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KR-102964177-B1 - Semiconductor wafer cleaning method

KR102964177B1KR 102964177 B1KR102964177 B1KR 102964177B1KR-102964177-B1

Abstract

The present invention relates to a method for cleaning the side of a semiconductor wafer, having the following steps in a given order: (1) a first cleaning step of cleaning with ozone water and a subsequent rinsing step with purified water; (2) a second cleaning step comprising a treatment step with ozone water followed by a treatment step with an HF-containing liquid, the second cleaning step may be repeated several times; (3) a third cleaning step of cleaning with ozone water and a subsequent rinsing step with purified water; and (4) a drying step, in which the side of the semiconductor wafer is dried. The present invention is characterized in that a pre-cleaning step with water is performed immediately before the first cleaning step, so that the side of the semiconductor wafer is still wet when the first cleaning step is initiated.

Inventors

  • 브록, 데미안
  • 쿠엔슈테터 알베르트

Assignees

  • 실트로닉 아게

Dates

Publication Date
20260512
Application Date
20221028
Priority Date
20211112

Claims (6)

  1. As a process for cleaning the surface of a semiconductor wafer, (1) A first cleaning step using ozonized water and a subsequent rinsing step using purified water, and (2) A second cleaning step comprising a treatment step with ozone water followed by a treatment step with an HF-containing liquid - said second cleaning step may be repeated several times - and, (3) A third cleaning step with ozone water and a subsequent rinsing step with purified water, and (4) A drying step in which the surface of the semiconductor wafer is dried Includes in order, The above process includes a pre-cleaning step with water immediately prior to the first cleaning step, wherein the surface of the semiconductor wafer is still wet while the first cleaning step is initiated, and A process in which, during the above pre-cleaning step, ozone water is added such that the fraction of the ozone water increases from the start of the above pre-cleaning step to the end of the above pre-cleaning step, and the period during which the fraction is less than 5% is greater than 1 second and less than 10 seconds.
  2. In paragraph 1, The above pre-cleaning step is a process that lasts for at least 1 second and no more than 15 seconds.
  3. In paragraph 1 or 2, A process in which the surface of the semiconductor wafer is horizontally aligned and rotated at a speed greater than 500 rpm and less than 1000 rpm during the pre-cleaning step.
  4. In paragraph 1 or 2, A process in which water is applied using a nozzle in the above-mentioned pre-cleaning step, wherein the flow velocity of the nozzle is between 0.5 m/s and 2 m/s, and the associated flow rate is between 0.5 l/min and 1.5 l/min.
  5. In paragraph 4, A process in which the nozzle is aligned such that the flow direction of the nozzle forms an angle α greater than 30° and less than 70° with the surface of the semiconductor wafer.
  6. delete

Description

Semiconductor wafer cleaning method The subject of the present invention is a process for cleaning a semiconductor wafer. For example, a semiconductor wafer, which serves as a substrate for the manufacture of microelectronic components and is typically a silicon wafer, is cleaned using a wet chemical process after polishing and a coating or heat treatment step (“annealing”) (e.g., by epitaxial deposition) and/or before a high-temperature operation step. The purpose of cleaning is to remove as much as possible contamination of the semiconductor wafer by metals, such as copper, or by organic materials, and to also remove as much as possible particles attached to the wafer surface, because such contamination leads to problems such as the non-uniform growth of gate oxides or the non-uniform deposition of polysilicon gates in the subsequent manufacture of components. A process employed in this context comprises a single wafer cleaning process, wherein a semiconductor wafer is rapidly rotated around its central axis, simultaneously cleaned first with one or more liquids, then rinsed with deionized water, and dried. The liquid is applied to the rotating semiconductor wafer and accelerated toward the wafer edge by centrifugal force, causing the liquid to flow outward, leaving a thin film that generally covers the entire surface of the wafer. During subsequent drying by further rotation of the semiconductor wafer, the entire liquid film flows outward, for example, by the addition of vapor (e.g., isopropanol) that reduces the surface tension of the liquid film. Such a process is described, for example, in US 2004/0 103 915 A1 and EP 0 905 747 A1. Specification US 2014/048 100 A1 discloses a process for cleaning a semiconductor wafer using the following steps: (1) A first cleaning step using ozonized water and a subsequent rinsing step using purified water, and (2) A second cleaning step comprising a treatment step with ozone water followed by a treatment step with an HF-containing liquid - said second cleaning step may be repeated several times - and, (3) A third cleaning step with ozone water and a subsequent rinsing step with purified water, and (4) Drying step - The side of the semiconductor wafer is dried -. While testing this process, the inventor discovered that defect patterns measurable by LLS measurements can occur on the wafer. These defects clearly occur preferentially in the center of the substrate and can adversely affect the behavior of the semiconductor wafer during component fabrication operations. Therefore, the objective of the present invention is to provide a process that does not have these defects, or at least minimizes the possibility of these defects occurring. The objective is achieved by the process described in the claim scope. FIG. 1 illustrates, in the form of an example, a radial defect density that can be measured after one semiconductor wafer is processed by a process (A) known in the prior art and another semiconductor wafer is cleaned by the process (B) of the present invention. It is evident that the process (B) of the present invention can prevent defects in the center of the semiconductor wafer more effectively than the process (A) of the prior art.List of abbreviationsDIW Deionized Water. Ozone water containing 15 to 20 ppm of ozone ( O3 ) dissolved in O3W deionized water. SC1 “Standard Clean 1” containing 0.3 % tetramethylammonium hydroxide (TMAH, [N( CH3 ) 4 ]OH) and 0.7% hydrogen peroxide ( H2O2 ) in deionized water 0.5% to 1% hydrogen fluoride (HF) dissolved in HF deionized water Drying operation performed in a 100% nitrogen atmosphere ( N₂ ) While testing a conventional process for cleaning semiconductor wafers using a single wafer cleaning device, the inventor determined possible defect patterns on the wafer that are measurable by LLS measurement. These defect patterns can be visualized, for example, by light scattering measurements using the KLA-Tencor instrument Surfscan SP1 MX, and are therefore referred to as localized light scattering defects. WO 2005101483 A1 discloses a technique for measuring scattered light of an epitaxially coated semiconductor wafer. As shown in Fig. 1, these defects occur preferentially in the center of the semiconductor wafer. They can have an adverse effect on the behavior of the semiconductor wafer affected during the component manufacturing process. In an attempt to eliminate the occurrence of these defects, the inventor has found that it is useful and therefore desirable to first perform a first cleaning step of cleaning with ozone water and a subsequent rinsing step with purified water, then perform a second cleaning step including a treatment step with ozone water and a treatment step with an HF-containing liquid, which may be repeated several times, then perform a third cleaning step of cleaning with ozone water and a subsequent rinsing step with purified water, and then perform a drying step in which the sides of the semiconductor wafer