffusion region 11 extends outside the photoresist film 7. because it is not only formed during the N-type polycrystalline silicon film 5 and the source and drain regions P + -type diffusion region 11 as a channel region P - -type diffusion region 9
Thus, the LDD structure can be formed using one photoresist film 7 as a mask.
【００２０】図２（ａ）〜（ｅ）は本発明の第２の実施
例を説明するための工程順に示した半導体チップの断面
図である。FIGS. 2A to 2E are sectional views of a semiconductor chip shown in the order of steps for explaining a second embodiment of the present invention.
【００２１】図２（ａ）に示すように、第１の実施例と
同様の工程でゲート電極３を含む表面にＳｉＯ2 膜４及
びＮ型多結晶シリコン膜５を順次堆積して設けた後、Ｎ
型多結晶シリコン膜５の表面を熱酸化するかあるいはＬ
ＰＣＶＤ法により堆積して５〜３０ｎｍのＳｉＯ２膜１
２を形成し、ＳｉＯ2 膜１２の上にＬＰＣＶＤ法により
厚さ２００〜３００ｎｍの多結晶シリコン膜１３を堆積
する。この多結晶シリコン膜１３には、導電性をもたせ
るために、ホウ素、リン、ヒ素などの不純物を、拡散法
あるいはイオン注入法によりドープしてもよい。As shown in FIG. 2A, after the SiO 2 film 4 and the N-type polycrystalline silicon film 5 are sequentially deposited and provided on the surface including the gate electrode 3 in the same process as in the first embodiment. , N
Thermal oxidation of the surface of the polycrystalline silicon film 5 or L
5-30 nm SiO2 film 1 deposited by PCVD
Then, a polycrystalline silicon film 13 having a thickness of 200 to 300 nm is deposited on the SiO 2 film 12 by LPCVD. The polycrystalline silicon film 13 may be doped with an impurity such as boron, phosphorus, or arsenic by a diffusion method or an ion implantation method in order to impart conductivity.
【００２２】次に、図２（ｂ）に示すように、多結晶シ
リコン膜１３の上にホトレジスト膜７を塗布し、ホトリ
ソグラフィ技術によりパターニングする。Next, as shown in FIG. 2B, a photoresist film 7 is applied on the polycrystalline silicon film 13 and patterned by photolithography.
【００２３】次に、図２（ｃ）示すように、等方性エッ
チングにより多結晶シリコン膜１３を、ホトレジスト膜
７の端部より２００〜３００ｎｍ内側までエッチングす
る。このときＳｉＯ2 膜１２はエッチングのストッパー
として機能する。次に、第１の実施例と同様に、シリコ
ン基板１に対して３０〜６０°の角度でホウ素イオン８
を注入し、１０17〜１０18ｃｍ-3の濃度にドープされた
Ｐ- 型拡散領域９を形成する。Next, as shown in FIG. 2C, the polycrystalline silicon film 13 is etched by 200 to 300 nm from the end of the photoresist film 7 by isotropic etching. At this time, the SiO 2 film 12 functions as an etching stopper. Next, similarly to the first embodiment, the boron ions 8 are formed at an angle of 30 to 60 ° with respect to the silicon substrate 1.
To form a P − -type diffusion region 9 doped at a concentration of 10 17 to 10 18 cm −3 .
【００２４】次に、図２（ｄ）に示すように、シリコン
基板１に対し垂直にホウ素イオン１０をイオン注入し
て、１０19〜１０20ｃｍ-3の濃度のＰ+ 型拡散領域１１
を形成する。Next, as shown in FIG. 2D, boron ions 10 are ion-implanted perpendicularly to the silicon substrate 1 to form a P + type diffusion region 11 having a concentration of 10 19 to 10 20 cm -3.
To form
【００２５】次に、図２（ｅ）に示すように、ホトレジ
スト膜７を除去して薄膜トランジスを構成する。Next, as shown in FIG. 2E, the photoresist film 7 is removed to form a thin film transistor.
【００２６】この実施例によれば、チャネル領域となる
Ｎ型多結晶シリコン膜５の上に、ＳｉＯ2 膜１２を介し
て多結晶シリコン膜１３が残るので、これを薄膜トラン
ジスタのゲート電極として用いれば、チャネル領域をゲ
ート電極が上下からはさむ形となり、チャネル電位が安
定し、薄膜トランジスタの特性が向上するという利点が
ある。According to this embodiment, since the polycrystalline silicon film 13 remains on the N-type polycrystalline silicon film 5 serving as a channel region via the SiO 2 film 12, it can be used as a gate electrode of a thin film transistor. In addition, there is an advantage that the gate electrode sandwiches the channel region from above and below, the channel potential is stabilized, and the characteristics of the thin film transistor are improved.
【００２７】[0027]
【発明の効果】以上説明したように本発明は、ホトレジ
スト膜を１回形成するだけでＬＤＤ構造が形成できるの
で、従来の技術のように位置合わせ誤差が足し合わさる
ことがなく、従来の技術では２００〜４００ｎｍであっ
た位置合わせ誤差が１００〜２００ｎｍに低減される。
また、低濃度拡散領域の大きさは、ホトレジスト膜の下
に敷く被覆膜の厚さ及びイオンビームの角度によって決
まる。従って制御性よく、安定した特性の下部ゲート
型、ＬＤＤ構造の薄膜トランジスタを得ることができ
る。As described above, according to the present invention, since the LDD structure can be formed only by forming the photoresist film once, the positioning errors are not added as in the prior art. The positioning error from 200 to 400 nm is reduced to 100 to 200 nm.
Further, the size of the low concentration diffusion region is determined by the thickness of the coating film laid below the photoresist film and the angle of the ion beam. Therefore, a thin film transistor having a lower gate type and an LDD structure having stable characteristics with good controllability can be obtained.
【図１】本発明の第１の実施例を説明するための工程順
に示した半導体チップの断面図。FIG. 1 is a sectional view of a semiconductor chip shown in the order of steps for explaining a first embodiment of the present invention.
【図２】本発明の第２の実施例を説明するための工程順
に示した半導体チップの断面図。FIG. 2 is a sectional view of a semiconductor chip shown in order of steps for explaining a second embodiment of the present invention.
【図３】従来の薄膜トランジスタの製造方法を説明する
ための工程順に示した半導体チップの断面図。FIG. 3 is a cross-sectional view of a semiconductor chip shown in the order of steps for explaining a conventional method of manufacturing a thin film transistor.
【図４】従来例の問題点を説明するための半導体チップ
の断面図。FIG. 4 is a cross-sectional view of a semiconductor chip for describing a problem of a conventional example.
１ シリコン基板 ２，４，６，１２ ＳｉＯ2 膜 ３ ゲート電極 ５ Ｎ型多結晶シリコン膜 ７，１４，１６ ホトレジスト膜 ８，１０，１５ ホウ素イオン ９ Ｐ- 型拡散領域 １１ Ｐ+ 型拡散領域 １３ 多結晶シリコン膜1 silicon substrate 2, 4, 6, 12 SiO 2 film 3 gate electrode 5 N-type polycrystalline silicon film 7,14,16 photoresist film 8, 10, 15 boron ions 9 P - -type diffusion region 11 P + -type diffusion region 13 Polycrystalline silicon film
Claims (1)
的にゲート電極を形成する工程と、前記ゲート電極の表
面にゲート酸化膜を形成する工程と、前記ゲート酸化膜
を含む表面に一導電型半導体膜及び絶縁膜を順次堆積す
る工程と、前記ゲート電極上の絶縁膜上に選択的にホト
レジスト膜を形成する工程と、前記ホトレジスト膜をマ
スクとして前記絶縁膜を等方性エッチングして前記ホト
レジスト膜の端部にアンダーカット部を設ける工程と、
前記ホトレジスト膜をマスクとして前記半導体膜に逆導
電型不純物を斜め方向からイオン注入して前記アンダー
カット部を含む前記半導体膜に逆導電型低濃度拡散領域
を形成する工程と、前記ホトレジスト膜をマスクとして
逆導電型不純物を垂直方向からイオン注入して前記半導
体膜に逆導電型高濃度拡散領域を形成する工程とを含む
ことを特徴とする薄膜トランジスタの製造方法。A step of selectively forming a gate electrode on an insulating film provided on a semiconductor substrate; a step of forming a gate oxide film on a surface of the gate electrode; A step of sequentially depositing a semiconductor film of one conductivity type and an insulating film, a step of selectively forming a photoresist film on the insulating film on the gate electrode, and isotropically etching the insulating film using the photoresist film as a mask. Providing an undercut portion at the end of the photoresist film,
Forming a reverse conductivity type low concentration diffusion region in the semiconductor film including the undercut portion by ion-implanting a reverse conductivity type impurity into the semiconductor film obliquely using the photoresist film as a mask; and masking the photoresist film. Forming a reverse-conductivity-type high-concentration diffusion region in the semiconductor film by ion-implanting a reverse-conductivity-type impurity in a vertical direction.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3238512A JP3019526B2 (en) | 1991-09-19 | 1991-09-19 | Method for manufacturing thin film transistor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3238512A JP3019526B2 (en) | 1991-09-19 | 1991-09-19 | Method for manufacturing thin film transistor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0582549A JPH0582549A (en) | 1993-04-02 |
| JP3019526B2 true JP3019526B2 (en) | 2000-03-13 |
Family
ID=17031356
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3238512A Expired - Fee Related JP3019526B2 (en) | 1991-09-19 | 1991-09-19 | Method for manufacturing thin film transistor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3019526B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7758675B2 (en) | 2004-04-28 | 2010-07-20 | Isuzu Motors Limited | Gas treatment device |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2530990B2 (en) * | 1992-10-15 | 1996-09-04 | 富士通株式会社 | Method of manufacturing thin film transistor matrix |
| US5440168A (en) * | 1993-02-22 | 1995-08-08 | Ryoden Semiconductor System Engineering Corporation | Thin-film transistor with suppressed off-current and Vth |
| JP2905680B2 (en) * | 1993-12-20 | 1999-06-14 | シャープ株式会社 | Method for manufacturing thin film transistor |
| KR950026032A (en) * | 1994-02-25 | 1995-09-18 | 김광호 | Method of manufacturing polycrystalline silicon thin film transistor |
| KR100444771B1 (en) * | 1997-12-30 | 2004-10-14 | 주식회사 하이닉스반도체 | Semiconductor fabrication method for forming transistor of ldd structure by performing photo-mask process only once |
| CN107154346B (en) * | 2017-05-19 | 2021-03-16 | 京东方科技集团股份有限公司 | Film doping method, thin film transistor and manufacturing method thereof |
-
1991
- 1991-09-19 JP JP3238512A patent/JP3019526B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7758675B2 (en) | 2004-04-28 | 2010-07-20 | Isuzu Motors Limited | Gas treatment device |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0582549A (en) | 1993-04-02 |
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