阅读说明：本技术 一种tmah蚀刻液的制备蚀刻方法 (Preparation and etching method of TMAH etching solution ) 是由 乔正收 王金城 于 2020-06-30 设计创作，主要内容包括：本发明提供了一种TMAH蚀刻液的制备蚀刻方法。所述的蚀刻液为组合物,包括四甲基氢氧化铵、醇类和水。所述的蚀刻对象为单晶硅。所述的蚀刻方法首先将单晶硅片上待蚀刻图形表面的氧化硅腐蚀干净,之后将单晶硅片浸入加热后的TMAH硅蚀刻液中完成蚀刻。通过本发明的TMAH蚀刻液及蚀刻方法获得硅片无表面金字塔、橘皮效应等缺陷。本发明的TMAH单晶硅蚀刻液应用在MEMS微加工工艺中,蚀刻后硅片无表面金字塔、橘皮效应,满足了半导体客户的需求。本发明的蚀刻液改变了对单晶硅的传统湿法蚀刻特性,具有操作简单、可精确控制蚀刻深度、重复性强、低毒性低污染、易于实现批量化的优点。(The invention provides a preparation etching method of TMAH etching solution. The etching solution is a composition and comprises tetramethylammonium hydroxide, alcohols and water. The etching object is monocrystalline silicon. The etching method comprises the steps of firstly, completely corroding silicon oxide on the surface of a pattern to be etched on a monocrystalline silicon wafer, and then immersing the monocrystalline silicon wafer into a heated TMAH silicon etching solution to complete etching. The TMAH etching solution and the etching method provided by the invention can be used for obtaining silicon wafers without defects of surface pyramid, orange peel effect and the like. The TMAH monocrystalline silicon etching solution is applied to the MEMS micromachining process, and the etched silicon wafer has no surface pyramid and orange peel effects, thereby meeting the requirements of semiconductor customers. The etching solution changes the traditional wet etching characteristic of monocrystalline silicon, and has the advantages of simple operation, accurate control of etching depth, strong repeatability, low toxicity, low pollution and easy realization of batch production.)

1. The method for preparing and etching TMAH etching solution is characterized by comprising the following steps:

(a) weighing a certain amount of TMAH solution, placing the TMAH solution into a polytetrafluoroethylene barrel, adding a certain amount of alcohol, uniformly stirring to obtain a TMAH + alcohol solution, placing the TMAH + alcohol solution in a water bath, heating the TMAH + alcohol solution to a certain temperature, and keeping the temperature.

(b) Weighing a certain amount of hydrofluoric acid by using an HDPE weighing bottle;

(c) weighing ultrapure water and placing the ultrapure water into an open polytetrafluoroethylene barrel

(d) The weighed hydrofluoric acid is carefully poured into ultrapure water contained in a polytetrafluoroethylene barrel, the barrel cover is closed, and the barrel is shaken uniformly, so that the concentration of the hydrofluoric acid solution is 0.1-5%.

(e) Carefully remove 1 silicon wafer with a teflon clamp.

(f) And (3) carefully placing the silicon wafer obliquely (with the front side upward) into a hydrofluoric acid solution by using a polytetrafluoroethylene clamp and completely immersing the silicon wafer, removing a natural oxidation layer of a pattern on the surface of the monocrystalline silicon wafer, and keeping silicon oxide in a region except the pattern.

(g) And (4) taking out the silicon wafer in the hydrofluoric acid, repeatedly cleaning the silicon wafer with ultrapure water, and cleaning the hydrofluoric acid (testing the pH value of the cleaning water and the pH value of the ultrapure water to be neutral).

(h) The cleaned silicon wafer is blow-dried, carefully placed obliquely (right side up) with a polytetrafluoroethylene clamp to a certain temperature in a TMAH + alcohol solution and completely immersed for a certain time.

(i) And (4) taking out the silicon wafer in the TMAH + alcohol solution, and repeatedly cleaning the silicon wafer with ultrapure water to clean the TMAH (the test cleaning water PH and the ultrapure water PH can be neutral).

(j) The silicon wafer is carefully dried by an electric blower (far away from the silicon wafer, the temperature cannot be too high), and the silicon wafer is taken out and put into an original packaging box.

2. The etching method prepared from TMAH etching solution according to claim 1, wherein the crystal orientation of the monocrystalline silicon wafer in step (f) is crystal orientation (100).

3. The method for preparing and etching TMAH etching solution according to claim 1, wherein the etching solution comprises the following components by weight percent: 2 to 37 percent of tetramethyl ammonium hydroxide, 5 to 30 percent of alcohol and 50 to 80 percent of water.

4. The method of claim 3, wherein the alcohol is methanol, ethanol, isopropanol, PEG, ethylene glycol, glycerol, or benzyl alcohol.

5. The method of claim 1, wherein the concentration of hydrofluoric acid is 5-50% of hydrofluoric acid solution.

6. The method for preparing and etching TMAH etching solution according to claim 1, wherein the temperature of the water bath is 20-98 ℃.

7. The method of claim 1, wherein the temperature of TMAH + alcohol solution is 20-98 ℃.

8. The method of claim 1, wherein the etching time in the TMAH + alcohol solution is 10-400 min.

9. The etching method prepared by using TMAH etching solution according to claim 1, wherein the silicon wafer is carefully inclined (right side up) into the hydrofluoric acid solution by using a polytetrafluoroethylene clamp, and the complete immersion time is 0.1-10 minutes.

Technical Field

The invention relates to the field of TMAH etching solution, in particular to a preparation etching method of TMAH etching solution.

Background

In recent years, electronic technology has seen unprecedented growth. As the demand for semiconductor devices and large numbers of integrated circuits in the market economy continues to increase, the performance and reliability standards need to be raised in time.

MEMS is a new generation of emerging technology that has been developed after microelectronics, and has many advantages that conventional electromechanical technology does not have, including greatly reduced volume and power consumption, many new functions, high-volume and high-precision production, low cost of a single piece, good expandability, etc. MEMS technology involves multiple disciplines, and its development will powerfully drive the development of these areas and related high-tech industries, so that the general belief in the foreign science and technology community and industry is that micro-mechanical engineering will form an emerging industry in the 21 st century.

The MEMS processing technology mainly includes a silicon planar process and a bulk silicon process developed from a semiconductor processing process. In the middle of the 20 th century, 80 years, another system of MEMS processing was created using the techniques of X-ray lithography, electroforming, and injection molding (ligaithograph Galvanformung undabformmug). Generally, MEMS technology has been developed based on conventional microelectronic fabrication processes, followed by development of unique technologies suitable for fabricating micro-machines, which are combined with conventional integrated circuit processes to implement MEMS.

Etching is an indispensable link in MEMS micromachining processes. The etching technique includes both types of dry etching and wet etching, and for the wet etching, an alkaline solution having a PH value exceeding 12 can be theoretically used as the etching solution. But comprehensively considers the requirements of anisotropic etching such as higher etching rate to silicon, good crystal orientation dependence, smooth etching surface, low toxicity, easy control of process compatibility to CMOs, and the like. In the MEMS process, KOH fu TMAHTetramet hydrogen ammonium hydroxide (TMAH) is commonly used, and since KOH pollutes the silicon wafer and the clean room environment, the KOH etching process is generally moved to the last step or the TMAH is used to replace KOHl. Therefore, TMAH etching of silicon is an important technique in MEMS processing. However, TMAH forms surface hillocks during etching, which affects surface smoothness, so this project focuses on the technology of obtaining a smooth etched surface by TMAH wet etching in the MEMS technology. Anisotropic etching is an important means of silicon micromachining technology, and currently widely used silicon anisotropic etching solutions include potassium hydroxide aqueous solution, pyrocatechol ethylene diamine aqueous solution EPW and the like, and the latter has poor controllability and high toxicity in the etching process, so that in recent years, fewer and fewer KOH aqueous solutions are used, and the KOH aqueous solutions have the advantages of low toxicity, good surface quality and easy control of etching rate, so that the silicon anisotropic etching solutions are most widely used, but have high possibility of ionic contamination caused by KOH, and have poor compatibility with MOS integrated circuit processes, and therefore, the silicon anisotropic etching solutions are limited in application. TMAH is an anisotropic etching solution with excellent etching performance, good selectivity, low toxicity and low pollution, and most importantly, TMAH is compatible with a Complementary Metal Oxide Semiconductor (CMOS) process and conforms to the development trend of systems On Chip (soC, System On A Chip).

Disclosure of Invention

The invention aims to: in order to solve the above problems, a method for preparing and etching TMAH etching solution is provided.

In order to achieve the purpose, the invention provides the following technical scheme: the method for preparing and etching TMAH etching solution is characterized by comprising the following steps:

(a) weighing a certain amount of TMAH solution, placing the TMAH solution into a polytetrafluoroethylene barrel, adding a certain amount of alcohol, uniformly stirring to obtain a TMAH + alcohol solution, placing the TMAH + alcohol solution in a water bath, heating the TMAH + alcohol solution to a certain temperature, and keeping the temperature.

(b) Weighing a certain amount of hydrofluoric acid by using an HDPE weighing bottle;

(c) weighing ultrapure water and placing the ultrapure water into an open polytetrafluoroethylene barrel

(d) The weighed hydrofluoric acid is carefully poured into ultrapure water contained in a polytetrafluoroethylene barrel, the barrel cover is closed, and the barrel is shaken uniformly, so that the concentration of the hydrofluoric acid solution is 0.1-5%.

(e) Carefully remove 1 silicon wafer with a teflon clamp.

(f) And (3) carefully placing the silicon wafer obliquely (with the front side upward) into a hydrofluoric acid solution by using a polytetrafluoroethylene clamp and completely immersing the silicon wafer, removing a natural oxidation layer of a pattern on the surface of the monocrystalline silicon wafer, and keeping silicon oxide in a region except the pattern.

(g) And (4) taking out the silicon wafer in the hydrofluoric acid, repeatedly cleaning the silicon wafer with ultrapure water, and cleaning the hydrofluoric acid (testing the pH value of the cleaning water and the pH value of the ultrapure water to be neutral).

(h) The cleaned silicon wafer is blow-dried, carefully placed obliquely (right side up) with a polytetrafluoroethylene clamp to a certain temperature in a TMAH + alcohol solution and completely immersed for a certain time.

(i) And (4) taking out the silicon wafer in the TMAH + alcohol solution, and repeatedly cleaning the silicon wafer with ultrapure water to clean the TMAH (the test cleaning water PH and the ultrapure water PH can be neutral).

(j) The silicon wafer is carefully dried by an electric blower (far away from the silicon wafer, the temperature cannot be too high), and the silicon wafer is taken out and put into an original packaging box.

Preferably, the crystal orientation of the monocrystalline silicon wafer in step (f) is the crystal orientation (100).

Preferably, the etching solution comprises the following components in percentage by weight: 2 to 37 percent of tetramethyl ammonium hydroxide, 5 to 30 percent of alcohol and 50 to 80 percent of water.

Preferably, the etching solution comprises the following components in percentage by weight: the alcohol is methanol, ethanol, isopropanol, PEG, ethylene glycol, glycerol, and benzyl alcohol.

Preferably, the concentration of the hydrofluoric acid is 5-50% of hydrofluoric acid solution.

Preferably, the water bath temperature is 20-98 ℃.

Preferably, the temperature of the TMAH + alcohol solution is 20-98 ℃.

Preferably, the etching time in the TMAH + alcohol solution is 10-400 minutes.

Preferably, the silicon wafer is carefully tipped (front side up) into the hydrofluoric acid solution with a teflon clamp and fully submerged for 0.1-10 minutes.

Compared with the prior art, the invention has the beneficial effects that: the TMAH etching solution controls the etching morphology by changing the additive proportion, so that the lobe shape and the etching surface roughness of the etched monocrystalline silicon wafer are changed simultaneously, the TMAH etching solution has a smooth etching surface, has an obvious lobe protection effect, effectively improves the lobe compensation problem, well solves the defects of pyramid effect, orange peel effect and the like on the surface of the silicon wafer, meets the requirements of microstructure processing for specific application on roughness and lobe protection, and provides technical support for the development of a high-performance integrated micro-electro-mechanical system. The etching solution changes the traditional wet etching characteristic of monocrystalline silicon, and has the advantages of simple operation, accurate control of etching depth, strong repeatability, low toxicity, low pollution and easy realization of batch production.

FIG. 1 is a graph comparing experimental results of the present invention;

FIG. 2 is a diagram showing the experimental conclusion of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to 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.