# US 5,705,422 A · Method for forming well of semiconductor device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,705,422 A - Document ID: US5705422A - Status: Granted - Kind: A - Application number: 08/773,594 - Filed: 1996-12-27 - Granted: 1998-01-06 - Earliest claimed: 1995-12-28 - Assignees: LG Semicon Co., Ltd. - Inventors: Hyeok-Jae L'Yee - Web page: https://patentgrep.com/patent/US5705422A ## CPC - H10B 12/01: {Manufacture or treatment} - H10B 12/30: {DRAM devices comprising one-transistor - one-capacitor [1T-1C] memory cells} - H10P 30/22: using masks - H10B: ELECTRONIC MEMORY DEVICES - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 ## Abstract A method for forming a well of a semiconductor device sequentially forms a buffer film, an oxidizable film, and an oxidation-blocking film on a periphery area of a semiconductor substrate. A predetermined part of the oxidation-blocking film is etched to partially expose a surface of the oxidizable film and a thermal oxidation is performed to form a field oxide film on a region of the periphery area where the oxidizable film is exposed and on a cell area where the substrate is exposed. The oxidation-blocking film, the oxidizable film, and the buffer film are removed. Impurity ions of a first conductivity type are implanted using high energy. Impurity ions of a second conductivity type are implanted using low energy by using the field oxide film as a mask. The field oxide film is removed and a diffusion is performed to form wells of the first and second conductivity types. ## Claims ### Claim 1 A method for forming a well of a semiconductor device, the method comprising the steps of: sequentially forming a buffer film, an oxidizable film, and an oxidation-blocking film on a periphery area of a semiconductor substrate; etching a portion of the oxidation-blocking film to partially expose a surface of the oxidizable film; forming a field oxide film on a region of the periphery area where the oxidizable film is exposed and on a cell area where the substrate is exposed; removing the oxidation-blocking film, the oxidizable film, and the buffer film; implanting impurity ions of a first conductivity type with a high energy; implanting impurity ions of a second conductivity type with a low energy by using the field oxide film as a mask; removing the field oxide film; and forming a first conductivity type well and a second conductivity type well through diffusion. ### Claim 2 (depends on 1) The method as claimed in claim 1, wherein the step of forming the buffer film forms the buffer film to a thickness in a range of approximately 50 .ANG. to 300 .ANG.. ### Claim 3 (depends on 1) The method as claimed in claim 1, wherein the impurity ions of the first conductivity type is implanted using an energy in a range of approximately 2 MeV to 4 MeV. ### Claim 4 (depends on 1) The method as claimed in claim 1, wherein the impurity ions of the second conductivity type is implanted using an energy in a range of approximately 100 keV to 200 keV. ### Claim 5 (depends on 1) The method as claimed in claim 1, wherein the oxidizable film includes a polycrystalline silicon film. ### Claim 6 (depends on 1) The method as claimed in claim 1, wherein the step of forming the first conductivity type well includes diffusing a P-type impurity. ### Claim 7 (depends on 1) The method as claimed in claim 1, wherein the step of forming the second conductivity type well includes diffusing an N-type impurity. ### Claim 8 A method for forming a well of a semiconductor device, the method comprising the steps of: sequentially forming a buffer film, an oxidizable film, and an oxidation-blocking film on a semiconductor substrate; defining a cell area and a periphery area on the semiconductor substrate; selectively removing the oxidation-blocking film to expose a portion of the oxidizable film; forming a field oxide film on the exposed portion of the oxidizable film and on the cell area; removing the oxidation-blocking film, the oxidizable film, and the buffer film; implanting an impurity of a first conductivity type; implanting an impurity of a second conductivity type by using the field oxide film as a mask; removing the field oxide film; and forming a first conductivity type well and a second conductivity type well through diffusion. ### Claim 9 (depends on 8) The method as claimed in claim 8, wherein the step of forming the first conductivity type well includes forming the first conductivity type well below the second conductivity type well. ### Claim 10 (depends on 8) The method as claimed in claim 8, wherein the buffer film is formed to a thickness in a range of approximately 50 .ANG. to 300 .ANG.. ### Claim 11 (depends on 8) The method as claimed in claim 8, wherein the buffer film includes an oxide film. ### Claim 12 (depends on 8) The method as claimed in claim 8, wherein the oxidizable film includes a polycrystalline silicon film. ### Claim 13 (depends on 8) The method as claimed in claim 8, wherein the oxidation-block film includes a nitride film. ### Claim 14 (depends on 8) The method as claimed in claim 8, wherein the step of selectively removing the oxidation-blocking film includes the steps of: forming a patterned photoresist film on the oxidation-blocking film; and etching the oxidation-blocking film by using the patterned photoresist film as a mask to expose the oxidizable film. ### Claim 15 (depends on 8) The method as claimed in claim 8, wherein the field oxide film is formed with a thickness in a range of approximately 10000 .ANG.. ### Claim 16 (depends on 8) The method as claimed in claim 8, wherein the step of implanting the impurity of the first conductivity type is performed using an energy in a range of approximately 2 MeV to 4 MeV. ### Claim 17 (depends on 8) The method as claimed in claim 8, wherein the step of implanting the impurity of the second conductivity type is performed using an energy in a range of approximately 100 keV to 200 keV. ### Claim 18 (depends on 8) The method as claimed in claim 8, wherein the first conductivity type impurity includes a P-type impurity. ### Claim 19 (depends on 8) The method as claimed in claim 8, wherein the second conductivity type impurity includes an N-type impurity. ### Claim 20 (depends on 8) The method as claimed in claim 8, wherein the step of defining the cell area and the periphery area includes the steps of: forming a photoresist film on the oxidation blocking film; patterning the photoresist film to define the cell area and the periphery area; and partially removing the oxidation blocking film, the oxidation film, and the buffer film using the patterned photoresist film as a mask. ### Claim 21 (depends on 8) The method as claimed in claim 8, wherein the step of forming the field oxide film includes the step of performing a thermal oxidation.