TW449817B - Method of removing watermark on wafers in native oxide layer etching process - Google Patents

Abstract

This invention provides a method to remove watermark on wafers during the native oxide layer etching process, which consists of: (A) removing native oxide layer by acid etching; (B) washing wafer by de-ionized water; (C) spinning to dry wafer at spin speed above 3500 rpm; and (D) blow dry wafer by helium gas. The spin dry speed needs to be increased from 2000 rpm to 3500 rpm or above, or also including water jet to form water film dissolving small water drops and watermark so that the water film can be spun away by using spin dry speed of 3500 rpm and above. The number of watermark is decreased to 0 to 5 counts, satisfying the need of the manufacture process, by increasing the spin dry speed without the use of oven.

Description

Α7 Β7 Economy. Which Central Standards Bureau, Consumer Cooperative, Cooperative Policy 5. Description of the Invention (丨)-The present invention relates to a 5 * method for etching water spots on a wafer when the original oxide layer is etched away. Increase the 0 0 0 rpm to more than 30 pm, or add water spray to form a water film and change the small water droplets. Then, the box enamel is removed at a spin-drying speed above 3 500 rpm. It is only necessary to increase the rotation speed, and it is not necessary to install additional grilled water spots to reduce the number of particles to 0 to 5, which can meet the needs of the manufacturing process. Fortune has in recent years 'the development of the semiconductor industry has brought a considerable amount of guidance to Taiwan ^' has made an indelible contribution to the improvement of the country's overall prosperity, and the semi-industry has also strengthened its research and development after the industry has grown significantly. The advanced technology has become international, and various industrial technologies are constantly being innovated. The present invention is one of them. ^ The semiconductor house industry's products are mainly made of wafers. The integrated circuit device that forms a circuit layout pattern does not form a layout pattern on the backside (ie, the crystal back), and many crystal layers (such as silicon nitride, polycrystalline silicon, and oxide layers) and an oxide layer are grown on the crystal back. ; However, during the wafer manufacturing process, the wafer needs to be heated. Because a too thick layer deposited on the wafer back will affect the heat transfer of the wafer heating, the deposited layer on the wafer back needs to be removed. Austria A semiconductor equipment company produces a device SEZ for removing the back layer of the crystal. The structure of the SEZ device is described in the first. In the circle, a wafer 931 is placed on the turntable 93 and fixed on the turntable 93. The turntable 93 is It is driven by 9 3 2 and the rotating wafer 9 3 1 is continuously processed by the processing liquid (such as hydrogen fluoride, β 0 E, deionized water) sprayed from the inner nozzle of the nozzle 9 2 above the wafer 9 3 1. Spray-washing for engraving, cleaning, gas, etc., the above treatment liquid (please read the precautions on the back before filling this page)

Printed by the Shellfish Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs ^ 49817 m A 7 B7 V. Description of the invention (i) Can be placed in the first tank room 9 4 1, the second tank room 9 4 2, the third tank room 943, In the fourth tank chamber 944, each of the tank chambers can be connected to the chemical tanks 945, 946, and 947 by a pipeline, and then pumped to the nozzle 92 by a pump cycle. The maximum speed of the motor of the above SEZ device can only reach 2500 rpm. The purpose of the present invention is not mainly to perform a wafer back processing process, but to solve the problem of water marks on the wafer surface when the conventional method for removing the original oxide layer on the front side of the wafer is used. ◊ SEZ device is also used in the present invention to remove water spots on the front surface of the wafer. As shown in FIG. 2A to FIG. 2D, the original oxide layer 9 5 2 is usually 5 to 10 angstroms on a general wafer 9 5 1. To remove the original oxide layer 9 5 2, please refer to the common method 3. First, the original oxide layer 9 5 2 is etched away with hydrofluoric acid, that is, the acid etching step 96 1, and bare silicon 9 5 1 a is exposed; then, DI rinse 9 is performed. 6 2. The residual acid on the original silicon wafer 9 5 1 a is washed away. The oxide layer 9 5 2 is hydrophilic, and the silicon 9 _ a is hydrophobic. In addition, the water van der Waals (hruie silicon crystal) The surface tension between the circles and other influences, the original dream a a lot of small water droplets 9 5 3, as shown in Figure two B, where the proportional to one of the sixth power of the sub-radius is Van der. The larger the hydrophobic and high surface tension properties will make the surface of the wafer in the spin-drying process after the deionized water is cleaned, it is easy to form small water droplets, plus the original stone The high surface reaction energy of the evening makes the formed small water droplets easier to adsorb on the silicon wafer, and it is not easy to spin dry. Small droplets of diameter 953 billion-2 billion * (Please read smell precautions to fill out the back of this page)

This paper size applies to Chinese National Standard (CNS) Λ4 specification (210X297 mm) 44981 7 A7 Ministry of Economic Affairs t Central Standards Bureau X Printed by Consumer Cooperatives 5. Description of invention (3) _ 3 · · · up to 0 · 8 microns · Next, spin dry 9 6 3 (Spindry) under 2500r P; finally, water purge 9 6 4 '々 wafer 9 6 4 will form water spot particles ( _γ mark particle) 9 5 4. If the newly generated water droplets are not removed in time, they will gradually dissolve oxygen in the air and oxidize primary silicon (uic <lt). Ca n’t remove the ㈣ process, and the van der Waals force absorbed by the small water droplets on the original cut is very large. Generally, it is still impossible to cut the small water droplets 9 5 3 from the original 5 la ^ at the spin speed of 2_r pm. Such water spots The particles 9 5 3 are as shown in β 4 and FIG. 5, and the number of water records is 3 6 9, while the number of water spot particles in FIG. 5 is 3 4 5. The method is (A) adding an oven (hot plate) to dry small water droplets 9 5 3, and then the oven-treated crystals 0 to 100 For water spot particles, please refer to Figure 6. (B) Another person uses SC 1 rinse (SC 1 rinse), the water recorder is washed away. Using SC 1 cleaning will still form the original oxide layer on the wafer surface, which cannot meet the requirements. The process requirement is equal to returning to the origin of the problem. The main purpose of the present invention is to provide a method for removing water spots on a wafer when the original oxide layer is etched away. In a specific example, the conventional spin-drying speed is changed from 2 0 0 0 The r pm is increased to above 3 500r Pm, and the small water droplets are swirled away at a very high speed. Just increase the speed without installing an oven, and the number of water spot particles can be reduced to 0 to 5, which can meet the needs of the process. The secondary-objective of the present invention is to provide a method for removing water spots on the circle of time when the original gasification layer is etched away. In the second specific example, the wire is known for etching. Order _ Shicai Guanjiasu (CNS) A4 specifications (210 ^^ A7 B7 Printed by the Consumer Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs 4 4 9 81 γ 5. Description of the invention (After the original oxide layer mite process method is removed, the wafer When the water spot particles are full, Spray water to form a water film, the purpose is to dissolve small water droplets into the water film, and then spin-dry the water at a spin-drying speed above 3500 rpm. The number of particles on the surface of the wafer is reduced to 0 to 5-without water spot particles remaining. Brief description of the formulas Figure 1A and circle 1B are schematic diagrams of SEZ machines used in the present invention and the conventional technology. Figures 2A to 2D are cross-sectional views illustrating the process of water spot particle formation. FIG. 3 is a conventional flowchart of etching away the original oxide layer. Figure 4 shows the result circle of a water spot particle inspection machine using a conventional wafer obtained by etching away the original oxide layer. _Five is a result chart of a water spot particle inspection machine using a conventional wafer obtained by etching away an original oxide layer. Figure 6 shows the results of a conventional water spot particle inspection machine using conventional etching to remove the original oxide layer and oven-processed wafers. Figure 7 is a flow chart of etching away the original oxide layer in the first specific example of the present invention. Figure 8 is a flow of etching away the original oxide layer in the second specific example of the present invention. Figure 9 is the etching of the original oxide layer using the present invention. The results of the water spot particle inspection machine used on the obtained wafer are shown in the figure. There are a total of 23 particles in the picture, the particles added in the main process, and the remaining 9 particles are the original particles of the wafer. The M's method is applicable to the 1¾¾ standard (CNS) Α4 specification (21 ^ 297¾- (Please read the precautions on the back before filling in this page)

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-19 81 T Α7 Β7 V. Description of the invention (f) Brief description of drawing number: 1 1 · · · acid etching 1 3 · · · at 3 5 0 0 2 1 · · · acid etching 2 3 · ·. 2 0 〇 2 4 · · · Nitrogen blow-drying 2 6 · · 4 0 · 0 9 2 · · · Nozzle and nozzle 9 3 · ·. 9 9 2 · · Motor 9 4 2 · · Second Tank chamber 9 4 4 ·· Fourth tank chamber 9 4 5 .First chemical liquid tank 9 4 6 .Second chemical liquid tank 9 4 7 .Third chemical liquid tank rrr 12 ·· Speed of deionized water cleaning above pm Spin down 2 2 · · · Rotate dry at 2pm with deionized water cleaning PM 5 · · · Spin dry at a speed of PM with water film 9 3 1 · Wafer 9 4 1 · · First cell chamber 9 4 3 ·· 3 Printed by the Consumer Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs of the Ministry of Economic Affairs 9 5 1a 9 5 3. 9 6 1. 9 6 3. 9 6 4. Nitrogen blow dry 951. Wafer 9 5 2. Original oxidized layer 9 5 4. Water spot particles 9 6 2.. Spin-dry at the speed of de-ionized water cleaning pin. Long-term research, such as enhanced deionized water cleaning or enhanced nitrogen blowing , Can not solve the above problems, finally (please read the note on the back before filling this page)

tThe paper size is applicable to Chinese National Standards (CNS) A4 is present (21〇 &gt; &lt; 297 mm) A7 B7 Printed by the Consumer Cooperatives of the Central Standards Bureau of the Ministry of Economic Affairs 4 4 9 B1 7 V. Description of the invention (4) Discover the original囡 On the spin-drying speed, the method of the invention solves the problem of water spots in the manufacturing process for a long time. A method for removing water spots on a wafer when the original oxide layer is etched according to the present invention, the method includes: (A) etching the original oxide layer by acid 1 1; (B) cleaning the silicon wafer with deionized water 12 (C) Spin the water droplets 1 3 at a spin-drying speed of 3500 rpm or more This is the first specific example of the present invention. In step (A), the acid etching 11 uses hydrofluoric acid. Steps (A &gt; to (c) are performed on the SEZ machine, that is, the wafer is placed on the turntable (9 3). The second method of the present invention is to remove water spots on the wafer after the original oxide layer is etched away. Method, the method includes: (A) acid etching away the original oxide layer 2 1; (B> washing the wafer with deionized water 22; (C) spinning the water droplets at a spin speed of 2000 rpm Dry 2 3 (D) Dry the wafer 2 4 with nitrogen; (E &gt; spray water to form a water film on the wafer and dissolve small water droplets into the water film 2 5; and (F) at a spin-drying speed of 3 Water droplets are spin-dried above 500 pm. This is the second specific example of the present invention. In step (A), the acid etching is using hydrofluoric acid. Steps (A) to (D) are in SEZ The steps (E) and (F) are performed on a scrubber. The scrubber is a conventional machine, here (please read the precautions on the back before filling this page)

This paper size applies to Chinese National Standard (CNS) A4 specification (210X297 mm) 4 4 9 8 t A7 B7 V. Description of the invention (7) Without further explanation, the scrubber is a rotary table with SEZ, which can rotate at high speed. When spraying water from the scrubbing machine, the brush head on the scrubbing machine does not move the wafer, but only sprays water and spins. The spin-drying speed in step (F) is 4000 rpm, which is the preferred speed. In the first and second specific examples, the spin-drying speed is above 3 500 r pm, and the wafer is rotated only at this high-speed. In order to use a large rotating centrifugal force to spin off the small water droplets attached to the wafer. (Please read the notes on the back before filling in this 1) Printed by the Consumer Cooperatives of the Central Bureau of Standards of the Ministry of Economic Affairs The silver standard of this paper applies the Chinese National Standard (CNS) A4 specification (2I0X297 mm)

Claims (1)

ABCD 0 Central Standards Department of the Ministry of Economic Affairs and Consumer Cooperation Law ^ Destruction 4 4S817 ι 9 81 7 VI. Application for Patent Scope 1. A method for removing water spots on wafers when the original oxide layer is etched. This force method includes: ( A) The original oxide layer is etched away by acid; (B) The silicon wafer is cleaned with deionized water; (C) The water droplets are spun at a spin-drying speed of 3,500 rpm or more. A method for removing wafer spots when etching away an original oxide layer, wherein the acid etching is a method for removing speckles on a wafer when etching away an original layer using hydrofluoric acid 3, such as the first item of the patent application park, wherein, Step (A) is performed on the SEZ opportunity. 4. A method for removing water spots on a wafer when the original oxide layer is etched. This method includes: (A) acid etching away the original oxide layer; (B) washing the hair wafer with deionized water; (C &gt; Spin-dry the spin at a spin speed of 2000 r ρ τη (D) blow dry the wafer with nitrogen; (E) spray water on the wafer to form a water film and turn small droplets into 4 large droplets; And (F) drying the water droplets at a spin-drying speed of 3,500 rpm or more. 5. The method for removing plaque on the wafer when the original oxide layer is etched away according to item 4 of the patent application park, wherein: The acid etching is using hydrofluoric acid 6. If the original oxide layer is etched away as described in item 4 of the patent application, please read the M item first and then the SI page This paper size is in accordance with Chinese National Standard (CNS) A4 (210 X 297 mm) ABCD 449817 VI. Patent Application &amp; / Spot "To. Method, where steps (A) to (D) are on the SEZ machine The steps (E) and (F) are performed on a scrubber. 7. The method for removing ice spots on a wafer when the original oxide layer is etched away according to item 4 of the patent application park, wherein: The spin-drying speed of step (F) is above 350 &lt; rpm. 11 This paper size is applicable to China National Standard (CNS) A4 (210 X 297 mm)