Polysilicon resistors, methods for manufacturing the same, and successive approximation register analog-to-digital converter

A method for manufacturing a polysilicon resistor, comprising:

• providing a silicon-on-insulator substrate, wherein the silicon-on-insulator substrate includes a first silicon substrate, a first silicon oxide layer, and a second silicon substrate that are sequentially stacked along a first direction;
• forming an insulating isolation structure on the silicon-on-insulator substrate, wherein the insulating isolation structure extends through the second silicon substrate along the first direction and divides the second silicon substrate into a plurality of substrate isolation areas separated from each other;
• forming a second silicon oxide layer on the silicon-on-insulator substrate, wherein the second silicon oxide layer covers the plurality of substrate isolation areas and the insulating isolation structure;
• and
• forming a polysilicon resistor layer on the second silicon oxide layer, wherein the polysilicon resistor layer includes a plurality of polysilicon resistor blocks separated from each other, the plurality of polysilicon resistor blocks is arranged in one-to-one correspondence with the plurality of substrate isolation areas, and the plurality of polysilicon resistor blocks is connected in series.

A successive approximation register analog-to-digital converter, comprising:

• a resistor voltage-divider unit, wherein a first end of the resistor voltage-divider unit is connected to an input voltage and a second end of the resistor voltage-divider unit is grounded, and the resistor voltage-divider unit includes two polysilicon resistors arranged in series, and a common end of the two polysilicon resistors is configured to output a sampling voltage;
• a bandgap reference unit configured to output a reference voltage;
• and
• a successive approximation register analog-to-digital conversion unit connected to the resistor voltage-divider unit and the bandgap reference unit and configured to receive the sampling voltage and the reference voltage,
• wherein each of the two polysilicon resistors includes:
• a first silicon substrate;
• a first silicon oxide layer disposed on the first silicon substrate;
• a second silicon substrate disposed on the first silicon oxide layer, wherein an insulating isolation structure is provided in the second silicon substrate, and the insulating isolation structure extends through the second silicon substrate and divides the second silicon substrate into a plurality of substrate isolation areas separated from each other;
• a second silicon oxide layer disposed on the second silicon substrate;
• and
• a polysilicon resistor layer disposed on the second silicon oxide layer, wherein the polysilicon resistor layer includes a plurality of polysilicon resistor blocks separated from each other, the plurality of polysilicon resistor blocks is arranged in one-to-one correspondence with the plurality of substrate isolation areas, and the plurality of polysilicon resistor blocks is connected in series.