Improved gas hood method for removing SiO2 film on edge of silicon substrate (EOS process)

Abstract

The invention relates to an improved gas hood method for removing a silicon substrate edge SiO2 film (EOS process), which is mainly used for a corrosion process for removing an edge oxide film after an oxide film grows on a silicon wafer, and the aim of optimizing the edge corrosion uniformity is fulfilled by changing the cavity form of a tool to optimize the corrosion state, so that the EOS quality is improved. The dome type design is more beneficial to the filling of HF gas in the gas hood, so that the gas can be uniformly distributed on the edge of the silicon wafer for corrosion, and the EOS uniformity is improved. And the heating pad can be placed in the concave embedded design at the top, so that the heating pad is protected, energy loss is reduced, and the service life of the heating pad is prolonged. The connection mode of the newly designed nozzle is changed into an integrated mode, so that the previous mode of fixing by a plurality of screws is improved, the disassembly during equipment maintenance or replacement is convenient, and the time is saved. Compared with the prior art, multiple designs are adopted, in terms of technical improvement, one purpose is achieved, and the method is worthy of popularization and application.

Description

Technical Field

[0001] The present invention provides an improved gas hood method for removing SiO2 film at the edge of a silicon substrate (EOS process). The present invention is mainly used for the etching process of removing the edge oxide film after the silicon wafer has grown an oxide film. By changing the cavity morphology of the tool to optimize the corrosion state, the purpose of optimizing the uniformity of edge corrosion is achieved, thereby improving the EOS quality. Background Art

[0002] With the rapid development of the semiconductor industry and fierce market competition, the demand for semiconductor silicon substrates has been increasing in the past two years, and the requirements for silicon polishing wafer products have been getting higher and higher. The requirements for the uniformity of the surface and edges of polishing wafers are also getting higher and higher. Therefore, new requirements are also put forward for the edge corrosion process in the production process. This is also a problem that every polishing wafer processing company will face. Improving the production capacity of each process in the production process and improving the yield are issues faced by many factories. There are two ways to etch the edge of silicon wafers: 1. Gas phase EOS 2. Liquid phase EOS. Liquid phase EOS has the disadvantages of high cost, wastewater, and complex process. This method is currently only used in small quantities. At present, gas phase EOS is the main method. The level of this process product depends largely on the stability and precision of the equipment. Therefore, the stability of the tooling during the corrosion process is the first factor to ensure the stability of product quality. Therefore, it is necessary to do more ideas and tests on the form of the gas hood currently used.

[0003] The process of removing SiO2 from the edge of silicon substrate by gas phase is a very important process in the manufacturing process of silicon substrate polishing wafer. The principle is to use the etching effect of HF on the oxide layer to remove the oxide layer on the edge chamfer and chamfer surface. The method is to use vacuum to adsorb the chip on the flat ceramic disk surface; then the gas mask falls to cover the chip, and HF reacts with the oxide layer on the edge of the chip. The EOS width can be adjusted by etching time, number of times and etching temperature.

[0004] Considering that the uniformity of removal will affect the customer's application effect, as a component of the production equipment in the process, the quality of the gas hood directly affects the effect. Improving the uniformity of EOS is a long-term improvement issue. Summary of the invention

[0005] The invention discloses an improved gas hood method for removing SiO2 film at the edge of silicon substrate (EOS process), which improves the uniformity of edge removal and prolongs the service life of heating pad on the gas hood. The newly designed nozzle joint is convenient for disassembly for equipment maintenance, and at the same time achieves the purpose of improving PPH and saving HF reagent. The method comprises the following steps: the interior of the gas hood is improved to be cylindrical before and dome-shaped after the improvement in order to improve the distribution of gas in the gas hood, in order to improve the uniformity of EOS. A depression is added on the back of the gas hood in order to place the heating pad, reduce heat loss and prolong the service life of the heating pad.

[0006] In one embodiment of the present invention, the method improves the interior of the gas hood to a cylindrical design before and a dome design after to improve the distribution of gas in the gas hood, in the hope of improving EOS uniformity.

[0007] In one embodiment of the present invention, the method adds a depression on the back of the gas hood to place the heating pad, reduce heat loss, and extend the life of the heating pad. (Before improvement: sandwich type and the heating pad leaks out. After improvement: embedded type, which can better protect the heating pad).

[0008] In one embodiment of the present invention, the old nozzle of this method is troublesome to install and remove. After improvement: the joint on the nozzle is fixed, and the nozzle is directly screwed on, which is convenient for equipment disassembly and maintenance.

[0009] The value of this invention: The newly designed gas hood can improve the uniformity of edge removal and extend the life of the heating pad on the gas hood. The newly designed nozzle joint is convenient for disassembly of equipment maintenance, while achieving the purpose of improving PPH and saving HF reagents. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 Comparison of the difference before and after the change of the gas mask DETAILED DESCRIPTION

[0011] The present invention is described in detail below with reference to the accompanying drawings.

[0012] The present invention is an improved gas hood method for removing SiO2 film at the edge of silicon substrate (EOS process), the improved gas hood of the method is as follows Figure 1 , the production process of this method:

[0013] 1. After emptying the old HF in the machine, insert a new HF;

[0014] 2. The machine is heated up, including the ceramic plate and the gas hood;

[0015] 3. Wipe the ceramic plate and air hood clean with isopropyl alcohol;

[0016] 4. After the temperature reaches the target value, make the first piece to confirm the corrosion rate and uniformity;

[0017] 5. Start formal production to see the continued stability of the quality of the new gas hoods;

[0018] 6. Batch measure data and then send it to the inspection station to check the yield.

[0019] This method improves the uniformity of edge removal and prolongs the life of the heating pad on the gas hood. The newly designed nozzle joint facilitates the disassembly of the equipment for maintenance, and at the same time achieves the purpose of improving PPH and saving HF reagents; the method is: the interior of the gas hood is improved from a cylindrical design to a dome design to improve the distribution of gas in the gas hood, and it is expected to improve the uniformity of EOS. The concave back of the gas hood is added to place the heating pad, reduce heat loss, and prolong the life of the heating pad. The corrosion rate of the new gas hood is faster when using the same flow rate, which is conducive to saving HF. The quality part has a more concentrated range and less fluctuation.

[0020] It should be understood that the specific embodiments described herein are only used to understand the present invention and are not used to limit the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

Claims

1. An improved gas hood method for removing SiO2 film at the edge of a silicon substrate (EOS process), which improves the uniformity of edge removal and prolongs the life of a heating pad on the gas hood. A newly designed nozzle joint facilitates disassembly for equipment maintenance, while achieving the purpose of improving PPH and saving HF reagents. The method is as follows: the interior of the gas hood is cylindrical before improvement and dome-shaped after improvement in order to improve the distribution of gas in the gas hood, in the hope of improving EOS uniformity. A depression is added on the back of the gas hood in order to place a heating pad, reduce heat loss, and prolong the life of the heating pad.

2. An improved gas mask method for removing SiO2 film at the edge of a silicon substrate (EOS process) as claimed in claim 1, characterized in that: The dome-shaped design of the method is more conducive to the filling of HF gas in the gas hood, so that the gas can be evenly distributed on the edge of the silicon wafer for etching, thereby improving EOS uniformity.

3. An improved gas mask method for removing SiO2 film at the edge of a silicon substrate (EOS process) as claimed in claim 1, characterized in that: The concave design at the top of the method allows the heating pad to be placed inside, which is beneficial to protecting the heating pad and reducing energy loss, thereby extending the life of the heating pad.

4. An improved gas mask method for removing SiO2 film at the edge of a silicon substrate (EOS process) as claimed in claim 1, characterized in that: The connection mode of the newly designed nozzle of the method described becomes an integrated one, which improves the previous fixing mode of multiple screws, facilitates the disassembly when the equipment is repaired or replaced, and saves time.

5. An improved gas mask method for removing SiO2 film at the edge of a silicon substrate (EOS process) as claimed in claim 1, characterized in that: The volume of the newly designed gas mask in the method is smaller than that of the old gas mask, and the gas filling time in the gas mask cavity is shorter, so the ventilation time is shortened, which saves HF in disguise.

6. An improved gas mask method for removing SiO2 film at the edge of a silicon substrate (EOS process) as claimed in claim 1, characterized in that: The method described above keeps the outer dimensions of the gas hood unchanged, and the dome-shaped design makes the upper wall of the gas hood thicker, so in actual use, it needs to be heated in advance to stabilize the temperature before production.

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