Polycrystalline silicon resistor, manufacturing method thereof and successive approximation analog-to-digital converter

Abstract

The invention provides a polycrystalline silicon resistor, a manufacturing method thereof and a successive approximation type analog-to-digital converter. When the polycrystalline silicon resistor is formed, an upper silicon substrate layer of a silicon-on-insulator substrate is divided into insulated and isolated substrate isolation regions by utilizing the characteristics of a silicon-on-insulator process; a silicon oxide layer and a polycrystalline silicon resistance layer are sequentially formed on an upper silicon substrate layer, the polycrystalline silicon resistance layer is divided into a plurality of polycrystalline silicon resistance blocks, and the polycrystalline silicon resistance blocks are arranged on a plurality of substrate isolation areas in a one-to-one correspondence mode, so that the potential of the substrate isolation areas tightly follows the potential of the polycrystalline silicon resistance blocks. A strong electric field cannot be formed between the polycrystalline silicon resistor block and a substrate isolation region below the polycrystalline silicon resistor block, so that a carrier edge gathering effect on the polycrystalline silicon resistor is eliminated; when the polycrystalline silicon resistor is applied to a front-end resistance voltage-dividing network of the successive approximation type analog-to-digital converter, the linearity of the resistance voltage-dividing network can be effectively improved, and the integral nonlinearity of the successive approximation type analog-to-digital converter is reduced.

Description

technical field [0001] The invention relates to the technical field of integrated circuits, in particular to a polysilicon resistor, a manufacturing method thereof, and a successive approximation analog-to-digital converter. Background technique [0002] Industrial successive approximation analog-to-digital converters (SAR ADCs) are often required to deal with voltage signal ranges of -10V to +10V, or even wider signal ranges. This requires the input signal range of the SAR ADC to reach -10V ~ +10V, but the reference voltage generated by the general integrated bandgap reference circuit is 1.25V or 2.5V, and most industrial SAR ADCs use a reference voltage of 2.5V, which is The input range of the SAR ADC signal is limited to 0-2.5V. In order to solve this problem, a resistor divider network is generally integrated in the front end of the SAR ADC, so that the signal processing range of the SAR ADC can reach ±10V. Such as figure 1 As shown, it is a typical industrial integra...

AI Technical Summary

Problems solved by technology

The inconsistency of the resistivity of the polysilicon resistive layer at the high-voltage end and the low-voltage end will cause very serious nonlinearity

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