A kind of varactor diode die and its preparation method

Abstract

The invention provides a variode core and a preparation method thereof. The variode core is provided with two passivation layers thereon, wherein the first passivation layer is located between a PN junction and a silver platform electrode but does not completely cut off the contact between the PN junction and the silver platform electrode, and the second passivation layer covers the top layer of the variode tube. The invention has the beneficial effects that normal-temperature reverse breakdown voltage drift creep is greatly improved; the normal-temperature reverse leakage current value of a device prepared in accordance with the invention is reduced, and performance parameters are improved; when the device is tested under the high-temperature state after reversal biasing for 48h under the high temperature of 150 DEG C, the reverse leakage current value and the discreteness are reduced, with the high-temperature leakage current satisfying the good standard requirement of being less than 30nA; when the device is tested again under the normal temperature after reversal biasing for 48h under the high temperature of 150 DEG C, the variations of the reverse breakdown voltage and the initial value before reverse biasing are reduced, the percentages of the reverse breakdown voltage variation and the initial value are decreased, and the high-temperature performance parameters of the device are improved.

Description

technical field [0001] The invention belongs to the technical field of semiconductors, and in particular relates to a varactor diode tube core and a preparation method thereof. Background technique [0002] Varactor Diodes, also known as "variable reactance diodes", are semiconductor devices made of the principle of variable capacitance between PN junctions, and are used as variable capacitors in tuning, frequency modulation and other circuits. The utility model has the advantages of small size, high reliability and good stability, and is convenient for automation. Varactor diodes are reverse-biased diodes. Changing the reverse bias voltage on its PN junction can change the capacitance of the PN junction. The higher the reverse bias voltage, the smaller the junction capacitance, and the relationship between reverse bias voltage and junction capacitance is nonlinear. [0003] Varactor diodes are used in automatic frequency control (AFC), scanning oscillation, frequency modu...

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Problems solved by technology

[0014] Varactor diodes will always be contaminated by surface impurities during the production process of silicon wafers. Usually, a large amount of potassium and sodium ions contaminate the surface of silicon wafers. Due to the thermal growth of SiO 2 It is an amorphous glassy network structure. Large ions such as potassium and sodium will exist in the network structure in an intermittent manner, and the network structure will be deformed, showing porosity, and impurities will be in the SiO 2 Migration and diffusion in the voids, resulting in device instability, and the existing varactor diodes mostly use a single passivation layer structure, and the composition of phosphosilicate glass (PSG for short) in the passivation layer is not appropriate, so it cannot be effectively Potassium and sodium ions can be firmly fixed; when the front silver electrode is electroplated and the glass seal is sintered, there will be a large amount of potassium and sodium ions that will contaminate the chip and directly cause damage to the surface of the die, resulting in poor performance at room temperature and high temperature. Stablize

[0015] The existing varactor diode manufacturing process does not form the second passivation layer through the PECVD process after the silver plated electrode, so there are two problems in the existing process, one cannot effectively adsorb and fix the passivation layer after the primary passivation through the PECVD process. Second, it cannot effectively fix the potassium and sodium ions overflowing during glass packaging, which will affect the yield and electrical parameters, especially the high temperature performance of the product

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