阅读说明：本技术 一种验证金属后腐蚀缺陷的方法 (Method for verifying metal post-corrosion defect ) 是由 郎刚平 信会菊 曾坤 李林 陈宝忠 于 2020-06-19 设计创作，主要内容包括：本发明公开了一种验证金属后腐蚀缺陷的方法,属于半导体集成电路领域,在金属刻蚀完成后将金属裸露放置在FAB环境中,直至金属表面出现腐蚀缺陷,记录金属表面出现腐蚀缺陷的时间,其中,FAB环境的试验参数为,温度21～25℃、湿度40％～50％,风速为0.2～0.4m/s。本方法在半导体集成电路的生产环境中即可实施操作,无需特殊的验证工具,且本发明的验证方法在6小时内即可检测出后腐蚀缺陷,显著缩短了金属后腐蚀缺陷的验证周期。(The invention discloses a method for verifying post-metal corrosion defects, which belongs to the field of semiconductor integrated circuits, wherein after metal etching is completed, metal is exposed and placed in an FAB environment until corrosion defects appear on the surface of the metal, and the time for the corrosion defects to appear on the surface of the metal is recorded, wherein the test parameters of the FAB environment are that the temperature is 21-25 ℃, the humidity is 40-50%, and the wind speed is 0.2-0.4 m/s. The method can be implemented and operated in the production environment of the semiconductor integrated circuit without a special verification tool, and the verification method can detect the post-corrosion defect within 6 hours, thereby obviously shortening the verification period of the post-metal corrosion defect.)

1. A method for verifying post-metal corrosion defects is characterized in that etched metal is kept stand for 2-6 hours in an FAB environment until corrosion defects appear on the surface of the metal; the experimental parameters of the FAB environment are as follows: the temperature is 21-25 ℃, the humidity is 40-50%, and the wind speed vertical to the metal surface is 0.2-0.4 m/s.

2. The method of claim 1, wherein the etched metal surface is provided with a metal pattern, and the width of the metal pattern is at most 0.5 μm.

3. The method for verifying post-metal corrosion defects according to claim 1, wherein the metal etching method is dry etching; and etching the metal surface by using a mixed gas of chlorine, boron trichloride, argon and nitrogen.

4. The method for verifying post-metal corrosion defects according to claim 1, further comprising a process of de-gumming and cleaning the metal surface after etching.

5. The method for verifying corrosion defects after metal etching as claimed in claim 4, wherein the gas used in the stripping process is a mixed gas of oxygen, nitrogen and water vapor; the photoresist removing temperature is 240-260 ℃.

6. The method of verifying corrosion defects after metal according to claim 4, wherein said cleaning comprises an EKC cleaning, an IPA cleaning and a water spin in sequence.

7. The method of claim 4, wherein the etching and the photoresist stripping are performed under vacuum conditions, and the vacuum pressure is at most 2.0 Torr.

8. A method of verifying corrosion defects after metals according to claim 1, wherein said metals are based on aluminum silicon copper material.

9. A method for verifying post-metal corrosion defects according to claim 8, wherein said substrate has a silicon content of 1% and a copper content of 0.5%.

10. Method of verifying corrosion defects after metals according to claim 1, characterized in that the corrosion defects of the metal surface are observed by means of a microscope.

Technical Field

The invention belongs to the field of semiconductor integrated circuits, and relates to a method for verifying post-metal corrosion defects.

Background

In the production of semiconductor integrated circuits, a metal dry etching process is frequently used, in the dry etching, plasma etching is a frequently used etching method, the existing dry etching is mostly a physical and chemical mixed action mechanism, although the dry etching does not need to be washed after etching compared with the wet etching. However, the etching process still cannot be completely controlled, and the metal post-corrosion defect may exist after etching. Therefore, detection of post-metal corrosion defects in semiconductor integrated circuits is of critical importance.

In a document named 'post-corrosion generated by dry etching of aluminum alloy leads and countermeasures thereof' in microelectronic technology, a method for detecting metal post-corrosion defects is described, namely, the existing method for detecting metal post-corrosion defects in the production process of semiconductor integrated circuits comprises the following steps: "Wet Box" (WETBOX, 150 ml of water in a box) validation method: a) the etched metal was placed in a "wet box" (WETBOX) and after a certain period of time, no post-corrosion defects were identified as standard. b) The sample surface was treated with water to provide the moisture required for post-excitation corrosion, after which a "wet box" (WETBOX) was tested. c) The sample is placed in hydrogen peroxide for accelerated corrosion formation. d) The samples were immersed in deionized water and tested for CL ion number on the metal by ion chromatography. e) After the sample is placed in the aluminum wet etching solution for a few seconds, because a natural oxide layer is not formed at the potential post-etching position, the AL side wall can be immediately dissolved, and the potential post-etching can be shown by estimating the hole of the metal side wall through SEM. The research result shows that: b) analogous to the "wet box" (WETBOX) in a); c) and d) require special validation tools (special instruments for hydrogen peroxide and chromatographic instruments); since the post-corrosion defects are randomly distributed and have uncertain positions on the wafer, the e) method is to extract sample points for detection and has randomness.

As described above, in the above method for detecting post-metal corrosion, the "wet box" (WETBOX) method is generally used in the production of semiconductor integrated circuits because of its simple operation and high feasibility, but the "wet box" (WETBOX) method generally has a verification time of 48 hours, and the experiment requires 48 hours before a result can be obtained, which is time-consuming. Therefore, it is highly desirable to develop a new method capable of completing post-metal corrosion verification in a short time.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a method for verifying the metal post-corrosion defect, so as to solve the technical problem that the existing wet box method detection process is long in time consumption.

In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:

a method for verifying corrosion defects of metal comprises the steps of placing etched metal in an FAB environment and standing for 3-6 hours until corrosion defects appear on the surface of the metal; the experimental parameters of the FAB environment are as follows: the temperature is 21-25 ℃, the humidity is 40-50%, and the wind speed vertical to the metal surface is 0.2-0.4 m/s.

Preferably, the etched metal surface is provided with a metal pattern, and the width of the metal pattern is 0.5 micron at most.

The etching method of the metal is dry etching;

preferably, the metal surface is etched by a mixed gas of chlorine, boron trichloride, argon and nitrogen.

Preferably, the etching process further comprises a process of degumming and cleaning the metal surface.

Further preferably, the gas adopted in the photoresist removing process is a mixed gas of oxygen, nitrogen and water vapor; the photoresist removing temperature is 240-260 ℃.

Further preferably, the cleaning process comprises an EKC cleaning, an IPA cleaning and a flush spin, which are performed sequentially.

Further preferably, both the etching and the photoresist stripping are performed under vacuum conditions at a maximum pressure of 2.0 Torr.

Preferably, the metal is an aluminum silicon copper material as the substrate.

Preferably, the substrate has a silicon content of 1% and a copper content of 0.5%.

Preferably, the corrosion defects of the metal surface are observed by a microscope.

Compared with the prior art, the invention has the following beneficial effects:

the invention discloses a method for verifying post-metal corrosion defects, which comprises the steps of placing a metal in an exposed state in an FAB environment after the metal is etched until the metal surface has corrosion defects, and recording the time of the metal surface having the corrosion defects, wherein the test parameters of the FAB environment comprise that the temperature is 21-25 ℃, the humidity is 40-50%, and the wind speed perpendicular to the metal surface is 0.2-0.4 m/s. Because a certain wind speed is set to be vertical to the metal surface, the metal surface can be strongly swept, the air atmosphere in the FAB environment can strongly impact the metal surface under the action of the artificially set wind speed under the condition of a certain temperature and humidity, and if the metal surface has a corrosion defect, the air atmosphere in the FAB environment can rapidly enter the corrosion defect of the metal surface, so that the corrosion of the defect part is accelerated. The method can be implemented and operated in the production environment of the semiconductor integrated circuit without a special verification tool, and the verification method can detect the post-corrosion defect within 6 hours, thereby obviously shortening the verification period. The method of the invention can be used for verifying the post-corrosion defects of each process in the production process of the semiconductor integrated circuit and confirming the direction that each process can be optimized or controlled. Through verification, risk points in the metal etching dry etching process are determined, and the occurrence probability of metal post-corrosion defects can be reduced by controlling each risk point.

Furthermore, the maximum width of the metal pattern is 0.5 microns, the width is large, and the time for verifying the corrosion defect after the metal is longer, so that the selection of the width range can ensure that the verification method obviously shortens the verification time on the premise of ensuring the accuracy.

Furthermore, the etching process is carried out by using a mixed gas of chlorine, boron trichloride, argon and nitrogen, radicals are generated by glow discharge in the etching process, and the radicals and the metal material undergo physical and chemical reactions under the action of an external electric field to form a volatile product, so that the metal surface is etched.

Further, the mixed gas of oxygen, nitrogen and water vapor generates oxygen free radicals under the action of the microwave source, and the oxygen free radicals react with the photoresist to generate a byproduct which can volatilize hydrocarbons, so that the purpose of removing the photoresist is achieved; the photoresist removing temperature is 250 ℃, the photoresist removing speed can be increased, meanwhile, water vapor condensation can be avoided, the content of chloride ions in the photoresist after dry etching is high, the photoresist needs to be removed in time, and the phenomenon that the chloride ions continue to corrode metal is avoided.

Furthermore, by using a wet solvent soaking mode, sequentially performing EKC cleaning, IPA cleaning and water flushing and spin-drying, and cleaning and removing the polymer with carbon, chlorine and other elements on the surface and the side wall of the etched metal pattern.

Furthermore, aluminum, silicon and copper commonly used in the semiconductor integrated circuit production technology are used, the aluminum metal material can be well attached to the dielectric layer to form ohmic contact, and sputtering deposition is easy to realize in the process; the aluminum film is doped with copper and silicon, so that electromigration, silicon precipitation and aluminum thorn defects can be prevented.

Drawings

FIG. 1 is a process diagram of the optimized control of metal dry etching.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

The invention is described in further detail below with reference to the accompanying drawings:

a method for verifying metal post-corrosion defects is disclosed, and the technological process of the method is shown in figure 1.