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Wafer blackening method, blackened wafer, and surface acoustic wave filter

A wafer and blackening technology, applied in chemical instruments and methods, post-processing, crystal growth, etc., can solve the problems affecting the blackening uniformity, chromaticity and transmittance of piezoelectric wafers, and the radial gradient of thermal field is difficult to uniformly amplify. If the thermal field gradient is too large or too small, the effects of improving the blackening uniformity DE value and chromaticity L value, improving the blackening yield and improving the transmittance can be achieved.

Pending Publication Date: 2021-08-17
FUJIAN JING AN OPTOELECTRONICS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] Existing piezoelectric wafers are obtained by using traditional piezoelectric wafer blackening methods, which are prone to problems such as poor blackening uniformity, poor chromaticity, and high transmittance, and are only suitable for piezoelectric wafers below 4 inches
If the traditional piezoelectric wafer blackening method is used to produce large-sized piezoelectric wafers, since large-sized piezoelectric wafers require a larger thermal field gradient, and the radial gradient of the thermal field is difficult to amplify uniformly, it is easy to appear a certain The thermal field gradient of the position is too large or too small, which affects the blackening uniformity, chromaticity and transmittance of the piezoelectric wafer

Method used

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  • Wafer blackening method, blackened wafer, and surface acoustic wave filter
  • Wafer blackening method, blackened wafer, and surface acoustic wave filter
  • Wafer blackening method, blackened wafer, and surface acoustic wave filter

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0076] Select a 4-inch wafer and a 6-inch wafer, and blacken the 4-inch wafer and the 6-inch wafer respectively. The blackening treatment is specifically: arranging the 6-inch wafer (or 4-inch wafer) and the reducing medium in a cross stack; after the 6-inch wafer (or 4-inch wafer) is arranged, the 6-inch wafer (or 4-inch wafer) is placed on the Blacken the furnace platform, and slowly raise the temperature in the furnace to 450°C, and introduce hydrogen gas during the heating process to isolate oxygen and participate in the reduction reaction. After the temperature rises to 450°C, keep the temperature for 3 hours, turn off the heater in the furnace, and cool down naturally to room temperature, then grind, thin, and polish to obtain a blackened 6-inch wafer (or a 4-inch wafer).

[0077] see image 3 , using a spectrophotometer to measure the 4-inch wafer and 6-inch wafer respectively: the chromaticity L value of the 4-inch wafer is 50.2, and the blackening uniformity DE value...

Embodiment 2

[0080] On the basis of the technical scheme provided in embodiment 1, after the blackening treatment of the 6-inch wafer is completed, the 6-inch wafer is placed under the ultraviolet light source and irradiated for a predetermined time, and the distance between the 6-inch wafer and the ultraviolet light source is 50cm. The wavelength of the ultraviolet light source is 315-400nm, and the ultraviolet light source irradiates a 6-inch wafer for 1 hour.

[0081] see image 3 , using a spectrophotometer to measure a 6-inch wafer after being irradiated by an ultraviolet light source for 1 hour: the chromaticity L value is 48.9, and the blackening uniformity DE value is 0.45. It can be seen that compared with the 6-inch wafer in Example 1, the chromaticity L value and the blackening uniformity DE value of the 6-inch wafer after ultraviolet light irradiation are all significantly reduced, which shows that the use of ultraviolet light to irradiate the wafer can effectively improve Th...

Embodiment 3

[0084] Place the 6-inch wafer under the ultraviolet light source for a predetermined time, and the distance between the 6-inch wafer and the ultraviolet light source is 50 cm. The wavelength of the ultraviolet light source is 315-400nm, and the ultraviolet light source irradiates a 6-inch wafer for 1 hour.

[0085] After irradiating the wafer with ultraviolet light for 1 hour, according to the technical scheme in Example 1, the 6-inch wafer after being irradiated with ultraviolet light for 1 hour was blackened.

[0086] see image 3 , using a spectrophotometer to measure a 6-inch wafer: the chromaticity L value is 49.2, and the blackening uniformity DE value is 0.48. It can be seen that compared with the 6-inch wafers in Embodiment 1 and Embodiment 2, the chromaticity L value and the blackening uniformity DE value of the 6-inch wafer in the present embodiment are all substantially close to the chromaticity L in Embodiment 2. value and blackening uniformity DE value, and are ...

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Abstract

The invention discloses a wafer blackening method, a blackened wafer and a surface acoustic wave filter, and relates to the related technical field of semiconductors. The wafer blackening method comprises the following steps: carrying out reductive treatment on a wafer; irradiating the wafer for a preset time by using ultraviolet light, wherein the blackening uniformity DE value of the wafer is between 0.3 and 0.6, and the chromaticity L value is between 48 and 54. In the application, the ultraviolet light is utilized to assist the blackening process of the wafer, so that the blackening uniformity DE value and the chromaticity L value of the wafer can be effectively improved, the transmissivity of the wafer is further improved, and the blackening yield of the wafer is improved. The sequence of carrying out reductive treatment on the wafer and irradiating the wafer with the ultraviolet light for the preset time can be interchanged, and both the two methods can improve the yield of wafer blackening.

Description

technical field [0001] The present application relates to the technical field related to semiconductors, in particular to a method for blackening a wafer, a blackened wafer and a surface acoustic wave filter. Background technique [0002] Piezoelectric wafers are the main material for making surface acoustic wave filters. Due to the high transmittance, large pyroelectric coefficient and high resistivity of piezoelectric wafers, a large amount of static charges are easy to accumulate on the surface of piezoelectric wafers, and these static charges will be deposited in the filter. Spontaneous release between the interdigital electrodes or between the piezoelectric wafers can lead to problems such as cracking of the piezoelectric wafers or burning of the interdigital electrodes. Therefore, in order to solve the above-mentioned problems, it is necessary to perform a blackening process (reduction treatment) on the piezoelectric wafer to reduce its resistivity and transmittance, s...

Claims

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Application Information

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IPC IPC(8): C30B33/00C30B33/02H03H9/64
CPCC30B33/00C30B33/02H03H9/64H03H9/02559H03H9/02921H03H3/08H03H9/145H03H9/25
Inventor 刘艺霖林仲和林彦甫黄世维枋明辉杨胜裕
Owner FUJIAN JING AN OPTOELECTRONICS CO LTD
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