Search

CN-122028440-A - Method for preparing polysilicon resistor

CN122028440ACN 122028440 ACN122028440 ACN 122028440ACN-122028440-A

Abstract

The invention provides a method for preparing a polysilicon resistor, which comprises the steps of exposing a photoresist layer on the polysilicon layer by adopting a half-tone light modulation mask comprising a light-tight region, a semi-transparent region and a light-transparent region, so that the developed photoresist layer has different thicknesses in different regions to realize the regulation and control of ion implantation doping amounts in different regions, wherein the polysilicon layer after ion implantation comprises a first polysilicon part covered by the photoresist layer with a first thickness, a second polysilicon doping part covered by the photoresist layer with a second thickness and a third polysilicon doping part not covered by the photoresist layer, and a plurality of polysilicon resistors with different resistivities can be obtained after the photoresist layer is removed and heat treatment is carried out. The invention can realize the simultaneous preparation of the polysilicon with different resistance values on the premise of not increasing the production cost, and can unbinding the resistance value of the polysilicon resistor and the ion implantation in the device process, thereby endowing the design end with a larger degree of freedom for calling the polysilicon resistor.

Inventors

  • Request for anonymity

Assignees

  • 青岛澳柯玛云联信息技术有限公司

Dates

Publication Date
20260512
Application Date
20241108

Claims (10)

  1. 1. A method of making a polysilicon resistor comprising the steps of: providing a semiconductor substrate, and forming a polysilicon layer on the semiconductor substrate; forming a photoresist layer on the polysilicon layer; Providing a half-tone light modulation cover comprising an opaque region, a semi-transparent region and a transparent region, exposing the photoresist layer based on the half-tone light modulation cover, wherein the photoresist layer exposed by the opaque region has a first thickness after development, the photoresist layer exposed by the semi-transparent region has a second thickness after development, the photoresist layer exposed by the transparent region is removed after development, and the second thickness is smaller than the first thickness; Performing ion implantation, wherein the polysilicon layer after the ion implantation comprises a first polysilicon part covered by the photoresist layer with the first thickness, a second polysilicon doping part covered by the photoresist layer with the second thickness and a third polysilicon doping part not covered by the photoresist layer, and the doping concentration of the second polysilicon doping part is lower than that of the third polysilicon doping part; Removing the photoresist layer; Heat treatment is performed to obtain a first polysilicon resistor having a first resistivity, a second polysilicon resistor having a second resistivity, and a third polysilicon resistor having a third resistivity.
  2. 2. The method of manufacturing a polysilicon resistor of claim 1, wherein at least two of the first polysilicon resistor, the second polysilicon resistor, and the third polysilicon resistor are in contact with each other.
  3. 3. The method of manufacturing a polysilicon resistor according to claim 1, wherein the polysilicon layer includes the first polysilicon portion, the second polysilicon portion, and the third polysilicon portion disposed at intervals, the first polysilicon portion being converted to the first polysilicon resistor, the second polysilicon portion being converted to the second polysilicon resistor, the third polysilicon portion being converted to the third polysilicon resistor, the first polysilicon resistor, the second polysilicon resistor, and the third polysilicon resistor being disposed at intervals after the ion implantation and the heat treatment.
  4. 4. The method of manufacturing a polysilicon resistor of claim 1, wherein the semiconductor substrate comprises a device region and a resistor region on one side of the device region, and the first polysilicon resistor, the second polysilicon resistor, and the third polysilicon resistor are all located in the resistor region.
  5. 5. The method of manufacturing a polysilicon resistor according to claim 4, wherein a partial region of the light-transmitting region is located above the device region when the photoresist layer is exposed based on the halftone mask.
  6. 6. The method of manufacturing a polysilicon resistor as set forth in claim 5, wherein the polysilicon layer comprises a polysilicon gate layer in the device region, and the ion implantation is performed to obtain the second polysilicon doped portion and the third polysilicon doped portion, and to obtain source and drain regions in the semiconductor substrate in the device region on both sides of the polysilicon gate layer.
  7. 7. The method of manufacturing a polysilicon resistor of claim 1, wherein the ion implantation comprises P-type ion implantation or N-type ion implantation.
  8. 8. The method of manufacturing a polysilicon resistor according to claim 1, wherein the halftone mask comprises a light-transmitting substrate layer, an opaque layer and a semi-transparent layer are sequentially disposed on the surface of the light-transmitting substrate layer in the opaque region from bottom to top, a semi-transparent layer is disposed on the surface of the light-transmitting substrate layer in the semi-transparent region, a covering layer is not disposed on the surface of the light-transmitting substrate layer in the light-transmitting region, and the light transmittance of the semi-transparent layer is smaller than that of the light-transmitting substrate layer and larger than that of the opaque layer.
  9. 9. The method of preparing a polysilicon resistor of claim 8, wherein the forming of the halftone mask comprises the steps of: Forming the light-tight layer on the surface of the light-permeable substrate; patterning the opaque layer to expose the semi-transparent region and the transparent substrate surface of the transparent region; forming a semi-transparent layer, wherein the semi-transparent layer covers the non-transparent layer and covers the exposed surface of the transparent substrate; patterning the semi-transparent layer to expose the transparent substrate surface of the transparent region.
  10. 10. The method of manufacturing a polysilicon resistor of claim 9 wherein the opaque layer comprises a Cr layer.

Description

Method for preparing polysilicon resistor Technical Field The invention belongs to the technical field of semiconductors, and relates to a method for preparing a polysilicon resistor. Background Polysilicon resistors are one of the most used devices in semiconductor integrated circuit design, and are commonly used in circuits as voltage dividers, current dividers, and load resistors. In semiconductor manufacturing processes, polysilicon resistors, such as the commonly found N-type heavily doped (n+ doped) polysilicon resistors and P-type heavily doped (p+ doped) polysilicon resistors, are typically prepared by ion implantation of polysilicon followed by annealing. In the manufacturing process of a semiconductor integrated circuit, the situation that the doped polysilicon resistor cannot meet the requirements of a design party under the condition that the performance of a device is in place often occurs, and if the resistance value of the polysilicon resistor is adjusted by adjusting the doping concentration of N+ or P+, the behavior of the device is adversely affected. In addition, in order to meet the requirement of the polysilicon resistor with higher resistance of the design side, an additional mask is usually added to obtain the polysilicon resistor by separate ion implantation, however, the additional photolithography process increases the production cost of the wafer, which complicates the production process. Therefore, it is necessary to provide a new method for preparing the polysilicon resistor, which can unbind the resistance value of the doped polysilicon resistor and the device performance while maintaining the original production cost, and release the calling restriction of the design party on the polysilicon resistor to a certain extent. It should be noted that the foregoing description of the background art is only for the purpose of providing a clear and complete description of the technical solution of the present application and is presented for the convenience of understanding by those skilled in the art. The above-described solutions are not considered to be known to the person skilled in the art simply because they are set forth in the background of the application section. Disclosure of Invention In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a method for preparing a polysilicon resistor, which is used for solving the problems that the existing preparation method of the polysilicon resistor is easy to affect the performance of the device and has high cost. To achieve the above and other related objects, the present invention provides a method for preparing a polysilicon resistor, comprising the steps of: providing a semiconductor substrate, and forming a polysilicon layer on the semiconductor substrate; forming a photoresist layer on the polysilicon layer; Providing a half-tone light modulation cover comprising an opaque region, a semi-transparent region and a transparent region, exposing the photoresist layer based on the half-tone light modulation cover, wherein the photoresist layer exposed by the opaque region has a first thickness after development, the photoresist layer exposed by the semi-transparent region has a second thickness after development, the photoresist layer exposed by the transparent region is removed after development, and the second thickness is smaller than the first thickness; Performing ion implantation, wherein the polysilicon layer after the ion implantation comprises a first polysilicon part covered by the photoresist layer with the first thickness, a second polysilicon doping part covered by the photoresist layer with the second thickness and a third polysilicon doping part not covered by the photoresist layer, and the doping concentration of the second polysilicon doping part is lower than that of the third polysilicon doping part; Removing the photoresist layer; Heat treatment is performed to obtain a first polysilicon resistor having a first resistivity, a second polysilicon resistor having a second resistivity, and a third polysilicon resistor having a third resistivity. Optionally, at least two of the first polysilicon resistor, the second polysilicon resistor and the third polysilicon resistor are in contact with each other. Optionally, the polysilicon layer includes a first polysilicon portion, a second polysilicon portion and a third polysilicon portion that are disposed at intervals, after the ion implantation and the heat treatment, the first polysilicon portion is converted into the first polysilicon resistor, the second polysilicon portion is converted into the second polysilicon resistor, the third polysilicon portion is converted into the third polysilicon resistor, and the first polysilicon resistor, the second polysilicon resistor and the third polysilicon resistor are disposed at intervals. Optionally, the semiconductor substrate includes a device region and a resistor region loca