JPH0391967A - Manufacture of photodiode - Google Patents
Manufacture of photodiodeInfo
- Publication number
- JPH0391967A JPH0391967A JP1229589A JP22958989A JPH0391967A JP H0391967 A JPH0391967 A JP H0391967A JP 1229589 A JP1229589 A JP 1229589A JP 22958989 A JP22958989 A JP 22958989A JP H0391967 A JPH0391967 A JP H0391967A
- Authority
- JP
- Japan
- Prior art keywords
- silicon substrate
- sensitivity
- photodiode
- oxide film
- thermal oxide
- 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
- 238000004519 manufacturing process Methods 0.000 title claims description 9
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 35
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 35
- 239000010703 silicon Substances 0.000 claims abstract description 35
- 239000000758 substrate Substances 0.000 claims abstract description 32
- 229910052785 arsenic Inorganic materials 0.000 claims abstract description 18
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims abstract description 13
- 229920005591 polysilicon Polymers 0.000 claims abstract description 13
- 238000002347 injection Methods 0.000 claims abstract description 12
- 239000007924 injection Substances 0.000 claims abstract description 12
- 238000000034 method Methods 0.000 claims abstract description 9
- 238000010438 heat treatment Methods 0.000 claims abstract description 6
- -1 arsenic ions Chemical class 0.000 claims abstract description 4
- 230000003213 activating effect Effects 0.000 claims description 2
- 230000035945 sensitivity Effects 0.000 abstract description 41
- 230000001681 protective effect Effects 0.000 abstract description 9
- 239000000969 carrier Substances 0.000 abstract description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 abstract description 3
- 229910052681 coesite Inorganic materials 0.000 abstract description 2
- 229910052906 cristobalite Inorganic materials 0.000 abstract description 2
- 238000000206 photolithography Methods 0.000 abstract description 2
- 229910052682 stishovite Inorganic materials 0.000 abstract description 2
- 229910052905 tridymite Inorganic materials 0.000 abstract description 2
- 239000000377 silicon dioxide Substances 0.000 abstract 1
- 235000012239 silicon dioxide Nutrition 0.000 abstract 1
- 238000002513 implantation Methods 0.000 description 16
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 14
- 238000005468 ion implantation Methods 0.000 description 8
- 230000000694 effects Effects 0.000 description 6
- 238000009792 diffusion process Methods 0.000 description 5
- 230000003595 spectral effect Effects 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000007943 implant Substances 0.000 description 3
- 238000005215 recombination Methods 0.000 description 3
- 230000006798 recombination Effects 0.000 description 3
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical group [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 2
- 238000000137 annealing Methods 0.000 description 2
- 229910052796 boron Inorganic materials 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 238000000825 ultraviolet detection Methods 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 239000002019 doping agent Substances 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Landscapes
- Light Receiving Elements (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明はホトダイオードの製造方法に関するもので、特
に紫外線に感度を有するシリコンホトダイオードの製造
に使用される。DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a photodiode, and is particularly used for manufacturing a silicon photodiode sensitive to ultraviolet light.
高速応答、信頼性などの点で、シリコンホトダイオード
が広く用いられている。このホトダイオードはバンドギ
ャップエネルギー等の点から、波長λ−５８０ｎｍ近傍
に高い分光感度を有し、赤外域や紫外域での感度はそれ
ほど高くない。Silicon photodiodes are widely used due to their high-speed response and reliability. This photodiode has high spectral sensitivity in the vicinity of wavelength λ-580 nm in terms of band gap energy and the like, and sensitivity in the infrared region and ultraviolet region is not so high.
ホトダイオードに紫外線が入射すると、短波長ゆえに光
キャリアはホトダイオードの表面（受光面）近傍で生成
する。従って、紫外線検出感度を向上させるためには、
ホトダイオードのｐｎ接合を受光面の浅い位置に形成す
ること、受光面近傍のトラップ準位を出来るだけ少なく
すること等の工夫が必要である。When ultraviolet light is incident on a photodiode, optical carriers are generated near the surface (light-receiving surface) of the photodiode due to its short wavelength. Therefore, in order to improve the ultraviolet detection sensitivity,
It is necessary to take measures such as forming the pn junction of the photodiode at a shallow position on the light-receiving surface and minimizing the number of trap levels near the light-receiving surface.
しかしながら、従来はこれらの必要性が一般的に検討さ
れるだけであったため、波長λ−３００ｎｍ近傍におい
ても優れた検出感度を有するシリコンホトダイオードは
得られなかった。However, in the past, these requirements were only generally considered, and a silicon photodiode with excellent detection sensitivity even near the wavelength λ-300 nm could not be obtained.
本発明はかかる課題を解決することを目的としている。The present invention aims to solve this problem.
本発明者はシリコンホトダイオードの紫外線感度の向上
に関し、ｐ型シリコン基板に砒素（Ａｓ ）をイオン注
入してｎ型層を形成することを前提として、種々の検討
を行なった結果、本発明を完戊するに至った。すなわち
本発明は、少なくとも表面側がｐ型にされたシリコン基
板の表面に注入保護膜としての熱酸化膜を形成する第１
の工程と、受光領域形成部に開口を有するポリシリコン
等のマスクを上記の熱酸化膜上に形成する第２の工糎と
、注入保護膜としての上記熱酸化膜を介して砒素イオン
をスルー注入し、上記マスクの開口部のシリコン基板に
ｐｎ接合の実効的深さが０，８μｍ以下となるようにイ
オン注入層を形或する第３の工程と、所定温度の熱処理
によってイオン注入層を活性化する第４の工程とを備え
ることを特徴とする。The present inventor has conducted various studies on improving the ultraviolet sensitivity of silicon photodiodes based on the premise of forming an n-type layer by ion-implanting arsenic (As) into a p-type silicon substrate, and has completed the present invention. I ended up dying. That is, the present invention provides a first method of forming a thermal oxide film as an implantation protective film on the surface of a silicon substrate whose surface side is made p-type.
a second process in which a mask made of polysilicon or the like having an opening in the light-receiving region formation area is formed on the thermal oxide film, and arsenic ions are passed through the thermal oxide film as an implantation protection film. A third step is to form an ion implantation layer in the silicon substrate at the opening of the mask so that the effective depth of the pn junction is 0.8 μm or less, and the ion implantation layer is formed by heat treatment at a predetermined temperature. and a fourth step of activating.
本発明の検討にあたって、ｐ型シリコン基板（少なくと
も表面側がｐ型にされたシリコン基板）に注入保護膜を
形戊し、これを介して砒素をイオン注入（スルー注入）
することとしたのは、下記の理由による。まず、ｎ型基
板にｐ型層を形成してホトダイオードを実現するときに
は、現状の技術では不純物として用い得るのはボロン（
Ｂ）しかない。ところが、ボロンは拡散係数が大きいの
で、紫外線検出に適した浅いドーピング層を形戊するの
は困難である。これに対し、ｐ型シリコン基板にｎ型層
を形或するときには、拡散係数の小さいドーバントとし
て砒素を用いることができ、従って浅いドーピング層の
形成を精度よくかつ容易に実現できる。In studying the present invention, an implantation protection film was formed on a p-type silicon substrate (a silicon substrate whose surface side is made p-type at least), and arsenic was ion-implanted through this (through-implantation).
The reason we decided to do this is as follows. First, when forming a p-type layer on an n-type substrate to realize a photodiode, the only impurity that can be used with current technology is boron (
There is only B). However, since boron has a large diffusion coefficient, it is difficult to form a shallow doped layer suitable for ultraviolet detection. On the other hand, when forming an n-type layer on a p-type silicon substrate, arsenic can be used as a dopant with a small diffusion coefficient, and therefore a shallow doped layer can be formed accurately and easily.
一方、砒素をドーピングする際の手法としては、イオン
注入法と熱拡散法があるが、熱拡散法では表面に欠陥層
が生成されて紫外線感度が劣化しやすい。そこで、砒素
をイオン注入することとし、かつ受光部の表面の照射損
傷を低減するため、薄い注入保護膜（熱酸化膜）を介し
てスルー注入することとした。このとき、イオン注入に
よって保護膜（熱酸化ＳＩＯ２膜）中にはプラスの電荷
が蓄積しやすくなるが、本発明ではｐ型シリコン基板に
ｎ型層を形成しているので、表面（受光面）に反転層が
生起したりすることはない。ちなみに、ｎ型基板にｐ型
層を形戊したときには、プラスのチャージによってｐ型
層の表面にｎ型の反転層が形成され、これがトラップ準
位となって紫外線感度が低下してしまうのである。On the other hand, methods for doping arsenic include an ion implantation method and a thermal diffusion method, but the thermal diffusion method tends to generate a defect layer on the surface and deteriorate the ultraviolet sensitivity. Therefore, we decided to ion-implant arsenic, and in order to reduce radiation damage to the surface of the light-receiving section, we decided to perform through-implantation through a thin implant protection film (thermal oxide film). At this time, positive charges tend to accumulate in the protective film (thermally oxidized SIO2 film) due to ion implantation, but in the present invention, since the n-type layer is formed on the p-type silicon substrate, the surface (light-receiving surface) An inversion layer never occurs. By the way, when a p-type layer is formed on an n-type substrate, an n-type inversion layer is formed on the surface of the p-type layer due to positive charges, which becomes a trap level and reduces the ultraviolet sensitivity. .
受光面の注入保護膜におけるプラス電荷の蓄積は、イオ
ン注入時だけでなく紫外線の照射時（センサとしての使
用時）においても生じる。このため、ｎ型基板にｐ型層
を形成したホトダイオードでは、反転層による紫外線感
度の経時的劣化が避けられない。本発明によればかかる
感度劣化は生じないだけでなく、注入保護膜のプラス電
荷がｎ型層表面のマイナス電荷を増加させる働きをする
ので、感度は逆に向上するものと考えられる。Accumulation of positive charges in the implantation protection film on the light-receiving surface occurs not only during ion implantation but also during ultraviolet irradiation (when used as a sensor). Therefore, in a photodiode in which a p-type layer is formed on an n-type substrate, deterioration of ultraviolet sensitivity over time due to the inversion layer cannot be avoided. According to the present invention, not only such sensitivity deterioration does not occur, but also the sensitivity is thought to be improved because the positive charges of the injection protection film serve to increase the negative charges on the surface of the n-type layer.
このように本発明者は、
■ ｐ型シリコン基板にｎ型層を形成してホトダイオー
ドを構或すること、
■ ｎ型不純物として拡散係数の小さい砒素を用い、か
つ熱酸化膜を介したスルー注入でドーピングすること
を特徴とする製造方法を採用すれば、従来のものと比べ
て著しく紫外線感度の優れたシリコンホトダイオードを
実現できるものと考え、更に下記の検討を行なった。In this way, the inventors have proposed two methods: 1. Forming an n-type layer on a p-type silicon substrate to construct a photodiode; 2. Using arsenic, which has a small diffusion coefficient, as the n-type impurity, and performing through-injection through a thermal oxide film. We believed that by adopting a manufacturing method characterized by doping with silicon, it would be possible to realize a silicon photodiode with significantly superior ultraviolet sensitivity compared to conventional ones, and we further conducted the following study.
第１は、スルー注入時の保護膜とその厚さについての検
討である。注入保護膜にはＣＶＤ膜、熱酸化膜、スバッ
タ膜など各種のものが考えられるが、紫外線感度に着目
したときには保護膜とｎ型層の間の界面準位の低減が極
めて重要であり、このような界面準位を低減し得るもの
として熱酸化ＳＩＯ２膜が用い得る。The first is the consideration of the protective film and its thickness during through injection. Various types of implantation protective films can be considered, such as CVD films, thermal oxide films, and spatter films, but when focusing on ultraviolet sensitivity, it is extremely important to reduce the interface state between the protective film and the n-type layer. A thermally oxidized SIO2 film can be used to reduce such interface states.
第２は、砒素注入層の深さ、すなわちｐｎ接合の深さに
ついての検討である。波長λ−３００ｎｍ程度の紫外線
による光キャリアは、シリコン表面のごく浅いところ（
０．１〜０．３μｍ深さ）で生成していると思われる。The second consideration is the depth of the arsenic implanted layer, that is, the depth of the pn junction. Photocarriers generated by ultraviolet light with a wavelength of about λ-300 nm are generated in very shallow areas on the silicon surface (
It is thought to be generated at a depth of 0.1 to 0.3 μm).
このため、ｐ型シリコン基板とｎ型層の間の接合深さが
０．０１〜０．４μｍ程度であるときには、優れた紫外
線感度を実現し得ることは容易に予測できる。しかし、
ｐｎ接合がこれよりも深くなっていくと、表面近くで生
成した光キャリアは光電流とならずに再結合してしまう
確率が高くなる。このため、紫外線感度は接合が深くな
るつれて、徐々に低下していくと予想される。Therefore, it can be easily predicted that excellent ultraviolet sensitivity can be achieved when the junction depth between the p-type silicon substrate and the n-type layer is about 0.01 to 0.4 μm. but,
When the pn junction becomes deeper than this, there is a high probability that photocarriers generated near the surface will recombine without becoming a photocurrent. Therefore, it is expected that the ultraviolet sensitivity will gradually decrease as the junction becomes deeper.
そこで、これを実験的に検討したところ、接合深さが０
．９μｍ前後で紫外線感度は急激に低下することがわか
った。このような感度の急変は、光生或キャリアの再結
合のみでは説明が難しい。Therefore, when we investigated this experimentally, we found that the junction depth was 0.
．． It was found that the ultraviolet sensitivity rapidly decreased at around 9 μm. Such a sudden change in sensitivity is difficult to explain only by photogeneration or carrier recombination.
砒素ドーピングによるｐｎ接合が深くなると注入エネル
ギーはそれだけ大きくなり、従って照射損傷も大きくす
ることが必要になる。この損傷によ？準位が光生成キャ
リアをトラップし、そのために紫外線感度が急変した可
能性が考えられる。また、接合深さが一定であるならば
、注入保護用の熱酸化膜厚を変えても紫外線感度は変化
しないことが判明した。従って、ｐ型領域が砒素注入に
よりｎ型領域に反転する接合の深さは０．８μｍ程度以
下であることが必要で、望ましくは０．７μｍ以下に設
定される。As the pn junction becomes deeper due to arsenic doping, the implantation energy increases accordingly, and accordingly, it is necessary to increase the irradiation damage. Due to this damage? It is possible that the level trapped photogenerated carriers, which caused the sudden change in ultraviolet sensitivity. It was also found that if the junction depth is constant, the ultraviolet sensitivity does not change even if the thickness of the thermal oxide film for injection protection is changed. Therefore, the depth of the junction where the p-type region is inverted to the n-type region by arsenic implantation needs to be about 0.8 μm or less, and preferably set to 0.7 μm or less.
本発明によれば、ｐ型シリコン基板に所定厚さの熱酸化
ＳｌＯ■からなる注入保護膜が形成され、これを介して
砒素がスルー注入されて０．８μｍ以下の深さでｎ型層
が形成される。そして、アニールのための熱処理がされ
る。このため、上記の工程を採用したことによる作用と
、これら工程を組み合わせたことで奏される相互作用と
により、ホトダイオードにおける紫外線による光生成キ
ャリアのトラップ、再結合は十分に抑えられ、波長λ−
３００ｎｍ程度の紫外線おいても高い感度が実現される
。According to the present invention, an implantation protection film made of thermally oxidized SlO2 with a predetermined thickness is formed on a p-type silicon substrate, and arsenic is through-implanted through this to form an n-type layer at a depth of 0.8 μm or less. It is formed. Then, heat treatment for annealing is performed. Therefore, due to the effect of adopting the above steps and the interaction produced by combining these steps, the trapping and recombination of photogenerated carriers by ultraviolet light in the photodiode is sufficiently suppressed, and the wavelength λ-
High sensitivity is achieved even with ultraviolet light of about 300 nm.
以下、添付図面に従って本発明を詳細に説明する。 Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
第１図は実施例の製造工程を示す素子断面図である。ま
ず、比抵抗が１〜５００ｃｍのｐ型シリコン基板１を用
意し、その（１ ０ ０）面を鏡面に仕上げる。なお、
シリコン基板上にｐ型エビタキシャル層を形成したもの
をｐ型シリコン基板１としてもよい。次に、このｐ型シ
リコン基板１上に厚さｔ の熱酸化膜２を形或し、その
上にボリシリＯｘ
コン膜３を形成する（第１図（ａ）図示）。熱酸化膜は
ｐ型シリコン基板１を９００〜１０５０℃の酸素中で熱
処理することで形成される。なお、上記のポリシリコン
膜３は同一の基板１上に集積されるＭＯＳトランジスタ
等のゲート電極（図示せず）と共用してもよい。FIG. 1 is a cross-sectional view of an element showing the manufacturing process of an example. First, a p-type silicon substrate 1 having a specific resistance of 1 to 500 cm is prepared, and its (1 0 0) surface is polished to a mirror finish. In addition,
The p-type silicon substrate 1 may be a silicon substrate on which a p-type epitaxial layer is formed. Next, a thermal oxide film 2 having a thickness of t is formed on this p-type silicon substrate 1, and a polysilicon film 3 is formed thereon (as shown in FIG. 1(a)). The thermal oxide film is formed by heat-treating the p-type silicon substrate 1 in oxygen at 900-1050°C. Note that the above polysilicon film 3 may also be used as a gate electrode (not shown) of a MOS transistor or the like integrated on the same substrate 1.
次に、フォトリソグラフィによりポリシリコン膜３をパ
ターンニングし、受光部４に開口を有するポリシリコン
マスク３１を形或する（第１図（ｂ）図示）。次に、ポ
リシリコンマスク３１を注入マスクとして、熱酸化膜２
を介して砒素イオンをスルー注入する。この注入エネル
ギーの制御により、受光部４のｐ型シリコン基板１中に
形成されるｎ型注入層５は所望の深さＸ．に設定されＪ
る（第１図（ｃ）図示））。Next, the polysilicon film 3 is patterned by photolithography to form a polysilicon mask 31 having an opening in the light receiving section 4 (as shown in FIG. 1(b)). Next, using the polysilicon mask 31 as an implantation mask, the thermal oxide film 2 is
Through-implant arsenic ions through. By controlling this implantation energy, the n-type implantation layer 5 formed in the p-type silicon substrate 1 of the light-receiving section 4 has a desired depth of X. J (as shown in FIG. 1(c))).
次に、上記のｐ型シリコン基板１を熱処理炉にセットし
、１０２５℃で３０〜６０分間の熱処理を行なう。なお
、この熱処理は９５０℃程度で行なってもよいが、逆方
向リーク電流を低減するためにはより高温（一例として
１０２５℃程度）がよ・り望ましい。これにより、本実
施例のホトダイオードが得られる。Next, the above p-type silicon substrate 1 is set in a heat treatment furnace and heat treated at 1025° C. for 30 to 60 minutes. Note that this heat treatment may be performed at about 950° C., but a higher temperature (about 1025° C. as an example) is more desirable in order to reduce the reverse leakage current. As a result, the photodiode of this example is obtained.
本発明者は上記の製造工程により試料を作製し、次のよ
うな実験を行なった。なお、ｐ型シリコン基板１として
は比抵抗が１０Ω（１）のものを用いた。The present inventor produced a sample using the above manufacturing process and conducted the following experiment. The p-type silicon substrate 1 used had a specific resistance of 10Ω (1).
ｐｎ接合深さＸ．と熱酸化膜の厚さｔ を変化さＪ
ＯＸせて分
光感度特性を調べた。pn junction depth x. and the thickness t of the thermal oxide film is changed by J
The spectral sensitivity characteristics were investigated using OX.
熱酸化膜厚ｔ。Ｘ
−３００， ５００， ７００， １０００，１
２００， １５００． ２０００Ａ接合深さＸ．
Ｊ
−０．３， ０．５．０．７，０．９，１・ １ μ
ｍ
その結果を第２図ないし第５図に示す。Thermal oxide film thickness t. X -300, 500, 700, 1000,1
200, 1500. 2000A junction depth J -0.3, 0.5.0.7,0.9,1・1μ
m The results are shown in Figures 2 to 5.
理解を容易にするため、横軸に接合深さＸ．をＪ
とり、縦軸に感度（相対感度、絶対感度）をとって波長
λ−３００ｎｍの紫外線の分光感度を図示したところ、
第６図のグラフが得られた。このグラフにより、次のこ
とがわかる。For ease of understanding, the horizontal axis represents the welding depth X. When J is taken and the sensitivity (relative sensitivity, absolute sensitivity) is plotted on the vertical axis, the spectral sensitivity of ultraviolet light with a wavelength of λ-300 nm is illustrated.
The graph shown in Figure 6 was obtained. This graph reveals the following:
第１に、熱酸化膜厚ｔ がＩＯＯＯＡ以下のとＯｘ きには紫外線感度が良好で、ｔ −１２００〜Ｏｘ １３００Ａ程度のと′ころで急に感度は低下し始める。First, if the thermal oxide film thickness t is less than IOOOA, Ox When UV sensitivity is good, t-1200~Ox At about 1300A, the sensitivity suddenly begins to decrease.
そして、ｔ −１５００Ａを越えると、感度Ｏｘ
は１／３以下になってしまうことである。熱酸化膜の厚
さに関しては、あまり薄いと注入保護の機能を奏し得な
いので、数Ａ〜数１０Ａ程度以上は必要であると考えら
れる。また、イオン注入層の深さを略一定にしたときに
は、熱酸化膜を厚くするに従ってイオン注入エネルギー
を大きくすればよい筈である。このとき、注入エネルギ
ーの増大に応じて保護膜は厚くなっているので、照射損
傷は保護膜長では大きくなってもｎ型層までは及ばず、
従って紫外線に対する感度は熱酸化膜厚にあまり影響さ
れないとも考えられる。ところが、実験によれば熱酸化
膜が１２００Ａ前後より厚くなったときに、紫外線感度
が急に低下した。If t -1500A is exceeded, the sensitivity Ox becomes 1/3 or less. Regarding the thickness of the thermal oxide film, if it is too thin, it cannot function as an injection protection, so it is thought that a thickness of several amps to several tens of amps or more is necessary. Furthermore, when the depth of the ion implantation layer is kept approximately constant, the ion implantation energy should be increased as the thermal oxide film becomes thicker. At this time, the protective film becomes thicker as the implantation energy increases, so even though the protective film length increases, the radiation damage does not extend to the n-type layer.
Therefore, it is considered that the sensitivity to ultraviolet rays is not affected much by the thickness of the thermal oxide film. However, according to experiments, when the thermal oxide film became thicker than about 1200A, the ultraviolet sensitivity suddenly decreased.
原因については、イオン注入時のエネルギーがあまりに
大きくなると、シリコン表面にアニールでは回復し得な
い程度の損傷が生じ、これが紫外線による光キャリアの
トラップとして働くためであると考えることが可能であ
る。あるいはまた、大きな注入エネルギーにより熱酸化
膜が大きな損傷を受け、これがｎ型層に影響を及ぼして
紫外線感度を劣化させているとも考えられ、さらにこれ
らの原因が複雑に結びついて紫外線感度を低下させてい
るとも考えられる。一方、熱酸化膜が厚くなりすぎると
、シリコン基板への砒素のドーピング自体が好適になさ
れず、所望の注入プロファイルが実現できなくなること
も考えられる。このように、熱酸化膜厚と注入エネルギ
ーの大小が紫外線感度に影響を与える原因は、必ずしも
完全に明確であるとは言えないが、実験によれば１３０
０Ａの熱酸化膜厚を境界としてその影響が相違していた
。従って、実施例のホトダイオードにおいて紫外線の感
度の改善のためには、注入保護用の熱酸化膜厚は１３０
０Ａ以下とすることが必要であり、望ましくは１２００
Ａ以下に設定される。It is possible to think that the cause is that when the energy during ion implantation becomes too large, damage occurs to the silicon surface to a degree that cannot be recovered by annealing, and this acts as a trap for photocarriers caused by ultraviolet rays. Alternatively, it is also possible that the thermal oxide film is severely damaged by the large injection energy, which affects the n-type layer and degrades the UV sensitivity, and furthermore, these causes are intricately linked to reduce the UV sensitivity. It is also possible that On the other hand, if the thermal oxide film becomes too thick, it is conceivable that the arsenic doping itself into the silicon substrate will not be carried out properly, making it impossible to realize the desired implantation profile. In this way, it cannot be said that it is completely clear why the thermal oxide film thickness and the magnitude of the injection energy affect the ultraviolet sensitivity, but according to experiments, 130
The effects differed around the thermal oxide film thickness of 0A. Therefore, in order to improve the ultraviolet sensitivity of the photodiode of the example, the thickness of the thermal oxide film for injection protection must be 130 mm.
It is necessary to keep it below 0A, preferably 1200A.
It is set below A.
第２に、砒素のドーピングによる接合深さＸ．Ｊ
が０．７μｍ以下のときには紫外線感度が良好で、ｘ．
−０．９μｍ程度のところで感度は急に低下Ｊ
する。そして、ｘ．＝１．１μｍを越えると、感Ｊ
度は１／３以下の値にべっでしまうことである。Second, the junction depth X. due to arsenic doping. When J is 0.7 μm or less, the ultraviolet sensitivity is good, and x.
The sensitivity suddenly decreases at about -0.9 μm. And x. If the value exceeds 1.1 μm, the sensitivity J will drop to a value of 1/3 or less.
以上の結果より、注入保護膜としての熱酸化膜厚は１３
００Ａ以下とすることが必要であり、砒素の注入による
ｎ型層の深さは０．８μｍ以下とすることが必要である
と言える。From the above results, the thermal oxide film thickness as an injection protection film is 13
It can be said that the depth of the n-type layer formed by implanting arsenic needs to be 0.8 μm or less.
以上の通り本発明によれば、ｐ型シリコン基板に熱酸化
Ｓ１０２からなる注入保護膜が形成され、これを介して
砒素がイオンスルー注入されて０．８μｍ以下の深さで
ｎ型層が形成される。このため、上記の工程を採用した
ことによる作用と、これら工程を組み合わせたことで奏
される相互作用により、紫外線による光生成キャリアの
トラップ、再結合は十分に抑えられ、波長λ−３００ｎ
ｍ程度の紫外線おいても高い感度が実現される効果があ
る。また、本発明によるホトダイオードは紫外線による
感度の劣化が少ないので、高い信頼性を有している。As described above, according to the present invention, an implantation protective film made of thermally oxidized S102 is formed on a p-type silicon substrate, and arsenic is ion-implanted through this to form an n-type layer at a depth of 0.8 μm or less. be done. Therefore, the trapping and recombination of photogenerated carriers by ultraviolet rays can be sufficiently suppressed due to the effect of adopting the above steps and the interaction produced by combining these steps, and the wavelength λ-300n
This has the effect of achieving high sensitivity even to ultraviolet rays of about 500 yen. Further, the photodiode according to the present invention has high reliability because its sensitivity is less degraded by ultraviolet rays.
第１図は本発明の実施例に係るホトダイオードの製造方
法を示す工七別の素子断面図、第２図、第３図、第４図
、第５図および第６図は熱酸化膜厚ｔ １接合深さＸ，
と分光感度の関係を示すグＯＸ
Ｊラフである。
１・・・ｐ型シリコン基板、２・・・熱酸化膜、３・・
・ポリシリコン膜、３１・・・ポリシリコンマスク、４
・・・受光部、５・・・ｎ型注入層。FIG. 1 is a cross-sectional view of a photodiode manufacturing method according to an embodiment of the present invention, and FIG. 2, FIG. 3, FIG. 1 joint depth x,
GOX which shows the relationship between and spectral sensitivity
J rough. 1...p-type silicon substrate, 2...thermal oxide film, 3...
・Polysilicon film, 31...Polysilicon mask, 4
. . . Light receiving portion, 5 . . . N-type injection layer.
Claims (1)
面に注入保護膜としての熱酸化膜を形成する第１の工程
と、 受光領域形成部に開口を有するマスクを前記熱酸化膜上
に形成する第２の工程と、 前記熱酸化膜を介して砒素イオンをスルー注入し、前記
マスクの開口部の前記シリコン基板に接合の実効的深さ
が０．８μｍ以下となるようにイオン注入層を形成する
第３の工程と、 所定温度の熱処理によって前記イオン注入層を活性化す
る第４の工程と を備えることを特徴とするホトダイオードの製造方法。 ２、前記第２の工程は、ポリシリコンのマスクを形成す
る工程であることを特徴とする請求項１記載のホトダイ
オードの製造方法。[Claims] 1. A first step of forming a thermal oxide film as an injection protection film on the surface of a silicon substrate whose surface side is made p-type; a second step of forming on the oxide film, and through-implanting arsenic ions through the thermal oxide film so that the effective depth of the bond to the silicon substrate in the opening of the mask is 0.8 μm or less; A method for manufacturing a photodiode, comprising: a third step of forming an ion-implanted layer; and a fourth step of activating the ion-implanted layer by heat treatment at a predetermined temperature. 2. The method of manufacturing a photodiode according to claim 1, wherein the second step is a step of forming a polysilicon mask.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1229589A JPH0391967A (en) | 1989-09-05 | 1989-09-05 | Manufacture of photodiode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1229589A JPH0391967A (en) | 1989-09-05 | 1989-09-05 | Manufacture of photodiode |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0391967A true JPH0391967A (en) | 1991-04-17 |
Family
ID=16894550
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1229589A Pending JPH0391967A (en) | 1989-09-05 | 1989-09-05 | Manufacture of photodiode |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0391967A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006147798A (en) * | 2004-11-18 | 2006-06-08 | Hamamatsu Photonics Kk | Photodetector |
| JP2006147791A (en) * | 2004-11-18 | 2006-06-08 | Hamamatsu Photonics Kk | Manufacturing method of photodetector |
| WO2012169462A1 (en) * | 2011-06-07 | 2012-12-13 | 国立大学法人東北大学 | Photodiode, method for manufacturing same, photodiode array, spectrophotometer, and device for imaging solids |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5238385A (en) * | 1975-09-23 | 1977-03-24 | Osamu Nakagawa | Accelerateefiring device for casttangling |
| JPS5673479A (en) * | 1979-11-07 | 1981-06-18 | Yokogawa Hewlett Packard Ltd | Photodiode array |
| JPH01207640A (en) * | 1988-02-16 | 1989-08-21 | Hamamatsu Photonics Kk | Semiconductor photodetecting device and ultraviolet detecting method, and semiconductor photodetecting element and its manufacture |
-
1989
- 1989-09-05 JP JP1229589A patent/JPH0391967A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5238385A (en) * | 1975-09-23 | 1977-03-24 | Osamu Nakagawa | Accelerateefiring device for casttangling |
| JPS5673479A (en) * | 1979-11-07 | 1981-06-18 | Yokogawa Hewlett Packard Ltd | Photodiode array |
| JPH01207640A (en) * | 1988-02-16 | 1989-08-21 | Hamamatsu Photonics Kk | Semiconductor photodetecting device and ultraviolet detecting method, and semiconductor photodetecting element and its manufacture |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006147798A (en) * | 2004-11-18 | 2006-06-08 | Hamamatsu Photonics Kk | Photodetector |
| JP2006147791A (en) * | 2004-11-18 | 2006-06-08 | Hamamatsu Photonics Kk | Manufacturing method of photodetector |
| WO2012169462A1 (en) * | 2011-06-07 | 2012-12-13 | 国立大学法人東北大学 | Photodiode, method for manufacturing same, photodiode array, spectrophotometer, and device for imaging solids |
| EP2720281A1 (en) * | 2011-06-07 | 2014-04-16 | Tohoku University | Photodiode, method for manufacturing same, photodiode array, spectrophotometer, and device for imaging solids |
| EP2720281A4 (en) * | 2011-06-07 | 2014-10-22 | Univ Tohoku | Photodiode, method for manufacturing same, photodiode array, spectrophotometer, and device for imaging solids |
| JPWO2012169462A1 (en) * | 2011-06-07 | 2015-02-23 | 国立大学法人東北大学 | Photodiode and manufacturing method thereof, photodiode array, spectrophotometer, and solid-state imaging device |
| JP2015122527A (en) * | 2011-06-07 | 2015-07-02 | 国立大学法人東北大学 | Photodiode, manufacturing method of the same, photodiode array, spectrophotometer, and solid state image pickup device |
| US9214489B2 (en) | 2011-06-07 | 2015-12-15 | National University Corporation Tohoku University | Photodiode and method for producing the same, photodiode array, spectrophotometer and solid-state imaging device |
| US9568364B2 (en) | 2011-06-07 | 2017-02-14 | Tohoku University | Photodiode and method for producing the same, photodiode array, spectrophotometer and solid-state imaging device |
| EP3182454A1 (en) * | 2011-06-07 | 2017-06-21 | Tohoku University | Photodiode and method for producing the same, photodiode array, spectrophotometer and solid-state imaging device |
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