Classifications

• • 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
  • H01L21/02041—Cleaning
  • H01L21/02043—Cleaning before device manufacture, i.e. Begin-Of-Line process
  • H01L21/02052—Wet cleaning only

Definitions

• the present invention relates to a method for etching a silicon wafer. More specifically, the present invention relates to a method for etching a silicon wafer, which can give a stable surface of a silicon wafer.
• an etching step has come to be an important step in a point of removing damages on a surface of a silicon wafer with simultaneously maintaining a flat shape of the surface of a silicon wafer.
• the etching step comes after a lapping step and before a polishing step.
• minuteness of a semiconductor device improves, a requirement for flatness of a silicon wafer becomes severer. It is difficult to improve flatness of a silicon wafer by merely controlling in a polishing step, and a precise treatment in an etching step, which has an influence upon a surface shape of a silicon wafer, is required.
• a composition of an etching liquid but also an etching apparatus itself has recently been improved.
• an etching step aims to corrode a surface of a silicon wafer, an oxidation film is not sufficiently formed on a surface of a silicon wafer obtained right after etching in view of properties of silicon, and the surface of the silicon wafer exhibits hydrophobicity.
• the silicon wafer is subjected to a rinsing treatment so as to restrain a progress of etching.
• a rinsing treatment there has conventionally been used deionized water. Since deionized water does not have an oxidizing ability, hydrophobicity of the surface of the silicon wafer is maintained. In such a condition, the surface of the silicon wafer is activated, and therefore, a foreign matter is liable to adhere to the surface of the silicon wafer. Moreover, once a foreign matter adheres, the foreign matter directly contacts with the silicon wafer, thereby having a difficulty in removing the foreign matter in the following washing step, or the like.
• a rinse adheres to the hydrophobic surface of the silicon wafer in the form of a waterdrop. If the condition is maintained, a trace of the waterdrop remains as a water mark after the silicon wafer is naturally dried.
• the water mark is not a mere trace of a deionized water.
• the waterdrop absorbs an oxygen in the air and is partially and abnormally oxidized, and the water mark cannot be removed in a following washing step using APM liquid (i.e., a washing liquid prepared by diluting ammonia and hydrogen peroxide with superdeionized water) .
• APM liquid i.e., a washing liquid prepared by diluting ammonia and hydrogen peroxide with superdeionized water
• the present invention aims to provide a method for etching a silicon wafer, the method being able to avoid an occurrence of a defect in advance during an etching treatment .
• a method for etching a silicon wafer comprising the steps of : lapping a silicon wafer; etching the silicon wafer; and polishing the silicon wafer; wherein the etching step includes an etching treatment and a rinsing treatment, and at least an oxidizing agent is added to a rinse to be used for the rinsing treatment, thereby forming an oxidation film on a surface of the silicon wafer.
• an oxidizing agent such as ozone, a neutralizing agent, and a surface-active agent or a wetting agent are added to a rinse to be used for restraining etching, the surface of the silicon wafer is oxidized during the rinsing treatment, thereby protecting the surface of the silicon wafer by a stable oxidation film so as to avoid generation of a defect.
• Fig. 1 is a schematic view showing conditions of adhesion of foreign matters in a method for etching a silicon wafer of the present invention and a conventional method for etching a silicon wafer.
• Fig. 2 is a graph showing an effect of adding ozone in a rinse used for a rinsing treatment.
• a process of producing a silicon wafer is generally described.
• a silicon ingot consisting of silicon single crystals is subjected to slicing, lapping, etching, polishing, and washing in this order so as to obtain a silicon wafer as a product.
• a silicon wafer is transferred to a process for producing a semiconductor device.
• An etching step is constituted of an etching treatment and a rinsing treatment which restrains etching.
• Etching the silicon wafer is to remove the damages on the surface.
• a mixed acid containing hydrogen fluoride (HF) , nitric acid (HN0 3 ) , acetic acid (CH 3 COOH) and water so as to remove a damaged layer of the surface of the silicon wafer.
• a rinsing treatment comes after the etching treatment.
• To the rinsing treatment is usually applied a quick damp rinse, an overflow rinse, or the like.
• a quick damp rinse a cycle of supplying and discharging deionized water is repeated several times.
• an overflow rinse a deionized water is supplied for a predetermined period of time to a vessel containing a silicon wafer from the bottom of the vessel so that the deionized water overflows, and simultaneously acid on the silicon wafer is removed.
• an oxidizing agent such as ozone is added to a rinse used for restraining etching in the aforementioned rinsing treatment so as to form an oxidation film on the surface of the silicon wafer.
• a neutralizing agent is preferably added to the rinse to stop an etching reaction, and a surface-active agent or a wetting agent is preferably added so as to decrease stains on a surface of a silicon wafer as much as possible.
• An oxidizing agent used for the rinsing treatment in the etching step is not limited, and ozone, hydrogen peroxide, a mixture of ammonium hydroxide and hydrogen peroxide, nitric acid, and sulfuric acid, or the like can be used.
• an oxidizing agent such as ozone dissolved at a rate ranging from 0.5 to 40 ppm in deionized water is effective, the rate is preferably within the range from 2 to 20 ppm from the economical view point.
• a temperature for the rinsing treatment has no limitation, either.
• a neutralizing agent, a surface- active agent, and a wetting agent to be added to the rinse are not particularly limited, and known agents can be employed for the agents.
• the present invention is hereinbelow described in more detail on the basis of embodiments shown in Figures.
• Fig. 1 is a schematic view showing conditions of adhesion of foreign matters in a method for etching a silicon wafer of the present invention and a conventional method for etching a silicon wafer.
• Reference numeral 1 denotes a silicon wafer.
• (a) of Fig. 1 shows a silicon wafer in a condition just after being cut off a silicon ingot.
• (b) of Fig. 1 shows a silicon wafer in a condition after damages on the surface of the silicon wafer 1 shown in (a) of Fig. 1 are removed.
• FIG. 1 shows surface conditions of silicon wafers 1 obtained after a rinsing treatment. One of them shows no oxidation film after a rinsing treatment using a mere deionized water. The other shows presence of an oxidation film 2 formed on the surface of the silicon wafer after a rinsing treatment using a deionized water 1 with an oxidizing agent such as ozone therein.
• FIG. 1 shows conditions of adhesion of pollutants 3 such as foreign matters which adhered to the silicon wafers 1 during storage. In case of rinsing with a mere deionizing water, pollutants 3 and the like directly adhere to the silicon wafer 1.
• Fig. 2 shows effect of rinsing treatments in which ozone was added to a rinse.
• rinsing treatments using ozone in a rinse decreases the generation of defects in silicon wafers in comparison with a rinsing treatment with mere deionized water.
• rates of defects were obtained by visually inspecting surfaces of the silicon wafers under a light-condensed condition.
• the generation of a defect on a surface of a silicon wafer is restricted because an oxidation film is formed on the surface of the silicon wafer by adding an oxidizing agent such as ozone to a rinse to be used in a rinsing treatment; thereby showing remarkable effect of improving properties of a semiconductor device, yield, or the like.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Manufacturing & Machinery (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Power Engineering (AREA)
• Cleaning Or Drying Semiconductors (AREA)
• Weting (AREA)

Applications Claiming Priority (5)

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• 1998
  • 1998-05-01 EP EP98920143A patent/EP0978140A1/de not_active Withdrawn
  • 1998-05-01 CN CN 98804760 patent/CN1254440A/zh active Pending
  • 1998-05-01 WO PCT/US1998/008936 patent/WO1998050948A1/en not_active Application Discontinuation

Non-Patent Citations (1)

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