JP2015109401A - Method for manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for rinsing a semiconductor substrate by electrolytically reduced water.SOLUTION: There is provided a method for cleaning a semiconductor substrate to an extent such that the metal contamination is 1x10atoms/cm2 or less, and the number of particles of 0.1 μm or larger is 10 pieces/wafer or less by rinsing the semiconductor substrate with electrolytically reduced water (having a pH of 11 to 13 and an oxidation-reduction potential of -500 to -1000 mV) produced by a device that produces only electrolytically reduced water by electrolysis.

Description

  The present invention relates to a method for manufacturing a semiconductor device used in a mobile phone, digital camera, video camera, car navigation, personal computer, game machine, liquid crystal television, printer, etc. as a transistor, capacitor, memory card, sensor, imaging device, etc. About.

  In the manufacture of semiconductor devices, cleaning is always performed to clean the surface before and after film formation of the silicon surface, insulating film, metal film, etc., after dry etching or wet etching, and after resist removal. . For example, Japanese Patent Publication No. 53-35436 (Patent Document 1) discloses a method called RCA cleaning in which particles on a semiconductor substrate are removed with an aqueous solution in which hydrogen peroxide and pure water are mixed with ammonia, and then added to hydrochloric acid. A method of removing metal contamination with an aqueous solution in which hydrogen oxide water and pure water are mixed is disclosed.

  Japanese Patent Laid-Open No. 6-291099 (Patent Document 2) discloses a method of removing particles and metal contamination by mixing an organic acid containing citric acid with pure water.

  On the other hand, Japanese Patent Application Laid-Open No. 2007-160496 (Patent Document 3) discloses removal of particles containing organic substances by ozone water generated on the anode side by electrolysis, and hydrogen water generated from the other cathode side. A method for removing metal contamination is disclosed.

  In current semiconductor substrate cleaning, the organic, inorganic cleaning liquids described above are combined to remove particles, organic matter, and metal contamination on the semiconductor substrate.

  Japanese Patent Publication No.53-35436   Japanese Patent Laid-Open No. 6-291099   Japanese Patent Laid-Open No. 2007-160496

  The conventional method using the RCA cleaning liquid requires enormous processing costs and equipment for the removal of toxic gas generated from the chemical solution, and the waste liquid processing after cleaning, as well as many problems such as safety for workers and environmental measures. Have been used.

  The present invention overcomes these problems and establishes a cleaning method that reduces safety and environmental burden on workers and does not cause environmental destruction on a global scale.

  The object of the present invention is to propose a cleaning method in consideration of the environment, and can be applied to any cleaning process of semiconductor devices and various solid-state devices produced all over the world.

The invention according to claim 1 is a semiconductor characterized in that in the case of cleaning the surface of a semiconductor substrate, electrolytic reduction water (hereinafter referred to as ERW) generated using an apparatus that generates only electrolytic reduction water is performed in the following series of steps. A device manufacturing method comprising:
(1). A semiconductor substrate is placed on a substrate holder of a single wafer cleaning machine, and is rotated at 50 to 1000 min −1, and has a pH of 11 to 13 and an oxidation-reduction potential (hereinafter referred to as ORP) −500 to −1000 mV on the surface of the semiconductor substrate Spraying ERW and washing,
(2). (3) removing the ERW by spraying pure water on the front surface or front and back surfaces of the semiconductor substrate while rotating the semiconductor substrate at 50 to 500 min−1; While the semiconductor substrate is rotated at 1000 to 2000 min-1, N2 or dry air is sprayed on the front surface or the front and back surfaces of the semiconductor substrate to dry the semiconductor substrate, thereby removing particles and metal contamination on the semiconductor substrate surface. Is the method.

According to a second aspect of the present invention, when the surface of a semiconductor substrate is cleaned, the semiconductor is characterized by performing the following series of steps using electrolytic reduced water (hereinafter referred to as ERW) generated using an apparatus that generates only electrolytic reduced water. A device manufacturing method comprising:
(1). Placing the semiconductor substrate on a substrate cassette of an immersion cleaning machine, immersing and cleaning the semiconductor substrate in an ERW of pH 11 to 13 and ORP-500 to -1000 mV;
(2). Immersing the semiconductor substrate in pure water to remove ERW;
(3). In this method, particles and metal contamination on the surface of the semiconductor substrate are removed by a step of spraying N2 or dry air onto the semiconductor substrate to dry the semiconductor substrate.

A wafer whose silicon surface is polished with an abrasive using silica is cleaned by the cleaning method of the present invention so that particles of 0.2 μm or more are reduced to 100 particles or less, and heavy metal contamination is reduced to 1 × ^{10 10} atoms / cm 2 or less. (See Tables 1 to 4).

It is a principle figure for manufacturing washing water of the present invention. It is a block diagram which shows the washing | cleaning method of this invention. The surface property of the silicon substrate surface after washing | cleaning by the method of Claim 1 of this invention is shown.

Table 1

The number of particles on the surface of the silicon substrate after being cleaned by the method of claim 1 of the present invention is shown.

Table 2

It shows the amount of heavy metal after washing by the method of claim 1 of the present invention.

Table 3

The number of particles on the surface of the silicon substrate after being cleaned by the method of claim 2 of the present invention is shown.

Table 4

It shows the amount of heavy metal after washing by the method of claim 2 of the present invention.

  Hereafter, the implementation method of this invention is demonstrated in detail.

Example 1
Using a 10-fold diluted non-woven fabric of silica slurry (GRANZOX-1302, manufactured by Fujimi Incorporated) having a particle diameter of 30 nm in which an 8-inch diameter silicon substrate surface is dispersed in an alkaline aqueous solution of pH 11.6 After polishing the silicon to a depth of 2 μm with a pad (SUBA # 400, manufactured by Nitta Haas), cleaning was performed under the following conditions. As the polishing machine, SPP800S manufactured by Okamoto Machine Tool Works was used.

(1). ERW of pH 12.6, oxidation-reduction potential (ORP) -813 mV is discharged at approximately the center of the silicon substrate at a flow rate of 1 L / min, and cleaned for 60 seconds at a silicon substrate rotation speed of 500 min-1,
(2). DIW is discharged to the center of the silicon substrate at a flow rate of 2 L / min, and rinsed for 60 seconds at a silicon substrate rotation speed of 100 min-1,
(3). The silicon substrate was dried at 1500 min-1 for 60 seconds to complete.

  As shown in # 1 to # 3 of Table 1, the number of particles after this cleaning is 10 to 19 particles of 0.2 microns or more, which is practically sufficient.

In addition, as a result of measuring the amount of heavy metal by total reflection X-ray fluorescence analysis at this time, as shown in # 1 to # 3 of Table 2, it was 1 × ^{10 10} atoms / cm 2 or less, which was favorable.

  The surface roughness of silicon is 0.27 to 0.34 nm (Ra), and it can be seen that the surface properties of the silicon surface are not deteriorated by this cleaning.

  Also, a silica slurry having a particle diameter of 30 nm (GLANZOX-1302, manufactured by Fujimi Incorporated) in which an 8-inch silicon substrate surface is dispersed in an alkaline aqueous solution having a pH of 11.6 is diluted 10 times with pure water. After polishing silicon to a depth of 2 μm with a non-woven pad (SUBA # 400, manufactured by Nitta Haas), 12 nm silica slurry (GLANZOX3105, manufactured by Fujimi Incorporated) dispersed in an alkaline solution at pH 10.6 is further purified. After being polished with a suede pad (RN-H, manufactured by Nitta Haas) using a solution diluted 30 times with water, cleaning was performed under the following conditions. The polishing machine used was Okamoto Machine Tool Works SPP800S.

(1). Release ERW of pH 12.6, oxidation-reduction potential (ORP) -798 mV to the center of the silicon substrate at a flow rate of 1 L / min, and clean for 60 seconds at a silicon substrate rotation speed of 500 min-1,
(2). DIW is discharged to the center of the silicon substrate at a flow rate of 2 L / min, rinsed for 60 seconds at a silicon substrate count of 100 min-1,
(3). The silicon substrate was dried at 1500 min-1 for 60 seconds to complete.

  As shown in # 4 to # 5 of Table 1, the number of particles after this cleaning is 2 to 3 at 0.2 microns or more, and it can be seen that the number of particles can be further reduced by the cleaning after finish polishing.

Moreover, as a result of measuring the amount of heavy metal at this time by total reflection X-ray fluorescence analysis, as shown in # 4 to # 5 in Table 2, it is 1 × ^{10 10} atoms / cm 2 or less. There was no difference in the presence or absence.

Example 2
Using a 10-fold diluted non-woven fabric of silica slurry (GRANZOX-1302, manufactured by Fujimi Incorporated) having a particle diameter of 30 nm in which an 8-inch diameter silicon substrate surface is dispersed in an alkaline aqueous solution of pH 11.6 After polishing the silicon to a depth of 2 μm with a pad (SUBA # 400, manufactured by Nitta Haas), cleaning was performed under the following conditions. As the polishing machine, SPP800S manufactured by Okamoto Machine Tool Works was used.

(1). Immerse in an ERW bath at pH 12.6, redox potential (ORP) -810 mV and wash for 120 seconds,
(2). Move to overflowing DIW tank and rinse for 120 seconds,
(3). It moved to the drying chamber and it was completed by drying for 60 seconds by N2 blow atmosphere.

  The number of particles after this cleaning is 30 to 86 with 0.2 micron or more as shown in # 1 to 5 of Table 3, which is slightly more than Example 1, but is practically sufficient.

In addition, as a result of measuring the amount of heavy metal by total reflection X-ray fluorescence analysis at this time, as shown in # 1 to 5 of Table 4, it was 1 × ^{10 10} atoms / cm 2 or less, which was favorable.

  As described above, cleaning with ERW alone can achieve practically sufficient performance, no harmful gas is generated, and waste liquid can be drained as it is without harm. Not only can the cost be expected to be drastically reduced, but also consumables such as PVA brushes that have been used in the past are not required, so that the running cost is reduced and the configuration of the washing machine can be simplified, and the initial cost can be reduced.

  It can contribute to the cleaning of semiconductor devices and solid-state devices by cleaning methods with less environmental impact.

DESCRIPTION OF SYMBOLS 1 Cation exchange membrane 2 Cathode electrode 3 Anode electrode 4 Electrolyte solution 5 Electrolytic reduction water (ERW)
6 Ultrapure water 7 Si wafer 8 Cleaning chamber 9 Wafer holding pin 10 Spin table

Claims (3)

A method of manufacturing a semiconductor device, wherein the semiconductor substrate surface is cleaned by electrolytic reduced water generated using an apparatus that generates only electrolytic reduced water in the following series of steps.
(1). A semiconductor substrate is placed on a substrate holder of a single wafer cleaning machine, and is rotated at 50 to 1000 min −1, and has a pH of 11 to 13 and an oxidation-reduction potential (hereinafter referred to as ORP) −500 to −1000 mV on the surface of the semiconductor substrate The process of spraying and reducing the electrolytically reduced water.
(2). A step of removing electrolytic reduction water by spraying pure water on the front surface or front and back surfaces of the semiconductor substrate while rotating the semiconductor substrate at 50 to 500 min −1 after the cleaning step;
(3). After the step of removing the electrolytically reduced water, a step of drying the semiconductor substrate by blowing N2 or dry air to the front surface or the front and back surfaces of the semiconductor substrate while rotating the semiconductor substrate at 1000 to 2000 min-1. A method of manufacturing a semiconductor device, wherein the semiconductor substrate surface is cleaned by electrolytic reduced water generated using an apparatus that generates only electrolytic reduced water in the following series of steps.
(1). A step of placing a semiconductor substrate on a substrate cassette of an immersion type cleaning machine, and immersing the semiconductor substrate in an electrolytic reduction water tank having a pH of 11 to 13 and an ORP of 500 to -1000 mV for cleaning.
(2). A step of immersing the semiconductor substrate in pure water and removing electrolytic reduction water after the step of immersing and cleaning.
(3). After the step of removing the electrolytically reduced water, a step of spraying N2 or dry air on the semiconductor substrate to dry the semiconductor substrate.   3. A method of manufacturing a semiconductor device, wherein the step of drying the semiconductor substrate according to claim 2 is performed by a Marangoni method.