JP5964182B2 - Processing method by cluster - Google Patents

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JP5964182B2
JP5964182B2 JP2012189770A JP2012189770A JP5964182B2 JP 5964182 B2 JP5964182 B2 JP 5964182B2 JP 2012189770 A JP2012189770 A JP 2012189770A JP 2012189770 A JP2012189770 A JP 2012189770A JP 5964182 B2 JP5964182 B2 JP 5964182B2
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吉野 裕
裕 吉野
小池 国彦
国彦 小池
武彦 妹尾
武彦 妹尾
松尾 二郎
二郎 松尾
利夫 瀬木
利夫 瀬木
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Iwatani Corp
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
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    • H01L21/04Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/302Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23FNON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F1/00Etching metallic material by chemical means
    • BPERFORMING OPERATIONS; TRANSPORTING
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    • B81C1/00436Shaping materials, i.e. techniques for structuring the substrate or the layers on the substrate
    • B81C1/00523Etching material
    • B81C1/00531Dry etching
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
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    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02041Cleaning
    • H01L21/02043Cleaning before device manufacture, i.e. Begin-Of-Line process
    • H01L21/02046Dry cleaning only
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/302Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
    • H01L21/306Chemical or electrical treatment, e.g. electrolytic etching
    • H01L21/3065Plasma etching; Reactive-ion etching
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B81MICROSTRUCTURAL TECHNOLOGY
    • B81CPROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C2201/00Manufacture or treatment of microstructural devices or systems
    • B81C2201/01Manufacture or treatment of microstructural devices or systems in or on a substrate
    • B81C2201/0101Shaping material; Structuring the bulk substrate or layers on the substrate; Film patterning
    • B81C2201/0128Processes for removing material
    • B81C2201/013Etching
    • B81C2201/0132Dry etching, i.e. plasma etching, barrel etching, reactive ion etching [RIE], sputter etching or ion milling

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Description

本発明は、反応性ガスから生成した反応性クラスタにより試料表面のエッチングやクリーニングなどを行う加工方法に関する技術である。   The present invention relates to a technique relating to a processing method for performing etching or cleaning of a sample surface by a reactive cluster generated from a reactive gas.

本出願人らは、試料のエッチングやクリーニングを行うに当たり、クラスタイオンを用いた場合の課題を解決する方法として、中性の反応性クラスタを用いる方法を提案している(例えば、特許文献1参照)。   The present applicants have proposed a method using neutral reactive clusters as a method for solving the problems in the case of using cluster ions in etching and cleaning of a sample (see, for example, Patent Document 1). ).

WO/2010/021265号公報WO / 2010/021265

特許文献1に記載された従来の技術は、反応性ガスと、前記反応性ガスと不活性であってそれよりも低沸点の添加ガスとを用いて中性の反応性クラスタを生成することにより、反応性クラスタが試料に衝突し、試料表面と反応することにより、試料表面を異方性加工することができ、イオン化していない電気的中性のクラスタであるため、試料への電気的な損傷を与えない利点を有する。
しかしながら、この加工方法は、例えばエッチングレートなどの加工性能が低いという課題がある。
The conventional technique described in Patent Document 1 generates a neutral reactive cluster by using a reactive gas, and the reactive gas and an additive gas that is inert and has a lower boiling point than that. Because the reactive cluster collides with the sample and reacts with the sample surface, the sample surface can be anisotropically processed and is an electrically neutral cluster that is not ionized. Has the advantage of not damaging.
However, this processing method has a problem that processing performance such as an etching rate is low.

一般的に、クラスタの加工性能を高くするには、クラスタ生成前の反応性ガスの濃度を高めたり、供給圧力を高めたりすることが考えられるが、沸点の高い反応性ガスの場合、ノズルまでの供給路内で液化分離してノズルでの断熱膨張によるクラスタの生成が妨げられるので、このような方法には限界があった。
また、大面積を処理する場合、複数本のノズルを用いることが考えられるが、ノズルの本数を増やせば、その分だけガス供給量が多くなる。そうすると、真空処理室内の真空状態を維持するために多量のガスを排気しなければならないが、排気能力の制約から限界があるし、ノズル1本当たりの加工能力が低下することにもなる。このように、加工の目的によっては、少ないガス供給量で所望の加工性能を確保することが求められる場合もある。
Generally, in order to increase the processing performance of the cluster, it is possible to increase the concentration of the reactive gas before cluster generation or increase the supply pressure. Such a method has a limit because the formation of clusters due to adiabatic expansion at the nozzle is prevented by liquefaction and separation in the supply path.
Further, when processing a large area, it is conceivable to use a plurality of nozzles. However, if the number of nozzles is increased, the amount of gas supply increases accordingly. Then, a large amount of gas must be exhausted in order to maintain the vacuum state in the vacuum processing chamber. However, there is a limit due to the limitation of the exhaust capability, and the processing capability per nozzle is also reduced. As described above, depending on the purpose of processing, it may be required to secure desired processing performance with a small gas supply amount.

本発明は、中性のクラスタによる異方性エッチングにおいて、特許文献1に記載の従来例では、中性のクラスタによる試料の加工性能が低いという課題を解決しようとするものであり、少ない流量で優れた加工性能を発揮し得る試料の加工方法を提供することを目的としている。   The present invention intends to solve the problem that the processing performance of a sample due to a neutral cluster is low in the conventional example described in Patent Document 1 in anisotropic etching using a neutral cluster. It aims at providing the processing method of the sample which can exhibit the outstanding processing performance.

請求項1に係る本発明のクラスタによる加工方法は、三フッ化塩素からなる反応性ガスと、アルゴンからなる第一の不活性ガスと、キセノンからなる第二の不活性ガスとの3種の混合ガスを、ノズルから断熱膨張させながら真空処理室内に噴出させて生成した反応性クラスタにより試料表面を加工する方法であって、前記ノズル入口における前記混合ガスは、圧力を0.4MPa(abs)(絶対圧基準)以上とし、前記反応性ガスの混合割合を3容積%以上10容積%以下とし、前記第一の不活性ガスの混合割合を40容積%以上94容積%以下とし、前記第二の不活性ガスの混合割合を3容積%以上50容積%以下としたものである。   The processing method using the cluster according to the first aspect of the present invention includes three types of a reactive gas composed of chlorine trifluoride, a first inert gas composed of argon, and a second inert gas composed of xenon. A method of processing a sample surface by a reactive cluster generated by ejecting a mixed gas from a nozzle while adiabatically expanding into a vacuum processing chamber, wherein the mixed gas at the nozzle inlet has a pressure of 0.4 MPa (abs) (Absolute pressure standard) or more, the mixing ratio of the reactive gas is 3 volume% or more and 10 volume% or less, the mixing ratio of the first inert gas is 40 volume% or more and 94 volume% or less, and the second The mixing ratio of the inert gas is 3 vol% or more and 50 vol% or less.

請求項2に係る本発明のクラスタによる加工方法は、請求項1に係る本発明の構成に加え、前記ノズル入口における前記混合ガスについて、圧力を0.6MPa(abs)以上とし、前記反応性ガスの混合割合を5容積%以上7容積%以下とし、前記第一の不活性ガスの混合割合を43容積%以上89容積%以下とし、前記第二の不活性ガスの混合割合を6容積%以上50容積%以下としたものである。   In addition to the structure of the present invention according to claim 1, the processing method using the cluster according to the present invention of claim 2 is such that the pressure of the mixed gas at the nozzle inlet is 0.6 MPa (abs) or more, and the reactive gas The mixing ratio of the first inert gas is 43 volume% or more and 89 volume% or less, and the mixing ratio of the second inert gas is 6 volume% or more. 50% by volume or less.

請求項1に係る本発明のクラスタによる加工方法は、ノズル入口における混合ガスの圧力及び反応性ガスの濃度を一定範囲とし、かつ、不活性ガスとしてアルゴンとキセノンの2種を用いるようにしたから、少ない流量で優れた加工性能を発揮させることができるのである。   In the processing method using the cluster according to the first aspect of the present invention, the pressure of the mixed gas and the concentration of the reactive gas at the nozzle inlet are in a certain range, and two kinds of argon and xenon are used as the inert gas. Therefore, excellent processing performance can be exhibited with a small flow rate.

請求項2に係る本発明のクラスタによる加工方法は、請求項1に係る本発明の効果に加え、特に深さ方向での加工性能に優れているため、微細加工など、高いアスペクト比が要求される用途に極めて有用である。   In addition to the effect of the present invention according to claim 1, the processing method using the cluster according to the present invention according to claim 2 is particularly excellent in processing performance in the depth direction, and thus requires a high aspect ratio such as micromachining. It is extremely useful for applications.

本発明のクラスタによる加工方法の概略を示す概略説明図である。It is a schematic explanatory drawing which shows the outline of the processing method by the cluster of this invention. 本発明のクラスタによる加工方法におけるキセノン混合割合と試料表面のエッチングレート(重量基準)との関係を表わした図である。It is a figure showing the relationship between the mixing ratio of a xenon and the etching rate (weight basis) of the sample surface in the processing method by the cluster of this invention. 本発明のクラスタによる加工方法におけるキセノン混合割合と試料表面のエッチングレート(深さ基準)との関係を表わした図である。It is a figure showing the relationship between the xenon mixing ratio and the etching rate (depth reference | standard) of a sample surface in the processing method by the cluster of this invention. 本発明のクラスタによる加工方法における混合ガス流量と試料表面のエッチングレート(深さ基準)との関係を表わした図である。It is a figure showing the relationship between the mixed gas flow rate and the etching rate ( depth reference | standard) of the sample surface in the processing method by the cluster of this invention. 本発明のクラスタによる加工方法における混合ガス流量と試料表面のエッチングレート(重量基準)との関係を表わした図である。It is a figure showing the relationship between the mixed gas flow rate in the processing method by the cluster of this invention, and the etching rate ( weight basis) of the sample surface.

以下、本発明の実施の形態を添付した図面を参照して詳細に説明する。
本発明の実施の形態に係るクラスタによる加工方法を図1の概略説明図を参照しながら説明する。
DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
A processing method using clusters according to an embodiment of the present invention will be described with reference to the schematic explanatory diagram of FIG.

図1において、1は混合ガス供給路、2はノズル、3は真空処理室、4は試料である。
混合ガス供給路1に、ガスシリンダー11が、減圧機能を有する圧力調整弁12、流量計13及び圧力計14を介して接続されている。
In FIG. 1, 1 is a mixed gas supply path, 2 is a nozzle, 3 is a vacuum processing chamber, and 4 is a sample.
A gas cylinder 11 is connected to the mixed gas supply path 1 via a pressure regulating valve 12 having a pressure reducing function, a flow meter 13 and a pressure gauge 14.

ガスシリンダー11としては、反応性ガスと、第一の不活性ガスと、第二の不活性ガスとを予め定めた割合で混合した混合ガス15を所定の圧力で容器に収納して供給する場合や、反応性ガスと、第一の不活性ガスと、第二の不活性ガスとを別個の容器に収容して、予め定めた混合比率となるよう調整しながら混合ガス15を供給する場合がある。
反応性ガスは三フッ化塩素である。この三フッ化塩素は珪素との反応性が高いので、試料表面41が珪素単結晶である場合に特に有効である。
そして、反応性クラスタを生成するためには、所定の圧力が必要であるが、上記反応性ガスは沸点が高く、圧力を高くすると凝縮(液化)してノズルでの断熱膨張ができないため、反応性ガスのみから反応性クラスタを生成するための必要な圧力を得ることができなかったのである。
As the gas cylinder 11, a mixed gas 15 obtained by mixing a reactive gas, a first inert gas, and a second inert gas at a predetermined ratio is stored in a container and supplied at a predetermined pressure. Or, the reactive gas, the first inert gas, and the second inert gas may be housed in separate containers, and the mixed gas 15 may be supplied while adjusting to a predetermined mixing ratio. is there.
The reactive gas is chlorine trifluoride. Since this chlorine trifluoride has high reactivity with silicon, it is particularly effective when the sample surface 41 is a silicon single crystal.
In order to generate a reactive cluster, a predetermined pressure is required. However, the reactive gas has a high boiling point, and if the pressure is increased, it is condensed (liquefied) and cannot be adiabatically expanded at the nozzle. The pressure required to generate reactive clusters from only the reactive gas could not be obtained.

そこで、反応性ガスに対して、不活性ガスを添加して混合することにより、上記反応性ガスの分圧を低下させ、反応性ガスの液化を防止しながら、反応性クラスタを生成するのに充分な一次圧力を得ることができるようにするのである。
本発明では、不活性ガスとして、アルゴンからなる第一の不活性ガスと、キセノンからなる第二の不活性ガスを用いる。
これらの第一の不活性ガス、第二の不活性ガスは、いずれも、ガスシリンダー11内及び混合ガス供給路1内で、反応性ガスと不活性なものである。従って、これらの第一の不活性ガス、第二の不活性ガスは、ガスシリンダー11内や混合ガス供給路1内で反応性ガスと反応せず、反応性クラスタの安定的な生成が可能であり、試料表面41の加工を阻害しない。
Therefore, by adding an inert gas to the reactive gas and mixing it, the partial pressure of the reactive gas is reduced and the reactive gas is prevented from being liquefied while generating a reactive cluster. A sufficient primary pressure can be obtained.
In the present invention, as the inert gas, a first inert gas composed of argon and a second inert gas composed of xenon are used.
These first inert gas and second inert gas are both inactive with the reactive gas in the gas cylinder 11 and the mixed gas supply path 1. Therefore, the first inert gas and the second inert gas do not react with the reactive gas in the gas cylinder 11 or the mixed gas supply path 1, and the reactive clusters can be stably generated. Yes, the processing of the sample surface 41 is not hindered.

ここで、加工処理は、反応性クラスタと試料表面との反応によるものであるから、加工処理の実質的な主体は反応性クラスタであって、不活性ガスは、上述のごとく、反応性ガスの分圧を低下させ、反応性ガスの液化を防止しながら、反応性クラスタを生成するのに充分な一次圧力を得るためのものに過ぎないとの理解に立てば、不活性ガスについて重要なのはその分圧のみであって、如何なる不活性ガスを用いるべきかは重要でないはずである。
しかし、本発明者の実験的検証によれば、アルゴンからなる第一の不活性ガスとともにキセノンからなる第二の不活性ガスを併用することにより、加工性能が向上することが分かったのである(後述する実施例も参照)。
Here, since the processing is due to the reaction between the reactive cluster and the sample surface, the substantial main body of the processing is the reactive cluster, and the inert gas is the reactive gas as described above. What is important about an inert gas is that it can only be used to reduce the partial pressure and prevent liquefaction of the reactive gas while still obtaining sufficient primary pressure to produce reactive clusters. It should only be partial pressure, and what inert gas should be used should not be important.
However, according to the inventor's experimental verification, it was found that the processing performance is improved by using a second inert gas composed of xenon together with a first inert gas composed of argon ( (See also Examples below).

本発明では、混合ガス15中の反応性ガスの混合割合を3容積%以上10容積%以下とし、混合ガス15中の第一の不活性ガスの混合割合を40容積%以上94容積%以下とし、混合ガス15中の第二の不活性ガスの混合割合を3容積%以上50容積%以下としている。
反応性ガスの混合割合が3容積%未満では、反応性ガスと試料との反応が不十分となり、10容積%を超えると、反応性ガスの液化が生じるおそれがある。好ましくは、5容積%以上7容積%以下である。
第一の不活性ガスの混合割合が40容積%未満では、相対的に反応性ガス及び第二の不活性ガスの各混合割合が多くなり、また、94容積%を超えると、相対的に反応性ガス及び第二の不活性ガスの各混合割合が少なくなるので、いずれの場合も反応性ガス及び第二の不活性ガスの各混合割合を所定の範囲内に設定することが困難となる。好ましくは、43容積%以上89容積%以下である。
第二の不活性ガスの混合割合が3容積%未満では、第二の不活性ガスを添加した効果が十分に得られず、反応性ガスと試料との反応が不十分となり、50容積%を超えると、キセノンが比較的高価であるため、コスト高となり、実用性が損なわれる。好ましくは、6容積%以上50容積%以下であり、この範囲では、特に深さ方向での加工性能に優れたものとなる。
In the present invention, the mixing ratio of the reactive gas in the mixed gas 15 is 3 volume% or more and 10 volume% or less, and the mixing ratio of the first inert gas in the mixed gas 15 is 40 volume% or more and 94 volume% or less. The mixing ratio of the second inert gas in the mixed gas 15 is 3% by volume or more and 50% by volume or less.
When the mixing ratio of the reactive gas is less than 3% by volume, the reaction between the reactive gas and the sample is insufficient, and when it exceeds 10% by volume, the reactive gas may be liquefied. Preferably, they are 5 volume% or more and 7 volume% or less.
When the mixing ratio of the first inert gas is less than 40% by volume, the mixing ratio of the reactive gas and the second inert gas is relatively increased. When the mixing ratio exceeds 94% by volume, the reaction is relatively performed. Since the mixing ratio of the reactive gas and the second inert gas is reduced, it is difficult to set the mixing ratio of the reactive gas and the second inert gas within a predetermined range in any case. Preferably, they are 43 to 89 volume%.
When the mixing ratio of the second inert gas is less than 3% by volume, the effect of adding the second inert gas cannot be sufficiently obtained, and the reaction between the reactive gas and the sample becomes insufficient, and 50% by volume is reduced. If it exceeds, xenon is relatively expensive, resulting in high cost and impairing practicality. Preferably, the content is 6% by volume or more and 50% by volume or less, and in this range, the processing performance is particularly excellent in the depth direction.

本発明では、また、一定の加工性能を確保するために、混合ガス15のノズル入口21での圧力を0.4MPa(abs)以上としている。0.4MPa(abs)未満では、反応性クラスタの生成が困難となる。好ましくは、0.6MPa(abs)以上であり、さらに好ましくは0.8MPa(abs)以上である。混合ガス15のノズル入口21での圧力の上限としては、特に限定されないが、装置への過大な負荷や反応性ガスの液化を防止する観点から、例えば、1MPa(abs)以下とするのが好ましい。   In the present invention, the pressure of the mixed gas 15 at the nozzle inlet 21 is set to 0.4 MPa (abs) or more in order to ensure a certain processing performance. If it is less than 0.4 MPa (abs), it becomes difficult to generate reactive clusters. Preferably, it is 0.6 MPa (abs) or more, more preferably 0.8 MPa (abs) or more. The upper limit of the pressure of the mixed gas 15 at the nozzle inlet 21 is not particularly limited, but it is preferably set to 1 MPa (abs) or less, for example, from the viewpoint of preventing an excessive load on the apparatus and liquefaction of the reactive gas. .

次に、上記混合ガス15をノズル2から断熱膨張させながら真空処理室3内に噴出する点について説明する。
まず、真空処理室3には、開閉弁31、ターボ分子ポンプ32及びドライポンプ33を介設した排気路35を接続しており、ターボ分子ポンプ32及びドライポンプ33により真空処理室3内を約10Pa(abs)の二次圧力としている。排気路35には、さらに除害部34が接続しており、排気ガスを無害化して放出するようにしている。
真空処理室3内の圧力は、圧力計36によって測定される。
Next, the point that the mixed gas 15 is ejected into the vacuum processing chamber 3 while adiabatically expanding from the nozzle 2 will be described.
First, the vacuum processing chamber 3 is connected to an exhaust passage 35 provided with an on-off valve 31, a turbo molecular pump 32 and a dry pump 33. The secondary pressure is 10 Pa (abs). The exhaust path 35 is further connected with a detoxifying section 34 so that the exhaust gas is rendered harmless and discharged.
The pressure in the vacuum processing chamber 3 is measured by a pressure gauge 36.

ノズル2は、ノズル入口21での一次圧力、例えば0.68MPa(abs)と真空処理室3内の二次圧力、例えば10Pa(abs)との差圧で、混合ガス15の断熱膨張により反応性クラスタ37を生成できる開口とするのである。
そして、本発明は、反応性クラスタ37の加工性能を高くするために、反応性ガスと、第一の不活性ガスと、第二の不活性ガスとの3種の混合ガス15を、ノズル出口22から断熱膨張させながら真空処理室3内に噴出させて、中性の反応性クラスタ37を生成するのである。
The nozzle 2 has a differential pressure between a primary pressure at the nozzle inlet 21, for example, 0.68 MPa (abs) and a secondary pressure in the vacuum processing chamber 3, for example, 10 Pa (abs), and is reactive by adiabatic expansion of the mixed gas 15. The openings that can generate the clusters 37 are used.
In the present invention, in order to improve the processing performance of the reactive cluster 37, three kinds of mixed gases 15 of the reactive gas, the first inert gas, and the second inert gas are supplied to the nozzle outlet. The neutral reactive clusters 37 are generated by being ejected into the vacuum processing chamber 3 while being adiabatically expanded from 22.

このようにして生成した中性の反応性クラスタ37を真空処理室3内の試料表面41に噴射して試料表面41を高速で異方性加工するのである。
なお、42は試料4を所定位置に固定する試料台である。
The neutral reactive cluster 37 generated in this way is sprayed onto the sample surface 41 in the vacuum processing chamber 3 to anisotropically process the sample surface 41 at a high speed.
Reference numeral 42 denotes a sample stage for fixing the sample 4 at a predetermined position.

ここで、下記の実施例により、不活性ガスとして、アルゴンからなる第一の不活性ガスとキセノンからなる第二の不活性ガスを併用した場合に、加工性能が向上することを確認した。
なお、下記実施例において、エッチングレート(重量基準)は、電子天秤「ER−182A」(A&D社製)を用いて、1分間の加工処理前後における試料の重量を測定して、その差として算出した。また、エッチングレート(深さ基準)は、1分間の加工処理において最も深くエッチングされた部分の深さを表したものであり、60μm未満の場合には接触式段差計「DekTak3」(Veeco社製)を用いて測定し、60μm以上の場合には走査型電子顕微鏡「JSM−7505FS」(JEOL社製)を用いて測定した。
また、混合ガスの流量(sccm)は、流量計13で測定された質量流量の値を、混合ガス中の各ガスの容積割合及び分子量から容積流量に換算して得た値であり、1分間当たりの混合ガスの容積流量である。
Here, according to the following examples, it was confirmed that the processing performance was improved when the first inert gas composed of argon and the second inert gas composed of xenon were used in combination as the inert gas.
In the following examples, the etching rate (weight basis) is calculated as the difference between the weights of samples before and after processing for 1 minute using an electronic balance “ER-182A” (manufactured by A & D). did. Further, the etching rate (depth reference) represents the depth of the deepest etched portion in the processing for 1 minute. When the etching rate is less than 60 μm, the contact-type step meter “DekTak3” (manufactured by Veeco) ) And in the case of 60 μm or more, it was measured using a scanning electron microscope “JSM-7505FS” (manufactured by JEOL).
Further, the flow rate (sccm) of the mixed gas is a value obtained by converting the mass flow rate value measured by the flow meter 13 into the volume flow rate from the volume ratio and molecular weight of each gas in the mixed gas. The volume flow rate of the mixed gas per unit.

(実施例)
真空処理室3内で、反応性クラスタ37で加工される試料表面41を珪素単結晶とし、混合ガス15を三フッ化塩素(ClF3)からなる反応性ガスと、アルゴン(Ar)からなる第一の不活性ガスと、キセノン(Xe)からなる第二の不活性ガスとの3種の混合ガスとした。
(Example)
In the vacuum processing chamber 3, the sample surface 41 processed by the reactive cluster 37 is a silicon single crystal, and the mixed gas 15 is a reactive gas composed of chlorine trifluoride (ClF 3 ) and argon (Ar). Three kinds of mixed gases of one inert gas and a second inert gas made of xenon (Xe) were used.

混合ガス供給路1における混合ガス15の供給圧力(一次圧力)を圧力調整弁12で制御するとともに、真空処理室3内の圧力をターボ分子ポンプ31及びドライポンプ32により約10Pa(abs)の真空とした。
ノズル出口22と試料表面41との距離を13mmとし、反応性クラスタ37を試料表面41に照射する時間を1minとした。
上記操作を、ノズル入口21での混合ガス15の一次圧力、混合ガス15の混合割合を、様々に変えて実施した。
The supply pressure (primary pressure) of the mixed gas 15 in the mixed gas supply path 1 is controlled by the pressure regulating valve 12, and the pressure in the vacuum processing chamber 3 is reduced to about 10 Pa (abs) by the turbo molecular pump 31 and the dry pump 32. It was.
The distance between the nozzle outlet 22 and the sample surface 41 was 13 mm, and the time for irradiating the sample surface 41 with the reactive cluster 37 was 1 min.
The above operation was performed by changing the primary pressure of the mixed gas 15 at the nozzle inlet 21 and the mixing ratio of the mixed gas 15 in various ways.

すなわち、ノズル入口21での混合ガス15の一次圧力を0.40MPa(abs)、0.60MPa(abs)、0.80MPa(abs)又は0.95MPa(abs)とした。また、混合ガス15の混合割合は、三フッ化塩素を6容積%とし、キセノンを0容積%、3容積%、6容積%、50容積%又は94容積%とし、残部をアルゴンとした(3者合計で100容積%)。   That is, the primary pressure of the mixed gas 15 at the nozzle inlet 21 was set to 0.40 MPa (abs), 0.60 MPa (abs), 0.80 MPa (abs), or 0.95 MPa (abs). The mixing ratio of the mixed gas 15 was 6% by volume of chlorine trifluoride, 0% by volume, 3% by volume, 6% by volume, 50% by volume or 94% by volume of xenon, and the balance was argon (3 100% by volume).

混合ガスの組成が同じでノズル入口21での混合ガス15の圧力のみ代える場合には、まず、ガスシリンダー11内に所定の組成で混合ガスを調製し、ガスシリンダー11内の混合ガスの圧力を、最高実験圧力(0.95MPa(abs))よりも高くしておき、圧力調整弁12によって減圧することにより所定の圧力(0.40MPa(abs)、0.60MPa(abs)、0.80MPa(abs)又は0.95MPa(abs))に調整するようにした。
また、異なる組成の混合ガスについて実験を行う際には、別途、組成の異なる混合ガスをガスシリンダー11内に調製して実験を行った。
なお、キセノンが0容積%の場合はアルゴンが94容積%であり、キセノンが94容積%の場合はアルゴンが0容積%であって、いずれも不活性ガスを1種のみ用いるものであるから、これらは本発明の対象ではない。
When the composition of the mixed gas is the same and only the pressure of the mixed gas 15 at the nozzle inlet 21 is changed, first, a mixed gas is prepared in the gas cylinder 11 with a predetermined composition, and the pressure of the mixed gas in the gas cylinder 11 is changed. The predetermined pressure (0.40 MPa (abs), 0.60 MPa (abs), 0.80 MPa (0.80 MPa ( abs) or 0.95 MPa (abs)).
When conducting experiments on mixed gases having different compositions, separately, mixed gases having different compositions were prepared in the gas cylinder 11 for experiments.
Note that when xenon is 0% by volume, argon is 94% by volume, and when xenon is 94% by volume, argon is 0% by volume, both of which use only one kind of inert gas. These are not the subject of the present invention.

図2に、横軸にキセノンの混合割合、縦軸に試料表面41のエッチングレート(重量基準:mg/min)を表したグラフを示す。
図3に、横軸にキセノンの混合割合、縦軸に試料表面41のエッチングレート(深さ基準:μm/min)を表したグラフを示す。
図4に、横軸に混合ガスの流量、縦軸に試料表面41のエッチングレート(深さ基準:μm/min)を表したグラフを示す。
図5に、横軸に混合ガスの流量、縦軸に試料表面41のエッチングレート(重量基準:mg/min)を表したグラフを示す。
FIG. 2 is a graph showing the mixing ratio of xenon on the horizontal axis and the etching rate (weight basis: mg / min) of the sample surface 41 on the vertical axis.
FIG. 3 is a graph in which the horizontal axis represents the mixing ratio of xenon and the vertical axis represents the etching rate of the sample surface 41 (depth reference: μm / min).
FIG. 4 is a graph in which the horizontal axis represents the flow rate of the mixed gas, and the vertical axis represents the etching rate of the sample surface 41 ( depth reference: μm / min).
FIG. 5 is a graph in which the horizontal axis represents the flow rate of the mixed gas and the vertical axis represents the etching rate of the sample surface 41 ( weight basis: mg / min).

図2及び図3によれば、キセノンを添加することにより、加工性能が向上することが分かる。ノズル入口21での混合ガスの圧力が高い方が、加工性能が高くなる傾向が見られる。   2 and 3, it can be seen that the processing performance is improved by adding xenon. There is a tendency that the higher the mixed gas pressure at the nozzle inlet 21, the higher the processing performance.

また、図4及び図5によれば、キセノンの添加により、図2及び図3に示す如き優れた加工性能を、少ない流量で発揮させることができることが分かる。
少ない流量で優れた加工性能が得られるということは、反応効率(投入された反応性ガスのうち、試料の加工に寄与する割合)が高いものであることを示している。
そして、ノズル一本当たりの混合ガスの流量が少なくてすむので、真空処理室3内を真空状態に維持するための排気能力上の制約が軽減され、ノズル本数を増やして混合ガスの流量を増やすことができ、大面積加工などの更なる用途への応用を可能とするものであると言える。
Moreover, according to FIG.4 and FIG.5, by adding xenon, it turns out that the outstanding processing performance as shown in FIG.2 and FIG.3 can be exhibited with a small flow volume.
The fact that excellent processing performance can be obtained with a small flow rate indicates that the reaction efficiency (the ratio of the input reactive gas that contributes to the processing of the sample) is high.
Further, since the flow rate of the mixed gas per nozzle can be reduced, the restriction on the exhaust capability for maintaining the vacuum processing chamber 3 in the vacuum state is reduced, and the flow rate of the mixed gas is increased by increasing the number of nozzles. It can be said that it can be applied to further uses such as large area processing.

図2〜図5に示す結果についてより詳細に検討すると、圧力が0.6MPa(abs)以上であってキセノンの混合割合が6〜50容積%の場合では、特に、深さ基準での加工性能が優れていることが分かり、高いアスペクト比が要求される用途に極めて有用であるといえる。   When the results shown in FIGS. 2 to 5 are examined in more detail, when the pressure is 0.6 MPa (abs) or more and the mixing ratio of xenon is 6 to 50% by volume, the processing performance on the basis of depth is particularly preferable. It can be said that it is extremely useful for applications requiring a high aspect ratio.

圧力(ノズル入口における混合ガスの圧力)が0.6MPa(abs)以上であってキセノンの混合割合が6〜50容積%の場合における深さ方向での優れた効果をより明確化するため、図3に示すグラフの基礎とした具体的数値データについて、下表に示す。   In order to further clarify the excellent effect in the depth direction when the pressure (pressure of the mixed gas at the nozzle inlet) is 0.6 MPa (abs) or more and the mixing ratio of xenon is 6 to 50% by volume, FIG. Specific numerical data based on the graph shown in FIG.

Figure 0005964182
Figure 0005964182

上記表1に示すとおり、0.6MPa(abs)以上の各圧力下において、キセノンの混合割合が0容積%の場合と、キセノンの混合割合が6容積%もしくは50容積%の場合とを対比すると、キセノン混合割合6〜50容積%において、エッチングレート(深さ基準)が大幅に向上していることが分かる。この効果は0.8MPa(abs)以上で特に顕著であることも分かった。   As shown in Table 1, when the mixing ratio of xenon is 0% by volume and the mixing ratio of xenon is 6% by volume or 50% by volume under each pressure of 0.6 MPa (abs) or more, It can be seen that the etching rate (depth reference) is greatly improved at a xenon mixing ratio of 6 to 50% by volume. It was also found that this effect is particularly remarkable at 0.8 MPa (abs) or more.

ところで、キセノン混合割合が3容積%の場合は、深さ基準での加工性能が格別高いわけではないが、この点は必ずしも加工方法として劣っていることを意味するものではなく、広い範囲で浅く加工を行いたい場合など、むしろ好ましい場合もある。すなわち、本発明の加工方法は、アルゴンとキセノンの2種の不活性ガスを用いることによって反応性クラスタの加工性能が変化することを見出した点に技術的価値があると見ることもできるのである。   By the way, when the mixing ratio of xenon is 3% by volume, the processing performance on the depth basis is not particularly high, but this does not necessarily mean that the processing method is inferior, and is shallow in a wide range. In some cases, such as when processing is desired. That is, the processing method of the present invention can be regarded as technically valuable in that it has been found that the processing performance of the reactive cluster is changed by using two kinds of inert gases, argon and xenon. .

キセノンを94容積%添加した場合には、重量基準でのエッチングレートは高いが、キセノンが高価であるため、実用上有利とはいえない。また、深さ基準でのエッチングレートについてみれば、アルゴンとキセノンとを併用した本発明の加工方法よりも性能が低いことが分かる。   When 94% by volume of xenon is added, the etching rate based on weight is high, but it is not practically advantageous because xenon is expensive. Moreover, when it sees about the etching rate on a depth reference | standard, it turns out that performance is lower than the processing method of this invention which used argon and xenon together.

なお、本発明において、三フッ化塩素からなる反応性ガスの混合割合は、液化を起こすことなく一定の加工性能を得る観点から調整されるものである。そして、三フッ化塩素からなる反応性ガスの混合割合が6容積%である上記実施例の結果と、三フッ化塩素の沸点や試料との反応性から、経験上、3容積%以上10容積%以下の混合割合でも、液化を起こすことなく一定の加工性能を確保しつつ、アルゴンとキセノンの併用による加工性能向上の効果が得られることが推察される。   In the present invention, the mixing ratio of the reactive gas composed of chlorine trifluoride is adjusted from the viewpoint of obtaining a certain processing performance without causing liquefaction. From experience, the mixing ratio of the reactive gas composed of chlorine trifluoride is 6% by volume, the boiling point of chlorine trifluoride, and the reactivity with the sample. It is presumed that the effect of improving the processing performance by the combined use of argon and xenon can be obtained even when the mixing ratio is not more than%, while ensuring a certain processing performance without causing liquefaction.

1 混合ガス供給路
2 ノズル
3 真空処理室
4 試料
15 混合ガス
21 ノズル入口
22 ノズル出口
37 反応性クラスタ
41 試料表面
DESCRIPTION OF SYMBOLS 1 Mixed gas supply path 2 Nozzle 3 Vacuum processing chamber 4 Sample 15 Mixed gas 21 Nozzle inlet 22 Nozzle outlet 37 Reactive cluster 41 Sample surface

Claims (4)

三フッ化塩素からなる反応性ガスと、アルゴンからなる第一の不活性ガスと、キセノンからなる第二の不活性ガスとの3種の混合ガスを、ノズルから断熱膨張させながら真空処理室内に噴出させて生成した反応性クラスタにより試料表面を加工する方法であって、
前記ノズル入口における前記混合ガスは、圧力を0.4MPa(abs)以上とし、前記反応性ガスの混合割合を3容積%以上10容積%以下とし、前記第一の不活性ガスの混合割合を40容積%以上94容積%以下とし、前記第二の不活性ガスの混合割合を3容積%以上50容積%以下としたことを特徴とするクラスタによる加工方法。
Three kinds of mixed gases of a reactive gas composed of chlorine trifluoride, a first inert gas composed of argon, and a second inert gas composed of xenon are adiabatically expanded from the nozzle into the vacuum processing chamber. A method of processing a sample surface with reactive clusters generated by jetting,
The mixed gas at the nozzle inlet has a pressure of 0.4 MPa (abs) or more, a mixing ratio of the reactive gas of 3% by volume to 10% by volume, and a mixing ratio of the first inert gas of 40%. A processing method using a cluster, wherein the volume ratio is not less than 94% by volume and the mixing ratio of the second inert gas is not less than 3% by volume and not more than 50% by volume.
前記ノズル入口における前記混合ガスは、圧力を0.6MPa(abs)以上とし、前記反応性ガスの混合割合を5容積%以上7容積%以下とし、前記第一の不活性ガスの混合割合を43容積%以上89容積%以下とし、前記第二の不活性ガスの混合割合を6容積%以上50容積%以下としたことを特徴とする請求項1に記載のクラスタによる加工方法。   The mixed gas at the nozzle inlet has a pressure of 0.6 MPa (abs) or more, a mixing ratio of the reactive gas of 5% by volume to 7% by volume, and a mixing ratio of the first inert gas of 43%. 2. The processing method using clusters according to claim 1, wherein the volume ratio is not less than 89% by volume and the mixing ratio of the second inert gas is not less than 6% and not more than 50% by volume. 前記ノズル入口における前記混合ガスの圧力が、0.4MPa(abs)以上0.95MPa(abs)以下である、請求項1に記載のクラスタによる加工方法。The processing method by a cluster according to claim 1, wherein the pressure of the mixed gas at the nozzle inlet is 0.4 MPa (abs) or more and 0.95 MPa (abs) or less. 前記ノズル入口における前記混合ガスの圧力が、0.8MPa(abs)以上0.95MPa(abs)以下である、請求項1に記載のクラスタによる加工方法。The processing method by a cluster according to claim 1, wherein the pressure of the mixed gas at the nozzle inlet is 0.8 MPa (abs) or more and 0.95 MPa (abs) or less.
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