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However, although hydroxyethyl cellulose is suitable for improving the hydrophilicity of the wafer, it has the problem of increasing the microscopic surface defects of the wafer due to the difficulty of filtration and easy condensation
Method used
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Embodiment
[0053] Hereinafter, the present invention will be more specifically described by showing examples and comparative examples of the present invention, but the present invention is not limited to these examples and comparative examples.
[0054]
[0055] The fine polishing of the silicon wafer is completed by the fine polishing method of the present invention.
[0056] First, abrasive grains (silica gel with an average primary particle size of 25 nm measured by BET method), ammonia, hydroxyethyl cellulose and pure water were mixed to prepare a polishing agent. In Example 1, the weight average molecular weight of hydroxyethyl cellulose was 500,000. In addition, the weight average molecular weight of hydroxyethyl cellulose was computed as the polyethylene oxide conversion value using the cycle gel permeation chromatography. In addition, at this time D 1 / D 2 The value of 1.86.
[0057] The polishing cloth is used as shown in Figure 5 The polishing cloth E. The polishing cl...
Embodiment 2
[0065] In addition to changing the weight average molecular weight of hydroxyethyl cellulose in the polishing agent to 400,000, and changing D 1 / D 2 Except changing to 1.51, the silicon wafer was polished under the same conditions as in Example 1, and the quality of the polished wafer was evaluated.
[0066] As a result, it can be seen from Table 1 that, while the haze level was good, the haze unevenness (Defect%) was a good value of 3.3%, which was lower than the pass standard of 5.0%. In addition, satisfactory results were also obtained with respect to minute defects.
Embodiment 3
[0068] In addition to changing the weight average molecular weight of hydroxyethyl cellulose in the polishing agent to 700,000, and changing D 1 / D 2 Except changing to 2.28, the silicon wafer was polished under the same conditions as in Example 1, and the quality of the polished wafer was evaluated.
[0069] As a result, as can be seen from Table 1, while the haze level was good, the haze unevenness (Defect %) was a good value of 2.9%, which was lower than the pass standard of 5.0%. In addition, satisfactory results were also obtained with respect to minute defects.
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Abstract
A final polishing method comprising using: a polishing agent which contains colloidal silica, ammonia and hydroxyethyl cellulose, and in which the primary particle diameter of the colloidal silica is 20 nm or more and less than 30 nm, the weight-average molecular weight of hydroxyethyl cellulose is 400,000 or more and not more than 700,000, and the ratio D1 / D2 [wherein D1 represents a particle diameter corresponding to a cumulative volume ratio of 95% of particles present in the polishing agent, and D2 represents a particle diameter corresponding to a cumulative volume ratio of 95% of the colloidal silica in the case of dispersing the colloidal silica in water so as to give the same concentration as the colloidal silica concentration of the polishing agent] is 1.5 or more and not more than 2.5; and a piece of polishing cloth which shows a contact angle of 60 degrees or more, said contact angle being measured 100 seconds after dropping purified water on the polishing cloth that has been seasoned and dried. Thus, provided is a method for final polishing of a silicon wafer whereby a silicon wafer having an excellent haze level as a whole, little haze irregularity in an outer circumferential part and few minute defects can be obtained.
Description
technical field [0001] The invention relates to a fine polishing method for a silicon wafer and a silicon wafer polished by the polishing method. Background technique [0002] Semiconductor wafers represented by silicon wafers, such as Image 6 As shown, a polishing device 601 composed of a flat plate 603 attached with a polishing cloth 602, a polishing agent supply mechanism 604, and a polishing head 606 is used, and the semiconductor wafer W is supported by the polishing head 606, and is supplied from the polishing agent supply mechanism 604. While the polishing compound 605 is applied to the polishing cloth 602 , the surface of the semiconductor wafer W is slidably contacted with the polishing cloth 602 by rotating the flat plate 603 and the polishing head 606 to perform polishing. [0003] In addition, the polishing of semiconductor wafers is mostly carried out by changing the type of polishing cloth or the type of polishing agent for segmental polishing. The initial dou...
Claims
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