CN103137548A - 改善硅接触孔刻蚀工艺窗口的方法 - Google Patents

改善硅接触孔刻蚀工艺窗口的方法 Download PDF

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CN103137548A
CN103137548A CN2011103884231A CN201110388423A CN103137548A CN 103137548 A CN103137548 A CN 103137548A CN 2011103884231 A CN2011103884231 A CN 2011103884231A CN 201110388423 A CN201110388423 A CN 201110388423A CN 103137548 A CN103137548 A CN 103137548A
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silicon
contact hole
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barrier layer
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刘俊
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Shanghai Huahong Grace Semiconductor Manufacturing Corp
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Shanghai Hua Hong NEC Electronics Co Ltd
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Abstract

本发明公开了一种改善硅接触孔刻蚀工艺窗口的方法,在硅接触孔刻蚀工艺中加入步骤:做完源、漏极后,在包括STI区的硅衬底表面生长非掺杂的多晶硅作为刻蚀阻挡层,去除不需保护区域的多晶硅;在刻蚀接触孔时,先用二氧化硅对多晶硅高选择比的刻蚀工艺刻蚀二氧化硅,再用多晶硅对氮化硅和二氧化硅都是高选择比的工艺刻蚀多晶硅,完成硅接触孔的刻蚀。该方法利用局部的非掺杂多晶硅刻蚀阻挡层,减少了硅接触孔刻蚀时,多晶硅栅极上的氮化硅绝缘层及borderless孔在STI边缘的氧化层受到的损失,从而改善了硅接触孔刻蚀工艺窗口,避免了自对准孔和多晶硅栅极间的电压泄露及borderless孔在STI边缘漏电。

Description

改善硅接触孔刻蚀工艺窗口的方法
技术领域
本发明涉及半导体集成电路制造领域,特别是涉及一种改善硅接触孔刻蚀工艺窗口的方法。
背景技术
在某些半导体制造工艺(例如嵌入式闪存制造工艺)中,硅接触孔既是Gate poly(多晶硅栅极)之间的自对准的孔,同时也是STI(shallow trench isolation,浅沟槽隔离)边缘的borderless(无边)孔。
自对准硅接触孔与Gate poly之间的结构通常如图1所示,Gate poly的顶部和侧壁应用氮化硅绝缘层来隔绝自对准硅接触孔和Gate poly之间的电压。该氮化硅层不能在硅接触孔刻蚀的时候受到损失,否则会造成自对准硅接触孔和Gate poly之间的电压泄露,不但影响产品的良品率,还会带来可靠性问题,因此,不能将氮化硅层作为自对准硅接触孔的刻蚀阻挡层。如果硅接触孔刻蚀时没有刻蚀阻挡层,硅接触孔刻蚀工艺的窗口就会非常的小,容易因刻蚀不足而导致硅接触孔不通,或因刻蚀过多而导致自对准硅接触孔和Gate poly之间的电压泄露(如图1中圆圈所示)。
borderless孔与STI边缘之间的结构通常如图2所示。如果borderless硅接触孔在刻蚀时没有刻蚀阻挡层,则硅接触孔刻蚀工艺的窗口也会非常的小,在刻蚀不足时会导致硅接触孔不通,而在刻蚀过多时又会导致borderless硅接触孔在STI边缘漏电(如图2中圆圈所示)。
发明内容
本发明要解决的技术问题是提供一种改善硅接触孔刻蚀工艺窗口的方法,它可以提高半导体产品的良品率和可靠性。
为解决上述技术问题,本发明的改善硅接触孔刻蚀工艺窗口的方法,在常规的硅接触孔刻蚀工艺中,加入以下工艺步骤:
1)在完成源极和漏极制作后,在包括STI区的硅衬底表面生长一层非掺杂的多晶硅,作为硅接触孔刻蚀时的刻蚀阻挡层;
2)去除硅接触孔刻蚀时不需要保护的区域的多晶硅刻蚀阻挡层;
3)在刻蚀接触孔时,先用二氧化硅对多晶硅高选择比的刻蚀工艺刻蚀二氧化硅,使刻蚀停留在多晶硅刻蚀阻挡层;
4)再用多晶硅对氮化硅和二氧化硅都是高选择比的工艺刻蚀多晶硅,完成硅接触孔的刻蚀。
所述高选择比是指选择比在10∶1以上。
本发明利用局部的非掺杂多晶硅刻蚀阻挡层,大大减少了硅接触孔刻蚀时,Gate poly上的氮化硅绝缘层及borderless孔在STI边缘的氧化层所受到的损失,从而改善了硅接触孔刻蚀工艺窗口,避免了自对准硅接触孔和Gate poly之间的电压泄露以及borderless硅接触孔在STI边缘漏电的问题,进而保证了产品的良品率和可靠性。
附图说明
图1是采用现有工艺刻蚀的自对准硅接触孔与Gate poly之间的结构示意图。
图2是采用现有工艺刻蚀的borderless孔与STI边缘之间的结构示意图。
图3是本发明的方法流程图。
具体实施方式
为对本发明的技术内容、特点与功效有更具体的了解,现结合图示的实施方式,详述如下:
本实施例为了改善硅接触孔刻蚀工艺窗口,在现有硅接触孔刻蚀工艺中引入了如下工艺步骤(参见图3):
步骤1,在完成源极和漏极(Source/Drain)制作后,在硅(Si)衬底表面(包括STI区)生长一层厚度为100~500埃米的非掺杂的多晶硅,作为后续硅接触孔刻蚀的刻蚀阻挡层,如图3(A)所示;
步骤2,通过光刻和刻蚀方法,去掉后续硅接触孔刻蚀时不需要保护的区域(例如,大部分无孔区域)的多晶硅刻蚀阻挡层,如图3(B)所示。仅在局部应用多晶硅刻蚀阻挡层,是为了防止多晶硅在某些敏感区域由于其成长过程中的热过程而导致掺杂,引起漏电。
步骤3,在完成层间膜生长和CMP等常规工艺后,在无孔区域上涂布光刻胶,如图3(C)所示。然后用二氧化硅对多晶硅高选择比(≥10∶1)的刻蚀工艺刻蚀二氧化硅,使得刻蚀停留在多晶硅刻蚀阻挡层,如图3(D)所示。
步骤4,用多晶硅对氮化硅和二氧化硅都是高选择比(≥10∶1)的工艺刻蚀多晶硅,完成硅接触孔刻蚀。如图3(E)所示。
步骤6,去掉光刻胶,结果如图3(F)所示。
在硅接触孔刻蚀工艺中,应用局部的非掺杂多晶硅刻蚀阻挡层后,大大减少了硅接触孔刻蚀时,Gate poly上的氮化硅绝缘层及borderless孔在STI边缘的氧化层所受到的损失,如图3(F)(圆圈位置)所示,从而极大地改善了硅接触孔刻蚀工艺窗口,避免了自对准硅接触孔和Gate poly之间的电压泄露,以及borderless硅接触孔在STI边缘漏电,进而提升了产品的良品率和可靠性。

Claims (5)

1.一种改善硅接触孔刻蚀工艺窗口的方法,其特征在于,在常规的硅接触孔刻蚀工艺中,加入以下工艺步骤:
1)在完成源极和漏极制作后,在包括浅沟槽隔离区的硅衬底表面生长一层非掺杂的多晶硅,作为硅接触孔刻蚀时的刻蚀阻挡层;
2)去除硅接触孔刻蚀时不需要保护的区域的多晶硅刻蚀阻挡层;
3)在刻蚀接触孔时,先用二氧化硅对多晶硅高选择比的刻蚀工艺刻蚀二氧化硅,使刻蚀停留在多晶硅刻蚀阻挡层;
4)再用多晶硅对氮化硅和二氧化硅都是高选择比的工艺刻蚀多晶硅,完成硅接触孔的刻蚀。
2.根据权利要求1所述的方法,其特征在于,步骤1),所述多晶硅刻蚀阻挡层的厚度为100~500埃米。
3.根据权利要求1所述的方法,其特征在于,步骤2),采用光刻和刻蚀方法去除不需要保护区域的多晶硅刻蚀阻挡层。
4.根据权利要求1所述的方法,其特征在于,步骤3),二氧化硅对多晶硅的选择比在10∶1以上。
5.根据权利要求1所述的方法,其特征在于,步骤4),多晶硅对氮化硅和二氧化硅的选择比都在10∶1以上。
CN2011103884231A 2011-11-29 2011-11-29 改善硅接触孔刻蚀工艺窗口的方法 Pending CN103137548A (zh)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111653476A (zh) * 2020-05-13 2020-09-11 上海华虹宏力半导体制造有限公司 接触孔的刻蚀方法及接触孔刻蚀结构

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US5174858A (en) * 1990-06-04 1992-12-29 Matsushita Electric Industrial Co., Ltd. Method of forming contact structure
US5670404A (en) * 1996-06-21 1997-09-23 Industrial Technology Research Institute Method for making self-aligned bit line contacts on a DRAM circuit having a planarized insulating layer
US6483153B1 (en) * 1999-10-14 2002-11-19 Advanced Micro Devices, Inc. Method to improve LDD corner control with an in-situ film for local interconnect processing
CN1541411A (zh) * 2002-08-22 2004-10-27 英特尔公司 到栅极的自对准接触

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5174858A (en) * 1990-06-04 1992-12-29 Matsushita Electric Industrial Co., Ltd. Method of forming contact structure
US5670404A (en) * 1996-06-21 1997-09-23 Industrial Technology Research Institute Method for making self-aligned bit line contacts on a DRAM circuit having a planarized insulating layer
US6483153B1 (en) * 1999-10-14 2002-11-19 Advanced Micro Devices, Inc. Method to improve LDD corner control with an in-situ film for local interconnect processing
CN1541411A (zh) * 2002-08-22 2004-10-27 英特尔公司 到栅极的自对准接触

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111653476A (zh) * 2020-05-13 2020-09-11 上海华虹宏力半导体制造有限公司 接触孔的刻蚀方法及接触孔刻蚀结构

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