JP6863251B2 - Silicon wafer processing method - Google Patents
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- JP6863251B2 JP6863251B2 JP2017232570A JP2017232570A JP6863251B2 JP 6863251 B2 JP6863251 B2 JP 6863251B2 JP 2017232570 A JP2017232570 A JP 2017232570A JP 2017232570 A JP2017232570 A JP 2017232570A JP 6863251 B2 JP6863251 B2 JP 6863251B2
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims description 52
- 229910052710 silicon Inorganic materials 0.000 title claims description 52
- 239000010703 silicon Substances 0.000 title claims description 52
- 238000003672 processing method Methods 0.000 title claims description 8
- 238000005498 polishing Methods 0.000 claims description 45
- 239000012535 impurity Substances 0.000 claims description 37
- 239000002184 metal Substances 0.000 claims description 36
- 229910052751 metal Inorganic materials 0.000 claims description 36
- 238000010438 heat treatment Methods 0.000 claims description 35
- 238000000034 method Methods 0.000 claims description 27
- 239000006061 abrasive grain Substances 0.000 claims description 18
- 239000011347 resin Substances 0.000 claims description 18
- 229920005989 resin Polymers 0.000 claims description 18
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 15
- 239000000126 substance Substances 0.000 claims description 12
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 claims description 8
- 239000003795 chemical substances by application Substances 0.000 claims description 8
- 230000006698 induction Effects 0.000 claims 1
- 238000005406 washing Methods 0.000 claims 1
- 230000007547 defect Effects 0.000 description 27
- 230000000052 comparative effect Effects 0.000 description 8
- 239000000243 solution Substances 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000007517 polishing process Methods 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 239000003513 alkali Substances 0.000 description 4
- 238000004140 cleaning Methods 0.000 description 4
- 239000008119 colloidal silica Substances 0.000 description 4
- 239000013078 crystal Substances 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 238000011109 contamination Methods 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 239000012299 nitrogen atmosphere Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- 238000000149 argon plasma sintering Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- Mechanical Treatment Of Semiconductor (AREA)
- Cleaning Or Drying Semiconductors (AREA)
Description
本発明は、少なくとも研磨を行うシリコンウェーハの加工方法に関する。 The present invention relates to at least a method for processing a silicon wafer to be polished.
シリコンを用いた半導体デバイスは微細化が進むにつれ、より微細なＬＬＳ（Ｌｏｃａｌｉｚｅｄ ｌｉｇｈｔ Ｓｃａｔｔｅｒｉｎｇ）欠陥の抑制が求められている。ＬＬＳ欠陥の中には、洗浄で落としきれない異物や研磨中に導入されるスクラッチの他に、ＮｉやＣｕなどの金属不純物が原因で発生する欠陥がある。これらの金属不純物が原因の欠陥は、突起状になっているものやピット状になっているものもあり、その凹凸自体がデバイス不良を引き起こす可能性があるだけでなく、その欠陥中に含まれる金属不純物が熱処理により拡散してデバイス不良を引き起こす可能性もあるため、厳重に発生を抑制しなければいけない。 As the miniaturization of semiconductor devices using silicon progresses, it is required to suppress finer LLS (Located light Scattering) defects. Among the LLS defects, there are defects generated due to metal impurities such as Ni and Cu, in addition to foreign substances that cannot be completely removed by cleaning and scratches introduced during polishing. Defects caused by these metal impurities may be prominent or pit-like, and the unevenness itself can cause device failure and is included in the defects. Since metal impurities may diffuse due to heat treatment and cause device defects, the generation must be strictly suppressed.
図２に、従来におけるウェーハの製造方法の工程フロー図を示す。上記ＬＬＳ欠陥を形成する金属不純物は、結晶引き上げ工程（図２（ａ））やスライス工程（図２（ｂ））、研削（ラップ）工程（図２（ｃ））、研磨工程（図２（ｄ））で導入されることが分かっている。特に、ＮｉやＣｕなど比較的シリコンウェーハ内の移動度が高い金属不純物は拡散速度が高いため、研削や研磨工程等のウェーハ加工工程でも容易に侵入し、ＬＬＳ欠陥を形成してしまう。図４に、代表的なＬＬＳ欠陥のＳＥＭ像を示す。 FIG. 2 shows a process flow chart of a conventional wafer manufacturing method. The metal impurities forming the LLS defect include a crystal pulling step (FIG. 2 (a)), a slicing step (FIG. 2 (b)), a grinding (wrapping) step (FIG. 2 (c)), and a polishing step (FIG. 2 (c)). It is known to be introduced in d)). In particular, metal impurities such as Ni and Cu, which have a relatively high mobility in a silicon wafer, have a high diffusion rate, so that they easily invade even in a wafer processing process such as a grinding or polishing process and form LLS defects. FIG. 4 shows an SEM image of a typical LLS defect.
金属不純物を除去するために、例えば特許文献１では、スライス工程後に熱処理を行うことで、金属不純物を表面に誘起させて除去する手法が開示されている。この手法であれば、結晶引き上げ工程やスライス工程で導入された金属不純物を除去することはできるが、スライス工程後の、研削、研磨工程等のウェーハ加工工程で導入される金属不純物の除去手段がないため、研削、研磨工程の状況によっては再び表面に金属不純物起因のＬＬＳ欠陥を形成してしまうという問題があった。 In order to remove metal impurities, for example, Patent Document 1 discloses a method of inducing and removing metal impurities on the surface by performing a heat treatment after the slicing step. With this method, it is possible to remove the metal impurities introduced in the crystal pulling process and the slicing process, but the means for removing the metal impurities introduced in the wafer processing process such as grinding and polishing after the slicing process is available. Therefore, there is a problem that LLS defects due to metal impurities are formed on the surface again depending on the conditions of the grinding and polishing processes.
本発明は、上記問題点に鑑みてなされたものであって、ウェーハ表面に存在する金属不純物および金属不純物起因の欠陥を抑制することができるシリコンウェーハの加工方法を提供することを目的とする。 The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for processing a silicon wafer capable of suppressing metal impurities existing on the wafer surface and defects caused by the metal impurities.
上記課題を解決するために、本発明は、シリコンウェーハに対し少なくとも研磨を行うシリコンウェーハの加工方法であって、前記シリコンウェーハに対し、樹脂パッドと砥粒を含む研磨剤とを用いて研磨を行い、該研磨後の前記シリコンウェーハを、過酸化水素又はオゾンを含む薬液で洗浄し、該洗浄後の前記シリコンウェーハに、４００℃以上７００℃以下の温度で熱処理を行い、その後、前記熱処理後の前記シリコンウェーハに対し、樹脂パッドと砥粒を含む研磨剤とを用い、取り代を５ｎｍ以上１００ｎｍ以下として最終仕上げ研磨を行うことを特徴とするシリコンウェーハの加工方法を提供する。 In order to solve the above problems, the present invention is a method for processing a silicon wafer that at least polishes a silicon wafer, and the silicon wafer is polished by using a resin pad and a polishing agent containing abrasive grains. Then, the polished silicon wafer is washed with a chemical solution containing hydrogen peroxide or ozone, and the cleaned silicon wafer is heat-treated at a temperature of 400 ° C. or higher and 700 ° C. or lower, and then after the heat treatment. Provided is a method for processing a silicon wafer, which comprises using a resin pad and a polishing agent containing abrasive grains to perform final finish polishing on the silicon wafer with a removal allowance of 5 nm or more and 100 nm or less.
このようなシリコンウェーハの加工方法であれば、ウェーハ表面に存在する金属不純物、及び金属不純物起因の欠陥を確実に抑制することができ、高品質のシリコンウェーハを得ることができる。 With such a silicon wafer processing method, metal impurities existing on the wafer surface and defects caused by metal impurities can be reliably suppressed, and a high-quality silicon wafer can be obtained.
本発明のシリコンウェーハの加工方法であれば、金属不純物及び金属不純物に起因する欠陥（ＬＬＳ欠陥）を確実に低減することができ、高品質のシリコンウェーハを得ることができる。 According to the silicon wafer processing method of the present invention, metal impurities and defects (LLS defects) caused by metal impurities can be reliably reduced, and a high quality silicon wafer can be obtained.
上述したように、従来の、スライス工程後に熱処理を行うシリコンウェーハの製造方法では、スライス工程後の研削、研磨工程で導入される金属不純物の除去手段がないため、研削、研磨工程において再び表面に金属不純物起因のＬＬＳ欠陥が発生してしまうという問題があった。 As described above, in the conventional method for manufacturing a silicon wafer in which heat treatment is performed after the slicing process, there is no means for removing metal impurities introduced in the grinding and polishing steps after the slicing process. There is a problem that LLS defects caused by metal impurities occur.
本発明者らは、ウェーハ加工プロセス中で低温熱処理を行うことで上記問題点の解決を図った。そして、なるべく加工プロセスの後半に低温熱処理を行い、低温熱処理後の工程は少なくする方が良いことを知見した。更に、低温熱処理後に、厳重に不純物管理された状態で、わずかな取り代で凹凸平坦化および表面金属除去工程を導入する必要があることを知見した。 The present inventors have tried to solve the above problems by performing low-temperature heat treatment in the wafer processing process. Then, it was found that it is better to perform low temperature heat treatment in the latter half of the processing process as much as possible and reduce the number of steps after the low temperature heat treatment. Furthermore, it was found that after low-temperature heat treatment, it is necessary to introduce a step of flattening unevenness and removing surface metal with a small allowance in a state where impurities are strictly controlled.
そして、本発明者らは上記の問題を解決するために鋭意検討を重ねた結果、シリコンウェーハに対し、樹脂パッドと砥粒を含む研磨剤とを用いて研磨を行い、該研磨後の前記シリコンウェーハを、過酸化水素又はオゾンを含む薬液で洗浄し、該洗浄後の前記シリコンウェーハに、４００℃以上７００℃以下の温度で熱処理を行い、その後、前記熱処理後の前記シリコンウェーハに対し、樹脂パッドと砥粒を含む研磨剤とを用い、取り代を５ｎｍ以上１００ｎｍ以下として最終仕上げ研磨を行うシリコンウェーハの加工方法であれば、ウェーハ表面に存在する金属不純物および金属不純物起因の欠陥を抑制することができることを見出し、本発明に到達した。 Then, as a result of diligent studies to solve the above problems, the present inventors polished the silicon wafer using a resin pad and a polishing agent containing abrasive grains, and the silicon after polishing. The wafer is washed with a chemical solution containing hydrogen peroxide or ozone, the cleaned silicon wafer is heat-treated at a temperature of 400 ° C. or higher and 700 ° C. or lower, and then the silicon wafer after the heat treatment is subjected to a resin. A silicon wafer processing method that uses a pad and a polishing agent containing abrasive grains and performs final finish polishing with a removal allowance of 5 nm or more and 100 nm or less suppresses metal impurities existing on the wafer surface and defects caused by metal impurities. We have found that we can do this and have arrived at the present invention.
即ち、本発明は、シリコンウェーハに対し少なくとも研磨を行うシリコンウェーハの加工方法であって、前記シリコンウェーハに対し、樹脂パッドと砥粒を含む研磨剤とを用いて研磨を行い、該研磨後の前記シリコンウェーハを、過酸化水素又はオゾンを含む薬液で洗浄し、該洗浄後の前記シリコンウェーハに、４００℃以上７００℃以下の温度で熱処理を行い、その後、前記熱処理後の前記シリコンウェーハに対し、樹脂パッドと砥粒を含む研磨剤とを用い、取り代を５ｎｍ以上１００ｎｍ以下として最終仕上げ研磨を行うことを特徴とするシリコンウェーハの加工方法を提供する。 That is, the present invention is a method for processing a silicon wafer that at least polishes a silicon wafer. The silicon wafer is polished using a resin pad and a polishing agent containing abrasive grains, and after the polishing. The silicon wafer is washed with a chemical solution containing hydrogen peroxide or ozone, and the cleaned silicon wafer is heat-treated at a temperature of 400 ° C. or higher and 700 ° C. or lower, and then the silicon wafer after the heat treatment is subjected to heat treatment. Provided is a method for processing a silicon wafer, which comprises using a resin pad and a polishing agent containing abrasive grains to perform final finish polishing with a removal allowance of 5 nm or more and 100 nm or less.
以下、本発明のシリコンウェーハの加工方法を説明する。図１は、本発明のシリコンウェーハの加工方法の一実施形態を含んだシリコンウェーハ製造工程フロー図である。 Hereinafter, a method for processing a silicon wafer of the present invention will be described. FIG. 1 is a silicon wafer manufacturing process flow chart including an embodiment of the silicon wafer processing method of the present invention.
まず、本発明のシリコンウェーハの加工方法では、シリコンウェーハに対し、樹脂パッドと砥粒を含む研磨剤とを用いて研磨を行う（図１（ｄ））。研磨を施すシリコンウェーハとしては、通常、結晶引き上げ工程（図１（ａ））、スライス工程（図１（ｂ））、研削（ラップ）工程（図１（ｃ））後のシリコンウェーハを用いることができる。 First, in the silicon wafer processing method of the present invention, the silicon wafer is polished using a resin pad and an abrasive containing abrasive grains (FIG. 1 (d)). As the silicon wafer to be polished, a silicon wafer after the crystal pulling step (FIG. 1 (a)), the slicing step (FIG. 1 (b)), and the grinding (wrapping) step (FIG. 1 (c)) is usually used. Can be done.
このようなシリコンウェーハに対して、樹脂パッドと砥粒を含む研磨剤とを用いて研磨を行う（図１（ｄ））。当該研磨は、硬質や軟質の樹脂パッドと砥粒を含む研磨剤とを用いる従来の研磨方法に従って行うことができ、例えば、研磨条件を変更して複数回行う多段研磨とすることができ、軟質パッドと砥粒を含む研磨剤を用いた研磨で終えることが好ましい。研磨剤は、砥粒としてのコロイダルシリカ、アルカリを含むものとすることができる。 Such a silicon wafer is polished using a resin pad and an abrasive containing abrasive grains (FIG. 1 (d)). The polishing can be performed according to a conventional polishing method using a hard or soft resin pad and an abrasive containing abrasive grains. For example, the polishing conditions can be changed to perform multi-stage polishing, which is soft. It is preferable to finish by polishing with an abrasive containing a pad and abrasive grains. The abrasive may contain colloidal silica and alkali as abrasive grains.
次いで、研磨後（好ましくは、軟質パッドと砥粒を含む研磨剤を用いた研磨後）のシリコンウェーハを、過酸化水素又はオゾンを含む薬液で洗浄する（図１（ｅ））。当該洗浄により、シリコンウェーハに残存していた砥粒やパッドから脱落した樹脂等の異物を除去することができると共に、ケミカル酸化膜を形成することにより、例えば搬送時のパーティクル付着を抑制することができる。 Next, the silicon wafer after polishing (preferably after polishing with a soft pad and an abrasive containing abrasive grains) is washed with a chemical solution containing hydrogen peroxide or ozone (FIG. 1 (e)). By the cleaning, foreign substances such as resin that have fallen off from the abrasive grains and pads remaining on the silicon wafer can be removed, and by forming a chemical oxide film, for example, particle adhesion during transportation can be suppressed. it can.
尚、過酸化水素又はオゾンを含む薬液としては、Ｈ２Ｏ２濃度０．１〜５％の過酸化水素水や、オゾン濃度１０〜３０ｐｐｍのオゾン水等が挙げられる。
As the chemical solution containing hydrogen peroxide or ozone,
このような研磨後の洗浄を行わない場合、上記異物（砥粒やパッドから脱落した樹脂等）がウェーハ表面に残存し、それらが後工程である熱処理により不純物としてウェーハ中に拡散してしまう。また、研磨直後にベアシリコンが露出している状態となるため、搬送時のパーティクル等の付着が顕著となってしまう。従って、熱処理後の研磨工程で多くの取り代（数ミクロン以上）が必要となってしまう。 If such cleaning after polishing is not performed, the foreign substances (abrasive grains, resin that has fallen off from the pad, etc.) remain on the wafer surface, and they are diffused into the wafer as impurities by the heat treatment in the subsequent process. In addition, since the bare silicon is exposed immediately after polishing, the adhesion of particles and the like during transportation becomes remarkable. Therefore, a large amount of allowance (several microns or more) is required in the polishing process after the heat treatment.
次いで、洗浄後のシリコンウェーハに、４００℃以上７００℃以下の温度で熱処理を行う（図１（ｆ））。このような、４００℃〜７００℃の低温熱処理は、金属不純物の拡散係数を増大させ、表面に誘起することができる。７００℃より高い温度での高温熱処理では、確かに金属不純物の拡散係数はより増大するものの、ＢＭＤ（Ｂｕｌｋ Ｍｉｃｒｏ Ｄｅｆｅｃｔ）等の酸素析出物の増大や、熱応力による転位の発生がみられる可能性もあり、また生産性、電力消費の面からも望ましくない。尚、低温熱処理は、窒素雰囲気下の常圧で行うことが好ましく、熱処理時間は３０分〜３時間とすることができる。 Next, the cleaned silicon wafer is heat-treated at a temperature of 400 ° C. or higher and 700 ° C. or lower (FIG. 1 (f)). Such a low temperature heat treatment at 400 ° C. to 700 ° C. can increase the diffusion coefficient of metal impurities and induce them on the surface. High-temperature heat treatment at a temperature higher than 700 ° C. does increase the diffusion coefficient of metal impurities, but there is a possibility that oxygen precipitates such as BMD (Bulk Micro Defect) may increase and dislocations may occur due to thermal stress. It is also undesirable in terms of productivity and power consumption. The low temperature heat treatment is preferably performed at normal pressure under a nitrogen atmosphere, and the heat treatment time can be 30 minutes to 3 hours.
その後、熱処理後のシリコンウェーハに対し、樹脂パッドと砥粒を含む研磨剤とを用い、取り代を５ｎｍ以上１００ｎｍ以下として最終仕上げ研磨を行う（図１（ｇ））。樹脂パッドとしては、通常、仕上げ研磨で用いられている軟質樹脂パッドを用いることができ、研磨剤は、砥粒としてのコロイダルシリカ、アルカリを含むものとすることができる。 Then, the silicon wafer after the heat treatment is subjected to final finish polishing using a resin pad and an abrasive containing abrasive grains with a removal allowance of 5 nm or more and 100 nm or less (FIG. 1 (g)). As the resin pad, a soft resin pad usually used for finish polishing can be used, and the abrasive may contain colloidal silica and alkali as abrasive grains.
このような最終仕上げ研磨により、低温熱処理（図１（ｆ））により表面に誘起した金属不純物を除去することができる。そして、本発明においては、最終仕上げ研磨を５ｎｍ以上１００ｎｍ以下の微少量の取り代とすることで、最終仕上げ研磨中に不純物が混入することを防ぐことができる。最終仕上げ研磨における取り代が５ｎｍより少ないと、金属不純物により形成される凹凸を修正できない。また、本発明においては、洗浄（図１（ｅ））により厳重に不純物の抑制管理がされているため、表面に誘起した金属不純物の除去には１００ｎｍ以下の取り代で十分であり、１００ｎｍを超えるとかえってフラットネスの悪化が顕著となってしまう。 By such final finish polishing, metal impurities induced on the surface by low temperature heat treatment (FIG. 1 (f)) can be removed. Then, in the present invention, by setting the final finish polishing as a small amount of allowance of 5 nm or more and 100 nm or less, it is possible to prevent impurities from being mixed during the final finish polishing. If the allowance in the final finish polishing is less than 5 nm, the unevenness formed by the metal impurities cannot be corrected. Further, in the present invention, since impurities are strictly suppressed and controlled by cleaning (FIG. 1 (e)), a allowance of 100 nm or less is sufficient for removing metal impurities induced on the surface, and 100 nm is used. If it exceeds the limit, the deterioration of flatness becomes remarkable.
このように、本発明においては、低温熱処理後に、取り代を５ｎｍ以上１００ｎｍ以下とした最終仕上げ研磨を行うことにより、低温熱処理後の金属混入を抑制しつつ、低温熱処理により表面に誘起した金属不純物を除去することができる。 As described above, in the present invention, after the low-temperature heat treatment, the final finish polishing with a removal allowance of 5 nm or more and 100 nm or less is performed to suppress metal contamination after the low-temperature heat treatment, and metal impurities induced on the surface by the low-temperature heat treatment. Can be removed.
一方、スライス工程後のウェーハ加工プロセスの早いうち（例えば、研磨工程前）に低温熱処理を行うと、その後の加工プロセス（例えば、研磨工程）で金属不純物を導入してしまう。また、全加工工程後（例えば、最終仕上げ研磨後）に低温熱処理を行うと、金属不純物を表面に誘起しただけで除去できておらず、また金属不純物が作る凹凸も平坦化できないため、ＬＬＳ欠陥として認識されてしまう。 On the other hand, if low-temperature heat treatment is performed early in the wafer processing process after the slicing process (for example, before the polishing process), metal impurities are introduced in the subsequent processing process (for example, polishing process). In addition, if low-temperature heat treatment is performed after the entire processing process (for example, after final finish polishing), metal impurities are only induced on the surface and cannot be removed, and the irregularities created by the metal impurities cannot be flattened, resulting in LLS defects. Will be recognized as.
以下、実施例及び比較例を示して本発明をより具体的に説明するが、本発明はこれらの実施例に限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.
（実施例１〜８、比較例１〜１２）
軟質樹脂パッドと、コロイダルシリカ、アルカリを含む研磨剤とを用いて、研磨ヘッドの回転数及び押圧を３０ｒｐｍ、２０ｋＰａで研磨した後のウェーハを、薬液で洗浄した後、窒素雰囲気下で表１に示す様々な温度で３０分熱処理を行った。その後、取り代を０ｎｍ、５ｎｍ、１５ｎｍとして最終仕上げ研磨を行い、ＬＬＳ欠陥数の評価を行った。尚、薬液はアンモニア水と過酸化水素水の混合液を用いた。最終仕上げ研磨は軟質樹脂パッドにコロイダルシリカ、アルカリを含む研磨剤で、３０ｒｐｍ、２０ｋＰａで行った。ＬＬＳ欠陥数の評価はＫＬＡテンコール社製表面欠陥検出器ＳＰ３を用いて行った。
(Examples 1 to 8 and Comparative Examples 1 to 12)
The wafer after polishing the polishing head at 30 rpm and 20 kPa using a soft resin pad and an abrasive containing colloidal silica and alkali was washed with a chemical solution and then shown in Table 1 under a nitrogen atmosphere. Heat treatment was performed for 30 minutes at the various temperatures shown. Then, the final finish polishing was performed with the removal allowances set to 0 nm, 5 nm, and 15 nm, and the number of LLS defects was evaluated. As the chemical solution, a mixed solution of ammonia water and hydrogen peroxide solution was used. The final finish polishing was performed with a polishing agent containing colloidal silica and alkali on a soft resin pad at 30 rpm and 20 kPa. The number of LLS defects was evaluated using a surface defect detector SP3 manufactured by KLA Corporation.
実施例、比較例の熱処理温度、熱処理後の研磨取り代（最終仕上げ研磨取り代）を表１に、ＬＬＳ欠陥数の評価結果を図３に示す。低温熱処理を行っていない比較例１〜３、熱処理を２００℃で行った比較例４〜６ではＬＬＳが改善していないのに対し、熱処理温度を４００℃〜７００℃で行い、なおかつその後５ｎｍ以上研磨を行った実施例１〜８では良好なＬＬＳ欠陥数結果となり、図４のような金属汚染によるＬＬＳ欠陥は見られなかった。また、熱処理後に研磨を行わなかった比較例７〜９（即ち、取り代０ｎｍ）では、ＬＬＳが改善していなかった。また、１０００℃で熱処理を行った比較例１０〜１２では逆に悪化してしまった。 Table 1 shows the heat treatment temperature of Examples and Comparative Examples, and the polishing removal allowance (final finish polishing removal allowance) after the heat treatment, and FIG. 3 shows the evaluation results of the number of LLS defects. In Comparative Examples 1 to 3 in which the low temperature heat treatment was not performed and Comparative Examples 4 to 6 in which the heat treatment was performed at 200 ° C., the LLS was not improved, whereas the heat treatment temperature was 400 ° C. to 700 ° C. and then 5 nm or more. In Examples 1 to 8 where polishing was performed, a good LLS defect number result was obtained, and no LLS defect due to metal contamination as shown in FIG. 4 was observed. Further, in Comparative Examples 7 to 9 (that is, the removal allowance 0 nm) in which polishing was not performed after the heat treatment, the LLS was not improved. On the contrary, in Comparative Examples 10 to 12 in which the heat treatment was performed at 1000 ° C.
上記結果から、研磨後のウェーハを洗浄し、その後４００〜７００℃で熱処理を行い、更にその後５ｎｍ以上１００ｎｍ以下の取り代で最終仕上げ研磨を行うことによって、金属不純物及び金属不純物起因の欠陥を抑制することができ、良好なＬＬＳレベルを達成することができた。 Based on the above results, the wafer after polishing is washed, then heat-treated at 400 to 700 ° C., and then final finish polishing is performed with a allowance of 5 nm or more and 100 nm or less to suppress metal impurities and defects caused by metal impurities. And was able to achieve good LLS levels.
なお、本発明は、上記実施形態に限定されるものではない。上記実施形態は、例示であり、本発明の特許請求の範囲に記載された技術的思想と実質的に同一な構成を有し、同様な作用効果を奏するものは、いかなるものであっても本発明の技術的範囲に包含される。
The present invention is not limited to the above embodiment. The above embodiment is an example, and any one having substantially the same configuration as the technical idea described in the claims of the present invention and exhibiting the same effect and effect is the present invention. It is included in the technical scope of the invention.
Claims (1)
前記シリコンウェーハに対し、樹脂パッドと砥粒を含む研磨剤とを用いて研磨を行い、
該研磨後の前記シリコンウェーハを、過酸化水素又はオゾンを含む薬液で洗浄し、
該洗浄後の前記シリコンウェーハに、４００℃以上７００℃以下の温度で熱処理を行って金属不純物を表面に誘起し、
その後、前記熱処理後の前記シリコンウェーハに対し、樹脂パッドと砥粒を含む研磨剤とを用い、取り代を５ｎｍ以上１００ｎｍ以下として最終仕上げ研磨を行うことによって、前記熱処理工程により前記表面に誘起した金属不純物を除去することを特徴とするシリコンウェーハの加工方法。 A silicon wafer processing method that at least polishes a silicon wafer.
The silicon wafer is polished with a resin pad and an abrasive containing abrasive grains.
The polished silicon wafer is washed with a chemical solution containing hydrogen peroxide or ozone.
On the silicon wafer after the washing, to induce the metal impurities on the surface I line heat treatment at a temperature of 700 ° C. 400 ° C. or higher,
Then, with respect to the silicon wafer after the heat treatment, induction using a polishing agent containing resin pad and abrasive grains, the final finish polishing the allowance as 5nm or 100nm or less by the row Ukoto, to the surface by the heat treatment step A method for processing a silicon wafer, which comprises removing metal impurities.
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