KR100340589B1 - Increasing method of electron lifetime in silicon wafer - Google Patents

Increasing method of electron lifetime in silicon wafer Download PDF

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KR100340589B1
KR100340589B1 KR1019970073933A KR19970073933A KR100340589B1 KR 100340589 B1 KR100340589 B1 KR 100340589B1 KR 1019970073933 A KR1019970073933 A KR 1019970073933A KR 19970073933 A KR19970073933 A KR 19970073933A KR 100340589 B1 KR100340589 B1 KR 100340589B1
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heat treatment
temperature
silicon substrate
layer
denude
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KR1019970073933A
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KR19990054148A (en
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김흥락
강성건
류근걸
김동수
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재단법인 포항산업과학연구원
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/324—Thermal treatment for modifying the properties of semiconductor bodies, e.g. annealing, sintering
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02367—Substrates
    • H01L21/0237—Materials
    • H01L21/02373—Group 14 semiconducting materials
    • H01L21/02381—Silicon, silicon germanium, germanium

Abstract

PURPOSE: A method for improving the lifetime of electrons in a silicon substrate is provided to form a denude layer of a desired depth and stabilize the surface thereof in hydride state. CONSTITUTION: A heat treatment is made to a silicon substrate for 20-30 minutes under oxygen atmosphere with maintaining the temperature in the range of 500-800 °C so as to remove organism and contaminated metals. Upon completion of the first heat treatment, the second heat treatment is performed such that the temperature is raised to 900-1100 °C and maintains the substrate under gas mixture atmosphere with the mixture ratio of hydrogen and nitrogen in the range of 1:10-1:100 for 3-8 hours so that a denude layer is formed.

Description

실리콘 기판의 전자수명 증가방법{Increasing method of electron lifetime in silicon wafer}Increasing method of electron lifetime in silicon wafer

본 발명은 반도체소자로 이용되는 실리콘 기판의 전자수명을 향상시키는 방법에 관한 것으로써, 보다 상세하게는 실리콘 기판의 표면에서 일정깊이 부분을 불순물의 없는 디누드층으로 만들어 전자수명을 향상시키는 방법에 관한 것이다.The present invention relates to a method for improving the electron life of a silicon substrate used as a semiconductor device, and more particularly, to a method for improving electron life by making a portion of the surface of the silicon substrate a denude layer free of impurities. It is about.

실리콘 기판은 디램(DRAM) 및 기타 여러 반도체소자의 기본 재료로 그 사용이 지속적으로 증대되고 있다.Silicon substrates continue to increase as a base material for DRAMs and other semiconductor devices.

실리콘 기판은 표면에서 수직으로 수㎛ 이내에 소자가 형성되므로, 이 소자가 형성될 부분은 전기적특성, 즉, 불순물이 없고, 무결함 격자구조가 형성되어 전자수명이 확보될 수 있어야 한다. 이와 같이 전자수명이 증가될 수 있는 표면층의 형성은 결국, 소자의 성능과 직접 연관이 있으므로 표면근처의 실리콘 기판의 특성을 향상시키려는 방법은 반도체 소재 메이커 뿐만 아니라, 소자 메이커에서도 지속적으로 개발하고 있는 실정이다.Since the silicon substrate is formed within several micrometers perpendicular to the surface, the portion on which the element is to be formed should have electrical characteristics, that is, no impurities and a defect-free lattice structure is formed to ensure electron life. Since the formation of the surface layer, which can increase the electron lifetime, is directly related to the performance of the device, a method of improving the characteristics of the silicon substrate near the surface has been continuously developed not only in semiconductor material manufacturers but also in device manufacturers. to be.

지금까지 실리콘 기판의 소수전하 수명을 증가시키는 방법으로는 1)실리콘 기판 표면에 에피층을 증착시키는 방법과 2)열처리를 통한 디누드 영역을 형성시켜 표면에서 수십㎛ 내안에 불순물을 석출시키는 방법 또는 3) 실리콘 기판 뒷면에 미세한 스크래치를 만들어 소자제작층에서 전자수명을 향상시키는 방법등이 있다.Up to now, the method of increasing the minority charge life of a silicon substrate includes 1) a method of depositing an epi layer on the surface of a silicon substrate, and 2) forming a denude region through heat treatment to deposit impurities within a few tens of micrometers from the surface, or 3) There is a method of improving the electron life in the device fabrication layer by making a fine scratch on the back of the silicon substrate.

위에서 언급한 방법들은 현재 널리 사용되고 있으나, 그 제조비 등의 경제적인 측면에서 개선의 여지가 많다. 특히, 상기 1)의 에피층증착 방법은 표면층에 완전 무결하고 불순물이 없는 에피층을 형성하므로 가장 좋은 품질의 기판을 만들 수 있으나, 보통의 기판에 비해 2배이상의 가격으로 제공되므로 가격 경쟁력이 떨어지며, 제조회사마다 그 채용을 주저하고 있는 기술이다.The above-mentioned methods are widely used at present, but there is much room for improvement in terms of economics such as manufacturing cost. In particular, the epi layer deposition method of 1) can make the best quality substrate because the epi layer is completely flawless and free of impurities on the surface layer, but the price is less competitive because it is provided at a price more than twice that of ordinary substrates. In other words, each manufacturer is hesitant to adopt the technology.

그리고, 상기 2)디누드층 형성방법과 3)스크래치 방법은 상대적으로 공정의 간단성 및 경제성이 있으나, 상대적으로 초극미세 소자에 있어서는 완벽한 재현성이 있는 분술물이 없는 실리콘 층의 형성이 어렵다는 단점이 있다.In addition, although the method of forming 2) the dinude layer and the method of 3) scratching are relatively simple and economical in the process, it is relatively difficult to form a silicon layer having a perfectly reproducible fraction in an ultrafine device. have.

그래도 디누드층 형성방법은 공정의 간단성 및 경제적인 잇점으로 실제 많이 이용되고 있다.Nevertheless, the method of forming the denude layer has been widely used because of the simplicity and economic advantages of the process.

종래, 디누드층을 형성하기 위한 열처리는 900℃이상의 고온에서 장시간열처리하는데, 주로 1100℃에서 20시간 열처리하고 있다. 이와 같이 고온에서 장시간 열처리하면 디누드층을 두껍게 할 수 있으나, 필요이상으로 두꺼운 디누드층을 형성하고,또한 고온에서 장시간의 열처리방법으로 제조원가가 상승하는 문제가 있다.Conventionally, the heat treatment for forming the denude layer is for a long time heat treatment at a high temperature of 900 ℃ or more, mainly heat treatment at 1100 ℃ 20 hours. As described above, when the heat treatment is performed at a high temperature for a long time, the denude layer can be thickened, but there is a problem that a thicker denude layer is formed than necessary, and the manufacturing cost increases by a long heat treatment method at a high temperature.

본 발명은 2단계의 열처리공정으로 소자 형성에 필요한 깊이정도만 디누드층을 형성하고, 나아가 표면을 수소화 상태로 안정되게 하여 실리콘 기판의 전자수명을 증가시키는데, 그 목적이 있다.The present invention is to increase the electron life of the silicon substrate by forming a denude layer only to the depth necessary for the element formation in a two-step heat treatment process, and further to stabilize the surface in a hydrogenated state.

도 1은 1차열처리조건과 전자수명과의 관계를 나타내는 그래프이다;1 is a graph showing the relationship between primary heat treatment conditions and electron lifetimes;

도 2는 1차열처리후 2차열처리조건과 전자수명과의 관계를 나타내는 그래프이다;2 is a graph showing the relationship between secondary heat treatment conditions and electron lifetime after primary heat treatment;

도 3은 2차열처리시 수소 및 질소의 비에 따른 전자수명의 관계를 나타내느 그래프이다.3 is a graph showing the relationship of electron life according to the ratio of hydrogen and nitrogen in the secondary heat treatment.

상기 목적을 달성하기 위한 본 발명은, 실리콘 기판의 전자수명을 향상시키는 방법에 있어서, 실리콘 기판을 산소분위기에서 500-800℃의 온도에서 20-30분간 유지하여 유기물 및 금속오염원을 제거하는 1단계 열처리하고, 상기 1단계 열처리 직후 900-1100℃의 온도범위로 승온하고, 수소와 질소의 혼합가스 분위기에서 3-8시간 유지하여 디누드 층을 형성하는 2단계 열처리하는 것을 포함하여 구성된다.In order to achieve the above object, the present invention provides a method for improving the electron life of a silicon substrate, the first step of removing the organic material and metal pollutants by maintaining the silicon substrate at an oxygen atmosphere for 20-30 minutes at a temperature of 500-800 ℃ After the heat treatment, the temperature is raised to a temperature range of 900-1100 ℃ immediately after the first heat treatment, and comprises a two-step heat treatment to form a denude layer by maintaining for 3-8 hours in a mixed gas atmosphere of hydrogen and nitrogen.

이하, 본 발명을 상세히 설명한다.Hereinafter, the present invention will be described in detail.

본 발명은 2단계의 효과적인 열처리 및 분위기 가스제어로 소자가 형성될 수㎛내외의 필요한 두께의 디누드층을 형성하고, 또한, 수소화기로 기판표면을 안정화시키는데, 그 특징이 있다. 즉, 본 발명은 1단계 열처리로 유기, 금속오염원을 제거하고, 이어 2단계 열처리로 산화막의 제거 및 격자결함의 원상복구 등을 통하여 디누등층 및 안정화된 표면을 형성하는 것이다.The present invention is characterized by a two-step effective heat treatment and atmosphere gas control to form a denude layer having a required thickness of about several micrometers, and also to stabilize the substrate surface with a hydrogenation device. That is, the present invention is to remove the organic and metal pollutants in a one-step heat treatment, and then to form a denuene layer and stabilized surface through the removal of the oxide film and the original recovery of the lattice defect by a two-step heat treatment.

이를 위해 우선, 1단계 열처리를 산소분위기에서 500-800℃의 온도에서 20-30분간 유지하여 유기물을 태워서 없애고, 금속오염원은 금속산화물로 표면에 형성하거나 더 기판내(수 ㎛내외 깊이)로 들어가도록 한다.To this end, first of all, heat treatment is carried out in an oxygen atmosphere at a temperature of 500-800 ° C. for 20-30 minutes to remove organic substances, and metal contamination sources are formed on the surface with metal oxides or further into the substrate (a few μm or less). To do that.

이때의 열처리는 유기물을 태우고, 금속오염원을 산화물로서 표면에 형성시키기 위해 산소분위기를 형성한다. 그리고, 열처리온도는 500℃이상하면 산소가스를 활성화시켜 유기물 및 금속오염원을 제거하는데 유용하나, 800℃를 넘으면 표면에 형성된 금속산화물이 다시 기판내부로 들어가거나 깊숙히 들어간 금속오염원이 다시 표면방향으로 나오므로 500-800℃로 하는 것이다. 열처리시간은 충분히 유기물을 태우고 금속오염원을 산화물로 표면에 형성하기 위해 20분이상 하나, 30분을 넘으면 금속산화물이 다시 기판내부로 들어가므로 20-30분으로 한다.The heat treatment at this time forms an oxygen atmosphere in order to burn organic matter and form a metal pollution source as an oxide. And, if the heat treatment temperature is above 500 ℃, it is useful for removing organic substances and metal pollutants by activating oxygen gas.However, if it exceeds 800 ℃, metal oxides formed on the surface enter the substrate again or deeply enter the metal pollutants. Therefore, it is to be 500-800 ℃. The heat treatment time is 20-30 minutes in order to burn the organic substance sufficiently and to form the metal pollution source on the surface of the oxide.

상기와 같은 조건으로 1단계 열처리한 직후 바로 승온하는데, 승온속도는 크게 상관이 없으나, 열처리를 가능한 단시간에 하기 위해 급속승온하는 것이 좋다. 이와 같이 900-1100℃의 온도범위로 승온하고, 수소와 질소의 혼합가스 분위기에서 3-8시간 유지하여 디누드 층을 형성하는 2단계 열처리를 한다.The temperature is raised immediately after the one-step heat treatment under the above conditions, but the temperature increase rate does not matter much, but it is preferable to increase the temperature rapidly in order to perform the heat treatment in the shortest time possible. As such, the temperature is raised to a temperature range of 900-1100 ° C., followed by a two-step heat treatment for forming a denude layer by maintaining the mixture for 3-8 hours in a mixed gas atmosphere of hydrogen and nitrogen.

본 발명에 따라 2단계 열처리를 하면, 1단계 열처리시 표면에 형성된 금속산화막이 수소가스와 반응하여 식각되어 제거되고, 수소가 실리콘 기판내로 침투하여 격자결함에 이르러 격자의 원상복구를 도우며, 1단계 열철리시 석출되지 못한 금속오염원을 더 깊은 곳으로 이끌어 석출시켜 디누드층이 형성된다. 또한, 실리콘 기판표면에 자연산화막이 생성되지 않고, 수소화기로 표면이 안정화된다.In the two-step heat treatment according to the present invention, the metal oxide film formed on the surface during the one-step heat treatment is etched and removed by reacting with hydrogen gas, and hydrogen penetrates into the silicon substrate to reach the lattice defect, thereby helping to recover the lattice, and in the first step, When hot iron is removed, the metal contamination source which cannot be precipitated is brought to a deeper place and precipitated to form a denude layer. In addition, a natural oxide film is not formed on the surface of the silicon substrate, and the surface is stabilized with a hydrogenation group.

이를 위한 2단계 열처리조건은 먼저, 분위기 가스로 수소와 질소의 혼합가스를 이용하는데, 그 이유는 수소의 폭발을 방지하고, 실리콘기판 표면의 조도를 확보하기 위해서이다. 그 혼합비는 본 발명의 실시결과인 도 3에 나타난 바와 같이 1:10-1:100으로 하는 것이 보다 바람직하다. 이때 수소와 질소의 혼합비가 1:100을 넘는경우 전자수명의 감소하는 것은 질소의 효과로 인하여 표면근처의 격자에 질소의 경화현상으로 전자수명의 감소한다.The two-stage heat treatment condition for this purpose, first, using a mixed gas of hydrogen and nitrogen as the atmosphere gas, in order to prevent the explosion of hydrogen and to ensure the roughness of the surface of the silicon substrate. The mixing ratio is more preferably set to 1: 10-1: 100, as shown in FIG. At this time, when the mixing ratio of hydrogen and nitrogen exceeds 1: 100, the decrease of the electron lifetime decreases the electron lifetime due to the hardening of nitrogen in the lattice near the surface due to the effect of nitrogen.

또한, 도 2에 나타난 바와 같이 열처리온도는 900-1100℃이고, 시간은 3-8시간으로 하는 것이 좋다.In addition, as shown in Figure 2, the heat treatment temperature is 900-1100 ℃, the time is preferably set to 3-8 hours.

이하, 본 발명을 실시예를 통하여 구체적으로 설명한다.Hereinafter, the present invention will be described in detail through examples.

[실시예]EXAMPLE

실리콘 기판을 산소분위기에서 200-1000℃의 온도에서 10-50분간 1단계 열처리하고, 그 열처리조건에 따른 실리콘 기판의 전자수명을 측정하고, 그 결과를 도 1에 나타내었다.The silicon substrate was heat-treated in an oxygen atmosphere at a temperature of 200-1000 ° C. for 10-50 minutes in one step, and the electron life of the silicon substrate was measured according to the heat treatment conditions, and the results are shown in FIG. 1.

상기 1단계 열처리하고, 이어 600-1200℃의 온도범위로 급속승온하고, 수소와 질소의 혼합비를 1:50으로 한 분위기에서 3-10시간 2단계 열처리하고, 그 열처리조건에 따른 실리콘 기판의 전자수명을 측정하고 그 결과를 도 2에 나타내었다. 도 2에서 1100℃이상의 온도에서 10시간 이상 열처리한 것은 상기 1단계열처리를 하지 않고, 바로 1100℃이상의 온도에서 10시간 이상열처리하는 기존의 방법으로 열처리한 것을 나타낸 것이다.The first step of heat treatment, followed by a rapid temperature increase in the temperature range of 600-1200 ℃, two-step heat treatment for 3-10 hours in an atmosphere with a mixture ratio of hydrogen and nitrogen 1:50, the electron of the silicon substrate according to the heat treatment conditions The lifetime was measured and the results are shown in FIG. 2. In FIG. 2, the heat treatment for 10 hours or more at a temperature of 1100 ° C. or more indicates that the heat treatment is performed by a conventional method of heat treatment for 10 hours or more at a temperature of 1100 ° C. or more without performing the first step heat treatment.

그리고, 상기 1단계 열처리한 직후 급속승온하여 1000℃에서 5시간 열처리하면서 수소와 질소의 혼합가스를 1:1-1:1000으로 한 분위기에서 열처리한 다음 전자수명을 측정하고 그 결과를 도 3에 나타내었다.Then, the temperature is rapidly increased immediately after the one-step heat treatment, and the heat treatment is performed at 1000 ° C. for 5 hours, followed by heat treatment in an atmosphere of 1: 1-1: 1000 mixed hydrogen and nitrogen, followed by measuring the electron lifetime. Indicated.

도 1에 나타난 바와 같이, 1단계 열처리의 경우 500-800℃의 온도에서 열처리한 경우 전자수명이 가장 컸다. 이는 본 발명의 1단계 열처리조건을 벗어나면 표면근처에 전자수명을 감소시키는 불순물이나 유기물이 그대로 존재한다는 것을 알 수 있었다.As shown in FIG. 1, in the one-step heat treatment, the electron life was greatest when the heat treatment was performed at a temperature of 500-800 ° C. FIG. It can be seen that the impurities or organic substances that reduce the electron lifetime near the surface as they are out of the one-step heat treatment condition of the present invention.

도 2에 나타난 바와 같이, 본 발명에 따라 900-1100℃의 온도범위에서 3-8시간 유지하는 것이 전자수명증가에 효과적임을 알 수 있으며, 이는 기존의 방법에 따라 열처리하는 것 보다 더 우수함을 알 수 있었다.As shown in Figure 2, according to the present invention it can be seen that maintaining in the temperature range of 900-1100 ℃ 3-8 hours is effective in increasing the electronic life, which is better than the heat treatment according to the existing method Could.

그리고, 도 3에 나타난 바와 같이, 수소와 질소의 비가 1:10-1:100의 경우 전자수명이 향상됨을 알 수 있다.And, as shown in Figure 3, it can be seen that the electron lifetime is improved when the ratio of hydrogen and nitrogen is 1: 10-1: 100.

상술한 바와 같이, 본 발명에 의하면, 종래대비 단시간의 열처리조건으로 디누드층의 형성된 실리콘 기판이 얻어지면 따라서, 제조원가가 절감되는 효과가 있는 것이다.As described above, according to the present invention, if the silicon substrate formed of the denude layer is obtained under a heat treatment condition of a shorter time as compared with the prior art, the manufacturing cost is thus reduced.

Claims (1)

실리콘 기판의 전자수명을 향상시키는 방법에 있어서,In the method of improving the electron lifetime of a silicon substrate, 실리콘 기판을 산소분위기에서 500-800℃의 온도에서 20-30분간 유지하여 유기물 및 금속오염원을 제거하는 1단계 열처리하고, 이 1단계 열처리 직후 900-1100℃의 온도범위로 승온하고, 수소와 질소의 혼합비가 1:10-1:100의 혼합가스 분위기에서 3-8시간 유지하여 디누드 층을 형성하는 2단계 열처리함을 특징으로 하는 실리콘 기판의 전자수명 향상방법.The silicon substrate is kept in an oxygen atmosphere at a temperature of 500-800 ° C. for 20-30 minutes to remove organic substances and metal contaminants, and immediately after this one-step heat treatment, the temperature is raised to a temperature range of 900-1100 ° C., and hydrogen and nitrogen Maintaining a mixing ratio of 1: 10-1: 100 in a mixed gas atmosphere for 3-8 hours to form a denude layer.
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