# US 11,307,245 B2 · Method for measuring an electric property of a test sample > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,307,245 B2 - Document ID: US11307245B2 - Status: Granted - Kind: B2 - Application number: 16/753,607 - Filed: 2020-03-18 - Published: 2021-07-29 - Granted: 2022-04-19 - Earliest claimed: 2019-04-04 - Assignees: KLA Corporation - Applicants: Kla Corporation - Inventors: Alberto Cagliani; Frederik Westergaard Østerberg; Chia-Hung Wei - Web page: https://patentgrep.com/patent/US11307245B2 ## CPC - G01R 31/2884: {using dedicated test connectors, test elements or test circuits on the IC under test (G01R31/2855 takes precedence)} - G01R 1/0491: {for testing integrated circuits on wafers, e.g. wafer-level test cartridge} - G01R 31/2648: {Characterising semiconductor materials (testing of materials or semi-finished products G01R31/2831; testing during manufacture H10P74/00)} - G11C 11/1677: {Verifying circuits or methods} - G11C 29/50: Marginal testing, e.g. race, voltage or current testing - G11C 29/50008: {of impedance} - H10B 61/00: Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices - H10N 50/80: Constructional details - G01R 1/06733: {Geometry aspects (G01R1/06727 takes precedence)} - G01R 31/2894: {Aspects of quality control [QC] (G01R31/31718 takes precedence; program control for QC G05B19/41875)} - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - G11C: STATIC STORES (semiconductor memory devices H10B) - H10B: ELECTRONIC MEMORY DEVICES - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR ## Abstract The method may be used for measuring an electric property of a magnetic tunnel junction used in an embedded MRAM memory for example. The method uses a multi point probe with a plurality of probe tips for contacting a designated area of the test sample, which is electrically insulated from the part of the test sample which is to be tested. Electrically connections are placed underneath the magnetic tunnel junction and goes to the designated area. ## Claims ### Claim 1 A method for measuring an electrical property of a multilayer test sample such as a magnetic tunnel junction, said method comprising: providing said multilayer test sample having a stack including at least a first layer and a second layer, said stack being above an electrically insulating layer, providing a first test sample terminal above said electrically insulating layer for a first connection with a measurement circuit, providing a second test sample terminal above said electrically insulating layer for a second connection with said measurement circuit, said first test sample terminal, said second test sample terminal, and said stack being electrically insulated from each other, providing a first electrically conductive path embedded in said electrically insulating layer, said first electrically conductive path electrically interconnecting said first test sample terminal and said stack, and providing a second electrically conductive path embedded in the electrically insulated layer, said second electrically conductive path electrically interconnecting said second test sample terminal and said stack, said method further comprising: providing said measuring circuit including a first measuring terminal and a second measuring terminal, contacting said first measuring terminal with said first test sample terminal, contacting said second measuring terminal with said second test sample terminal, and measuring said electric property of said stack by means of said measuring circuit. ### Claim 2 (depends on 1) The method according to claim 1, said multilayer test sample being a semiconductor wafer for magnetoresistive random-access memory. ### Claim 3 (depends on 1) The method according to claim 1, said stack constituting a magnetic tunnel junction. ### Claim 4 (depends on 1) The method according to claim 1, said first layer being a ferromagnetic sheet. ### Claim 5 (depends on 1) The method according to claim 1, said second layer being a ferromagnetic sheet. ### Claim 6 (depends on 1) The method according to claim 1, said stack including a middle layer sandwiched between said first layer and said second layer. ### Claim 7 (depends on 6) The method according to claim 6, said middle layer being an electric insulator for tunnelling electrons between said first layer and said second layer. ### Claim 8 (depends on 1) The method according to claim 1, a first island of said test sample having at least three layers. ### Claim 9 (depends on 8) The method according to claim 8, a second island of said test sample having at least three layers. ### Claim 10 (depends on 1) The method according to claim 1, said first electrically conductive path extending planarly in said electrically insulating layer. ### Claim 11 (depends on 1) The method according to claim 1, comprising providing a first via between said first test sample and said first electrically conductive path. ### Claim 12 (depends on 11) The method according to claim 11, comprising providing a second via between said stack and said first electrically conductive path. ### Claim 13 (depends on 1) The method according to claim 1, comprising providing a test probe including a first probe tip of said first measuring terminal and a second probe tip of said second measuring terminal, contacting said first probe tip with said first test sample terminal, and contacting said second probe tip with said second test sample terminal. ### Claim 14 A multilayer test sample for embedded measuring of an electrical property of said multilayer test sample, said multilayer test sample comprising: a stack including at least a first layer and a second layer, said stack being above an electrically insulating layer, a first test sample terminal above said electrically insulating layer for a first connection with a measurement circuit, a second test sample terminal above said electrically insulating layer for a second connection with said measurement circuit, said first test sample terminal, said second test sample terminal, and said stack being electrically insulated from each other, said multilayer test sample further comprising: a first electrically conductive path embedded in the electrically insulated layer, said first electrically conductive path electrically interconnecting said first test sample terminal and said stack, and a second electrically conductive path embedded in the electrically insulated layer, said second electrically conductive path interconnecting said second test sample terminal and said stack such that said first electrically conductive path and said second electrically conductive path together with said stack form a circuit between said first test sample terminal and said second test sample terminal for measuring said electrically property.